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1

Optimal mixing in recirculation zones  

Microsoft Academic Search

Coarse-scale mixing in a recirculation zone is described with a simple vortex model. Time-dependent forcing is employed to change the vortex motion and mixing properties. An optimal mixing problem is defined in which the flux across the recirculation region shall be maximized under the side-constraints of bounded vortex motion and bounded actuation. Concepts of control theory and chaotic advection are

Bernd R. Noack; Igor Mezic; Gilead Tadmor; Andrzej Banaszuk

2004-01-01

2

Fluid residence times within a recirculation zone created by an extraction–injection well pair  

Microsoft Academic Search

We present several analytical and semi-analytical solutions to evaluate the fluid residence times within the recirculation zone created by an extraction–injection well pair for several types of flow fields. The flow fields include: a well doublet in the absence of regional flow; an ‘encaged recirculation cell’ where a well doublet is located within and parallel to a uniform regional flow;

Jian Luo; Peter K. Kitanidis

2004-01-01

3

Laser scanning of a recirculation zone on the Bolund escarpment  

NASA Astrophysics Data System (ADS)

Rapid variations in the height of the recirculation zone are measured with a scanning wind lidar over a small escarpment on the Bolund Peninsula. The lidar is essentially a continuous-wave laser Doppler anemometer with the capability of rapidly changing the focus distance and the beam direction. The instrument measures the line-of-sight velocity 390 times per second and scans ten wind profiles from the ground up to seven meters per second. We observe a sharp interface between slow and fast moving fluid after the escarpment, and the interface is moving rapidly up and down. This implies that the position of the maximum velocity standard deviation is elevated a few meters above the surface. Close to the ground the mean wind is reversed relative to the general flow. The results are used to test computational fluid dynamics models for flow over terrain, and has relevance for wind energy. The preliminary comparison shows that the models are incapable of reproducing the reversed flow close to the surface, but more works needs to be done.

Mann, J.; Angelou, N.; Sjöholm, M.; Mikkelsen, T.; Hansen, K. H.; Cavar, D.; Berg, J.

2014-12-01

4

Recirculating and marginal zone B cell populations can be established and maintained independently of primary and secondary follicles  

Microsoft Academic Search

In normal spleen, most recirculating naïve IgM+IgDhi B cells are located within primary follicles and mantle zones of secondary follicles. By contrast, the marginal zone contains a heterogeneous population of IgMhiIgDlo\\/- B cells that are mostly non-recirculating. Although these are dynamic populations they are maintained at a constant size, the fundamental homeostatic mechanisms remain uncertain. One possibility is that the

Heinrich Körner; Thomas H Winkler; Jonathon D Sedgwick; Martin Röllinghoff; Antony Basten; Matthew C Cook

2001-01-01

5

Dynamic simulation of large boilers with natural recirculation  

Microsoft Academic Search

This paper presents a dynamic simulator of water-in-tube boilers with natural recirculation, the kind of equipment widely used in industries for steam generation either as a source of power or for providing heating capabilities in process plants. The development is based on a combination of two non-linear models, one for the evaporation in the vertical tubes and the other for

E. J. Adam; J. L. Marchetti

1999-01-01

6

Exhaust gas recirculation control  

Microsoft Academic Search

A regulating unit senses the pressures in two zones of a recirculation passage to create a control pressure, and a transducer regulates an operating pressure which positions a control valve to provide exhaust gas recirculation at rates which establish the pressures in the zones necessary to maintain the control pressure equal to a reference pressure. Exhaust gas recirculation thus varies

Stoltman

1980-01-01

7

The STREON Recirculation Chamber: An Advanced Tool to Quantify Stream Ecosystem Metabolism in the Benthic Zone  

NASA Astrophysics Data System (ADS)

The STReam Experimental Observatory Network is a large-scale experimental effort that will investigate the effects of eutrophication and loss of large consumers in stream ecosystems. STREON represents the first experimental effort undertaken and supported by the National Ecological Observatory Network (NEON).Two treatments will be applied at 10 NEON sites and maintained for 10 years in the STREON program: the addition of nitrate and phosphate to enrich concentrations by five times ambient levels and electrical fields that exclude top consumers (i.e., fish or invertebrates) of the food web from the surface of buried sediment baskets. Following a 3-5 week period, the sediment baskets will be extracted and incubated in closed, recirculating metabolic chambers to measure rates of respiration, photosynthesis, and nutrient uptake. All STREON-generated data will be open access and available on the NEON web portal. The recirculation chamber represents a critical infrastructural component of STREON. Although researchers have applied such chambers for metabolic and nutrient uptake measurements in the past, the scope of STREON demands a novel design that addresses multiple processes often neglected by earlier models. The STREON recirculation chamber must be capable of: 1) incorporating hyporheic exchange into the flow field to ensure measurements of respiration include the activity of subsurface biota, 2) operating consistently with heterogeneous sediments from sand to cobble, 3) minimizing heat exchange from the motor and external environment, 4) delivering a reproducible uniform flow field over the surface of the sediment basket, and 5) efficient assembly/disassembly with minimal use of tools. The chamber also required a means of accommodating an optical dissolved oxygen probe and a means to inject/extract water. A prototype STREON chamber has been designed and thoroughly tested. The flow field within the chamber has been mapped using particle imaging velocimetry (PIV) under various velocity settings. The extent of exchange with the sediment was assessed by means of a saline tracer injection and adjustment using flow-regulating components was explored. Performance under a broad range of temperatures (1 to 30 °C) was assessed. Finally, a novel heat-exchange mechanism meant to minimize warming during operations was evaluated. All prototype assessments demonstrate the applicability of the STREON chamber under a broad range of conditions. Though the STREON recirculation chamber has been designed to satisfy the specific needs of the STREON program, the open-access nature of the NEON network should facilitate scope expansion in the coming decades. The STREON recirculation chamber design and all prototype testing data will be accessible to facilitate chamber use elsewhere. The large number of chamber assemblies required for STREON operations should facilitate the acquisition of units by researchers working outside of the NEON network. Furthermore, the current scope of STREON includes the use of the chambers only once annually, thus a valuable tool for stream ecosystem measurements will be readily available at STREON sites for potential use by researchers interested in such measurements.

Brock, J. T.; Utz, R.; McLaughlin, B.

2013-12-01

8

Exhaust gas recirculation control  

Microsoft Academic Search

In an internal combustion engine, recirculation of exhaust gases is controlled to maintain the control pressure in a zone of the recirculation passage proportional to a reference pressure and thus to provide exhaust gas recirculation as a proportion of induction air flow. A duty cycle modulated valve controls an exhaust backpressure port and an atmospheric pressure port to create the

Stoltman

1983-01-01

9

Central recirculation zone analysis in an unconfined tangential swirl burner with varying degrees of premixing  

NASA Astrophysics Data System (ADS)

Swirl-stabilised combustion is one of the most widely used techniques for flame stabilisation, uses ranging from gas turbine combustors to pulverised coal-fired power stations. In gas turbines, lean premixed systems are of especial importance, giving the ability to produce low NOx systems coupled with wide stability limits. The common element is the swirl burner, which depends on the generation of an aerodynamically formed central recirculation zone (CRZ) and which serves to recycle heat and active chemical species to the root of the flame as well as providing low-velocity regions where the flame speed can match the local flow velocity. Enhanced mixing in and around the CRZ is another beneficial feature. The structure of the CRZ and hence that of the associated flames, stabilisation and mixing processes have shown to be extremely complex, three-dimensional and time dependent. The characteristics of the CRZ depend very strongly on the level of swirl (swirl number), burner configuration, type of flow expansion, Reynolds number (i.e. flowrate) and equivalence ratio. Although numerical methods have had some success when compared to experimental results, the models still have difficulties at medium to high swirl levels, with complex geometries and varied equivalence ratios. This study thus focuses on experimental results obtained to characterise the CRZ formed under varied combustion conditions with different geometries and some variation of swirl number in a generic swirl burner. CRZ behaviour has similarities to the equivalent isothermal state, but is strongly dependent on equivalence ratio, with interesting effects occurring with a high-velocity fuel injector. Partial premixing and combustion cause more substantive changes to the CRZ than pure diffusive combustion.

Valera-Medina, A.; Syred, N.; Kay, P.; Griffiths, A.

2011-06-01

10

Exhaust gas recirculation control  

SciTech Connect

In an internal combustion engine, recirculation of exhaust gases is controlled to maintain the control pressure in a zone of the recirculation passage proportional to a reference pressure and thus to provide exhaust gas recirculation as a proportion of induction air flow. A duty cycle modulated valve controls an exhaust backpressure port and an atmospheric pressure port to create the reference pressure, whereby the proportion of exhaust gases recirculated is established by the duty cycle and is independent of the induction air flow.

Stoltman, D.D.

1983-08-23

11

Exhaust gas recirculation control  

SciTech Connect

A regulating unit senses the pressures in two zones of a recirculation passage to create a control pressure, and a transducer regulates an operating pressure which positions a control valve to provide exhaust gas recirculation at rates which establish the pressures in the zones necessary to maintain the control pressure equal to a reference pressure. Exhaust gas recirculation thus varies with engine exhaust backpressure and accordingly is a proportion of induction air flow with the proportion being ruled by the regulating unit.

Stoltman, D.D.

1980-04-08

12

Exhaust gas recirculation control  

Microsoft Academic Search

A switching member simultaneously establishes a reference pressure and selects the pressure in one of two zones of a recirculation passage to create a control pressure, and a transducer regulates an operating pressure which positions a control valve to provide exhaust gas recirculation at rates which establish the pressures in the zones necessary to maintain the control pressure equal to

R. J. Haka; D. D. Stoltman

1980-01-01

13

Exhaust gas recirculation control  

SciTech Connect

A switching member simultaneously establishes a reference pressure and selects the pressure in one of two zones of a recirculation passage to create a control pressure, and a transducer regulates an operating pressure which positions a control valve to provide exhaust gas recirculation at rates which establish the pressures in the zones necessary to maintain the control pressure equal to the reference pressure. Exhaust gas recirculation thus varies with engine exhaust backpressure and accordingly is a proportion of induction air flow with the proportion being ruled by the switching member.

Haka, R. J.; Stoltman, D. D.

1980-02-05

14

Combustion oscillation: Chemical control showing mechanistic link to recirculation zone purge time  

Microsoft Academic Search

Active control mechanisms are being examined for lean premix combustion applications, such as gas turbine generators. Lean premix combustors are susceptible to large combustion oscillations, particularly when driven very lean to achieve low NOx. While past design work has been focussed on understanding the source of the oscillation and modifying the combustor to avoid such oscillations, commercial combustion designers have

R. S. Gemmen; G. A. Richards; M. J. Yip; T. S. Norton

1995-01-01

15

Recirculating rotary gas compressor  

DOEpatents

A positive displacement, recirculating Roots-type rotary gas compressor which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits (24 and 26) which return compressed discharge gas to the compressor housing (14), where it is mixed with low pressure inlet gas, thereby minimizing adiabatic heating of the gas. The compressor includes a pair of involutely lobed impellers (10 and 12) and an associated port configuration which together result in uninterrupted flow of recirculation gas. The large diameter recirculation conduits equalize gas flow velocities within the compressor and minimize gas flow losses. The compressor is particularly suited to applications requiring sustained operation at higher gas compression ratios than have previously been feasible with rotary pumps, and is particularly applicable to refrigeration or other applications requiring condensation of a vapor.

Weinbrecht, John F. (601 Oakwood Loop, NE., Albuquerque, NM 87123)

1992-01-01

16

Rupture Zones of Large South American Earthquakes and Some Predictions  

Microsoft Academic Search

This study attempts to forecast likely locations for large shallow South American earthquakes in the near future by examining the past space-time pattern of occurrence of large (M _ 7.7) earthquakes, the lateral extent of their rupture zones, and, where possible, the direction of rupture propagation. Rupture zones of large shallow earthquakes generally abut and do not overlap. Patterns of

John A. Kelleher

1972-01-01

17

Exhaust gas recirculation control  

Microsoft Academic Search

A transducer regulates an operating pressure which positions an exhaust gas recirculation control valve pintle to provide exhaust gas recirculation at rates which maintain the pressure in the recirculation passage upstream of the valve pintle equal to a reference pressure; exhaust gas recirculation thus varies with engine exhaust backpressure and accordingly is substantially proportional to induction air flow. The transducer

Haka

1979-01-01

18

Large-Area Zone Plate Fabrication with Optical Lithography  

SciTech Connect

Zone plates as condenser optics for x-ray microscopes offer simple optical designs for both illumination and spectral resolution when used as a linear monochromator. However, due to the long write times for electron beam lithography, both the availability and the size of zone plates for condensers have been limited. Since the resolution provided by the linear monochromator scales almost linearly with the diameter of the zone plate, the full potential for zone plate monochromators as illumination systems for x-ray microscopes has not been achieved. For example, the 10-mm-diameter zone plate has demonstrated a spectral resolution of E/{Delta}E = 700[1], but with a 26-mm-diameter zone plate, the calculated spectral resolution is higher than E/{Delta}E = 3000. These large-area zone plates are possible to fabricate with the leading edge semiconductor lithography tools such as those available at the College of Nanoscale Science and Engineering at the University at Albany. One of the lithography tools available is the ASML TWINSCAN XT: 1950i with 37-nm resolution [2]. A single 300-mm wafer can contain more than 60 fields, each with a large area condenser, and the throughput of the tool can be more than one wafer every minute.

Denbeaux, G. [College of Nanoscale Science and Engineering, University at Albany, 255 Fuller Road, Albany, NY 12203 (United States)

2011-09-09

19

Hydro-mechanical behavior of Municipal Solid Waste subject to leachate recirculation in a large-scale compression reactor cell  

SciTech Connect

The paper presents the results of a laboratory experiment on Municipal Solid Waste (MSW) subjected to one-dimensional compression in a 1 m{sup 3} instrumented cell. The focus was on the hydro-mechanical behavior of the material under conditions of confinement and leachate percolation that replicate those found in real-scale landfills. The operation of the apparatus is detailed together with the testing methodology and the monitoring program. Two samples of waste were tested: the first extended over a period of 10 months ('Control Test') and the second for 22 months ('Enhanced Test' with leachate recirculation). Consolidation data is reported with regard to both short-term (stress-dependent) and long-term (time-dependent) settlements. A discussion follows based on the derived values of primary and secondary compression ratios. Correlations between compression parameters and the biodegradation process are presented. In particular, results clearly highlight the effect of leachate recirculation on waste settlement: 24% secondary deformation reached after slightly less than 2 years (equivalent to a 5-fold increase in compressibility) and 17.9% loss of dry matter. Comparisons are proposed considering the results derived from the few monitoring programs conducted on experimental bioreactors worldwide. Finally, the hydraulic characterization of waste is discussed with regard to the evaluation of effective porosity and permeability.

Olivier, Franck [Environment, Energy and Waste Research Center (CREED), 291, avenue Dreyfous Ducas, 78520 Limay (France) and Laboratoire LIRIGM - Maison des Geosciences, 1381, rue de la piscine 38400 Saint-Martin d'Heres (France)]. E-mail: franck.olivier@ujf-grenoble.fr; Gourc, Jean-Pierre [Laboratoire LIRIGM - Maison des Geosciences, 1381, rue de la piscine 38400 Saint-Martin d'Heres (France)]. E-mail: gourc@ujf-grenoble.fr

2007-07-01

20

Exhaust gas recirculation control  

Microsoft Academic Search

A transducer creates an operating pressure that positions a control valve to provide exhaust gas recirculation at rates which maintain the control pressure in the recirculation passage between the valve and an orifice equal to a reference pressure; exhaust gas recirculation thus varies with engine exhaust backpressure and accordingly is substantially proportional to induction air flow. The transducer also varies

Vogelsberg

1979-01-01

21

A satellite magnetic perspective of subduction zones, large igneous provinces, rifts, and diffuse plate boundary zones  

NASA Astrophysics Data System (ADS)

Large and intermediate-scale tectonic features such as subduction zones, large igneous provinces, rifts, and diffuse plate boundary zones are often seen to have a magnetic signature visible from the perspective of near-Earth magnetic field satellites such as CHAMP and Orsted. Why do these tectonic features have a magnetic signature, while others do not? A new model of the lithospheric field (MF-6, Maus et al., 2008) extending to spherical harmonic degree 120 (333 km wavelength) has been used to evaluate the magnetic state of the lithosphere under the assumption that the magnetization is either induced (with a seismic starting model), or remanent (with a minimum norm approach). Some of the features identified from these images include the Tethyan and NE Siberian diffuse plate boundary zones, the Red Sea rift, and Cretaceous rift basins developed on the West African shield. Almost without exception, subduction zones exhibit a magnetic signature, as do many large igneous provinces. In this talk we discuss some of the new insights this magnetic perspective provides, and speculate on the controls which determine whether tectonic features will be expressed magnetically.

Purucker, M. E.; Whaler, K. A.

2008-12-01

22

Confined turbulent swirling recirculating flow predictions. Ph.D. Thesis. Final Report  

NASA Technical Reports Server (NTRS)

The capability and the accuracy of the STARPIC computer code in predicting confined turbulent swirling recirculating flows is presented. Inlet flow boundary conditions were demonstrated to be extremely important in simulating a flowfield via numerical calculations. The degree of swirl strength and expansion ratio have strong effects on the characteristics of swirling flow. In a nonswirling flow, a large corner recirculation zone exists in the flowfield with an expansion ratio greater than one. However, as the degree of inlet swirl increases, the size of this zone decreases and a central recirculation zone appears near the inlet. Generally, the size of the central zone increased with swirl strength and expansion ratio. Neither the standard k-epsilon turbulence mode nor its previous extensions show effective capability for predicting confined turbulent swirling recirculating flows. However, either reduced optimum values of three parameters in the mode or the empirical C sub mu formulation obtained via careful analysis of available turbulence measurements, can provide more acceptable accuracy in the prediction of these swirling flows.

Abujelala, M. T.; Lilley, D. G.

1985-01-01

23

Large earthquake processes in the northern Vanuatu subduction zone  

NASA Astrophysics Data System (ADS)

northern Vanuatu (formerly New Hebrides) subduction zone (11°S to 14°S) has experienced large shallow thrust earthquakes with Mw > 7 in 1966 (MS 7.9, 7.3), 1980 (Mw 7.5, 7.7), 1997 (Mw 7.7), 2009 (Mw 7.7, 7.8, 7.4), and 2013 (Mw 8.0). We analyze seismic data from the latter four earthquake sequences to quantify the rupture processes of these large earthquakes. The 7 October 2009 earthquakes occurred in close spatial proximity over about 1 h in the same region as the July 1980 doublet. Both sequences activated widespread seismicity along the northern Vanuatu subduction zone. The focal mechanisms indicate interplate thrusting, but there are differences in waveforms that establish that the events are not exact repeats. With an epicenter near the 1980 and 2009 events, the 1997 earthquake appears to have been a shallow intraslab rupture below the megathrust, with strong southward directivity favoring a steeply dipping plane. Some triggered interplate thrusting events occurred as part of this sequence. The 1966 doublet ruptured north of the 1980 and 2009 events and also produced widespread aftershock activity. The 2013 earthquake rupture propagated southward from the northern corner of the trench with shallow slip that generated a substantial tsunami. The repeated occurrence of large earthquake doublets along the northern Vanuatu subduction zone is remarkable considering the doublets likely involved overlapping, yet different combinations of asperities. The frequent occurrence of large doublet events and rapid aftershock expansion in this region indicate the presence of small, irregularly spaced asperities along the plate interface.

Cleveland, K. Michael; Ammon, Charles J.; Lay, Thorne

2014-12-01

24

Exhaust gas recirculation system  

Microsoft Academic Search

An engine exhaust gas recirculation (EGR) system is provided in which a sonic flow EGR valve is moved to open positions to establish a different constant rate of flow at each open position of the EGR valve in response to air pressure acting on a servo means secured to the valve, the air pressure force being controlled by changes in

Rachedi

1983-01-01

25

33 CFR 165.839 - Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to Mile Marker...  

...2014-07-01 false Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest...165.839 Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest...are established around all large cruise ships transiting between the Southwest Pass...

2014-07-01

26

33 CFR 165.839 - Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to Mile Marker...  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest...165.839 Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest...are established around all large cruise ships transiting between the Southwest Pass...

2013-07-01

27

33 CFR 165.1317 - Security and Safety Zone; Large Passenger Vessel Protection, Puget Sound and adjacent waters...  

Code of Federal Regulations, 2010 CFR

... 2010-07-01 false Security and Safety Zone; Large Passenger Vessel Protection...SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY REGULATED NAVIGATION AREAS AND LIMITED...District § 165.1317 Security and Safety Zone; Large Passenger Vessel...

2010-07-01

28

Large crowding zones in peripheral vision for briefly presented stimuli.  

PubMed

When a target is flanked by distractors, it becomes more difficult to identify. In the periphery, this crowding effect extends over a wide range of target-flanker separations, called the spatial extent of interaction (EoI). A recent study showed that the EoI dramatically increases in size for short presentation durations (Chung & Mansfield, 2009). Here we investigate this duration-EoI relation in greater detail and show that (a) it holds even when visibility of the unflanked target is equated for different durations, (b) the function saturates for durations shorter than 30 to 80 ms, and (c) the largest EoIs represent a critical spacing greater than 50% of eccentricity. We also investigated the effect of same or different polarity for targets and flankers across different presentation durations. We found that EoIs for target and flankers having opposite polarity (one white, the other black) show the same temporal pattern as for same polarity stimuli, but are smaller at all durations by 29% to 44%. The observed saturation of the EoI for short-duration stimuli suggests that crowding follows the locus of temporal integration. Overall, the results constrain theories that map crowding zones to fixed spatial extents or to lateral connections of fixed length in the cortex. PMID:25550071

Tripathy, Srimant Prasad; Cavanagh, Patrick; Bedell, Harold E

2014-01-01

29

Cooling Along Hyporheic Pathlines in a Large River Riparian Zone  

EPA Science Inventory

Floodplains can contribute to hyporheic cooling and moderation of temperature for rivers, but extent and magnitude are dependent on ground water hydrology. Here we illustrate the controls and dynamics of hyporheic cooling in the ground water of a large river floodplain with field...

30

High ratio recirculating gas compressor  

DOEpatents

A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor.

Weinbrecht, John F. (601 Oakwood Pl., NE., Albuquerque, NM 87123)

1989-01-01

31

High ratio recirculating gas compressor  

DOEpatents

A high ratio positive displacement recirculating rotary compressor is disclosed. The compressor includes an integral heat exchanger and recirculation conduits for returning cooled, high pressure discharge gas to the compressor housing to reducing heating of the compressor and enable higher pressure ratios to be sustained. The compressor features a recirculation system which results in continuous and uninterrupted flow of recirculation gas to the compressor with no direct leakage to either the discharge port or the intake port of the compressor, resulting in a capability of higher sustained pressure ratios without overheating of the compressor. 10 figs.

Weinbrecht, J.F.

1989-08-22

32

Exhaust gas recirculation system  

SciTech Connect

An engine exhaust gas recirculation (EGR) system is provided in which a sonic flow EGR valve is moved to open positions to establish a different constant rate of flow at each open position of the EGR valve in response to air pressure acting on a servo means secured to the valve, the air pressure force being controlled by changes in a control vacuum opposing the air pressure force and modified by an air bleed device as a function of changes in engine exhaust gas backpressure levels, to provide an EGR valve movement that varies essentially in proportion to changes in engine air flow.

Rachedi, S.H.

1983-08-30

33

A new approach to jet phenomena. Gas entrainment and recirculation in a bidimensional spouted fluidized bed  

SciTech Connect

Although literature studies report the fluctuating nature of jets escaping into a fluidized bed, up to now the models assumed steady and permanent jets. A new approach which accounts for the fluctuating nature of the jet is proposed. The experiments were carried out in a large 2-dimensional fluidized bed equipped with a ''V'' grid and a central jet. The gas jet velocity was kept around 100 m/s and the influence of the grid aeration on the gas mixing was investigated. A model was developed based on the concentration profiles of an inert tracer gas and the measurement with a light detector of the probability of jet presence. The model separates the bed in 2 zones: a zone in which the jet fluctuates (a point in this zone will alternately be in the jet and in the emulsion phase) and a zone in which the jet is never present. The model predicts the rate of gas entrainment into the jet and the rate of gas recirculation between the jet and the emulsion phase. When the grid aeration is close to the minimum fluidization velocity, the gas entrainment into the jet is limited by frictional resistance to the gas flow in the defluidized emulsion phase. For high gas aeration at the grid, the gas entrainment can reach 30% of the total gas introduced at the grid. The rate of gas recirculation between the jet and the emulsion phase is relatively low in all cases.

Freychet, N.; Briens, C.L.; Bergougnou, M.A.

1987-01-01

34

Quiet zone within a seismic gap near western Nicaragua: Possible location of a future large earthquake  

USGS Publications Warehouse

A 5700-square-kilometer quiet zone occurs in the midst of the locations of more than 4000 earthquakes off the Pacific coast of Nicaragua. The region is indicated by the seismic gap technique to be a likely location for an earthquake of magnitude larger than 7. The quiet zone has existed since at least 1950; the last large earthquake originating from this area occurred in 1898 and was of magnitude 7.5. A rough estimate indicates that the magnitude of an earthquake rupturing the entire quiet zone could be as large as that of the 1898 event. It is not yet possible to forecast a time frame for the occurrence of such an earthquake in the quiet zone. Copyright ?? 1981 AAAS.

Harlow, D.H.; White, R.A.; Cifuentes, I.L.; Aburto, Q.A.

1981-01-01

35

Combustion-gas recirculation system  

DOEpatents

A combustion-gas recirculation system has a mixing chamber with a mixing-chamber inlet and a mixing-chamber outlet. The combustion-gas recirculation system may further include a duct connected to the mixing-chamber inlet. Additionally, the combustion-gas recirculation system may include an open inlet channel with a solid outer wall. The open inlet channel may extend into the mixing chamber such that an end of the open inlet channel is disposed between the mixing-chamber inlet and the mixing-chamber outlet. Furthermore, air within the open inlet channel may be at a pressure near or below atmospheric pressure.

Baldwin, Darryl Dean (Lacon, IL)

2007-10-09

36

The Impact of Laptop-Free Zones on Student Performance and Attitudes in Large Lectures  

ERIC Educational Resources Information Center

The goal of this study was to determine if laptop use in lecture negatively impacts learning outcomes of surrounding students taking notes on paper. Two sections of a large introductory biology course (greater than 400 students/section) were zoned into a laptop-permitted and a laptop-free area. Two sections in which laptop users could sit anywhere…

Aguilar-Roca, Nancy M.; Williams, Adrienne E.; O'Dowd, Diane K.

2012-01-01

37

Marginal zone lymphoma of both spleen and kidney displaying transformation into large B-cell lymphoma  

Microsoft Academic Search

We report a case of simultaneous involvement of the spleen and the left kidney in a marginal zone lymphoma with a monotypic\\u000a lymphoplasmacytic cell component, which transformed into a diffuse large B-cell lymphoma of the immunoblastic type. PCR showed\\u000a that the small and large B-cell populations carried the same type of immunoglobulin heavy chain gene rearrangement. This type\\u000a of rearrangement

A. Canelhas; E. Compérat; A. Le Tourneau; T. Molina; M. Ramos; P. Ribeiro; A. Pimenta; J. Diebold; J. Audouin

2006-01-01

38

Present wind activity on Mars - Relation to large latitudinally zoned sediment deposits  

Microsoft Academic Search

The relation of present Martian winds to large latitudinally zoned sediment deposits has been investigated using global wind streak data and mapping of large sand and dust deposits. Dune sand deposits occur primarily in three latitude belts: north polar (74-85 degrees North), low latitude (5 degrees North-20 degrees South), and south polar (40-80 degrees South). Comparison with wind streak data

Peter Thomas

1982-01-01

39

Large-scale folding in the upper part of the Ivrea-Verbano zone, NW Italy  

NASA Astrophysics Data System (ADS)

New geological mapping has led to a new interpretation of the large-scale superimposed folding in the upper part of the Ivrea-Verbano zone, Italian Alps. The region is widely held to represent an upended section through lower continental crust of northern Italy. The dominant fold structure, extending some 40 km along strike, is the Massone tight to isoclinal antiform, with a hinge line strongly curved through 115°. This folds pre-existing large-scale folds that formed during regional migmatization, probably during the Hercynian orogeny, to form a type-2 interference geometry. The region then suffered post-orogenic mafic magmatic underplating and other magmatism, accompanied by crustal stretching, with contact metamorphism and migmatization causing the imposition of the final pattern of metamorphic isograds. The Ivrea-Verbano zone was brought into contact with the overlying metamorphic rocks of the Serie dei Laghi on a major shear zone. Sub-solidus stretching continued though displacements on low-angle, high-temperature shear zones. Most of the Ivrea-Verbano zone was finally tilted to the vertical and emplaced into its present position after the Mesozoic era and probably during Alpine orogenesis, forming the vertical limb of a crustal-scale double kink.

Rutter, Ernest; Brodie, Katharine; James, Tony; Burlini, Luigi

2007-01-01

40

The "dead zone" is a large area of decreased dissolved oxygen concentration in bottom waters that forms  

E-print Network

oxygen in the northern Gulf of Mexico Walter K Dodds The "dead zone", an area with reduced concentrations that forms each summer in the northern Gulf of Mexico. This hypoxic zone (HZ) is formally defined as an areaThe "dead zone" is a large area of decreased dissolved oxygen concentration in bottom waters

Kaufman, Glennis A.

41

Recirculation of municipal landfill leachate  

E-print Network

RECIRCULATION OF MUNICIPAL LANDFILL LEACHATE A Thesis by BRIAN JUDE PINKO4ISKI Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1987 Major Subject...: Civil Engineering RECIRCULATION OF MUNICIPAL LANDFILL LEACHATE A Thesis by BRIAN JUDE PINKOWSKI Approved as to style and content by: Charles P. Giammona (Chair of Committee) Roy . Harm, (Member) Kirk W. Brown (Member) Donald A. Maxwel...

Pinkowski, Brian Jude

2012-06-07

42

Megacities and large urban agglomerations in the coastal zone: interactions between atmosphere, land, and marine ecosystems.  

PubMed

Megacities are not only important drivers for socio-economic development but also sources of environmental challenges. Many megacities and large urban agglomerations are located in the coastal zone where land, atmosphere, and ocean meet, posing multiple environmental challenges which we consider here. The atmospheric flow around megacities is complicated by urban heat island effects and topographic flows and sea breezes and influences air pollution and human health. The outflow of polluted air over the ocean perturbs biogeochemical processes. Contaminant inputs can damage downstream coastal zone ecosystem function and resources including fisheries, induce harmful algal blooms and feedback to the atmosphere via marine emissions. The scale of influence of megacities in the coastal zone is hundreds to thousands of kilometers in the atmosphere and tens to hundreds of kilometers in the ocean. We list research needs to further our understanding of coastal megacities with the ultimate aim to improve their environmental management. PMID:23076973

von Glasow, Roland; Jickells, Tim D; Baklanov, Alexander; Carmichael, Gregory R; Church, Tom M; Gallardo, Laura; Hughes, Claire; Kanakidou, Maria; Liss, Peter S; Mee, Laurence; Raine, Robin; Ramachandran, Purvaja; Ramesh, R; Sundseth, Kyrre; Tsunogai, Urumu; Uematsu, Mitsuo; Zhu, Tong

2013-02-01

43

The permeability of large phyllosilicate-rich fault zones in the brittle crust  

NASA Astrophysics Data System (ADS)

Field mapping of a large strike-slip fault zone (the Carboneras fault; ˜40 km offset) in southeastern Spain has revealed that the internal structure is very different from other descriptions of strike-slip faults of a similar offset. This difference is attributed to the presence of a high proportion of phyllosilicates within the fault that is derived predominantly from a mica schist protolith. The fault zone is wide, up to 1 km, and contains multiple strands of phyllosilicate-rich fault gouge that entrain lenses of variably fractured protolith between them. This internal structure differs from other faults that run through predominantly quartzofeldspathic protoliths. These generally have a single zone of very high strain on the order of 50 cm wide, surrounded by a fracture damage zone up to 100 m wide. The structure of the fault zone has major implications for the hydrological, seismological and mechanical properties it possesses. This contribution concentrates on the hydrological properties of phyllosilicate-rich fault zones. This depends on the permeability of both the strands of phyllosilicate-rich fault gouge and lenses of variably damaged protolith. Fluid flow parallel to the fault zone is controlled by the lenses of damaged protolith, whereas flow perpendicular to the zone is mediated by the strands of phyllosilicate-rich gouge. Natural samples of phyllosilicate-rich gouge have been collected from the surface trace of the Carboneras fault and their permeability measured in the laboratory under varying conditions of pressure and temperature using both argon and water as the permeant. These laboratory studies have revealed that the permeability is characteristically low (<10-18 m^2) and dependent upon direction, pressure, temperature and pore fluid. The permeability is highly anisotropic, with 3 orders of magnitude higher permeability recorded parallel to the fault plane as opposed to perpendicular to it. The permeability depends heavily on effective pressure, with a poroelastic muliplier close to 1. Temperature up to 150^oC promotes recoverable compaction that correspondingly lowers permeability. Finally, using water as the pore fluid allows physicochemical interactions with the phyllosilicate phases present. This results in a lowering of the permeability by up to 1 order of magnitude (relative to argon). Furthermore, elevated temperatures reduce the effectiveness of this interaction, such that it may be viewed as low temperature phenomenon. All these data may be combined to produce a model for the permeability structure in a crustal scale strike-slip fault zone that contains a high proportion of phyllosilicate material.

Faulkner, D.

2003-04-01

44

Large-scale folding in the upper part of the Ivrea-Verbano zone, NW Italy  

Microsoft Academic Search

New geological mapping has led to a new interpretation of the large-scale superimposed folding in the upper part of the Ivrea-Verbano zone, Italian Alps. The region is widely held to represent an upended section through lower continental crust of northern Italy. The dominant fold structure, extending some 40km along strike, is the Massone tight to isoclinal antiform, with a hinge

Ernest Rutter; Katharine Brodie; Tony James; Luigi Burlini

2007-01-01

45

How Large Scale Flows in the Solar Convection Zone may Influence Solar Activity  

NASA Technical Reports Server (NTRS)

Large scale flows within the solar convection zone are the primary drivers of the Sun s magnetic activity cycle. Differential rotation can amplify the magnetic field and convert poloidal fields into toroidal fields. Poleward meridional flow near the surface can carry magnetic flux that reverses the magnetic poles and can convert toroidal fields into poloidal fields. The deeper, equatorward meridional flow can carry magnetic flux toward the equator where it can reconnect with oppositely directed fields in the other hemisphere. These axisymmetric flows are themselves driven by large scale convective motions. The effects of the Sun s rotation on convection produce velocity correlations that can maintain the differential rotation and meridional circulation. These convective motions can influence solar activity themselves by shaping the large-scale magnetic field pattern. While considerable theoretical advances have been made toward understanding these large scale flows, outstanding problems in matching theory to observations still remain.

Hathaway, D. H.

2004-01-01

46

Biological Treatment in Recirculating Aquaculture Systems1 William J. Golz  

E-print Network

Biological Treatment in Recirculating Aquaculture Systems1 William J. Golz Department of Civil. 1995. Biological Treatment in Recirculating Aquaculture Systems. In Recirculating aquaculture Treatment in Recirculating Aquaculture Systems 2 Heterotrophs grow very efficiently, doubling in population

47

Breaking size segregation waves and particle recirculation in granular avalanches  

Microsoft Academic Search

Particle-size segregation is a common feature of dense gravity-driven granular free-surface flows, where sliding and frictional grainlens'-like structure. A high-resolution shock-capturing numerical scheme is used to investigate the temporal evolution of a linearly decreasing shock towards a steady-state lens, as well as the interaction of two recirculation zones that travel at different speeds and eventually coalesce to form a single

A. R. Thornton; J. M. N. T. Gray

2008-01-01

48

Three-dimensional recirculation flow in a backward facing step  

SciTech Connect

The flow field behind a small aspect ratio (channel width/step height = 3) backward-facing step is examined using laser Doppler anemometer. All three velocity components inside the separation region are surveyed in detail. The velocity profile just upstream of the step is laminar and two-dimensional. The velocity field reveals that the reattachment and the flow in the recirculation zone are highly three-dimensional due to the small aspect ratio.

Shih, C. (Florida A M Univ., Tallahassee, FL (United States) Florida State Univ., Tallahassee, FL (United States)); Ho, C.M. (Univ. of California, Los Angeles, CA (United States). Mechanical, Aerospace and Nuclear Engineering Dept.)

1994-06-01

49

Multistage exhaust gas recirculation system  

Microsoft Academic Search

An automotive type exhaust gas recirculation (EGR) system has two modes of operation, a first one that regulates EGR flow at a constant percentage rate as a function of throttle valve position independently of exhaust gas backpressure changes, and a second one that provides a variable percentage rate of flow of EGR gases in response to changes in exhaust gas

D. C. Ahrns; S. H. Rachedi

1983-01-01

50

Do Large Earthquakes Penetrate below the Seismogenic Zone? Potential Clues from Microseismicity  

NASA Astrophysics Data System (ADS)

It is typically assumed that slip in large earthquakes is confined within the seismogenic zone - often defined by the extent of the background seismicity - with regions below creeping. In terms of rate-and-state friction properties, the locked seismogenic zone and the deeper creeping fault extensions are velocity-weakening (VW) and velocity-strengthening (VS), respectively. Recently, it has been hypothesized that earthquake rupture could penetrate into the deeper creeping regions (Shaw and Wesnousky, BSSA, 2008), and yet it is difficult to detect the deep slip due to limited resolution of source inversions with depth. We hypothesize that absence of concentrated microseismicity at the bottom of the seismogenic zone may point to the existence of deep-penetrating earthquake ruptures. The creeping-locked boundary creates strain and stress concentrations. If it is at the bottom of the VW region, which supports earthquake nucleation, microseismicity should persistently occur at the bottom of the seismogenic zone. Such behavior has been observed on the Parkfield segment of the San Andreas Fault (SAF) and the Calaveras fault. However, such microseismicity would be inhibited if dynamic earthquake rupture penetrates substantially below the VW/VS transition, which would drop stress in the ruptured VS areas, making them effectively locked. Hence the creeping-locked boundary, with its stress concentration, would be located within the VS area, where earthquake nucleation is inhibited. Indeed, microseismicity concentration at the bottom of the seismogenic zone is not observed for several faults that hosted major earthquakes, such as the Carizzo segment of the SAF (the site of 1857 Mw 7.9 Fort Tejon earthquake) and Palu-Lake-Hazar segment of the Eastern Anatolian Fault. We confirm this hypothesis by simulating earthquake sequences and aseismic slip in 3D fault models (Lapusta and Liu, 2009; Noda and Lapusta, 2010). The fault is governed by rate-and-state friction laws, with a VW region surrounded by VS areas. At the bottom of the VW region, patches of smaller nucleation sizes simulate fault heterogeneity that could lead to microseismicity. On part of the fault, thermally-induced pore fluid pressurization (TP) is effective, leading to enhanced coseismic weakening. The possibility of coseismic weakening of VS areas has been suggested in recent studies (e.g., Rice and Platt, AGU, 2011; Noda and Lapusta, AGU, 2011). In the case where efficient TP is restricted to the VW zone, model-spanning earthquakes arrest quickly in the VS areas, and the creeping-locked boundary reaches the bottom of the VW region early in the earthquake cycle, producing microseismicity. In contrast, if efficient TP extends deeper (5 km), ruptures activate coseismic weakening in the VS areas, penetrating much deeper. The creeping-locked boundary, while moving updip with time, is below the VW area throughout the interseismic period, producing no microseismicity. Hence, the absence of concentrated microseismicity at the bottom of the seismogenic zone may point to penetration of large earthquakes below seismogenic zones. The argument is strongest under the assumption of localized shear zones extending below the so-called brittle-ductile transition, which is supported by frictional postseismic slip and seismic tremor at the deeper fault extensions (e.g., Bruhat et al., JGR, 2011; Shelly, 2010)

Jiang, J.; Lapusta, N.

2012-12-01

51

The impact of building recirculation rates on secondary organic aerosols generated by indoor chemistry  

Microsoft Academic Search

Numerous investigators have documented increases in the concentrations of airborne particles as a consequence of ozone\\/terpene reactions in indoor environments. This study examines the effect of building recirculation rates on the concentrations of secondary organic aerosol (SOA) resulting from reactions between indoor limonene and ozone. The experiments were conducted in a large environmental chamber using four recirculation rates (11, 14,

M. S. Zuraimi; C. J. Weschler; K. W. Tham; M. O. Fadeyi

2007-01-01

52

Review article Disinfestation of recirculating nutrient solutions  

E-print Network

Review article Disinfestation of recirculating nutrient solutions in greenhouse horticulture David) Abstract ­ Recirculating nutrient systems offer a good method to control nutrient leaching from greenhouses of recirculating nutrient systems by the greenhouse industry. This review discusses and compares five broadly

Boyer, Edmond

53

In Situ Biotreatment of TBA with Recirculation/Oxygenation.  

PubMed

The potential for in situ biodegradation of tert-butyl alcohol (TBA) by creation of aerobic conditions in the subsurface with recirculating well pairs was investigated in two field studies conducted at Vandenberg Air Force Base (VAFB). In the first experiment, a single recirculating well pair with bromide tracer and oxygen amendment successfully delivered oxygen to the subsurface for 42 days. TBA concentrations were reduced from approximately 500 ?g/L to below the detection limit within the treatment zone and the treated water was detected in a monitoring transect several meters downgradient. In the second experiment, a site-calibrated model was used to design a double recirculating well pair with oxygen amendment, which successfully delivered oxygen to the subsurface for 291 days and also decreased TBA concentrations to below the detection limit. Methylibium petroleiphilum strain PM1, a known TBA-degrading bacterium, was detectable at the study site but addition of oxygen had little impact on the already low baseline population densities, suggesting that there was not enough carbon within the groundwater plume to support significant new growth in the PM1 population. Given favorable hydrogeologic and geochemical conditions, the use of recirculating well pairs to introduce dissolved oxygen into the subsurface is a viable method to stimulate in situ biodegradation of TBA or other aerobically-degradable aquifer contaminants. PMID:23358537

North, Katharine P; Mackay, Douglas M; Kayne, Julian S; Petersen, Daniel; Rasa, Ehsan; Rastegarzadeh, Laleh; Holland, Reef B; Scow, Kate M

2012-01-01

54

In Situ Biotreatment of TBA with Recirculation/Oxygenation  

PubMed Central

The potential for in situ biodegradation of tert-butyl alcohol (TBA) by creation of aerobic conditions in the subsurface with recirculating well pairs was investigated in two field studies conducted at Vandenberg Air Force Base (VAFB). In the first experiment, a single recirculating well pair with bromide tracer and oxygen amendment successfully delivered oxygen to the subsurface for 42 days. TBA concentrations were reduced from approximately 500 ?g/L to below the detection limit within the treatment zone and the treated water was detected in a monitoring transect several meters downgradient. In the second experiment, a site-calibrated model was used to design a double recirculating well pair with oxygen amendment, which successfully delivered oxygen to the subsurface for 291 days and also decreased TBA concentrations to below the detection limit. Methylibium petroleiphilum strain PM1, a known TBA-degrading bacterium, was detectable at the study site but addition of oxygen had little impact on the already low baseline population densities, suggesting that there was not enough carbon within the groundwater plume to support significant new growth in the PM1 population. Given favorable hydrogeologic and geochemical conditions, the use of recirculating well pairs to introduce dissolved oxygen into the subsurface is a viable method to stimulate in situ biodegradation of TBA or other aerobically-degradable aquifer contaminants. PMID:23358537

North, Katharine P.; Mackay, Douglas M.; Kayne, Julian S.; Petersen, Daniel; Rasa, Ehsan; Rastegarzadeh, Laleh; Holland, Reef B.; Scow, Kate M.

2012-01-01

55

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Captain of the Port...  

Code of Federal Regulations, 2013 CFR

...River Bar “C” buoy and extending eastward on the Columbia River to Kennewick, WA and upriver through Lewiston, ID on the Snake River. (d) Compliance. The large passenger vessel security and safety zone established by this section...

2013-07-01

56

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Captain of the Port...  

Code of Federal Regulations, 2012 CFR

...River Bar “C” buoy and extending eastward on the Columbia River to Kennewick, WA and upriver through Lewiston, ID on the Snake River. (d) Compliance. The large passenger vessel security and safety zone established by this section...

2012-07-01

57

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Captain of the Port...  

Code of Federal Regulations, 2011 CFR

...River Bar “C” buoy and extending eastward on the Columbia River to Kennewick, WA and upriver through Lewiston, ID on the Snake River. (d) Compliance. The large passenger vessel security and safety zone established by this section...

2011-07-01

58

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Portland, OR Captain of...  

Code of Federal Regulations, 2010 CFR

...River Bar “C” buoy and extending eastward on the Columbia River to Kennewick, WA and upriver through Lewiston, ID on the Snake River. (d) Compliance. The large passenger vessel security and safety zone established by this section...

2010-07-01

59

33 CFR 165.1318 - Security and Safety Zone Regulations, Large Passenger Vessel Protection, Captain of the Port...  

...River Bar “C” buoy and extending eastward on the Columbia River to Kennewick, WA and upriver through Lewiston, ID on the Snake River. (d) Compliance. The large passenger vessel security and safety zone established by this section...

2014-07-01

60

Breaking size segregation waves and particle recirculation in granular avalanches  

NASA Astrophysics Data System (ADS)

Particle-size segregation is a common feature of dense gravity-driven granular free-surface flows, where sliding and frictional grainlens’-like structure. A high-resolution shock-capturing numerical scheme is used to investigate the temporal evolution of a linearly decreasing shock towards a steady-state lens, as well as the interaction of two recirculation zones that travel at different speeds and eventually coalesce to form a single zone. Movies are available with the online version of the paper.

Thornton, A. R.; Gray, J. M. N. T.

61

Repeating and not so Repeating Large Earthquakes in the Mexican Subduction Zone  

NASA Astrophysics Data System (ADS)

The rupture area and recurrence interval of large earthquakes in the mexican subduction zone are relatively small and almost the entire length of the zone has experienced a large (Mw?7.0) earthquake in the last 100 years (Singh et al., 1981). Several segments have experienced multiple large earthquakes in this time period. However, as the rupture areas of events prior to 1973 are only approximately known, the recurrence periods are uncertain. Large earthquakes occurred in the Ometepec, Guerrero, segment in 1937, 1950, 1982 and 2012 (Singh et al., 1981). In 1982, two earthquakes (Ms 6.9 and Ms 7.0) occurred about 4 hours apart, one apparently downdip from the other (Astiz & Kanamori, 1984; Beroza et al. 1984). The 2012 earthquake on the other hand had a magnitude of Mw 7.5 (globalcmt.org), breaking approximately the same area as the 1982 doublet, but with a total scalar moment about three times larger than the 1982 doublet combined. It therefore seems that 'repeat earthquakes' in the Ometepec segment are not necessarily very similar one to another. The Central Oaxaca segment broke in large earthquakes in 1928 (Mw7.7) and 1978 (Mw7.7) . Seismograms for the two events, recorded at the Wiechert seismograph in Uppsala, show remarkable similarity, suggesting that in this area, large earthquakes can repeat. The extent to which the near-trench part of the fault plane participates in the ruptures is not well understood. In the Ometepec segment, the updip portion of the plate interface broke during the 25 Feb 1996 earthquake (Mw7.1), which was a slow earthquake and produced anomalously low PGAs (Iglesias et al., 2003). Historical records indicate that a great tsunamigenic earthquake, M~8.6, occurred in the Oaxaca region in 1787, breaking the Central Oaxaca segment together with several adjacent segments (Suarez & Albini 2009). Whether the updip portion of the fault broke in this event remains speculative, although plausible based on the large tsunami. Evidence from the mexican subduction zone therefore suggests that even if the same segments breaks repeatedly, individual earthquakes may or may not be similar. Furthermore, at least some of the segments can participate in larger earthquakes involving adjacent segments. The near trench part has only broken in two known large events, 800 km apart, the 1995 Jalisco (Mw8.0) and the 1996 event in the Ometepec segment. If the near-trench fault area between these two events can rupture seismically, and participate in larger events together with downdip segments, there would be important implications for seismic and tsunami hazard. In this presentation we review the earthquake history of the region and demonstrate the similarity and non-similarity of earthquakes in repeatedly breaking subduction zone segments, with particular emphasis on our recent work on events in the Ometepec segment.

Hjorleifsdottir, V.; Singh, S.; Iglesias, A.; Perez-Campos, X.

2013-12-01

62

Unusually large shear wave anisotropy for chlorite in subduction zone settings  

NASA Astrophysics Data System (ADS)

first principle simulations we calculated the elasticity of chlorite. At a density ?~ 2.60 g cm-3, the elastic constant tensor reveals significant elastic anisotropy: VP ~27%, VS1 ~56%, and VS2 ~43%. The shear anisotropy is exceptionally large for chlorite and enhances upon compression. Upon compression, the shear elastic constant component C44 and C55 decreases, whereas C66 shear component stiffens. The softening in C44 and C55 is reflected in shear modulus, G, and the shear wave velocity, VS. Our results on elastic anisotropy at conditions relevant to the mantle wedge indicates that a 10-20 km layer of hydrated peridotite with serpentine and chlorite could account for the observed shear polarization anisotropy and associated large delay times of 1-2 s observed in some subduction zone settings. In addition, chlorite could also explain the low VP/VS ratios that have been observed in recent high-resolution seismological studies.

Mookherjee, Mainak; Mainprice, David

2014-03-01

63

Solar Sail - Fresnel Zone Plate Lens for a Large Space Based Telescope  

SciTech Connect

A Fresnel zone plate lens made with solar sail material could be used as the primary optic for a very large aperture telescope on deep space probes propelled by solar sails. The large aperture telescope capability could enable significant science on fly-by missions to the asteroids, Pluto, Kuiper belt or the tort cloud and could also enable meaningful interstellar fly-by missions for laser propelled sails. This type of lens may also have some potential for laser communications and as a solar concentrator. The techniques for fabrication of meter size and larger Fresnel phase plate optics are under development at LLNL, and we are extending this technology to amplitude zone plates made from sail materials. Corrector optics to greatly extend the bandwidth of these Fresnel optics will be demonstrated in the future. This novel telescope concept will require new understanding of the fabrication, deployment and control of gossamer space structures. It will also require new materials technology for fabricating these optics and understanding their long term stability in a space environment.

Early, J T

2002-02-13

64

Invited review paper: Seismicity along the South American subduction zone: Review of large earthquakes, tsunamis, and subduction zone complexity  

Microsoft Academic Search

Earthquakes along the shallow South American subduction zone exhibit heterogeneous rupture characteristics, going back several centuries of the earthquake record in this area. This heterogeneity is manifest in several ways, such as changes in rupture mode from magnitude >8 events during one century followed by smaller ones in other time periods, as well as unusual tsunami events. There is also

Susan L. Bilek

2010-01-01

65

Compromise between ventilation, filtration strategies and recirculation rates for the design and operation of air-conditioned facilities in the tropics  

Microsoft Academic Search

This study examines the impact of filtration, ventilation and recirculation rate on concentration of condensed-phase, ozone (of outdoor origin)-derived oxidation products (secondary organic aerosols (SOA)) in a model room with a ventilation system that recirculates a large percentage (90%) of its supply air. Additionally, it critically evaluates the potential approach for filtering recirculated air and also avoiding the negative consequence

Moshood Olawale Fadeyi

2012-01-01

66

Recirculation anaesthesia for laboratory fish  

Microsoft Academic Search

Summary An economic reliable long-term recirculation anaesthesia system for laboratory fish is des- cribed. Anaesthesia of channel catfish (\\/ctalurus punctatus Rafinesque) was induced within 60 s and was maintained for up to 40 min using tricaine methanesulphonate; recovery occurred within 30-60 s. Various surgical procedures were performed on the fish. No deaths were recorded. All water-quality parameters tested over 19

L. A. Brown

1987-01-01

67

Chronology of historical tsunamis in Mexico and its relation to large earthquakes along the subduction zone  

NASA Astrophysics Data System (ADS)

The chronology of historical earthquakes along the subduction zone in Mexico spans a time period of approximately 400 years. Although the population density along the coast of Mexico has always been low, relative to that of central Mexico, several of the large subduction earthquakes reports include references to the presence of tsunamis invading the southern coast of Mexico. Here we present a chronology of historical tsunamis affecting the Pacific coast of Mexico and compare this with the historical record of subduction events and to the existing Mexican and worldwide catalogs of tsunamis in the Pacific basin. Due to the geographical orientation of the Pacific coat of Mexico, tsunamis generated on the other subduction zones of the Pacific have not had damaging effects in the country. Among the tsunamis generated by local earthquakes, the largest one by far is the one produced by the earthquake of 28 March 1787. The reported tsunami has an inundation area that reaches for over 6 km inland. The length of the coast where the tsunami was reported extends for over 450 km. In the last 100 years two large tsunamis have been reported along the Pacific coast of Mexico. On 22 June 1932 a tsunami with reported wave heights of up to 11 m hit the coast of Jalisco and Colima. The town of Cuyutlan was heavily damaged and approximately 50 people lost their lives do to the impact of the tsunami. This unusual tsunami was generated by an aftershock (M 6.9) of the large 3 June 1932 event (M 8.1). The main shock of 3 June did not produce a perceptible tsunami. It has been proposed that the 22 June event is a tsunami earthquake generated on the shallow part of the subduction zone. On 16 November 1925 an unusual tsunami was reported in the town of Zihuatanejo in the state of Guerrero, Mexico. No earthquake on the Pacific rim occurs at the same time as this tsunami and the historical record of hurricanes and tropical storms do not list the presence of a meteorological disturbance that could explain a surge wave of the height reported. Here we investigate the morphology of the trench in this region to analyze whether a local landslide on the trench slope or in the continental shelf could be the cause of this tsunami.

Suarez, G.; Mortera, C.

2013-05-01

68

Contamination of port zone sediments by metals from Large Marine Ecosystems of Brazil.  

PubMed

Sediment contamination by metals poses risks to coastal ecosystems and is considered to be problematic to dredging operations. In Brazil, there are differences in sedimentology along the Large Marine Ecosystems in relation to the metal distributions. We aimed to assess the extent of Al, Fe, Hg, Cd, Cr, Cu, Ni, Pb and Zn contamination in sediments from port zones in northeast (Mucuripe and Pecém) and southeast (Santos) Brazil through geochemical analyses and sediment quality ratings. The metal concentrations found in these port zones were higher than those observed in the continental shelf or the background values in both regions. In the northeast, metals were associated with carbonate, while in Santos, they were associated with mud. Geochemical analyses showed enrichments in Hg, Cd, Cu, Ni and Zn, and a simple application of international sediment quality guidelines failed to predict their impacts, whereas the use of site-specific values that were derived by geochemical and ecotoxicological approaches seemed to be more appropriate in the management of the dredged sediments. PMID:22306311

Buruaem, Lucas M; Hortellani, Marcos A; Sarkis, Jorge E; Costa-Lotufo, Leticia V; Abessa, Denis M S

2012-03-01

69

Toroidal transducer with two large focal zones for increasing the coagulated volume  

NASA Astrophysics Data System (ADS)

Toroidal HIFU transducers have been shown to generate large conical ablations (7 cm3 in 40 seconds). The focal zone is composed of a first ring-shaped focal zone and an overlap of ultrasound beams behind this first focus. A HIFU device has been developed on this principle to treat liver metastases during an open procedure. Although these large lesions contribute to reduce treatment time, it is still needed to juxtapose 4 to 9 single HIFU lesions to treat liver metastasis (2 cm in diameter) with safety margins. In this work, a different toroidal geometry was used. With this transducer, the overlap area is located between the probe and the focal ring. The objective was to use this transducer with electronic focusing in order to create a spherical shape lesion with sufficient volume for the destruction of a metastasis of 2 cm in diameter without any mechanical displacement. The operating frequency of the toroidal transducer was 2.5 MHz. The radius of curvature was 70 mm with a diameter of 67 mm. The focal ring had a radius of 15 mm. The overlap zone extent between 35 to 55 mm from the emitting surface. An ultrasound-imaging probe (working at 7.5 MHz) was placed in a central circular opening of 26 mm in the HIFU transducer and was aligned with the focal plane. The transducer was divided into 32 rings of 78 mm2. Using a 32 channels amplifier with a phase resolution of 1.4 degrees, it was possible to change the diameter (0 to 15 mm) and depth (45 to 85 mm) of the focus circle to maximize dimensions of the lesion. Tests were conducted in vitro, in bovine liver samples. This toroidal geometry and the use of electronic beam steering allow the creation of roughly spherical lesions (diameter of 47 mm, depth of 35 mm). This treatment was obtained in 6 minutes and 10 seconds without any mechanical displacement of the transducer. The lesions obtained were homogeneous and no untreated area was observed. In conclusion, these results indicate that the treatment of a liver metastasis up to 2 cm in diameter is conceivable with safety margins. An in vivo validation on porcine model is under progress.

Vincenot, J.; Melodelima, D.; Kocot, A.; Chavrier, F.; Chapelon, J. Y.

2012-11-01

70

Growth of large single crystals using the improved lamp-image floating-zone furnace: application to ?  

NASA Astrophysics Data System (ADS)

We grew large single crystals of 0953-2048/11/9/011/img10 reproducibly over a wide doping range using an improved travelling solvent floating zone (TSFZ) method. We performed a simulation on the lamp-image focusing to find an optimum condition for a steep temperature gradient along the rod. Based on the results of simulation, we adapted smaller lamps and shielded the partial area of the mirror surfaces. The improvement of the focusing had a great effect on keeping the molten zone stable for more than 100 h. Stabilization of the molten zone improves both the reproducibility of the crystal growth and the quality of the grown crystals.

Lee, Chul-Ho; Kaneko, Nobuhisa; Hosoya, Syoichi; Kurahashi, Kenji; Wakimoto, Shuichi; Yamada, Kazuyoshi; Endoh, Yasuo

1998-09-01

71

Large-Scale Structures in the Zone of Avoidance: The Galactic Anticenter Region  

NASA Technical Reports Server (NTRS)

We have selected a sample of 876 galaxy candidates from the IRAS Point Source Catalog in the region of 2(exp h) < alpha < 10(exp h) and 0 deg < delta < 36 deg, which crosses the Galactic anticenter part of the Zone of Avoidance (ZOA) and includes most of the highly obscured Orion-Taurus complex region. We have identified galaxies among the candidate sources by attempting to detect the 21 cm H I line of those sources which were not known to be galaxies at the beginning of the survey. In this manner, we constructed a galaxy sample which is largely free from Galactic reddening. Of the 272 observed candidates, 89 were detected in the H I line up to a heliocentric velocity of v(sub h) approximately 16,000 km/s. The resulting galaxy sample of 717 galaxies is fairly complete (within about 10%) and uniform (within about 4%) in the part of the survey area 10 deg away from the Galactic plane and for velocities up to at least 9000 km/s. This provides, for the first time, a largely unbiased view on the large-scale structures in much of the survey area. Our main results are the following: (1) Several large voids are identified. In particular, a void between alpha approximately equals 3(sup h) and 4(sup h), up to v(sub h) approximately 6000 km/s, separates the Pisces-Perseus supercluster at alpha < 3(sup h) from structures at alpha > 4(sup h); and a "nearby void" occupies most of our survey area and reaches out to a redshift of nearly 3000 km/s. (2) We found no nearby galaxy concentration that could significantly contribute to the "Local Velocity Anomoly" (LVA), but a general excess of galaxies around v(sub h) approximately 5000 km/s in the survey area. (3) The contrast between the "Great Wall" at v(sub h) approximately 8500 km/s and the void in front of it appears to gradually diffuse out after it enters the Zone of Avoidance from the northern Galactic hemisphere. (4) Our data combined with other galaxy surveys in or near the Galactic anticenter part of the ZOA suggest that the main ridge of the Pisces-Perseus supercluster does not extend to Abell 569, a cluster in the northern Galactic hemisphere, and that the simple gravitational model consisting of the Local Void of Tully & Fisher, our nearby void, and Puppis and Fornax-Eridanus clusters would predict a LVA whose direction is probably too far away from that derived from observations.

Lu, Nanyao Y.; Freudling, Wolfram

1995-01-01

72

Na+ recirculation and isosmotic transport.  

PubMed

The Na(+) recirculation theory for solute-coupled fluid absorption is an expansion of the local osmosis concept introduced by Curran and analyzed by Diamond & Bossert. Based on studies on small intestine the theory assumes that the observed recirculation of Na(+) serves regulation of the osmolarity of the absorbate. Mathematical modeling reproducing bioelectric and hydrosmotic properties of small intestine and proximal tubule, respectively, predicts a significant range of observations such as isosmotic transport, hyposmotic transport, solvent drag, anomalous solvent drag, the residual hydraulic permeability in proximal tubule of AQP1 (-/-) mice, and the inverse relationship between hydraulic permeability and the concentration difference needed to reverse transepithelial water flow. The model reproduces the volume responses of cells and lateral intercellular space (lis) following replacement of luminal NaCl by sucrose as well as the linear dependence of volume absorption on luminal NaCl concentration. Analysis of solvent drag on Na(+) in tight junctions provides explanation for the surprisingly high metabolic efficiency of Na(+) reabsorption. The model predicts and explains low metabolic efficiency in diluted external baths. Hyperosmolarity of lis is governed by the hydraulic permeability of the apical plasma membrane and tight junction with 6-7 mOsm in small intestine and < or = 1 mOsm in proximal tubule. Truly isosmotic transport demands a Na(+) recirculation of 50-70% in small intestine but might be barely measurable in proximal tubule. The model fails to reproduce a certain type of observations: The reduced volume absorption at transepithelial osmotic equilibrium in AQP1 knockout mice, and the stimulated water absorption by gallbladder in diluted external solutions. Thus, it indicates cellular regulation of apical Na(+) uptake, which is not included in the mathematical treatment. PMID:17206513

Larsen, E H; Møbjerg, N

2006-01-01

73

Austral winter distributions of large tintinnid and large sarcodinid protozooplankton in the ice-edge zone of the Weddell/Scotia Seas  

NASA Astrophysics Data System (ADS)

Seasonal distribution and abundance data for large sarcodinid protozooplankton (Radiolaria, Foraminifera, Acantharia and the heliozoan Sticholonche spp.) and larger tintinnid ciliates (e.g., Laackmaniella spp.) are necessary for evaluating their roles in food webs and particle fluxes. As part of the Antarctic Marine Ecosystem Research in the Ice Edge Zone (AMERIEZ) project, we sampled these large (? 50 ?m) protozooplankton in the winter ice edge zone of the Scotia/Weddell Seas. Organisms alive at the time of capture were counted in large volume (60 1) water samples from 5 paired depths in the upper 210 m from 17 stations. Relationships between abundances and environmental factors in ice-covered, ice edge, and open waters were assessed with correlation, cluster, and multidimensional scaling analyses. Mean abundances of large tintinnids were less than 3150 per m 3, and mean abundances of the individual sarcodine groups were generally less than 1000 per m 3. The most pronounced distributional patterns were related to depth. In general, large tintinnids were more abundant in the colder waters from 0-85 m, a zone encompassed by the mixed layer and the euphotic zone. Acantharians were more abundant in this upper zone only in ice-covered waters. Radiolaria (predominantly phaeodarians) and the heliozoan Sticholonche spp. were more abundant from 115 to 210 m, a zone of warmer, more saline water. Foraminiferan distributions showed little pattern with depth. Results of the cluster analyses also suggested that depth was the most significant effect determining similarity among assemblages of large protozooplankton at the 17 stations. The few correlations between abundances of the groups and chlorophyll a probably reflect relationships more complex than grazing. Abundances of large tintinnids were higher in surface waters under the ice than at the ice edge or in open water. This could result from their feeding on algal cells released from the base of the ice or it may be a result of higher populations in the outflow of Weddell Sea water. There were no consistent abundance patterns among large sarcodines that could be related to ice cover. It is suggested that the combination of low winter productivity, a dynamic environment, and slower growth rates of these large protozoans may prevent them from responding to local enhanced production with increased abundances in the winter ice edge zone. Furthermore, although there is enhanced productivity at the ice edge, this signal may not reach the protozooplankton groups most abundant in the water layer below the euphotic zone.

Gowing, Marcia M.; Garrison, David L.

1991-07-01

74

Recirculation in multiple wave conversions  

SciTech Connect

A one-dimensional multiple wave-conversion model is constructed that allows energy recirculation in ray phase space. Using a modular eikonal approach, the connection coefficients for this model are calculated by ray phase-space methods. Analytical results (confirmed numerically) show that all connection coefficients exhibit interference effects that depend on an interference phase, calculated from the coupling constants and the area enclosed by the intersecting rays. This conceptual model, which focuses on the topology of intersecting rays in phase space, is used to investigate how mode conversion between primary and secondary waves is modified by the presence of a tertiary wave.

Kaufman, A. N.; Brizard, A.J.; Kaufman, A.N.; Tracy, E.R.

2008-07-30

75

Recirculation in multiple wave conversions  

SciTech Connect

A one-dimensional multiple wave-conversion model is constructed that allows energy recirculation in ray phase space. Using a modular eikonal approach, the connection coefficients for this model are calculated by ray phase-space methods. Analytical results (confirmed numerically) show that all connection coefficients exhibit interference effects that depend on an interference phase, calculated from the coupling constants and the area enclosed by the intersecting rays. This conceptual model, which focuses on the topology of intersecting rays in phase space, is used to investigate how mode conversion between primary and secondary waves is modified by the presence of a tertiary wave.

Brizard, A. J. [Department of Chemistry and Physics, Saint Michael's College, Colchester, Vermont 05439 (United States); Kaufman, A. N. [Department of Physics and Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States); Tracy, E. R. [Department of Physics, College of William and Mary, Williamsburg, Virginia 23187-8795 (United States)

2008-08-15

76

Gas recirculator for acyclic machines  

NASA Astrophysics Data System (ADS)

The present invention relates to acyclic machines of the type using liquid metal collectors, and more particularly to an improvement for retaining the liquid metal in such machines. Radial type acyclic motors and generators generally include a metallic disk rotor rotating on a shaft between electromagnetic stator poles excited by field coils wound concentric with the shaft. Instead of solid brush, current collectors at the rotor periphery, liquid metal collectors are sometimes used to close the electrical current loop between the shaft and the rotor, and an inert pressurized cover gas fills the gaps between the rotating components and the stationary housing. A cover has recirculator in an acyclic generator having liquid metal collectors for reducing entrainment of the liquid metal in the gas. Radial passages in the stator housing provide natural recirculating paths for the cover gas to flow radially outward along the sides of the rotor and return inwardly through the passages. Scoops or lips located inward of the liquid metal collector divert the outward gas flow into the passages to minimize contact of the gas with the liquid metal.

Balsa, T. F.

1985-05-01

77

Denitrification in recirculating systems: Theory and applications  

Microsoft Academic Search

Profitability of recirculating systems depends in part on the ability to manage nutrient wastes. Nitrogenous wastes in these systems can be eliminated through nitrifying and denitrifying biofilters. While nitrifying filters are incorporated in most recirculating systems according to well-established protocols, denitrifying filters are still under development. By means of denitrification, oxidized inorganic nitrogen compounds, such as nitrite and nitrate are

Jaap van Rijn; Yossi Tal; Harold J. Schreier

2006-01-01

78

A recirculating hydroponic system for studying peanut (Arachis hypogaea L.)  

NASA Technical Reports Server (NTRS)

Peanut (Arachis hypogaea L.) plants were grown hydroponically, using continuously recirculating nutrient solution. Two culture tray designs were tested; one tray design used only nutrient solution, while the other used a sphagnum-filled pod development compartment just beneath the cover and above the nutrient solution. Both trays were fitted with slotted covers to allow developing gynophores to reach the root zone. Peanut seed yields averaged 350 gm-2 dry mass, regardless of tray design, suggesting that substrate is not required for hydroponic peanut production.

Mackowiak, C. L.; Wheeler, R. M.; Stutte, G. W.; Yorio, N. C.; Ruffe, L. M.; Sager, J. C. (Principal Investigator)

1998-01-01

79

Quality Evaluation of Cone Biopsy Specimens Obtained by Large Loop Excision of the Transformation Zone  

PubMed Central

Background Large loop excision of the transformation zone (LLETZ) has been used for the diagnosis and treatment of precancerous cervical lesions, and it is the first choice of treatment in the majority of cervical pathology services. The aim of this study was to evaluate the presence of thermal artifacts, the need for serial sections, the percentage of clear and involved resection margins and the relationship between endocervical gland involvement and the severity of the lesion in samples resected using LLETZ. Methods A retrospective study was performed at Santa Casa de Misericordia School of Science (HSCMV), Vitoria, Espirito Santo, Brazil with a sample of 52 histopathology slides from patients submitted to conization because of abnormal cytology findings and a biopsy result of cervical intraepithelial neoplasia (CIN) 2, CIN 3 and adenocarcinoma in situ. Statistical analysis was performed using Student’s t-test. Results Serial sections were required to confirm diagnosis in four of 52 cases. Thermal artifacts were present in all cases, with grade I being the most common (94.2% of cases). Clear margins were found in 96.2% of cases. No association was found between glandular involvement and CIN 1 (P > 0.05); however, there was an association with CIN 2 and CIN 3 (P < 0.05). Conclusion The amount of excised tissue was sufficient, thermal artifacts were slight, resection margins were clear in most of cases, and a possible association was found between glandular involvement and the severity of the lesion.

Garcia Ramos, Aristoteles Mauricio; Garcia Ramos, Erika Souza; dos Reis, Helena Lucia Barroso; de Rezende, Ricardo Bueno

2015-01-01

80

77 FR 65816 - Safety Zone; Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to Mile Marker...  

Federal Register 2010, 2011, 2012, 2013

...moving safety zone around large cruise ships as they transit the Lower...between the Port of New Orleans Cruise Ship Terminal, mile marker...and one-mile astern of each cruise ship. This safety measure...hazards associated with congested maritime traffic on the Lower...

2012-10-31

81

Observer-based control of vortex motion in a combustor recirculation region  

Microsoft Academic Search

Established paradigms for observers design are yet a missing component in efforts to introduce feedback control of turbulent flows. This case study concerns tracking a reference orbit in a combustor recirculation zone. Actuation is by perturbations of a corner potential, and the sensed output is fluid velocity at a single boundary point. Control design is based on a single vortex

Gilead Tadmor; Andrzej Banaszuk

2002-01-01

82

Diesel engine exhaust gas recirculation––a review on advanced and novel concepts  

Microsoft Academic Search

Exhaust gas recirculation (EGR) is effective to reduce nitrogen oxides (NOx) from Diesel engines because it lowers the flame temperature and the oxygen concentration of the working fluid in the combustion chamber. However, as NOx reduces, particulate matter (PM) increases, resulting from the lowered oxygen concentration. When EGR further increases, the engine operation reaches zones with higher instabilities, increased carbonaceous

Ming Zheng; Graham T. Reader; J. Gary Hawley

2004-01-01

83

Lesser Antilles Subduction Zone Investigation by a Cluster of Large Seismic Experiments in the Forearc Region  

NASA Astrophysics Data System (ADS)

Thales LAST stands for Lesser Antilles Subduction zone Team which gathers the scientific teams of a cluster of surveys and cruises that have been carried out in 2007 and coordinated under the European Union THALES WAS RIGHT project (Coord. A. Hirn). This cluster is composed by the German cruise TRAIL with the vessel F/S Merian (PI E. Flueh and H. Kopp, IFM-GEOMAR), the French cruise SISMANTILLES 2 with the IFREMER vessel N/O Atalante (PI M. Laigle, IPG Paris and JF. Lebrun, Univ. Antilles Guyane), and French cruise OBSANTILLES with the IRD vessel N/O Antea (PI P. Charvis, Geoazur, Nice, France). During these cruises and surveys, 84 Ocean Bottom 3-components Seismometers (OBS) and 20 Hydrophones (OBHs) have been brought together from several pools (Geoazur, INSU, IPGP, IFM-GEOMAR, AWI,), with up to 30 land stations (CSIC Barcelone, IPG Paris, INSU-RLBM and -LITHOSCOPE) in addition to the permanent onshore arrays of IPGP and SRU. The deployment of all these instruments has been supported principally by ANR Catastrophes Telluriques et Tsunamis (SUBSISMANTI), by the EU SALVADOR Programme of IFM-GEOMAR, as well as by the EU project THALES WAS RIGHT on the Antilles and Hellenic active subductions to which contribute IPGP, Geoazur, IFM-GEOMAR (Germany), ETH Zurich (Switzerland), CSIC Barcelona (Spain), Univ. Trieste (Italy) and NOA Athens (Greece). The main goal of this large seismic investigation effort is the understanding of the behaviour of the seismogenic zone and location of potential source regions of mega-thrust earthquakes. Specific goals are the mapping of the subduction interplate in the range where it may be seismogenic along the Lesser Antilles Arc from Antigua to southern Martinique Islands, as a contribution to identification and localisation in advance of main rupture zones of possible future major earthquakes, and to the search for transient signals of the activity. The forearc region, commonly considered as a proxy to the seismogenic portion of the subduction mega-thrust fault plane, and which is here the main target has been localized along 3 transects to the Arc thanks to a preliminary survey in 2001, the French SISMANTILLES cuise. We will present the first results obtained during these experiments dedicated specifically to image at depth the seismic structure and activity of this region. To image faults at depth and the detailed upper-crustal structure, 3700 km of multi-beam bathymetry and multi-channel reflection seismic profiles have been collected along a grid comprising 7 strike-lines of up to 300 km long and spaced by 15 km and 12 transects of up to 150 km long and spaced by 25 km (SISMANTILLES 2). All these airgun shots dedicated to deep penetration have been recorded by the 84 OBSs and 20 OBHs deployed by the F/S Merian and N/O Atalante on the nodes of this grid of profiles. It will permit to get Vp constraints on the deep forearc region and mantle wedge by wide-angle refraction studies, as well as constraints on the updip and downdip limits of the seismogenic part of the mega-thrust fault plane. Two of these transects have been extended across the whole arc during the TRAIL survey, with up to 50 OBSs deployed along both 240 km long profiles. All these OBSs remained several months beyond the shot experiments for local earthquakes Vp and Vp/Vs tomography. They have been recovered and partly redeployed by N/O Antea during the OBSANTILLES survey. A significant number of those instruments had broadband seismometers, a notable originality in the case of the OBSs to detect low-frequency transient signals.

Last, T.

2007-12-01

84

Xenon recirculation-purification with a heat exchanger  

Microsoft Academic Search

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling

K. L. Giboni; E. Aprile; B. Choi; T. Haruyama; R. F. Lang; K. E. Lim; A. J. Melgarejo; G. Plante

2011-01-01

85

Effects of a large northern European no-take zone on flatfish populations.  

PubMed

In March 2006, a 360?km² no-take zone (NTZ) was established north of Gotland in the central Baltic Sea, with the purpose to scientifically evaluate the effects of a fishing ban on flatfish populations. A monitoring programme was set up to study the populations in the NTZ and in a reference area east of Gotland where the fishing pressure was high. The programme included fishing with multimesh survey nets, modelling of potential larval export and estimation of fish consumption by large marine predators. Overall, the results showed a clear positive effect of the NTZ on turbot Scophthalmus maximus, with higher densities in the closed area compared with the fished area and also higher densities after closure compared with before. The NTZ also had older individuals and a more even sex ratio. This, in combination with a high potential for larval export from the NTZ to Gotland, shows that the marine reserve may be important for maintaining a viable S. maximus stock at Gotland. Also, for flounder Platichthys flesus, the densities were higher in the NTZ compared to the reference area and there was a net larval export to the fished area. For both species, density-dependent growth was evident, with a lower length at age in the closed area. Potential predation by grey seal Halichoerus grypus and great cormorant Phalacrocorax carbo sinesis on flatfishes, that could hamper the evaluation of the marine reserve, was also addressed. Taken together, the results show that there are clear benefits of the fishing ban for both flatfish species within the NTZ, while the net effects on fisheries are difficult to quantify. PMID:24090556

Florin, A-B; Bergström, U; Ustups, D; Lundström, K; Jonsson, P R

2013-10-01

86

Xenon Recirculation-Purification with a Heat Exchanger  

E-print Network

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling power is spent to compensate losses from recirculation. The phase change during recondensing requires five times more cooling power than cooling the gas from ambient temperature to -100C (173 K). Thus, to reduce the cooling power requirements for large detectors, we propose to use the heat from the purified incoming gas to evaporate the outgoing xenon gas, by means of a heat exchanger. Generally, a heat exchanger would appear to be only of very limited use, since evaporation and liquefaction occur at zero temperature difference. However, the use of a recirculation pump reduces the pressure of the extracted liquid, forces it to evaporate, and thus cools it down. We show that this temperature difference can be used for an efficient heat exchange process. We investigate the use of a commercial parallel plate heat exchanger with a small liquid xenon detector. Although we expected to be limited by the available cooling power to flow rates of about 2 SLPM, rates in excess of 12 SLPM can easily be sustained, limited only by the pump speed and the impedance of the flow loop. The heat exchanger operates with an efficiency of (96.8 +/- 0.5)%. This opens the possibility for fast xenon gas recirculation in large-scale experiments, while minimizing thermal losses.

K. L. Giboni; E. Aprile; B. Choi; T. Haruyama; R. F. Lang; K. E. Lim; A. J. Melgarejo; G. Plante

2011-03-04

87

TANK MIXING STUDY WITH FLOW RECIRCULATION  

SciTech Connect

The primary objective of this work is to quantify the mixing time when two miscible fluids are mixed by one recirculation pump and to evaluate adequacy of 2.5 hours of pump recirculation to be considered well mixed in SRS tanks, JT-71/72. The work scope described here consists of two modeling analyses. They are the steady state flow pattern analysis during pump recirculation operation of the tank liquid and transient species transport calculations based on the initial steady state flow patterns. The modeling calculations for the mixing time are performed by using the 99% homogeneity criterion for the entire domain of the tank contents.

Lee, S.

2014-06-25

88

Normal zone detectors for a large number of inductively coupled coils  

SciTech Connect

In order to protect a set of inductively coupled superconducting magnets, it is necessary to locate and measure normal zone voltages that are small compared with the mutual and self-induced voltages. The method described in this report uses two sets of voltage measurements to locate and measure one or more normal zones in any number of coupled coils. One set of voltages is the outputs of bridges that balance out the self-induced voltages The other set of voltages can be the voltages across the coils, although alternatives are possible. The two sets of equations form a single combined set of equations. Each normal zone location or combination of normal zones has a set of these combined equations associated with it. It is demonstrated that the normal zone can be located and the correct set chosen, allowing determination of the size of the normal zone. Only a few operations take plae in a working detector: multiplication of a constant, addition, and simple decision-making. In many cases the detector for each coil, although weakly linked to the other detectors, can be considered to be independent. An example of the detector design is given for four coils with realistic parameters. The effect on accuracy of changes in the system parameters is discussed.

Owen, E.W.; Shimer, D.W.

1983-01-10

89

Xenon Recirculation-Purification with a Heat Exchanger  

E-print Network

Liquid-xenon based particle detectors have been dramatically growing in size during the last years, and are now exceeding the one-ton scale. The required high xenon purity is usually achieved by continuous recirculation of xenon gas through a high-temperature getter. This challenges the traditional way of cooling these large detectors, since in a thermally well insulated detector, most of the cooling power is spent to compensate losses from recirculation. The phase change during recondensing requires five times more cooling power than cooling the gas from ambient temperature to -100C (173 K). Thus, to reduce the cooling power requirements for large detectors, we propose to use the heat from the purified incoming gas to evaporate the outgoing xenon gas, by means of a heat exchanger. Generally, a heat exchanger would appear to be only of very limited use, since evaporation and liquefaction occur at zero temperature difference. However, the use of a recirculation pump reduces the pressure of the extracted liquid...

Giboni, K L; Choi, B; Haruyama, T; Lang, R F; Lim, K E; Melgarejo, A J; Plante, G; 10.1088/1748-0221/6/03/P03002

2011-01-01

90

Recovery of coastal ecosystems after large tsunamis in various climatic zones - review of cases from tropical, temperate and polar zones (Invited)  

NASA Astrophysics Data System (ADS)

Large tsunamis cause significant changes in coastal ecosystems. They include modifications in shoreline position, sediment erosion and deposition, new initial soil formation, salination of soils and waters, removal of vegetation, as well as direct impact on humans and infrastructure. The processes and rate of coastal zone recovery from large tsunamis has been little studied but during the last decade a noteworthy progress has been made. This study focus on comparison of recovery processes in various climatic zones, namely in monsoonal-tropical, temperate and polar zone. It is based on own observation and monitoring in areas affected by 2004 Indian Ocean Tsunami in Thailand, 2011 Tohoku-oki tsunami in Japan and 2000 Paatuut landslide-generated tsunami in Vaigat Strait (west Greenland), as well as on review of published studies from those areas. The particular focus is on physical and biological recoveries of beaches, recovery of coastal vegetation, new soil formation in eroded areas and those covered by tsunami deposits, marine salt removal from soils, surface- and groundwater, as well as landscape adjustment after the tsunamis. The beach zone - typically the most tsunami-eroded zone, has been recovered already within weeks to months and has been observed to be in the pre-tsunami equilibrium stage within one year in all the climate zones, except for sediment-starved environments. The existing data on beach ecosystems point also to relatively fast recovery of meio- and macrofauna (within weeks to several months). The recovery of coastal vegetation depends on the rate of salt removal from soils or on the rate of soil formation in case of its erosion or burial by tsunami deposits. The salt removal have been observed to depend mainly on precipitation and effective water drainage. In tropical climate with seasonal rainfall of more 3000 mm the salt removal was fast, however, in temperate climate with lower precipitation and flat topography the salinities still exceeded the recommended concentrations for freshwater plants after one year. The new soil formation and vegetation recovery depends mainly on the rate of biological production. In tropical climate the vegetation largely recovered already after the first rainy season and supported the new soil formation. In temperate climate this process was much slower, in particular in flat lying areas and on coastal dunes with poor sandy soils. In polar climate only limited vegetation recovery (mainly of Salix species) has been observed after 12 years and vegetation withered due to salt stress still marked the tsunami inundation limit and the new soil formation was very slow and focused on low lying, wet areas buried with thin tsunami deposits cover. The post-tsunami recovery processes may be grouped into climate-related (vegetation recovery, removal of salts from soils) and non climate-related (e.g. beach recovery) or modified by climatic and local factors (for instance, the rate of tsunami deposits reworking and thus new soil formation). The rate of recovery varies from days / weeks as in case of beach recovery to several decades as in case of new soil formation on tsunami deposits. The study was partly funded by Polish National Science Centre grant No. 2011/01/B/ST10/01553. The review results from studies in collaboration with number of researchers from Australia, Japan, Poland, Thailand, United Kingdom and United States to whom I express sincere thanks.

Szczucinski, W.

2013-12-01

91

Exhaust gas recirculation control system for internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation control system for controlling the amount of exhaust gas subjected to recirculation to the air inlet depending on the amount of inlet air of an internal combustion engine is described. This system comprises a control valve disposed in an exhaust gas recirculation passage, for controlling the amount of exhaust gas recirculation, an orifice disposed in the

T. Ito; T. Nishimiya; S. Numakura; M. Okumura

1980-01-01

92

Recirculating cross-correlation detector  

DOEpatents

A digital cross-correlation detector is provided in which two time-varying signals are correlated by repetitively comparing data samples stored in digital form to detect correlation between the two signals. The signals are sampled at a selected rate converted to digital form, and stored in separate locations in separate memories. When the memories are filled, the data samples from each memory are first fed word-by-word through a multiplier and summing circuit and each result is compared to the last in a peak memory circuit and if larger than the last is retained in the peak memory. Then the address line to leading signal memory is offset by one byte to affect one sample period delay of a known amount in that memory and the data in the two memories are then multiplied word-by-word once again and summed. If a new result is larger than a former sum, it is saved in the peak memory together with the time delay. The recirculating process continues with the address of the one memory being offset one additional byte each cycle until the address is shifted through the length of the memory. The correlation between the two signals is indicated by the peak signal stored in the peak memory together with the delay time at which the peak occurred. The circuit is faster and considerably less expensive than comparable accuracy correlation detectors.

Andrews, W.H. Jr.; Roberts, M.J.

1985-01-18

93

Large-scale hydraulic structure of a seismogenic fault at 10 km depth (Gole Larghe Fault Zone, Italian Southern Alps)  

NASA Astrophysics Data System (ADS)

The definition of hydraulic properties of fault zones is a major issue in structural geology, seismology, and in several applications (hydrocarbons, hydrogeology, CO2 sequestration, etc.). The permeability of fault rocks can be measured in laboratory experiments, but its upscaling to large-scale structures is not straightforward. For instance, typical permeability of fine-grained fault rock samples is in the 10-18-10-20 m2 range, but, according to seismological estimates, the large-scale permeability of active fault zones can be as high as 10-10 m2. Solving this issue is difficult because in-situ measurements of large-scale permeability have been carried out just at relatively shallow depths - mainly in oil wells and exceptionally in active tectonic settings (e.g. SAFOD at 3 km), whilst deeper experiments have been performed only in the stable continental crust (e.g. KTB at 9 km). In this study, we apply discrete fracture-network (DFN) modelling techniques developed for shallow aquifers (mainly in nuclear waste storage projects like Yucca Mountain) and in the oil industry, in order to model the hydraulic structure of the Gole Larghe Fault Zone (GLFZ, Italian Southern Alps). This fault, now exposed in world-class glacier-polished outcrops, has been exhumed from ca. 8 km, where it was characterized by a well-documented seismic activity, but also by hydrous fluid flow evidenced by alteration halos and precipitation of hydrothermal minerals in veins and along cataclasites. The GLFZ does not show a classical seal structure that in other fault zones corresponds to a core zone characterized by fine-grained fault rocks. However, permeability is heterogeneous and the permeability tensor is strongly anisotropic due to fracture preferential orientation. We will show with numerical experiments that this hydraulic structure results in a channelized fluid flow (which is consistent with the observed hydrothermal alteration pattern). This results in a counterintuitive situation where a permeable fault zone act as a barrier to fluid flow.

Bistacchi, Andrea; Di Toro, Giulio; Smith, Steve; Mittempergher, Silvia; Garofalo, Paolo

2014-05-01

94

Prospective evaluation of systematic sextant transition zone biopsies in large prostates for cancer detection  

Microsoft Academic Search

Objectives. A prospective evaluation was performed to define the role of systematic transition zone (TZ) biopsies in prostates larger than 50 cc.Methods. From August 1994 to July 1997, 213 consecutive patients referred because of an abnormal digital rectal examination or prostate-specific antigen greater than 4.0 ng\\/mL had a calculated prostate size greater than 50 cc by transrectal ultrasound (TRUS) measurement.

James J Chang; Katsuto Shinohara; Regina M Hovey; Carolyn Montgomery; Joseph C Presti

1998-01-01

95

Weak Compliance Undermines the Success of No-Take Zones in a Large Government-Controlled Marine Protected Area  

PubMed Central

The effectiveness of marine protected areas depends largely on whether people comply with the rules. We quantified temporal changes in benthic composition, reef fish biomass, and fishing effort among marine park zones (including no-take areas) to assess levels of compliance following the 2005 rezoning of the government-controlled Karimunjawa National Park (KNP), Indonesia. Four years after the rezoning awareness of fishing regulations was high amongst local fishers, ranging from 79.5±7.9 (SE) % for spatial restrictions to 97.7±1.2% for bans on the use of poisons. Despite this high awareness and strong compliance with gear restrictions, compliance with spatial restrictions was weak. In the four years following the rezoning reef fish biomass declined across all zones within KNP, with >50% reduction within the no-take Core and Protection Zones. These declines were primarily driven by decreases in the biomass of groups targeted by local fishers; planktivores, herbivores, piscivores, and invertivores. These declines in fish biomass were not driven by changes in habitat quality; coral cover increased in all zones, possibly as a result of a shift in fishing gears from those which can damage reefs (i.e., nets) to those which cause little direct damage (i.e., handlines and spears). Direct observations of fishing activities in 2009 revealed there was limited variation in fishing effort between zones in which fishing was allowed or prohibited. The apparent willingness of the KNP communities to comply with gear restrictions, but not spatial restrictions is difficult to explain and highlights the complexities of the social and economic dynamics that influence the ecological success of marine protected areas. Clearly the increased and high awareness of fishery restrictions following the rezoning is a positive step. The challenge now is to understand and foster the conditions that may facilitate compliance with spatial restrictions within KNP and marine parks worldwide. PMID:23226237

Campbell, Stuart J.; Hoey, Andrew S.; Maynard, Jeffrey; Kartawijaya, Tasrif; Cinner, Joshua; Graham, Nicholas A. J.; Baird, Andrew H.

2012-01-01

96

Weak compliance undermines the success of no-take zones in a large government-controlled marine protected area.  

PubMed

The effectiveness of marine protected areas depends largely on whether people comply with the rules. We quantified temporal changes in benthic composition, reef fish biomass, and fishing effort among marine park zones (including no-take areas) to assess levels of compliance following the 2005 rezoning of the government-controlled Karimunjawa National Park (KNP), Indonesia. Four years after the rezoning awareness of fishing regulations was high amongst local fishers, ranging from 79.5±7.9 (SE) % for spatial restrictions to 97.7±1.2% for bans on the use of poisons. Despite this high awareness and strong compliance with gear restrictions, compliance with spatial restrictions was weak. In the four years following the rezoning reef fish biomass declined across all zones within KNP, with >50% reduction within the no-take Core and Protection Zones. These declines were primarily driven by decreases in the biomass of groups targeted by local fishers; planktivores, herbivores, piscivores, and invertivores. These declines in fish biomass were not driven by changes in habitat quality; coral cover increased in all zones, possibly as a result of a shift in fishing gears from those which can damage reefs (i.e., nets) to those which cause little direct damage (i.e., handlines and spears). Direct observations of fishing activities in 2009 revealed there was limited variation in fishing effort between zones in which fishing was allowed or prohibited. The apparent willingness of the KNP communities to comply with gear restrictions, but not spatial restrictions is difficult to explain and highlights the complexities of the social and economic dynamics that influence the ecological success of marine protected areas. Clearly the increased and high awareness of fishery restrictions following the rezoning is a positive step. The challenge now is to understand and foster the conditions that may facilitate compliance with spatial restrictions within KNP and marine parks worldwide. PMID:23226237

Campbell, Stuart J; Hoey, Andrew S; Maynard, Jeffrey; Kartawijaya, Tasrif; Cinner, Joshua; Graham, Nicholas A J; Baird, Andrew H

2012-01-01

97

Effect of sparger design on hydrodynamics of a gas recirculation anaerobic bioreactor.  

PubMed

The effects of sparger design and gas flow rate on, gas holdup distribution and liquid (slurry) recirculation velocity have been studied in a surrogate anaerobic bioreactor used for treating bovine waste with a conical bottom mixed by gas recirculation. A single orifice sparger (SOS) and a multi-orifice ring sparger (MORS) with the same orifice open area and gas flow rates (hence the same process power input) are compared in this study. The advanced non-invasive techniques of computer automated tomography (CT) and computer automated radioactive particle tracking (CARPT) were employed to determine gas holdup, liquid recirculation velocity, and the poorly mixed zones. Gas flows (Q(g)) ranging of 0.017 x 10(-3) m(3)/s to 0.083 x 10(-3) m(3)/s were used which correspond to draft tube superficial gas velocities ranging from 1.46 x 10(-2) m/s to 7.35 x 10(-2) m/s (based on draft tube diameter). Air was used for the gas, as the molecular weights of air and biogas (consisting mainly of CH(4) and CO(2)) are in the same range (biogas: 28.32-26.08 kg/kmol and air: 28.58 kg/kmol). When compared to the SOS for a given gas flow rate, the MORS gave better gas holdup distribution in the draft tube, enhanced the liquid (slurry) recirculation, and reduced the fraction of the poorly mixed zones. The improved gas holdup distribution in the draft tube was found to have increased the overall liquid velocity. Hence, for the same process power input the MORS system performed better by enhancing the liquid recirculation and reducing the poorly mixed zones. PMID:17514754

Varma, Rajneesh; Al-Dahhan, Muthanna

2007-12-15

98

The influence of large-magnitude earthquakes and fault zone damage on the spatial distribution of slow-moving landslides  

NASA Astrophysics Data System (ADS)

In areas of weak, clay-rich bedrock with low to moderate hillslope gradients, slow-moving landslides (earthflows) can be the primary drivers of hillslope lowering and the dominant source of sediment to river networks. Despite their importance, the controls on the spatial distribution of active earthflows are poorly understood. Here, we seek to isolate the effects of rock strength and the absence of large-magnitude earthquakes on earthflow spatial distribution. We use airborne interferometric synthetic aperture radar (InSAR) to map previously unrecognized slow-moving landslides along a ~145 km by 22 km long swath, centered on the "creeping section" of the San Andreas Fault (SAF), central California, USA. Although our data extend up to 10 km to either side of the fault, approximately 75% of detected landslides occur within 2 km of the SAF trace. We show variations in annual precipitation, topographic metrics (e.g., hillslope gradient and aspect), and lithology are small within the study area, and alone are not enough to explain the observed spatial distribution of earthflows. Instead, we hypothesize that earthflow occurrence proximate to the creeping section of the San Andreas Fault is governed by the width of the fault damage zone and lack of large-magnitude earthquakes. Within the fault damage zone rock is weak and highly fractured leading to reduced bulk rock strength which can increase hillslope susceptibility to failure. Similarly, the lack of large-magnitude earthquakes within the creeping section of the SAF limits the occurrence of co-seismic landslides which can preferentially remove fractured bedrock from hillslopes, thus limiting the availability of material for earthflows to form in. This latter point is supported by the observation that earthflow occurrence in fault damage zones is rare north of the creeping section of the SAF where lithology, climate, and topography are suitable for earthflow development, yet large-magnitude earthquakes and associated co-seismic landslides are common.

Scheingross, J. S.; Minchew, B. M.; Mackey, B. H.; Simons, M.; Lamb, M. P.; Hensley, S.

2012-12-01

99

A Large Eddy Simulation of Turbulent Compressible Convection: Differential Rotation in the Solar Convection Zone  

E-print Network

We present results of two simulations of the convection zone, obtained by solving the full hydrodynamic equations in a section of a spherical shell. The first simulation has cylindrical rotation contours (parallel to the rotation axis) and a strong meridional circulation, which traverses the entire depth. The second simulation has isorotation contours about mid-way between cylinders and cones, and a weak meridional circulation, concentrated in the uppermost part of the shell. We show that the solar differential rotation is directly related to a latitudinal entropy gradient, which pervades into the deep layers of the convection zone. We also offer an explanation of the angular velocity shear found at low latitudes near the top. A non-zero correlation between radial and zonal velocity fluctuations produces a significant Reynolds stress in that region. This constitutes a net transport of angular momentum inwards, which causes a slight modification of the overall structure of the differential rotation near the top. In essence, the {\\it thermodynamics controls the dynamics through the Taylor-Proudman momentum balance}. The Reynolds stresses only become significant in the surface layers, where they generate a weak meridional circulation and an angular velocity `bump'.

Francis J. Robinson; Kwing L. Chan

2000-11-21

100

An explanation of large-scale coal and gas outbursts in underground coal mines: the effect of low-permeability zones on abnormally abundant gas  

NASA Astrophysics Data System (ADS)

Large-scale coal and gas outbursts post a risk of fatal disasters in underground mines. Large-scale outbursts (outburst of coal and rock greater than 500 t) in recent years in China indicate that there is abundant gas in areas of outbursts containing large amounts of potential energy. The adequate sealing properties of the roof and floor of a coal seam are required for local abundant gas around the site of an outburst, but an annular low-permeability zone in a coal seam, which prevents the loss by gas migration through the coal seam itself, is also required. The distribution of coal gas with this annular zone of low permeability is described, and it is proposed that the annular zone of low permeability creates conditions for confining the coal gas. The effect of this low-permeability zone on the gas distribution is analyzed after allowing for simplifications in the model. The results show that the permeability and length of the low-permeability zone have a great impact on the gas distribution. A steep gradient of gas pressure in the low-permeability zone and the high gas pressure in the abundant zone of gas can promote coal mass failure and coal wall deformation, thereby accelerating the coal and gas outburst. The high pressure gas in abundant zone of gas will lead to a large-scale outburst if an outburst occurs.

An, F. H.; Cheng, Y. P.

2013-09-01

101

Laser velocimeter measurements in highly turbulent recirculating flows  

NASA Astrophysics Data System (ADS)

Both a two-dimensional, rearward facing step and a cylindrical, sudden expansion geometry are considered in the present study of subsonic separated flows using a laser Doppler velocimeter (LDV). Study objectives extended to determination of whether a velocity bias error occurs in turbulent flow LDV measurements, and if so, whether it can be eliminated; a comparison of results with numerical predictions based on the kappa-epsilon turbulence model; and the mapping of mean velocity, turbulence intensity, Reynolds stress, etc., including the entire recirculation zone. Velocity bias is noted and overcome by means of suitable data acquisition procedures. Although the kappa-epsilon turbulence model yields a good qualitative view of the flow field, it does not result in an adequate quantitative description.

Stevenson, W. H.; Thompson, H. D.; Craig, R. R.

102

Large-scale high-resolution seismic study in the western end of the Nankai seismogenic zone  

NASA Astrophysics Data System (ADS)

In the Nankai Trough subduction seismogenic zone, M8-class great earthquake area can be divided into three segments; they are source regions of the Nankai, Tonankai and presumed Tokai earthquakes. The Nankai and Tonankai earthquakes had often occurred simultaneously, and caused a great event. Possibility of a megathrust earthquake along the Nankai Trough from Tokai to the Hyuga-nada, east off the Kyushu Island, Japan, is recently pointed out. To understand rupture synchronization and segmentation of the Nankai megathrust earthquake, it is important to know the deep seismic image and activity in the Hyuga-nada, the western end of the Nankai seismogenic zone. To obtain the deep structure related to the rupture synchronization and segmentation in this region, the large-scale high-resolution wide-angle seismic study was conducted in Dec. 2008. In this study, 160 ocean bottom seismographs are deployed with a spacing of 5km along four seismic profiles, 830km in a total length. A tuned airgun system (7800 cu. in.) was shot every 200m along these profiles (Fig. 1). This research is part of ‘Research concerning Interaction Between the Tokai, Tonankai and Nankai Earthquakes’ funded by Ministry of Education, Culture, Sports, Science and Technology, Japan. The subducting plate interface beneath coseismic slip zone of the 1968 event (Mw7.5) is the top of the oceanic crust contacting with the old accreted sediments. The young accretionary sediments (Vp<5km/s) above the subducting Philippine Sea plate reaches a maximum thickness of ~10km, and is widely distributed landward. In the northwestern half of the slip zone of the 1968 event, the young Accretionary sediments become thin abruptly. Figure 1: Location map of seismic survey

Nakanishi, A.; Kodaira, S.; Fujie, G.; Obana, K.; Takizawa, K.; Kashiwase, K.; Kaneda, Y.

2009-12-01

103

Chronology and dynamics of a large silicic magmatic system. Central Taupo volcanic zone, New Zealand  

SciTech Connect

The central Taupo Volcanic Zone in New Zealand is a region of intense Quaternary silicic volcanism accompanying rapid extension of continental crust. At least 34 caldera-forming ignimbrite eruptions have produced a complex sequence of relatively short-lived, nested, and/or overlapping volcanic centers over 1.6 m.y. Silicic volcanism at Taupo is similar to the Yellowstone system in size, longevity, thermal flux, and magma output rate. However, Taupo contrasts with Yellowstone in the exceptionally high frequency, but small size, of caldera-forming eruptions. This contrast reflects the thin, rifted nature of the crust, which precludes the development of long-term magmatic cycles at Taupo. 11 refs., 4 figs., 1 tab.

Houghton, B.F.; Wilson, C.J.N. (Wairakei Research Center, Taupo (New Zealand)); McWilliams, M.O. (Stanford Univ., CA (United States)); Lanphere, M.A.; Pringle, M.S. (Geological Survey, Menlo Park, CA (United States)); Weaver, S.D. (Univ. of Canterbury, Christchurch (New Zealand)); Briggs, R.M. (Univ. of Waikato, Hamilton (New Zealand))

1995-01-01

104

Fish Health Management Considerations in Recirculating Aquaculture Systems -Part 1  

E-print Network

Cir 120 Fish Health Management Considerations in Recirculating Aquaculture Systems - Part 1, Tropical Aquaculture Laboratory, Ruskin FL 33570, Program in Fisheries and Aquatic Sciences, School Cooperating. Nick T. Place , Dean Introduction Recirculating aquaculture systems, also known as water reuse

Watson, Craig A.

105

Seismic constraints on a large dyking event and initiation of a transform fault zone in Western Gulf of Aden  

NASA Astrophysics Data System (ADS)

In November 2010, a large number of events were recorded by the world seismic networks showing important activity occurring along the western part of the Aden Ridge. West of the Shulka El Sheik fracture zone, events in this large seismic swarm (magnitudes above 5) occurred in a complex area, where the change of both the ridge direction and the bathymetry suggest the propagation of the ridge into a continental lithosphere and the influence of the Afar plume. We combine several sets of data from permanent networks and temporary 3C broad stations installed after the beginning of the event along the southern and eastern coasts of Yemen and Djibouti respectively, we located more than 600 earthquakes with magnitudes ranging from 2.5 to 5.6 that occurred during the first months following the first event. The spatial distribution of the main seismicity reveals a very clear N115° -trending alignment, parallel to the mean direction of the en-echelon spreading segments that form the ridge at this longitude. Half of the events, which represent half of the total seismic energy released during the first months, are located in the central third section of the segment. Here several volcanic cones and recent lava flows observed from bathymetric and acoustic reflectivity data during the Tadjouraden cruise (Audin, 1999, Dauteuil et al., 2001) constitute the sea floor. In addition to this main activity, two small groups of events suggest the activiation of landslides into a large fan and the activity in a volcanic area 50 km due east from the main active zone. The time evolution of the seismicity shows several bursts of activity. Some of them are clearly related to sudden activities within the volcanic areas, when others exhibit horizontal migration of the events, with velocity around ˜ 1 km/h. The time-space evolution of the seismicity clearly reveals the intrusion of dykes associated with magma propagation from the crustal magmatic centres into the rift zone. Taking into account that the geodetic moment is one order of magnitude higher than the seismic moment during such events, the seismic activity of this event of the Aden ridge represents a major rifting episode certainly associated with the opening of the segment by dyking estimated to be higher than 10 m. Several computed focal mechanisms are dextral strike-slip in the western part of the dyking area could be related to a nascent transform fault zone.

Ahmed, AbdulHakim; Doubre, Cecile; Leroy, Sylvie; Perrot, Julie; Audin, Laurence; Rolandone, Frederique; Keir, Derek; Al-Ganad, Ismael; Sholan, Jamal; Khanbari, Khaled; Mohamed, Kassim; Vergne, Jerome; Jacques, Eric; Nercessian, Alex

2013-04-01

106

Recirculating sprayer for fiber-filled paints  

NASA Technical Reports Server (NTRS)

Recirculating paint sprayer applies spray of coarse filler in highly volatile solvent. Sprayer was developed for applying insulation material containing epxoy resin, glass fibers, and inert fillers suspended in chlorinated solvents. Sprayer resists abrasive action of fiberglass filler and chemical activity of solvent. Pump and position ensure more uniform pressure at spray gun without backpressure regulator, which tended to clog in old sprayer.

Major, R. K.

1980-01-01

107

Production of cobia in recirculating systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Only limited information exists with respect to rearing juvenile cobia Rachycentron canadum to stocker and marketable sizes using recirculating aquaculture systems (RAS). To investigate this topic, two rearing trials were conducted using commercial scale RAS. In Trial 1, juvenile cobia (29 g) we...

108

Performance of a closed recirculating system with foam separation, nitrification and denitrification units for intensive culture of eel: towards zero emission  

Microsoft Academic Search

The development of a closed recirculating aquaculture system that does not discharge effluents would reduce a large amount of pollutant load on aquatic bodies. In this study, eel were reared in a closed recirculating system, which consisted of a rearing tank, a foam separation unit, a nitrification unit and a denitrification unit. The foam separation unit has an inhalation-type aerator

Yoshihiro Suzuki; Toshiroh Maruyama; Hiroyuki Numata; Hajime Sato; Makio Asakawa

2003-01-01

109

Principles of Water Recirculation and Filtration in Aquaculture 1  

E-print Network

designs for recirculating systems and most will work effectively if they accomplish: 1) aeration, 2FA12 Principles of Water Recirculation and Filtration in Aquaculture 1 Michael McGee and Charles/Institute of Food and Agricultural Sciences/University of Florida/Christine Taylor Waddill, Dean. Recirculating

Watson, Craig A.

110

Toluene removal in membrane bioreactors under recirculating and non-recirculating liquid conditions  

Microsoft Academic Search

A single-, dual- and multiple-tube dense phase silicone rubber membrane bioreactor were investigated for control of toluene-contaminated\\u000a air under circulating and non-recirculating liquid conditions. A mathematical model was developed to describe the system.\\u000a The reactors were seeded with a mixed bacterial consortium isolated from activated sludge and capable of aromatic biodegradation.\\u000a After operating with recirculating liquid nutrient solution, the reactors

Ellen England; Mark W. Fitch; Melanie Mormile; Michael Roberts

2005-01-01

111

Extragalactic large-scale structures in the northern Zone of Avoidance  

E-print Network

We used the Nan\\c{c}ay Radio Telescope (NRT) to measure the 21 cm line emission of near-infrared bright galaxies in the northern Zone of Avoidance (ZoA) without previous redshift determinations. We selected galaxies with extinction-corrected magnitudes $K_s^o \\leq 11\\hbox{$.\\!\\!^{\\rm m}$}25$ from the 2MASS Extended Source Catalog. These data will complement the existing 2MASS Redshift Survey (2MRS; first data release) as well as the ongoing 2MASS Tully-Fisher survey, both of which exclude the inner ZoA ($|b|< 5^{\\circ}$), where the identification of galaxy candidates is the hardest. Of the $\\sim$1000 identified 2MASX galaxy candidates we have so far detected 252 to our 3.0 mJy rms sensitivity limit and the velocity limit of 10500 km/s. The resulting redshift distribution reveals various new structures that were hitherto uncharted. They seem to form part of the larger Perseus-Pisces Supercluster (PPS). The most conspicuous is a ridge at about $\\ell\\approx 160^{\\circ}$,$v \\approx 6500$ km/s. Within this wall...

Ramatsoku, M; Schröder, A C; van Driel, W

2014-01-01

112

The fate of chlorinated volatile organic compounds in aeration basins using recirculated aeration: a pilot-plant evaluation.  

PubMed

The fate of chloroform, which was chosen to represent chlorinated volatile organic compounds sometimes found in publicly owned wastewater treatment works, has been followed in a pilot aeration basin utilizing aeration recirculation. Tests were conducted using real wastewaters spiked with two different concentration levels of chloroform and operated at conditions similar to those of a large-scale aeration basin of the Mill Creek Wastewater Treatment Plant in Cincinnati, Ohio. Aeration recirculation levels of 0, 25, 50, and 75% were used to evaluate the concept that aeration recirculation can be an effective method of reducing the release of these toxic compounds to the atmosphere. Data obtained demonstrated that the concentration of chloroform in the off-gas increased as the recirculation ratio increased, but that the total mass emission rate to the atmosphere decreased due to the decreased off-gas volumetric flow rate. Biodegradation in the pilot plant increased by 183% for the 75% recirculation level compared to 0% recirculation. Mass balance analysis results indicated that 60% of chloroform emissions could be reduced with 75% recirculation ratio with little or no effect of dissolved oxygen concentration. PMID:16865916

Sundrup, J; Jung, K Sook; Keener, T C; Khang, S J; Siddiqui, K

2006-06-01

113

Isotopic variation of fishes in freshwater and estuarine zones of a large subtropical coastal lagoon  

Microsoft Academic Search

We used stable C and N isotope ratios of tissues from 29 fish species from a large subtropical lagoon in southern Brazil to examine spatial variability in isotopic composition and vertical trophic structure across freshwater and estuarine habitats. Nitrogen isotope ratios indicated a smooth gradation in trophic positions among species, with most fishes occupying the secondary and tertiary consumer level.

A. M. Garcia; D. J. Hoeinghaus; J. P. Vieira; K. O. Winemiller

2007-01-01

114

Toward the Rapid Imaging of Large Earthquake Rupture Zones with Teleseismic P-waves  

Microsoft Academic Search

A current bottleneck in the prompt estimation of ground shaking associated with large earthquakes is the determination of the rupture length and geometry, rupture propagation direction, and spatial distribution of seismic moment release. The relative locations of the first-motion hypocenter, the early aftershocks, and the Harvard centroid moment tensor are currently the most rapidly obtained data that are used for

K. Walker; P. Shearer; M. Ishii; P. Earle

2005-01-01

115

Fabrication and evaluation of a weak zone plate for monitoring performance of large orbiting telescopes  

NASA Technical Reports Server (NTRS)

An experimental study of the feasibility of monitoring the optical performance of a large telescope by means of a very faint phase hologram imprinted upon the primary mirror is reported. Tests have been made using an f/5 telescope with a 0.3 m aperture. The results indicate that a usable hologram can be so faint and so restricted in area that it will probably not interfere significantly with normal operation of a 3.0 m telescope at wavelengths longer than 100 nm for stars brighter than magnitude 29.

Erickson, K. E.

1972-01-01

116

Marginal Zone Mucosa Associated Lymphoid Tissue Diffuse Large B Cell Lymphoma  

PubMed Central

Context: Non-Hodgkin's lymphomas (NHL) primarily involving the orbit, is relatively uncommon. Rarely two pathologically different NHL cell types have been found to be coexistent. Case Report: We report a case of orbital lymphoma in a 62-year-old male with rare histopathological findings secondary to transformation of once cell type into another. Tissue diagnosis and molecular studies led to revelation of diffuse large B cell lymphoma evolving from MALT lymphoma. Conclusion: Proliferation of two morphologically and phenotypically different B cells resulting in malignancy has not been found in the orbit so far. They are usually aggressive tumors and require chemo-immunotherapy. PMID:25210678

Aldave, Adrian Pedro Noriega; Jaiswal, Shikha; Davidson, Stephen L

2014-01-01

117

Multipoint measurements of large DC electric fields and shears in the auroral zone  

NASA Astrophysics Data System (ADS)

We present electric field and electron data from the Auroral Turbulence II (AT2) sounding rocket mission. This three pay load rocket flew through several discrete night side auroral arc structures. The pay loads traversed a large, stable arc structure containing, near its poleward edge, at least 400 mV/m of DC electric field, together with broadband waves in the electric field at frequencies from DC up to 100 Hz. Multipoint measurements allow us to determine the size of this region and to observe that it is characterized by two distinct variations: a region of spatial shear approximately 1 km in extent across the arc, immediately followed by a region of temporal change in electric field, nearly 6 km in extent. The observed broadband waves do not show a preference for the spatial shear region over the time varying region.

Pietrowski, D.; Lynch, K. A.; Torbert, R. B.; Marklund, G.; Ivchenko, N.; Ranta, A.; Danielides, M.; Kelley, M. C.

118

Induced seismicity and CO2 leakage through fault zones during large-scale underground injection in a multilayered sedimentary system  

NASA Astrophysics Data System (ADS)

Overpressure caused by the direct injection of CO2 into a deep sedimentary system may produce changes in the state of stress, as well as, have an impact on the sealing capabilities of the targeted system. The importance of geomechanics including the potential for reactivating faults associated with large-scale geologic carbon sequestration operations has recently become more widely recognized. However, not withstanding the potential for triggering notable (felt) seismic events, the potential for buoyancy-driven CO2 to reach potable groundwater and the ground surface is more important from safety and storage-efficiency perspectives. In this context, this work extends previous studies on the geomechanical modeling of fault responses during underground carbon dioxide injection, focusing on both short- and long-term integrity of the sealing caprock, and hence of potential leakage of either brine or CO2 to shallow groundwater aquifers during active injection. The first part of this work aims to study the fault responses during underground carbon dioxide injection, focusing on the short-term (5 years) integrity of the CO2 repository, and hence on the potential leakage of CO2 to shallow groundwater aquifers. Increased pore pressure can alter the stress distribution on a fault/fracture zone, which may produce changes in the permeability related to the elastic and/or plastic strain (or stress) during single (or multiple) shear ruptures. We account for stress/strain-dependent permeability and study the leakage through the fault zone as its permeability changes along with strain and stress variations. We analyze several scenarios related to the injected amount of CO2 (and hence related to potential overpressure) involving both involving minor and major faults, and analyze the profile risks of leakage for different stress/strain permeability coupling functions, as well as increasing the complexity of the system in terms of hydromechanical heterogeneities. We conclude that whereas it is very difficult to predict how much fault permeability could change upon reactivation, this process can have a significant impact on the leakage rate. Moreover, our analysis shows that induced seismicity associated with fault reactivation may not necessarily open up a new flow path for leakage. Results show a poor correlation between magnitude and amount of fluid leakage, meaning that a single event is generally not enough to substantially change the permeability along the entire fault length. In the second part of this work we address the three following questions: (1) is there a link between fault-zone architecture and fault reactivation by CO2 injection? (2) what is the impact of the fault architecture on the induced seismicity and on CO2 leakage? and (3) how do caprock and reservoir thickness impact the results? We analyze the hydromechanical behavior of a fault zone represented either by: (i) a continuous damage zone, or by a discontinuous damage zone caused by (ii) variations in lithology of the different layers (shale caprock and limestone aquifers), and also by (iii) the initial properties of the sedimentary layers within the injection reservoir itself. We use the model to estimate the moment magnitude associated with a sudden fault slip event as well as the amount of CO2 migrating from the injection aquifer and upwards across the primary caprock located just above the injection aquifer after a long-term post-injection period. We recognize that such migration out of the injection aquifer may not formally constitute CO2 leakage up into potable shallow aquifers, if for example there is leak-off into intervening aquifers or multiple overlying low permeability formations that prevent further upward migration of the CO2. Finally, results show that a thin caprock or aquifer allows smaller events, but a much higher percentage of leakage in the upper aquifer. The elevate amount of leakage reduces drastically by assuming a multi-caprock, multi-aquifer system.

Pio Rinaldi, Antonio; Rutqvist, Jonny; Jeanne, Pierre; Cappa, Frederic; Guglielmi, Yves

2014-05-01

119

Global Omori law decay of triggered earthquakes: large aftershocks outside the classical aftershock zone  

USGS Publications Warehouse

Triggered earthquakes can be large, damaging, and lethal as evidenced by the 1999 shocks in Turkey and the 2001 earthquakes in El Salvador. In this study, earthquakes with Ms ? 7.0 from the Harvard centroid moment tensor (CMT) catalog are modeled as dislocations to calculate shear stress changes on subsequent earthquake rupture planes near enough to be affected. About 61% of earthquakes that occurred near (defined as having shear stress change ???? ? 0.01 MPa) the Ms ? 7.0 shocks are associated with calculated shear stress increases, while ?39% are associated with shear stress decreases. If earthquakes associated with calculated shear stress increases are interpreted as triggered, then such events make up at least 8% of the CMT catalog. Globally, these triggered earthquakes obey an Omori law rate decay that lasts between ?7–11 years after the main shock. Earthquakes associated with calculated shear stress increases occur at higher rates than background up to 240 km away from the main shock centroid. Omori's law is one of the few time-predictable patterns evident in the global occurrence of earthquakes. If large triggered earthquakes habitually obey Omori's law, then their hazard can be more readily assessed. The characteristic rate change with time and spatial distribution can be used to rapidly assess the likelihood of triggered earthquakes following events of Ms ? 7.0. I show an example application to the M = 7.7 13 January 2001 El Salvador earthquake where use of global statistics appears to provide a better rapid hazard estimate than Coulomb stress change calculations.

Parsons, Tom

2002-01-01

120

Global Omori law decay of triggered earthquakes: Large aftershocks outside the classical aftershock zone  

USGS Publications Warehouse

Triggered earthquakes can be large, damaging, and lethal as evidenced by the 1999 shocks in Turkey and the 2001 earthquakes in El Salvador. In this study, earthquakes with Ms ??? 7.0 from the Harvard centroid moment tensor (CMT) catalog are modeled as dislocations to calculate shear stress changes on subsequent earthquake rupture planes near enough to be affected. About 61% of earthquakes that occured near (defined as having shear stress change ???????? ??? 0.01 MPa) the Ms ??? 7.0 shocks are associated with calculated shear stress increases, while ???39% are associated with shear stress decreases. If earthquakes associated with calculated shear stress increases are interpreted as triggered, then such events make up at least 8% of the CMT catalog. Globally, these triggered earthquakes obey an Omori law rate decay that lasts between ???7-11 years after the main shock. Earthquakes associated with calculated shear stress increases occur at higher rates than background up to 240 km away from the main shock centroid. Omori's law is one of the few time-predictable patterns evident in the global occurrence of earthquakes. If large triggered earthquakes habitually obey Omori's law, then their hazard can be more readily assessed. The characteristics rate change with time and spatial distribution can be used to rapidly assess the likelihood of triggered earthquakes following events of Ms ??? 7.0. I show an example application to the M = 7.7 13 January 2001 El Salvador earthquake where use of global statistics appears to provide a better rapid hazard estimate than Coulomb stress change calculations.

Parsons, T.

2002-01-01

121

Preoperational test report, recirculation condenser cooling systems  

SciTech Connect

This represents a preoperational test report for Recirculation Condenser Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The four system provide condenser cooling water for vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102. Each system consists of a valved piping loop, a pair of redundant recirculation pumps, a closed-loop evaporative cooling tower, and supporting instrumentation; equipment is located outside the farm on concrete slabs. Piping is routed to the each ventilation condenser inside the farm via below-grade concrete trenches. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

Clifton, F.T.

1997-11-04

122

Multi-stage exhaust gas recirculation system  

SciTech Connect

An automotive type exhaust gas recirculation (EGR) system has two modes of operation, a first one that regulates EGR flow at a constant percentage rate as a function of throttle valve position independently of exhaust gas backpressure changes, and a second one that provides a variable percentage rate of flow of EGR gases in response to changes in exhaust gas backpressures, both modes utilizing carburetor ported vacuum modified by an air bleed device as the EGR valve opening force.

Ahrns, D.C.; Rachedi, S.H.

1983-08-16

123

High Power Picosecond Laser Pulse Recirculation  

SciTech Connect

We demonstrate a nonlinear crystal-based short pulse recirculation cavity for trapping the second harmonic of an incident high power laser pulse. This scheme aims to increase the efficiency and flux of Compton-scattering based light sources. We demonstrate up to 36x average power enhancement of frequency doubled sub-millijoule picosecond pulses, and 17x average power enhancement of 177 mJ, 10 ps, 10 Hz pulses.

Shverdin, M Y; Jovanovic, I; Semenov, V A; Betts, S M; Brown, C; Gibson, D J; Shuttlesworth, R M; Hartemann, F V; Siders, C W; Barty, C P

2010-04-12

124

An explanation of large-scale coal and gas outbursts in underground coal mines: the effect of low-permeability zones on abnormally abundant gas  

NASA Astrophysics Data System (ADS)

Large-scale coal and gas outbursts pose a risk of fatal disasters in underground mines. Large-scale outbursts (outburst of coal and rock greater than 500 t) in recent years in China indicate that there is abundant gas in areas of outbursts containing large amounts of potential energy. The adequate sealing properties of the roof and floor of a coal seam are required for local abundant gas around the site of an outburst, but an annular low-permeability zone in a coal seam, which prevents the loss by gas migration through the coal seam itself, is also required. The distribution of coal gas with this annular zone of low permeability is described, and it is proposed that the annular zone of low permeability creates conditions for confining the coal gas. The effect of this low-permeability zone on the gas distribution is analyzed after allowing for simplifications in the model. The results show that the permeability and length of the low-permeability zone have a great impact on the gas distribution, and the permeability is required to be several orders of magnitude less than that of normal coal and enough length is also in demand. A steep gradient of gas pressure in the low-permeability zone and the high-pressure gas in the abundant zone of gas can promote coal mass failure and coal wall deformation, thereby accelerating the coal and gas outburst. The high-pressure gas in abundant zone of gas will lead to a large-scale outburst if an outburst occurs.

An, F. H.; Cheng, Y. P.

2014-08-01

125

Regional extent of the large coseismic slip zone of the 2011 Mw 9.0 Tohoku-Oki earthquake delineated by on-fault aftershocks  

NASA Astrophysics Data System (ADS)

Since the 2011 Tohoku-Oki earthquake, many fault source models have been constructed using a variety of data, such as teleseismic, strong ground motion, geodetic, and tsunami recordings. However, questions remain as to how far the associated large-slip zone extended along the plate interface during the rupture. Here we delineate the outer edge of this large-slip zone in detail, based on the sharp density contrast observed for interplate, repeating, and down-dip compressional earthquakes induced by the Tohoku-Oki mainshock. The seismicity rate of interplate earthquakes changed significantly after the mainshock, probably as a result of stress perturbations by the large-slip, and here we use this information as qualitative constraints in constructing our model. The model that we present for the large-slip zone of the Tohoku-Oki earthquake incorporates the main features of previously proposed fault source models, and also the observed fine-scale heterogeneities of fault slip associated with this event. It is important to highlight that the outer edge of this large-slip zone shows a remarkably complex shape. In particular, it is narrow and elongate southward along the ~35 km iso-depth contour of the plate boundary offshore of Fukushima and Ibaraki. This southward elongate slip zone corresponds to down-dip regions that appear to have produced higher relative levels of short-period seismic radiation.

Kato, Aitaro; Igarashi, Toshihiro

2012-08-01

126

Estimation of recurrence interval of large earthquakes on the central Longmen Shan fault zone based on seismic moment accumulation/release model.  

PubMed

Recurrence interval of large earthquake on an active fault zone is an important parameter in assessing seismic hazard. The 2008 Wenchuan earthquake (Mw 7.9) occurred on the central Longmen Shan fault zone and ruptured the Yingxiu-Beichuan fault (YBF) and the Guanxian-Jiangyou fault (GJF). However, there is a considerable discrepancy among recurrence intervals of large earthquake in preseismic and postseismic estimates based on slip rate and paleoseismologic results. Post-seismic trenches showed that the central Longmen Shan fault zone probably undertakes an event similar to the 2008 quake, suggesting a characteristic earthquake model. In this paper, we use the published seismogenic model of the 2008 earthquake based on Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data and construct a characteristic seismic moment accumulation/release model to estimate recurrence interval of large earthquakes on the central Longmen Shan fault zone. Our results show that the seismogenic zone accommodates a moment rate of (2.7?±?0.3)?×?10¹??N?m/yr, and a recurrence interval of 3900?±?400?yrs is necessary for accumulation of strain energy equivalent to the 2008 earthquake. This study provides a preferred interval estimation of large earthquakes for seismic hazard analysis in the Longmen Shan region. PMID:23878524

Ren, Junjie; Zhang, Shimin

2013-01-01

127

Estimation of Recurrence Interval of Large Earthquakes on the Central Longmen Shan Fault Zone Based on Seismic Moment Accumulation/Release Model  

PubMed Central

Recurrence interval of large earthquake on an active fault zone is an important parameter in assessing seismic hazard. The 2008 Wenchuan earthquake (Mw 7.9) occurred on the central Longmen Shan fault zone and ruptured the Yingxiu-Beichuan fault (YBF) and the Guanxian-Jiangyou fault (GJF). However, there is a considerable discrepancy among recurrence intervals of large earthquake in preseismic and postseismic estimates based on slip rate and paleoseismologic results. Post-seismic trenches showed that the central Longmen Shan fault zone probably undertakes an event similar to the 2008 quake, suggesting a characteristic earthquake model. In this paper, we use the published seismogenic model of the 2008 earthquake based on Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data and construct a characteristic seismic moment accumulation/release model to estimate recurrence interval of large earthquakes on the central Longmen Shan fault zone. Our results show that the seismogenic zone accommodates a moment rate of (2.7?±?0.3)?×?1017?N?m/yr, and a recurrence interval of 3900?±?400?yrs is necessary for accumulation of strain energy equivalent to the 2008 earthquake. This study provides a preferred interval estimation of large earthquakes for seismic hazard analysis in the Longmen Shan region. PMID:23878524

Zhang, Shimin

2013-01-01

128

Exhaust gas recirculation system for an internal combustion engine  

SciTech Connect

An exhaust gas recirculation system for an internal combustion engine comprises an exhaust driven turbocharger having a low pressure turbine outlet in fluid communication with an exhaust gas conduit. The turbocharger also includes a low pressure compressor intake and a high pressure compressor outlet in communication with an intake air conduit. An exhaust gas recirculation conduit fluidly communicates with the exhaust gas conduit to divert a portion of exhaust gas to a low pressure exhaust gas recirculation branch extending between the exhaust gas recirculation conduit and an engine intake system for delivery of exhaust gas thereto. A high pressure exhaust gas recirculation branch extends between the exhaust gas recirculation conduit and the compressor intake and delivers exhaust gas to the compressor for mixing with a compressed intake charge for delivery to the intake system.

Wu, Ko-Jen

2013-05-21

129

Exhaust gas recirculation in a homogeneous charge compression ignition engine  

DOEpatents

A homogeneous charge compression ignition engine operates by injecting liquid fuel directly in a combustion chamber, and mixing the fuel with recirculated exhaust and fresh air through an auto ignition condition of the fuel. The engine includes at least one turbocharger for extracting energy from the engine exhaust and using that energy to boost intake pressure of recirculated exhaust gas and fresh air. Elevated proportions of exhaust gas recirculated to the engine are attained by throttling the fresh air inlet supply. These elevated exhaust gas recirculation rates allow the HCCI engine to be operated at higher speeds and loads rendering the HCCI engine a more viable alternative to a conventional diesel engine.

Duffy, Kevin P. (Metamora, IL); Kieser, Andrew J. (Morton, IL); Rodman, Anthony (Chillicothe, IL); Liechty, Michael P. (Chillicothe, IL); Hergart, Carl-Anders (Peoria, IL); Hardy, William L. (Peoria, IL)

2008-05-27

130

Passive recirculation in the National Launch System's fuel feedlines  

NASA Technical Reports Server (NTRS)

This report contains the passive recirculation tests on the fuel feedline of the National Launch System (NLS). The majority of testing was performed in February 1992, at the National Institute of Standards and Technology in Boulder, CO. The primary objective was to characterize passive recirculation in the NLS fuel feedline. The objective was met by observing the passive recirculation in a one-fifth scale model of the feedline with clear glass sections. The testing was recorded on video tape and with photographs. A description of the testing apparatus and support equipment is included. The experiment indicates that passive recirculation was occurring; higher angles from the horizontal transfer more heat.

Wilson, W. R.; Holt, K. A.

1993-01-01

131

Recirculating Linear Accelerators for Future Muon Facilities  

SciTech Connect

Neutrino Factories (NF) and Muon Colliders (MC) require rapid acceleration of short-lived muons to multi-GeV and TeV energies. A Recirculating Linear Accelerator (RLA) that uses superconducting RF structures can provide exceptionally fast and economical acceleration to the extent that the focusing range of the RLA quadrupoles allows each muon to pass several times through each high-gradient cavity. A new concept of rapidly changing the strength of the RLA focusing quadrupoles as the muons gain energy is being developed to increase the number of passes that each muon will make in the RF cavities, leading to greater cost effectiveness.

S.A. Bogacz, K.B.Beard, R.P. Johnson

2010-05-01

132

Preoperational test report, recirculation ventilation systems  

SciTech Connect

This represents a preoperational test report for Recirculation Ventilation Systems, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system provides vapor space cooling of tanks AY1O1, AY102, AZ1O1, AZ102 and supports the ability to exhaust air from each tank. Each system consists of a valved piping loop, a fan, condenser, and moisture separator; equipment is located inside each respective tank farm in its own hardened building. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.

Clifton, F.T.

1997-11-11

133

In-tank recirculating arsenic treatment system  

DOEpatents

A low-cost, water treatment system and method for reducing arsenic contamination in small community water storage tanks. Arsenic is removed by using a submersible pump, sitting at the bottom of the tank, which continuously recirculates (at a low flow rate) arsenic-contaminated water through an attached and enclosed filter bed containing arsenic-sorbing media. The pump and treatment column can be either placed inside the tank (In-Tank) by manually-lowering through an access hole, or attached to the outside of the tank (Out-of-Tank), for easy replacement of the sorption media.

Brady, Patrick V. (Albuquerque, NM); Dwyer, Brian P. (Albuquerque, NM); Krumhansl, James L. (Albuquerque, NM); Chwirka, Joseph D. (Tijeras, NM)

2009-04-07

134

Large-eddy simulation of swirling reacting flows  

NASA Astrophysics Data System (ADS)

Turbulent, swirling flows are encountered frequently in various chemical engineering processes. In combustion processes swirling flames are of interest due to the fact that provide enhanced mixing and reduce the pollutants formation. The challenge in understanding turbulent swirling flows stems mainly from the complexity of the flow field which is subject to vortex breakdown, recirculation and flow instability. In general the flow instabilities arise at high swirl numbers and can be used to control the performance of combustors. In the present study a large-eddy simulation (LES) approach with Smagorinsky eddy viscosity subgrid scale model is used to predict the swirling flame. The conserved scalar mixture fraction-based thermo-chemical variables are described using the steady laminar flamelet model. The present study shows that LES together with a laminar flamelet model provides a good prediction of the structure of turbulent swirling flames. Also LES captured very well the complex flame structures involving vortex breakdown which leads to swirl-induced recirculation zones, flow instability, and the occurrence of localized extinction. Also, the present study shows that the formation of an elongated recirculation (bluff-body stabilized) zone is strongly dependent on the swirl number and the ratio of momentum in the swirling annulus and central fuel jet.

Ilie, Marcel

2009-03-01

135

Tide-driven dynamics of ephemeral fluid mud deposits in troughs of large, subaqueous dunes in an estuarine turbidity zone  

NASA Astrophysics Data System (ADS)

Near-bed density stratification due to suspended, fine-grained cohesive sediments and the formation of fluid mud layers are frequently observed in tide-dominated estuaries. Significant progress was made during the past years in terms of the description and parameterization of fluid mud related sediment transport processes. However, only few studies present in-situ measurements of the spatiotemporal distribution of estuarine fluid mud deposits. Due to the tidal excursion, settling of cohesive sediments during slack water and the formation of fluid mud is also expected to occur in tidal channels, located upstream and downstream of the tidally averaged location of the estuarine turbidity zone and characterized by coarser bed sediments and mobile bedforms. In the Weser estuary (Southern North Sea, Germany), high resolution sediment echo sounder and acoustic Doppler current profiler measurements revealed ephemeral fluid mud deposits in troughs of large, ebb-directed, subaqueous dunes during flood slack water. The spatial distribution of fluid mud deposits correlated with the location of the turbidity zone, shifted upstream during the flood phase. Density stratification, induced by the accumulation of suspended sediments in dune troughs, was initially observed 1.2h before flood slack water. Sediment concentrations in the fluid mud layer ranged from 25g/l below the lutocline to a maximum concentration of 70g/l at the river bed, validated by Rumohr-type gravity coring. During the early ebb phase internal waves were observed as current velocities exceeded 0.2m/s, measured 1m above the lutocline. Fluid mud remained in dune troughs for approximately 2h after slack water and was not entrained until current velocities exceeded 0.45m/s. According to the local gradient Richardson number, calculated on the basis of average current velocities, the corresponding density gradient was stable with respect to shear instabilities during entrainment. Entrainment of fluid mud is explained to be induced by the development of the dune specific turbulent flow field downstream of the dune crest and advection of strong turbulent stresses in direction of the lutocline. Indicating high suspended sediment concentrations near the bed, lutoclines were observed for 3.5h during the tidal cycle around slack water. The associated fluid mud deposits are considered to affect the grain size distribution in dune troughs in terms of matrix infilling and the formation of mud drapes, embedded in cross-strata as found to be preserved in the sedimentary record.

Becker, M.; Schrottke, K.; Bartholomä, A.; Ernstsen, V. B.; Winter, C.; Hebbeln, D.

2012-04-01

136

Modeling non-volcanic tremor, slow slip events and large earthquakes in the Guerrero1 subduction zone (Mexico) with space-variable frictional weakening and creep2  

E-print Network

1 Modeling non-volcanic tremor, slow slip events and large earthquakes in the Guerrero1 subduction and Michel Campillo2 4 5 1 Department of Earth Sciences, University of Southern California, Los Angeles, CA: Modeling NVT, SSE and Earthquakes16 17 Keywords: Earthquake dynamics; Rheology and friction of fault zones

Ben-Zion, Yehuda

137

Geothermal evidence for fluid flow through the gas hydrate stability field off Central Chile-transient flow related to large subduction zone earthquakes?  

Microsoft Academic Search

Fluids are suspected to play a major role in the nucleation and rupture propagation of earthquakes. In Chile, seismological data were previously interpreted to indicate that fluids captured in the fault zone are released periodically during large underthrust earthquakes, leading to post-seismic fluid flow. In central Chile, heat flow derived from the presence of a bottom simulating reflector (BSR) show

Ingo Grevemeyer; Norbert Kaul; Juan L. Diaz-Naveas

2006-01-01

138

Large Earthquake Hazard of the San Jacinto Fault Zone, CA, from Long Record of Simulated Seismicity Assimilating the Available Instrumental and Paleoseismic Data  

E-print Network

with magnitudes up to m = 5.4 (HAUKSSON et al. 2012). The largest recorded earthquake in the study area is the M6Large Earthquake Hazard of the San Jacinto Fault Zone, CA, from Long Record of Simulated Seismicity record, consistent with paleo- earthquakes documented at sites along the SJFZ for the last 1,400 years

Ben-Zion, Yehuda

139

The impact of predation by burbot ( Lota lota L.) on the macroinvertebrate community in the littoral zone of a large lake  

Microsoft Academic Search

We studied the effects of predation by juvenile burbot (Lota lota) on the macroinvertebrate community in mesocosm experiments in the stony littoral zone of Lake Constance, a large prealpine lake in Central Europe. Although the growth data of the burbot suggest that the benthivorous fish exerts strong predation pressure on the invertebrate community, the predicted level of consumption is only

Daniel Baumgärtner; Karl-Otto Rothhaupt

2005-01-01

140

Variations of mesoscale and large-scale sea ice morphology in the 1984 Marginal Ice Zone Experiment as observed by microwave remote sensing  

Microsoft Academic Search

During the summer 1984 Marginal Ice Zone Experiment in the Fram Strait and Greenland Sea (MIZEX '84), passive and active microwave sensors on five aircraft and the Nimbus 7 scanning multichannel microwave radiometer (SMMR) acquired synoptic sequential observations which when combined give a comprehensive sequential description of the mesoscale and large-scale ice morphology variations during the period June 9 through

W. J. Cambell; P. Gloersen; E. G. Josberger; O. M. Johannessen; P. S. Guest; N. Mognard; R. Shuchman; B. A. Burns; N. Lannelongue; K. L. Davidson

1987-01-01

141

High speed exhaust gas recirculation valve  

DOEpatents

In order to minimize pollutants such as Nox, internal combustion engines typically include an exhaust gas recirculation (EGR) valve that can be used to redirect a portion of exhaust gases to an intake conduit, such as an intake manifold, so that the redirected exhaust gases will be recycled. It is desirable to have an EGR valve with fast-acting capabilities, and it is also desirable to have the EGR valve take up as little space as possible. An exhaust gas recirculation valve is provided that includes an exhaust passage tube, a valve element pivotally mounted within the exhaust passage tube, a linear actuator; and a gear train. The gear train includes a rack gear operatively connected to the linear actuator, and at least one rotatable gear meshing with the rack gear and operatively connected to the valve element to cause rotation of the valve element upon actuation of the linear actuator. The apparatus provides a highly compact package having a high-speed valve actuation capability.

Fensom, Rod (Peterborough, GB); Kidder, David J. (Peterborough, GB)

2005-01-18

142

Bacterial contamination of recirculating brine used in the commercial production of moisture-enhanced pork.  

PubMed

In a commercial process for the production of moisture-enhanced pork, boneless pork loins were conveyed through a recirculating injection apparatus, and brine (sodium phosphate, sodium chloride, and lemon juice solids) was pumped into the meat through banks of needles inserted automatically into the upper surfaces of cuts. Brine samples were collected at intervals during the production process and analyzed to determine the total plate count and the numbers of lactic acid bacteria, pseudomonads, Brochothrix thermosphacta, and Enterobacteriaceae. Listeria monocytogenes numbers in the brine were determined using a PCR with primers for the hemolysin gene in combination with a most probable numbers determination. Maximum numbers of bacteria (log CFU/ml) recovered from the brine after 2.5 h of recirculation were as follows: total plate count, 4.50; lactic acid bacteria, 2.99; pseudomonads, 3.95; B. thermosphacta, 2.79; and enterics, 3.01. There was an increase in the number of L. monocytogenes in the recirculating brine with time, reaching a maximum of 2.34 log CFU/100 ml after 2.5 h of moisture-enhanced pork production. Thus, recirculating brines can harbor large populations of spoilage bacteria and L. monocytogenes and are an important source of contamination for moisture-enhanced pork. PMID:14717372

Greer, G Gordon; Nattress, Frances; Dilts, Bryan; Baker, Lynda

2004-01-01

143

Incremental growth of a large volume, chemically zoned magma body: a study of the tephra sequence beneath the Rainier Mesa ash flow sheet of the Timber Mountain Tuff  

Microsoft Academic Search

The Rainier Mesa ash-flow is a large (1200 km3), 11.6 My old, chemically zoned unit that ranges in composition from 55 to 76% SiO2 --- one of the largest chemical ranges ever observed in a large volume ash-flow sheet. Two chemical trends occur in this sheet, a low silica (55 66% SiO2) and a high silica (>66% SiO2) trend. Ninety

Kristin T. Huysken; Thomas A. Vogel; Paul W. Layer

1994-01-01

144

Incremental growth of a large volume, chemically zoned magma body: a study of the tephra sequence beneath the Rainier Mesa ash flow sheet of the Timber Mountain Tuff  

Microsoft Academic Search

The Rainier Mesa ash-flow is a large (1200 km3), 11.6 My old, chemically zoned unit that ranges in composition from 55 to 76% SiO2 — one of the largest chemical ranges ever observed in a large volume ash-flow sheet. Two chemical trends occur in this sheet, a low silica (55–66% SiO2) and a high silica (>66% SiO2) trend. Ninety per

Kristin T. Huysken; Thomas A. Vogel; Paul W. Layer

1994-01-01

145

Incremental growth of a large volume, chemically zoned magma body: a study of the tephra sequence beneath the Rainier Mesa ash flow sheet of the Timber Mountain Tuff  

Microsoft Academic Search

The Rainier Mesa ash-flow is a large (1200 km3), 11.6 My old, chemically zoned unit that ranges in composition from 55 to 76% SiO2 - one of the largest chemical ranges ever observed in a large volume ash-flow sheet. Two chemical trends occur in this sheet, a low silica (55-66% SiO2) and a high silica (>66% SiO2) trend. Ninety per

Kristin T. Huysken; Thomas A. Vogel; Paul W. Layer

1994-01-01

146

Regional extent of the large coseismic slip zone of the 2011 Mw 9.0 Tohoku-Oki Earthquake delineated by on-fault aftershocks  

NASA Astrophysics Data System (ADS)

In order to image the rupture process of the 2011 Tohoku-Oki earthquake, many fault source models have recently been developed following this giant earthquake by inverting for slip on the fault plane, based on a variety of collected data, strong ground motion, geodetic, and tsunami recordings. Most of these studies suggest that the area of largest coseismic slip (~30-80 m) was located near the mainshock hypocenter, extending eastward to a location near the Japan Trench axis. However, the estimated outer edges of the large-slip zone are substantially different between these models, due to the currently limited spatial resolution of slip along the fault. Consequently, there are insufficient constraints as to how far the large-slip zone extended along the plate interface during the mainshock rupture. Here we delineate the outer edge of this large-slip zone in detail, by applying a spatial correlation between on-fault aftershocks and slip to the Tohoku aftershock sequence. We focus on the sharp density contrast observed for interplate, repeating, and down-dip compressional earthquakes induced by the Tohoku-Oki mainshock. The seismicity rate of interplate earthquakes changed significantly after the mainshock, probably as a result of stress perturbations by the large-slip, and here we use this information as qualitative constraints in constructing our model. The model that we present for the large-slip zone incorporates the main features of previously proposed fault source models, and also the observed fine-scale heterogeneities of fault slip associated with this event. It is important to highlight that the outer edge of this large-slip zone shows a remarkably complex shape. In particular, it is narrow and elongate southward along the ~35 km iso-depth contour of the plate boundary offshore of Fukushima and Ibaraki. This southward elongate slip zone corresponds to down-dip regions that appear to have produced higher relative levels of short-period seismic radiation. We explore whether the coseismic geodetic data could be fit with a fault source model in which slip is confined to the large-slip zone delineated by on-fault aftershocks, described above. We impose zero slip outside the large-slip zone assuming a nonplanar fault plane along the plate boundary. The slip model has a moment magnitude of 9.0. In addition to the largest coseismic slip area off Miyagi, an isolated high slip region is imaged off Ibaraki. Repeating earthquakes that occur along the plate boundary are likely an indication of post-seismic transient afterslip, which could be described in terms of a brittle creep rheology. Because most of the repeating earthquakes coincided closely with the dense concentrations of on-fault aftershocks, it is likely that the stress increase generated by abrupt slip termination of the Tohoku-Oki mainshock triggered the post-seismic transient afterslip event on the outside of the large-slip zone. Beneath the Kanto district, the distribution of interplate earthquakes including repeating earthquakes dissipates across the northern reaches of a contact zone where two oceanic plates are subducting. Because the post-seismic slip has occurred beneath the Kanto, it is important to monitor the seismicity using a dense seismic array operated by the Special project for reducing vulnerability for urban mega earthquake disasters.

Kato, A.; Igarashi, T.; Fukuda, J.

2012-12-01

147

Full-scale demonstration of in situ cometabolic biodegradation of trichloroethylene in groundwater 1. Dynamics of a recirculating well system  

NASA Astrophysics Data System (ADS)

Recirculating well systems provide an engine for the in situ treatment of subsurface contaminants. Although numerous recirculating wells have been installed in the field, for such systems, there is a paucity of comprehensive monitoring data and models constrained to data appearing in the research literature. Here we present an extensive data set combined with detailed inverse and simulation analyses for a two-well groundwater recirculation system used for in situ bioremediation at Edwards Air Force Base in southern California. The ``conveyor belt'' flow system, which was established for in situ treatment of trichloroethylene (TCE) in two bioactive zones, was created by pumping water upward in one well and downward in another well, each well being screened in both the upper and lower aquifers. A bromide tracer test was conducted and extensively monitored for 60 days. Combined inverse analysis was conducted on hydraulic heads from 38 monitoring wells, 32 bromide concentration histories, and a constraint on the degree of recirculation that was based on TCE concentration data. Four different formulations involving alternative weighting schemes used in a nonlinear weighted least squares simulation-regression analysis were explored. The best formulation provided parameter estimates with tight bounds on estimated covariances, suggesting that the model provides a reasonable description of the hydrogeologic system. Our investigation indicates the geometry of the recirculation zone and the degree of recirculation under two different sets of operating conditions. Surprisingly, our analysis suggests that the effects of aquifer heterogeneity are not significant at this site under the conditions of forced recirculation. Furthermore, anomalous flow through an open monitoring well created significant vertical short-circuiting between the generally insulated aquifers. Flow through this small open conduit was equivalent to as much as 33% of the flow through the pumping wells. Using the model as a guide, we treated the aquifer system and bioactive zones as an equivalent mixed reactor to develop simple expressions relating effluent concentrations to influent concentrations. We demonstrate how these expressions are useful in predicting the removal of TCE that had undergone in situ bioremediation in the recirculatory treatment well system. The finite element model developed in this work serves as the foundation for a reactive transport simulator that we developed to analyze bioremediation which occurred during a 444 day experiment [Gandhi et al., 2002].

Gandhi, Rahul K.; Hopkins, Gary D.; Goltz, Mark N.; Gorelick, Steven M.; McCarty, Perry L.

2002-04-01

148

Energy savings from air recirculation in peanut curing  

SciTech Connect

A thin-layer peanut drying simulation model was adapted to incorporate air recirculation. Laboratory crop dryers were designed and constructed to conduct experiments to verify the model. Five batches of peanuts were dried using different recirculation strategies. The model successfully predicted the results.

Cook, D.F.; Cundiff, J.S.; Vaughan, D.H.

1982-12-01

149

Energy conservation by partial recirculation of peanut drying air  

SciTech Connect

Conventional, recirculating, and intermittent type peanut dryers were compared in a three-year study. Comparisons indicate that partial recirculation of peanut drying air may reduce energy consumption per unit of water removed by approximately 25% while also reducing required drying time and maintaining high quality.

Young, J.H.

1983-06-01

150

Recirculating Air Filtration Significantly Reduces Exposure to Airborne Nanoparticles  

PubMed Central

Background Airborne nanoparticles from vehicle emissions have been associated with adverse effects in people with pulmonary and cardiovascular disease, and toxicologic studies have shown that nanoparticles can be more hazardous than their larger-scale counterparts. Recirculating air filtration in automobiles and houses may provide a low-cost solution to reducing exposures in many cases, thus reducing possible health risks. Objectives We investigated the effectiveness of recirculating air filtration on reducing exposure to incidental and intentionally produced airborne nanoparticles under two scenarios while driving in traffic, and while generating nanomaterials using gas-phase synthesis. Methods We tested the recirculating air filtration in two commercial vehicles when driving in traffic, as well as in a nonventilation room with a nanoparticle generator, simulating a nanomaterial production facility. We also measured the time-resolved aerosol size distribution during the in-car recirculation to investigate how recirculating air filtration affects particles of different sizes. We developed a recirculation model to describe the aerosol concentration change during recirculation. Results The use of inexpensive, low-efficiency filters in recirculation systems is shown to reduce nanoparticle concentrations to below levels found in a typical office within 3 min while driving through heavy traffic, and within 20 min in a simulated nanomaterial production facility. Conclusions Development and application of this technology could lead to significant reductions in airborne nanoparticle exposure, reducing possible risks to health and providing solutions for generating nanomaterials safely. PMID:18629306

Pui, David Y.H.; Qi, Chaolong; Stanley, Nick; Oberdörster, Günter; Maynard, Andrew

2008-01-01

151

Future of recirculating systems in the US aquaculture industry  

Microsoft Academic Search

Recirculating systems consist of a culture unit, a recirculating pump, and a treatment block which facilitate extended re-use of water in the rearing of aquatic animals. As water re-use is extended from a few hours to months or even years, the complexity of the treatment block increases. Classified as either `open` with greater than 10 percent water replacement per day

Malone

1994-01-01

152

A nitrogen budget for a closed, recirculating mariculture system  

Microsoft Academic Search

Nitrogen dynamics were evaluated in a closed, recirculating mariculture system by constructing a mass and isotopic balance of all major nitrogen pools. The experimental system consisted of 12?238-l, closed, independent, recirculating systems, each containing red drum (Sciaenopsocellatus), a biological filter, water pump and subsurface aeration. The standard system used in our laboratory was compared to two treatments in order to

Eric S. Thoman; Ellery D. Ingall; D. Allen Davis; Connie R. Arnold

2001-01-01

153

Large volume sample stacking in capillary zone electrophoresis for the monitoring of the degradation products of metribuzin in environmental samples.  

PubMed

A capillary zone electrophoresis (CZE) method with UV-vis detection has been developed for the simultaneous monitoring of the major degradation products of metribuzin, i.e. deaminometribuzin (DA), deaminodiketometribuzin (DADK) and diketometribuzin (DK). The dissociation acid constants have also been estimated by CE and no significant differences have been observed with the values obtained by applying other techniques. Optimum separation has been achieved in less than 9 min in 40 mM sodium tetraborate buffer, pH 9.5 by applying a voltage of 15kV at 25 degrees C and using p-aminobenzoic acid as internal standard. In order to increase sensitivity, large volume sample stacking (LVSS) with polarity switching has been applied as on-line pre-concentration methodology. Detection limits of 10, 10 and 20 ng/mL for DA, DADK and DK, respectively were obtained. The method has been applied to soil samples, after pressurized liquid extraction (PLE). Samples were extracted at high temperature (103 degrees C and 1500 psi) using methanol as extraction solvent and sodium sulphate as drying agent. This PLE procedure was followed by an off-line pre-concentration and sample clean-up procedure by solid-phase extraction (SPE) using a LiChrolut EN sorbent column. These last two procedures were also suitable for the direct treatment of groundwater samples before CE analysis. The combination of both off-line and on-line pre-concentration procedures provided a significant improvement in sensitivity. LVSS provided pre-concentration factors of 4, 36 and 28 for DK, DA and DADK, respectively and with SPE a pre-concentration of 500-fold for the case of water samples and of 2.5-fold in the case of soil samples was obtained. The method is suitable for the monitoring of these residues in environmental samples with high sensitivity, precision and satisfactory recoveries. PMID:17673223

Quesada-Molina, Carolina; García-Campaña, Ana M; Del Olmo-Iruela, Laura; Del Olmo, Monsalud

2007-09-14

154

Geomechanical effects on CO{sub 2} leakage through fault zones during large-scale underground injection  

SciTech Connect

The importance of geomechanics—including the potential for faults to reactivate during large scale geologic carbon sequestration operations—has recently become more widely recognized. However, notwithstanding the potential for triggering notable (felt) seismic events, the potential for buoyancy-driven CO{sub 2} to reach potable groundwater and the ground surface is actually more important from public safety and storage-efficiency perspectives. In this context, this work extends the previous studies on the geomechanical modeling of fault responses during underground carbon dioxide injection, focusing on the short-term integrity of the sealing caprock, and hence on the potential for leakage of either brine or CO{sub 2} to reach the shallow groundwater aquifers during active injection. We consider stress/strain-dependent permeability and study the leakage through the fault zone as its permeability changes during a reactivation, also causing seismicity. We analyze several scenarios related to the volume of CO{sub 2} injected (and hence as a function of the overpressure), involving both minor and major faults, and analyze the profile risks of leakage for different stress/strain-permeability coupling functions. We conclude that whereas it is very difficult to predict how much fault permeability could change upon reactivation, this process can have a significant impact on the leakage rate. Moreover, our analysis shows that induced seismicity associated with fault reactivation may not necessarily open up a new flow path for leakage. Results show a poor correlation between magnitude and amount of fluid leakage, meaning that a single event is generally not enough to substantially change the permeability along the entire fault length. Consequently, even if some changes in permeability occur, this does not mean that the CO{sub 2} will migrate up along the entire fault, breaking through the caprock to enter the overlying aquifer.

Rinaldi, A.P.; Rutqvist, J.; Cappa, F.

2013-09-01

155

Impact of the construction of a large dam on riparian vegetation cover at different elevation zones as observed from remotely sensed data  

NASA Astrophysics Data System (ADS)

The impact of the construction of a large dam on riparian vegetation cover can be multifold. How the riparian vegetation cover changes at different elevation zones in response to the construction of a large dam and the subsequent impound of reservoir water is still an open question. In this study, we used satellite remote sensing data integrated with geographic information system (GIS) to monitor vegetation cover change at different riparian elevation zones on a large spatial scale, taking the Three Gorges Dam in China as an example. Due to the large scale of this newly formed reservoir, it is expected to impact the riparian vegetation canopy both directly and indirectly. We chose to monitor vegetation cover changes along the 100 km riparian stretch of river directly upstream of the Three Gorges Dam site, over the construction period of eleven years (2000-2010), using MODIS vegetation indices products, digital elevation model (DEM) data from ASTER, and the time series water level data of the Three Gorges reservoir as the data sources. Results show that non-vegetated area increased in the inundated zone (below 175 m), as expected; area of densely vegetated land cover increased within the elevation zone of 175-775 m and no change in vegetation cover was observed above 775 m in elevation. Regression analysis between the vegetation index data and the reservoir water level shows that increasing water levels have had a negative impact on vegetation cover below 175 m, a positive impact on vegetation cover is limited to the region between 175 and 775 m, and no significant impact was observed above 775 m. MODIS EVI product is less sensitive in mapping non-vegetated land cover change, but more sensitive in mapping vegetated land cover change, caused by the reservoir water level variation; both products are similar in effectively tracking a trend between land cover change in each elevation zone with time or with reservoir water level.

Kellogg, Christopher H.; Zhou, Xiaobing

2014-10-01

156

LARGE-SCALEHYDROTHERMAL ZONING REFLECTEDIN THE TETRAHEDRITE-FREIBERGITESOLID SOLUTION, KENO HILL Ag-Pb-Zn DISTRICT, YUKON  

Microsoft Academic Search

The zoned Keno Hill vein system of central Yukon extends laterally from a Cretaceous plutonic-metamorphic center and surrounding quartz-feldspar veins, to carbonate-Ag-Pb-Zn deposits, and further to peripheral veins having epithermal characteristics. Seven distinct mineralogical zones are recognized, and the entire sequence is continuous from east to west in a 4O-kmbelt. The fault- and fracture-controlled veins are stratabound to the brit-

J. V. GREGORY LYNCH

157

Demonstration of split-flow ventilation and recirculation as flow-reduction methods in an Air Force paint spray booth. Final technical report, February 1991-October 1992  

SciTech Connect

During a series of painting operations in a horizontal-flow paint spray booth at Travis AFB, CA, baseline concentrations of four classes of toxic airborne pollutants were measured at 24 locations across a plane immediately forward of the exhaust filters, in the exhaust duct, and inside and outside the respirator in the painter`s breathing zone (BZ). The resulting data were analyzed and used to design a modified ventilation system that (1) separates a portion of the exhaust exiting the lower portion of the booth, which contains a concentration of toxic pollutants greater than the average at the exhaust plane (split-flow); and (2) provides an option to return the flow from the upper portion of the exhaust to the intake plenum for mixing with fresh air and recirculation through the booth (recirculation). After critical review by cognizant Air Force offices and an experimental demonstration showing that a flame ionization detector monitoring the air entering the booth is able to detect excursions above the equivalent exposure limit for the solvents in the paint, the exhaust duct was reconfigured for split-flow and recirculating ventilation. A volunteer painter was briefed on the increased risk of exposure during recirculation, and on the purposes and possible benefits of this study. He then signed an informed consent form before participating in the recirculation tests. A series of tests generally equivalent to the baseline series was conducted during split-flow and recirculating ventilation, and three tests were performed during only split-flow ventilation.

Hughes, S.; Ayer, J.; Sutay, R.

1994-07-01

158

Industrial Energy Conservation, Forced Internal Recirculation Burner  

SciTech Connect

The overall objective of this research project is to develop and evaluate an industrial low NOx burner for existing and new gas-fired combustion systems for intermediate temperature (1400 degree to 2000 degree F) industrial heating devices such as watertube boilers and process fluid heaters. A multi-phase effort is being pursued with decision points to determine advisability of continuance. The current contract over Phases II and III of this work. The objectives of each phase are as follows. Phase II - to design, fabricate, and evaluate prototype burners based on the Forced Internal Recirculation (FIR) concept. Phase III - to evaluate the performance of an FIR burner under actual operating conditions in a full-scale field test and establish the performance necessary for subsequent commercialization

Joseph Rabovitser

2003-06-19

159

Nutrient Management in Recirculating Hydroponic Culture  

NASA Technical Reports Server (NTRS)

There is an increasing need to recirculate and reuse nutrient solutions in order to reduce environmental and economic costs. However, one of the weakest points in hydroponics is the lack of information on managing the nutrient solution. Many growers and research scientists dump out nutrient solutions and refill at weekly intervals. Other authors have recommended measuring the concentrations of individual nutrients in solution as a key to nutrient control and maintenance. Dumping and replacing solution is unnecessary. Monitoring ions in solution is not always necessary; in fact the rapid depletion of some nutrients often causes people to add toxic amounts of nutrients to the solution. Monitoring ions in solution is interesting, but it is not the key to effective maintenance.

Bugbee, Bruce

2004-01-01

160

Recirculation bubbler for glass melter apparatus  

DOEpatents

A gas bubbler device provides enhanced recirculation of molten glass within a glass melter apparatus. The bubbler device includes a tube member disposed within a pool of molten glass contained in the melter. The tube member includes a lower opening through which the molten glass enters and upper slots disposed close to (above or below) the upper surface of the pool of molten glass and from which the glass exits. A gas (air) line is disposed within the tube member and extends longitudinally thereof. A gas bubble distribution device, which is located adjacent to the lower end of the tube member and is connected to the lower end of the gas line, releases gas through openings therein so as to produce gas bubbles of a desired size in the molten glass and in a distributed pattern across the tube member.

Guerrero, Hector (Evans, GA); Bickford, Dennis (Folly Beach, SC)

2007-06-05

161

Growth and Culture of Larval and Juvenile Tautogs in a Closed Recirculating-Seawater System  

Microsoft Academic Search

Field-captured and laboratory-held adult tautogs Tautoga onitis were allowed to spawn naturally under laboratory conditions. Embryos were cultured to hatching and raised successfully through the larval stage to 490-d-old posthatch juveniles. A large (8,500-L), closed, recirculating-seawater system, designed with a biological filter containing air diffusers that passed a strong air?water mixture through a high-surface-area substrate, was used to culture the

Dean M. Perry; Renee Mercaldo-Allen; Stacy Burgh

2001-01-01

162

Exogenous processes study in the coastal zone of the large reservoirs in the archaeological monuments placement (Volga-Kama region)  

NASA Astrophysics Data System (ADS)

The problem of conservation of archaeological heritage is highly relevant for the Republic of Tatarstan (RT), because in its territory identified, studied and registered around 4,300 archaeological sites. Most of archaeological sites from the Mesolithic to the late Middle Ages, now situated in the coastal zone of reservoirs where archaeological objects destroying because of intensive abrasion processes. The Volga and Kama rivers region attracted people for millennia. This territory of the Russian Plain is abounding in archaeological sites of various ages. During the Upper Paleolithic study region was quite convenient for living activity of the first inhabitants because of its situation out of the glacier limits. The sites on the banks are deposited within deluvial sediments of the Late Valday glaciation which have been accumulated on the slope of the Volga and Kama valleys, placing the third terrace and the segmentations of the second terrace over the flood-plain and now completely or fragmentary destroyed by reservoir waters. The analysis of remote sensing (1958-2013) and field survey (2011-2013) data performed. Georeferencing and alignment of the historical maps with remote sensing data makes possible to reveal mistakes in old site plans and re-create the shape of the destroyed archaeological objects, as well to get the exact size of the monument and its correct orientation. Results showed also that the studying sites caused a great rate of destruction of coastline. Cultural heritage sites monitoring, with information about the chronology, cultural layer value, settlement specifics, etc., taking into account the methods used in landscape ecology and field archaeological survey, allows to evaluate damage and the intensity of archaeological sites destruction through the dangerous exogenous processes estimation. Exogenous processes data and archaeological GIS integration will form unified system of archaeological rescue works, will provide analysis of large amount data in a short time, to update and enter new data, etc. This approach will help to determine the most problematic areas, in their funding valuation and archaeological excavations planning and broaden knowledge about the past of the peoples living in study region.

Gaynullin, Iskander; Usmanov, Bulat

2014-05-01

163

Large volume sample stacking in capillary zone electrophoresis for the monitoring of the degradation products of metribuzin in environmental samples  

Microsoft Academic Search

A capillary zone electrophoresis (CZE) method with UV–vis detection has been developed for the simultaneous monitoring of the major degradation products of metribuzin, i.e. deaminometribuzin (DA), deaminodiketometribuzin (DADK) and diketometribuzin (DK). The dissociation acid constants have also been estimated by CE and no significant differences have been observed with the values obtained by applying other techniques. Optimum separation has been

Carolina Quesada-Molina; Ana M. García-Campaña; Laura del Olmo-Iruela; Monsalud del Olmo

2007-01-01

164

Coulomb stress changes in the South Iceland Seismic Zone due to two large earthquakes in June 2000  

E-print Network

Iceland Seismic Zone experienced the largest earthquakes for 88 years in June 2000, with a MS = 6.6 event for example in 1630­1633, 1732­1734, 1784, 1896 and 2000. The largest historical earthquake, with estimated MS to be instrumen- tally recorded [Bjarnason et al., 1993]. Following the 1912 earthquake, the SISZ was seismically

Pedersen, Rikke

165

Holocene paleoseismicity, temporal clustering, and probabilities of future large (M > 7) earthquakes on the Wasatch fault zone, Utah  

Microsoft Academic Search

The clu:onology of M>7 palcoearthquakes on the central five segments of the Wasatch fault zone (WFZ) is one of the best dated in the world and contains 16 earthquakes in the past 5600 years with an average repeat thne of 350 years. Repeat times for individual segments vary by a factor of 2, and range from about 1200 to 2600

J. P. McCalpin; S. P. Nishenko

1996-01-01

166

DETERMINATION OF THE SOLIDS REMOVAL EFFICIENCY FOR SYSTEM COMPONENTS IN A RECIRCULATING AQUACULTURE SYSTEM USING PARTICLE SIEVE ANALYSIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

A major target in the recirculating water treatment scheme of an aquaculture production system is removal of suspended solids. The large volumes of waste fish generate are highly organic in nature and contribute to filter clogging, ammonia production, oxygen consumption, and disease for systems empl...

167

Anoxic gas recirculation system for fouling control in anoxic membrane reactor.  

PubMed

Anoxic gas recirculation system was applied to control the membrane fouling in pilot-scale 4-stage anoxic membrane bioreactor (MBR). In the anaerobic-anoxic-anoxic-aerobic flow scheme, hydrophilic polytetrafluoroethylene (PTFE) membrane (0.2 ?m, 7.2 m(2)/module) was submerged in the second anoxic zone. During 8 months operation, the average flux of the membrane was 21.3 L/(m(2)·hr). Chemical cleaning of the membrane was conducted only once with sodium hydroxide and sodium hypochlorite. Dissolved oxygen (DO) concentration in the second anoxic zone was maintained with an average of 0.19 ± 0.05 mg/L. Gas chromatography analysis showed that the headspace gas in the second anoxic reactor was mainly consisted of N2 (93.0% ± 2.5%), O2 (3.8% ± 0.6%), and CO2 (3.0% ± 0.5%), where the saturation DO concentration in liquid phase was 1.57 mg/L. Atmospheric O2 content (20.5% ± 0.8%) was significantly reduced in the anoxic gas. The average pH in the reactor was 7.2 ± 0.4. As a result, the recirculation of the anoxic gas was successfully applied to control the membrane fouling in the anoxic MBR. PMID:25079838

Lee, Hansaem; Lee, Daeju; Hong, Seongwan; Yun, Geum Hee; Kim, Sungpyo; Hwang, Jung Ki; Lee, Woojae; Yun, Zuwhan

2014-06-01

168

Origin and emplacement of the andesite of Burroughs Mountain, a zoned, large-volume lava flow at Mount Rainier, Washington, USA  

USGS Publications Warehouse

Burroughs Mountain, situated at the northeast foot of Mount Rainier, WA, exposes a large-volume (3.4 km3) andesitic lava flow, up to 350 m thick and extending 11 km in length. Two sampling traverses from flow base to eroded top, over vertical sections of 245 and 300 m, show that the flow consists of a felsic lower unit (100 m thick) overlain sharply by a more mafic upper unit. The mafic upper unit is chemically zoned, becoming slightly more evolved upward; the lower unit is heterogeneous and unzoned. The lower unit is also more phenocryst-rich and locally contains inclusions of quenched basaltic andesite magma that are absent from the upper unit. Widespread, vuggy, gabbronorite-to-diorite inclusions may be fragments of shallow cumulates, exhumed from the Mount Rainier magmatic system. Chemically heterogeneous block-and-ash-flow deposits that conformably underlie the lava flow were the earliest products of the eruptive episode. The felsic-mafic-felsic progression in lava composition resulted from partial evacuation of a vertically-zoned magma reservoir, in which either (1) average depth of withdrawal increased, then decreased, during eruption, perhaps due to variations in effusion rate, or (2) magmatic recharge stimulated ascent of a plume that brought less evolved magma to shallow levels at an intermediate stage of the eruption. Pre-eruptive zonation resulted from combined crystallization- differentiation and intrusion(s) of less evolved magma into the partly crystallized resident magma body. The zoned lava flow at Burroughs Mountain shows that, at times, Mount Rainier's magmatic system has developed relatively large, shallow reservoirs that, despite complex recharge events, were capable of developing a felsic-upward compositional zonation similar to that inferred from large ash-flow sheets and other zoned lava flows. ?? 2002 Elsevier Science B.V. All rights reserved.

Stockstill, K.R.; Vogel, T.A.; Sisson, T.W.

2002-01-01

169

Future of recirculating systems in the US aquaculture industry  

SciTech Connect

Recirculating systems consist of a culture unit, a recirculating pump, and a treatment block which facilitate extended re-use of water in the rearing of aquatic animals. As water re-use is extended from a few hours to months or even years, the complexity of the treatment block increases. Classified as either `open` with greater than 10 percent water replacement per day or `closed` with less than 10 percent daily replacement, most recirculating systems include aerators, clarifiers, and biofilters as key core elements. The aquaculture industry is increasingly facing a variety of socio-economic issues which will dramatically influence its future development. These problems range from increased competition for water rights through price depression and foreign imports to predation by protected migratory birds. As water-use, environmental, and conservation conflicts grow, the cost differences between the flow-through and closed production technologies will narrow, increasing the industry`s use of recirculating systems.

Malone, R.F.

1994-08-01

170

Impact of nitrate-enhanced leachate recirculation on gaseous releases from a landfill bioreactor cell  

SciTech Connect

This study evaluates the impact of nitrate injection on a full scale landfill bioreactor through the monitoring of gaseous releases and particularly N{sub 2}O emissions. During several weeks, we monitored gas concentrations in the landfill gas collection system as well as surface gas releases with a series of seven static chambers. These devices were directly connected to a gas chromatograph coupled to a flame ionisation detector and an electron capture detector (GC-FID/ECD) placed directly on the field. Measurements were performed before, during and after recirculation of raw leachate and nitrate-enhanced leachate. Raw leachate recirculation did not have a significant effect on the biogas concentrations (CO{sub 2}, CH{sub 4} and N{sub 2}O) in the gas extraction network. However, nitrate-enhanced leachate recirculation induced a marked increase of the N{sub 2}O concentrations in the gas collected from the recirculation trench (100-fold increase from 0.2 ppm to 23 ppm). In the common gas collection system however, this N{sub 2}O increase was no more detectable because of dilution by gas coming from other cells or ambient air intrusion. Surface releases through the temporary cover were characterized by a large spatial and temporal variability. One automated chamber gave limited standard errors over each experimental period for N{sub 2}O releases: 8.1 {+-} 0.16 mg m{sup -2} d{sup -1} (n = 384), 4.2 {+-} 0.14 mg m{sup -2} d{sup -1} (n = 132) and 1.9 {+-} 0.10 mg m{sup -2} d{sup -1} (n = 49), during, after raw leachate and nitrate-enhanced leachate recirculation, respectively. No clear correlation between N{sub 2}O gaseous surface releases and recirculation events were evidenced. Estimated N{sub 2}O fluxes remained in the lower range of what is reported in the literature for landfill covers, even after nitrate injection.

Tallec, G.; Bureau, C. [Cemagref, UR HBAN, Parc de Tourvoie, BP44, F-92163 Antony (France); Peu, P.; Benoist, J.C. [Cemagref, UR GERE, 17 Avenue de Cucille, CS 64427, F-35044 Rennes (France); Lemunier, M. [Suez-Environnement, CIRADE, 38 Av. Jean Jaures, 78440 Gargenville (France); Budka, A.; Presse, D. [SITA France, 132 Rue des 3 Fontanot, 92000 Nanterre Cedex (France); Bouchez, T. [Cemagref, UR HBAN, Parc de Tourvoie, BP44, F-92163 Antony (France)], E-mail: theodore.bouchez@cemagref.fr

2009-07-15

171

Heat recirculating cooler for fluid stream pollutant removal  

DOEpatents

A process by which heat is removed from a reactant fluid to reach the operating temperature of a known pollutant removal method and said heat is recirculated to raise the temperature of the product fluid. The process can be utilized whenever an intermediate step reaction requires a lower reaction temperature than the prior and next steps. The benefits of a heat-recirculating cooler include the ability to use known pollutant removal methods and increased thermal efficiency of the system.

Richards, George A. (Morgantown, WV); Berry, David A. (Morgantown, WV)

2008-10-28

172

Geothermal evidence for fluid flow through the gas hydrate stability field off Central Chile-transient flow related to large subduction zone earthquakes?  

NASA Astrophysics Data System (ADS)

Fluids are suspected to play a major role in the nucleation and rupture propagation of earthquakes. In Chile, seismological data were previously interpreted to indicate that fluids captured in the fault zone are released periodically during large underthrust earthquakes, leading to post-seismic fluid flow. In central Chile, heat flow derived from the presence of a bottom simulating reflector (BSR) show a smooth trend across the margin. BSR-derived data are in excellent agreement with thermal subduction zone models. Over the young accretionary prism, both BSR-derived and measured surface heat flow support a common trend. Landwards of the backstop, however, measured heat flow triples over a distance of 20-30 km, producing a profound discrepancy to the BSR-derived data. We suggest that this disparity is related to transient flow of warm fluids through the gas hydrate stability zone possibly caused by fluids released after large underthrust earthquakes. Such flow events may inherently affect the distribution of solid gas hydrates between the seafloor and the BSR.

Grevemeyer, Ingo; Kaul, Norbert; Diaz-Naveas, Juan L.

2006-07-01

173

Field evaluation of a horizontal well recirculation system for groundwater treatment: Pilot test at the Clean Test Site Portsmouth Gaseous Diffusion Plant, Piketon, Ohio  

SciTech Connect

This report presents the results of field testing a horizontal well recirculation system at the Portsmouth Gaseous Diffusion Plant (PORTS). The recirculation system uses a pair of horizontal wells, one for groundwater extraction and treatment and the other for reinjection of treated groundwater, to set up a recirculation flow field. The induced flow field from the injection well to the extraction well establishes a sweeping action for the removal and treatment of groundwater contaminants. The overall purpose of this project is to study treatment of mixed groundwater contaminants that occur in a thin water-bearing zone not easily targeted by traditional vertical wells. The project involves several research elements, including treatment-process evaluation, hydrodynamic flow and transport modeling, pilot testing at an uncontaminated site, and pilot testing at a contaminated site. The results of the pilot test at an uncontaminated site, the Clean Test Site (CTS), are presented in this report.

Muck, M.T.; Kearl, P.M.; Siegrist, R.L. [and others] [and others

1998-08-01

174

Nappe-Bounding Shear Zones Initiated On Syn-Tectonic, Pegmatite-Filled Extensional Shear Fractures During Deep-Crustal Nappe Flow In A Large Hot Orogen  

NASA Astrophysics Data System (ADS)

The Central Gneiss Belt (CGB) of the Proterozoic western Grenville Province is an extensive exposure of the mid-crustal levels (upper amphibolite facies, lesser granulites) of a large hot orogen. Numerical models give a credible prediction of structure and metamorphism accompanying CGB deep-crustal nappe flow and define a temporal framework based on four developmental phases: thickening, heating, nappe-flow and post convergence extensional spreading. These phases are diachronous in direction of orogen propagation and imply a spatial framework: externides (close to orogen-craton boundary) containing moderately inclined thickening and/or extensional structures, and internides containing thickening structures overprinted by sub-horizontal nappe flow structures, which may be locally overprinted by those due to extensional spreading. Although on average of granitoid composition, CGB nappes differ in rheology, varying from fertile and weak (unmetamorphosed before Grenville, meltable) to infertile and strong (metamorphosed at high grade before Grenville, unmeltable) or mixed fertile-infertile protoliths. Deformation style varies from diffuse in fertile nappes, weakened by pervasive melting, to localised in shear zones on boundaries or interiors of infertile nappes. Specifically, in terms of deformation phase and location within the orogen, shear zones occur as: thickening structures of externides, early thickening- and later overprinting nappe-flow structures of infertile internide nappes, and extension-related shear zones in externides and internides. Many of the nappe-flow shear zones of the internides are associated with pegmatites. One example has been recognized of a preserved progression from small-scale fracture arrays to regional shear zone. The sequence is present on a km-scale and initiates in the interior of a nappe of layered granulite with arrays of pegmatite filled extensional-shear fractures (mm to cm width) displaying amphibolized margins. The fracture arrays develop into systems of pegmatite cored amphibolite facies shear zones (cm to dm width) lying within metre-scale corridors of variably retrogressed unsheared layered granulite. The sequence culminates with transposition of the layered protolith within the kilometre-scale amphibolite facies shear zone that forms the base of the granulite nappe. The pegmatitic hydrous magma clearly plays a role in initial crack formation, progressive retrogression and weakening of the granulite but its source remains obscure.

Culshaw, Nicholas; Gerbi, Christopher; Marsh, Jeffrey; Regan, Peter

2014-05-01

175

Removal of acidic pharmaceuticals within a nitrifying recirculating biofilter.  

PubMed

The fate of pharmaceutically active compounds (PhACs) in wastewater treatment systems is an area of increasing concern. Little research has been done to understand this issue in rural or decentralized communities. The objective of this research was to examine the ability of a bench scale nitrifying recirculating biofilter (RBF) to remove four acidic PhACs: gemfibrozil, naproxen, ibuprofen and diclofenac from secondary treated municipal wastewater at concentrations of 20 and 200?g/L. The average removals in this study were between 92 and 99% for ibuprofen, 89 and 99% for naproxen, 62 and 92% for gemfibrozil and 40 and 76% for diclofenac, which is consistent with literature. Ibuprofen and naproxen were largely removed through biological transformation; whereas gemfibrozil and diclofenac showed more variable removal, likely due to both biological transformation and sorption processes. PhAC removal in the RBFs was repeatable between trials, robust and responsive to system upsets, and the presence of PhACs as a single compound versus mixtures had no impact on PhAC removal efficiency. In summary, this study indicates that RBFs as a nitrifying stage of a multi-stage filtration process could be a viable technology for removal of some acidic pharmaceuticals in small onsite wastewater treatment facilities. PMID:24727009

Krkošek, W H; Payne, S J; Gagnon, G A

2014-05-30

176

Bio-desulfurization of biogas using acidic biotrickling filter with dissolved oxygen in step feed recirculation.  

PubMed

Triple stage and single stage biotrickling filters (T-BTF and S-BTF) were operated with oxygenated liquid recirculation to enhance bio-desulfurization of biogas. Empty bed retention time (EBRT 100-180s) and liquid recirculation velocity (q 2.4-7.1m/h) were applied. H2S removal and sulfuric acid recovery increased with higher EBRT and q. But the highest q at 7.1m/h induced large amount of liquid through the media, causing a reduction in bed porosity in S-BTF and H2S removal. Equivalent performance of S-BTF and T-BTF was obtained under the lowest loading of 165gH2S/m(3)/h. In the subsequent continuous operation test, it was found that T-BTF could maintain higher H2S elimination capacity and removal efficiency at 175.6±41.6gH2S/m(3)/h and 89.0±6.8% versus S-BTF at 159.9±42.8gH2S/m(3)/h and 80.1±10.2%, respectively. Finally, the relationship between outlet concentration and bed height was modeled. Step feeding of oxygenated liquid recirculation in multiple stages clearly demonstrated an advantage for sulfide oxidation. PMID:25569031

Chaiprapat, Sumate; Charnnok, Boonya; Kantachote, Duangporn; Sung, Shihwu

2015-03-01

177

Tiny Is Mighty: Seagrass Beds Have a Large Role in the Export of Organic Material in the Tropical Coastal Zone  

PubMed Central

Ecosystems in the tropical coastal zone exchange particulate organic matter (POM) with adjacent systems, but differences in this function among ecosystems remain poorly quantified. Seagrass beds are often a relatively small section of this coastal zone, but have a potentially much larger ecological influence than suggested by their surface area. Using stable isotopes as tracers of oceanic, terrestrial, mangrove and seagrass sources, we investigated the origin of particulate organic matter in nine mangrove bays around the island of Phuket (Thailand). We used a linear mixing model based on bulk organic carbon, total nitrogen and ?13C and ?15N and found that oceanic sources dominated suspended particulate organic matter samples along the mangrove-seagrass-ocean gradient. Sediment trap samples showed contributions from four sources oceanic, mangrove forest/terrestrial and seagrass beds where oceanic had the strongest contribution and seagrass beds the smallest. Based on ecosystem area, however, the contribution of suspended particulate organic matter derived from seagrass beds was disproportionally high, relative to the entire area occupied by mangrove forests, the catchment area (terrestrial) and seagrass beds. The contribution from mangrove forests was approximately equal to their surface area, whereas terrestrial contributions to suspended organic matter under contributed compared to their relative catchment area. Interestingly, mangrove forest contribution at 0 m on the transects showed a positive relationship with the exposed frontal width of the mangrove, indicating that mangrove forest exposure to hydrodynamic energy may be a controlling factor in mangrove outwelling. However we found no relationship between seagrass bed contribution and any physical factors, which we measured. Our results indicate that although seagrass beds occupy a relatively small area of the coastal zone, their role in the export of organic matter is disproportional and should be considered in coastal management especially with respect to their importance as a nutrient source for other ecosystems and organisms. PMID:25386853

Gillis, Lucy G.; Ziegler, Alan D.; van Oevelen, Dick; Cathalot, Cecile; Herman, Peter M. J.; Wolters, Jan W.; Bouma, Tjeerd J.

2014-01-01

178

Large-scale separation of hydroxyanthraquinones from Rheum palmatum L. by pH-zone-refining counter-current chromatography  

Microsoft Academic Search

pH-zone-refining counter-current chromatography was successfully applied to purify four hydroxyanthraquinones, rhein, emodin, aloe-emodin and chrysophanol, from three crude extracts of Rheum palmatum L.. After the two-phase solvent system methyl tert-butyl ether–tetrahydrofuran–water at an optimized volume ratio of 2:2:3 (v\\/v) was equilibrated, trifluoroacetic acid (10mM) was added to the organic phase as a retainer and ammonia (10mM), sodium carbonate (15mM) and

Shengqiang Tong; Jizhong Yan

2007-01-01

179

77 FR 29254 - Safety Zones, Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to Mile Marker...  

Federal Register 2010, 2011, 2012, 2013

...the Port of New Orleans Cruise Ship Terminal, mile...astern of each large cruise ship. This safety measure...associated with congested maritime traffic on the Lower...astern of each large cruise ship transiting the Lower...associated with congested maritime traffic on the...

2012-05-17

180

Influence of leachate recirculation on aerobic and anaerobic decomposition of solid wastes.  

PubMed

In this study, the effect of leachate recirculation on aerobic and anaerobic degradation of municipal solid wastes is determined by four laboratory-scale landfill reactors. The options studied and compared with the traditional anaerobic landfill are: leachate recirculation, landfill aeration, and aeration with leachate recirculation. Leachate quality is regularly monitored by the means of pH, alkalinity, total dissolved solids, conductivity, oxidation-reduction potential, chloride, chemical oxygen demand, ammonia, and total Kjeldahl nitrogen, in addition to generated leachate quantity. Aerobic leachate recirculated landfill appears to be the most effective option in the removal of organic matter and ammonia. The main difference between aerobic recirculated and non-recirculated landfill options is determined at leachate quantity. Recirculation is more effective on anaerobic degradation of solid waste than aerobic degradation. Further studies are going on to determine the optimum operational conditions for aeration and leachate recirculation rates, also with the operational costs of aeration and recirculation. PMID:17023112

Bilgili, M Sinan; Demir, Ahmet; Ozkaya, Bestamin

2007-05-01

181

Characterizing a large shear-zone with seismic and magnetotelluric methods: The case of the Dead Sea Transform  

USGS Publications Warehouse

Seismic tomography, imaging of seismic scatterers, and magnetotelluric soundings reveal a sharp lithologic contrast along a ???10 km long segment of the Arava Fault (AF), a prominent fault of the southern Dead Sea Transform (DST) in the Middle East. Low seismic velocities and resistivities occur on its western side and higher values east of it, and the boundary between the two units coincides partly with a seismic scattering image. At 1-4 km depth the boundary is offset to the east of the AF surface trace, suggesting that at least two fault strands exist, and that slip occurred on multiple strands throughout the margin's history. A westward fault jump, possibly associated with straightening of a fault bend, explains both our observations and the narrow fault zone observed by others. Copyright 2005 by the American Geophysical Union.

Maercklin, N.; Bedrosian, P.A.; Haberland, C.; Ritter, O.; Ryberg, T.; Weber, M.; Weckmann, U.

2005-01-01

182

Onshore-offshore seismic networks: an inescapable approach to reveal the crustal structure and the seismic activity of large subduction zones  

NASA Astrophysics Data System (ADS)

Ninety percent of the seismic energy released worldwide and ninety percent of the largest earthquakes and tsunamis occur in subduction zones. Several recent catastrophic subduction earthquakes surprised us on many aspects, either because we had been unable to anticipate their extremely large magnitude (2011 Tohoku Earthquake, Mw 9.0), or because we had considered the subduction as partly aseismic (2004 Sumatra Andaman earthquake, Mw 9.1). One of the reasons for our present ignorance of the behavior of large subduction earthquakes is the lack of marine data to image and monitor the structure and evolution of megathrust faults offshore. Over the last 15 years, our group has conducted several passive and active seismic experiments* in the forearc regions of the Ecuador-Colombia, Lesser Antilles and Hellenic subduction zones. The objectives of these experiments were to image the subduction interplate fault at depth and accurately locate the current earthquake activity of the megathrusts using arrays of combined ocean-bottom and land-based seismometers. In the case of very large events and in the absence of geodetic data in the offshore part of the faults, the precise knowledge of current seismicity is mandatory to estimate the seismogenic behavior and potential of the fault interface. 2D dense active seismic lines, shot jointly with multichannel acquisitions, provide invaluable images of the deep structure of the Lesser Antilles arc and forearc, which allow locating the updip and downdip limits of the expected seismogenic zone. Assuming that the Moho is the downdip limit of the seismogenic zone, the 26 km-thick crust of the arc makes the seismogenic zone 3 times wider than it is in ';standard' oceanic arcs (like Marianas). 3D active and passive experiments in the Lesser Antilles and Ecuador forearcs provide an unprecedented way to image the structure in 3D down to the lower plate. The tomography documents the spatial variability of the interplate fault structure and of the plate above, and thereby sheds light on the control that the fault structure might play on the interface coupling. In both Antilles and Ecuador, we show that the nature and rheology of the upper plate together influence the seismic coupling and hence the behavior of large earthquakes. Since the sediment and upper-crustal structure markedly vary in space, a precise knowledge of those variations is mandatory to precisely locate earthquake hypocenters and to examine their relationships with the master subduction fault. In both Antilles and Ecuador, we show that most of the interseismic earthquake activity is concentrated in the lower crust and in the mantle wedge, suggesting that the interplate fault has a seismogenic, stick-slip behavior below the Moho of the upper plate. The occurrence of these events within the mantle wedge requires the presence of chemical heterogeneity there, since the latter is expected to be serpentinized and hence aseismic. *Since 2000, we conducted ten experiments in subduction zones in cooperation with French (IPG, Paris), European (Geomar, Kiel; National Observatory, Athens) and south American (Institute of Geophysics EPN, Quito) partners.

Charvis, P.; Galve, A.; Laigle, M.; Hirn, A.; Hello, Y. M.; Oge, A.; Yates, B. A.

2013-12-01

183

Large Earthquake Hazard of the San Jacinto Fault Zone, CA, from Long Record of Simulated Seismicity Assimilating the Available Instrumental and Paleoseismic Data  

NASA Astrophysics Data System (ADS)

We investigate spatio-temporal properties of earthquake patterns in the San Jacinto fault zone (SJFZ), California, between Cajon Pass and the Superstition Hill Fault, using a long record of simulated seismicity constrained by available seismological and geological data. The model provides an effective realization of a large segmented strike-slip fault zone in a 3D elastic half-space, with heterogeneous distribution of static friction chosen to represent several clear step-overs at the surface. The simulated synthetic catalog reproduces well the basic statistical features of the instrumental seismicity recorded at the SJFZ area since 1981. The model also produces events larger than those included in the short instrumental record, consistent with paleo-earthquakes documented at sites along the SJFZ for the last 1,400 years. The general agreement between the synthetic and observed data allows us to address with the long-simulated seismicity questions related to large earthquakes and expected seismic hazard. The interaction between m ? 7 events on different sections of the SJFZ is found to be close to random. The hazard associated with m ? 7 events on the SJFZ increases significantly if the long record of simulated seismicity is taken into account. The model simulations indicate that the recent increased number of observed intermediate SJFZ earthquakes is a robust statistical feature heralding the occurrence of m ? 7 earthquakes. The hypocenters of the m ? 5 events in the simulation results move progressively towards the hypocenter of the upcoming m ? 7 earthquake.

Zöller, G.; Ben-Zion, Y.

2014-11-01

184

Experimental investigation of reactive turbulent recirculating jet mixing in a dump  

NASA Technical Reports Server (NTRS)

A ducted, subsonic, hydrogen air turbulent jet mixing flowfield was investigated, both with and without combustion. The geometric configuration was representative of a sudden expansion or dump combustor, with a central air jet surrounded by a low velocity hydrogen stream at an overall equivalence ratio of 0.12. The ratio of the duct to inner nozzle diameter was 2.5. Radial distributions of mean axial and radial velocity, axial and radial turbulent intensity, velocity cross correlation, gas composition, static temperature and total pressure, as well as axial distributions of wall static pressure, were obtained for axial stations from zero to six duct diameters from the combustor entrance. The data indicate that mixing is slower in the chemically reactive flow field than in the nonreactive flow field, and that the presence of combustion has a significant effect on the size and location of the recirculation zone within the mixing duct.

Smith, G. D.; Giel, T. V.; Catalano, C. G.

1980-01-01

185

Blood recirculation in temporary central catheters for acute hemodialysis.  

PubMed

The low-flow method has been shown as a reliable evaluation of access recirculation. Few data is available on temporary central catheter blood recirculation; results of 2% and 4% have been reported in subclavian, 10% in 24 cm long femoral, and 18% in 15 cm long femoral catheters, mostly in indwelling catheters for chronic hemodialysis. The purpose of this prospective study was to evaluate blood recirculation in a larger number of recently inserted temporary intravenous catheters for acute hemodialysis, comparing subclavian and femoral sites. Fifty blood recirculation measurements were performed in 38 different temporary central venous dialysis catheters inserted in thirty-one critically ill patients from medical and surgical intensive care units presenting acute renal failure supported by intermittent hemodialysis. All the catheters used were well-functioning 11.5 French dual lumen Quinton of 13.5 or 19.5 cm length. Catheters presenting mechanical dysfunction, which did not allow a blood flow rate of 300 ml/min or for which lines had to be reversed were excluded from the analysis. Access blood recirculation was measured shortly after catheter insertion according to the low flow method applied after the first 30 minutes of hemodialysis at a blood flow rate of 300 ml/min. Mean blood recirculation for the 50 measurements was 10.3 +/- 9.2%. It was significantly higher in the 26 femoral catheters than in the 24 subclavian catheters, reaching respective means of 16.1 +/- 9.1% and 4.1 +/- 3.6% (p = 0.0001). Blood recirculation rate was not different between 13.5 cm and 19.5 cm long subclavian catheters (3.0 +/- 2.6%, n = 13, versus 5.4 +/- 4.3%, n = 11, respectively), but was significantly higher in 13.5 cm long femoral catheters (22.8 +/- 9.1%, n = 9, versus 12.6 +/- 6.9%, n = 17) (p = 0.004). Blood recirculation was measured on two separate occasions in 12 catheters randomly selected (5 femoral and 7 subclavian catheters); the obtained results were reproducible with a mean difference of only 2.1 +/- 1.8% between the two measurements and a correlation of 0.96. The mean time elapsed between catheter insertion and recirculation assessment was 2.2 +/- 3.1 days and was similar for femoral and subclavian catheters. No correlation was found between the percentage of recirculation and the arterial and venous resistances recorded during dialysis session or with the time from catheter insertion. Mean urea reduction ratio (URR) for the 50 dialysis sessions was 57.8 +/- 13.0%. It was significantly higher for sessions performed with subclavian than with femoral catheters (62.5 +/- 10.9%, n = 24, versus 54.5 +/- 14.2%, n = 26) (p = 0.03). In conclusion, the expected blood recirculation in well-functioning and recently inserted temporary dialysis catheters is under 5% for subclavian, over 12% in 19.5 cm femoral, and over 22% in shorter 13.5 cm femoral catheters at a blood flow rate of 300 ml/min. The consequently reduced dialysis efficiency with femoral catheters is another factor to be considered in the choice of a site for temporary dialysis catheter insertion in acute renal failure patients, particularly when dialysis dose delivery is a priority, such as intoxication cases treated by extracorporeal therapy. PMID:8738663

Leblanc, M; Fedak, S; Mokris, G; Paganini, E P

1996-05-01

186

Low-head saltwater recirculating aquaculture systems utilized for juvenile red drum production  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recirculating aquaculture systems reuse water with mechanical and biological treatment between each use and thus require wastewater treatment techniques for continuous waste removal. However, the traditional techniques and equipment utilized in recirculating aquaculture systems are expensive. The d...

187

In-tank aeration, a necessary compliment of loaded systems in an airlift recirculating aquaculture system  

Technology Transfer Automated Retrieval System (TEKTRAN)

Water treatment components in recirculating aquaculture systems in generally address solids removal, nitrification, circulation, aeration, and degasification. Airlift pumps in a recirculating aquaculture system can address water circulation, aeration, and degasification. Recent data indicates oxygen...

188

Demonstration of split-flow ventilation and recirculation as flow-reduction methods in an Air Force paint spray booth. Final report, 15 February 1991-9 October 1992  

SciTech Connect

During a series of painting operations in a horizontal-flow paint spray booth at Travis AFB, CA, baseline concentrations of four classes of toxic airborne pollutants were measured at 24 locations across a plane immediately forward of the exhaust filters, in the exhaust duct, and inside and outside the respirator in the painter`s breathing zone (BZ). The resulting data were analyzed and used to design a modified ventilation system that (1) separates a portion of the exhaust exiting the lower portion of the booth, which contains a concentration of toxic pollutants greater than the average at the exhaust plane (split-flow); and (2) provides an option to return the flow from the upper portion of the exhaust to the intake plenum for mixing with fresh air and recirculation through the booth (recirculation). After critical review by cognizant Air Force offices and an experimental demonstration showing that a flame ionization detector monitoring the air entering the booth is able to detect excursions above the equivalent exposure limit for the solvents in the paint, the exhaust duct was reconfigured for split-flow and recirculating ventilation. A volunteer painter was briefed on the increased risk of exposure during recirculation, and on the purposes and possible benefits of this study. He then signed an informed consent form before participating in the recirculation tests. A series of tests generally equivalent to the baseline series was conducted during split-flow and recirculating ventilation, and three tests were performed during only split-flow ventilation.

Hughes, S.; Ayer, J.; Sutay, R.

1994-07-27

189

Role of Differential Air Pressure Zones in the Control of Aerosols in a Large Animal Isolation Facility  

PubMed Central

The uncontrolled transmission of hog cholera in a large animal isolation facility, designed to control the movement of aerosols within and between individual wings of a multiunit building, indicated the need for a critical study of aerosol behavior under existing conditions of operation. Studies with aerosols of Escherichia coli B T3 bacteriophage (T3 coliphage) conclusively demonstrated the impossibility of obtaining the desired control by means of a “static” air balance relationship between adjacent areas within the facility. Modifications needed to provide the desired control of the air-handling system are outlined and discussed. Images Fig. 1 Fig. 2 Fig. 3 PMID:5951332

Sullivan, James F.; Songer, Joseph R.

1966-01-01

190

Application of airlift technology in recirculation aquaculture systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Marine hatcheries implementing recirculating aquaculture technology require pristine water quality and must be designed to provide a disease free environment as much as possible to limit disease transmission. Given the aggressive nature of a variety of marine pathogens, design considerations with re...

191

Developments in recirculation systems for Mediterranean fish species  

Microsoft Academic Search

Nowadays, most European commercial hatcheries use recirculating water systems for all the different stages of Mediterranean fish rearing, from breeders to fingerlings several grams in weight. Despite a higher initial investment relative to flow-through systems, this technology reduces production costs mainly because much less energy is required for heating and the survival rate of the fingerlings is much higher. The

Jean Paul Blancheton

2000-01-01

192

A recirculating seawater aquarium system for inland laboratories  

Microsoft Academic Search

We have designed and installed a 7,500 l recirculating aquarium system for the purpose of maintaining marine gastropods in an inland laboratory. It is completely nonmetallic and can be adapted for any number of isolated living compartments. Vonvenient and efficient filtration is achieved by the use of disposable cartridge filters. The water temperature is regulated by a direct expansion cooling

M. E. Lickey; R. L. Emigh; F. R. Randle

1970-01-01

193

33 CFR 159.127 - Safety coliform count: Recirculating devices.  

...devices. Thirty-eight of forty samples of flush fluid from a recirculating device must have less than 240 fecal coliform bacteria per 100 milliliters. These samples must be collected in accordance with § 159.123(b) and tested in accordance with...

2014-07-01

194

33 CFR 159.127 - Safety coliform count: Recirculating devices.  

Code of Federal Regulations, 2012 CFR

...devices. Thirty-eight of forty samples of flush fluid from a recirculating device must have less than 240 fecal coliform bacteria per 100 milliliters. These samples must be collected in accordance with § 159.123(b) and tested in accordance with...

2012-07-01

195

33 CFR 159.127 - Safety coliform count: Recirculating devices.  

Code of Federal Regulations, 2011 CFR

...devices. Thirty-eight of forty samples of flush fluid from a recirculating device must have less than 240 fecal coliform bacteria per 100 milliliters. These samples must be collected in accordance with § 159.123(b) and tested in accordance with...

2011-07-01

196

The effect of flow recirculation on abdominal aortic aneurysm  

NASA Astrophysics Data System (ADS)

The presences of flow recirculation at the abdominal aortic aneurysm (AAA) region yield the unpredictable failure of aneurismal wall. The failure of the aneurismal wall is closely related to the hemodynamic factor. Hemodynamic factor such as pressure and velocity distribution play a significance role of aneurysm growth and rupture. By using the computational approach, the influence of hemodynamic factor is investigated using computational fluid dynamic (CFD) method on the virtual AAA model. The virtual 3D AAAs model was reconstructed from Spiral Computed Tomography scan (CT-scan). The blood flow is assumed as being transient, laminar and Newtonian within a rigid section of the vessel. The blood flow also driven by an imposed of pressure gradient in the form of physiological waveform. The pulsating blood flow is also considered in this simulation. The results on pressure distribution and velocity profile are analyzed to interpret the behaviour of flow recirculation. The results show the forming of vortices is seen at the aneurysm bulge. This vortices is form at the aneurysm region then destroyed rapidly by flow recirculation. Flow recirculation is point out much higher at distal end of aneurysm closed to iliac bifurcation. This phenomenon is managed to increase the possibility of aneurysm growth and rupture.

Taib, Ishkrizat; Amirnordin, Shahrin Hisham; Madon, Rais Hanizam; Mustafa, Norrizal; Osman, Kahar

2012-06-01

197

Use of low temperature blowers for recirculation of hot gases  

DOEpatents

An apparatus is described for maintaining motors at low operating temperatures during recirculation of hot gases in fuel cell operations and chemical processes such as fluidized bed coal gasification. The apparatus includes a means for separating the hot process gas from the motor using a secondary lower temperature gas, thereby minimizing the temperature increase of the motor and associated accessories.

Maru, H.C.; Forooque, M.

1982-08-19

198

An Inexpensive Recirculating Aquaculture System with Multiple Use Capabilities.  

ERIC Educational Resources Information Center

Describes the construction of an inexpensive recirculating aquaculture system that can hold up to 46 pounds of fish, invertebrates, and mussels for classroom use. The system is versatile, requires little maintenance, and can be used for both teaching and research purposes. (WRM)

Scurlock, Gerald Don, Jr.; Cook, S. Bradford; Scurlock, Carrie Ann

1999-01-01

199

Exhaust gas recirculation valve device for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation valve device is described for an exhaust gas cleaning apparatus of an internal combustion engine for an automobile. A diaphragm mechanism is mounted on a body for operating the valve device. The diaphragm mechanism has a diaphragm and has, on both sides of the diaphragm, chambers which should be connected to the respective engine ports. One

M. Ando; K. Katow; M. Yamazaki

1977-01-01

200

10 Commercially Feasible Urban Recirculating Aquaculture: Addressing the Marine Sector  

Microsoft Academic Search

With the global collapse of marine fisheries and the environmental issues associated with net-pen aquaculture practices, there is a pressing need to develop fully contained and environmentally sus- tainable approaches to producing seafood. Recirculating aquaculture systems (RAS), which provide this approach, have been widely used over the last two decades to farm freshwater species. However, the cost associated with the

Yonathan Zohar; Yossi Tal; Harold Schreier; Colin Steven; John Stubblefield

201

Amplified recirculating circuits for pseudo-continuous wave generation  

Microsoft Academic Search

An analysis of amplified recirculating structures for producing a pseudo-continuous wave, PCW, signal is presented. Experimentations with amplification provided by EDFA and SOA are shown. Both the hold-on function and the switch-off function are analyzed. The comparison between structures with different amplifiers shows better duration performances for EDFAs, but faster all-optical operation capabilities for SOAs.

Paola Parolari; Lucia Marazzi; Pierpaolo Boffi; Mario Martinelli

1999-01-01

202

Parameters of the Second Muon Recirculating Linear Accelerator for  

E-print Network

into muon decay rings for a ¡ factory, in a fashion very similar to that for designing muon storage rings [1 aperture of the storage ring should provide, the relative energy spread § e and the muon beam current beam Mathematica commands for parameter searches of muon recirculating linear accelera- tors RLA, used as injectors

Keil, Eberhard

203

Using exhaust gas recirculation in internal combustion engines: a review  

Microsoft Academic Search

The aim of this work is to review the potential of exhaust gas recirculation (EGR) to reduce the exhaust emissions, particularly NOX emissions, and to delimit the application range of this technique. A detailed analysis of previous and current results of EGR effects on the emissions and performance of Diesel engines, spark ignition engines and duel fuel engines is introduced.

G. H. Abd-Alla

2002-01-01

204

Management Ability and the Economics of Recirculating Aquaculture Production Systems  

Microsoft Academic Search

A bioeconomic model of fish growth in recirculating aquaculture systems was constructed by developing a bioenergetic model comprised of metabolic sub-models for growth, ammonia production, and oxygen consumption. Metabolite accumulations are determined by exogenous control variables for filtration and aeration and used to indirectly represent management ability. Numerical solutions to model parameters were obtained using a two point boundary shooting

Richard F. Kazmierczak Jr.; Rex H. Caffey

1995-01-01

205

Aeration Performance of Triangular Notch Weirs at Recirculating System  

Microsoft Academic Search

An adequate supply of dissolved oxygen is essential for the survival of aquatic organisms. Hydraulic structures can increase dissolved oxygen levels by creat- ing turbulent conditions, where small air bubbles are carried into the bulk of the flow. Plunging overfall jets from weirs at recirculating systems are a partic- ular instance of this. This paper seeks triangular notch weirs having

AHMET BAYLAR; TAMER BAGATUR; AHMET TUNA

206

Culture of Penaeus monodon in a recirculating system  

Microsoft Academic Search

In this decade, the production of Penaeus monodon using the traditional open pond method decreased seriously due to disease that spread via seawater. In order to prevent the introduction of pathogenic micro-organisms from seawater, a recirculating system was constructed and tested in this study. This system includes culture tanks (CT), a lamella separator (LS), an aeration tank (AT), a submerged

Kuo-Feng Tseng; Huei-Meei Su; Mao-Sun Su

1998-01-01

207

In-Situ Leachate Management in a Tropical Landfill by Storage and Recirculation Operation Techniques  

Microsoft Academic Search

This paper presents the application of storage and recirculation techniques to leachate management in tropical climate. Four pilot-scale landfill lysimeters were operated under different operational mode, i.e. 1) conventional landfill operation (control) 2) leachate re- circulation 3) internal storage with recirculation and 4) internal storage without recirculation. The experiment was carried out to quantify the amount and characteristics of leachate

Chart Chiemchaisri; Wilai Chiemchaisri; Salinee Sittichoktum; Taweesak Tantichanthakarun; Sunya Tangsri

208

Simulating Large-Scale Earthquake Dynamic Rupture Scenarios On Natural Fault Zones Using the ADER-DG Method  

NASA Astrophysics Data System (ADS)

In this presentation we will demonstrate the benefits of using modern numerical methods to support physic-based ground motion modeling and research. For this purpose, we utilize SeisSol an arbitrary high-order derivative Discontinuous Galerkin (ADER-DG) scheme to solve the spontaneous rupture problem with high-order accuracy in space and time using three-dimensional unstructured tetrahedral meshes. We recently verified the method in various advanced test cases of the 'SCEC/USGS Dynamic Earthquake Rupture Code Verification Exercise' benchmark suite, including branching and dipping fault systems, heterogeneous background stresses, bi-material faults and rate-and-state friction constitutive formulations. Now, we study the dynamic rupture process using 3D meshes of fault systems constructed from geological and geophysical constraints, such as high-resolution topography, 3D velocity models and fault geometries. Our starting point is a large scale earthquake dynamic rupture scenario based on the 1994 Northridge blind thrust event in Southern California. Starting from this well documented and extensively studied event, we intend to understand the ground-motion, including the relevant high frequency content, generated from complex fault systems and its variation arising from various physical constraints. For example, our results imply that the Northridge fault geometry favors a pulse-like rupture behavior.

Gabriel, Alice; Pelties, Christian

2014-05-01

209

A search for evidence of large body Earth impacts associated with biological crisis zones in the fossil record  

NASA Technical Reports Server (NTRS)

The natural history of the Earth, how the present plant and animal species developed, how others completely died out, etc., was studied. The rock strata sampled and studied were at the time of deposition at sea bottom. It was found that, exactly at the stratigraphic level corresponding to the extinction, a thin clay layer was greatly enriched in the the rare element iridium. It was hypothesized that the excess irridium at the boundary came from a large steroid like object that hit the earth, and that the impact of this object threw up a dust cloud dense enough and long lasting enough to bring about the extinction of a wide variety of plants and animals, producing the unique break in in the fossil record, the cretaceous-tertiary boundary. The same iridium and platinum metals enrichement are found in a thin clay layer that corresponds with the boundary as difined by sudden radical changes in plant populations. The irridium enrichement is confirmed at other fresh water origin rites in the Raton Basin.

Orth, C. J.; Gilmore, J. S.; Knight, J. D.

1985-01-01

210

The species-specific structure of microanatomical compartments in the human spleen: strongly sialoadhesin-positive macrophages occur in the perifollicular zone, but not in the marginal zone.  

PubMed Central

The microanatomical structure of human and rat splenic white pulp is compared, with special emphasis on the localization of the marginal zone occupied by immunoglobulin M (IgM)+ IgD-/dull B lymphocytes and its specialized macrophages. Our study reveals that in contrast to rats, the marginal zone of humans primarily exists in the vicinity of primary and secondary splenic follicles and that it is almost absent around the periarteriolar T-cell zones. We demonstrate that in humans there is an additional compartment, the perifollicular zone, located between the marginal zone and the red pulp. The perifollicular zone is a dynamic region of variable cellular and phenotypic composition, which can be regarded either as a part of the red pulp or of the follicles. In most cases the perifollicular zone appears as a compartment of the red pulp containing erythrocyte-filled spaces which differ from the typical red pulp sinusoids. Similar to the splenic cords, the perifollicular zone mostly harbours scattered B and T lymphocytes. However, sometimes B lymphocytes clearly predominate in the perifollicular area. In addition, strongly sialoadhesin-positive macrophages form sheaths around capillaries in the perifollicular zone. Such capillary sheaths are not observed in rats. In humans weakly sialoadhesin-positive macrophages are also present in the perifollicular zone and in the red pulp. In some specimens sialoadhesin is, however, strongly expressed by a large number of dispersed perifollicular macrophages. Interestingly, in striking contrast to rats, the human marginal zone does not contain sialoadhesin-positive macrophages and marginal metallophilic macrophages are also absent in humans. Thus, sialoadhesin-positive macrophages and IgM+ IgD- memory B lymphocytes both share the marginal zone as a common compartment in rats, while they occupy different compartments in humans. We show that the human splenic marginal zone does not contain a marginal sinus and assume that in humans the perifollicular region is the compartment where antigen and recirculating lymphocytes enter the organ. Images Figure 1 Figure 2 Figure 3 PMID:9415041

Steiniger, B; Barth, P; Herbst, B; Hartnell, A; Crocker, P R

1997-01-01

211

Radiocarbon and geochemical constraints on shallow groundwater recharge in a large arid zone river, Cooper Creek, SW Queensland, Australia  

NASA Astrophysics Data System (ADS)

In the arid and semi-arid internally drained Lake Eyre Basin of central Australia, large mud dominated anabranching river systems transport monsoon derived floodwaters into the centre of the continent during the summer months, and subsequently spend much of the year under low to no flow conditions. Cooper Creek has the largest catchment in this basin, and in south west Queensland has a wide (20-60km) floodplain and multiple channel system. Enlarged channel segments, known as waterholes or billabongs, can retain water throughout much of the dry season, and their mud base can often be scoured during floods into the underlying sandy alluvium where the shallow groundwater table exists ~3-5m below the base of the waterholes. Little is known of the groundwater recharge mechanisms in this ecologically important and hydrologically unregulated river system, thus a number of piezometer transects were construct across the floodplain between two waterholes to investigate groundwater recharge processes in further detail. Samples recovered from all piezometers were analysed for major-trace element, water stable isotopes (?2H and ?180), 3H and 14C. Water stable isotopes reveal shallow groundwater is recharged by high magnitude, low frequency monsoonal flood events, with minor evaporative enrichment probably linked to recent smaller flooding events. 14C dating of dissolved inorganic carbon reveals recharge is most effective beneath the deepest channel segments of the waterholes, and that residence time of the shallow groundwater increases with distance from major waterholes, with the post 1950's 14C bomb pulse signature present only in close proximity to the channels. 3H allows further refinement of the shallow groundwater residence times, with no 3H detected in groundwater over ~500m from the waterholes, indicating groundwater recharge is slow and restricted to major flooding events. The increase in groundwater residence time with distance from waterholes, is also accompanied by an abrupt increase in salinity, and suggests recent recharge has formed local freshwater lenses above the regional, more saline groundwater. This increase in salinity with increasing distance from the waterholes is not accompanied by an increase on the evaporative signal of water stable isotopes, suggesting evapotranspiration is the dominant mechanism of salinisation within the shallow groundwater beneath the floodplains and minor channels. This study demonstrates that detailed chemical analysis of groundwaters from arid and semi arid areas can provide a useful estimate of recharge where the remote location makes traditional detailed borehole monitoring difficult or impossible to achieve.

Larsen, Joshua; Cendón, Dioni; Nanson, Gerald; Jones, Brian

2010-05-01

212

Research on leachate recirculation from different types of landfills  

SciTech Connect

Landfills can produce a great amount of leachate containing highly concentrated organic matter. This is especially true for the initial leachate from landfilled municipal solid wastes (MSW) that generally has concentrations of COD{sub Cr} and BOD{sub 5} up to 80,000 and 50,000 mg/L, respectively. The leachate could be disposed by means of recirculating technique, which decomposes the organics through the action of proliferating microorganisms and thereby purifies the leachate, and simultaneously accelerates organic decomposition through water saturation control. Data from experimental results indicated that leachate recirculating could reduce the organic concentration considerably, with a maximum reduction rate of COD{sub Cr} over 95%; and, using a semi-aerobic process, NH{sub 3}-N concentration of treated leachate could be under 10 mg/L. In addition, the organic concentration in MSW decreased greatly.

Wang Qi [Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, No. 8 of Dayangfang, Chaoyang District, Beijing 100012 (China) and Faculty of Engineering, Fukuoka University, 8-19-1 Nanakuma, Johnan-ku, Fukuoka 814-0180 (Japan)]. E-mail: wangqi@craes.org.cn; Matsufuji, Yasushi [Faculty of Engineering, Fukuoka University, 8-19-1 Nanakuma, Johnan-ku, Fukuoka 814-0180 (Japan); Dong Lu [Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, No. 8 of Dayangfang, Chaoyang District, Beijing 100012 (China); Huang Qifei [Research Institute of Solid Waste Management, Chinese Research Academy of Environmental Sciences, No. 8 of Dayangfang, Chaoyang District, Beijing 100012 (China); Hirano, Fumiaki [Faculty of Engineering, Fukuoka University, 8-19-1 Nanakuma, Johnan-ku, Fukuoka 814-0180 (Japan); Tanaka, Ayako [Faculty of Engineering, Fukuoka University, 8-19-1 Nanakuma, Johnan-ku, Fukuoka 814-0180 (Japan)

2006-07-01

213

Multiple-scale turbulence closure modeling of confined recirculating flows  

NASA Technical Reports Server (NTRS)

A multiple-scale turbulence closure scheme is developed for the numerical predictions of confined recirculating flows. This model is based on the multiple-time-scale concepts of Hanjalic et al. (1980) and takes into account the non-equilibrium spectra energy transfer mechanism. Problems concerning new formulation of energy transfer rate equations and subsequent model coefficient redefinition and energy spectrum partition are discussed. Comparisons are made with several experiments of internal recirculating flows for the purpose of model validation. Numerical results using the present model show significant improvement of predictive capability over that obtained with the single-scale k-epsilon model and show promising potential for complex turbulent flow predictions.

Chen, C. P.

1985-01-01

214

Growth Performance of Walleye, Sander vitreus, in Recirculating Aquaculture Systems  

Microsoft Academic Search

Walleye, Sander vitreus, fingerlings were reared in two recirculating aquaculture systems (RAS) to compare growth performance at three stocking densities (11, 24, and 36 kg\\/m). There was a negative relationship between increasing stocking density and growth calculated as percent body weight (BW) gain\\/day, total length (mm) gain\\/day, specific growth rate (SGR) of weight (%\\/day), and SGR of total length (%\\/day).

Chester B. Zarnoch; Martin P. Schreibman; Richard T. Colesante; Michael B. Timmons

2010-01-01

215

Recirculation of Factory Heat and Air to Reduce Energy Consumption  

E-print Network

the recirculating "air turnover" flow pattern can serve as the most practical means of transporting contaminants from above the workspace into an appropriate air clean er. (This is particularly likely for the case of welding fumes in wide span high bay... if sensible heat alone were recovered (as happens in most conventional heat exchanger in stallations) . BACKGROUND Traditional exhausting of non-toxic contaminants such as oil mist or welding smoke from manufactur ing areas causes a substantial increase...

Thiel, G. R.

1983-01-01

216

Closed recirculating system for shrimp-mollusk polyculture  

Microsoft Academic Search

This paper deals with a new system of aquaculture, i.e., a closed recirculating system for shrimp-mollusk polyculture. The\\u000a culture system consisted of several shrimp ponds, a mollusk water-purifying pond and a reservoir. During the production cycle,\\u000a water circulated between the shrimp and mollusk ponds, and the reservoir compensated for water loss from seepage and evaporation.\\u000a Constricted tagelus,Sinonovacula constricta, was selected

Xiongfei Wu; Zhidong Zhao; Deshang Li; Kangmei Chang; Zhuanshang Tong; Liegang Si; Kaichong Xu; Bailin Ge

2005-01-01

217

A recirculating linac-based facility for ultrafast X-ray science  

SciTech Connect

We present an updated design for a proposed source of ultra-fast synchrotron radiation pulses based on a recirculating superconducting linac, in particular the incorporation of EUV and soft x-ray production. The project has been named LUX - Linac-based Ultrafast X-ray facility. The source produces intense x-ray pulses with duration of 10-100 fs at a 10 kHz repetition rate, with synchronization of 10 s fs, optimized for the study of ultra-fast dynamics. The photon range covers the EUV to hard x-ray spectrum by use of seeded harmonic generation in undulators, and a specialized technique for ultra-short-pulse photon production in the 1-10 keV range. High-brightness rf photocathodes produce electron bunches which are optimized either for coherent emission in free-electron lasers, or to provide a large x/y emittance ration and small vertical emittance which allows for manipulation to produce short-pulse hard x-rays. An injector linac accelerates the beam to 120 MeV, and is followed by four passes through a 600-720 MeV recirculating linac. We outline the major technical components of the proposed facility.

Corlett, J.N; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Green, M.A.; Heimann, P.; Leone, S.; Lidia, S.; Li, D.; Ratti, A.; Robinson, K.; Schoenlein, R.; Staples, J.; Wan, W.; Wells, R.; Wolski, A.; Zholents, A.; Placidi, M.; Pirkl, W.; Parmigiani, F.

2003-05-06

218

Cyclone reactor with internal separation and axial recirculation  

DOEpatents

A cyclone combustor apparatus contains a circular partition plate containing a central circular aperture is described. The partition plate divides the apparatus into a cylindrical precombustor chamber and a combustor chamber. A coal-water slurry is passed axially into the inlet end of the precombustor chamber, and primary air is passed tangentially into said chamber to establish a cyclonic air flow. Combustion products pass through the partition plate aperture and into the combustor chamber. Secondary air may also be passed tangentially into the combustor chamber adjacent the partition plate to maintain the cyclonic flow. Flue gas is passed axially out of the combustor chamber at the outlet end and ash is withdrawn tangentially from the combustor chamber at the outlet end. A first mixture of flue gas and ash may be tangentially withdrawn from the combustor chamber at the outlet end and recirculated to the axial inlet of the precombustor chamber with the coal-water slurry. A second mixture may be tangentially withdrawn from the outlet end and passed to a heat exchanger for cooling. Cooled second mixture is then recirculated to the axial inlet of the precombustor chamber. In another embodiment a single cyclone combustor chamber is provided with both the recirculation streams of the first mixture and the second mixture. 10 figs.

Becker, F.E.; Smolensky, L.A.

1988-07-19

219

Cyclone reactor with internal separation and axial recirculation  

DOEpatents

A cyclone combustor apparatus contains a circular partition plate containing a central circular aperture. The partition plate divides the apparatus into a cylindrical precombustor chamber and a combustor chamber. A coal-water slurry is passed axially into the inlet end of the precombustor chamber, and primary air is passed tangentially into said chamber to establish a cyclonic air flow. Combustion products pass through the partition plate aperture and into the combustor chamber. Secondary air may also be passed tangentially into the combustor chamber adjacent the partition plate to maintain the cyclonic flow. Flue gas is passed axially out of the combustor chamber at the outlet end and ash is withdrawn tangentially from the combuston chamber at the outlet end. A first mixture of flue gas and ash may be tangentially withdrawn from the combustor chamber at the outlet end and recirculated to the axial inlet of the precombustor chamber with the coal-water slurry. A second mixture of flue gas and ash may be tangentially withdrawn from the outlet end of the combustor chamber and passed to a heat exchanger for cooling. Cooled second mixture is then recirculated to the axial inlet of the precombustor chamber. In another embodiment a single cyclone combustor chamber is provided with both the recirculation streams of the first mixture and the second mixture.

Becker, Frederick E. (Reading, MA); Smolensky, Leo A. (Concord, MA)

1989-01-01

220

Displacement of large-scale open solar magnetic fields from the zone of active longitudes and the heliospheric storm of November 3-10, 2004: 2. "Explosion" of singularity and dynamics of sunspot formation and energy release  

NASA Astrophysics Data System (ADS)

A more detailed scenario of one stage (August-November 2004) of the quasibiennial MHD process "Origination ... and dissipation of the four-sector structure of the solar magnetic field" during the decline phase of cycle 23 has been constructed. It has been indicated that the following working hypothesis on the propagation of an MHD disturbance westward (in the direction of solar rotation) and eastward (toward the zone of active longitudes) with the displacement of the large-scale open solar magnetic field (LOSMF) from this zone can be constructed based on LOSMF model representations and data on sunspot formation, flares, active filaments, and coronal ejections as well as on the estimated contribution of sporadic energy release to the flare luminosity and kinetic energy of ejections: (1) The "explosion" of the LOSMF singularity and the formation in the explosion zone of an anemone active region (AR), which produced the satellite sunspot formation that continued west and east of the "anemone," represented a powerful and energy-intensive source of MHD processes at this stage. (2) This resulted in the origination of two "governing" large-scale MHD processes, which regulated various usual manifestations of solar activity: the fast LOSMF along the neutral line in the solar atmosphere, strongly affecting the zone of active longitudes, and the slow LOSMF in the outer layers of the convection zone. The fronts of these processes were identified by powerful (about 1031 erg) coronal ejections. (3) The collision of a wave reflected from the zone of active longitudes with the eastern front of the hydromagnetic impulse of the convection zone resulted in an increase in LOSMF magnetic fluxes, origination of an active sector boundary in the zone of active longitudes, shear-convergent motions, and generation and destabilization of the flare-productive AR 10696 responsible for the heliospheric storm of November 3-10, 2004.

Ivanov, K. G.

2010-12-01

221

Recirculation of Laser Power in an Atomic Fountain  

NASA Technical Reports Server (NTRS)

A new technique for laser-cooling atoms in a cesium atomic fountain frequency standard relies on recirculation of laser light through the atom-collection region of the fountain. The recirculation, accomplished by means of reflections from multiple fixed beam-splitter cubes, is such that each of two laser beams makes three passes. As described below, this recirculation scheme offers several advantages over prior designs, including simplification of the laser system, greater optical power throughput, fewer optical and electrical connections, and simplification of beam power balancing. A typical laser-cooled cesium fountain requires the use of six laser beams arranged as three orthogonal pairs of counter-propagating beams to decelerate the atoms and hold them in a three-dimensional optical trap in vacuum. Typically, these trapping/cooling beams are linearly polarized and are positioned and oriented so that (1) counter-propagating beams in each pair have opposite linear polarizations and (2) three of the six orthogonal beams have the sum of their propagation directions pointing up, while the other three have the sum of their propagation directions pointing down. In a typical prior design, two lasers are used - one to generate the three "up" beams, the other to generate the three "down" beams. For this purpose, the output of each laser is split three ways, then the resulting six beams are delivered to the vacuum system, independently of each other, via optical fibers. The present recirculating design also requires two lasers, but the beams are not split before delivery. Instead, only one "up" beam and one oppositely polarized "down" beam are delivered to the vacuum system, and each of these beams is sent through the collection region three times. The polarization of each beam on each pass through the collection region is set up to yield the same combination of polarization and propagation directions as described above. In comparison with the prior design, the present recirculating design utilizes the available laser light more efficiently, making it possible to trap more atoms at a given laser power or the same number of atoms at a lower laser power. The present design is also simpler in that it requires fewer optical fibers, fiber couplings, and collimators, and fewer photodiodes for monitoring beam powers. Additionally, the present design alleviates the difficulty of maintaining constant ratios among power levels of the beams within each "up" or "down" triplet.

Enzer, Daphna G.; Klipstein, WIlliam M.; Moore, James D.

2007-01-01

222

Laminar mixing in a small floating zone  

NASA Technical Reports Server (NTRS)

The relationship between the flow and solute fields during steady mass transfer of a dilute component is analyzed for multi-cellular rotating flows in the floating zone process of semiconductor growth. When the recirculating flows are weak in relation to the rate of crystal growth, a closed-form solution clearly shows the link between the convection pattern in the melt and the solute distribution across the surface of the growing solid. In the limit of strong convection, finite element calculations demonstrate the tendency of the composition to become uniform over the majority of the melt. The solute segregation in the product crystal is greatest when the recirculating motion is comparable to the rate of crystal growth, and points to the danger in attempting to grow compositionally uniform materials from a nearly convectionless melt.

Harriott, George M.

1987-01-01

223

Paleoseismology of the Nephi Segment of the Wasatch Fault Zone, Juab County, Utah - Preliminary Results From Two Large Exploratory Trenches at Willow Creek  

USGS Publications Warehouse

In 2004, we identified a small parcel of U.S. Forest Service land at the mouth of Willow Creek (about 5 km west of Mona, Utah) that was suitable for trenching. At the Willow Creek site, which is near the middle of the southern strand of the Nephi segment, the WFZ has vertically displaced alluvial-fan deposits >6-7 m, forming large, steep, multiple-event scarps. In May 2005, we dug two 4- to 5-m-deep backhoe trenches at the Willow Creek site, identified three colluvial wedges in each trench, and collected samples of charcoal and A-horizon organic material for AMS (acceleration mass spectrometry) radiocarbon dating, and sampled fine-grained eolian and colluvial sediment for luminescence dating. The trenches yielded a stratigraphic assemblage composed of moderately coarse-grained fluvial and debris-flow deposits and discrete colluvial wedges associated with three faulting events (P1, P2, and P3). About one-half of the net vertical displacement is accommodated by monoclinal tilting of fan deposits on the hanging-wall block, possibly related to massive ductile landslide deposits that are present beneath the Willow Creek fan. The timing of the three surface-faulting events is bracketed by radiocarbon dates and results in a much different fault chronology and higher slip rates than previously considered for this segment of the Wasatch fault zone.

Machette, Michael N.; Crone, Anthony J.; Personius, Stephen F.; Mahan, Shannon A.; Dart, Richard L.; Lidke, David J.; Olig, Susan S.

2007-01-01

224

Large-scale separation of antipsychotic alkaloids from Rauwolfia tetraphylla L. by pH-zone-refining fast centrifugal partition chromatography.  

PubMed

pH-zone-refining centrifugal partition chromatography was successively applied in the large-scale separation of close R(f) antipsychotic indole alkaloids directly from CHCl(3) fraction of Rauwolfia tetraphylla leaves. Two experiments with increasing mass from 500 mg to 3 g of crude alkaloid extracts (1C) of R. tetraphylla were carried out in normal-displacement mode using a two-phase solvent system composed of methyl tert-butyl ether/ACN/water (4:1:5, v/v/v) where HCl (12 mM) was added to the lower aqueous stationary phase as a retainer and triethylamine (5 mM) to the organic mobile phase as an eluter. The two centrifugal partition chromatography separations afforded a total of 162.6 mg of 10-methoxytetrahydroalstonine (1) and 296.5 mg of isoreserpiline (2) in 97% and 95.5% purity, respectively, along with a 400.9 mg mixture of ?-yohimbine and reserpiline (3 and 4). Further, this mixture was resolved over medium pressure LC using TLC grade silica gel H (average particle size 10 ?m), which afforded 160.4 mg of ?-yohimbine (3) and 150.2 mg of reserpiline (4) in >95% purities. The purity of the isolated antipsychotic alkaloids was analyzed by high-performance LC and their structures were characterized on the basis of their 1D, 2D NMR and electrospray ionization-mass spectroscopic data. PMID:23335460

Maurya, Anupam; Gupta, Shikha; Srivastava, Santosh K

2013-01-01

225

Holocene behavior of the Brigham City segment: implications for forecasting the next large-magnitude earthquake on the Wasatch fault zone, Utah  

USGS Publications Warehouse

The Brigham City segment (BCS), the northernmost Holocene?active segment of the Wasatch fault zone (WFZ), is considered a likely location for the next big earthquake in northern Utah. We refine the timing of the last four surface?rupturing (~Mw 7) earthquakes at several sites near Brigham City (BE1, 2430±250; BE2, 3490±180; BE3, 4510±530; and BE4, 5610±650 cal yr B.P.) and calculate mean recurrence intervals (1060–1500??yr) that are greatly exceeded by the elapsed time (~2500??yr) since the most recent surface?rupturing earthquake (MRE). An additional rupture observed at the Pearsons Canyon site (PC1, 1240±50 cal yr B.P.) near the southern segment boundary is probably spillover rupture from a large earthquake on the adjacent Weber segment. Our seismic moment calculations show that the PC1 rupture reduced accumulated moment on the BCS about 22%, a value that may have been enough to postpone the next large earthquake. However, our calculations suggest that the segment currently has accumulated more than twice the moment accumulated in the three previous earthquake cycles, so we suspect that additional interactions with the adjacent Weber segment contributed to the long elapse time since the MRE on the BCS. Our moment calculations indicate that the next earthquake is not only overdue, but could be larger than the previous four earthquakes. Displacement data show higher rates of latest Quaternary slip (~1.3??mm/yr) along the southern two?thirds of the segment. The northern third likely has experienced fewer or smaller ruptures, which suggests to us that most earthquakes initiate at the southern segment boundary.

Personius, Stephen F.; DuRoss, Christopher B.; Crone, Anthony J.

2012-01-01

226

Demonstration of a Highly Efficient Solid Oxide Fuel Cell Power System Using Adiabatic Steam Reforming and Anode Gas Recirculation  

SciTech Connect

Solid oxide fuel cells (SOFC) are currently being developed for a wide variety of applications because of their high efficiency at multiple power levels. Applications for SOFCs encompass a large range of power levels including 1-2 kW residential combined heat and power applications, 100-250 kW sized systems for distributed generation and grid extension, and MW-scale power plants utilizing coal. This paper reports on the development of a highly efficient, small-scale SOFC power system operating on methane. The system uses adiabatic steam reforming of methane and anode gas recirculation to achieve high net electrical efficiency. The anode exit gas is recirculated and all of the heat and water required for the endothermic reforming reaction are provided by the anode gas emerging from the SOFC stack. Although the single-pass fuel utilization is only about 55%, because of the anode gas recirculation the overall fuel utilization is up to 93%. The demonstrated system achieved gross power output of 1650 to 2150 watts with a maximum net LHV efficiency of 56.7% at 1720 watts. Overall system efficiency could be further improved to over 60% with use of properly sized blowers.

Powell, Michael R.; Meinhardt, Kerry D.; Sprenkle, Vincent L.; Chick, Lawrence A.; Mcvay, Gary L.

2012-05-01

227

Investigation of groundwater recirculation for the removal of RDX from the Pantex Plant perched aquifer  

SciTech Connect

The Pantex Plant near Amarillo, Texas, is a US Department of Energy (DOE) facility that has been in operation since 1942. Past and present operations at Pantex include the creation of chemical high explosives components for nuclear weapons and assembly and disassembly of nuclear weapons. The Pantex Plant is underlain by the Ogallala aquifer, which in this area, consists of the main water-bearing unit and a perched water zone. These are separated by a fine-grained zone of low permeability. Multiple contaminant plumes containing high explosive (HE) compounds have been detected in the perched aquifer beneath the plant. The occurrence of these contaminants is the result of past waste disposal practices at the facility. RDX is an HE compound, which has been detected in the groundwater of the perched aquifer at significant concentrations. A pilot-scale, dual-phase extraction treatment system has been installed at one location at the plant, east of Zone 12, to test the effectiveness of such a system on the removal of these contaminants from the subsurface. A tracer test using a conservative tracer, bromide (Br), was conducted at the treatment site in 1996. In addition to the bromide, RDX and water elevations in the aquifer were monitored. Using data from the tracer test and other relevant data from the investigations at Pantex, flow and contaminant transport in the perched aquifer were simulated with groundwater models. The flow was modeled using MODFLOW and the transport of contaminants in the aqueous phase was modeled using MT3D. Modeling the perched aquifer had been conducted to characterize the flow in the perched aquifer; estimate RDX retardation in the perched aquifer; and evaluate the use of groundwater re-circulation to enhance the extraction of RDX from the perched aquifer.

Woods, A.L. [ed.; Barnes, D.L. [Amarillo National Resource Center for Plutonium, TX (United States); Boles, K.M.; Charbeneau, R.J. [Univ. of Texas, Austin, TX (United States); Black, S.; Rainwater, K. [Texas Tech Univ., Lubbock, TX (United States). Water Resources Center

1998-07-01

228

Influence of leachate recirculation on aerobic and anaerobic decomposition of solid wastes  

Microsoft Academic Search

In this study, the effect of leachate recirculation on aerobic and anaerobic degradation of municipal solid wastes is determined by four laboratory-scale landfill reactors. The options studied and compared with the traditional anaerobic landfill are: leachate recirculation, landfill aeration, and aeration with leachate recirculation. Leachate quality is regularly monitored by the means of pH, alkalinity, total dissolved solids, conductivity, oxidation–reduction

M. Sinan Bilgili; Ahmet Demir; Bestamin Özkaya

2007-01-01

229

Method and apparatus for affecting a recirculation zone in a cross flow  

SciTech Connect

Disclosed is a cross flow apparatus including a surface and at least one outlet located at the surface. The cross flow apparatus further includes at least one guide at the surface configured to direct an intersecting flow flowing across the surface and increase a velocity of a cross flow being expelled from the at least one outlet downstream from the at least one outlet.

Bathina, Mahesh (Andhra Pradesh, IN); Singh, Ramanand (Uttar Pradesh, IN)

2012-07-17

230

Recirculation-aeration: Bibliography for aquaculture. Bibliographies and literature of agriculture (Final)  

Microsoft Academic Search

The bibliography includes literature citations through 1992 related to water recirculation and aeration in aquaculture. The focus is on filtration, aeration, and circulation techniques in various aquaculture situations.

P. W. Perschbacher; R. V. Powell; D. W. Freeman; W. J. Lorio; D. T. Hanfman

1993-01-01

231

Recirculation-aeration: Bibliography for aquaculture. Bibliographies and literature of agriculture (Final)  

SciTech Connect

The bibliography includes literature citations through 1992 related to water recirculation and aeration in aquaculture. The focus is on filtration, aeration, and circulation techniques in various aquaculture situations.

Perschbacher, P.W.; Powell, R.V.; Freeman, D.W.; Lorio, W.J.; Hanfman, D.T.

1993-08-01

232

On part load recirculation of pumps and fans-a generic study  

NASA Astrophysics Data System (ADS)

At part load in turbo machinery, there is a boundary layer separation resulting in a large vortex structure called part load recirculation. Up to now the influence of Reynolds number, relative roughness and degree of turbulence on this important stability limit of machines is not sufficiently understood. To shed some light onto these phenomena, in this work the simplest "machine" is considered by numerical and experimental studies. The apparatus we examine is a circular pipe at rest followed by a rotating co-axial pipe segment. By doing so, we have a generic test case which serves to study the critical flow number, defined by the onset of the separation and formation of a ring vortex.

Stapp, D.; Pelz, P. F.; Loens, J. M.

2013-12-01

233

Lymphopoiesis and lymphocyte recirculation in the sheep fetus  

PubMed Central

The production and the circulation of lymphocytes has been examined in the sheep fetus where neither foreign antigen nor immunoglobulins occur. It was found that as the lymphoid organs increased in size during fetal life, the numbers and the output of lymphocytes in the thoracic duct lymph increased. The recirculating pool of lymphocytes was estimated to be 5.5 +/- 1.5 X 10(8) cells in fetal lambs 95-100 days of age, 5.7 +/- 1.2 X 10(9) cells in fetuses 130-135 days of age, and 1.2 +/0 9.3 X 10(10) cells in fetuses near to term. The rate of addition of lymphocytes to the recirculating pool was 3.2 +/- 1.9 X 10(6) cells/h in fetuses of 100 days and 3.4 +/- 0.9 X 10(7) cells/h in fetuses of 130 days of age. Lymphocytes recirculated from blood to lymph in fetuses; labeled cells injected into the blood stream reappeared in the thoracic duct lymph promptly and reached maximum levels around 12-18 h after they were injected. Labeled lymphocytes were detected subsequently in greatest numbers in the lymph nodes, particularly in the mesenteric lymph nodes and in the interfollicular areas of the Peyer's patches. Chronic drainage of thoracic duct lymph from fetuses in utero for periods of up to 36 days had no obvious effects on the growth or development of the fetus and only minimal effects on the content of lymphocytes in the various lymphoid tissues even though the number of cells in the blood and lymph were reduced to between 20-30% of normal levels. Thymectomy done in fetuses about 2 mo befor cannulation of the thoracic duct reduced the output of cells in the thoracic duct to about 25% of normal levels and caused a significant reduction in the content of lymphocytes in the various lymphoid tissues. Thymectomized fetal lambs subjected to thoracic duct drainage for periods up to 2 wk in utero had a similar complement of lymphocytes in their lymphoid tissues to intact thymectomized fetal lambs. Lymphocytes obtained from the thoracic duct lymph of lambs thymectomized 2 mo previously recirculated from blood to lymph when they were injected intravenously, although they did this at a significantly slower rate than did lymphocytes from normal lambs. PMID:1244417

1976-01-01

234

Power plant including an exhaust gas recirculation system for injecting recirculated exhaust gases in the fuel and compressed air of a gas turbine engine  

DOEpatents

A power plant is provided and includes a gas turbine engine having a combustor in which compressed gas and fuel are mixed and combusted, first and second supply lines respectively coupled to the combustor and respectively configured to supply the compressed gas and the fuel to the combustor and an exhaust gas recirculation (EGR) system to re-circulate exhaust gas produced by the gas turbine engine toward the combustor. The EGR system is coupled to the first and second supply lines and configured to combine first and second portions of the re-circulated exhaust gas with the compressed gas and the fuel at the first and second supply lines, respectively.

Anand, Ashok Kumar; Nagarjuna Reddy, Thirumala Reddy; Shaffer, Jason Brian; York, William David

2014-05-13

235

Investigation of the Impact of the Upstream Induction Zone on LIDAR Measurement Accuracy for Wind Turbine Control Applications using Large-Eddy Simulation  

NASA Astrophysics Data System (ADS)

Several sources of error exist in lidar measurements for feedforward control of wind turbines including the ability to detect only radial velocities, spatial averaging, and wind evolution. This paper investigates another potential source of error: the upstream induction zone. The induction zone can directly affect lidar measurements and presents an opportunity for further decorrelation between upstream wind and the wind that interacts with the rotor. The impact of the induction zone is investigated using the combined CFD and aeroelastic code SOWFA. Lidar measurements are simulated upstream of a 5 MW turbine rotor and the true wind disturbances are found using a wind speed estimator and turbine outputs. Lidar performance in the absence of an induction zone is determined by simulating lidar measurements and the turbine response using the aeroelastic code FAST with wind inputs taken far upstream of the original turbine location in the SOWFA wind field. Results indicate that while measurement quality strongly depends on the amount of wind evolution, the induction zone has little effect. However, the optimal lidar preview distance and circular scan radius change slightly due to the presence of the induction zone.

Simley, Eric; Y Pao, Lucy; Gebraad, Pieter; Churchfield, Matthew

2014-06-01

236

Self-Recirculating Casing Treatment Concept for Enhanced Compressor Performance  

NASA Technical Reports Server (NTRS)

A state-of-the-art CFD code (APNASA) was employed in a computationally based investigation of the impact of casing bleed and injection on the stability and performance of a moderate speed fan rotor wherein the stalling mass flow is controlled by tip flow field breakdown. The investigation was guided by observed trends in endwall flow characteristics (e.g., increasing endwall aerodynamic blockage) as stall is approached and based on the hypothesis that application of bleed or injection can mitigate these trends. The "best" bleed and injection configurations were then combined to yield a self-recirculating casing treatment concept. The results of this investigation yielded: 1) identification of the fluid mechanisms which precipitate stall of tip critical blade rows, and 2) an approach to recirculated casing treatment which results in increased compressor stall range with minimal or no loss in efficiency. Subsequent application of this approach to a high speed transonic rotor successfully yielded significant improvements in stall range with no loss in compressor efficiency.

Hathaway, Michael D.

2002-01-01

237

Passive mode control in the recirculating planar magnetron  

SciTech Connect

Preliminary experiments of the recirculating planar magnetron microwave source have demonstrated that the device oscillates but is susceptible to intense mode competition due, in part, to poor coupling of RF fields between the two planar oscillators. A novel method of improving the cross-oscillator coupling has been simulated in the periodically slotted mode control cathode (MCC). The MCC, as opposed to a solid conductor, is designed to electromagnetically couple both planar oscillators by allowing for the propagation of RF fields and electrons through resonantly tuned gaps in the cathode. Using the MCC, a 12-cavity anode block with a simulated 1 GHz and 0.26 c phase velocity (where c is the speed of light) was able to achieve in-phase oscillations between the two sides of the device in as little as 30 ns. An analytic study of the modified resonant structure predicts the MCC's ability to direct the RF fields to provide tunable mode separation in the recirculating planar magnetron. The self-consistent solution is presented for both the degenerate even (in phase) and odd (180 Degree-Sign out of phase) modes that exist due to the twofold symmetry of the planar magnetrons.

Franzi, Matthew; Gilgenbach, Ronald; Lau, Y. Y.; Greening, Geoff; Zhang, Peng [Plasma, Pulsed Power, and Microwave Laboratory, Nuclear Engineering and Radiological Sciences Department, University of Michigan, Ann Arbor, Michigan 48109-2104 (United States); Hoff, Brad [Air Force Research Laboratory, Kirtland AFB, New Mexico 87117 (United States)

2013-03-15

238

Numerical Model of Turbulence, Sediment Transport, and Sediment Cover in a Large Canyon-Bound River  

NASA Astrophysics Data System (ADS)

The Colorado River in Grand Canyon is confined by bedrock and coarse-grained sediments. Finer grain sizes are supply limited, and sandbars primarily occur in lateral separation eddies downstream of coarse-grained tributary debris fans. These sandbars are important resources for native fish, recreational boaters, and as a source of aeolian transport preventing the erosion of archaeological resources by gully extension. Relatively accurate prediction of deposition and, especially, erosion of these sandbar beaches has proven difficult using two- and three-dimensional, time-averaged morphodynamic models. We present a parallelized, three-dimensional, turbulence-resolving model using the Detached-Eddy Simulation (DES) technique. DES is a hybrid large eddy simulation (LES) and Reynolds-averaged Navier Stokes (RANS). RANS is applied to the near-bed grid cells, where grid resolution is not sufficient to fully resolve wall turbulence. LES is applied further from the bed and banks. We utilize the Spalart-Allmaras one equation turbulence closure with a rough wall extension. The model resolves large-scale turbulence using DES and simultaneously integrates the suspended sediment advection-diffusion equation. The Smith and McLean suspended sediment boundary condition is used to calculate the upward and downward settling of sediment fluxes in the grid cells attached to the bed. The model calculates the entrainment of five grain sizes at every time step using a mixing layer model. Where the mixing layer depth becomes zero, the net entrainment is zero or negative. As such, the model is able to predict the exposure and burial of bedrock and coarse-grained surfaces by fine-grained sediments. A separate program was written to automatically construct the computational domain between the water surface and a triangulated surface of a digital elevation model of the given river reach. Model results compare favorably with ADCP measurements of flow taken on the Colorado River in Grand Canyon during the High Flow Experiment (HFE) of 2008. The model accurately reproduces the size and position of the major recirculation currents, and the error in velocity magnitude was found to be less than 17% or 0.22 m/s absolute error. The mean deviation of the direction of velocity with respect to the measured velocity was found to be 20 degrees. Large-scale turbulence structures with vorticity predominantly in the vertical direction are produced at the shear layer between the main channel and the separation zone. However, these structures rapidly become three-dimensional with no preferred orientation of vorticity. Surprisingly, cross-stream velocities, into the main recirculation zone just upstream of the point of reattachment and out of the main recirculation region just downstream of the point of separation, are highest near the bed. Lateral separation eddies are more efficient at storing and exporting sediment than previously modeled. The input of sediment to the eddy recirculation zone occurs near the reattachment zone and is relatively continuous in time. While, the export of sediment to the main channel by the return current occurs in pulses. Pulsation of the strength of the return current becomes a key factor to determine the rates of erosion and deposition in the main recirculation zone.

Alvarez, L. V.; Schmeeckle, M. W.

2013-12-01

239

Fish Health Management Considerations in Recirculating Aquaculture Systems -Part 2: Pathogens1  

E-print Network

Cir 121 Fish Health Management Considerations in Recirculating Aquaculture Systems - Part 2 Aquaculture Laboratory, Ruskin FL 33570, Program in Fisheries and Aquatic Sciences, School of Forest Resources Introduction Recirculating aquaculture systems, also known as water reuse systems, have become more and more

Watson, Craig A.

240

A recirculating equilibrium procedure for determining organic compound solubility in supercritical fluids. Anthracene in carbon dioxide  

Microsoft Academic Search

An instrumental recirculation technique was developed to measure the solubility of organic compounds and thus their potential extractability, in supercritical fluids over the pressure range of 80--500 bar. Anthracene, whose solubility is well defined, was chosen as a model compound to be used in evaluating the recirculation technique. Its solubility in supercritical carbon dioxide was measured at 40, 50, and

James W. Hampson

1996-01-01

241

Inactivation of bacteria using ultraviolet irradiation in a recirculating salmonid culture system  

Technology Transfer Automated Retrieval System (TEKTRAN)

The objective of this research was to determine the ultraviolet (UV) irradiation dosages required to inactivate bacteria in a commercial-scale recirculating salmonid culture system. Research was conducted in the commercial-scale recirculating system used for Arctic char growout at the Conservation ...

242

Apparatus for controlling the exhaust gas recirculation rate in an internal combustion engine  

Microsoft Academic Search

An apparatus is proposed for controlling the exhaust recirculation rate in an internal combustion engine, in particular an engine with auto-ignition, which includes preferably one mixture valve in the area of the discharge opening of the exhaust recirculation line and which is characterized in that the control is accomplished via the mixture valve position ahead of the inlet valves in

K. Muller; E. Linder; H. Maurer; F. Rieger

1984-01-01

243

Developments in recirculating systems for Arctic char culture in North America  

Microsoft Academic Search

Arctic char (Salvelinus alpinus) tolerate high-density culture conditions, have an excellent fillet yield, are amenable to niche marketing, and are suitable for production within super-intensive recirculating systems. Much of the North American production of Arctic char has been within recirculating systems, which can provide more optimum water temperatures for fish growth and can also overcome limitations created by a lack

Steven T. Summerfelt; Gary Wilton; David Roberts; Tina Rimmerd; Kari Fonkalsrud

2004-01-01

244

RECENT PROGRESS TOWARD A MUON RECIRCULATING LINEAR ACCELERATOR  

SciTech Connect

Both Neutrino Factories (NF) and Muon Colliders (MC) require very rapid acceleration due to the short lifetime of muons. After a capture and bunching section, a linac raises the energy to about 900 MeV, and is followed by one or more Recirculating Linear Accelerators (RLA), possibly followed by a Rapid Cycling Synchnotron (RCS) or Fixed-Field Alternating Gradient (FFAG) ring. A RLA reuses the expensive RF linac section for a number of passes at the price of having to deal with different energies within the same linac. Various techniques including pulsed focusing quadruopoles, beta frequency beating, and multipass arcs have been investigated via simulations to improve the performance and reduce the cost of such RLAs.

Slawomir Bogacz, Vasiliy Morozov, Yves Roblin, Kevin Beard

2012-07-01

245

Recirculation model for liquid flow in foam channels  

NASA Astrophysics Data System (ADS)

Although extensively studied in the past, drainage of aqueous foams still offers major unaddressed issues. Among them, the behaviour of foam films during drainage has great significance as the thickness of the films is known to control the Ostwald ripening in foams, which in turn impacts liquid drainage. We propose a model relating the films’ behavior to the liquid flow in foam channels. It is assumed that Marangoni-driven recirculation counterflows take place in the transitional region between the foam channel and the adjoining films, and the Gibbs elasticity is therefore introduced as a relevant parameter. The velocity of these counterflows is found to be proportional to the liquid velocity in the channel. The resulting channel permeability is determined and it is shown that Marangoni stresses do not contribute to rigidify the channel’s surfaces, in strong contrast with the drainage of horizontal thin liquid films. New experimental data are provided and support the proposed model. in here

Pitois, O.; Louvet, N.; Rouyer, F.

2009-09-01

246

Experiments With Recirculating Target for F-18 Production  

NASA Astrophysics Data System (ADS)

Approximately 10 ml of O-18 water was loaded in an apparatus containing a 5 ml storage vessel, pump, silver target attached to a cyclotron, filter, backpressure regulator, conductivity meter, several valves and ion exchange cartridges. The water was continuously pumped through the target during proton bombardment at a rate 5 ml/min. Continuous irradiation with beam current ranging from 10 to 50 uA was conducted while pressure, temperature and conductivity were continuously monitored. The results indicate that recirculating of the target water can increase production of F-18 in relation to consumed O-18 water material. It can also increase productivity by eliminating idle periods for re-filling the target. A backpressure regulator can precisely control target pressure. This method also allows for continuous monitoring of the target material temperature, pressure, conductivity and accumulated radioactivity. Results of these observations provide important information about target performance and physical processes taking place inside the target.

Kiselev, M. Y.

2003-08-01

247

Handheld recirculation system and customized media for microfluidic cell culture.  

PubMed

A palm-sized microfluidic recirculation system and customized media enable simplified long-term culture and imaging of cells. The combination of bare Braille display modules, a leveled monolithic surface for complete chip mounting, and a transparent heater improved portability, mechanical stability and optical accessibility. Modification of basal culture media with Leibovitz's L-15 medium enabled an incubator-free culture of carbonate-dependent cells by eliminating the need for exogenous carbon dioxide. This capability is demonstrated through time-lapse recording of proliferation of C2C12 myoblasts and MC3T3-E1 osteoblasts for over 2 weeks in ambient atmosphere without medium exchange. The method opens up new possibilities for portable cell culture and for long-term continuous visual monitoring of cells. PMID:16372083

Futai, Nobuyuki; Gu, Wei; Song, Jonathan W; Takayama, Shuichi

2006-01-01

248

Capture of CO2 From Recirculating Flue Gas Boilers  

SciTech Connect

The possible need for an economical method for the separation of CO2 from flue gas adds a new set of challenges to power plant design, construction, operation, and maintenance. Many of the new requirements of CO2 separation are similar in nature to those addressed by the mature chemical engineering processes used in petroleum refining and industrial chemical production. Chemical engineering processes are regularly used to separate heterogeneous vapors in processes such as the fractionation of hydrocarbons or the separation of the components of air. This paper addresses the application of chemical engineering processes to the mixtures of gases and vapors found in the flue gas of recirculating boilers. Adaptation of these techniques can lead to a reduction in the energy required to capture CO2.

Ochs, Thomas L.

2003-01-01

249

Experiments With Recirculating Target for F-18 Production  

SciTech Connect

Approximately 10 ml of O-18 water was loaded in an apparatus containing a 5 ml storage vessel, pump, silver target attached to a cyclotron, filter, backpressure regulator, conductivity meter, several valves and ion exchange cartridges. The water was continuously pumped through the target during proton bombardment at a rate 5 ml/min. Continuous irradiation with beam current ranging from 10 to 50 uA was conducted while pressure, temperature and conductivity were continuously monitored. The results indicate that recirculating of the target water can increase production of F-18 in relation to consumed O-18 water material. It can also increase productivity by eliminating idle periods for re-filling the target. A backpressure regulator can precisely control target pressure. This method also allows for continuous monitoring of the target material temperature, pressure, conductivity and accumulated radioactivity. Results of these observations provide important information about target performance and physical processes taking place inside the target.

Kiselev, M.Y. [Eastern Isotopes, Inc. Sterling, VA (United States)

2003-08-26

250

Traffic and proliferative responses of recirculating lymphocytes in fetal calves.  

PubMed Central

The thoracic duct or efferent prescapular duct was cannulated in four fetal calves aged 121-259 days post-conception. The duration of lymph flow ranged from 2 to 20 days and the mean flow rates sustained over these collection periods varied from 5.4 to 48.8 ml/hr. Lymphocyte output ranged from 4.4 x 10(6) cells/hr in thoracic duct lymph from a 121-day fetus to 3.9 x 10(8) cells/hr in efferent prescapular lymph from a 259-day fetus. The circulating lymphocyte pool in fetal calves of about 120 and 190 days gestational age was calculated to contain, respectively, 4 x 10(8) cells and 2 x 10(10) cells. The proportion of lymphocytes bearing surface immunoglobulin detected in fetal lymph ranged from 2.1% to 8.7%. Recirculating lymphocytes from fetal calves produced strong proliferative responses when stimulated by T-cell mitogens but responded poorly to B-cell mitogens. Fetal lymphocytes also responded to stimulation by allogeneic cells and stimulated other cells to proliferate during mixed lymphocyte culture. When stimulated with Con A, fetal lymphocytes secreted IL-2 to a degree that was indistinguishable from the secretory behaviour of lymphocytes from adult animals. The results presented in this paper show that chronic lymphatic fistulae can be established successfully in fetal calves to give access to recirculating lymphocytes. This provides a new experimental approach for studying the development of the bovine immune system. PMID:2971606

Hein, W R; Shelton, J N; Simpson-Morgan, M W; Morris, B

1988-01-01

251

Distribution of Off-Flavor Compounds and Isolation of Geosmin-Producing Bacteria in a Series of Water Recirculating Systems for Rainbow Trout Culture  

Microsoft Academic Search

Preharvest off-flavor in aquaculture products results in large economic losses to producers due to delayed harvest. The common off flavors “earthy” and “musty” are due to the presence of geosmin and 2-methylisoborneol (MIB), respectively. Although certain species of cyanobacteria are responsible for these problems in pond-cultured fish, the microbial sources of geosmin and MIB in recirculating aquaculture systems (RASs) are

Kevin K. Schrader; Steven T. Summerfelt

2010-01-01

252

The impact of increased blood flow rates on recirculation in central venous hemodialysis catheters.  

PubMed

A recent practice change in our unit from Quinton dual lumen PermCaths to Vas-Cath Optiflow central venous catheters resulted in the routine achievement of bloodflow rates (BFR) of 500 ml/min. Previously BFRs of 300-400 ml/min were the norm. The increased BFR was achieved without any apparent increase in venous pressure, prompting us to consider the possibility that increased recirculation was occurring. This paper presents the results of a study designed to answer the following questions: (a) What is the difference in recirculation rates between Quinton dual lumen PermCaths and Vas-Cath Optiflow dual lumen catheters? and (b) What is the impact of increased BFR on recirculation rates in Optiflow hemodialysis catheters? The study documented recirculation rates in two groups of patients. In Group 1, the Optiflow group, recirculation rates were calculated for 10 subjects, first at 350 ml/min and then at 500 ml/min. In Group 2, the PermCath Group, recirculation rates were calculated for 10 subjects at 300 ml/min. Paired t-tests were performed to compare Group 1 at 350 ml/min with Group 2. No significant differences were found within or between groups suggesting that recirculation rates were not affected by increased BFR. PMID:12143473

Szabo, J; Locking-Cusolito, H

2001-12-01

253

Recirculation, urea disequilibrium, and dialysis efficiency: peripheral arteriovenous versus central venovenous vascular access.  

PubMed

When accurate, non-urea-based methods of measuring recirculation are used, recirculation is usually absent in arteriovenous (AV) accesses. When urea-based methods are used to measure recirculation in AV accesses, falsely elevated recirculation rates are common. These errors are due to AV and venovenous disequilibrium (peripheral vein method), delayed systemic sampling (two-needle methods), and errors in urea measurement (all methods). The literature suggests that recirculation in central venovenous (CV) catheters is approximately 5%. The methods used for these determinations have all been urea based. However, there are few theoretical problems in using urea-based measurements for measuring recirculation in this setting, making it more likely that these values are accurate. When hemodialysis via CV and AV accesses are compared, equilibrated Kt/V values differ significantly for the same single-pool Kt/V when 15-second postdialysis blood urea nitrogen values are used for modeling, but differ minimally when 2-minute postdialysis samples are used. The impact of transient retrograde blood flow in the superior vena cava on recirculation and whether dialysis efficiency is influenced by the exact site of CV catheter placement (superior vena cava v right atrium) is uncertain. PMID:9100035

Sherman, R A; Kapoian, T

1997-04-01

254

Enterohepatic recirculation model of irinotecan (CPT-11) and metabolite pharmacokinetics in patients with glioma  

PubMed Central

Background Enterohepatic recirculation of irinotecan and one of its metabolites, SN-38, has been observed in pharmacokinetic data sets from previous studies. A mathematical model that can incorporate this phenomenon was developed to describe the pharmacokinetics of irinotecan and its metabolites. Patients and methods A total of 32 patients with recurrent malignant glioma were treated with weekly intravenous administration of irinotecan at a dose of 125 mg/m2. Plasma concentrations of irinotecan and its three major metabolites were determined. Pharmacokinetic models were developed and tested for simultaneous fit of parent drug and metabolites, including a recirculation component. Results Rebound in the plasma concentration suggestive of enterohepatic recirculation at approximately 0.5–1 h post-infusion was observed in most irinotecan plasma concentration profiles, and in some plasma profiles of the SN-38 metabolite. A multi-compartment model containing a recirculation chain was developed to describe this process. The recirculation model was optimal in 22 of the 32 patients compared to the traditional model without the recirculation component. Conclusion A recirculation chain incorporated in a multi-compartment pharmacokinetic model of irinotecan and its metabolites appears to improve characterization of this drug’s disposition in patients with glioma. PMID:18496691

Younis, Islam R.; Malone, Samuel; Friedman, Henry S.; Schaaf, Larry J.

2014-01-01

255

Haldane's rule revisited: do hybrid females have a shorter lifespan? Survival of hybrids in a recent contact zone between two large gull species.  

PubMed

Haldane's rule predicts that particularly high fitness reduction should affect the heterogametic sex of interspecific hybrids. Despite the fact that hybridization is widespread in birds, survival of hybrid individuals is rarely addressed in studies of avian hybrid zones, possibly because of methodological constraints. Here, having applied capture-mark-recapture models to an extensive, 19-year-long data set on individually marked birds, we estimate annual survival rates of hybrid individuals in the hybrid zone between herring (Larus argentatus) and Caspian (Larus cachinnans) gulls. In both parental species, males have a slightly higher survival rate than females (model-weighted mean ± SE: herring gull males 0.88 ± 0.01, females 0.87 ± 0.01, Caspian gull males 0.88 ± 0.01, females 0.87 ± 0.01). Hybrid males do not survive for a shorter time than nonhybrid ones (0.88 ± 0.01), whereas hybrid females have the lowest survival rate among all groups of individuals (0.83 ± 0.03). This translates to a shorter adult (reproductive) lifespan (on average by 1.7-1.8 years, i.e. ca 25%) compared with nonhybrid females. We conclude that, in line with Haldane's rule, the lower survival rate of female hybrids may contribute to selection against hybrids in this hybrid zone. PMID:24820228

Neubauer, G; Nowicki, P; Zagalska-Neubauer, M

2014-06-01

256

Lycos Zone  

NSDL National Science Digital Library

In the tradition of Yahooligans (reviewed in the March 22, 1996 Scout Report) and other so-called "green spaces," Lycos has created a new online safe haven for young users which is fairly self-contained, with the exception of the advertisements. (In response to criticisms regarding aggressive marketing to children at similar sites, Lycos claims that the ads are clearly marked and will not collect any personal information.) The site is composed of four sections: the Fun and Games Zone, the Homework Zone, the New and Cool Zone, and an area for parents and teachers. The first two sections are fairly deep, with numerous resources and activities aimed at various age levels. Some links in the Homework Zone lead users outside the site, but they are first presented with a gateway page informing them that they are leaving and offering advice on not divulging personal information.

257

Sulfur recirculation for increased electricity production in Waste-to-Energy plants.  

PubMed

Sulfur recirculation is a new technology for reducing boiler corrosion and dioxin formation. It was demonstrated in full-scale tests at a Waste to Energy plant in Göteborg (Sweden) during nearly two months of operation. Sulfur was recirculated as sulfuric acid from the flue gas cleaning back to the boiler, thus creating a sulfur loop. The new technology was evaluated by extensive measurement campaigns during operation under normal conditions (reference case) and operation with sulfur recirculation. The chlorine content of both fly ash and boiler ash decreased and the sulfur content increased during the sulfur recirculation tests. The deposit growth and the particle concentration decreased with sulfur recirculation and the dioxin concentration (I-TEQ) of the flue gas was reduced by approximately 25%. Sulfuric acid dew point measurements showed that the sulfuric acid dosage did not lead to elevated SO3 concentrations, which may otherwise induce low temperature corrosion. In the sulfur recirculation corrosion probe exposures, the corrosion rate decreased for all tested materials (16Mo3, Sanicro 28 and Inconel 625) and material temperatures (450 °C and 525 °C) compared to the reference exposure. The corrosion rates were reduced by 60-90%. Sulfur recirculation prevented the formation of transition metal chlorides at the metal/oxide interface, formation of chromate and reduced the presence of zinc in the corrosion products. Furthermore, measured corrosion rates at 525 °C with sulfur recirculation in operation were similar or lower compared to those measured at 450 °C material temperature in reference conditions, which corresponds to normal operation at normal steam temperatures. This implies that sulfur recirculation allows for higher steam data and electricity production without increasing corrosion. PMID:24140194

Andersson, Sven; Blomqvist, Evalena W; Bäfver, Linda; Jones, Frida; Davidsson, Kent; Froitzheim, Jan; Karlsson, Martin; Larsson, Erik; Liske, Jesper

2014-01-01

258

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E-print Network

N O P R I N TI N G Z O N E N O P R I N TI N G Z O N E N O P R I N TI N G Z O N E NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE NO PRINTING ZONE

Kainen, Paul C.

259

Evaluation of the impact of nitrate-nitrogen levels in recirculating aquaculture systems on concentrations of the off-flavor compounds geosmin and 2-methylisoborneol in water and rainbow trout (Oncorhynchus mykiss)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aquatic animals raised in recirculating aquaculture systems (RAS) can develop preharvest “off-flavors” such as “earthy” or “musty” which are caused by the bioaccumulation of the odorous compounds geosmin or 2-methylisoborneol (MIB), respectively, in their flesh. Tainted aquatic products cause large...

260

Molecular and morphological patterns of introgression between two large white-headed gull species in a zone of recent secondary contact.  

PubMed

Incomplete reproductive isolation promotes gene flow between diverging taxa. However, any gene encoding for traits involved in the reproductive barriers will be less prone to introgression than neutral markers. Comparing introgression rates among loci is thus informative of the number and functions of loci involved in the reproductive barriers. This study aimed at identifying possible mechanisms of restriction to gene flow across a zone of recent secondary contact between Larus argentatus and Larus cachinnans by comparing introgression patterns for nine microsatellite loci, a fragment of mitochondrial DNA and a set of phenotypic traits. The low linkage disequilibrium between neutral nuclear markers indicated introgression without any barrier to gene flow. However, asymmetric introgression of mitochondrial DNA suggested that interspecific crosses may be more successful in one direction. The introgression rate for phenotypic traits was variable and low compared to neutral molecular markers. This was particularly evident in colouration of bare parts: individuals with intermediate colouration were scarcer in sympatry than expected if the genomes recombined freely. We hypothesized that one of these variables, the orbital ring colour, may play a role in mate choice, acting as an incomplete premating barrier through assortative mating. This study emphasizes that multilocus approaches are useful to discriminate among possible mechanisms responsible for the maintenance of hybrid zones. PMID:17651198

Gay, L; Neubauer, G; Zagalska-Neubauer, M; Debain, C; Pons, J-M; David, P; Crochet, P-A

2007-08-01

261

Quantitative investigations of the Missouri gravity low: A possible expression of a large, Late Precambrian batholith intersecting the New Madrid seismic zone  

USGS Publications Warehouse

Analysis of gravity and magnetic anomaly data helps characterize the geometry and physical properties of the source of the Missouri gravity low, an important cratonic feature of substantial width (about 125 km) and length (> 600 km). Filtered anomaly maps show that this prominent feature extends NW from the Reelfoot rift to the Midcontinent Rift System. Geologic reasoning and the simultaneous inversion of the gravity and magnetic data lead to an interpretation that the gravity anomaly reflects an upper crustal, 11-km-thick batholith with either near vertical or outward dipping boundaries. Considering the modeled characteristics of the batholith, structural fabric of Missouri, and relations of the batholith with plutons and regions of alteration, a tectonic model for the formation of the batholith is proposed. The model includes a mantle plume that heated the crust during Late Precambrian and melted portions of lower and middle crust, from which the low-density granitic rocks forming the batholith were partly derived. The batholith, called the Missouri batholith, may be currently related to the release of seismic energy in the New Madrid seismic zone (earthquake concentrations occur at the intersection of the Missouri batholith and the New Madrid seismic zone). Three qualitative mechanical models are suggested to explain this relationship with seismicity. Copyright 1996 by the American Geophysical Union.

Hildenbrand, T.G.; Griscom, A.; Van Schmus, W. R.; Stuart, W.D.

1996-01-01

262

Soil nitrifying enrichments as biofilter starters in intensive recirculating saline water aquaculture  

E-print Network

aquaculture Abstract Intensive recirculating aquaculture relies on biofilters to sustain satisfactory water quality in the ponds. Establishment of new biofilters in aquaculture ponds without a start-up culture

Gross, Amit

263

Fish Health Management Considerations in Recirculating Aquaculture systems -Part 3: General  

E-print Network

Cir 122 Fish Health Management Considerations in Recirculating Aquaculture systems -Part 3: General Professor, Tropical Aquaculture Laboratory, Ruskin FL 33570, Department of Fisheries and Aquatic Sciences commonly used in aquaculture facilities, wholesale and retail tropical fish facilities, and public aquaria

Watson, Craig A.

264

Experimental Study of the Circulation Air Volume of Recirculation Evaporative Cooling  

E-print Network

ICEBO2006, Shenzhen, China HVAC Technologies for Energy Efficiency, Vol. IV-11-3 Experimental Study of the Circulation Air Volume of Recirculation Evaporative Cooling 1 Jun Xiong ZeHua Liu Chao Wang GuoJie Chen Bachelor Senior...

Xiong, J.; Liu, Z.; Wang, C.; Chen, G.

2006-01-01

265

The evaluation of oxygen and carbon dioxide transfer associated with airlifts in recirculating aquaculture systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Airlifts in recirculating aquaculture systems (RAS) provide aeration, degasification, and water circulation. They allow the simplification of systems, and if designed properly, can reduce the capital costs and minimize operation and maintenance associated with alternative pumping systems. In order t...

266

The entrainment and homogenization of tracers within the cyclonic gulf stream recirculation gyre  

E-print Network

The various distributions of tracer associated with the Northern Recirculation Gyre of the Gulf Stream (NRG) are studied to try to obtain information about the flow. An advective-diffusive numerical model is implemented ...

Pickart, Robert S

1987-01-01

267

TO RATING FIXED-FILM BIOFILTERS USED IN RECIRCULATING AQUACULTURE SYSTEMS  

Technology Transfer Automated Retrieval System (TEKTRAN)

A standardized methodology for evaluating and rating biofilters is proposed to simplify design of recirculating systems. This methodology will allow engineers to compare biofilters options and accurately predict performance before construction. The methodology is based upon an increasing recognized ...

268

High-Power Laser Pulse Recirculation for Inverse Compton Scattering-Produced Gamma-Rays  

SciTech Connect

Inverse Compton scattering of high-power laser pulses on relativistic electron bunches represents an attractive method for high-brightness, quasi-monoenergetic {gamma}-ray production. The efficiency of {gamma}-ray generation via inverse Compton scattering is severely constrained by the small Thomson scattering cross section. Furthermore, repetition rates of high-energy short-pulse lasers are poorly matched with those available from electron accelerators, resulting in low repetition rates for generated {gamma}-rays. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. Here we propose and experimentally demonstrate an alternative method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J. Inverse Compton scattering of recirculated Joule-level laser pulses has a potential to produce unprecedented peak and average {gamma}-ray brightness in the next generation of sources.

Jovanovic, I; Shverdin, M; Gibson, D; Brown, C

2007-04-17

269

The growth of New Guinea impatiens with controlled-release fertilizer in a recirculating subirrigation system  

E-print Network

With concerns increasing over the supply and quality of water, pressure on greenhouse growers to use water and fertilizers more efficiently is also increasing. Controlled-release fertilizers (CRF) and recirculating subordination systems...

Richards, Daphne Ladean

2012-06-07

270

Aircraft Recirculation Filter for Air-Quality and Incident Assessment  

PubMed Central

The current research examines the possibility of using recirculation filters from aircraft to document the nature of air-quality incidents on aircraft. These filters are highly effective at collecting solid and liquid particulates. Identification of engine oil contaminants arriving through the bleed air system on the filter was chosen as the initial focus. A two-step study was undertaken. First, a compressor/bleed air simulator was developed to simulate an engine oil leak, and samples were analyzed with gas chromatograph-mass spectrometry. These samples provided a concrete link between tricresyl phosphates and a homologous series of synthetic pentaerythritol esters from oil and contaminants found on the sample paper. The second step was to test 184 used aircraft filters with the same gas chromatograph-mass spectrometry system; of that total, 107 were standard filters, and 77 were nonstandard. Four of the standard filters had both markers for oil, with the homologous series synthetic pentaerythritol esters being the less common marker. It was also found that 90% of the filters had some detectable level of tricresyl phosphates. Of the 77 nonstandard filters, 30 had both markers for oil, a significantly higher percent than the standard filters. PMID:25641977

Eckels, Steven J.; Jones, Byron; Mann, Garrett; Mohan, Krishnan R.; Weisel, Clifford P.

2015-01-01

271

In situ treatment of VOCs by recirculation technologies  

SciTech Connect

The project described herein was conducted by Oak Ridge National Laboratory (ORNL) to identify processes and technologies developed in Germany that appeared to have near-term potential for enhancing the cleanup of volatile organic compound (VOC) contaminated soil and groundwater at DOE sites. Members of the ORNL research team identified and evaluated selected German technologies developed at or in association with the University of Karlsruhe (UoK) for in situ treatment of VOC contaminated soils and groundwater. Project activities included contacts with researchers within three departments of the UoK (i.e., Applied Geology, Hydromechanics, and Soil and Foundation Engineering) during fall 1991 and subsequent visits to UoK and private industry collaborators during February 1992. Subsequent analyses consisted of engineering computations, groundwater flow modeling, and treatment process modeling. As a result of these project efforts, two processes were identified as having near-term potential for DOE: (1) the vacuum vaporizer well/groundwater recirculation well and (2) the porous pipe/horizontal well. This document was prepared to summarize the methods and results of the assessment activities completed during the initial year of the project. The project is still ongoing, so not all facets of the effort are completely described in this document. Recommendations for laboratory and field experiments are provided.

Siegrist, R.L.; Webb, O.F.; Ally, M.R.; Sanford, W.E. [Oak Ridge National Lab., TN (US); Kearl, P.M.; Zutman, J.L. [Oak Ridge National Lab., Grand Junction, CO (US)

1993-06-01

272

Picosecond Pulse Recirculation for High Average Brightness Thomson Scattering-based Gamma-ray Sources  

SciTech Connect

Pulse recirculation has been successfully demonstrated with the interaction laser system of LLNL's Thomson-Radiated Extreme X-ray (T-REX) source. The recirculation increased twenty-eight times the intensity of the light coming out of the laser system, demonstrating the capability of increasing the gamma-ray flux emitted by T-REX. The technical approach demonstrated could conceivably increase the average gamma-ray flux output by up to a hundred times.

Semenov, V

2009-05-28

273

Grain quality impacts of prohibiting recombination recirculation dust at export grain elevators  

E-print Network

GRAIN QUALITY IMPACTS OF PROHIBITING RECOMBINATION RECIRCULATION DUST AT EXPORT GRAIN ELEVATORS A Thesis by DARYL DREW SPILLMANN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1992 Major Subject: Agricultural Engineering GRAIN QUALITY IMPACTS OF PROHIBITING RECOMBINATION RECIRCULATION DUST AT EXPORT GRAIN ELEVATORS A Thesis by DARYL DREW SPILLMANN Approved as to style and content by...

Spillmann, Daryl Drew

1992-01-01

274

Comparison of hydroponic crop production techniques in a recirculating fish culture system  

E-print Network

of the experimental recirculating aquaculture system. All major parts are described including the three experimental water treatments. Portion of System Total Water Units Volume (L) Flow (L/day) Retention T trna (hours) Media Surface Ar~a (m ) Aeration...COMPARISON OF HYDROPONIC CROP PRODUCTION TECHNIQUES IN A RECIRCULATING FISH CULTURE SYSTEM A Thesis by STEVEN WHITAKKR WREN Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements for the degree...

Wren, Steven Whitaker

2012-06-07

275

Ventilating characteristics of a recirculating air-curtain laboratory exhaust hood  

E-print Network

VENTILATING CHARACTERISTICS OF A RECIRCULATING AIR-CURTAIN LABORATORY EXHAUST HOOD A Thesis by DALE FLOYD JANES Submitted to the Graduate College of Texas A8M University in partial fulfillment of the requirement for the degree of MASTER... OF SCIENCE August, 1978 Major Subject: Industrial Hygiene Copyright by Dale Floyd Janes 1978 443229 VENTILATING CHARACTERISTICS OF A RECIRCULATING AIR-CURTAIN LABORATORY EXHAUST HOOD A Thesis by DALE FLOYD JANES Approved as to style and content by...

Janes, Dale Floyd

2012-06-07

276

Culture of selected organisms in recirculating and flow-through systems using thermal effluent  

E-print Network

of. 1~&STER OF SCIENCE August. 1978 Najor Subject: Wildlife and Fisheries Sciences CULTURE OF SELECTED ORGANISMS IN RECIRCULATING AND FLOW-THROUGH SYSTEMS USING THERMAL EFFLUENT A Thesis by TERRI LAYNE BERRY Approved as to style and content... by: (Chairman of Commit ) Head of Department Member Member August, l978 443161 ABSTRACT Culture of Selected Organism. in Recirculating and Flow-Through Systems Using Thermal Effle nt. (August 1978) Terri Layne Berry, B. S. , Texas A...

Berry, Terri Layne

2012-06-07

277

Technical Notes: Multiple-Tank Aquarium System with Recirculating Water for Laboratory Studies of Freshwater Fishes  

Microsoft Academic Search

A recirculating-water aquarium system for laboratory studies of freshwater fishes is described. The system consists of 216 glass tanks (3.5 gal each), two particle filters, a multistage biofilter, two ultraviolet-light sterilizers, and a regenerative blower for auxiliary aeration. Each tank is connected separately to the recirculating-water supply through inflow and outflow manifold pipes. Water flow to individual tanks is adjustable

Roger W. Rottmann; Donald E. Campton

1989-01-01

278

Dead Zone  

NSDL National Science Digital Library

In this video segment adapted from the independent film Big River: A King Corn Companion, the filmmakers explain how agricultural runoff from the Midwest has contributed to a massive "dead zone" in the Gulf of Mexico. A cornfield treated with conventional chemical fertilizer promises a bumper crop, but chemical runoff from the farm enters the Iowa River, eventually draining into the Mississippi River and the Gulf of Mexico. In the Gulf, these dissolved nutrients allow algae to flourish. The algae's decay depletes the water of oxygen, creating a dead zone where shrimp and fish are starved of oxygen and die. A background essay, discussion questions, and standards correlations are also provided.

2010-08-31

279

Modelling and Optimisation of Eurycoma longifolia Extraction Utilising a Recirculating Flow Extractor  

NASA Astrophysics Data System (ADS)

In this study, Tongkat Ali was extracted with a newly designed recirculating flow extractor with temperature and flow rate as the operating parameters. The optimum duration and ratio for extraction were found to be 90 min and 40:1 w/w, respectively. The determination of optimal operating parameter value for this extractor was based on maximum percentage extract yield and solid diffusivity, Ds,. From the experiments, it was found that the temperature and flow rate that produce the highest yield and solid diffusivity value were at 90°C and 400 rpm (22.47 mL sec-1), respectively. The optimal operating parameter values were used to compare the recirculating flow extractor performance with a batch extraction at 90°C. The comparison showed that the batch extraction was able to extract more rapidly than the recirculating flow extractor. The solid diffusivity, Ds, value for the batch extraction was found to be is 3.12x10-11 m2 sec-1 while the recirculating flow extractor had a solid diffusivity, Ds, value of 2.98x10-11 m2 sec-1 which indicated the difference in extraction rate. However, by utilizing the recirculating flow extractor, a higher final yield than batch extraction was produced which is 7.70% (w/w) for the recirculating flow extractor and 6.67% (w/w) for the batch extraction. This is possibly caused by the higher rates of solvent losses through evaporation for batch extraction.

Ajib Mohtar, Mohd; Kumaresan, Sivakumar; Roji Sarmidi, Mohd; Aziz, Ramlan Abdul

280

Anolyte recirculation effects in buffered and unbuffered single-chamber air-cathode microbial fuel cells.  

PubMed

Two identical microbial fuel cells (MFCs) with a floating air-cathode were operated under either buffered (MFC-B) or bufferless (MFC-BL) conditions to investigate anolyte recirculation effects on enhancing proton transfer. With an external resistance of 50? and recirculation rate of 1.0ml/min, MFC-BL had a 27% lower voltage (9.7% lower maximal power density) but a 64% higher Coulombic efficiency (CE) than MFC-B. MFC-B had a decreased voltage output, batch time, and CE with increasing recirculation rate resulting from more oxygen transfer into the anode. However, increasing the recirculation rate within a low range significantly enhanced proton transfer in MFC-BL, resulting in a higher voltage output, a longer batch time, and a higher CE. A further increase in recirculation rate decreased the batch time and CE of MFC-BL due to excess oxygen transfer into anode outweighing the proton-transfer benefits. The unbuffered MFC had an optimal recirculation rate of 0.35ml/min. PMID:25514399

Zhang, Liang; Zhu, Xun; Kashima, Hiroyuki; Li, Jun; Ye, Ding-Ding; Liao, Qiang; Regan, John M

2015-03-01

281

Disinfection of Pythium-infested recirculation water by UV-oxidation technology.  

PubMed

Selective disinfection against Pythium aphanidermatum in recirculation water was tested with UV-irradiation and with UV-oxidation technology with the objective to reduce the electrical energy consumption per cubic meter treated water. UV-oxidation technology is based on injection of hydrogen peroxide in recirculation water, just before passage along a UV-lamp, thus creating hydroxyl radicals. Pythium aphanidermatum was applied artificially to recirculation water from tomatoes, grown, in rockwool and coconut fibre. Other parameters in this study were pH and transmission value (T10) of the infested recirculation water. Results indicated that the recommended UV-C dose of 100 mJ/cm2 for elimination of fungal pathogens in general can be lowered in case recirculation water is infected with Pythium aphanidermatum only. When UV-oxidation technology was applied with 1 mmol hydrogen peroxide per litre recirculation water, the UV-C dose could be reduced even more in comparison with merely UV irradiation. PMID:12425022

Runia, W T; Boonstra, S

2001-01-01

282

Properties of the mean recirculation region in the wakes of two-dimensional bluff bodies  

NASA Astrophysics Data System (ADS)

The properties of the time- and span-averaged mean wake recirculation region are investigated in separated flows over several different two-dimensional bluff bodies. Ten different cases are considered and they divide into two groups: cylindrical geometries of circular, elliptic and square cross-sections and the normal plate. A wide Reynolds number range from 250 to 140000 is considered, but in all the cases the attached portion of the boundary layer remains laminar until separation. The lower Reynolds number data are from direct numerical simulations, while the data at the higher Reynolds number are obtained from large-eddy simulation and the experimental work of Cantwell & Coles (1983), Krothapalli (1996, personal communication), Leder (1991) and Lyn et al. (1995). Unlike supersonic and subsonic separations with a splitter plate in the wake, in all the cases considered here there is strong interaction between the shear layers resulting in Kármán vortex shedding. The impact of this fundamental difference on the distribution of Reynolds stress components and pressure in relation to the mean wake recirculation region (wake bubble) is considered. It is observed that in all cases the contribution from Reynolds normal stress to the force balance of the wake bubble is significant. In fact, in the cylinder geometries this contribution can outweigh the net force from the shear stress, so that the net pressure force tends to push the bubble away from the body. In contrast, in the case of normal plate, owing to the longer wake, the net contribution from shear stress outweighs that from the normal stress. At higher Reynolds numbers, separation of the Reynolds stress components into incoherent contributions provides more insight. The behaviour of the coherent contribution, arising from the dominant vortex shedding, is similar to that at lower Reynolds numbers. The incoherent contribution to Reynolds stress, arising from small-scale activity, is compared with that of a canonical free shear layer. Based on these observations a simple extension of the wake model (Sychev 1982; Roshko 1993a, b) is proposed.

Balachandar, S.; Mittal, R.; Najjar, F. M.

1997-11-01

283

Mono-fermentation of chicken manure: Ammonia inhibition and recirculation of the digestate.  

PubMed

The effects of ammonia concentration on the performance and stability of mono-fermentation of chicken manure were investigated in a lab-scale continuous stirred tank reactor at 40°C. Technical stripping was performed to remove ammonia from the liquid fraction of digestate, and the entire product was recycled to the fermenter to control ammonia concentration in the fermenter. Organic loading rate (OLR) of 5.3gVS/(Ld) was achieved with an average free ammonia nitrogen (FAN) concentration of 0.77g/L and a specific gas yield of 0.39L/gVS. When OLR was increased to 6.0gVS/(Ld), stable operation could be obtained with an average FAN concentration of 0.86g/L and a specific gas yield of 0.27L/gVS. Mono-fermentation of chicken manure was successfully carried out at high ammonia concentrations. Controlled recirculation of treated liquid fraction of digestate could be a solution in large-scale application for both: to avoid ammonia inhibition and minimize digestate. PMID:25266688

Nie, Hong; Jacobi, H Fabian; Strach, Katrin; Xu, Chunming; Zhou, Hongjun; Liebetrau, Jan

2015-02-01

284

Temporal and spatial pore water pressure distribution surrounding a vertical landfill leachate recirculation well.  

PubMed

Addition of liquids into landfilled waste can result in an increase in pore water pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured pore pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth. PMID:21655145

Kadambala, Ravi; Townsend, Timothy G; Jain, Pradeep; Singh, Karamjit

2011-05-01

285

Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary Formations  

SciTech Connect

There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. Terralog USA, in collaboration with the University of California, Irvine (UCI), are currently investigating advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. This two-year research project, funded by the US Department of Energy, includes combined efforts for: 1) Resource characterization; 2) Small and large scale laboratory investigations; 3) Numerical simulation at both the laboratory and field scale; and 4) Engineering feasibility studies and economic evaluations. The research project is currently in its early stages. This paper summarizes our technical approach and preliminary findings related to potential resources, small-scale laboratory simulation, and supporting numerical simulation efforts.

Mike Bruno; Russell L. Detwiler; Kang Lao; Vahid Serajian; Jean Elkhoury; Julia Diessl; Nicky White

2012-09-30

286

Temporal and Spatial Pore Water Pressure Distribution Surrounding a Vertical Landfill Leachate Recirculation Well  

PubMed Central

Addition of liquids into landfilled waste can result in an increase in pore water pressure, and this in turn may increase concerns with respect to geotechnical stability of the landfilled waste mass. While the impact of vertical well leachate recirculation on landfill pore water pressures has been mathematically modeled, measurements of these systems in operating landfills have not been reported. Pressure readings from vibrating wire piezometers placed in the waste surrounding a liquids addition well at a full-scale operating landfill in Florida were recorded over a 2-year period. Prior to the addition of liquids, measured pore pressures were found to increase with landfill depth, an indication of gas pressure increase and decreasing waste permeability with depth. When liquid addition commenced, piezometers located closer to either the leachate injection well or the landfill surface responded more rapidly to leachate addition relative to those far from the well and those at deeper locations. After liquid addition stopped, measured pore pressures did not immediately drop, but slowly decreased with time. Despite the large pressures present at the bottom of the liquid addition well, much smaller pressures were measured in the surrounding waste. The spatial variation of the pressures recorded in this study suggests that waste permeability is anisotropic and decreases with depth. PMID:21655145

Kadambala, Ravi; Townsend, Timothy G.; Jain, Pradeep; Singh, Karamjit

2011-01-01

287

Closed recirculating system for shrimp-mollusk polyculture  

NASA Astrophysics Data System (ADS)

This paper deals with a new system of aquaculture, i.e., a closed recirculating system for shrimp-mollusk polyculture. The culture system consisted of several shrimp ponds, a mollusk water-purifying pond and a reservoir. During the production cycle, water circulated between the shrimp and mollusk ponds, and the reservoir compensated for water loss from seepage and evaporation. Constricted tagelus, Sinonovacula constricta, was selected as the cultured mollusk, and Pacific white shrimp, Litopenaeus vannamei, as the cultured shrimp. The main managing measures during the production cycle were: setting and using the aerators; introducting the probiotic products timely into the shrimp ponds; adopting a “pen-closing” method for controlling shrimp viral epidemics; setting the flow diversion barriers in the mollusk pond to keep the circulating water flowing through the pond along a sine-like curve and serve as substrate for biofilm; no direct feeding was necessary for the cultured mollusk until the co-cultured shrimp was harvested; natural foods in the water from the shrimp ponds was used for their foods. Two sets of the system were used in the experiment in 2002 and satisfactory results were achieved. The average yield of the shrimp was 11 943.5 kg/hm2, and that of the mollusk was 16 965 kg/hm2. After converting the mollusk yield into shrimp yield at their market price ratio, the food coefficient of the entire system averaged at as low as 0.81. The water quality in the ponds was maintained at a desirable level and no viral epidemics were discovered during the production cycle.

Wu, Xiongfei; Zhao, Zhidong; Li, Deshang; Chang, Kangmei; Tong, Zhuanshang; Si, Liegang; Xu, Kaichong; Ge, Bailin

2005-12-01

288

Mineral and organic compounds in leachate from landfill with concentrate recirculation.  

PubMed

The effect of a reverse osmosis concentrate recirculation on the mineral and organic compounds in a landfill leachate was investigated. Investigated was the quality of a leachate from two landfills operated for different periods (a 20-year-old Cell A and a 1-year-old Cell B), where the concentrate was recirculated. Examined were general parameters (conductivity, pH), organic compounds (biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic nitrogen, BOD/COD), and inorganic compounds (nitrogen ammonia, sulfite, sulfate, cyanide, boron, chloride, ferrous, zinc, chrome, copper). The findings from the first year of investigation showed that over the initial period of recirculation, the concentration of organic compounds (BOD, COD) increased, but after 6 months their values stabilized. It indicates that the concentrate recirculation accelerated organic decomposition, especially in the new landfill Cell. The analysis of inorganic parameters showed that recirculation landfills produce a leachate with a higher concentration of N-NH4, and Cl(-). In case of the old landfill Cell, an increase in B and Fe was also noticeable. These compounds are cyclically washed out from a waste dump and require an additional pretreatment in order to exclude them from recirculation cycle. The increased concentration of Cu, Zn, and Fe was noticed during the initial months of recirculation and in the season of intense atmospheric precipitation in the leachate from both Cells. Higher values of electro conductivity, Cl(-), N-NH4 (+), B, and Fe in the leachate from the old field indicate that the attenuation capacity of this landfill is close to exhaustion. PMID:25194843

Talalaj, Izabela Anna

2014-09-01

289

Resolving the Effects of Aperture and Volume Restriction of the Flow by Semi-Porous Barriers Using Large-Eddy Simulations  

NASA Astrophysics Data System (ADS)

The Regional Atmospheric Modelling System (RAMS)-based Forest Large-Eddy Simulation (RAFLES) model is used to simulate the effects of large rectangular prism-shaped semi-porous barriers of varying densities under neutrally buoyant conditions. RAFLES model resolves flows inside and above forested canopies and other semi-porous barriers, and it accounts for barrier-induced drag on the flow and surface flux exchange between the barrier and the air. Unlike most other models, RAFLES model also accounts for the barrier-induced volume and aperture restriction via a modified version of the cut-cell coordinate system. We explicitly tested the effects of the numerical representation of volume restriction, independent of the effects of the drag, by comparing drag-only simulations (where we prescribed neither volume nor aperture restrictions to the flow), restriction-only simulations (where we prescribed no drag), and control simulations where both drag and volume plus aperture restrictions were included. Previous modelling and empirical work have revealed the development of important areas of increased uplift upwind of forward-facing steps, and recirculation zones downwind of backward-facing steps. Our simulations show that representation of the effects of the volume and aperture restriction due to the presence of semi-porous barriers leads to differences in the strengths and locations of increased-updraft and recirculation zones, and the length and strength of impact and adjustment zones when compared to simulation solutions with a drag-only representation. These are mostly driven by differences to the momentum budget of the streamwise wind velocity by resolved turbulence and pressure gradient fields around the front and back edges of the barrier. We propose that volume plus aperture restriction is an important component of the flow system in semi-porous environments such as forests and cities and should be considered by large-eddy simulation (LES).

Chatziefstratiou, Efthalia K.; Velissariou, Vasilia; Bohrer, Gil

2014-09-01

290

Electron recirculation in electrostatic multicusp systems: II. System performance scaling of one-dimensional rollover wells  

SciTech Connect

In an earlier paper a comprehensive study was made of the recirculation and losses of electrons in their flow through simple inverse power-law potential wells bounded by similarly inverse power-law dependent magnetic fields. This study examined electron flow and loss behavior in the simplest approximation invoked to describe Polywell confinement systems. The importance of this study, and of the present paper, is that the power balance in Polywell systems is determined entirely by the rate of electron losses; if these are large, then the system can not yield net power. Thus it is of interest to determine those conditions that results in small losses, and to design experiments and systems to attempt to achieve and operate at these most favorable conditions, in order to test and prove the efficacy of the system for the generation of net power from fusion reactions. The outline and summary of this problem presented is generally repeated here, with some modifications to clarify particular physics issues of most concern, in order to avoid having to refer to the earlier document for this general description. As noted, a large body of work has been undertaken over the past 35 or so years in the study of general cusp confinement of plasmas. Nearly all of this has examined single particle electron (or ion) motion or the motion of particles in neutral plasmas within cusped magnetic systems, generally without internal electric potential fields.**INVALID KEYWORDS: controlled nuclear fusion, electron flux, plasma devices, confinement, performance, engineering, scaling factor, multicusp systems, polywell systems

Bussard, R.W.; King, K.E.

1992-01-01

291

Exhaust gas recirculation control method and apparatus for internal combustion engine  

SciTech Connect

An exhaust gas recirculation control method is described for operating an exhaust gas recirculation control device including a needle valve provided in an exhaust gas recirculation passage for setting an effective diameter of the passage, a position sensor for providing a signal representing a position of the needle valve, and a negative pressure motor for positioning the needle valve. The method comprises: setting a target value for the needle valve according to predetermined operating conditions of the internal combustion engine; measuring a positional deviation between the target value and an actual position of the needle valve as represented by the signal provided by the position sensor; and driving the negative pressure motor with only a single drive pulse having a time width corresponding to the measured positional deviation. An exhaust gas recirculation control apparatus is described for operating an exhaust gas recirculation control device. The apparatus comprises: means for setting a target value for the needle valve according to predetermined operating conditions of the internal combustion engine; and means for measuring a positional deviation between the target value and an actual position of the needle valve as represented by the signal provided by the position sensor.

Tsutsumi, K.

1987-02-10

292

[Research on the variation regularity of effluent from the leachate reverse osmosis concentrate recirculation].  

PubMed

To provide certain theoretical basis for selecting recirculation landfill scientifically and reasonably, the variation regularity of recirculation effluent from the landfill columns in three different years was studied. By using leachate reverse osmosis concentrate from a refuse landfill in Chengdu, the recirculation experiments were carried out in three landfill columns filled with garbage in 1, 5 and 15 landfill ages respectively. The variation regularity of pH, total organic carbon, ammonia nitrogen, nitrate nitrogen and heavy metals of recirculation effluent was researched. It showed that the one-year landfill column with a favorable ability of removing nitrate nitrogen and degradation rate of nitrate nitrogen reaching above 88% was in the stage of producing methanation, but the concentration of organic matter and ammonia nitrogen of the effluent is higher and changes in the parameters mainly depend on the biological function. The five-year landfill column without typical features of mineralized refuse and with relatively poor adsorption capacity and biological effects, as well as removal capacity of organic matter, salinity, Cr and Ni approaches stabilization. The fifteen-year landfill column has high capability of adsorption, complexing, as well as organic matter, salinity, Cr and Ni removal, and the removal rate at the initial stage reaches 90%, 78%, 93% and 78%, respectively, but the recirculation process and progress need to be controlled when the rate approaches or reaches the adsorption capacity. PMID:25244874

Wang, Dong-Mei; Liu, Dan; Liu, Qing-Mei; Tao, Li-Xia; Liu, Ying

2014-07-01

293

Field evaluation of a horizontal well recirculation system for groundwater treatment: Field demonstration at X-701B Portsmouth Gaseous Diffusion Plant, Piketon, Ohio  

SciTech Connect

This report describes the field-scale demonstration performed as part of the project, In Situ Treatment of Mixed Contaminants in Groundwater. This project was a 3{1/2} year effort comprised of laboratory work performed at Oak Ridge National Laboratory and fieldwork performed at the US Department of Energy (DOE) Portsmouth Gaseous Diffusion Plant (PORTS). The overall goal of the project was to evaluate in situ treatment of groundwater using horizontal recirculation coupled with treatment modules. Specifically, horizontal recirculation was tested because of its application to thin, interbedded aquifer zones. Mixed contaminants were targeted because of their prominence at DOE sites and because they cannot be treated with conventional methods. The project involved several research elements, including treatment process evaluation, hydrodynamic flow and transport modeling, pilot testing at an uncontaminated site, and full-scale testing at a contaminated site. This report presents the results of the work at the contaminated site, X-701B at PORTS. Groundwater contamination at X-701B consists of trichloroethene (TCE) (concentrations up to 1800 mg/L) and technetium-998 (Tc{sup 99}) (activities up to 926 pCi/L).

Korte, N.; Muck, M.; Kearl, P.; Siegrist, R.; Schlosser, R.; Zutman, J. [Oak Ridge National Lab., TN (United States)] [Oak Ridge National Lab., TN (United States); Houk, T. [Lockheed Martin Energy Systems, Piketon, OH (United States). Portsmouth Gaseous Diffusion Plant] [Lockheed Martin Energy Systems, Piketon, OH (United States). Portsmouth Gaseous Diffusion Plant

1998-08-01

294

Large Eddy Simulation of Isothermal Swirling Flows  

Microsoft Academic Search

Modelling of swirling flames is a difficult challenge due to their complex recirculation and vortex characteristics. Most of the traditional modelling approaches which work well in other situations fails to perform well in swirling flows when the swirl numbers are high. To this end the purpose of this paper is to perform and validate large eddy simulation of a simple,

K. K. J. Ranga; W. Malalasekera; S. S. Ibrahim; M. P. Kirkpatrick

295

Effects of anti-recirculation ring on performance of an automotive cooling fan  

NASA Astrophysics Data System (ADS)

An investigation has been conducted to evaluate the effects of anti-recirculation ring on performance of automotive axial flow cooling fan by CFD simulation. In order to reduce the element size and save computing time, periodic boundary condition and single flow channel has been applied to the simulation. The grid is composed of tetrahedral mesh and hexahedral mesh. The SST k - ? turbulence model and standard wall function method have been used. CFD results show that optimal design of pressure loss anti-recirculation ring can not only increase P-Q performance and aerodynamic efficiency, but also can improve the pressure distribution on fan tip which can reduce the axial deformation of cooling fan. So it can be proved that good design of anti-recirculation ring will not increase the total axial size of an axial cooling fan.

Chen, Q. G.; Zhang, Y. C.; Li, F.; Kong, X. Z.; Luan, X. H.

2013-12-01

296

The Performance of Refrigeration Cycle with Vapor Re-circulation Evaporator Using an Ejector  

NASA Astrophysics Data System (ADS)

We have proposed new method that re-circulates vapor refrigerant into the evaporator using an ejector to enhance the evaporating heat transfer in the refrigeration cycle. It makes the evaporating heat transfer coefficient higher by increase of the dryness-quality at the inlet of evaporator. We investigated experimentally the coefficient of performance (COP) of the refrigeration cycle and the evaporating heat transfer coefficient with a proposal means, under various evaporating and condensing temperatures and heat loads. As a result, the COP of proposed cycle is 5-13% higher than the conventional cycle with a D.C. inverter compressor by re-circulation of refrigerant. Furthermore, we investigated the dry-out length in the evaporator by authorized empirical equation and evaluated the optimum flow rate of re-circulation.

Man'o, Tatsunori; Tanino, Masayuki; Okazaki, Takashi; Koyama, Shigeru

297

Upstream open loop control of the recirculation area downstream of a backward-facing step  

E-print Network

The flow downstream a backward-facing step is controlled using a pulsed jet placed upstream of the step edge. Experimental velocity fields are computed and used to the recirculation area quantify. The effects of jet amplitude, frequency and duty cycle on this recirculation area are investigated for two Reynolds numbers (Re=2070 and Re=2900). The results of this experimental study demonstrate that upstream actuation can be as efficient as actuation at the step edge when exciting the shear layer at its natural frequency. Moreover it is shown that it is possible to minimize both jet amplitude and duty cycle and still achieve optimal efficiency. With minimal amplitude and a duty-cycle as low as 10\\% the recirculation area is nearly canceled.

Gautier, Nicolas

2014-01-01

298

Large eddy simulation of the unsteady flow-field in an idealized human mouth-throat configuration.  

PubMed

The present study concerns the simulation and analysis of the flow field in the upper human respiratory system in order to gain an improved understanding of the complex flow field with respect to the process affecting drug delivery for medical treatment of the human air system. For this purpose, large eddy simulation (LES) is chosen because of its powerful performance in the transitional range of laminar and turbulent flow fields. The average gas velocity in a constricted tube is compared with experimental data (Ahmed and Giddens, 1983) and numerical data from Reynolds-averaged Navier-Stokes (RANS) equations coupled with low Reynolds number (LRN) ?-? model (Zhang and Kleinstreuer, 2003) and LRN shear-stress transport ?-? model (Jayaraju et al., 2007), for model validation. The present study emphasizes on the instantaneous flow field, where the simulations capture different scales of secondary vortices in different flow zones including recirculation zones, the laryngeal jet zone, the mixing zone, and the wall shear layer. It is observed that the laryngeal jet tail breaks up, and the unsteady motion of laryngeal jet is coupled with the unsteady distribution of secondary vortices in the jet boundary. The present results show that it is essential to study the unsteady flow field since it strongly affects the particle flow in the human upper respiratory system associated with drug delivery for medical treatment. PMID:21937045

Cui, X G; Gutheil, E

2011-11-10

299

Methane emissions from MSW landfill with sandy soil covers under leachate recirculation and subsurface irrigation  

NASA Astrophysics Data System (ADS)

CH 4 emissions and leachate disposal are recognized as the two major concerns in municipal solid waste (MSW) landfills. Recently, leachate recirculation was attempted to accelerate land-filled waste biodegradation and thus enhanced landfill gas generation. Leachate irrigation was also conducted for volume reduction effectively. Nevertheless, the impacts of leachate recirculation and irrigation on landfill CH 4 emissions have not been previously reported. A field investigation of landfill CH 4 emissions was conducted on selected sandy soil cover with leachate recirculation and subsurface irrigation based on whole year around measurement. The average CH 4 fluxes were 311±903, 207±516, and 565±1460 CH 4 m -2 h -1 from site A without leachate recirculation and subsurface irrigation, lift B2 with leachate subsurface irrigation, and lift B1 with both leachate recirculation and subsurface irrigation, respectively. Both gas recovery and cover soil oxidation minimized CH 4 emissions efficiently, while the later might be more pronounced when the location was more than 5 m away from gas recovery well. After covered by additional clay soil layer, CH 4 fluxes dropped by approximately 35 times in the following three seasons compared to the previous three seasons in lift B2. The diurnal peaks of CH 4 fluxes occurred mostly followed with air or soil temperature in the daytimes. The measured CH 4 fluxes were much lower than those of documented data from the landfills, indicating that the influences of leachate recirculation and subsurface irrigation on landfill CH 4 emissions might be minimized with the help of a well-designed sandy soil cover. Landfill cover composed of two soil layers (clay soil underneath and sandy soil above) is suggested as a low-cost and effective alternative to minimize CH 4 emissions.

Zhang, Houhu; He, Pinjing; Shao, Liming

300

Automated liquid-liquid extraction by pneumatic recirculation on a centrifugal microfluidic platform.  

PubMed

In this technical note, a liquid-liquid extraction technique was performed using pneumatic liquid recirculation on a centrifugal microfluidic device. Non-contact pneumatic pumping enabled a multi-cycle liquid-liquid extraction process using aqueous iodine in a potassium iodide solution and hexadecane while requiring a minimal amount of space on the device. The extraction process was completely automated on the device following sample introduction and required only 50 s for each extraction cycle. The pumping rate achieved during liquid recirculation was 120 ± 10 ?L/min. A recycling process such as the one demonstrated would be difficult to implement in a conventional centrifugal microfluidic system. PMID:22845877

Kazarine, Alexei; Kong, Matthew C R; Templeton, Erin J; Salin, Eric D

2012-08-21

301

Chaotic mixing in a microchannel utilizing periodically switching electro-osmotic recirculating rolls  

NASA Astrophysics Data System (ADS)

In this study, active mixing in a microchannel with spatiotemporal variations in ? potential distributions was investigated theoretically. In this mixing system, the primary flow is a pressure-driven flow (i.e., parabolic flow), and the electro-osmotic recirculating rolls induced by the heterogeneous ? potential distributions act as the perturbation source. By timewise alterations of two different electro-osmotic recirculating flow fields, chaotic mixing can be induced. Blob deformation, Poincaré map, and Lyapunov exponent analyses were employed to describe the behaviors of the particle motion in this active mixing system. Finally, the optimal time-switching period was identified, which was also verified through direct numerical simulations.

Chang, Chih-Chang; Yang, Ruey-Jen

2008-05-01

302

Performance of the prototype gas recirculation system with built-in RGA for INO RPC system  

NASA Astrophysics Data System (ADS)

An open loop gas recovery and recirculation system has been developed for the INO RPC system. The gas mixture coming from RPC exhaust is first desiccated by passing through molecular sieve (3 Å+4 Å). Subsequent scrubbing over basic active alumina removes toxic and acidic contaminants. The Isobutane and Freon are then separated by diffusion and liquefied by fractional condensation by cooling up to -26C. A Residual Gas Analyser (RGA) is being used in the loop to study the performance of the recirculation system. The results of the RGA analysis will be discussed.

Bhuyan, M.; Datar, V. M.; Joshi, A.; Kalmani, S. D.; Mondal, N. K.; Rahman, M. A.; Satyanarayana, B.; Verma, P.

2012-01-01

303

Hybrid heat exchange for the compression capture of CO2 from recirculated flue gas  

SciTech Connect

An approach proposed for removal of CO2 from flue gas cools and compresses a portion of a recirculated flue-gas stream, condensing its volatile materials for capture. Recirculating the flue gas concentrates SOx, H2O and CO2 while dramatically reducing N2 and NOx, enabling this approach, which uses readily available industrial components. A hybrid system of indirect and direct-contact heat exchange performs heat and mass transfer for pollutant removal and energy recovery. Computer modeling and experimentation combine to investigate the thermodynamics, heat and mass transfer, chemistry and engineering design of this integrated pollutant removal (IPR) system.

Oryshchyn, Danylo B.; Ochs, Thomas L.; Summers, Cathy A.

2004-01-01

304

Estimated Costs and Returns for Catfish Farms with Recirculating Ponds Along the Upper Texas Coast.  

E-print Network

. The paddle wheels are included in the analysis as a risk reduction measure. I Aside from the paddle wheels, substantial aeration and mixing are provided by the recirculating water in each system. All farms are supplied with equipment to distrib LIte... of the recirculating system. Each pond is equipped with a 7.46 kW (10 hp) electric paddle wheel. During the summer growing season, all ponds are monitored daily for dissolved oxygen deficiency dur ?ng the early morning hours. CATSIM applies aeration if pond...

Lambregts, J.A.D.; Griffin, W.L.; Lacewell R.D.; Davis, J.T.; Clary, G.M.

1992-01-01

305

The PM2.5 chemical composition in an industrial zone included in a large urban settlement: main sources and local background.  

PubMed

Chemical analyses, receptor modeling and meteorological data were combined to determine the composition and sources of PM2.5 sampled daily in a large area in Italy characterized by a high number of heterogeneous industrial emissions and contiguous to a major urban center. The PM2.5 local background in the area, i.e. the common basic composition and concentrations of PM2.5, was determined. Factor analysis-multiple linear regression analysis (FA-MLRA) was used to identify and quantify the main PM sources. Groups of samples with similar source contributions were then sorted using cluster analysis. The potential source location and the influence of long range transport were investigated by using the conditional probability function (CPF) and the potential source contribution function (PSCF) respectively. On an annual basis, five sources of PM were found relevant. Industrial emissions accounted for 3% of PM mass, whereas the main contribution to PM was related to a combination of ammonium nitrate, combustion (54%) and road traffic (36%), mainly related to urban emissions. The PM2.5 background was estimated to account for 20 ?g m(-3). It comprises contributions of 55% ammonium nitrate and combustion, 46% road traffic, 6% fossil fuel combustion and 3% industrial emissions. Source contributions are influenced by both local atmospheric circulation and regional transport. PMID:24912903

Squizzato, Stefania; Masiol, Mauro; Visin, Flavia; Canal, Andrea; Rampazzo, Giancarlo; Pavoni, Bruno

2014-08-01

306

Dynamics of the large-scale open solar magnetic field and its specific features in the zone of the main active longitudes in 2006-2012  

NASA Astrophysics Data System (ADS)

The dynamics of the absolute global values (?) of the large-scale open solar magnetic field (LOSMF) fluxes at an interval of one solar rotation in 2006-2012 has been studied based on the Wilcox Solar Observatory data and using the ISOPAK original package for modeling the solar magnetic field. The reference points and the duration of the final quasi-biennial interval in cycle 23 (January 2006-May 2007; 17 months) and the phases of the cycle 24 minimum (May 2007-November 2009; 30 months), growth (November 2009-May 2012; 30 months), and the beginning of the maximum (May 2012-January 2013) have been determined. It has been indicated that the absolute values (?) decreased sharply at the beginning of the minimum, growth, and the maximum phases to ˜(2, 1.25, 0.75) × 1022 Mx, respectively. During the entire minimum phase, LOSMF corotated super-quasi-rigidly westward in the direction of solar rotation; at the beginning of the growth phase, this field started corotating mostly eastward. The LOSMF polarity reversal in the current cycle 24 started in May-June 2012 (CR 2123-2124), when fields of southern polarity rushed from the Sun's southern hemisphere toward the north. The statement that the solar cycle is a continuous series of quasi-biennial LOSMF intervals is confirmed. In particular, the minimum and growth phases are characterized by opposite LOSMF rotation directions, i.e., super-quasi-rigid corotation (twisting) and detwisting, with identical duration at least in cycle 24.

Ivanov, K. G.; Kharshiladze, A. F.

2013-11-01

307

Development and design of a fluidized bed/upflow sand filter configuration for use in recirculating aquaculture systems  

SciTech Connect

A fluidized bed/upflow sand filter configuration, was developed and designed for utilization in recirculating aquaculture system, specifically the soft-shell crab and soft-shell crawfish industries. These filters were selected and designed because of their ability to withstand clogging and still maintain high levels of water quality for aquaculture production. The effectiveness of sand grain size was used to evaluate fluidized bed filter performance with filter loadings ranging from 16 to 1285 pounds of crawfish per cubic foot of filter sand. A coarse sand grain size was recommended as a filter media because of it's ability to shear excessive biofilm growth from the and, thus prohibiting clogging from occurring within the filter bed. The fluidized bed/upflow sand filter combination was evaluated in terms of nitrification and oxygen consumption when used with a recirculating crab shedding system. The filter combination's carrying capacity (700 crabs per cubic foot of sand media) exceeded that observed with the submerged rock filter by more than 20 times and was largely explained by the filter's solids removal ability which significantly reduced the filter's oxygen loading rate (OLR). Nitrification rates with the filter combination were extremely high as total ammonia and nitrite levels remained below 1.0 mg-N/l. Verification of a volumetric loading criteria (150 pounds per cubic foot) for this filter combination was further established with performance data obtained from a commercial soft-shell crawfish facility. Water quality monitoring results indicated that the filters maintained total ammonia and nitrite levels below 1.0 mg-N/l under typical operating conditions. Shock loading, pH control, and over-feeding, rather than filter capacity, dominated water quality fluctuations, thereby indicating that the loading criteria was sufficient for commercial operation.

Burden, D.G.

1988-01-01

308

A Mathematical Model of Solute Coupled Water Transport in Toad Intestine Incorporating Recirculation of the Actively Transported Solute  

PubMed Central

A mathematical model of an absorbing leaky epithelium is developed for analysis of solute coupled water transport. The non-charged driving solute diffuses into cells and is pumped from cells into the lateral intercellular space (lis). All membranes contain water channels with the solute passing those of tight junction and interspace basement membrane by convection-diffusion. With solute permeability of paracellular pathway large relative to paracellular water flow, the paracellular flux ratio of the solute (influx/outflux) is small (2–4) in agreement with experiments. The virtual solute concentration of fluid emerging from lis is then significantly larger than the concentration in lis. Thus, in absence of external driving forces the model generates isotonic transport provided a component of the solute flux emerging downstream lis is taken up by cells through the serosal membrane and pumped back into lis, i.e., the solute would have to be recirculated. With input variables from toad intestine (Nedergaard, S., E.H. Larsen, and H.H. Ussing, J. Membr. Biol. 168:241–251), computations predict that 60–80% of the pumped flux stems from serosal bath in agreement with the experimental estimate of the recirculation flux. Robust solutions are obtained with realistic concentrations and pressures of lis, and with the following features. Rate of fluid absorption is governed by the solute permeability of mucosal membrane. Maximum fluid flow is governed by density of pumps on lis-membranes. Energetic efficiency increases with hydraulic conductance of the pathway carrying water from mucosal solution into lis. Uphill water transport is accomplished, but with high hydraulic conductance of cell membranes strength of transport is obscured by water flow through cells. Anomalous solvent drag occurs when back flux of water through cells exceeds inward water flux between cells. Molecules moving along the paracellular pathway are driven by a translateral flow of water, i.e., the model generates pseudo-solvent drag. The associated flux-ratio equation is derived. PMID:10919860

Larsen, Erik Hviid; Sørensen, Jakob Balslev; Sørensen, Jens Nørkær

2000-01-01

309

Microbial community distribution and extracellular enzyme activities in leach bed reactor treating food waste: effect of different leachate recirculation practices.  

PubMed

This study aimed at understanding the relationship between microbial community and extracellular enzyme activities of leach bed reactor (LBR) treating food waste under different leachate recirculation practices (once per day and continuous) and liquid to solid (L/S) ratios (1:1 and 0.5:1). Microbial community analysis using PCR-DGGE revealed that Lactobacillus sp., Bifidobacter sp., and Proteobacteria were the most abundant species. Number of phylotypes was higher in LBRs with intermittent recirculation; whereas, lower number of phylotypes dominated by the key players of degradation was observed with continuous recirculation. The L/S ratio of 1:1 significantly enhanced the volatile solids removal compared with 0.5:1; however, this effect was insignificant under once a day leachate recirculation. Continuous leachate recirculation with 1:1 L/S ratio significantly improved the organic leaching (240 g COD/kgvolatile solid) and showed distinct extracellular enzyme activities suitable for food waste acidogenesis. PMID:24972915

Xu, Su Yun; Karthikeyan, Obuli P; Selvam, Ammaiyappan; Wong, Jonathan W C

2014-09-01

310

The Spontaneous Formation of a Space-Filling Lattice of Large-Amplitude Vortices throughout the "Dead Zone" of a Protoplanetary Disk and the Role of the Lattice in Star and Planet Formation  

NASA Astrophysics Data System (ADS)

The annular region of a protoplanetary disk, approximately 5 - 12 AU from the protostar and within 1 or 2 pressure scale heights of the mid-plane, has too low a temperature to significantly ionize hydrogen gas and therefore to destabilize the near-Keplerian flow via the magneto-hydrodynamic instability (MRI). Because it is assumed that Keplerian flow is linearly stable and that no hydrodynamic features can arise spontaneously within this region and thereby aid in star formation by transporting angular momentum and energy radially, this region is known as the "dead zone". Here we show that the pronouncement of this region as "dead" is premature (to paraphrase Mark Twain). Baroclinic critical layers can occur in rotating, vertically-stratified, uni-directional shear flows such as that in a protoplanetary disk. They are special cases of neutrally stable eigenmodes. Baroclinic critical layers have logarithmic singularities in density and vertical velocity. They differ from barotropic critical layers associated with Kelvin's cats-eyes in constant-density, unidirectional shear flows, which form at locations where the shear flow velocity matches the eigenmode's phase speed and have singularities only in stream-wise velocities. Baroclinic critical layers are easily excited with no special tuning of parameters by perturbations from vortices or waves. Unlike barotropic critical layers the amplitudes of baroclinic layers become large by drawing energy from the background shear. In the case of protoplanetary disk, energy is extracted from the huge reservoir of kinetic energy in the near-Keplerian shear. The large vertical velocities in the critical layers, coupled with the Coriolis parameter create large-amplitude vortex layers. These layers often roll-up into large coherent vortices. The baroclinic critical layers' growth and roll-up are robust: they form in cylindrical and Cartesian geometries, in Boussinesq fluids and ideal gases, and in flows with uniform and non-uniform shear and vertical stratification. However, they do not form in numerical calculations with insufficient spatial resolution or large grid dissipation. For flows with uniform or nearly-uniform horizontal shear and for some profiles of Brunt-Vaisala frequency, the process of excitation, critical layer growth, roll-up and vortex creation can self-similarly self-replicate so that the entire 3D computational domain fills with a spatially periodic lattice of large-amplitude vortices. This self-replication occurs in flows that are linearly stable, and in particular, in near-Keplerian protoplanetary disks that are convectively and centrifugally linearly stable. Thus, a small, but finite-amplitude perturbation in the form of a wave or vortex fills the entire dead zone of the protoplanetary disk with large-amplitude coherent structures. This phenomenon was serendipitously discovered in calculations of protoplanetary disks and independently in calculations of planetary vortices in zonal flows, but the spontaneous formation of a vortex lattice also occurs in large Reynolds number laboratory flows such as circular and plane Couette flows.

Marcus, P. S.; Jiang, C.; Pei, S.; Hassanzadeh, P.

2012-12-01

311

Fracturing and hydrothermal alteration in normal fault zones  

Microsoft Academic Search

Large normal fault zones are characterized by intense fracturing and hydrothermal alteration. Displacement is localized in a slip zone of cataclasite, breccia and phyllonite surrounding corrugated and striated fault surfaces. Slip zone rock grades into fractured, but less comminuted and hydrothermally altered rock in the transition zone, which in turn grades abruptly into the wall rock. Fracturing and fluid flow

Ronald L. Bruhn; William T. Parry; William A. Yonkee; Troy Thompson

1994-01-01

312

SELECTIVE NOx RECIRCULATION FOR STATIONARY LEAN-BURN NATURAL GAS ENGINES  

SciTech Connect

The research program conducted at the West Virginia University Engine and Emissions Research Laboratory (EERL) is working towards the verification and optimization of an approach to remove nitric oxides from the exhaust gas of lean burn natural gas engines. This project was sponsored by the US Department of Energy, National Energy Technology Laboratory (NETL) under contract number: DE-FC26-02NT41608. Selective NOx Recirculation (SNR) involves three main steps. First, NOx is adsorbed from the exhaust stream, followed by periodic desorption from the aftertreatment medium. Finally the desorbed NOx is passed back into the intake air stream and fed into the engine, where a percentage of the NOx is decomposed. This reporting period focuses on the NOx decomposition capability in the combustion process. Although researchers have demonstrated NOx reduction with SNR in other contexts, the proposed program is needed to further understand the process as it applies to lean burn natural gas engines. SNR is in support of the Department of Energy goal of enabling future use of environmentally acceptable reciprocating natural gas engines through NOx reduction under 0.1 g/bhp-hr. The study of decomposition of oxides of nitrogen (NOx) during combustion in the cylinder was conducted on a 1993 Cummins L10G 240 hp lean burn natural gas engine. The engine was operated at different air/fuel ratios, and at a speed of 800 rpm to mimic a larger bore engine. A full scale dilution tunnel and analyzers capable of measuring NOx, CO{sub 2}, CO, HC concentrations were used to characterize the exhaust gas. Commercially available nitric oxide (NO) was used to mimic the NOx stream from the desorption process through a mass flow controller and an injection nozzle. The same quantity of NOx was injected into the intake and exhaust line of the engine for 20 seconds at various steady state engine operating points. NOx decomposition rates were obtained by averaging the peak values at each set point minus the baseline and finding the ratio between the injected NO amounts. It was observed that the air/fuel ratio, injected NO quantity and engine operating points affected the NOx decomposition rates of the natural gas engine. A highest NOx decomposition rate of 27% was measured from this engine. A separate exploratory tests conducted with a gasoline engine with a low air/fuel ratio yielded results that suggested, that high NOx decomposition rates may be possible if a normally lean burn engine were operated at conditions closer to stoichiometric, with high exhaust gas recirculation (EGR) for a brief period of time during the NOx decomposition phase and with a wider range of air/fuel ratios. Chemical kinetic model predictions using CHEMKIN were performed to relate the experimental data with the established rate and equilibrium models. NOx decomposition rates from 35% to 42% were estimated using the CHEMKIN software. This provided insight on how to maximize NOx decomposition rates for a large bore engine. In the future, the modeling will be used to examine the effect of higher NO{sub 2}/NO ratios that are associated with lower speed and larger bore lean burn operation.

Nigel Clark; Gregory Thompson; Richard Atkinson; Chamila Tissera; Matt Swartz; Emre Tatli; Ramprabhu Vellaisamy

2005-01-01

313

Next Generation Pressurized Oxy-Coal Combustion: High Efficiency and No Flue Gas Recirculation  

SciTech Connect

The Gas Technology Institute (GTI) has developed a pressurized oxy-coal fired molten bed boiler (MBB) concept, in which coal and oxygen are fired directly into a bed of molten coal slag through burners located on the bottom of the boiler and fired upward. Circulation of heat by the molten slag eliminates the need for a flue gas recirculation loop and provides excellent heat transfer to steam tubes in the boiler walls. Advantages of the MBB technology over other boilers include higher efficiency (from eliminating flue gas recirculation), a smaller and less expensive boiler, modular design leading to direct scalability, decreased fines carryover and handling costs, smaller exhaust duct size, and smaller emissions control equipment sizes. The objective of this project was to conduct techno-economic analyses and an engineering design of the MBB project and to support this work with thermodynamic analyses and oxy-coal burner testing. Techno-economic analyses of GTI’s pressurized oxy-coal fired MBB technology found that the overall plant with compressed CO2 has an efficiency of 31.6%. This is a significant increase over calculated 29.2% efficiency of first generation oxy-coal plants. Cost of electricity (COE) for the pressurized MBB supercritical steam power plant with CO2 capture and compression was calculated to be 134% of the COE for an air-coal supercritical steam power plant with no CO2 capture. This compares positively with a calculated COE for first generation oxy-coal supercritical steam power plants with CO2 capture and compression of 164%. The COE for the MBB power plant is found to meet the U.S. Department of Energy (DOE) target of 135%, before any plant optimization. The MBB power plant was also determined to be simpler than other oxy-coal power plants with a 17% lower capital cost. No other known combustion technology can produce higher efficiencies or lower COE when CO2 capture and compression are included. A thermodynamic enthalpy and exergy analysis found a number of modifications and adjustments that could provide higher efficiency and better use of available work. Conclusions from this analysis will help guide the analyses and CFD modeling in future process development. The MBB technology has the potential to be a disruptive technology that will enable coal combustion power plants to be built and operated in a cost effective way, cleanly with no carbon dioxide emissions. A large amount of work is needed to quantify and confirm the great promise of the MBB technology. A Phase 2 proposal was submitted to DOE and other sponsors to address the most critical MBB process technical gaps. The Phase 2 proposal was not accepted for current DOE support.

Rue, David

2013-09-30

314

Ocean thermal energy conversion plants: experimental and analytical study of mixing and recirculation  

Microsoft Academic Search

Ocean thermal energy conversion (OTEC) is a method of generating power using the vertical temperature gradient of the tropical ocean as an energy source. Experimental and analytical studies have been carried out to determine the characteristics of the temperature and velocity fields induced in the surrounding ocean by the operation of an OTEC plant. The condition of recirculation, i.e., the

G. H. Jirka; R. P. Johnson; D. J. Fry; D. R. F. Harleman

1977-01-01

315

Evaluation of commercial marine fish feeds for production of juvenile cobia in recirculating aquaculture systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

The effect of feeding three commercially available diets manufactured by three U.S. feed companies on production characteristics and body composition of juvenile cobia Rachycentron canadum reared in recirculating aquaculture systems (RAS) was evaluated in a 57 d growth trial. Juvenile cobia (26.7 +...

316

Influence of gas velocity on particulate fouling of exhaust gas recirculation coolers  

Microsoft Academic Search

The objective of this research is to study the influence of gas flow velocity on particulate fouling of exhaust gas recirculation (EGR) coolers. An experimental setup has been designed and constructed to simulate particulate fouling in EGR coolers in diesel engines. The setup consists of soot generator, gas\\/particle flow heater, testing section for EGR coolers and finally an exhaust system.

M. S. Abd-Elhady; T. Zornek; M. R. Malayeri; S. Balestrino; P. G. Szymkowicz; H. Müller-Steinhagen

2011-01-01

317

On thermoelectric power conversion from heat re-circulating combustion systems F. J. Weinberg  

E-print Network

On thermoelectric power conversion from heat re-circulating combustion systems F. J. Weinberg Fax: 4420 7594 5604 Word count: 3750 Diags. equivalent: 1600 5350 #12;On thermoelectric power the absolute maximum efficiency of energy conversion by thermoelectric devices that operate as part of the heat

318

tinual recirculation. The strain measurements from the compliant members of the freely rotating 4-bar  

E-print Network

#12;tinual recirculation. The strain measurements from the compliant members of the freely rotating of the empirical function relating strain measurement to leg configura- tion. Section 4 concerns the data for measurement of strain, := R+ , which varies as a function of leg configuration. The gauge is located

Lin, Pei-Chun

319

Disinfection of water in recirculating aquaculture systems with peracetic acid (PAA)  

Technology Transfer Automated Retrieval System (TEKTRAN)

The disinfection behaviour of peracetic acid (PAA) in recirculating aquaculture systems (RAS) was investigated. Peracetic acid is a strong oxidizing agent found in various concentrations in different products. Three Wofasteril PAA products (E400 (c), Lspecical; AC 150) were tested in vitro for the...

320

Improvement of anaerobic digester performance by wastewater recirculation through an aerated membrane.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Swine wastewater from an anaerobic digester was recirculated through a silicone hose located in an external aeration chamber to determine its effect on wastewater malodorants and biogas composition. The silicone hose acted as a semipermeable membrane for the passage of small molecules. In the first...

321

RECIRCULATING AQUACULTURE SYSTEM FOR MARINE FINFISH RESEARCH AT HARBOR BRANCH OCEANOGRAPHIC INSTITUTION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Recirculating aquaculture systems (RAS,) for both commercial and experimental uses, has been under development in many parts of the world in response to several driving forces. With regards to sites for coastal aquaculture, the scarcity of affordable land has driven aquaculture endeavors for marine ...

322

Low-head recirculating aquaculture system for juvenile red drum production  

Technology Transfer Automated Retrieval System (TEKTRAN)

The USDA Agricultural Research Service and the Center for Aquaculture and Stock Enhancement at Harbor Branch Oceanographic Institute-FAU (HBOI-FAU) are collaborating to evaluate low-head recirculating aquaculture system designs to intensively produce red drum juveniles as part of the Florida Fish an...

323

Geosmin causes off-flavour in arctic charr in recirculating aquaculture systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

The “earthy” and “muddy” off-flavors in pond-reared fish are due to the presence of geosmin or 2-methylisoborneol (MIB) in the flesh of the fish. Similar off-flavors have been reported in fish raised in recirculating aquaculture systems (RAS); however, little information is available regarding the ...

324

Beam position measurement in the CEBAF recirculating linacs by use of pseudorandom pulse sequences  

SciTech Connect

The recirculating linear accelerator at CEBAF presents unique problems in beam position measurement. As many as five beams with different energies may be simultaneously in the linac. Modulation of the beam intensity by pseudorandom pulse sequences offers a simple, effective method for distinguishing between the individual beamlets.

Barry, W.C.; Heefner, J.W.; Jones, G.S.; Perry, J.E.; Rossmanith, R.

1990-08-01

325

Effect of automatic recirculation flow control on the transient response for Lungmen ABWR plant  

Microsoft Academic Search

In this study the automatic mode of the recirculation flow control system (RFCS) for the Lungmen ABWR plant has been modeled and incorporated into the basic RETRAN-02 system model. The integrated system model is then used to perform the analyses for the two transients in which the automatic RFCS is involved. The two transients selected are: (1) one reactor internal

Yih-Chyun Tzang; Ray-Feng Chiang; Yuh-Ming Ferng; Bau-Shei Pei

2009-01-01

326

Suction-recirculation device for stabilizing particle flows within a solar powered solid particle receiver  

DOEpatents

A suction-recirculation device for stabilizing the flow of a curtain of blackened heat absorption particles falling inside of a solar receiver with an open aperture. The curtain of particles absorbs the concentrated heat from a solar mirror array reflected up to the receiver on a solar power tower. External winds entering the receiver at an oblique angle can destabilize the particle curtain and eject particles. A fan and ductwork is located behind the back wall of the receiver and sucks air out through an array of small holes in the back wall. Any entrained particles are separated out by a conventional cyclone device. Then, the air is recirculated back to the top of the receiver by injecting the recycled air through an array of small holes in the receiver's ceiling and upper aperture front wall. Since internal air is recirculated, heat losses are minimized and high receiver efficiency is maintained. Suction-recirculation velocities in the range of 1-5 m/s are sufficient to stabilize the particle curtain against external wind speeds in excess of 10 m/s.

Kolb, Gregory J. (Albuquerque, NM)

2012-02-07

327

Design and Evaluation of Recirculating Water Systems for Maintenance and Propagation of Freshwater Mussels  

Microsoft Academic Search

A complete system for culturing, rearing, and holding juvenile and adult freshwater mussels (Unionidae) was designed and evaluated for use at hatcheries and research facilities. The system includes air delivery, water conditioning and delivery, algal culturing and automated algal feed delivery, and air-driven water-recirculating units. These systems are appropriate for holding and conditioning adult mussels for spawning, as well as

William F. Henley; Lora L. Zimmerman; Richard J. Neves; Mark R. Kidd

2001-01-01

328

Electron recirculation in electrostatic multicusp systems: II. System performance scaling of one-dimensional rollover wells  

Microsoft Academic Search

In an earlier paper a comprehensive study was made of the recirculation and losses of electrons in their flow through simple inverse power-law potential wells bounded by similarly inverse power-law dependent magnetic fields. This study examined electron flow and loss behavior in the simplest approximation invoked to describe Polywell confinement systems. The importance of this study, and of the present

R. W. Bussard; K. E. King

1992-01-01

329

Researchers evaluate low-energy recirculating system for inland production of marine finfish juveniles  

Technology Transfer Automated Retrieval System (TEKTRAN)

The low-energy recirculating aquaculture system consists of nine separate modules which utilize the double drain fish culture tank paired to a moving bed biofilter. The nine fiberglass tanks are five feet in diameter and normal water depth is about three feet for a total tank volume of approximately...

330

PERFORMANCE CHARACTERISTICS OF THE FLOATING BEAD BIOCLARIFIER IN A RECIRCULATING AQUACULTURE SYSTEM  

Technology Transfer Automated Retrieval System (TEKTRAN)

In a recirculating aquaculture production system an important requirement is an efficient and effective process for water treatment. The objective of this study was to evaluate the nitrification and solids removal performance of a propeller-wash floating media biofilters in a two-tank small-scale ti...

331

Experimental Bleaching of a Reef-Building Coral Using a Simplified Recirculating Laboratory Exposure System  

EPA Science Inventory

Determining stressor-response relationships in reef building corals is a critical need for researchers because of global declines in coral reef ecosystems. A simplified recirculating coral exposure system for laboratory testing of a diversity of species and morphologies of reef b...

332

Design keys of a recent recirculating facility built in Chile operating with fluidized bed biofilters  

Microsoft Academic Search

The fast evolution of recirculation systems for salmonids has challenged the engineering companies to develop new and better design and engineering practices, to improve the water quality and system flexibility. One of the major factors that affect the water quality parameters is the total suspended solids produced within the system. The design of water flow from the water inlet into

Rafael I. Morey

2009-01-01

333

Observations on side-swimming rainbow trout Oncorhynchus mykiss in water recirculation aquaculture systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

During a controlled 6-month study using six replicated water recirculation aquaculture systems (WRAS), it was observed that rainbow trout Oncorhynchus mykiss in all WRAS exhibited a higher-than-normal prevalence of side-swimming (i.e. controlled, forward swimming, but with misaligned orientation suc...

334

Ozonation of a recirculating rainbow trout culture system II. Effects on microscreen filtration and water quality  

Microsoft Academic Search

Ozone was added to water in a recirculating rainbow trout (Oncorhynchus mykiss) culture system just prior to the culture tanks in order to oxidize nitrite and organic material, improve overall water quality, and assist removal of solids across the microscreen filter. Data from four 8-week studies on ozonation and an 8-week no ozone control indicated that adding ozone reduced the

Steven T. Summerfelt; Joseph A. Hankins; Amy L. Weber; Martin D. Durant

1997-01-01

335

Growth and survival of larval and juvenile cobia Rachycentron canadum in a recirculating raceway system  

Microsoft Academic Search

Cobia Rachycentron canadum is a fast-growing, pelagic marine species that has recently attracted aquaculturists in both the research and commercial sectors. The typical method of grow-out for this species is in outdoor systems where production is limited to locations and seasons conducive for adequate growth and survival. Expanding the culture of cobia to indoor recirculating aquaculture systems (RAS) would allow

Cynthia K. Faulk; Jeffrey B. Kaiser; G. Joan Holt

2007-01-01

336

PERFORMANCE OF A ROTATING BIOLOGICAL CONTRACTOR IN TILAPIA RECIRCULATING AQUACULTURE SYSTEM  

Technology Transfer Automated Retrieval System (TEKTRAN)

This paper describes the performance characteristics of an industrial-scale air-driven rotating biological contactor (RBC) installed in a recirculating aquaculture system (RAS) rearing tilapia at 28 oC. This 3-staged RBC system was configured with stages 1 and 2 possessing approximately the same to...

337

Adaptive Air Charge Estimation for Turbocharged Diesel Engines without Exhaust Gas Recirculation  

E-print Network

Adaptive Air Charge Estimation for Turbocharged Diesel Engines without Exhaust Gas Recirculation an adaptive observer for in-cylinder air charge estimation for turbocharged diesel engines without exhaust gas (734) 764-4256 1 #12;Storset et al.- Adaptive Air Charge Est. for TC Diesel Engines 2 1 Introduction

Stefanopoulou, Anna

338

Fulminant hepatic failure following marijuana drug abuse: Molecular adsorbent recirculation system therapy  

PubMed Central

Marijuana is used for psychoactive and recreational purpose. We report a case of fulminant hepatic failure following marijuana drug abuse who recovered following artificial support systems for acute liver failure. There is no published literature of management of marijuana intoxication with molecular adsorbent recirculation system (MARS). MARS is effective and safe in patients with fulminant hepatic failure following marijuana intoxication. PMID:24049281

Swarnalatha, G.; Pai, S.; Ram, R.; Dakshinamurty, K. V.

2013-01-01

339

Fulminant hepatic failure following marijuana drug abuse: Molecular adsorbent recirculation system therapy.  

PubMed

Marijuana is used for psychoactive and recreational purpose. We report a case of fulminant hepatic failure following marijuana drug abuse who recovered following artificial support systems for acute liver failure. There is no published literature of management of marijuana intoxication with molecular adsorbent recirculation system (MARS). MARS is effective and safe in patients with fulminant hepatic failure following marijuana intoxication. PMID:24049281

Swarnalatha, G; Pai, S; Ram, R; Dakshinamurty, K V

2013-09-01

340

Applying rotary jet heads for mixing and mass transfer in a forced recirculation tank reactor system  

Microsoft Academic Search

An approximation to an ideally mixed tank reactor can be obtained by vigorous stirring with mechanical mixers. For an aerated reactor the gas dispersion contributes to the mixing process. Mixing can also be achieved by recirculation of a portion of the liquid through either an internal or an external loop.In this study, we determine mixing times in water and CMC

Mikkel Nordkvist; Thomas Grotkjær; Jan S. Hummer; John Villadsen

2003-01-01

341

Oxygen mass balance in a recirculation aquaculture system for raising European Wels (Silurus glanis L.)  

Microsoft Academic Search

The growth of the European Wels or sheat-fish (Silurus glanis L.) was eva- luated in a recirculation aquaculture system situated in a greenhouse. Recir- culation aquaculture system components were evaluated in terms of oxygen use and generation. Oxygen gradients revealed the main fault of the originally constructed system elements - mechanical and biological filters. The influen- ce of organic matter

Viktoras Mongirdas; Albinas Kusta

2006-01-01

342

Three simple culture devices for aquatic invertebrates and fish larvae with continuous recirculation of the medium  

Microsoft Academic Search

The 3 culturing devices described are based on the principle of the classic air-water lift, which facilitates continuous recirculation and aeration of the cultivation medium. The first device is a “circulation cylinder”, convenient for hatching eggs of the brine shrimp Artemia salina and for culturing algae and protozoans. In the second device, an internal basket (i.e., a glass cylinder with

P. Sorgeloos; G. Persoone

1972-01-01

343

The Effectiveness of Aeration Recirculation in Controlling VOC Emissions from Publicly Owned Treatment Works  

Microsoft Academic Search

The effects of aeration recirculation on oxygen transfer and the fate of five volatile organic compounds (VOCs) commonly found in publicly owned treatment works (POTWs) influent are studied using various modeling approaches. The five compounds are benzene, chloroform, methylene chloride, toluene, and trichloroethylene. The models predict that the overall oxygen transfer efficiency can be increased by 96.7% at 50% aeration

Hongwei Zhu; Tim C. Keener; Tim L. Orton; Paul L. Bishop; Soon Jai Khang; Kaniz Siddiqui

1997-01-01

344

Conservation principles suspended solids distribution modelling to support ATS introduction on a recirculating WWTP  

Microsoft Academic Search

A model for the description of the SS distribution in a full-scale recirculating activated sludge WWTP was developed. The model, based on conservation principles, uses on-line plant data as model inputs, and provides a prediction of the SS load in the inlet to the secondary clarifiers and the SS distribution in the WWTP as outputs. The calibrated model produces excellent

Krist V. Gernaey; Marinus K. Nielsen; Dines Thornberg; Benny Hook; Thomas Munk-Nielsen; Pernille Ingildsen; Sten Bay Jørgensen

345

INTERACTION BETWEEN FREESURFACE AERATION AND CAVITY RECIRCULATION IN SKIMMING FLOWS DOWN STEPPED CHUTES  

Microsoft Academic Search

Experimental investigations have been conducted in stepped spillway model chutes assembled at the National Laboratory of Civil Eng ineering (LNEC), Lisbon, at Nihon University (UNIHON), Tokyo and at the University of Queensland (UQLD), Australia. In the present paper, the research is focussed on the interactions between entrained air bubbles and cavity recirculation in the skimming flow regime. The experimental results

Jorge Matos; Youichi Yasuda; Hubert Chanson

346

Problem of Vain Energy Consumption in a VAV Air Conditioning System Shared By an Inner Zone and Exterior Zone  

E-print Network

In northern China, there are a large number of space buildings divided in inner zone and exterior zone based on usage requirements. The exterior zone needs to be heated in winter and cooled in summer, while the inner zone needs to be cooled both...

Wenji, G.; Ling, C.; Dongdong, L.; Mei, S.; Li, Z.

2006-01-01

347

Temperate Oceans : Light Zones  

NSDL National Science Digital Library

This reference provides an overview of the three zones into which the ocean can be divided based on the amount of light recieved: the sunlit (or euphotic) zone, the twilight (or disphotic) zone, and the midnight (or aphotic) zone. The descriptions are accompanied by diagrams and a brief listing of the organisms that live in each zone.

2007-12-12

348

Twin Convergence Zones  

NASA Technical Reports Server (NTRS)

NASA's QuikSCAT satellite has confirmed a 30-year old largely unproven theory that there are two areas near the equator where the winds converge year after year and drive ocean circulation south of the equator. By analyzing winds, QuikSCAT has found a year-round southern and northern Intertropical Convergence Zone. This find is important to climate modelers and weather forecasters because it provides more detail on how the oceans and atmosphere interact near the equator. The Intertropical Convergence Zone (ITCZ) is the region that circles the Earth near the equator, where the trade winds of both the Northern and Southern Hemispheres come together. North of the equator, strong sun and warm water of the equator heats the air in the ITCZ, drawing air in from north and south and causing the air to rise. As the air rises it cools, releasing the accumulated moisture in an almost perpetual series of thunderstorms. Satellite data, however, has confirmed that there is an ITCZ north of the equator and a parallel ITCZ south of the equator. Variation in the location of the ITCZ is important to people around the world because it affects the north-south atmospheric circulation, which redistributes energy. It drastically affects rainfall in many equatorial nations, resulting in the wet and dry seasons of the tropics rather than the cold and warm seasons of higher latitudes. Longer term changes in the ITCZ can result in severe droughts or flooding in nearby areas. 'The double ITCZ is usually only identified in the Pacific and Atlantic Oceans on a limited and seasonal basis,' said Timothy Liu, of NASA's Jet Propulsion Laboratory and California Institute of Technology, Pasadena, Calif., and lead researcher on the project. In the eastern Pacific Ocean, the southern ITCZ is usually seen springtime. In the western Atlantic Ocean, the southern ITCZ was recently clearly identified only in the summertime. However, QuikSCAT's wind data has seen the southern ITCZ in all seasons across the entire Atlantic Ocean and the eastern Pacific. 'QuikSCAT's wind data confirms there is a double ITCZ, and that they exist all year long,' Liu said. This is a major find for the science community, as the existence, location, and seasonality of the double ITCZ had remained controversial since 1969. full text: Satellite Sees Double Zones of Converging Tropical Winds around The World For more about convergence zones, read: The Intertropical Convergence Zone and Convergence Zones: Where the Action Is Image courtesy Liu and Xie, NASA JPL

2002-01-01

349

The upper intertidal zone  

NSDL National Science Digital Library

The upper intertidal zone is exposed most of the time and will become submerged only during high tide. This zone is least abundant of the intertidal zones but contains some mollusks, barnacles, and other animals adapted to avoid drying out.

Katie Hale (California State University, Fullerton; Student, Biological Sciences)

2007-01-04

350

The upper intertidal zone  

NSDL National Science Digital Library

The upper intertidal zone is exposed most of the time and will become submerged only during high tide. This zone is least abundant of the intertidal zones but contains some mollusks, barnacles, and other animals adapted to avoid drying out.

Katie Hale (CSUF; Biological Sciences)

2007-06-08

351

The bottom intertidal zone  

NSDL National Science Digital Library

The bottom intertidal area remains under water except during low tides. This zone is most abundant of the intertidal zones and contains seaweeds and other plants, invertebrates, and fishes. The bottom zone is subject to the most intense wave action.

Katie Hale (California State University, Fullerton; Student, Biological Sciences)

2007-01-04

352

The bottom intertidal zone  

NSDL National Science Digital Library

The bottom intertidal area remains under water except during low tides. This zone is most abundant of the intertidal zones and contains seaweeds and other plants, invertebrates, and fishes. The bottom zone is subject to the most intense wave action.

Katie Hale (CSUF; Biological Sciences)

2007-06-08

353

Effects of non-uniform root zone salinity on water use, Na+ recirculation, and Na+ and H+ flux in cotton  

PubMed Central

A new split-root system was established through grafting to study cotton response to non-uniform salinity. Each root half was treated with either uniform (100/100?mM) or non-uniform NaCl concentrations (0/200 and 50/150?mM). In contrast to uniform control, non-uniform salinity treatment improved plant growth and water use, with more water absorbed from the non- and low salinity side. Non-uniform treatments decreased Na+ concentrations in leaves. The [Na+] in the ‘0’ side roots of the 0/200 treatment was significantly higher than that in either side of the 0/0 control, but greatly decreased when the ‘0’ side phloem was girdled, suggesting that the increased [Na+] in the ‘0’ side roots was possibly due to transportation of foliar Na+ to roots through phloem. Plants under non-uniform salinity extruded more Na+ from the root than those under uniform salinity. Root Na+ efflux in the low salinity side was greatly enhanced by the higher salinity side. NaCl-induced Na+ efflux and H+ influx were inhibited by amiloride and sodium orthovanadate, suggesting that root Na+ extrusion was probably due to active Na+/H+ antiport across the plasma membrane. Improved plant growth under non-uniform salinity was thus attributed to increased water use, reduced leaf Na+ concentration, transport of excessive foliar Na+ to the low salinity side, and enhanced Na+ efflux from the low salinity root. PMID:22200663

Kong, Xiangqiang; Luo, Zhen; Dong, Hezhong; Eneji, A. Egrinya

2012-01-01

354

Root Apex Transition Zone As Oscillatory Zone  

PubMed Central

Root apex of higher plants shows very high sensitivity to environmental stimuli. The root cap acts as the most prominent plant sensory organ; sensing diverse physical parameters such as gravity, light, humidity, oxygen, and critical inorganic nutrients. However, the motoric responses to these stimuli are accomplished in the elongation region. This spatial discrepancy was solved when we have discovered and characterized the transition zone which is interpolated between the apical meristem and the subapical elongation zone. Cells of this zone are very active in the cytoskeletal rearrangements, endocytosis and endocytic vesicle recycling, as well as in electric activities. Here we discuss the oscillatory nature of the transition zone which, together with several other features of this zone, suggest that it acts as some kind of command center. In accordance with the early proposal of Charles and Francis Darwin, cells of this root zone receive sensory information from the root cap and instruct the motoric responses of cells in the elongation zone. PMID:24106493

Baluška, František; Mancuso, Stefano

2013-01-01

355

Zoning, equity, and public health.  

PubMed Central

Zoning, the most prevalent land use planning tool in the United States, has substantial implications for equity and public health. Zoning determines where various categories of land use may go, thereby influencing the location of resulting environmental and health impacts. Industrially zoned areas permit noxious land uses and typically carry higher environmental burdens than other areas. Using New York City as a case study, the author shows that industrial zones have large residential populations within them or nearby. Noxious uses tend to be concentrated in poor and minority industrial neighborhoods because more affluent industrial areas and those with lower minority populations are rezoned for other uses, and industrial zones in poorer neighborhoods are expanded. Zoning policies, therefore, can have adverse impacts on public health and equity. The location of noxious uses and the pollution they generate have ramifications for global public health and equity; these uses have been concentrated in the world's poorer places as well as in poorer places within more affluent countries. Planners, policymakers, and public health professionals must collaborate on a worldwide basis to address these equity, health, and land use planning problems. PMID:11441726

Maantay, J

2001-01-01

356

Future float zone development in industry  

NASA Technical Reports Server (NTRS)

The present industrial requirements for float zone silicon are summarized. Developments desired by the industry in the future are reported. The five most significant problems faced today by the float zone crystal growth method in industry are discussed. They are economic, large diameter, resistivity uniformity, control of carbon, and swirl defects.

Sandfort, R. M.

1980-01-01

357

A Spatial Model for Marine Park Zoning  

Microsoft Academic Search

The complexity of stakeholder interests, governing structures, and biophysical processes often present challenges in adopting multiple-use approaches in the management of large marine areas. Marine zoning plans provide a mechanism for ensuring the realization of conservation objectives under spatially varying levels of resource use. The need for a systematic and transparent approach to zone planning highlights the role of Geographical

Eleanor M. Bruce; Ian G. Eliot

2006-01-01

358

Manipulating flow separation: sensitivity of stagnation points, separatrix angles and recirculation area to steady actuation.  

PubMed

A variational technique is used to derive analytical expressions for the sensitivity of several geometric indicators of flow separation to steady actuation. Considering the boundary layer flow above a wall-mounted bump, the six following representative quantities are considered: the locations of the separation point and reattachment point connected by the separatrix, the separation angles at these stagnation points, the backflow area and the recirculation area. For each geometric quantity, linear sensitivity analysis allows us to identify regions which are the most sensitive to volume forcing and wall blowing/suction. Validations against full nonlinear Navier-Stokes calculations show excellent agreement for small-amplitude control for all considered indicators. With very resemblant sensitivity maps, the reattachment point, the backflow and recirculation areas are seen to be easily manipulated. By contrast, the upstream separation point and the separatrix angles are seen to remain extremely robust with respect to external steady actuation. PMID:25294968

Boujo, E; Gallaire, F

2014-10-01

359

A recirculating equilibrium procedure for determining organic compound solubility in supercritical fluids. Anthracene in carbon dioxide  

SciTech Connect

An instrumental recirculation technique was developed to measure the solubility of organic compounds and thus their potential extractability, in supercritical fluids over the pressure range of 80--500 bar. Anthracene, whose solubility is well defined, was chosen as a model compound to be used in evaluating the recirculation technique. Its solubility in supercritical carbon dioxide was measured at 40, 50, and 60 C using an off-line spectroscopic technique. The solubility data were found to have good precision and to agree with published results. Anthracene solubility increased with pressure but was more enhanced by higher temperature. An upper crossover pressure of the isotherms due to retrograde vaporization that agreed with theory was found at 142.2 bar.

Hampson, J.W. [Dept. of Agriculture, Philadelphia, PA (United States)] [Dept. of Agriculture, Philadelphia, PA (United States)

1996-01-01

360

LUX - A recirculating linac-based ultrafast X-ray source  

SciTech Connect

We describe the design of a proposed source of ultra-fast synchrotron radiation x-ray pulses based on a recirculating superconducting linac, with an integrated array of ultrafast laser systems. The source produces x-ray pulses with duration of 10-50 fs at a 10 kHz repetition rate, with tunability from EUV to hard x-ray regimes, and optimized for the study of ultra-fast dynamics. A high-brightness rf photocathode provides electron bunches. An injector linac accelerates the beam to the 100 MeV range, and is followed by four passes through a 700 MeV recirculating linac. Ultrafast hard x-ray pulses are obtained by a combination of electron bunch manipulation, transverse temporal correlation of the electrons, and x-ray pulse compression. EUV and soft x-ray pulses as short as 10 fs are generated in a harmonic-cascade free electron laser scheme.

Corlett, J.N.; Barletta, W.A.; DeSantis, S.; Doolittle, L.; Fawley, W.M.; Green, M.A.; Heimann, P.; Leone, S.R.; Lidia, S.; Li, D.; Parmigiani, F.; Ratti, A.; Robinson, K.; Schoenlein, R.; Staples, J.; Wan, W.; Wells, R.; Wilcox, R.; Wolski, A.; Zholents, A.

2003-08-01

361

Identification and origin of plant pathogenic microorganisms in recirculating nutrient solutions.  

PubMed

Avoidance of root-infecting microorganisms was originally considered one of the advantages of cultivation of crops in a soilless, recirculating nutrient solution. However, to date, four viral, three bacterial and 21 fungal pathogens have been identified as causal agents of root disease in hydroponically-grown crops. Root-infecting fungi, particularly those which produce a motile stage known as a zoospore, have been the primary pathogens associated with extensive crop losses. Documented sources of these root pathogens in hydroponic systems include peat, surface water such as rivers and streams, and insects. The severity of disease caused by these introduced root pathogens is primarily governed by the genetic susceptibility of each crop and the temperature of the recirculating nutrient solution. PMID:11540205

Stanghellini, M E; Rasmussen, S L

1994-11-01

362

Design and performance characteristics of a low-head recirculating aquaculture tank system for low salinity finfish production  

Technology Transfer Automated Retrieval System (TEKTRAN)

Water treatment components of a recirculating aquaculture system (RAS) consist mainly of: solid removal devices, biofiltration, aeration, degassing units, and water distribution. For each component, multiple options are available and the selection is based on system volume, system hydrodynamics, fis...

363

The design and construction of an open channel recirculating water tank for the study of biological hydrocarbons  

E-print Network

This project chronicles the design and construction of a small scale recirculating water tank for the purpose of studying biological hydrodynamics. Currently available systems were analyzed and studied prior to developing ...

Hennessey, Thomas V. (Thomas Vincent), III

2005-01-01

364

Investigations into the reproductive performance and larval rearing of the Brown shrimp, Farfantepenaeus aztecus, using closed recirculating systems  

E-print Network

The effects of unilateral eyestalk ablation, diets and sex ratios were evaluated on two wild populations of Farfantepenaeus aztecus in a closed recirculating maturation system. Ovarian development and spawning frequencies of ablated females in both...

Gandy, Ryan Leighton

2005-02-17

365

Block-implicit multigrid calculation of three-dimensional recirculating flows  

Microsoft Academic Search

An efficient finite difference calculation procedure for three-dimensional recirculating flows is presented. The algorithm is based on a coupled solution of the three-dimensional momentum and continuity equations in primitive variables by the multigrid technique. A symmetrical coupled Gauss-Siedel technique is used for iterations and is observed to provide good rates of smoothing. Calculations were made of the fluid motion in

S. P. Vanka

1985-01-01

366

Nitrification performance of nitrifiers immobilized in PVA (polyvinyl alcohol) for a marine recirculating aquarium system  

Microsoft Academic Search

Characteristics of the nitrification processes with immobilized nitrifier consortium were evaluated for the development of the marine recirculating aquarium system. In order to evaluate the activity of the nitrifiers, a 45 l airlift reactor was used for the determination of ammonia removal rate for 40 days of operation. The ammonia removal efficiency rate was 98% with 23 g ammonia-N\\/m3\\/day, respectively.

Jae-Koan Seo; Il-Hyong Jung; Mi-Ryung Kim; Byong Jin Kim; Soo-Wan Nam; Sung-Koo Kim

2001-01-01

367

Diffusion Combustion of Liquid Heptane in a Small Tube with and Without Heat Recirculating  

Microsoft Academic Search

To understand diffusion flame characteristics in a small tube, combustion of liquid n-heptane and air was experimentally and numerically studied. A tube of ID 4 mm and OD 6 mm made of quartz was used as the burner. Liquid n-heptane was delivered into a capillary from a syringe pump. Stable flames were established inside the burner with and without heat recirculating. Additionally,

Li Junwei; Huang Jinghuai; Zhao Dan; Zhao Junying; Yan Mi; Wang Ningfei

2012-01-01

368

Loop-synchronous polarization scrambling technique for simulating polarization effects using recirculating fiber loops  

Microsoft Academic Search

A loop-synchronous polarization-scrambling technique has been proposed for the purpose of simulating polarization effects in straight-line systems using recirculating loops. This technique uses a fast polarization controller within a fiber loop. The polarization controller changes its transmission matrix after each round trip of the optical signal circulating through the loop; thus, the periodic polarization transform of the loop is avoided.

Q. Yu; L.-S. Yan; S. Lee; Y. Xie; A. E. Willner

2003-01-01

369

An evaluation of commercially available biological filters for recirculating aquaculture systems  

Microsoft Academic Search

Three different commercially available biological filters were evaluated in triplicate on a 60m3 tank-based Tilapia system under commercial warmwater growout conditions. The study was performed at the North Carolina State University Fish Barn—a commercial scale research and demonstration recirculating aquaculture facility operated by the department of Biological and Agricultural Engineering. Total ammoniacal nitrogen (TAN) removal rates were determined for the

Todd C. Guerdat; Thomas M. Losordo; John J. Classen; Jason A. Osborne; Dennis P. DeLong

2010-01-01

370

Heat and mass transfer in turbulent flows with several recirculated flow eddies  

Microsoft Academic Search

Numerical modeling of the concentration and temperature distribution in axial symmetrical systems with several recirculated flow eddies, which is based on various 2D stationary k-? models and commercial codes, e.g. ANSYS and FLUENT, leads to results, which are significantly different from experimental data. Therefore additional user-defined subroutines were included in the commercial program code to improve the turbulent heat and

E. Baake; B. Nacke; A. Jakovics; A. Umbrashko

2001-01-01

371

High gradient magnetic beneficiation of dry pulverized coal via upwardly directed recirculating fluidization  

DOEpatents

This invention relates to an improved device and method for the high gradient magnetic beneficiation of dry pulverized coal, for the purpose of removing sulfur and ash from the coal whereby the product is a dry environmentally acceptable, low-sulfur fuel. The process involves upwardly directed recirculating air fluidization of selectively sized powdered coal in a separator having sections of increasing diameters in the direction of air flow, with magnetic field and flow rates chosen for optimum separations depending upon particulate size.

Eissenberg, David M. (Oak Ridge, TN); Liu, Yin-An (Opelika, AL)

1980-01-01

372

Water Treatment and Performance Characteristics Evaluation of a Pilot-Scale Recirculating Aquaculture System  

Microsoft Academic Search

To minimize the impact on the environment and land requirements, a pilot-scale recirculating aquaculture system was engineered and investigated in a greenhouse. The system included a three-step particulates separation device, fluidized bed reactors (FBR), UV treatment and cooling. Japanese flounder (Paralichthys olivaceus) were raised from initial mean weight 4.9 plusmn 0.6g to final mean weight 35.8 plusmn 14.6g after 140

Yan Zaisheng; Liu Changfa; Wang Shihe; He Jie; Liu Yuan; Zhang Liyong; Zhang Junxin

2008-01-01

373

Regulating the hydrolysis of organic wastes by micro-aeration and effluent recirculation  

Microsoft Academic Search

In this study, the effects of micro-aeration and liquid recirculation on the hydrolysis of vegetable and flower wastes during two-phase solid–liquid anaerobic digestion were assessed. To accomplish this, we evaluated the hydrolysis of five batches of waste that were treated under the following conditions: anaerobic, insufficient micro-aeration (aeration for 5min every 24h), and sufficient micro-aeration (aeration for 5min every 12,

Min Zhu; Fan Lü; Li-Ping Hao; Pin-Jing He; Li-Ming Shao

2009-01-01

374

Evaluation of submerged surface flow (SSF) constructed wetlands for recirculating tilapia production systems  

Microsoft Academic Search

A recirculating aquaculture system (RAS) treating tilapia production wastewaters used a two-step process combining a simple clarifier and a submerged surface flow (SSF) constructed wetlands for suspended solids removal and removal of nitrogenous compounds. This system successfully supported a commercial scale level of production (>35kg\\/m3) for over 36 months of operation. The innovative SSF wetland design incorporated a high hydraulic

W ZACHRITZII; A. T. Hanson; J. A. Sauceda; K. M. Fitzsimmons

2008-01-01

375

Influence of semi-aerobic and anaerobic landfill operation with leachate recirculation on stabilization processes.  

PubMed

To investigate the influence of semi-aerobic and anaerobic landfill operation on stabilization processes of landfill sites with leachate recirculation, in situ simulated semi-aerobic landfill sites with leachate recirculation (SLR) and anaerobic landfill sites with leachate recirculation (ALR) were constructed. Refuse properties and landfill settlement were determined. Leachate quality and landfill gas compositions were monitored regularly. Based on the data obtained, leachate quality, landfill gas and final refuse characteristics were adopted as assessment factors to quantitatively evaluate stabilization of landfill sites. The results showed that volatile solids (VS), total organic carbon (TOC) and biologically degradable matter (BDM) of aged refuse in SLR (15.8, 7.3 and 9.9%, respectively) were lower than those in ALR, which were 19.1, 9.2 and 11.3%, respectively. Settlement and reduction ratio of SLR were 1.71 m and 30.91%, respectively, and 1.40?m and 25.45% in the case of ALR. Concentrations of organic pollutants, especially ammonia, were reduced in SLR, and variation in leachate quality was also smoother than ALR. Throughout the experiment the average concentration of CH4 in ALR was higher than that in SLR (36.7 and 14.5%, respectively). At the end of the experiment, SLR was moderately stable, while ALR was moderately unstable. The comprehensive assessment index (I) for SLR and ALR was 200 and 355, respectively. PMID:21930516

Yang, Yangfei; Yue, Bo; Yang, Yu; Huang, Qifei

2012-03-01

376

Regulating the hydrolysis of organic wastes by micro-aeration and effluent recirculation.  

PubMed

In this study, the effects of micro-aeration and liquid recirculation on the hydrolysis of vegetable and flower wastes during two-phase solid-liquid anaerobic digestion were assessed. To accomplish this, we evaluated the hydrolysis of five batches of waste that were treated under the following conditions: anaerobic, insufficient micro-aeration (aeration for 5 min every 24 h), and sufficient micro-aeration (aeration for 5 min every 12, 4 and 1h). Hydrolysis was found to depend on the level of micro-aeration. Specifically, insufficient micro-aeration led to unstable and decreased performance. Conversely, sufficient micro-aeration promoted the hydrolysis of easily biodegradable carbohydrates and proteins, but the microbial activity was later impaired by liquid recirculation using methanogenic effluent. The hydrolysis efficiency under anaerobic conditions was comparable to the efficiency observed under sufficient micro-aeration, while the cumulative TOC of the anaerobic batch was 1.4-2.4 times higher than that of the micro-aerated batches. In addition, liquid recirculation did not have a negative effect on the development of microbial activity under anaerobic conditions, which resulted in the lignocelluloses having a higher hydrolysis efficiency. PMID:19157839

Zhu, Min; Lü, Fan; Hao, Li-Ping; He, Pin-Jing; Shao, Li-Ming

2009-07-01

377

Removal of nitrogen from MBT residues by leachate recirculation in combination with intermittent aeration.  

PubMed

Mechanical-biological treatment (MBT) techniques have been used to reduce the emission potential of waste before placement in landfills for a couple of years, especially in Europe. The main focus of MBT is on the reduction of native organic substances and not on nitrogen compounds. As a result, the concentrations of organic substances in leachate from MBT landfills are considerably reduced in comparison to leachates from municipal solid waste landfills, while the ammonia nitrogen concentrations remain at a high level. From the stabilization of old landfills it is well known that recirculation of leachate and supplementary aeration can reduce emissions to an acceptable level in a comparatively short time. In a series of laboratory-scale tests the efficiency of this technique for MBT residues was investigated under different boundary conditions. While the effect of leachate recirculation is also well known for MBT residues, the additional aeration has so far not been investigated. The results show that this technique has only a limited influence on the reduction of organic carbon compounds. In view of nitrogen compounds, only the additional aeration during recirculation shows a strong effect on the quality of leachate, in which the concentrations of ammonium and total nitrogen are reduced by more than 90%. The results indicate that by using simple techniques the long-term emission behavior of MBT residues can be quickly reduced to an acceptable level. PMID:24293068

Tran, Hoai Nam; Münnich, Kai; Fricke, Klaus; Harborth, Peter

2014-01-01

378

The accumulation of substances in Recirculating Aquaculture Systems (RAS) affects embryonic and larval development in common carp Cyprinus carpio  

Microsoft Academic Search

The accumulation of substances in Recirculating Aquaculture Systems (RAS) may impair the growth and welfare of fish. To test the severity of contaminants accumulated in RAS, early-life stages of fish were used. Ultrafiltered water from two Recirculating Aquaculture Systems (RAS), one RAS with a high accumulation of substances (water exchange rate 30 L\\/kg feed\\/day) and one RAS with a low accumulation

Catarina I. M. Martins; Marco G. Pistrin; Stephan S. W. Ende; Ep H. Eding; Johan A. J. Verreth

2009-01-01

379

A 200 MeV Recirculating LINAC as an Injector for the LNLS UVX Electron Storage Ring  

Microsoft Academic Search

The design of an isochronous recirculating system to double the injection energy (from 100 to 200 MeV) of the LNLS UVX electron storage ring is dcscribcd. The system is composed of a gun-to-LINAC transport line, four 3-meter long SLAC-type traveling wave sections, which accelerate the beam to 100 MeV, and an isochronous recirculating line which reinjects the beam into the

R. H. A. Farias; L. Jahnel; L. Lin; P. F. Tavares

380

The significance of the Himalayan suture zone  

NASA Astrophysics Data System (ADS)

The 2500 km long Himalayan Suture Zone is discussed within the widest structural frame, with new results obtained from a study of the Landsat pictures. The platform sediments from the Tethys or Tibetan Himalaya, north of the Main Central Thrust, Change northwards into a belt of Flysch sediments beginning in the Triassic and reaching the Paleocene. The belt is mixed with oceanic crust material such as volcanics, melanges and ultrabasic slabs, and is strongly tectonized: the Suture Zone. It is followed to the north by a conspicuous belt of Kailas Molasse, of Paleogene age and transgressing the late Cretaceous Transhimalayan plutons. They consist of five bodies, predominantly tonalitic, separated by structural anomalies that also cut the Suture Zone. The plutons are structurally controlled and related to the Himalayan Suture (Subduction belt?). They are followed to the north by the south Tibetan Nyenchen Tangla belt, bordered by large fault zones and characterized by frequent Paleogene acid volcanics. The Central Tibetan Chang Thang area is structurally most complex, contains some ultrabasic rocks related to large fault zones, and exposes a large subrecent basaltic volcanism with no structural control but reminiscent of a "hot spot". The northern Kun Lun — Astin Tagh Paleozoic erogenic belt displays 200 km of rejuvenated fault zones, some older mantle fragments and subrecent volcanism. This structural aspect of Tibet, with internal older Suture Zones, younging southwards, contrasts with the Indian plate south of the Main Himalayan Suture. This Suture Zone is the only constant structural element all along the Alpine-Himalayan belt.

Gansser, A.

1980-02-01

381

The effect of sludge recirculation rate on a UASB-digester treating domestic sewage at 15 °C.  

PubMed

The anaerobic treatment of low strength domestic sewage at low temperature is an attractive and important topic at present. The upflow anaerobic sludge bed (UASB)-digester system is one of the anaerobic systems to challenge low temperature and concentrations. The effect of sludge recirculation rate on a UASB-digester system treating domestic sewage at 15 °C was studied in this research. A sludge recirculation rate of 0.9, 2.6 and 12.5% of the influent flow rate was investigated. The results showed that the total chemical oxygen demand (COD) removal efficiency rose with increasing sludge recirculation rate. A sludge recirculation rate of 0.9% of the influent flow rate led to organic solids accumulation in the UASB reactor. After the sludge recirculation rate increased from 0.9 to 2.6%, the stability of the UASB sludge was substantially improved from 0.37 to 0.15 g CH?-COD/g COD, and the bio-gas production in the digester went up from 2.9 to 7.4 L/d. The stability of the UASB sludge and bio-gas production in the digester were not significantly further improved by increasing sludge recirculation rate to 12.5% of the influent flow rate, but the biogas production in the UASB increased from 0.37 to 1.2 L/d. It is recommended to apply a maximum sludge recirculation rate of 2-2.5% of the influent flow rate in a UASB-digester system, as this still allows energy self-sufficiency of the system. PMID:23109575

Zhang, Lei; Hendrickx, Tim L G; Kampman, Christel; Zeeman, Grietje; Temmink, Hardy; Li, Weiguang; Buisman, Cees J N

2012-01-01

382

Area-based breeding zones to minimize maladaptation  

Microsoft Academic Search

A new breeding zone delineation scheme identifies for a given number of zones the zone-boundary place- ment that minimizes regional maladaptation in breeding programs. First, an adaptive map is created by using conven- tional genetic test data. Then, the large array of predicted adaptive values is subjected to cluster analysis, which assigns each grid cell of the region to one

Gregory A. O'Neill; Sally N. Aitken

2004-01-01

383

Large Eddy Simulations of Volume Restriction Effects on Canopy-Induced Increased-Uplift Regions  

NASA Astrophysics Data System (ADS)

ABSTRACT Previous modeling and empirical work have shown the development of important areas of increased uplift past forward-facing steps, and recirculation zones past backward-facing steps. Forests edges represent a special kind of step - a semi-porous one. Current models of the effects of forest edges on the flow represent the forest with a prescribed drag term and does not account for the effects of the solid volume in the forest that restrict the airflow. The RAMS-based Forest Large Eddy Simulation (RAFLES) resolves flows inside and above forested canopies. RAFLES is spatially explicit, and uses the finite volume method to solve a descretized set of Navier-Stokes equations. It accounts for vegetation drag effects on the flow and on the flux exchange between the canopy and the canopy air, proportional to the local leaf density. For a better representation of the vegetation structure in the numerical grid within the canopy sub-domain, the model uses a modified version of the cut cell coordinate system. The hard volume of vegetation elements, in forests, or buildings, in urban environments, within each numerical grid cell is represented via a sub-grid-scale process that shrinks the open apertures between grid cells and reduces the open cell volume. We used RAFLES to simulate the effects of a canopy of varying foliage and stem densities on flow over virtual qube-shaped barriers under neutrally buoyant conditions. We explicitly tested the effects of the numerical representation of volume restriction, independent of the effects of the leaf drag by comparing drag-only simulations, where we prescribed no volume or aperture restriction to the flow, restriction-only simulations, where we prescribed no drag, and control simulations, where both drag and volume plus aperture restriction were included. Our simulations show that representation of the effects of the volume and aperture restriction due to obstacles to flow is important (figure 1) and leads to differences in the strengths and locations of increased-updraft and recirculation zones. Particularly, introduction of volume restriction shifted the location of the uplift zone and anchored it to the downwind edge of the barrier. In addition. We propose that volume restriction due to the presence of the stems and branches is an important improvement to LES that should be considered. Figure 1: Horizontal and vertical wind components (arrows) illustrated across a vertical cross section through the simulation domain. The colors illustrate the variation of the vertical wind component. The canopy location is marked by a thick continuous line. A. Drag-only simulation (Drag = 0.04?, Volume blockage = 0%), B. Control simulation (Drag = 0.04?, Volume blockage = 40%).

Chatziefstratiou, E.; Bohrer, G.; Velissariou, V.

2012-12-01

384

Duration of a large Mafic intrusion and heat transfer in the lower crust: A SHRIMP U-Pb zircon Study in the Ivrea-Verbano Zone (Western Alps, Italy)  

USGS Publications Warehouse

The Ivrea-Verbano Zone in the western Italian Alps contains one of the world's classic examples of ponding of mantle-derived, mafic magma in the deep crust. Within it, a voluminous, composite mafic pluton, the Mafic Complex, intruded lower-crustal, high-grade paragneiss of the Kinzigite Formation during Permian-Carboniferous time, and is now exposed in cross-section as a result of Alpine uplift. The age of the intrusion is still debated because the results of geochronological studies in the last three decades on different rock types and with various dating techniques range from 250 to about 300 Ma. Sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon age determinations on 12 samples from several locations within the Mafic Complex were performed to better constrain the age of the igneous event. The results indicate a long history of magma emplacement and cooling, which reconciles the spread in previously published ages. The main intrusive phase took place at 288 ?? 4 Ma, causing a perturbation of the deep-crustal geotherm, which relaxed to the Sm-Nd closure temperature in garnet-free mafic rocks after about 15-20 Myr of sub-solidus cooling at c. 270 Ma. These results suggest that large, deep crustal plutons, such as those identified geophysically at depths of 10-20 km within extended continental crust (e.g. Yellowstone, Rio Grande Rift, Basin and Range) may have formed rapidly but induced a prolonged thermal perturbation. In addition, the data indicate that a significant thermal event affected the country rock of the Mafic Complex at about 310 Ma. The occurrence of an upper amphibolite- to granulite-facies thermal event in the Kinzigite Formation prior to the main intrusive phase of the Mafic Complex has been postulated by several workers, and is corroborated by other geochronological investigations. However, it remains uncertain whether this event (1) was part of a prolonged perturbation of the deep-crustal geotherm, which started long before the onset of intrusion of the Mafic Complex, or (2) corresponded to the intrusion of the first sills of the Mafic Complex, or (3) was related to an earlier, independent thermal pulse. ?? The Author 2007. Published by Oxford University Press. All rights reserved.

Peressini, G.; Quick, J.E.; Sinigoi, S.; Hofmann, A.W.; Fanning, M.

2007-01-01

385

Argon purification studies and a novel liquid argon re-circulation system  

NASA Astrophysics Data System (ADS)

Future giant liquid argon (LAr) time projection chambers (TPCs) require a purity of better than 0.1 parts per billion (ppb) to allow the ionised electrons to drift without significant capture by any electronegative impurities. We present a comprehensive study of the effects of electronegative impurity on gaseous and liquid argon scintillation light, an analysis of the efficiency of various purification chemicals, as well as the Liverpool LAr setup, which utilises a novel re-circulation purification system. Of the impurities tested - Air, O2, H2O, N2 and CO2 in the range of between 0.01 ppm to 1000 ppm - H2O was found to have the most profound effect on gaseous argon scintillation light, and N2 was found to have the least. Additionally, a correlation between the slow component decay time and the total energy deposited with 0.01 ppm - 100 ppm O2 contamination levels in liquid argon has been established. The superiority of molecular sieves over anhydrous complexes at absorbing Ar gas, N2 gas and H2O vapour has been quantified using BET isotherm analysis. The efficiency of Cu and P2O5 at removing O2 and H2O impurities from 1 bar N6 argon gas at both room temperature and -130 °C was investigated and found to be high. A novel, highly scalable LAr re-circulation system has been developed. The complete system, consisting of a motorised bellows pump operating in liquid and a purification cartridge, were designed and built in-house. The system was operated successfully over many days and achieved a re-circulation rate of 27 litres/hour and high purity.

Mavrokoridis, K.; Calland, R. G.; Coleman, J.; Lightfoot, P. K.; McCauley, N.; McCormick, K. J.; Touramanis, C.

2011-08-01

386

Expressions for the threshold current of multipass beam breakup in recirculating linacs from single cavity models  

SciTech Connect

We investigate multipass beam breakup (BBU) in a recirculating linear accelerator in the framework of a single cavity model. We present expressions for the beam breakup threshold current for various situations derived from a perturbative solution of BBU equations. These formulae should serve as a guide to understand the BBU phenomenon for a particular system and also as a tool to estimate the BBU threshold current quickly. Many of the results presented are more general than previous considerations because they include the effects of coupling between the two transverse polarizations in each dipole higher order mode.

Byung C. Yunn

2005-10-01

387

Flowing recirculated-water system for inducing laboratory spawning of sea lampreys  

USGS Publications Warehouse

We describe a water-recirculating system for inducing spawning of sea lampreys (Petromyzon marinus) held under laboratory conditions. Water temperature in the system was gradually increased to and maintained at 18 +/- 2 degrees C, the optimal temperature for spawning. About 10% freshwater was added daily to prevent buildup of waste products. Sea lampreys were provided substrate (approximately 3-6 cm in diameter) to build nests, and a water velocity of 0.2-0.3 m/s was maintained with an electric trolling motor. Sea lampreys held in this system exhibited characteristic spawning behavior. Prolarvae produced from artificial fertilization of gametes developed according to the standard timeline.

Fredricks, Kim T.; Seelye, James G.

1995-01-01

388

Recirculating Beam Breakup Study for the 12 GeV Upgrade at Jefferson Lab  

SciTech Connect

Two new high gradient C100 cryomodules with a total of 16 new cavities were installed at the end of the CEBAF south linac during the 2011 summer shutdown as part of the 12-GeV upgrade project at Jefferson Lab. We surveyed the higher order modes (HOMs) of these cavities in the Jefferson Lab cryomodule test facility and CEBAF tunnel. We then studied recirculating beam breakup (BBU) in November 2011 to evaluate CEBAF low energy performance, measure transport optics, and evaluate BBU thresholds due to these HOMs. This paper discusses the experiment setup, cavity measurements, machine setup, optics measurements, and lower bounds on BBU thresholds by new cryomodules.

Ilkyoung Shin, Todd Satogata, Shahid Ahmed, Slawomir Bogacz, Mircea Stirbet, Haipeng Wang, Yan Wang, Byung Yunn, Ryan Bodenstein

2012-07-01

389

Prediction of flow recirculation in a blanket assembly under worst-case natural-convection conditions. [LMFBR  

SciTech Connect

Reactor fuel and blanket assemblies within a Liquid Metal Fast Breeder Reactor (LMFBR) can be subjected to severe radial heat flux gradients. At low-flow conditions, with power-to-flow ratios of nearly the same magnitude as design conditions, buoyancy forces cause flow redistribution to the side of a bundle with the higher heat generation rate. Recirculation of fluid within a rod bundle can occur during a natural convection transient because of the combined effect of flow coastdown and buoyancy-induced redistribution. An important concern is whether recirculation leads to high coolant temperatures. For this reason, the COBRA-WC code was developed with the capability of modeling recirculating flows. Experiments have been conducted in a 2 x 6 rod bundle for flow and power transients to study recirculation in the mixed-convection (forced cooled) and natural-convection regimes. The data base developed was used to validate the recirculation module in the COBRA-WC code. COBRA-WC code calculations were made to predict flow and temperature distributions in a typical LMFBR blanket assembly for the worst-case, natural-circulation transient.

Khan, E.U.; Rector, D.R.

1982-06-29

390

Adenovirus Vector-Induced CD8+ T Effector Memory Cell Differentiation and Recirculation, But Not Proliferation, Are Important for Protective Immunity Against Experimental Trypanosoma cruzi Infection  

PubMed Central

Abstract Heterologous prime-boost vaccination using plasmid DNA followed by replication-defective adenovirus vector generates a large number of specific CD8+ T effector memory (TEM) cells that provide long-term immunity against a variety of pathogens. In the present study, we initially characterized the frequency, phenotype, and function of these T cells in vaccinated mice that were subjected to infectious challenge with the human protozoan parasite Trypanosoma cruzi. We observed that the frequency of the specific CD8+ T cells in the spleens of the vaccinated mice increased after challenge. Specific TEM cells differentiated into cells with a KLRG1High CD27Low CD43Low CD183LowT-betHigh EomesLow phenotype and capable to produce simultaneously the antiparasitic mediators IFN? and TNF. Using the gzmBCreERT2/ROSA26EYFP transgenic mouse line, in which the cells that express Granzyme B after immunization, are indelibly labeled with enhanced yellow fluorescent protein, we confirmed that CD8+ T cells present after challenge were indeed TEM cells that had been induced by vaccination. Subsequently, we observed that the in vivo increase in the frequency of the specific CD8+ T cells was not because of an anamnestic immune response. Most importantly, after challenge, the increase in the frequency of specific cells and the protective immunity they mediate were insensitive to treatment with the cytostatic toxic agent hydroxyurea. We have previously described that the administration of the drug FTY720, which reduces lymphocyte recirculation, severely impairs protective immunity, and our evidence supports the model that when large amounts of antigen-experienced CD8+ TEM cells are present after heterologous prime-boost vaccination, differentiation, and recirculation, rather than proliferation, are key for the resultant protective immunity. PMID:24568548

Vasconcelos, José Ronnie; Dominguez, Mariana R.; Neves, Ramon L.; Ersching, Jonatan; Araújo, Adriano; Santos, Luara I.; Virgilio, Fernando S.; Machado, Alexandre V.; Bruna-Romero, Oscar; Gazzinelli, Ricardo T.

2014-01-01

391

EPA Map of Radon Zones  

MedlinePLUS

... pCi/L (picocuries per liter) (red zones) Highest Potential Zone 2 counties have a predicted average indoor ... 2 and 4 pCi/L (orange zones) Moderate Potential Zone 3 counties have a predicted average indoor ...

392

Fluid processes in subduction zones.  

PubMed

Fluids play a critical role in subduction zones and arc magmatism. At shallow levels in subduction zones (<40 kilometers depth), expulsion of large volumes of pore waters and CH(4)-H(2)O fluids produced by diagenetic and low-grade metamorphic reactions affect the thermal and rheological evolution of the accretionary prism and provide nutrients for deep-sea biological communities. At greater depths, H(2)O and CO(2) released by metamorphic reactions in the subducting oceanic crust may alter the bulk composition in the overlying mantle wedge and trigger partial melting reactions. The location and conse-quences of fluid production in subduction zones can be constrained by consideration of phase diagrams for relevant bulk compositions in conjunction with fluid and rock pressure-temperature-time paths predicted by numerical heat-transfer models. Partial melting of subducting, amphibole-bearing oceanic crust is predicted only within several tens of million years of the initiation of subduction in young oceanic lithosphere. In cooler subduction zones, partial melting appears to occur primarily in the overlying mantle wedge as a result of fluid infiltration. PMID:17784486

Peacock, S A

1990-04-20

393

Recirculating vertical flow constructed wetland: green alternative to treating both human and animal sewage.  

PubMed

Subsurface constructed wetlands using a recirculating vertical flow are a viable alternative technology to pretreating conventional residential septic systems effluents before underground discharge. The authors examined performance of a recirculating vertical flow constructed wetland (RVFCW) to treat both human and domestic animal sewage from the LaGrange County (Indiana) Animal Shelter. Effluent water samples were analyzed for the five-day biochemical oxygen demand (BOD5), total suspended solids (TSS), ammonia-nitrogen (AN), total Kjeldhal nitrogen (TKN), total nitrogen (TN), nitrate-nitrogen, total phosphorus (TP) and fecal coliform bacteria (FC). Treatment efficiencies (percentage removal) after a two-year operation were high for BOD5 (99%), TSS (98%), AN (96%), TKN (94%), TN (83%), and FC (99%). Nitrate-nitrogen final mean value was 6.8 mg/L, dissolved oxygen concentration increased from 1.8 to 4.3 mg/L, and removal efficiency for total phosphorus was low (33%). These results show that vertical flow constructed wetlands are a green alternative to remove pollutants generated for both human and domestic animals. PMID:19908434

García-Pérez, Alfredo; Harrison, Mark; Grant, Bill

2009-11-01

394

Novel concept development of an internal recirculation catalyst for mild gasification  

SciTech Connect

The objective of this program is to provide an overall evaluation of a novel process concept for mild gasification by completing work in three major tasks: (1) Laboratory-Scale Experiments, (2) Bench-Scale Tests, and (3) Proof-of-Concept Tests and Evaluation (optional). During this quarter, experimental work involving potential recirculating catalysts for coal, initiated in the previous quarter, was continued. The construction and shakedown of an all quartz laboratory-scale isothermal free-fall reactor was completed. Three free-fall experiments were performed in an existing stainless-steel free-fall reactor with untreated and ammonia treated Illinois No. 6 high-voltatile bituminous coal, and the analyzed data are presented herein. A survey of available literature on catalyzed devolatilization of coal, coal pretreatment methods, and related topics was made. Based on the results of this survey, two potential recirculating catalysts, in addition to the already selected zinc chloride, were selected for study: ferrous chloride (FeCl{sub 2}) and ferric chloride (FeCl{sub 3}). Also, based on the survey, two coal pretreatment/chemical comminution methods were selected for study, in addition to methanol treatment: ammonia and n-butylamine pretreatment. A matrix of experiments was formulated to study the three catalysts and three pretreatment methods selected. 2 refs., 2 tabs.

Knight, R.A.; Babu, S.P.; Martin, K.A.; Chao, S.C.

1988-10-01

395

Novel concept development of an internal recirculation catalyst for mild gasification  

SciTech Connect

The Institute of Gas Technology (IGT) has conducted a fundamental research program to evaluate a novel process concept for mild coal gasification that uses a semivolatile'' internal recirculation catalyst, which would remain in the gasifier because its vapor pressure is such that it remains in the vapor state in the hotter (char exit) part of the reactor, but condenses in the colder (coal inlet) section. Work was divided into two tasks: Task 1: Laboratory-Scale Tests and Task 2: Bench-Scale Tests. Task 1 was to be conducted using an existing microscale pyrolysis-gas chromatograph-mass spectrometer (PY-GC-MS) method, in order to obtain detailed information on the effects of the selected internal recirculation catalysts, cesium hydroxide and ZnCl{sub 2}, on mild gasification products. An Illinois No. 6 high-volatile bituminous, a Wyodak subbituminous, and a North Dakota lignite, were tested. The remainder of the study was directed towards the investigation of chemical pretreatment methods for mild gasification. Coal pretreated with methanol, ammonia, and n-butylamine was studied in the IFFR, along with untreated samples. The experiments also investigated the effect of CO{sub 2} as a mild gasification gaseous medium, in comparison to inert gases, He and N{sub 2}. A total of nine IFFR experiments were conducted. Task 2 was not undertaken. 33 refs., 21 figs., 49 tabs.

Knight, R.A.; Babu, S.P.; Martin, K.A.; Chao, S.C.

1989-02-01

396

Linear Fixed-Field Multi-Pass Arcs for Recirculating Linear Accelerators  

SciTech Connect

Recirculating Linear Accelerators (RLA's) provide a compact and efficient way of accelerating particle beams to medium and high energies by reusing the same linac for multiple passes. In the conventional scheme, after each pass, the different energy beams coming out of the linac are separated and directed into appropriate arcs for recirculation, with each pass requiring a separate fixed-energy arc. In this paper we present a concept of an RLA return arc based on linear combined-function magnets, in which two and potentially more consecutive passes with very different energies are transported through the same string of magnets. By adjusting the dipole and quadrupole components of the constituting linear combined-function magnets, the arc is designed to be achromatic and to have zero initial and final reference orbit offsets for all transported beam energies. We demonstrate the concept by developing a design for a droplet-shaped return arc for a dog-bone RLA capable of transporting two beam passes with momenta different by a factor of two. We present the results of tracking simulations of the two passes and lay out the path to end-to-end design and simulation of a complete dog-bone RLA.

V.S. Morozov, S.A. Bogacz, Y.R. Roblin, K.B. Beard

2012-06-01

397

Fate of saline ions in a planted landfill site with leachate recirculation.  

PubMed

Recirculation of leachate on a covered landfill site planted with willows or other highly evapotranspirative woody plants is an inexpensive option for leachate management. In our study, a closed landfill leachate recirculation system was established on a rehabilitated municipal solid waste landfill site with planted landfill cover. The main objective of the study was to evaluate the sustainability of the system with regard to high hydraulic loads of the landfill leachate on the landfill cover and high concentrations of saline ions, especially potassium (K(+)), sodium (Na(+)) and chloride (Cl(-)), in leachate. The results of intensive monitoring, implemented during May 2004 and September 2007, including leachate, soil and plant samples, showed a high sustainability of the system regarding saline ions with the precipitation regime of the studied region. Saline ion concentrations in leachates varied between 132 and 2592mg Cl(-) L(-1), 69 and 1310mg Na(+) L(-1) and between 66 and 2156mg K(+) L(-1), with mean values of 1010, 632 and 686mg L(-1), respectively. Soil salinity, measured as soil electrical conductivity (EC), remained between 0.17 and 0.38mS cm(-1) at a depth between 0 and 90cm. An average annual precipitation of 1000mm provided sufficient leaching of saline ions, loaded by irrigation with landfill leachate, from the soil of the landfill cover and thus prevented possible salinity shocks to the planted willows. PMID:19796928

Loncnar, Mojca; Zupancic, Marija; Bukovec, Peter; Zupancic Justin, Maja

2010-01-01

398

Effects of Exhaust Gas Recirculation on SI Engines at Wide Open Throttle  

NASA Astrophysics Data System (ADS)

Exhaust gas recirculation, a charge dilution technique, has proven to be an effective method of reducing NOx emissions and fuel consumption of spark ignition engines. Wide open throttle operation also increases overall engine efficiency by reducing the pumping losses caused by throttling. In this study, the emissions and fuel economy benefits of exhaust gas recirculation (EGR) at wide open throttle conditions were quantified using a 2.4L port-injected engine. Engine performance and emissions data were recorded as the percentage of EGR in the intake charge was increased from zero to just above thirty percent (the EGR limit). This EGR percentage, in-cylinder pressure measurements, and the temperatures and pressures of the intake and exhaust were all recorded to ensure stable operating conditions. These tests were performed with a stoichiometric air-fuel ratio at a constant speed of 2000 rpm at wide open throttle. The variation of brake specific fuel consumption and emissions (in particular NOx) with increasing EGR percentages was analyzed.

Bronson, Sydney; Puzinauskas, Paulius

2011-11-01

399

[Removal nitrogen in wavy subsurface-flow constructed wetland utilizing aeration and recirculation].  

PubMed

To improve the removal rates of ammonium nitrogen in the constructed wetlands, the traditional wavy subsurface-flow constructed wetland (W-SFCW) was modified to install the aeration tube in the second wave interval to improve the DO and the nitrification rates within the constructed wetlands. It was found that as most of COD had been removed in the second wave interval, nitrifying bacteria become dominant in the third wave interval, which led to the nitrification extent reaching more than 90%, and the ability to endure the impact of hydraulic loading was enhanced. Recirculation rates of 50% were adopted to evaluate the effect on TN removal. It showed that with effluent recirculation the average removal efficiencies of TN obviously increased to 50% when the wastewater entered 1/3 of the wetland not infall. The hydraulic loading of wetland reached 0.8 m3/(m2 x d), and COD organic loading was 56-112 g/(m2 x d), and the ammonium loading rate was 20-28 g/(m2 x d). PMID:18290423

Ren, Yong-zheng; Zhang, Bei-ping; Hai, Ben-zeng

2007-12-01

400

Geochemical Zoning in Metamorphic Minerals  

NASA Astrophysics Data System (ADS)

Rocks encode the sum of Earth processes that affected them during their "lifetimes," and the purpose of most geological studies is to invert that information to refine our understanding of those processes. A metamorphic rock records not just a peak P-T condition, a single cooling rate, or a simple texture, but rather has undergone an evolving history of changes in P and T, mineral abundances, rim compositions, and textures, acting over its metamorphic lifespan, in response to heat flow, stress and strain, and inter- and intragranular movement of material. The greatest advances in understanding metamorphic rocks have been achieved through a recognition that metamorphism is a continuum, and by collection of data and development of models that directly address these continuum processes. Of the many approaches for investigating and interpreting metamorphic rocks, one of the most important is the characterization and quantitative modeling of geochemical zoning in metamorphic minerals. Geochemical zoning is particularly useful, because it is a quasicontinuous record of these metamorphic processes.There have been several previous reviews of chemical zoning in metamorphic minerals (e.g., Tracy, 1982; Loomis, 1983; Chakraborty and Ganguly, 1991; Spear, 1993). This review differs from them in three ways.(i) A catalogue was not compiled of all the minerals that exhibit zonation, and of the elements that are zoned. Although some minerals may be more obviously zoned than others, all minerals must be zoned in some element or isotope at some scale, and it is simply a matter of time before that zonation is described.(ii) Emphasis is placed on theoretical models of zoning, and these are illustrated with one or two of the best natural examples. Some other examples of zonation are also discussed which are particularly relevant to other endeavors, or hold special promise for future research.(iii) A large body of information, mostly collected since the early 1990s, is presented for trace element, stable isotope, and radiogenic isotope zoning.Garnet (Grt) is overwhelmingly favored for geochemical zoning studies, in part because it is commonly zoned in major and trace elements as well as in stable and radiogenic isotopes, but also because its chemistry, geochemical partitioning behavior, and physical shape are readily modeled theoretically. Other minerals are also zoned, but most are not as amenable to study or modeling. For these reasons, garnet is a major focus of this review. Emphasis is placed on theory and principles rather than on documentation, so extrapolation to other minerals and other chemical systems should be possible. The information is organized into four sections: major elements, stable isotopes, trace elements, and radiogenic isotopes. Most theory has been developed for the distribution of the major elements, but studies of the other types of zoning are becoming increasingly common, and deserve separate subsections in this review.This chapter does not cover analytical techniques, and assumes that the reader is at least moderately familiar with the electron microprobe, ion microprobe, and laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS), as well as with the distinction between X-ray mapping and spot analysis by electron microprobe. Mineral abbreviations are after Kretz (1983).

Kohn, M. J.

2003-12-01

401

Recirculation in double lumen catheter veno-venous extracorporeal membrane oxygenation measured by an ultrasound dilution technique.  

PubMed

Recirculation is a limiting factor for oxygen delivery in double lumen catheter veno-venous extracorporeal membrane oxygenation (DLVV-ECMO). This study compares three different methods for the determination of the recirculation fraction during double lumen catheter veno-venous ECMO at ECMO flow rates of 150, 125, 100, 75, and 50 ml/kg.min in nine lambs: (1) an ultrasound dilution method, in which the change in ultrasound velocity in blood after injection of a saline bolus as a marker is used for determination of recirculation; (2) an SvO2 method using real mixed venous blood oxygen saturation, the gold standard, for determination of recirculation fraction; and (3) the CVL method, in which oxygen saturation of a blood sample of the inferior vena cava is considered to represent mixed venous oxygen saturation. In all methods, the recirculation fraction increased with increasing ECMO flow rate. The correlation coefficient between the ultrasound dilution method and the SvO2 method was 0.68 (p < 0.01); mean difference was -2.4% (p = 0.6). Correlation coefficient between the ultrasound dilution method and the CVL method was 0.48 (p < 0.01); mean difference was -18.1% (p < 0.01). The correlation coefficient between the SvO2 method and the CVL method was 0.51 (p < 0.01); mean difference was -15.7% (p < 0.01). The ultrasound dilution method is a useful method for measurement of the recirculation fraction in DLVV-ECMO and is easier to use than the other methods. PMID:11482489

van Heijst, A F; van der Staak, F H; de Haan, A F; Liem, K D; Festen, C; Geven, W B; van de Bor, M

2001-01-01

402

Heterogeneous coupling along Makran subduction zone  

Microsoft Academic Search

The Makran subduction zone, located in the southeast of Iran and southern Pakistan, extends for almost 900 km along the Eurasian-Arabian plate boundary. The seismic activities in the eastern and western Makran exhibit very different patterns. The eastern Makran characterized by infrequent large earthquakes and low level of seismicity. The only large instrumentally recorded earthquake in the eastern Makran, the

Z. Zarifi; M. Raeesi

2010-01-01

403

Marginal Zone Lymphomas  

Microsoft Academic Search

\\u000a \\u000a Marginal zone lymphoma (MZL) encompasses a heterogeneous group of small B-cell lymphomas, characterized by a predominance of tumor cells with a\\u000a phenotype, homing pattern, and occasionally the appearance of the nonneoplastic marginal zone B cells that surround germinal centers and populate the white pulp of the spleen. Covered in this chapter are extranodal marginal\\u000a zone lymphoma of mucosa-associated lymphoid tissue

Rachel L. Sargent

404

Introduction to Ocean Zones  

NSDL National Science Digital Library

In this activity, learners will create a diagram of the ocean zones and determine what organisms live in each zone. Learners will draw the appropriate scale to demark meters (and conversion to feet) from 0-6000m and draw the zones that correspond to the geological structures of the ocean basin. Finally, learners will use their critical thinking skills to determine where in the ocean each organism lives and place the organism in the habitat that is within the limitations for survival.

West, Cosee

2012-01-01

405

[The epileptogenic zone].  

PubMed

The definition of the epileptogenic zone is a concept proposed by Jean Bancaud and Jean Talairach based on the anatomical, electrical and clinical correlations established from stereoelectroencephalographic recordings. They believed the epileptogenic zone to be the "region of the beginning and the primary organization" of ictal discharges. The opinion of North American authors is different: the epileptogenic zone is the "what to remove area" to produce freedom from seizures. This surgical definition assumes postsurgical validation. The aim of this paper is to show how to define the epileptogenic zone from all the stereoelectroencephalographic recording data. PMID:18440034

Kahane, P; Landré, E

2008-05-01

406

MEASUREMENT OF SOOT MORPHOLOGY, CHEMISTRY, AND OPTICAL PROPERTIES IN THE VISIBLE AND NEAR-INFRARED SPECTRUM IN THE FLAME ZONE AND OVERFIRE REGION OF LARGE JP-8 POOL FIRES  

Microsoft Academic Search

The dimensionless extinction coefficient, Ke, was measured for soot produced in 2 m JP-8 pool fires. Light extinction and gravimetric sampling measurements were performed simultaneously at 635 and 1310 nm wavelengths at three heights in the flame zone and in the overfire region. Measured average Ke values of 8.4 ± 1.2 at 635 nm and 8.7 ± 1.1 at 1310 nm in the overfire region agree well with

KIRK A. JENSEN; JILL M. SUO-ANTTILA; LINDA G. BLEVINS

2007-01-01

407

Insights from quartz cathodoluminescence zoning into crystallization of the Vinalhaven granite, coastal Maine  

NASA Astrophysics Data System (ADS)

The aim of the present work is to compare stability combustion domains, flame structures and dynamics between CH4/air flames and a biogas/air flames (issued from waste methanisation) in a lean gas turbine premixed combustion conditions. Velocity profiles are obtained by Laser Doppler Anemometry measurements. CH* chemiluminescence measurements and temporal acquisition of chamber pressure are performed in order to describe flame structure and instabilities. Changes in flame structure and dynamics when fuel composition is varying are found to strongly depend on laminar flame speed. No clear correlation between the unstable flame and the reaction zone penetration in the corner recirculation can be found.

Lafay, Y.; Taupin, B.; Martins, G.; Cabot, G.; Renou, B.; Boukhalfa, A.

2007-08-01

408

Commercial Zone Melting Ingots  

NASA Astrophysics Data System (ADS)

Bismuth telluride-based compounds have been extensively utilized for commercial application. However, thermoelectric materials must suffer numerous mechanical vibrations and thermal stresses while in service, making it equally important to discuss the mechanical properties, especially at high temperature. In this study, the compressive and bending strengths of Bi0.5Sb1.5Te3 commercial zone melting (ZM) ingots were investigated at 25, 100, and 200 °C, respectively. Due to the obvious anisotropy of materials prepared by ZM method, the effect of anisotropy on the strengths was also explored. Two-parameter Weibull distribution was employed to fit a series of values acquired by a universal testing machine. And digital speckle photography was applied to record the strain field evolution, providing visual observation of surface strain. The compressive and bending strengths along ZM direction were approximately three times as large as those perpendicular to the ZM direction independent of the temperature, indicating a weak van der Waals bond along the c axis.

Zheng, Yun; Xie, Hongyao; Shu, Shengcheng; Yan, Yonggao; Li, Han; Tang, Xinfeng

2014-06-01

409

GIT (Glucose Infusion Test): polycentric evaluation of a new test for vascular access recirculation.  

PubMed

Introduction. Vascular access recirculation (AR), which is often unacknowledged, remains an important cause of inadequate dialytic dose. The glucose infusion test (GIT) is a new method for detecting and quantifying AR. This paper reports on a polycentric evaluation of the new test and a comparison with the classical Urea-test (UT). Methods. GIT protocol comprises withdrawal from the arterial port (sample A), injection into the venous drip chamber of 1 g glucose in 4 seconds, withdrawal from the arterial port (sample B) continuously from 13 to 17 seconds. Glucose is determined on A and B by a reflectance photometer. If B = A then there is no recirculation. If B exceeds A by at least 20 mg/dl there is recirculation. AR quantification: AR% = (B-A) / 20. GIT was performed on 623 patients from eleven dialysis centers to screen the patients for AR. Subsequently, GIT and Urea-test (UT) were compared in 189 paired tests. The reproducibility of GIT and UT was studied in 28 paired tests performed in sequence. Results. The screening test by GIT was positive in 68 cases (11 %). The majority of positivities was found in central venous catheters (CVC, 27/50 cases, 54 %), whereas only 7 % of artero-venous fistulas (AVF) were positive. In the CVC group, Tesio catheters were more frequently positive compared to Dual Lumen Catheters (64 % vs. 29 %). The comparison GIT - UT showed that results matched in 162 tests (79 negative and 83 positive both by GIT and UT), showing that on the grounds of UT, GIT has high sensitivity and specificity. In 27 tests GIT was positive, but UT negative. This disagreement is due to the different minimal limit of detection, 1 % for GIT and 5% for UT. The reproducibility was greater with GIT than with UT with a lower D% (respectively -0.6 +/- 2.5 and -0.4 +/- 6.1 %, p<0.001) and a lower coefficient of variation (17 vs 33 %). Conclusions. The screening of 623 patients by GIT confirmed that AR in AVF is normally absent, whereas an un-expectedly high frequency of moderate AR in CVC was found. The GIT-UT comparison showed that the new test is simple and immediate, and gives results with higher accuracy, sensitivity and reproducibility than UT. PMID:17638247

Alloatti, S; Magnasco, A; Bonfant, G; Bonello, F; Ciciani, A M; Fidelio, T; Filiberti, O; Forneris, G; Martina, G; Robaudo, C; Romano, U; Schelotto, C

2000-01-01

410

Systems and methods for reactive distillation with recirculation of light components  

DOEpatents

Systems and methods for producing gas-to-liquids products using reactive distillation are provided. The method for producing gas-to-liquids products can include reacting a feedstock in a column having a distillation zone and a reaction zone to provide a bottoms stream and an overhead stream. A first portion of the overhead stream can be recycled to the column at the top of the reaction zone and second portion of the overhead stream can be recycled to the column at the bottom of the reaction zone.

Stickney, Michael J. (Nassau Bay, TX); Jones, Jr., Edward M. (Friendswood, TX)

2011-07-26

411

Degradation of Surfactants in Hydroponic Wheat Root Zones  

NASA Astrophysics Data System (ADS)

Hygiene water recycling in recirculating hydroponic systems can be enhanced by plant roots by providing a substrate and root exudates for bacterial growth. However, reduced plant growth can occur during batch mode additions of high concentrations of surfactant. An analog hygiene water stream containing surfactants (Steol CS330, Mirataine CB) was added to a hydroponically-grown wheat plant root zone. The plants were grown at 700 mol mol-1 CO2, a photosynthetic photon flux of 300 mol m-2 s-1, and a planting density of 380 plants m-2. Volumetric oxygen mass transfer coefficients were determined using the fermentative/dynamic outgassing method to maintain adequate oxygen mass transfer rates in the root zone. This analysis suggested an optimal flow rate of the hydroponic solution of 5 L min-1. The hydroponic system was inoculated with biofilm from a bioreactor and rates of surfactant degradation were measured daily based on reduction in chemical oxygen demand (COD). The COD decreased from 400 to 100 mg L-1 after 2 days following batch addition of the analog hygiene water to the hydroponic system. Measurements of dissolved oxygen concentration and solution temperature suggest that the root zone was provided adequate aeration to meet both oxygen demands from plant and microbial respiration during the degradation of the surfactant. Results from this study show that hydroponic systems can be used to enhance rates of hygiene water processing.

Monje, Oscar; McCoy, Lashelle; Flanagan, Aisling

412

Dead Zones and Extrasolar Planetary Properties  

E-print Network

Most low-mass protostellar disks evolve in clustered environments where they are affected by external radiation fields, while others evolve in more isolated star-forming regions. Assuming that the magneto-rotational instability (MRI) is the main source of viscosity, we calculate the size of a poorly ionized, MRI inactive, and hence low viscosity region - the "dead zone" - in these protostellar disks. We include disk ionization by X-rays, cosmic rays, radioactive elements and thermal collisions, recombination by molecules, metals, and grains, as well as the effect of turbulence stimulation in the dead zone by the active layers lying above it. We also calculate the gap-opening masses of planets, which are determined by a disk's viscosity and a disk aspect ratio, for disks in these environments and compare them with each other. We find that the dead zone is a robust feature of the protostellar disks that is largely independent of their environment, typically stretching out to ~ 15 AU. We analyze the possible effects of dead zones on planet formation, migration, and eccentricity evolution. We show that the gap-opening mass inside the dead zone is expected to be of the order of terrestrial and ice giant mass planets while that outside the dead zone is Jovian or super-Jovian mass planets, largely independent of the star-forming environment. We show that dead zones can significantly slow down both type I and type II planetary migration due to their lower viscosity. We also find that the growth of eccentricity of massive extrasolar planets is particularly favorable through the planet-disk interaction inside the dead zones due to the large gaps expected to be opened by planets.

Soko Matsumura; Ralph E. Pudritz

2005-12-08

413

The Use of Exhaust Gas Recirculation to Optimize Fuel Economy and Minimize Emission in Engines Operating on E85 Fuel  

SciTech Connect

This report summarizes activities conducted for the project “The Use of Exhaust Gas Recirculation to Optimized Fuel Economy and Minimize Emissions in Engines Operating on E85 Fuel” under COOPERATIVE AGREEMENT NUMBER DE-FC26-07NT43271, which are as outlined in the STATEMENT OF PROJECT OBJECTIVES (SOPO) dated March 2007 and in the supplemental SOPO dated October 2010. The project objective was to develop and demonstrate an internal combustion engine that is optimized for E85 (85% ethanol and 15% gasoline) fuel operation to achieve substantially improved fuel economy while operating with E85 fuel and that is also production viable in the near- to medium-term. The key engine technology selected for research and development was turbocharging, which is known to improve fuel economy thru downsizing and is in particular capable of exploiting ethanol fuel’s characteristics of high octane number and high latent heat of vaporization. The engine further integrated synergistic efficiency improving technologies of cooled exhaust gas recirculation (EGR), direct fuel injection and dual continuously variable intake and exhaust cam phasers. On the vehicle level, fuel economy was furthered thru powertrain system optimization by mating a state-of-the-art six-speed automatic transmission to the engine. In order to achieve the project’s objective of near- to medium-term production viability, it was essential to develop the engine to be flex-fuel capable of operating with fuels ranging from E0 (0% ethanol and 100% gasoline) to E85 and to use three-way type of catalyst technology for exhaust aftertreatment. Within these scopes, various technologies were developed through systems approach to focus on ways to help accelerate catalyst light-off. Significant amount of development took place during the course of the project within General Motors, LLC. Many prototype flex-fuel engines were designed, built and developed with various hardware configurations selected to achieve the project goals. Several flex-fuel demonstration vehicles were designed and built for carrying out calibration development and final testing to quantify the technology merits. Based on the extensive test results collected from dynamometer and vehicle testing, the fuel economy benefits of cooled EGR from the intended level of turbocharger technology were quantified. When combined with turbo downsizing, the FE benefits are considered large enough for E0 fuel as well as for E85 fuel to warrant further development of the technology beyond the current proof-of-concept level to a level that can meet production driveability quality and durability requirements in order to meet customers’ expectations. Cold-start cart test results from the emissions segment of the project were positive, confirming the assumption of faster thermal response of turbo exhaust system for emissions reductions for both E0 and E85 fuels. Vehicle emissions test results directionally correlated to the cold-start cart findings. The limited number of test runs did demonstrate the potentials of meeting stringent emission standards, however, they did not comprehend the factors such as hardware variability and long-term durability, 3 which are essential for mass production to satisfy customers’ expectations. It is therefore recommended, moving forward, durability concerns over turbocharger, EGR system and aftertreatment system, which would likely impact production viability, should be addressed. The data moreover suggested that further FE increase is likely with turbocharger technology advancement.

Wu, Ko-Jen

2011-12-31

414

Changes in Hardiness Zones  

NSDL National Science Digital Library

This animation illustrates how the hardiness zones for plants have changed between 1990 and 2006 based on an extensive updating of U.S. Hardiness Zones using data from 5,000 National Climatic Data Center cooperative stations across the continental United States.

Foundation, Arbor D.

415

Acceleration of aged-landfill stabilization by combining partial nitrification and leachate recirculation: A field-scale study.  

PubMed

Leachate recirculation for rapid landfill stabilization can result in the accumulation of high-strength ammonium. An on-site sequencing batch reactor (SBR) was therefore, applied to oxidize the ammonium to nitrite, which was then recirculated to the landfill for denitrification to nitrogen gas. At relatively higher ammonium levels, nitrite accumulated well in the SBR; the nitrite was denitrified stably in the landfill, despite an insufficient biodegradable carbon source in the leachate. As the leachate was recirculated, the methane and carbon dioxide contents produced from the landfill fluctuated, implying that the organic acids and hydrogen produced in the acid production phase acted as the carbon source for denitrification in the landfill. Leachate recirculation combined with ex-situ partial nitrification of the leachate may enhance the biodegradation process by: (a) removing the nitrogen that is contained with the leachate, and (b) accelerating landfill stabilization, because the biodegradation efficiency of landfill waste is increased by supplying sufficient moisture and its byproducts are used as the carbon source for denitrification. In addition, partial nitrification using an SBR has advantages for complete denitrification in the landfill, since the available carbon source is in short supply in aged landfills. PMID:25531070

Chung, Jinwook; Kim, Seungjin; Baek, Seungcheon; Lee, Nam-Hoon; Park, Seongjun; Lee, Junghun; Lee, Heechang; Bae, Wookeun

2015-03-21

416

Evaluation of a low-head recirculating aquaculture system used for rearing Florida pompano to market size  

Technology Transfer Automated Retrieval System (TEKTRAN)

A low-head recirculating aquaculture system (RAS) was evaluated for the production Florida pompano Trachinotus carolinus from juvenile to market size. The RAS consisted of three dual-drain, 3-m diameter culture tanks of 7.8 m3 volume each, two 0.7-m3 moving bed bioreactors filled 67% with K1 kaldnes...

417

Dynamic Control of Engine NOx Emissions: Characterization and Improvement of the Transient Response of an Exhaust Gas Recirculation System  

Microsoft Academic Search

An effective method for reducing NOx emissions from automotive engines is to use exhaust gas recirculation (EGR) to dilute the inducted air-fuel charge. Previous work has shown that degraded propagation delay and rise time characteristics of an EGR system can result in increases in NOx emissions for engine operation over dynamic rpm\\/torque versus time trajectories as exemplified by the Federal

M. J. Throop; D. R. Hamburg

1985-01-01

418

Water quality and rainbow trout performance in a Danish Model Farm recirculating system: Comparison with a flow through system  

Microsoft Academic Search

The objective was to compare water quality and fish growth and mortality in a pilot scale recirculating system (RS) and a control tank in flow through system (FTS). The RS was designed after the Danish Model Trout Farm and operated with a make up water renewal rate of 9m3kg-1 of fish produced. RS water quality did not decrease significantly with

Emmanuelle Roque d’orbcastel; Jean-Paul Blancheton; Alain Belaud

2009-01-01

419

A new method for determination of apparent kinetics parameters in recirculating packed-bed immobilized enzyme reactors  

Microsoft Academic Search

In this study, a simple and effective technique for characterizing Michaelis–Menten apparent kinetic parameters in packed-bed immobilized enzyme reactors is presented. The apparent kinetic parameters of immobilized glucose oxidase on weak base ion exchanger resin (Duolite A 568) were determined for different substrate flow rates in a recirculation system and compared with those for soluble glucose oxidase. It was observed

Ahmet R. Özdural; Deniz Tanyolaç; Zafer Demircan; ?smail H. Boyaci; Mehmet Mutlu; Colin Webb

2001-01-01

420

The effects of carbon dioxide on performance and histopathology of rainbow trout Oncorhynchus mykiss in water recirculation aquaculture systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Chronic exposure to elevated levels of dissolved carbon dioxide (CO2) has been linked to reduced growth, physiological disturbances and negative health outcomes in intensively reared fish. Although pumping to a degassing tower can lower concentrations of dissolved CO2 in water recirculation aquacult...

421

Preliminary studies on the depuration of common off-flavors from fish raised in recirculating aquaculture systems  

Technology Transfer Automated Retrieval System (TEKTRAN)

“Off-flavor” problems can adversely impact the growth of the aquaculture industry. Fish raised in recirculating systems have the potential to develop the common off-flavors “earthy” and “musty” due to accumulation of the microbial metabolites geosmin and 2-methylisoborneol (MIB) in the fish flesh. ...

422

Characterization of the microbial community and nitrogen transformation processes associated with moving bed bioreactors in a closed recirculated mariculture system  

Microsoft Academic Search

The microbial consortium of a moving bed bioreactor (MBB) connected to a marine recirculating aquaculture system was examined by denaturing gradient gel electrophoresis (DGGE) of amplified 16S rRNA gene fragments. Both ammonia and nitrite oxidizers, Nitrosomonas cryotolerans and Nitrospira marina, respectively, were found associated with the marine system as well as a number of heterotrophic bacteria, including Pseudomonas sp. and

Yossi Tal; Joy E. M. Watts; Susan B. Schreier; Kevin R. Sowers; Harold J. Schreier

2003-01-01

423

NO x emission and performance data for a hydrogen fueled internal combustion engine at 1500 rpm using exhaust gas recirculation  

Microsoft Academic Search

This paper describes six experiments conducted on a 2-liter, 4-cylinder Ford ZETEC internal combustion engine developed to operate on hydrogen fuel. The experiments were conducted to ascertain the effect exhaust gas recirculation (EGR) and a standard 3-way catalytic converter had on NOx emissions and engine performance. All the experiments were conducted at a constant engine speed of 1500rpm and each

James W Heffel

2003-01-01

424

NO x emission reduction in a hydrogen fueled internal combustion engine at 3000 rpm using exhaust gas recirculation  

Microsoft Academic Search

This paper describes five experiments conducted on a 2-l, 4-cylinder Ford ZETEC internal combustion engine (ICE) developed to operate on hydrogen fuel. The experiments were conducted to ascertain the effect exhaust gas recirculation (EGR) and a standard 3-way catalytic converter had on NOx emissions and engine performance. All the experiments were conducted at a constant engine speed of 3000 rpm

James W Heffel

2003-01-01

425

NITRIFICATION PERFORMANCE OF A PROPELLER-WASHED BEAD CLARIFIER SUPPORTING A FLUIDIZED SAND BIOFILTER IN A RECIRCULATING WARMWATER FISH SYSTEM  

Technology Transfer Automated Retrieval System (TEKTRAN)

A propeller-wash bead filter (PWBF) and a fluidized sand filter (FSF) on a 28 m3 recirculating system stocked with tilapia maintained favorable water quality at five different feed rates, ranging from 0.9 to 4.5 kg feed per day. TAN removal rates ranged up to about 200 g TAN per m3 of media per day ...

426

Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator  

NASA Technical Reports Server (NTRS)

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high-capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit Transport Water Loop. The bed design further leverages a sorbent developed for the ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System. The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of crewed spaceflight Environmental Control and Life Support System hardware.

Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2012-01-01

427

Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator  

NASA Technical Reports Server (NTRS)

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a clear demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2011-01-01

428

Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator  

NASA Technical Reports Server (NTRS)

A water loop maintenance device and process to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been undergoing a performance evaluation. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the water recirculation maintenance device and process is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance process further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware. This

Rector, Tony; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2012-01-01

429

Photocatalytic reactors for treating water pollution with solar illumination: A simplified analysis for n-steps flow reactors with recirculation  

Microsoft Academic Search

The concentration of dissolved oxygen in water, in equilibrium with atmospheric air (ca. 8ppm at 20°C), defines the limits of all practical oxidizing processes for removing pollutants in photocatalytic reactors. To solve this limitation, an alternative approach to that of a continuously aerated reactor is the use of a recirculating system with aeration performed after every cycle at the reactor

Gerd Sagawe; Rodolfo J. Brandi; Detlef Bahnemann; Alberto E. Cassano

2005-01-01

430

Design and function of a closed, recirculating seawater system with denitrification for the culture of black tiger shrimp broodstock  

Microsoft Academic Search

A closed, recirculating seawater system with a denitrification process was designed for the culture of black tiger shrimp broodstock. The system comprised a circular rearing tank (9 m3 volume), a nitrifying biofilter (6 m3 volume) and denitrification process. The denitrification process comprised a deoxygenation column, a bacterial substrate column (143 L volume) and a re-aeration column connected to the biofilter.

Piamsak Menasveta; Tanya Panritdam; Pakitsin Sihanonth; Sorawit Powtongsook; Benjamas Chuntapa; Phillip Lee

2001-01-01

431

Technicians test OV-102's aft fuselage LRU hydrogen recirculation pump  

NASA Technical Reports Server (NTRS)

Donald C. Buckner, a Lockheed mechanical lead technician, installs an aft fuselage line replaceable unit (LRU) liquid hydrogen recirculation pump from Columbia, Orbiter Vehicle (OV) 102 into JSC's Thermochemical Test Area (TTA) Support Laboratory Bldg 350 test stand. Technicians ran the pump package through the battery of leak tests. Preliminary indications showed only minor, acceptable leakage from the package and Kennedy Space Center (KSC) technicians have replaced a crushed seal on the prevalve of the main propulsion system they believe may have caused the STS-35 hydrogen leak. In addition to Buckner, (left to right) Larry Kilbourn, a Rockwell Service Center lead mechanical technician from Cape Canaveral, and John Dickerson, a quality inspector with EBASCO Services, also monitored the test at JSC. Photo taken by JSC photographer Benny Benavides.

1990-01-01

432

Statistical analysis of the influence of forces on particles in EM driven recirculated turbulent flows  

NASA Astrophysics Data System (ADS)

The present paper contains an analysis of the statistical distribution of forces affecting non-conducting particles dispersed in an EM induced recirculated flow in induction furnaces. The simulation is conducted adopting the LES-based Euler-Lagrange approach in the limit of dilute conditions (one-way coupling). It is done by means of a development of OpenFOAM software code. The used Lagrange equation for particle tracking includes drag, EM, buoyancy, lift, acceleration and added mass forces. The relevant approximations for the forces are chosen on the basis of the statistical analysis of the non-dimensional parameters (particle Reynolds number, shear stress and acceleration parameter). The effect of force distribution on particle homogenization is described under different density ratios and particle sizes. The recommendations of the consistence of the Lagrange model for the simulation of the particle motion in the laboratory scale induction crucible furnace are given in conclusion.

Š?epanskis, M.; Jakovi?s, A.; Baake, E.

2011-12-01

433

Use of exhaust gas recirculation as a control approach for thermoacoustic instabilities  

SciTech Connect

Investigation into exhaust gas recirculation (EGR) as a method for reducing costs of postcombustion carbon capture in gas turbine systems reveals that EGR offers potential applications as a control strategy for thermoacoustic instabilities. Introduction of EGR allows semi-independent variation of the operating parameter of flame temperature and characteristic flame length scales, known to play a primary role in the phase of the thermoacoustic coupling mechanism. Measurements were made showing the ability of EGR to reduce the amplitude of thermoacoustic oscillations over a range of operating conditions in a laboratory scale, swirled dump combustor, without affecting the flame temperature. Theoretical analysis was also performed to investigate the limitations on the ability of this approach to influence dynamics.

Ranalli, J.; Ferguson, D.

2011-10-09

434

Biomass production from fermented starch wastewater in photo-bioreactor with internal overflow recirculation.  

PubMed

A photo-bioreactor with internal overflow recirculation was applied to treat real fermented starch wastewater and convert it to photosynthetic biomass for further utilization. The photo-bioreactor was operated at a hydraulic retention time of 10days by circulating mixed liquor through overflow pipes and penetrating light through infrared transmitting filter. During the operation of 154days, the average BOD and COD removals were 95% and 88%, respectively. Majority of photosynthetic bacteria was found attached on pipes as biofilm contributed to 82% of total biomass production. Photosynthetic biomass yield was 0.51g dried solid/g BOD removed and crude protein content of 0.58g/g dried solid. Rhodopseudomonas palustris was found in the photosynthetic system as the predominant bacterial group by denaturing gradient gel electrophoretic analysis (DGGE) and 16S rDNA sequencing method. PMID:24745900

Prachanurak, Pradthana; Chiemchaisri, Chart; Chiemchaisri, Wilai; Yamamotob, Kazuo

2014-08-01

435

A Computer Code for Swirling Turbulent Axisymmetric Recirculating Flows in Practical Isothermal Combustor Geometries  

NASA Technical Reports Server (NTRS)

A primitive pressure-velocity variable finite difference computer code was developed to predict swirling recirculating inert turbulent flows in axisymmetric combustors in general, and for application to a specific idealized combustion chamber with sudden or gradual expansion. The technique involves a staggered grid system for axial and radial velocities, a line relaxation procedure for efficient solution of the equations, a two-equation k-epsilon turbulence model, a stairstep boundary representation of the expansion flow, and realistic accommodation of swirl effects. A user's manual, dealing with the computational problem, showing how the mathematical basis and computational scheme may be translated into a computer program is presented. A flow chart, FORTRAN IV listing, notes about various subroutines and a user's guide are supplied as an aid to prospective users of the code.

Lilley, D. G.; Rhode, D. L.

1982-01-01

436

Possible role for cell-surface carbohydrate-binding molecules in lymphocyte recirculation  

PubMed Central

We are investigating the hypothesis that carbohydrate-binding molecules on the cell surface are involved in the recirculation of lymphocytes from the bloodstream into lymphoid organs. This phenomenon requires the specific attachment of circulating lymphocytes to the endothelial cells of postcapillary venules. Using an in vitro assay to measure the adhesive interaction between lymphocytes and postcapillary venules, we have found that L-fucose, D mannose, and the L-fucose-rich, sulfated polysaccharide fucoidin specifically inhibit this binding interaction. L-fucose shows stereo-selective inhibitory activity at concentrations greater than 18 mM while fucoidin produces 50% inhibition at approximately 1-5 X 10(-8) M. Fucoidin appears to interact with the lymphocyte, and not the postcapillary venule, to inhibit binding. These data suggest that cell surface carbohydrates (fucoselike) and carbohydrate-binding molecules (cell surface lectins) may contribute to the specific attachment of lymphocytes to postcapillary venules. PMID:6833380

1983-01-01

437

Two-operator glucose infusion test (GIT2) for vascular access recirculation measurement during hemodialysis.  

PubMed

Vascular access recirculation rate (AR) monitoring is fundamental to guarantee treatment adequacy and to detect access failure early. We have evaluated the GIT2 test to measure AR unaffected by cardio-pulmonary recirculation (CPR), based on a short glucose infusion in place of the bolus and on a two-operator sampling, differently from the classical glucose infusion test (GIT). The GIT2 test is based on four steps: 1) basal (B) glucose arterial sample; 2) 10% glucose infusion for 1 min, by infusion pump at 600 ml/hr; (or 20% at 300 ml/hr); 3) simultaneous sampling at arterial (A) and venous (V) ports, after 35-40 sec from starting the infusion, taking care to avoid blood pump stop during the test; 4) AR=100*((A-B)/(V-B)). In vitro tests by dialysis on a 40 L tank containing a urea solution, with AR volumetrically simulated at 0, 5, 10, 20%, and in vivo comparison of GIT, GIT2 with stop-flow (SF) urea method. Our results have shown in vitro an almost perfect correspondence of SF urea method and a better reliability of GIT2 than GIT. The methylene-blue test has shown that a single color bolus in V reaches the A port after variable time, depending on blood flow and AR, while the continuous infusion determines a steady gradient after about 30". In vivo tests (n=24) show good correspondence between GIT2 (4.37 +/- 3.36) and SF (4.51 +/- 3.62), while GIT data (1.01 +/- 0.51) are significantly underestimated. In conclusion, our preliminary results have evidenced a good reliability of the new test, the continuous infusion causing a steady gradient in V and A that more precisely reflects the AR rate. PMID:20383860

Bosticardo, Gian Mario; Morellini, Veronica; Schillaci, Enrico; Battisti, Marco; Norza, Massimo; Detoma, Paolo; Forneris, Giacomo; Filiberti, Oliviero; Bajardi, Pietro

2010-01-01

438

Low frequency ultrasound and UV-C for elimination of pathogens in recirculating aquaculture systems.  

PubMed

Low frequency ultrasound (LFUS) was evaluated as a novel disinfection technique within recirculating aquaculture systems both individually and combined with UV-C. Dose-dependent inactivation rates were determined for the total viable counts and model organisms representing different taxa of common fish parasites: the ciliate Paramecium sp., second larval stage (L2) of the nematode Anguillicola crassus and metanauplii of Artemia sp. Application of LFUS up to 19 kJ/L did not reduce the number of colony forming units (CFU), whilst UV-C irradiation was highly effective. Pre-treatment with LFUS reduced the mean size of suspended solids in aquaculture water and thus increased the germicidal effect of UV-C by up to 0.6 log units. LFUS was effective against the eukaryotic organisms, and the dose-dependent inactivation could be well described by functions of an exponential decay. However, the efficiency of LFUS differed greatly between species. A LFUS dose of 1.9 kJ/L (consumed energy) was sufficient to inactivate Artemia by 99%, but a ten times higher dose was necessary to inactivate 95% and 81% of Paramecium and Anguillicola larvae, respectively. In clear water, the energetic efficiency of UV-C (emitted by a low pressure lamp) against Paramecium and Anguillicola larvae was higher compared to LFUS, but LFUS was more efficient against Artemia. However, the efficiency of LFUS against ciliates or nematode larvae would be similar or even higher than UV-C in highly turbid water or if less efficient medium pressure lamps are used. This study shows that LFUS can be applied safely at energy densities that are effective against a wide range of parasites like ciliates, nematodes and crustaceans. The combination of LFUS and UV-C could provide an appropriate water treatment with regards to all relevant pathogens in recirculating aquaculture systems. PMID:23434531

Bazyar Lakeh, Amir Abbas; Kloas, Werner; Jung, Rainer; Ariav, Ra'anan; Knopf, Klaus

2013-09-01

439

Directional Migration of Recirculating Lymphocytes through Lymph Nodes via Random Walks  

PubMed Central

Naive T lymphocytes exhibit extensive antigen-independent recirculation between blood and lymph nodes, where they may encounter dendritic cells carrying cognate antigen. We examine how long different T cells may spend in an individual lymph node by examining data from long term cannulation of blood and efferent lymphatics of a single lymph node in the sheep. We determine empirically the distribution of transit times of migrating T cells by applying the Least Absolute Shrinkage & Selection Operator () or regularised to fit experimental data describing the proportion of labelled infused cells in blood and efferent lymphatics over time. The optimal inferred solution reveals a distribution with high variance and strong skew. The mode transit time is typically between 10 and 20 hours, but a significant number of cells spend more than 70 hours before exiting. We complement the empirical machine learning based approach by modelling lymphocyte passage through the lymph node . On the basis of previous two photon analysis of lymphocyte movement, we optimised distributions which describe the transit times (first passage times) of discrete one dimensional and continuous (Brownian) three dimensional random walks with drift. The optimal fit is obtained when drift is small, i.e. the ratio of probabilities of migrating forward and backward within the node is close to one. These distributions are qualitatively similar to the inferred empirical distribution, with high variance and strong skew. In contrast, an optimised normal distribution of transit times (symmetrical around mean) fitted the data poorly. The results demonstrate that the rapid recirculation of lymphocytes observed at a macro level is compatible with predominantly randomised movement within lymph nodes, and significant probabilities of long transit times. We discuss how this pattern of migration may contribute to facilitating interactions between low frequency T cells and antigen presenting cells carrying cognate antigen. PMID:23028891

Thomas, Niclas; Matejovicova, Lenka; Srikusalanukul, Wichat; Shawe-Taylor, John; Chain, Benny

2012-01-01

440

Mathematical Modeling Reveals Kinetics of Lymphocyte Recirculation in the Whole Organism  

PubMed Central

The kinetics of recirculation of naive lymphocytes in the body has important implications for the speed at which local infections are detected and controlled by immune responses. With a help of a novel mathematical model, we analyze experimental data on migration of 51Cr-labeled thoracic duct lymphocytes (TDLs) via major lymphoid and nonlymphoid tissues of rats in the absence of systemic antigenic stimulation. We show that at any point of time, 95% of lymphocytes in the blood travel via capillaries in the lung or sinusoids of the liver and only 5% migrate to secondary lymphoid tissues such as lymph nodes, Peyer's patches, or the spleen. Interestingly, our analysis suggests that lymphocytes travel via lung capillaries and liver sinusoids at an extremely rapid rate with the average residence time in these tissues being less than 1 minute. The model also predicts a relatively short average residence time of TDLs in the spleen (2.5 hours) and a longer average residence time of TDLs in major lymph nodes and Peyer's patches (10 hours). Surprisingly, we find that the average residence time of lymphocytes is similar in lymph nodes draining the skin (subcutaneous LNs) or the gut (mesenteric LNs) or in Peyer's patches. Applying our model to an additional dataset on lymphocyte migration via resting and antigen-stimulated lymph nodes we find that enlargement of antigen-stimulated lymph nodes occurs mainly due to increased entrance rate of TDLs into the nodes and not due to decreased exit rate as has been suggested in some studies. Taken together, our analysis for the first time provides a comprehensive, systems view of recirculation kinetics of thoracic duct lymphocytes in the whole organism. PMID:24830705

Ganusov, Vitaly V.; Auerbach, Jeremy

2014-01-01

441

Discovery on the fault zone structure from fault-zone in-situ TCDP borehole seismometers  

NASA Astrophysics Data System (ADS)

We use the borehole array data collected along the Chelungpu fault zone, Taiwan, since November 2006, to give the close-in observations of the fault zone structure and dynamics after the 1999 Mw 7.6 Chi-Chi earthquake. Several features had been observed. 1. A complete stress drop and locked during the inter-seismic period in the co-seismic large slip zone (slip>12m). The high resolution TCDP borehole seismometers detected no any micro earthquakes with magnitude down to M0.3 in the co-seismic slip zone. 2. Observation of non-shearing events. A non-shear failure event (I-type events) occurred in a fluid-rich permeable zone directly below the impermeable slip zone of the 1999 Mw 7.6 Chi-Chi earthquake. This might be related to rock failure induced by high fluid pressure by opening cavities and cracks. These seismic events may be associated with the formation of veins and other fluid features often observed in rocks surrounding fault zones and may be similar to artificially induced hydraulic fracturing. 3. Determination of the fault zone Q structure. Very low Qs and Qp of 21-22 and 27-35, respectively, in the zone associated to the co-seismic slip (within about 150m above the primary slip zone identified from retrieved drilling core), suggesting highly fractured fault zone. The similar values to the study within the San Andreas Fault, might suggest that the Q structure within the fault zone is sedimentary rock independent. 4. Leaking waves or trap waves from the thin low velocity fault zone. A 3D finite-difference simulation of the fault zone structure (with grid size of 3 m) shows the generation of P-SV leaking wave from the thin low velocity thrust dipping fault zone. Fault zone velocity structure from logging, spatial distribution of the seismicity and locations of the I-type (Isotropic) events. wave interaction within fault zone

Ma, K.; Lin, Y.; Wang, Y.

2013-12-01

442

Analysis of post-tensioned girder anchorage zones  

NASA Astrophysics Data System (ADS)

Several large thin-webbed box girders, with post-tensioned anchorage zones experienced large cracks along the tendon path in the anchorage zones at the design stressing load. Cracking provides a path for penetration of moisture and salts and thus presents a potential corrosion and frost damage threat. Such cracking negates the use of prestressed concretes. An extensive literature review which documents the state of the art in anchorage zone analysis behavior, and design recommendations is summarized. The general utilization of a three dimensional finite element program, PUZGAP3D, for analysis of the complex anchorage zone region is outlined. The program was used to study straight and curved tendon paths.

Stone, W. C.; Breen, J. E.

1981-06-01

443

The global aftershock zone (Invited)  

NASA Astrophysics Data System (ADS)

There is little doubt that the whole planet becomes the aftershock zone of large (M?7) earthquakes. Surface waves distort fault zones and volcanic centers as they pass through the crust, leading to seismic failures. From a hazard perspective we are obviously concerned that this dynamic process might encourage high magnitude earthquakes. Great strides have been made in operational earthquake forecasting near mainshocks in time and space, but we are far less certain how to assess the hazard posed at global distances. Results from global compilations demonstrate significant rate increases during, and immediately after (~45 minutes) M>7.0 mainshocks in all tectonic settings and ranges. However, it is difficult to find strong evidence for M>5 rate increases during the passage of surface waves in combined global catalogs. On the other hand, studies of individual large mainshocks correlate M>5 triggering at global range that is delayed by hours to days after surface wave arrivals. These examples tend to lie in the noise when the global catalogs are examined simultaneously, which implies that they are relatively rare events. However, if large triggered earthquakes can occur in the global aftershock zone, then we must be concerned about how to calculate and convey the hazard they pose. Results from comparative responses of individual regions to hundreds of global M>7 mainshocks give us some preliminary insights into the likelihood of damaging global aftershocks. About 50% of the catalogs we studied showed possible (delayed) remote triggering, and ~20% showed probable (instantaneous) remote triggering. However, in any given region, at most only about 2-3% of global mainshocks cause significant local earthquake rate increases. We note that surface wave amplitude, mainshock magnitude, and relative proximity are not important factors in determining which mainshocks cause remote triggering. Instead, azimuth, and polarization of surface waves with respect to receiver faults appear to be more important factors.

Parsons, T.; Segou, M.; Marzocchi, W.

2013-12-01

444

Seismic coupling and uncoupling at subduction zones  

NASA Technical Reports Server (NTRS)

Some of the correlations concerning the properties of subduction zones are reviewed. A quantitative global comparison of many subduction zones reveals that the largest earthquakes occur in zones with young lithosphere and fast convergence rates. Maximum earthquake size is directly related to the asperity distribution on the fault plane. This observation can be translated into a simple model of seismic coupling where the horizontal compressive stress between two plates is proportional to the ratio of the summed asperity area to the total area of the contact surface. Plate age and rate can control asperity distribution directly through the horizontal compressive stress associated with the vertical and horizontal velocities of subducting slabs. The basalt to eclogite phase change in the down-going oceanic crust may be largely responsible for the uncoupling of subduction zones below a depth of about 40 km.

Ruff, L.; Kanamori, H.

1983-01-01

445

www.VadoseZoneJournal.org Vadose Zone Journal  

E-print Network

, biofuels, sustainability, and nanotechnology. Since its inception, Vadose Zone Journal has grown tre issues in vadose zone hydrology, uncertainty analyses, inverse modeling, fractal mathematics, ecosystem

Vrugt, Jasper A.

446