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Sample records for submerged arc fluxes

  1. Study on mechanical and microstructure behavior of submerged arc welding flux using red mud

    Science.gov (United States)

    Dewangan, Rishi; Pandey, Pankaj K.; Upadhyay, Renu

    2018-05-01

    This paper emphasis on utilization of Red Mud for preparing submerged arc welding flux and study its mechanical and microstructure behavior. Among the six fluxes prepared in the laboratory, Flux no. 1 (basicity 1.106) found to be best due to its running performance, micro hardness and Brinell hardness. The hardness value (HV) of the fluxes was varying from 165.70 to 217.15 at a load of 1000gm respectively. From the micrograph of welded metal, acicular ferrite found to be optimum which helps in increasing the ductility and hardness of the welded material.

  2. The effect of flux on properties of weld in submerged arc welding with filler metal

    International Nuclear Information System (INIS)

    Fattahpour, Iran.

    1984-01-01

    In the submerged-arc welding, the electrode wire is shielded by a blanket of granular fusible material called a flux. This granular material, flux, must ensure the deposition of weld metal of given chemical composition and specified mechanical properties. The flux must also ensure stable burning of the welding arc and contribute to the formation of a dense weld of required shape and size, and free from pores, cracks and slag inclusions. As the deposited molten metal solidifies, the flux must form a slag crust, easily separable from the surface of the weld. This material must be of a certain chemical composition and possess definite physical properties, such as melting point, viscosity, bulk weight. The chemical composition of the flux is chosen, depending on the composition of the welded metal and electrode wire used. (Author)

  3. Study of the transfer efficiency of alloyed elements in fluxes during submerged arc welding process

    International Nuclear Information System (INIS)

    Quintana, R.; Cruz, A.; Perdomo, L.; Castellanos, G.; Garcia, L. L.; Formoso, A.; Cores, A.

    2003-01-01

    It is assessed the transfer of chromium, manganese and carbon of different agglomerate fluxes constituted by 18.75% of alloyed load and 81.25% of matrix during the SAW process (submerge Arc Welding). A vitreous basic matrix corresponding to the system SiO 2 -Al 2 O 3 -(CaO+MgO) was obtained from minerals by fusion in the electric arc furnace. The current proportions of the alloyed load components (FeCr, FeMn and graphite) were carried out using a McLean Anderson experiment design. The corresponding fluxes to each experimental point were obtained by granulation with liquid glass;afterwards, their transfer coefficient for a given regimen of welding was determined. The transfer coefficients were calculated by means of a formula based on the laws of mass conservation and of distribution. (Author) 17 refs

  4. Upper shelf toughness of six submerged-arc weldmetals manufactured using Linde 124 flux

    International Nuclear Information System (INIS)

    Druce, S.G.; Hippsley, C.A.

    1984-06-01

    This paper describes the testing technique, data analysis procedures and results from the first phase of an experimental programme investigating upper shelf toughness of six submerged-arc weldmetals. The welds were manufactured using uncoated, Nickel coated and Copper coated wire electrodes and Linde 124 flux. J integral crack growth resistance curves have been derived from tests on single specimens over a range in temperature from 150 to 290 deg C. The results indicate a general decline in toughness with increasing temperature. At 290 deg C, the levels of initiation toughness from all six welds were essentially constant varying between 152 to 159 MPa square root of m. The Jsub(I)-R curves derived from this work are compared with toughness data used in the Marshall Study Group report of an assessment of the integrity of PWR pressure vessels. (author)

  5. Characterization of a manganese ore to define the use in the fluxes synthesis for submerged arc welding

    International Nuclear Information System (INIS)

    Cruz, A.; Quintana, R.; Perdomo, L.; Garcia, L. L.; Formoso, A.; Cores, A.

    2003-01-01

    Chemical analysis, thermal analysis (DTA and TG), phase determination by X-ray diffraction and granulometric analysis of the manganese ore from the location Margarita de Cambute in the eastern part of cuba were carried out. Based on these characterization results, a flux synthesis strategy was established, comprising the definition, as a basic condition, of the MnO/SiO 2 range of values. This strategy was confirmed experimentally by obtaining a flux prototype in an electric arc furnace connected to direct current source and the carrying out of the flux in submerged arc welding tests. (Author) 26 refs

  6. Use of refractory chromites for obtaining fluxes amassed employed in submerged arc welding (SAW); Empleo de cromitas refractarias par la obtencion de fundentes aglomerados utilizados en la soldadura automatica por arco sumegido (SAW)

    Energy Technology Data Exchange (ETDEWEB)

    Perdomo-Gonzalez, L.; Quintana-Puchol, R.; Cruz-Crespo, A.; Castellanos-Estupinan, J.; Garcia-Sanchez, L. L.; Formoso-Prego, A.; Cores-Sanchez, A.

    2003-07-01

    In the present work high carbon ferrochrome (load ferrochrome) and slags are obtained, starting from the metallurgic reductive processing of refractory chromites. The obtaining of alloys and slags is studied using an experiment design based in the relationships among components. The chemical compositions of alloys and slags guarantee their application for the conformation of alloys loads and matrix fluxes amassed for the superficial filling by means of submerged arc welding (SAW). The melting-reduction process is carried out in an electric arc furnace. (Author) 16 refs.

  7. Correlation of Flux Composition and Inclusion Characteristics With Submerged Arc Weld Metal Properties in HY-100 Steel

    Science.gov (United States)

    1993-09-01

    chemistries are complex, the welding engineer needs to obtain the correct CCT diagram for the alloy system in question. Once the CCT diagram is estimated...the CCT diagram must be pertinent to the particular chemistry of the weld metal, especially when the weld metal composition varies with flux

  8. Welding of Nb micro-alloyed steel by the submerged arc process using Brazilian consumables

    International Nuclear Information System (INIS)

    Scotti, A.; Quites, A.M.

    1982-01-01

    A set of procedures was established for welding of Nb micro-alloyed steel by the submerged arc process, using national consumables, in order to simultaneously achieve a more economic welding and better mechanical properties. From all the wire-flux combinations the better were the correspondent to AWS F84ED1, F74EM12K and F84EH14, the last being the best. (Author) [pt

  9. Submerged arc narrow gap welding of the steel DIN 20MnMoNi55

    International Nuclear Information System (INIS)

    Moraes, M.M.

    1987-01-01

    The methodology for submerged arc narrow gap welding for high thickness rolled steel DIN 20MnMoNi55 was developed, using din S3NiMo1 04 mm and 05 mm wires, and DIN 8B435 flux. For this purpose, submerged arc narrow gap welded joints with 50 mm and 120 mm thickness were made aiming the welding parameters optimization and the study of the influence of welding voltage, wire diameter and wire to groove face distance on the operational performance and on the welded joint quality, specially on the ISO-V impact toughness. These welded joints were checked by non-destructive mechanical and metallographic tests. Results were compared with those obtained by one 120 mm thickness submerged arc conventional gap welded joint, using the same base metal and consumables (05 mm wire). The analysis of the results shows that the increasing of the wire to groove face distance and the welding voltage increases the hardness and the ISO-V impact toughness of the weld metal. It shows that the reduction of the gap angle is the main cause for the obtained of a heat affected zone free from coarse grains, the reduction of the welding voltage, the increasing of the wire to groove face distance, and the grounding optimization also contribute for that. It was also concluded that the quality and the execution complexity level of a narrow gap welded joint are identical to a conventional gap welded joint. (author) [pt

  10. In process acoustic emission in multirun submerged arc welding

    International Nuclear Information System (INIS)

    Asty, M.; Birac, C.

    1980-01-01

    In order to avoid the formation of deep grooves when repairing defects in welded joints in heavy plates, an investigation was made aiming to detect and locate the defects by in-process acoustic emission in multirun submerged arc welding. Twelve defects (lack of penetration, cracks, inclusions, lack of fusion together with inclusions, blowholes) were intentionally introduced when the first plate was welded. A space-time method for processing the acoustic activity during welding allowed the detection and the location of the intentional defects as well as of the most important accidental defects evidenced by ultrasonic testing [fr

  11. Application of gas shielded arc welding and submerged arc welding for fabrication of nuclear reactor vessels

    International Nuclear Information System (INIS)

    Gehani, M.L.; Rodrigues, W.D.

    1976-01-01

    The remarkable progress made in the development of knowhow and expertise in the manufacture of equipment for nuclear power plants in India is outlined. Some of the specific advances made in the application of higher efficiency weld processes for fabrication of nuclear reactor vessels and the higher level of quality attained are discussed in detail. Modifications and developments in submerged arc, gas tungsten arc and gas metal arc processes for welding of Calandria which have been a highly challenging and rewarding experience are discussed. Future scope for making the gas metal arc process more economical by using various gas-mixes like Agron + Oxygen, Argon + Carbon Dioxide, Argon + Nitrogen (for Copper Alloys) etc., in various proportions are outlined. Quality and dimensional control exercised in these jobs of high precision are highlighted. (K.B.)

  12. Submerged-arc wire electrodes with nickel-plated surfaces

    International Nuclear Information System (INIS)

    Hagen, H. vom.

    1976-01-01

    The article reports on the development of SANWELD welding rods at GARHYTTAN's which is a wire free of impurities, copper, and hydrogen with a nickel surface. It is producted according to the SANBOND process. The wire has an optimum of mechanical quality grades depending on the powder used for welding, especially an improvement of notch impact strength. The elongation, especially the long-time values, are improved, hydrogen cracks are excluded depending on the correct powder or protective gas, and the low-temparature values are improved. An attendant phenomenon, which is not unimportant, is that the wires are practically corrosion-resistant in the non-welded state. The wire is suitable for submerged-arc welding in steam boilers and pressure vessels. (IHoe) [de

  13. The modelling of irradiation embrittlement in submerged-arc welds

    International Nuclear Information System (INIS)

    Bolton, C.J.; Buswell, J.T.; Jones, R.B.; Moskovic, R.; Priest, R.H.

    1996-01-01

    Until very recently, the irradiation embrittlement behavior of submerged-arc welds has been interpreted in terms of two mechanisms, namely a matrix damage component and an additional component due to the irradiation-enhanced production of copper-rich precipitates. However, some of the weld specimens from a recent accelerated re-irradiation experiment have shown high Charpy shifts which exceeded the values expected from the measured shift in yield stress. Microstructural examination has revealed the occurrence of intergranular fracture (IGF) in these specimens, accompanied by grain boundary segregation of phosphorus. Theoretical models were developed to predict the parametric dependence of irradiation-enhanced phosphorus segregation on experimental variables. Using these parametric forms, along with the concept of a critical level of segregation for the onset of IGF instead of cleavage, a three mechanism trend curve has been developed. The form of this trend curve, taking into account IGF as well as matrix and copper embrittlement, is thus mechanistically based. The constants in the equation, however, are obtained by a statistical fit to the actual Charpy shift database

  14. Stainless steel submerged arc weld fusion line toughness

    International Nuclear Information System (INIS)

    Rosenfield, A.R.; Held, P.R.; Wilkowski, G.M.

    1995-04-01

    This effort evaluated the fracture toughness of austenitic steel submerged-arc weld (SAW) fusion lines. The incentive was to explain why cracks grow into the fusion line in many pipe tests conducted with cracks initially centered in SAWS. The concern was that the fusion line may have a lower toughness than the SAW. It was found that the fusion line, Ji. was greater than the SAW toughness but much less than the base metal. Of greater importance may be that the crack growth resistance (JD-R) of the fusion line appeared to reach a steady-state value, while the SAW had a continually increasing JD-R curve. This explains why the cracks eventually turn to the fusion line in the pipe experiments. A method of incorporating these results would be to use the weld metal J-R curve up to the fusion-line steady-state J value. These results may be more important to LBB analyses than the ASME flaw evaluation procedures, since there is more crack growth with through-wall cracks in LBB analyses than for surface cracks in pipe flaw evaluations

  15. Fatigue assessment of a double submerged arc welded gas pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Fazzini, Pablo; Otegui, Jose Luis [Universidad Nacional Mar del Plata, Mar del Plata (Argentina). Instituto de Ciencia y Tecnologia de Materiales (INTEMA); Teutonico, Mauricio; Manfredi, Carlos [GIE S.A., Mar del Plata (Argentina)

    2005-07-01

    An uncommon blowout in a 24'' diameter, 7 mm thick API 5L X52 gas pipeline was due to fracture at the longitudinal double submerged arc weld. Oddly enough for gas pipelines, it was found that fatigue cracks had propagated from a large embedded weld defect of lack of fusion resulting from severe geometrical mismatch between inner and outer weld passes. What makes this failure particularly interesting is that: previous in line inspections failed to detect any defect, no evidence of third party damage was found, and very few large pressure cycles had been recorded during the last 5 years of service, which were believed to be representative of the entire service life of the pipeline. Fatigue tests were carried out to characterize propagation of fatigue cracks in weld metal, it was found that a large Paris exponent made the few large amplitude cycles most contributing to crack propagation. Crack growth path and striation patterns were studied. Fatigue growth was modelled by integrating experimental results and by extrapolating striation spacing in the fracture surface of the failed pipe. Crack growth path and striation patterns were studied. It was found that microstructure discontinuities govern propagation at low {delta}K, but one striation per cycle was produced at large {delta}K, due to a mostly ductile propagation mode. Fatigue growth was modelled by integrating experimental results and by extrapolating striation spacing in the fracture surface of the failed pipe. It was found that in the early life of the line many more large pressure cycles than expected had occurred. Good correspondence between predicted and actual fatigue lives was in this way obtained (author)

  16. Fatigue assessment of a double submerged arc welded gas pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Fazzini, Pablo; Otegui, Jose Luis [Universidad Nacional Mar del Plata, Mar del Plata (Argentina). Instituto de Ciencia y Tecnologia de Materiales (INTEMA); Teutonico, Mauricio; Manfredi, Carlos [GIE S.A., Mar del Plata (Argentina)

    2005-07-01

    An uncommon blowout in a 24'' diameter, 7 mm thick API 5L X52 gas pipeline was due to fracture at the longitudinal double submerged arc weld. Oddly enough for gas pipelines, it was found that fatigue cracks had propagated from a large embedded weld defect of lack of fusion resulting from severe geometrical mismatch between inner and outer weld passes. What makes this failure particularly interesting is that: previous in line inspections failed to detect any defect, no evidence of third party damage was found, and very few large pressure cycles had been recorded during the last 5 years of service, which were believed to be representative of the entire service life of the pipeline. Fatigue tests were carried out to characterize propagation of fatigue cracks in weld metal, it was found that a large Paris exponent made the few large amplitude cycles most contributing to crack propagation. Crack growth path and striation patterns were studied. Fatigue growth was modelled by integrating experimental results and by extrapolating striation spacing in the fracture surface of the failed pipe. Crack growth path and striation patterns were studied. It was found that microstructure discontinuities govern propagation at low {delta}K, but one striation per cycle was produced at large {delta}K, due to a mostly ductile propagation mode. Fatigue growth was modelled by integrating experimental results and by extrapolating striation spacing in the fracture surface of the failed pipe. It was found that in the early life of the line many more large pressure cycles than expected had occurred. Good correspondence between predicted and actual fatigue lives was in this way obtained (author)

  17. Finite element modelling of electric currents in AC submerged arc furnaces

    CSIR Research Space (South Africa)

    Mc Dougall, I

    2007-01-01

    Full Text Available and the power ratings is not a hindrance. 2. MATHEMATICAL FORMULATION As the frequency of the current is low, the quasi-static form of Maxwell’s equations is solved. (1) (2) (3) (4) where E denotes the electric field intensity, H the magnetic field... of Electric Currents in AC Submerged Arc Furnaces 637 REFERENCES [1] Bermudez, A., Muniz, M.C., Pena, F. , Bullon, J., “ Numerical Computation of the Electromagnetic Field in the Electrodes of a Three-Phase Arc Furnace”, Int. Jnl for Numerical Methods...

  18. Pragmatic analysis of the electric submerged arc furnace continuum

    Science.gov (United States)

    Karalis, K.; Karkalos, N.; Antipas, G. S. E.; Xenidis, A.

    2017-09-01

    A transient mathematical model was developed for the description of fluid flow, heat transfer and electromagnetic phenomena involved in the production of ferronickel in electric arc furnaces. The key operating variables considered were the thermal and electrical conductivity of the slag and the shape, immersion depth and applied electric potential of the electrodes. It was established that the principal stimuli of the velocities in the slag bath were the electric potential and immersion depth of the electrodes and the thermal and electrical conductivities of the slag. Additionally, it was determined that, under the set of operating conditions examined, the maximum slag temperature ranged between 1756 and 1825 K, which is in accordance with industrial measurements. Moreover, it was affirmed that contributions to slag stirring due to Lorentz forces and momentum forces due to the release of carbon monoxide bubbles from the electrode surface were negligible.

  19. Similarity of Ferrosilicon Submerged Arc Furnaces With Different Geometrical Parameters

    Directory of Open Access Journals (Sweden)

    Machulec B.

    2017-12-01

    Full Text Available In order to determine reasons of unsatisfactory production output regarding one of the 12 MVA furnaces, a comparative analysis with a furnace of higher power that showed a markedly better production output was performed. For comparison of ferrosilicon furnaces with different geometrical parameters and transformer powers, the theory of physical similarity was applied. Geometrical, electrical and thermal parameters of the reaction zones are included in the comparative analysis. For furnaces with different geometrical parameters, it is important to ensure the same temperature conditions of the reaction zones. Due to diverse mechanisms of heat generation, different criteria for determination of thermal and electrical similarity for the upper and lower reaction zones were assumed contrary to other publications. The parameter c3 (Westly was assumed the similarity criterion for the upper furnace zones where heat is generated as a result of resistive heating while the parameter J1 (Jaccard was assumed the similarity criterion for the lower furnace zones where heat is generated due to arc radiation.

  20. 3D Numerical Analysis of the Arc Plasma Behavior in a Submerged DC Electric Arc Furnace for the Production of Fused MgO

    International Nuclear Information System (INIS)

    Wang Zhen; Wang Ninghui; Li Tie; Cao Yong

    2012-01-01

    A three dimensional steady-state magnetohydrodynamic model is developed for the arc plasma in a DC submerged electric arc furnace for the production of fused MgO. The arc is generated in a small semi-enclosed space formed by the graphite electrode, the molten bath and unmelted raw materials. The model is first used to solve a similar problem in a steel making furnace, and the calculated results are found to be in good agreement with the published measurements. The behavior of arcs with different arc lengths is also studied in the furnace for MgO production. From the distribution of the arc pressure on the bath surface it is shown that the arc plasma impingement is large enough to cause a crater-like depression on the surface of the MgO bath. The circulation of the high temperature air under the electrode may enhance the arc efficiency, especially for a shorter arc.

  1. Mathematical model for optimization of multilayer submerged-arc welding of frame equipment of power units

    International Nuclear Information System (INIS)

    Pankov, V.V.; Chernyshev, G.G.; Kozlov, N.E.

    1987-01-01

    A mathematical model for optimization of multilayer submerged arc welding of frame equipment of power units is constructed. The variation-energy method permits to construct the universal mathematical model for strengthening formation of a single bead; the method is reasonable for simulation of a multilayer welded joint. Minimization of the distance between maximum and minimum layer height of a built-up metal is the necessary condition for qualitative formation of the multilayer joint. One can calculate in real time scale the optimal vector of maximally ten parameters under the multilayer welding condition immediately after change in the grooving width using the developed mathematical model of optimization

  2. Mechanical Characteristics of Submerged Arc Weldment in API Gas Pipeline Steel of Grade X65

    International Nuclear Information System (INIS)

    Hashemi, S. H.; Mohammadyani, D.

    2011-01-01

    The mechanical properties of submerged arc weldment (SAW) in gas transportation pipeline steel of grade API X65 (65 ksi yield strength) were investigated. This steel is produced by thermo mechanical control rolled (TMC), and is largely used in Iran gas piping systems and networks. The results from laboratory study on three different regions; i.e. base metal (BM), fusion zone (FZ) and heat affected zone (HAZ) were used to compare weldment mechanical characteristics with those specified by API 5L (revision 2004) standard code. Different laboratory experiments were conducted on test specimens taken from 48 inch outside diameter and 14.3 mm wall thickness gas pipeline. The test results showed a gradient of microstructure and Vickers hardness data from the centerline of FZ towards the unaffected MB. Similarly, lower Charpy absorbed energy (compared to BM) was observed in the FZ impact specimens. Despite this, the API specifications were fulfilled in three tested zones, ensuring pipeline structural integrity under working conditions.

  3. Monitoring of the submerged arc welding process using current and voltage transducers

    International Nuclear Information System (INIS)

    Barrera, G.; Velez, M.; Espinosa, M.A.; Santos, O.; Barrera, E.; Gomez, G.

    1996-01-01

    Welding by fusion is one of the most used techniques to join materials in the manufacture industry. given the increase in applications of this welding process and the demand of more quality in the welding deposits, these welding processes are good candidates for the improvement of their instrumentation and control. Any improvement in the control technique will have a positive effect in the quality and productivity of the welding process. Some of the most significant variables in the submerged arc welding process are: current, voltage and torch speed. For the instrumentation of this research work, two transducers were designed, one for CD current monitoring and one for CD voltage monitoring of the welding machine. The design of both transducers includes an isolation amplifier. Graphical programming and the concept of virtual instrumentation were the main tools used for the design of the data acquisition system and the signal processing task. (Author) 9 refs

  4. Energy and flux variations across thin auroral arcs

    Directory of Open Access Journals (Sweden)

    H. Dahlgren

    2011-10-01

    Full Text Available Two discrete auroral arc filaments, with widths of less than 1 km, have been analysed using multi-station, multi-monochromatic optical observations from small and medium field-of-view imagers and the EISCAT radar. The energy and flux of the precipitating electrons, volume emission rates and local electric fields in the ionosphere have been determined at high temporal (up to 30 Hz and spatial (down to tens of metres resolution. A new time-dependent inversion model is used to derive energy spectra from EISCAT electron density profiles. The energy and flux are also derived independently from optical emissions combined with ion-chemistry modelling, and a good agreement is found. A robust method to obtain detailed 2-D maps of the average energy and number flux of small scale aurora is presented. The arcs are stretched in the north-south direction, and the lowest energies are found on the western, leading edges of the arcs. The large ionospheric electric fields (250 mV m−1 found from tristatic radar measurements are evidence of strong currents associated with the region close to the optical arcs. The different data sets indicate that the arcs appear on the boundaries between regions with different average energy of diffuse precipitation, caused by pitch-angle scattering. The two thin arcs on these boundaries are found to be related to an increase in number flux (and thus increased energy flux without an increase in energy.

  5. Maximum allowable heat flux for a submerged horizontal tube bundle

    International Nuclear Information System (INIS)

    McEligot, D.M.

    1995-01-01

    For application to industrial heating of large pools by immersed heat exchangers, the socalled maximum allowable (or open-quotes criticalclose quotes) heat flux is studied for unconfined tube bundles aligned horizontally in a pool without forced flow. In general, we are considering boiling after the pool reaches its saturation temperature rather than sub-cooled pool boiling which should occur during early stages of transient operation. A combination of literature review and simple approximate analysis has been used. To date our main conclusion is that estimates of q inch chf are highly uncertain for this configuration

  6. Calorimeter probes for measuring high thermal flux. [in arc jets

    Science.gov (United States)

    Russell, L. D.

    1979-01-01

    Expendable, slug-type calorimeter probes were developed for measuring high heat-flux levels of 10-30 kW/sq cm in electric-arc jet facilities. The probes were constructed with thin tungsten caps mounted on Teflon bodies. The temperature of the back surface of the tungsten cap is measured, and its time rate of change gives the steady-state absorbed heat flux as the calorimeter probe heats to destruction when inserted into the arc jet. Design, construction, test, and performance data are presented.

  7. STUDY OF THE INFLUENCE OF THE HEAT INPUT ON MECHANICAL PROPERTIES OF C-Mn STEEL WELD METALS OBTAINED BY SUBMERGED ARC PROCESS

    Directory of Open Access Journals (Sweden)

    Erick de Sousa Marouço

    2013-06-01

    Full Text Available The present work is part of a research program that aims to evaluate the technical feasibility of increasing productivity in the manufacturing of tubular components for offshore oil industry, which are fully welded by automatic submerged arc welding process, with high heat input, but with no impairment on the impact toughness of the weld metal. Multipass welds were produced by the submerged arc welding process, with a combination of F7A4-EM12K (wire/flux, by using a 3.2 mm-diameter wire, preheating at 80°C, with direct current, in flat position, with heat input varying from 3.5 kJ/mm to 12 kJ/mm. After welding, tensile tests and Charpy-V impact tests at –60°C, –40°C, –20°C, 0°C and 20°C were carried out, as well as metallographic examination by both optical (OM and scanning electron microscopy (SEM, of specimens obtained entirely from the weld metal, allowing the discussion over the toughness X microstructure relationship. The weld metals have shown higher toughness levels in relation to the minimum required for use with low-alloy C-Mn steels welding with requirements of impact toughness of 27 J at 0°C for heat input up to 12 kJ/mm allowing an increase in productivity of 58% on the effective manufacturing time.

  8. Advances in submerged arc, narrow-gap welding with strip electrodes and thin, dual-wire electrodes

    International Nuclear Information System (INIS)

    Nies, H.

    1990-01-01

    Container and tank construction for nuclear installations traditionally is one of the major applications of narrow-gap welding with the submerged arc technique. This type of welding presents one problem, namely to completely and reliably remove the welding slag from the deep and narrow gap. The research report in hand explains the variants of welding techniques that have been tested and describes the results obtained, which primarily are reduced occurrence of faults, i.e. enhanced reliability, and better welding economy. As an alternative to welding with thick wire electrodes, which is the standard method for the applications under review, a new technique has been conceived and extensively tested, which uses thin strip electrodes at longitudinal position in the gap. This submerged arc, dual-wire technique with thin electrodes is characterised by a significantly higher thermal efficiency compared to welding with thick wires, so that the same energy input yields better efficiency of metal deposition. (orig./MM) [de

  9. Metallurgical and mechanical characterization of a submerged arc welded joint in a 316 type stainless steel

    International Nuclear Information System (INIS)

    Piatti, G.; Vedani, M.

    1990-01-01

    The tensile (deformation and fracture) behaviour of a multipass submerged arc welded joint Type 316 stainless steel is investigated by tests at room temperature and at 400 0 C on all-weld metal and transverse to weld (composite) specimens as well as by microstructural and compositional analyses (optical, scanning electron and transmission electron microscopy). The as-deposited metal is characterised by a systematic variation in the tensile properties across the thickness with the higher strength and the lower ductility in the weld centre. These variations are related to material variability (mainly in dislocation density) because of local dissimilarities in thermal and mechanical histories occurring during the welding process. However, the material variability in the fusion zone, although important is not so large in the present weld and it does not influence the tensile properties of the weld as a whole. Moreover, the tensile behaviour concerning the transverse to weld specimens is characterized by a supporting effect from the higher yield strength material zone (fusion zone) to the lower yield strength material zone (parent metal) justified by the different contribution of the parent metal and of the weld-deposit metal to the integral plastic strain of the specimens. (author)

  10. Analytical model of stress field in submerged arc welding butt joint with thorough penetration

    Directory of Open Access Journals (Sweden)

    Winczek Jerzy

    2018-01-01

    Full Text Available Analytical model of temporary and residual stresses for butt welding with thorough penetration was described assuming planar section hypothesis and using integral equations of stress equilibrium of the bar and simple Hooke’s law. In solution the effect of phase transformations (structure changes and structural strains has been taken into account. Phase transformations during heating are limited by temperature values at the beginning and at the end of austenitic transformation, depending on chemical composition of steel while the progress of phase transformations during cooling is determined on the basis of TTT-welding diagram. Temperature values at the beginning and at the end of transformation are conditioned by the speed of heating. Kinetics of diffusional transformation is described basing on Johnson-Mehl-Avrami-Kolmogorov equation, while martensitic transformation, basing on Koistinen-Marburger equation. Stresses in elasto-plastic state are determined by iteration, using elastic solutions method with changeable longitudinal modulus of elasticity, conditioned by stress-strain curve. Computations of stress field have been conducted for one-side butt welded of two steel flats made from S235 steel. It has enabled a clear interpretation of influence of temperature field and phase transformation on stresses caused by welding using Submerged Arc Welding (SAW method.

  11. The effect of heat treatment on phosphorus segregation in a submerged-arc weld metal

    International Nuclear Information System (INIS)

    Beere, W.B.; Buswell, J.T.

    1999-01-01

    Intergranular fracture (IGF) has been observed in carbon-manganese steels after irradiation or high temperature exposure for prolonged periods. The effect is associated with an increase in the ductile-brittle transition temperature and has been related to phosphorus diffusion to grain boundaries. Phosphorus also diffuses thermally at the temperatures used for post-weld heat treatments such that in principle, the slightly different heat treatments given to different parts of a large vessel could lead to differing grain boundary phosphorus coverage and hence susceptibility to IGF. The effect of typical heat treatments on phosphorus coverage has been investigated using a finite difference model based on a theory that has been fitted to a wide range of constant temperature data. Regardless of previous history, the grain boundary coverage of phosphorus was predicted to depend on the final anneal and cooling rate. These differed insufficiently in the typical heat treatments to produce significant differences in segregation. It was concluded that the ductile-brittle transition temperature in submerged-arc welds would be unaffected in vessels that had seen typical post-weld heat treatments

  12. Optimization of submerged arc welding process parameters using quasi-oppositional based Jaya algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Rao, R. Venkata; Rai, Dhiraj P. [Sardar Vallabhbhai National Institute of Technology, Gujarat (India)

    2017-05-15

    Submerged arc welding (SAW) is characterized as a multi-input process. Selection of optimum combination of process parameters of SAW process is a vital task in order to achieve high quality of weld and productivity. The objective of this work is to optimize the SAW process parameters using a simple optimization algorithm, which is fast, robust and convenient. Therefore, in this work a very recently proposed optimization algorithm named Jaya algorithm is applied to solve the optimization problems in SAW process. In addition, a modified version of Jaya algorithm with oppositional based learning, named “Quasi-oppositional based Jaya algorithm” (QO-Jaya) is proposed in order to improve the performance of the Jaya algorithm. Three optimization case studies are considered and the results obtained by Jaya algorithm and QO-Jaya algorithm are compared with the results obtained by well-known optimization algorithms such as Genetic algorithm (GA), Particle swarm optimization (PSO), Imperialist competitive algorithm (ICA) and Teaching learning based optimization (TLBO).

  13. Optimization of submerged arc welding process parameters using quasi-oppositional based Jaya algorithm

    International Nuclear Information System (INIS)

    Rao, R. Venkata; Rai, Dhiraj P.

    2017-01-01

    Submerged arc welding (SAW) is characterized as a multi-input process. Selection of optimum combination of process parameters of SAW process is a vital task in order to achieve high quality of weld and productivity. The objective of this work is to optimize the SAW process parameters using a simple optimization algorithm, which is fast, robust and convenient. Therefore, in this work a very recently proposed optimization algorithm named Jaya algorithm is applied to solve the optimization problems in SAW process. In addition, a modified version of Jaya algorithm with oppositional based learning, named “Quasi-oppositional based Jaya algorithm” (QO-Jaya) is proposed in order to improve the performance of the Jaya algorithm. Three optimization case studies are considered and the results obtained by Jaya algorithm and QO-Jaya algorithm are compared with the results obtained by well-known optimization algorithms such as Genetic algorithm (GA), Particle swarm optimization (PSO), Imperialist competitive algorithm (ICA) and Teaching learning based optimization (TLBO).

  14. Double-Sided Single-Pass Submerged Arc Welding for 2205 Duplex Stainless Steel

    Science.gov (United States)

    Luo, Jian; Yuan, Yi; Wang, Xiaoming; Yao, Zongxiang

    2013-09-01

    The duplex stainless steel (DSS), which combines the characteristics of ferritic steel and austenitic steel, is used widely. The submerged arc welding (SAW) method is usually applied to join thick plates of DSS. However, an effective welding procedure is needed in order to obtain ideal DSS welds with an appropriate proportion of ferrite (δ) and austenite (γ) in the weld zone, particularly in the melted zone and heat-affected zone. This study evaluated the effectiveness of a high efficiency double-sided single-pass (DSSP) SAW joining method for thick DSS plates. The effectiveness of the converse welding procedure, characterizations of weld zone, and mechanical properties of welded joint are analyzed. The results show an increasing appearance and continuous distribution feature of the σ phase in the fusion zone of the leading welded seam. The converse welding procedure promotes the σ phase to precipitate in the fusion zone of leading welded side. The microhardness appears to significantly increase in the center of leading welded side. Ductile fracture mode is observed in the weld zone. A mixture fracture feature appears with a shear lip and tears in the fusion zone near the fusion line. The ductility, plasticity, and microhardness of the joints have a significant relationship with σ phase and heat treatment effect influenced by the converse welding step. An available heat input controlling technology of the DSSP formation method is discussed for SAW of thick DSS plates.

  15. Irradiation behavior of a submerged arc welding material with different copper content; Bestrahlungsverhalten einer UP-Versuchsschweissnaht mit unterschiedlichen Kupfergehalten

    Energy Technology Data Exchange (ETDEWEB)

    Langer, R [Siemens AG Energieerzeugung KWU, Erlangen (Germany); Bartsch, R [Kernkraftwerk Obrigheim GmbH (Germany)

    1998-11-01

    Che report presents results of an irradiation program on specimens of submerged arc weldings with copper contents of 0.14% up to 0.42% and a fluence up to 2.2E19 cm{sup -2} (E>1MeV). Unirradiated and irradiated tensile- Charpy-, K{sub lc}- and Pellini-specimens were tested of material with a copper content of 0.22%. On the other materials Charpy tests and tensile tests were performed. The irradiation of the specimens took place in the KWO - ``RPV, a PWR with low flux and in the VAK - RPV, a small BWR with high flux. - The irradiation induced embrittlemnt shows a copper dependence up to about 30%. The specimens with a copper content higher than 0.30% show no further embrittlement. Irradiation in different reactors with different flux (factor > 33) shows the same state of embrittlement. Determination of a K{sub lc}, T-curve with irradiated specimens is possible. The conservative of the RT{sub NDT} - concept could be confirmed by the results of Charpy-V, drop weight- and K{sub lc}-test results. [Deutsch] Zur zusaetzlichen Absicherung des KWO-RDB wurde Ende 1979 eine UP-Versuchsschweissnaht mit vergleichbarer chemischer Zusammensetzung und vergleibaren mechanisch-technologischen Werkstoffen im unbestrahlten Ausgangszustand wie die RDB Core-Rundnaht hergestellt. Teile der Naht wurden durch Verkupfern der Schweissdraehte auf unterschiedliche Gehalte von Cu=0,14% bis 0,42% eingestellt. Aus dieser Schweissverbindung wurden Proben im VAK und KWO-RDB bestrahlt. Im Rahmen der Aktivitaeten zur Absicherung des KWO-RDBs erfolgte 1995 die Pruefung der bestrahlten Proben. Die mechanisch technologischen Werkstoffwerte vor und nach Bestrahlung werden gegenuebergestellt und praesentiert. Mit dem Ergebnis wurde ein weiterer Nachweis fuer die Konservativitaet des RT{sub NDT}-Konzeptes erbracht. Es wurde nachgewiesen, dass fuer den untersuchten Bereich kein Dose-Rate Effekt bzw. Bestrahlungszeiteinfluss existiert. Fuer UP-Schweissungen mit den vorliegenden Fertigungsparametern und bei

  16. Joining of Materials with Diferent Properties Through Submerged Arc Welding Process and Destructive and Non-Destructive Testing of the Joints

    Directory of Open Access Journals (Sweden)

    Yakup Kaya

    2013-01-01

    Full Text Available In this study, X60, X65 and X70 steels used in petroleum and natural gas pipeline were joined with Submerged Arc Welding by using different type of welding fluxes (LN761 and P223 and wires (S1 and S2Mo. Initially, visual and radiographic inspection techniques were subjected to welded joints for determining surface and subsurface defects. After that, spectral analyses were carried out in order to determine the compositions of wire-flux-base metal on the joints. Impact toughness test were performed for determining toughness properties the joints. Furthermore, hardness and microstructure studies were also carried out on the samples. As a result of the visual and radiographic inspection on the welded samples, there were no weld defects on joints were observed. It was clearly understood that carbon ratio in the compositions of weld metal higher than base metal but lower than filler metal in terms of spectral analyses results. According to impact toughness test results, the joints obtained by using S2Mo welding wire and P223 welding flux had better impact toughness value than the joints obtained by S1 welding wire and LN 761 welding flux. With respect to hardness test, the highest hardness values were measured on weld metal. When the microstructure images were examined, it is clearly understood that similar images for all the joints were shown adjacent zones to weld metals heat affected zones and welding boundary, due to heat input constant.

  17. The modelling of irradiation-enhanced phosphorus segregation in neutron irradiated reactor pressure vessel submerged-arc welds

    Energy Technology Data Exchange (ETDEWEB)

    Druce, S.G.; English, C.A.; Foreman, A.J.E.; McElroy, R.J.; Vatter, I.A. [AEA Technology, Didcot (United Kingdom). Harwell Lab.; Bolton, C.J.; Buswell, J.T.; Jones, R.B. [Nuclear Electric, Berkeley (United Kingdom). Berkeley Technology Centre

    1996-12-31

    Recent results on neutron-irradiated RPV submerged-arc welds have revealed grain boundary segregation of phosphorus during irradiation, which may lead to intergranular fracture. However, the experimental database is insufficient to define the dependence of the process on variables such ad dose, dose-rate and temperature. This paper describes work in which two existing models of phosphorus segregation, under thermal or irradiation conditions, have been developed to obtain predictions of these dependencies. The critical parameters in the models have been adjusted to give consistency with the available reference data, and predictions have been made of the dependence of segregation on a number of variables.

  18. Microstructural changes of a thermally aged stainless steel submerged arc weld overlay cladding of nuclear reactor pressure vessels

    Science.gov (United States)

    Takeuchi, T.; Kameda, J.; Nagai, Y.; Toyama, T.; Matsukawa, Y.; Nishiyama, Y.; Onizawa, K.

    2012-06-01

    The effect of thermal aging on microstructural changes in stainless steel submerged arc weld-overlay cladding of reactor pressure vessels was investigated using atom probe tomography (APT). In as-received materials subjected to post-welding heat treatments (PWHTs), with a subsequent furnace cooling, a slight fluctuation of the Cr concentration was observed due to spinodal decomposition in the δ-ferrite phase but not in the austenitic phase. Thermal aging at 400 °C for 10,000 h caused not only an increase in the amplitude of spinodal decomposition but also the precipitation of G phases with composition ratios of Ni:Si:Mn = 16:7:6 in the δ-ferrite phase. The degree of the spinodal decomposition in the submerged arc weld sample was similar to that in the electroslag weld one reported previously. We also observed a carbide on the γ-austenite and δ-ferrite interface. There were no Cr depleted zones around the carbide.

  19. Microstructural changes of a thermally aged stainless steel submerged arc weld overlay cladding of nuclear reactor pressure vessels

    Energy Technology Data Exchange (ETDEWEB)

    Takeuchi, T., E-mail: takeuchi.tomoaki@jaea.go.jp [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Kameda, J. [National Institute for Materials Science, Sengen, Tsukuba 305-0047 (Japan); Nagai, Y.; Toyama, T.; Matsukawa, Y. [Oarai Center, Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313 (Japan); Nishiyama, Y.; Onizawa, K. [Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

    2012-06-15

    The effect of thermal aging on microstructural changes in stainless steel submerged arc weld-overlay cladding of reactor pressure vessels was investigated using atom probe tomography (APT). In as-received materials subjected to post-welding heat treatments (PWHTs), with a subsequent furnace cooling, a slight fluctuation of the Cr concentration was observed due to spinodal decomposition in the {delta}-ferrite phase but not in the austenitic phase. Thermal aging at 400 Degree-Sign C for 10,000 h caused not only an increase in the amplitude of spinodal decomposition but also the precipitation of G phases with composition ratios of Ni:Si:Mn = 16:7:6 in the {delta}-ferrite phase. The degree of the spinodal decomposition in the submerged arc weld sample was similar to that in the electroslag weld one reported previously. We also observed a carbide on the {gamma}-austenite and {delta}-ferrite interface. There were no Cr depleted zones around the carbide.

  20. Fatigue crack growth behavior of pressure vessel steels and submerged arc weldments in a high-temperature pressurized water environment

    International Nuclear Information System (INIS)

    Liaw, P.K.; Logsdon, W.A.; Begley, J.A.

    1989-01-01

    The fatigue crack growth rate (FCGR) properties of SA508 Cl 2a and SA533 Gr A Cl 2 pressure vessel steels and the corresponding automatic submerged arc weldments were developed in a high-temperature pressurized water (HPW) environment at 288 degrees C (550 degrees F) and 7.2 MPa (1044 psi) at load ratios of 0.20 and 0.50. The properties were generally conservative compared to American Society of Mechanical Engineers Section XI water environment reference curve. The growth rate of fatigue cracks in the base materials, however, was faster in the HPW environment than in a 288 degrees C (550 degrees F) base line air environment. The growth rate of fatigue cracks in the two submerged arc weldments was also accelerated in the HPW environment but to a lesser degree than that demonstrated by the base materials. In the air environment, fatigue striations were observed, independent of material and load ratio, while in the HPW environment, some intergranular facets were present. The greater environmental effect on crack growth rates displayed by the base materials compared the weldments attributed to a different sulfide composition and morphology

  1. Electrical conductivity of the screening residuals of coke production in context of ferrochromium production in a submerged arc furnace

    Energy Technology Data Exchange (ETDEWEB)

    Rousu, Arto; Mattila, Olli [Lab. of Process Metallurgy, Univ. of Oulu (Finland)

    2009-11-15

    Coke is used as a reducing agent in the production of ferrochromium in a submerged arc furnace (SAF). Its good electrical conductivity compared to other input materials makes it a dominant current conductivity substance in the burden. The resistance of the coke has to be high enough to ensure the proper functionality of the furnace. Used cokes for submerged arc furnace production are relatively small in size compared to e.g. blast furnace (BF) cokes. A common practice is to use screening residual coke, which is too small for the BF, in SAF. The goal of this study was to show differences in the electrical properties of screening residual cokes compared to coke formed in different parts of the coke battery, in dependence of particle size. The resistances of different cokes were measured and XRD measurements were performed to define the crystallographic structure of the selected cokes. The results indicate that small coke particles have higher overall resistance, which is due to their internal properties. This small weakly carbonized coke is formed in the middle of the coking battery and is subject to changes in varying coking practices. Continuous quality control of screening residual coke is needed to use it in the SAF. (orig.)

  2. Interactive Relationship between Silver Ions and Silver Nanoparticles with PVA Prepared by the Submerged Arc Discharge Method

    Directory of Open Access Journals (Sweden)

    Kuo-Hsiung Tseng

    2018-01-01

    Full Text Available This study uses the submerged arc discharge method (SADM and the concentrated energy of arc to melt silver metal in deionized water (DW so as to prepare metal fluid with nanoparticles and submicron particles. The process is free from any chemical agent; it is rapid and simple, and rapid and mass production is available (0.5 L/min. Aside from the silver nanoparticle (Ag0, silver ions (Ag+ exist in the colloidal Ag prepared by the system. In the preparation of colloidal Ag, polyvinyl alcohol (PVA is used as an additive so that the Ag0/Ag+ concentration, arcing rate, peak, and scanning electron microscopic (SEM images in the cases with and without PVA can be analyzed. The findings show that the Ag0/Ag+ concentration increases with the addition level of PVA, while the nano-Ag and Ag+ electrode arcing rate rises. The UV-Vis absorption peak increases Ag0 absorbance and shifts as the dispersity increases with PVA addition. Lastly, with PVA addition, the proposed method can prepare smaller and more amounts of Ag0 nanoparticles, distributed uniformly. PVA possesses many distinct features such as cladding, dispersion, and stability.

  3. Abrasion Wear Resistance, Hardness and Microstructure of Hard Linings Deposited by Means of a Submerged Arc. Dureza, microestructura y resistencia al desgaste por abrasion de recargues duros depositados con arco sumergido

    Energy Technology Data Exchange (ETDEWEB)

    Paranhos, R; Alcoforado, J M; Castillo, J A; Sauer, A

    1989-01-01

    Consumable materials for submerged arc welding of the types alloyed flux-neutral electrode and neutral flux-alloyed electrode were used to form, through multipass welding, a light alloy hard lining of the C-Mn type on ASTM A36 Type structural steel. Emphasis was put on microstructural characterization of the linings surveyed under electron scanning microscopy, and tests were performed to study their hardness and abrasion wear resistance at low pressures. As a result of these tests, a great influence of welding parameters on hardness and abrasion resistance properties of the combination active flux-neutral electrode was noticed. As the results showed no relationship between the hardness and the abrasion wear resistance of the linings surveyed, an attempt was made to relate the resulting microstructure with their abrasion wear resistance. (Author)

  4. Nuclear Technology. Course 28: Welding Inspection. Module 28-3, Tungsten Inert Gas (TIG), Metal Inert Gas (MIG) and Submerged Arc Welding.

    Science.gov (United States)

    Espy, John

    This third in a series of ten modules for a course titled Welding Inspection presents the apparatus, process techniques, procedures, applications, associated defects, and inspection for the tungsten inert gas, metal inert gas, and submerged arc welding processes. The module follows a typical format that includes the following sections: (1)…

  5. Welding by submerged arc of steel with addition of iron powder; Soldagem por arco submerso de aco microligado com adicao de po de ferro

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Samuel I.N.; Spinelli, Dirceu [Sao Paulo Univ., Sao Carlos, SP (Brazil). Escola de Engenharia; Souza, Paulo C.R. D. de [SICOM Compressores Ltda., Sao Carlos, SP (Brazil); Magalhaes Bento Goncalves, Gilberto de [Bauru Univ., SP (Brazil)

    1993-12-31

    Welding metals with and without iron powder addition were produced in steel plates ASTM A 242 by submerged arc process. as a conclusion, the mechanical properties of hardness and toughness of weld metal and heat affect zone were more affected when the welding were done with lower heat input. (author). 16 refs., 3 figs., 9 tabs.

  6. The influence of plate thickness on the welding residual stresses from submerged arc welding in offshore steel structures

    DEFF Research Database (Denmark)

    Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

    2017-01-01

    Welding-induced residual tensile stresses and distortion have become a major concern in relation to the structural integrity of welded structures within the offshore wind industry. The stresses have a negative impact on the integrity of the welded joint, as they promote distortion, reduce fatigue...... leading to a better understanding of the distribution and development of the welding residual stresses. This can later be used to optimize the fatigue design, providing a more efficient and improved design. In this context, the current research is expected to benefit the offshore industry by leading...... to an improved design, which consequently may be included in future norms and standards. Submerged Arc Welding (SAW) was used to make a fully penetrated butt weld in 10 mm and 40 mm thick steel plates with the same welding parameters as used in the production procedures. The base material is thermomechanical hot...

  7. Mechanism and Microstructure of Oxide Fluxes for Gas Tungsten Arc Welding of Magnesium Alloy

    Science.gov (United States)

    Liu, L. M.; Zhang, Z. D.; Song, G.; Wang, L.

    2007-03-01

    Five single oxide fluxes—MgO, CaO, TiO2, MnO2, and Cr2O3—were used to investigate the effect of active flux on the depth/width ratio in AZ31B magnesium alloy. The microstructure and mechanical property of the tungsten inert gas (TIG) welding seam were studied. The oxygen content in the weld seam and the arc images during the TIG welding process were analyzed. A series of emission spectroscopy of weld arc for TIG welding for magnesium with and without flux were developed. The results showed that for the five single oxide fluxes, all can increase the weld penetration effectively and grain size in the weld seam of alternating current tungsten inert gas (ACTIG) welding of the Mg alloy. The oxygen content of the welds made without flux is not very different from those produced with oxide fluxes not considering trapped oxide. However, welds that have the best penetration have a relatively higher oxygen content among those produced with flux. It was found that the arc images with the oxide fluxes were only the enlarged form of the arc images without flux; the arc constriction was not observed. The detection of arc spectroscopy showed that the metal elements in the oxides exist as the neutral atom or the first cation in the weld arc. This finding would influence the arc properties. When TIG simulation was carried out on a plate with flux applied only on one side, the arc image video showed an asymmetric arc, which deviated toward the flux free side. The thermal stability, the dissociation energy, and the electrical conductivity of oxide should be considered when studying the mechanism for increased TIG flux weld penetration.

  8. Single-walled nanohorns and other nanocarbons generated by submerged arc discharge between carbon electrodes in liquid argon and other media

    International Nuclear Information System (INIS)

    Vasu, K; Pramoda, K; Govindaraj, A; Rao, C N R; Moses, K

    2014-01-01

    Arc discharge between two graphite electrodes submerged in different liquid media yields various dimensional nanocarbon structures such as 1D carbon nanotubes and 2D graphene. Single-walled carbon nanohorns (SWNHs) prepared by submerged arc discharge in liquid nitrogen medium are found to have nitrogen impurities. Here, we report the structure and properties of pure and nitrogen-doped SWNHs obtained by submerged arc discharge in a liquid argon medium. The absence of an XPS N 1s signal, which is present in nanohorns obtained in liquid nitrogen, indicate that the nanohorns are free from nitrogen impurities. Raman spectra show a strong defect-induced D band and current–voltage characteristics show a slight nonlinear behavior. N 2 adsorption of pure SWNHs shows type-IV isotherms with a surface area of 300 m 2 g −1 . Adsorption of CO 2 and H 2 in pure SWNHs has also been measured. Arc discharge in other liquid media such as water, ethanol, dimethylformamide (DMF), n-methyl pyrrolidone (NMP), formamide, benzene, heptane and acetone yields different nanocarbon structures including multi-walled carbon nanotubes (MWNTs), few-layer graphene, carbon onions and carbon nanoparticles. (papers)

  9. Fabrication of TiO2/Carbon Photocatalyst using Submerged DC Arc Discharged in Ethanol/Acetic Acid Medium

    Science.gov (United States)

    Saraswati, T. E.; Nandika, A. O.; Andhika, I. F.; Patiha; Purnawan, C.; Wahyuningsih, S.; Rahardjo, S. B.

    2017-05-01

    This study aimed to fabricate a modified photocatalyst of TiO2/C to enhance its performance. The fabrication was achieved using the submerged direct current (DC) arc-discharge method employing two graphite electrodes, one of which was filled with a mixture of carbon powder, TiO2, and binder, in ethanol with acetic acid added in various concentrations. The arc-discharge method was conducted by flowing a current of 10-20 A (~20 V). X-ray diffraction (XRD) patterns showed significant placements of the main peak characteristics of TiO2, C graphite, and titanium carbide. The surface analysis using Fourier transform infrared spectroscopy (FTIR) revealed that fabricated TiO2/C nanoparticles had stretching vibrations of Ti-O, C-H, C═O, C-O, O-H and C═C in the regions of 450-550 cm-1, 2900-2880 cm-1, 1690-1760 cm-1, 1050-1300 cm-1, 3400-3700 cm-1 and ~1600 cm-1, respectively. In addition, the study investigated the photocatalysts of unmodified and modified TiO2/C for photodegradation of methylene blue (MB) dye solution under mercury lamp irradiation. The effectiveness of the degradation was defined by the decrease in 60-minute absorbance under a UV-Vis spectrophotometer. Modified TiO2/C proved to be significantly more efficient in reducing dye concentrations, reaching ~70%. It indicated that the oxygen-containing functional groups have been successfully attached to the surface of the nanoparticles and played a role in enhancing photocatalytic activity.

  10. Heat Flux of a Transferred Arc Driven by a Transverse Magnetic Field

    Directory of Open Access Journals (Sweden)

    Naomi Matsumoto

    2009-01-01

    Full Text Available Theoretical consideration of a magnetically driven arc was performed to elucidate the variation of heat flux with an imposed DC magnetic field. Experiments were conducted to confirm the validity of the theoretical model. The heat flux decreased concomitantly with increased imposed magnetic flux density. Theoretical predictions agreed with experimental results.

  11. Submerged Arc Stainless Steel Strip Cladding—Effect of Post-Weld Heat Treatment on Thermal Fatigue Resistance

    Science.gov (United States)

    Kuo, I. C.; Chou, C. P.; Tseng, C. F.; Lee, I. K.

    2009-03-01

    Two types of martensitic stainless steel strips, PFB-132 and PFB-131S, were deposited on SS41 carbon steel substrate by a three-pass submerged arc cladding process. The effects of post-weld heat treatment (PWHT) on thermal fatigue resistance and hardness were evaluated by thermal fatigue and hardness testing, respectively. The weld metal microstructure was investigated by utilizing optical microscopy, scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM). Results showed that, by increasing the PWHT temperature, hardness decreased but there was a simultaneous improvement in weldment thermal fatigue resistance. During tempering, carbide, such as (Fe, Cr)23C6, precipitated in the weld metals and molybdenum appeared to promote (Fe, Cr, Mo)23C6 formation. The precipitates of (Fe, Cr, Mo)23C6 revealed a face-centered cubic (FCC) structure with fine grains distributed in the microstructure, thereby effectively increasing thermal fatigue resistance. However, by adding nickel, the AC1 temperature decreased, causing a negative effect on thermal fatigue resistance.

  12. Irradiation effects on fracture toughness of two high-copper submerged-arc welds, HSSI Series 5

    International Nuclear Information System (INIS)

    Nanstad, R.K.; Haggag, F.M.; McCabe, D.E.; Iskander, S.K.; Bowman, K.O.; Menke, B.H.

    1992-10-01

    The Fifth Irradiation Series in the Heavy-Section Steel Irradiation Program obtained a statistically significant fracture toughness data base on two high-copper (0.23 and 0.31 wt %) submerged-arc welds to determine the shift and shape of the K Ic curve as a consequence of irradiation. Compact specimens with thicknesses to 101.6 mm (4 in) in the irradiated condition and 203.2 mm (8 in) in the unirradiated condition were tested, in addition to Charpy impact, tensile, and drop-weight specimens. Irradiations were conducted at a nominal temperature of 288 degree C and an average fluence of 1.5 x 10 19 neutrons/cm 2 (>l MeV). The Charpy 41-J temperature shifts are about the same as the corresponding drop-weight NDT temperature shifts. The irradiated welds exhibited substantial numbers of cleavage pop-ins. Mean curve fits using two-parameter (with fixed intercept) nonlinear and linearized exponential regression analysis revealed that the fracture toughness 100 MPa lg-bullet √m shifts exceeded the Charpy 41-J shifts for both welds. Analyses of curve shape changes indicated decreases in the slopes of the fracture toughness curves, especially for the higher copper weld. Weibull analyses were performed to investigate development of lower bound curves to the data, including the use of a variable K min parameter which affects the curve shape

  13. The movement of the burden in submerged-arc furnaces for the production of high-carbon ferromanganese

    International Nuclear Information System (INIS)

    Dyason, G.J.; See, J.B.

    1978-01-01

    The mechanism by which the burden moves in a submerged-arc furnace was investigated in two large industrial furnaces by the stimulus-response technique with a radiotracer of the radio-isotope 5 Fe as the stimulus. As this radio-isotope was suitable only for the measurement of residence-time distributions in the alloy phase, the analysis of the experiments was limited to that phase. The residence-time distributions obtained by the measurement of alloy samples obtained during tapping were analysed by various techniques. This analysis verified the existence of stagnant zones within the furnace, and showed that the movement of the burden through the furnace could not be described by either of the two idealized patterns of flow, i.e., plug flow or mixed flow. A composite model to describe the movement of the burden through the furnace was developed by consideration of the mechanism and position of heat generation within the furnace, the inner structure of the furnace, the general form of the measured residence-time distributions, and the mode of burden descent through the furnace. The composite model consisted of a dispersed plug-flow region in the upper regions of the furnace discharging into a constantly stirred tank reactor beneath the electrode tips. Non-linear regression analysis of the equations developed from the composite model permitted the selection of optimum values of model parameters to give computed curves that approximated to the residence-time distributions [af

  14. The relationship between critical flux and fibre movement induced by bubbling in a submerged hollow fibre system.

    Science.gov (United States)

    Wicaksana, F; Fan, A G; Chen, V

    2005-01-01

    Bubbling has been used to enhance various processes. In this paper we deal with the effect of bubbling on submerged hollow fibre membranes, where bubbling is applied to prevent severe membrane fouling. Previous work with submerged hollow fibres has observed that significant fibre movement can be induced by bubbling and that there is a qualitative relationship between fibre movement and filtration performance. Therefore, the aim of the present research has been to analyse the link between bubbling, fibre movement and critical flux, identified as the flux at which the transmembrane pressure (TMP) starts to rise. Tests were performed on vertical isolated fibres with a model feed of yeast suspension. The fibres were subject to steady bubbling from below. The parameters of interest were the fibre characteristics, such as tightness, diameter and length, as well as feed concentration. The results confirmed that the critical fluxes are affected by the fibre characteristics and feed concentration. Higher critical flux values can be achieved by using loose fibres, smaller diameters and longer fibres. The enhancement is partially linked to fibre movement and this is confirmed by improved performance when fibres are subject to mechanical movement in the absence of bubbling.

  15. Effects of Surface Alloying and Laser Beam Treatment on the Microstructure and Wear Behaviour of Surfaces Modified Using Submerged Metal Arc Welding

    Directory of Open Access Journals (Sweden)

    Regita BENDIKIENE

    2016-05-01

    Full Text Available In this study, the effects of surface alloying of cheap plain carbon steel using submerged metal arc technique and subsequent laser beam treatment on the microstructure and wear behaviour of surfaced layers were studied. This method is the cheapest one to obtain high alloyed coatings, because there is no need to apply complex technologies of powder making (metal powder is spread on the surface of base metal or inserted into the flux, it is enough to grind, granulate and blend additional materials. On the other hand, strengthening of superficial layers of alloys by thermal laser radiation is one of the applications of laser. Surface is strengthened by concentrated laser beam focused into teeny area (from section of mm till some mm. Teeny area of metal heat up rapidly and when heat is drain to the inner metal layers giving strengthening effect. Steel surface during this treatment exceeds critical temperatures, if there is a need to strengthen deeper portions of the base metal it is possible even to fuse superficial layer. The results presented in this paper are based on micro-structural and micro-chemical analyses of the surfaced and laser beam treated surfaces and are supported by analyses of the hardness, the wear resistance and resultant microstructures. Due to the usage of waste raw materials a significant improvement (~ 30 % in wear resistance was achieved. The maximum achieved hardness of surfaced layer was 62 HRC, it can be compared with high alloyed conventional steel grade. Wear properties of overlays with additional laser beam treatment showed that weight loss of these layers was ~10 % lower compared with overlays after welding; consequently it is possible to replace high alloyed conventional steel grades forming new surfaces or restoring worn machine elements and tools.DOI: http://dx.doi.org/10.5755/j01.ms.22.1.7621

  16. Heat flux characteristics in an atmospheric double arc argon plasma jet

    International Nuclear Information System (INIS)

    Tu Xin; Yu Liang; Yan Jianhua; Cen Kefa; Cheron, Bruno

    2008-01-01

    In this study, the axial evolution of heat flux excited by a double arc argon plasma jet impinging on a flat plate is determined, while the nonstationary behavior of the heat flux is investigated by combined means of the fast Fourier transform, Wigner distribution, and short-time Fourier transform. Two frequency groups (<1 and 2-10 kHz) are identified in both the Fourier spectrum and the time-frequency distributions, which suggest that the nature of fluctuations in the heat flux is strongly associated with the dynamic behavior of the plasma arc and the engulfment of ambient air into different plasma jet regions

  17. Membrane flux dynamics in the submerged ultrafiltration hybrid treatment process during particle and natural organic matter removal

    Institute of Scientific and Technical Information of China (English)

    Wei Zhang; Xiaojian Zhang; Yonghong Li; Jun Wang; Chao Chen

    2011-01-01

    Particles and natural organic matter (NOM) are two major concerns in surface water,which greatly influence the membrane filtration process.The objective of this article is to investigate the effect of particles,NOM and their interaction on the submerged ultrafiltration (UF) membrane flux under conditions of solo UF and coagulation and PAC adsorption as the pretreatment of UF.Particles,NOM and their mixture were spiked in tap water to simulate raw water.Exponential relationship,(JP/JP0 =axexp{-k[t-(n- 1)T]}),was developed to quantify the normalized membrane flux dynamics during the filtration period and fitted the results well.In this equation,coefficient a was determined by the value of Jp/Jp0 at the beginning of a filtration cycle,reflecting the flux recovery after backwashing,that is,the irreversible fouling.The coefficient k reflected the trend of flux dynamics.Integrated total permeability (ΣJp) in one filtration period could be used as a quantified indicator for comparison of different hybrid membrane processes or under different scenarios.According to the results,there was an additive effect on membrane flux by NOM and particles during solo UF process.This additive fouling could be alleviated by coagulation pretreatment since particles helped the formation of flocs with coagulant,which further delayed the decrease of membrane flux and benefited flux recovery by backwashing.The addition of PAC also increased membrane flux by adsorbing NOM and improved flux recovery through backwashing.

  18. Further contribution to the study of buffer layer on austenitic stainless stell overlays obtained by means of automatic submerged arc welding with electrode-wire

    International Nuclear Information System (INIS)

    Colla, G.

    1988-01-01

    The influence of several buffer layer types on a 308 type austenitic stainless steel surface overlay having a 19-21% chromium and 10-12% nikel content have been analysed. Cladding passes have been deposited on carbon steel test samples by using automatic submerged arc welding process with electrode-wire. The experimental tests have involved buffer layers having seven different chemical compositions and the obtained results are reported and discussed in the paper. The achieved experimetal results allow selecting the most suitable buffer layer to be deposited in order to reach the required cladding performance in service

  19. The application of imperialist competitive algorithm for optimization of deposition rate in submerged arc welding process using TiO{sub 2} nano particle

    Energy Technology Data Exchange (ETDEWEB)

    Ghaderi, Mohammad Reza; Eslampanah, Amirhossein; Ghaderi, Kianoosh [Islamic Azad University, Sanandaj (Iran, Islamic Republic of); Aghakhani, Masood [Razi University, Kermanshah (Iran, Islamic Republic of)

    2015-01-15

    We used a novel optimization algorithm based on the imperialist competitive algorithm (ICA) to optimize the deposition rate in the submerged arc welding (SAW) process. This algorithm offers some advantages such as simplicity, accuracy and time saving. Experiments were conducted based on a five factor, five level rotatable central composite design (RCCD) to collect welding data for deposition rate as a function of welding current, arc voltage, contact tip to plate distance, welding speed and thickness of TiO{sub 2} nanoparticles coated on the plates of mild steel. Furthermore, regression equation for deposition rate was obtained using least squares method. The regression equation as the cost function was optimized using ICA. Ultimately, the levels of input variables to achieve maximum deposition rate were obtained using ICA. Computational results indicate that the proposed algorithm is quite effective and powerful in optimizing the cost function.

  20. The application of imperialist competitive algorithm for optimization of deposition rate in submerged arc welding process using TiO2 nano particle

    International Nuclear Information System (INIS)

    Ghaderi, Mohammad Reza; Eslampanah, Amirhossein; Ghaderi, Kianoosh; Aghakhani, Masood

    2015-01-01

    We used a novel optimization algorithm based on the imperialist competitive algorithm (ICA) to optimize the deposition rate in the submerged arc welding (SAW) process. This algorithm offers some advantages such as simplicity, accuracy and time saving. Experiments were conducted based on a five factor, five level rotatable central composite design (RCCD) to collect welding data for deposition rate as a function of welding current, arc voltage, contact tip to plate distance, welding speed and thickness of TiO 2 nanoparticles coated on the plates of mild steel. Furthermore, regression equation for deposition rate was obtained using least squares method. The regression equation as the cost function was optimized using ICA. Ultimately, the levels of input variables to achieve maximum deposition rate were obtained using ICA. Computational results indicate that the proposed algorithm is quite effective and powerful in optimizing the cost function.

  1. Optimisation of the FeMn and ZnO production from spent pyrolised primary batteries. Feasibility of a DC-submerged arc furnace process

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Alvarado, R.; Friedrich, B. [RWTH Aachen (Germany). IME Process Metallurgy and Metal Recycling

    2008-07-01

    In the present work the feasibility to produce a Fe-Mn-alloy and a ZnO-concentrate from spent pyrolised primary batteries has been investigated based on fundamental research, already reported in 'World of Metallurgy' - ERZ-METALL 1/2007. Through a carbothermic reduction in a Direct Current Submerged Arc Furnace process (DC-SAF) at IME Aachen, several laboratory-scale as well as semi-pilot scale tests were conducted with three different slag-compositions using solid- and hollow-electrode technique. The process was theoretically modelled with the thermochemical package FactSage 5.3.1. The effect of the process parameters temperature, slag composition and carbon addition were analysed. The results show that it is possible to recycle spent primary batteries through the submerged arc route to obtain a Fe-Mn alloy with a ratio Mn/Fe>1 and a ZnO concentrate as a separated product, reaching recycling quotes for Mn between 44 and 62%, for Fe between 56 and 96% and for zinc of more than 90%. (orig.)

  2. On dryout heat flux and pressure drop of a submerged inductively heated bed flow from below

    International Nuclear Information System (INIS)

    Tsai, F.F.; Catton, I.

    1983-01-01

    An experimental investigation of dryout heat flux in a saturated porous medal with forced flow from below has been conducted using methanol as a coolant. The mass flux varied from 0 to 0.557 kg/m 2 sec. Particle sizes were 590-790 μm, 1.6 mm, 3.2 mm, and 4.8 mm. The dryout heat flux increases as the mass flux increases, and asymptotically goes to the total evaporation energy of the inlet flow. The pressure drop across the bed changed very rapidly near the dryout point due to the formation of dry zone

  3. Cake formation and consolidation: main factors governing the applicable flux in anaerobic submerged membrane bioreactors (AnSMBR) treating acidified wastewater

    NARCIS (Netherlands)

    Jeison, D.; Lier, van J.B.

    2007-01-01

    A laboratory scale anaerobic submerged membrane bioreactor (AnSMBR) was operated for over 200 days, with a volatile fatty acid mixture as substrate. Gas sparging was used for mixing and to provide membrane surface shear. Results show that cake formation was entirely governing the applicable flux.

  4. Characteristics of membrane fouling in submerged membrane bioreactor under sub-critical flux operation.

    Science.gov (United States)

    Su, Y C; Huang, C P; Pan, Jill R; Lee, H C

    2008-01-01

    Recently, the membrane bioreactor (MBR) process has become one of the novel technologies to enhance the performance of biological treatment of wastewater. Membrane bioreactor process uses the membrane unit to replace a sediment tank, and this can greatly enhance treatment performance. However, membrane fouling in MBR restricts its widespread application because it leads to permeate flux decline, making more frequent membrane cleaning and replacement necessary, which then increases operating and maintenance costs. This study investigated the sludge characteristics in membrane fouling under sub-critical flux operation and also assessed the effect of shear stress on membrane fouling. Membrane fouling was slow under sub-critical flux operation. However, as filamentous microbes became dominant in the reactor, membrane fouling increased dramatically due to the increased viscosity and polysaccharides. A close link was found between membrane fouling and the amount of polysaccharides in soluble EPS. The predominant resistance was the cake resistance which could be minimized by increasing the shear stress. However, the resistance of colloids and solutes was not apparently reduced by increasing shear stress. Therefore, smaller particles such as macromolecules (e.g. polysaccharides) may play an important role in membrane fouling under sub-critical flux operation.

  5. Groundwater fluxes into a submerged sinkhole area, Central Italy, using radon and water chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Tuccimei, P. [Dipartimento di Scienze Geologiche, Universita ' Roma Tre' , Largo San Leonardo Murialdo 1, 00146 Rome (Italy)]. E-mail: tuccimei@uniroma3.it; Salvati, R. [Dipartimento di Scienze Geologiche, Universita ' Roma Tre' , Largo San Leonardo Murialdo 1, 00146 Rome (Italy); Capelli, G. [Dipartimento di Scienze Geologiche, Universita ' Roma Tre' , Largo San Leonardo Murialdo 1, 00146 Rome (Italy); Delitala, M.C. [Dipartimento di Scienze Geologiche, Universita ' Roma Tre' , Largo San Leonardo Murialdo 1, 00146 Rome (Italy); Primavera, P. [Dipartimento di Scienze Geologiche, Universita ' Roma Tre' , Largo San Leonardo Murialdo 1, 00146 Rome (Italy)

    2005-10-15

    The groundwater contribution into Green Lake and Black Lake (Vescovo Lakes Group), two cover collapse sinkholes in Pontina Plain (Central Italy), was estimated using water chemistry and a {sup 222}Rn budget. These data can constrain the interactions between sinkholes and deep seated fluid circulation, with a special focus on the possibility of the bedrock karst aquifer feeding the lake. The Rn budget accounted for all quantifiable surface and subsurface input and output fluxes including the flux across the sediment-water interface. The total value of groundwater discharge into Green Lake and Black Lake ({approx}540 {+-} 160 L s{sup -1}) obtained from the Rn budget is lower than, but comparable with historical data on the springs group discharge estimated in the same period of the year (800 {+-} 90 L s{sup -1}). Besides being an indirect test for the reliability of the Rn-budget 'tool', it confirms that both Green and Black Lake are effectively springs and not simply 'water filled' sinkholes. New data on the water chemistry and the groundwater fluxes into the sinkhole area of Vescovo Lakes allows the assessment of the mechanism responsible for sinkhole formation in Pontina Plain and suggests the necessity of monitoring the changes of physical and chemical parameters of groundwater below the plain in order to mitigate the associated risk.

  6. Groundwater fluxes into a submerged sinkhole area, Central Italy, using radon and water chemistry

    International Nuclear Information System (INIS)

    Tuccimei, P.; Salvati, R.; Capelli, G.; Delitala, M.C.; Primavera, P.

    2005-01-01

    The groundwater contribution into Green Lake and Black Lake (Vescovo Lakes Group), two cover collapse sinkholes in Pontina Plain (Central Italy), was estimated using water chemistry and a 222 Rn budget. These data can constrain the interactions between sinkholes and deep seated fluid circulation, with a special focus on the possibility of the bedrock karst aquifer feeding the lake. The Rn budget accounted for all quantifiable surface and subsurface input and output fluxes including the flux across the sediment-water interface. The total value of groundwater discharge into Green Lake and Black Lake (∼540 ± 160 L s -1 ) obtained from the Rn budget is lower than, but comparable with historical data on the springs group discharge estimated in the same period of the year (800 ± 90 L s -1 ). Besides being an indirect test for the reliability of the Rn-budget 'tool', it confirms that both Green and Black Lake are effectively springs and not simply 'water filled' sinkholes. New data on the water chemistry and the groundwater fluxes into the sinkhole area of Vescovo Lakes allows the assessment of the mechanism responsible for sinkhole formation in Pontina Plain and suggests the necessity of monitoring the changes of physical and chemical parameters of groundwater below the plain in order to mitigate the associated risk

  7. Irradiated dynamic fracture toughness of ASTM A533, Grade B, Class 1 steel plate and submerged arc weldment. Heavy section steel technology program technical report No. 41

    International Nuclear Information System (INIS)

    Davidson, J.A.; Ceschini, L.J.; Shogan, R.P.; Rao, G.V.

    1976-10-01

    As a result of the Heavy Section Steel Technology Program (HSST), sponsored by the Nuclear Regulatory Commission, Westinghouse Electric Corporation conducted dynamic fracture toughness tests on irradiated HSST Plate 02 and submerged arc weldment material. Testing performed at the Westinghouse Research and Development Laboratory in Pittsburgh, Pennsylvania, included 0.394T compact tension, 1.9T compact tension, and 4T compact tension specimens. This data showed that, in the transition region, dynamic test procedures resulted in lower (compared to static) fracture toughness results, and that weak direction (WR) oriented specimen data were lower than the strong direction (RW) oriented specimen results. Irradiated lower-bound fracture toughness results of the HSST Program material were well above the adjusted ASME Section III K/sub IR/ curve. An irradiated and nonirradiated 4T-CT specimen was tested during a fracture toughness test as a preliminary study to determine the effect of irradiation on the acoustic emission-stress intensity factor relation in pressure vessel grade steel. The results indicated higher levels of acoustic emission activity from the irradiated sample as compared to the unirradiated one at a given stress intensity factor (K) level

  8. Experimental study on effect of flux composition on element transfer ...

    Indian Academy of Sciences (India)

    BRIJPAL SINGH

    2018-03-10

    Mar 10, 2018 ... 3 Division of Manufacturing Processes and Automation Engineering, Netaji Subhas Institute of ... Submerged arc welding; basicity index; element transfer; slag metal reactions; oxidizing power of ... flux composition, wire and base plate composition. ..... increase in BI of the flux with increasing NiO additive. If.

  9. Relationships between Microbial Activities and Subduction-related Outgassing and Volatile Flux at Aleutian Arc Volcanoes

    Science.gov (United States)

    Miller, H.; Lopez, T. M.; Fischer, T. P.; Schrenk, M. O.

    2016-12-01

    Subduction-related processes, including the movement and alteration of carbon compounds, are an important component of global geochemical cycles. Actively degassing volcanoes of the Aleutian Island arc offer interesting opportunities to not only characterize the composition and abundance of volatiles, but also to identify the origin of the discharging gases (e.g. mantle, organic matter, or carbonates). Taking this approach a step further, microbial activities in and around volcanic fumarole areas may impact the composition and flux of reduced volcanic gases, either through their modification or their assimilation into fixed biomass. Microbiological studies of these systems can be used to develop predictive models to complement those based upon geochemical data while providing greater understanding of the causal relationships between microbial populations and their environment, and ultimately refine estimates of volcanic outgassing. Coupled fumarole soil and gas samples were collected from several Aleutian Island volcanoes in 2015 (Gareloi, Kanaga, Kiska, Little Sitkin) and 2016 (Okmok, Resheschnoi). DNA was extracted from the soil and used to describe microbial community composition, while gas samples were analyzed through chromatography and mass spectrometry. Preliminary data suggests a relationship between the abundance of specific groups of prokaryotes known to metabolize reduced gases, such as sulfur-oxidizers and methanotrophs, and the abundances of the degassing volatiles, including sulfur dioxide and methane. Ongoing studies aimed at investigating the relationship between the genomic composition of the fumarolic microbial community and the physical and chemical properties of the soil (i.e. mineralogy, bulk geochemistry, nutrient concentration, gas flux, and environmental measurements) are underway. These data will be used to evaluate the potential for microbial communities to remove volcanic carbon and store it as biomass, or to modify the volatile carbon

  10. Gaseous Shielding Gas Additives as Flux Substitute for TIG Arc Brazing

    Directory of Open Access Journals (Sweden)

    Uwe Reisgen

    2015-09-01

    Full Text Available Abstract Brazing is one of the key technologies in the field of joining of metal components. To improve the wetting of brazing material and work-piece surface, it is often required to fall back on the use of flux. The application of these substances requires accuracy and is often connected with considerable expenditure and it is, just as the removal of flux residues, often an additional working step which has to be carried out manually. Within the framework of a DFG research project it has been investigated to which degree gaseous substances as addition to the shielding gas may replace conventional flux in TIG arc brazing. To this end, investigations have been carried out using different combinations of base and filler materials. Mainly monosilane as a gaseous flux substitute has been added in low concentrations to the shielding gas volume flow. The resulting brazed joints have been quantified with regard to their geometry, their fusion conditions and their chemical compositions. These qualities were then correlated and evaluated with the provided quantity of monosilane in order to identify dependencies.

  11. Influence of the composition and microstructure on the mechanical properties of single pass weld metal obtained with two-run multipower submerged arc welding of 35 MM Fe 510 quality steels

    International Nuclear Information System (INIS)

    Berkhout, C.F.; Sipkes, M.P.

    1977-01-01

    For three 35 mm Fe 510 quality steels (with and without niobium) experiments have been carried out to establish a relationship between composition, microstructure and mechanical properties of weldmetal obtained with two-run multipower submerged arc welding. The most striking aspects are summarized in the following. The weldmental composition can influence the toughness both, directly by matrix alloying or indirectly through the grainsize and constituents of the microstructure such as the perlite-cementite and martensite fraction. In the range of compositions investigated Mn for instance has a beneficial, while Nb and N have a detrimental effect on notch toughness. For nitrogen the concentration in the weldmetal is determined by the type of weldingflux used. The unfavourable effect of Nb in the weldmetal depends mainly on the Nb content of the plate material (dilution effect). Niobium introduced by the flux is not active and in all probability only present as non metallic inclusions. Remarkable is the strong interaction found between Nb and N. The influence of Nb decreases when the N content of the weldmetal increases. This effect may probably also be an explanation for the great differences in the interpretation of the influence of Nb on weldmetal ductility as mentioned in the literature. A change in the concentration of these elements does not have any influence on the grainsize of the weldmetal. The influence of Mo is quite remarkable. In the first place it has a grain-refining effect, which strongly predominates its detrimental effect in promoting the martensite formation. From quantitative measurements it also appears that Mo reduces the amount of perlite in the weldmetal and suppresses entirely the influence of Mn on the Charpy-V transition temperature and the uppershelf-energy level

  12. Calorimeter probes for measuring high thermal flux. [in electric-arc jet facilities for planetary entry heating simulation

    Science.gov (United States)

    Russell, L. D.

    1979-01-01

    The paper describes expendable, slug-type calorimeter probes developed for measuring high heat-flux levels of 10-30 kW/sq cm in electric-arc jet facilities. The probes are constructed with thin tungsten caps mounted on Teflon bodies; the temperature of the back surface of the tungsten cap is measured, and its rate of change gives the steady-state, absorbed heat flux as the calorimeter probe heats to destruction when inserted into the arc jet. It is concluded that the simple construction of these probes allows them to be expendable and heated to destruction to obtain a measurable temperature slope at high heating rates.

  13. Irradiation effects on fracture toughness of two high-copper submerged-arc welds, HSSI series 5

    International Nuclear Information System (INIS)

    Nanstad, R.K.; Haggag, F.M.; McCabe, D.E.; Iskander, S.K.; Bowman, K.O.; Menke, B.H.

    1992-10-01

    The Fifth Irradiation Series in the Heavy-Section Steel irradiation (HSSI) Program was aimed at obtaining a statistically significant fracture toughness data base on two weldments with high-copper contents to determine the shift and shape of the K lc curve as a consequence of irradiation. The program included irradiated Charpy V-notch impact, tensile, and drop-weight specimens in addition to compact fracture toughness specimens. Compact specimens with thicknesses of 25.4, 50.8, and 101.6 mm [1T C(T), 2T C(T), and 4T C(T), respectively] were irradiated. Additionally, unirradiated 6T C(T) and 8T C(T) specimens with the same K lc measuring capacity as the irradiated specimens were tested. The materials for this irradiation series were two weldments fabricated from special heats of weld wire with copper added to the melt. One lot of Linde 0124 flux was used for all the welds. Copper levels for the two welds are 0.23 and 0.31 wt %, while the nickel contents for both welds are 0.60 wt %. Twelve capsules of specimens were irradiated in the pool-side facility of the Oak Ridge Research Reactor at a nominal temperature of 288 degree C and an average fluence of about 1.5 x 10 19 neutrons/cm 2 (> 1 MeV). This volume, Appendices E and F, contains the load-displacement curves and photographs of the fracture toughness specimens from the 72W weld (0.23 wt % Cu) and the 73 W weld (0.31 wt % Cu), respectively

  14. Weld metal microstructures of hardfacing deposits produced by self-shielded flux-cored arc welding

    International Nuclear Information System (INIS)

    Dumovic, M.; Monaghan, B.J.; Li, H.; Norrish, J.; Dunne, D.P.

    2015-01-01

    The molten pool weld produced during self-shielded flux-cored arc welding (SSFCAW) is protected from gas porosity arising from oxygen and nitrogen by reaction ('killing') of these gases by aluminium. However, residual Al can result in mixed micro-structures of δ-ferrite, martensite and bainite in hardfacing weld metals produced by SSFCAW and therefore, microstructural control can be an issue for hardfacing weld repair. The effect of the residual Al content on weld metal micro-structure has been examined using thermodynamic modeling and dilatometric analysis. It is concluded that the typical Al content of about 1 wt% promotes δ-ferrite formation at the expense of austenite and its martensitic/bainitic product phase(s), thereby compromising the wear resistance of the hardfacing deposit. This paper also demonstrates how the development of a Schaeffler-type diagram for predicting the weld metal micro-structure can provide guidance on weld filler metal design to produce the optimum microstructure for industrial hardfacing applications.

  15. Rotating Arc Jet Test Model: Time-Accurate Trajectory Heat Flux Replication in a Ground Test Environment

    Science.gov (United States)

    Laub, Bernard; Grinstead, Jay; Dyakonov, Artem; Venkatapathy, Ethiraj

    2011-01-01

    Though arc jet testing has been the proven method employed for development testing and certification of TPS and TPS instrumentation, the operational aspects of arc jets limit testing to selected, but constant, conditions. Flight, on the other hand, produces timevarying entry conditions in which the heat flux increases, peaks, and recedes as a vehicle descends through an atmosphere. As a result, we are unable to "test as we fly." Attempts to replicate the time-dependent aerothermal environment of atmospheric entry by varying the arc jet facility operating conditions during a test have proven to be difficult, expensive, and only partially successful. A promising alternative is to rotate the test model exposed to a constant-condition arc jet flow to yield a time-varying test condition at a point on a test article (Fig. 1). The model shape and rotation rate can be engineered so that the heat flux at a point on the model replicates the predicted profile for a particular point on a flight vehicle. This simple concept will enable, for example, calibration of the TPS sensors on the Mars Science Laboratory (MSL) aeroshell for anticipated flight environments.

  16. Critical flux and chemical cleaning-in-place during the long-term operation of a pilot-scale submerged membrane bioreactor for municipal wastewater treatment

    KAUST Repository

    Wei, Chunhai

    2011-01-01

    The critical flux and chemical cleaning-in-place (CIP) in a long-term operation of a pilot-scale submerged membrane bioreactor for municipal wastewater treatment were investigated. Steady filtration under high flux (30 L/(m2 h)) was successfully achieved due to effective membrane fouling control by sub-critical flux operation and chemical CIP with sodium hypochlorite (NaClO) in both trans-membrane pressure (TMP) controlling mode (cleaning with high concentration NaClO of 2000-3000 mg/L in terms of effective chorine was performed when TMP rose to 15 kPa) and time controlling mode (cleanings were performed weekly and monthly respectively with low concentration NaClO (500-1000 mg/L) and high concentration NaClO (3000 mg/L)). Microscopic analysis on membrane fibers before and after high concentration NaClO was also conducted. Images of scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that NaClO CIP could effectively remove gel layer, the dominant fouling under sub-critical flux operation. Porosity measurements indicated that NaClO CIP could partially remove pore blockage fouling. The analyses from fourier transform infrared spectrometry (FTIR) with attenuated total reflectance accessory (ATR) and energy dispersive spectrometer (EDS) demonstrated that protein-like macromolecular organics and inorganics were the important components of the fouling layer. The analysis of effluent quality before and after NaClO CIP showed no obvious effect on effluent quality. © 2010 Elsevier Ltd.

  17. Inverted V's and/or discrete arcs: a three-dimensional phenomenon at boundaries between magnetic flux tubes

    International Nuclear Information System (INIS)

    Atkinson, G.

    1982-01-01

    If discrete arcs and inverted V's are associated with current sheets and the U shaped electric potential structure, then existing two-dimensional models are probably inadequate. The rapid east-west electric-field associated flow in the arms of the U shaped potential structure requires that there must be a substantial inflow to the outflow from each arm somewhere along the system since arcs and inverted V's have a limited east-west extent. Thus strong north-south polarization currents occur as the plasma enters and leaves the arms of the U. It is hypothesized that these currents, determine the north-south thickness. Three representative three-dimensional models are considered in which the current sheets are either tangential or rotational discontinuities modified by the U shaped potential structure. Thicknesses of the order of a few tens of kilometers are obtained. The occurence and type of discontinuity expected at various locations in the magnetosphere are considered. Discontinuities and hence inverted V's and/or arcs are expected at the interface between open and closed field lines, which explains quiet time polar cap sun-aligned arcs, and at interfaces between plasmas which have merged or been injected on the dayside or reconnected on the nightside in different impulsive events. The last two account for arcs occurring near the throat at active times and for parallel arcs within the oval. The occurrence of long parallel arcs within the oval is encouraged by the convective flow pattern and by the differences in precipitation from flux tubes with differential histories

  18. Study and development of solid fluxes for gas tungsten arc welding applied to titanium and its alloys and stainless steels

    International Nuclear Information System (INIS)

    Perry, N.

    2000-06-01

    Gas Tungsten Arc Welding uses an electric arc between the refractory tungsten electrode and the plates to be welded under an argon shielding gas. As a result, the joint quality is excellent, no pollution nor defects are to be feared, consequently this process is used in nuclear, aeronautic, chemical and food industries. Despite of this good qualities, GTAW is limited because of, on the one side, a poor penetrating weld pool and, on the other side, a week productivity rate. Indeed, up to 3 mm thick plates, machining and filler metal is needed. Multiple runs increase the defect's risks, the manufactory time and increase the deformations and the heat affected zone. The goal of this study is to break through this limits without any device investment. Active GTA welding (or ATIG) is a new technique with GTA device and an activating flux to be spread on the upper plate before welding. The arc, by plasma electrochemical equilibrium modifications, and the pool with the inner connective flows inversion, allow 7 mm thick joints in one run without edges machining or filler metal for both stainless steel and titanium alloys. This manuscript describes the development of these fluxes, highlights the several phenomena and presents the possibilities of this new process. This work, in collaboration with B.S.L. industries, leads to two flux formulations (stainless steel and titanium alloys) now in a commercial phase with CASTOLIN S.A. Moreover, B.S.L.industries produces a pressure device (nitrate column) with the ATIG process using more than 2800 ATIG welds. (author)

  19. New algorithm for controlling electric arc furnaces using their vibrational and acoustic characteristics

    Science.gov (United States)

    Cherednichenko, V. S.; Bikeev, R. A.; Serikov, V. A.; Rechkalov, A. V.; Cherednichenko, A. V.

    2016-12-01

    The processes occurring in arc discharges are analyzed as the sources of acoustic radiation in an electric arc furnace (EAF). Acoustic vibrations are shown to transform into mechanical vibrations in the furnace laboratory. The shielding of the acoustic energy fluxes onto water-cooled wall panels by a charge is experimentally studied. It is shown that the rate of charge melting and the depth of submergence of arc discharges in the slag and metal melt can be monitored by measuring the vibrational characteristics of furnaces and using them in a universal industrial process-control system, which was developed for EAFs.

  20. Advanced characterization techniques in understanding the roles of nickel in enhancing strength and toughness of submerged arc welding high strength low alloy steel multiple pass welds in the as-welded condition

    Science.gov (United States)

    Sham, Kin-Ling

    Striving for higher strength along with higher toughness is a constant goal in material properties. Even though nickel is known as an effective alloying element in improving the resistance of a steel to impact fracture, it is not fully understood how nickel enhances toughness. It was the goal of this work to assist and further the understanding of how nickel enhanced toughness and maintained strength in particular for high strength low alloy (HSLA) steel submerged arc welding multiple pass welds in the as-welded condition. Using advanced analytical techniques such as electron backscatter diffraction, x-ray diffraction, electron microprobe, differential scanning calorimetry, and thermodynamic modeling software, the effect of nickel was studied with nickel varying from one to five wt. pct. in increments of one wt. pct. in a specific HSLA steel submerged arc welding multiple pass weldment. The test matrix of five different nickel compositions in the as-welded and stress-relieved condition was to meet the targeted mechanical properties with a yield strength greater than or equal to 85 ksi, a ultimate tensile strength greater than or equal to 105 ksi, and a nil ductility temperature less than or equal to -140 degrees F. Mechanical testing demonstrated that nickel content of three wt. pct and greater in the as-welded condition fulfilled the targeted mechanical properties. Therefore, one, three, and five wt. pct. nickel in the as-welded condition was further studied to determine the effect of nickel on primary solidification mode, nickel solute segregation, dendrite thickness, phase transformation temperatures, effective ferrite grain size, dislocation density and strain, grain misorientation distribution, and precipitates. From one to five wt. pct nickel content in the as-welded condition, the primary solidification was shown to change from primary delta-ferrite to primary austenite. The nickel partitioning coefficient increased and dendrite/cellular thickness was

  1. A mass spectrographic investigation of the methods for obtaining quantitative analyses for the mass balance of P and B through a submerged arc silicon smelter

    International Nuclear Information System (INIS)

    Rogers, D.E.C.; Jones, D.S.; Wegman, J.W.; Brain, L.; Van Wamelen, J.

    1983-11-01

    Mass spectrographic analyses of silica, silicon and silica reducing agents have been made using an arc discharge mass spectrograph. Analyses of certified standards and standard mixtures are given. An evaluation of doping techniques shows that the solid doping technique is satisfactory and that the liquid doping technique leads to significant errors. The amount of liquid dopant absorbed onto the substrate matrix varied from one compound to another and from one matrix to another. Comparison of analyses of solid-doped and undoped certified standards shows that all of the solid dopant is taken up by the sample. Analysis of silica reducing agents used in the arc reduction furnace shows that the major source of contamination by B and P is likely to be the coal and wood. Silica contains 0.4 ppm of B and 4 ppm of P and is a minor source of contamination. The levels in silicon are about 10 ppm for B and 20 ppm for P. A mass balance on P cannot be made and the missing amount is larger than the inaccuracy of the analysis. For analyses of feedstocks where the smelter outlet fumes are not sampled an accuracy of analysis to a factor of two is sufficient for the analysis of the coal and wood chips

  2. U-Series disequilibria, magma petrogenesis and flux rates along the depleted Tonga-Kermadec Island Arc

    International Nuclear Information System (INIS)

    Turner, S.; Hawkesworth, C.; Rogers, N.; Bartlett, J.; Smith, I.; Worthington, T.; Smith, I.; Worthington, T.

    1997-01-01

    The fluid contribution to the lava source has been calculated as -1 ppm Rb, 10 ppm Ba, 0.02 ppm U, 600 ppm K 0.2 ppm Pb and 30 ppm Sr. It has 87 Sr/ 86 Sr = 0.7035 and 206 Pb/ 204 Pb = 18.5 and thus is inferred to be derived from dehydration of the subducting altered oceanic crust. U-Th isotope disequilibria reflect the time since fluid release from the subducting slab and a pseudo-isochron through the lowest ( 230 Th/ 232 Th) lavas constrains this to be ∼ 50 000 yr. Significantly, U-Th isotope data record similar timescales in the Lesser Antilles (∼40 000 yr, Turner et al., 1996) and in the Marianas (30 000 yr, Elliott et al., 1996) which provides encouragement that these data reflect some general aspect of the flux rates beneath island arcs. Large 226 Ra excesses have also been reported from Tonga-Kermadec (( 226 Ra/ 230 Th) = 1.5-3.0, Gill and Williams, 1990). Since 226 Ra will return to secular equilibrium with 230 Th (( 226 Ra/ 230 Th) = 1) within 7500 yr of Ra/Th fractionation the 238 U/ 230 Th and 226 Ra/ 230 Th disequilibria are clearly decoupled (see also Turner et al., 1996). This is an unexpected result and clearly the 226 Ra/ 230 Th disequilibria must have developed after the process responsible for the major U/Th fractionation. It is suggested that Th-Ra isotope disequilibria record the time since partial melting and thus indicate rapid channelled magma ascent. Olivine gabbro xenoliths from Raoul are interpreted as cumulates to their host lavas with which they form zero age U-Th isochrons indicating that minimal time was spent in magma chambers. The subduction signature is not observed in lavas from the back arc island of Niuafo'ou and thus does not penetrate as far 200 km beyond the arc front volcanoes. These were derived from partial melting of fertile peridotite at 130-160 km depth with melt rates around 2 x 10 -4 kg m -3 yr -1 , possibly due to volatiles released from the breakdown of phengite and lawsonite in the underlying slab at 200 km

  3. Searching for conditions of observation of subduction seismogenic zone transients on Ocean Bottom Seismometers deployed at the Lesser Antilles submerged fore-arc

    Science.gov (United States)

    Bécel, Anne; Laigle, Mireille; Diaz, Jordi; Hirn, Alfred; Flueh, Ernst; Charvis, Philippe

    2010-05-01

    In the frame of the European Union « THALES WAS RIGHT » and French ANR CATTELL SUBSISMANTI funding, an unprecedented array of 80 OBS, Ocean Bottom Seismometers of Géoazur Nice, INSU/IPGP Paris, IfM-GEOMAR Kiel, AWI Bremerhaven could gathered. They have been deployed for continuous recording over four months on the fore-arc domain of the Lesser Antilles subduction zone offshore Martinique, Dominica, Guadeloupe and Antigua Islands, by scientific cruises of N/O ATALANTE, F/S M. A. MERIAN and N/O ANTEA. One of the aims of this OBS array was the feasibility study of detecting at sea-bottom the seismological part of recently discovered phenomena such as NVT non-volcanic tremors and LP, for Long-Period events. The ability of detecting such transient signals is of importance, since they are possibly related to potential mega-thrust earthquakes and their preparation zone. At the Lesser Antilles subduction zone, the fore-arc domain overlying the seismogenic part of the interplate is located offshore, covered by as much as 4000 m of water. In this case, transient signals can be accessible only from OBS observations. Hence, there is a major difference, in the sense of the instrumental and logistical effort, with the subductions under NW US-Canada and under Central Japan where these signals have been discovered. There, the subduction zones have an emerged fore-arc that has allowed the chance discovery of those phenomena by regular instrument maintained routinely on land. Over 20 of the instruments were BB-OBS, with broadband seismic sensors, possibly the largest such gathering at the time of the experiment among the OBS types. Among those broadband OBS designed or used by different Institutions, there were at least three different seismometer brands and acoustical sensors, as well as different mechanical mounting and technical solutions for coupling them to ground. This did not facilitate data recovery and processing, but on the other hand, as planned by interweaving the

  4. Legirani praški za navarjanje z večžično elektrodo: Alloyed fluxes for surfacing with multiple - wire electrode:

    OpenAIRE

    Kejžar, Božena; Kejžar, Rajko

    1997-01-01

    Submerged arc surfacing with alloyed agglomerated fluxes permits unalloyed and low-alloy structural steels to be surfaced in one layer of high-alloyed claddings. Surfacing dilution produced by fusion of the parent metal, and burn-off of alloying elements are substituted by additional alloying by means of a welding flux, which is, in the case of the above-mentioned surfacing processes, the main carrier of alloying elements for surfacing alloying. With alloyed agglomerated fluxes, it is recomme...

  5. US State Submerged Lands

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Submerged Lands Act (43 U.S.C. Section 1301 et seq.) grants coastal states title to natural resources located within their coastal submerged lands and navigable...

  6. Miocene-Recent sediment flux in the south-central Alaskan fore-arc basin governed by flat-slab subduction

    Science.gov (United States)

    Finzel, Emily S.; Enkelmann, Eva

    2017-04-01

    The Cook Inlet in south-central Alaska contains the early Oligocene to Recent stratigraphic record of a fore-arc basin adjacent to a shallowly subducting oceanic plateau. Our new measured stratigraphic sections and detrital zircon U-Pb geochronology and Hf isotopes from Neogene strata and modern rivers illustrate the effects of flat-slab subduction on the depositional environments, provenance, and subsidence in fore-arc sedimentary systems. During the middle Miocene, fluvial systems emerged from the eastern, western, and northern margins of the basin. The axis of maximum subsidence was near the center of the basin, suggesting equal contributions from subsidence drivers on both margins. By the late Miocene, the axis of maximum subsidence had shifted westward and fluvial systems originating on the eastern margin of the basin above the flat-slab traversed the entire width of the basin. These mud-dominated systems reflect increased sediment flux from recycling of accretionary prism strata. Fluvial systems with headwaters above the flat-slab region continued to cross the basin during Pliocene time, but a change to sandstone-dominated strata with abundant volcanogenic grains signals a reactivation of the volcanic arc. The axis of maximum basin subsidence during late Miocene to Pliocene time is parallel to the strike of the subducting slab. Our data suggest that the character and strike-orientation of the down-going slab may provide a fundamental control on the nature of depositional systems, location of dominant provenance regions, and areas of maximum subsidence in fore-arc basins.

  7. Flux

    DEFF Research Database (Denmark)

    Ravn, Ib

    . FLUX betegner en flyden eller strømmen, dvs. dynamik. Forstår man livet som proces og udvikling i stedet for som ting og mekanik, får man et andet billede af det gode liv end det, som den velkendte vestlige mekanicisme lægger op til. Dynamisk forstået indebærer det gode liv den bedst mulige...... kanalisering af den flux eller energi, der strømmer igennem os og giver sig til kende i vore daglige aktiviteter. Skal vores tanker, handlinger, arbejde, samvær og politiske liv organiseres efter stramme og faste regelsæt, uden slinger i valsen? Eller skal de tværtimod forløbe ganske uhindret af regler og bånd...

  8. Use of flux welding slag of the Mn-O-SiO2 system for the obtaining of a new alloyed agglomerated flux

    International Nuclear Information System (INIS)

    Cruz, A.; Quintana, R.; Garcia, L. L.; Perdomo, L.; Jimenez, G.; Gomez, C. R.; Alguacil, F. J.; Cores, A.

    2005-01-01

    This paper deals with the use of welding slags of the MnO-SiO 2 system fluxes, coming from the recovering by means of the submerged arc welding in the manufacturing of agglomerated fluxes for surfacing with the same propose. the composition of the matrix is studied by means of an experimental design in a restricted area of the Mc Lean Anderson kind, the technological behaviour of the different mixtures is checked, and the results of the best types that have alloy charges included are analysed by a characterization of the weld. (Author) 20 refs

  9. Use of the gapped bead-on-plate test to investigate hydrogen induced cracking of flux cored arc welds of a quenched and tempered steel

    International Nuclear Information System (INIS)

    Chen, Liang; Dunne, Druce; Davidson, Len

    2014-01-01

    Gapped bead-on-plate (G-BOP) testing of flux cored arc welds was conducted to assess the susceptibility to hydrogen induced cold cracking (HICC) of weld metal deposited on a high strength quenched and tempered steel. For preheat temperatures higher than 40°C, no weld metal cracking was observed using a shielding gas consisting of argon with 20% carbon dioxide. In contrast, the no-crack condition was not achieved for a shielding gas consisting of argon-5% carbon dioxide for preheat temperatures lower than 100°C. This extraordinary difference in weld metal HICC resistance indicates that, in general, the shielding gas mixture can exert a major influence on weld metal transverse cold cracking behaviour

  10. Optimization of submerged vane parameters

    Indian Academy of Sciences (India)

    H Sharma

    the height or length of the submerged vane, no effective change in bed profile .... easily and again vanes will be ineffective, which is what. Odgaard and .... [3] Odgaard A J and Wang Y 1991a Sediment management with submerged vanes.

  11. Torque Ripple Reduction of a Novel Modular Arc-Linear Flux-Switching Permanent-Magnet Motor with Rotor Step Skewing

    Directory of Open Access Journals (Sweden)

    Xiangdong Liu

    2016-05-01

    Full Text Available A novel modular arc-linear flux-switching permanent-magnet motor (MAL-FSPM used for scanning system instead of reduction gearboxes and kinematic mechanisms is proposed and researched in this paper by the finite element method (FEM. The MAL-FSPM combines characteristics of flux-switching permanent-magnet motor and linear motor and can realize the direct driving and limited angular movement. Structure and operation principle of the MAL-FSPM are analyzed. Cogging torque model of the MAL-FSPM is established. The characteristics of cogging torque and torque ripple are investigated for: (1 distance (dend between left end of rotor and left end of stator is more than two rotor tooth pitch (τp; and (2 dend is less than two rotor tooth pitch. Cogging torque is an important component of torque ripple and the period ratio of the cogging torque to the back electromotive force (EMF equals one for the MAL-FSPM before optimization. In order to reduce the torque ripple as much as possible and affect the back EMF as little as possible, influence of period ratio of cogging torque to back EMF on rotor step skewing is investigated. Rotor tooth width and stator slot open width are optimized to increase the period ratio of cogging torque to back EMF. After the optimization, torque ripple is decreased by 79.8% for dend > τp and torque ripple is decreased by 49.7% for dend < τp. Finally, 3D FEM model is established to verify the 2D results.

  12. production of manual arc welding electrodes with local raw materials

    African Journals Online (AJOL)

    CHUKSSUCCESS 4 LOVE

    Manual arc welding using flux coated electrodes is carried out by producing an electric arc between ... major objectives: to form fusible slags, to stabilize the arc and to produce an inert gas shielding ... Current fusion welding techniques rely.

  13. ANALISA ELECTRODE CONSUMABLE TYPE OK AUTROD 12.10 PENGELASAN SUBMERGED ARC WELDING PADA BLOK-BLOK KAPAL DCV 18500 DWT DI PT. JASA MARINA INDAH UNIT II SEMARANG

    Directory of Open Access Journals (Sweden)

    Sukanto Jatmiko

    2012-07-01

    Full Text Available In this globalization era technological advances growed very fast. In shipping industry of development process shipbuilding of principal feedstock to used steel plate, with construction tacking on using welder method.In this research purpose of lifted is know number of requirement (consumable electrode for welder SAW at block-block ship DCV 18500 DWT in PT. Jasa Marina Indah Semarang.At this experiment specimen applied is low carbon steel of type ST 42 with thickness of 12, 13, 14, 17, 19 dan 24 mm. Research is done by the way of making specimen at every plate thickness. Then is done path measurement of length, used electrode length, and weight flux applied at the welder.From result of gauging and data calculation welder at block DB 5(p/c/s, SS5A(p/s, SS 5B(p/s, UD 5C, and TB 102 (p/c/s will be known number of electrodes applied in welder SAW and number of flux used.

  14. Submerged AUV Charging Station

    Science.gov (United States)

    Jones, Jack A.; Chao, Yi; Curtin, Thomas

    2014-01-01

    Autonomous Underwater Vehicles (AUVs) are becoming increasingly important for military surveillance and mine detection. Most AUVs are battery powered and have limited lifetimes of a few days to a few weeks. This greatly limits the distance that AUVs can travel underwater. Using a series of submerged AUV charging stations, AUVs could travel a limited distance to the next charging station, recharge its batteries, and continue to the next charging station, thus traveling great distances in a relatively short time, similar to the Old West “Pony Express.” One solution is to use temperature differences at various depths in the ocean to produce electricity, which is then stored in a submerged battery. It is preferred to have the upper buoy submerged a reasonable distance below the surface, so as not to be seen from above and not to be inadvertently destroyed by storms or ocean going vessels. In a previous invention, a phase change material (PCM) is melted (expanded) at warm temperatures, for example, 15 °C, and frozen (contracted) at cooler temperatures, for example, 8 °C. Tubes containing the PCM, which could be paraffin such as pentadecane, would be inserted into a container filled with hydraulic oil. When the PCM is melted (expanded), it pushes the oil out into a container that is pressurized to about 3,000 psi (approx equals 20.7 MPa). When a valve is opened, the high-pressure oil passes through a hydraulic motor, which turns a generator and charges a battery. The low-pressure oil is finally reabsorbed into the PCM canister when the PCM tubes are frozen (contracted). Some of the electricity produced could be used to control an external bladder or a motor to the tether line, such that depth cycling is continued for a very long period of time. Alternatively, after the electricity is generated by the hydraulic motor, the exiting low-pressure oil from the hydraulic motor could be vented directly to an external bladder on the AUV, such that filling of the bladder

  15. Use of flux welding slag of the Mn-O-SiO{sub 2} system for the obtaining of a new alloyed agglomerated flux; Empleo de escorias de soldadura del sistema MnO-SiO{sub 2} para la obtencion de un nuevo fundente aglomerado aleado

    Energy Technology Data Exchange (ETDEWEB)

    Cruz, A.; Quintana, R.; Garcia, L. L.; Perdomo, L.; Jimenez, G.; Gomez, C. R.; Alguacil, F. J.; Cores, A.

    2005-07-01

    This paper deals with the use of welding slags of the MnO-SiO{sub 2} system fluxes, coming from the recovering by means of the submerged arc welding in the manufacturing of agglomerated fluxes for surfacing with the same propose. the composition of the matrix is studied by means of an experimental design in a restricted area of the Mc Lean Anderson kind, the technological behaviour of the different mixtures is checked, and the results of the best types that have alloy charges included are analysed by a characterization of the weld. (Author) 20 refs.

  16. Filtered cathodic arc source

    International Nuclear Information System (INIS)

    Falabella, S.; Sanders, D.M.

    1994-01-01

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge is described. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45 degree to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles. 3 figures

  17. Submerged Grove in Lake Onogawa

    OpenAIRE

    Sato, Yasuhiro; Nakamura, Soken; Ochiai, Masahiro

    1996-01-01

    Abstract : The first record by ultrasonic echo sounding on the distribution of the submerged standing trees on the bottom of Lake Onogawa is presented. Lake Onogawa is a dammed lake formed at the time of the eruption of the volcano Mt.Bandai in 1888. Since then the original vegetation of the dammed valley has remained submerged. Many submerged standing trees are distributed on the bottom within about 600m from the northeast end of the lake. The density of the trees in this area is sufficient ...

  18. Simultaneous obtention of multicomponent ferroalloy and slag from black sands for the development of electrical arc welding consumables

    International Nuclear Information System (INIS)

    Cruz-Crespo, A.; Gomez-Rodriguez, L.; Garcia-Sanchez, L. L.; Quintana-Puchol, R.; Cerpa-Naranjo, A.; Cores-Sanchez, A.

    2004-01-01

    In this paper, chemical and mineralogical characterizations of the black sands of the Mejias placer of Sagua de Tanamo (the most important beach littoral placer of the northwest of oriental Cuba) are exposed. Starting from these characterizations a calculation strategy is developed for the making of the metallurgical load that allows to obtain simultaneously, when processed by carbothermic reduction in an electrical arc furnace, a multicomponent ferroalloy and a useful slag for the making of electric arch welding consumables. The powder of the obtained slag is agglomerated with liquid glass. The resulting pellets, due to their behavior on the submerged arc welding (SAW) present technological and metallurgical properties that correspond with the requirements of an agglomerated flux matrix. The chemical composition of the multicomponent ferroalloy is constituted by metallic elements of high metallurgical and alloyed values (V, Cr, Mo, Ti, Nb). It is appropriate for the formulation of consumables for manual welding (SMAW) and SAW, as well. (Author) 15 refs

  19. Characterisation of submerged arc welding process using infrared imaging technique

    CSIR Research Space (South Africa)

    Zondi, MC

    2017-09-01

    Full Text Available function of material emissivity, which in turn is affected by the surface condition of the material. a. UKZN PhD Eng. Student, 7 Cordia Crescent, Umhlanga Rocks, Durban, 4043, zondi@outlook.com b. CSIR DPSS, Landward Sciences, yanga...

  20. ARC Operations

    Science.gov (United States)

    coordination on a regular basis. The overall ARC organizational structure is shown below. Organizational Structure Dynamics and Control of Vehicles Human Centered Modeling and Simulation High Performance

  1. Submerged membrane distillation for seawater desalination

    KAUST Repository

    Francis, Lijo; Ghaffour, NorEddine; Alsaadi, Ahmad Salem; Amy, Gary L.

    2014-01-01

    A submerged membrane distillation (SMD) process for fresh water production from Red Sea water using commercially available hollow fiber membranes has been successfully employed and compared with the conventional direct contact membrane distillation (DCMD) process. The hollow fiber membranes have been characterized for its morphology using field effect scanning electron microscope. In SMD process, a bunch of hollow fiber membranes are glued together at both ends to get a simplified open membrane module assembly submerged into the coolant tank equipped with a mechanical stirrer. Hot feed stream is allowed to pass through the lumen side of the membrane using a feed pump. Continuous stirring at the coolant side will reduce the temperature and concentration polarization. During the conventional DCMD process, using feed-coolant streams with co-current and counter-current flows has been tested and the results are compared in this study. In SMD process, a water vapor flux of 10.2 kg m-2 h-1 is achieved when using a feed inlet temperature of 80°C and coolant temperature of 20°C. Under the same conditions, during conventional DCMD process, a water vapor flux of 11.6 and 10.1 kg m-2 h-1 were observed during counter-current and co-current flow streams, respectively. Results show that the water production in the SMD process is comparable with the conventional DCMD process, while the feed-coolant flow streams are in the co-current direction. During conventional DCMD operation, a 15% increase in the water production is observed when feed-coolant streams are in the counter-current direction compared to the co-current direction. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

  2. Submerged membrane distillation for seawater desalination

    KAUST Repository

    Francis, Lijo

    2014-08-11

    A submerged membrane distillation (SMD) process for fresh water production from Red Sea water using commercially available hollow fiber membranes has been successfully employed and compared with the conventional direct contact membrane distillation (DCMD) process. The hollow fiber membranes have been characterized for its morphology using field effect scanning electron microscope. In SMD process, a bunch of hollow fiber membranes are glued together at both ends to get a simplified open membrane module assembly submerged into the coolant tank equipped with a mechanical stirrer. Hot feed stream is allowed to pass through the lumen side of the membrane using a feed pump. Continuous stirring at the coolant side will reduce the temperature and concentration polarization. During the conventional DCMD process, using feed-coolant streams with co-current and counter-current flows has been tested and the results are compared in this study. In SMD process, a water vapor flux of 10.2 kg m-2 h-1 is achieved when using a feed inlet temperature of 80°C and coolant temperature of 20°C. Under the same conditions, during conventional DCMD process, a water vapor flux of 11.6 and 10.1 kg m-2 h-1 were observed during counter-current and co-current flow streams, respectively. Results show that the water production in the SMD process is comparable with the conventional DCMD process, while the feed-coolant flow streams are in the co-current direction. During conventional DCMD operation, a 15% increase in the water production is observed when feed-coolant streams are in the counter-current direction compared to the co-current direction. © 2014 © 2014 Balaban Desalination Publications. All rights reserved.

  3. Study and development of solid fluxes for gas tungsten arc welding applied to titanium and its alloys and stainless steels; Etude et developpement des flux solides en vue d'application en soudage ATIG applique au titane et ses alliages ainsi qu'aux aciers inoxydables

    Energy Technology Data Exchange (ETDEWEB)

    Perry, N

    2000-06-15

    Gas Tungsten Arc Welding uses an electric arc between the refractory tungsten electrode and the plates to be welded under an argon shielding gas. As a result, the joint quality is excellent, no pollution nor defects are to be feared, consequently this process is used in nuclear, aeronautic, chemical and food industries. Despite of this good qualities, GTAW is limited because of, on the one side, a poor penetrating weld pool and, on the other side, a week productivity rate. Indeed, up to 3 mm thick plates, machining and filler metal is needed. Multiple runs increase the defect's risks, the manufactory time and increase the deformations and the heat affected zone. The goal of this study is to break through this limits without any device investment. Active GTA welding (or ATIG) is a new technique with GTA device and an activating flux to be spread on the upper plate before welding. The arc, by plasma electrochemical equilibrium modifications, and the pool with the inner connective flows inversion, allow 7 mm thick joints in one run without edges machining or filler metal for both stainless steel and titanium alloys. This manuscript describes the development of these fluxes, highlights the several phenomena and presents the possibilities of this new process. This work, in collaboration with B.S.L. industries, leads to two flux formulations (stainless steel and titanium alloys) now in a commercial phase with CASTOLIN S.A. Moreover, B.S.L.industries produces a pressure device (nitrate column) with the ATIG process using more than 2800 ATIG welds. (author)

  4. Study and development of solid fluxes for gas tungsten arc welding applied to titanium and its alloys and stainless steels; Etude et developpement des flux solides en vue d'application en soudage ATIG applique au titane et ses alliages ainsi qu'aux aciers inoxydables

    Energy Technology Data Exchange (ETDEWEB)

    Perry, N

    2000-06-15

    Gas Tungsten Arc Welding uses an electric arc between the refractory tungsten electrode and the plates to be welded under an argon shielding gas. As a result, the joint quality is excellent, no pollution nor defects are to be feared, consequently this process is used in nuclear, aeronautic, chemical and food industries. Despite of this good qualities, GTAW is limited because of, on the one side, a poor penetrating weld pool and, on the other side, a week productivity rate. Indeed, up to 3 mm thick plates, machining and filler metal is needed. Multiple runs increase the defect's risks, the manufactory time and increase the deformations and the heat affected zone. The goal of this study is to break through this limits without any device investment. Active GTA welding (or ATIG) is a new technique with GTA device and an activating flux to be spread on the upper plate before welding. The arc, by plasma electrochemical equilibrium modifications, and the pool with the inner connective flows inversion, allow 7 mm thick joints in one run without edges machining or filler metal for both stainless steel and titanium alloys. This manuscript describes the development of these fluxes, highlights the several phenomena and presents the possibilities of this new process. This work, in collaboration with B.S.L. industries, leads to two flux formulations (stainless steel and titanium alloys) now in a commercial phase with CASTOLIN S.A. Moreover, B.S.L.industries produces a pressure device (nitrate column) with the ATIG process using more than 2800 ATIG welds. (author)

  5. Drought and submergence tolerance in plants

    Energy Technology Data Exchange (ETDEWEB)

    Du, Hewei; Zhou, Yufan; Oksenberg, Nir; Ronald, Pamela

    2017-11-14

    The invention provides methods of genetically modified plants to increase tolerance to drought and/or submergence. The invention additionally provides plants having increased drought and/or submergence tolerance engineered using such methods.

  6. Production of Manual Metal Arc Welding Electrodes with Local Raw ...

    African Journals Online (AJOL)

    Manual arc welding using flux coated electrodes is carried out by producing an electric arc between the base metal and a flux covered metal electrode with electric current that depends on the type of electrode, material, welding position and the desired strength. The composition of flux coated electrodes is complex and a ...

  7. Submerged membrane distillation for desalination of water

    KAUST Repository

    Francis, Lijo; Ghaffour, NorEddine; Alsaadi, Ahmad Salem

    2016-01-01

    Submerged membrane modules for use for desalination of water are disclosed. In one or more aspects, the membrane modules can be submerged either in a feed solution tank or the feed solution can pass through the lumen side of the membrane submerged within the tank. The feed solution can be a water-based feed stream containing an amount of salt.

  8. Submerged membrane distillation for desalination of water

    KAUST Repository

    Francis, Lijo

    2016-10-27

    Submerged membrane modules for use for desalination of water are disclosed. In one or more aspects, the membrane modules can be submerged either in a feed solution tank or the feed solution can pass through the lumen side of the membrane submerged within the tank. The feed solution can be a water-based feed stream containing an amount of salt.

  9. Mechanical properties of API X80 steel pipe joints welded by Flux Core Arc Weld Process; Propriedades mecanicas de juntas de tubos de aco API X80 soldadas com arame tubulares

    Energy Technology Data Exchange (ETDEWEB)

    Ordonez, Robert E. Cooper; Silva, Jose Hilton F.; Trevisan, Roseana E. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia de Fabricacao

    2003-07-01

    Flux Core Arc Welding processes (FCAW) are beginning to be applied in pipeline welds, however, very limited experimental data regarding mechanical properties of pipeline weld joints with these processes are available in the literature. In this paper, the effects of preheat temperature and type of FCAW on mechanical properties (microhardness and tensile strength) of API X80 weld joint steel are presented. FCAW processes with gas protection and self-shielded were used. Multipasses welding were applied in 30'' diameter and 0,625'' thickness tubes. Influence factors were: FCAW type and preheat temperature. Acceptance criteria of welded joints were evaluated by API 1104 standard for tensile strength test and ASTM E384-99 for microhardness test. The results obtained showed that FCAW type and preheat temperature have no influence on mechanical properties of API X80 joint steel. (author)

  10. Investigation of a submerged membrane reactor for continuous biomass hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Malmali, Mohammadmahdi; Stickel, Jonathan; Wickramasinghe, S. Ranil

    2015-10-01

    Enzymatic hydrolysis of cellulose is one of the most costly steps in the bioconversion of lignocellulosic biomass. Use of a submerged membrane reactor has been investigated for continuous enzymatic hydrolysis of cellulose thus allowing for greater use of the enzyme compared to a batch process. Moreover, the submerged 0.65 μm polyethersulfone microfiltration membrane avoids the need to pump a cellulose slurry through an external loop. Permeate containing glucose is withdrawn at pressures slightly below atmospheric pressure. The membrane rejects cellulose particles and cellulase enzyme bound to cellulose. Our proof-of-concept experiments have been conducted using a modified, commercially available membrane filtration cell under low fluxes around 75 L/(m2 h). The operating flux is determined by the rate of glucose production. Maximizing the rate of glucose production involves optimizing mixing, reactor holding time, and the time the feed is held in the reactor prior to commencement of membrane filtration and continuous operation. When we maximize glucose production rates it will require that we operate it at low glucose concentration in order to minimize the adverse effects of product inhibition. Consequently practical submerged membrane systems will require a combined sugar concentration step in order to concentrate the product sugar stream prior to fermentation.

  11. Heat transfer model for quenching by submerging

    International Nuclear Information System (INIS)

    Passarella, D N; Varas, F; MartIn, E B

    2011-01-01

    In quenching by submerging the workpiece is cooled due to vaporization, convective flow and interaction of both mechanisms. The dynamics of these phenomena is very complex and the corresponding heat fluxes are strongly dependent on local flow variables such as velocity of fluid and vapor fraction. This local dependence may produce very different cooling rates along the piece, responsible for inappropriate metallurgical transformations, variability of material properties and residual stresses. In order to obtain an accurate description of cooling during quenching, a mathematical model of heat transfer is presented here. The model is based on the drift-flux mixture-model for multiphase flows, including an equation of conservation of energy for the liquid phase and specific boundary conditions that account for evaporation and presence of vapor phase on the surface of the piece. The model was implemented on Comsol Multiphysics software. Generation of appropriate initial and boundary conditions, as well as numerical resolution details, is briefly discussed. To test the model, a simple flow condition was analyzed. The effect of vapor fraction on heat transfer is assessed. The presence of the typical vapor blanket and its collapse can be recovered by the model, and its effect on the cooling rates on different parts of the piece is analyzed. Comparisons between numerical results and data from literature are made.

  12. Heat transfer model for quenching by submerging

    Energy Technology Data Exchange (ETDEWEB)

    Passarella, D N; Varas, F [Departamento de Matematica Aplicada II, E.T.S. de Ing. de Telecomunicacion, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain); MartIn, E B, E-mail: diego@dma.uvigo.es, E-mail: fvaras@uvigo.es, E-mail: emortega@uvigo.es [Area de Mecanica de Fluidos, E.T.S. de Ing. Industriales, Universidad de Vigo, Campus Marcosende, 36310 Vigo (Spain)

    2011-05-01

    In quenching by submerging the workpiece is cooled due to vaporization, convective flow and interaction of both mechanisms. The dynamics of these phenomena is very complex and the corresponding heat fluxes are strongly dependent on local flow variables such as velocity of fluid and vapor fraction. This local dependence may produce very different cooling rates along the piece, responsible for inappropriate metallurgical transformations, variability of material properties and residual stresses. In order to obtain an accurate description of cooling during quenching, a mathematical model of heat transfer is presented here. The model is based on the drift-flux mixture-model for multiphase flows, including an equation of conservation of energy for the liquid phase and specific boundary conditions that account for evaporation and presence of vapor phase on the surface of the piece. The model was implemented on Comsol Multiphysics software. Generation of appropriate initial and boundary conditions, as well as numerical resolution details, is briefly discussed. To test the model, a simple flow condition was analyzed. The effect of vapor fraction on heat transfer is assessed. The presence of the typical vapor blanket and its collapse can be recovered by the model, and its effect on the cooling rates on different parts of the piece is analyzed. Comparisons between numerical results and data from literature are made.

  13. Macroinvertebrates associated with two submerged macrophytes ...

    African Journals Online (AJOL)

    Macroinvertebrates associated with two submerged macrophytes, Lagarosiphon ilicifolius and Vallisneria aethiopica , in the Sanyati Basin, Lake Kariba, Zimbabwe: effect of plant morphological complexity.

  14. Use of pulsed arc welding for butt joint fabrication

    International Nuclear Information System (INIS)

    Merkulov, B.A.

    1977-01-01

    A technology of pulsed-arc butt welding with periodic wire feed to the welding zone has been developed. The pulsed arc is suitable both for submerged and gas-shielded weldings. The technology proposed has some advantages over the stationary-arc welding. Control of the amplitude-frequency characteristics of the process enables one to affect melting and crystallization conditions of the welding crater, weld shape, relation between melting and deposited metal section areas, etc., as well as to reduce heat contribution to the base metal. The new process is shown to be applicable in power engineering. Automatic submerged welding conditions are given for low-carbon and pearlitic heat-resistant steels

  15. Caracterização e avaliação da resistência à corrosão na soldagem de tubulação de aço inoxidável duplex UNS S31803 pelo processo a arco submerso Characterization and evaluation of corrosion resistance of welded joint of duplex stainless steel pipe UNS S31803 by submerged arc process

    Directory of Open Access Journals (Sweden)

    Juan Manuel Pardal

    2011-12-01

    Full Text Available O presente trabalho apresenta os resultados da caracterização e avaliação da resistência à corrosão de uma junta soldada correspondente a uma tubulação de aço inoxidável duplex (AID UNS S31803 de 35 mm de espessura de parede soldada pelos processos de soldagem TIG (GTAW na raiz e arco submerso (SAW no enchimento e acabamento. Foram empregados como consumíveis de soldagem metais de adição de liga 25Cr-9Ni-4Mo (% em peso. Os resultados da caracterização das propriedades mecânicas, composição química e resistência à corrosão em diversas regiões da junta soldada foram comparados com os obtidos para o metal de base da tubulação, assim como com os valores mínimos exigidos pelas normas de projeto. Os resultados obtidos demonstram claramente a possibilidade da implementação do processo SAW na pré fabricação de tubulações de paredes espessas de AID, tendo em vista os resultados das propriedades analisadas e a grande demanda na construção e montagem de tubulações desta família de aço inoxidáveis na indústria offshore.This work presents the mechanical properties, microstructural and corrosion resistance evaluation of a welded joint of duplex stainless steel (DSS pipe with 35 mm wall thickness. The joint was welded by gas tungsten arc welding (GTAW process in the root passes and submerged arc welding (SAW in the filling and cap passes using filler metals with composition 25Cr-9Ni-4Mo (%wt.. The results of mechanical properties, chemical composition and corrosion resistance characterization in different regions of the welded joint were compared to the base metal and to the specifications required by the standards applied in the project. The main focus of this work was to show the successful utilization of SAW process in the welding of thick wall pipes of DSS. The application of high productivity process such as SAW has a crescent demand in offshore industry.

  16. The Origin of Acicular Ferrite in Gas Metal Arc and Submerged ARC Welds

    Science.gov (United States)

    1994-03-01

    Ratio vs Acicular Ferrite 45 Figure 2.10 Crack Propagati6n Schematic . . ........... 46 Figure 2.11 CCT Diagram ... .......... ............ 47 Figure 3.1...10𔃾 TIME (S) Figure 2. 11 Continuous cooling transformation ( CCT ) diagram showing the effects of alloying elements, inclusion formers and cooling rate

  17. Flow and scour around vertical submerged structures

    Indian Academy of Sciences (India)

    The safety of the foundations of submerged hydraulic structures due to excessive local scour is threatened by the erosive action of the waves and currents passing around these structures. Fish and aquatic habitat is seriously affected due to the modification of the flow field caused by these submerged structures. Hence, the ...

  18. Effect of flux powder SiO2 for the welding of 304-austenitic stainless ...

    African Journals Online (AJOL)

    optimal weld pool geometry in the tungsten inert gas (TIG) welding of ..... Flux assisted gas tungsten arc and laser welding of titanium with cryolite containing fluxes: arc spectroscopy and corrosion resistance studies, Welding Journal, Vol.

  19. Submergence rice cultivation in southern Bangladesh: farmers opinion and adaptations practices

    Directory of Open Access Journals (Sweden)

    AKM Abdul Ahad Biswas

    2015-12-01

    Full Text Available Rice productivity in coastal Bangladesh is lower than the national average and total coastal area is considered to be submergence-prone and higher vulnerable in July to January cropping season. The selected study areas are Kalapara and Patuakhali Sadar Upazila that are too vulnerable to agriculture practices. Field survey was conducted during 01st June to 30th July, 2015 to investigate the impact of submergence on Aman rice cultivation (ARC, existing adopted local adaptation practices with impacts and options to address the submergence problem. Primary data was collected through Focus Group Discussion (FGD, Individual Interview and Key Informant Interview methods and secondary data was collected from different secondary sources. A well-structured pretested questionnaire schedule was developed keeping in mind the objectives and variables under this study. After cyclone SIDR and AILA devastation, the rate of traditional ARC is decreasing every year and in 2015 it was 26.51%. Recently farmers have adopted new cropping practices and strategies like modern ARC in Aman season as single crop; Boro-Aus-Aman season as triple crop and Aus-Aman season as double crop are practicing. Approximately all farmers have adopted to grow stress tolerant rice varieties (STRV; farmer’s curiosities to familiar with and to have the STRV are encouraging. Farmers were fully adopted BRRIdhan52 rice cultivation with positive perceptions of higher yield and lower production cost. Therefore it can be concluded that the intensity of adoption of adaptation and mitigation measures are significantly influenced positively by the STRV yield capability; farmer’s participation in intervention programs; livelihood diversification; frequency of extension personnel contact; submergence and inundation characteristics; tolerance attributes of STRV and availability of STRV cultivation information.International Journal of Environment Vol.4(4 2015: 100-113

  20. The mechanism of improved aeration due to gas films on leaves of submerged rice.

    Science.gov (United States)

    Verboven, Pieter; Pedersen, Ole; Ho, Quang Tri; Nicolai, Bart M; Colmer, Timothy D

    2014-10-01

    Some terrestrial wetland plants, such as rice, have super-hydrophobic leaf surfaces which retain a gas film when submerged. O2 movement through the diffusive boundary layer (DBL) of floodwater, gas film and stomata into leaf mesophyll was explored by means of a reaction-diffusion model that was solved in a three-dimensional leaf anatomy model. The anatomy and dark respiration of leaves of rice (Oryza sativa L.) were measured and used to compute O2 fluxes and partial pressure of O2 (pO2 ) in the DBL, gas film and leaf when submerged. The effects of floodwater pO2 , DBL thickness, cuticle permeability, presence of gas film and stomatal opening were explored. Under O2 -limiting conditions of the bulk water (pO2  gas film significantly increases the O2 flux into submerged leaves regardless of whether stomata are fully or partly open. With a gas film, tissue pO2 substantially increases, even for the slightest stomatal opening, but not when stomata are completely closed. The effect of gas films increases with decreasing cuticle permeability. O2 flux and tissue pO2 decrease with increasing DBL thickness. The present modelling analysis provides a mechanistic understanding of how leaf gas films facilitate O2 entry into submerged plants. © 2014 John Wiley & Sons Ltd.

  1. PERFORMANCE OF NEWLY CONFIGURED SUBMERGED MEMBRANE BIOREACTOR FOR AEROBIC INDUSTRIAL WASTEWATER TREATMENT

    Directory of Open Access Journals (Sweden)

    I Gede Wenten

    2012-02-01

    Full Text Available The application of membrane to replace secondary clarifier of conventional activated sludge, known as membrane bioreactor, has led to a small footprint size of treatment with excellent effluent quality. The use of MBR eliminates almost all disadvantages encountered in conventional wastewater treatment plant such as low biomass concentration and washout of fine suspended solids. However, fouling remains as a main drawback. To minimize membrane fouling, a new configuration of submerged membrane bioreactor for aerobic industrial wastewater treatment has been developed. For the new configuration, a bed of porous particle is applied to cover the submerged ends-free mounted ultrafiltration membrane. Membrane performance was assessed based on flux productivity and selectivity. By using tapioca wastewater containing high organic matter as feed solution, reasonably high and stable fluxes around 11 l/m2.h were achieved with COD removal efficiency of more than 99%. The fouling analysis also shows that the newly configured ends-free membrane bioreactor exhibits lower irreversible resistance compared with the submerged one. In addition, the performance of pilot scale system, using a membrane module  with 10 m2 effective area and reactor tank with 120 L volume, was also assessed. The flux achieved from the pilot scale system around 8 l/m2.h with COD removal of more than 99%. Hence, this study has demonstrated the feasibility of the newly configured submerged ends-free MBR at larger scale.

  2. IODINE REMOVAL EFFICIENCY IN NON-SUBMERGED AND SUBMERGED SELF-PRIMING VENTURI SCRUBBER

    Directory of Open Access Journals (Sweden)

    MAJID ALI

    2013-04-01

    Full Text Available The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH and sodium thiosulphate (Na2S2O3 in water to remove the gaseous iodine (I2 from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of 0.99±0.001 has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber.

  3. Iodine Removal Efficiency in Non-Submerged and Submerged Self-Priming Venturi Scrubber

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Majid; Yan, Changqi; Sun, Zhongning; Gu, Haifeng; Wang, Junlong; Mehboob; Khurram [Harbin Engineering Univ., Harbin (China)

    2013-04-15

    The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate (Na{sub 2}S{sub 2}O{sub 3}) in water to remove the gaseous iodine (I{sub 2}) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of 0.99±0.001 has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber.

  4. Iodine Removal Efficiency in Non-Submerged and Submerged Self-Priming Venturi Scrubber

    International Nuclear Information System (INIS)

    Ali, Majid; Yan, Changqi; Sun, Zhongning; Gu, Haifeng; Wang, Junlong; Mehboob; Khurram

    2013-01-01

    The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate (Na 2 S 2 O 3 ) in water to remove the gaseous iodine (I 2 ) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine for submerged and non-submerged operating conditions. In the non-submerged venturi scrubber, only the droplets take part in iodine removal efficiency. However, in a submerged venturi scrubber condition, the iodine gas is absorbed from gas to droplets inside the venturi scrubber and from bubbles to surrounding liquid at the outlet of a venturi scrubber. Experimentally, it is observed that the iodine removal efficiency is greater in the submerged venturi scrubber as compare to a non-submerged venturi scrubber condition. The highest iodine removal efficiency of 0.99±0.001 has been achieved in a submerged self-priming venturi scrubber condition. A mathematical correlation is used to predict the theoretical iodine removal efficiency in submerged and non-submerged conditions, and it is compared against the experimental results. The Wilkinson et al. correlation is used to predict the bubble diameter theoretically whereas the Nukiyama and Tanasawa correlation is used for droplet diameter. The mass transfer coefficient for the gas phase is calculated from the Steinberger and Treybal correlation. The calculated results for a submerged venturi scrubber agree well with experimental results but underpredicts in the case of the non-submerged venturi scrubber

  5. Acoustic and adsorption properties of submerged wood

    Science.gov (United States)

    Hilde, Calvin Patrick

    Wood is a common material for the manufacture of many products. Submerged wood, in particular, is used in niche markets, such as the creation of musical instruments. An initial study performed on submerged wood from Ootsa Lake, British Columbia, provided results that showed that the wood was not suitable for musical instruments. This thesis re-examined the submerged wood samples. After allowing the wood to age unabated in a laboratory setting, the wood was retested under the hypothesis that the physical acoustic characteristics would improve. It was shown, however, that the acoustic properties became less adequate after being left to sit. The adsorption properties of the submerged wood were examined to show that the submerged wood had a larger accessible area of wood than that of control wood samples. This implied a lower amount of crystalline area within the submerged wood. From the combined adsorption and acoustic data for the submerged wood, relationships between the moisture content and speed of sound were created and combined with previous research to create a proposed model to describe how the speed of sound varies with temperature, moisture content and the moisture content corresponding to complete hydration of sorption sites within the wood.

  6. Fluid-structure interaction of submerged structures

    International Nuclear Information System (INIS)

    Tang, H.T.; Becker, E.B.; Taylor, L.M.

    1979-01-01

    The purpose of the paper is to investigate fluid-structure interaction (FSI) of submerged structures in a confined fluid-structure system. Our particular interest is the load experienced by a rigid submerged structure subject to a pressure excitation in a fluid domain bounded by a structure which is either flexible or rigid. The objective is to see whether the load experienced by the submerged structure will be influenced by its confinement conditions. This investigation is intended to provide insight into the characteristics of FSI and answer the question as to whether one can obtain FSI independent data by constructing a small scale rigid submerged structure inside a flexible fluid-structure system. (orig.)

  7. Submerged cutting characteristics of abrasive suspension jet

    International Nuclear Information System (INIS)

    Shimizu, Seiji; Peng, Guoyi; Oguma, Yasuyuki; Nishikata, Hiroyuki

    2015-01-01

    An abrasive suspension jet (ASJ) formed by propelling abrasive suspension through a nozzle has a greater cutting capability than the conventional abrasive water jet. However the cutting capability of submerged ASJs decreases drastically with increasing the standoff distance and the pressure around the jet. A sheathed nozzle with ventilation for ASJs has been developed as a mean of extending the effective stand-off distance and improving the cutting capabilities under submerged condition. In the present investigation, cutting tests by ASJs in air and under submerged condition are conducted with specimens of aluminum alloy. Air coated ASJs are formed by using a sheathed nozzle with ventilation. The relative cutting depth is defined as the cutting depth under submerged condition divided by the cutting depth in air at the same standoff distance. The relative cutting depth is arranged effectually by the cavitation number based on the cavity pressure measured at the sheath. (author)

  8. Arc saw development report

    International Nuclear Information System (INIS)

    Deichelbohrer, P.R.; Beitel, G.A.

    1981-01-01

    The arc saw is one of the key components of the Contaminated Equipment Volume Reduction (CEVR) Program. This report describes the progress of the arc saw from its inception to its current developmental status. History of the arc saw and early contributors are discussed. Particular features of the arc saw and their advantages for CEVR are detailed. Development of the arc saw including theory of operation, pertinent experimental results, plans for the large arc saw and advanced control systems are covered. Associated topics such as potential applications for the arc saw and other arc saw installations in the world is also touched upon

  9. Arc Motion in an Obliquely Imposed Alternating Magnetic Field

    International Nuclear Information System (INIS)

    Akiho, R; Takeda, K; Sugimoto, M

    2012-01-01

    The arc motion is theoretically investigated under an alternating magnetic field imposed obliquely to the arc. The arc is known to oscillate on a 2-D plane when the alternating magnetic field is imposed perpendicularly to the arc. If the alternating magnetic field is imposed obliquely to the arc, then it is expected that the arc oscillates not on the 2-D plane but in a 3-D space. For this study, 3-D simulation was performed on the motion of the plasma gas under an alternating magnetic field crossing obliquely to the arc. It was also assumed that a stream line of the plasma gas represented the arc profile. The momentum equation for the plasma gas was solved together with the continuity equation. Governing parameters for the gas motion are θ (crossing angle), v 0 (initial velocity of the plasma gas), and λ. Parameter λ is defined as λ = (I a B 0 )/Q 0 . Numerical results are reported under different operating conditions such as magnetic flux densities and the angles between the arc and the magnetic flux. If the crossing angle is larger than 4/π, the arc might be extinguished because of the drastic increase of the arc length.

  10. The grain boundary segregation of phosphorus in thermally aged and irradiated C-Mn submerged-are weld metal

    International Nuclear Information System (INIS)

    Mendes, C.M.

    1999-01-01

    The segregation of free phosphorus atoms to grain boundaries in C-Mn steels has been identified as an embrittlement mechanism. A change in the brittle fracture mechanism from transgranular to intergranular has been observed for materials with higher phosphorus grain boundary coverage. The grain boundary segregation of phosphorus in various steels used in the nuclear power industry has been thermodynamically and kinetically modelled mostly with the Langmuir-McLean model. Recent publications have also suggested that neutron irradiation can affect segregation and various attempts at modelling this are currently under way. The present paper describes a data base assembled on phosphorus grain boundary coverage measured by Auger electron spectroscopy on thermally aged and irradiated C-Mn submerged-arc weld specimens. Software tools were developed to evaluate the changes in phosphorus grain boundary coverage associated with instantaneous temperature changes and temperature gradients. The phosphorus free energy change associated with grain boundary segregation was modelled from the thermally aged data and used with the software to determine the phosphorus segregation in submerged-arc weld metals following the post weld stress relief heat treatments received prior to plant operation. The phosphorus grain boundary coverage changes arising from the thermal history of submerged-arc weld materials during irradiation were also modelled and found to compare well with data obtained on irradiated materials. It was concluded that under the irradiation conditions sampled, phosphorus grain boundary segregation in submerged-arc weld materials can be modelled successfully using only the thermal term without appealing to an irradiation induced segregation process. (author)

  11. Impeller Submergence Depth for Stirred Tanks

    Directory of Open Access Journals (Sweden)

    Thiyam T. Devi

    2011-11-01

    Full Text Available Impeller submergence governs the performance of mixing tanks employed in oxygen transfer operation. Present work experimentally investigates the effect of impeller submergence depths on oxygen transfer and corresponding power consumption. It has been found that at higher range of impeller submergence, mixing tanks consume less power and gives higher values of oxygen transfer coefficient. Optimal range of submergence depth is 0.7 to 0.9 times the impeller diameter. Copyright ©2011 BCREC UNDIP. All rights reserved.(Received: 4th March 2011; Revised: 12nd July 2011; Accepted: 14th July 2011[How to Cite: T.T. Devi, A.P. Sinha, M. Thakre, and B. Kumar. (2011. Impeller Submergence Depth for Stirred Tanks. Bulletin of Chemical Reaction Engineering & Catalysis, 6 (2: 123-128. doi:10.9767/bcrec.6.2.826.123-128][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.6.2.826.123-128 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/826] | View in 

  12. Submerged cutting characteristics of abrasive suspension jet

    International Nuclear Information System (INIS)

    Shimizu, Seiji; Peng, Guoyi; Oguma, Yasuyuki; Nishikata, Hiroki

    2015-01-01

    An abrasive suspension jet (ASJ) formed by propelling abrasive suspension through a nozzle has a greater cutting capability than the conventional abrasive water jet. However the cutting capability of submerged ASJs decreases drastically with increasing the standoff distance and the pressure around the jet. A sheathed nozzle nozzle with ventilation for ASJs has been developed as a mean of extending the effective stand-off distance and improving the cutting capabilities under submerged condition. In the present investigation, cutting tests by ASJs in air and under submerged condition are conducted with specimens of aluminum alloy. Air coated ASJs are formed by using a sheathed nozzle with ventilation. The relative cutting depth is defined as the cutting depth is arranged effectually by the cavitation number based on the cavity pressure measured at the sheath. (author)

  13. Method to reduce arc blow during DC arc welding of pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Espina-Hernandez, J. H.; Rueda-Morales, G.L.; Caleyo, F.; Hallen, J. M. [Instituto Politecnico Nacional, Mexico, (Mexico); Lopez-Montenegro, A.; Perz-Baruch, E. [Pemex Exploracion y Produccion, Tabasco, (Mexico)

    2010-07-01

    Steel pipelines are huge ferromagnetic structures and can be easily subjected to arc blow during the DC arc welding process. The development of methods to avoid arc blow during pipeline DC arc welding is a major objective in the pipeline industry. This study developed a simple procedure to compensate the residual magnetic field in the groove during DC arc welding. A Gaussmeter was used to perform magnetic flux density measurements in pipelines in southern Mexico. These data were used to perform magnetic finite element simulations using FEMM. Different variables were studied such as the residual magnetic field in the groove or the position of the coil with respect to the groove. An empirical predictive equation was developed from these trials to compensate for the residual magnetic field. A new method of compensating for the residual magnetic field in the groove by selecting the number of coil turns and the position of the coil with respect to the groove was established.

  14. Experimental investigation of submerged single jet impingement using Cu–water nanofluid

    International Nuclear Information System (INIS)

    Li Qiang; Xuan Yimin; Yu Feng

    2012-01-01

    Jet impingement cooling is a vital technique for thermal management of electronic devices of high-heat-flux by impinging fluid on a heater surface due to its high local heat transfer rates. In this paper, two types of Cu–water nanofluids (Cu particles with 25 nm diameter or 100 nm) are introduced into submerged single jet impingement cooling system as the working fluid. The heat transfer features of the nanofluids were experimentally investigated. The effects of the nanoparticle concentration, Reynolds number, nozzle-to-plate distance, fluid temperature, and nanoparticle diameter on the heat transfer performances of the jet impingement of nanofluids are discussed. The experimental results show that the suspended nanoparticles remarkably increase the convective heat transfer coefficient of the base fluid. The convective heat transfer coefficient of Cu–water nanofluid with the volume fraction of 3.0% has 52% higher than the pure water. The experiments also revealed that the suspended nanoparticles brought almost no extra addition of pressure drop in both submerged single jet impingement. In addition, by considering the effects of the suspended nanoparticles as well as the condition of impinging jet, a new heat transfer correlation of nanofluids for the submerged single jet impingement has been proposed. - Highlights: ► Cu–water nanofluids are introduced into submerged single jet impingement. ► The affecting parameters on the heat transfer performances of nanofluids are discussed. ► New heat transfer correlation of nanofluid for single jet impingement is proposed.

  15. Topology optimization for submerged buoyant structures

    NARCIS (Netherlands)

    Picelli, R.; van Dijk, R.; Vicente, W.M.; Pavanello, R.; Langelaar, M.; van Keulen, A.

    2017-01-01

    This paper presents an evolutionary structural topology optimization method for the design of completely submerged buoyant modules with design-dependent fluid pressure loading. This type of structure is used to support offshore rig installation and pipeline transportation at all water depths. The

  16. Benthic bacterial diversity in submerged sinkhole ecosystems.

    Science.gov (United States)

    Nold, Stephen C; Pangborn, Joseph B; Zajack, Heidi A; Kendall, Scott T; Rediske, Richard R; Biddanda, Bopaiah A

    2010-01-01

    Physicochemical characterization, automated ribosomal intergenic spacer analysis (ARISA) community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale, while deeper, organically rich sediments contained diverse and active bacterial communities.

  17. Waterlogging and submergence: surviving poor aeration

    NARCIS (Netherlands)

    Atwell, B.J.; Ismail, A.M.; Pedersen, O.; Shabala, S.; Sorrell, B.; Voesenek, Laurentius|info:eu-repo/dai/nl/074850849

    2014-01-01

    Flooding, resulting in soil waterlogging and in many situations even complete submergence of plants, is an important abiotic stress in many regions worldwide. The number of floods has increased in recent decades (Figure 18.1), and the severity of floods is expected to increase further in many

  18. Production of extracellular aspartic protease in submerged ...

    African Journals Online (AJOL)

    Fungal milk-clotting enzymes have gained value as bovine Chymosin substitutes in the cheese industry. In this work, the effects of culture conditions on the production of extracellular milk clotting enzymes from Mucor mucedo DSM 809 in submerged fermentation were studied. The maximum activity was observed after 48 h ...

  19. [Effects of two submerged macrophytes on dissolved inorganic nitrogen in overlying water and interstitial water].

    Science.gov (United States)

    Yang, Wen-Bin; Li, Yang; Sun, Gong-Xian

    2014-06-01

    Ceratophyllum demersum (C. demersum) and Vallisneria spiralis L. (V. spiralis L.) were studied as model submerged macrophytes. The effects of the submerged macrophytes on the forms and concentration of the dissolved inorganic nitrogen (DIN) in the overlying water and the interstitial water, as well as the diffusion flux of DIN in the water-sediment interface were investigated by batch simulation experiment. The results indicated that the removal effect of DIN in the overlying water was better than that in the interstitial water by submerged macrophytes. The removal efficiency of DIN in the overlying water and the interstitial water followed the order of NO2(-) -N > NH4(+) -N > NO3(-) -N. The removal rate of DIN by C. demersum was higher than that of V. spiralis L. in the overlying water, while the result was converse in the interstitial water. C. demersum and V. spiralis L. decreased the diffusion flux of NH4(+) -N and NO2(-) -N, and increased the diffusion flux of NO3(-) -N significantly. Consequently, NO3(-) -N replaced NH4(+) -N and became the main form of DIN, which diffused from the interstitial water to the overlying water. The impact of the diffusion flux of NO3(-) -N between C. demersum and V. spiralis L. showed no significant difference, and the result was the same for NH4(+) -N. C. demersum and V. spiralis L. increased the width of variation of the three nitrogen forms to total DIN in the overlying water and the interstitial water, the influence on the ratio of DIN by C. demersum was greater than that of V. spiralis L. in the overlying water, while the result was opposite in the interstitial water. In general, C. demersum had more influence in the overlying water, while V. spiralis L. had more influence in the interstitial water, and the influence of DIN diffusion flux was not significant.

  20. Oxygen dynamics in submerged rice (Oryza sativa L.)

    DEFF Research Database (Denmark)

    Colmer, Timothy D.; Pedersen, Ole

    2008-01-01

    Complete submergence of plants prevents direct O2 and CO2 exchange with air. Underwater photosynthesis can result in marked diurnal changes in O2 supply to submerged plants. Dynamics in pO2 had not been measured directly for submerged rice (Oryza sativa), but in an earlier study, radial O2 loss...... from roots showed an initial peak following shoot illumination.  O2 dynamics in shoots and roots of submerged rice were monitored during light and dark periods, using O2 microelectrodes. Tissue sugar concentrations were also measured.  On illumination of shoots of submerged rice, pO2 increased rapidly...... of magnitude higher than in darkness, enhancing also pO2 in roots.The initial peak in pO2 following illumination of submerged rice was likely to result from high initial rates of net photosynthesis, fuelled by CO2 accumulated during the dark period. Nevertheless, since sugars decline with time in submerged...

  1. 'LTE-diffusion approximation' for arc calculations

    International Nuclear Information System (INIS)

    Lowke, J J; Tanaka, M

    2006-01-01

    This paper proposes the use of the 'LTE-diffusion approximation' for predicting the properties of electric arcs. Under this approximation, local thermodynamic equilibrium (LTE) is assumed, with a particular mesh size near the electrodes chosen to be equal to the 'diffusion length', based on D e /W, where D e is the electron diffusion coefficient and W is the electron drift velocity. This approximation overcomes the problem that the equilibrium electrical conductivity in the arc near the electrodes is almost zero, which makes accurate calculations using LTE impossible in the limit of small mesh size, as then voltages would tend towards infinity. Use of the LTE-diffusion approximation for a 200 A arc with a thermionic cathode gives predictions of total arc voltage, electrode temperatures, arc temperatures and radial profiles of heat flux density and current density at the anode that are in approximate agreement with more accurate calculations which include an account of the diffusion of electric charges to the electrodes, and also with experimental results. Calculations, which include diffusion of charges, agree with experimental results of current and heat flux density as a function of radius if the Milne boundary condition is used at the anode surface rather than imposing zero charge density at the anode

  2. Pump Coastdown with the Submerged Flywheel

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Hyun-Gi; Seo, KyoungWoo; Kim, Seong Hoon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Many research reactors are generally designed as open pool types in consideration of the heat removal of the nuclear fuels, reactor operation and accessibility. Reactor structure assembly is generally placed at the pool bottom as shown in Fig. 1. Primary cooling system pump circulates the coolant from the reactor structure to the heat exchanger in order to continuously remove the heat generated from the reactor core in the research reactor as shown in Fig. 1. The secondary cooling system releases the transferred heat to the atmosphere by the cooling tower. Coastdown flow rate of the primary cooling system pump with the submerged flywheel are calculated analytically in case of the accident situation. Coastdown flow rate is maintained until almost 80 sec when the pump stops normally. But, coastdown flow rate is rapidly decreased when the flywheel is submerged because of the friction load on the flywheel surface.

  3. Experimental motion behavior of submerged fuel racks

    International Nuclear Information System (INIS)

    Ellingson, F.J.; Wachter, W.; Moscardini, R.L.

    1989-01-01

    The design of submerged nuclear storage racks for light water reactor nuclear fuel has undergone a change from fixed position to a free-standing arrangement. Seismic analysis of the motion of the free-standing racks requires three-dimensional computer modeling that uses past studies of hydrodynamic mass and hydraulic coupling for rigid flat plates. This paper describes the results of experiments that show a reduced value for hydrodynamic mass and coupling forces when flexible elements are involved. To support this work, experiments were run with two full-scale welded box sections submerged in a water tank. The preliminary results indicate reduction in hydrodynamic mass due to box wall flexibility, a lack of impacting of box wall to box wall over the entire frequency range, and large hydrodynamic coupling forces under all test conditions. It is hypothesized that the coupling forces are sufficiently strong to prevent rotational motion of one rack when surrounded by adjacent racks

  4. Effect of clone size on submergence tolerance and post-submergence growth recovery in Carex brevicuspis (Cyperaceae

    Directory of Open Access Journals (Sweden)

    Zhengmiao Deng

    2016-12-01

    Full Text Available Clonal plants are prevalent in wetlands and play important roles in maintaining the functions of the ecosystem. In the present study, we determined the effect of clone sizes (R1, R2, and R3 comprising 1, 3, and 5clumping ramets on the tolerance of Carex brevicuspis growing under 30-cm-deep water to three different periods (one, two, and three months of submergence and its growth recovery one month after de-submergence. Our results showed that the relative growth rate (RGR of C. brevicuspis significantly declined with increasing submergence time, and was higher in R3 and R5 than in R1 plants under both submergence and post-submergence conditions. The concentration of water-soluble carbohydrates (WSCs was highest in R3, intermediate in R5, and the lowest in R1 plants during the first two months of submergence, indicating an optimal trade-off between energy investment and vegetative growth (i.e., buds and ramets production in C. brevicuspis. WSCs were significantly reduced with increasing submergence time, while the starch content was significantly reduced only during the third month of submergence, implying that WSCs were a direct energy source for C. brevicuspis during submergence. The number of buds was higher in R5 than in R3 and R1 plants after two and three months of submergence, which directly resulted in a significantly higher post-submergence ramet production in R5 plants. These results indicated that plants with relatively larger clone sizes display better tolerance to submergence stress and post-submergence growth recovery. Therefore, we speculate that the large clone size in C brevicuspis might be an effective adaptive mechanism to survive under submergence stress in floodplain wetlands.

  5. Radiocarbon measurements on submerged forest floating chronologies

    International Nuclear Information System (INIS)

    Campbell, J.A.; Baxter, M.S.

    1979-01-01

    It is stated that the submerged forests along the west coast of England and Wales provide a unique source of wood for radiocarbon/ dendrochronological studies. 14 C age determinations are reported on sequential growth increments from three 'gloating' chronologies. A sampling frequency of approximately 10 samples per century was used. Fluctuations in atmospheric 14 C levels of 2 to 3% over several decades can occur, these variations being superimposed on a smoothly changing trend. (author)

  6. Unusual energy properties of leaky backward Lamb waves in a submerged plate.

    Science.gov (United States)

    Nedospasov, I A; Mozhaev, V G; Kuznetsova, I E

    2017-05-01

    It is found that leaky backward Lamb waves, i.e. waves with negative energy-flux velocity, propagating in a plate submerged in a liquid possess extraordinary energy properties distinguishing them from any other type of waves in isotropic media. Namely, the total time-averaged energy flux along the waveguide axis is equal to zero for these waves due to opposite directions of the longitudinal energy fluxes in the adjacent media. This property gives rise to the fundamental question of how to define and calculate correctly the energy velocity in such an unusual case. The procedure of calculation based on incomplete integration of the energy flux density over the plate thickness alone is applied. The derivative of the angular frequency with respect to the wave vector, usually referred to as the group velocity, happens to be close to the energy velocity defined by this mean in that part of the frequency range where the backward mode exists in the free plate. The existence region of the backward mode is formally increased for the submerged plate in comparison to the free plate as a result of the liquid-induced hybridization of propagating and nonpropagating (evanescent) Lamb modes. It is shown that the Rayleigh's principle (i.e. equipartition of total time-averaged kinetic and potential energies for time-harmonic acoustic fields) is violated due to the leakage of Lamb waves, in spite of considering nondissipative media. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Comparative study on the treatment of raw and biologically treated textile effluents through submerged nanofiltration.

    Science.gov (United States)

    Chen, Qing; Yang, Ying; Zhou, Mengsi; Liu, Meihong; Yu, Sanchuan; Gao, Congjie

    2015-03-02

    Raw and biologically treated textile effluents were submerged filtrated using lab-fabricated hollow fiber nanofiltration membrane with a molecular weight cut-off of about 650 g/mol. Permeate flux, chemical oxygen demand (COD) reduction, color removal, membrane fouling, and cleaning were investigated and compared by varying the trans-membrane pressure (TMP) and volume concentrating factor (VCF). It was found that both raw and biologically treated textile effluents could be efficiently treated through submerged nanofiltration. The increase of TMP resulted in a decline in water permeability, COD reduction, color removal, and flux recovery ratio, while the increase of VCF resulted in both increased COD reduction and color removal. Under the TMP of 0.4 bar and VCF of 5.0, fluxes of 1.96 and 2.59 l/m(2)h, COD reductions of 95.7 and 94.2%, color removals of 99.0, and 97.3% and flux recovery ratios of 91.1 and 92.9% could be obtained in filtration of raw and biologically treated effluents, respectively. After filtration, the COD and color contents of the raw effluent declined sharply from 1780 to 325 mg/l and 1.200 to 0.060 Abs/cm, respectively, while for the biologically treated effluent, they decreased from 780 to 180 mg/l and 0.370 to 0.045 Abs/cm, respectively. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Monitoring ARC services with GangliARC

    International Nuclear Information System (INIS)

    Cameron, D; Karpenko, D

    2012-01-01

    Monitoring of Grid services is essential to provide a smooth experience for users and provide fast and easy to understand diagnostics for administrators running the services. GangliARC makes use of the widely-used Ganglia monitoring tool to present web-based graphical metrics of the ARC computing element. These include statistics of running and finished jobs, data transfer metrics, as well as showing the availability of the computing element and hardware information such as free disk space left in the ARC cache. Ganglia presents metrics as graphs of the value of the metric over time and shows an easily-digestable summary of how the system is performing, and enables quick and easy diagnosis of common problems. This paper describes how GangliARC works and shows numerous examples of how the generated data can quickly be used by an administrator to investigate problems. It also presents possibilities of combining GangliARC with other commonly-used monitoring tools such as Nagios to easily integrate ARC monitoring into the regular monitoring infrastructure of any site or computing centre.

  9. IODINE REMOVAL EFFICIENCY IN NON-SUBMERGED AND SUBMERGED SELF-PRIMING VENTURI SCRUBBER

    OpenAIRE

    MAJID ALI; YAN CHANGQI; SUN ZHONGNING; GU HAIFENG; WANG JUNLONG; KHURRAM MEHBOOB

    2013-01-01

    The objective of this conducted research is to study the iodine removal efficiency in a self-priming venturi scrubber for submerged and non-submerged operating conditions experimentally and theoretically. The alkaline solution is used as an absorbent, which is prepared by dissolving sodium hydroxide (NaOH) and sodium thiosulphate (Na2S2O3) in water to remove the gaseous iodine (I2) from the gas. Iodine removal efficiency is examined at various gas flow rates and inlet concentrations of iodine...

  10. Design of extended length submerged traveling screen and submerged bar screen fish guidance equipment

    International Nuclear Information System (INIS)

    Bardy, D.; Lindstrom, M.; Fechner, D.

    1991-01-01

    The hydropower projects on the Snake and lower Columbia Rivers in the Pacific Northwest are unique because these rivers are also the spawning grounds for migratory salmon. The salmon swim upstream from the ocean, lay their eggs, and die. The newly hatched fingerlings must then make their way past the hydroelectric dams to the ocean. Two separate bypass systems are needed, one to pass the adult fish going upstream, and one to pass the fingerlings going downstream. This paper addresses the design considerations for two of the components of the downstream migrant fish passage facilities, the extended Submerged Traveling Screen and Submerged Bar Screen

  11. Electric arc hydrogen heaters

    International Nuclear Information System (INIS)

    Zasypin, I.M.

    2000-01-01

    The experimental data on the electric arc burning in hydrogen are presented. Empirical and semiempirical dependences for calculating the arc characteristics are derived. An engineering method of calculating plasma torches for hydrogen heating is proposed. A model of interaction of a hydrogen arc with a gas flow is outlined. The characteristics of plasma torches for heating hydrogen and hydrogen-bearing gases are described. (author)

  12. Graphite electrode arc melter demonstration Phase 2 test results

    International Nuclear Information System (INIS)

    Soelberg, N.R.; Chambers, A.G.; Anderson, G.L.; O'Connor, W.K.; Oden, L.L.; Turner, P.C.

    1996-06-01

    Several U.S. Department of Energy organizations and the U.S. Bureau of Mines have been collaboratively conducting mixed waste treatment process demonstration testing on the near full-scale graphite electrode submerged arc melter system at the Bureau's Albany (Oregon) Research Center. An initial test series successfully demonstrated arc melter capability for treating surrogate incinerator ash of buried mixed wastes with soil. The conceptual treatment process for that test series assumed that buried waste would be retrieved and incinerated, and that the incinerator ash would be vitrified in an arc melter. This report presents results from a recently completed second series of tests, undertaken to determine the ability of the arc melter system to stably process a wide range of open-quotes as-receivedclose quotes heterogeneous solid mixed wastes containing high levels of organics, representative of the wastes buried and stored at the Idaho National Engineering Laboratory (INEL). The Phase 2 demonstration test results indicate that an arc melter system is capable of directly processing these wastes and could enable elimination of an up-front incineration step in the conceptual treatment process

  13. Graphite electrode arc melter demonstration Phase 2 test results

    Energy Technology Data Exchange (ETDEWEB)

    Soelberg, N.R.; Chambers, A.G.; Anderson, G.L.; O`Connor, W.K.; Oden, L.L.; Turner, P.C.

    1996-06-01

    Several U.S. Department of Energy organizations and the U.S. Bureau of Mines have been collaboratively conducting mixed waste treatment process demonstration testing on the near full-scale graphite electrode submerged arc melter system at the Bureau`s Albany (Oregon) Research Center. An initial test series successfully demonstrated arc melter capability for treating surrogate incinerator ash of buried mixed wastes with soil. The conceptual treatment process for that test series assumed that buried waste would be retrieved and incinerated, and that the incinerator ash would be vitrified in an arc melter. This report presents results from a recently completed second series of tests, undertaken to determine the ability of the arc melter system to stably process a wide range of {open_quotes}as-received{close_quotes} heterogeneous solid mixed wastes containing high levels of organics, representative of the wastes buried and stored at the Idaho National Engineering Laboratory (INEL). The Phase 2 demonstration test results indicate that an arc melter system is capable of directly processing these wastes and could enable elimination of an up-front incineration step in the conceptual treatment process.

  14. Using arc voltage to locate the anode attachment in plasma arc cutting

    International Nuclear Information System (INIS)

    Osterhouse, D J; Heberlein, J V R; Lindsay, J W

    2013-01-01

    Plasma arc cutting is a widely used industrial process in which an electric arc in the form of a high velocity plasma jet is used to melt and blow away metal. The arc attaches inside the resulting cut slot, or kerf, where it both provides a large heat flux and determines the flow dynamics of the plasma. Knowledge of the position of the arc attachment is essential for understanding the phenomena present at the work piece. This work presents a new method of measuring the location of the arc attachment in which the arc voltage is measured during the cutting of a range of work piece thicknesses. The attachment location is then interpreted from the voltages. To support the validity of this method, the kerf shape, dross particle size and dross adhesion to the work piece are also observed. While these do not conclusively give an attachment location, they show patterns which are consistent with the attachment location found from the voltage measurements. The method is demonstrated on the cutting of mild steel, where the arc attachment is found to be stationary in the upper portion of the cut slot and in reasonable agreement with existing published findings. For a process optimized for the cutting of 12.7 mm mild steel, the attachment is found at a depth of 1.5–3.4 mm. For a slower process optimized for the cutting of 25.4 mm mild steel, the attachment is found at a depth of 3.4–4.8 mm, which enhances heat transfer further down in the kerf, allowing cutting of the thicker work piece. The use of arc voltage to locate the position of the arc attachment is unique when compared with existing methods because it is entirely independent of the heat distribution and visualization techniques. (paper)

  15. Calibration of submerged multi-sluice gates

    Directory of Open Access Journals (Sweden)

    Mohamed F. Sauida

    2014-09-01

    The main objective of this work is to study experimentally and verify empirically the different parameters affecting the discharge through submerged multiple sluice gates (i.e., the expansion ratios, gates operational management, etc.. Using multiple regression analysis of the experimental results, a general equation for discharge coefficient is developed. The results show, that the increase in the expansion ratio and the asymmetric operation of gates, give higher values for the discharge coefficient. The obtained predictions of the discharge coefficient using the developed equations are compared to the experimental data. The present developed equations showed good consistency and high accuracy.

  16. Optical emission spectroscopy of metal vapor dominated laser-arc hybrid welding plasma

    International Nuclear Information System (INIS)

    Ribic, B.; DebRoy, T.; Burgardt, P.

    2011-01-01

    During laser-arc hybrid welding, plasma properties affect the welding process and the weld quality. However, hybrid welding plasmas have not been systematically studied. Here we examine electron temperatures, species densities, and electrical conductivity for laser, arc, and laser-arc hybrid welding using optical emission spectroscopy. The effects of arc currents and heat source separation distances were examined because these parameters significantly affect weld quality. Time-average plasma electron temperatures, electron and ion densities, electrical conductivity, and arc stability decrease with increasing heat source separation distance during hybrid welding. Heat source separation distance affects these properties more significantly than the arc current within the range of currents considered. Improved arc stability and higher electrical conductivity of the hybrid welding plasma result from increased heat flux, electron temperatures, electron density, and metal vapor concentrations relative to arc or laser welding.

  17. Comparison of Welding Residual Stresses of Hybrid Laser-Arc Welding and Submerged Arc Welding in Offshore Steel Structures

    DEFF Research Database (Denmark)

    Andreassen, Michael Joachim; Yu, Zhenzhen; Liu, Stephen

    2016-01-01

    In the offshore industry, welding-induced distortion and tensile residual stresses have become a major concern in relation to the structural integrity of a welded structure. Particularly, the continuous increase in size of welded plates and joints needs special attention concerning welding induced...... residual stresses. These stresses have a negative impact on the integrity of the welded joint as they promote distortion, reduce fatigue life, and contribute to corrosion cracking and premature failure in the weld components. This paper deals with the influence and impact of welding method on the welding...... induced residual stresses. It is also investigated whether the assumption of residual stresses up to yield strength magnitude are present in welded structures as stated in the design guidelines. The fatigue strength for welded joints is based on this assumption. The two welding methods investigated...

  18. Heat transfers in a low-pressure arc-jet

    Energy Technology Data Exchange (ETDEWEB)

    Dudeck, M [Centre National de la Recherche Scientifique (CNRS), 92 - Meudon-Bellevue (France); Kaminska, A [Politechnika Poznanska, Poznan (Poland)

    1995-03-01

    In the framework of low-pressure arc-jet applications to thermodynamical condition simulation for reentry vehicles at hypersonic speed, an analytical study has been carried out concerning the thermodynamical conditions of a plasma in an arc-source for plasmatron usual operating conditions. After a review of gas physical properties, the gas flow in the plasmatron with a divergent nozzle is modelled; temperature profiles in the arc and in the divergent and the wall heat flux are then computed. Results are given. 8 refs., 6 figs.

  19. Impacts of climate change on submerged and emergent wetland plants

    Science.gov (United States)

    Frederick T. Short; Sarian Kosten; Pamela A. Morgan; Sparkle L Malone; Gregg E. Moore

    2016-01-01

    Submerged and emergent wetland plant communities are evaluated for their response to global climate change (GCC), focusing on seagrasses, submerged freshwater plants, tidal marsh plants, freshwater marsh plants and mangroves. Similarities and differences are assessed in plant community responses to temperature increase, CO2increase, greater UV-B exposure, sea...

  20. Multielement stoichiometry of submerged macrophytes across Yunnan plateau lakes (China).

    Science.gov (United States)

    Xing, Wei; Wu, Haoping; Shi, Qiao; Hao, Beibei; Liu, Han; Wang, Zhixiu; Liu, Guihua

    2015-05-13

    Stoichiometric homeostasis of element composition is one of the central concepts of ecological stoichiometry. We analyzed concentrations of macroelements (C, N, P, Ca, K, Mg, S), microelements (Cu, Fe, Mn, Mo, Ni, Zn) and beneficial elements (Na, Se, Si) in submerged macrophytes, water and sediments across 20 Yunnan plateau lakes. We predicted that tissue element composition in submerged macrophytes is affected by lake trophic level and taxonomy, and submerged macrophytes have weak stoichiometric homeostasis for all above 16 elements. Canonical discriminant analyses successfully discriminated among trophic level groups and taxa groups. Of all the elements, C, N, P and S most effectively discriminated among trophic level groups across 20 lakes, revealing lake trophic level mostly affect tissue macroelement composition in submerged macrophytes; while Ca, K and Se most effectively discriminated among submerged macrophytes taxa groups, suggesting taxonomy mostly affect compositions of macroelements and beneficial elements in submerged macrophytes. In addition, the stoichiometric homeostatic coefficient of 1/HCa:C for all five taxa of submerged macrophytes were less than zero, suggesting submerged macrophytes in Yunnan plateau lakes have strong Ca stoichiometric homeostasis. Our findings, not only broaden the knowledge of multielement stoichiometric homeostasis, but also help to choose most appropriate lake management strategy.

  1. Impact of global transcriptional regulation by ArcA, ArcB, Cra, Crp, Cya, Fnr, and Mlc on glucose catabolism in Escherichia coli.

    Science.gov (United States)

    Perrenoud, Annik; Sauer, Uwe

    2005-05-01

    Even though transcriptional regulation plays a key role in establishing the metabolic network, the extent to which it actually controls the in vivo distribution of metabolic fluxes through different pathways is essentially unknown. Based on metabolism-wide quantification of intracellular fluxes, we systematically elucidated the relevance of global transcriptional regulation by ArcA, ArcB, Cra, Crp, Cya, Fnr, and Mlc for aerobic glucose catabolism in batch cultures of Escherichia coli. Knockouts of ArcB, Cra, Fnr, and Mlc were phenotypically silent, while deletion of the catabolite repression regulators Crp and Cya resulted in a pronounced slow-growth phenotype but had only a nonspecific effect on the actual flux distribution. Knockout of ArcA-dependent redox regulation, however, increased the aerobic tricarboxylic acid (TCA) cycle activity by over 60%. Like aerobic conditions, anaerobic derepression of TCA cycle enzymes in an ArcA mutant significantly increased the in vivo TCA flux when nitrate was present as an electron acceptor. The in vivo and in vitro data demonstrate that ArcA-dependent transcriptional regulation directly or indirectly controls TCA cycle flux in both aerobic and anaerobic glucose batch cultures of E. coli. This control goes well beyond the previously known ArcA-dependent regulation of the TCA cycle during microaerobiosis.

  2. Association of Candidate Genes With Submergence Response in Perennial Ryegrass

    Directory of Open Access Journals (Sweden)

    Xicheng Wang

    2017-05-01

    Full Text Available Perennial ryegrass is a popular cool-season grass species due to its high quality for forage and turf. The objective of this study was to identify associations of candidate genes with growth and physiological traits to submergence stress and recovery after de-submergence in a global collection of 94 perennial ryegrass accessions. Accessions varied largely in leaf color, plant height (HT, leaf fresh weight (LFW, leaf dry weight (LDW, and chlorophyll fluorescence (Fv/Fm at 7 days of submergence and in HT, LFW and LDW at 7 days of recovery in two experiments. Among 26 candidate genes tested by various models, single nucleotide polymorphisms (SNPs in 10 genes showed significant associations with traits including 16 associations for control, 10 for submergence, and 8 for recovery. Under submergence, Lp1-SST encoding sucrose:sucrose 1-fructosyltransferase and LpGA20ox encoding gibberellin 20-oxidase were associated with LFW and LDW, and LpACO1 encoding 1-aminocyclopropane-1-carboxylic acid oxidase was associated with LFW. Associations between Lp1-SST and HT, Lp6G-FFT encoding fructan:fructan 6G-fructosyltransferase and Fv/Fm, LpCAT encoding catalase and HT were also detected under submergence stress. Upon de-submergence, Lp1-SST, Lp6G-FFT, and LpPIP1 encoding plasma membrane intrinsic protein type 1 were associated with LFW or LDW, while LpCBF1b encoding C-repeat binding factor were associated with HT. Nine significant SNPs in Lp1-SST, Lp6G-FFT, LpCAT, and LpACO1 resulted in amino acid changes with five substitutions found in Lp1-SST under submergence or recovery. The results indicated that allelic diversity in genes involved in carbohydrate and antioxidant metabolism, ethylene and gibberellin biosynthesis, and transcript factor could contribute to growth variations in perennial ryegrass under submergence stress and recovery after de-submergence.

  3. Tokamak ARC damage

    International Nuclear Information System (INIS)

    Murray, J.G.; Gorker, G.E.

    1985-01-01

    Tokamak fusion reactors will have large plasma currents of approximately 10 MA with hundreds of megajoules stored in the magnetic fields. When a major plasma instability occurs, the disruption of the plasma current induces voltage in the adjacent conducting structures, giving rise to large transient currents. The induced voltages may be sufficiently high to cause arcing across sector gaps or from one protruding component to another. This report reviews a tokamak arcing scenario and provides guidelines for designing tokamaks to minimize the possibility of arc damage

  4. Tokamak ARC damage

    Energy Technology Data Exchange (ETDEWEB)

    Murray, J.G.; Gorker, G.E.

    1985-01-01

    Tokamak fusion reactors will have large plasma currents of approximately 10 MA with hundreds of megajoules stored in the magnetic fields. When a major plasma instability occurs, the disruption of the plasma current induces voltage in the adjacent conducting structures, giving rise to large transient currents. The induced voltages may be sufficiently high to cause arcing across sector gaps or from one protruding component to another. This report reviews a tokamak arcing scenario and provides guidelines for designing tokamaks to minimize the possibility of arc damage.

  5. Metal halide arc discharge lamp having short arc length

    Science.gov (United States)

    Muzeroll, Martin E. (Inventor)

    1994-01-01

    A metal halide arc discharge lamp includes a sealed light-transmissive outer jacket, a light-transmissive shroud located within the outer jacket and an arc tube assembly located within the shroud. The arc tube assembly includes an arc tube, electrodes mounted within the arc tube and a fill material for supporting an arc discharge. The electrodes have a spacing such that an electric field in a range of about 60 to 95 volts per centimeter is established between the electrodes. The diameter of the arc tube and the spacing of the electrodes are selected to provide an arc having an arc diameter to arc length ratio in a range of about 1.6 to 1.8. The fill material includes mercury, sodium iodide, scandium tri-iodide and a rare gas, and may include lithium iodide. The lamp exhibits a high color rendering index, high lumen output and high color temperature.

  6. Improved, Low-Stress Economical Submerged Pipeline

    Science.gov (United States)

    Jones, Jack A.; Chao, Yi

    2011-01-01

    A preliminary study has shown that the use of a high-strength composite fiber cloth material may greatly reduce fabrication and deployment costs of a subsea offshore pipeline. The problem is to develop an inexpensive submerged pipeline that can safely and economically transport large quantities of fresh water, oil, and natural gas underwater for long distances. Above-water pipelines are often not feasible due to safety, cost, and environmental problems, and present, fixed-wall, submerged pipelines are often very expensive. The solution is to have a submerged, compliant-walled tube that when filled, is lighter than the surrounding medium. Some examples include compliant tubes for transporting fresh water under the ocean, for transporting crude oil underneath salt or fresh water, and for transporting high-pressure natural gas from offshore to onshore. In each case, the fluid transported is lighter than its surrounding fluid, and thus the flexible tube will tend to float. The tube should be ballasted to the ocean floor so as to limit the motion of the tube in the horizontal and vertical directions. The tube should be placed below 100-m depth to minimize biofouling and turbulence from surface storms. The tube may also have periodic pumps to maintain flow without over-pressurizing, or it can have a single pump at the beginning. The tube may have periodic valves that allow sections of the tube to be repaired or maintained. Some examples of tube materials that may be particularly suited for these applications are non-porous composite tubes made of high-performance fibers such as Kevlar, Spectra, PBO, Aramid, carbon fibers, or high-strength glass. Above-ground pipes for transporting water, oil, and natural gas have typically been fabricated from fiber-reinforced plastic or from more costly high-strength steel. Also, previous suggested subsea pipeline designs have only included heavy fixed-wall pipes that can be very expensive initially, and can be difficult and expensive

  7. Vacuum arc anode phenomena

    International Nuclear Information System (INIS)

    Miller, H.C.

    1976-01-01

    A brief review of anode phenomena in vacuum arcs is presented. Discussed in succession are: the transition of the arc into the anode spot mode; the temperature of the anode before, during and after the anode spot forms; and anode ions. Characteristically the anode spot has a temperature of the order of the atmospheric boiling point of the anode material and is a copious source of vapor and energetic ions. The dominant mechanism controlling the transition of the vacuum arc into the anode spot mode appears to depend upon the electrode geometry, the electrode material, and the current waveform of the particular vacuum arc being considered. Either magnetic constriction in the gap plasma or gross anode melting can trigger the transition; indeed, a combination of the two is a common cause of anode spot formation

  8. Workshop on ROVs and deep submergence

    Science.gov (United States)

    The deep-submergence community has an opportunity on March 6 to participate in a unique teleconferencing demonstration of a state-of-the-art, remotely operated underwater research vehicle known as the Jason-Medea System. Jason-Medea has been developed over the past decade by scientists, engineers, and technicians at the Deep Submergence Laboratory at Woods Hole Oceanographic Institution. The U.S. Navy, the Office of the Chief of Naval Research, and the National Science Foundation are sponsoring the workshop to explore the roles that modern computational, communications, and robotics technologies can play in deep-sea oceanographic research.Through the cooperation of Electronic Data Systems, Inc., the Jason Foundation, and Turner Broadcasting System, Inc., 2-1/2 hours of air time will be available from 3:00 to 5:30 PM EST on March 6. Twenty-seven satellite downlink sites will link one operating research vessel and the land-based operation with workshop participants in the United States, Canada, the United Kingdom, and Bermuda. The research ship Laney Chouest will be in the midst of a 3-week educational/research program in the Sea of Cortez, between Baja California and mainland Mexico. This effort is focused on active hydrothermal vents driven by heat flow from the volcanically active East Pacific Rise, which underlies the sediment-covered Guaymas Basin. The project combines into a single-operation, newly-developed robotic systems, state-of-the-art mapping and sampling tools, fiber-optic data transmission from the seafloor, instantaneous satellite communication from ship to shore, and a sophisticated array of computational and telecommunications networks. During the workshop, land-based scientists will observe and participate directly with their seagoing colleagues as they conduct seafloor research.

  9. Single-Arc IMRT?

    International Nuclear Information System (INIS)

    Bortfeld, Thomas; Webb, Steve

    2009-01-01

    The idea of delivering intensity-modulated radiation therapy (IMRT) with a multileaf collimator in a continuous dynamic mode during a single rotation of the gantry has recently gained momentum both in research and industry. In this note we investigate the potential of this Single-Arc IMRT technique at a conceptual level. We consider the original theoretical example case from Brahme et al that got the field of IMRT started. Using analytical methods, we derive deliverable intensity 'landscapes' for Single-Arc as well as standard IMRT and Tomotherapy. We find that Tomotherapy provides the greatest flexibility in shaping intensity landscapes and that it allows one to deliver IMRT in a way that comes close to the ideal case in the transverse plane. Single-Arc and standard IMRT make compromises in different areas. Only in relatively simple cases that do not require substantial intensity modulation will Single-Arc be dosimetrically comparable to Tomotherapy. Compared with standard IMRT, Single-Arc could be dosimetrically superior in certain cases if one is willing to accept the spreading of low dose values over large volumes of normal tissue. In terms of treatment planning, Single-Arc poses a more challenging optimization problem than Tomotherapy or standard IMRT. We conclude that Single-Arc holds potential as an efficient IMRT technique especially for relatively simple cases. In very complex cases, Single-Arc may unduly compromise the quality of the dose distribution, if one tries to keep the treatment time below 2 min or so. As with all IMRT techniques, it is important to explore the tradeoff between plan quality and the efficiency of its delivery carefully for each individual case. (note)

  10. [Algal control ability of allelopathically active submerged macrophytes: a review].

    Science.gov (United States)

    Xiao, Xi; Lou, Li-ping; Li, Hua; Chen, Ying-xu

    2009-03-01

    The inhibitory effect of allelochemicals released by submerged macrophytes on phytoplankton is considered as one of the mechanisms that contribute to the stabilization of clear-water status in shallow lakes. This paper reviewed the research progress in the allelopathy of submerged macrophytes on algae from the aspects of the occurrence frequency and coverage of allelopathically active submerged macrophytes in lakes, and the kinds and allelopathical effects of the allelochemicals released from the macrophytes. The previous researches indicated that allelopathically active submerged macrophyte species such as Myriophyllum, Ceratophyllum, and Elodea were efficient to control phytoplankton, especially when their biomass was high enough, and the dominant algae were sensitive species. The allelochemicals such as hydroxybenzene released by the submerged macrophytes could inhibit the growth of algae. Different phytoplankton species exhibited different sensitivity against allelochemicals, e.g., cyanobacteria and diatom were more sensitive than green algae, while epiphytic species were less sensitive than phytoplankton. Environmental factors such as light, temperature, and nutrients could significantly affect the allelopathical effect of submerged macrophytes. The research of the allelopathy of submerged macrophytes is still at its beginning, and further researches are needed on the effects of environmental factors on the allelopathy, extraction and identification of allelochemicals, selective algal control mechanisms, and metabolism of the allelochmicals.

  11. Quantification of the toughness distribution in a heavy section submerged arc multilayer reactor pressure vessel weldment

    International Nuclear Information System (INIS)

    Cerjak, H.; Prader, R.

    1999-01-01

    In a working procedure qualification test weld representing a heavy section circumferential reactor pressure vessel (RPV) weld tested in 1968, lower toughness values were observed in the top layer region compared to those found in the filler region. Gleeble simulation, extensive microscopic evaluation, diligent Charpy V-notch testing and modelling of the bead sequence and distribution of alloying elements was applied to explain this effect. It could be revealed that the microstructure of the weld metal is the most important factor influencing the toughness. When an 'as welded' microstructure is partly or fully reaustenitised by the adjacent multilayer beads, the microstructure transforms and the toughness increases. In the filler region, 85% of the cross-section consists from transformed microstructure, whereas in the top layer only 20% are transformed. It is quite evident that, accidentally, the notch tip of Charpy samples in 1968 were placed in untransformed microstructures. When the top layer on the inner surface of the RPV is weld cladded by austenitic stainless steel, full transformation occurs and the toughness representing the filler region can be taken into account for safety evaluations. (orig.)

  12. Toughness of submerged arc weld metals of controlled rolled NB bearing steel

    International Nuclear Information System (INIS)

    Yamaguchi, T.; Shiga, A.; Kamada, A.; Tsuboi, J.

    1982-01-01

    The toughness and the hardness of reheated weld metals depend on the maximum reheating temperature. When the maximum reheating temperature is 500 to 700 0 C, the hardness of single pass weld metal increases and the toughness decreases because of fine Nb- and V-carbonitride precipitation. When the maximum reheating temperature is over 800 0 C, the hardness and the toughness remain almost unchanged. The stress relieving treatment of single pass weld metal at 600 0 C for 1 up to about 100 hours causes the increase in hardness and then decreases the hardness gradually. It needs over 500 hours to obtain the same hardness value as that of as-welded metal. The addition of Ti to weld metal is very effective to improve the toughness, however excess Ti increases the hardness of stress relieved weld metal by precipitating as fine Ti-carbonitride. Therefore Ti addition should be restricted within the lowest limit required to improve as-welded metal toughness. The optimum Ti content is about 0.020% in the case of weld metal of which oxygen content is 350 ppM or so. In multipass welding, the hardness of weld metal affected by subsequent weld heat cycle varies from pass to pass, because Nb and V content change with the passes as the result of the change in dilution from base metal. The most hardened zone is observed in the reheated first pass weld metal, in which Nb and V content are the highest. Good weld metal toughness would be obtained by lowering dilution from base metal and taking advantage of grain refinement by subsequent passes

  13. Impacts of continental arcs on global carbon cycling and climate

    Science.gov (United States)

    Lee, C. T.; Jiang, H.; Carter, L.; Dasgupta, R.; Cao, W.; Lackey, J. S.; Lenardic, A.; Barnes, J.; McKenzie, R.

    2017-12-01

    On myr timescales, climatic variability is tied to variations in atmospheric CO2, which in turn is driven by geologic sources of CO2 and modulated by the efficiency of chemical weathering and carbonate precipitation (sinks). Long-term variability in CO2 has largely been attributed to changes in mid-ocean ridge inputs or the efficiency of global weathering. For example, the Cretaceous greenhouse is thought to be related to enhanced oceanic crust production, while the late Cenozoic icehouse is attributed to enhanced chemical weathering associated with the Himalayan orogeny. Here, we show that continental arcs may play a more important role in controlling climate, both in terms of sources and sinks. Continental arcs differ from island arcs and mid-ocean ridges in that the continental plate through which arc magmas pass may contain large amounts of sedimentary carbonate, accumulated over the history of the continent. Interaction of arc magmas with crustal carbonates via assimilation, reaction or heating can significantly add to the mantle-sourced CO2 flux. Detrital zircons and global mapping of basement rocks shows that the length of continental arcs in the Cretaceous was more than twice that in the mid-Cenozoic; maps also show many of these arcs intersected crustal carbonates. The increased length of continental arc magmatism coincided with increased oceanic spreading rates, placing convergent margins into compression, which favors continental arcs. Around 50 Ma, however, nearly all the continental arcs in Eurasia and North America terminated as India collided with Eurasia and the western Pacific rolled back, initiating the Marianas-Tonga-Kermadec intra-oceanic subduction complex and possibly leading to a decrease in global CO2 production. Meanwhile, extinct continental arcs continued to erode, resulting in regionally enhanced chemical weathering unsupported by magmatic fluxes of CO2. Continental arcs, during their magmatic lifetimes, are thus a source of CO2, driving

  14. Vibrational analysis of submerged cylindrical shells based on elastic foundations

    International Nuclear Information System (INIS)

    Shah, A.G.; Naeem, M.N.

    2014-01-01

    In this study a vibration analysis was performed of an isotropic cylindrical shell submerged in fluid, resting on Winkler and Pasternak elastic foundations for simply supported boundary condition. Love's thin shell theory was exploited for strain- and curvature- displacement relationship. Shell problem was solved by using wave propagation approach. Influence of fluid and Winkler as well as Pasternak elastic foundations were studied on the natural frequencies of submerged isotropic cylindrical shells. Results were validated by comparing with the existing results in literature. Vibration, Submerged cylindrical shell, Love's thin shell theory, Wave propagation method, Winkler and Pasternak foundations. (author)

  15. Stud arc welding in a magnetic field – Investigation of the influences on the arc motion

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  16. Continental Arcs as Both Carbon Source and Sink in Regulating Long Term Climate

    Science.gov (United States)

    Jiang, H.; Lee, C. T.

    2017-12-01

    The long-term variability of atmospheric pCO2 is determined by the balance between the rate of geologic inputs of CO­­2 (e.g., magmatic/metamorphic degassing, carbonate weathering) and the rate of carbonate precipitation driven by silicate weathering. The Late Cretaceous-Early Cenozoic was characterized by elevated atmospheric pCO2 and greenhouse climate, likely due to increased magmatic flux from mid-ocean ridges and, in particular, continental arcs. However, it has been suggested that continental arc magmatism is accompanied by rapid uplift and erosion due to magmatic/tectonic thickening of the crust, thus continental arcs likely enhance the chemical weathering flux, in turn increasing the carbon sink. To assess the contribution of continental arcs to global carbon inputs and sinks, we conducted a case study in the Cretaceous Peninsular Ranges batholith (PRB) and associated forearc basin in southern California, USA, representing one segment of the Cretaceous Cordillera arc-forearc system. Arc magmatism occurred between 170-85 Ma, peaking at 100 Ma, but erosion of the arc continues into the early Eocene, with forearc sediments representing this protracted arc unroofing. During magmatism, we estimate the CO2 degassing flux from the PRB was at least 5-25*105 mol·km-2·yr-1. By calculating the depletion of Ca and Mg in the forearc sediments relative to their arc protoliths, we estimate the silicate weathering/carbonate precipitation flux to be 106 mol·km-2·yr-1 during Late Cretaceous magmatism, decreasing to 105 mol·km-2·yr-1 by the Early Eocene. We show that during active continental arc magmatism, the CO2 degassing flux is comparable to CO2 consumption driven by silicate weathering in the arc. However, after magmatism ends, a regional imbalance arises in which the arc no longer contributes to CO2 inputs but continued silicate weathering of the arc drives carbonate precipitation such that the arc indirectly becomes CO2 sink. We propose that the development of

  17. Intra-Arc extension in Central America: Links between plate motions, tectonics, volcanism, and geochemistry

    Science.gov (United States)

    Phipps Morgan, Jason; Ranero, Cesar; Vannucchi, Paola

    2010-05-01

    This study revisits the kinematics and tectonics of Central America subduction, synthesizing observations of marine bathymetry, high-resolution land topography, current plate motions, and the recent seismotectonic and magmatic history in this region. The inferred tectonic history implies that the Guatemala-El Salvador and Nicaraguan segments of this volcanic arc have been a region of significant arc tectonic extension; extension arising from the interplay between subduction roll-back of the Cocos Plate and the ~10-15 mm/yr slower westward drift of the Caribbean plate relative to the North American Plate. The ages of belts of magmatic rocks paralleling both sides of the current Nicaraguan arc are consistent with long-term arc-normal extension in Nicaragua at the rate of ~5-10 mm/yr, in agreement with rates predicted by plate kinematics. Significant arc-normal extension can ‘hide' a very large intrusive arc-magma flux; we suggest that Nicaragua is, in fact, the most magmatically robust section of the Central American arc, and that the volume of intrusive volcanism here has been previously greatly underestimated. Yet, this flux is hidden by the persistent extension and sediment infill of the rifting basin in which the current arc sits. Observed geochemical differences between the Nicaraguan arc and its neighbors which suggest that Nicaragua has a higher rate of arc-magmatism are consistent with this interpretation. Smaller-amplitude, but similar systematic geochemical correlations between arc-chemistry and arc-extension in Guatemala show the same pattern as the even larger variations between the Nicaragua arc and its neighbors. We are also exploring the potential implications of intra-arc extension for deformation processes along the subducting plate boundary and within the forearc ‘microplate'.

  18. Plasma drifts associated with a system of sun-aligned arcs in the polar cap

    International Nuclear Information System (INIS)

    Mende, S.B.; Doolittle, J.H.; Robinson, R.M.; Vondrak, R.R.; Rich, F.J.

    1988-01-01

    A series of four sun-aligned arcs passed over Sondre Stromfjord, Greenland, on the night of the 17th and 18th of February, 1985. Observations of these arcs were made using the Sondrestrom incoherent scatter radar and an intensified all-sky imaging TV system that was operated at the radar site. The first of the four arcs crossed the Sondre Stromfjord meridian just before local midnight moving westward, and the other three arcs followed at approximately half-hour intervals. When we account for the earth's rotation, the arc drift in an inertial frame was eastward, or dusk to dawn. The half-hour interval between meridian crossings of the arcs implies that the mean spacing between the arcs was 180 km. A Defense Meteorological Satellite Program (DMSP) F6 satellite pass at 0110 UT revealed the presence of highly structured electron and ion precipitation throughout the polar cap. The DMSP visible imager detected a single, sun-aligned arc associated with the largest peak in precipitating electron flux. This arc was also observed at Thule, Greenland, with an intensified film camera. These observations suggest that at least one of the arcs that were observed at Sondre Stromfjord extended across a large part of the polar cap. The radar at Sondre Stromfjord measured electron density and ion drift velocities associated with the four arcs. The radar drift measurements were superimposed on the all-sky video images to determine the location of the measurements relative to the arcs. Plasma drifts outside the arcs were found to be both sunward and antisunward, while within the arcs the drifts were predominantly antisunward. The variability of the drifts in the direction parallel to the arcs indicates that the electric fields were highly structured even though the configuration and motion of the arcs were well behaved

  19. Consolidating NASA's Arc Jets

    Science.gov (United States)

    Balboni, John A.; Gokcen, Tahir; Hui, Frank C. L.; Graube, Peter; Morrissey, Patricia; Lewis, Ronald

    2015-01-01

    The paper describes the consolidation of NASA's high powered arc-jet testing at a single location. The existing plasma arc-jet wind tunnels located at the Johnson Space Center were relocated to Ames Research Center while maintaining NASA's technical capability to ground-test thermal protection system materials under simulated atmospheric entry convective heating. The testing conditions at JSC were reproduced and successfully demonstrated at ARC through close collaboration between the two centers. New equipment was installed at Ames to provide test gases of pure nitrogen mixed with pure oxygen, and for future nitrogen-carbon dioxide mixtures. A new control system was custom designed, installed and tested. Tests demonstrated the capability of the 10 MW constricted-segmented arc heater at Ames meets the requirements of the major customer, NASA's Orion program. Solutions from an advanced computational fluid dynamics code were used to aid in characterizing the properties of the plasma stream and the surface environment on the calorimeters in the supersonic flow stream produced by the arc heater.

  20. ALICE-ARC integration

    International Nuclear Information System (INIS)

    Anderlik, C; Gregersen, A R; Kleist, J; Peters, A; Saiz, P

    2008-01-01

    AliEn or Alice Environment is the Grid middleware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The inter-operation has two aspects, one is the data management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. Therefore, we will concentrate on the second part. Solving it, was somewhat cumbersome, mainly due to the different computing models employed by AliEn and ARC. AliEN uses an Agent based pull model while ARC handles jobs through the more 'traditional' push model. The solution comes as a module implementing the functionalities necessary to achieve AliEn job submission and management to ARC enabled sites

  1. Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Geoform

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...

  2. Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Geodatabase

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...

  3. Submerged Aquatic Vegetation of Bogue Sound, North Carolina 1992 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — During 1992, 1:20,000 scale aerial photography for Bogue Sound, North Carolina was collected as part of an effort to map submerged aquatic vegetation (SAV) in...

  4. Supporting Calculations For Submerged Bed Scrubber Condensate Disposal Preconceptual Study

    International Nuclear Information System (INIS)

    Pajunen, A. J.; Tedeschi, A. R.

    2012-01-01

    This document provides supporting calculations for the preparation of the Submerged Bed Scrubber Condensate Disposal Preconceptual Study report. The supporting calculations include equipment sizing, Hazard Category determination, and LAW Melter Decontamination Factor Adjustments

  5. Marine algal flora of submerged Angria Bank (Arabian Sea)

    Digital Repository Service at National Institute of Oceanography (India)

    Untawale, A.G.; Reddy, C.R.K.; Ambiye, V.

    Submerged Angria Bank was surveyed for the deep water marine algal flora. About 57 species were reported from this bank for the first time. Rhodophyta dominated (30 species) followed by Chlorophyta (18 species) and Phaeophyta (9 species). A few...

  6. Submergence tolerance in Hordeum marinum

    DEFF Research Database (Denmark)

    Pedersen, Ole; Malik, Al I.; Colmer, Timothy D.

    2010-01-01

    Floodwaters differ markedly in dissolved CO(2), yet the effects of CO(2) on submergence responses of terrestrial plants have rarely been examined. The influence of dissolved CO(2) on underwater photosynthesis and growth was evaluated for three accessions of the wetland plant Hordeum marinum Huds....... All three accessions tolerated complete submergence, but only when in CO(2) enriched floodwater. Plants submerged for 7 days in water at air equilibrium (18 mM CO(2)) suffered loss of biomass, whereas those with 200 mM CO(2) continued to grow. Higher underwater net photosynthesis at 200 mM CO(2......) increased by 2.7- to 3.2-fold sugar concentrations in roots of submerged plants, compared with at air equilibrium CO(2). Leaf gas films enhancing gas exchange with floodwater, lack of a shoot elongation response conserving tissue sugars and high tissue porosity (24-31% in roots) facilitating internal O(2...

  7. Canopy Modeling of Aquatic Vegetation: Construction of Submerged Vegetation Index

    Science.gov (United States)

    Ma, Z.; Zhou, G.

    2018-04-01

    The unique spectral characteristics of submerged vegetation in wetlands determine that the conventional terrestrial vegetation index cannot be directly employed to species identification and parameter inversion of submerged vegetation. Based on the Aquatic Vegetation Radiative Transfer model (AVRT), this paper attempts to construct an index suitable for submerged vegetation, the model simulated data and a scene of Sentinel-2A image in Taihu Lake, China are utilized for assessing the performance of the newly constructed indices and the existent vegetation indices. The results show that the angle index composed by 525 nm, 555 nm and 670 nm can resist the effects of water columns and is more sensitive to vegetation parameters such as LAI. Furthermore, it makes a well discrimination between submerged vegetation and water bodies in the satellite data. We hope that the new index will provide a theoretical basis for future research.

  8. Durability performance of submerged concrete structures - phase 2.

    Science.gov (United States)

    2015-09-01

    This project determined that severe corrosion of steel can occur in the submerged : portions of reinforced concrete structures in marine environments. Field studies of decommissioned : pilings from Florida bridges revealed multiple instances of stron...

  9. Supporting Calculations For Submerged Bed Scrubber Condensate Disposal Preconceptual Study

    Energy Technology Data Exchange (ETDEWEB)

    Pajunen, A. J.; Tedeschi, A. R.

    2012-09-18

    This document provides supporting calculations for the preparation of the Submerged Bed Scrubber Condensate Disposal Preconceptual Study report The supporting calculations include equipment sizing, Hazard Category determination, and LAW Melter Decontamination Factor Adjustments.

  10. Evidence that polar cap arcs occur on open field lines

    International Nuclear Information System (INIS)

    Gussenhoven, M.S.; Hardy, D.A.; Rich, F.J.; Mullen, E.G.; Redus, R.H.

    1990-01-01

    The characteristics of polar cap arc occurrence are reviewed to show that the assumption of a closed magnetospheric magnetic field topology at very high latitudes when the IMF B z is strongly northward is difficult to reconcile with a wide variety of observational and theoretical considerations. In particular, we consider the implications of observations of particle entry for high and low energy electrons, magnetic flux conservation between the near and far tail, the time sequencing in polar cap arcs events, and the hemispherical differences in polar cap arc observations. These points can be explained either by excluding the need for a major topological magnetic field change from explanations of polar cap arc dynamics, or by assuming a long-tailed magnetosphere for all IMF orientations in which magnetic field lines eventually merge with solar wind field lines in either a smooth or a patchy fashion. (author)

  11. Impeded Carbohydrate Metabolism in Rice Plants under Submergence Stress

    Directory of Open Access Journals (Sweden)

    Malay Kumar ADAK

    2011-06-01

    Full Text Available The detrimental effects of submergence on physiological performances of some rice varieties with special references to carbohydrate metabolisms and their allied enzymes during post-flowering stages have been documented and clarified in the present investigation. It was found that photosynthetic rate and concomitant translocation of sugars into the panicles were both related to the yield. The detrimental effects of the complete submergence were recorded in generation of sucrose, starch, sucrose phosphate synthase and phosphorylase activity in the developing panicles of the plants as compared to those under normal or control (i.e. non-submerged condition. The accumulation of starch was significantly lower in plants under submergence and that was correlated with ADP-glucose pyrophosphorylase activity. Photosynthetic rate was most affected under submergence in varying days of post-flowering and was also related to the down regulation of Ribulose bisphosphate carboxylase activity. However, under normal or control condition, there recorded a steady maintenance of photosynthetic rate at the post-flowering stages and significantly higher values of Ribulose bisphosphate carboxylase activity. Still, photosynthetic rate of the plants under both control and submerged conditions had hardly any significant correlation with sugar accumulation and other enzymes of carbohydrate metabolism like invertase with grain yield. Finally, plants under submergence suffered significant loss of yield by poor grain filling which was related to impeded carbohydrate metabolism in the tissues. It is evident that loss of yield under submergence is attributed both by lower sink size or sink capacity (number of panicles, in this case as well as subdued carbohydrate metabolism in plants and its subsequent partitioning into the grains.

  12. Application of submerged induction hardening; Ekichu koshuha yakiire no jitsuyoka

    Energy Technology Data Exchange (ETDEWEB)

    Nishimori, Y; Nagai, Y; Amii, Y [Mazda Motor Corp., Hiroshima (Japan); Tanaka, Y [Netsuren Co. Ltd., Tokyo (Japan); Mizuma, T [Toyo Advanced Technologies Co. Ltd., Hiroshima (Japan)

    1997-10-01

    As a cost-cutting measure, the linerless diesel engine was adopted by applying submerged induction hardening process which can harden partial inner surface of cylinder block bore. In applying this process, (1) development of induction coil which can form any shape of quenched pattern and (2) the development of machining technology which can hone precisely the distorted bore after quenching, were important. With these improvements, submerged Induction hardening was made practical. 1 ref., 11 figs.

  13. Effective mass and damping of submerged structures

    International Nuclear Information System (INIS)

    Dong, R.G.

    1979-01-01

    A number of structures important for safety in nuclear power plants are submerged in water. These include spent fuel storage racks, main pressure relief valve lines, and internal structures in the reactor vessel. Dynamic analyses of such structures must include the force and damping effects of water. A wide variety of modeling assumptions are being used in design analyses, and currently there are no uniform positions by which to judge the adequacy of the assumptions . A study was caried out to establish a technical basis for evaluating the assymptions and to recommend suitable methods to describe the effects of the water. The results of the study were based on information published in the literature or conveyed by industrial firms. A survey of 32 firms and 49 technical references was carried out. Heavy emphasis was placed on validating the results with available experimental data. The information collected apply generally to idealized structures such as single isolated members, arrays of members and coaxial cylinders. The results of the study are categorized with respect to such idealized structures, and the applicability to actual reactor structures was discussed through observations and recommendations. (orig.)

  14. Effective mass and damping of submerged structures

    International Nuclear Information System (INIS)

    Dong, R.G.

    1978-01-01

    Various structures important for safety in nuclear power plants must remain functioning in the event of an earthquake or other dynamic phenomenon. Some of these important structures, such as spent-fuel storage racks, main pressure-relief valve lines, and internal structures in the reactor vessel, are submerged in water. Dynamic analysis must include the force and damping effects of water. This report provides a technical basis for evaluating the wide variety of modeling assumptions currently used in design analysis. Current design analysis techniques and information in the literature form the basis of our conclusions and recommendations. We surveyed 32 industrial firms and reviewed 49 technical references. We compare various theories with published experimental results wherever possible. Our findings generally pertain to idealized structures, such as single isolated members, arrays of members, and coaxial cylinders. We relate these findings to the actual reactor structures through observations and recommendations. Whenever possible we recommend a definite way to evaluate the effect of hydrodynamic forces on these structures

  15. Vacuum Arc Ion Sources

    CERN Document Server

    Brown, I.

    2013-12-16

    The vacuum arc ion source has evolved into a more or less standard laboratory tool for the production of high-current beams of metal ions, and is now used in a number of different embodiments at many laboratories around the world. Applications include primarily ion implantation for material surface modification research, and good performance has been obtained for the injection of high-current beams of heavy-metal ions, in particular uranium, into particle accelerators. As the use of the source has grown, so also have the operational characteristics been improved in a variety of different ways. Here we review the principles, design, and performance of vacuum arc ion sources.

  16. Investigation of arcing on fiber-formed nanostructured tungsten by pulsed plasma during steady state plasma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Yajima, M., E-mail: yajima.miyuki@LHD.nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, 509-5292 Japan (Japan); Ohno, N. [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kajita, S. [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); De Temmerman, G. [ITER Organization, Route de Vinon sur Verdon, CS 90 046-13067 St Paul Lez Durance Cedex (France); Bystrov, K.; Bardin, S.; Morgan, T.W. [FOM Institute DIFFER, Dutch Institute for Fundamental Energy Research, Partner in the Trilateral Euregio Cluster, 5612 AJ Eindhoven (Netherlands); Masuzaki, S. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, 509-5292 Japan (Japan)

    2016-11-15

    Arcing on fiber-formed nanostructured tungsten samples during ELM-like pulses was investigated using the superimposition of high power pulsed plasma on a steady state plasma with hydrogen gas in the linear plasma device Pilot-PSI. The ignition of arcing was observed when the floating potential of the samples was less than −75 V with sufficient heat flux. The surface observation showed that the arc spots were not in the center, but in the peripheral area of the plasma column. Considering the plasma potential profile in the Pilot-PSI, the arcing occurred at the position where the heat flux and the sheath potential drop are sufficiently large.

  17. Arc Heated Scramjet Test Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Arc Heated Scramjet Test Facility is an arc heated facility which simulates the true enthalpy of flight over the Mach number range of about 4.7 to 8 for free-jet...

  18. Electric contact arcing

    International Nuclear Information System (INIS)

    Cuthrell, R.E.

    1976-01-01

    Electrical contacts must function properly in many types of components used in nuclear weapon systems. Design, application, and testing of these components require detailed knowledge of chemical and physical phenomena associated with stockpile storage, stockpile testing, and operation. In the past, investigation of these phenomena has led to significant discoveries on the effects of surface contaminants, friction and wear, and the mechanics of closure on contact performance. A recent investigation of contact arcing phenomena which revealed that, preceding contact closure, arcs may occur at voltages lower than had been previously known is described. This discovery is important, since arcing may damage contacts, and repetitive testing of contacts performed as part of a quality assurance program might produce cumulative damage that would yield misleading life-test data and could prevent proper operation of the contacts at some time in the future. This damage can be avoided by determining the conditions under which arcing occurs, and ensuring that these conditions are avoided in contact testing

  19. Thermal Arc Spray Overview

    Science.gov (United States)

    Hafiz Abd Malek, Muhamad; Hayati Saad, Nor; Kiyai Abas, Sunhaji; Mohd Shah, Noriyati

    2013-06-01

    Usage of protective coating for corrosion protection was on highly demand during the past decade; and thermal spray coating played a major part during that time. In recent years, the thermal arc spray coating becomes a popular coating. Many big players in oil and gas such as PETRONAS, EXXON MOBIL and SHELL in Malaysia tend to use the coating on steel structure as a corrosion protection. Further developments in coating processes, the devices, and raw materials have led to expansion of functional coatings and applications scope from conventional coating to specialized industries. It is widely used because of its ability to withstand high process temperature, offer advantages in efficiency, lower cost and acts as a corrosion protection. Previous research also indicated that the thermal arc spray offers better coating properties compared to other methods of spray. This paper reviews some critical area of thermal spray coating by discussing the process/parameter of thermal arc spray technology and quality control of coating. Coating performance against corrosion, wear and special characteristic of coating are also described. The field application of arc spray technology are demonstrated and reviewed.

  20. Circular arc structures

    KAUST Repository

    Bo, Pengbo; Pottmann, Helmut; Kilian, Martin; Wang, Wen Ping; Wallner, Johannes

    2011-01-01

    and connecting elements as well as repetition of costly parts. This paper proposes so-called circular arc structures as a means to faithfully realize freeform designs without giving up smooth appearance. In contrast to non-smooth meshes with straight edges where

  1. ALICE-ARC integration

    DEFF Research Database (Denmark)

    Anderlik, Csaba; Gregersen, Anders Rhod; Kleist, Josva

    2008-01-01

    Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The interoperation has two aspects, one is the data...

  2. Thermal Arc Spray Overview

    International Nuclear Information System (INIS)

    Malek, Muhamad Hafiz Abd; Saad, Nor Hayati; Abas, Sunhaji Kiyai; Shah, Noriyati Mohd

    2013-01-01

    Usage of protective coating for corrosion protection was on highly demand during the past decade; and thermal spray coating played a major part during that time. In recent years, the thermal arc spray coating becomes a popular coating. Many big players in oil and gas such as PETRONAS, EXXON MOBIL and SHELL in Malaysia tend to use the coating on steel structure as a corrosion protection. Further developments in coating processes, the devices, and raw materials have led to expansion of functional coatings and applications scope from conventional coating to specialized industries. It is widely used because of its ability to withstand high process temperature, offer advantages in efficiency, lower cost and acts as a corrosion protection. Previous research also indicated that the thermal arc spray offers better coating properties compared to other methods of spray. This paper reviews some critical area of thermal spray coating by discussing the process/parameter of thermal arc spray technology and quality control of coating. Coating performance against corrosion, wear and special characteristic of coating are also described. The field application of arc spray technology are demonstrated and reviewed.

  3. THE ARC TRAIL

    African Journals Online (AJOL)

    INTRODUCTION. The project, carried out by the 1985 Conservation. Team at Durban Girls1 High School, consisted of three main aims- Awareness, Recreation and conservation, which were incorporated into the naming of the ARC trail. The trail is situated in suburban Durban where it was felt that it was important to ...

  4. ARC Software and Models

    Science.gov (United States)

    Archives RESEARCH ▼ Research Areas Ongoing Projects Completed Projects SOFTWARE CONTACT ▼ Primary Contacts Researchers External Link MLibrary Deep Blue Software Archive Most research conducted at the ARC produce software code and methodologies that are transferred to TARDEC and industry partners. These

  5. ALICE: ARC integration

    CERN Document Server

    Anderlik, C; Kleist, J; Peters, A; Saiz, P

    2008-01-01

    AliEn or Alice Environment is the Grid middleware developed and used within the ALICE collaboration for storing and processing data in a distributed manner. ARC (Advanced Resource Connector) is the Grid middleware deployed across the Nordic countries and gluing together the resources within the Nordic Data Grid Facility (NDGF). In this paper we will present our approach to integrate AliEn and ARC, in the sense that ALICE data management and job processing can be carried out on the NDGF infrastructure, using the client tools available in AliEn. The inter-operation has two aspects, one is the data management part and the second the job management aspect. The first aspect was solved by using dCache across NDGF to handle data. Therefore, we will concentrate on the second part. Solving it, was somewhat cumbersome, mainly due to the different computing models employed by AliEn and ARC. AliEN uses an Agent based pull model while ARC handles jobs through the more 'traditional' push model. The solution comes as a modu...

  6. Submerged cultivation of medicinal mushrooms: bioprocesses and products (review).

    Science.gov (United States)

    Elisashvili, Vladimir

    2012-01-01

    Medicinal mushrooms belonging to higher Basidiomycetes are an immensely rich yet largely untapped resource of useful, easily accessible, natural compounds with various biological activities that may promote human well-being. The medicinal properties are found in various cellular components and secondary metabolites (polysaccharides, proteins and their complexes, phenolic compounds, polyketides, triterpenoids, steroids, alkaloids, nucleotides, etc.), which have been isolated and identified from the fruiting bodies, culture mycelium, and culture broth of mushrooms. Some of these compounds have cholesterol-lowering, anti-diabetic, antioxidant, antitumor, immunomodulating, antimicrobial, and antiviral activities ready for industrial trials and further commercialization, while others are in various stages of development. Recently, the submerged cultivation of medicinal mushrooms has received a great deal of attention as a promising and reproducible alternative for the efficient production of mushroom mycelium and metabolites. Submerged cultivation of mushrooms has significant industrial potential, but its success on a commercial scale depends on increasing product yields and development of novel production systems that address the problems associated with this technique of mushroom cultivation. In spite of many researchers' efforts for the production of bioactive metabolites by mushrooms, the physiological and engineering aspects of submerged cultures are still far from being thoroughly studied. The vast majority of studies have focused on polysaccharide and ganoderic acid production in submerged cultivation of medicinal mushrooms, and very little has been written so far on the antioxidant and hemagglutinating activity of submerged mushroom cultures. The purpose of this review is to provide an update of the present state of the art and future prospects of submerged cultivation of medicinal mushrooms to produce mycelium and bioactive metabolites, and to make a

  7. Differential preservation in the geologic record of intraoceanic arc sedimentary and tectonic processes

    Science.gov (United States)

    Draut, Amy; Clift, Peter D.

    2013-01-01

    Records of ancient intraoceanic arc activity, now preserved in continental suture zones, are commonly used to reconstruct paleogeography and plate motion, and to understand how continental crust is formed, recycled, and maintained through time. However, interpreting tectonic and sedimentary records from ancient terranes after arc–continent collision is complicated by preferential preservation of evidence for some arc processes and loss of evidence for others. In this synthesis we examine what is lost, and what is preserved, in the translation from modern processes to the ancient record of intraoceanic arcs. Composition of accreted arc terranes differs as a function of arc–continent collision geometry. ‘Forward-facing’ collision can accrete an oceanic arc on to either a passive or an active continental margin, with the arc facing the continent and colliding trench- and forearc-side first. In a ‘backward-facing’ collision, involving two subduction zones with similar polarity, the arc collides backarc-first with an active continental margin. The preservation of evidence for contemporary sedimentary and tectonic arc processes in the geologic record depends greatly on how well the various parts of the arc survive collision and orogeny in each case. Preservation of arc terranes likely is biased towards those that were in a state of tectonic accretion for tens of millions of years before collision, rather than tectonic erosion. The prevalence of tectonic erosion in modern intraoceanic arcs implies that valuable records of arc processes are commonly destroyed even before the arc collides with a continent. Arc systems are most likely to undergo tectonic accretion shortly before forward-facing collision with a continent, and thus most forearc and accretionary-prism material in ancient arc terranes likely is temporally biased toward the final stages of arc activity, when sediment flux to the trench was greatest and tectonic accretion prevailed. Collision geometry

  8. Time-varying Entry Heating Profile Replication with a Rotating Arc Jet Test Article

    Science.gov (United States)

    Grinstead, Jay Henderson; Venkatapathy, Ethiraj; Noyes, Eric A.; Mach, Jeffrey J.; Empey, Daniel M.; White, Todd R.

    2014-01-01

    A new approach for arc jet testing of thermal protection materials at conditions approximating the time-varying conditions of atmospheric entry was developed and demonstrated. The approach relies upon the spatial variation of heat flux and pressure over a cylindrical test model. By slowly rotating a cylindrical arc jet test model during exposure to an arc jet stream, each point on the test model will experience constantly changing applied heat flux. The predicted temporal profile of heat flux at a point on a vehicle can be replicated by rotating the cylinder at a prescribed speed and direction. An electromechanical test model mechanism was designed, built, and operated during an arc jet test to demonstrate the technique.

  9. Experimental investigation on fluid flow and heat transfer characteristics of a submerged combustion vaporizer

    International Nuclear Information System (INIS)

    Han, Chang-Liang; Ren, Jing-Jie; Wang, Yan-Qing; Dong, Wen-Ping; Bi, Ming-Shu

    2017-01-01

    Highlights: • Thermal performance analysis of submerged combustion vaporizer (SCV) was performed experimentally. • Visualization study of shell-side flow field for SCV was carried out. • The effects of various operational parameters on the overall system performance were discussed. • Two new non-dimensional Nusselt correlations were proposed to predict the heat transfer performance of SCV. - Abstract: Submerged combustion vaporizer (SCV) occupies a decisive position in liquefied natural gas (LNG) industrial chain. In this paper, a visual experimental apparatus was established to have a comprehensive knowledge about fluid flow and heat transfer performance of SCV. Trans-critical liquid nitrogen (LN_2) was selected as alternative fluid to substitute LNG because of safety reason. Some unique experimental phenomena inside the SCV (local water bath freezes on the external surface of tube bundle) were revealed. Meanwhile the influences of static water height, superficial flue gas velocity, heat load, tube-side inlet pressure and tube-side mass flux on the system performance were systematically discussed. Finally, based on the obtained experimental results, two new empirical Nusselt number correlations were regressed to predict the shell-side and tube-side heat transfer characteristics of SCV. The maximum errors between predicted results and experimental data were respectively ±25% and ±20%. The outcomes of this paper were critical to the optimum design and economical operation of SCV.

  10. Mathematical Modelling of Nitrate Removal from Water Using a Submerged Membrane Adsorption Hybrid System with Four Adsorbents

    Directory of Open Access Journals (Sweden)

    Mahatheva Kalaruban

    2018-01-01

    Full Text Available Excessive concentrations of nitrate in ground water are known to cause human health hazards. A submerged membrane adsorption hybrid system that includes a microfilter membrane and four different adsorbents (Dowex 21K XLT ion exchange resin (Dowex, Fe-coated Dowex, amine-grafted (AG corn cob and AG coconut copra operated at four different fluxes was used to continuously remove nitrate. The experimental data obtained in this study was simulated mathematically with a homogeneous surface diffusion model that incorporated membrane packing density and membrane correlation coefficient, and applied the concept of continuous flow stirred tank reactor. The model fit with experimental data was good. The surface diffusion coefficient was constant for all adsorbents and for all fluxes. The mass transfer coefficient increased with flux for all adsorbents and generally increased with the adsorption capacity of the adsorbents.

  11. Preliminary Analysis of a Submerged Wave Energy Device

    Science.gov (United States)

    Wagner, J. R.; Wagner, J. J.; Hayatdavoodi, M.; Ertekin, R. C.

    2016-02-01

    Preliminary analysis of a submerged wave energy harvesting device is presented. The device is composed of a thin, horizontally submerged plate that is restricted to heave oscillations under the influence of surface waves. The submerged plate is oscillating, and it can be attached to a fixed rotor, or a piston, to harvest the wave energy. A fully submerged wave energy converter is preferred over a surface energy convertor due to its durability and less visual and physical distractions it presents. In this study, the device is subject to nonlinear shallow-water waves. Wave loads on the submerged oscillating plate are obtained via the Level I Green-Naghdi equations. The unsteady motion of the plate is obtained by solving the nonlinear equations of motion. The results are obtained for a range of waves with varying heights and periods. The amplitude and period of plate oscillations are analyzed as functions of the wave parameters and plate width. Particular attention is given to the selection of the site of desired wave field. Initial estimation on the amount of energy extraction from the device, located near shore at a given site, is provided.

  12. Demonstration and Field Evaluation of Streambank Stabilization with Submerged Vanes

    Science.gov (United States)

    Whitman, H.; Hoopes, J.; Poggi, D.; Fitzpatrick, F.; Walz, K.; ,

    2001-01-01

    The effectiveness of submerged vanes for reducing bank erosion and improving aquatic habitat is being evaluated at a site on North Fish Creek, a Lake Superior tributary. Increased runoff from agricultural areas with clayey soils has increased flood magnitudes and the erosion potential/transport capacity of the stream. Most of the creek's sediment load originates from the erosion of 17 large bluffs. This creek contains important recreational fisheries that are potentially limited by the loss of aquatic habitat from deposition of sediment on spawning beds. Submerged vanes are a cost effective and environmentally less intrusive alternative to traditional structural stabilization measures. Submerged vanes protrude from a channel bed, are oriented at an angle to the local velocity, and are distributed along a portion of channel. They induce a transverse force and torque on the flow along with longitudinal vortexes that alter the cross sectional shape and alignment of the channel. Submerged vanes were installed at a bluff/bend site in summer and fall 2000. The number, size, and layout of the vanes were based upon the channel morphology under estimated bankfull conditions. The effectiveness of the vanes will be evaluated by comparing surveys of the bluff face, streamflow, and channel conditions for several years after installation of the submerged vanes with surveys before and immediately after their installation.

  13. Ionization and electric field properties of auroral arcs during magnetic quiescence

    International Nuclear Information System (INIS)

    Robinson, R.M.; Mende, S.B.

    1990-01-01

    Studies of the morphology of auroral precipitation during times of magnetic quiescence indicate that the polar cap shrinks and becomes distorted into a teardrop or pear-shaped region. On November 16, 1987, incoherent scatter radar and all-sky imaging photometer measurements were made of auroral arcs over Sondre Stromfjord, Greenland. The arcs were generally oriented in a geographic east-west direction which is approximately Sun aligned at a local time just after dusk. Kp was 1, and the interlplanetary magnetic field was northward during the time of observation, so tha the arcs occurred under magnetically quiet conditions. The Sondrestrom radar measurements were used to determine the electron density and plasma drifts associated with the arcs; the all-sky imaging photometer data were used to relate the radar measurements to the arc morphology. Assuming the arcs were produced by precipitating electrons, the height profiles of electron density indicate average energies less than about 2 keV and energy fluxes of 1 erg/(cm 2 s). F region electron densities were high in the polar cap north of the arcs and low within the region of the arcs. The poleward boundary of the arc system was a convection reversal boundary across which plasma exited the polar cap region moving antisunward and then turned sunward (westward). The observed arc-associated convection is consistent with that expected under these geomagnetic conditions. Comparison of these results with the electrodynamic properties of other arcs observed in the afternoon and early evening suggests that there is a system of arcs that delineates the afternoon convection cell. The observed gradient in F region electron density across the arc can be explained in terms of the recombination of ionization drifting in response to the arc-associated convection pattern

  14. Vacuum arcing behavior between transverse magnetic field contacts subjected to variable axial magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Hui; Wang, Jianhua; Liu, Zhiyuan, E-mail: liuzy@mail.xjtu.edu.cn; Geng, Yingsan; Wang, Zhenxing; Yan, Jing [State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an 710049 (China)

    2016-06-15

    The objective of this work is to reveal the effects of an axial magnetic field (AMF) on the vacuum arc characteristics between transverse magnetic field (TMF) contacts. These vacuum arc characteristics include the vacuum arcing behavior and the arc voltage waveform. In the experiments, an external AMF was applied to a pair of TMF contacts. The external AMF flux density B{sub AMF} can be adjusted from 0 to 110 mT. The arc current in the tests varied over a range from 0 to 20 kA rms at 45 Hz. The contact material was CuCr25 (25% Cr). A high-speed charge-coupled device video camera was used to record the vacuum arc evolution. The experimental results show that the application of the AMF effectively reduces the TMF arc voltage noise component and reduces the formation of liquid metal drops between the contacts. The diffuse arc duration increases linearly with increasing AMF flux density, but it also decreases linearly with increasing arc current under application of the external AMF. The results also indicate that the diffuse arc duration before the current zero is usually more than 1 ms under the condition that the value of the AMF per kiloampere is more than 2.0 mT/kA. Finally, under application of the AMF, the arc column of the TMF contacts may constrict and remain in the center region without transverse rotation. Therefore, the combined TMF–AMF contacts should be designed such that they guarantee that the AMF is not so strong as to oppose transverse rotation of the arc column.

  15. Vacuum arcing behavior between transverse magnetic field contacts subjected to variable axial magnetic field

    International Nuclear Information System (INIS)

    Ma, Hui; Wang, Jianhua; Liu, Zhiyuan; Geng, Yingsan; Wang, Zhenxing; Yan, Jing

    2016-01-01

    The objective of this work is to reveal the effects of an axial magnetic field (AMF) on the vacuum arc characteristics between transverse magnetic field (TMF) contacts. These vacuum arc characteristics include the vacuum arcing behavior and the arc voltage waveform. In the experiments, an external AMF was applied to a pair of TMF contacts. The external AMF flux density B AMF can be adjusted from 0 to 110 mT. The arc current in the tests varied over a range from 0 to 20 kA rms at 45 Hz. The contact material was CuCr25 (25% Cr). A high-speed charge-coupled device video camera was used to record the vacuum arc evolution. The experimental results show that the application of the AMF effectively reduces the TMF arc voltage noise component and reduces the formation of liquid metal drops between the contacts. The diffuse arc duration increases linearly with increasing AMF flux density, but it also decreases linearly with increasing arc current under application of the external AMF. The results also indicate that the diffuse arc duration before the current zero is usually more than 1 ms under the condition that the value of the AMF per kiloampere is more than 2.0 mT/kA. Finally, under application of the AMF, the arc column of the TMF contacts may constrict and remain in the center region without transverse rotation. Therefore, the combined TMF–AMF contacts should be designed such that they guarantee that the AMF is not so strong as to oppose transverse rotation of the arc column.

  16. Vacuum arcing behavior between transverse magnetic field contacts subjected to variable axial magnetic field

    Science.gov (United States)

    Ma, Hui; Wang, Jianhua; Liu, Zhiyuan; Geng, Yingsan; Wang, Zhenxing; Yan, Jing

    2016-06-01

    The objective of this work is to reveal the effects of an axial magnetic field (AMF) on the vacuum arc characteristics between transverse magnetic field (TMF) contacts. These vacuum arc characteristics include the vacuum arcing behavior and the arc voltage waveform. In the experiments, an external AMF was applied to a pair of TMF contacts. The external AMF flux density BAMF can be adjusted from 0 to 110 mT. The arc current in the tests varied over a range from 0 to 20 kA rms at 45 Hz. The contact material was CuCr25 (25% Cr). A high-speed charge-coupled device video camera was used to record the vacuum arc evolution. The experimental results show that the application of the AMF effectively reduces the TMF arc voltage noise component and reduces the formation of liquid metal drops between the contacts. The diffuse arc duration increases linearly with increasing AMF flux density, but it also decreases linearly with increasing arc current under application of the external AMF. The results also indicate that the diffuse arc duration before the current zero is usually more than 1 ms under the condition that the value of the AMF per kiloampere is more than 2.0 mT/kA. Finally, under application of the AMF, the arc column of the TMF contacts may constrict and remain in the center region without transverse rotation. Therefore, the combined TMF-AMF contacts should be designed such that they guarantee that the AMF is not so strong as to oppose transverse rotation of the arc column.

  17. Underwater plasma arc cutting

    International Nuclear Information System (INIS)

    Leautier, R.; Pilot, G.

    1991-01-01

    This report describes the work done to develop underwater plasma arc cutting techniques, to characterise aerosols from cutting operations on radioactive and non-radioactive work-pieces, and to develop suitable ventilation and filtration techniques. The work has been carried out in the framework of a contract between CEA-CEN Cadarache and the Commission of European Communities. Furthermore, this work has been carried out in close cooperation with CEA-CEN Saclay mainly for secondary emissions and radioactive analysis. The contract started in May 1986 and was completed in December 1988 by a supplementary agreement. This report has been compiled from several progress reports submitted during the work period, contains the main findings of the work and encloses the results of comparative tests on plasma arc cutting

  18. Arc cathode spots

    International Nuclear Information System (INIS)

    Schrade, H.O.

    1989-01-01

    Arc spots are usually highly unstable and jump statistically over the cathode surface. In a magnetic field parallel to the surface, preferably they move in the retrograde direction; i.e., opposite to the Lorentzian rule. If the field is inclined with respect to the surface, the spots drift away at a certain angle with respect to the proper retrograde direction (Robson drift motion). These well-known phenomena are explained by one stability theory

  19. Aperture modulated arc therapy

    International Nuclear Information System (INIS)

    Crooks, S M; Wu, Xiaodong; Takita, C; Watzich, M; Xing Lei

    2003-01-01

    We show that it is possible to translate an intensity modulated radiation therapy (IMRT) treatment plan and deliver it as a single arc. This technique is referred to in this paper as aperture modulation arc therapy (AMAT). During this arc, the MLC leaves do not conform to the projection of the target PTV and the machine output of the accelerator has a constant value. Dose was calculated using the CORVUS 4.0 IMRT system, which uses a pencil beam dose algorithm, and treatments were delivered using a Varian 2100C/D Clinac. Results are presented for a head and neck and a prostate case, showing the equivalence of the IMRT and the translated AMAT delivery. For a prostate AMAT delivery, coronal plane film dose for the IMRT and AMAT deliveries agreed within 7.19 ± 6.62%. For a meningioma the coronal plane dose distributions were similar to a value of 4.6 ± 6.62%. Dose to the isocentre was measured as being within 2% of the planned value in both cases

  20. Circular arc structures

    KAUST Repository

    Bo, Pengbo

    2011-07-01

    The most important guiding principle in computational methods for freeform architecture is the balance between cost efficiency on the one hand, and adherence to the design intent on the other. Key issues are the simplicity of supporting and connecting elements as well as repetition of costly parts. This paper proposes so-called circular arc structures as a means to faithfully realize freeform designs without giving up smooth appearance. In contrast to non-smooth meshes with straight edges where geometric complexity is concentrated in the nodes, we stay with smooth surfaces and rather distribute complexity in a uniform way by allowing edges in the shape of circular arcs. We are able to achieve the simplest possible shape of nodes without interfering with known panel optimization algorithms. We study remarkable special cases of circular arc structures which possess simple supporting elements or repetitive edges, we present the first global approximation method for principal patches, and we show an extension to volumetric structures for truly threedimensional designs. © 2011 ACM.

  1. CO2 flux from Javanese mud volcanism.

    Science.gov (United States)

    Queißer, M; Burton, M R; Arzilli, F; Chiarugi, A; Marliyani, G I; Anggara, F; Harijoko, A

    2017-06-01

    Studying the quantity and origin of CO 2 emitted by back-arc mud volcanoes is critical to correctly model fluid-dynamical, thermodynamical, and geochemical processes that drive their activity and to constrain their role in the global geochemical carbon cycle. We measured CO 2 fluxes of the Bledug Kuwu mud volcano on the Kendeng Fold and thrust belt in the back arc of Central Java, Indonesia, using scanning remote sensing absorption spectroscopy. The data show that the expelled gas is rich in CO 2 with a volume fraction of at least 16 vol %. A lower limit CO 2 flux of 1.4 kg s -1 (117 t d -1 ) was determined, in line with the CO 2 flux from the Javanese mud volcano LUSI. Extrapolating these results to mud volcanism from the whole of Java suggests an order of magnitude total CO 2 flux of 3 kt d -1 , comparable with the expected back-arc efflux of magmatic CO 2 . After discussing geochemical, geological, and geophysical evidence we conclude that the source of CO 2 observed at Bledug Kuwu is likely a mixture of thermogenic, biogenic, and magmatic CO 2 , with faulting controlling potential pathways for magmatic fluids. This study further demonstrates the merit of man-portable active remote sensing instruments for probing natural gas releases, enabling bottom-up quantification of CO 2 fluxes.

  2. Drinking water treatment using a submerged internal-circulation membrane coagulation reactor coupled with permanganate oxidation.

    Science.gov (United States)

    Zhang, Zhongguo; Liu, Dan; Qian, Yu; Wu, Yue; He, Peiran; Liang, Shuang; Fu, Xiaozheng; Li, Jiding; Ye, Changqing

    2017-06-01

    A submerged internal circulating membrane coagulation reactor (MCR) was used to treat surface water to produce drinking water. Polyaluminum chloride (PACl) was used as coagulant, and a hydrophilic polyvinylidene fluoride (PVDF) submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure (TMP), zeta potential (ZP) of the suspended particles in raw water, and KMnO 4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China (GB 5749-2006), as evaluated by turbidity (<1 NTU) and total organic carbon (TOC) (<5mg/L) measurements. Besides water flux, the removal of turbidity, TOC and dissolved organic carbon (DOC) in the raw water also increased with increasing TMP in the range of 0.01-0.05MPa. High ZP induced by PACl, such as 5-9mV, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity. However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1-2mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO 4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes. Copyright © 2016. Published by Elsevier B.V.

  3. Methane oxidation associated to submerged brown-mosses buffers methane emissions from Siberian polygonal peatlands

    Science.gov (United States)

    Liebner, Susanne; Zeyer, Josef; Knoblauch, Christian

    2010-05-01

    Circumpolar peatlands store roughly 18 % of the globally stored carbon in soils [based on 1, 2]. Also, northern wetlands and tundra are a net source of methane (CH4), an effective greenhouse gas (GHG), with an estimated annual CH4 release of 7.2% [3] or 8.1% [4] of the global total CH4 emission. Although it is definite that Arctic tundra significantly contributes to the global methane emissions in general, regional variations in GHG fluxes are enormous. CH4 fluxes of polygonal tundra within the Siberian Lena Delta, for example, were reported to be low [5, 6], particularly at open water polygonal ponds and small lakes [7] which make up around 10 % of the delta's surface. Low methane emissions from polygonal ponds oppose that Arctic permafrost thaw ponds are generally known to emit large amounts of CH4 [8]. Combining tools of biogeochemistry and molecular microbiology, we identified sinks of CH4 in polygonal ponds from the Lena Delta that were not considered so far in GHG studies from Arctic wetlands. Pore water CH4 profiling in polygonal ponds on Samoylov, a small island in the central part of the Lena Delta, revealed a pronounced zone of CH4 oxidation near the vegetation surface in submerged layers of brown-mosses. Here, potential CH4 oxidation was an order of magnitude higher than in non-submerged mosses and in adjacent bulk soil. We could additionally show that this moss associated methane oxidation (MAMO) is hampered when exposure of light is prevented. Shading of plots with submerged Scorpidium scorpioides inhibited MAMO leading to higher CH4 concentrations and an increase in CH4 fluxes by a factor of ~13. Compared to non-submerged mosses, the submerged mosses also showed significantly lower δ13C values indicating that they use carbon dioxide derived from methane oxidation for photosynthesis. Applying stable isotope probing of DNA, type II methanotrophs were identified to be responsible for the oxidation of CH4 in the submerged Scorpidium scorpioides. Our

  4. Long-term allelopathic control of phytoplankton by the submerged macrophyte Elodea nuttallii

    NARCIS (Netherlands)

    Vanderstukken, M.; Declerck, S.A.J.; Decaestecker, E.; Muylaert, K.

    2014-01-01

    Keywords: allelochemicals; chemical ecology; competition; nutrient limitation; shallow lakes Summary 1.It is well known that submerged macrophytes can suppress phytoplankton blooms in lakes and thus promote water quality and biodiversity. One of the possible mechanisms through which submerged

  5. Through-flow of water in leaves of a submerged plant is influenced by the apical opening

    DEFF Research Database (Denmark)

    Pedersen, Ole; Jørgensen, Lise Bolt; Sand-Jensen, Kaj

    1997-01-01

    Submerged plant, apical opening, hydathode, Sparganium, hydraulic architecture, leaf specific conductivity......Submerged plant, apical opening, hydathode, Sparganium, hydraulic architecture, leaf specific conductivity...

  6. Rocket measurements within a polar cap arc: Plasma, particle, and electric circuit parameters

    International Nuclear Information System (INIS)

    Weber, E.J.; Ballenthin, J.O.; Basu, S.; Carlson, H.C.; Hardy, D.A.; Maynard, N.C.; Smiddy, M.; Kelley, M.C.; Fleischman, J.R.; Sheehan, R.E.; Pfaff, R.F.; Rodriguez, P.

    1989-01-01

    An instrumented rocket payload was launched into a polar cap F layer aurora to investigate the energetic particle, plasma, and electric circuit parameters of a Sun-aligned arc. On-board instruments measured energetic electron flux, ion composition and density fluctuations, electron density and temperature, electron density fluctuations, and ac and dc electric fields. Real-time all-sky imaging photometer measurements of the location and motion of the aurora, were used to determine the proper geophysical situation for launch. Comparison of the in situ measurements with remote optical measurements shows that the arc was produced by fluxes of low-energy (< 1 keV) electrons. Field-aligned potentials in the arc inferred from the electron spectra had a maximum value of approximately 300 V, and from the spectral shape a parent population of preaccelerated electrons characteristic of the boundary plasma sheet or magnetosheath was inferred. Electric field components along and across the arc show sunward flow within the arc and duskward drift of the arc consistent with the drift direction and speed determined from optical imaging. Thus this arc is drifting duskward under the influence of the convection electric field. Three possible explanations for this (field-aligned currents, chemistry, and transport) are considered. Finally, ionospheric irregularity and electric field fluctuations indicate two different generation mechanisms on the dawnside and duskside of the arc. On the duskside, parameters are suggestive of an interchange process, while on the dawnside, fluctuation parameters are consistent with a velocity shear instability

  7. Hybrid laser-arc welding

    DEFF Research Database (Denmark)

    Hybrid laser-arc welding (HLAW) is a combination of laser welding with arc welding that overcomes many of the shortfalls of both processes. This important book gives a comprehensive account of hybrid laser-arc welding technology and applications. The first part of the book reviews...... the characteristics of the process, including the properties of joints produced by hybrid laser-arc welding and ways of assessing weld quality. Part II discusses applications of the process to such metals as magnesium alloys, aluminium and steel as well as the use of hybrid laser-arc welding in such sectors as ship...... building and the automotive industry. With its distinguished editor and international team of contributors, Hybrid laser-arc welding, will be a valuable source of reference for all those using this important welding technology. Professor Flemming Ove Olsen works in the Department of Manufacturing...

  8. Leaf gas films contribute to rice (Oryza sativa) submergence tolerance during saline floods

    DEFF Research Database (Denmark)

    Herzog, Max; Konnerup, Dennis; Pedersen, Ole

    2018-01-01

    Floods and salinization of agricultural land adversely impact global rice production. We investigated whether gas films on leaves of submerged rice delay salt entry during saline submergence. Two-week-old plants with leaf gas films (+GF) or with gas films experimentally removed (-GF) were submerged...

  9. Modelling vacuum arcs : from plasma initiation to surface interactions

    International Nuclear Information System (INIS)

    Timko, H.

    2011-01-01

    A better understanding of vacuum arcs is desirable in many of today's 'big science' projects including linear colliders, fusion devices, and satellite systems. For the Compact Linear Collider (CLIC) design, radio-frequency (RF) breakdowns occurring in accelerating cavities influence efficiency optimisation and cost reduction issues. Studying vacuum arcs both theoretically as well as experimentally under well-defined and reproducible direct-current (DC) conditions is the first step towards exploring RF breakdowns. In this thesis, we have studied Cu DC vacuum arcs with a combination of experiments, a particle-in-cell (PIC) model of the arc plasma, and molecular dynamics (MD) simulations of the subsequent surface damaging mechanism. We have also developed the 2D Arc-PIC code and the physics model incorporated in it, especially for the purpose of modelling the plasma initiation in vacuum arcs. Assuming the presence of a field emitter at the cathode initially, we have identified the conditions for plasma formation and have studied the transitions from field emission stage to a fully developed arc. The 'footing' of the plasma is the cathode spot that supplies the arc continuously with particles; the high-density core of the plasma is located above this cathode spot. Our results have shown that once an arc plasma is initiated, and as long as energy is available, the arc is self-maintaining due to the plasma sheath that ensures enhanced field emission and sputtering.The plasma model can already give an estimate on how the time-to-breakdown changes with the neutral evaporation rate, which is yet to be determined by atomistic simulations. Due to the non-linearity of the problem, we have also performed a code-to-code comparison. The reproducibility of plasma behaviour and time-to-breakdown with independent codes increased confidence in the results presented here. Our MD simulations identified high-flux, high-energy ion bombardment as a possible mechanism forming the early

  10. Correlation methods in cutting arcs

    Energy Technology Data Exchange (ETDEWEB)

    Prevosto, L; Kelly, H, E-mail: prevosto@waycom.com.ar [Grupo de Descargas Electricas, Departamento Ing. Electromecanica, Universidad Tecnologica Nacional, Regional Venado Tuerto, Laprida 651, Venado Tuerto (2600), Santa Fe (Argentina)

    2011-05-01

    The present work applies similarity theory to the plasma emanating from transferred arc, gas-vortex stabilized plasma cutting torches, to analyze the existing correlation between the arc temperature and the physical parameters of such torches. It has been found that the enthalpy number significantly influence the temperature of the electric arc. The obtained correlation shows an average deviation of 3% from the temperature data points. Such correlation can be used, for instance, to predict changes in the peak value of the arc temperature at the nozzle exit of a geometrically similar cutting torch due to changes in its operation parameters.

  11. Correlation methods in cutting arcs

    International Nuclear Information System (INIS)

    Prevosto, L; Kelly, H

    2011-01-01

    The present work applies similarity theory to the plasma emanating from transferred arc, gas-vortex stabilized plasma cutting torches, to analyze the existing correlation between the arc temperature and the physical parameters of such torches. It has been found that the enthalpy number significantly influence the temperature of the electric arc. The obtained correlation shows an average deviation of 3% from the temperature data points. Such correlation can be used, for instance, to predict changes in the peak value of the arc temperature at the nozzle exit of a geometrically similar cutting torch due to changes in its operation parameters.

  12. Gas tungsten arc welder

    International Nuclear Information System (INIS)

    Christiansen, D.W.; Brown, W.F.

    1984-01-01

    A welder for automated closure of fuel pins by a gas tungsten arc process in which a rotating length of cladding is positioned adjacent a welding electrode in a sealed enclosure. An independently movable grinder, co-axial with the electrode, is provided in the enclosure for refurbishing the used electrode between welds. The specification also discloses means for loading of the cladding with fuel pellets and for placement of reflectors, gas capsules and end caps. Gravity feed conveyor and inerting means are also described. (author)

  13. Microcystin production in epiphytic cyanobacteria on submerged macrophytes.

    Science.gov (United States)

    Mohamed, Zakaria A; Al Shehri, Abdulrahman M

    2010-06-15

    Cyanotoxins have been largely studied in planktonic and benthic cyanobacteria, but microcystin (MCYST) production in epiphytic cyanobacteria has not been reported yet. The present study reports for the first time the MCYST production in epiphytic cyanobacteria on submerged macrophytes. During this study, four common submerged macrophytes in eutrophic pond in Saudi Arabia were surveyed for the presence of toxic epiphytic cyanobacteria. The results showed that chlorophyll-a and total biovolume of epiphytic cyanobacteria differed significantly among submerged plants with highest values obtained in Stratiotes aloides and lowest in Elodea canadensis. Epiphytic materials collected from Ceratophyllum demersum and S. aloides had higher species diversities than materials collected from E. canadensis and Myriophyllum verticillatum. The cyanobacteria, Merismopedia tenuissima and Leptolyngbya boryana were recorded with a high abundance in epiphytic materials collected from all submerged macrohpytes. Based on Enzyme-linked immunosorbent assay (ELISA), these two species were found to produce MCYSTs (MCYSTs) with concentrations of 1438 and 630 microg g(-1) dry weight, respectively. HPLC analysis of the methanolic extracts of the two species showed that M. tenuissima extract contained MCYST-RR and -LR/demethyl LR plus 3 minor unidentified MCYSTs, while L. boryana extract contained MCYST-YR, -LR/demethyl LR, and 2 minor unidentified MCYSTs. This study suggests that epiphytic species should be considered during monitoring of toxic cyanobacteria in water sources. 2010 Elsevier Ltd. All rights reserved.

  14. Gas exchange under water. Acclimation of terrestrial plants to submergence

    NARCIS (Netherlands)

    Mommer, L.

    2005-01-01

    Gas exchange between the plant and the environment is severely hampered when plants are submerged, leading to oxygen and energy deficits. A straightforward way to reduce these shortages of oxygen and carbohydrates would be prolonged photosynthesis under water, but this has received only little

  15. Tidal Power Potential in the Submerged Channels of Dar es

    African Journals Online (AJOL)

    on the tidal plateau, shallow water area on the sand banks and in the submerged channels, using self—recording .... in a Cartesian frame where iz is directed towards the vertical, ix points ..... Bongoyo, there is a 15 m deep channel that passes.

  16. Benthic Bacterial Diversity in Submerged Sinkhole Ecosystems▿ †

    Science.gov (United States)

    Nold, Stephen C.; Pangborn, Joseph B.; Zajack, Heidi A.; Kendall, Scott T.; Rediske, Richard R.; Biddanda, Bopaiah A.

    2010-01-01

    Physicochemical characterization, automated ribosomal intergenic spacer analysis (ARISA) community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale, while deeper, organically rich sediments contained diverse and active bacterial communities. PMID:19880643

  17. Effects of submerged and anaerobic fermentations on cassava flour ...

    African Journals Online (AJOL)

    Cassava tubers for processing into cassava flour, Lafun a Nigerian locally fermented product was subjected to two different types of fermentations: submerged and anaerobic fermentation for 72 h. Physicochemical changes that occurred during fermentation and their influence on the functional, rheological and sensory ...

  18. Surface Intermediate Zone of Submerged Turbulent Buoyant Jet in Current

    DEFF Research Database (Denmark)

    Chen, H. B.; Larsen, Torben

    1995-01-01

    This paper deals with the intermediate zone between the jet and plume stages of a submerged buoyant discharge from sea outfall in current. The stability criteria, plume width and height after the intermediate zone and the dilution within the intermediate region have been studied theoretically and...

  19. Identification of a novel submergence response gene regulated by ...

    African Journals Online (AJOL)

    Tuoyo Aghomotsegin

    2016-12-07

    Dec 7, 2016 ... ... stress. Hormone ABA treatment induces, whereas GA treatment decreases, RS1 ... Key word: Rice (Oryza sativa L.), submergence, RNA-seq, Sub1A, abiotic stress. ... genes may interact with Sub1A-1 that are necessary for.

  20. Effects of submerged vegetation on water clarity across climates

    NARCIS (Netherlands)

    Kosten, S.; Lacerot, G.; Jeppesen, E.; Motta Marques, D.M.L.; Nes, van E.H.; Mazzeo, N.; Scheffer, M.

    2009-01-01

    A positive feedback between submerged vegetation and water clarity forms the backbone of the alternative state theory in shallow lakes. The water clearing effect of aquatic vegetation may be caused by different physical, chemical, and biological mechanisms and has been studied mainly in temperate

  1. Geological constraints on continental arc activity since 720 Ma: implications for the link between long-term climate variability and episodicity of continental arcs

    Science.gov (United States)

    Cao, W.; Lee, C. T.

    2016-12-01

    events. This coherence provides further evidence that continental arcs may play an important role in controlling long-term climate evolution. CO2 degassing fluxes from continental arcs should be incorporated into global, long-term climate models. Our work provides a quantitative framework for estimating these fluxes.

  2. Study of electric arc welding of castings for nuclear power machine-building

    International Nuclear Information System (INIS)

    Rymkevich, A.I.; Korsunov, P.M.

    1977-01-01

    Mechanical and corrosion-resistance properties are studied of the welded joints of cast billets from steel 00Kh12N3DL by automatic submerged arc welding. It is shown by testing the joints made with preheating up to 100 deg C and subsequent tempering (620 deg C for 25 h + 640 deg C for 16 h) that in the temperature range of 20-350 deg C they possess fairly good strength, ductility, impact viscosity, and corrosion-resistance properties approximating the corresponding characteristics of the base metal. The welding technology developed can be used to make pump casings for atomic power equipment

  3. Electric arc welding gun

    Science.gov (United States)

    Luttrell, Edward; Turner, Paul W.

    1978-01-01

    This invention relates to improved apparatus for arc welding an interior joint formed by intersecting tubular members. As an example, the invention is well suited for applications where many similar small-diameter vertical lines are to be welded to a long horizontal header. The improved apparatus includes an arc welding gun having a specially designed welding head which is not only very compact but also produces welds that are essentially free from rolled-over solidified metal. The welding head consists of the upper end of the barrel and a reversely extending electrode holder, or tip, which defines an acute angle with the barrel. As used in the above-mentioned example, the gun is positioned to extend upwardly through the vertical member and the joint to be welded, with its welding head disposed within the horizontal header. Depending on the design of the welding head, the barrel then is either rotated or revolved about the axis of the vertical member to cause the electrode to track the joint.

  4. Rice SUB1A constrains remodeling of the transcriptome and metabolome during submergence and post-submergence recovery”.

    Science.gov (United States)

    The rice (Oryza sativa L.) ethylene-responsive transcription factor SUB1A confers tolerance to prolonged, complete submergence by limiting underwater elongation growth. Rice encoding SUB1A-1 also recovers photosynthetic function and re-commences development towards flowering more rapidly after desu...

  5. The Origin of Silicic Arc Crust - Insights from the Northern Pacific Volcanic Arcs through Space and Time

    Science.gov (United States)

    Straub, S. M.; Kelemen, P. B.

    2016-12-01

    The remarkable compositional similarities of andesitic crust at modern convergent margins and the continental crust has long evoked the hypothesis of similar origins. Key to understanding either genesis is understanding the mode of silica enrichment. Silicic crust cannot be directly extracted from the upper mantle. Hence, in modern arcs, numerous studies - observant of the pervasive and irrefutable evidence of melt mixing - proposed that arc andesites formed by mixing of mantle-derived basaltic melts and fusible silicic material from the overlying crust. Mass balance requires the amount of silicic crust in such hybrid andesites to be on the order to tens of percent, implying that their composition to be perceptibly influenced by the various crustal basements. In order to test this hypothesis, major and trace element compositions of mafic and silicic arc magmas with arc-typical low Ce/PbMexico) were combined with Pb isotope ratios. Pb isotope ratios are considered highly sensitive to crustal contamination, and hence should reflect the variable composition of the oceanic and continental basement on which these arcs are constructed. In particular, in thick-crust continental arcs where the basement is isotopically different from the mantle and crustal assimilation thought to be most prevalent, silicic magmas must be expected to be distinct from those of the associated mafic melts. However, in a given arc, the Pb isotope ratios are constant with increasing melt silica regardless of the nature of the basement. This observation argues against a melt origin of silicic melts from the crustal basement and suggest them to be controlled by the same slab flux as their co-eval mafic counterparts. This inference is validated by the spatial and temporal pattern of arc Pb isotope ratios along the Northern Pacific margins and throughout the 50 million years of Cenozoic evolution of the Izu Bonin Mariana arc/trench system that are can be related to with systematic, `real

  6. Characterizing the thermal effects of High Energy Arc Faults

    Energy Technology Data Exchange (ETDEWEB)

    Putorti, Anthony; Bareham, Scott; Praydis, Joseph Jr. [National Institute of Standards and Technology (NIST), Gaithersburg, MD (United States); Melly, Nicholas B. [U.S. Nuclear Regulatory Commission (NRC), Washington, DC (United States)

    2015-12-15

    International and domestic operating experience involving High Energy Arc Faults (HEAF) in Nuclear Power Plant (NPP) electrical power systems have demonstrated the potential to cause extensive damage to electrical components and distribution systems along with damage to adjacent equipment and cables. An international study by the Committee on the Safety of Nuclear Installations (CSNI) gOECD Fire Project. Topical Report No. 1: Analysis of High Energy Arcing Fault (HEAF) Fire Events h published June 25, 2013 [1], illustrates that HEAF events have the potential to be major risk contributors with significant safety consequences and substantial economic loss. In an effort to better understand and characterize the threats posed by HEAF related phenomena, an international project has been chartered; the Joint Analysis of Arc Faults (Joan of ARC) OECD International Testing Program for High Energy Arc Faults. One of the major challenges of this research is how to properly measure and characterize the risk and influence of these events. Methods are being developed to characterize relevant parameters such as; temperature, heat flux, and heat release rate of fires resulting from HEAF events. Full scale experiments are being performed at low (≤ 1000 V) and medium (≤ 35 kV) voltages in electrical components. This paper introduces the methods being developed to measure thermal effects and discusses preliminary results of full scale HEAF experiments.

  7. Arc-weld pool interactions

    International Nuclear Information System (INIS)

    Glickstein, S.S.

    1978-08-01

    The mechanisms involved in arc-weld pool interactions are extremely complex and no complete theory is presently available to describe much of the phenomena observed during welding. For the past several years, experimental and analytical studies have been undertaken at the Bettis Atomic Power Laboratory to increase basic understanding of the gas tungsten arc welding process. These studies have included experimental spectral analysis of the arc in order to determine arc temperature and analytical modeling of the arc and weld puddle. The investigations have been directed toward determining the cause and effects of variations in the energy distribution incident upon the weldment. In addition, the effect of weld puddle distortion on weld penetration was investigated, and experimental and analytical studies of weld process variables have been undertaken to determine the effects of the variables upon weld penetration and configuration. A review of the results and analysis of these studies are presented

  8. Numerical and experimental study of heat transfers in an arc plasma. Application to TIG arc welding

    International Nuclear Information System (INIS)

    Borel, Damien

    2013-01-01

    The arc welding is used for many industrial applications, especially GTA welding. Given the excellent quality of the produced welds, GTA welding is used for the majority of the interventions (repairs, joined sealing) on the French nuclear park. This work is part of a project carried out by EDF R and D which aims to simulate the whole process and builds a tool able to predict the welds quality. In this study, we focus on the development of a predictive model of the exchanged heat flux at the arc - work piece interface, responsible of the work piece fusion. The modeling of the arc plasma using the electric module of the hydrodynamics software Code Saturne R developed by EDF R and D is required. Two types of experimental tests are jointly carried out to validate this numerical model: i) on density and temperature measurements of plasma by atomic emission spectroscopy and ii) on the evaluation of the heat transfers on the work piece surface. This work also aims at demonstrate that the usual method of using an equivalent thermal source to model the welding process, can be replaced by our plasma model, without the numerous trials inherent to the usual method. (author)

  9. Applying the seedling-emergence method under waterlogged conditions to detect the seed bank of aquatic plants in submerged sediments

    NARCIS (Netherlands)

    Boedeltje, G; ter Heerdt, GNJ; Bakker, JP

    Seed bank studies focused on submerged aquatic plants are generally performed under submerged conditions, using the seedling-emergence method. However, if a study targets at both submerged species and helophytes, submerged conditions are generally not suitable. We tested the emergence of seedlings

  10. Net uptake of atmospheric CO2 by coastal submerged aquatic vegetation

    Science.gov (United States)

    Tokoro, Tatsuki; Hosokawa, Shinya; Miyoshi, Eiichi; Tada, Kazufumi; Watanabe, Kenta; Montani, Shigeru; Kayanne, Hajime; Kuwae, Tomohiro

    2014-01-01

    ‘Blue Carbon’, which is carbon captured by marine living organisms, has recently been highlighted as a new option for climate change mitigation initiatives. In particular, coastal ecosystems have been recognized as significant carbon stocks because of their high burial rates and long-term sequestration of carbon. However, the direct contribution of Blue Carbon to the uptake of atmospheric CO2 through air-sea gas exchange remains unclear. We performed in situ measurements of carbon flows, including air-sea CO2 fluxes, dissolved inorganic carbon changes, net ecosystem production, and carbon burial rates in the boreal (Furen), temperate (Kurihama), and subtropical (Fukido) seagrass meadows of Japan from 2010 to 2013. In particular, the air-sea CO2 flux was measured using three methods: the bulk formula method, the floating chamber method, and the eddy covariance method. Our empirical results show that submerged autotrophic vegetation in shallow coastal waters can be functionally a sink for atmospheric CO2. This finding is contrary to the conventional perception that most near-shore ecosystems are sources of atmospheric CO2. The key factor determining whether or not coastal ecosystems directly decrease the concentration of atmospheric CO2 may be net ecosystem production. This study thus identifies a new ecosystem function of coastal vegetated systems; they are direct sinks of atmospheric CO2. PMID:24623530

  11. Arc fault detection system

    Science.gov (United States)

    Jha, K.N.

    1999-05-18

    An arc fault detection system for use on ungrounded or high-resistance-grounded power distribution systems is provided which can be retrofitted outside electrical switchboard circuits having limited space constraints. The system includes a differential current relay that senses a current differential between current flowing from secondary windings located in a current transformer coupled to a power supply side of a switchboard, and a total current induced in secondary windings coupled to a load side of the switchboard. When such a current differential is experienced, a current travels through a operating coil of the differential current relay, which in turn opens an upstream circuit breaker located between the switchboard and a power supply to remove the supply of power to the switchboard. 1 fig.

  12. Arc fault detection system

    Science.gov (United States)

    Jha, Kamal N.

    1999-01-01

    An arc fault detection system for use on ungrounded or high-resistance-grounded power distribution systems is provided which can be retrofitted outside electrical switchboard circuits having limited space constraints. The system includes a differential current relay that senses a current differential between current flowing from secondary windings located in a current transformer coupled to a power supply side of a switchboard, and a total current induced in secondary windings coupled to a load side of the switchboard. When such a current differential is experienced, a current travels through a operating coil of the differential current relay, which in turn opens an upstream circuit breaker located between the switchboard and a power supply to remove the supply of power to the switchboard.

  13. The ARCS radial collimator

    International Nuclear Information System (INIS)

    Stone, M.B.; Abernathy, D.L.; Niedziela, J.L.; Overbay, M.A.

    2015-01-01

    We have designed, installed, and commissioned a scattered beam radial collimator for use at the ARCS Wide Angular Range Chopper Spectrometer at the Spallation Neutron Source. The collimator has been designed to work effectively for thermal and epithermal neutrons and with a range of sample environments. Other design considerations include the accommodation of working within a high vacuum environment and having the ability to quickly install and remove the collimator from the scattered beam. The collimator is composed of collimating blades (or septa). The septa are 12 micron thick Kapton foils coated on each side with 39 microns of enriched boron carbide ( 10 B 4 C with 10 B > 96%) in an ultra-high vacuum compatible binder. The collimator blades represent an additional 22 m 2 of surface area. In the article we present collimator's design and performance and methodologies for its effective use

  14. Influence of nanoparticles on filterability of fruit-juice industry wastewater using submerged membrane bioreactor.

    Science.gov (United States)

    Demirkol, Guler Turkoglu; Dizge, Nadir; Acar, Turkan Ormanci; Salmanli, Oyku Mutlu; Tufekci, Nese

    2017-07-01

    In this study, polyethersulfone (PES) ultrafiltration membrane surface was modified with nano-sized zinc oxide (nZnO) and silver (nAg) to improve the membrane filterability of the mixed liquor and used to treat fruit-juice industry wastewater in a submerged membrane bioreactor (MBR). The nAg was synthesized using three different methods. In the first method, named as nAg-M1, PES membrane was placed on the membrane module and nAg solution was passed through the membrane for 24 h at 25 ± 1 °C. In the second method, named as nAg-M2, PES membrane was placed in a glass container and it was shaken for 24 h at 150 rpm at 25 ± 1 °C. In the third method, named as nAg-M3, Ag nanoparticles were loaded onto PES membrane in L-ascorbic acid solution (0.1 mol/L) at pH 2 for 24 h at 150 rpm at 25 ± 1 °C. For the preparation of nZnO coated membrane, nZnO nanoparticles solution was passed through the membrane for 24 h at 25 ± 1 °C. Anti-fouling performance of pristine and coated membranes was examined using the submerged MBR. The results showed that nZnO and nAg-M3 membranes showed lower flux decline compared with pristine membrane. Moreover, pristine and coated PES membranes were characterized using a permeation test, contact angle goniometer, and scanning electron microscopy.

  15. Plasma's sweeping arc

    International Nuclear Information System (INIS)

    Pichon, Max

    2010-01-01

    Full text: It is purely elemental, returning materials to their basic atoms through extreme heat and then recondensing them in useful ways. Plasma arc gasification is the latest advanced waste treatment (AWT)concept to hit our shores, courtesy of Zenergy Australia. According to its fans, plasma technology can eliminate all domestic waste to landfill and turn it into beneficial by-products. Japan has toyed with it for a decade, but the idea is now creating a bit of buzz, in the US in particular. Consultancy URS last year undertook a review of 16 advanced technologies for the City of Los Angeles and determined plasma arc gasification was one of the most promising. The Waste Management Association of Australia (VVMAA), however, is cautious - too many AWT projects here have failed to live up to their promises. Plasma arc gasification works on the same principle as a welding machine. An inert gas is passed through an electrical arc between two electrodes and becomes ionised (called plasma), reaching temperatures as high as 13,900°C. It is then injected into the plasma converter holding the waste. Zenergy is working with US technology company Plasma Waste Recycling (PWR), which says it can convert 80 per cent of waste to syngas, a mixture of carbon monoxide and hydrogen that can be used to generate renewable electricity. The inorganic compounds in the waste come out as a solid, either molten metal to be cast as scrap steel or a slag that can be used as a building material aggregate or spun into mineral wool. “The plasma arc process is the next generation for AWT plants as there is no incineration involved, no fly ash, no bottom ash and nothing left to landfill,” said Zenergy Australia's Paul Prasad. He estimates a plant could convert up to 175,000 tonnes of household waste a year into energy or reusable by-products. Technically, it also gets around Australia's fears over incineration, though whether that is really the case in practice remains to be seen. Prasad says

  16. Arc Interference Behavior during Twin Wire Gas Metal Arc Welding Process

    Directory of Open Access Journals (Sweden)

    Dingjian Ye

    2013-01-01

    Full Text Available In order to study arc interference behavior during twin wire gas metal arc welding process, the synchronous acquisition system has been established to acquire instantaneous information of arc profile including dynamic arc length variation as well as relative voltage and current signals. The results show that after trailing arc (T-arc is added to the middle arc (M-arc in a stable welding process, the current of M arc remains unchanged while the agitation increases; the voltage of M arc has an obvious increase; the shape of M arc changes, with increasing width, length, and area; the transfer frequency of M arc droplet increases and the droplet itself becomes smaller. The wire extension length of twin arc turns out to be shorter than that of single arc welding.

  17. Double Arc Instability in the Solar Corona

    Energy Technology Data Exchange (ETDEWEB)

    Ishiguro, N.; Kusano, K., E-mail: n-ishiguro@isee.nagoya-u.ac.jp [Institute for Space-Earth Environmental Research, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601 Japan (Japan)

    2017-07-10

    The stability of the magnetic field in the solar corona is important for understanding the causes of solar eruptions. Although various scenarios have been suggested to date, the tether-cutting reconnection scenario proposed by Moore et al. is one of the widely accepted models to explain the onset process of solar eruptions. Although the tether-cutting reconnection scenario proposes that the sigmoidal field formed by internal reconnection is the magnetic field in the pre-eruptive state, the stability of the sigmoidal field has not yet been investigated quantitatively. In this paper, in order to elucidate the stability problem of the pre-eruptive state, we developed a simple numerical analysis in which the sigmoidal field is modeled by a double arc electric current loop and its stability is analyzed. As a result, we found that the double arc loop is more easily destabilized than the axisymmetric torus, and it becomes unstable even if the external field does not decay with altitude, which is in contrast to the axisymmetric torus instability. This suggests that tether-cutting reconnection may well work as the onset mechanism of solar eruptions, and if so, the critical condition for eruption under a certain geometry may be determined by a new type of instability rather than by the torus instability. Based on them, we propose a new type of instability called double arc instability (DAI). We discuss the critical conditions for DAI and derive a new parameter κ , defined as the product of the magnetic twist and the normalized flux of the tether-cutting reconnection.

  18. [Antimicrobial activity of Laetiporus sulphureus strains grown in submerged culture].

    Science.gov (United States)

    Ershova, E Iu; Tikhonova, O V; Lur'e, L M; Efremenkova, O V; Kamzolkina, O V; Dudnik, Iu V

    2003-01-01

    Cultural conditions for growth and fruit body formation were elaborated to four strains of Laetiporus sulphureus isolated from nature. All strains demonstrated antimicrobial activity against a wide spectrum of gram-positive and gram-negative bacteria during agar and submerged cultivation including methicillin-resistant strain of Staphylococcus aureus (MRSA) and glycopeptide-resistant strain of Leuconostoc mesenteroides. Antifungal activity was not found. The level of antimicrobial activity during submerged cultivation reached maximum after seven days of growth on specific medium with soybean meal and corn liquid; the next four weeks its increasing was not so manifested. Antimicrobial activity correlated with orange pigment secretion and cultural liquid acidification to pH 2.0-2.8 that indicates on acid nature of synthesized products.

  19. Improvement of Xylanase Production by Cochliobolus sativus in Submerged Culture

    Directory of Open Access Journals (Sweden)

    Yasser Bakri

    2008-01-01

    Full Text Available The xylanase production by a new Cochliobolus sativus Cs5 strain was improved under submerged fermentation. The xylanase was induced by xylan and repressed by glucose, sucrose, maltose, xylose, starch and cellulose. Highest enzyme production (98.25 IU/mL was recorded when wheat straw (4 % by mass per volume was used as a carbon source after 120 h of incubation. NaNO3 increased xylanase production 5.4-fold as compared to the control. Optimum initial pH was found to be 4.5 to 5. The C. sativus Cs5 strain grown under submerged culture in a simple medium proved to be a promising microorganism for xylanase production.

  20. Mineralization of Surfactants by the Microbiota of Submerged Plant Detritus

    OpenAIRE

    Federle, Thomas W.; Ventullo, Roy M.

    1990-01-01

    In wetlands and canopied bodies of water, plant detritus is an important source of carbon and energy. Detrital materials possess a large surface area for sorption of dissolved organics and are colonized by a large and diverse microbiota. To examine the biodegradation of surfactants by these microorganisms, submerged oak leaves were obtained from a laundromat wastewater pond, its overflow, and a pristine control pond. Leaves were cut into disks and incubated in sterile water amended with 50 μg...

  1. Submerged beachrock preservation in the context of wave ravinement

    Science.gov (United States)

    Pretorius, Lauren; Green, Andrew N.; Andrew Cooper, J.

    2018-02-01

    This study examines a Holocene-aged submerged shoreline, Limestone Reef, located in the shallow subtidal zone of South Africa's east coast. It comprises an elongate, coast-oblique, slab-like outcrop of beachrock situated above the contemporary fair-weather wave base. It is currently undergoing mechanical disintegration. Its unique and rare preservation in a high-energy setting affords an opportunity to examine the mechanical processes occurring during wave ravinement associated with rising sea level. The submerged shoreline and the adjacent shoreface were examined using high-resolution seismic reflection, side-scan sonar and shallow-water multibeam echosounding techniques. Limestone Reef rests on top of unconsolidated Holocene deposits. The structure's surface is characterised by reef-perpendicular gullies with rubble derived from the slab fringing its seaward edge. Limestone Reef slopes gently seawards and has a steep landward-facing edge where gullies are most prominently developed. Teardrop-shaped rippled scour depressions, marked by high backscatter, are located seawards of the submerged shoreline. These elongate in a seaward direction and are filled with bioclastic gravels and residual rubble from Limestone Reef. The gullies in the upstanding structure are indicative of wave plucking and abrasion of the shoreline. The material exposed by the rippled scour depressions is identical to that comprising the postglacial ravinement surface identified in the offshore stratigraphy. These deposits are considered to represent the contemporary, actively forming wave ravinement surface. The results suggest that wave ravinement of submerged shorelines is a discontinuous process dominated by the seaward entrainment of material from its landward edge controlled by high-energy drawback during storm surges. The ravinement process appears to operate at the seasonal scale and averages out over the long-term millennial scale for the continuous surface.

  2. Measurement of Submerged Oil/Gas Leaks using ROV Video

    Science.gov (United States)

    Shaffer, Franklin; de Vera, Giorgio; Lee, Kenneth; Savas, Ömer

    2013-11-01

    Drilling for oil or gas in the Gulf of Mexico is increasing rapidly at depths up to three miles. The National Commission on the Deepwater Horizon Oil Leak concluded that inaccurate estimates of the leak rate from the Deepwater Horizon caused an inadequate response and attempts to cap the leak to fail. The first response to a submerged oil/gas leak will be to send a Remotely Operated Vehicle (ROV) down to view the leak. During the response to the Deepwater Horizon crisis, the authors Savas and Shaffer were members of the Flow Rate Technical Group's Plume Team who used ROV video to develop the FRTG's first official estimates of the oil leak rate. Savas and Shaffer developed an approach using the larger, faster jet features (e.g., turbulent eddies, vortices, entrained particles) in the near-field developing zone to measure discharge rates. The authors have since used the Berkeley Tow Tank to test this approach on submerged dye-colored water jets and compressed air jets. Image Correlation Velocimetry has been applied to measure the velocity of visible features. Results from tests in the Berkeley Tow Tank and submerged oil jets in the OHMSETT facility will be presented.

  3. The effect of submergence on structural response in confined pools

    International Nuclear Information System (INIS)

    Sturm, A.J. Jr.; Song, C.C.S.

    1980-01-01

    In this paper the response of single and multi degree of submerged systems is investigated. The complete equations of motions including fluid coupling terms are developed for submerged bodies where the surrounding fluid is both moving in phase and out of phase with the support motion. The analysis considers both structural and fluid damping. Also included is an analysis of two degrees of freedom fluid coupling for submerged bodies completely enclosed within another body. In this case limiting conditions of the inner body hydrodynamic mass are examined, along the frequency response characteristics of these systems. The paper developes a simplified forcing function approach for in phase fluid support motion systems. This method is applicable for both modal-spectral and time history dynamic analyses of any linear structure. The results of the analysis are expanded for s structures with non-linear support configuration, i.e. (sliding or rocking bases) to again define a simplified analytical approach accounting for in phase fluid support motion. (orig.)

  4. Production of Alpha Amylase by Bacillus cereus in Submerged Fermentation

    Directory of Open Access Journals (Sweden)

    Helen H. Raplong

    2014-09-01

    Full Text Available Microorganisms have the ability to secrete enzymes when they are grown in the presence of certain substrates. Amylases are among the most important industrial enzymes and are of great significance in biotechnological studies. Bacteria belonging to the genus Bacillus were isolated using mannitol egg yolk polymyxin B (MYP agar a highly selective media for Bacillus cereus isolation. The isolates were tested for α-amylase production on nutrient agar supplemented with starch and in submerged fermentation. The bacteria isolated and identified (using the Microgen Bacillus identification kit were all Bacillus cereus and SB2 had the largest zone of hydrolysis of 12mm on nutrient agar supplemented with starch as well as the highest enzyme activity of 1.62U/ml. Amylase activity of 2.56U/ml was obtained after 24 hours incubation in submerged fermentation. When amylase enzyme production parameters where optimized, maximum amylase activity was obtained at a pH of 6.5, temperature of 350C, incubation time of 24 hours and 4% inoculums concentration. Bacillus cereus SB2 is a potential isolate for alpha-amylase production with soluble starch as the sole carbon source in submerged fermentation.

  5. Vibration analysis of partially cracked plate submerged in fluid

    Science.gov (United States)

    Soni, Shashank; Jain, N. K.; Joshi, P. V.

    2018-01-01

    The present work proposes an analytical model for vibration analysis of partially cracked rectangular plates coupled with fluid medium. The governing equation of motion for the isotropic plate based on the classical plate theory is modified to accommodate a part through continuous line crack according to simplified line spring model. The influence of surrounding fluid medium is incorporated in the governing equation in the form of inertia effects based on velocity potential function and Bernoulli's equations. Both partially and totally submerged plate configurations are considered. The governing equation also considers the in-plane stretching due to lateral deflection in the form of in-plane forces which introduces geometric non-linearity into the system. The fundamental frequencies are evaluated by expressing the lateral deflection in terms of modal functions. The assessment of the present results is carried out for intact submerged plate as to the best of the author's knowledge the literature lacks in analytical results for submerged cracked plates. New results for fundamental frequencies are presented as affected by crack length, fluid level, fluid density and immersed depth of plate. By employing the method of multiple scales, the frequency response and peak amplitude of the cracked structure is analyzed. The non-linear frequency response curves show the phenomenon of bending hardening or softening and the effect of fluid dynamic pressure on the response of the cracked plate.

  6. On the submerging of a spherical intruder into granular beds

    Directory of Open Access Journals (Sweden)

    Wu Chuan-Yu

    2017-01-01

    Full Text Available Granular materials are complex systems and their mechanical behaviours are determined by the material properties of individual particles, the interaction between particles and the surrounding media, which are still incompletely understood. Using an advanced discrete element method (DEM, we simulate the submerging process of a spherical projectile (an intruder into granular materials of various properties with a zero penetration velocity (i.e. the intruder is touching the top surface of the granular bed and released from stationary and examine its settling behaviour. By systematically changing the density and size of the intruder and the particle density (i.e. the density of the particles in the granular bed, we find that the intruder can sink deep into the granular bed even with a zero penetration velocity. Furthermore, we confirm that under certain conditions the granular bed can behave like a Newtonian liquid and the submerging intruder can reach a constant velocity, i.e. the terminal velocity, identical to the settling of a sphere in a liquid, as observed experimentally. A mathematical model is also developed to predict the maximum penetration depth of the intruder. The model predictions are compared with experimental data reported in the literature,good agreement was obtained, demonstrating the model can accurately predict the submerging behaviour of the intruder in the granular media.

  7. Detecting submerged features in water: modeling, sensors, and measurements

    Science.gov (United States)

    Bostater, Charles R., Jr.; Bassetti, Luce

    2004-11-01

    It is becoming more important to understand the remote sensing systems and associated autonomous or semi-autonomous methodologies (robotic & mechatronics) that may be utilized in freshwater and marine aquatic environments. This need comes from several issues related not only to advances in our scientific understanding and technological capabilities, but also from the desire to insure that the risk associated with UXO (unexploded ordnance), related submerged mines, as well as submerged targets (such as submerged aquatic vegetation) and debris left from previous human activities are remotely sensed and identified followed by reduced risks through detection and removal. This paper will describe (a) remote sensing systems, (b) platforms (fixed and mobile, as well as to demonstrate (c) the value of thinking in terms of scalability as well as modularity in the design and application of new systems now being constructed within our laboratory and other laboratories, as well as future systems. New remote sensing systems - moving or fixed sensing systems, as well as autonomous or semi-autonomous robotic and mechatronic systems will be essential to secure domestic preparedness for humanitarian reasons. These remote sensing systems hold tremendous value, if thoughtfully designed for other applications which include environmental monitoring in ambient environments.

  8. Influence of Microalgae onto submerged surfaces on Fouling

    Science.gov (United States)

    Kong, M.; Eom, C.; Yoon, B.; Yoon, H.; Kim, B.; Chung, K.

    2012-12-01

    Lots of algae together with organic matter deposited on the submerged surface can be easily observed occurring in the shallower water along the coast. This is mainly because only those organisms with the ability to adapt to the new situations created by man can firmly adhere enough to avoid being washed off. Chemical and microbiological characteristics of the fouling microalgae developed on various surfaces in contact with the seawater were made. The microbial compositions of the microalgae formed on the submerged surfaces were tested for. The quantities of the diverse microalgae in the samples developed on the prohibiting submerged surface were larger when there was no concern about materials for special selection for fouling. To confirm formation of microalgae on adsorbents was done SEM-EDS (Scanning Electron Microscope-Spectrometer) analysis. Microbial identified using optical microscope. In addition to, we quantified attaching microalgae as pass time. Experiment results, ten species which are Nitzshhia sp., Eucampia sp., Coscinodiscus sp., Licmophora sp., Rhizosolenia sp., Cylindrotheca sp., Striateela sp., Thalassionema sp., Guinardia sp., and Helicostomella sp. discovered to reservoir formed biofouling. They showed the important role microbial activity in fouling and corrosion of the surfaces in contact with the any seawater.

  9. On arc efficiency in gas tungsten arc welding

    Directory of Open Access Journals (Sweden)

    Nils Stenbacka

    2013-12-01

    Full Text Available The aim of this study was to review the literature on published arc efficiency values for GTAW and, if possible, propose a narrower band. Articles between the years 1955 - 2011 have been found. Published arc efficiency values for GTAW DCEN show to lie on a wide range, between 0.36 to 0.90. Only a few studies covered DCEP - direct current electrode positive and AC current. Specific information about the reproducibility in calorimetric studies as well as in modeling and simulation studies (considering that both random and systematic errors are small was scarce. An estimate of the average arc efficiency value for GTAW DCEN indicates that it should be about 0.77. It indicates anyway that the GTAW process with DCEN is an efficient welding method. The arc efficiency is reduced when the arc length is increased. On the other hand, there are conflicting results in the literature as to the influence of arc current and travel speed.

  10. Electrical characteristics of TIG arcs in argon from non-equilibrium modelling and experiment

    Science.gov (United States)

    Baeva, Margarita; Uhrlandt, Dirk; Siewert, Erwan

    2016-09-01

    Electric arcs are widely used in industrial processes so that a thorough understanding of the arc characteristics is highly important to industrial research and development. TIG welding arcs operated with pointed electrodes made of tungsten, doped with cerium oxide, have been studied in order to analyze in detail the electric field and the arc voltage. Newly developed non-equilibrium model of the arc is based on a complete diffusion treatment of particle fluxes, a generalized form of Ohm's law, and boundary conditions accounting for the space-charge sheaths within the magneto-hydrodynamic approach. Experiments have been carried out for electric currents in the range 5-200 A. The electric arc has been initiated between a WC20 cathode and a water-cooled copper plate placed 0.8 mm from each other. The arc length has been continuously increased by 0.1 mm up to 15 mm and the arc voltage has been simultaneously recorded. Modelling and experimental results will be presented and discussed.

  11. Effect of different electrode tip angles with tilted torch in stationary gas tungsten arc welding: A 3D simulation

    International Nuclear Information System (INIS)

    Abid, M.; Parvez, S.; Nash, D.H.

    2013-01-01

    In this study, the effect of different tip angles (30°, 60°, 90° and 120°) on the arc and weld pool behavior is analyzed in 2 mm and 5 mm arc lengths with tilted (70°) torch. Arc temperature, velocity, current density, heat flux and gas shear are investigated in the arc region and pool convection and puddle shapes are studied in the weld pool region. The arc temperature at the tungsten electrode is found the maximum with sharp tip and decreases as the tip angle increases. The arc temperature on the anode (workpiece) surface becomes concentrated with increase in tip angle. The arc velocity and gas shear stress are observed large with sharp tip and decreasing as the tip angle increases. Current density on the anode surface does not change with tip angle and observed almost the same in all the tip angles in both 2 mm and 5 mm arc lengths. Heat flux due to conduction and convection is observed more sensitive to the tip angle and decreases as the tip angle increases. The electromagnetic force is slightly observed increasing and the buoyancy force is observed slightly decreasing with increase in tip angle. Analyzing each driving force in the weld pool individually shows that the gas drag and Marangoni forces are much stronger than the electromagnetic and buoyancy forces. The weld pool shape is observed wide and shallow in sharp and narrow and deep in large tip angle. Increasing the arc length does not change the weld pool width; however, the weld pool depth significantly changes with arc length and is observed deep in short arc length. The arc properties and weld pool shapes are observed wide ahead of the electrode tip in the weld direction due to 70° torch angle. Good agreement is observed between the numerical and experimental weld pool shapes

  12. Electric arc radius and characteristics

    International Nuclear Information System (INIS)

    Fang, T.M.

    1980-01-01

    The heat transfer equation of an arc discharge has been solved. The arc is assumed to be a cylinder with negligible axial variation and the dominant heat transfer process is conduction radially inside the column and radiation/convection at the outside edge. The symmetric consideration allows a simple one-dimensional formulation. By taking into account proper variation of the electrical conductivity as function of temperature, the heat balance equation has been solved analytically. The radius of the arc and its current-field characteristics have also been obtained. The conventional results that E approx. I 0 5385 and R approx. I 0 7693 with E being the applied field, I the current, and R the radius of the cylindrical arc, have been proved to be simply limiting cases of our more general characteristics. The results can be applied quite widely including, among others, the neutral beam injection project in nuclear fusion and MHD energy conversion

  13. The electrodynamic, thermal, and energetic character of intense sun-aligned arcs in the polar cap

    International Nuclear Information System (INIS)

    Valladares, C.E.; Carlson, H.C. Jr.

    1991-01-01

    The authors report here measurements of two intense Sun-aligned arcs. The two arcs were diagnosed on two different nights (February 26 and March 1, 1987) using the Sondre Stromfjord radar as a stand-alone diagnostic. Repeatable patterns are found in mesoscale area (order 10 3 km by 10 3 km) maps of altitude profiles for observed electron and ion gas number densities, temperatures and line-of-sight velocities, and projected mesoscale area maps of derived electric fields, Pedersen and Hall conductivities (N e , T e , T i , V, E, Σ p , Σ H ), horizontal and field-aligned currents, joule heating rate, and Poynting flux. They confirm, for the first time with continuous mesoscale area maps, that the arcs have the anticipated simple arc electrodynamics. That is, the visual and enhanced ionization signatures of the arc are produced by incoming energetic electrons carrying the outgoing current from the electric field convergence in the arc. Strong electron temperature enhancements (>2,000 K) are found as expected within the sheets of ionizing particle precipitation. Dawn to dusk decreases in the antisunward plasma flow of order 1 km s -1 , across order 100 km, correspond to peak electron densities of order 10 5 cm -3 down to altitudes as low as 120 km, and upward currents of order 1 μA m -2 . These data also lead to important implications for the physics of polar cap arcs. The high-velocity (antisunward flow on the dawnside) edge of the arc marks the location of strong persistent Joule heating driven by downward Poynting flux. The deposition rate into the atmosphere of the net electromagnetic energy well exceeds the net particle energy deposited by the ionizing energetic electron flux. This heating is a substantial source of heat into the polar thermosphere

  14. PC-based arc ignition and arc length control system for gas tungsten arc welding

    International Nuclear Information System (INIS)

    Liu, Y.; Cook, G.E.; Barnett, R.J.; Springfield, J.F.

    1992-01-01

    In this paper, a PC-based digital control system for gas tungsten arc welding (GTAW) is presented. This system controls the arc ignition process, the arc length, and the process of welding termination. A DT2818 made by Data Translation is used for interface and A/D and D/A conversions. The digital I/O ports of the DT2818 are used for control of wirefeed, shield gas, cooling water, welding power supply, etc. The DT2818 is housed in a PC. The welding signals and status are displayed on the screen for in-process monitoring. A user can control the welding process by the keyboard

  15. Theory of flux cutting and flux transport at the critical current of a type-II superconducting cylindrical wire

    International Nuclear Information System (INIS)

    Clem, John R.

    2011-01-01

    I introduce a critical-state theory incorporating both flux cutting and flux transport to calculate the magnetic-field and current-density distributions inside a type-II superconducting cylinder at its critical current in a longitudinal applied magnetic field. The theory is an extension of the elliptic critical-state model introduced by Romero-Salazar and Perez-Rodriguez. The vortex dynamics depend in detail on two nonlinear effective resistivities for flux cutting (ρ(parallel)) and flux flow (ρ(perpendicular)), and their ratio r = ρ(parallel)/ρ(perpendicular). When r c (φ) that makes the vortex arc unstable.

  16. Arc modeling for welding analysis

    International Nuclear Information System (INIS)

    Glickstein, S.S.

    1978-04-01

    A one-dimensional model of the welding arc that considers heat generation by the Joule effect and heat losses by radiation and conduction has been used to study the effects of various gases and gas mixtures currently employed for welding applications. Minor additions of low ionization potential impurities to these gases are shown to significantly perturb the electrical properties of the parent gas causing gross changes in the radial temperature distribution of the arc discharge. Such changes are reflected in the current density distribution and ultimately in the input energy distribution to the weldment. The result is observed as a variation in weld penetration. Recently published experiments and analyses of welding arcs are also evaluated and shown to contain erroneous data and results. Contrary to previous beliefs, the inclusion of a radiation loss term in the basic energy balance equation is important and cannot be considered as negligible in an argon arc at temperatures as low as 10,000 0 K. The one-dimensional analysis of the welding arc as well as the evaluation of these earlier published reports helps to explain the effects of various gases used for welding, improves our understanding of the physics of the welding arc, and provides a stepping stone for a more elaborate model which can be applied to help optimize welding parameters

  17. In-situ assessment of biofilm formation in submerged membrane system using optical coherence tomography and computational fluid dynamics

    KAUST Repository

    Fortunato, Luca

    2016-09-09

    This paper introduces a novel approach to study the biofouling development on gravity driven submerged membrane bioreactor (SMBR). The on-line monitoring of biofilm formation on a flat sheet membrane was conducted non-destructively using optical coherence tomography (OCT), allowing the in-situ investigation of the biofilm structure for 43 d. The OCT enabled to obtain a time-lapse of biofilm development on the membrane under the continuous operation. Acquired real-time information on the biofilm structure related to the change in the flux profile confirming the successful monitoring of the dynamic evolution of the biofouling layer. Four different phases were observed linking the permeate flux with the change of biofilm morphology. In particular, a stable flux of 2.1±0.1 L/m2 h was achieved with the achievement of steady biofilm morphology after 30 d of operation. Biofilm descriptors, such as thickness, biofilm area, macro-porosity and roughness (absolute and relative), were calculated for each OCT acquired scans. Interestingly, relative roughness was correlated with the flux decrease. Furthermore, the precise biofilm morphology obtained from the OCT scans was used in computational fluid dynamics (CFD) simulation to better understand the role of biofilm structure on the filtration mechanism. © 2016 Elsevier B.V.

  18. Magmatically Greedy Reararc Volcanoes of the N. Tofua Segment of the Tonga Arc

    Science.gov (United States)

    Rubin, K. H.; Embley, R. W.; Arculus, R. J.; Lupton, J. E.

    2013-12-01

    Volcanism along the northernmost Tofua Arc is enigmatic because edifices of the arc's volcanic front are mostly, magmatically relatively anemic, despite the very high convergence rate of the Pacific Plate with this section of Tonga Arc. However, just westward of the arc front, in terrain generally thought of as part of the adjacent NE Lau Backarc Basin, lie a series of very active volcanoes and volcanic features, including the large submarine caldera Niuatahi (aka volcano 'O'), a large composite dacite lava flow terrain not obviously associated with any particular volcanic edifice, and the Mata volcano group, a series of 9 small elongate volcanoes in an extensional basin at the extreme NE corner of the Lau Basin. These three volcanic terrains do not sit on arc-perpendicular cross chains. Collectively, these volcanic features appear to be receiving a large proportion of the magma flux from the sub-Tonga/Lau mantle wedge, in effect 'stealing' this magma flux from the arc front. A second occurrence of such magma 'capture' from the arc front occurs in an area just to the south, on southernmost portion of the Fonualei Spreading Center. Erupted compositions at these 'magmatically greedy' volcanoes are consistent with high slab-derived fluid input into the wedge (particularly trace element abundances and volatile contents, e.g., see Lupton abstract this session). It is unclear how long-lived a feature this is, but the very presence of such hyperactive and areally-dispersed volcanism behind the arc front implies these volcanoes are not in fact part of any focused spreading/rifting in the Lau Backarc Basin, and should be thought of as 'reararc volcanoes'. Possible tectonic factors contributing to this unusually productive reararc environment are the high rate of convergence, the cold slab, the highly disorganized extension in the adjacent backarc, and the tear in the subducting plate just north of the Tofua Arc.

  19. Critical flux determination by flux-stepping

    DEFF Research Database (Denmark)

    Beier, Søren; Jonsson, Gunnar Eigil

    2010-01-01

    In membrane filtration related scientific literature, often step-by-step determined critical fluxes are reported. Using a dynamic microfiltration device, it is shown that critical fluxes determined from two different flux-stepping methods are dependent upon operational parameters such as step...... length, step height, and.flux start level. Filtrating 8 kg/m(3) yeast cell suspensions by a vibrating 0.45 x 10(-6) m pore size microfiltration hollow fiber module, critical fluxes from 5.6 x 10(-6) to 1.2 x 10(-5) m/s have been measured using various step lengths from 300 to 1200 seconds. Thus......, such values are more or less useless in itself as critical flux predictors, and constant flux verification experiments have to be conducted to check if the determined critical fluxes call predict sustainable flux regimes. However, it is shown that using the step-by-step predicted critical fluxes as start...

  20. An explanation of closed-flux formation and sustainment using coaxial helicity injection on HIT-II

    International Nuclear Information System (INIS)

    Jarboe, T R

    2010-01-01

    An explanation of the closed-flux operation on HIT-II is given. This method of operation generated flux amplification and closed flux on HIT-II without the presence of n = 1 or any large amplitude mode as measured from the outside shell. The method of operating also prevents hard absorber arcs and maximizes the toroidal current.

  1. Enhanced phosphorus reduction in simulated eutrophic water: a comparative study of submerged macrophytes, sediment microbial fuel cells, and their combination.

    Science.gov (United States)

    Xu, Peng; Xiao, Enrong; Xu, Dan; Li, Juan; Zhang, Yi; Dai, Zhigang; Zhou, Qiaohong; Wu, Zhenbin

    2018-05-01

    The phosphorus reduction in water column was attempted by integrating sediment microbial fuel cells (SMFCs) with the submerged macrophyte Vallisneria spiralis. A comparative study was conducted to treat simulated water rich in phosphate with a control and three treatments: SMFC alone (SMFC), submerged macrophytes alone (macophyte), and combined macrophytes and fuel cells (M-SMFC). All treatments promoted phosphorus flux from the water column to sediments. Maximum phosphorus reduction was obtained in proportion to the highest stable phosphorus level in sediments in M-SMFC. For the initial phosphate concentrations of 0.2, 1, 2, and 4 mg/L, average phosphate values in the overlying water during four phases decreased by 33.3% (25.0%, 8.3%), 30.8% (5.1%, 17.9%), 36.5% (27.8%, 15.7%), and 36.2% (0.7%, 22.1%) for M-SMFC (macrophyte, SMFC), compared with the control. With macrophyte treatment, the obvious phosphorus release from sediments was observed during the declining period. However, such phenomenon was significantly inhibited with M-SMFC. The electrogenesis bacteria achieved stronger phosphorus adsorption and assimilation was significantly enriched on the closed-circuit anodes. The higher abundance of Geobacter and Pseudomonas in M-SMFC might in part explain the highest phosphorus reduction in the water column. M-SMFC treatment could be promising to control the phosphorus in eutrophic water bodies.

  2. GigaUnit Transplant System: A New Mechanical Tool for Transplanting Submerged Aquatic Vegetation

    National Research Council Canada - National Science Library

    Shafer, Deborah J

    2008-01-01

    Submerged aquatic vegetation (SAV) performs many important ecosystem functions, including wave attenuation and sediment stabilization, water quality improvement, primary production, food web support for secondary consumers...

  3. Computer Modeling of Radiative Transfer in Hybrid-Stabilized Argon–Water Electric Arc

    Czech Academy of Sciences Publication Activity Database

    Jeništa, Jiří; Takana, H.; Nishiyama, H.; Křenek, Petr; Bartlová, M.; Aubrecht, V.

    2011-01-01

    Roč. 39, č. 11 (2011), s. 2892-2893 ISSN 0093-3813 Institutional research plan: CEZ:AV0Z20430508 Keywords : Divergence of radiation flux * hybrid-stabilized electric arc * mass flow rate * partial characteristics * radiation flux Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.174, year: 2011 http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=27

  4. Physically based arc-circuit interaction

    International Nuclear Information System (INIS)

    Zhong-Lie, L.

    1984-01-01

    An integral arc model is extended to study the interaction of the gas blast arc with the test circuit in this paper. The deformation in the waveshapes of arc current and voltage around the current zero has been formulated to first approximation by using a simple model of arc voltage based on the arc core energy conservation. By supplementing with the time scale for the radiation, the time rates of arc processes were amended. Both the contributions of various arc processes and the influence of circuit parameters to the arc-circuit interaction have been estimated by this theory. Analysis generated a new method of calculating test circuit parameters which improves the accurate simulation of arc-circuit interaction. The new method agrees with the published experimental results

  5. Enhanced Sorbitol Production under Submerged Fermentation using Lactobacillus plantarum

    Directory of Open Access Journals (Sweden)

    Khan Nadiya Jan

    2017-04-01

    Full Text Available Background and Objective: Sorbitol is a non-toxic and slightly hygroscopic compound with different applications. Zymomonas mobiles produces sorbitol from sucrose or mixtures of glucose and fructose (formation is coupled with the dehydrogenation of glucose to glucono-δ- lactone. Recombinant Zymomonas mobilis may produce sorbitol and gluconic acid from glucose and fructose using different divalent metal ions with reduced the ethanol yield andsignificantly increased yield of sorbitol. Current study envisaged to alter the media components, physical process parameters and supplementation of amino acids for enhanced sorbitol production.Material and Methods: Several process variables were evaluated on sorbitol production including carbon sources (glucose, fructose, maltose, sucrose, carbon concentrations (5, 10, 20 and 25 g l-1, nitrogen sources (peptone, tryptone, yeast extract, beef extract and organic nitrogen mix, temperatures (25, 29, 33, 37, 41°C, pH (6, 6.5, 7 , 7.5 ,8, agitation rate (50, 100, 150, 200 rpm and amino acids (cysteine, cystine, tryptophanin batch cultivation ofLactobacillus plantarum NCIM 2912. Shake flask cultivation performed under optimum conditions like temperature 37°C, pH 7.0 and agitation rate of 150 rpm, resulted in enhanced sorbitol production. Comparative study of sorbitol production in solid state fermentation and submerged fermentation was also evaluated.Results and Conclusion: Batch cultivation under submerged conditions further performed in 7.5-l lab scale bioreactor (working volume 3.0-l under optimized conditions resulted in maximum cell biomass of 8.95±0.03 g g-1 and a sorbitol content of 9.78±0.04 g l-1 after 42.0 h of fermentation. Scale up study on bioreactor resulted in maximum sorbitol yield (Yp/x and productivity of 1.11 g g-1 and 0.50 g l-1 h under submerged fermentation, respectively.Conflict of interest: The authors declare no conflict of interest.

  6. Liquid Film Diffusion on Reaction Rate in Submerged Biofilters

    DEFF Research Database (Denmark)

    Christiansen, Pia; Hollesen, Line; Harremoës, Poul

    1995-01-01

    Experiments were carried out in order to investigate the influence of liquid film diffusion on reaction rate in a submerged biofilter with denitrification and in order to compare with a theoretical study of the mass transfer coefficient. The experiments were carried out with varied flow, identified...... by the empty bed velocity of inflow and recirculation, respectively 1.3, 2.8, 5.6 and 10.9 m/h. The filter material consisted of 3 mm biostyren spheres. The results indicate that the influence of liquid film diffusion on reaction rate can be ignored....

  7. Discharge modes at the anode of a vacuum arc

    International Nuclear Information System (INIS)

    Miller, H.C.

    1982-01-01

    The two most common anode modes in a vacuum arc are the low current mode, where the anode is basically inert; and the high current mode with a fully developed anode spot. This anode spot is very bright, has a temperature near the boiling point of the anode material, and is a copious source of vapor and energetic ions. However, other anode modes can exist. A low current vacuum arc with electrodes of readily sputterable material will emit a flux of sputtered atoms from the anode. An intermediate currents an anode footpoint can form. This footpoint is luminous, but much cooler than a true anode spot. Finally, a high current mode can exist where several small anode spots are present instead of a single large anode spot

  8. Emission mechanism in high current hollow cathode arcs

    International Nuclear Information System (INIS)

    Krishnan, M.

    1976-01-01

    Large (2 cm-diameter) hollow cathodes have been operated in a magnetoplasmadynamic (MPD) arc over wide ranges of current (0.25 to 17 kA) and mass flow (10 -3 to 8 g/sec), with orifice current densities and mass fluxes encompassing those encountered in low current steady-state hollow cathode arcs. Detailed cathode interior measurements of current and potential distributions show that maximum current penetration into the cathode is about one diameter axially upstream from the tip, with peak inner surface current attachment up to one cathode diameter upstream of the tip. The spontaneous attachment of peak current upstream of the cathode tip is suggested as a criterion for characteristic hollow cathode operation. This empirical criterion is verified by experiment

  9. Toward Assessing the Causes of Volcanic Diversity in the Cascades Arc

    Science.gov (United States)

    Till, C. B.; Kent, A. J.; Abers, G. A.; Pitcher, B.; Janiszewski, H. A.; Schmandt, B.

    2017-12-01

    A fundamental unanswered question in subduction system science is the cause of the observed diversity in volcanic arc style at an arc-segment to whole-arc scale. Specifically, we have yet to distinguish the predominant mantle and crustal processes responsible for the diversity of arc volcanic phenomenon, including the presence of central volcanoes vs. dispersed volcanism; episodicity in volcanic fluxes in time and space; variations in magma chemistry; and differences in the extent of magmatic focusing. Here we present a thought experiment using currently available data to estimate the relative role of crustal magmatic processes in producing the observed variations in Cascades arc volcanism. A compilation of available major element compositions of Quaternary arc volcanism and estimates of eruptive volumes are used to examine variations in the composition of arc magmas along strike. We then calculate the Quaternary volcanic heat flux into the crust, assuming steady state, required to produce the observed distribution of compositions via crystallization of mantle-derived primitive magmas vs. crustal melting using experiment constraints on possible liquid lines of descent and crustal melting scenarios. For pure crystallization, heat input into the crust scales with silica content, with dacitic to rhyolite compositions producing significantly greater latent heat relative to basalts to andesites. In contrast, the heat required to melt lower crustal amphibolite decreases with increasing silica and is likely provided by the latent heat of crystallization. Thus we develop maximum and minimum estimates for heat added to the crust at a given SiO2 range. When volumes are considered, we find that the average Quaternary volcanic heat flux at latitudes south of South Sister to be more than twice that to the north. Distributed mafic volcanism produces only a quarter to half the heat flux calculated for the main edifices at a given latitude because of their lesser eruptive volumes

  10. Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis.

    Science.gov (United States)

    Raniszewski, Grzegorz; Wiak, Slawomir; Pietrzak, Lukasz; Szymanski, Lukasz; Kolacinski, Zbigniew

    2017-02-23

    One of the most common methods of carbon nanotubes (CNTs) synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon-plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs). It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented.

  11. Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis

    Directory of Open Access Journals (Sweden)

    Grzegorz Raniszewski

    2017-02-01

    Full Text Available One of the most common methods of carbon nanotubes (CNTs synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon–plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs. It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented.

  12. Arcing phenomena in fusion devices workshop

    International Nuclear Information System (INIS)

    Clausing, R.E.

    1979-01-01

    The workshop on arcing phenomena in fusion devices was organized (1) to review the pesent status of our understanding of arcing as it relates to confinement devices, (2) to determine what informaion is needed to suppress arcing and (3) to define both laboratory and in-situ experiments which can ultimately lead to reduction of impurities in the plasma caused by arcing. The workshop was attended by experts in the area of vacuum arc electrode phenomena and ion source technology, materials scientists, and both theoreticians and experimentalists engaged in assessing the importance of unipolar arcing in today's tokamaks. Abstracts for papers presented at the workshop are included

  13. Equilibrium motion of quict auroral arcs

    International Nuclear Information System (INIS)

    Lyatskij, V.B.; Leont'ev, S.V.

    1981-01-01

    Ionospheric plasma convection across auroral arc is investigated. It is shown that the existence of plasma area of increased concentration adjoining arc results not only from the arc but also is a factor supporting its existence. Under stable conditions the arc and plasma zone connected to it will move at a velocity different from a velocity of plasma convection. Arc velocity will be higher or lower as compared with convection velocity depending on arc orientation relative to an external electric field. At that the plasma zone is located either in front of or behind aurora polaris [ru

  14. Study on submerged anaerobic membrane bioreactor (SAMBR) treating high suspended solids raw tannery wastewater for biogas production.

    Science.gov (United States)

    Umaiyakunjaram, R; Shanmugam, P

    2016-09-01

    This study deals with the treatment of high suspended solids raw tannery wastewater using flat sheet Submerged Anaerobic Membrane (0.4μm) Bioreactor (SAMBR) acclimatized with hypersaline anaerobic seed sludge for recovering biogas. The treatability of SAMBR achieved higher CODremoval efficiency (90%) and biogas yield (0.160L.g(-1) CODremoved) coincided with high r(2) values between permeate flux and TSS (0.95), biogas and COD removed (0.96). The acidification of hypersaline influent wastewater by biogas mixing with high CO2, achieved quadruplet benefit of gas liquid and solid separation, in-situ pH and NH3 control, in-situ CH4 enrichment, and prevention of membrane fouling. The initial high VFA became stable as time elapsed reveals the hydrolysing ability of particulate COD into soluble COD and into biogas, confirms the suitability of SAMBR for high suspended solids tannery wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Higher-order turbulence statistics of wave–current flow over a submerged hemisphere

    Energy Technology Data Exchange (ETDEWEB)

    Barman, Krishnendu; Debnath, Koustuv; Mazumder, Bijoy S, E-mail: debnath_koustuv@yahoo.com [Department of Aerospace Engineering and Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah 711103, West Bengal (India)

    2017-04-15

    Higher-order turbulence characteristics such as turbulence production, turbulence kinetic energy flux, third order moments and velocity spectra associated with turbulent bursting events due to the influence of a submerged hemisphere under wave–current interactions are presented. The velocity components were measured using three dimensional (3D) 16 MHz micro-acoustic Doppler velocimetry (Micro-ADV). In the wave–current interactions, the contributions of turbulent bursting events such as ejections and sweeps significantly reduce in comparison to the current-only case. The distributions of the mean time intervals of ejection and sweeping events are found to alter due to the superposition of surface waves. Results also depict that the turbulence production in the wake region of the hemisphere reduces remarkably, due to the superposition of surface waves on the current. Further, spectral and co-spectral analysis demonstrates that there is a significant reduction of power spectral peak for both longitudinal and bottom-normal velocities upon superposition of surface waves, which signifies a remarkable change in energy distribution between different frequencies of waves. (paper)

  16. Effect of different leachate/acetate ratios in a submerged anaerobic membrane bioreactor (SAnMBR)

    Energy Technology Data Exchange (ETDEWEB)

    Taskan, Ergin [Department of Environmental Engineering, Faculty of Engineering, Firat University, Elazig (Turkey); Hasar, Halil [Department of Environmental Engineering, Faculty of Engineering, Firat University, Elazig (Turkey); National Research Center on Membrane Technologies, Maslak, Istanbul (Turkey)

    2012-05-15

    Leachate treatment using a membrane bioreactor is an effective method. This study presents a configuration including an anaerobic bioreactor and a membrane module, called submerged anaerobic membrane bioreactor (SAnMBR), for treating influent with leachate/acetate rations (L/A), that were kept to be 10, 25, 50, 75, and 100% at a constant SRT (100 days). COD removal decreased from 85 to 75% when the L/A ratio increased from 10 to 100. To prevent membrane fouling, a SAnMBR was operated in the case of circulation of mixed liquor under continuous and intermittent suction. The average fluxes were 2.60 and 0.40 L/m{sup 2} h at the periods of intermittent and continuous suction, respectively. The methane production varied between 0.25 and 0.32 L CH{sub 4}/g COD{sub removed}. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Multi-instrumentation observations of a transpolar arc in the northern hemisphere

    Directory of Open Access Journals (Sweden)

    A. Goudarzi

    2008-02-01

    Full Text Available A transpolar arc was imaged by the FUV instrument on the IMAGE spacecraft during a 3-h interval on 5 February 2002. Observations indicate that a burst of reconnection in the geomagnetic tail, which was not associated with a substorm, was responsible for the formation of the arc. The arc initially formed across the central polar cap, extending from near midnight to noon such that the polar cap was approximately divided in half. The subsequent motion of the arc was controlled by the amount of open flux being added to the dawn sector cap from a magnetopause reconnection site on the post-noon side of the magnetosphere. The dayside reconnection happened during a period when the IMF By component was dominant, although the Bz component initially remained positive, and resulted in strong westward azimuthal flows in the noon sector. The arc continued to move towards the duskside auroral oval after the IMF Bz turned southward. A keogram of the FUV/WIC auroral observations along the dawn-dusk meridian provides further evidence of the expansion and contraction of the polar cap during the period in which different IMF orientations occurred. Furthermore, comparing images from IMAGE and ionospheric convection flow from SuperDARN measurements, vortical convection flows occurred exactly at the time and location of the formation of the transpolar arc and subsequently followed the head of the transpolar arc as it moved across the polar cap. The observations are consistent with the prediction of a recent model for the formation of the transpolar cap by the closure of open flux in the geomagnetic tail, and its subsequent motion through changes in the open flux distribution within the polar cap.

  18. Multi-instrumentation observations of a transpolar arc in the northern hemisphere

    Directory of Open Access Journals (Sweden)

    A. Goudarzi

    2008-02-01

    Full Text Available A transpolar arc was imaged by the FUV instrument on the IMAGE spacecraft during a 3-h interval on 5 February 2002. Observations indicate that a burst of reconnection in the geomagnetic tail, which was not associated with a substorm, was responsible for the formation of the arc. The arc initially formed across the central polar cap, extending from near midnight to noon such that the polar cap was approximately divided in half. The subsequent motion of the arc was controlled by the amount of open flux being added to the dawn sector cap from a magnetopause reconnection site on the post-noon side of the magnetosphere. The dayside reconnection happened during a period when the IMF By component was dominant, although the Bz component initially remained positive, and resulted in strong westward azimuthal flows in the noon sector. The arc continued to move towards the duskside auroral oval after the IMF Bz turned southward. A keogram of the FUV/WIC auroral observations along the dawn-dusk meridian provides further evidence of the expansion and contraction of the polar cap during the period in which different IMF orientations occurred. Furthermore, comparing images from IMAGE and ionospheric convection flow from SuperDARN measurements, vortical convection flows occurred exactly at the time and location of the formation of the transpolar arc and subsequently followed the head of the transpolar arc as it moved across the polar cap. The observations are consistent with the prediction of a recent model for the formation of the transpolar cap by the closure of open flux in the geomagnetic tail, and its subsequent motion through changes in the open flux distribution within the polar cap.

  19. Arcing at B4C-covered limiters exposed to a SOL-plasma

    International Nuclear Information System (INIS)

    Laux, M.; Schneider, W.; Wienhold, P.; Juettner, B.; Huber, A.; Balden, M.; Linke, J.; Kostial, H.; Mayer, M.; Rubel, M.; Herrmann, A.; Pospieszczyk, A.; Jachmich, S.; Schweer, B.; Hildebrandt, D.; Bolt, H.

    2003-01-01

    Plasma sprayed B 4 C-layers considered as wall coatings for the W7X stellarator have been studied during and after exposure to TEXTOR and after arcing experiments in vacuum. Arcing through the B 4 C layer occurred favoured by high power fluxes and not restricted to less stable phases. But this arcing implies an especially noisy scrape-off layer (SOL). Instead of moving retrograde in the external magnetic field, the arc spot on the B 4 C-layer sticks to the same location for its whole lifetime. Consequently, the arc erodes the entire B 4 C layer, finally burning down to the Cu substrate. In the neighbourhood of craters the surface contains Cu originating from those craters. This material, hauled to the surface by the arc, is subject to subsequent erosion, transport, and redeposition by the SOL-plasma. The behaviour of arcs on B 4 C is most probably caused by the peculiar temperature dependences of the electrical and heat conductivity of B 4 C

  20. Principles of arc flash protection

    Energy Technology Data Exchange (ETDEWEB)

    Hirschmann, R. B.

    2003-04-01

    Recent developments in NFPA 70E, the electrical safety standards in the United States and Canada, designed to provide for a safe industrial work environment, are discussed. The emphasis in this instance is on arc explosions. Development of an arc flash protective program is discussed under various major components of an electrical safety program. These are: appropriate qualifications and training for workers, safe work practices, appropriate hazard assessment practices for any task exceeding 50V where there is the potential of an arc flash accident, flash protection equipment commensurate with the hazard associated with the task to be performed, layering in protective clothing over all body surfaces, and strict adherence to rules regarding use of safety garments and equipment.

  1. Magnetically enhanced vacuum arc thruster

    International Nuclear Information System (INIS)

    Keidar, Michael; Schein, Jochen; Wilson, Kristi; Gerhan, Andrew; Au, Michael; Tang, Benjamin; Idzkowski, Luke; Krishnan, Mahadevan; Beilis, Isak I

    2005-01-01

    A hydrodynamic model of the vacuum arc thruster and its plume is described. Primarily an effect of the magnetic field on the plume expansion and plasma generation is considered. Two particular examples are investigated, namely the magnetically enhanced co-axial vacuum arc thruster (MVAT) and the vacuum arc thruster with ring electrodes (RVAT). It is found that the magnetic field significantly decreases the plasma plume radial expansion under typical conditions. Predicted plasma density profiles in the plume of the MVAT are compared with experimental profiles, and generally a good agreement is found. In the case of the RVAT the influence of the magnetic field leads to plasma jet deceleration, which explains the non-monotonic dependence of the ion current density, on an axial magnetic field observed experimentally

  2. Magnetically enhanced vacuum arc thruster

    Energy Technology Data Exchange (ETDEWEB)

    Keidar, Michael [University of Michigan, Ann Arbor 48109 MI (United States); Schein, Jochen [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Wilson, Kristi [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Gerhan, Andrew [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Au, Michael [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Tang, Benjamin [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Idzkowski, Luke [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Krishnan, Mahadevan [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Beilis, Isak I [Tel Aviv University, Tel Aviv (Israel)

    2005-11-01

    A hydrodynamic model of the vacuum arc thruster and its plume is described. Primarily an effect of the magnetic field on the plume expansion and plasma generation is considered. Two particular examples are investigated, namely the magnetically enhanced co-axial vacuum arc thruster (MVAT) and the vacuum arc thruster with ring electrodes (RVAT). It is found that the magnetic field significantly decreases the plasma plume radial expansion under typical conditions. Predicted plasma density profiles in the plume of the MVAT are compared with experimental profiles, and generally a good agreement is found. In the case of the RVAT the influence of the magnetic field leads to plasma jet deceleration, which explains the non-monotonic dependence of the ion current density, on an axial magnetic field observed experimentally.

  3. Unzipping of the volcano arc, Japan

    Science.gov (United States)

    Stern, R.J.; Smoot, N.C.; Rubin, M.

    1984-01-01

    A working hypothesis for the recent evolution of the southern Volcano Arc, Japan, is presented which calls upon a northward-progressing sundering of the arc in response to a northward-propagating back-arc basin extensional regime. This model appears to explain several localized and recent changes in the tectonic and magrnatic evolution of the Volcano Arc. Most important among these changes is the unusual composition of Iwo Jima volcanic rocks. This contrasts with normal arc tholeiites typical of the rest of the Izu-Volcano-Mariana and other primitive arcs in having alkaline tendencies, high concentrations of light REE and other incompatible elements, and relatively high silica contents. In spite of such fractionated characteristics, these lavas appear to be very early manifestations of a new volcanic and tectonic cycle in the southern Volcano Arc. These alkaline characteristics and indications of strong regional uplift are consistent with the recent development of an early stage of inter-arc basin rifting in the southern Volcano Arc. New bathymetric data are presented in support of this model which indicate: 1. (1) structural elements of the Mariana Trough extend north to the southern Volcano Arc. 2. (2) both the Mariana Trough and frontal arc shoal rapidly northwards as the Volcano Arc is approached. 3. (3) rugged bathymetry associated with the rifted Mariana Trough is replaced just south of Iwo Jima by the development of a huge dome (50-75 km diameter) centered around Iwo Jima. Such uplifted domes are the immediate precursors of rifts in other environments, and it appears that a similar situation may now exist in the southern Volcano Arc. The present distribution of unrifted Volcano Arc to the north and rifted Mariana Arc to the south is interpreted not as a stable tectonic configuration but as representing a tectonic "snapshot" of an arc in the process of being rifted to form a back-arc basin. ?? 1984.

  4. A New Detection Method for Submerged Implants: Oral Tattoo.

    Science.gov (United States)

    Soylu, Emrah; Gönen, Zeynep Burçin; Alkan, Alper

    2018-04-01

    To evaluate the marking potential of tattoo ink in determining the definitive locations of submerged implants at the time of surgical exposure of the implants. In total, 104 implants in 32 patients were included in this study. After placement of the implants, cover screws were inserted. Overlying mucosa was marked with tattoo ink using a 20 g needle through the center of the cover screw. At the time of surgical exposure the tattoo marks were evaluated relative to visibility. At the time of the surgical exposures, tattoo ink was clearly visible at 91 implants, slightly visible at 8 implants, and not visible at 5 implants. After detection and classification of tattoo ink, the overlying mucosa was gently removed by tissue punch under local anesthesia. The results of this study seemed to indicate that marking the location of implants with tattoos at the time of implant placement can be an inexpensive, easy, healthy, and practical way to identify the location of marked submerged dental implants. © 2016 by the American College of Prosthodontists.

  5. Bistatic scattering from submerged unexploded ordnance lying on a sediment.

    Science.gov (United States)

    Bucaro, J A; Simpson, H; Kraus, L; Dragonette, L R; Yoder, T; Houston, B H

    2009-11-01

    The broadband bistatic target strengths (TSs) of two submerged unexploded ordnance (UXO) targets have been measured in the NRL sediment pool facility. The targets-a 5 in. rocket and a 155 mm projectile-were among the targets whose monostatic TSs were measured and reported previously by the authors. Bistatic TS measurements were made for 0 degrees (target front) and 90 degrees (target side) incident source directions, and include both backscattered and forward scattered echo angles over a complete 360 degrees with the targets placed proud of the sediment surface. For the two source angles used, each target exhibits two strong highlights: a backscattered specular-like echo and a forward scattered response. The TS levels of the former are shown to agree reasonably well with predictions, based on scattering from rigid disks and cylinders, while the levels of the latter with predictions from radar cross section models, based on simple geometric optics appropriately modified. The bistatic TS levels observed for the proud case provide comparable or higher levels of broadband TS relative to free-field monostatic measurements. It is concluded that access to bistatic echo information in operations aimed at detecting submerged UXO targets could provide an important capability.

  6. Cathodic disbonding of organic coatings on submerged steel

    Energy Technology Data Exchange (ETDEWEB)

    Knudsen, Ole oeystein

    1998-12-31

    In offshore oil production, submerged steel structures are commonly protected by an organic coating in combination with cathodic protection. The main advantage is that the coating decreases the current demand for cathodic protection. But the coating degrades with time. This thesis studies one of the most important mechanisms for coating degradation in seawater, cathodic disbonding. Seven commercial coatings and two model coatings with various pigmentations have been studied. Parameter studies, microscopy and studies of free films were used in the mechanism investigations. Exposure to simulated North Sea conditions was used in the performance studies. The effect of aluminium and glass barrier pigments on cathodic disbonding was investigated. The mechanism for the effect of the aluminium pigments on cathodic disbonding was also investigated. The transport of charge and oxygen to the steel/coating interface during cathodic disbonding was studied for two epoxy coatings. Cathodic disbonding, blistering and current demand for cathodic protection was measured for nine commercial coatings for submerged steel structures, using the ASTM-G8 standard test and a long term test under simulated North Sea conditions. The relevance of the ASTM-G8 test as a prequalification test was evaluated. 171 refs., 40 figs., 6 tabs.

  7. THE INFLUENCE OF SUBMERGED MACROPHYTES ON SEDIMENTARY DIATOM ASSEMBLAGES(1).

    Science.gov (United States)

    Vermaire, Jesse C; Prairie, Yves T; Gregory-Eaves, Irene

    2011-12-01

    Submerged macrophytes are a central component of lake ecosystems; however, little is known regarding their long-term response to environmental change. We have examined the potential of diatoms as indicators of past macrophyte biomass. We first sampled periphyton to determine whether habitat was a predictor of diatom assemblage. We then sampled 41 lakes in Quebec, Canada, to evaluate whether whole-lake submerged macrophyte biomass (BiomEpiV) influenced surface sediment diatom assemblages. A multivariate regression tree (MRT) was used to construct a semiquantitative model to reconstruct past macrophyte biomass. We determined that periphytic diatom assemblages on macrophytes were significantly different from those on wood and rocks (ANOSIM R = 0.63, P macrophyte, nutrient-limited lakes (BiomEpiV ≥525 μg · L(-1) ; total phosphorus [TP] macrophyte, nutrient-limited lakes (BiomEpiV macrophytes have a significant influence on diatom community structure and that sedimentary diatom assemblages can be used to infer past macrophyte abundance. © 2011 Phycological Society of America.

  8. Sludge mobilization with submerged nozzles in horizontal cylindrical tanks

    International Nuclear Information System (INIS)

    Hylton, T.D.; Cummins, R.L.; Youngblood, E.L.; Perona, J.J.

    1995-10-01

    The Melton Valley Storage Tanks (MVSTs) and the evaporator service tanks at the Oak Ridge National Laboratory (ORNL) are used for the collection and storage of liquid low-level waste (LLLW). Wastes collected in these tanks are typically acidic when generated and are neutralized with sodium hydroxide to protect the tanks from corrosion; however, the high pH of the solution causes the formation of insoluble compounds that precipitate. These precipitates formed a sludge layer approximately 0.6 to 1.2 m (2 to 4 ft) deep in the bottom of the tanks. The sludge in the MVSTs and the evaporator service tanks will eventually need to be removed from the tanks and treated for final disposal or transferred to another storage facility. The primary options for removing the sludge include single-point sluicing, use of a floating pump, robotic sluicing, and submerged-nozzle sluicing. The objectives of this study were to (1) evaluate the feasibility of submerged-nozzle sluicing in horizontal cylindrical tanks and (2) obtain experimental data to validate the TEMPEST (time-dependent, energy, momentun, pressure, equation solution in three dimensions) computer code

  9. The USGS role in mapping the nation's submerged lands

    Science.gov (United States)

    Schwab, Bill; Haines, John

    2004-01-01

    The seabed provides habitat for a diverse marine life having commercial, recreational, and intrinsic value. The habitat value of the seabed is largely a function of the geological structure and related geological, biological, oceanologic, and geochemical processes. Of equal importance, the nation's submerged lands contain energy and mineral resources and are utilized for the siting of offshore infrastructure and waste disposal. Seabed character and processes influence the safety and viability of offshore operations. Seabed and subseabed characterization is a prerequisite for the assessment, protection, and utilization of both living and non-living marine resources. A comprehensive program to characterize and understand the nation's submerged lands requires scientific expertise in the fields of geology, biology, hydrography, and oceanography. The U.S. Geological Survey (USGS) has long experience as the Federal agency charged with conducting geologic research and mapping in both coastal and offshore regions. The USGS Coastal and Marine Geology Program (CMGP) leads the nation in expertise related to characterization of seabed and subseabed geology, geological processes, seabed dynamics, and (in collaboration with the National Oceanic and Atmospheric Administration (NOAA) and international partners) habitat geoscience. Numerous USGS studies show that sea-floor geology and processes determine the character and distribution of biological habitats, control coastal evolution, influence the coastal response to storm events and human alterations, and determine the occurrence and concentration of natural resources.

  10. Analysis of microstructural variation and mechanical behaviors in submerged arc welded joint of high strength low carbon bainitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Lan, Liangyun, E-mail: lly.liangyun@gmail.com [State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819 (China); Qiu, Chunlin; Zhao, Dewen; Gao, Xiuhua; Du, Linxiu [State Key Laboratory of Rolling Technology and Automation, Northeastern University, Shenyang 110819 (China)

    2012-12-15

    Microstructural variation in high strength low carbon bainitic steel weldment was investigated in detail by means of optical microscope, transmission electron microscope and scanning electron microscope equipped with electron backscattered diffraction. The results showed that the welded joint has various microstructures such as acicular ferrite, coarse granular ferrite and fine polygonal ferrite. The martensite-austenite (MA) constituent has a variable structure in each sub-zone, which includes fully martensite and fully retained austenite. Meanwhile, the fine grained heat affected zone has higher content of retained austenite than the welded metal (WM) and coarse grained heat affected zone (CGHAZ). The orientation relationship between retained austenite and product phases in the WM and CGHAZ is close to Kurdjumov-Sachs relationship. However, the polygonal ferrite in the fine grained HAZ has no specific orientation relationship with the neighboring retained austenite. The toughness of the coarse grained region is much lower than that of the WM because the coarse bainite contains many large MA constituents to assist the nucleation of microcracks and coarse cleavage facet lowers the ability to inhibit the crack propagation.

  11. A functional comparison of acclimation to shade and submergence in two terrestrial plant species

    NARCIS (Netherlands)

    Mommer, L.; Kroon, de H.; Pierik, R.; bögemann, G.M.; Visser, E.J.W.

    2005-01-01

    Terrestrial plants experience multiple stresses when they are submerged, caused both by oxygen deficiency due to reduced gas diffusion in water, and by shade due to high turbidity of the floodwater. It has been suggested that responses to submergence are de facto responses to low light intensity. •

  12. Contrasting Changes Caused by Drought and Submergence Stresses in Bermudagrass (Cynodon dactylon)

    Science.gov (United States)

    Ye, Tiantian; Shi, Haitao; Wang, Yanping; Chan, Zhulong

    2015-01-01

    In this study, we investigated the mechanisms by which bermudagrass withstands the drought and submergence stresses through physiological, proteomic and metabolomic approaches. The results showed that significant physiological changes were observed after drought treatment, while only slight changes after submergence treatment, including compatible solute contents, ROS levels and antioxidant enzyme activities. Proteomics results showed that 81 proteins regulated by drought or submergence treatment were identified by MALDI-TOF-MS. Among them, 76 proteins were modulated by drought stress with 46 increased abundance and 30 decreased abundance. Forty-five showed abundance changes after submergence treatment with 10 increased and 35 decreased. Pathway enrichment analysis revealed that pathways of amino acid metabolism and mitochondrial electron transport/ATP synthesis were only enriched by drought treatment, while other pathways including photosynthesis, biodegradation of xenobiotics, oxidative pentose phosphate, glycolysis and redox were commonly over-represented after both drought and submergence treatments. Metabolomic analysis indicated that most of the metabolites were up-regulated by drought stress, while 34 of 40 metabolites contents exhibited down-regulation or no significant changes when exposed to submergence stress, including sugars and sugar alcohols. These data indicated that drought stress extensively promoted photosynthesis and redox metabolisms while submergence stress caused declined metabolisms and dormancy in Cynodon dactylon. Taken together, the quiescence strategy with retarded growth might allow bermudagrass to be adaptive to long-term submerged environment, while activation of photosynthesis and redox, and accumulation of compatible solutes and molecular chaperones increased bermudagrass tolerance to drought stress. PMID:26617615

  13. Architectural Surfaces and Structures from Circular Arcs

    KAUST Repository

    Shi, Ling

    2013-01-01

    the most attention from geometry researchers. In this thesis, we aim to realize this process with simple geometric primitives, circular arcs. We investigate architectural surfaces and structures consisting of circular arcs. Our focus is lying on how

  14. Heat transfer study of a submerged reactor channel under boil-off condition

    Energy Technology Data Exchange (ETDEWEB)

    Mukhopadhyay, Deb [Bhabha Atomic Research Centre, Mumbai (India). Reactor Safety Div.; Sahoo, P.K. [Indian Institute of Technology, Roorkee (India). Dept. of Mechanical and Industrial Engineering; Ghosh, A.K. [Bhabha Atomic Research Centre, Mumbai (India). Health, Safety and Environment Group

    2012-12-15

    Experiments have been carried out to study the heatup behavior of a single segmented reactor channel for Pressurized Heavy Water Reactor under submerged, partially submerged and exposed conditions. This situation may arise from a severe accident scenario of Pressurised Heavy Water Reactors where full or segmented reactor channels are likely to be disassembled and form a submerged debris bed. An assembly of electrical heater rod, simulating fuel bundle and channel components like Pressure Tube and Calandria Tube constitutes the segmented reactor channel. Heatup of this assembly is observed with respect to different water levels ranging from full submergence to totally exposed and power levels of 6-8 kW, typical to decay power level. It has been observed from the set of experiment that fuel bundle local dry out followed by heatup does not happen till the bundle is partially submerged. Temperature excursion of the bundle is evident when the bundle is exposed to steam-air environment. (orig.)

  15. [Effects of light on submerged macrophytes in eutrophic water: research progress].

    Science.gov (United States)

    Li-Sha, Zou; Ze-Yu, Nie; Xiao-Yan, Yao; Ji-Yan, Shi

    2013-07-01

    The restoration of submerged macrophytes is the key to remediate eutrophic water and maintain the health of aquatic ecosystem, while light is the main limiting factor. This paper summarized the factors affecting the light extinction in water and the mechanisms of light intensity affecting the physiology of submerged macrophytes, with the focuses on the metabolic mechanisms of carbon, nitrogen, and phosphorus, the responses of antioxidant enzyme system, and the feedbacks of pigment composition and concentration in the common submerged macrophytes under low light stress. Several engineering techniques applied in the ecological restoration of submerged macrophytes were presented, and the framework of the restoration of submerged macrophytes in eutrophic water was proposed. Some problems in current research and several suggestions on future research were addressed, which could help the related research and engineering practices.

  16. THE STUDY ON THE DURABILITY OF SUBMERGED STRUCTURE DISPLACEMENT DUE TO CONCRETE FAILURE

    Directory of Open Access Journals (Sweden)

    M. Mohd

    2016-09-01

    Full Text Available Concrete structures that exposed to marine environments are subjected to multiple deterioration mechanisms. An overview of the existing technology for submerged concrete, pressure resistant, concrete structures which related such as cracks, debonds, and delamination are discussed. Basic knowledge related to drowning durability such as submerged concrete structures in the maritime environment are the durability of a concrete and the ability to resist to weathering, chemical attack, abrasion or other deterioration processes. The measuring techniques and instrumentation for geometrical monitoring of submerged structural displacements have traditionally been categorized into two groups according to the two main groups, namely as geodetic surveying and geotechnical structural measurements of local displacements. This paper aims to study the durability of submerged concrete displacement and harmful effects of submerged concrete structures.

  17. A rotating arc plasma invertor

    International Nuclear Information System (INIS)

    Reusch, M.F.; Jayaram, K.

    1987-02-01

    A device is described for the inversion of direct current to alternating current. The main feature is the use of a rotating plasma arc in crossed electric and magnetic fields as a switch. This device may provide an economic alternative to other inversion methods in some circumstances

  18. Study of gliding arc discharge plasma

    International Nuclear Information System (INIS)

    Yang Chi; Lin Lie; Wu Bin

    2006-01-01

    The electric parameters change during discharge is studied and the relationship between non-equilibrium degree and parameters is discussed for gliding arc discharges. Using two-channel model, the rules of arc moving due to effect of the airflow is simulated. The numerical simulation results can help analyzing the generation mechanism of gliding arc non-equilibrium plasma. (authors)

  19. Rapid arc - clinical rationale and results

    International Nuclear Information System (INIS)

    Cozzi, Lucca

    2008-01-01

    The presentation will focus on the background of Intensity modulation volumetric arc therapy Rapid Arc from Varian Medical Systems aiming to highlight the technical and clinical rational also from an historical perspective to the founding pillars of fast delivery with a minimum number of arcs and a minimum number of monitor units

  20. STRUVE arc and EUPOS® stations

    Science.gov (United States)

    Lasmane, Ieva; Kaminskis, Janis; Balodis, Janis; Haritonova, Diana

    2013-04-01

    The Struve Geodetic Arc was developed in Years 1816 to 1855, 200 years ago. Historic information on the points of the Struve Geodetic Arc are included in the UNESCO World Heritage list in 2005. Nevertheless, the sites of many points are still not identified nor included in the data bases nowadays. Originally STRUVE arc consisted of 258 main triangles with 265 triangulation points. Currently 34 of the original station points are identified and included in the in the UNESCO World Heritage list. identified original measurement points of the Meridian Arc are located in Sweden (7 points), Norway (15), Finland (83), Russia (1), Estonia (22), Latvia (16), Lithuania (18), Belorussia (28), Ukraine (59) and Moldova (27). In Year 2002 was initiated another large coverage project - European Position Determination System "EUPOS®". Currently there are about 400 continuously operating GNSS (Global Navigation Satellite Systems) stations covering EU countries Estonia, Latvia, Lithuania, Poland, Czech Republic, Slovakia, Hungary, Bulgaria, Romania and East European countries Ukraine and Moldavia. EUPOS® network is a ground based GNSS augmentation system widely used for geodesy, land surveying, geophysics and navigation. It gives the opportunity for fast and accurate position determination never available before. It is an honorable task to use the EUPOS® system for research of the Struve triangulation former sites. Projects with Struve arc can popularize geodesy, geo-information and its meaning in nowadays GIS and GNSS systems. Struve Arc and its points is unique cooperation cross-border object which deserve special attention because of their natural beauty and historical value for mankind. GNSS in geodesy discovers a powerful tool for the verification and validation of the height values of geodetic leveling benchmarks established historically almost 200 years ago. The differential GNSS and RTK methods appear very useful to identify vertical displacement of landscape by means of

  1. Influence of arc current and pressure on non-chemical equilibrium air arc behavior

    Science.gov (United States)

    Yi, WU; Yufei, CUI; Jiawei, DUAN; Hao, SUN; Chunlin, WANG; Chunping, NIU

    2018-01-01

    The influence of arc current and pressure on the non-chemical equilibrium (non-CE) air arc behavior of a nozzle structure was investigated based on the self-consistent non-chemical equilibrium model. The arc behavior during both the arc burning and arc decay phases were discussed at different currents and different pressures. We also devised the concept of a non-equilibrium parameter for a better understanding of non-CE effects. During the arc burning phase, the increasing current leads to a decrease of the non-equilibrium parameter of the particles in the arc core, while the increasing pressure leads to an increase of the non-equilibrium parameter of the particles in the arc core. During the arc decay phase, the non-CE effect will decrease by increasing the arc burning current and the nozzle pressure. Three factors together—convection, diffusion and chemical reactions—influence non-CE behavior.

  2. Silica-enriched mantle sources of subalkaline picrite-boninite-andesite island arc magmas

    Science.gov (United States)

    Bénard, A.; Arculus, R. J.; Nebel, O.; Ionov, D. A.; McAlpine, S. R. B.

    2017-02-01

    Primary arc melts may form through fluxed or adiabatic decompression melting in the mantle wedge, or via a combination of both processes. Major limitations to our understanding of the formation of primary arc melts stem from the fact that most arc lavas are aggregated blends of individual magma batches, further modified by differentiation processes in the sub-arc mantle lithosphere and overlying crust. Primary melt generation is thus masked by these types of second-stage processes. Magma-hosted peridotites sampled as xenoliths in subduction zone magmas are possible remnants of sub-arc mantle and magma generation processes, but are rarely sampled in active arcs. Published studies have emphasised the predominantly harzburgitic lithologies with particularly high modal orthopyroxene in these xenoliths; the former characteristic reflects the refractory nature of these materials consequent to extensive melt depletion of a lherzolitic protolith whereas the latter feature requires additional explanation. Here we present major and minor element data for pristine, mantle-derived, lava-hosted spinel-bearing harzburgite and dunite xenoliths and associated primitive melts from the active Kamchatka and Bismarck arcs. We show that these peridotite suites, and other mantle xenoliths sampled in circum-Pacific arcs, are a distinctive peridotite type not found in other tectonic settings, and are melting residues from hydrous melting of silica-enriched mantle sources. We explore the ability of experimental studies allied with mantle melting parameterisations (pMELTS, Petrolog3) to reproduce the compositions of these arc peridotites, and present a protolith ('hybrid mantle wedge') composition that satisfies the available constraints. The composition of peridotite xenoliths recovered from erupted arc magmas plausibly requires their formation initially via interaction of slab-derived components with refractory mantle prior to or during the formation of primary arc melts. The liquid

  3. Mixing Characteristics during Fuel Coolant Interaction under Reactor Submerged Conditions

    International Nuclear Information System (INIS)

    Hong, S. W.; Na, Y. S.; Hong, S. H.; Song, J. H.

    2014-01-01

    A molten material is injected into an interaction chamber by free gravitation fall. This type of fuel coolant interaction could happen to operating plants. However, the flooding of a reactor cavity is considered as SAM measures for new PWRs such as APR-1400 and AP1000 to assure the IVR of a core melt. In this case, a molten corium in a reactor is directly injected into water surrounding the reactor vessel without a free fall. KAERI has carried out fuel coolant interaction tests without a free fall using ZrO 2 and corium to simulate the reactor submerged conditions. There are four phases in a steam explosion. The first phase is a premixing phase. The premixing is described in the literature as follows: during penetration of melt into water, hydrodynamic instabilities, generated by the velocities and density differences as well as vapor production, induce fragmentation of the melt into particles; the particles fragment in turn into smaller particles until they reach a critical size such that the cohesive forces (surface tension) balance exactly the disruptive forces (inertial); and the molten core material temperature (>2500 K) is such that the mixing always occurs in the film boiling regime of the water: It is very important to qualify and quantify this phase because it gives the initial conditions for a steam explosion This paper mainly focuses on the observation of the premixing phase between a case with 1 m free fall and a case without a free fall to simulate submerged reactor condition. The premixing behavior between a 1m free fall case and reactor case submerged without a free fall is observed experimentally. The average velocity of the melt front passing through 1m water pool; - Case without a free fall: The average velocity of corium, 2.7m/s, is faster than ZrO 2 , 2.3m/s, in water. - Cases of with a 1 m free fall and without a free fall : The case without a free fall is about two times faster than a case with a 1 m free fall. Bubble characteristics; - Case

  4. Submerged cutting of steel by abrasive water jets

    International Nuclear Information System (INIS)

    Haferkamp, H.; Louis, H.; Meier, G.

    1990-01-01

    A special cutting head for underwater use was designed and built. Tests were carried out to find out useful parameters for submerged cutting. With regard to the production of secondary waste the abrasive flow rate had to be minimized. This was achieved by using a small water jet nozzle (up to 0.4 mm diameter) and a high pressure (up to 4000 bar) with an optimal abrasive flow rate of about 5 g/s. In the case of a higher ambient pressure a decrease of the cutting performance was measured. But this decrease is not important regarding decommissioning because the ambient pressure is less than 2 bar. An air mantle nozzle was adapted to the cutting head to improve the working distance under water. The air mantle surrounding the abrasive jet lowers the friction between jet and surrounding water and increases the cutting efficiency in the case of greater working distances. (author)

  5. Microbial production of four biodegradable siderophores under submerged fermentation.

    Science.gov (United States)

    Fazary, Ahmed E; Al-Shihri, Ayed S; Alfaifi, Mohammad Y; Saleh, Kamel A; Alshehri, Mohammed A; Elbehairi, Serag Eldin I; Ju, Yi-Hsu

    2016-07-01

    Four siderophore analogues were isolated and purified from Escherichia coli, Bacillus spp. ST13, and Streptomyces pilosus microorganisms under some specific submerged fermentation conditions. In order to evaluate the highest production of this siderophore analogues through the growth, a rapid spectrophotometric screening semi-quantitative method was used, in which interestingly the analogues were isolated in its own form not its iron chelate. After chromatographic separation, the chemical structures of the isolated and purified siderophores were illustrated using detailed spectroscopic techniques. The biodegradation studies were done on that four novel isolated and purified siderophores following OECD protocols. In addition, the bioactivities of these siderophores and their iron complexes were examined and evaluated. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Use of the submerged demineralizer system at Three Mile Island

    International Nuclear Information System (INIS)

    Hofstetter, K.J.; Hitz, C.G.

    1983-01-01

    The Submerged Demineralizer System (SDS) has been used at Three Mile Island-Unit 2 (TMI-2) to process more than 1.5 million gallons of water contaminated as a result of the March, 1979 accident. The SDS has processed approximately 315,000 gallons of water accumulated in tanks in the Auxiliary Building, approximately 650,000 gallons of water that existed in the Reactor Containment Building basement, approximately 90,000 gallons of primary reactor coolant (processed in a bleed and feed mode) and approximately 169,000 gallons of water used in the large scale decontamination of the Reactor Building. During its operation, the SDS has immobilized approximately 340,000 curies of the principal fission products 137 Cs, 134 Cs and 90 Sr on inorganic media (zeolite). Processing summaries and performance evaluations are presented. 12 references, 1 figure, 6 tables

  7. Endodontic Treatment in Submerged Roots: A Case Report

    Directory of Open Access Journals (Sweden)

    Hemalatha Pameshwar Hiremath

    2010-06-01

    Full Text Available Alveolar ridge resorption has long been considered an unavoidable consequence of tooth extraction. While the extent and pattern of resorption is variable among individuals, there is a progressive loss of ridge contour as a result of physiologic bone remodeling. Even today, with best modalities of tooth preservation, there is a group of elderly individuals who do not benefit from modern preventive practices and who now present a dilemma in terms of maintaining the masticatory apparatus necessary for nutrition. Even with excellent dental care, such patients experience abrasion of the natural tooth crowns with age, and embedded roots are left within the alveolar bone. According to old concepts of dental care, extraction of these roots would have been recommended, but today’s goal of excellence in endodontics dictates otherwise. We report a case in which vital and non-vital root submergence was carried out to prevent alveolar ridge reduction.

  8. Three-Dimensional Flow Behavior Inside the Submerged Entry Nozzle

    Science.gov (United States)

    Real-Ramirez, Cesar Augusto; Carvajal-Mariscal, Ignacio; Sanchez-Silva, Florencio; Cervantes-de-la-Torre, Francisco; Diaz-Montes, Jesus; Gonzalez-Trejo, Jesus

    2018-05-01

    According to various authors, the surface quality of steel depends on the dynamic conditions that occur within the continuous casting mold's upper region. The meniscus, found in that upper region, is where the solidification process begins. The liquid steel is distributed into the mold through a submerged entry nozzle (SEN). In this paper, the dynamic behavior inside the SEN is analyzed by means of physical experiments and numerical simulations. The particle imaging velocimetry technique was used to obtain the vector field in different planes and three-dimensional flow patterns inside the SEN volume. Moreover, large eddy simulation was performed, and the turbulence model results were used to understand the nonlinear flow pattern inside the SEN. Using scaled physical and numerical models, quasi-periodic behavior was observed due to the interaction of two three-dimensional vortices that move inside the SEN lower region located between the exit ports of the nozzle.

  9. Comparison of submerged and unsubmerged printing of ovarian cancer cells.

    Science.gov (United States)

    Davidoff, Sherry N; Au, David; Smith, Samuel; Brooks, Amanda E; Brooks, Benjamin D

    2015-01-01

    A high-throughput cell based assay would greatly aid in the development and screening of ovarian cancer drug candidates. Previously, a three-dimensional microfluidic printer that is not only capable of controlling the location of cell deposition, but also of maintaining a liquid, nutrient rich environment to preserve cellular phenotype has been developed (Wasatch Microfluidics). In this study, we investigated the impact (i.e., viability, density, and phenotype) of depositing cells on a surface submerged in cell culture media. It was determined that submersion of the microfluidic print head in cell media did not alter the cell density, viability, or phenotype.. This article describes an in depth study detailing the impact of one of the fundamental components of a 3D microfluidic cell printer designed to mimic the in vivo cell environment. Development of such a tool holds promise as a high-throughput drug-screening platform for new cancer therapeutics.

  10. Growth Control of Cyanobacteria by Three Submerged Macrophytes

    Science.gov (United States)

    Wang, Haiou; Zhong, Guangrong; Yan, Hai; Liu, Hu; Wang, Yao; Zhang, Chun

    2012-01-01

    Abstract To illustrate the control of harmful cyanobacterial growth and the removal of nutritients from fresh water, three submerged macrophytes were grown in the raw water of Guishui Lake. Lindernia rotundifolia, Hygrophila stricta, and Cryptocoryne crispatula were grown together in situ to assess their effectiveness in nutrient removal in microcosms. Results revealed the inhibitory effects of these species on cyanobacterial growth. In addition, water quality in the planted microcosms showed improvement when compared to the water quality of the unplanted microcosm. At all treatments studied, the chemical oxygen demand in the planted microcosms was lower than that in the unplanted microcosms, and the removal rate of all the nitrogen and phosphate in the planted microcosms was better than that of the microcosm without plants. Our study offers a useful algal control method for the lakes or reservoirs that suffer from harmful cyanobacterial blooms. PMID:22693412

  11. Phytoremediation of arsenic in submerged soil by wetland plants.

    Science.gov (United States)

    Jomjun, Nateewattana; Siripen, Trichaiyaporn; Maliwan, Saeouy; Jintapat, Nateewattana; Prasak, Thavornyutikarn; Somporn, Choonluchanon; Petch, Pengchai

    2011-01-01

    Wetland aquatic plants including Canna glauca L., Colocasia esculenta L. Schott, Cyperus papyrus L. and Typha angustifolia L. were used in the phytoremediation of submerged soil polluted by arsenic (As). Cyperus papyrus L. was noticed as the largest biomass producer which has arsenic accumulation capacity of 130-172 mg As/kg plant. In terms of arsenic removal rate, however, Colocasia esculenta L. was recognized as the largest and fastest arsenic remover in this study. Its arsenic removal rate was 68 mg As/m2/day while those rates of Canna glauca L., Cyperus papyrus L. and Typha angustifolia L. were 61 mg As/m2/day, 56 mg As/m2/day, and 56 mg As/m2/day, respectively. Although the 4 aquatic plants were inferior in arsenic accumulation, their high arsenic removal rates were observed. Phytostabilization should be probable for the application of these plants.

  12. Microstructural Study on Oxygen Permeated Arc Beads

    Directory of Open Access Journals (Sweden)

    Kuan-Heng Liu

    2015-01-01

    Full Text Available We simulated short circuit of loaded copper wire at ambient atmosphere and successfully identified various phases of the arc bead. A cuprous oxide flake was formed on the surface of the arc bead in the rapid solidification process, and there were two microstructural constituents, namely, Cu-κ eutectic structure and solutal dendrites. Due to the arc bead formed at atmosphere during the local equilibrium solidification process, the phase of arc bead has segregated to the cuprous oxide flake, Cu-κ eutectic, and Cu phase solutal dendrites, which are the fingerprints of the arc bead permeated by oxygen.

  13. Safe shutdown analysis for submerged equipment inside containment

    International Nuclear Information System (INIS)

    Song, Dong Soo; Lee, Seung Chan; Yoon, Duk Joo; Ha, Sang Jun

    2017-01-01

    The purpose of the paper is to analyze internal flooding effects on the submerged safety-related components inside containment building. Safe shutdown analysis has been performed based on the criteria, assumptions and guideline provided in ANSI/ANS-56.11-1988 and ANSI/ANS-58.11-1988. Flooding can be postulated from a failure of several systems located inside the containment. Loss of coolant accident (LOCA), Feed water line break (FWLB), and other pipe breaks/cracks are assumed. The worst case flooding scenario is a large break LOCA. The maximum flood level for a large break LOCA is calculated based on the combined inventory of the reactor coolant system, the three accumulators, the boron injection tank (BIT), the chemical additive tank (CAT), and the refueling water storage tank (RWST) flooding the containment. The maximum flood level that could occur from all of the water which is available in containment is 2.3 m from the base elevation. A detailed flooding analysis for the components has been performed to demonstrate that internal flooding resulting from a postulated initiating event does not cause the loss of equipment required to achieve and maintain safe shutdown of the plant, emergency core cooling capability, or equipment whose failure could result in unacceptable offsite radiological consequences. The flood height can be calculated as h = (dh/dt) x (t-t 0 ) + h 0 , where h = time dependent flood height and subscript 0 means the initial value and height slope dh/dt. In summary, the submerged components inside containment are acceptable because they complete the mission of safety injection (SI) prior to submeregency or have no safe shutdown function including containment isolation during an accident. (author)

  14. Photosynthetic carbon metabolism in the submerged aquatic angiosperm Scirpus subterminalis

    Energy Technology Data Exchange (ETDEWEB)

    Beer, S; Wetzel, R G

    1981-01-01

    Scirpus subterminalis Torr., a submerged angiosperm abundant in many hardwater lakes of the Great Lakes region, was investigated for various photosynthetic carbon fixation properties in relation to available inorganic carbon and levels of carbon fixing enzymes. Photosynthetic experiments were CO/sub 2/ and HCO/sub 3//sup -/ were supplied at various concentrations showed that Scirpus was able to utilize HCO/sub 3//sup -/ at those concentrations close to natural conditions. However, when CO/sub 2/ concentrations were increased above ambient, photosynthetic rates increased markedly. It was concluded that the photosynthetic potential of this plant in many natural situations may be limited by inorganic carbon uptake in the light. Phosphoenolpyruvate carboxylase (PEPcase)/ribulose-1,5-bisphosphate carboxylase (ruBPcase) ratios of the leaves varied between 0.5 and 0.9 depending on substrate concentration during assay. The significance of PEP-mediated carbon fixation of Scirpus (basically a C/sub 3/ plant) in the dark was investigated. Malate accumulated in the leaves during the dark period of a 24-h cycle and malate levels decreased significantly during the following light period. The accumulation was not due to transport of malate from the roots. Carbon uptake rates in the dark by the leaves of Scirpus were lower than malate accumulation rates. Therefore, part of the malate was likely derived from respired CO/sub 2/. Carbon uptake rates in the light were much higher than malate turnover rates. It was estimated that carbon fixation via malate could contribute up to 12% to net photosynthetic rates. The ecological significance of this type of metabolism in submerged aquatics is discussed.

  15. Development of New Submergence Tolerant Rice Variety for Bangladesh Using Marker-Assisted Backcrossing

    Directory of Open Access Journals (Sweden)

    Khandakar Md Iftekharuddaula

    2015-01-01

    Full Text Available Submergence tolerant high yielding rice variety was developed using BR11 as a recipient parent applying foreground, phenotypic and background selection approaches. Recombinant selection was found essential to minimize linkage drag by BC2F2 generation. Without recombinant selection, the introgression size in the backcross recombinant lines (BRLs was approximately 15 Mb on the carrier chromosome. The BRLs were found submergence tolerance compared to the check varieties under complete submergence for two weeks at Bangladesh Rice Research Institute, and produced higher yield compared to the isogenic Sub1-line under controlled submerged condition. The BRL IR85260-66-654-Gaz2 was released as BRRI dhan52 in 2010, which was the first high yielding submergence tolerant variety in Bangladesh. BRRI dhan52 produced grain yield ranging from 4.2 to 5.2 t/hm2 under different flash flood prone areas of Bangladesh in three consecutive seasons. The study demonstrated the efficiency of recombinant selection and better adaptability of the newly released submergence tolerant high yielding variety in flash flood prone different areas of the country with respect to submergence tolerance and yield potential.

  16. Antioxidant activity of seedling growth in selected soybean genotypes (Glycine max (L.) Merrill) responses of submergence

    Science.gov (United States)

    Damanik, R. I.; Marbun, P.; Sihombing, L.

    2016-08-01

    In order to better understand the physiological and biochemical responses relating to direct seeding establishment in soybeans, the plant growth rate and antioxidative defense responses of seedlings in seven Indonesian soybean genotypes (Anjasmoro, Detam-1, Detam-2, Dieng, Grobogan, Tanggamus, and Willis) at different submergence periods (4, and 8 days) were examined. Twelve-day old seedlings were hydroponically grown in limited oxygen conditions. The results showed that the chlorophyll content in soybean seedlings was reduced beginning as early as 4 d under submerged condition, except for Detam-1, Detam-2, and Grobogan genotypes. The dry weight and protein concentration of seedlings were significantly higher at control condition (0 d) than those in submerged condition. The activities of superoxide dismutase (SOD) increased linearly until 8 d submerged for all genotypes. On the other hand, our results showed that catalase (CAT) and ascorbate peroxidase (APX) activities did not work together, meaning that CAT is activated and APX deactivated, or vice versa, in response to submergence conditions, except for Grobogan and Tanggamus genotypes which had an effect on both CAT and APX activities. Submergence stress led to a significant increase in glutathione reductase (GR) together with APX activity for Detam-2 and Dieng genotypes at 8 d submerged.

  17. The Performance and Fouling Control of Submerged Hollow Fiber (HF Systems: A Review

    Directory of Open Access Journals (Sweden)

    Ebrahim Akhondi

    2017-07-01

    Full Text Available The submerged membrane filtration concept is well-established for low-pressure microfiltration (MF and ultrafiltration (UF applications in the water industry, and has become a mainstream technology for surface-water treatment, pretreatment prior to reverse osmosis (RO, and membrane bioreactors (MBRs. Compared to submerged flat sheet (FS membranes, submerged hollow fiber (HF membranes are more common due to their advantages of higher packing density, the ability to induce movement by mechanisms such as bubbling, and the feasibility of backwashing. In view of the importance of submerged HF processes, this review aims to provide a comprehensive landscape of the current state-of-the-art systems, to serve as a guide for further improvements in submerged HF membranes and their applications. The topics covered include recent developments in submerged hollow fiber membrane systems, the challenges and developments in fouling-control methods, and treatment protocols for membrane permeability recovery. The highlighted research opportunities include optimizing the various means to manipulate the hydrodynamics for fouling mitigation, developing online monitoring devices, and extending the submerged HF concept beyond filtration.

  18. Submergence sensitivity of durum wheat, bread wheat and barley at the germination stage

    Directory of Open Access Journals (Sweden)

    Iduna Arduini

    2016-06-01

    Full Text Available Soil waterlogging at initial growth stages can cause heavy yield losses of winter cereals. Therefore, the screening for submergence tolerance traits in seeds of commercial varieties is of high concern worldwide. Ten Italian varieties of durum wheat (Triticum durum Desf., bread wheat (T. aestivum L. and barley (Hordeum vulgare L. were investigated for their ability to germinate in submerged conditions and to recover after submergence periods of three to 15 days. Submergence prevented germination and decreased germinability, at rates that increased with duration of submergence. Sensitivity ranked in the order: barley >durum wheat >bread wheat. We related the higher sensitivity of barley to its slower germination and slightly higher leakage of electrolytes, whereas the percentage of abnormal seedlings was lower than in other species. It was less than 4%, compared to less than 15 and 8% in durum wheat and bread wheat, respectively. Wide varietal differences were found in all species. According to variety, after 6-day submergence, germinability ranged from 2 to 42% in barley, from 5 to 80% in durum wheat, and from 30 to 77% in bread wheat. Varieties with more than 40% seed survival were three, six and seven per species, in the same order. The differential submergence sensitivity of varieties indicates a potential to select for waterlogging tolerance within Italian genotypes of winter cereal crops.

  19. Magnetic-flux pump

    Science.gov (United States)

    Hildebrandt, A. F.; Elleman, D. D.; Whitmore, F. C. (Inventor)

    1966-01-01

    A magnetic flux pump is described for increasing the intensity of a magnetic field by transferring flux from one location to the magnetic field. The device includes a pair of communicating cavities formed in a block of superconducting material, and a piston for displacing the trapped magnetic flux into the secondary cavity producing a field having an intense flux density.

  20. Radon flux measurement methodologies

    International Nuclear Information System (INIS)

    Nielson, K.K.; Rogers, V.C.

    1984-01-01

    Five methods for measuring radon fluxes are evaluated: the accumulator can, a small charcoal sampler, a large-area charcoal sampler, the ''Big Louie'' charcoal sampler, and the charcoal tent sampler. An experimental comparison of the five flux measurement techniques was also conducted. Excellent agreement was obtained between the measured radon fluxes and fluxes predicted from radium and emanation measurements

  1. Effects of an anode sheath on energy and momentum transfer in vacuum arcs

    International Nuclear Information System (INIS)

    Wang, Zhenxing; Zhou, Zhipeng; Tian, Yunbo; Wang, Haoran; Wang, Jianhua; Geng, Yingsan; Liu, Zhiyuan

    2017-01-01

    Anode phenomena under high-current vacuum arcs have a significant impact on the interrupting capacity of vacuum interrupters. However, the vacuum arc energy flux and momentum flux on the anode—which are necessary boundary conditions for simulations—are either set to an imaginary distribution or calculated using simple formulas without considering anode sheath regulatory effects. The objective of this paper is to reveal the anode sheath effects on regulating the energy and momentum transfer from the arc column to the anode surface in vacuum arcs. A particle-in-cell model for the anode sheath is developed. The required input parameters are obtained from a magnetohydrodynamic model for the arc column. From the results, there exists a sheath near the anode with a negative voltage drop. Both the electron density and the ion density significantly decline in the anode sheath region. The kinetic energy of the ions absorbed by the anode consists of directed kinetic energy, random kinetic energy, and sheath acceleration energy. The sheath acceleration energy contribution is the largest, and the random kinetic energy also accounts for a large part that cannot be ignored. The arc pressure on the anode surface is mainly caused by ion impact, and the accelerating effect of the anode sheath on the ions cannot be neglected in pressure calculations. In addition, in the case of an arc current at 15 kA, the input energy and momentum upon the anode surface is not obviously affected by the evaporated atoms at surface temperatures of 1600 K and 2000 K. (paper)

  2. High current vacuum arc ion source for heavy ion fusion

    International Nuclear Information System (INIS)

    Qi, N.; Schein, J.; Gensler, S.; Prasad, R.R.; Krishnan, M.; Brown, I.

    1999-01-01

    Heavy Ion fusion (HIF) is one of the approaches for the controlled thermonuclear power production. A source of heavy ions with charge states 1+ to 2+, in ∼0.5 A current beams with ∼20 micros pulse widths and ∼10 Hz repetition rates are required. Thermionic sources have been the workhorse for the HIF program to date, but suffer from sloe turn-on, heating problems for large areas, are limited to low (contact) ionization potential elements and offer relatively low ion fluxes with a charge state limited to 1+. Gas injection sources suffer from partial ionization and deleterious neutral gas effects. The above shortcomings of the thermionic ion sources can be overcome by a vacuum arc ion source. The vacuum arc ion source is a good candidate for HIF applications. It is capable of providing ions of various elements and different charge states, in short and long pulse bursts, with low emittance and high beam currents. Under a Phase-I STTR from DOE, the feasibility of the vacuum arc ion source for the HIF applications is investigated. An existing ion source at LBNL was modified to produce ∼0.5 A, ∼60 keV Gd (A∼158) ion beams. The experimental effort concentrated on beam noise reduction, pulse-to-pulse reproducibility and achieving low beam emittance at 0.5 A ion current level. Details of the source development will be reported

  3. A New Sulfur and Carbon Degassing Inventory for the Southern Central American Volcanic Arc: The Importance of Accurate Time-Series Data Sets and Possible Tectonic Processes Responsible for Temporal Variations in Arc-Scale Volatile Emissions

    Science.gov (United States)

    de Moor, J. M.; Kern, C.; Avard, G.; Muller, C.; Aiuppa, A.; Saballos, A.; Ibarra, M.; LaFemina, P.; Protti, M.; Fischer, T. P.

    2017-12-01

    This work presents a new database of SO2 and CO2 fluxes from the Southern Central American Volcanic Arc (SCAVA) for the period 2015-2016. We report ˜300 SO2 flux measurements from 10 volcanoes and gas ratios from 11 volcanoes in Costa Rica and Nicaragua representing the most extensive available assessment of this ˜500 km arc segment. The SO2 flux from SCAVA is estimated at 6,240 ± 1,150 T/d, about a factor of three higher than previous estimations (1972-2013). We attribute this increase in part to our more complete assessment of the arc. Another consideration in interpreting the difference is the context of increased volcanic activity, as there were more eruptions in 2015-2016 than in any period since ˜1980. A potential explanation for increased degassing and volcanic activity is a change in crustal stress regime (from compression to extension, opening volcanic conduits) following two large (Mw > 7) earthquakes in the region in 2012. The CO2 flux from the arc is estimated at 22,500 ± 4,900 T/d, which is equal to or greater than estimates of C input into the SCAVA subduction zone. Time-series data sets for arc degassing need to be improved in temporal and spatial coverage to robustly constrain volatile budgets and tectonic controls. Arc volatile budgets are strongly influenced by short-lived degassing events and arc systems likely display significant short-term variations in volatile output, calling for expansion of nascent geochemical monitoring networks to achieve spatial and temporal coverage similar to traditional geophysical networks.

  4. A new sulfur and carbon degassing inventory for the Southern Central American Volcanic Arc: The importance of accurate time-series datasets and possible tectonic processes responsible for temporal variations in arc-scale volatile emissions

    Science.gov (United States)

    de Moor, Maarten; Kern, Christoph; Avard, Geoffroy; Muller, Cyril; Aiuppa, Sandro; Saballos, Armando; Ibarra, Martha; LaFemina, Peter; Protti, Mario; Fischer, Tobias

    2017-01-01

    This work presents a new database of SO2 and CO2 fluxes from the Southern Central American Volcanic Arc (SCAVA) for the period 2015–2016. We report ∼300 SO2 flux measurements from 10 volcanoes and gas ratios from 11 volcanoes in Costa Rica and Nicaragua representing the most extensive available assessment of this ∼500 km arc segment. The SO2 flux from SCAVA is estimated at 6,240 ± 1,150 T/d, about a factor of three higher than previous estimations (1972–2013). We attribute this increase in part to our more complete assessment of the arc. Another consideration in interpreting the difference is the context of increased volcanic activity, as there were more eruptions in 2015–2016 than in any period since ∼1980. A potential explanation for increased degassing and volcanic activity is a change in crustal stress regime (from compression to extension, opening volcanic conduits) following two large (Mw > 7) earthquakes in the region in 2012. The CO2 flux from the arc is estimated at 22,500 ± 4,900 T/d, which is equal to or greater than estimates of C input into the SCAVA subduction zone. Time‐series data sets for arc degassing need to be improved in temporal and spatial coverage to robustly constrain volatile budgets and tectonic controls. Arc volatile budgets are strongly influenced by short‐lived degassing events and arc systems likely display significant short‐term variations in volatile output, calling for expansion of nascent geochemical monitoring networks to achieve spatial and temporal coverage similar to traditional geophysical networks.

  5. ATLAS DDM integration in ARC

    DEFF Research Database (Denmark)

    Behrmann, Gerd; Cameron, David; Ellert, Mattias

    2008-01-01

    The Nordic Data Grid Facility (NDGF) consists of Grid resources running ARC middleware in Denmark, Finland, Norway and Sweden. These resources serve many virtual organisations and contribute a large fraction of total worldwide resources for the ATLAS experiment, whose data is distributed and mana......The Nordic Data Grid Facility (NDGF) consists of Grid resources running ARC middleware in Denmark, Finland, Norway and Sweden. These resources serve many virtual organisations and contribute a large fraction of total worldwide resources for the ATLAS experiment, whose data is distributed...... and managed by the DQ2 software. Managing ATLAS data within NDGF and between NDGF and other Grids used by ATLAS (the Enabling Grids for E-sciencE Grid and the Open Science Grid) presents a unique challenge for several reasons. Firstly, the entry point for data, the Tier 1 centre, is physically distributed...

  6. Influence of sediment recycling on the trace element composition of primitive arc lavas

    Science.gov (United States)

    Collinet, M.; Jagoutz, O. E.

    2017-12-01

    Primitive calc-alkaline lavas from continental arcs are, on average, enriched in incompatible elements compared to those from intra-oceanic arcs. This relative enrichment is observed in different groups of trace elements: LILE (e.g. K, Rb), LREE to MREE (La-Dy) and HFSE (e.g.Zr, Nb) and is thought to result from (1) a transfer of material from the subducting slab to the mantle wedge at higher temperature than in intra-oceanic margins and/or (2) lower average degrees of melting in the mantle wedge, as a consequence of thicker overlying crusts and higher average pressures of melting. In addition to thicker overlying crusts and generally higher slab temperatures, continental margins are characterized by larger volumes of rock exposed above sea level and enhanced erosion rates compared to intra-oceanic arcs. As several geochemical signatures of arc lavas attest to the importance of sediment recycling in subduction zones, we explore the possibility that the high concentrations of incompatible elements in primitive lavas from continental arcs directly reflect a larger input of sediment to the subduction system. Previous efforts to quantify the sediment flux to oceanic trenches focused on the thickness of pelagic and hemipelagic sediments on top of the plate entering the subduction zone (Plank and Langmuir, 1993, Nature). These estimates primarily relied on the sediment layer drilled outboard from the subduction system and likely underestimate the volume of sediment derived from the arc itself. Accordingly, we find that such estimates of sediment flux do not correlate with the concentration of incompatible elements in primitive arc lavas. To account for regional contributions of coarser detrital sediments, usually delivered to oceanic trenches by turbidity currents, we apply to arc segments a model that quantifies the sediment load of rivers based on the average relief, area, temperature and runoff of their respective drainage areas (Syvitski et al., 2003, Sediment. Geol

  7. A scaling law for the local CHF on the external bottom side of a fully submerged reactor vessel

    International Nuclear Information System (INIS)

    Cheung, F.B.; Haddad, K.H.; Liu, Y.C.

    1997-01-01

    A scaling law for estimating the local critical heat flux on the outer surface of a heated hemispherical vessel that is fully submerged in water has been developed from the results of an advanced hydrodynamic CHF model for pool boiling on a downward facing curved heating surface. The scaling law accounts for the effects of the size of the vessel, the level of liquid subcooling, the intrinsic properties of the fluid, and the spatial variation of the local critical heat flux along the heating surface. It is found that for vessels with diameters considerably larger than the characteristic size of the vapor masses, the size effect on the local critical heat flux is limited almost entirely to the effect of subcooling associated with the local liquid head. When the subcooling effect is accounted for separately, the local CHF limit is nearly independent of the vessel size. Based upon the scaling law developed in this work, it is possible to merge, within the experimental uncertainties, all the available local CHF data obtained for various vessel sizes under both saturated and subcooled boiling conditions into a single curve. Applications of the scaling law to commercial-size vessels have been made for various system pressures and water levels above the heated vessel. Over the range of conditions explored in this study, the local CHF limit is found to increase by a factor of two or more from the bottom center to the upper edge of the vessel. Meanwhile, the critical heat flux at a given angular position of the heated vessel is also found to increase appreciably with the system pressure and the water level

  8. An ultrasonic method for separation of epiphytic microbes from freshwater submerged macrophytes.

    Science.gov (United States)

    Cai, Xianlei; Gao, Guang; Yang, Jing; Tang, Xiangming; Dai, Jiangyu; Chen, Dan; Song, Yuzhi

    2014-07-01

    Epiphytic microbes are common inhabitants of freshwater submerged macrophytes, which play an important role in aquatic ecosystems. An important precondition for studying the epiphytic microbes is having an effective method of separating the attached microbes from the host macrophytes. We developed an ultrasound-based method for separating epiphytic microbes from freshwater submerged macrophytes, optimized the conditions of ultrasonic separation with an orthogonal experimental design, and compared the optimized ultrasonic method with manual separation. This method can be particularly useful for freshwater submerged macrophytes having a complex morphology. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Erosion properties of unipolar arcs

    International Nuclear Information System (INIS)

    Chekalin, Eh.K.

    1982-01-01

    Processes modelling the formation of unipolar arcs on the elements of the first wall in limiters of the vacuum chamber and on active elements of tokamak divertor, are experimentally investigated. Erosion, processes that take place at two types of non-stationary cathode spots are considered. Experimental data prove the possibility of reducing erosion intensity by coating the surface of electrodes by oxide films, reduction of the temperature of electrode and discharge current

  10. Geochemical Variation of Subducting Pacific Crust Along the Izu-Bonin Arc System and its Implications on the Generation of Arc Magmas

    Science.gov (United States)

    Durkin, K.; Castillo, P.; Abe, N.; Kaneko, R.; Straub, S. M.; Garcia, E. S. M.; Yan, Q.; Tamura, Y.

    2015-12-01

    Subduction zone magmatism primarily occurs due to flux melting of the mantle wedge that has been metasomatized by the slab component. The latter is enriched in volatiles and fluid-mobile elements and derived mainly from subducted sediments and altered oceanic crust (AOC). Subduction input has been linked to arc output in many studies, but this relationship is especially well documented in sedimented arc-trench systems. However, the Izu-Bonin system is sediment-poor, therefore the compositional and latitudinal variations (especially in Pb isotopes) of its arc magmas must be sourced from the subduction component originating primarily from the AOC. Pb is a very good tracer of recycled AOC that may contribute 50% or more of arc magma Pb. Izu-Bonin arc chemistry suggests a subduction influx of Indian-type crust, but the subducting crust sampled at ODP Site 1149 is Pacific-type. The discrepancy between subduction input and arc output calls into question the importance of the AOC as a source of the subduction component, and raises major concerns with our understanding of slab input. During the R/V Revelle 1412 cruise in late 2014, we successfully dredged vertical fault scarps at several sites from 27.5 N to 34.5 N, spanning a range of crustal ages that include a suggested compositional change at ~125 Ma. Major element data show an alkali enrichment towards the north of the study transect. Preliminary incompatible trace element data (e.g. Ba, Zr and Sr) data support this enrichment trend. Detailed mass balance calculations supported by Sr, Nd, Hf and especially Pb isotope analyses will be performed to evaluate whether the AOC controls the Pb isotope chemistry of the Izu-Bonin volcanic arc.

  11. Slab melting and magma formation beneath the southern Cascade arc

    Science.gov (United States)

    Walowski, Kristina J.; Wallace, Paul J.; Clynne, Michael A.; Rasmussen, D.J.; Weis, D.

    2016-01-01

    The processes that drive magma formation beneath the Cascade arc and other warm-slab subduction zones have been debated because young oceanic crust is predicted to largely dehydrate beneath the forearc during subduction. In addition, geochemical variability along strike in the Cascades has led to contrasting interpretations about the role of volatiles in magma generation. Here, we focus on the Lassen segment of the Cascade arc, where previous work has demonstrated across-arc geochemical variations related to subduction enrichment, and H-isotope data suggest that H2O in basaltic magmas is derived from the final breakdown of chlorite in the mantle portion of the slab. We use naturally glassy, olivine-hosted melt inclusions (MI) from the tephra deposits of eight primitive (MgO>7 wt%) basaltic cinder cones to quantify the pre-eruptive volatile contents of mantle-derived melts in this region. The melt inclusions have B concentrations and isotope ratios that are similar to mid-ocean ridge basalt (MORB), suggesting extensive dehydration of the downgoing plate prior to reaching sub-arc depths and little input of slab-derived B into the mantle wedge. However, correlations of volatile and trace element ratios (H2O/Ce, Cl/Nb, Sr/Nd) in the melt inclusions demonstrate that geochemical variability is the result of variable addition of a hydrous subduction component to the mantle wedge. Furthermore, correlations between subduction component tracers and radiogenic isotope ratios show that the subduction component has less radiogenic Sr and Pb than the Lassen sub-arc mantle, which can be explained by melting of subducted Gorda MORB beneath the arc. Agreement between pMELTS melting models and melt inclusion volatile, major, and trace element data suggests that hydrous slab melt addition to the mantle wedge can produce the range in primitive compositions erupted in the Lassen region. Our results provide further evidence that chlorite-derived fluids from the mantle portion of the

  12. Effect of arc behaviour on the temperature fluctuation of carbon electrode in DC arc discharge

    International Nuclear Information System (INIS)

    Liang, F; Tanaka, M; Choi, S; Watanabe, T

    2014-01-01

    Diffuse and multiple arc-anode attachment modes were observed in a DC arc discharge with a carbon electrode. During the arc discharge, the surface temperature of the electrode was successfully measured by two-colour pyrometry combined with a high-speed camera which employs appropriate band-pass filters. The relationship between the arc-anode attachment mode and the temperature fluctuation of electrode surface was investigated. The diffuse arc-anode attachment mode leads to relatively large temperature fluctuation on anode surface due to the rotation of the arc spot. In the case of diffuse mode, the purity of synthesized multi-wall carbon nanotube was deteriorated with temperature fluctuation

  13. Effects of submergence on growth and survival of saplings of three wetland trees differing in adaptive mechanisms for flood tolerance

    Directory of Open Access Journals (Sweden)

    Fumiko Iwanaga

    2015-04-01

    Full Text Available Aim of study: Withstanding total submergence and reaeration following submergence is essential for the survival and establishment of wetland species. We focused on “LOES–low oxygen escape syndrome” and “LOQS–low oxygen quiescence syndrome” and compared tolerances to total submergence among wetland woody species differing in morphological adaptation to soil flooding. Area of study, materials and methods: This study examined the survival of 2-year-old saplings of Taxodium distichum and Metasequioia glyptostroboides (LOQS species, and Alnus japonica (LOES species, during and after total submergence. Saplings were completely submerged, then de-submerged to determine trends in survival and growth Main results: The M. glyptostroboides and A. japonica saplings could not survive prolonged submergence for more than 8 weeks, whereas saplings of T. distichum survived for over 2 years. Submerged saplings of all species showed no significant growth or modifications in morphology and anatomy under water, such as shoot elongation, adventitious root formation, and/or aerenchyma development. All T. distichum saplings that were de-submerged in the second year had the same pattern of shoot growth regardless of differences in timing and seasonality of de-submergence. Wood formation in T. distichum saplings ceased during submergence and resumed after de-submergence in spring and summer, but not in autumn. Research highlights: T. distichum saplings, which survived longer submergence periods than A. japonica and M. glyptostroboides, had physiological characteristics, such as suspension of growth and metabolism, which allowed survival of protracted total submergence (at least 2 years when saplings were immersed during the dormant stage before leaf flushing.

  14. Mercury and Iodine systematics of volcanic arc fluids

    Science.gov (United States)

    Varekamp, J. C.; Kading, T.; Fehn, U.; Lu, Z.

    2008-12-01

    The mantle has low Mercury and Iodine concentrations, but these elements occur in volcanic gases and hydrothermal fluids at ppb (Hg) and ppm (Iodine) levels. Possibly, the Hg and Iodine concentrations in volcanic fluids reflect subducted sediment sources in arc magmas. Iodine is a biophilic element, and I129/I values indicate that subducted sediment (especially organic matter) is an important Iodine source for arc magmas. It is uncertain if this is true for Hg as well, although in the surface environment Hg is commonly associated with organic matter. We present 60 new analyses of Hg and I in fluids from volcanoes in Central America, New Zealand, Japan, and the Cascades. A first assessment suggests that Iodine is released to some degree in the early stage of subduction in the forearc, whereas Hg may be released largely below the main volcanic arc. Isotope and trace element signatures of volcanic rocks of the investigated volcanoes show no simple correlation with Hg or Iodine abundances. The acid hot spring fluids of Copahue volcano (Argentina) carried ~ 200 ppt Hg in January 1999, ~80 ppt Hg in March 2008, and 90 ppt Hg in the crater lake in March 1997. The dissolved Hg fluxes from the Copahue hydrothermal system are ~300 gr Hg/year in 1999 and ~130 gr Hg/year in 2008. The bulk hydrothermal Hg flux (particle bound+dissolved) in 2008 was ~ 350 gr Hg/year. The potential Mercury evasion from these hydrothermal spring fluids into the air has not yet been incorporated in these estimates.

  15. Bifurcation theory of ac electric arcing

    International Nuclear Information System (INIS)

    Christen, Thomas; Peinke, Emanuel

    2012-01-01

    The performance of alternating current (ac) electric arcing devices is related to arc extinction or its re-ignition at zero crossings of the current (so-called ‘current zero’, CZ). Theoretical investigations thus usually focus on the transient behaviour of arcs near CZ, e.g. by solving the modelling differential equations in the vicinity of CZ. This paper proposes as an alternative approach to investigate global mathematical properties of the underlying periodically driven dynamic system describing the electric circuit containing the arcing device. For instance, the uniqueness of the trivial solution associated with the insulating state indicates the extinction of any arc. The existence of non-trivial attractors (typically a time-periodic state) points to a re-ignition of certain arcs. The performance regions of arcing devices, such as circuit breakers and arc torches, can thus be identified with the regions of absence and existence, respectively, of non-trivial attractors. Most important for applications, the boundary of a performance region in the model parameter space is then associated with the bifurcation of the non-trivial attractors. The concept is illustrated for simple black-box arc models, such as the Mayr and the Cassie model, by calculating for various cases the performance boundaries associated with the bifurcation of ac arcs. (paper)

  16. Physical characteristics of welding arc ignition process

    Science.gov (United States)

    Shi, Linan; Song, Yonglun; Xiao, Tianjiao; Ran, Guowei

    2012-07-01

    The existing research of welding arc mainly focuses on the stable combustion state and the research on the mechanism of welding arc ignition process is quite lack. The tungsten inert gas(TIG) touch arc ignition process is observed via a high speed camera and the high time resolution spectral diagnosis system. The changing phenomenon of main ionized element provided the electrons in the arc ignition is found. The metallic element is the main contributor to provide the electrons at the beginning of the discharging, and then the excitated shielding gas element replaces the function of the metallic element. The electron density during the period of the arc ignition is calculated by the Stark-broadened lines of Hα. Through the discussion with the repeatability in relaxation phenomenon, the statistical regularity in the arc ignition process is analyzed. The similar rules as above are observed through the comparison with the laser-assisted arc ignition experiments and the metal inert gas(MIG) arc ignition experiments. This research is helpful to further understanding on the generation mechanism of welding arc ignition and also has a certain academic and practical significance on enriching the welding physical theoretical foundation and improving the precise monitoring on automatic arc welding process.

  17. Evaluation of the US Army Research Laboratory Squeeze 5 Magnetic Flux Compression Generator

    Science.gov (United States)

    2016-09-01

    armature cracking, high-voltage insulation , and electrical arcing. 15. SUBJECT TERMS magnetic flux compression, field diffusion, mega ampere, high... insulation and can result in arcing that robs energy from the system. Magnetic field diffusion into the conducting portions of the system can also play a...indicates a short circuit occurred internally to the device, most likely due to damaged insulation during construction. The high-voltage switch failed to

  18. Effect of non-condensation gas on pressure oscillation of submerged steam jet condensation

    International Nuclear Information System (INIS)

    Zhao, Quanbin; Cong, Yuelei; Wang, Yingchun; Chen, Weixiong; Chong, Daotong; Yan, Junjie

    2016-01-01

    Highlights: • Oscillation intensity of steam–air jet increases with rise of water temperature. • Oscillation intensity reduces obviously when air is mixed. • Both first and second dominant frequencies decrease with rise of air mass fraction. • Air has little effect on power of 1st & 2nd frequency bands under low temperature. • The maximum oscillation power occurs under case of A = 1% and T ⩾ 50 °C. - Abstract: The effect of air with low mass fraction on the oscillation intensity and oscillation frequency of a submerged steam jet condensation is investigated under stable condensation region. With air mixing in steam, an obvious dynamic pressure peak appears along the jet direction. The intensity peak increases monotonously with the rise of steam mass flux and water temperature. Peak position moves downstream with the rise of air mass fraction. Moreover, when compared with that of pure steam jet, the oscillation intensity clearly decreases as air is mixed. However, when water temperature is lower than approximately 45 °C, oscillation intensity increases slightly with the rise of air mass fraction, and when water temperature is higher than 55 °C, the oscillation intensity decreases greatly with the rise of air mass fraction. Both the first and second dominant frequencies decrease with rise of air mass fraction. Finally, effect of air mass fractions on the oscillation power of the first and second dominant frequency bands shows similar trends. Under low water temperature, the mixed air has little effect on the oscillation power of both first and second frequency bands. However, when water temperature is high, the oscillation power of both first and second frequency bands appears an obvious peak when air mass fraction is about 1%. With further rise of air mass fraction, the oscillation power decreases gradually.

  19. Simultaneous rocket and radar measurements of currents in an auroral arc

    International Nuclear Information System (INIS)

    Robinson, R.M.; Bering, E.A.; Vondrak, R.R.; Anderson, H.R.; Cloutier, P.A.

    1981-01-01

    A detailed study of electric field, current and conductivities associated with an auroral arc was made in a coordinated rocket and radar experiment in Alaska on March 9, 1978. The payload, designated 29.007 UE, was launched at 1013 p.m. local time. It penetrated the diffuse aurora on the upleg and at apogee traversed field lines connected to a stable auroral arc of 40 kR intensity. Among the instruments carried by the payload were a vector magnetometer, a set of electrostatic double probes and a set of electron and proton spectrometers. Simultaneous electron density and line-of-sight velocity measurements were made by Chatanika radar operating in an elevation scan mode in the magnetic meridian plane. Both the radar and rocket measurements indicated that the zonal electric field was westward and approximately constant across the arc with a magnitude of about 7 mV/m. Small differences between the rocket and radar zonal electric field measurements indicated the presence of upward drifting ions in the region of the arc. The meridional field was large and northward equatorward of the arc, but negligible within the arc. Conductivities computed from measured fluxes of energetic electrons agreed well with the conductivities derived from the radar measureements of electron density. The electric field and conductivity measurements indicated that the zonal currents were eastward equatorward of the arc and westward within the arc. These electrojet currents agreed well with those inferred from the rocket magnetometer data. Better agreement was obtained when a westward neutral wind was added. The westward wind was also consistent with differences between the rocket and radar meridional electric fields. The meridional currents computed from the electric field measurements were northward over the entire region

  20. Influence of Catalysis and Oxidation on Slug Calorimeter Measurements in Arc Jets

    Science.gov (United States)

    Nawaz, Anuscheh; Driver, Dave; TerrazasSalinas, Imelda

    2012-01-01

    Arc jet tests play a critical role in the characterization and certification of thermal protection materials and systems (TPS). The results from these arc jet tests feed directly into computational models of material response and aerothermodynamics to predict the performance of the TPS in flight. Thus the precise knowledge of the plasma environment to which the test material is subjected, is invaluable. As one of the environmental parameters, the heat flux is commonly measured. The measured heat flux is used to determine the plasma enthalpy through analytical or computational models. At NASA Ames Research Center (ARC), slug calorimeters of a geometrically similar body to the test article are routinely used to determine the heat flux. A slug calorimeter is a thermal capacitance-type calorimeter that uses the temperature rise in a thermally insulated slug to determine the heat transfer rate, see Figure 1(left). Current best practices for measuring the heat flux with a slug calorimeter are described in ASTM E457 - 96. Both the calorimeter body and slug are made of Oxygen Free High Conductivity Copper, and are cleaned before each run.

  1. Arc Shape Characteristics with Ultra-High-Frequency Pulsed Arc Welding

    Directory of Open Access Journals (Sweden)

    Mingxuan Yang

    2017-01-01

    Full Text Available Arc plasma possesses a constriction phenomenon with a pulsed current. The constriction is created by the Lorentz force, the radial electromagnetic force during arc welding, which determines the energy distribution of the arc plasma. Welding experiments were carried out with ultra-high-frequency pulsed arc welding (UHFP-AW. Ultra-high-speed camera observations were produced for arc surveillance. Hue-saturation-intensity (HSI image analysis was used to distinguish the regions of the arc plasma that represented the heat energy distribution. The measurement of arc regions indicated that, with an ultra-high-frequency pulsed arc, the constriction was not only within the decreased arc geometry, but also within the constricted arc core region. This can be checked by the ratio of the core region to the total area. The arc core region expanded significantly at 40 kHz at 60 A. A current level of 80 A caused a decrease in the total region of the arc. Meanwhile, the ratio of the core region to the total increased. It can be concluded that arc constriction depends on the increased area of the core region with the pulsed current (>20 kHz.

  2. Auroral arc classification scheme based on the observed arc-associated electric field pattern

    International Nuclear Information System (INIS)

    Marklund, G.

    1983-06-01

    Radar and rocket electric field observations of auroral arcs have earlier been used to identify essentially four different arc types, namely anticorrelation and correlation arcs (with, respectively, decreased and increased arc-assocaited field) and asymmetric and reversal arcs. In this paper rocket double probe and supplementary observations from the literature, obtained under various geophysical conditions, are used to organize the different arc types on a physical rather than morphological basis. This classification is based on the relative influence on the arc electric field pattern from the two current continuity mechanisms, polarisation electric fields and Birkeland currents. In this context the tangential electric field plays an essential role and it is thus important that it can be obtained with both high accuracy and resolution. In situ observations by sounding rockets are shown to be better suited for this specific task than monostatic radar observations. Depending on the dominating mechanism, estimated quantitatively for a number of arc-crossings, the different arc types have been grouped into the following main categories: Polarisation arcs, Birkeland current arcs and combination arcs. Finally the high altitude potential distributions corresponding to some of the different arc types are presented. (author)

  3. Clustering of arc volcanoes caused by temperature perturbations in the back-arc mantle.

    Science.gov (United States)

    Lee, Changyeol; Wada, Ikuko

    2017-06-29

    Clustering of arc volcanoes in subduction zones indicates along-arc variation in the physical condition of the underlying mantle where majority of arc magmas are generated. The sub-arc mantle is brought in from the back-arc largely by slab-driven mantle wedge flow. Dynamic processes in the back-arc, such as small-scale mantle convection, are likely to cause lateral variations in the back-arc mantle temperature. Here we use a simple three-dimensional numerical model to quantify the effects of back-arc temperature perturbations on the mantle wedge flow pattern and sub-arc mantle temperature. Our model calculations show that relatively small temperature perturbations in the back-arc result in vigorous inflow of hotter mantle and subdued inflow of colder mantle beneath the arc due to the temperature dependence of the mantle viscosity. This causes a three-dimensional mantle flow pattern that amplifies the along-arc variations in the sub-arc mantle temperature, providing a simple mechanism for volcano clustering.

  4. EAARL-B Submerged Topography - Saint Croix and Saint Thomas, U.S. Virgin Islands, 2014

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Binary point-cloud data for part of the submerged environs of Saint Croix and Saint Thomas, U.S. Virgin Islands, were produced from remotely sensed, geographically...

  5. Acclimation of a terrestrial plant to submergence facilitates gas exchange under water

    DEFF Research Database (Denmark)

    Mommer, L.; Pedersen, O.; Visser, E. J. W.

    2004-01-01

    Flooding imposes stress upon terrestrial plants since it severely hampers gas exchange rates between the shoot and the environment. The resulting oxygen deficiency is considered to be the major problem for submerged plants. Oxygen microelectrode studies have, however, shown that aquatic plants...... of this terrestrial plant species to submergence for gas exchange capacity is also shown. Shoot acclimation to submergence involved a reduction of the diffusion resistance to gases, which was not only functional by increasing diffusion of oxygen into the plant, but also by increasing influx of CO2, which enhances...... maintain relatively high internal oxygen pressures under water, and even may release oxygen via the roots into the sediment, also in dark. Based on these results, we challenge the dogma that oxygen pressures in submerged terrestrial plants immediately drop to levels at which aerobic respiration is impaired...

  6. Design procedure for sizing a submerged-bed scrubber for airborne particulate removal

    International Nuclear Information System (INIS)

    Ruecker, C.M.; Scott, P.A.

    1987-04-01

    Performance correlations to design and operate the submerged bed scrubber were developed for various applications. Structural design procedure outlined in this report focuses on off-gas scrubbing for HLW vitrification applications; however, the method is appropriate for other applications

  7. Does mechanical disturbance affect the performance and species composition of submerged macrophyte communities?

    Science.gov (United States)

    Zhang, Qian; Xu, Ying-Shou; Huang, Lin; Xue, Wei; Sun, Gong-Qi; Zhang, Ming-Xiang; Yu, Fei-Hai

    2014-05-01

    Submerged macrophyte communities are frequently subjected to disturbance of various frequency and strength. However, there is still little experimental evidence on how mechanical disturbance affects the performance and species composition of such plant communities. In a greenhouse experiment, we constructed wetland communities consisting of five co-occurring clonal submerged macrophyte species (Hydrilla verticillata, Elodea canadensis, Ceratophyllum demersum, Chara fragilis, and Myriophyllum spicatum) and subjected these communities to three mechanical disturbance regimes (no, moderate and strong disturbance). Strong mechanical disturbance greatly decreased overall biomass, number of shoot nodes and total shoot length, and increased species diversity (evenness) of the total community. It also substantially decreased the growth of the most abundant species (H. verticillata), but did not affect growth of the other four species. Our data reveal that strong disturbance can have different effects on different submerged macrophyte species and thus alters the performance and species composition of submerged macrophyte communities.

  8. Satellite remote sensing of submerged aquatic vegetation distribution and status in the Currituck Sound, NC.

    Science.gov (United States)

    2012-11-01

    Submerged Aquatic Vegetation (SAV) is an important component in any estuarine ecosystem. As such, it is regulated by federal and state agencies as a jurisdictional resource, where impacts to SAV are compensated through mitigation. Historically, tradi...

  9. Effects of stern-foil submerged elevation on the lift and drag of a hydrofoil craft

    Science.gov (United States)

    Suastika, K.; Apriansyah

    2018-03-01

    Effects of the stern-foil submerged elevation on the lift and drag of a hydrofoil craft are studied by using computational fluid dynamics (CFD) and by considering three alternative stern-foil submerged elevations. The submerged elevation of the front foil is kept constant in all the alternatives. From among the alternatives, the deepest stern-foil placement results in the highest stern-foil lift with the highest foil’s lift-to-drag ratio. However, considering the lift-to-drag ratio of the whole foil-strut-hull system, the shallowest stern-foil placement results in the highest lift-to-drag ratio. The struts and the foil’s submerged elevation significantly affects the drag of the whole foil-strut-hull system.

  10. Metal accumulation by submerged macrophytes in eutrophic lakes at the watershed scale.

    Science.gov (United States)

    Xing, Wei; Wu, Haoping; Hao, Beibei; Liu, Guihua

    2013-10-01

    Metal concentrations (Al, Ba, Ca, K, Li, Mg, Na, Se, Sr and Ti) in submerged macrophytes and corresponding water and sediments were studied in 24 eutrophic lakes along the middle and lower reaches of the Yangtze River (China). Results showed that these eutrophic lakes have high metal concentrations in both water and sediments because of human activities. Average concentrations of Al and Na in tissues of submerged macrophytes were very high in sampled eutrophic lakes. By comparison, Ceratophyllum demersum and Najas marina accumulated more metals (e.g. Ba, Ca, K, Mg, Na, Sr and Ti). Strong positive correlations were found between metal concentrations in tissues of submerged macrophytes, probably because of co-accumulation of metals. The concentrations of Li, Mg, Na and Sr in tissues of submerged macrophytes significantly correlated with their corresponding water values, but not sediment values.

  11. Root transcript profiling of two Rorippa (brassicaceae) species reveals gene clusters associated with extreme submergence tolerance.

    NARCIS (Netherlands)

    Sasidharan, R.; Mustroph, A.; Boonman, A.; Akman, M.; Ammerlaan, A.M.H.; Breit, T.M.; Schranz, M.E.; Voesenek, L.A.C.J.; Tienderen, van P.H.

    2013-01-01

    Complete submergence represses photosynthesis and aerobic respiration, causing rapid mortality in most terrestrial plants. However, some plants have evolved traits allowing them to survive prolonged flooding, such as species of the genus Rorippa, close relatives of Arabidopsis (Arabidopsis

  12. Large-Scale Submerged Aquatic Vegetation Restoration in Chesapeake Bay: Status Report, 2003-2006

    National Research Council Canada - National Science Library

    Shafer, Deborah J; Bergstrom, Peter

    2008-01-01

    In 2003, the U.S. Army Engineer Research and Development Center (ERDC) and the National Oceanic and Atmospheric Administration Chesapeake Bay Office began a comprehensive research effort to restore submerged aquatic vegetation (SAV...

  13. Growth physiology and dimorphism of Mucor circinelloides (syn. racemosus) during submerged batch cultivation

    DEFF Research Database (Denmark)

    Mcintyre, Mhairi; Breum, J.; Arnau, J.

    2002-01-01

    Mucor circinelloides is being investigated as a possible host for the production of heterologous proteins. Thus, the environmental conditions defining the physiology and morphology of this dimorphic fungus have been investigated in submerged batch cultivation. The optimal conditions for growth...

  14. Vertical Gradient Freezing Using Submerged Heater Growth With Rotation and With Weak Magnetic and Electric Fields

    National Research Council Canada - National Science Library

    Bliss, D. F; Holmes, A. M; Wang, X; Ma, N; Iseler, G. W

    2005-01-01

    ...) method utilizing a submerged heater. Electromagnetic stirring can be induced in the gallium-antimonide melt just above the crystal growth interface by applying a weak radial electric current in the melt together with a weak axial magnetic field...

  15. Narrow gap mechanised arc welding in nuclear components manufactured by AREVA NP

    International Nuclear Information System (INIS)

    Peigney, A.

    2007-01-01

    Nuclear components require welds of irreproachable and reproducible quality. Moreover, for a given welding process, productivity requirements lead to reduce the volume of deposited metal and thus to use narrow gap design. In the shop, narrow gap Submerged Arc Welding process (SAW) is currently used on rotating parts in flat position for thicknesses up to 300 mm. Welding is performed with one or two wires in two passes per layer. In Gas Tungsten Arc Welding process (GTAW), multiple applications can be found because this process presents the advantage of allowing welding in all positions. Welding is performed in one or two passes per layer. The process is used in factory and on the nuclear sites for assembling new components but also for replacing components and for repairs. Presently, an increase of productivity of the process is sought through the use of hot wire and/or two wires. Concerning Gas Metal Arc Welding process (GMAW), its use is growing for nuclear components, including narrow gap applications. This process, limited in its applications in the past on account of the defects it generated, draws benefit from the progress of the welding generators. Then it is possible to use this efficient process for high security components such as those of nuclear systems. It is to be noted that the process is applicable in the various welding positions as it is the case for GTAW, while being more efficient than the latter. This paper presents the state of the art in the use of narrow gap mechanised arc welding processes by AREVA NP units. (author) [fr

  16. Prototype arc saw design and cutting trials

    International Nuclear Information System (INIS)

    Allison, G.S.

    1980-09-01

    A program was initiated to develop the arc saw as a tool capable of removing the end fittings from spent nuclear fuel bundles. A special arc saw for this purpose was designed, installed at the Pacific Northwest Laboratory and satisfactorily operated to remove end fittings from simulated, nonradioactive fuel bundles. The design of the arc saw included consideration of the cutting environment, power supply size, control equipment, and work piece size. Several simulated fuel bundles were cut to demonstrate that the arc saw met design specifications. Although the arc saw development program was curtailed before significant performance data could be collected, tests indicate that the arc saw is a good means of cropping spent fuel bundles and is well suited to remote operation and maintenance

  17. Submerged reef systems on the central western continental shelf of India

    Digital Repository Service at National Institute of Oceanography (India)

    Vora, K.H.; Almeida, F.

    -262 255 Elsevier Science Publishers B.V., Amsterdam -- Printed in the Netherlands Letter Section Submerged Reef Systems on the Central Western Continental Shelf of India K.H. VORA and F. ALMEIDA National Institute of Oceanography, Dona Paula, Goa 403... 004 (India) (Revision accepted October 26, 1989) Abstract Vora, K.H. and Almeida, F., 1990. Submerged reef systems on the central western continental shelf of India. Mar. Geol., 91: 255-262. Echosounding and sidescan sonar data from the western...

  18. Agenesis of premolar associated with submerged primary molar and a supernumerary premolar: An unusual case report

    Directory of Open Access Journals (Sweden)

    S. V. S. G. Nirmala

    2012-01-01

    Full Text Available The combination of submerged primary molar, agenesis of permanent successor with a supernumerary in the same place is very rare. The purpose of this article is to report a case of submerged mandibular left second primary molar with supernumerary tooth in the same region along with agenesis of second premolar in an 11-year-old girl, its possible etiological factors, and a brief discussion on treatment options.

  19. Analysis of submerged implant towards mastication load using 3D finite element method (FEM)

    OpenAIRE

    Widia Hafsyah Sumarlina Ritonga; Janti Rusjanti; Nunung Rusminah; Aldilla Miranda; Tatacipta Dirgantara

    2016-01-01

    Introduction: The surgical procedure for implantation of a surgical implant comprising a stage for the implant design nonsubmerged and two stages for submerged. Submerged implant design often used in Faculty of Dentistry Universitas Padjadjaran because it is safer in achieving osseointegration. This study was conducted to evaluate the failure of dental implant based on location and the value of internal tensiones as well as supporting tissues when given mastication load by using the 3D Finite...

  20. On the formation of auroral arcs

    International Nuclear Information System (INIS)

    Stasiewicz, K.

    1984-04-01

    A new mechanism for auroral arc formation is presented. The characteristic linear shape of auroral arcs is determined by magnetically connected plasma clouds in the distant equatorial magnetosphere. These clouds originate as high speed plasma beams in the magnetotail and in the solar wind. It is found that the free energy for driving an auroral arc is provided by the difference of pressure between the cloud and the ambient plasma. (author)

  1. Programming ArcGIS with Python cookbook

    CERN Document Server

    Pimpler, Eric

    2015-01-01

    Programming ArcGIS with Python Cookbook, Second Edition, is written for GIS professionals who wish to revolutionize their ArcGIS workflow with Python. Whether you are new to ArcGIS or a seasoned professional, you almost certainly spend time each day performing various geoprocessing tasks. This book will teach you how to use the Python programming language to automate these geoprocessing tasks and make you a more efficient and effective GIS professional.

  2. Arc saw and its application to decommissioning

    International Nuclear Information System (INIS)

    Deichelbohrer, P.R.

    1982-01-01

    The arc saw is a toothless, circular saw that cuts by arc erosion. A model was built to study the arc saw's usefulness in cutting up radioactively contaminated metal scrap. It was chosen because it cuts with very little contact to the work piece and because cutting is not affected by material hardness. After installation of several improvements it was found it could cut almost any combination of metals and that clamping or fixturing requirements were minimum. Cutting proceeds rapidly and efficiently

  3. Nomenclature of SLC Arc beamline components

    International Nuclear Information System (INIS)

    Silva, J.; Weng, W.T.

    1986-01-01

    This note defines I and C formal names for beamline components in the Arc as specified in the TRANSPORT decks ARCN FINAL and ARCS FINAL of June 5, 1985. The formal name consists of three fields: the primary name, the zone and the unit number. The general principles and guidelines are explained in Reference 1. The rationale and the final resolutions of the naming conventions for the Arc are explained

  4. Diffuse and spot mode of cathode arc attachments in an atmospheric magnetically rotating argon arc

    International Nuclear Information System (INIS)

    Chen, Tang; Wang, Cheng; Liao, Meng-Ran; Xia, Wei-Dong

    2016-01-01

    A model including the cathode, near-cathode region, and arc column was constructed. Specifically, a thermal perturbation layer at the arc fringe was calculated in order to couple sheath/presheath modelling with typical arc column modelling. Comparative investigation of two modes of attachment of a dc (100, 150, 200 A) atmospheric-pressure arc in argon to a thermionic cathode made of pure tungsten was conducted. Computational data revealed that there exists two modes of arc discharge: the spot mode, which has an obvious cathode surface temperature peak in the arc attachment centre; and the diffuse mode, which has a flat cathode surface temperature distribution and a larger arc attachment area. The modelling results of the arc attachment agree with previous experimental observations for the diffuse mode. A further 3D simulation is obviously needed to investigate the non-axisymmetrical features, especially for the spot mode. (paper)

  5. Transcriptomic Analysis of Gibberellin- and Paclobutrazol-Treated Rice Seedlings under Submergence

    Directory of Open Access Journals (Sweden)

    Jing Xiang

    2017-10-01

    Full Text Available Submergence stress is a limiting factor for rice growing in rainfed lowland areas of the world. It is known that the phytohormone gibberellin (GA has negative effects on submergence tolerance in rice, while its inhibitor paclobutrazol (PB does the opposite. However, the physiological and molecular basis underlying the GA- and PB-regulated submergence response remains largely unknown. In this study, we reveal that PB could significantly enhance rice seedling survival by retaining a higher level of chlorophyll content and alcohol dehydrogenase activity, and decelerating the consumption of non-structure carbohydrate when compared with the control and GA-treated samples. Further transcriptomic analysis identified 3936 differentially expressed genes (DEGs among the GA- and PB-treated samples and control, which are extensively involved in the submergence and other abiotic stress responses, phytohormone biosynthesis and signaling, photosynthesis, and nutrient metabolism. The results suggested that PB enhances rice survival under submergence through maintaining the photosynthesis capacity and reducing nutrient metabolism. Taken together, the current study provided new insight into the mechanism of phytohormone-regulated submergence response in rice.

  6. [Influence of submerged macrophytes on phosphorus transference between sediment and overlying water in the growth period].

    Science.gov (United States)

    Wang, Li-Zhi; Wang, Guo-Xiang; Yu, Zhen-Fei; Zhou, Bei-Bei; Chen, Qiu-Min; Li, Zhen-Guo

    2012-02-01

    In order to study the process of phosphorus transfer between sediment and overlying water, Hydrilla verticillata and Vallisneria natans were cultured in spring, Potamogeton crispus was cultured in winter. Changes of environmental factors and phosphorus concentrations in water and sediment were investigated. The results indicated that: submerged macrophytes could reduce all phosphorus fractions in the overlying water. Phosphorus concentrations in overlying water maintained in a relative low level in the growth period of submerged macrophytes. The concentrations of total phosphorus (TP) in overlying water of H. verticillata, V. natans and P. crispus were 0.03-0.05, 0.04-0.12, 0.02-0.11 mg x L(-1), respectively. All phosphorus fractions in sediment were reduced. The maximum value between submerged macrophyte and control of H. verticillata, V. natans and P. crispus were 35.34, 60.67 and 25.92 mg x kg(-1), respectively. Dissolved oxygen (DO), redox potential (Eh) and pH in overlying water increased (DO 10.0-14.0 mg x L(-1), Eh 185-240 mV, pH 8.0-11.0) in the submerged macrophytes groups. Submerged macrophytes increased Eh( -140 - -23 mV) and maintained pH(7.2-8.0) in neutral range. The results indicated that submerged macrophytes affected phosphorus transferring between sediment and overlying water through increasing DO, Eh and pH in overlying water, and Eh in sediment.

  7. Alternative energy efficient membrane bioreactor using reciprocating submerged membrane.

    Science.gov (United States)

    Ho, J; Smith, S; Roh, H K

    2014-01-01

    A novel membrane bioreactor (MBR) pilot system, using membrane reciprocation instead of air scouring, was operated at constant high flux and daily fluctuating flux to demonstrate its application under peak and diurnal flow conditions. Low and stable transmembrane pressure was achieved at 40 l/m(2)/h (LMH) by use of repetitive membrane reciprocation. The results reveal that the inertial forces acting on the membrane fibers effectively propel foulants from the membrane surface. Reciprocation of the hollow fiber membrane is beneficial for the constant removal of solids that may build up on the membrane surface and inside the membrane bundle. The membrane reciprocation in the reciprocating MBR pilot consumed less energy than coarse air scouring used in conventional MBR systems. Specific energy consumption for the membrane reciprocation was 0.072 kWh/m(3) permeate produced at 40 LMH flux, which is 75% less than for a conventional air scouring system as reported in literature without consideration of energy consumption for biological aeration (0.29 kWh/m(3)). The daily fluctuating flux test confirmed that the membrane reciprocation is effective to handle fluctuating flux up to 50 LMH. The pilot-scale reciprocating MBR system successfully demonstrated that fouling can be controlled via 0.43 Hz membrane reciprocation with 44 mm or higher amplitude.

  8. The development of argon arc brazing with Cu-based filler for ITER thermal anchor attachment

    International Nuclear Information System (INIS)

    Sun Zhenchao; Li Pengyuan; Pan Chuanjie; Hou Binglin; Han Shilei; Pei Yinyin; Long Weimin

    2012-01-01

    Thermal anchor is the key component of ITER magnet supports to maintain the low temperature for the nor mal operation of superconducting coils. During the advanced research of ITER thermal anchor attachment, dozens of brazing filler and several kinds of brazing technique have been developed and investigated. The test result shows that Cu-based alloy have the preferable mechanical properties at both room temperature and liquid nitrogen temperatures (77 K) for high brazing temperature. And it has a good weldability to 316LN. The brazing temperature of Cu-based filler is over 1000℃, but heat input is relatively low for shallower heating depth of argon arc brazing. Lower heat input is good for the control of brazing deformation. It is no need to clean after brazing because for argon arc brazing there is no bra- zing flux used. Arc brazing with Cu-based filler was chosen as the principal method for the attachment of thermal anchor. (authors)

  9. Underwater Photosynthesis of Submerged Plants – Recent Advances and Methods

    Science.gov (United States)

    Pedersen, Ole; Colmer, Timothy D.; Sand-Jensen, Kaj

    2013-01-01

    We describe the general background and the recent advances in research on underwater photosynthesis of leaf segments, whole communities, and plant dominated aquatic ecosystems and present contemporary methods tailor made to quantify photosynthesis and carbon fixation under water. The majority of studies of aquatic photosynthesis have been carried out with detached leaves or thalli and this selectiveness influences the perception of the regulation of aquatic photosynthesis. We thus recommend assessing the influence of inorganic carbon and temperature on natural aquatic communities of variable density in addition to studying detached leaves in the scenarios of rising CO2 and temperature. Moreover, a growing number of researchers are interested in tolerance of terrestrial plants during flooding as torrential rains sometimes result in overland floods that inundate terrestrial plants. We propose to undertake studies to elucidate the importance of leaf acclimation of terrestrial plants to facilitate gas exchange and light utilization under water as these acclimations influence underwater photosynthesis as well as internal aeration of plant tissues during submergence. PMID:23734154

  10. Mineralization of surfactants by the microbiota of submerged plant detritus.

    Science.gov (United States)

    Federle, T W; Ventullo, R M

    1990-02-01

    In wetlands and canopied bodies of water, plant detritus is an important source of carbon and energy. Detrital materials possess a large surface area for sorption of dissolved organics and are colonized by a large and diverse microbiota. To examine the biodegradation of surfactants by these microorganisms, submerged oak leaves were obtained from a laundromat wastewater pond, its overflow, and a pristine control pond. Leaves were cut into disks and incubated in sterile water amended with 50 mug of C-labeled linear alkylbenzene sulfonate (LAS), linear alcohol ethoxylate, stearyltrimethyl ammonium chloride, distearyldimethyl ammonium chloride, benzoic acid, or mixed amino acids per liter. Sorption of the test compounds to the detritus and evolution of CO(2) were followed with time. All of the compounds sorbed to the detritus to various degrees, with LAS and stearyltrimethyl ammonium chloride the most sorptive and benzoic acid the least. All compounds were mineralized without a lag. With leaves from the laundromat wastewater pond, half-lives were 12.6 days for LAS, 8.4 days for linear alcohol ethoxylate, 14.2 days for stearyltrimethyl ammonium chloride, 1.0 days for benzoic acid, and 2.7 days for mixed amino acids. Mineralization of LAS and linear alcohol ethoxylate by control pond leaves was slower and exhibited an S-shaped rather than a typical first-order pattern. This study shows that detritus represents a significant site of surfactant removal in detritus-rich systems.

  11. Mineralization of surfactants by the microbiota of submerged plant detritus

    International Nuclear Information System (INIS)

    Federle, T.W.; Ventullo, R.M.

    1990-01-01

    In wetlands and canopied bodies of water, plant detritus is an important source of carbon and energy. Detrital materials possess a large surface area for sorption of dissolved organics and are colonized by a large and diverse microbiota. To examine the biodegradation of surfactants by these microorganisms, submerged oak leaves were obtained from a laundromat wastewater pond, its overflow, and a pristine control pond. Leaves were cut into disks and incubated in sterile water amended with 50 μg of 14 C-labeled linear alkylbenzene sulfonate (LAS), linear alcohol ethoxylate, stearyltrimethyl ammonium chloride, distearyldimethyl ammonium chloride, benzoic acid, or mixed amino acids per liter. Sorption of the test compounds to the detritus and evolution of 14 CO 2 were followed with time. All of the compounds sorbed to the detritus to various degrees, with LAS and stearyltrimethyl ammonium chloride the most sorptive and benzoic acid the least. All compounds were mineralized without a lag. With leaves from the laundromat wastewater pond, half-lives were 12.6 days for LAS, 8.4 days for linear alcohol ethoxylate, 14.2 days for stearyltrimethyl ammonium chloride, 1.0 days for benzoic acid, and 2.7 days for mixed amino acids. Mineralization of LAS and linear alcohol ethoxylate by control pond leaves was slower and exhibited an S-shaped rather than a typical first-order pattern. This study shows that detritus represents a significant site of surfactant removal in detritus-rich systems

  12. Production of tannase by Aspergillus tamarii in submerged cultures

    Directory of Open Access Journals (Sweden)

    Andréa M. Costa

    2008-04-01

    Full Text Available The production of tannase by Aspergillus tamarii was studied in submerged cultures. The fungus produced an extracellular tannase after two days of growth in mineral medium containing tannic acid, gallic acid and methyl gallate as carbon source. The best result was obtained using gallic acid as inducer (20.6 U/ml. The production of enzyme was strongly repressed by the presence of glucose. Crude enzyme was optimally active at pH 5.0 and 30º C. The enzyme was stable in a large range of pH and up to the temperature of 45º C.A produção de tanase por um novo potencial produtor, o fungo filamentoso Aspergillus tamarii, foi parcialmente caracterizada neste estudo. O fungo produziu uma tanase extracelular em culturas submersas após 2 dias de crescimento em meio mineral contendo ácido tânico, ácido gálico ou metil galato como fonts de carbono. Os melhores resultados foram obtidos em culturas com ácido gálico (20,6 U/ml. A produção da enzima foi fortemente inibida por glicose. A enzima bruta foi otimamente ativa em pH 5,0 e a 30º C e estável em ampla faixa de pH e em temperaturas inferiores a 45ºC.

  13. Modeling Refuge Effect of Submerged Macrophytes in Lake System.

    Science.gov (United States)

    Lv, Dongyu; Fan, Meng; Kang, Yun; Blanco, Krystal

    2016-04-01

    This paper considers a significant problem in biological control of algae issue in ecological environment. A four-dimensional dynamic model is carefully formulated to characterize the interactions among phytoplankton, submerged macrophyte, zooplankton, and general fish class in a lake ecosystem. The predation relationship is modeled by Beddington-DeAngelis functional responses derived from the classical Holling time budget arguments. Qualitative analyses of the global dynamics show that the system can generate very rich dynamics with potentially 10 different equilibria and several bistable scenarios. We perform analysis on the existence and local stability of equilibria and explore the refuge effect of macrophyte on the zooplankton with numerical simulations on aquatic ecosystems. We also discuss effective methods of biological control used to restrain the increase of phytoplankton. Our study shows the proposed model could have rich and complex dynamics including but not limited to bistable and chaotic phenomenon. Numerical simulation results demonstrate that both the refuge constant and the density of the macrophytes are two key factors where refuge effects take place. In addition, the intraspecific competition between the macrophyte and the phytoplankton can also affect the macrophyte's refuge effect. Our analytical and simulation results suggest that macrophytes provide structure and shelter against predation for zooplankton such that it could restore the zooplankton population, and that planting macrophyte properly might achieve the purpose of controlling algae growth.

  14. Wave forces on cylinder submerged horizontally in shallow water

    Energy Technology Data Exchange (ETDEWEB)

    Mitani, H; Sasaki, K; Kobayashi, T; Nomura, N; Kawabe, H; Sugimoto, H

    1976-12-01

    To estimate the wave forces on offshore and/or coastal structures, the ideal method is undoubtedly to obtain the more accurate solution of hydrodynamic equations under suitable boundary conditions. However, in practice, it is difficult to introduce precise solutions under present technical levels because some important problems still remain. Among them is the unsteady boundary layers with separation around the objects. Consequently, every effort is being made in this field to approximate these conditions. Among these approximations, the Diffraction Wave Theory and the Morrison's Method are the most famous means in practice, although both still have some problems. Some problems with the traditional Finite Amplitude Wave Theories such as Stokes and Cnoidal Wave Theories are examined, and by applying additional computed results to the Morrison's formula, the estimated formula for wave forces on a cylinder submerged horizontally in shallow water is introduced. Subsequently, the applicability of the formula and also the specific characteristics of wave forces on a horizontally settled cylinder are investigated in detail, attaching first importance to the distinctions from the vertically settled cylinder, based on the comparison of computed results with experimental results. The experiments were carried out on two different diameters of cylinder, 70 mm and 140 mm, and bottom slopes of the experimental tanks, /sup 1///sub 100/ and /sup 1///sub 30/, under various conditions varying water depth, wave period, wave height and also setting position of cylinder.

  15. Spatiotemporal dynamics of submerged macrophytes in a Mediterranean coastal lagoon

    Science.gov (United States)

    Obrador, Biel; Pretus, Joan Lluís

    2010-03-01

    The seasonal and interannual dynamics of the biomass and spatial distribution of a macrophyte meadow were explored in a Mediterranean coastal lagoon (Albufera des Grau, Balearic Islands) from 2002 to 2007. The dynamics in the main physicochemical variables were also analysed to assess the factors involved in the spatiotemporal variability of the submerged macrophytes. The meadows were dominated by Ruppia cirrhosa, which showed a marked seasonal cycle with winter quiescence and complete annual regrowth. The annual production of R. cirrhosa had high interannual variability and was amongst the highest described for this species in the literature, ranging 327-919 gDW m -2. The spatial distribution of macrophytes was determined by light availability and wave exposure, with the highest abundances found in shallow and gently sloped areas sheltered from the strong northerly winds. The interannual variations in macrophyte descriptors (area of occurrence, average depth of the meadows, and maximum biomass) were mainly related to water turbidity and salinity, but the effect of these variables was constrained to the spring and summer months, respectively. A significant negative correlation between the extent of coverage of R. cirrhosa and the water level at the end of the previous annual cycle was observed, suggesting a positive effect of desiccation on the extent of coverage of the macrophytes. After six years of apparent stability, the macrophytes abruptly disappeared from the lagoon. Although the mechanisms are not clear, this shift was likely attributable to a combination of several factors.

  16. Submerged macrophyte communities in the Forsmark area. Building of a GIS application as a tool for biomass estimations

    International Nuclear Information System (INIS)

    Fredriksson, Ronny

    2005-12-01

    The aim of this study was to compile the information from previous studies to produce a GIS application that both illustrates the distribution of different vegetation communities and also makes it possible to estimate the total biomass of the different vegetation communities and its associated fauna. The GIS application was created by means of the software Arc View 3.3 by Environmental Systems Research Institute, Inc. Distribution readings and quantitative data of submerged macrophyte communities and its associated fauna was obtained from studies by Kautsky et al. and by Borgiel. Information about the macrophyte distribution in Laangoersviken, located in the northern parts of Kallrigafjaerden, was obtained from a report by Upplandsstiftelsen. Information about water depth and bottom substrate was available as USGS DEM file, produced by Geological Survey of Sweden. Complementary data of the covering degree of submerged vegetation was obtained from a study using an under water video camera by Tobiasson. Quantitative data on macrophyte and faunal biomass were either obtained from the primary SKB data base SICADA or directly from reports. Samples were compiled and analysed according to dominating vegetation. The work was carried out as follows: Where information about the bottom substrate was available polygons were created by means of the substrate shape file and depth grid from Geological Survey of Sweden. The vegetation community and the covering degree on a certain depth and substrate combination were determined by compiled information from studies by Kautsky and by Borgiel. All observations from a certain bottom substrate were analysed to find the dominating vegetation within different depth ranges. After determining the dominating vegetation, the covering degrees of different macrophyte classes within each depth range were calculated as a mean of all readings. Areas without information about the bottom substrate, but still adjacent to areas included in the

  17. Submerged macrophyte communities in the Forsmark area. Building of a GIS application as a tool for biomass estimations

    Energy Technology Data Exchange (ETDEWEB)

    Fredriksson, Ronny [Univ. of Kalmar (Sweden)

    2005-12-15

    The aim of this study was to compile the information from previous studies to produce a GIS application that both illustrates the distribution of different vegetation communities and also makes it possible to estimate the total biomass of the different vegetation communities and its associated fauna. The GIS application was created by means of the software Arc View 3.3 by Environmental Systems Research Institute, Inc. Distribution readings and quantitative data of submerged macrophyte communities and its associated fauna was obtained from studies by Kautsky et al. and by Borgiel. Information about the macrophyte distribution in Laangoersviken, located in the northern parts of Kallrigafjaerden, was obtained from a report by Upplandsstiftelsen. Information about water depth and bottom substrate was available as USGS DEM file, produced by Geological Survey of Sweden. Complementary data of the covering degree of submerged vegetation was obtained from a study using an under water video camera by Tobiasson. Quantitative data on macrophyte and faunal biomass were either obtained from the primary SKB data base SICADA or directly from reports. Samples were compiled and analysed according to dominating vegetation. The work was carried out as follows: Where information about the bottom substrate was available polygons were created by means of the substrate shape file and depth grid from Geological Survey of Sweden. The vegetation community and the covering degree on a certain depth and substrate combination were determined by compiled information from studies by Kautsky and by Borgiel. All observations from a certain bottom substrate were analysed to find the dominating vegetation within different depth ranges. After determining the dominating vegetation, the covering degrees of different macrophyte classes within each depth range were calculated as a mean of all readings. Areas without information about the bottom substrate, but still adjacent to areas included in the

  18. Automatic Control Of Length Of Welding Arc

    Science.gov (United States)

    Iceland, William F.

    1991-01-01

    Nonlinear relationships among current, voltage, and length stored in electronic memory. Conceptual microprocessor-based control subsystem maintains constant length of welding arc in gas/tungsten arc-welding system, even when welding current varied. Uses feedback of current and voltage from welding arc. Directs motor to set position of torch according to previously measured relationships among current, voltage, and length of arc. Signal paths marked "calibration" or "welding" used during those processes only. Other signal paths used during both processes. Control subsystem added to existing manual or automatic welding system equipped with automatic voltage control.

  19. Investigations Of A Pulsed Cathodic Vacuum Arc

    Science.gov (United States)

    Oates, T. W. H.; Pigott, J.; Denniss, P.; Mckenzie, D. R.; Bilek, M. M. M.

    2003-06-01

    Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed.

  20. The Abundance of Large Arcs From CLASH

    Science.gov (United States)

    Xu, Bingxiao; Postman, Marc; Meneghetti, Massimo; Coe, Dan A.; Clash Team

    2015-01-01

    We have developed an automated arc-finding algorithm to perform a rigorous comparison of the observed and simulated abundance of large lensed background galaxies (a.k.a arcs). We use images from the CLASH program to derive our observed arc abundance. Simulated CLASH images are created by performing ray tracing through mock clusters generated by the N-body simulation calibrated tool -- MOKA, and N-body/hydrodynamic simulations -- MUSIC, over the same mass and redshift range as the CLASH X-ray selected sample. We derive a lensing efficiency of 15 ± 3 arcs per cluster for the X-ray selected CLASH sample and 4 ± 2 arcs per cluster for the simulated sample. The marginally significant difference (3.0 σ) between the results for the observations and the simulations can be explained by the systematically smaller area with magnification larger than 3 (by a factor of ˜4) in both MOKA and MUSIC mass models relative to those derived from the CLASH data. Accounting for this difference brings the observed and simulated arc statistics into full agreement. We find that the source redshift distribution does not have big impact on the arc abundance but the arc abundance is very sensitive to the concentration of the dark matter halos. Our results suggest that the solution to the "arc statistics problem" lies primarily in matching the cluster dark matter distribution.

  1. Teaching with ArcGIS Pro

    OpenAIRE

    Theller, Larry

    2016-01-01

    For Fall semester 2016 the ABE department moved the course ASM 540 Basic GIS from ArcGIS Desktop 10.2 to ArcGIS Pro 1.3. This software from ESRI has a completely new look and feel, (ribbon-based rather than cascading menus) and is a true 64 bit application, capable of multi-threading, and built on Python 3. After ArcGIS Desktop 10.5 is released, desktop ends and the future release will be ArcGIS Pro; so it makes sense to switch sooner rather than later. This talk will discuss some issues and...

  2. Investigations Of A Pulsed Cathodic Vacuum Arc

    International Nuclear Information System (INIS)

    Oates, T.W.H.; Pigott, J.; Denniss, P.; Mckenzie, D.R.; Bilek, M.M.M.

    2003-01-01

    Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed

  3. The dual-electrode DC arc furnace-modelling brush arc conditions

    OpenAIRE

    Reynolds, Q.G.

    2012-01-01

    The dual-electrode DC arc furnace, an alternative design using an anode and cathode electrode instead of a hearth anode, was studied at small scale using computational modelling methods. Particular attention was paid to the effect of two key design variables, the arc length and the electrode separation, on the furnace behaviour. It was found that reducing the arc length to brush arc conditions was a valid means of overcoming several of the limitations of the dual-electrode design, namely high...

  4. Clustering of Emerging Flux

    Science.gov (United States)

    Ruzmaikin, A.

    1997-01-01

    Observations show that newly emerging flux tends to appear on the Solar surface at sites where there is flux already. This results in clustering of solar activity. Standard dynamo theories do not predict this effect.

  5. Plasma arc melting of zirconium

    International Nuclear Information System (INIS)

    Tubesing, P.K.; Korzekwa, D.R.; Dunn, P.S.

    1997-01-01

    Zirconium, like some other refractory metals, has an undesirable sensitivity to interstitials such as oxygen. Traditionally, zirconium is processed by electron beam melting to maintain minimum interstitial contamination. Electron beam melted zirconium, however, does not respond positively to mechanical processing due to its large grain size. The authors undertook a study to determine if plasma arc melting (PAM) technology could be utilized to maintain low interstitial concentrations and improve the response of zirconium to subsequent mechanical processing. The PAM process enabled them to control and maintain low interstitial levels of oxygen and carbon, produce a more favorable grain structure, and with supplementary off-gassing, improve the response to mechanical forming

  6. Analogue modeling of arc and backarc deformation in the New Hebrides arc and North Fiji Basin

    NARCIS (Netherlands)

    Schellart, W. P.; Lister, G. S.; Jessell, M. W.

    In most backarc basins, extension is perpendicular to the arc. Thus individual spreading ridges extend approximately parallel to the arc. In the North Fiji Basin, however, several ancient and active spreading ridges strike 70°-90° to the New Hebrides arc. These high-angle spreading ridges relocated

  7. Interelectrode plasma evolution in a hot refractory anode vacuum arc: Theory and comparison with experiment

    International Nuclear Information System (INIS)

    Beilis, I.I.; Goldsmith, S.; Boxman, R.L.

    2002-01-01

    In this paper a theoretical study of a hot refractory anode vacuum arc, which was previously investigated experimentally [Phys. Plasmas 7, 3068 (2000)], is presented. The arc was sustained between a thermally isolated refractory anode and a water-cooled copper cathode. The arc started as a multicathode-spot (MCS) vacuum arc and then switched to the hot refractory anode vacuum arc (HRAVA) mode. In the MCS mode, the cathodic plasma jet deposits a film of the cathode material on the anode. Simultaneously, the temperature of the thermally isolated anode begins to rise, reaching eventually a sufficiently high temperature to re-evaporate the deposited material, which is subsequently ionized in the interelectrode gap. The transition to the HRAVA mode is completed when the density of the interelectrode plasma consists mostly of ionized re-evaporated atoms--the anode plasma. The evolution of the HRAVA mode is characterized by the propagation of a luminous plasma plume from the anode to the cathode. The time dependent model of the various physical processes taking place during the transition to the HRAVA mode is represented by a system of equations describing atom re-evaporation, atom ionization through the interaction of the cathode jet and the interelectrode plasma with the anode vapor, plasma plume propagation, plasma radial expansion, plasma energy, and heavy particle density balance. The time dependence of the anode heat flux and the effective anode voltage were obtained by solving these equations. In addition, the time dependent plasma electron temperature, plasma density, anode potential drop, arc voltage, and anode temperature distribution were calculated and compared with previous measurements. It was shown that the observed decrease of the effective anode voltage with time during the mode transition is due to decrease of the heat flux incident on the anode surface from the cathode spot jets

  8. Evaluating optical hazards from plasma arc cutting.

    Science.gov (United States)

    Glassford, Eric; Burr, Gregory

    2018-01-01

    The Health Hazard Evaluation Program of the National Institute for Occupational Safety and Health evaluated a steel building materials manufacturer. The employer requested the evaluation because of concerns about optical radiation hazards from a plasma arc cutting system and the need to clarify eye protection requirements for plasma operators, other employees, and visitors. The strength of the ultraviolet radiation, visible radiation (light), and infrared radiation generated by the plasma arc cutter was measured at various distances from the source and at different operating amperages. Investigators also observed employees performing the plasma arc cutting. Optical radiation above safe levels for the unprotected eyes in the ultraviolet-C, ultraviolet-B, and visible light ranges were found during plasma arc cutting. In contrast, infrared and ultraviolet-A radiation levels during plasma arc cutting were similar to background levels. The highest non-ionizing radiation exposures occurred when no welding curtains were used. A plasma arc welding curtain in place did not eliminate optical radiation hazards to the plasma arc operator or to nearby employees. In most instances, the measured intensities for visible light, UV-C, and UV-B resulted in welding shade lens numbers that were lower than those stipulated in the OSHA Filter Lenses for Protection Against Radiant Energy table in 29 CFR 1910.133(a)(5). [1] Investigators recommended using a welding curtain that enclosed the plasma arc, posting optical radiation warning signs in the plasma arc cutter area, installing audible or visual warning cues when the plasma arc cutter was operating, and using welding shades that covered the plasma arc cutter operator's face to protect skin from ultraviolet radiation hazards.

  9. Volumetric modulated arc therapy: IMRT in a single gantry arc

    International Nuclear Information System (INIS)

    Otto, Karl

    2008-01-01

    In this work a novel plan optimization platform is presented where treatment is delivered efficiently and accurately in a single dynamically modulated arc. Improvements in patient care achieved through image-guided positioning and plan adaptation have resulted in an increase in overall treatment times. Intensity-modulated radiation therapy (IMRT) has also increased treatment time by requiring a larger number of beam directions, increased monitor units (MU), and, in the case of tomotherapy, a slice-by-slice delivery. In order to maintain a similar level of patient throughput it will be necessary to increase the efficiency of treatment delivery. The solution proposed here is a novel aperture-based algorithm for treatment plan optimization where dose is delivered during a single gantry arc of up to 360 deg. The technique is similar to tomotherapy in that a full 360 deg. of beam directions are available for optimization but is fundamentally different in that the entire dose volume is delivered in a single source rotation. The new technique is referred to as volumetric modulated arc therapy (VMAT). Multileaf collimator (MLC) leaf motion and number of MU per degree of gantry rotation is restricted during the optimization so that gantry rotation speed, leaf translation speed, and dose rate maxima do not excessively limit the delivery efficiency. During planning, investigators model continuous gantry motion by a coarse sampling of static gantry positions and fluence maps or MLC aperture shapes. The technique presented here is unique in that gantry and MLC position sampling is progressively increased throughout the optimization. Using the full gantry range will theoretically provide increased flexibility in generating highly conformal treatment plans. In practice, the additional flexibility is somewhat negated by the additional constraints placed on the amount of MLC leaf motion between gantry samples. A series of studies are performed that characterize the relationship

  10. Free convection in a partially submerged fluid loop

    International Nuclear Information System (INIS)

    Britt, T.E.; Wood, D.C.

    1982-01-01

    Several natural convection loop systems are studied in order to determine the operational characteristics for a multiple loop container which is used to cool failed nuclear reactor assemblies. Both analytical and experimental studies were undertaken to examine flow in both circular and rectangular flow loops. It was found that when a circular loop is heated at the bottom and cooled at the top, recirculation cells form at all input power fluxes. At fluxes between 0.1 W/cm 2 and 0.7 W/cm 2 the cells caused flow oscillations and reversals. With the circular loop heated from the side, no recirculation cells were observed at the power fluxes up to 1.5 W/cm. Boiling did not occur in the circular loop. For a rectangular loop heated and cooled on its vertical sides, no recirculation cells or flow reversals were seen. At input power fluxes above 1.2 W/cm 2 , periodic boiling in the heated side caused flow oscillations

  11. Influence of membrane properties on fouling in submerged membrane bioreactors

    NARCIS (Netherlands)

    van der Marel, P.; Zwijnenburg, A.; Kemperman, Antonius J.B.; Wessling, Matthias; Temmink, Hardy; van der Meer, Walterus Gijsbertus Joseph

    2010-01-01

    Polymeric flat-sheet membranes with different properties were used in filtration experiments with activated sludge from a pilot-scale MBR to investigate the influence of membrane pore size, surface porosity, pore morphology, and hydrophobicity on membrane fouling. An improved flux-step method was

  12. Interactions between laser and arc plasma during laser-arc hybrid welding of magnesium alloy

    Science.gov (United States)

    Liu, Liming; Chen, Minghua

    2011-09-01

    This paper presents the results of the investigation on the interactions between laser and arc plasma during laser-arc hybrid welding on magnesium alloy AZ31B using the spectral diagnose technique. By comparably analyzing the variation in plasma information (the shape, the electron temperature and density) of single tungsten inert gas (TIG) welding with the laser-arc hybrid welding, it is found that the laser affects the arc plasma through the keyhole forming on the workpiece. Depending on the welding parameters there are three kinds of interactions taking place between laser and arc plasma.

  13. Arcing and surface damage in DITE

    International Nuclear Information System (INIS)

    Goodall, D.H.J.; McCracken, G.M.

    1977-11-01

    An investigation into the arcing damage on surfaces exposed to plasmas in the DITE tokamak is described. It has been found that arcing occurs on the fixed limiters, on probes inserted into the plasma and on parts of the torus structure. For surfaces parallel to the toroidal field most of the arcs run across the surface orthogonal to the field direction. Observations in the scanning electron microscope show that the arc tracks are formed by a series of melted craters characteristic of cathode arc spots. The amount of metal removed from the surface is consistent with the concentration of metal observed in the plasma. In plasmas with hydrogen gas puffing during the discharge or with injection of low Z impurities, the arc tracks are observed to be much shallower than in normal low density discharges. Several types of surface damage other than arc tracks have also been observed on probes. These phenomena occur less frequently than arcing and appear to be associated with abnormal discharge conditions. (author)

  14. The next-generation ARC middleware

    DEFF Research Database (Denmark)

    Appleton, O.; Cameron, D.; Cernak, J.

    2010-01-01

    The Advanced Resource Connector (ARC) is a light-weight, non-intrusive, simple yet powerful Grid middleware capable of connecting highly heterogeneous computing and storage resources. ARC aims at providing general purpose, flexible, collaborative computing environments suitable for a range of use...

  15. The structure and singularities of arc complexes

    DEFF Research Database (Denmark)

    Penner, Robert

    A classical combinatorial fact is that the simplicial complex consisting of disjointly embedded chords in a convex planar polygon is a sphere. For any surface F with non-empty boundary, there is an analogous complex Arc(F) consisting of suitable equivalence classes of arcs in F connecting its bou...

  16. Verification of Timed-Arc Petri Nets

    DEFF Research Database (Denmark)

    Jacobsen, Lasse; Jacobsen, Morten; Møller, Mikael Harkjær

    2011-01-01

    of interesting theoretical properties distinguishing them from other time extensions of Petri nets. We shall give an overview of the recent theory developed in the verification of TAPN extended with features like read/transport arcs, timed inhibitor arcs and age invariants. We will examine in detail...

  17. Modeling and Simulation of Low Voltage Arcs

    NARCIS (Netherlands)

    Ghezzi, L.; Balestrero, A.

    2010-01-01

    Modeling and Simulation of Low Voltage Arcs is an attempt to improve the physical understanding, mathematical modeling and numerical simulation of the electric arcs that are found during current interruptions in low voltage circuit breakers. An empirical description is gained by refined electrical

  18. Risk assessment of metal vapor arcing

    Science.gov (United States)

    Hill, Monika C. (Inventor); Leidecker, Henning W. (Inventor)

    2009-01-01

    A method for assessing metal vapor arcing risk for a component is provided. The method comprises acquiring a current variable value associated with an operation of the component; comparing the current variable value with a threshold value for the variable; evaluating compared variable data to determine the metal vapor arcing risk in the component; and generating a risk assessment status for the component.

  19. Implementing RapidArc into clinical routine

    DEFF Research Database (Denmark)

    Van Esch, Ann; Huyskens, Dominique P; Behrens, Claus F

    2011-01-01

    With the increased commercial availability of intensity modulated arc therapy (IMAT) comes the need for comprehensive QA programs, covering the different aspects of this newly available technology. This manuscript proposes such a program for the RapidArc (RA) (Varian Medical Systems, Palo Alto...

  20. Arc generators of low-temperature plasma

    International Nuclear Information System (INIS)

    Krolikowski, Cz.; Niewiedzial, R.; Siwiec, J.

    1979-01-01

    This paper is a review of works concerning investigation and use of low-temperature plasma in arc plasma generators made in Electric Power Institute of PP. There are discussed: analytical approach to a problem of volt-current and operational characteristics of DC arc plasma generators, determination of limits of their stable work and possibilities of their use to technological aims. (author)

  1. Non-Intrusive Magneto-Optic Detecting System for Investigations of Air Switching Arcs

    International Nuclear Information System (INIS)

    Zhang Pengfei; Zhang Guogang; Dong Jinlong; Liu Wanying; Geng Yingsan

    2014-01-01

    In current investigations of electric arc plasmas, experiments based on modern testing technology play an important role. To enrich the testing methods and contribute to the understanding and grasping of the inherent mechanism of air switching arcs, in this paper, a non-intrusive detecting system is described that combines the magneto-optic imaging (MOI) technique with the solution to inverse electromagnetic problems. The detecting system works in a sequence of main steps as follows: MOI of the variation of the arc flux density over a plane, magnetic field information extracted from the magneto-optic (MO) images, arc current density distribution and spatial pattern reconstruction by inverting the resulting field data. Correspondingly, in the system, an MOI set-up is designed based on the Faraday effect and the polarization properties of light, and an intelligent inversion algorithm is proposed that involves simulated annealing (SA). Experiments were carried out for high current (2 kA RMS) discharge cases in a typical low-voltage switchgear. The results show that the MO detection system possesses the advantages of visualization, high resolution and response, and electrical insulation, which provides a novel diagnostics tool for further studies of the arc. (low temperature plasma)

  2. Novel non-equilibrium modelling of a DC electric arc in argon

    Science.gov (United States)

    Baeva, M.; Benilov, M. S.; Almeida, N. A.; Uhrlandt, D.

    2016-06-01

    A novel non-equilibrium model has been developed to describe the interplay of heat and mass transfer and electric and magnetic fields in a DC electric arc. A complete diffusion treatment of particle fluxes, a generalized form of Ohm’s law, and numerical matching of the arc plasma with the space-charge sheaths adjacent to the electrodes are applied to analyze in detail the plasma parameters and the phenomena occurring in the plasma column and the near-electrode regions of a DC arc generated in atmospheric pressure argon for current levels from 20 A up to 200 A. Results comprising electric field and potential, current density, heating of the electrodes, and effects of thermal and chemical non-equilibrium are presented and discussed. The current-voltage characteristic obtained is in fair agreement with known experimental data. It indicates a minimum for arc current of about 80 A. For all current levels, a field reversal in front of the anode accompanied by a voltage drop of (0.7-2.6) V is observed. Another field reversal is observed near the cathode for arc currents below 80 A.

  3. Novel non-equilibrium modelling of a DC electric arc in argon

    International Nuclear Information System (INIS)

    Baeva, M; Uhrlandt, D; Benilov, M S; Almeida, N A

    2016-01-01

    A novel non-equilibrium model has been developed to describe the interplay of heat and mass transfer and electric and magnetic fields in a DC electric arc. A complete diffusion treatment of particle fluxes, a generalized form of Ohm’s law, and numerical matching of the arc plasma with the space-charge sheaths adjacent to the electrodes are applied to analyze in detail the plasma parameters and the phenomena occurring in the plasma column and the near-electrode regions of a DC arc generated in atmospheric pressure argon for current levels from 20 A up to 200 A. Results comprising electric field and potential, current density, heating of the electrodes, and effects of thermal and chemical non-equilibrium are presented and discussed. The current–voltage characteristic obtained is in fair agreement with known experimental data. It indicates a minimum for arc current of about 80 A. For all current levels, a field reversal in front of the anode accompanied by a voltage drop of (0.7–2.6) V is observed. Another field reversal is observed near the cathode for arc currents below 80 A. (paper)

  4. Differential Response of Floating and Submerged Leaves of Longleaf Pondweed to Silver Ions

    Directory of Open Access Journals (Sweden)

    Nisha Shabnam

    2017-06-01

    Full Text Available In this study, we have investigated variations in the potential of floating and submerged leaves of longleaf pondweed (Potamogeton nodosus to withstand silver ion (Ag+-toxicity. Both floating and submerged leaves changed clear colorless AgNO3 solutions to colloidal brown in the presence of light. Transmission electron microscopy revealed the presence of distinct crystalline Ag-nanoparticles (Ag-NPs in these brown solutions. Powder X-ray diffraction pattern showed that Ag-NPs were composed of Ag0 and Ag2O. Photosystem (PS II efficiency of leaves declined upon exposure to Ag+ with a significantly higher decline in the submerged leaves than in the floating leaves. Similarly, Ag+ treatment caused a significant reduction in the carboxylase activity of the ribulose bisphosphate carboxylase/oxygenase in leaves. The reduction in this carboxylase activity was significantly higher in the submerged than in the floating leaves. Ag+ treatment also resulted in a significant decline in the levels of non-enzymatic and enzymatic antioxidants; the decline was significantly lower in the floating than in submerged leaves. X-ray photoelectron spectroscopy revealed the presence of Ag2O in these leaves. Inductively coupled plasma mass spectrometry analysis revealed a three-fold higher Ag content in the submerged than in floating leaves. Our study demonstrates that floating leaves of longleaf pondweed have a superior potential to counter Ag+-toxicity compared with submerged leaves, which could be due to superior potential of floating leaves to reduce Ag+ to less/non-toxic Ag0/Ag2O-nanoparticles/nanocomplexes. We suggest that modulating the genotype of longleaf pondweed to bear higher proportion of floating leaves would help in cleaning fresh water bodies contaminated with ionic forms of heavy metals.

  5. CYANOBACTERIA FOR MITIGATING METHANE EMISSION FROM SUBMERGED PADDY FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    Upasana Mishra; Shalini Anand [Department of Environmental Studies, Inderprastha Engineering College, Sahibabad, Ghaziabad (India)

    2008-09-30

    Atmospheric methane, a potent greenhouse gas with high absorption potential for infrared radiation, is responsible for one forth of the total anticipated warming. It is forming a major part of green house gases, next after carbon dioxide. Its concentration has been increasing alarmingly on an average at the rate of one percent per year. Atmospheric methane, originating mainly from biogenic sources such as paddy fields, natural wetlands and landfills, accounts for 15-20% of the world's total anthropogenic methane emission. With intensification of rice cultivation in coming future, methane emissions from paddy fields are anticipated to increase. India's share in world's rice production is next after to China and likewise total methane emission from paddy fields also. Methane oxidation through planktophytes, particularly microalgae which are autotrophic and abundant in rice rhizospheres, hold promise in controlling methane emission from submerged paddy fields. The present study is focused on the role of nitrogen fixing, heterocystous cyanobacteria and Azolla (a water fern harboring a cyanobacterium Anabaena azollae) as biological sink for headspace concentration of methane in flooded soils. In this laboratory study, soil samples containing five potent nitrogen fixer cyanobacterial strains from paddy fields, were examined for their methane reducing potential. Soil sample without cyanobacterial strain was tested and taken as control. Anabaena sp. was found most effective in inhibiting methane concentration by 5-6 folds over the control. Moist soil cores treated with chemical nitrogen, urea, in combination with cyanobacteria mixture, Azolla microphylla or cyanobacteria mixture plus Azolla microphylla exhibited significance reduction in the headspace concentration of methane than the soil cores treated with urea alone. Contrary to other reports, this study also demonstrates that methane oxidation in soil core samples from paddy fields was stimulated by

  6. Challenges for mass production of nematodes in submerged culture.

    Science.gov (United States)

    de la Torre, Mayra

    2003-08-01

    Nematodes of Steinernema and Heterorhabditis genera are used as agents in insect biocontrol programs. They are associated with specific bacteria which are also involved in the mechanism of pathogenicity and which are consumed by nematodes as living food. S. feltiae has various developmental stages in its life cycle, including four juvenile stages, adults and the free living form. During mating, males coil themselves around the female, which is around 1 cm long. Successful commercialization of nematode-bacteria biocontrol products depends on the ability to produce sufficient quantities of these products at competitive prices for a full pest control program. This could be feasible if high cell density submerged cultures are designed and implemented; however, major problems related to nematodes mass production in a bioreactor remain unsolved due to the lack of knowledge about the physiological aspects of the nematode, bacteria and nematode-bacteria association, interaction between the three phases present in the bioreactor (liquid, gas, nematodes-bacteria), possibility of mating under hydrodynamic stress conditions, etc. We have found that the two most important engineering aspects to take into account the mass propagation of nematodes are oxygen transfer rate and hydrodynamics to allow mating and to avoid mechanical damage of juveniles in stage 2. This article focuses on several aspects related to the fermentation system such as kinetics of growth, shear stress, hydrodynamics fields in the bioreactor and oxygen demand. Also, results published by other groups, together with those of our own, will be discussed in relation to the main challenges found during the fermentation process.

  7. Nonlinear interaction and wave breaking with a submerged porous structure

    Science.gov (United States)

    Hsieh, Chih-Min; Sau, Amalendu; Hwang, Robert R.; Yang, W. C.

    2016-12-01

    Numerical simulations are performed to investigate interactive velocity, streamline, turbulent kinetic energy, and vorticity perturbations in the near-field of a submerged offshore porous triangular structure, as Stokes waves of different heights pass through. The wave-structure interaction and free-surface breaking for the investigated flow situations are established based on solutions of 2D Reynolds Averaged Navier-Stokes equations in a Cartesian grid in combination with K-ɛ turbulent closure and the volume of fluid methodology. The accuracy and stability of the adopted model are ascertained by extensive comparisons of computed data with the existing experimental and theoretical findings and through efficient predictions of the internal physical kinetics. Simulations unfold "clockwise" and "anticlockwise" rotation of fluid below the trough and the crest of the viscous waves, and the penetrated wave energy creates systematic flow perturbation in the porous body. The interfacial growths of the turbulent kinetic energy and the vorticity appear phenomenal, around the apex of the immersed structure, and enhanced significantly following wave breaking. Different values of porosity parameter and two non-porous cases have been examined in combination with varied incident wave height to reveal/analyze the nonlinear flow behavior in regard to local spectral amplification and phase-plane signatures. The evolution of leading harmonics of the undulating free-surface and the vertical velocity exhibits dominating roles of the first and the second modes in inducing the nonlinearity in the post-breaking near-field that penetrates well below the surface layer. The study further suggests the existence of a critical porosity that can substantially enhance the wave-shoaling and interface breaking.

  8. Electric arc behaviour in dynamic magnetic fields

    International Nuclear Information System (INIS)

    Put'ko, V.F.

    2000-01-01

    The behaviour of an electric arc in different time-dependent (dynamic) magnetic fields was investigated. New possibilities were found for spatial and energy stabilisation of a discharge, for intensifying heat exchange, extending the electric arc and distributed control of electric arc plasma. Rotating, alternating and travelling magnetic fields were studied. It was found that under the effect of a relatively low frequency of variations of dynamic magnetic fields (f 1000 Hz) the arc stabilised at the axis of the discharge chamber, the pulsation level decreased and discharge stability increased. The borders between these two arc existence modes were formed by a certain critical field variation frequency the period of which was determined by the heat relaxation time of the discharge. (author)

  9. Low voltage arc formation in railguns

    Science.gov (United States)

    Hawke, R.S.

    1985-08-05

    A low voltage plasma arc is first established across the rails behind the projectile by switching a low voltage high current source across the rails to establish a plasma arc by vaporizing a fuse mounted on the back of the projectile, maintaining the voltage across the rails below the railgun breakdown voltage to prevent arc formation ahead of the projectile. After the plasma arc has been formed behind the projectile a discriminator switches the full energy bank across the rails to accelerate the projectile. A gas gun injector may be utilized to inject a projectile into the breech of a railgun. The invention permits the use of a gas gun or gun powder injector and an evacuated barrel without the risk of spurious arc formation in front of the projectile.

  10. Neogene displacements in the Solomon Islands Arc

    Science.gov (United States)

    Ridgway, J.

    1987-02-01

    The geology and present configuration of the Solomon Island arc can be explained in terms of the Neogene displacement of a single linear chain of islands. The central part of an original arc consisting of Bougainville, Choiseul, Santa Ysabel, Guadalcanal and San Cristobal was displaced to the northeast as a consequence of the attempted subduction of the Woodlark spreading system. Malaita arose on the northeastern side of the arc as a result of interaction between the arc and the Pacific Ocean floor and the volcanic islands of the New Georgia group formed to the southwest in response to the subduction of a spreading ridge, thus giving rise to the present double chain structure of the arc.

  11. Metal transfer during vacuum consumable arc remelting

    International Nuclear Information System (INIS)

    Zanner, F.J.

    1977-11-01

    A description of the vacuum consumable arc remelt process as related to solidification and a review of vacuum arc literature is presented. Metal transfer at arc lengths less than or equal to 3 cm was found to occur when liquid metal spikes hanging from the cathode form a low resistance bridge (drop short) by touching the anode and subsequently rupturing. During the bridge lifetime (0.0003 to 0.020 s) the arc is extinguished and all of the electrical power is directed through the molten bridge. The formation and rupture of these molten metal bridges are confirmed with electrical resistance measurements. At long arc lengths (greater than 10 cm) the spikes separate before touching the anode

  12. Stability of alternating current gliding arcs

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Salewski, Mirko; Leipold, Frank

    2014-01-01

    on Ohm’s law indicates that the critical length of alternating current (AC) gliding arc discharge columns can be larger than that of a corresponding direct current (DC) gliding arc. This finding is supported by previously published images of AC and DC gliding arcs. Furthermore, the analysis shows......A gliding arc is a quenched plasma that can be operated as a non-thermal plasma at atmospheric pressure and that is thus suitable for large-scale plasma surface treatment. For its practical industrial use the discharge should be extended stably in ambient air. A simple analytical calculation based...... that the critical length can be increased by increasing the AC frequency, decreasing the serial resistance and lowering the gas flow rate. The predicted dependence of gas flow rate on the arc length is experimentally demonstrated. The gap width is varied to study an optimal electrode design, since the extended non...

  13. Navigating environmental, economic, and technological trade-offs in the design and operation of submerged anaerobic membrane bioreactors (AnMBRs)

    KAUST Repository

    Pretel, R.

    2015-12-01

    © 2015 Elsevier Ltd. Anaerobic membrane bioreactors (AnMBRs) enable energy recovery from wastewater while simultaneously achieving high levels of treatment. The objective of this study was to elucidate how detailed design and operational decisions of submerged AnMBRs influence the technological, environmental, and economic sustainability of the system across its life cycle. Specific design and operational decisions evaluated included: solids retention time (SRT), mixed liquor suspended solids (MLSS) concentration, sludge recycling ratio (r), flux (J), and specific gas demand per membrane area (SGD). The possibility of methane recovery (both as biogas and as soluble methane in reactor effluent) and bioenergy production, nutrient recovery, and final destination of the sludge (land application, landfill, or incineration) were also evaluated. The implications of these design and operational decisions were characterized by leveraging a quantitative sustainable design (QSD) framework which integrated steady-state performance modeling across seasonal temperatures (using pilot-scale experimental data and the simulating software DESASS), life cycle cost (LCC) analysis, and life cycle assessment (LCA). Sensitivity and uncertainty analyses were used to characterize the relative importance of individual design decisions, and to navigate trade-offs across environmental, economic, and technological criteria. Based on this analysis, there are design and operational conditions under which submerged AnMBRs could be net energy positive and contribute to the pursuit of carbon negative wastewater treatment.

  14. The characteristic of twin-electrode TIG coupling arc pressure

    International Nuclear Information System (INIS)

    Leng Xuesong; Zhang Guangjun; Wu Lin

    2006-01-01

    The coupling arc of twin-electrode TIG (T-TIG) is a particular kind of arc, which is achieved through the coupling of two arcs generated from two insulated electrodes in the same welding torch. It is therefore different from the single arc of conventional TIG in its physical characteristics. This paper studies the distribution of T-TIG coupling arc pressure, and analyses the influences of welding current, arc length, the distance between electrode tips and electrode shape upon arc pressure on the basis of experiment. It is expected that the T-TIG welding method can be applied in high efficiency welding according to its low arc pressure

  15. Submergible barge retrievable storage and permanent disposal system for radioactive waste

    Science.gov (United States)

    Goldsberry, Fred L.; Cawley, William E.

    1981-01-01

    A submergible barge and process for submerging and storing radioactive waste material along a seabed. A submergible barge receives individual packages of radwaste within segregated cells. The cells are formed integrally within the barge, preferably surrounded by reinforced concrete. The cells are individually sealed by a concrete decking and by concrete hatch covers. Seawater may be vented into the cells for cooling, through an integral vent arrangement. The vent ducts may be attached to pumps when the barge is bouyant. The ducts are also arranged to promote passive ventilation of the cells when the barge is submerged. Packages of the radwaste are loaded into individual cells within the barge. The cells are then sealed and the barge is towed to the designated disposal-storage site. There, the individual cells are flooded and the barge will begin descent controlled by a powered submarine control device to the seabed storage site. The submerged barge will rest on the seabed permanently or until recovered by a submarine control device.

  16. Submerged karst landforms observed by multibeam bathymetric survey in Nagura Bay, Ishigaki Island, southwestern Japan

    Science.gov (United States)

    Kan, Hironobu; Urata, Kensaku; Nagao, Masayuki; Hori, Nobuyuki; Fujita, Kazuhiko; Yokoyama, Yusuke; Nakashima, Yosuke; Ohashi, Tomoya; Goto, Kazuhisa; Suzuki, Atsushi

    2015-01-01

    Submerged tropical karst features were discovered in Nagura Bay on Ishigaki Island in the southern Ryukyu Islands, Japan. The coastal seafloor at depths shallower than ~ 130 m has been subjected to repeated and alternating subaerial erosion and sedimentation during periods of Quaternary sea-level lowstands. We conducted a broadband multibeam survey in the central area of Nagura Bay (1.85 × 2.7 km) and visualized the high-resolution bathymetric results over a depth range of 1.6-58.5 m. Various types of humid tropical karst landforms were found to coexist within the bay, including fluviokarst, doline karst, cockpit karst, polygonal karst, uvalas, and mega-dolines. Although these submerged karst landforms are covered by thick postglacial reef and reef sediments, their shapes and sizes are distinct from those associated with coral reef geomorphology. The submerged landscape of Nagura Bay likely formed during multiple glacial and interglacial periods. According to our bathymetric results and the aerial photographs of the coastal area, this submerged karst landscape appears to have developed throughout Nagura Bay (i.e., over an area of approximately 6 × 5 km) and represents the largest submerged karst in Japan.

  17. Modified Application of Nitrogen Fertilizer for Increasing Rice Variety Tolerance toward Submergence Stress

    Directory of Open Access Journals (Sweden)

    Gribaldi Gribaldi

    2017-01-01

    Full Text Available This research was conducted from July to October 2015, using Randomized Block Design with two treatment factors and three replications for each treatment. The first factor was rice varieties (V: V1 = IR 64; V2 = Inpara 5. The second factor was fertilizer (N: N0: without submergence, all N fertilizer was given during planting; N1: all N fertilizer dose was given during planting; and N2: 1/2 dose of N fertilizer was given during planting; the rest was given at 42 days after planting. The submergence was during 7–14 days after planting; N3 = the entire dose of N fertilizer that was given during planting, N4 = 1/2 the dose of N fertilizer that was given during planting, and the rest was given at 42 days after planting. The submergence was during 7–14 and 28–35 days after planting. The results showed that the management of nitrogen fertilizer application had effect on rice growth and production which experienced dirty water submergence stress; the application of 1/2 dose of N fertilizer given during planting had the best effect on rice growth and production; the longer the submergence period for rice variety, the higher the effect on rice growth and production.

  18. Vegetative Propagule Pressure and Water Depth Affect Biomass and Evenness of Submerged Macrophyte Communities.

    Science.gov (United States)

    Li, Hong-Li; Wang, Yong-Yang; Zhang, Qian; Wang, Pu; Zhang, Ming-Xiang; Yu, Fei-Hai

    2015-01-01

    Vegetative propagule pressure may affect the establishment and structure of aquatic plant communities that are commonly dominated by plants capable of clonal growth. We experimentally constructed aquatic communities consisting of four submerged macrophytes (Hydrilla verticillata, Ceratophyllum demersum, Elodea nuttallii and Myriophyllum spicatum) with three levels of vegetative propagule pressure (4, 8 and 16 shoot fragments for communities in each pot) and two levels of water depth (30 cm and 70 cm). Increasing vegetative propagule pressure and decreasing water level significantly increased the growth of the submerged macrophyte communities, suggesting that propagule pressure and water depth should be considered when utilizing vegetative propagules to re-establish submerged macrophyte communities in degraded aquatic ecosystems. However, increasing vegetative propagule pressure and decreasing water level significantly decreased evenness of the submerged macrophyte communities because they markedly increased the dominance of H. verticillata and E. nuttallii, but had little impact on that of C. demersum and M. spicatum. Thus, effects of vegetative propagule pressure and water depth are species-specific and increasing vegetative propagule pressure under lower water level can facilitate the establishment success of submerged macrophyte communities.

  19. Vegetative Propagule Pressure and Water Depth Affect Biomass and Evenness of Submerged Macrophyte Communities.

    Directory of Open Access Journals (Sweden)

    Hong-Li Li

    Full Text Available Vegetative propagule pressure may affect the establishment and structure of aquatic plant communities that are commonly dominated by plants capable of clonal growth. We experimentally constructed aquatic communities consisting of four submerged macrophytes (Hydrilla verticillata, Ceratophyllum demersum, Elodea nuttallii and Myriophyllum spicatum with three levels of vegetative propagule pressure (4, 8 and 16 shoot fragments for communities in each pot and two levels of water depth (30 cm and 70 cm. Increasing vegetative propagule pressure and decreasing water level significantly increased the growth of the submerged macrophyte communities, suggesting that propagule pressure and water depth should be considered when utilizing vegetative propagules to re-establish submerged macrophyte communities in degraded aquatic ecosystems. However, increasing vegetative propagule pressure and decreasing water level significantly decreased evenness of the submerged macrophyte communities because they markedly increased the dominance of H. verticillata and E. nuttallii, but had little impact on that of C. demersum and M. spicatum. Thus, effects of vegetative propagule pressure and water depth are species-specific and increasing vegetative propagule pressure under lower water level can facilitate the establishment success of submerged macrophyte communities.

  20. Suspension of Egg Hatching Caused by High Humidity and Submergence in Spider Mites.

    Science.gov (United States)

    Ubara, Masashi; Osakabe, Masahiro

    2015-08-01

    We tested the effects of high humidity and submergence on egg hatching of spider mites. In both the high humidity and submergence treatments, many Tetranychus and Panonychus eggs did not hatch until after the hatching peak of the lower humidity or unsubmerged controls. However, after humidity decreased or water was drained, many eggs hatched within 1-3 h. This was observed regardless of when high humidity or submergence treatments were implemented: either immediately after oviposition or immediately before hatching was due. Normal eyespot formation was observed in most eggs in the high humidity and submergence treatments, which indicates that spider mite embryos develop even when eggs are underwater. Therefore, delays in hatching are not caused by delayed embryonic development. A delay in hatching was always observed in Panonychus citri (McGregor) but was more variable in Tetranychus urticae Koch and Tetranychus kanzawai Kishida. The high humidity and submergence treatments affected but did not suppress larval development in these species. In contrast, many Oligonychus eggs died following the high humidity treatments. In Tetranychus and Panonychus spider mites, suspension of egg hatching may mitigate the adverse effects of rainfall. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. Responses of bacterial community structure and denitrifying bacteria in biofilm to submerged macrophytes and nitrate

    Science.gov (United States)

    Zhang, Songhe; Pang, Si; Wang, Peifang; Wang, Chao; Guo, Chuan; Addo, Felix Gyawu; Li, Yi

    2016-10-01

    Submerged macrophytes play important roles in constructed wetlands and natural water bodies, as these organisms remove nutrients and provide large surfaces for biofilms, which are beneficial for nitrogen removal, particularly from submerged macrophyte-dominated water columns. However, information on the responses of biofilms to submerged macrophytes and nitrogen molecules is limited. In the present study, bacterial community structure and denitrifiers were investigated in biofilms on the leaves of four submerged macrophytes and artificial plants exposed to two nitrate concentrations. The biofilm cells were evenly distributed on artificial plants but appeared in microcolonies on the surfaces of submerged macrophytes. Proteobacteria was the most abundant phylum in all samples, accounting for 27.3-64.8% of the high-quality bacterial reads, followed by Chloroflexi (3.7-25.4%), Firmicutes (3.0-20.1%), Acidobacteria (2.7-15.7%), Actinobacteria (2.2-8.7%), Bacteroidetes (0.5-9.7%), and Verrucomicrobia (2.4-5.2%). Cluster analysis showed that bacterial community structure can be significantly different on macrophytes versus from those on artificial plants. Redundancy analysis showed that electrical conductivity and nitrate concentration were positively correlated with Shannon index and operational taxonomic unit (OTU) richness (log10 transformed) but somewhat negatively correlated with microbial density. The relative abundances of five denitrifying genes were positively correlated with nitrate concentration and electrical conductivity but negatively correlated with dissolved oxygen.

  2. Submerged macrophytes modify bacterial community composition in sediments in a large, shallow, freshwater lake.

    Science.gov (United States)

    Zhao, Da-Yong; Liu, Peng; Fang, Chao; Sun, Yi-Meng; Zeng, Jin; Wang, Jian-Qun; Ma, Ting; Xiao, Yi-Hong; Wu, Qinglong L

    2013-04-01

    Submerged aquatic macrophytes are an important part of the lacustrine ecosystem. In this study, the bacterial community compositions in the rhizosphere sediments from three kinds of submerged macrophytes (Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans) were investigated to determine whether submerged macrophytes could drive the variation of bacterial community in the eutrophic Taihu Lake, China. Molecular techniques, including terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified 16S rRNA gene and clone libraries, were employed to analyze the bacterial community compositions. Remarkable differences of the T-RFLP patterns were observed among the different samples, and the results of LIBSHUFF analysis also confirmed that the bacterial community compositions in the rhizosphere sediments of three kinds of submerged macrophytes were statistically different from that of the unvegetated sediment. Acidobacteria, Deltaproteobacteria, and Betaproteobacteria were the dominant bacterial groups in the rhizosphere sediments of Ceratophyllum demersum, Potamogeton crispus, and Vallisneria natans, respectively, accounting for 15.38%, 29.03%, and 18.00% of the total bacterial abundances. Our study demonstrated that submerged macrophytes could influence the bacterial community compositions in their rhizosphere sediments, suggesting that macrophytes have an effect on the cycling and transportation of nutrients in the freshwater lake ecosystem.

  3. Material impacts and heat flux characterization of an electrothermal plasma source with an applied magnetic field

    Science.gov (United States)

    Gebhart, T. E.; Martinez-Rodriguez, R. A.; Baylor, L. R.; Rapp, J.; Winfrey, A. L.

    2017-08-01

    To produce a realistic tokamak-like plasma environment in linear plasma device, a transient source is needed to deliver heat and particle fluxes similar to those seen in an edge localized mode (ELM). ELMs in future large tokamaks will deliver heat fluxes of ˜1 GW/m2 to the divertor plasma facing components at a few Hz. An electrothermal plasma source can deliver heat fluxes of this magnitude. These sources operate in an ablative arc regime which is driven by a DC capacitive discharge. An electrothermal source was configured with two pulse lengths and tested under a solenoidal magnetic field to determine the resulting impact on liner ablation, plasma parameters, and delivered heat flux. The arc travels through and ablates a boron nitride liner and strikes a tungsten plate. The tungsten target plate is analyzed for surface damage using a scanning electron microscope.

  4. Electric Arc Furnace Modeling with Artificial Neural Networks and Arc Length with Variable Voltage Gradient

    Directory of Open Access Journals (Sweden)

    Raul Garcia-Segura

    2017-09-01

    Full Text Available Electric arc furnaces (EAFs contribute to almost one third of the global steel production. Arc furnaces use a large amount of electrical energy to process scrap or reduced iron and are relevant to study because small improvements in their efficiency account for significant energy savings. Optimal controllers need to be designed and proposed to enhance both process performance and energy consumption. Due to the random and chaotic nature of the electric arcs, neural networks and other soft computing techniques have been used for modeling EAFs. This study proposes a methodology for modeling EAFs that considers the time varying arc length as a relevant input parameter to the arc furnace model. Based on actual voltages and current measurements taken from an arc furnace, it was possible to estimate an arc length suitable for modeling the arc furnace using neural networks. The obtained results show that the model reproduces not only the stable arc conditions but also the unstable arc conditions, which are difficult to identify in a real heat process. The presented model can be applied for the development and testing of control systems to improve furnace energy efficiency and productivity.

  5. Intensity-modulated arc therapy simplified

    International Nuclear Information System (INIS)

    Wong, Eugene; Chen, Jeff Z.; Greenland, Jonathan

    2002-01-01

    Purpose: We present a treatment planning strategy for intensity-modulated radiation therapy using gantry arcs with dynamic multileaf collimator, previously termed intensity-modulated arc therapy (IMAT). Methods and Materials: The planning strategy is an extension of the photon bar arc and asymmetric arc techniques and is classified into three levels of complexity, with increasing number of gantry arcs. This principle allows us to generalize the analysis of the number of arcs required for intensity modulation for a given treatment site. Using a phantom, we illustrate how the current technique is more flexible than the photon bar arc technique. We then compare plans from our strategy with conventional three-dimensional conformal treatment plans for three sites: prostate (prostate plus seminal vesicles), posterior pharyngeal wall, and chest wall. Results: Our strategy generates superior IMAT treatment plans compared to conventional three-dimensional conformal plans. The IMAT plans spare critical organs well, and the trade-off for simplicity is that the dose uniformity in the target volume may not rival that of true inverse treatment plans. Conclusions: The analyses presented in this paper give a better understanding of IMAT plans. Our strategy is easier to understand and more efficient in generating plans than inverse planning systems; our plans are also simpler to modify, and quality assurance is more intuitive

  6. Compact neutron flux monitor

    International Nuclear Information System (INIS)

    Madhavi, V.; Phatak, P.R.; Bahadur, C.; Bayala, A.K.; Jakati, R.K.; Sathian, V.

    2003-01-01

    Full text: A compact size neutron flux monitor has been developed incorporating standard boards developed for smart radiation monitors. The sensitivity of the monitors is 0.4cps/nV. It has been tested up to 2075 nV flux with standard neutron sources. It shows convincing results even in high flux areas like 6m away from the accelerator in RMC (Parel) for 106/107 nV. These monitors have a focal and remote display, alarm function with potential free contacts for centralized control and additional provision of connectivity via RS485/Ethernet. This paper describes the construction, working and results of the above flux monitor

  7. METHOD OF CONJUGATED CIRCULAR ARCS TRACING

    Directory of Open Access Journals (Sweden)

    N. Ageyev Vladimir

    2017-01-01

    Full Text Available The geometric properties of conjugated circular arcs connecting two points on the plane with set directions of tan- gent vectors are studied in the work. It is shown that pairs of conjugated circular arcs with the same conditions in frontier points create one-parameter set of smooth curves tightly filling all the plane. One of the basic properties of this set is the fact that all coupling points of circular arcs are on the circular curve going through the initially given points. The circle radius depends on the direction of tangent vectors. Any point of the circle curve, named auxiliary in this work, determines a pair of conjugated arcs with given boundary conditions. One more condition of the auxiliary circle curve is that it divides the plane into two parts. The arcs going from the initial point are out of the circle limited by this circle curve and the arcs coming to the final point are inside it. These properties are the basis for the method of conjugated circular arcs tracing pro- posed in this article. The algorithm is rather simple and allows to fulfill all the needed plottings using only the divider and ruler. Two concrete examples are considered. The first one is related to the problem of tracing of a pair of conjugated arcs with the minimal curve jump when going through the coupling point. The second one demonstrates the possibility of trac- ing of the smooth curve going through any three points on the plane under condition that in the initial and final points the directions of tangent vectors are given. The proposed methods of conjugated circular arcs tracing can be applied in solving of a wide variety of problems connected with the tracing of cam contours, for example pattern curves in textile industry or in computer-aided-design systems when programming of looms with numeric control.

  8. Tolerance of combined submergence and salinity in the halophytic stem-succulent Tecticornia pergranulata

    DEFF Research Database (Denmark)

    Colmer, T D; Vos, H; Pedersen, Ole

    2009-01-01

    pergranulata subsp. pergranulata (syn. Halosarcia pergranulata subsp. pergranulata). Growth and total sugars in succulent stems were assessed as a function of time after submergence. Underwater net photosynthesis, dark respiration, total sugars, glycinebetaine, Na(+), Cl(-) and K(+), in succulent stems, were...... assessed in a NaCl dose-response experiment. KEY RESULTS: Submerged plants ceased to grow, and tissue sugars declined. Photosynthesis by succulent stems was reduced markedly when underwater, as compared with in air. Capacity for underwater net photosynthesis (P(N)) was not affected by 10-400 mM Na......Cl, but it was reduced by 30 % at 800 mM. Dark respiration, underwater, increased in succulent stems at 200-800 mM NaCl, as compared with those at 10 mM NaCl. On an ethanol-insoluble dry mass basis, K(+) concentration in succulent stems of submerged plants was equal to that in drained controls, across all Na...

  9. Molecular characterization of the submergence response of Arabidopsis thaliana ecotype Columbia

    DEFF Research Database (Denmark)

    Lee, S.C.; Mustroph, A.; Sasidaharan, R.

    2011-01-01

    partial pressure of the petiole and root had stabilized at c. 6 and 0.1 kPa, respectively. As controls, plants were untreated or exposed to darkness. Following quantitative profiling of cellular mRNAs with the Affymetrix ATH1 platform, changes in the transcriptome in response to submergence, early...... darkness, and O2-deprivation were evaluated by fuzzy k-means clustering. This identified genes co-regulated at the conditional, developmental or organ-specific level. Mutants for 10 differentially expressed HYPOXIA-RESPONSIVE UNKNOWN PROTEIN (HUP) genes were screened for altered submergence tolerance....... • The analysis identified 34 genes that were ubiquitously co-regulated by submergence and O2 deprivation. The biological functions of these include signaling, transcription, and anaerobic energy metabolism. HUPs comprised 40% of the co-regulated transcripts and mutants of seven of these genes were significantly...

  10. Plasma instability of a vacuum arc centrifuge

    International Nuclear Information System (INIS)

    Hole, M.J.; Dallaqua, R.S.; Simpson, S.W.; Del Bosco, E.

    2002-01-01

    Ever since conception of the vacuum arc centrifuge in 1980, periodic fluctuations in the ion saturation current and floating potential have been observed in Langmuir probe measurements in the rotation region of a vacuum arc centrifuge. In this work we develop a linearized theoretical model to describe a range of instabilities in the vacuum arc centrifuge plasma column, and then test the validity of the description through comparison with experiment. We conclude that the observed instability is a 'universal' instability, driven by the density gradient, in a plasma with finite conductivity

  11. Arc pressure control in GTA welding

    International Nuclear Information System (INIS)

    Cook, G.E.; Wells, F.M.; Levick, P.C.

    1986-01-01

    Relationships are established between the peak current of a pulsed, rectangular current waveform and the pulse current duty cycle under conditions of constant arc power. By appropriate choice of these interrelated parameters, it is shown that the arc pressure may be varied over a wide range even though the arc power is held constant. The methodology is suggested as a means of countering the effect of gravity in 5-G welding, while maintaining constant heat input to the weld. Combined with appropriate penetration sensors, the methodology is additionally suggested as a means of controlling penetration

  12. Arc saw and its application to decommissioning

    International Nuclear Information System (INIS)

    Deichelbohrer, P.R.

    1982-01-01

    The arc saw is a toothless, circular saw that cuts by arc erosion. A model was built to study the arc saw's usefulness in cutting up radioactively contaminated metal scrap. It was chosen because it cuts with very little contact to the work piece and because cutting is not affected by material hardness. After installation of several improvements it was found it could cut almost any combination of metals and that clamping or fixturing requirements were minimum. Cutting proceeds rapidly and efficiently. 10 figures

  13. Implementation av spridningsmodell i ArcGIS

    OpenAIRE

    Jou, Javid

    2012-01-01

    The project involves implementing a finished dispersion model into ArcGIS. The goal of the tool is to show how dangerous and toxic substances will travel in the ground after long periods. The goal of the project is to understand GIS in general, what it is used for and gain an insight into how developing tools for ArcGIS is, what challenges might exists. Understanding the type of data that can be stored and accessed in ArcGIS a long with the tools and functionality offered by the system when u...

  14. Modelling of plasma generation and expansion in a vacuum arc: application to the vacuum arc remelting process

    International Nuclear Information System (INIS)

    Chapelle, P.; Bellot, J.P.; Duval, H.; Jardy, A.; Ablitzer, D.

    2002-01-01

    As part of a complete theoretical description of the behaviour of the electric arc in the vacuum arc remelting process, a model has been developed for the column of plasma generated by a single cluster of cathode spots. The model combines a kinetic approach, taking into account the formation of the plasma in the cathodic region, and a hydrodynamic approach, describing the expansion of the plasma in the vacuum between the electrodes. The kinetic model is based on a system of Boltzmann-Vlasov-Poisson equations and uses a particle-type simulation procedure, combining the PIC (particle in cell) and FPM (finite point set method) methods. In the two-dimensional hydrodynamic model, the plasma is assimilated to a mixture of two continuous fluids (the electrons and the ions), each described by a system of coupled transport equations. Finally, a simplified method has been defined for calculating the electric current density and the energy flux density transmitted by the plasma to the anode. The results of the numerical simulation presented are consistent with a certain number of experimental data available in the literature. In particular, the model predicts a percentage of the electric power of the cluster transmitted to the anode (25%) in good agreement with the value indicated in the literature. (author)

  15. Elevation dynamics in a restored versus a submerging salt marsh in Long Island Sound

    Science.gov (United States)

    Anisfeld, Shimon C.; Hill, Troy D.; Cahoon, Donald R.

    2016-01-01

    Accelerated sea-level rise (SLR) poses the threat of salt marsh submergence, especially in marshes that are relatively low-lying. At the same time, restoration efforts are producing new low-lying marshes, many of which are thriving and avoiding submergence. To understand the causes of these different fates, we studied two Long Island Sound marshes: one that is experiencing submergence and mudflat expansion, and one that is undergoing successful restoration. We examined sedimentation using a variety of methods, each of which captures different time periods and different aspects of marsh elevation change: surface-elevation tables, marker horizons, sediment cores, and sediment traps. We also studied marsh hydrology, productivity, respiration, nutrient content, and suspended sediment. We found that, despite the expansion of mudflat in the submerging marsh, the areas that remain vegetated have been gaining elevation at roughly the rate of SLR over the last 10 years. However, this elevation gain was only possible thanks to an increase in belowground volume, which may be a temporary response to waterlogging. In addition, accretion rates in the first half of the twentieth century were much lower than current rates, so century-scale accretion in the submerging marsh was lower than SLR. In contrast, at the restored marsh, accretion rates are now averaging about 10 mm yr−1 (several times the rate of SLR), much higher than before restoration. The main cause of the different trajectories at the two marshes appeared to be the availability of suspended sediment, which was much higher in the restored marsh. We considered and rejected alternative hypotheses, including differences in tidal flooding, plant productivity, and nutrient loading. In the submerging marsh, suspended and deposited sediment had relatively high organic content, which may be a useful indicator of sediment starvation.

  16. DMSP optical and electron measurements in the vicinity of polar cap arcs

    International Nuclear Information System (INIS)

    Hardy, D.A.; Burke, W.J.; Gussenhoven, M.S.

    1982-01-01

    We have completed an extensive analysis of the electron and optical data from the DMSP satellites for an external period of polar cap arc occurrences on December 12, 1977. The polar cap arcs are observed in three distinct intervals in a period of quieting after a time of intense substorm activity. The observation of polar cap arcs is associated with the admittance of large and variable fluxes of low-energy electrons into a major portion of both the northern and southern hemisphere polar caps. These fluxes fall into the following categories: First, nearly Maxwellian distributions of electrons with temperatures between 50 eV and 200 eV and number densities varying from 0.03/cm 3 to 4/cm 3 . The highest densities are found at the poleward boundary of the diffuse aurorae and near the visible polar cap arcs. The lowest densities are associated with the polar rain. Second, distributions of electrons peaked between 50 eV and 200 eV. These distributions result from accelertion of the cold Maxwellian distribution through a potential of 50 to 200 V without any heating of the electrons. Third, distributions of electrons displaying two populations; an intense low-energy component with a temperature of approx.20 eV and a much weaker high-energy component with a temperature of 180 eV. We interpret such distributions as evidence of direct admittance of magnetosheath electrons into the polar cap. Fourth,, distributions of electrons peaked at approx.1 keV. These distributions produce the visible arcs. They result from the acceleration of a two-component electron population with temperatures of 100 and 350 eV through a potential drop of approx.750 V

  17. Across-arc versus along-arc Sr-Nd-Pb isotope variations in the Ecuadorian volcanic arc

    Science.gov (United States)

    Ancellin, Marie-Anne; Samaniego, Pablo; Vlastélic, Ivan; Nauret, François; Gannoun, Adbelmouhcine; Hidalgo, Silvana

    2017-03-01

    Previous studies of the Ecuadorian arc (1°N-2°S) have revealed across-arc geochemical trends that are consistent with a decrease in mantle melting and slab dehydration away from the trench. The aim of this work is to evaluate how these processes vary along the arc in response to small-scale changes in the age of the subducted plate, subduction angle, and continental crustal basement. We use an extensive database of 1437 samples containing 71 new analyses, of major and trace elements as well as Sr-Nd-Pb isotopes from Ecuadorian and South Colombian volcanic centers. Large geochemical variations are found to occur along the Ecuadorian arc, in particular along the front arc, which encompasses 99% and 71% of the total variations in 206Pb/204Pb and 87Sr/86Sr ratios of Quaternary Ecuadorian volcanics, respectively. The front arc volcanoes also show two major latitudinal trends: (1) the southward increase of 207Pb/204Pb and decrease of 143Nd/144Nd reflect more extensive crustal contamination of magma in the southern part (up to 14%); and (2) the increase of 206Pb/204Pb and decrease of Ba/Th away from ˜0.5°S result from the changing nature of metasomatism in the subarc mantle wedge with the aqueous fluid/siliceous slab melt ratio decreasing away from 0.5°S. Subduction of a younger and warmer oceanic crust in the Northern part of the arc might promote slab melting. Conversely, the subduction of a colder oceanic crust south of the Grijalva Fracture Zone and higher crustal assimilation lead to the reduction of slab contribution in southern part of the arc.

  18. Wave energy absorption by a submerged air bag connected to a rigid float

    DEFF Research Database (Denmark)

    Kurniawan, Adi; Chaplin, J. R.; Hann, M. R.

    2017-01-01

    A new wave energy device features a submerged ballasted air bag connected at the top to a rigid float. Under wave action, the bag expands and contracts, creating a reciprocating air flow through a turbine between the bag and another volume housed within the float. Laboratory measurements are gene......A new wave energy device features a submerged ballasted air bag connected at the top to a rigid float. Under wave action, the bag expands and contracts, creating a reciprocating air flow through a turbine between the bag and another volume housed within the float. Laboratory measurements...

  19. Primary cosmic ray flux

    Energy Technology Data Exchange (ETDEWEB)

    Stanev, Todor

    2001-05-01

    We discuss the primary cosmic ray flux from the point of view of particle interactions and production of atmospheric neutrinos. The overall normalization of the cosmic ray flux and its time variations and site dependence are major ingredients of the atmospheric neutrino predictions and the basis for the derivation of the neutrino oscillation parameters.

  20. Flux cutting in superconductors

    International Nuclear Information System (INIS)

    Campbell, A M

    2011-01-01

    This paper describes experiments and theories of flux cutting in superconductors. The use of the flux line picture in free space is discussed. In superconductors cutting can either be by means of flux at an angle to other layers of flux, as in longitudinal current experiments, or due to shearing of the vortex lattice as in grain boundaries in YBCO. Experiments on longitudinal currents can be interpreted in terms of flux rings penetrating axial lines. More physical models of flux cutting are discussed but all predict much larger flux cutting forces than are observed. Also, cutting is occurring at angles between vortices of about one millidegree which is hard to explain. The double critical state model and its developments are discussed in relation to experiments on crossed and rotating fields. A new experiment suggested by Clem gives more direct information. It shows that an elliptical yield surface of the critical state works well, but none of the theoretical proposals for determining the direction of E are universally applicable. It appears that, as soon as any flux flow takes place, cutting also occurs. The conclusion is that new theories are required. (perspective)

  1. 49 CFR 195.226 - Welding: Arc burns.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false Welding: Arc burns. 195.226 Section 195.226 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY... PIPELINE Construction § 195.226 Welding: Arc burns. (a) Each arc burn must be repaired. (b) An arc burn may...

  2. Modeling of the anode surface deformation in high-current vacuum arcs with AMF contacts

    International Nuclear Information System (INIS)

    Huang, Xiaolong; Wang, Lijun; Deng, Jie; Jia, Shenli; Qin, Kang; Shi, Zongqian

    2016-01-01

    A high-current vacuum arc subjected to an axial magnetic field is maintained in a diffuse status. With an increase in arc current, the energy carried by the arc column to the anode becomes larger and finally leads to the anode temperature exceeding the melting point of the anode material. When the anode melting pool is formed, and the rotational plasma of the arc column delivers its momentum to the melting pool, the anode melting pool starts to rotate and also flow outwards along the radial direction, which has been photographed by some researchers using high-speed cameras. In this paper, the anode temperature and melting status is calculated using the melting and solidification model. The swirl flow of the anode melting pool and deformation of the anode is calculated using the magneto-hydrodynamic (MHD) model with the volume of fraction (VOF) method. All the models are transient 2D axial-rotational symmetric models. The influence of the impaction force of the arc plasma, electromagnetic force, viscosity force, and surface tension of the liquid metal are all considered in the model. The heat flux density injected into the anode and the arc pressure are obtained from the 3D numerical simulation of the high-current vacuum arc using the MHD model, which gives more realistic parameters for the anode simulation. Simulation results show that the depth of the anode melting pool increases with an increase in the arc current. Some droplets sputter out from the anode surface, which is caused by the inertial centrifugal force of the rotational melting pool and strong plasma pressure. Compared with the previous anode melting model without consideration of anode deformation, when the deformation and swirl flow of the anode melting pool are considered, the anode temperature is relatively lower, and just a little more than the melting point of Cu. This is because of liquid droplets sputtering out of the anode surface taking much of the energy away from the anode surface. The

  3. Biological control of phytoplankton by the subtropical submerged macrophytes Egeria densa and Potamogeton illinoensis: a mesocosm study

    NARCIS (Netherlands)

    Vanderstukken, M.; Mazzeo, N.; Colen, W.; Declerck, S.A.J.; Muylaert, K.

    2011-01-01

    1. In temperate regions, submerged macrophytes can hamper phytoplankton blooms. Such an effect could arise directly, for instance via allelopathy, or indirectly, via competition for nutrients or the positive interaction between submerged macrophytes and zooplankton grazing. However, there is some

  4. Heat flux microsensor measurements

    Science.gov (United States)

    Terrell, J. P.; Hager, J. M.; Onishi, S.; Diller, T. E.

    1992-01-01

    A thin-film heat flux sensor has been fabricated on a stainless steel substrate. The thermocouple elements of the heat flux sensor were nickel and nichrome, and the temperature resistance sensor was platinum. The completed heat flux microsensor was calibrated at the AEDC radiation facility. The gage output was linear with heat flux with no apparent temperature effect on sensitivity. The gage was used for heat flux measurements at the NASA Langley Vitiated Air Test Facility. Vitiated air was expanded to Mach 3.0 and hydrogen fuel was injected. Measurements were made on the wall of a diverging duct downstream of the injector during all stages of the hydrogen combustion tests. Because the wall and the gage were not actively cooled, the wall temperature reached over 1000 C (1900 F) during the most severe test.

  5. Mass development of monospecific submerged macrophyte vegetation after the restoration of shallow lakes: Roles of light, sediment nutrient levels, and propagule density

    NARCIS (Netherlands)

    Verhofstad, M.J.J.M.; Alirangues Núñez, M. M.; Reichman, E. P.; van Donk, E.; Lamers, L. P.M.; Bakker, E. S.

    2017-01-01

    After restoration, eutrophicated shallow freshwaters may show mass development of only one or two submerged macrophyte species, lowering biodiversity and hampering recreation. It is unclear which environmental factors govern this high percentage of the volume inhabited (PVI2) by submerged

  6. Sitka, Alaska 9 arc-second DEM

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Sitka, Alaska Elevation Grid provides bathymetric data in ASCII raster format of 9 arc-second resolution in geographic coordinates. This grid is strictly for...

  7. Retinal injury from a welding arc

    International Nuclear Information System (INIS)

    Naidoff, M.A.; Sliney, D.H.

    1974-01-01

    An 18-year-old man stared at a welding arc for approximately ten minutes, sustaining moderate facial erythema, keratoconjunctivitis, marked visual loss, a pupillary abnormality, and a retinal injury accompanied by a dense central scotoma and peripheral field constriction. A residual, partially pigmented foveal lesion remained after 16 months, with normal visual acuity. Since the degree of keratoconjunctivitis and facial erythema was known, we substantiated the duration of exposure to the arc by weighting the known action spectrum of moderate ultraviolet erythema with the ultraviolet spectral irradiance measurements of the arc. From the radiometric measurements of the visible brightness and visible and near infrared spectrum of the arc and from knowledge of pupil size, we calculated the retinal exposure dose rate, which was less than normally considered necessary to produce a chorioretinal burn. This case may provide a clinical example of photic maculopathy recently reported in experimental investigations

  8. Sitka, Alaska 1 arc-second DEM

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Sitka, Alaska Elevation Grid provides bathymetric data in ASCII raster format of 1 arc-second resolution in geographic coordinates. This grid is strictly for...

  9. Arc tracks on nanostructured surfaces after microbreakdowns

    International Nuclear Information System (INIS)

    Sinelnikov, D; Bulgadaryan, D; Kolodko, D; Kurnaev, V; Hwangbo, D; Ohno, N; Kajita, S

    2016-01-01

    Studying of initial steps of unipolar arc ignition process is important for reduction of probability of arcing between the plasma and the wall in thermonuclear devices. Tungsten nano-fuzz surface formed by helium plasma irradiation at high fluences and temperatures is a perfect material for arc ignition. Snowflake-like craters were detected on the fuzzy surfaces after short micro-breakdowns. Such sort of craters have not been observed before on any other metallic surfaces. These specific traces are formed due to unique properties of the fuzz structure. The nano-fuzz could be easily melted and vaporized by micro-breakdown current, due to its porosity and bad thermal conductivity, and formation of low conducting metallic vapour under the cathode spot causes discharge movement to the nearest place. Thus, even low current arc can easily move and leave traces, which could be easily observed by a secondary electron microscope. (paper)

  10. Sitka, Alaska 3 arc-second DEM

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Sitka, Alaska Elevation Grid provides bathymetric data in ASCII raster format of 3 arc-second resolution in geographic coordinates. This grid is strictly for...

  11. Seward, Alaska 3 arc-second DEM

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The 3 arc-second Seward Alaska Elevation Grid provides bathymetric data in ASCII raster format of 2.67-second resolution in geographic coordinates. This grid is...

  12. Seldovia, Alaska 1 arc-second DEM

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Seldovia, Alaska Elevation Grid provides bathymetric data in ASCII raster format of 1 arc-second resolution in geographic coordinates. This grid is strictly for...

  13. Basins in ARC-continental collisions

    Science.gov (United States)

    Draut, Amy E.; Clift, Peter D.; Busby, Cathy; Azor, Antonio

    2012-01-01

    Arc-continent collisions occur commonly in the plate-tectonic cycle and result in rapidly formed and rapidly collapsing orogens, often spanning just 5-15 My. Growth of continental masses through arc-continent collision is widely thought to be a major process governing the structural and geochemical evolution of the continental crust over geologic time. Collisions of intra-oceanic arcs with passive continental margins (a situation in which the arc, on the upper plate, faces the continent) involve a substantially different geometry than collisions of intra-oceanic arcs with active continental margins (a situation requiring more than one convergence zone and in which the arc, on the lower plate, backs into the continent), with variable preservation potential for basins in each case. Substantial differences also occur between trench and forearc evolution in tectonically erosive versus tectonically accreting margins, both before and after collision. We examine the evolution of trenches, trench-slope basins, forearc basins, intra-arc basins, and backarc basins during arc-continent collision. The preservation potential of trench-slope basins is low; in collision they are rapidly uplifted and eroded, and at erosive margins they are progressively destroyed by subduction erosion. Post-collisional preservation of trench sediment and trench-slope basins is biased toward margins that were tectonically accreting for a substantial length of time before collision. Forearc basins in erosive margins are usually floored by strong lithosphere and may survive collision with a passive margin, sometimes continuing sedimentation throughout collision and orogeny. The low flexural rigidity of intra-arc basins makes them deep and, if preserved, potentially long records of arc and collisional tectonism. Backarc basins, in contrast, are typically subducted and their sediment either lost or preserved only as fragments in melange sequences. A substantial proportion of the sediment derived from

  14. Metal Vapor Arcing Risk Assessment Tool

    Science.gov (United States)

    Hill, Monika C.; Leidecker, Henning W.

    2010-01-01

    The Tin Whisker Metal Vapor Arcing Risk Assessment Tool has been designed to evaluate the risk of metal vapor arcing and to help facilitate a decision toward a researched risk disposition. Users can evaluate a system without having to open up the hardware. This process allows for investigating components at risk rather than spending time and money analyzing every component. The tool points to a risk level and provides direction for appropriate action and documentation.

  15. Managing Data and ArcGIS

    OpenAIRE

    Farr, Lucy

    2011-01-01

    Glenn Jobson (CRASSH) produced and edited this video in collaboration with the Incremental project. ESRI's ArcGIS data, and other vector data system, are highly vulnerable to partial or complete data loss over time because as the company makes frequent software updates, and the data themselves have so many moving parts. In this presentation, Lucy Farr (McDonald Institute for Archaeological Research) describes her experiences using ArcGIS, lessons learnt, and recommendations for best practi...

  16. The influence of permanently submerged macrophytes on sediment mercury distribution, mobility and methylation potential in a brackish Norwegian fjord.

    Science.gov (United States)

    Olsen, Marianne; Schaanning, Morten Thorne; Braaten, Hans Fredrik Veiteberg; Eek, Espen; Moy, Frithjof E; Lydersen, Espen

    2018-01-01

    Macrophytes are shown to affect the microbial activity in different aqueous environments, with an altering of the sediment cycling of mercury (Hg) as a potential effect. Here, we investigated how a meadow with permanently submerged macrophytes in a contaminated brackish fjord in southern Norway influenced the conditions for sulfate reducing microbial activity, the methyl-Hg (MeHg) production and the availability of MeHg. Historically discharged Hg from a chlor-alkali plant (60-80tons, 1947-1987) was evident through high Hg concentrations (491mgTot-Hgkg -1 , 268μgMeHgkg -1 ) in intermediate sediment depths (10-20cm) outside of the meadow, with reduced concentrations within the meadow. Natural recovery of the fjord was revealed by lower sediment surface concentrations (1.9-15.5mgTot-Hgkg -1 , 1.3-3.2μgMeHgkg -1 ). Within the meadow, vertical gradients of sediment hydrogen sulfide (H 2 S) E h and pH suggested microbial sulfate reduction in 2-5cm depths, coinciding with peak values of relative MeHg levels (0.5% MeHg). We assume that MeHg production rates was stimulated by the supply and availability of organic carbon, microbial activity and a sulfide oxidizing agent (e.g. O 2 ) within the rhizosphere. Following this, % MeHg in sediment (0-5cm) within the meadow was approximately 10× higher compared to outside the meadow. Further, enhanced availability of MeHg within the meadow was demonstrated by significantly higher fluxes (p<0.01) from sediment to overlying water (0.1-0.6ngm -2 d -1 ) compared to sediment without macrophytes (0.02-0.2ngm -2 d -1 ). Considering the productivity and species richness typical for such habitats, submerged macrophyte meadows located within legacy Hg contaminated sediment sites may constitute important entry points for MeHg into food webs. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Leaf gas films delay salt entry and enhance underwater photosynthesis and internal aeration of Melilotus siculus submerged in saline water

    DEFF Research Database (Denmark)

    Teakle, Natasha Lea; Colmer, Timothy David; Pedersen, Ole

    2014-01-01

    A combination of flooding and salinity is detrimental to most plants. We studied tolerance of complete submergence in saline water for Melilotus siculus, an annual legume with superhydrophobic leaf surfaces that retain gas films when under water. M. siculus survived complete submergence of 1 week...... at low salinity (up to 50 mol m(-3) NaCl), but did not recover following de-submergence from 100 mol m(-3) NaCl. The leaf gas films protected against direct salt ingress into the leaves when submerged in saline water, enabling underwater photosynthesis even after 3 d of complete submergence. By contrast......, leaves with the gas films experimentally removed suffered from substantial Na(+) and Cl(-) intrusion and lost the capacity for underwater photosynthesis. Similarly, plants in saline water and without gas films lost more K(+) than those with intact gas films. This study has demonstrated that leaf gas...

  18. Optical radiative properties of ablating polymers exposed to high-power arc plasmas

    Science.gov (United States)

    Becerra, Marley; Pettersson, Jonas

    2018-03-01

    The radiative properties of polymers exposed to high-intensity radiation are of importance for the numerical simulation of arc-induced ablation. The paper investigates the optical properties of polymethylmethacrylate PMMA and polyamide PA6 films exposed to high-power arc plasmas, which can cause ablation of the material. A four-flux radiative approximation is first used to estimate absorption and scattering coefficients of the tested materials in the ultraviolet (UV) and in the visible (VIS) ranges from spectrophotometric measurements. The temperature-induced variation of the collimated transmissivity of the polymers is also measured from room temperature to the glass temperature of PMMA and the melting temperature of PA6. Furthermore, band-averaged absorption and scattering coefficients of non-ablating and ablating polymers are estimated from the UV to the short-wavelength infrared (SWIR), covering the range of interest for the simulation of arc-induced ablation. These estimates are obtained from collimated transmissivities measured with an additional in situ photometric system that uses a high-power, transient arc plasma to both illuminate the samples and to induce ablation. It is shown that the increase in the bulk temperature of PA6 leads to a strong reversible increase in collimated transmissivity, significantly reducing the absorption and scattering coefficients of the material. A weaker but opposite effect of temperature on the optical properties is found in PMMA. As a consequence, it is suggested that the absorption coefficient of polymers used for arc-induced ablation estimates should not be taken directly from direct collimated transmissivity measurements at room temperature. The band-averaged radiation measurements also show that the layer of products released by ablation of PMMA produces scattering radiation losses mainly in the VIS-SWIR ranges, which are only a small fraction of the total incident arc radiation. In a similar manner, the ablation layer

  19. ATLAS DDM integration in ARC

    International Nuclear Information System (INIS)

    Behrmann, G; Cameron, D; Ellert, M; Kleist, J; Taga, A

    2008-01-01

    The Nordic Data Grid Facility (NDGF) consists of Grid resources running ARC middleware in Denmark, Finland, Norway and Sweden. These resources serve many virtual organisations and contribute a large fraction of total worldwide resources for the ATLAS experiment, whose data is distributed and managed by the DQ2 software. Managing ATLAS data within NDGF and between NDGF and other Grids used by ATLAS (the Enabling Grids for E-sciencE Grid and the Open Science Grid) presents a unique challenge for several reasons. Firstly, the entry point for data, the Tier 1 centre, is physically distributed among heterogeneous resources in several countries and yet must present a single access point for all data stored within the centre. The middleware framework used in NDGF differs significantly from other Grids, specifically in the way that all data movement and registration is performed by services outside the worker node environment. Also, the service used for cataloging the location of data files is different from other Grids but must still be useable by DQ2 and ATLAS users to locate data within NDGF. This paper presents in detail how we solve these issues to allow seamless access worldwide to data within NDGF

  20. Klystron Gun Arcing and Modulator Protection

    International Nuclear Information System (INIS)

    Gold, S

    2004-01-01

    The demand for 500 kV and 265 amperes peak to power an X-Band klystron brings up protection issues for klystron faults and the energy dumped into the arc from the modulator. This situation is made worse when more than one klystron will be driven from a single modulator, such as the existing schemes for running two and eight klystrons. High power pulsed klystrons have traditionally be powered by line type modulators which match the driving impedance with the load impedance and therefore current limit at twice the operating current. Multiple klystrons have the added problems of a lower modulator source impedance and added stray capacitance, which converts into appreciable energy at high voltages like 500kV. SLAC has measured the energy dumped into klystron arcs in a single and dual klystron configuration at the 400 to 450 kV level and found interesting characteristics in the arc formation. The author will present measured data from klystron arcs powered from line-type modulators in several configurations. The questions arise as to how the newly designed solid-state modulators, running multiple tubes, will react to a klystron arc and how much energy will be dumped into the arc

  1. Recent ARC developments: Through modularity to interoperability

    International Nuclear Information System (INIS)

    Smirnova, O; Cameron, D; Ellert, M; Groenager, M; Johansson, D; Kleist, J; Dobe, P; Joenemo, J; Konya, B; Fraagaat, T; Konstantinov, A; Nilsen, J K; Saada, F Ould; Qiang, W; Read, A; Kocan, M; Marton, I; Nagy, Zs; Moeller, S; Mohn, B

    2010-01-01

    The Advanced Resource Connector (ARC) middleware introduced by NorduGrid is one of the basic Grid solutions used by scientists worldwide. While being well-proven in daily use by a wide variety of scientific applications at large-scale infrastructures like the Nordic DataGrid Facility (NDGF) and smaller scale projects, production ARC of today is still largely based on conventional Grid technologies and custom interfaces introduced a decade ago. In order to guarantee sustainability, true cross-system portability and standards-compliance based interoperability, the ARC community undertakes a massive effort of implementing modular Web Service (WS) approach into the middleware. With support from the EU KnowARC project, new components were introduced and the existing key ARC services got extended with WS technology based standard-compliant interfaces following a service-oriented architecture. Such components include the hosting environment framework, the resource-coupled execution service, the re-engineered client library, the self-healing storage solution and the peer-to-peer information system, to name a few. Gradual introduction of these new services and client tools into the production middleware releases is carried out together with NDGF and thus ensures a smooth transition to the next generation Grid middleware. Standard interfaces and modularity of the new component design are essential for ARC contributions to the planned Universal Middleware Distribution of the European Grid Initiative.

  2. Recent ARC developments: Through modularity to interoperability

    Energy Technology Data Exchange (ETDEWEB)

    Smirnova, O; Cameron, D; Ellert, M; Groenager, M; Johansson, D; Kleist, J [NDGF, Kastruplundsgade 22, DK-2770 Kastrup (Denmark); Dobe, P; Joenemo, J; Konya, B [Lund University, Experimental High Energy Physics, Institute of Physics, Box 118, SE-22100 Lund (Sweden); Fraagaat, T; Konstantinov, A; Nilsen, J K; Saada, F Ould; Qiang, W; Read, A [University of Oslo, Department of Physics, P. O. Box 1048, Blindern, N-0316 Oslo (Norway); Kocan, M [Pavol Jozef Safarik University, Faculty of Science, Jesenna 5, SK-04000 Kosice (Slovakia); Marton, I; Nagy, Zs [NIIF/HUNGARNET, Victor Hugo 18-22, H-1132 Budapest (Hungary); Moeller, S [University of Luebeck, Inst. Of Neuro- and Bioinformatics, Ratzeburger Allee 160, D-23538 Luebeck (Germany); Mohn, B, E-mail: oxana.smirnova@hep.lu.s [Uppsala University, Department of Physics and Astronomy, Div. of Nuclear and Particle Physics, Box 535, SE-75121 Uppsala (Sweden)

    2010-04-01

    The Advanced Resource Connector (ARC) middleware introduced by NorduGrid is one of the basic Grid solutions used by scientists worldwide. While being well-proven in daily use by a wide variety of scientific applications at large-scale infrastructures like the Nordic DataGrid Facility (NDGF) and smaller scale projects, production ARC of today is still largely based on conventional Grid technologies and custom interfaces introduced a decade ago. In order to guarantee sustainability, true cross-system portability and standards-compliance based interoperability, the ARC community undertakes a massive effort of implementing modular Web Service (WS) approach into the middleware. With support from the EU KnowARC project, new components were introduced and the existing key ARC services got extended with WS technology based standard-compliant interfaces following a service-oriented architecture. Such components include the hosting environment framework, the resource-coupled execution service, the re-engineered client library, the self-healing storage solution and the peer-to-peer information system, to name a few. Gradual introduction of these new services and client tools into the production middleware releases is carried out together with NDGF and thus ensures a smooth transition to the next generation Grid middleware. Standard interfaces and modularity of the new component design are essential for ARC contributions to the planned Universal Middleware Distribution of the European Grid Initiative.

  3. Interaction of a vacuum arc plasma beam with an obstacle positioned normal to the plasma flow

    International Nuclear Information System (INIS)

    Zarchin, O; Zhitomirsky, V N; Goldsmith, S; Boxman, R L

    2003-01-01

    The effect of an obstacle positioned normal to a plasma jet produced by a vacuum arc plasma source on the radial distribution of ion flux in the vicinity of the obstacle was studied. This study was motivated by interest in the mutual influence of tightly packed substrates on coatings in industrial vacuum arc deposition systems. The experimental system consisted of a vacuum arc plasma source, a straight plasma duct, and a multi-probe consisting of a removable disc obstacle and a set of ring probes for measuring the radial ion flux. A dc arc discharge was ignited in vacuum between a truncated cone-shaped Cu cathode and an annular anode. The plasma jet produced by cathode spots passed through the anode aperture into the straight plasma duct. An axial magnetic field guided the plasma jet in the duct. The multi-probe consisted of a removable disc obstacle and a set of five ring probes for measuring the radial plasma flux as a function of distance from the disc obstacle. The rings and the disc probes were coaxially arranged on the multi-probe assembly and positioned so that plasma from the source passed through the ring probes and then encountered the disc. The influence of the obstacle was determined by measuring the ring ion currents, both in the presence of the obstacle, and when the disc obstacle was removed. The difference between the measured ion currents with and without the obstacle was interpreted to be the contribution of reflected or sputtered particles from the obstacle to the radial ion flux. The ring probes were biased by -60 V with respect to the grounded anode, to collect the saturated ion current. The multi-probe was connected to a movable stem, and positioned at different distances from the plasma source. A plasma density of ∼6 x 10 17 m -3 was estimated in this study based on the ion current to the obstacle. The radial ion flux collected by the ring probes increased by 20-25% due to the presence of the obstacle. As the calculated mean free path for

  4. Simultaneous synthesis of single-walled carbon nanotubes and graphene in a magnetically-enhanced arc plasma.

    Science.gov (United States)

    Li, Jian; Shashurin, Alexey; Kundrapu, Madhusudhan; Keidar, Michael

    2012-02-02

    Carbon nanostructures such as single-walled carbon nanotubes (SWCNT) and graphene attract a deluge of interest of scholars nowadays due to their very promising application for molecular sensors, field effect transistor and super thin and flexible electronic devices(1-4). Anodic arc discharge supported by the erosion of the anode material is one of the most practical and efficient methods, which can provide specific non-equilibrium processes and a high influx of carbon material to the developing structures at relatively higher temperature, and consequently the as-synthesized products have few structural defects and better crystallinity. To further improve the controllability and flexibility of the synthesis of carbon nanostructures in arc discharge, magnetic fields can be applied during the synthesis process according to the strong magnetic responses of arc plasmas. It was demonstrated that the magnetically-enhanced arc discharge can increase the average length of SWCNT (5), narrow the diameter distribution of metallic catalyst particles and carbon nanotubes (6), and change the ratio of metallic and semiconducting carbon nanotubes (7), as well as lead to graphene synthesis (8). Furthermore, it is worthwhile to remark that when we introduce a non-uniform magnetic field with the component normal to the current in arc, the Lorentz force along the J×B direction can generate the plasmas jet and make effective delivery of carbon ion particles and heat flux to samples. As a result, large-scale graphene flakes and high-purity single-walled carbon nanotubes were simultaneously generated by such new magnetically-enhanced anodic arc method. Arc imaging, scanning electron microscope (SEM), transmission electron microscope (TEM) and Raman spectroscopy were employed to analyze the characterization of carbon nanostructures. These findings indicate a wide spectrum of opportunities to manipulate with the properties of nanostructures produced in plasmas by means of controlling the

  5. Crustal growth of the Izu-Ogasawara arc estimated from structural characteristics of Oligocene arc

    Science.gov (United States)

    Takahashi, N.; Yamashita, M.; Kodaira, S.; Miura, S.; Sato, T.; No, T.; Tatsumi, Y.

    2011-12-01

    Japan Agency for Marine-Earth Science and Technology (JAMSTEC) carried out seismic surveys using a multichannel reflection system and ocean bottom seismographs, and we have clarified crustal structures of whole Izu-Ogasawara (Bonin)-Marina (IBM) arc since 2002. These refection images and velocity structures suggest that the crustal evolution in the intra-oceanic island arc accompanies with much interaction of materials between crust and mantle. Slow mantle velocity identified beneath the thick arc crusts suggests that dense crustal materials transformed into the mantle. On the other hand, high velocity lower crust can be seen around the bottom of the crust beneath the rifted region, and it suggests that underplating of mafic materials occurs there. Average crustal production rate of the entire arc is larger than expected one and approximately 200 km3/km/Ma. The production rate of basaltic magmas corresponds to that of oceanic ridge. Repeated crustal differentiation is indispensable to produce much light materials like continental materials, however, the real process cannot still be resolved yet. We, therefore, submitted drilling proposals to obtain in-situ middle crust with P-wave velocity of 6 km/s. In the growth history of the IBM arc, it is known by many papers that boninitic volcanisms preceded current bimodal volcanisms based on basaltic magmas. The current volcanisms accompanied with basaltic magmas have been occurred since Oligocene age, however, the tectonic differences to develop crustal architecture between Oligocene and present are not understood yet. We obtained new refraction/reflection data along an arc strike of N-S in fore-arc region. Then, we estimate crustal structure with severe change of the crustal thickness from refraction data, which are similar to that along the volcanic front. Interval for location of the thick arc crust along N-S is very similar to that along the volcanic front. The refection image indicates that the basement of the fore-arc

  6. THE REDSHIFT DISTRIBUTION OF GIANT ARCS IN THE SLOAN GIANT ARCS SURVEY

    International Nuclear Information System (INIS)

    Bayliss, Matthew B.; Gladders, Michael D.; Koester, Benjamin P.; Oguri, Masamune; Hennawi, Joseph F.; Sharon, Keren; Dahle, Haakon

    2011-01-01

    We measure the redshift distribution of a sample of 28 giant arcs discovered as a part of the Sloan Giant Arcs Survey. Gemini/GMOS-North spectroscopy provides precise redshifts for 24 arcs, and 'redshift desert' constrains for the remaining 4 arcs. This is a direct measurement of the redshift distribution of a uniformly selected sample of bright giant arcs, which is an observable that can be used to inform efforts to predict giant arc statistics. Our primary giant arc sample has a median redshift z = 1.821 and nearly two-thirds of the arcs, 64%, are sources at z ∼> 1.4, indicating that the population of background sources that are strongly lensed into bright giant arcs resides primarily at high redshift. We also analyze the distribution of redshifts for 19 secondary strongly lensed background sources that are not visually apparent in Sloan Digital Sky Survey imaging, but were identified in deeper follow-up imaging of the lensing cluster fields. Our redshift sample for the secondary sources is not spectroscopically complete, but combining it with our primary giant arc sample suggests that a large fraction of all background galaxies that are strongly lensed by foreground clusters reside at z ∼> 1.4. Kolmogorov-Smirnov tests indicate that our well-selected, spectroscopically complete primary giant arc redshift sample can be reproduced with a model distribution that is constructed from a combination of results from studies of strong-lensing clusters in numerical simulations and observational constraints on the galaxy luminosity function.

  7. Sonar gas flux estimation by bubble insonification: application to methane bubble flux from seep areas in the outer Laptev Sea

    Science.gov (United States)

    Leifer, Ira; Chernykh, Denis; Shakhova, Natalia; Semiletov, Igor

    2017-06-01

    Sonar surveys provide an effective mechanism for mapping seabed methane flux emissions, with Arctic submerged permafrost seepage having great potential to significantly affect climate. We created in situ engineered bubble plumes from 40 m depth with fluxes spanning 0.019 to 1.1 L s-1 to derive the in situ calibration curve (Q(σ)). These nonlinear curves related flux (Q) to sonar return (σ) for a multibeam echosounder (MBES) and a single-beam echosounder (SBES) for a range of depths. The analysis demonstrated significant multiple bubble acoustic scattering - precluding the use of a theoretical approach to derive Q(σ) from the product of the bubble σ(r) and the bubble size distribution where r is bubble radius. The bubble plume σ occurrence probability distribution function (Ψ(σ)) with respect to Q found Ψ(σ) for weak σ well described by a power law that likely correlated with small-bubble dispersion and was strongly depth dependent. Ψ(σ) for strong σ was largely depth independent, consistent with bubble plume behavior where large bubbles in a plume remain in a focused core. Ψ(σ) was bimodal for all but the weakest plumes. Q(σ) was applied to sonar observations of natural arctic Laptev Sea seepage after accounting for volumetric change with numerical bubble plume simulations. Simulations addressed different depths and gases between calibration and seep plumes. Total mass fluxes (Qm) were 5.56, 42.73, and 4.88 mmol s-1 for MBES data with good to reasonable agreement (4-37 %) between the SBES and MBES systems. The seepage flux occurrence probability distribution function (Ψ(Q)) was bimodal, with weak Ψ(Q) in each seep area well described by a power law, suggesting primarily minor bubble plumes. The seepage-mapped spatial patterns suggested subsurface geologic control attributing methane fluxes to the current state of subsea permafrost.

  8. Identification of the submergence tolerance QTL Come Quick Drowning1 (CGD1) in Arabidopsis thaliana

    NARCIS (Netherlands)

    Akman, Melis; Kleine, Rogier; Tienderen, van Peter H.; Schranz, Eric M.

    2017-01-01

    Global climate change is predicted to increase water precipitation fluctuations and lead to localized prolonged floods in agricultural fields and natural plant communities. Thus, understanding the genetic basis of submergence tolerance is crucial in order to improve plant survival under these

  9. Conidiation of Neurospora crassa induced by treatment with natrium fluoride in submerged culture

    Energy Technology Data Exchange (ETDEWEB)

    Timberlake, W E; Turian, G

    1975-01-01

    A transient treatment of pregerminated conidia of Neurospora crassa with NaF induced young, submerged cultures to prematurely differentiate conidia. The inductive treatment decreased the rate of respiration (with lower RQ), reduced the relative concentration of nucleoside triphosphates, and inhibited leucine incorporation into protein and adenosine incorporation into RNA.

  10. Acclimation of a terrestrial plant to submergence facilitates gas exchange under water

    NARCIS (Netherlands)

    Mommer, L.; Pedersen, O.; Visser, E.J.W.

    2004-01-01

    Flooding imposes stress upon terrestrial plants since it severely hampers gas exchange rates between the shoot and the environment. The resulting oxygen deficiency is considered to be the major problem for submerged plants. Oxygen microelectrode studies have, however, shown that aquatic plants

  11. Photosynthetic consequences of phenotypic plasticity in response to submergence: Rumex palustris as a case study

    NARCIS (Netherlands)

    Mommer, L.; Pons, T.L.; Visser, E.J.W.

    2006-01-01

    Survival and growth of terrestrial plants is negatively affected by complete submergence. This is mainly the result of hampered gas exchange between plants and their environment, since gas diffusion is severely reduced in water compared with air, resulting in O2 deficits which limit aerobic

  12. The structuring role of submerged macrophytes in a large subtropical shallow lake

    NARCIS (Netherlands)

    Finkler Ferreira, Tiago; Crossetti, Luciane O.; Motta Marques, David M.L.; Cardoso, Luciana; Fragoso, Carlos Ruberto; Nes, van Egbert H.

    2018-01-01

    It is well known that submerged macrophytes exert positive feedback effects that enhance the water transparency, stabilizing the clear-water state in shallow temperate lakes. However, the structuring effect of macrophytes on the food web of subtropical and tropical ecosystems is still poorly

  13. Modeling growth, lipid accumulation and lipid turnover in submerged batch cultures of Umbelopsis isabellina

    NARCIS (Netherlands)

    Meeuwse, P.; Akbari, P.; Tramper, J.; Rinzema, A.

    2012-01-01

    The production of lipids by oleaginous yeast and fungi becomes more important because these lipids can be used for biodiesel production. To understand the process of lipid production better, we developed a model for growth, lipid production and lipid turnover in submerged batch fermentation. This

  14. Diminishing peat oxidation of agricultural peat soils by infiltration via submerged drains

    NARCIS (Netherlands)

    Akker, van den J.J.H.; Hendriks, R.F.A.

    2017-01-01

    Oxidation of peat soils used in dairy farming in the western peat area of The Netherlands causes subsidence rates up to 13 mm.y and emissions of CO2 to about 27 t.ha.y. In 2003 experiments started with subsurface irrigation by submerged drains to raise groundwater levels to reduce oxidation and so

  15. Factors affecting palatability of four submerged macrophytes for grass carp Ctenopharyngodon idella.

    Science.gov (United States)

    Sun, Jian; Wang, Long; Ma, Lin; Min, Fenli; Huang, Tao; Zhang, Yi; Wu, Zhenbin; He, Feng

    2017-12-01

    Grass carp can weaken the growth and reproductive capacity of submerged macrophytes by consuming valuable tissues, but factors affecting palatability of submerged macrophytes for grass carp rarely are considered. In this study, relative consumption rate of grass carp with regard to submerged macrophytes was in the following order: Hydrilla verticillata > Vallisneria natans > Ceratophyllum demersum > Myriophyllum spicatum. Firmness of macrophytes was in the following order: M. spicatum > C. demersum > H. verticillata = V. natans, whereas shear force was M. spicatum > C. demersum > H. verticillata > V. natans. After crude extracts of M. spicatum were combined with H. verticillata, grass carp fed on fewer macrophyte pellets that contained more plant secondary metabolites (PSMs). This indicated that structure and PSMs affected palatability of macrophytes.PSMs do not contribute to reduction in palatability through inhibition of intestinal proteinases activity, but they can cause a decrease in the abundance of Exiguobacterium, Acinetobacter-yielding proteases, lipases, and cellulose activity, which in turn can weaken the metabolic capacity of grass carp and adversely affect their growth. Thus, the disadvantages to the growth and development of grass carp caused by PSMs may drive grass carp to feed on palatable submerged macrophytes with lower PSMs.

  16. Heavy metals in water, sediments and submerged macrophytes in ponds around the Dianchi Lake, China.

    Science.gov (United States)

    Wang, Zhixiu; Yao, Lu; Liu, Guihua; Liu, Wenzhi

    2014-09-01

    Through retaining runoff and pollutants such as heavy metals from surrounding landscapes, ponds around a lake play an important role in mitigating the impacts of human activities on lake ecosystems. In order to determine the potential for heavy metal accumulation of submerged macrophytes, we investigated the concentrations of 10 heavy metals (i.e., As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in water, sediments, and submerged macrophytes collected from 37 ponds around the Dianchi Lake in China. Our results showed that both water and sediments of these ponds were polluted by Pb. Water and sediments heavy metal concentrations in ponds received urban and agricultural runoff were not significantly higher than those in ponds received forest runoff. This result indicates that a large portion of heavy metals in these ponds may originate from atmospheric deposition and weathering of background soils. Positive relationships were found among heavy metal concentrations in submerged macrophytes, probably due to the coaccumulation of heavy metals. For most heavy metals, no significant relationships were found between submerged macrophytes and their water and sediment environments. The maximum concentrations of Cr, Fe and Ni in Ceratophyllum demersum were 4242, 16,429 and 2662mgkg(-1), respectively. The result suggests that C. demersum is a good candidate species for removing heavy metals from polluted aquatic environments. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Continental shelf drowned landscapes: Submerged geomorphological and sedimentary record of the youngest cycles

    NARCIS (Netherlands)

    Cohen, K.M.; Lobo, F.J.

    2013-01-01

    Continental shelves today find themselves largely submerged as a consequence of the sea-level rise in the last 20,000 years, the time since the Last Glacial Maximum (LGM), the period of maximum ice mass and minimum ocean volume within the Last Glacial Cycle. Their geomorphology, however, is far from

  18. Aerobic and anaerobic ethanol production by Mucor circinelloides during submerged growth

    DEFF Research Database (Denmark)

    Lübbehüsen, Tina Louise; Nielsen, Jens; Mcintyre, Mhairi

    2004-01-01

    The dimorphic organism Mucor circinelloides is currently being investigated as a potential host for heterologous protein production. The production of ethanol on pentose and hexose sugars was studied in submerged batch cultivations to further the general knowledge of Mucor physiology, with a view...

  19. Deep water marine algal flora of the submerged banks off west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Ambiye, V.; Untawale, A.G.

    A survey of submerged banks off India viz Cora Divh, Sessostris and Bassas de-Pedro resulted in obtaining information on the rich and diverse marine algal flora from various depths ranging from 18-70 m. A programme of onboard dredging was undertaken...

  20. Corrosion monitoring for underground and submerged concrete structures - examples and interpretation issues

    NARCIS (Netherlands)

    Polder, R.B.; Peelen, W.H.A.; Leegwater, G.

    2008-01-01

    Since about 1980 Corrosion Monitoring Systems have been used in many concrete structures in aggressive environmentworldwide. While these systemswork properly in aboveground environment, some questions have arisen for submerged conditions, e.g. the outer sides of tunnels, piers in seawater or