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1

Prediction of recirculation zones in isothermal coaxial jet flows relevant to combustors  

NASA Technical Reports Server (NTRS)

The characteristics of the recirculation zones in confined coaxial turbulent jets are investigated numerically employing the kappa - epsilon turbulence model. The geometrical arrangement corresponds to the experimental study of Owen (AIAA J. 1976) and the investigation is undertaken to provide information for isothermal flow relevant to combustor flows. For the first time, the shape, size, and location of the recirculation zones for the above experimental configuration are correctly predicted. The processes leading to the observed results are explained. Detailed comparisons of the prediction with measurements are made. It is shown that the recirculation zones are very sensitive to the central jet exit configuration and the velocity ratio of the jets.

Nallasamy, M.

1987-01-01

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

Flow Field Features of the Induced Recirculation Zone using Planar Jet Injection.  

NASA Astrophysics Data System (ADS)

The objective of the present work is to study the recirculation bubble induced by injecting a planar jet in to a channel flow. The work is motivated by the desire to provide a flame stabilization environment for ramjet engines without the use of a sudden expansion or bluff-body which incurs drag penalties. A planar jet issuing into a cross flow is used to create a recirculation zone reminiscent of the flow field created downstream of a rearward-facing step configuration which is used in a current ramjet/scramjet systems. The effect of confinement at high momentum flux ratios leads to a saturation of the control of the recirculation bubble size and strength. Comparison to a rearward-facing step flow shows the current method produces higher turbulence levels and larger integral length scales. It is clear that the flow field produced with fluidic injection has potential for flame anchoring and enhancing combustion rates.

Ahmed, Kareem; Forliti, David; Moody, Jack

2006-11-01

4

Vortex formation and recirculation zones in left anterior descending artery stenoses: computational fluid dynamics analysis  

NASA Astrophysics Data System (ADS)

Flow patterns may affect the potential of thrombus formation following plaque rupture. Computational fluid dynamics (CFD) were employed to assess hemodynamic conditions, and particularly flow recirculation and vortex formation in reconstructed arterial models associated with ST-elevation myocardial infraction (STEMI) or stable coronary stenosis (SCS) in the left anterior descending coronary artery (LAD). Results indicate that in the arterial models associated with STEMI, a 50% diameter stenosis immediately before or after a bifurcation creates a recirculation zone and vortex formation at the orifice of the bifurcation branch, for most of the cardiac cycle, thus allowing the creation of stagnating flow. These flow patterns are not seen in the SCS model with an identical stenosis. Post-stenotic recirculation in the presence of a 90% stenosis was evident at both the STEMI and SCS models. The presence of 90% diameter stenosis resulted in flow reduction in the LAD of 51.5% and 35.9% in the STEMI models and 37.6% in the SCS model, for a 10 mmHg pressure drop. CFD simulations in a reconstructed model of stenotic LAD segments indicate that specific anatomic characteristics create zones of vortices and flow recirculation that promote thrombus formation and potentially myocardial infarction.

Katritsis, D. G.; Theodorakakos, A.; Pantos, I.; Andriotis, A.; Efstathopoulos, E. P.; Siontis, G.; Karcanias, N.; Redwood, S.; Gavaises, M.

2010-03-01

5

Mixer assembly for a gas turbine engine having a pilot mixer with a corner flame stabilizing recirculation zone  

NASA Technical Reports Server (NTRS)

A mixer assembly for a gas turbine engine is provided, including a main mixer, and a pilot mixer having an annular housing in which a corner is formed between an aft portion of the housing and a bulkhead wall in which a corner recirculation zone is located to stabilize and anchor the flame of the pilot mixer. The pilot mixer can further include features to cool the annular housing, including in the area of the corner recirculation zone.

Dai, Zhongtao (Inventor); Cohen, Jeffrey M. (Inventor); Fotache, Catalin G. (Inventor)

2012-01-01

6

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

7

Tracer Gas Measurement of Airflow Rates in Spaces with Several Air-Handling Units, Recirculation, or Large Time Constants  

Microsoft Academic Search

Methods to measure airflow rates using tracer gas in single air-handling units are well known. In some buildings, however, in particular in Singapore, rooms are often ventilated with two or more units and present large recirculation rates. Large recirculation ratios homogenize the concentrations, so concentrations in supply and extract ducts are close to each other. In addition, these spaces often

C.-A. Roulet; M. S. Zuraimi; S. C. Sekhar; K. W. Tham

2006-01-01

8

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

9

Evaluating the effects of organic carbon on biological filtration performance in a large scale recirculating aquaculture system  

Microsoft Academic Search

Studies evaluating the impact of organic carbon on biological filters at the large scale for aquaculture production are lacking. Understanding the performance characteristics of different biofilters under actual production conditions will be the only means by which recirculating system designers may properly select and size biological filters for commercial production use. Previous studies have determined the impact of organic carbon

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

2011-01-01

10

Exhaust gas recirculation system  

Microsoft Academic Search

An exhaust gas recirculation system comprises a valve assembly for controlling the recirculation of exhaust gases in such a manner as to maintain a difference between a first and second pressure at a predetermined value. The first pressure is a pressure in a zone in an air induction passage between a throttle valve therein and a flow restrictor disposed therein

Aoyama

1980-01-01

11

Recirculating rotary gas compressor  

DOEpatents

A positive displacement, recirculating Roots-type rotary gas compressor is described which operates on the basis of flow work compression. The compressor includes a pair of large diameter recirculation conduits which return compressed discharge gas to the compressor housing, 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 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. 12 figs.

Weinbrecht, J.F.

1992-02-25

12

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

13

Demonstration of the Feasibility of Large Port Count Optical Switching Using a Hybrid MZI SOA Switch Module in a Recirculating Loop  

E-print Network

Demonstration of the Feasibility of Large Port Count Optical Switching Using a Hybrid MZI-SOA Switch Module in a Recirculating Loop Q. Cheng*, A. Wonfor, J. L. Wei, R. V. Penty, and I. H. White Centre for Photonic Systems, Electrical Engineering...

Cheng, Q.; Wonfor, A.; Wei, J. L.; Penty, R. V.; White, I. H.

2014-09-02

14

Exhaust gas recirculation system  

Microsoft Academic Search

In an exhaust gas recirculation system for internal combustion engines having a detachable gasket member between an exhaust gas recirculation valve and an exhaust pipe of the engine, the exhaust gas recirculation rate is controlled by a flow control orifice formed in the detachable gasket member. The recirculation valve can be applied to various types of engines requiring various recirculation

K. Numata; Y. Muramatu

1977-01-01

15

Redesigning exhaust-gas recirculation systems in sintering  

Microsoft Academic Search

The recirculation of hot gases (air from the sinter coolers or the cooling zone, sintering waste gases) permits energy conservation and environmental protection in sinter production. A benefit of gas recirculation is the reduced atmospheric emission of harmful materials (CO, CO 2 , H 2 S, SO 2 ) and dust. One common method of hot-gas recirculation is to return

A. A. Vyatkin; S. S. Skachkova; E. G. Dmitrieva; R. N. Shumilov; A. Yu. Morozov

2008-01-01

16

Evidence for large earthquakes at the Cascadia subduction zone  

Microsoft Academic Search

Large, historically unprecedented earthquakes at the Cascadia subduction zone in western North America have left signs of sudden land level change, tsunamis, and strong shaking in coastal sediments. The coastal geological evidence suggests that many of the earthquakes occurred at the boundary between the overriding North American plate and the subducting Juan de Fuca plate. This hypothesis is consistent with

John J. Clague

1997-01-01

17

Exhaust gas recirculation system  

Microsoft Academic Search

An exhaust gas recirculation system is disclosed which includes a control valve inserted in an exhaust gas recirculation passageway for controlling the flow rate of the exhaust gases to be recirculated, a constant pressure chamber defined in the recirculation passageway upstream of the control valve, and a modulator valve with a diaphragm chamber in communication with the constant pressure chamber

S. Nakamura; H. Nohira; H. Tokuda

1980-01-01

18

Exhaust gas recirculation system  

Microsoft Academic Search

In response to the operation of an internal combustion engine, an input signal pressure is developed which differs from the atmospheric pressure by more than a first predetermined amount when exhaust gas recirculation is desirable. A recirculation valve then opens to permit the recirculation of exhaust gases from the exhaust passage to the intake passage of the engine. In response

1975-01-01

19

Exhaust gas recirculating system  

Microsoft Academic Search

An internal combustion engine equipped with an exhaust gas recirculating system is described. The exhaust gas recirculating system comprises an EGR valve normally closing an EGR duct to prevent recirculation and movable by a signal vacuum applied thereto to an open position and control means operable to provide a signal vacuum. The control means includes a vacuum line connecting a

Harada

1978-01-01

20

Exhaust gas recirculation system  

Microsoft Academic Search

An auxiliary flow control valve is disposed in an exhaust gas recirculation passageway at a location upstream of a main flow control valve controlling the flow rate of exhaust gases recirculated into an intake system. Two conduits communicating with an intake manifold communicate with a vacuum chamber of a servo motor controlling the main flow control valve. One of the

Y. Fujikawa; Y. Nakajima; Y. Hayashi; K. Sugihara; Y. Hase

1976-01-01

21

Exhaust gas recirculation system  

Microsoft Academic Search

Apparatus for controlling exhaust gas recirculation in an internal combustion engine employs a first control valve in an exhaust gas recirculation passageway, a second control valve in an air conduit connecting the intake passage to atmosphere through selective restriction means, and a regulating valve responsive to differential vacuum intensities for actuating the control valves. The restriction means comprise a plurality

Y. Itoh; A. Totsune; H. Yamabe

1982-01-01

22

Exhaust gas recirculation system  

Microsoft Academic Search

In a diesel engine having a turbocharger for feeding supercharged air to the engine, an exhaust gas recirculation passage communicates between the exhaust passage from the engine and the intake passage to a compressor of the turbocharger. A first control valve closes the exhaust gas recirculation passage when the output pressure of the air leading from the compressor is lower

Yoshiba

1982-01-01

23

EXHAUST GAS RECIRCULATION  

E-print Network

EXHAUST GAS RECIRCULATION (EGR) COOLER TESTING Southwest Research Institute® #12;overnment) and oxides of nitrogen (NOx). The use of exhaust gas recirculation (EGR) coolers is considered research, offers complete facilities for testing diesel engines and their emissions control systems

Chapman, Clark R.

24

Exhaust gas recirculation system  

Microsoft Academic Search

An exhaust gas recirculation system for use in an internal combustion engine includes an intake manifold having a riser portion serving as a heating source for an intake mixture charge, an exhaust gas recirculation passage running from an exhaust manifold to an intake system for introducing part of exhaust gases from the former to the latter, and a temperature-responsive valve

N. Kawai; H. Yamamoto

1980-01-01

25

Exhaust gas recirculator  

Microsoft Academic Search

An exhaust gas recirculator for an internal combustion engine having an exhaust pipe, an intake manifold and a carburetor throttle valve. The exhaust gas recirculator comprises an egr passage which makes the exhaust pipe communicate with the intake manifold, an egr controlling valve and an egr valve respectively arranged in the upper and lower portions of the egr passage. The

Suda

1983-01-01

26

Lattice Design for the LHEC Recirculating Linac  

SciTech Connect

In this paper, we present a lattice design for the Large Hadron Electron Collider (LHeC) recirculating linac. The recirculating linac consists of one roughly 3-km long linac hosting superconducting RF (SRF) accelerating cavities, two arcs and one transfer line for the recirculation. In two passes through a pulsed SRF linac the electron beam can get a maximum energy of 140 GeV. Alternatively, in the Energy Recovery Linac (ERL) option the beam passes through a CW linac four times (two passes for acceleration and two for deceleration) for a maximum energy of 60 GeV.

Sun, Yipeng; /CERN; Eide, Anders; /CERN; Zimmermann, Frank; /CERN; Adolphsen, Chris; /SLAC

2011-05-20

27

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...

28

Exhaust gas recirculation system  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine is disclosed in which an exhaust gas control valve and a pressure regulating valve is constructed as one body to facilitate the mounting of the system on the engine and to improve the response characteristic of the system. Also, the chamber of the pressure regulating valve opposite to the chamber

S. Hayashi; N. Shibata; Y. Takahara; S. Yamada

1981-01-01

29

Exhaust gas recirculation system  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine. The internal combustion engine including at least one combustion chamber; an intake mechanism for delivering a combustible fluid mixture to the combustion chamber; an ignition system for igniting the combustible mixture; and an exhaust system for carrying exhaust fluid produced by the combustion of the combustible fluid mixture away from

Freesh

1982-01-01

30

Exhaust gas recirculating system  

Microsoft Academic Search

This patent describes an exhaust gas recirculating system for an internal combustion engine having an intake passage, a main throttle valve located in the intake passage, and an exhaust passage. The engine is installed in an automotive vehicle provided with a traction control system including means for sensing slippage of a drive wheel of the vehicle during acceleration, a second

H. Takahashi; T. Naganawa

1988-01-01

31

Exhaust gas recirculation system  

Microsoft Academic Search

An exhaust gas recirculation system for cleaning exhaust gas from an internal combustion engine is provided in which a variable constriction is provided between an intake pipe and a pressure control valve in operative connection to a throttle valve in the carburetor and the pressure differential across said variable constriction is maintained constant to keep off any influence of the

M. Minoura; K. Yorioka

1980-01-01

32

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

33

Exhaust gas recirculation system  

Microsoft Academic Search

The EGR control system comprises EGR control valve means including a first fluid chamber the vacuum in which increases and decreases in accordance with operating conditions of the engine whereby EGR control valve means control the recirculated amount of exhaust gases back to the engine and a second fluid chamber receiving therein a suction vacuum to thereby cause multiplication of

Aoyama

1979-01-01

34

Exhaust gas recirculation system  

Microsoft Academic Search

An exhaust gas recirculation system is described for an engine having a throttle valve in an intake passage, comprising: the intake passage having an EGR port provided adjacent to the upstream side of the throttle valve at the closed position. A control port provides a position at downstream of the throttle valve at the closed position. A leak port provides

Sugiura

1987-01-01

35

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

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Security and Safety Zone; Large Passenger Vessel... COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PORTS AND WATERWAYS SAFETY...Coast Guard District § 165.1317 Security and Safety Zone; Large Passenger...

2011-07-01

36

Airlift recirculation well test results -- Southern sector  

SciTech Connect

Chlorinated solvents used in the A and M-Areas at the Savannah River Site (SRS) from 1952--1982 have contaminated the groundwater under the site. A plume of groundwater contaminated with trichloroethylene (TCE) and perchloroethylene (PCE) in the Lost Lake aquifer is moving generally southward with the natural flow of groundwater. To comply with the requirements of the current SCDHEC Part B Permit, a series of wells is being installed to contain and treat the plume. Airlift Recirculation Wells (ARW) are a new and innovative technology with potential for more cost effective implementation than conventional pump and treat systems. Two Airlift Recirculation Wells have been installed and tested to quantify performance parameters needed to locate a line of these wells along the leading edge of the contaminant plume. The wells proved to be very sensitive to proper development, but after this requirement was met, performance was very good. The Zone of Capture has been estimated to be within a radius of 130--160 ft. around the wells. Thus a line of wells spaced at 250 ft. intervals could intercept the contaminant plume. At SSR-012, TCE was stripped from the groundwater at approximately 1.2 lb./day. The longer term effect of the recirculation wells upon the plume and the degree of recirculation within the aquifer itself will require additional data over a longer time period for an accurate review. Data collection is ongoing.

White, R.M.; Hiergesell, R.A.

1997-08-01

37

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

38

Exhaust gas recirculation system  

SciTech Connect

An exhaust gas recirculation system is described for an engine having a throttle valve in an intake passage, comprising: the intake passage having an EGR port provided adjacent to the upstream side of the throttle valve at the closed position. A control port provides a position at downstream of the throttle valve at the closed position. A leak port provides at upstream of the throttle valve; an EGR valve recirculates exhaust gases to the intake passage. The EGR valve has a diaphragm defining a first chamber applied with the pressure at the EGR port and a second chamber is applied with the pressure at the leak port. A valve body connects to the diaphragm for controlling the amount of recirculated gases; a control valve has a diaphragm defining a first control chamber and a second control chamber, and valve means on the diaphragm. The first control chamber is pressured at the EGR port. The second control chamber is applied with the pressure at the control port through a first conduit having an end port and with the pressure at the leak port through a second conduit. The valve means is arranged to open the end port of the first conduit when the difference between pressures in the first and second control chambers exceeds a predetermined value. Pressure regulating means renders the pressure in the second control chamber lower than the pressure in the second chamber of the EGR valve.

Sugiura, K.

1987-08-04

39

Hydraulics of recirculating well pairs for ground water remediation.  

PubMed

Recirculating well pairs are a proven means of implementing bioremediation and may also be useful for applying other in situ ground water remediation technologies. A bromide tracer test was performed to characterize the hydraulic performance of a recirculating well pair installed at Moffett Field, California. In particular, we estimate two important properties of the recirculating well pair: (1) the fraction of captured water that is recycled between the wells, and (2) the travel-time distribution of ground water in the induced zone of recirculation. We also develop theoretical estimates of these two properties and demonstrate they depend upon a dimensionless pumping rate, denoted xi. The bromide breakthrough curve predicted from theory agrees well with that determined experimentally at Moffett Field. The minimum travel time between the wells is denoted t(min). In theory, t(min) depends inversely on Q, the pumping rate in the recirculating wells, and is proportional to a2, the square of the distance between the wells. Both the experimental and theoretical travel-time distributions indicate that at least half the recirculating water travels between the wells along fast flowpaths (travel time < 2*t(min)). Therefore, when designing recirculating well pairs, engineers should ensure that t(min) will be sufficiently high to allow biologically mediated reactions (or other in situ remediation processes) sufficient time to proceed. PMID:15584301

Cunningham, Jeffrey A; Hoelen, Thomas P; Hopkins, Gary D; Lebrón, Carmen A; Reinhard, Martin

2004-01-01

40

Combustion-gas recirculation system  

Microsoft Academic Search

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

Darryl Dean

2007-01-01

41

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

42

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

43

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

44

Exhaust gas recirculator  

SciTech Connect

An exhaust gas recirculator for an internal combustion engine having an exhaust pipe, an intake manifold and a carburetor throttle valve. The exhaust gas recirculator comprises an egr passage which makes the exhaust pipe communicate with the intake manifold, an egr controlling valve and an egr valve respectively arranged in the upper and lower portions of the egr passage. The egr valve operates in association with the carburetor throttle valve for metering the flow of egr gas. The egr controlling valve is separated by a diaphragm into an egr gas chamber communicating with the egr passage between the egr controlling valve and the egr valve and a negative pressure chamber communicating with the intake manifold. The negative pressure chamber contains a compression spring, and the diaphragm is connected with a valve member through a rod upon which is disposed a stopper to serve as a different seal in place of the valve member to close off the exhaust gas passage, which valve member and stopper are constructed to be opened and closed by pressure difference between the egr gas chamber and the negative pressure chamber and by elastic force of the compression spring. The egr controlling valve functions to control the pressure difference around the egr valve to be constant.

Suda, K.

1983-01-04

45

On the development of a 3D cohesive zone element in the presence of large deformations  

Microsoft Academic Search

Delamination is typically modelled using cohesive zone models. In this paper, it is shown that the validity of most models\\u000a is limited to small displacements and\\/or deformations at the interface and the surrounding bulk materials. A large displacement\\u000a formulation (LDF) is proposed that overcomes issues of the classical formulation with large displacements and deformations\\u000a at the interface. Subsequently, a 3D

M. J. van den Bosch; P. J. G. Schreurs; M. G. D. Geers

2008-01-01

46

Engine exhaust gas recirculation system  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine employs a recirculation control valve in a passageway connecting the engine exhaust passage to the engine intake passage downstream from the throttle valve. An air conduit having an air control valve therein furnishes atmospheric air to the intake passage downstream from the throttle valve. Vacuum responsive actuators are provided for

H. Nishimura; T. Shioya; T. Umemoto

1981-01-01

47

Engine exhaust gas recirculation system  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine employs a recirculation control valve in a passageway connecting the engine exhaust passage to the engine intake passage downstream from the throttle valve. An air conduit having an air control valve therein draws atmospheric air into the intake passage downstream from the throttle valve. Vacuum responsive actuators are provided for

K. Ishii; H. Nishimura; K. Osawa

1981-01-01

48

The Impact of Accretionary Prism Heterogeneity on Seafloor Displacement during Large Subduction Zone Earthquakes  

NASA Astrophysics Data System (ADS)

Large earthquakes often occur in sediment dominated subduction zones where large accretionary prisms have formed. Deformation within the prism creates heterogeneity that can be very difficult to incorporate into models of rupture and coseismic seafloor deformation. Finite element modeling was used to assess the impact of prism heterogeneity on coseismic seafloor displacement. The modeling was based on information from the Nankai Trough subduction zone, where a large splay fault system (the megasplay) carries older sediments over younger, less consolidated sediments. This region is being investigated as part of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE). The major fault zones were incorporated into the model as frictional contacts. Different frictional properties were assigned to the deep portion of the plate boundary fault, the shallow portion of the plate boundary fault, and the megasplay fault. To simulate the earthquake cycle, a lower coefficient of friction was applied to the deep portion of the megathrust during the earthquake than during the interseismic period. This approach allowed stress to build up in the model region prior to the earthquake. Seafloor displacement was compared for simulations with a homogeneous prism and for simulations in which the splay fault's footwall was weaker than the hanging wall. The weaker footwall resulted in greater horizontal seafloor displacement but less vertical displacement than the homogeneous case. This difference in seafloor deformation may have implications for tsunami hazards.

Screaton, E.; Ge, S.; Regueiro, R.

2010-12-01

49

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

50

Analysis of linear alkylbenzenesulfonates by capillary zone electrophoresis with large-volume sample stacking  

Microsoft Academic Search

A systematic investigation of optimal conditions for determining the homologues of linear alkylbenzenesulfonates (LAS) by capillary zone electrophoresis (CZE) using the large-volume sample stacking technique was presented. The most effective sample stacking and separation conditions was 20 mM borate buffer with 30% acetonitrile at pH 9.0, and the sample hydrodynamic injection of up to 90 s at 4 p.s.i. (1

Wang-Hsien Ding; Chi-Hung Liu

2001-01-01

51

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

52

Viewing-Zone Control of Large Full-Color LED Display for 3-D and Digital Signage  

Microsoft Academic Search

We propose methods to control viewing zones of large screen consisted of full-color LED panel. Large parallax barriers have been developed for public 3-D display. By changing pixel arrangements, locations and number of perspectives can be reconstructed. Response of viewer's position caused by a shift of viewing was detected to evaluate the design of stereoscopic viewing zone. Furthermore, an array

Hirotsugu Yamamoto; Tomoya Kimura; Shinya Matsumoto; Shiro Suyama

2009-01-01

53

Hydroxyl time series and recirculation in turbulent nonpremixed swirling flames  

SciTech Connect

Time-series measurements of OH, as related to accompanying flow structures, are reported using picosecond time-resolved laser-induced fluorescence (PITLIF) and particle-imaging velocimetry (PIV) for turbulent, swirling, nonpremixed methane-air flames. The [OH] data portray a primary reaction zone surrounding the internal recirculation zone, with residual OH in the recirculation zone approaching chemical equilibrium. Modeling of the OH electronic quenching environment, when compared to fluorescence lifetime measurements, offers additional evidence that the reaction zone burns as a partially premixed flame. A time-series analysis affirms the presence of thin flamelet-like regions based on the relation between swirl-induced turbulence and fluctuations of [OH] in the reaction and recirculation zones. The OH integral time-scales are found to correspond qualitatively to local mean velocities. Furthermore, quantitative dependencies can be established with respect to axial position, Reynolds number, and global equivalence ratio. Given these relationships, the OH time-scales, and thus the primary reaction zone, appear to be dominated by convection-driven fluctuations. Surprisingly, the OH time-scales for these nominally swirling flames demonstrate significant similarities to previous PITLIF results in nonpremixed jet flames. (author)

Guttenfelder, Walter A.; Laurendeau, Normand M.; Ji, Jun; King, Galen B.; Gore, Jay P. [School of Mechanical Engineering, Purdue University, West Lafayette, IN 47907-1288 (United States); Renfro, Michael W. [Department of Mechanical Engineering, University of Connecticut, Storrs, CT 06269-3139 (United States)

2006-10-15

54

Exhaust-gas recirculation system  

Microsoft Academic Search

An exhaust-gas recirculation (EGR) system for an internal-combustion engine comprises an EGR valve for controlling the amount of exhaust-gas recirculation installed midway in an EGR passage that establishes communication between the intake and exhaust pipes of the engine, and an exhaust-gas transducer valve for opening and closing by the exhaust pressure of the exhaust gas an atmospheric-releasing orifice formed midway

K. Yamada; C. Niida; T. Takayama

1979-01-01

55

Recirculation of municipal landfill leachate  

E-print Network

aerobic decomposition of the leachate on the surface in addition to the anaer obic decomposition of the leachate within the landfill and the increased efficiency due to recirculation. HETHODS Each of the experimental landfi 1 1 cel is, as constructed... aerobic decomposition of the leachate on the surface in addition to the anaer obic decomposition of the leachate within the landfill and the increased efficiency due to recirculation. HETHODS Each of the experimental landfi 1 1 cel is, as constructed...

Pinkowski, Brian Jude

2012-06-07

56

Automated, reproducible delineation of zones at risk from inundation by large volcanic debris flows  

USGS Publications Warehouse

Large debris flows can pose hazards to people and property downstream from volcanoes. We have developed a rapid, reproducible, objective, and inexpensive method to delineate distal debris-flow hazard zones. Our method employs the results of scaling and statistical analyses of the geometry of volcanic debris flows (lahars) to predict inundated valley cross-sectional areas (A) and planimetric areas (B) as functions of lahar volume. We use a range of specified lahar volumes to evaluate A and B. In a Geographic Information System (GIS) we employ the resulting range of predicted A and B to delineate gradations in inundation hazard, which is highest near the volcano and along valley thalwegs and diminishes as distances from the volcano and elevations above valley floors increase. Comparison of our computer-generated hazard maps with those constructed using traditional, field-based methods indicates that our method can provide an accurate means of delineating lahar hazard zones.

Schilling, Steve, P.; Iverson, Richard, M.

1997-01-01

57

Nitrate distribution and isotopic composition in vadose-zone sediments underlying large dairy operations  

NASA Astrophysics Data System (ADS)

Understanding the transport and cycling of nitrate in the vadose zone is essential to 1) linking agronomic models of nitrate flux out of the root zone to groundwater models of nitrate loading at the water table, 2) quantifying the impact of vadose-zone biogeochemical processes on nitrate isotopic composition for the purpose of source attribution, and 3) constraining transport time scales through the vadose zone in order to assess the impact of changes in agricultural nutrient management on underlying groundwater quality. In this study, we have investigated the isotopic composition of water-leachable nitrate extracted from sediment cores underlying three dairy operations in the southern San Joaquin Valley of California. One of the dairy operations is new (less than ten years old) and is sited on former range land; the other two operations are older (with one having been continuously operated for over a century). All use dairy wastewater for irrigation, and have vadose zones of 25-60 meters thickness developed in sedimentary sequences dominated by alluvial fan deposits. Sediment core samples from a UC-Davis monitor well drilling program were extracted with an equal amount of ultrapure water, and analyzed for nitrate isotopic composition using the denitrifying bacteria method at LLNL. The range in nitrate isotopic composition (?15N,air = 4.8 to 26.6 permil, ?18O,VSMOW = -0.3 to 16.2 permil) is large, comparable to isotopic compositions observed in dairy wastewater-impacted groundwaters (Singleton et al., 2007, ES&T 41:759-765), and varies from site to site. The range is the largest on the oldest operation (?15N = 5.2 to 26.6), and most tightly clustered on the youngest operation (?15N = 4.8 to 7.8). Leachable nitrate-?18O correlates with nitrate-?15N along a characteristic denitrification trend for individual cores. Leachable nitrate-?15N is not simply correlated with leachable nitrate concentration (which is generally high in shallow sediments and decreases with depth). In one core, the most enriched isotopic compositions are associated with the highest leachate nitrate concentrations. Observed nitrate isotopic compositions are consistent with nitrification of ammonium and mineralized organic N compounds from manure-rich wastewater, followed at some locations by denitrification. Sediment core patterns indicate that these processes can occur in the deep vadose zone. Profiles of leachable nitrate concentration and isotopic composition also differ significantly with respect to the duration of overlying dairy operations on a decadal timescale.

Esser, B. K.; Singleton, M. J.; Moran, J. E.; Roberts, S. K.; Barton, C. G.; Watanabe, N.; Harter, T.

2009-12-01

58

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

59

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

60

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

Code of Federal Regulations, 2011 CFR

...and upriver through Lewiston, ID on the Snake River. (d) Compliance. The...vessel must stay moored or anchored while it remains with in the large passenger vessel's security and safety zone unless it is either ordered by, or given...

2011-07-01

61

Review article Disinfestation of recirculating nutrient solutions  

E-print Network

Review article Disinfestation of recirculating nutrient solutions in greenhouse horticulture David suppression, but few products are commercially available. recirculation / disinfestation / hydroponics The majority of greenhouse crops are grown using artificial substrates in hydroponic systems. These sub

Boyer, Edmond

62

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

63

Integrated dynamic aquaculture and wastewater treatment modelling for recirculating aquaculture systems  

Microsoft Academic Search

Recirculating aquaculture systems (RAS) in land based fish tanks, where the fish tank effluent is biologically treated and then recirculated back to the fish tanks, offers a possibility for large scale ecologically sustainable fish production. In order to fully exploit the advantages of RAS, however, the water exchange should be as small as possible. This implies strong demands on the

Torsten E. I. Wik; Björn T. Lindén; Per I. Wramner

2009-01-01

64

Integrated Dynamic Aquaculture and Wastewater Treatment Modelling for Recirculating Aquaculture Systems  

Microsoft Academic Search

Recirculating aquaculture systems (RAS) in land based sh tanks, where the sh tank euen t is biologically treated and then recirculated back to the sh tanks, of- fers a possibility for large scale ecologically sustainable sh production. In order to fully exploit the advantages of RAS, however, the water exchange should be as small as possible. This implies strong demands

Torsten E. I. Wika; Bjorn T. Lind

65

Exhaust gas recirculation control system  

Microsoft Academic Search

An EGR control valve is closably disposed in an EGR passageway connecting an intake passageway and an exhaust gas passageway which leads to an internal combustion engine. The EGR control valve is operated to control recirculated exhaust gas flow by varying the exhaust gas pressure in a chamber between a restriction disposed in the EGR passageway and the EGR valve,

Aoyama

1979-01-01

66

Exhaust gas recirculation (EGR) system  

Microsoft Academic Search

This invention relates to electronically controlled exhaust gas recirculation valves and more particularly to systems incorporating an electrical vacuum regulator. It is therefore an object of the present invention to provide an EGR system that is less susceptible to output flow changes caused by carbon build up. A further object of the invention is to provide a vacuum regulator that

Cook

1984-01-01

67

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

68

Exhaust gas recirculation control system  

Microsoft Academic Search

An exhaust gas recirculation (EGR) control valve is described. The valve is provided with an extension which is inserted into a restriction, formed in the EGR passageway upstream of the EGR control valve, to reduce the effective cross sectional area of the restriction and therefore the EGR ratio when the pressure in the EGR passageway between the restriction and the

Aoyama

1978-01-01

69

Exhaust gas recirculation control system  

Microsoft Academic Search

An EGR control valve is closely disposed in an EGR passageway connecting an intake passageway and an exhaust gas passageway which leads to an internal combustion engine. The EGR control valve is operated to control recirculated exhaust gas flow by varying the exhaust gas pressure in a chamber between a restriction disposed in the EGR passageway and the EGR valve,

Aoyama

1978-01-01

70

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

71

Exhaust gas recirculation flow control system  

Microsoft Academic Search

A closed-loop exhaust gas recirculation flow control system for minimizing nitrogen oxide emissions from internal combustion engines is described that, unlike prior-art devices, compensates for changes in sensed engine variables by incorporating feedback from the exhaust gas recirculation system. A valve that is responsive to engine air flow and to recirculated exhaust gas flow provides a scheduled flow control signal

Wertheimer

1974-01-01

72

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

73

Exhaust gas recirculation system with engine load dependent performance  

Microsoft Academic Search

An exhaust gas recirculation system is disclosed, which is of the well-known type wherein an exhaust gas recirculation control valve in the exhaust gas recirculation passage controls the amount of exhaust gas recirculation. An orifice element, upstream of the exhaust gas recirculation valve in the passage, defines a pressure chamber between itself and the exhaust gas recirculation control valve. The

Onaka

1981-01-01

74

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

75

Preliminary Study on Emittance Growth in the LHEC Recirculating Linac  

SciTech Connect

In this paper, we estimate the emittance growth in the LHeC recirculating Linac, the lattice design of which is presented in another paper of IPAC10 proceedings. The possible sources for emittance growth included here are: energy spread from RF acceleration in the SRF (superconducting RF) linac together with large chromatic effects from the lattice, and synchrotron radiation (SR) fluctuations in the recirculating arcs. 6-D multi-particle tracking is launched to calculate the emittance from the statistical point of view. The simulation results are also compared with a theoretical estimation.

Sun, Yi-Peng; Adolphsen, Chris; /SLAC; Zimmermann, Frank; /CERN

2011-05-20

76

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

77

Determining the extent and characteristics of overrepresentation of large truck crashes in daytime and nighttime work zones  

E-print Network

DETERMINING THE EXTENT AND CHARACTERISTICS OF OVERREPRESENTATION OF LARGE TRUCK CRASHES IN DAYTIME AND NIGHTTIME WORK ZONES A Thesis by NAVEEN MOKKAPATI Submitted to the Office of Graduate Studies of Texas A&M University in partial... ZONES A Thesis by NAVEEN MOKKAPATI 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 Approved by: Chair of Committee, Gene H...

Mokkapati, Naveen

2008-10-10

78

The dynamic response of geomagnetic sudden commencement to tectonic zone and large earthquakes in China  

NASA Astrophysics Data System (ADS)

Based on the skin effect of EM waves, geomagnetic storm variations can be used to study the subsurface tectonic structure and faulting to have information of penetration view of the earth’s interior. We collected geomagnetic storm report data for 8 years 2000-2007 from 35 geomagnetic stations in China and calculated the amplitude of the vertical component of geomagnetic storm sudden commencement (?Zssc) to study the correlations between ?Zssc and the occurrence of Ms=6.0-8.1 earthquakes in China and its vicinity (70-140°E, 15-55°N) in the period of Year 2000 to 2008. We found that there were significant correlations between the spatial distribution of amplitude changes of ?Zssc, fault activity and occurrence of large earthquakes. Our study provides a method to monitor possibility of medium-to-short term (0.5-12 months) earthquake. There are 5 ?Zssc zero isoporic lines delineating 5 areas normally distributed in China where we called Zero Isoporic Zone (ZIZ) as following, and apparently they coincide with several tectonic zones and seismic gaps from the past 60 years. 1.?Zssc zero isoporic line in eastern China, extending along the rivers of Heilongjiang and Yalu - Eastern Coastal Area - Taiwan Strait - the South China Sea. 2. ZIZ in Luliang Mountain area, where is east to the Great Bend of the Yellow River; 3. ZIZ in Wuling Mountain area is in south of Yangtze River; 4. ZIZ in Longmenshan Fault Zone in central China. This is one area to note in particular. 5. ZIZ in Middle and South Yunnan region. Longmenshan fault zone located at the geographic center of China, where is a seismic sensitive band to correspond to great earthquakes of around Ms8.0. On May 12, 2008, Wenchuan Earthquake of Ms 8.0 occurred in this area. We noticed that, over the period of January 2000 to May 2008, in 5 great earthquakes of Ms=7.8-8.1 in China and its vicinity, 2 to 5 months before the earthquakes, the ZIZ in Longmenshan Fault Zone showed the translation and deformation changes. It moved to NNW or NNE, rotated and even turned up sudden disappearance. The ZIZ in middle and south Yunnan was characterized by its disappearance and formation of a new isoporic line in western area of the original ZIZ. When ZIZ changes came about, within 0.5-12 months, there were 9 middle-strong earthquakes took place, which made up 64% in total 14 earthquakes that we studied in this area. An exceptional case, which had 3 earthquakes of Ms=6.2,6.4,6.6 in a row, occurred in compactly surrounding regions to ZIZ in Yunnan. In eastern China, ?Zssc zero isoporic line behaved changes of bending,tearing,elongation. It also formed a new ZIZ to connect with other 4 ZIZs. That indicated a great earthquake would occur within next 12 months. The ZIZ change in Wuling Mountain area was in the form of its disappearance, enlargement, connecting to eastern ZIZ or ?Zssc zero isoporic line. They foreshadowed the other 9 earthquakes as well. They are one of the biggest earthquakes in Wuling local history; earthquakes of Ms?6.5 in the East China Sea and Taiwan; earthquakes of Ryukyu Islands of Ms?7.0, and earthquakes in the South China Sea. The corresponding rate is 90%.

Zeng, X.; Zheng, J.; Wang, Z.; Lin, Y.

2009-12-01

79

Numerical Analysis of a Hydrocyclone in a Recirculating Aquaculture System  

Microsoft Academic Search

This study investigated the performance of a vortex hydrocyclone for solid removal in a recirculating aquaculture system. In a fish- breeding industry, effluent water is mainly disposed by gravity sedimentation. Thus, a large settling tank and a lot of water are needed to purify effluent water. However, this typical method does not show consistent efficiency. In case of low efficiency,

Eunpil Kim; Gul Chang; Jung In Yoon

80

Recirculating Heavy Ion Accelerator Experiment  

Microsoft Academic Search

Because of their high efficiency, high repetition rate, and relatively simple target chamber geometry, heavy-ion accelerators are attractive candidates as drivers for inertial fusion power plants. Recirculating induction accelerators have been proposed as potential lower cost alternatives to linear induction machines. The requirement of coordinated and accelerated bending introduces new challenges. A program to develop a small (2.2m radius) scaled

A. Molvik; J. J. Barnard; M. D. Cable; D. A. Callahan; V. Cianciolo; A. Friedman; D. P. Grote; G. W. Kamin; H. C. Kirbie; B. G. Logan; S. M. Lund; L. A. Nattrass; M. B. Nelson; T. C. Sangster; W. M. Sharp; C. Ward; T. J. Fessenden; D. L. Judd; H. S. Hopkins; A. G. Debeling; D. B. Longinotti

1996-01-01

81

Large mid-Holocene and late Pleistocene earthquakes on the Oquirrh fault zone, Utah  

NASA Astrophysics Data System (ADS)

The Oquirrh fault zone is a range-front normal fault that bounds the east side of Tooele Valley and it has long been recognized as a potential source for large earthquakes that pose a significant hazard to population centers along the Wasatch Front in central Utah. Scarps of the Oquirrh fault zone offset the Provo shoreline of Lake Bonneville and previous studies of scarp morphology suggested that the most recent surface-faulting earthquake occurred between 9000 and 13,500 years ago. Based on a potential rupture length of 12 to 21 km from previous mapping, moment magnitude ( Mw) estimates for this event range from 6.3 to 6.6 In contrast, our results from detailed mapping and trench excavations at two sites indicate that the most-recent event actually occurred between 4300 and 6900 yr B.P. (4800 and 7900 cal B.P.) and net vertical displacements were 2.2 to 2.7 m, much larger than expected considering estimated rupture lengths for this event. Empirical relations between magnitude and displacement yield Mw 7.0 to 7.2. A few, short discontinuous fault scarps as far south as Stockton, Utah have been identified in a recent mapping investigation and our results suggest that they may be part of the Oquirrh fault zone, increasing the total fault length to 32 km. These results emphasize the importance of integrating stratigraphic and geomorphic information in fault investigations for earthquake hazard evaluations. At both the Big Canyon and Pole Canyon sites, trenches exposed faulted Lake Bonneville sediments and thick wedges of fault-scarp derived colluvium associated with the most-recent event. Bulk sediment samples from a faulted debris-flow deposit at the Big Canyon site yield radiocarbon ages of 7650 ± 90 yr B.P. and 6840 ± 100 yr B.P. (all lab errors are ±1 ?). A bulk sediment sample from unfaulted fluvial deposits that bury the fault scarp yield a radiocarbon age estimate of 4340 ± 60 yr B.P. Stratigraphic evidence for a pre-Bonneville lake cycle penultimate earthquake was exposed at the Pole Canyon site, and although displacement is not well constrained, the penultimate event colluvial wedge is comparable in size to the most-recent event wedges. Charcoal from a marsh deposit, which overlies the penultimate event colluvium and was deposited during the Bonneville lake cycle transgression, yields an AMS radiocarbon age of 20,370 ± 120 yr B.P. Multiple charcoal fragments from fluvial deposits faulted during the penultimate event yield an AMS radiocarbon age of 26,200 ± 200 yr B.P. Indirect stratigraphic evidence for an antepenultimate event was also exposed at Pole Canyon. Charcoal from fluvial sediments overlying the eroded free-face for this event yields an AMS age of 33,950 ± 1160 yr B.P., providing a minimum limiting age on the antepenultimate event. Ages for the past two events on the Oquirrh fault zone yield a recurrence interval of 13,300 to 22,100 radiocarbon years and estimated slip rates of 0.1 to 0.2 mm/yr. Temporal clustering of earthquakes on the nearby Wasatch fault zone in the late Holocene does not appear to have influenced activity on the Oquirrh fault zone. However, consistent with findings on the Wasatch fault zone and with some other Quaternary faults within the Bonneville basin, we found evidence for higher rates of activity during interpluvial periods than during the Bonneville lake cycle. If a causal relation between rates of strain release along faults and changes in loads imposed by the lake does exist, it may have implications for fault dips and mechanics. However, our data are only complete for one deep-lake cycle (the past 32,000 radiocarbon years), and whether this pattern persisted during the previous Cutler Dam and Little Valley deep-lake cycles is unknown.

Olig, Susan S.; Lund, William R.; Black, Bill D.

1994-08-01

82

Effect of solar rotation on turbulent transfer of the large-scale magnetic field in the convective zone  

NASA Astrophysics Data System (ADS)

The turbulent transfer of the large-scale magnetic field is investigated in the density-stratified convective zone with due regard for turbulence anisotropy excited by solar rotation. It is found that the transfer directions of poloidal and toroidal components of the magnetic field do not coincide in the rotating convective envelope. The values of different transfer velocity components of the magnetic fields for the Spruit convective zone model are calculated. The possible role of the transport effects in the large-scale field dynamics over a solar cycle is discussed.

Kichatinov, L. L.; Krivodubs'kii, V. N.

1991-12-01

83

Analysis of linear alkylbenzenesulfonates by capillary zone electrophoresis with large-volume sample stacking.  

PubMed

A systematic investigation of optimal conditions for determining the homologues of linear alkylbenzenesulfonates (LAS) by capillary zone electrophoresis (CZE) using the large-volume sample stacking technique was presented. The most effective sample stacking and separation conditions was 20 mM borate buffer with 30% acetonitrile at pH 9.0, and the sample hydrodynamic injection of up to 90 s at 4 p.s.i. (1 p.s.i. = 6,892.86 Pa) (around 711 nl). Under such conditions, approximately a 100-fold enrichment factor was achieved based on peak heights. The reproducibility of migration time and quantitative results of stacking CZE can be improved by using internal standards. Quantitation limits of the homologues of LAS were 0.002-0.01 mg/l under these enrichment conditions. The analysis of real samples of laundry and dishwashing detergents was performed. The established high-performance liquid chromatography method was applied to evaluate the stacking CZE method, and compatible results were obtained. PMID:11594396

Ding, W H; Liu, C H

2001-09-21

84

Experimental investigation of a local recirculation photobioreactor for mass cultures of photosynthetic microorganisms.  

PubMed

The present work deals with the experimental fluid mechanics analysis of a wavy-bottomed cascade photobioreactor, to characterize the extent and period of recirculatory and straight-flowing streams establishing therein as a function of reactor inclination and liquid flow rate. The substream characterization via Feature Tracking (FT) showed that a local recirculation zone establishes in each vane only at inclinations ?6° and that its location changes from the lower (?3°) to the upper part of each vane (6°). A straight-flowing stream flows opposite (above or below) the local recirculation stream. The recirculation time ranges from 0.86 s to 0.23 s, corresponding, respectively, to the minimum flow rate at the minimum inclination and to the maximum flow rate at the maximum inclination where recirculation was observed. The increase of photosynthetic activity, resulting from the entailed "flash effect", was estimated to range between 102 and 113% with respect to equivalent tubular and bubble column photobioreactors. PMID:24447955

Moroni, Monica; Cicci, Agnese; Bravi, Marco

2014-04-01

85

Crystal zoning in a large-volume ignimbrite: constraints on the thermal history of a supervolcano magma system  

Microsoft Academic Search

Chemical zoning of crystals provides an important archive of information that allows for the reconstruction of complex thermal histories and changes in melt composition of the magma reservoir during crystallization. Here we investigate cathodoluminescence (CL) and Ti zonation in quartz crystals extracted from pumices from the Whakamaru and Rangitaiki ignimbrite units (part of the large-volume Whakamaru Group Ignimbrites), New Zealand,

N. E. Matthews; D. M. Pyle; C. J. Wilson

2009-01-01

86

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

E-print Network

The "dead zone" is a large area of decreased dissolved oxygen concentration in bottom waters where the dissolved oxygen falls below 2 mg O2 per liter. Low dissolved oxygen potentially stresses, they are decomposed by the microbial community that concomitantly consumes dissolved oxygen. Stimulation

Kaufman, Glennis A.

87

3D Modeling of Strong Ground Motion in the Pacific Northwest From Large Earthquakes in the Cascadia Subduction Zone  

Microsoft Academic Search

The Cascadia subduction zone in the Pacific Northwest, USA, generates Great (megathrust) earthquakes with a recurrence period of about 500 years, most recently the M~9 event on January 26, 1700. Since no earthquake of such magnitude has occurred in the Pacific Northwest since the deployment of strong ground motion instruments, a large uncertainty is associated with the ground motions expected

K. B. Olsen; A. Geisselmeyer; W. J. Stephenson; P. M. Mai

2007-01-01

88

Possible Morphologic Indicators for the Location of Large Slow Earthquakes in Subduction Zones  

NASA Astrophysics Data System (ADS)

Global observations of convergent margin morphology may identify regions more likely to produce tsunami earthquakes. Earthquake observations and laboratory modeling show that subduction of seafloor relief influences the accretionary prism (AP), interplate coupling and the occurrence of large interplate earthquakes. The amplitude, wavelength, and direction of convergence of seafloor roughness appear to relate to the scale of the disruption of the subduction process. Sandbox models of AP deformation caused by subduction of relatively small seafloor relief causes a displacement of the active decollement into the AP, rather than along its base. If the relief has a "wake" (e.g. seamount), passive entrance of the toe of the AP, in the wake of the descending seafloor relief, down into the subduction channel occurs, leaving an indented toe. More importantly, when seafloor relief is sufficiently deep in the subduction zone, the decollement descends to the base of the AP. However, this new base has been little faulted if at all, as it was carried passively down the subduction channel. Therefore, conditions for normal earthquake rupture may not exist, and a tsunami earthquake may be more likely. The morphology of an indented AP can be easily identified globally in ETOPO-2 bathymetry. As most convergent margins define small circles and to first order, the bathymetry of the inner wall of the trench is nearly smooth, trench inner wall bathymetry should define conic sections. Residual bathymetry would be the difference between a regionally predicted conic section and observed bathymetry. Anomalously deep residual bathymetry successfully identifies the location of the Tonga, Nicaragua, 1963 Kuril Islands, and eastern Java slow earthquakes. Both slow earthquakes in Peru (1960, 1996) occur along non-accreting margin segments presently subducting rough seafloor with sediment filled troughs. The 1968 and 1994 "hybrid" earthquakes off Honshu are anomalous in that their ruptures began updip as slow earthquakes and later became regular earthquakes. Their initial ruptures lie in the source region of the 1896 slow earthquake.

McCann, W. R.

2007-05-01

89

Exhaust gas recirculation system for internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine is comprised of an exhaust gas recirculation passage for recirculating exhaust gases from an exhaust pipe into an intake pipe downstream of a throttle valve, a control valve responsive to a pressure signal for opening or closing said recirculation passage, a pressure chamber defined within the recirculation passage, a negative

T. Kohama; H. Obayashi; T. Ozaki; H. Nohira

1980-01-01

90

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine includes an exhaust gas recirculation passage for communicating an exhaust port with an intake passage through a recirculation flow control valve. The recirculation system according to the invention comprises a timing valve in the recirculation passage adapted to open at specified moments for extracting exhaust gases containing highly concentrated hydrocarbons.

H. Aihara; Y. Matsumoto; Y. Nakagawa; S. Suzuki

1981-01-01

91

Turbulent transfer of the large-scale magnetic field in the rotating convective zone of the sun  

NASA Astrophysics Data System (ADS)

Consideration is given to the problem of the turbulent transfer of the large-scale magnetic field in a density-stratified convective zone, with the turbulence anisotropy excited by the sun's rotation taken into account. The anisotropy parameter (the Coriolis number - reciprocal of the Rossby number) and the transfer velocity components for the Spruit convective zone model are calculated. The transfer directions of the poloidal and toroidal components of the mean magnetic field do not coincide. The possible role of the turbulent transfer effects in the observed redistribution of magnetic fields over a solar cycle is discussed.

Krivodubskij, V. N.

1992-08-01

92

Determining fault zone structure and examining earthquake early warning signals using large datasets of seismograms  

NASA Astrophysics Data System (ADS)

Seismic signals associated with near-fault waveforms are examined to determine fault zone structure and scaling of earthquake properties with event magnitude. The subsurface structure of faults is explored using fault zone head and/or trapped waves, while various signals from the early parts of seismograms are investigated to find out the extent to which they scale with magnitude. Fault zone trapped waves are observed in three arrays of instruments across segments of the San Jacinto fault. Similarly to previous fault zone trapped wave studies, the low velocity damage zones are found to be 100-200m wide and extend to a depth of ˜3-5km. Observation and modeling indicate that the damage zone was asymmetric around the fault trace. A similar sense of damage asymmetry was observed using detailed geological mapping by Dor et al. (2006) nearby on the San Jacinto fault at Anza. Travel time analysis and arrival time inversions of fault zone head waves were used to produce high resolution images of the fault structure of the San Andreas fault south of Hollister. The contrast of P wave velocities across the fault was found to be ˜50% in the shallow section, lowering to 10-20% below 3 km, with the southwest side having faster velocities. Inversions making use of different subsets of stations suggest that a low velocity damage zone also exists in this area and that it is more prominent on the faster velocity side of the fault. The patterns of damage from these studies of fault zone head waves and trapped waves are consistent (Ben-Zion and Shi, 2005) with the theoretical prediction that earthquake ruptures on these fault sections have statistically-preferred propagation directions. The early parts of P waveforms are examined for signals that have previously been proposed to scale with the final event magnitude. Data from Turkey and a deep South African gold mine show that scaling is present in signals related to the maximum displacement amplitude and frequency content. The high sampling rate of the instruments in the gold mine enables the reduction of the time window in which measurements are made to below the estimated rupture duration of the largest events. Using increasingly small time windows has only a minimal effect on the scaling of the signals with event magnitude, implying that the size of earthquakes is affected statistically by some property of the early part of the rupture.

Lewis, Michael Antony

93

Large two-dimensional laboratory experiment with biodegradation of a PCE source zone  

NASA Astrophysics Data System (ADS)

To investigate the effects of bioremediation on DNAPL source zones, we carried out an experiment in a two-dimensional tank filled with sand. A microbial assemblage originating from a contaminated field site was used for inoculation without enrichment. Injection of 250 ml PCE into the tank yielded a residual zone of PCE with a pool at the bottom. After this injection, the tank was continuously flushed with anaerobic water containing sufficient electron donor and various nutrients. Chlorinated ethenes analysis, microbial groups counting, and the visual observation of the colored PCE show that PCE was degraded in the source zone. Bio-enhanced dissolution occurred as cDCE concentrations were measured four times the solubility limit of PCE and because the PCE solubility limit in the source zone increased. Degradation of cDCE to VC and ethene occurred when PCE concentrations were low (<0.1 mM). After one year of experiment, approximately 135 ml of chlorinated ethenes were removed from the tank. PCE left in the tank was 90 ml and was only present in the pool. keywords: 2D tank experiment, PCE-DNAPL, reductive dechlorination, source zone, bio-enhanced dissolution, mobilization.

Langevoort, M.; Hassanizadeh, S.; Kleingeld, P.; Heimovaara, T.; Leijnse, T.

2008-12-01

94

Orifice of exhaust gas recirculation system  

Microsoft Academic Search

In an exhaust gas recirculation system for an internal combustion engine, orifices disposed in a passage for recirculating the exhaust gas is made of a sheet of a bimetal or other material capable of changing from a normal shape to a deformed shape when the heat of the exhaust gas is applied, in order to prevent carbon contained in the

Fukae

1984-01-01

95

Turbocharged engine exhaust gas recirculation system  

Microsoft Academic Search

Improved exhaust gas recirculation systems for turbocharged gas engines that include an exhaust pipe, a turbocharger connected thereto, and a carburetor connected with a source of gas for the engine. The recirculation system includes an air conduit extending from the turbocharger compressor discharge to a venturi, an exhaust gas conduit that extends from a connection with the exhaust pipe between

Stachowicz

1984-01-01

96

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

97

Control system for exhaust gas recirculating valve  

Microsoft Academic Search

An exhaust gas recirculation control system for an internal combustion engine is disclosed in which a pressure operated exhaust gas recirculation (EGR) valve governs the flow of engine exhaust gas into the engine intake. The EGR valve is supplied with operating pressure from the engine intake manifold via a pressure amplifier. The amplifier has a pressure input which tends to

Caldwell

1976-01-01

98

Self-calibrating exhaust gas recirculation system  

Microsoft Academic Search

A motor vehicle combustion engine has an exhaust gas recirculation system in which the flow of recirculated exhaust gas is controlled through an orifice having exhaust back pressure on one side and a control pressure on the other as determined by an EGR valve. A pressure transducer compares the control pressure with a reference pressure provided in part by an

R. J. Haka; D. D. Stoltman

1983-01-01

99

Large-scale metal zoning in a late-Precambrian skarn-type mineralization, Wadi Kid, SE Sinai, Egypt  

NASA Astrophysics Data System (ADS)

A Precambrian skarn-type mineralization is recently discovered in the Wadi Kid area in southeast Sinai, Egypt. Two sulfide ore types define large scale metal zoning; Cu-Zn-Co in calc-silicate rocks and Zn-Pb-As-Ag in metapelites. The sulfides and host rocks underwent amphibolite facies metamorphism (2.1-4.2 kbar and 500-620 °C). Dating by the chemical Th-U-total Pb isochrone method yields an Th-Pb isochrone age of 660 ± 25 Ma for metamorphic monazite from metapelites. Overall structural and textural relationships of silicate and sulfide minerals favor syn-tectonic formation during granitoids emplacement in a continental margin setting. Large-scale metal zoning reflects variable distances from the causative pluton(s). The Wadi Kid area is highly prospective for Cu, Zn, Pb and Ag mineralization.

Helmy, H. M.; Shalaby, I. M.; Abdel Rahman, H. B.

2014-02-01

100

Large-scale modeling of reactive solute transport in fracture zones of granitic bedrocks  

Microsoft Academic Search

Final disposal of high-level radioactive waste in deep repositories located in fractured granite formations is being considered by several countries. The assessment of the safety of such repositories requires using numerical models of groundwater flow, solute transport and chemical processes. These models are being developed from data and knowledge gained from in situ experiments such as the Redox Zone Experiment

Jorge Molinero; Javier Samper

2006-01-01

101

Exhaust gas recirculation (EGR) system  

SciTech Connect

This invention relates to electronically controlled exhaust gas recirculation valves and more particularly to systems incorporating an electrical vacuum regulator. It is therefore an object of the present invention to provide an EGR system that is less susceptible to output flow changes caused by carbon build up. A further object of the invention is to provide a vacuum regulator that can be used with simple, low cost EGR valves. Simple valves can be used by virtue of the closed loop vacuum regulation feature of the present invention since the flow rate/vacuum signal relationship is not important. A further object of the present invention is to provide an EGR flow regulation system which automatically compensates for pressure variations which result in changes in the pressure differential across the EGR valve due to changes in exhaust system pressure and intake manifold pressure. Many other objects and purposes of the invention will be clear from the following detailed description of the drawing.

Cook, J.E.

1984-09-04

102

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

103

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

104

Geochemical Effects of Increased Production on Recirculated Process Water at the Kiirunavaara Iron Mine, Northern Sweden  

Microsoft Academic Search

Understanding process water characteristics and variations is important for ensuring high quality processing of iron ore.\\u000a Large amounts of water are used during refinement, and the water is often recirculated to save energy. Water quality is important\\u000a for processes such as flotation and agglomeration but recirculation of process water and changes in production can alter water\\u000a quality significantly. This study

Magnus Westerstrand; Björn Öhlander

105

The large buried anticline in the Kizil zone of the southern Urals  

Microsoft Academic Search

Research performed by the authors, the data of drilling of deep boreholes, and analysis of geophysical materials have shown\\u000a that the tectonics of the Kizil zone is characterized by development of thrust dislocation and inconsistency of exposed and\\u000a deep structural plans, when structures developed at the surface and those originated at depth differ both in sizes and specific\\u000a features of

V. N. Puchkov; T. T. Kazantseva

2009-01-01

106

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

107

The Generation of Continents through Subduction Zone Processing of Large Igneous Provinces: A Case Study from the Central American Subduction Zone  

NASA Astrophysics Data System (ADS)

Billions of years ago primary mantle magmas evolved to form the continental crust, although no simple magmatic differentiation process explains the progression to average andesitic crustal compositions observed today. A multiple stage process is often invoked, involving subduction and or oceanic plumes, to explain the strong depletion observed in Archean xenoliths and as well as pervasive tonalite-trondhjemite-granodiorite and komatiite protoliths in the greenstone belts in the crust in the cratons. Studying modern day analogues of oceanic plateaus that are currently interacting with subductions zones can provide insights into continental crust formation. Here we use surface waves to image crustal isotropic and radially anisotropic shear velocity structure above the central American subduction system in Nicaragua and Costa Rica, which juxtaposes thickened ocean island plateau crust in Costa Rica with continental/normal oceanic crust in Nicaragua. We find low velocities beneath the active arc regions (3-6% slower than the surrounding region) and up to 6% radially anisotropic structures within the oceanic crust of the Caribbean Large Igneous Province beneath Costa Rica. The low velocities and radial anisotropy suggest the anomalies are due to pervasive deep crustal magma sills. The inferred sill structures correlate spatially with increased silicic outputs in northern Costa Rica, indicating that deep differentiation of primary magmas is more efficient beneath Costa Rica relative to Nicaragua. Subduction zone alteration of large igneous provinces promotes efficient, deep processing of primary basalts to continental crust. This scenario can explain the formation of continental lithosphere and crust, by both providing strongly depleted mantle lithosphere and a means for rapidly generating a silicic crustal composition.

Harmon, N.; Rychert, C.

2013-12-01

108

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

109

Exhaust gas recirculation system for internal combustion engines  

Microsoft Academic Search

In an exhaust gas recirculation system for an internal combustion engine, the flow quantity of exhaust gases recirculated from an exhaust pipe into an induction pipe through a recirculation pipe is controlled in relation to exhaust pressure in the recirculation pipe in accordance with pneumatic pressure defined by a value calculated in a digital computer taking account of negative pressure

T. Ina; H. Kawai; K. Kobashi; T. Kohama; T. Matsui; A. Nishimatsu; H. Nohira

1980-01-01

110

Exhaust gas recirculation system with an auxiliary valve  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine is described that has an exhaust gas recirculation flow control valve provided at a middle position of the exhaust gas recirculation passage, the control valve being operated depending upon comparison between target and actual values of a control parameter with regard to the amount of exhaust gas recirculation. An auxiliary

Tanaka

1980-01-01

111

Exhaust gas recirculation system for internal combustion engines  

Microsoft Academic Search

In an exhaust gas recirculation system for an internal combustion engine, a flow control valve is disposed within a recirculation pipe and operatively connected to a pneumatically operated servomotor to control the flow quantity of exhaust gases through the recirculation pipe, and an orifice is disposed within the recirculation pipe upstream of the valve to form a space between the

T. Inoue; K. Kobashi; T. Kohama; T. Matsui; A. Nishimatsu; K. Oishi

1981-01-01

112

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system is described for an internal combustion engine of the back pressure control type wherein a back pressure chamber formed in a recirculation passage for recirculating exhaust gases is controlled to be substantially at atmospheric pressure by co-operation of a vacuum-operated diaphragm type exhaust gas recirculation control valve and a vacuum control valve which modifies the

N. Nakamura; N. Toyama; T. Baika

1979-01-01

113

Exhaust gas recirculation system for internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system is disclosed for an internal combustion engine. The recirculating system is of the type including an exhaust gas recirculation passage for communicating an exhaust tube with an intake tube downstream of a throttle valve disposed therein for recirculating part of exhaust gases from the exhaust tube into the intake tube, and a control valve for

T. Kohama; H. Nohira; H. Obayashi; T. Ozaki

1980-01-01

114

Three-step exhaust gas recirculation control system  

Microsoft Academic Search

An exhaust gas recirculation control system is disclosed for particular application to a diesel engine. The system has an exhaust gas recirculation control valve, and a means for actuating the exhaust gas recirculation control valve, which positions the exhaust gas recirculation control valve selectively and steppedly at one of three states, that are: a first state in which it provides

1981-01-01

115

Exhaust gas recirculation system for internal combustion engines  

Microsoft Academic Search

An engine exhaust gas recirculation system includes a recirculation gas control valve provided in a gas recirculation passage. The gas recirculation passage is further provided with a restriction and pressure sensors for detecting the pressure drop across the restriction so that the opening of the control valve be adjusted in accordance with the engine operating conditions and with a prestored

1983-01-01

116

A model for large-scale plastic yield of the Gorda deformation zone  

SciTech Connect

A solution satisfying both continuity and force balance for an elastoplastic Gorda plate in planar coordinates is presented. Continuity on a plane is used to approximate continuity on a spherical surface due to the small area under consideration. The zone of plastic yield vs the seismicity does not change much with fault strength along the Mendocino. Due to the nature of the deformation, the direction of maximum shear stress near the Mendocino triple junction is between 40 and 50 deg to the Mendocino transform in both cases, but curves sharply in the neighborhood of the transform if the fault is strong. It is concluded that the strength of the Mendocino relative to the lithosphere varied over time. Five million years ago a change in pole position increased convergence of the Blanco fracture zone and Mendocino transform, exponentially increasing brittle shear stresses across the fault. Between 2.47 Ma and 1.8 Ma the convergence stabilized, and the resistance to sliding along the transform decayed back to residual levels. The relative slip along the fault during this time was about 1 km. As a result of this history, previous models either for flexural-slip or for right-lateral shear will fit the deformation at different times. 35 refs.

Denlinger, R.P. (Hawaii Volcano Observatory, Hawaii Volcanoes National Park (United States))

1992-10-01

117

Evidence for large prehistoric earthquakes in the northern New Madrid Seismic Zone, central United States  

USGS Publications Warehouse

We surveyed the area north of New Madris, Missouri, for prehistoric liquefaction deposits and uncovered two new sites with evidence of pre-1811 earthquakes. At one site, located about 20 km northeast of New Madrid, Missouri, radiocarbon dating indicates that an upper sand blow was probably deposited after A.D. 1510 and a lower sand blow was deposited prior to A.D. 1040. A sand blow at another site about 45 km northeast of New Madrid, Missouri, is dated as likely being deposited between A.D.55 and A.D. 1620 and represents the northernmost recognized expression of prehistoric liquefaction likely related to the New Madrid seismic zone. This study, taken together with other data, supports the occurrence of at least two earthquakes strong enough to indcue liquefaction or faulting before A.D. 1811, and after A.D. 400. One earthquake probably occurred around AD 900 and a second earthquake occurred around A.D. 1350. The data are not yet sufficient to estimate the magnitudes of the causative earthquakes for these liquefaction deposits although we conclude that all of the earthquakes are at least moment magnitude M ~6.8, the size of the 1895 Charleston, Missouri, earthquake. A more rigorous estimate of the number and sizes of prehistoric earthquakes in the New Madrid sesmic zone awaits evaluation of additional sites.

Li, Y.; Schweig, E.S.; Tuttle, M.P.; Ellis, M.A.

1998-01-01

118

Exhaust gas recirculation valve malfunction indicator apparatus  

Microsoft Academic Search

An internal combustion engine is provided with an exhaust gas recirculating (EGR) system containing a vacuum\\/electric switch assembly activated in response to a non-movement type malfunction of the EGR valve to energize a warning light.

1977-01-01

119

Exhaust gas recirculation control system  

SciTech Connect

A system is described for controlling exhaust gas recirculation (EGR) in an internal combustion engine: (a) base means defining an exhaust gas inlet port, an exhaust gas outlet port and an EGR passage communicating the inlet port with the outlet port, the base means adapted for attachment to an exhaust passage and a combustion chamber inlet passage of an engine; (b) flow valve means disposed in the passage and including a valve seat and poppet member operable upon movement with respect to the seat for controlling EGR flow between the inlet and the outlet; (c) actuator means operable upon receipt of an electrical control signal to move the poppet, the actuator means including: (i) a stepper motor, (ii) an axial lead means operatively rotated by the stepper motor, (iii) follower means guided for axial movement, and operably connected to move the poppet in response to rotation of the lead means; (d) plate means disposed in the EGR passage between the seat and the outlet port and defining a flow measuring orifice; (e) pressure tap means operative to sense the pressure in the passage on the upstream and downstream sides of the orifice; (f) transducer means operative in response to the pressure in the pressure tap means to provide the electrical control signal for the stepper motor.

Egle, L.E.

1987-09-01

120

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

E-print Network

Global Omori law decay of triggered earthquakes: Large aftershocks outside the classical aftershock November 2001; accepted 14 November 2001; published 25 September 2002. [1] Triggered earthquakes can be large, damaging, and lethal as evidenced by the1999 shocks in Turkey and the 2001 earthquakes in El

121

Towards measuring large-scale hydraulic properties of the seismogenic Gole Larghe Fault Zone at 8 km depth  

NASA Astrophysics Data System (ADS)

Fluid flow along fault zones is a major issue in structural geology and seismology. The permeability of fault rocks can be measured in laboratory experiments (e.g. Mitchell et al., this meeting) but its upscaling to large scale structures is not an easy task. On the other hand, in-situ measurements of permeability have been carried out just at relatively shallow depths, only exceptionally up to 3 km for active tectonic settings (e.g. SAFOD), whilst deeper experiments have been performed only in the stable continental crust (e.g. KTB). In this contribution we combine field and microstructural observations, fracture network modelling techniques borrowed from the oil industry, and geochemistry, in order to characterize the (possibly transient) hydraulic structure of the Gole Larghe Fault Zone (GLFZ, Italian Southern Alps), exhumed from ca. 8 km where it was characterized by a well-documented seismic activity. Our strategy consists of: (1) quantitative field characterization of the large- and meso-scale fault and fracture network of the GLFZ, combining DGPS scanlines and image analysis; (2) evaluation of the aperture of fractures based on microstructural and mechanical considerations; (3) reconstruction of realistic Discrete Fracture Network (DFN) 3D models; (4) output in terms of upscaled hydraulic parameters; (5) calibration based on the observed large scale fluid-rock interaction pattern. In this contribution we present the first results of this study performed on the GLFZ, which reveals a composite, heterogeneous, and highly anisotropic hydraulic structure.

Bistacchi, Andrea; Mittempergher, Silvia; Smith, Steve; Di Toro, Giulio; Mitchell, Tom; Nielsen, Stefan

2013-04-01

122

Deformations Associated With Large Interplate Earthquakes Along the Sumatra-Andaman Subduction Zone  

NASA Astrophysics Data System (ADS)

Since the occurrence of the 2004 Sumatra-Andaman earthquake (Mw9.2), the Sumatra-Andaman Subduction zone has attracted geophysicists' attention. We have been carrying on CGPS observation in Thailand and Myanmar to detect postseismic deformation following this gigantic event. Since CGPS on land is not enough to clarify the detailed image of postseismic deformation, we also make InSAR analyses in Andaman and Phuket Islands. On September 12, 2007, another Mw8.4 event occurred SW off Sumatra. We report deformations observed with GPS and SAR including co- and postseismic deformation following this event. We have analyzed CGPS data up to the end of 2007 and detected postseismic displacements all over the Indochina peninsula. Phuket, which suffered from about 26cm coseismic displacement, has shifted by 26cm southwestward till July, 2007. Postseismic transient is clearly recognized and already exceeds coseismic movements at remote sites such as Bangkok and Chiang Mai in Thailand. We processed ALOS/PALSAR data in Andaman and Phuket islands. No remarkable deformation is found in Andaman and Phuket Islands, since the operation period of ALOS/PALSAR is not long enough and the wavelength of postseismic deformation may be much longer than the swath. We try to synthesize the postseismic displacement using a 3-D viscoelastic FEM model. Its results imply that viscoelastic relaxation in mantle with a typical mantle viscosity may play an important role for the observed postseismic transients except during the first six month. An extremely low viscosity is not required beneath the Andaman Sea, though this back arc is now actively opening. Coseismic motion following the 2007 Sumatra event is detected north of Benkgulu on the coast of southern Sumatra with InSAR. The largest LOS displacement of about 35cm is observed 100km NW of Bengkulu. Coseismic westward displacements of 3.5cm from the 2007 Sumatra event are also observed at Singapore, whose epicentral distance is about 700km, with CGPS. The observed fringe can be simulated by a plane fault model gently dipping northeastward with a 10m slip. On the other hand, the maximum of postseismic LOS displacement is shifted about 50km south from the coseismic maximum and significant fringes are more localized than the coseismic ones. The shift and localization of fringe are difficult to understand with an afterslip on deeper extension of coseismic fault plane. There is a slight disturbance in fringes along the Sumatran fault in the coseismic image, although it might be a topographic error. We will continue monitoring crustal deformations in the Sumatra-Andaman subduction zone with GPS and InSAR in order to reveal stress transfer.

Hashimoto, M.; Fukushima, Y.; Katagi, T.; Hashizume, M.; Satomura, M.; Wu, P.; Kato, T.

2008-12-01

123

Experimental characterization of the initial zone of an annular jet with a very large diameter ratio  

NASA Astrophysics Data System (ADS)

This article presents an experimental investigation of a large diameter ratio annular air jet by particle image velocimetry, Laser Doppler Anemometry, hot-wire anemometry and time-resolved tomography. Annular jets consist of a round nozzle with an obstacle placed in its center. These jets are thus defined by an external and an internal diameter corresponding to the round nozzle lips and the diameter of the obstacle, respectively. The ratio between these two diameters defines the behavior of the flow across a characteristic diameter called diameter ratio. In most industrial applications these jets have large diameter ratios, superior to 0.7.

Danlos, Amélie; Lalizel, Gildas; Patte-Rouland, Béatrice

2012-12-01

124

Experimental characterization of the initial zone of an annular jet with a very large diameter ratio  

NASA Astrophysics Data System (ADS)

This article presents an experimental investigation of a large diameter ratio annular air jet by particle image velocimetry, Laser Doppler Anemometry, hot-wire anemometry and time-resolved tomography. Annular jets consist of a round nozzle with an obstacle placed in its center. These jets are thus defined by an external and an internal diameter corresponding to the round nozzle lips and the diameter of the obstacle, respectively. The ratio between these two diameters defines the behavior of the flow across a characteristic diameter called diameter ratio. In most industrial applications these jets have large diameter ratios, superior to 0.7.

Danlos, Amélie; Lalizel, Gildas; Patte-Rouland, Béatrice

2013-01-01

125

Exhaust gas recirculation control system having variable valve lift correcting speed for exhaust gas recirculation valve  

Microsoft Academic Search

An exhaust gas recirculation control system which is adapted to control the valve opening of the exhaust gas recirculation valve so as to minimize the difference between a detected value of the valve opening of the above value and a command value determined as a function of operating conditions of the engine. The valve opening is corrected at a higher

S. Hasegawa; J. Kimura; T. Koumuta; J. Miyake; T. Nakajima

1984-01-01

126

Possible Morphologic Indicators for the Location of Large Slow Earthquakes in Subduction Zones  

Microsoft Academic Search

Global observations of convergent margin morphology may identify regions more likely to produce tsunami earthquakes. Earthquake observations and laboratory modeling show that subduction of seafloor relief influences the accretionary prism (AP), interplate coupling and the occurrence of large interplate earthquakes. The amplitude, wavelength, and direction of convergence of seafloor roughness appear to relate to the scale of the disruption of

W. R. McCann

2007-01-01

127

Tidal Triggering Effect on Earthquake Occurrence Precursory to Large Thrust Earthquakes in Subduction Zones  

Microsoft Academic Search

We observed a clear tidal triggering effect on earthquake occurrence precursory to large thrust earthquakes associated with the subduction of oceanic plates. We measured the correlation between the Earth tide and earthquake occurrence using shallow reverse-fault type earthquakes with Mw >= 5.0 in and around the focal regions of eleven interplate earthquakes with Mw >= 7.5. For each earthquake, we

S. Tanaka; M. Ohtake; H. Sato

2004-01-01

128

Effects of viscosity and bottom friction on recirculating flows  

NASA Astrophysics Data System (ADS)

A recent set of coastal experiments (Pattiaratchi et al., 1987), found that the horizontal eddy Reynolds number did not adequately describe the wakes found in the lee of coastal islands. Other flow parameters formulated on bottom friction were found to be much better at describing these wakes. In this paper it is suggested that these findings are caused by the extraction of energy from the flow due to bottom friction, which is the net result of the vertical viscous transfer of momentum through the water column to the seabed. This is in contrast to the horizontal viscous transfer of momentum which results in negligible energy loss to the coast, because of the far larger horizontal scales. It is hypothesized that this difference results in fundamentally different flow regimes and this hypothesis is investigated both analytically and numerically. Conditions for the existence of steady zones of barotropic recirculation under the influence of both horizontal viscosity and bottom friction in the wake behind a bluff body are examined analytically. It is found that such steady recirculation requires the presence of horizontal viscosity and is hindered by the loss of energy due to bottom friction. A numerical model is used to verify and quantify this analytical result for the case of two-dimensional flow around a circular cylinder, and it is concluded that an appropriate bottom friction number, based on the ratio of scales of the nonlinear and bottom friction terms, may often govern the nature of the recirculation in the lee of coastal islands, instead of the eddy Reynolds number based on horizontal eddy viscosity, as is sometimes assumed.

Denniss, Tom; Middleton, Jason H.

1994-05-01

129

On the nature of large auroral zone electric fields at 1-R/E/ altitude  

NASA Technical Reports Server (NTRS)

Mechanisms that may support magnetic-field-aligned electric fields in collisionless plasma are discussed in the light of recent magnetospheric observations, which for the first time allow a quantitative test of the theoretical models. Data from barium ion releases which indicate large field-aligned potential drops and direct electric field probe measurements at high altitude which reveal electric fields of several hundred millivolts per meter are discussed. It is concluded that the large field strengths observed (1) cannot be explained by anomalous resistivity or thermoelectric effects based on wave-particle interaction, (2) are much larger than required merely to balance the local mirror forces, and (3) are compatible with electric double layers of the same nature as those observed in the laboratory.

Shawhan, S. D.; Falthammar, C.-G.; Block, L. P.

1978-01-01

130

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

131

Large multicellular filamentous bacteria under the oxygen minimum zone of the eastern South Pacific: a forgotten biosphere  

NASA Astrophysics Data System (ADS)

In the soft reduced sediments of the continental shelf, below the oxygen minimum zone (OMZ) of the eastern South Pacific (ESP), peculiar microbial communities have been disclosed which include a variety of large prokaryotes, protists and small metazoans. Dominant among the prokaryotes are large multi-cellular filamentous bacteria which, according to their size range, are roughly divided into megabacteria and macrobacteria. The former group is made up of a few species of Gamma Proteobacteria of the genera Thioploca and Beggiatoa and the second group includes a diversity of phenotypes. Protists include ciliates, flagellates, and foraminifers and the metazoans are mostly nematodes and small polychaetes. A significant similarity has been found in the exploitation of the area/volume relationship among these large bacteria and their fossil analog forms as described from pre-Cambrian rocks. For the same reason, the latter have mostly been referred to as algae or cyanobacteria in the literature. The presence of these seemingly ancient bacteria in the sediments of the oxygen minimum zones of the ESP, one of the most productive but also ecologically most inefficient marine ecosystems of the world, suggests that such setting must have prevailed throughout the geological history of the planet allowing for their survival and further that it might be considered an analog of Proterozoic ocean conditions. These non-cyanobacterial communities offer an alternative hypothesis to students of the evolution of life on Earth and may be of special interest to astrobiologists looking for life or traces of life in terrestrial or extraterrestrial environments since these do not necessarily imply a photosynthesis-based metabolism.

Gallardo, Victor Ariel; Espinoza, Carola

2007-09-01

132

Thermal boundary layers and heat flux in turbulent convection - The role of recirculating flows  

Microsoft Academic Search

The hypothesis that the sealing of the Nusselt number Nu (nondimensional heat flux) with Rayleigh number Ra in turbulent thermal convection is affected by large-scale flows near and within the boundary layers is examined experimentally. The natural flows are enhanced artificially by a moving layer of mercury beneath the convecting fluid. Recirculating large-scale flows are thereby induced near the lower

T. H. Solomon; J. P. Gollub

1991-01-01

133

Large shield volcanos on Venus: The effect of neutral buoyancy zone development on evolution and altitude distribution  

NASA Technical Reports Server (NTRS)

The Magellan mission to Venus has emphasized the importance of volcanism in shaping the surface of the planet. Volcanic plains make up 80 percent of the terrain and hundreds of regions of localized eruptions have been identified. Large volcanos, defined as edifices with diameters greater than 100 km, are the sites of some of the most voluminous eruptions. Head et al. have identified 158 of these structures. Their spatial distribution is neither random nor arranged in linear chains as on the Earth; large volcanos on Venus are concentrated in two large, near-equatorial clusters that are also the site of many other forms of volcanic activity. The set of conditions that must be met on Venus that controls the change from widespread, distributed volcanism to focused, shield-building volcanism is not well understood. Future studies of transitional features will help to address this problem. It is likely, however, that the formation and evolution of a neutral buoyancy zone (NBZ) plays an important role in both determining the style of the volcanism and the development of the volcanic feature once it has begun to erupt. Head and Wilson have suggested that the high surface pressure on Venus may inhibit volatile exsolution, which may influence the density distribution of the upper crust and hence control the nature and location of a NBZ. The extreme variations in pressure with elevation may result in significantly different characteristics of such a NBZ at different locations on the planet. In order to test these ideas regarding the importance of NBZ development in the evolution of a large shield and to determine the style of volcanism, three large volcanos that occur at different basal elevations were examined and the distribution of large volcanos as a function of altitude was determined.

Keddie, S.; Head, James W., III

1992-01-01

134

Small recirculating filters for nitrogen reduction.  

PubMed

Concerned about the negative impacts of nitrogen loading from septic systems on the Chesapeake Bay watershed, Maryland's Anne Arundel County Health Department has pioneered the use of small recirculating sand filters to reduce nitrogen in effluent from residential septic systems. Recirculating sand filters can reduce the total nitrogen in septic-tank effluent by up to 70 percent. Years of experience and the county's participation in the National Onsite Demonstration Project have led to modifications that make the filters more acceptable to homeowners. Use of alternative media, changes in flow patterns, and homeowner education have increased acceptance by homeowners. PMID:11544843

Piluk, R J; Byers, B R

2001-09-01

135

Flux-free growth of large superconducting crystal of FeSe by traveling-solvent floating-zone technique  

NASA Astrophysics Data System (ADS)

A flux-free solution to the growth of large and composition homogeneous superconducting FeSe crystal is reported for the first time, which is based on the traveling-solvent floating-zone technique. The size of the crystal samples prepared by this approach is up to 15 × 6 × 2 mm3, being far bigger than previously reported in all dimensions, and the main phase of the crystals is of a single preferred orientation along the tetragonal (101) plane. X-ray diffraction analysis identifies the main phase to be the superconducting tetragonal ?-FeSe. The superconducting transition temperature (TC) is determined to be 9.4 K by AC magnetic susceptibility and electronic transport measurements. A nearly perfect diamagnetic shielding of ?97% is observed, indicating a bulk superconductivity in the crystal sample.

Ma, Mingwei; Yuan, Dongna; Wu, Yue; Zhou, Huaxue; Dong, Xiaoli; Zhou, Fang

2014-12-01

136

Large and rapid melt-induced velocity changes in the ablation zone of the Greenland Ice Sheet.  

PubMed

Continuous Global Positioning System observations reveal rapid and large ice velocity fluctuations in the western ablation zone of the Greenland Ice Sheet. Within days, ice velocity reacts to increased meltwater production and increases by a factor of 4. Such a response is much stronger and much faster than previously reported. Over a longer period of 17 years, annual ice velocities have decreased slightly, which suggests that the englacial hydraulic system adjusts constantly to the variable meltwater input, which results in a more or less constant ice flux over the years. The positive-feedback mechanism between melt rate and ice velocity appears to be a seasonal process that may have only a limited effect on the response of the ice sheet to climate warming over the next decades. PMID:18599784

van de Wal, R S W; Boot, W; van den Broeke, M R; Smeets, C J P P; Reijmer, C H; Donker, J J A; Oerlemans, J

2008-07-01

137

River food web response to large-scale riparian zone manipulations.  

PubMed

Conservation programs often focus on select species, leading to management plans based on the autecology of the focal species, but multiple ecosystem components can be affected both by the environmental factors impacting, and the management targeting, focal species. These broader effects can have indirect impacts on target species through the web of interactions within ecosystems. For example, human activity can strongly alter riparian vegetation, potentially impacting both economically-important salmonids and their associated river food web. In an Olympic Peninsula river, Washington state, USA, replicated large-scale riparian vegetation manipulations implemented with the long-term (>40 yr) goal of improving salmon habitat did not affect water temperature, nutrient limitation or habitat characteristics, but reduced canopy cover, causing reduced energy input via leaf litter, increased incident solar radiation (UV and PAR) and increased algal production compared to controls. In response, benthic algae, most insect taxa, and juvenile salmonids increased in manipulated areas. Stable isotope analysis revealed a predominant contribution of algal-derived energy to salmonid diets in manipulated reaches. The experiment demonstrates that riparian management targeting salmonids strongly affects river food webs via changes in the energy base, illustrates how species-based management strategies can have unanticipated indirect effects on the target species via the associated food web, and supports ecosystem-based management approaches for restoring depleted salmonid stocks. PMID:23284786

Wootton, J Timothy

2012-01-01

138

How much, where and why? On the diversity of large earthquakes across subduction zones, including "silent"ones  

NASA Astrophysics Data System (ADS)

The December 2004 Sumatra earthquake, the largest in 40 years, gives new insights into the largest subduction zone earthquakes. Earlier ideas about where such earthquakes can occur were based on convergence rate and age of the subducting lithosphere, and to some extent, trench sediment thickness, with mega-events occurring only where young plates (preferably bearing large sedimentary loads) subduct fast. We analyze critically an improved dataset reflecting better known convergence rates (for example, Nazca-South America significantly slower than previously assumed), and reassessed earthquake moments (including recently "discovered" events such as the 1700 Juan de Fuca mega-earthquake, and excluding some large trench earthquakes which turn out to be normal faults), with much of the correlation between event size and age/speed vanishing. In addition, we find that the size of the largest trench earthquakes and seismic coupling fractions depend at best weakly on trench sediment thickness. Taking further into account the concept of rupture variability pioneered in Nankai by Ando (1975), and more recently documented in Chile by Cisternas et al. (2005), this suggests that subduction zones perceived as "silent" or rupturing at relatively moderate levels (M.le.8) could occasionally feature much larger events on the mega earthquake scale, a scenario examplified by the Sumatra event, but potentially applicable to the Makran and Tonga systems, and raising questions in environements such as Java, the Lesser Antilles or the Marianas. In apparently silent subduction systems, the recent 2006 Java "tsunami earthquake" also reopens the debate on the regional distribution of these events characterized by extremely slow rupture, and of their supplementary -- or complementary -- role in the subduction process.

Stein, S.; Okal, E. A.

2006-12-01

139

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

140

40 CFR 1065.127 - Exhaust gas recirculation.  

Code of Federal Regulations, 2011 CFR

...CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.127 Exhaust gas recirculation. Use the exhaust gas recirculation (EGR) system installed with the engine or one that represents a typical in-use configuration. This...

2011-07-01

141

40 CFR 1065.127 - Exhaust gas recirculation.  

Code of Federal Regulations, 2010 CFR

...CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.127 Exhaust gas recirculation. Use the exhaust gas recirculation (EGR) system installed with the engine or one that represents a typical in-use configuration. This...

2010-07-01

142

40 CFR 1065.127 - Exhaust gas recirculation.  

Code of Federal Regulations, 2013 CFR

...CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.127 Exhaust gas recirculation. Use the exhaust gas recirculation (EGR) system installed with the engine or one that represents a typical in-use configuration. This...

2013-07-01

143

40 CFR 1065.127 - Exhaust gas recirculation.  

Code of Federal Regulations, 2012 CFR

...CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.127 Exhaust gas recirculation. Use the exhaust gas recirculation (EGR) system installed with the engine or one that represents a typical in-use configuration. This...

2012-07-01

144

Generation and maintenance of recirculations by Gulf Stream instabilities  

E-print Network

This thesis studies the problems of generation and maintenance of recirculations by Gulf Stream instabilities. Observations show that the horizontal structure of the jet and its recirculations suffer significant changes ...

Beliakova, Natalia Yurievna, 1967-

1999-01-01

145

Technology development for recirculating heavy-ion accelerators  

Microsoft Academic Search

Summary  The «recirculator», a recirculating heavy-ion accelerator, has been identified as a promising approach for an inertial-fusion\\u000a driver. System studies have been conducted to evaluate the recirculator on the basis of feasibility and cost. The recirculator\\u000a has been shown to have significant cost advantages over other potential driver schemes, but some of the performance requirements\\u000a exceed the capabilities of present technology.

M. A. Newton; H. C. Kirbie

1993-01-01

146

Exhaust gas recirculation system for diesel engine  

Microsoft Academic Search

An exhaust gas recirculation control system calculates a target EGR ratio value based upon engine operating parameters and maintains the EGR ratio at the target EGR ratio value. Each time the vehicle travels a predetermined distance, the control system calculates an actual EGR ratio value and corrects the target EGR ratio value to reduce a deviation between the target and

K. Masaki; S. Yasuhara

1984-01-01

147

Closed loop exhaust gas recirculation system  

Microsoft Academic Search

A closed loop exhaust gas recirculation system for an internal combustion engine is described that has an intake system, an exhaust manifold, a throttle disposed within the intake system for controlling air flow therein, a conduit coupling the exhaust manifold to the intake system for supplying exhaust gases back to the intake system for controlling the generation and emission of

Toelle

1979-01-01

148

Pressure transducer for exhaust gas recirculation system  

Microsoft Academic Search

A pressure transducer for use in internal combustion engine exhaust gas recirculation systems is disclosed having low inertia moving components for improved response time and a low cost diaphragm mounting arrangement. Upper and lower housing shells define in cooperation with a diaphragm and an upperand lower reaction plates fabricated from light weight plastic, a vacuum chamber, control chamber and a

1983-01-01

149

Variable percentage exhaust gas recirculation valve  

Microsoft Academic Search

An exhaust gas recirculation (EGR) valve for an internal combustion engine is disclosed in which the rate of flow of exhaust gas from the outlet manifold to the inlet manifold of the engine is controlled as a function of engine load and speed.

1978-01-01

150

High speed exhaust gas recirculation valve  

Microsoft Academic Search

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

Rod Fensom; David J. Kidder

2005-01-01

151

Large-Eddy Simulation of Lean Premixed Flames in a Model Swirl Burner  

Microsoft Academic Search

\\u000a Lean premixed flames in an un-confined model swirl burner are studied numerically by means of large eddy simulation. In the\\u000a burner considered, swirling flow and a richer pilot flame are used to stabilize the flame. The paper investigates the occurrence\\u000a of the central recirculation zone (CRZ) and the precessing vortex core (PVC) for two variants of the burner, as well

Ping Wang; Jochen Fröhlich; Ulrich Maas

152

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

153

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

154

Effects of feedstock, airflow rate, and recirculation ratio on performance of composting systems with air recirculation.  

PubMed

The thermodynamics, kinetics, and energy use of composting systems with air recirculation were determined for feedstocks comprising paper mill sludge and biosolids. Results were developed by simulating the composting system using a two-dimensional finite difference numerical model. Incorporated into the simulation model was independent regulation of temperature and oxygen using a closed loop feedback control system with a two-stage fan setting. Results showed that at low airflows and high recirculation ratios, heat removal by the exhaust gas was insufficient to maintain set point temperatures with the result that process temperatures increased and eventually limited the reaction rate. Types of feedstock, magnitude of airflow and recirculation ratio all affected the energy use of the system. Although recirculation leads to high energy use, it can produce high quality compost by having a temperature gradient of less than 2 degrees C across the bed. PMID:15963715

Ekinci, K; Keener, H M; Akbolat, D

2006-05-01

155

Exhaust gas recirculation system for internal combustion engines  

Microsoft Academic Search

An exhaust gas recirculation system for internal combustion engines comprises an exhaust gas recirculating passage for tapping engine exhaust gas from an exhaust pipe and feeding back to an engine intake pipe downstream of a throttle valve disposed therein, a control valve for opening and closing the recirculating passage in response to a pressure signal, and a throttle port formed

T. Kohama; H. Nohira; H. Obayashi; T. Ozaki

1980-01-01

156

Exhaust gas recirculation system for internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine has an exhaust gas recirculation passage, a constant pressure chamber disposed in the exhaust gas recirculation passage, a pressure regulating valve operative in response to the exhaust gas pressure in the constant pressure chamber, a first flow-rate control valve adapted to be actuated by the vacuum regulated by the pressure

Y. Ikuta; M. Matsuo

1981-01-01

157

Internal combustion engine with an exhaust gas recirculation system  

Microsoft Academic Search

Disclosed is an internal combustion engine with an exhaust gas recirculation system. The engine is provided with an exhaust gas recirculation control valve device, a modulator valve device and a vacuum control valve device. The exhaust gas recirculation control valve device communicates an exhaust passage of the engine with an intake passage of the engine and is provided with a

J. Saiki; T. Kumai

1979-01-01

158

Exhaust gas recirculation system for internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine is disclosed that has an exhaust gas recirculation passage, a constant pressure chamber disposed at an intermediate portion of the exhaust gas recirculation passage, a pressure regulating valve operative in response to the exhaust gas pressure in the constant pressure chamber, a first flow-rate control valve actuated by vacuum regulated

Y. Ikuta; M. Matsuo

1981-01-01

159

Exhaust gas recirculation system for internal combustion engine  

Microsoft Academic Search

An internal combustion engine is provided with an exhaust gas recirculating passage for communicating the intake passage and the exhaust passage thereof. The recirculating passage is provided with a valve for controlling the amount of recirculated exhaust gas. A fundamental air-fuel ratio control value for regulating the air-fuel ratio of the intake gas to a predetermined value is corrected by

S. Yoshioka; Y. Nomoto; T. Oda; K. Yokooku

1984-01-01

160

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine of the back pressure control type is described which includes a chamber space which is positioned at a middle portion of an exhaust gas recirculation passage and upstream of an exhaust gas recirculation control valve and downstream of an orifice and which is maintained substantially at atmospheric pressure, wherein the

Yuuki

1980-01-01

161

Exhaust gas recirculation system for internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine for automotive use is disclosed, wherein a diaphragm-operated recirculation rate control valve adapted to control the exhaust gas recirculation rate depending upon the relationship between the pressure of the exhaust gases passed through an orifice and a vacuum developed in the mixture supply system of the engine is used in

T. Yano; H. Yuzawa

1981-01-01

162

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine is disclosed that has an exhaust gas recirculation control valve of the diaphragm type which controls the opening of an exhaust gas recirculation passage and is actuated by intake vacuum of the engine modified by a vacuum control valve which in turn is actuated by the pressure of exhaust gases

Toyama

1980-01-01

163

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 Cooperating. Nick T. Place , Dean Introduction Recirculating aquaculture systems, also known as water reuse in Recirculating Aquaculture Systems: Parts 1, 2 and 3 ­ provides basic information that should assist

Watson, Craig A.

164

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

The disclosed engine exhaust gas recirculation (EGR) system has an EGR passage for recirculating exhaust gases from an exhaust system of an engine back into an intake system thereof downstream of a throttle valve. The EGR passage has a restriction orifice therein and an EGR control valve responsive to a vacuum signal to control the recirculation of exhaust gases through

T. Kohama; H. Obayashi; T. Ozaki; H. Nohira

1979-01-01

165

Large amplification of ground motion at rock sites within a fault zone in Nocera Umbra (central Italy)  

NASA Astrophysics Data System (ADS)

During the two mainshocks of September 26, 1997 inthe Umbria-Marche border a strong-motion accelerographrecorded peak ground accelerations as large as 0.6 g,approximately, in the town of Nocera Umbra, atdistances of 10 to 15 km from the epicentres. Thisvalue is significantly larger than expected on thebasis of the usual regressions with magnitude anddistance. A broad-band amplification up to a factor of10 was consistently estimated in previous papers,using both weak and strong motion data recorded at theaccelerograph site during local moderate earthquakes.To study the cause of this amplification we deployedsix seismologic stations across the tectonic contactbetween the Ceno-Mesozoic limestone and the Mesozoicmarly sandstone where the accelerograph is installed.Seismograms of 21 shallow aftershocks in the magnituderange from 2.2 to 4.0 and a subcrustal Mw = 5.3event are analysed. Regardless of epicentre location,waveforms show a large complexity in an approximately200 m wide band adjacent to the tectonic contact. Thisis interpreted as the effect of trapped waves in thehighly fractured, lower velocity materials within thefault zone.

Marra, F.; Azzara, R.; Bellucci, F.; et al.

166

3D Modeling of Strong Ground Motion in the Pacific Northwest From Large Earthquakes in the Cascadia Subduction Zone  

NASA Astrophysics Data System (ADS)

The Cascadia subduction zone in the Pacific Northwest, USA, generates Great (megathrust) earthquakes with a recurrence period of about 500 years, most recently the M~9 event on January 26, 1700. Since no earthquake of such magnitude has occurred in the Pacific Northwest since the deployment of strong ground motion instruments, a large uncertainty is associated with the ground motions expected from such event. To decrease this uncertainty, we have carried out the first 3D simulations of megathrust earthquakes (Mw8.5 and Mw9.0) rupturing along the Cascadia subduction zone. The simulations were carried out in a recently developed 3D velocity model of the region of dimensions 1050 km by 550 km, discretized into 2 billion 250 m3 cubes with a minimum S-wave velocity of 625 m/s. The model includes the subduction slab, accretionary sediments, local sedimentary basins, and the ocean layer. About 6 minutes of wave propagation for each scenario consumed about 24 Wall-clock hours using a parallel fourth-order finite-difference method with 1600 processors on the San Diego Supercomputer Center Datastar supercomputer. The source descriptions for the Mw9.0 scenarios were designed by mapping the inversion results for the December 26, 2004 M9+ Sumatra-Andaman Islands earthquake (Ji, 2006) onto a 950 km by 150 km large rupture for the Pacific Northwest model. Simulations were carried out for hypocenters located toward the northern and southern ends of the subduction zone. In addition, we simulated two M8.5 events with a source area of 275 km by 150 km located in the northern and central parts of the model area. The sources for the M8.5 events were generated using the pseudo-dynamic model by Guatteri et al. (2004). All sources used spatially-variable slip, rise time and rupture velocity. Three major metropolitan areas are located in the model region, namely Seattle (3 million+ people), Vancouver (2 million+ people), and Portland (2 million+ people), all located above sedimentary basins amplifying the waves incident from the subduction zone. The estimated peak ground velocities (PGVs) for frequencies less than 0.5 Hz vary significantly with the assumed rise time. Using a mean rise of 32 s, as estimated from source inversion of the 2004 M9+ Sumatra-Andeman event (Ji, 2006), PGVs reached 40 cm/s in Seattle and 10 cm/s in Vancouver and Portland. However, if the mean rise time is decreased to about 14 s, as suggested by the empirical regression by Somerville et al. (1999), PGVs are increased by 2-3 times at these locations. For the Mw8.5 events, PGVs would reach about 10 cm/s in Seattle, and about 5 cm/s in Vancouver and Portland. Combined with extended duration of the shaking exceeding 1 minute for the Mw8.5 events and 2 minutes for the Mw9 events, these long-period ground motions may inflict significant damage on the built environment, in particular on the highrises in downtown Seattle. However, the strongest shaking arrives 1-2 minutes after the earthquake nucleates, indicating that an early warning system in place may help mitigate loss of life in case of a megathrust earthquake in the Pacific Northwest. Additional efforts should analyse the simulated displacements on the ocean bottom for tsunami generation potential.

Olsen, K. B.; Geisselmeyer, A.; Stephenson, W. J.; Mai, P. M.

2007-12-01

167

Particle sieve analysis for determining solids removal efficiency of water treatment components in a recirculating aquaculture system  

Microsoft Academic Search

Recirculating aquaculture systems offer potential finfish production units for small-scale entities as well as large-scale operations. However, the water treatment components of such systems require efficient and proper operation to assure successful production. This study evaluated the solids removal ability of three water treatment components in a two-tank recirculating aquaculture system (28m3) utilized for the warmwater production of tilapia. The

Timothy J. Pfeiffer; Andrew Osborn; Megan Davis

2008-01-01

168

Recirculation Bubbles Measured at the Black Rock Forest Site in New York  

NASA Astrophysics Data System (ADS)

In conditions of low or moderate wind speed, large eddy structures - or recirculation bubbles - may form in the atmosphere over complex terrain. Recirculating air can have a significant influence on the exchange of moisture, energy and trace gases between the atmosphere and biosphere. Recirculation bubbles were predicted by an analytical model (Wang and Yi, 2012), and a numerical model (Xu and Yi, 2012). We conducted an experiment using two nearby towers in Black Rock Forest, New York, confirming the predicted phenomenon. Sensors were installed at five different levels on a tower at the top of a forested hill, and at five different levels at the middle of the eastern slope of the same hill. Each tower contained sensors both above and within the canopy measuring wind speed and direction, temperature, carbon dioxide, water vapor, relative humidity, net radiation, ground heat flux and other key parameters. Sensors collected data from 20 April to 9 June, 2013. The energy flux balances at the tops of the hilltop and midslope towers were approximately 75% and 85% of closure, respectively. The formation of recirculation bubbles was observed to be dependent on wind speed and direction, terrain features, temperature gradients and prevailing synoptic conditions. Carbon dioxide, water vapor and temperature profiles show that net ecosystem exchange is influenced by the presence or absence of recirculation. This research was supported by NSF Grants ATM-0930015 and PSC-CUNY ENHC-44-83.

Kutter, E.; Yi, C.; Hendrey, G. R.; Liu, H.; Eaton, T. T.; Ni-Meister, W.

2013-12-01

169

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

170

Multi-Point Interferometric Rayleigh Scattering using Dual-Pass Light Recirculation  

NASA Technical Reports Server (NTRS)

This paper describes for the first time an interferometric Rayleigh scattering system using dual-pass light recirculation (IRS-LR) capable of simultaneously measuring at multiple points two orthogonal components of flow velocity in combustion flows using single shot laser probing. An additional optical path containing the interferometer input mirror, a quarter-wave plate, a polarization dependent beam combiner, and a high reflectivity mirror partially recirculates the light that is rejected by the interferometer. Temporally- and spatially-resolved acquisitions of Rayleigh spectra in a large-scale combustion-heated supersonic axi-symmetric jet were performed to demonstrate the technique. Recirculating of Rayleigh scattered light increases the number of photons analyzed by the system up to a factor of 1.8 compared with previous configurations. This is equivalent to performing measurements with less laser energy or performing measurements with the previous system in gas flows at higher temperatures.

Bivolaru, Daniel; Danehy, Paul M.; Cutler, Andrew D.

2008-01-01

171

Application of a gas recirculation system to industrial acetic fermentation processes  

Microsoft Academic Search

This paper describes a gas recirculation system for the exhaust gases from the aerobic fermenters normally used in acetic fermentation processes. With the application of this procedure, it is possible to operate in a closed system, so preventing the large losses of fermentation yield due to evaporation which occur in open systems. In addition, this system reduces losses of volatile

J. M. Gómez; L. E. Romero; L. Caro; D. Cantero

1994-01-01

172

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

NASA Technical Reports Server (NTRS)

The data acquired during the summer 1984 Marginal Ice Zone Experiment in the Fram Strait-Greenland Sea marginal ice zone, using airborne active and passive microwave sensors and the Nimbus 7 SMMR, were analyzed to compile a sequential description of the mesoscale and large-scale ice morphology variations during the period of June 6 - July 16, 1984. Throughout the experiment, the long ice edge between northwest Svalbard and central Greenland meandered; eddies were repeatedly formed, moved, and disappeared but the ice edge remained within a 100-km-wide zone. The ice pack behind this alternately diffuse and compact edge underwent rapid and pronounced variations in ice concentration over a 200-km-wide zone. The high-resolution ice concentration distributions obtained in the aircraft images agree well with the low-resolution distributions of SMMR images.

Campbell, W. J.; Josberger, E. G.; Gloersen, P.; Johannessen, O. M.; Guest, P. S.

1987-01-01

173

Self-calibrating exhaust gas recirculation system  

SciTech Connect

A motor vehicle combustion engine has an exhaust gas recirculation system in which the flow of recirculated exhaust gas is controlled through an orifice having exhaust back pressure on one side and a control pressure on the other as determined by an EGR valve. A pressure transducer compares the control pressure with a reference pressure provided in part by an electromagnetic force to provide an operating pressure for positioning the EGR valve to obtain a control pressure equal to the reference pressure. At engine idle, the EGR valve is closed and the control pressure is equal to the exhaust back pressure. When this condition exists, the electromagnetic force is varied until the reference pressure is substantially equal to the control pressure, the magnitude of the electromagnetic force being a measure of the control pressure at idle and which comprises a calibration value that is stored for use as a reference for controlling exhaust back pressure during other engine operating conditions.

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

1983-08-09

174

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

175

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

176

Geometric controls on large volume mid-crustal magma chambers and magma evolution zones: A 3-D modeling approach  

NASA Astrophysics Data System (ADS)

The consequences of varying the spatial relations and the geometry of intrusions have not been explored in most numerical simulations of crustal magma chambers. This study uses a 3-D finite difference algorithm to: 1) examine the relationship of intrusion geometry to other common modeling parameters (thermal properties, crustal composition, and ambient temperature) and to explore the effects of intrusion geometry and spacing on a crustal column. Variations in crustal heat capacity, density, and thermal conductivity across the range of measured values for crustal rocks result in decreases in magma chamber solidification time of only one to two times whereas isovolumetric flattening of a spherical magma body into a thin sill results in an order of magnitude decrease in solidification time. Horizontal variations in sill ellipticity and surface roughness features such as stocks similarly alter solidification times by factors of two. For given constant intrusion composition and rate, focusing of basaltic intrusions into stacked sill complexes or discrete magma bodies results in an order of magnitude more unsolidified basalt remaining after 1.5 m.y. than an equal volume of magma distributed as ellipsoidal sills throughout the model space. However, scattered sills generate "hot zones" of significant crustal melting, with up to ~50% partially molten crust. Scattered sills also result in highly immobile magmas with liquid fractions less than 10% on average as opposed up to ~50% in the focused intrusion simulations. In all simulations, localizing the intrusion site into the lower crust or at the Moho results in geothermal gradient increases of less than one degree C per km (above 20 km depth after 1.5 m.y. of intrusion. Only the presence of intrusions in the mid to upper crust causes geothermal gradient increases of five to ten degrees per km). When compared to previously published 1-D simulations of crustal "hot zones," the 3-D simulations are two to three orders of magnitude less efficient at generating partially molten crust and preserving primary magma. The 3-D simulations also show 10s to 100s of degrees less crustal heating than their 1-D counterparts. Simulations using parameters from the literature show how varying geometry can result in large volume upper-crustal magma chambers remaining liquid for several hundred thousand years. The simulations describe how a focused, high magmatic flux ignimbrite dominated volcanic field such as Long Valley or the Southern Rocky Mountains could develop.

Lake, E. T.

2011-12-01

177

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

...Protection, Captain of the Port Columbia River Zone. 165.1318 Section 165.1318...Protection, Captain of the Port Columbia River Zone. (a) Notice of enforcement or...notice by the Captain of the Port Columbia River. Captain of the Port Columbia...

2014-07-01

178

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

179

Investigation of swirler/dilution jet flow split on primary zone flow patterns in a water model can-type combustor  

NASA Astrophysics Data System (ADS)

LDA measurements of the three mean velocity components and the corresponding turbulence intensities have been made to provide qualitative and quantitative information on the flow field in a water model of a can type gas turbine combustion chamber. The combustor geometry comprised a swirl driven primary zone, annulus fed rows of primary and secondary jets and an exit contraction. The effect of variation of the flow split between the swirler and the dilution holes on the flow pattern in the primary zone has been investigated in detail. Flow visualization studies revealed that significant changes occur in this region due to the interaction between the swirling flow and the radially directed primary jets. A large toroidal recirculation was formed and high levels of turbulence energy generated in the core of the combustor at low levels of swirler flow rate. As the swirl level increases the strength of this recirculation was observed to weaken and become less stable. Beyond a critical level, the primary recirculation was pushed off center and the undesirable feature of a forward velocity on the combustor axis in the primary zone was observed. Despite the dramatic changes brought about in the primary zone the flow pattern downstream of the secondary jets was practically the same for all flow splits due to the strong mixing caused by the two rows of jets.

Koutmos, P.; McGuirk, J. J.

1985-03-01

180

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

PubMed

This study evaluates the impact of nitrate injection on a full scale landfill bioreactor through the monitoring of gaseous releases and particularly N(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(2), CH(4) and N(2)O) in the gas extraction network. However, nitrate-enhanced leachate recirculation induced a marked increase of the N(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(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(2)O releases: 8.1 +/- 0.16 mg m(-2) d(-1) (n = 384), 4.2 +/- 0.14 mg m(-2) d(-1) (n = 132) and 1.9 +/- 0.10 mg m(-2) d(-1) (n = 49), during, after raw leachate and nitrate-enhanced leachate recirculation, respectively. No clear correlation between N(2)O gaseous surface releases and recirculation events were evidenced. Estimated N(2)O fluxes remained in the lower range of what is reported in the literature for landfill covers, even after nitrate injection. PMID:19297142

Tallec, G; Bureau, C; Peu, P; Benoist, J C; Lemunier, M; Budka, A; Presse, D; Bouchez, T

2009-07-01

181

Bathymetry-Density Interaction as a Driver for Seawater Recirculation in Submarine Groundwater Discharge  

NASA Astrophysics Data System (ADS)

A new mechanism for shallow saltwater recirculation as a component of submarine groundwater discharge (SGD) in coastal areas is proposed and evaluated. The proposed process occurs as a result of the interaction between bedform topography and buoyancy forces without requiring transient forcing (e.g., tides or waves) or currents over the bedform. Under hydrostatic seawater, the equivalent freshwater head is greatest on the seabed surface at the troughs of the bedform and lowest at the crest. In this mechanism, the inverted salinity (and density) profile in the presence of both a bedform on the seafloor and upward flow of fresher groundwater from depth induces a downward flow of saline porewater under the troughs and upward flow under the adjacent crest of the bedform. The magnitude and occurrence of the mechanism were evaluated and tested using the SEAWAT model. The results indicate that this mechanism could drive seawater recirculation and contribute 20 to 30 percent of local SGD under a range of realistic conditions. Bedform shape, hydraulic conductivity, hydraulic head and salinity at depth in the porous media, aquifer thickness, effective porosity, and hydrodynamic dispersion are among the factors that control the occurrence and magnitude of the recirculation of seawater, though the upward flux of fresher water is a dominant control. The hydraulic head at depth generally decreases with distance offshore as the head dissipates with the upward flow and discharge of the deeper fresher groundwater. Thus, one might anticipate the occurrence of a banded pattern—approximately parallel to the shoreline—of saltwater recirculation due to topographic-density interaction. Close to shore, the underlying head might be so large as to preclude saltwater recirculation, and far offshore fresher groundwater at depth may be absent or the head might be so small as to preclude upwards flow of deeper groundwater, thereby also eliminating the saltwater recirculation due to topographic-density interaction.

Konikow, L. F.; Akhavan, M.; Sawyer, A. H.; Michael, H. A.; Langevin, C. D.

2012-12-01

182

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

183

Trace determination of sulfonylurea herbicides in water and grape samples by capillary zone electrophoresis using large volume sample stacking.  

PubMed

A sensitive and reliable method using capillary zone electrophoresis with UV-diode array detection has been developed and validated for trace determination of residues of sulfonylurea herbicides in environmental water samples and grapes from different origins. The analytes included are triasulfuron, rimsulfuron, flazasulfuron, metsulfuron-methyl, and chlorsulfuron. Optimum separation has been achieved on a 48.5-cm x 50-microm (effective length 40 cm) bubble cell capillary using 90 mM ammonium acetate buffer, pH 4.8, by applying a voltage of 20 kV at 25 degrees C and using p-aminobenzoic acid as the internal standard. In order to increase sensitivity, large volume sample stacking with polarity switching has been applied as on-line preconcentration methodology. For water samples, a solid-phase extraction (SPE) procedure based on the use of Oasis HLB cartridges was applied for off-line preconcentration and cleanup. For grape samples, the SPE procedure was achieved with C(18) sorbent, after extraction of the compounds with MeOH:H(2)O (1:1) by sonication. The limits of detection for the studied compounds were between 0.04 and 0.12 microg/L for water samples and 0.97 and 8.30 microg/kg in the case of grape samples, lower in all cases than the maximum residue limits permitted by the EU for this kind of food. The developed methodology has demonstrated its suitability for the monitoring of these residues in environmental water and grape samples with high sensitivity, precision, and satisfactory recoveries. PMID:20496055

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

2010-07-01

184

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

185

Scales Depencence of Fracture Density and Fabric in the Damage Zone of a Large Displacement Continental Transform Fault  

E-print Network

Characterization of fractures in an arkosic sandstone from the western damage zone of the San Andreas Fault (SAF) at San Andreas Fault Observatory at Depth (SAFOD) was used to better understand the origin of damage and to determine the scale...

Ayyildiz, Muhammed

2012-08-28

186

Determining the extent and characteristics of overrepresentation of large truck crashes in daytime and nighttime work zones  

E-print Network

The growth of vehicle travel in the United States has accelerated wear on the interstate highway system leading to frequent pavement repair and rehabilitation projects. The presence of work zones not only causes traffic congestion and backup...

Mokkapati, Naveen

2009-05-15

187

Exhaust gas recirculation system for an internal combustion engine  

DOEpatents

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

188

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

189

Exhaust-gas-recirculation system for use in diesel engines  

Microsoft Academic Search

An exhaust-gas-recirculation system is disclosed for use in diesel engines, having a valve member adapted to control the flow rate of the exhaust gas recirculated from the exhaust pipe to the intake pipe of the diesel engine. The exhaust-gas-recirculation system has a fly-weight rotatable in synchronization with the engine to produce a centrifugal force, a governor sleeve displaceable in response

K. Matsui; T. Miyazaki; E. Nomura; H. Sami; T. Ueda

1981-01-01

190

FULL-SCALE EXPERIENCES WITH LEACHATE RECIRCULATING LANDFILLS: CASE STUDIES  

Microsoft Academic Search

Leachate recirculation has been shown in lysimeter, pilot-scale and full-scale investigations to reduce the time required for waste stabilization, improve leachate quality, provide the opportunity for leachate volume reduction, and to enhance the rate of gas production. New generation full-scale landfills are implementing recirculation as a leachate management tool with increasing frequency. Leachate recirculation techniques used at full-scale landfills include

Debra R. Reinhart

1996-01-01

191

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

192

Removal of naphthalene from recirculated wash oil  

SciTech Connect

A bleed stream from the recirculating wash oil in a final cooling system for coke oven gas is centrifugally separated into a waste water stream, a sludge stream and a clean, dry oil stream which is substantially free of solids and has a water content less than 0.5% (Wt.). The clean, dry oil stream is heated to less than about 160/sup 0/C., preferably 125/sup 0/-135/sup 0/C, before entering a naphthalene stripper-wash oil still.

Burcaw, K.R.; Watkins, R.E.

1981-09-01

193

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

194

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

195

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

196

The Southern Part of the Southern Volcanic Zone (SSVZ; 42-46S) of the Andes: History of Medium and Large Explosive Holocene Eruptions  

Microsoft Academic Search

Chaitén volcano is one of 13 large volcanic centers, and numerous small cones, comprising the southern part of the Andean Southern Volcanic Zone (SVZ), that results from the subduction of the Nazca plate (at 7.8 cm\\/yr) between the landward extension of the Chiloé FZ at 42S and the Chile Rise - Trench triple junction at 46S. Chaitén is a rhyolite

C. R. Stern; J. A. Naranjo

2008-01-01

197

Control strategies for domestic hot water recirculation systems  

SciTech Connect

The purpose of a domestic hot water (DHW) recirculation system is to decrease the time spent waiting for the water to be delivered at acceptable temperatures when called for and also decrease the subsequent water consumption. The research detailed in this paper considered whether it is necessary to continuously run these recirculation pumps, as is general practice, or whether it is possible to reduce DHW system energy consumption by operating these pumps with some type of control strategy. Three different control strategies were evaluated by employing detailed monitoring. The different operating modes were: (1) base case (continuous operation), (2) shutdown during the overnight period, (3) shutdown during the peak morning and evening periods, and (4) cycling by a return line aquastat set at 110 F (61 C). In order to accomplish the research, six sites each had an aquastat installed onto the DHW return line and a programmable timeclock wired into the pump. The analysis identifies the relative energy use for each of the strategies during four round-robin rounds of two weeks each during the spring, summer, fall, and winter periods. When compared to the base case, (pump running 24 hours per day), Strategy B saves an average of 6%, Strategy C saves 6%, and Strategy D saves 11% of the DHW portion of a building's DHW energy requirements annually. This is significant in that for Strategy D, this translates into a savings of 4% of the building's total annual fuel bill. All of the control strategies evaluated were simple and employed low-cost devices (under $250 installed), which should help in achieving an extremely large implementation rate for the control strategy recommended. Tenant water quality survey questionnaires show that there was always an acceptable level of satisfaction, regardless of system control strategy.

Goldner, F.S.

1999-07-01

198

Exhaust gas recirculation system for a diesel engine  

Microsoft Academic Search

An exhaust gas recirculation system is provided for reducing the content of oxides of nitrogen in the exhaust of a diesel engine. The system is effective in recirculating variable amounts of exhaust gas back through the engine in relation to engine load by being operatively controlled in response to predetermined settings of the engine's fuel supply system.

R. A. Kern; C. L. McClung; J. R. Turner

1977-01-01

199

Exhaust gas recirculation system for internal combustion engine  

Microsoft Academic Search

In an exhaust gas recirculation system for an internal combustion engine having an intake manifold in which a throttle valve is disposed and an exhaust gas conduit provided with a particle trap for accumulatively catching particles entrained by exhaust gas discharged from the engine, a control valve apparatus which is disposed in a recirculation passage and connected to the intake

K. Dozono; Y. Hasegawa

1983-01-01

200

Exhaust gas recirculation system for internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine employs a first control valve in an exhaust gas introduction passageway, a second control valve in an air conduit connecting the engine intake passage to atmosphere, and a regulating valve responsive to differential vacuum intensities for operating vacuum-responsive actuators for the control valves. A recirculation stop valve vents to atmosphere

Y. Abe; O. Gotoh; A. Takagi

1982-01-01

201

Internal combustion engine having exhaust gas recirculation system  

Microsoft Academic Search

An internal combustion engine has an exhaust gas recirculation system including a recirculation valve for controlling the amount of exhaust gas returned to the intake system. The position or opening of the valve is controlled to a desired position in accordance with a memory in a memory device storing desired valve positions under various combinations of the engine load and

K. Iida; K. Okazaki; Y. Yada

1983-01-01

202

Internal combustion engine with an exhaust gas recirculation system  

Microsoft Academic Search

Disclosed is an internal combustion engine with an exhaust gas recirculation system. The engine is provided with a carburetor which includes a primary system and a secondary system. The recirculated exhaust gas is supplied to the intake passage via an exhaust gas supply pipe which is disposed at a position downstream of the carburetor. The top end of the exhaust

Saiki

1980-01-01

203

Control system for use in exhaust gas recirculation system  

Microsoft Academic Search

A control system is described for use in an exhaust gas recirculation system of an internal combustion engine, in which part of exhaust gases is recirculated from an exhaust system to an intake system in an attempt to reduce the amount of harmful components contained in exhaust gases from the engine as well as to prevent lowering of the running

Onaka

1977-01-01

204

Flow control valve for exhaust gas recirculation system  

Microsoft Academic Search

A flow control valve is provided for use in an exhaust gas recirculation system of an internal combustion engine, whereby a constant flow of the recirculating gas may be maintained. The valve comprises a first and second valve chamber separated by a flow orifice, with a valve body for opening and closing of the flow orifice. Exhaust gas entering the

K. Goto; R. Mitsui

1975-01-01

205

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine wherein a fixed restriction, a pressure chamber and a pressure control valve are arranged in the order named in an exhaust gas recirculation passage and the pressure control valve is controlled in such a way that the pressure in the pressure chamber may be maintained equal to the combined pressure

Yorioka

1980-01-01

206

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine of the back pressure control type is described which provides, by a vacuum-operated control valve, a pressure chamber of substantially constant and nearly atmospheric pressure at a middle portion of an exhaust gas recirculation passage, and a thermostatic control means incorporated in a vacuum passage which supplies control vacuum to

T. Taifu; N. Toyama

1980-01-01

207

Exhaust gas recirculation system having electrical control means  

Microsoft Academic Search

Exhaust gas recirculation system including an intake pressure operated control valve for controlling the amount of exhaust gas recirculated to the intake system and a suction pressure adjusting valve of a duty factor solenoid type for determining the suction pressure applied to the control valve. A control circuit is provided for applying an operating signal to the pressure adjusting valve.

1984-01-01

208

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system for reducing nitrogen oxide emissions from automotive internal combustion engines is described in which the rate or amount of exhaust gases recirculated into the intake manifold of the engine is controlled in relation to the operating conditions of the engine. A device for supplying secondary air into the exhaust is also provided. An exhaust gas

Hayashi

1974-01-01

209

Exhaust gas recirculation system for internal combustion engines  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine employs a vacuum actuator for a control valve in the exhaust gas recirculation passageway. A suction conduit to the actuator contains a magnetic valve for venting the suction conduit to atmosphere. The operating means for the magnetic valve includes a vacuum switch responsive to suction pressure in the engine intake

M. Obata; N. Satoh

1982-01-01

210

Principles of Water Recirculation and Filtration in Aquaculture 1  

E-print Network

FA12 Principles of Water Recirculation and Filtration in Aquaculture 1 Michael McGee and Charles water systems are designed to minimize or reduce dependence on water exchange and flushing in fish tanks, and aquaria systems, as well as small scale aquaculture projects. Water is typically recirculated

Watson, Craig A.

211

Populations of heterotrophic bacteria in an experimental recirculating aquaculture system  

Microsoft Academic Search

The aim of this work was to identify the main viable heterotrophic bacteria in a marine fish farm with a recirculating water system and to study their growth dynamics. The experiments were performed with sea bass (Dicentrarchus labrax) in an experimental recirculating water system. The bacteria identified were typical of the marine environment: Pseudomonas, Oceanospirillum, Marinobacter, Paracoccus and Erythrobacter genus

N Leonard; J. P Blancheton; J. P Guiraud

2000-01-01

212

Identification of Bacterial Pathogens in Biofilms of Recirculating Aquaculture Systems  

Microsoft Academic Search

Biofilms are capable of forming on all aquaculture system components, incorporating the various microflora present in the water. Pathogenic bacteria released from the biofilms are potentially capable of causing recurring diseases. Seven recirculating freshwater and two recirculating saltwater facilities were sampled, with eight different types of materials tested. Pathogenic bacteria were identified using standard bacteriological methods and commercial kits. The

Robin K. King; George J. Flick Jr; D. Pierson; Stephen A. Smith; Gregory D. Boardman; Charles W. Coale Jr

2004-01-01

213

Water quality trials in four recirculating aquacultural system configurations  

Microsoft Academic Search

Four circular, 2000-l, fiberglass tanks in four independent, indoor recirculating aquacultural systems were stocked with hybrid striped bass fingerlings (60-g average weight) at similar densities (320 fish\\/tank at the start of the study). The four systems represented four different recirculating system configurations as obtained by the combination of two types of biofilters (trickling and bead) and two types of solids

Sahdev Singh; James Ebeling; Fredrick Wheaton

1999-01-01

214

Exhaust gas recirculation for an internal combustion engine  

Microsoft Academic Search

A back pressure control type EGR system is disclosed wherein a vacuum line for connecting an EGR port with a vacuum operated EGR valve for controlling the amount of the recirculated exhaust gas is selectively opened to an air chamber of a vacuum modulator valve responsive to the pressure of the recirculated exhaust gas. The air chamber is connected, via

H. Onaka; Y. Sato

1980-01-01

215

Exhaust gas recirculation control system for a diesel engine  

Microsoft Academic Search

An exhaust gas recirculation control system is disclosed such that the throttle valve is controlled by two vacuum actuators through three stages of fully-opened, half-opened, and fully closed positions, in addition to the control of the exhaust gas recirculation control valve, in accordance with the engine operating conditions including engine load. The egr valve is fully closed under a heavy

Y. Kimura; M. Shiobara; Y. Yoshiba

1983-01-01

216

Engineering development for a small-scale recirculator experiment  

SciTech Connect

Lawrence Livermore National Laboratory (LLNL) is evaluating the physics and technology of recirculating induction accelerators for heavy-ion inertial-fusion drivers. As part of this evaluation, the authors are building a small-scale recirculator to demonstrate the concept and to use as a test bed for the development of recirculator technologies. System designs have been completed and components are presently being designed and developed for the small-scale recirculator. This paper discusses results of the design and development activities that are presently being conducted to implement the small-scale recirculator experiments. An, overview of the system design is presented along with a discussion of the implications of this design on the mechanical and electrical hardware. The paper focuses primarily on discussions of the development and design of the half-lattice period hardware and the advanced solid-state modulator.

Newton, M.A.; Deadrick, F.J.; Hanks, R.L.; Hawkins, S.A.; Holm, K.A.; Kirbie, H.C.; Karpenko, V.P.; Nattrass, L.A. [Lawrence Livermore National Lab., CA (United States); Longinotti, D.B. [EG and G Energy Measurements, Inc., Pleasanton, CA (United States)

1995-09-04

217

Recirculation of coastal urban air pollution under a synoptic scale thermal trough in Perth, Western Australia  

NASA Astrophysics Data System (ADS)

Air pollutant recirculation is a common feature of coastal cities as a result of the diurnal variation of the land/sea breeze circulation. On the western coast of Australia, a thermally induced synoptic scale trough interacts with this local circulation to enhance the sea breeze flow, allowing pollutant to penetrate further inland. As well a low wind speed zone formed offshore near the trough axis leads to increased ozone concentrations and the rotation of the trough axis during its onshore movement spreads these higher concentrations of air pollutant over a larger area.

Yimin, Ma; Lyons, T. J.

218

Large-scale separation of clavine alkaloids from Ipomoea muricata by pH-zone-refining centrifugal partition chromatography  

Microsoft Academic Search

Centrifugal partition chromatography in the pH-zone-refining mode was successfully applied to the separation of alkaloids, directly from a crude extract of Ipomoea muricata. The experiment was performed with a two-phase solvent system composed of methyl tert-butyl ether (MtBE)–acetonitrile–water (4:1:5, v\\/v) where triethylamine (10mM) was added to the upper organic stationary phase as a retainer and trifluoroacetic acid (10mM) to the

Anupam Maurya; Santosh Kumar Srivastava

2009-01-01

219

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

...Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to...Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to...Location. Within the Lower Mississippi River and Southwest Pass, moving...

2013-07-01

220

Exhaust gas recirculation control system having a function of automatically correcting detected zero opening value of exhaust gas recirculation valve  

Microsoft Academic Search

An exhaust gas recirculation control system is disclosed which is adapted to control the valve opening of the exhaust gas recirculation valve so as to minimize the difference between a detected value of the valve opening of the above valve and a command value read from a memory as a function of operating condition of the engine. The system includes

S. Hasegawa; Y. Otobe; A. Yamato

1983-01-01

221

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

222

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

223

Exhaust gas recirculation for a diesel engine  

SciTech Connect

An exhaust gas recirculation control valve for a diesel engine is described. The valve comprises a valve casing of a rectangular cross-sectional shape disposed in the intake line of the engine. A valve seat connected to an exhaust line of the engine via an egr passageway is formed in a side wall of the rectangular-shaped valve casing. A valve member is arranged in the casing and then rotated about an axis located upstream of the valve seat in such a manner that the valve member is moved between a position wherein valve member closes the valve seat and another position wherein the plate closes the intake passageway. The valve member comprises a base portion of a flat shape and a guide portion which is inserted into the valve seat when the degree of opening of the valve member is small.

Toda, T.; Ueda, T.

1980-12-09

224

Exhaust gas recirculation for a diesel engine  

SciTech Connect

Disclosed herein is an exhaust gas recirculation control valve for a diesel engine. The valve comprises a valve casing, disposed in the intake line of the engine, of a rectangular cross sectional shape. A valve seat connected to an exhaust line of the engine via an egr passageway is formed in a side wall of the rectangular shaped valve casing. A valve member of a plate shape is arranged in the casing and is rotated about an axis located upstream of the valve seat in such a manner that the valve member is moved between a position wherein the plate closes the valve seat and another position wherein the plate closes the intake passageway. The valve device is operated by an actuator means including a vacuum actuator connected to the valve plate and a vacuum generator which transmits a vacuum signal into the actuator in accordance with the load of the engine.

Sami, H.; Ueda, T.

1980-09-16

225

Recirculating Molten Metal Supply System And Method  

DOEpatents

The melter furnace includes a heating chamber (16), a pump chamber (18), a degassing chamber (20), and a filter chamber (22). The pump chamber (18) is located adjacent the heating chamber (16) and houses a molten metal pump (30). The degassing chamber (20) is located adjacent and in fluid communication with the pump chamber (18), and houses a degassing mechanism (36). The filter chamber (22) is located adjacent and in fluid communication with the degassing chamber (20). The filter chamber (22) includes a molten metal filter (38). The melter furnace (12) is used to supply molten metal to an externally located holder furnace (14), which then recirculates molten metal back to the melter furnace (12).

Kinosz, Michael J. (Apollo, PA); Meyer, Thomas N. (Murrysville, PA)

2003-07-01

226

Recirculating Linac Accelerators For Future Muon Facilities  

SciTech Connect

Neutrino Factories (NF) and Muon Colliders (MC) require rapid acceleration of shortlived 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. We discuss the optics and technical requirements for RLA designs, using RF cavities capable of simultaneous acceleration of both m+ and m- species. The design will include the optics for the multi-pass linac and droplet-shaped return arcs.

Yves Roblin, Alex Bogacz, Vasiliy Morozov, Kevin Beard

2012-04-01

227

The Physical, Geochemical and Microbial Conditions and Processes in the Hyporheic Zone of a Large Tidally Influenced River: The Fraser River, British Columbia, Canada  

NASA Astrophysics Data System (ADS)

The objective of this research is to investigate the physical, chemical and biological conditions and processes that occur in the hyporheic zone of the lower Fraser River, British Columbia. The large flows of between 2000 and 10000 cubic meters per second, the 10 15 m deep, 250 m wide channel, the 1 m tidal fluctuations, the localized scour and redeposition of sediments during freshet and the strong geochemical contrast between groundwater and surface water distinguish this investigation from studies on smaller channels and streams and required the development of novel characterization tools and strategies. The geochemistry of water samples collected with a push-in profiler, bulk electrical conductivity (EC) measurements collected with a push-in tool and hydraulic head measurements indicate that groundwater principally discharges into the river approximately 100 m offshore in a 10 m wide band. River water and groundwater mix to a maximum depth of between 0.75 and 1.5 m. While hydraulic heads show strong tidal reversals, bulk EC profiles show only moderate changes during the tidal cycle. It was hypothesized that high iron (10's mg/L of Fe(II)) in reduced groundwater would precipitate from solution as secondary iron-oxide phases in the zone where groundwater mixes with aerobic river water. Sediments were collected with a freeze-shoe corer and depth profiles through the hyporheic zone and into the underlying aquifer were analyzed by selective extractions. The 15-30 mg/g of total extractable iron in both the aquifer and hyporheic zone is relatively high. The lack of noticeable iron accumulation in the hyporheic zone may indicate that iron precipitates on shallow sediments that are subsequently scoured from the river bed during freshet. Microbial DNA from sediments was analyzed using denaturing gradient gel electrophoresis and showed a relatively diverse community structure but an overall low biomass.

Bianchin, M.; Roschinski, T.; Ross, K.; Leslie, S.; William, M.; Beckie, R.

2006-12-01

228

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

229

Large Eddy Simulations of forced ignition of a non-premixed bluff-body methane flame with Conditional Moment Closure  

SciTech Connect

Large Eddy Simulations (LES) of forced ignition of a bluff-body stabilised non-premixed methane flame using the Conditional Moment Closure (CMC) turbulent combustion model have been performed. The aim is to investigate the feasibility of the use of CMC/LES for ignition problems and to examine which, if any, of the characteristics already observed in related experiments could be predicted. A three-dimensional formulation of the CMC equation was used with simple and detailed chemical mechanisms, and sparks with different parameters (location, size) were used. It was found that the correct pattern of flame expansion and overall flame appearance were predicted with reasonable accuracy with both mechanisms, but the detailed mechanism resulted in expansion rates closer to the experiment. Moreover, the distribution of OH was predicted qualitatively accurately, with patches of high and low concentration in the recirculation zone during the ignition transient, consistent with experimental data. The location of the spark relative to the recirculation zone was found to determine the pattern of the flame propagation and the total time for the flame stabilisation. The size was also an important parameter, since it was found that the flame extinguishes when the spark is very small, in agreement with expectations from experiment. The stabilisation mechanism of the flame was dominated by the convection and sub-grid scale diffusion of hot combustion products from the recirculation zone to the cold gases that enter the burner, as revealed by analysis of the CMC equation. (author)

Triantafyllidis, A.; Mastorakos, E. [Hopkinson Laboratory, Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom); Eggels, R.L.G.M. [Rolls Royce Deutschland, Blankenfelde-Mahlow (Germany)

2009-12-15

230

Flow patterns in carotid bifurcation models using pulsed Doppler ultrasound: effect of concentric vs. eccentric stenosis on turbulence and recirculation.  

PubMed

Hemodynamics play a significant role in stroke risk, where thrombus formation may be accelerated in regions of slow or recirculating flow, high shear and increased turbulence. An in vitro investigation was performed with pulsed Doppler ultrasound (DUS) using the complete spectral data to investigate the three-dimensional (3-D) distribution of advanced parameters that may have potential for making a more specific in vivo diagnosis of carotid disease and stroke risk. The effect of stenosis symmetry and the potential of DUS spectral parameters for visualizing regions of recirculation or turbulence were explored. DUS was used to map pulsatile flow in four model geometries representing two different plaque symmetries (eccentricity) and two stenosis severities (mild, severe). Qualitative comparisons were made with flow patterns visualized using digital particle imaging. Color-encoded maps of DUS spectral parameters (mean velocity, spectral-broadening index and turbulence intensity) clearly distinguished regions of slow or recirculating flow and disturbed or turbulent flow. Distinctly different flow patterns resulted from stenoses of equal severity but different eccentricity. Noticeable differences were seen in both the size and location of recirculation zones and in the paths of high-velocity jets. Highly elevated levels of turbulence intensity were seen distal to severe stenosis. Results demonstrated the importance of plaque shape, which is typically not considered in standard diagnosis, in addition to stenosis severity. PMID:20447759

Poepping, Tamie L; Rankin, Richard N; Holdsworth, David W

2010-07-01

231

Design study of a gas turbine combustor with heat recirculation  

NASA Technical Reports Server (NTRS)

A means of avoiding stoichiometric combustion, reducing emissions, and yet providing stable burning for lean mixtures is based on the use of heat recirculation rather than flow recirculation. This paper is concerned with the calculations of the design parameters of a gas turbine combustor with heat exchanger to produce the desired preheat temperature. The combustor inlet temperature, maximum temperature, equivalence ratio and recirculated heat are determined by thermodynamic analysis. The heat transfer analysis then provides the dimensions of the system to produce the predetermined boundary conditions. It is indicated that practical combustor design may be feasible for reactant mixtures as low as equivalence ratio 0.2.

Ganji, A.; Branch, M. C.; Oppenheim, A. K.

1976-01-01

232

Exhaust gas recirculation apparatus for an internal combustion engine  

SciTech Connect

Disclosed herein is an internal combustion engine provided with an exhaust gas recirculation system of so-called back pressure control type. The exhaust gas recirculation system is provided with a vacuum line connecting a so-called EGR port with a vacuum operated flow control valve, and a modulator valve having a control chamber selectively opened to the vacuum line in response to the pressure of recirculated exhaust gas for controlling vacuum signal level of the flow control valve. The control chamber of the modulator is connected to another vacuum signal port located slightly above the EGR port.

Abe, T.; Hasegawa, Y.; Kawai, N.; Ota, I.; Yamamoto, H.; Yamasaki, T.

1980-09-16

233

Dependence of adhesive behavior of neutrophils on local fluid dynamics in a region with recirculating flow.  

PubMed

We have recently described patterns of adhesion of different types of leukocytes downstream of a backward facing step. Here the predicted fluid dynamics in channels incorporating backward facing steps are described, and related to the measured velocities of flowing cells, patterns of attachment and characteristics of rolling adhesion for neutrophils perfused over P-selectin. Deeper (upstream depth 300 microm, downstream depth 600 microm, maximum wall shear stress approximately 0.1 Pa) and shallower (upstream depth 260 microm, downstream depth 450 microm, maximum wall shear stress approximately 0.3 Pa) channels were compared. Computational fluid dynamics (CFD) predicted the presence of vortices downstream of the steps, distances to reattachment of flow, local wall shear stresses and components of velocity parallel and perpendicular to the wall. Measurements of velocities of perfused neutrophils agreed well with predictions, and suggested that adhesion to P-selectin should be possible in the regions of recirculating flow, but not downstream in re-established flow in the high shear channel. When channels were coated with a P-selectin-Fc chimaera, neutrophils were captured from flow and immobilised. Capture showed local maxima around the reattachment points, but was absent elsewhere in the high shear chamber. In the low shear chamber there was depression of adhesion just beyond the reattachment point because of expansion of flow and depletion of neutrophils near the wall. Inside the recirculation zones, adhesion decreased approaching the step because of an increasing, vertically upward velocity component. When channels were coated with P-selectin, neutrophils rolled in all regions, but lifted off the surface as they rolled backwards into low shear regions near the step. Rolling velocity in the recirculation zone was independent of shear stress, possibly because of the effects of vertical lift. We conclude that while local wall shear stress influences adhesive behavior, delivery of cells to the wall and their behavior after capture also depend on components of flow perpendicular to the wall. PMID:11381176

Skilbeck, C; Westwood, S M; Walker, P G; David, T; Nash, G B

2001-01-01

234

Ozonated seawater induces genotoxicity and hematological alterations in turbot ( Scophthalmus maximus) — Implications for management of recirculation aquaculture systems  

Microsoft Academic Search

Ozonation has proven useful in recirculating aquaculture systems promoting the stabilization of water quality and disease control. Nevertheless, its cytogenetic and physiological effects on fish are still largely unknown. Hence, this research investigated the effects of ozone exposure in juvenile turbot (Scophthalmus maximus) by assessing its genotoxic potential (erythrocytic nuclear abnormalities — ENA — assay) and alterations on hematological parameters

J. Silva; A. Laranjeira; R. Serradeiro; M. A. Santos; M. Pacheco

2011-01-01

235

Towards the inclusion of wave-ice interactions in large-scale models for the Marginal Ice Zone  

E-print Network

A wave-ice interaction model for the marginal ice zone (MIZ) is reported, which involves both the attenuation of ocean surface waves by sea ice and the concomitant breaking of the ice by waves. It is specifically designed to embed wave-ice interactions in an operational ice/ocean model for the first time. We investigate different methods of including the wave forcing, and different criteria for determining if they cause floes to break. We also investigate and discuss the effects of using various attenuation models, finding that predicted MIZ widths are quite sensitive to the choice of model. Additional sensitivity tests are performed on: (i) different parameterizations of the floe size distribution (FSD), including the initial FSD used; (ii) the properties of the wave field; and (iii) the sea ice properties such as concentration, thickness and breaking strain. Results are relatively insensitive to FSD parameterization but vary noticeably and systematically with its initial configuration, as they do with prope...

Williams, Timothy; Dumont, Dany; Squire, Vernon; Bertino, Laurent

2012-01-01

236

Large-scale separation of clavine alkaloids from Ipomoea muricata by pH-zone-refining centrifugal partition chromatography.  

PubMed

Centrifugal partition chromatography in the pH-zone-refining mode was successfully applied to the separation of alkaloids, directly from a crude extract of Ipomoea muricata. The experiment was performed with a two-phase solvent system composed of methyl tert-butyl ether (MtBE)-acetonitrile-water (4:1:5, v/v) where triethylamine (10 mM) was added to the upper organic stationary phase as a retainer and trifluoroacetic acid (10 mM) to the aqueous mobile phase as an eluter. From 4 g of crude extract, 210 mg lysergol and 182 mg chanoclavine were obtained in 97% and 79.6% purities. Total yield recovery was >95%. Isolated alkaloids were characterized on the basis of their (1)H, (13)C NMR and ESI-MS data. PMID:19467935

Maurya, Anupam; Srivastava, Santosh Kumar

2009-06-15

237

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

238

A simplified multi-zone model for determining the placement of bio-defense sensors in large buildings  

E-print Network

The anthrax mailings of 2001 increased public and government awareness to the threat of bio-terrorism. Particularly vulnerable to a bio-terrorist event are large indoor facilities such as convention centers, office buildings, ...

Van Broekhoven, Scott B. (Scott Bennett)

2008-01-01

239

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

Federal Register 2010, 2011, 2012, 2013

...Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to...ships as they transit the Lower Mississippi River between the Port of New Orleans...maritime traffic on the Lower Mississippi River. DATES: Comments and...

2012-05-17

240

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

Federal Register 2010, 2011, 2012, 2013

...Large Cruise Ships; Lower Mississippi River, Southwest Pass Sea Buoy to...ships as they transit the Lower Mississippi River between the Port of New Orleans...maritime traffic on the Lower Mississippi River. DATES: This rule is...

2012-10-31

241

Method of detecting a fault of an exhaust gas recirculation system  

Microsoft Academic Search

This patent describes a method of detecting a fault of an exhaust gas recirculation system of an internal combustion engine, wherein a temperature relating to a temperature of the exhaust gas recirculating through the exhaust gas recirculation system is detected when the exhaust gas recirculation system is in a condition in which the system should be operated to return part

T. Hashimoto; A. Takahashi; T. Imaizuma; S. Saito; H. Tanaka; T Jimbo

1989-01-01

242

21 CFR 880.5045 - Medical recirculating air cleaner.  

Code of Federal Regulations, 2010 CFR

21 Food and Drugs 8 2010-04-01...2010-04-01 false Medical recirculating air cleaner...5045 Section 880.5045 Food and Drugs FOOD AND DRUG ADMINISTRATION...SERVICES (CONTINUED) MEDICAL DEVICES GENERAL...

2010-04-01

243

21 CFR 880.5045 - Medical recirculating air cleaner.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 8 2013-04-01...2013-04-01 false Medical recirculating air cleaner...5045 Section 880.5045 Food and Drugs FOOD AND DRUG ADMINISTRATION...SERVICES (CONTINUED) MEDICAL DEVICES GENERAL...

2013-04-01

244

21 CFR 880.5045 - Medical recirculating air cleaner.  

Code of Federal Regulations, 2012 CFR

21 Food and Drugs 8 2012-04-01...2012-04-01 false Medical recirculating air cleaner...5045 Section 880.5045 Food and Drugs FOOD AND DRUG ADMINISTRATION...SERVICES (CONTINUED) MEDICAL DEVICES GENERAL...

2012-04-01

245

21 CFR 880.5045 - Medical recirculating air cleaner.  

21 Food and Drugs 8 2014-04-01...2014-04-01 false Medical recirculating air cleaner...5045 Section 880.5045 Food and Drugs FOOD AND DRUG ADMINISTRATION...SERVICES (CONTINUED) MEDICAL DEVICES GENERAL...

2014-04-01

246

21 CFR 880.5045 - Medical recirculating air cleaner.  

Code of Federal Regulations, 2011 CFR

21 Food and Drugs 8 2011-04-01...2011-04-01 false Medical recirculating air cleaner...5045 Section 880.5045 Food and Drugs FOOD AND DRUG ADMINISTRATION...SERVICES (CONTINUED) MEDICAL DEVICES GENERAL...

2011-04-01

247

Pulsed Magnet Arc Designs for Recirculating Linac Muon Accelerators  

SciTech Connect

Recirculating linear accelerators (RLAs) using both pulsed quadrupoles and pulsed dipoles can be used to quickly accelerate muons in the 3 – 2000 GeV range. Estimates on the requirements for the pulsed quadrupoles and dipoles are presented.

K.B. Beard, R.P. Johnson, S.A. Bogacz, G.M. Wang

2009-05-01

248

A BIOECONOMIC MODEL OF RECIRCULATING SHRIMP PRODUCTION SYSTEMS.  

E-print Network

??To prevent disease outbreaks and increase competitiveness of U.S. shrimp products, U.S. aquaculture researchers have developed super-intensive, bio-secure, recirculating shrimp production systems since the early… (more)

ZHOU, XIA Vivian

2007-01-01

249

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

250

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

251

LONGITUDINAL REFERENCE PARTICLE MOTION IN NEARLY ISOCHRONOUS FFAG RECIRCULATING ACCELERATORS.  

SciTech Connect

A Fixed Field Alternating Gradient (FFAG) arc can be used to reduce the cost of a recirculating accelerator. Path length variation with energy in such an arc can limit its usefulness, however, due to phase offset at the linac. This paper examines the dynamics of the reference particle in an FFAG recirculating accelerator, and describes the limitations on the design because of path length variation with energy.

BERG,J.S.

2001-07-01

252

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.

2014-02-01

253

Visualisation of isothermal large coherent structures in a swirl burner  

SciTech Connect

Lean premixed combustion using swirl flame stabilisation is widespread amongst gas turbine manufacturers. The use of swirl mixing and flame stabilisation is also prevalent in many other non-premixed systems. Problems that emerge include loss of stabilisation as a function of combustor geometry and thermo-acoustic instabilities. Coherent structures and their relationship with combustion processes have been a concern for decades due to their complex nature. This paper thus adopts an experimental approach to characterise large coherent structures in swirl burners under isothermal conditions so as to reveal the effects of swirl in a number of geometries and cold flow patterns that are relevant in combustion. Aided by techniques such as Hot Wire Anemometry, High Speed Photography and Particle Image Velocimetry, the recognition of several structures was achieved in a 100 kW swirl burner model. Several varied, interacting, structures developed in the field as a consequence of the configurations used. New structures never observed before were identified, the results not only showing the existence of very well defined large structures, but also their dependency on geometrical and flow parameters. The PVC is confirmed to be a semi-helical structure, contrary to previous simulations performed on the system. The appearance of secondary recirculation zones and suppression of the vortical core as a consequence of geometrical constrictions are presented as a mechanism of flow control. The asymmetry of the Central Recirculation Zone in cold flows is observed in all the experiments, with its elongation dependent on Re and swirl number used. (author)

Valera-Medina, A.; Syred, N.; Griffiths, A. [School of Engineering, Cardiff University, Queen's Building, The Parade, Cardiff, Wales CF24 3AA (United Kingdom)

2009-09-15

254

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

255

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

USGS Publications Warehouse

The chronology of M>7 paleoearthquakes 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 time of 350 years. Repeat times for individual segments vary by a factor of 2, and range from about 1200 to 2600 years. Four of the central five segments ruptured between ??? 620??30 and 1230??60 calendar years B.P. The remaining segment (Brigham City segment) has not ruptured in the past 2120??100 years. Comparison of the WFZ space-time diagram of paleoearthquakes with synthetic paleoseismic histories indicates that the observed temporal clusters and gaps have about an equal probability (depending on model assumptions) of reflecting random coincidence as opposed to intersegment contagion. Regional seismicity suggests that for exposure times of 50 and 100 years, the probability for an earthquake of M>7 anywhere within the Wasatch Front region, based on a Poisson model, is 0.16 and 0.30, respectively. A fault-specific WFZ model predicts 50 and 100 year probabilities for a M>7 earthquake on the WFZ itself, based on a Poisson model, as 0.13 and 0.25, respectively. In contrast, segment-specific earthquake probabilities that assume quasi-periodic recurrence behavior on the Weber, Provo, and Nephi segments are less (0.01-0.07 in 100 years) than the regional or fault-specific estimates (0.25-0.30 in 100 years), due to the short elapsed times compared to average recurrence intervals on those segments. The Brigham City and Salt Lake City segments, however, have time-dependent probabilities that approach or exceed the regional and fault specific probabilities. For the Salt Lake City segment, these elevated probabilities are due to the elapsed time being approximately equal to the average late Holocene recurrence time. For the Brigham City segment, the elapsed time is significantly longer than the segment-specific late Holocene recurrence time.

McCalpin, J.P.; Nishenko, S.P.

1996-01-01

256

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

257

Evolution of the vertical profile and flux of large sea-salt particles in a coastal zone  

NASA Astrophysics Data System (ADS)

In the vicinity of the North Carolina Outer Banks we observed both steady onshore flow conditions and a continental air mass transition into a marine boundary layer. Using the CIRPAS Twin Otter aircraft, we measured changes in the column burden of sea salt as the air mass was advected out to sea. We also measured the flux of whitecap-generated sea-salt particles in neutrally stable atmosphere at wind speeds of 4, 8, and 12 m s-1. Production of salt particles as small as 0.27 ?m in diameter was observed. Furthermore, we measured salt particle size distributions at various wind speeds during along shore wind and near steady state conditions. Using these measurements as a frame of reference, we discuss the very large differences in the reported size and flux of sea salt presented in the literature. The disagreement in reported salt fluxes is larger for smaller- sized particles (almost an order of magnitude) and is most likely due to assumptions made when the fluxes were computed, especially the particle dry deposition velocity and air mass history. However, for giant salt particles with short atmospheric lifetimes (>˜10 ?m in diameter), there is general agreement between fluxes and size distributions measured in this study and previous ones. Reported salt particle size distributions in the literature also vary considerably under similar steady wind and stability conditions. From these and our results it is clear that no more than half of the variance in salt particle concentration can be explained by wind speed alone, suggesting that the idea of "steady state" in the marine boundary layer rarely exists at midlatitudes.

Reid, Jeffrey S.; Jonsson, Haflidi H.; Smith, Michael H.; Smirnov, Alexander

2001-06-01

258

Acceleration schedules for a recirculating heavy-ion accelerator  

SciTech Connect

Recent advances in solid-state switches have made it feasible to design programmable, high-repetition-rate pulsers for induction accelerators. These switches could lower the cost of recirculating induction accelerators, such as the ''small recirculator'' at Lawrence Livermore National Laboratory (LLNL), by substantially reducing the number of induction modules. Numerical work is reported here to determine what effects the use of fewer pulsers at higher voltage would have on the beam quality of the LLNL small recirculator. Lattices with different numbers of pulsers are examined using the fluid/envelope code CIRCE, and several schedules for acceleration and compression are compared for each configuration. For selected schedules, the phase-space dynamics is also studied using the particle-in-cell code WARP3d.

Sharp, W.M.; Grote, D.P.

2002-05-01

259

Exhaust gas recirculation for an internal combustion engine  

SciTech Connect

A back pressure control type EGR system is disclosed wherein a vacuum line for connecting an EGR port with a vacuum operated EGR valve for controlling the amount of the recirculated exhaust gas is selectively opened to an air chamber of a vacuum modulator valve responsive to the pressure of the recirculated exhaust gas. The air chamber is connected, via a vacuum line, to a second vacuum port located slightly above the EGR port. A vacuum switching valve responsive to vacuum pressure at a third port formed in an intake manifold is arranged in the vacuum line.

Onaka, H.; Sato, Y.

1980-06-10

260

Exhaust gas recirculation control system for a diesel engine  

SciTech Connect

An exhaust gas recirculation control system is disclosed such that the throttle valve is controlled by two vacuum actuators through three stages of fully-opened, half-opened, and fully closed positions, in addition to the control of the exhaust gas recirculation control valve, in accordance with the engine operating conditions including engine load. The egr valve is fully closed under a heavy engine load and fully opened under a medium and light engine load, and the throttle valve is fully opened under a heavy engine load, half opened under a medium engine load, and fully closed under a light engine load, under due consideration of engine speed.

Kimura, Y.; Shiobara, M.; Yoshiba, Y.

1983-06-21

261

Modulation of ATP/ADP concentration at the endothelial surface by shear stress: effect of flow recirculation.  

PubMed

The extracellular presence of the adenine nucleotides ATP and ADP induces calcium mobilization in vascular endothelial cells (ECs). ATP/ADP concentration at the EC surface is determined by a balance of convective-diffusive transport to and from the EC surface, hydrolysis by ectonucleotidases at the cell surface, and flow-induced ATP release from ECs. Our previous numerical simulations in a parallel plate geometry had demonstrated that flow-induced ATP release has a profound effect on nucleotide concentration at the EC surface. In the present study, we have extended the modeling to probe the impact of flow separation and recirculation downstream of a backward facing step (BFS) on ATP/ADP concentration at the EC surface. The results show that for both steady and pulsatile flow over a wide range of wall shear stresses, the ATP+ADP concentration at the EC surface is considerably lower within the flow recirculation region than in areas of undisturbed flow outside the recirculation zone. Pulsatile flow also leads to sharp temporal gradients in nucleotide concentration. If confirmed experimentally, the present findings suggest that disturbed and undisturbed flow may affect EC calcium mobilization differently. Such differences might, in turn, contribute to the observed endothelial dysfunction in regions of disturbed flow. PMID:17253149

Choi, Hyo Won; Ferrara, Katherine W; Barakat, Abdul I

2007-04-01

262

Frequency of Aeromonas spp. detection in rainbow trout and recirculation aquaculture systems and the storage stability of fillets.  

E-print Network

??Recirculating aquaculture systems enable increased fish production per unit volume of water. Unfortunately, recirculation systems also provide conditions for bacterial growth. Aeromonas, a genus of… (more)

Littler, Tabetha Marie.

2007-01-01

263

Exhaust gas recirculation system for automatic transmission vehicle  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine is described which consists of an automatic transmission which has gear ratios and shifts between the gear ratios in accordance with selected shift patterns including an economy pattern in which upshift between successive ones of gear ratios occurs at first corresponding predetermined vehicle speeds and a power pattern in which

Y. Abe; T. Okano; T. Omori; M. Kawamoto

1987-01-01

264

Vacuum regulation valve in an exhaust gas recirculation system  

Microsoft Academic Search

The vacuum regulation valve operable to regulate the vacuum in the vacuum line of an exhaust gas recirculation system, includes a compact construction and a buffer means which is effective to eliminate the clattering sounds inherent in the conventional vacuum regulation valve.

M. Washio; T. Harada

1978-01-01

265

The benefits of flue gas recirculation in waste incineration.  

PubMed

Flue gas recirculation in the incinerator combustion chamber is an operative technique that offers substantial benefits in managing waste incineration. The advantages that can be obtained are both economic and environmental and are determined by the low flow rate of fumes actually emitted if compared to the flue gas released when recirculation is not conducted. Simulations of two incineration processes, with and without flue gas recirculation, have been carried out by using a commercial flowsheeting simulator. The results of the simulations demonstrate that, from an economic point of view, the proposed technique permits a greater level of energy recovery (up to +3%) and, at the same time, lower investment costs as far as the equipment and machinery constituting the air pollution control section of the plant are concerned. At equal treatment system efficiencies, the environmental benefits stem from the decrease in the emission of atmospheric pollutants. Throughout the paper reference is made to the EC legislation in the field of environmental protection, thus ensuring the general validity in the EU of the foundations laid and conclusions drawn henceforth. A numerical example concerning mercury emission quantifies the reported considerations and illustrates that flue gas recirculation reduces emission of this pollutant by 50%. PMID:16516458

Liuzzo, Giuseppe; Verdone, Nicola; Bravi, Marco

2007-01-01

266

Integrated idle air and exhaust gas recirculation system  

Microsoft Academic Search

An integrated idle air and exhaust gas recirculation control system for use on an internal combustion engine. A control valve assembly comprising a base having a central chamber therin and inlet means for the introduction of idle air and exhaust gas to the central chamber and an outlet opening for the supply of the idle air and exhaust gas to

McKay

1991-01-01

267

Exhaust gas recirculation system for a V-type engine  

Microsoft Academic Search

This patent describes an exhaust gas recirculation system for a V-type engine having a pair of cylinder banks arranged at an angle to each other on opposite sides of a crankshaft, each cylinder bank having cylinders therein and an intake passage being separately provided for each cylinder. The improvement described here comprises that the intake passages have respective proximate portions

M. Choushi; H. Ishimi

1986-01-01

268

Exhaust gas recirculation system for internal combustion engine  

Microsoft Academic Search

An impeller is disposed in an exhaust gas recirculation passage communicating between the exhaust passage and the intake passage of the engine. The impeller supplies part of the exhaust gas positively from the exhaust passage to the intake passage of the engine. The blowing device includes a blower which is driven electrically or mechanically.

Ushimura

1983-01-01

269

Exhaust gas recirculation system for an automotive engine  

Microsoft Academic Search

The invention discloses an exhaust gas recirculation system for an automotive engine in which that portion of the exhaust stream is selectively withdrawn which contains the major amount of undesirable ingredients. The portion of gas from each cylinder is received in a common mixing chamber and thereafter passed to the inlet side of the engine for mixing with fresh charge

K. S. Virk; H. E. Leikkanen

1979-01-01

270

Exhaust gas recirculation system for an internal combustion engine  

Microsoft Academic Search

In an internal combustion engine having an intake passage provided therein with a throttle valve for controlling intake flow of air or an air-fuel mixture passing therethrough toward engine cylinders and an exhaust passage, an exhaust gas recirculation system comprises first means for conducting a portion of the exhaust gases from the exhaust passage into the intake passage downstream of

Higashi

1984-01-01

271

Exhaust gas recirculation system of an internal combustion engine  

Microsoft Academic Search

Disclosed is an exhaust gas recirculation system of an internal combustion engine for high altitude use. The system includes a feedback control valve for controlling the amount of exhaust gas fed back to an intake passage, and a compensating device for decreasing a set pressure level of the feedback control valve, above which set level the feedback control valve is

K. Katoh; T. Ogita

1980-01-01

272

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

273

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

274

Pumping effect on particle sizes in a recirculating aquaculture system  

Microsoft Academic Search

Centrifugal pumps are widely used to continuously move water to and from filtration devices in recirculating fish culture systems. The smaller the particle size, particularly below 60–100 ?m, the more difficult and costly it is to remove particulate materials. Minimizing the production of small particles reduces the overall amount of filtration needed. The high rotational speed of a centrifugal pump

J. D McMillan; F. W Wheaton; J. N Hochheimer; J Soares

2003-01-01

275

Rating fixed film nitrifying biofilters used in recirculating aquaculture systems  

Microsoft Academic Search

Predicting the performance of biofilters is an engineering challenge that is critical to both designers and managers. The task is complicated by the wide variety of water quality expectations and environmental conditions displayed by a recirculating aquaculture system (RAS). A myriad of biofilters designs have been generated reflecting approaches of engineers attempting to maximize specific surface area and oxygen transfer

Ronald F. Malone; Timothy J. Pfeiffer

2006-01-01

276

Exergetic performance analysis of a recirculating aquaculture system  

Microsoft Academic Search

This paper examines exergetic aspects of a Recirculation Aquaculture System (RAS) for Black Sea trout (Salmo trutta labrax) fingerling rearing at the Trabzon Central Fisheries Research Institute, Turkey. In its thermodynamic analysis, each component of the RAS is treated as a steady-state steady flow system and its exergetic efficiencies are studied. In addition, the following parameters are measured and recorded

Haydar Kucuk; Adnan Midilli; Atilla Özdemir; Eyüp Çakmak; Ibrahim Dincer

2010-01-01

277

Anaerobic digestion of sludge from intensive recirculating aquaculture systems: Review  

Microsoft Academic Search

Intensive recirculating aquaculture systems (RAS) produce high volumes of biosolid waste which is a potential source of pollution if not properly treated. A reduction in sludge-mass would therefore minimize the potential environmental hazard and economic burden stemming from its disposal. Recently, anaerobic digestion was suggested as an alternative to aquaculture sludge digestion and stabilization in RAS. This practice results not

Natella Mirzoyan; Yossi Tal; Amit Gross

2010-01-01

278

Exhaust gas recirculation apparatus for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation apparatus for an internal combustion engine is described that is provided with a vacuum-operated EGR valve having a diaphragm which forms a vacuum control chamber on one side of the diaphragm, which chamber is connected to a vacuum port formed in the engine intake system for transmitting a vacuum signal to the chamber in order to

1978-01-01

279

Exhaust gas recirculation system of a motor vehicle  

Microsoft Academic Search

An improvement for an exhaust gas recirculation (EGR) system of a motor vehicle is described. The system consists of: (1) a diaphragm type EGR valve mounted on an EGR pipe which connects the exhaust manifold and the intake manifold; (2) an opening path for air from the atmosphere diverged from a connecting pipe which connects the diaphragm chamber of the

Hamanishi

1977-01-01

280

Dynamic Scheduling of Internal Exhaust Gas Recirculation Systems.  

E-print Network

manifold to the intake mani- fold through a vacuum actuated valve. The EGR control algorithm is a simple PI events. Optimized valve events can improve the gas exchange process and enable control of internal EGR Exhaust gas recirculation (EGR) was introduced in the early 1970s to reduce the formation of oxides of ni

Stefanopoulou, Anna

281

Exhaust gas recirculation system in an internal combustion engine  

Microsoft Academic Search

This application discloses an exhaust gas recirculation system in an internal combustion engine. The system is comprise of: (1) an EGR pipe which interconnects an exhaust pipe and an intake pipe of the engine; (2) an EGR valve mounted of the EFR pipe; (3) an EGR cooler mounted on the EGR pipe upstream of said EGR valve; (4) a by-pass

Nagano

1979-01-01

282

Energy stability in recirculating, energy-recovering linacs.  

National Technical Information Service (NTIS)

Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M(sub 5...

L. Merminga, J. J. Bisognano, J. R. Delayen

1996-01-01

283

EVALUATION OF A PAINT SPRAY BOOTH UTILIZING AIR RECIRCULATION  

EPA Science Inventory

The objective of this project was to evaluate the effectiveness of the recirculating air spray booth process at the Deere and Company facility in Davenport, Iowa. The effort involved a field measurement program and subsequent analysis of flow rates and emission data from the spra...

284

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

285

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

286

Liquid hydrogen and liquid oxygen feedline passive recirculation analysis  

Microsoft Academic Search

During the National Launch System design phase, a computer code (FEEDLINE) was written to analyze the feasibility of using passive recirculation propellant conditioning for the LH2 and LO2 feed systems. The FEEDLINE code was employed to provide temperature profiles to the STME design team. The team used the temperature profiles to determine if the required Space Transportation Main Engine net

Kimberly A. Holt; Nicole L. Cleary; Andrew J. Nichols; Gretchen L. E. Perry

1993-01-01

287

The recirculation dynamics of bluff body stabilized premixed combustion  

Microsoft Academic Search

Bluff body stabilized premixed combustion is present in many power generation and propulsion systems such as gas turbines and afterburners. In this environment, flow recirculation behind the bluff body provides low speed, hot products that act as an ignition source for the incoming reactants and help anchor the flame. Beyond this coarse phenomenological description, however, understanding of bluff body flame

Marios Soteriou

2005-01-01

288

Ozone Application in Recirculating Aquaculture System: An Overview  

Microsoft Academic Search

In recirculating aquaculture systems (RAS), particulates (including feces, uneaten feed, bacteria, and algae) can cause several problems, in that they may harbor pathogens, can physically irritate the fish, and upon decomposition, release ammonia and consume oxygen. Mechanical filters, foam fractionators, and other engineered devices are used to remove particles quickly from aquaculture systems, in order to improve fish health and

Alex Augusto Gonçalves; Graham A. Gagnon

2011-01-01

289

Exhaust gas recirculation system controlled by a microcomputer for an internal combustion engine  

Microsoft Academic Search

An exhaust gas recirculation system controlled by a microcomputer for an internal combustion engine is comprised of a pressure sensor for measuring the pressure of the exhaust gas downstream of an orifice disposed in the exhaust gas recirculation passage, a microcomputer for electrically controlling an electromagnetic valve which fluidly controls an exhaust gas recirculation control valve arranged in the exhaust

T. Yano; H. Yuzawa

1981-01-01

290

Diesel engine exhaust gas recirculation system with greater atmospheric pressure compensation at low engine load  

Microsoft Academic Search

An exhaust gas recirculation system is described for a diesel engine for a vehicle utilizing an air intake system and an exhaust system including: (a) an exhaust gas recirculation passage a downstream and of which is connected to the exhaust system and an upstream end of which is connected to the air intake system, so as to recirculate exhaust gas

M. Kawagoe; O. Hishinuma

1986-01-01

291

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 a system, consult with an aquaculture specialist or an expert on recirculating systems. #12;2 All important Introduction Both the popularity and use of recirculating systems have increased, and these systems are now

Watson, Craig A.

292

Diesel engine exhaust gas recirculation and intake air flow control system  

Microsoft Academic Search

In a diesel engine which includes an air intake system, an exhaust system, and an exhaust gas recirculation passage which recirculates part of the exhaust gases produced by the engine from the exhaust system to the air intake system, a control system for the recirculation of exhaust gases and the flow of intake air, having an intake air flow control

K. Hiyama; T. Ueda

1982-01-01

293

Dry scrubbing of acid gases in recirculating cyclones.  

PubMed

This paper describes a laboratory-scale study on the use of recirculating cyclones as reaction chambers for dry scrubbing of gaseous HCl with solid slaked lime particles. This gas cleaning system combines a numerically optimized reverse flow gas cyclone (RS_VHE geometry) with a straight-through cyclone concentrator, which simultaneously increases the capture of the solid particles and promotes their partial recirculation. A laboratory-scale study was undertaken to test this technology and to compare its performance to a modified Stairmand HE reverse flow cyclone without recirculation. The experimental conditions were: reaction temperature approximately 326 K, gas flow rate approximately 2.9 x 10(-4) Nm(3) s(-1) and relative humidity of the gas approximately 8.5%. The experimental variables tested were the solids load (1.0-9.2 x 10(-7) kg s(-1)) and HCl concentration (0.4-2.8 x 10(-2) mol m(-3)) in the inlet gas. The experimentally obtained particulate removal efficiencies with the recirculating cyclones ( approximately 98%) were higher than those obtained with the Stairmand HE cyclone ( approximately 93%), with the additional advantage of having significantly lower pressure drop. As for the acid removal efficiencies ( approximately 10-96%), no significant differences were found between the two systems tested under the same experimental conditions. The possibility of using optimized recirculating cyclones for gas cleaning in a dry scrubbing process is very promising, since this is a low cost technology, highly efficient both for the removal of acid gases and for the capture of solid particles, which has the advantage of not requiring a post-reaction de-duster. PMID:17360111

Chibante, Vânia; Fonseca, Ana; Salcedo, Romualdo

2007-06-18

294

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

295

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

296

Particle transport in recirculated liquid metal flows  

Microsoft Academic Search

Purpose – Aims to present recent activities in numerical modeling of turbulent transport processes in induction crucible furnace. Design\\/methodology\\/approach – 3D large eddy simulation (LES) method was applied for fluid flow modeling in a cylindrical container and transport of 30,000 particles was investigated with Lagrangian approach. Findings – Particle accumulation near the side crucible boundary is determined mainly by the

M. Kirpo; A. Jakovi?s; B. Nacke; E. Baake

2008-01-01

297

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

298

External Mass Transfer Model for a Recirculated Packed-Bed Batch Reactor on the Hydrolysis of Palm Olein Using Immobilized Lipase  

Microsoft Academic Search

The application of immobilized enzyme in organic synthesis is gaining popularity as it offers advantages over conventional chemical reactions. A recirculated packed-bed batch reactor (RPBBR) can be used for immobilized enzyme systems. However, external mass transfer limitation is significant in an RPBBR, especially at large scales. This study investigated the external mass transfer coefficients in an RPBBR. The effect of

Chew Yin Hoon; Lee Chew Tin

299

Digital feedwater and recirculation flow control for GPUN Oyster Creek  

SciTech Connect

This paper describes the digital system for feedwater and recirculation control that GPU Nuclear will be installing at Oyster Creek during its next outage - expected circa December 1992. The replacement was motivated by considerations of reliability and obsolescence - the analog equipment was aging and reaching the end of its useful life. The new system uses Atomic Energy of Canada Ltd.'s software platform running on dual, redundant, industrial-grade 386 computers with opto-isolated field input/output (I/O) accessed through a parallel bus. The feedwater controller controls three main feed regulating valves, two low flow regulating valves, and two block valves. The recirculation controller drives the five scoop positioners of the hydraulic couplers. The system also drives contacts that lock up the actuators on detecting an open circuit in their current loops.

Burjorjee, D. (Atomic Energy of Canada Ltd., Mississauga, Ontario (Canada)); Gan, B. (GPU Nuclear Corp., Parsippany, NJ (United States))

1992-01-01

300

Numerical analysis of confined recirculating gas-solid turbulent flows  

NASA Technical Reports Server (NTRS)

Particle dispersion in confined recirculating turbulent flows has been investigated numerically. The present computational scheme utilizes Eulerian forms of the governing equations and allows two-way coupling between gas and solid phases. A recently developed two-phase closure model based on the multiple-scale turbulence model was used for the estimation of turbulent viscosities and diffusivities. For the particle size and loading considered in this study, the effect of particulate phase on the conveying gas is small, the nonequilibrium between the two phases is significant. Effects of recirculation, expanded chamber size and secondary annular jet momentum on the particle mixing rate are also investigated. In general, the present numerical results are in reasonably good agreement with the available experimental data.

Chen, C. P.

1986-01-01

301

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

302

TRACG Simulation of Drywell Gas Recirculation System in ESBWR  

Microsoft Academic Search

This paper presents the results of a parametric study on the mitigating effects of the Drywell Gas Recirculation System (DGRS) in ESBWR during postulated LOCA and severe accidents. The post-accident containment pressure depends on the sum of the partial pressure from non-condensable gases and partial steam pressure inside the wet-well airspace. Results of parametric studies show that, with the activation

Yee K. Cheung; Atambir S. Rao

2002-01-01

303

Improved numerical methods for turbulent viscous recirculating flows  

NASA Technical Reports Server (NTRS)

The objective of the present study is to improve both the accuracy and computational efficiency of existing numerical techniques used to predict viscous recirculating flows in combustors. A review of the status of the study is presented along with some illustrative results. The effort to improve the numerical techniques consists of the following technical tasks: (1) selection of numerical techniques to be evaluated; (2) two dimensional evaluation of selected techniques; and (3) three dimensional evaluation of technique(s) recommended in Task 2.

Vandoormaal, J. P.; Turan, A.; Raithby, G. D.

1986-01-01

304

Packed-bed reactor with continuous recirculation of electrolyte  

Microsoft Academic Search

A comparison of calculated and experimental parameters for the packed-bed reactor working with recirculation of the electrolyte is given. A simple mathematical model was applied and the applicability of the relation\\u000a$$c = c^0 {\\\\text{ exp(}} - k_1 At\\/V{\\\\text{) for }}V_c \\\\ll V_R $$\\u000a was tested. For the investigated reactor a dimensionless relation has been established from experimentalI-E curves for

Dj. Mati?

1979-01-01

305

Mathematical modeling of leachate routing in a leachate recirculating landfill  

Microsoft Academic Search

Full-scale application of leachate recirculation has been hampered by an inability to uniformly apply leachate to the waste mass. Much of this problem is due to the varied nature of the disposed waste which promotes preferential routing and short-circuiting of leachate flows. The United States Geological Survey’s Saturated-Unsaturated Flow and Transport (SUTRA) model [Voss C. I. (1984) SUTRA, Saturated–Unsaturated Transport,

Philip T McCreanor; Debra R Reinhart

2000-01-01

306

Ammonia Conversion Characteristics in a Closed Recirculating Aquaculture System  

Microsoft Academic Search

Nitrification and denitrification were commonly used in the recirculating aquaculture system (RAS) to decrease the ammonia and nitrate concentration. The variation characteristics of nitrogenous compounds and microbiology in a closed RAS were studied with gradually increasing ammonia-nitrogen (NH4 +-N) concentration. The NH4 +-N was completely converted into nitrite nitrogen (NO2 --N) in 46 days, but the NO2 --N raised slowly

Guang-Yu Wang; Ji-xian Yang; Fang Ma; Lei Chen; Wei-Guo Li; Jingbo Guo

2009-01-01

307

Steering algorithms for a small recirculating heavy-ion accelerator  

SciTech Connect

Beam-steering algorithms are proposed for a small recirculating induction accelerator being built at the Lawrence Livermore National Laboratory. The principal problem is that the transverse position and velocity of the beam must be inferred from capacitive position monitors, and this determination is complicated by the limited probe resolution and by the lattice errors within steering modules. The fluid/envelope code CIRCE is used to evaluate these algorithms.

Sharp, W.M.; Grote, D.P.; Hemandez, G.W.

1997-11-07

308

Turbulent flows on forested hilly terrain: the recirculation region  

Microsoft Academic Search

ABSTRACT: A number,of analytical and numerical,studies employing,first-order closure principles have suggested that canopy flows on gentle sinusoidal hills feature a recirculation region, situated on the lee side, that can dramatically affect scalar transfer between the biosphere and the atmosphere. To date, the onset of this region, and its effects on bulk flow properties, have not been experimentally investigated. We study

D. Poggi; G. G. Katul

2007-01-01

309

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

310

Air pollution in the shore zone of a Large Alpine Lake - 1 - Road dust and urban aerosols at Lake Tahoe, California-Nevada  

NASA Astrophysics Data System (ADS)

Concentrated human activity and limited atmospheric mixing create a high potential for airborne pollutant impacts to alpine lakes developed as mountain resorts. Lake Tahoe is a major alpine resort straddling the California-Nevada border, receiving more than two million visitors each year. The lake's clarity has declined substantially since the inception of intense development in the Tahoe basin in the 1970s. The 2002-2004 Lake Tahoe Atmospheric Deposition Study (LTADS) was conducted as part of a multi-agency effort to develop a water quality management plan for the lake. Estimating aerosol deposition to the lake requires detailed knowledge of the spatial and temporal patterns of aerosol concentration, size distribution, and chemical composition over the entire basin - and developing a management plan requires also that the sources of the aerosols be known with considerable specificity. In lieu of the intensive measurement network implied by this level of detail, we hypothesized that a set of measurements to characterized the temporal, spatial, and size distribution patterns of particles in ambient air and in local emissions in the vicinity of Lake Tahoe could be used to extrapolate long time series of simple measurements to an annual aerosol deposition computation. Here we report the results of our detailed aerosol measurement campaign. Our results show that there are strong systematic and repeating gradients in aerosol loading that occur as functions of location, land use, traffic activity, and time of day, and that road dust is a major source of aerosols around the lake. In addition, we observed strong consistency of particle size distributions as a function of source type, largely independent of particle concentrations. Finally, we demonstrated the use of particle counters to directly observe downwind dispersion and deposition of particles. Together, these findings support the use of imputed location- and time-specific size distributions in annual aerosol deposition calculations, even though particle size distributions were not directly measured in the LTADS baseline monitoring program, and that program was conducted at only a limited set of sites in the Tahoe basin. Two companion articles in this journal issue describe the overall findings of the LTADS study (Dolislager et al., "Overview of the Lake Tahoe Atmospheric Deposition Study") and the results of measurements taken on the lake itself (VanCuren et al., "Air Pollution in the Shore Zone of a Large Alpine Lake - 2 - Local and Regional Pollutant Distribution over Lake Tahoe California-Nevada").

VanCuren, R.; Pederson, J.; Lashgari, A.; Dolislager, L.; McCauley, E.

2012-01-01

311

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

312

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

313

Increased brightness by light recirculation through an LED source  

NASA Astrophysics Data System (ADS)

LED light sources are finding ever increasing application in illumination. LEDs have many advantages, such as high efficiency, long life, compactness, directional light emission, mechanical resistance, low-temperature operation, light color control and low UV or IR emissions. These and other advantages make them very well suited for general illumination applications as well as flashlights, car headlights, backlights, or frontlights. In most applications, LEDs are combined with optics to direct their light output. Brighter LEDs have a smaller emission area and, therefore, may be coupled to smaller optics. This is very important in many applications where compactness is crucial, particularly automotive headlamps. When LED brightness is insufficient, it can be augmented by recirculating part of the emitted light back to the LED's emitting surface. This increase in brightness comes at the expense of a reduced flux-emission. As an example, the brightness of an LED with a diffuse reflectivity of 70% may be increased by nearly that much if it is coupled to a high-efficiency recirculating optic. Such augmentation, however, comes at the expense of a flux reduction, as much as 50%. Several optical geometries are explored in this paper to achieve that recirculation together with raytracing results using on a simple model of an LED. Also a number of optical architectures will be shown that escape the classical nonimaging etendue limit associated with traditional optics.

Chaves, Julio C.; Falicoff, Waqidi; Parkyn, Bill; Benítez, Pablo; Miñano, Juan C.

2008-08-01

314

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

315

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

316

Mechanisms of solute transport and dispersion in open channels with surface storage zones  

NASA Astrophysics Data System (ADS)

Lateral cavities in rivers and open channels are distinctive morphodynamic features that work as transient storage zones, which play a significant role on the dispersion and transport of contaminants in the stream. The dynamics of large-scale coherent structures in these turbulent flows constitute the controlling mechanisms of mass-exchange and residence times in the cavity. In this work we study the recirculating flow in lateral rectangular cavities with aspect ratios 1.0 and 3.0. We focus on the complex dynamics of the flow in the cavities and the differences as function of the geometry represented by the aspect ratio. By using time-resolved Particle Image Velocimetry (PIV) and numerical simulations with hybrid turbulence models (URANS/LES), we provide new insights on the mechanisms of dispersion and transport of contaminants for each aspect ratio, analyzing the statistics of mass exchange and residence times for these two configurations.

Escauriaza, C. R.; Soto, K.; Gonzalez, C.; Wei, C.; Mignot, E.; Riviere, N.

2013-12-01

317

A study of NO{sub x} reduction by fuel injection recirculation. Final report, January 1995--June 1996  

SciTech Connect

Flue-gas recirculation (FGR) is a well-known method used to control oxides of nitrogen (NO{sub x}) in industrial burner applications. Recent small- and large-scale experiments in natural-gas fired boilers have shown that introducing the recirculated flue gases with the fuel results in a much greater reduction in NO{sub x}, per unit mass of gas recirculated, in comparison to introducing the flue gases with the combustion air. That fuel injection recirculation (FIR) is more effective than windbox FGR is quite remarkable. At present, however, there is no definitive understanding of why FIR is more effective than conventional FGR. The objective of the present investigation is to ascertain whether or not chemical and/or molecular transport effects alone can explain the differences in NO{sub x} reduction observed between FIR and FGR by studying laminar diffusion flames. The purpose of studying laminar flames is to isolate chemical effects from the effects of turbulent mixing and heat transfer, which are inherent in practical boilers. The results of both the numerical simulations and the experiments suggest that, although molecular transport and chemical kinetic phenomena are affected by the location of diluent addition depending on flow conditions, the greater effectiveness of FIR over FGR in practical applications may result from differences in turbulent mixing and heat transfer. Further research is required to understand how differences in diluent-addition location affect NO{sub x} production in turbulent flames. The present study, however, provides an underlying basis for understanding how flow conditions can affect flame chemistry. 51 figs., 7 tabs.

Feese, J.J.; Turns, S.R.

1996-08-01

318

Characterizing multiple timescales of stream and storage zone interaction that affect solute fate and transport in streams  

Microsoft Academic Search

The fate of contaminants in streams and rivers is affected by exchange and biogeochemical transformation in slowly moving or stagnant flow zones that interact with rapid flow in the main channel. In a typical stream, there are multiple types of slowly moving flow zones in which exchange and transformation occur, such as stagnant or recirculating surface water as well as

Jungyill Choi; Judson W. Harvey; Martha H. Conklin

2000-01-01

319

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

320

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

DOEpatents

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

321

Microvortices and recirculating flow generated by an oscillatory microplate for microfluidic applications  

NASA Astrophysics Data System (ADS)

Circulatory flow structures can be useful in a microfluidic device but often are difficult to generate mechanically in microscale. This paper presents generation of such flow via an in-plane resonating microplate (100×100×1.2?m3) actuated by Lorentz law. Results show either one of two nonlinear time-mean flow structures is feasible for the finite plate: (1) two-dimensional (2D) small-scale, counter-rotating microvortices or (2) three-dimensional, large-scale, recirculating flow. Sharpness of microplate's edge is found to be the decisive factor for 2D microvortices to form. Both flow structures are robust and controllable. Potential applications include trapping and mixing of bioparticles in microfluidic devices.

Lin, Cheng Ming; Lai, Yu Shang; Liu, Hsin Ping; Wo, Andrew M.

2008-09-01

322

The northern recirculation gyre of the gulf Stream  

NASA Astrophysics Data System (ADS)

Results from two recent field programsin the western North Atlantic are presented with particular emphasis on the deep circulation. New long-term moored current measurements show that the flow north of the Gulf Stream and east of the New England Seamount Chain is toward the west from 500 m to the bottom with very little depth dependence. Nearly 40 × 10 6 m 3s -1 is transported to the west near 63°W, and half of this recirculates back to the east over the Seamount Chain to add a strong component to the deep Gulf Stream between the Chain and the Grand Banks. We call this current the "Northern Recirculation Gyre" in contrast with a similar feature to the south of the Stream popularly known as the "Worthington Gyre" ( WORTHINGTON, 1976, The Johns Hopkins Oceanographic Studies, 6, 110 pp.). The new gyre is similar to that proposed by HOGG (1983, Deep-Sea Research, 30, 945-961) but somewhat smaller in scale. Its relationship to the Gulf Stream and the Deep Western Boundary Current is made explicit by the new measurements. Tracer measurements show that the Northern Recirculation Gyre exchanges water properties with the Deep Western Boundary Current where the two are in close proximity along the northern boundary. The relatively high values of oxygen and freon, so imparted, are then advected to the interior where the gyre carries water eastward under the Gulf Stream. Beneath the thermocline these tracer fields are practically homogenous within the gyre, perhaps a reflection of the expulsion process described by RHINES and YOUNG (1983, Journal of Fluid Mechanics, 133, 133-145). An advective-diffusive model is used to interpret some slight differences between the various tracer distributions.

Hogg, Nelson G.; Pickart, Robert S.; Hendry, Ross M.; Smethie, William J.

1986-09-01

323

[Analysis of effect of sludge recirculation on setting efficiency in horizontal sedimentation tank].  

PubMed

The problem that the present sediment theory does not consider sludge recirculation effect on the efficiency of particle settling is studied. Based on the longitudinal mixing settling theory, an imperfect sediment model that takes reflux ratio in consideration is built. According to the established model, the study analyzes the effect of sludge recirculation taken by suction dredge on particle setting, in horizontal sedimentation tank. Specifically, the relation between overplus of sewerage suspension and sedimentation rate was chosen as an example. Shown as a result, when sludge recirculation is not taken in consideration, efficiency of particle settling is 72.8%. However, when sludge recirculation increases from 0.5 to 3.0, efficiency of particle settling decreases from 71.1% to 50.9%, which is smaller than efficiency of particle settling without recirculation; and when sludge recirculation is 3.0, efficiency of particle settling is 50.9%, which is approximately 30% less than efficiency of particle settling without recirculation. So, sludge recirculation make efficiency of particle settling is smaller than efficiency of particle settling without recirculation, and the efficiency of particle settling reduces with the increase of reflux ratio. PMID:17633172

Zou, Zhi-hong; Zhang, Wei; Sui, Jun

2007-05-01

324

Anammox bacteria in different compartments of recirculating aquaculture systems.  

PubMed

Strict environmental restrictions force the aquaculture industry to guarantee optimal water quality for fish production in a sustainable manner. The implementation of anammox (anaerobic ammonium oxidation) in biofilters would result in the conversion of both ammonium and nitrite (both toxic to aquatic animals) into harmless dinitrogen gas. Both marine and freshwater aquaculture systems contain populations of anammox bacteria. These bacteria are also present in the faeces of freshwater and marine fish. Interestingly, a new planctomycete species appears to be present in these recirculation systems too. Further exploitation of anammox bacteria in different compartments of aquaculture systems can lead to a more environmentally friendly aquaculture practice. PMID:22103532

van Kessel, Maartje A H J; Harhangi, Harry R; Flik, Gert; Jetten, Mike S M; Klaren, Peter H M; Op den Camp, Huub J M

2011-12-01

325

Recirculation of In-Plant Air at General Motors  

E-print Network

for cleaning up the in-plant environment at GM is the rotary drum filter. This rotary drum filter is an air cleaning unit manufactured by two indus trial concerns. It consists of an expanded metal drum fitted with two layers of media. The inner layer... are controlled by recirculating plant air through rotary drum filters in winter and flush ventilation in the summer. Air tempering was con sidered, but dismissed as a viable alternative pri marily due to cost benefit. If summer temperatures could...

McKibben, V. L.

1983-01-01

326

Exhaust gas recirculation system for an internal combustion engine  

SciTech Connect

Disclosed herein is a back pressure control type EGR system for an internal combustion engine, wherein a vacuum modulator has an air introducing chamber which is selectively opened, in accordance with the pressure of recirculated exhaust gas, to a vacuum line connecting an EGR port with a vacuum operated flow control valve. The air introducing chamber is further connected to another vacuum port formed slightly above the EGR port via another vacuum line. Switching valve devices responsive to the temperature of the engine are located on the vacuum lines for stopping the EGR operation when the engine is cold.

Abe, T.; Ota, I.

1980-09-16

327

Liquid hydrogen and liquid oxygen feedline passive recirculation analysis  

NASA Astrophysics Data System (ADS)

During the National Launch System design phase, a computer code (FEEDLINE) was written to analyze the feasibility of using passive recirculation propellant conditioning for the LH2 and LO2 feed systems. The FEEDLINE code was employed to provide temperature profiles to the STME design team. The team used the temperature profiles to determine if the required Space Transportation Main Engine net positive suction pressure was met. One desired outcome of the LH2 testing was to determine if modifications are required for the FEEDLINE code. The initial LN2 calibration tests indicate that the environmental heat into the system decreases with increasing heater input.

Holt, Kimberly A.; Cleary, Nicole L.; Nichols, Andrew J.; Perry, Gretchen L. E.

328

Large-Strain Frictional Behavior of Megasplay Fault Zone Materials and Accretionary Wedge Sediments Recovered from NanTroSEIZE Expedition 316 Drilling  

NASA Astrophysics Data System (ADS)

At subduction interfaces, the updip limit of seismic slip is a critical issue, particularly regarding tsunamigenesis. A key question is - Do megasplay faults, which branch from the subduction megathrust at depth, slip seismically? A critical factor controlling the occurrence of seismic slip is the velocity dependence of friction of fault rocks. We are therefore conducting a broad experimental survey of the frictional properties of megasplay fault and other materials retrieved via NanTroSEIZE Expedition 316 drilling. Our rotary-shear apparatus allows for tests to shear strains in excess of 1000, to explore the tendency for slip localization and its often associated velocity-weakening (VW) frictional behavior, a necessary condition for unstable slip. Tests on materials recovered at site C0004D - a ‘microbreccia’ from the megasplay fault zone at 275 mbsf, Section 29R-2, and a mudstone from the accretionary prism overlying the megasplay fault at 252 mbsf, Section 24R-1 - were conducted at an estimated in situ normal stress of ?n=31.6 MPa and pore pressure Pp =25.8 MPa, for total slips ? of 1 to 3.4 m. All tests yielded initial values of the friction coefficient µ ? 0.6 at V=1 and 10 µm/s; however, all samples dramatically slip weaken to nominally steady-state values in the range µ=0.16 to 0.4 within ?=0.2 m at those slip rates. For Section 29R-2 samples, the friction behavior is velocity-strengthening (VS) over the V range 1 nm/s to 5 mm/s, except for VW behavior for V=0.1 - 10 µm/s observed in some tests. The magnitude of the friction velocity dependence (i.e., the rate and state friction quantity a - b) in the 29R-2 tests decreases dramatically with increasing ?, for both VS and VW behavior, in some cases yielding a transition from VS to VW over 1 to 2 meters of slip. For Section 24R-1 samples, VS behavior is observed for V=1 nm/s to 32 µm/s in one test. In another test, after a slip of 0.5 m at 0.1 to 10 µm/s, yielding VS behavior, four sequential, identical high-velocity-stepping sequences were conducted, each of which stepped V progressively up, then down, in (typically) factor-of-three increments in the range V=1 µm/s - 10 mm/s, with each sequence accruing 0.8 m of slip. VS behavior was observed at all velocities until the end of the second high-V sequence, after which VW behavior emerged at V=1 - 100 µm/s and persisted until the end of the test (total ?=3.4 m). Our experiments underscore the possible importance of slip localization leading to velocity-weakening friction and therefore conditionally unstable slip. In all tests in this study, strong VS behavior is observed above V=100 µm/s, which we tentatively attribute to dilation hardening. This strong VS barrier to rapid slip for V>100 µm/s, and the limited range of VW behavior at V=1 - 100 µm/s, for materials subjected to large shear strains, may allow for the propagation of slow slip events in regions above the Nankai megathrust.

Goldsby, D.; Fabbri, O.

2010-12-01

329

Correlation and emplacement of a large, zoned, discontinuously exposed ash flow sheet: The 40 Ar\\/ 39 Ar chronology, paleomagnetism, and petrology of the Pahranagat Formation, Nevada  

Microsoft Academic Search

Many single-cryslal 4oAr\\/3gAr ages and thermoremanent magnetization directions have resolved the problematic stratigraphic correlation of the laterally and vertically zoned rhyolite ash flow sheet of the Pahranagat Formation in the southern Great Basin. This outflow sheet was previously designated by four different stratigraphic names in different locations over its highly discontinuous exposure area of 33,000 kmz. We show that it

Myron G. Best; Eric H. Christiansen; Alan L. Deino; C. Sherman Grommé; David G. Tingeyl

1995-01-01

330

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

331

Liquid flow focused by a gas: jetting, dripping, and recirculation.  

PubMed

The liquid cone-jet mode can be produced upon stimulation by a coflowing gas sheath. Most applications deal with the jet breakup, leading to either of two droplet generation regimes: Jetting and dripping. The cone-jet flow pattern is explored by direct axisymmetric volume of fluid (VOF) numerical simulation; its evolution is studied as the liquid flow rate is increased around the jetting-dripping transition. As observed in other focused flows such as electrospraying cones upon steady thread emission, the flow displays a strong recirculating pattern within the conical meniscus; it is shown to play a role on the stability of the system, being a precursor to the onset of dripping. Close to the minimum liquid flow rate for steady jetting, the recirculation cell penetrates into the feed tube. Both the jet diameter and the size of the cell are accurately estimated by a simple theoretical model. In addition, the transition from jetting to dripping is numerically analyzed in detail in some illustrative cases, and compared, to good agreement, with a set of experiments. PMID:18851159

Herrada, Miguel A; Gañán-Calvo, Alfonso M; Ojeda-Monge, Antonio; Bluth, Benjamin; Riesco-Chueca, Pascual

2008-09-01

332

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

333

Design of a scaled recirculator for Heavy Ion Inertial Fusion  

NASA Astrophysics Data System (ADS)

An alternative concept for Heavy Ion Inertial Fusion (HIF) is the use of a recirculator to accelerate ion beams to energies in the range of 50-100 GeV [1]. The physics of an ion recirculator can be explored by means of scaled experiments in a compact machine like the existing University of Maryland Electron Ring (UMER). UMER has been successfully used for the study of the fundamental physics of space-charge-dominated transport using a 10 keV electron beam with up to 100 mA of current (or 10 nC per a 100 ns pulse) [2]. Due to the low energy and high perveance, the UMER beam accesses the same range of intensities as an HIF driver. In this paper we report on a computational study for the design of an acceleration stage for UMER using an induction cell. Using the two-dimensional transverse slice model in the particle-in-cell code WARP we show that it is possible to accelerate the UMER beam up to 20 keV without major modifications to the machine. Such acceleration enables future experiments on transverse resonance crossing and studies on longitudinal pulse behavior.

Fiuza, K.; Beaudoin, B.; Bernal, S.; Haber, I.; Kishek, R. A.; O'Shea, P. G.; Papadopoulos, C.; Sutter, D.; Wu, C.

2010-08-01

334

Vortical Structures in Wall-Bounded Turbulent Flow with Recirculation  

NASA Astrophysics Data System (ADS)

Hairpin or horse-shoe vortices are a widely-accepted feature of the wall-bounded flows. These vortical structures have mostly been studied in canonical flows. Relatively few studies have been conducted on the characteristics of the vortical structures in wall-bounded flows with adverse pressure gradient and still fewer on the detached flows with recirculation. In the present contribution, vortices have been educed using a DNS database of incompressible flow over a 2-dimensional surface bump in a converging-diverging channel at a Reynolds number Re? of 617, based on the friction velocity at inlet. Vortices have been educed from the instantaneous velocity field in streamwise/wall-normal and spanwise/wall-normal planes using the signed swirling strength criterion. Vortex validation is done through a fit of the vortex velocity field to the Oseen vortex model. The effects of a strong adverse pressure gradient and flow reciruclation on the population density and sizes of the streamwise and spanwise-oriented vortices have been studied. It has been found that a strong adverse pressure gradient and flow recirculation leads to the generation of a new near-wall peak of small spanwise prograde vortex population. Furthermore, this peak of vortex density has been found to coincide and hence relate to the outward movement of the peak of streamwise rms velocity fluctuations typical of adverse pressure gradient wall-bounded turbulent flows.

Imran Shah, Syed

2011-12-01

335

Continuous hydroponic wheat production using a recirculating system  

NASA Technical Reports Server (NTRS)

Continuous crop production, where plants of various ages are growing simultaneously in a single recirculating nutrient solution, is a possible alternative to batch production in a Controlled Ecological Life Support System. A study was conducted at John F. Kennedy Space Center where 8 trays (0.24 sq m per tray) of Triticum aestivum L. Yecora Rojo were grown simultaneously in a growth chamber at 23 C, 65 percent relative humidity, 1000 ppm CO2, continuous light, with a continuous flow, thin film nutrient delivery system. The same modified Hoagland nutrient solution was recirculated through the plant trays from an 80 L reservoir throughout the study. It was maintained by periodic addition of water and nutrients based on chemical analyses of the solution. The study was conducted for 216 days, during which 24 trays of wheat were consecutively planted (one every 9 days), 16 of which were grown to maturity and harvested. The remaining 8 trays were harvested on day 216. Grain yields averaged 520 g m(exp -2), and had an average edible biomass of 32 percent. Consecutive yields were unaffected by nutrient solution age. It was concluded that continual wheat production will work in this system over an extended period of time. Certain micronutrient deficiencies and toxicities posed problems and must be addressed in future continuous production systems.

Mackowiak, C. L.; Owens, L. P.; Hinkle, C. R.; Prince, R. P.

1989-01-01

336

Timing of large earthquakes since A.D. 800 on the Mission Creek strand of the San Andreas fault zone at Thousand Palms Oasis, near Palm Springs, California  

USGS Publications Warehouse

Paleoseismic investigations across the Mission Creek strand of the San Andreas fault at Thousand Palms Oasis indicate that four and probably five surface-rupturing earthquakes occurred during the past 1200 years. Calendar age estimates for these earthquakes are based on a chronological model that incorporates radio-carbon dates from 18 in situ burn layers and stratigraphic ordering constraints. These five earthquakes occurred in about A.D. 825 (770-890) (mean, 95% range), A.D. 982 (840-1150), A.D. 1231 (1170-1290), A.D. 1502 (1450-1555), and after a date in the range of A.D. 1520-1680. The most recent surface-rupturing earthquake at Thousand Palms is likely the same as the A.D. 1676 ?? 35 event at Indio reported by Sieh and Williams (1990). Each of the past five earthquakes recorded on the San Andreas fault in the Coachella Valley strongly overlaps in time with an event at the Wrightwood paleoseismic site, about 120 km northwest of Thousand Palms Oasis. Correlation of events between these two sites suggests that at least the southernmost 200 km of the San Andreas fault zone may have ruptured in each earthquake. The average repeat time for surface-rupturing earthquakes on the San Andreas fault in the Coachella Valley is 215 ?? 25 years, whereas the elapsed time since the most recent event is 326 ?? 35 years. This suggests the southernmost San Andreas fault zone likely is very near failure. The Thousand Palms Oasis site is underlain by a series of six channels cut and filled since about A.D. 800 that cross the fault at high angles. A channel margin about 900 years old is offset right laterally 2.0 ?? 0.5 m, indicating a slip rate of 4 ?? 2 mm/yr. This slip rate is low relative to geodetic and other geologic slip rate estimates (26 ?? 2 mm/yr and about 23-35 mm/yr, respectively) on the southernmost San Andreas fault zone, possibly because (1) the site is located in a small step-over in the fault trace and so the rate is not be representative of the Mission Creek fault, (2) slip is partitioned northward from the San Andreas fault and into the eastern California shear zone, and/or (3) slip is partitioned onto the Banning strand of the San Andreas fault zone.

Fumal, T.E.; Rymer, M.J.; Seitz, G.G.

2002-01-01

337

Exhaust gas recirculation system in compression-ignition internal combustion engine  

Microsoft Academic Search

In an exhaust gas recirculation system of a compression ignition internal combustion engine, there are provided two passages, that is, an EGR passage for recirculation of exhaust gases and a bypass passage by-passing the throttle valve in the induction passage to allow a supplemental air flow to the engine when EGR is cut off in definite engine operating conditions. These

Shinzawa

1982-01-01

338

Cross-flow type internal combustion engine with a small sized exhaust gas recirculating system  

Microsoft Academic Search

A cylinder head of a cross-flow type internal combustion engine is formed with a through hole or a groove which is associated with an exhaust gas recirculating system to simplify the exhaust gas recirculating system and simultaneously to make it small.

Y. Hayashi; H. Kamino; A. Ohnishi; M. Waku

1980-01-01

339

Association of Mycobacteria in Recirculating Aquaculture Systems and Mycobacterial Disease in Fish  

E-print Network

Association of Mycobacteria in Recirculating Aquaculture Systems and Mycobacterial Disease in Fish and aquarium surfaces. Therefore, the ecology of the NTM is consistent with reports of infections (e zoonotic potential, a better understanding of mycobacterial ecology and pathogen- esis in recirculating

Watson, Craig A.

340

The potential use of constructed wetlands in a recirculating aquaculture system for shrimp culture  

Microsoft Academic Search

A pilot-scale constructed wetland unit, consisting of free water surface (FWS) and subsurface flow (SF) constructed wetlands arranged in series, was integrated into an outdoor recirculating aquaculture system (RAS) for culturing Pacific white shrimp (Litopenaeus vannamei). This study evaluated the performance of the wetland unit in treating the recirculating wastewater and examined the effect of improvement in water quality of

Ying-Feng Lin; Shuh-Ren Jing; Der-Yuan Lee

2003-01-01

341

Membrane biological reactor treatment of a saline backwash flow from a recirculating aquaculture system  

Microsoft Academic Search

A recirculating aquaculture system (RAS) can minimize water use, allowing fish production in regions where water is scarce and also placing the waterborne wastes into a concentrated and relatively small volume of effluent. The RAS effluent generated during clarifier backwash is usually small in volume (possibly 0.2–0.5% of the total recirculating flow when microscreen filters are used) but contains high

Mark J. Sharrer; Yossi Tal; Drew Ferrier; Joseph A. Hankins; Steven T. Summerfelt

2007-01-01

342

Engine exhaust gas recirculation system with periodic recalibration of exhaust back pressure reference  

Microsoft Academic Search

The invention discloses an exhaust gas recirculation system in which the flow of recirculated exhaust gas is controlled through an orifice having exhaust back pressure on one side and a control pressure on the other, determined by an EGR valve. Apparatus is provided for sensing the control pressure and controlling the EGR valve in response to the sensed control pressure,

Lahiff

1979-01-01

343

Diagnosing system for an exhaust gas recirculation system of an automotive engine  

Microsoft Academic Search

This patent describes a diagnosing system for an exhaust gas recirculation system having an EGR passage communicating an exhaust pipe of an engine with an intake passage of the engine, an EGR valve provided in the EGR passage, control means for opening the EGR valve in accordance with enigne operating conditions comprising: first means for detecting flow rate of recirculated

Tamura

1988-01-01

344

Identification of optimum potassium nutrition of greenhouse plants grown in recirculating subirrigation  

E-print Network

of this research was to determine the optimum potassium nutrition of greenhouse plants grown in recirculating subirrigation. New Guinea impatiens 'Ovation Salmon Pink Swirl' were grown in recirculating subirrigation trays using 0 -12 mM K, with constant 1.5 mM P...

Blessington, Trisha R.

2012-06-07

345

Physics design and scaling of recirculating induction accelerators: from benchtop prototypes to drivers  

SciTech Connect

Recirculating induction accelerators (recirculators) have been investigated as possible drivers for inertial fusion energy production because of their potential cost advantage over linear induction accelerators. Point designs were obtained and many of the critical physics and technology issues that would need to be addressed were detailed. A collaboration involving Lawrence Livermore National Laboratory and Lawrence Berkeley National Laboratory researchers is now developing a small prototype recirculator in order to demonstrate an understanding of nearly all of the critical beam dynamics issues that have been raised. We review the design equations for recirculators and demonstrate how, by keeping crucial dimensionless quantities constant, a small prototype recirculator was designed which will simulate the essential beam physics of a driver. We further show how important physical quantities such as the sensitivity to errors of optical elements (in both field strength and placement), insertion/extraction, vacuum requirements, and emittance growth, scale from small-prototype to driver-size accelerator.

Barnard, J.J.; Cable, M.D.; Callahan, D.A.

1996-02-06

346

Dead Zones  

NSDL National Science Digital Library

The Earth currently has more than 400 "dead zones"--marine expanses covering hundreds, or even thousands, of square miles that periodically become virtually lifeless. Explore the surprising causes of Oregon's dead zones, and the pioneering methods used to research them.

347

Recirculation of Air Pollutants During Lake Breeze Events in Chicago  

NASA Astrophysics Data System (ADS)

Chicago is located at the southwestern end of Lake Michigan and experiences lake breezes on a regular basis during the summer months. In order to study transport and evolution of air pollution during such lake breeze events reactive trace gases NOx and ozone were measured as well as aerosol samples collected in summer 2003. The aerosol samples were analyzed for major ionic species by ion chromatography and for elemental species by total reflection X-ray fluorescence spectrometry. Several lake breeze events occurred during the field collections with one set of events on June 30 and July 1, 2003 standing out due to high levels of NOx and some aerosol species such as nitrate, iron and lead. The fully coupled chemistry-meteorology model WRF/CHEM was applied to simulate atmospheric conditions on these two days. The simulations show that a temperature and wind field front developed in the course of the lake breeze event creating a local cell of about 150km in diameter. Air and pollutants trapped in this cell appear to be re-circulating above Chicago and western Lake Michigan. The model results provide important insight on the evolution of ozone precursors, photolysis rates and ozone production during transport above the lake, and allow for quantifying the influence of this recirculation on the observed levels of local pollutants in Chicago. Whereas the June 30/July 1, 2003 lake breeze seems to be very pronounced, other lake breeze situations showed also enhanced NOx and nitrate mixing ratios compared to non-lake breeze days. Interestingly ozone mixing ratios were found to be lower in average during lake breeze events as compared to non-lake breeze conditions. To understand the development of the local lake breeze cell and possible recirculation of pollutants we plan to simulate temperature, wind field and pollutant level on other lake breeze days as well. Satellite data from the moderate resolution imaging spectrometer (MODIS) and Atmospheric Infrared Sounder (AIRS) will be used to highlight the general atmospheric distribution of aerosols and relative humidity within the region.

Schmeling, M.; Hodzic, A.; Massie, S. T.

2009-12-01

348

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

349

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

350

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

351

Numerical investigation of recirculation in the UTSI MHD combustor  

SciTech Connect

Numerical studies were carried out to investigate the gross structure of flow in cylindrical combustors. The combustor configurations studied are variations of a working design used at the University of Tennessee Space Institute to burn pulverized coal at temperatures in excess of 3000K for generation of a plasma feeding a magnetohydrodynamic channel. The numerical studies were conducted for an isothermal fluid; the main objective of the calculations was to study the effect of the oxidant injection pattern on the gross structure of recirculating flows within the combustor. The calculations illustrate the basic features of the flow in combustors of this type and suggest implications for the injection of coal and oxidizer in this type of combustor.

Schulz, R.J.; Lee, J.J.; Giel, T.V. Jr.

1983-09-01

352

Microbial diversity of biological filters in recirculating aquaculture systems.  

PubMed

Development of environmentally sustainable farming of marine and freshwater species using recirculating aquaculture systems (RASs) requires a complete understanding of the biological component involved in wastewater treatment. This component integrates biofilters composed of microbial communities whose structure, dynamics, and activities are responsible for system success. Engineering highly efficient, environmentally sound, disease-free, and economically viable systems necessitates a thorough knowledge of microbial processes involved in all facets of RAS biofilters and has only recently been the focus of comprehensive studies. These studies have included the application of molecular tools to characterize community diversity and have identified key processes useful for improving system performance. In this paper we summarize the current understanding of the microbial diversity and physiology of RAS biofilters and discuss directions for future studies. PMID:20371171

Schreier, Harold J; Mirzoyan, Natella; Saito, Keiko

2010-06-01

353

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

354

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

355

Dynamics of microorganism populations in recirculating nutrient solutions  

NASA Technical Reports Server (NTRS)

This overview covers the basic microbial ecology of recirculating hydroponic solutions. Examples from NASA and Soviet Controlled Ecological Life Support Systems (CELSS) tests and the commercial hydroponic industry will be used. The sources of microorganisms in nutrient solutions include air, water, seeds, plant containers and plumbing, biological vectors, and personnel. Microbial fates include growth, death, and emigration. Important microbial habitats within nutrient delivery systems are root surfaces, hardware surfaces (biofilms), and solution suspension. Numbers of bacteria on root surfaces usually exceed those from the other habitats by several orders of magnitude. Gram negative bacteria dominate the microflora with fungal counts usually much lower. Trends typically show a decrease in counts with increasing time unless stressed plants increase root exudates. Important microbial activities include carbon mineralization and nitrogen transformations. Important detrimental interactions include competition with plants, and human and plant pathogenesis.

Strayer, R. F.

1994-01-01

356

Dynamics of microorganism populations in recirculating nutrient solutions  

NASA Technical Reports Server (NTRS)

This overview covers the basic microbial ecology of recirculating hydroponic solutions. Examples from NASA and Soviet CELSS tests and the commercial hydroponic industry will be used. The sources of microorganisms in nutrient solutions include air, water, seeds, plant containers and plumbing, biological vectors, and personnel. Microbial fates include growth, death, and emigration. Important microbial habitats within nutrient delivery systems are root surfaces, hardware surfaces (biofilms), and solution suspension. Numbers of bacteria on root surfaces usually exceed those from the other habitats by several orders of magnitude. Gram negative bacteria dominate the microflora with fungal counts usually much lower. Trends typically show a decrease in counts with increasing time unless stressed plants increase root exudates. Important microbial activities include carbon mineralization and nitrogen transformations. Important detrimental interactions include competition with plants, and human and plant pathogenesis.

Strayer, R. F.

1994-01-01

357

Mean properties of mesoscale eddies in the Kuroshio recirculation region  

NASA Astrophysics Data System (ADS)

Using a 19-year altimetric dataset, the mean properties and spatiotemporal variations of eddies in the Kuroshio recirculation region are examined. A total of 2 001 cyclonic tracks and 1 847 anticyclonic tracks were identified using a geometry-based eddy detection method. The mean radius was 57 km for cyclonic eddies and was 61 km for anticyclonic eddies, respectively, and the mean lifetime was about 10 weeks for both type eddies. There were asymmetric spatial distributions for eddy generation and eddy termination, which were domain-dependent. Mean eddy generation rates were 2.0 per week for cyclonic eddies and were 1.9 per week for anticyclonic eddies. Both type eddies tended to deform during their lifetime and had different propagation characteristics, which mainly propagated westward and southwestward with velocities 4.0-9.9 cm/s, in the Kuroshio recirculation region. Further discussion illustrates that the eddy westward speed maybe influenced by the combined effect of vertical shear of horizontal currents and nonlinearity of eddy. To better understand the evolution of eddy tracks, a total of 134 long-lived tracks (lifetime ?20 weeks) were examined. Comparison between short-span eddies (lifetime ?4 weeks and <20 weeks) and long-lived eddies is also conducted and the result shows that the short-span and long-lived eddies have similar time evolution. Finally, eddy seasonal variations and interannual changes are discussed. Correlation analysis shows that eddy activity is sensitive to the wind stress curl and meridional gradient of sea surface temperature on interannual timescales. Besides, the strength and orientation of background flows also have impacts on the eddy genesis.

Ma, Libin; Wang, Qiang

2014-05-01

358

A five-year study of coastal recirculation and its effect on air pollutants over the East Mediterranean region  

Microsoft Academic Search

Many studies have shown that air pollutants concentrations in coastal cities may be gravely affected by coastal recirculation. In this study an attempt is made to examine the properties of coastal recirculation over a long period (5 yrs) at multiple sites along the East Mediterranean Sea (EMS). For this purpose, a single station quantitative measure of horizontal recirculation is used

Ilan Levy; Uri Dayan; Yitzhak Mahrer

2008-01-01

359

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

NASA Astrophysics Data System (ADS)

We explore with numerical simulations the range of conditions leading to key observed features of NVT in relation to SSE and earthquakes along the Guerrero segment of the Mexican subduction zone. The Guerrero segment is known to produce some of the largest slow slip events (SSE) recorded so far with equivalent magnitude up to 7.5 Mw. These SSE, with apparent durations of about 4 years, are accompanied by strong activity of Non Volcanic Tremor (NVT) in central Guerrero. Recently, NVT triggered by the 8.8 Mw Maule earthquake were also been reported in that region. The geometry of the Guerrero subduction zone remains sub-horizontal between 150 km to 250 km from the coast, making it easy to model with a simple flat frictional interface. We use a model with a planar interface governed by space-varying static/kinetic friction and dislocation creep in elastic solid. The model is tailored through the employed dimensions, distribution of rheological properties and boundary conditions to the Guerrero segment, with particular attention to conditions of the past 15 years for which observations are available. A section of the fault with zero weakening during frictional slip fails in a mode corresponding to a "critical depinning transition" that produces many observed features of NVT. When a high creep patch representing a section sustaining SSE is added, strong interactions between NVT and SSE are observed as in the natural fault system. We also examine triggering of NVT by larger remote earthquakes, implemented by adding periodic triggering oscillations to the regular tectonic loading. In addition to modeling observations of NVT and SSE made in Guerrero during the past 15 years, the simulations allow us to distinguish aspects of the observed behavior that are robust over long time intervals from aspects that change during intervals longer than the observational period.

Zigone, D.; Ben-Zion, Y.; Campillo, M.

2012-12-01

360

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.

361

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

362

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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.

363

Cascadia Subduction Zone  

USGS Publications Warehouse

The geometry and recurrence times of large earthquakes associated with the Cascadia Subduction Zone (CSZ) were discussed and debated at a March 28-29, 2006 Pacific Northwest workshop for the USGS National Seismic Hazard Maps. The CSZ is modeled from Cape Mendocino in California to Vancouver Island in British Columbia. We include the same geometry and weighting scheme as was used in the 2002 model (Frankel and others, 2002) based on thermal constraints (Fig. 1; Fluck and others, 1997 and a reexamination by Wang et al., 2003, Fig. 11, eastern edge of intermediate shading). This scheme includes four possibilities for the lower (eastern) limit of seismic rupture: the base of elastic zone (weight 0.1), the base of transition zone (weight 0.2), the midpoint of the transition zone (weight 0.2), and a model with a long north-south segment at 123.8? W in the southern and central portions of the CSZ, with a dogleg to the northwest in the northern portion of the zone (weight 0.5). The latter model was derived from the approximate average longitude of the contour of the 30 km depth of the CSZ as modeled by Fluck et al. (1997). A global study of the maximum depth of thrust earthquakes on subduction zones by Tichelaar and Ruff (1993) indicated maximum depths of about 40 km for most of the subduction zones studied, although the Mexican subduction zone had a maximum depth of about 25 km (R. LaForge, pers. comm., 2006). The recent inversion of GPS data by McCaffrey et al. (2007) shows a significant amount of coupling (a coupling factor of 0.2-0.3) as far east as 123.8? West in some portions of the CSZ. Both of these lines of evidence lend support to the model with a north-south segment at 123.8? W.

Frankel, Arthur D.; Petersen, Mark D.

2008-01-01

364

Impact of recirculation on the East Greenland Current in Fram Strait: Results from moored current meter measurements between 1997 and 2009  

NASA Astrophysics Data System (ADS)

Transports of total volume and water masses obtained from a mooring array in the East Greenland Current (EGC) in Fram Strait are presented for the period 1997-2009. The array in the EGC was moved along isobaths from 79°N to 78°50?N in 2002 to line up with moorings in the eastern Fram Strait. Analysis of the time series at the two latitudes shows that associated with the southward move, the annual mean volume transport of the EGC increased from 5.8±1.8 Sv to 8.7±2.5 Sv, mostly related with an increase in barotropic flow. This suggests a recirculation of close to 3 Sv at 78°50?N as a consequence of the large-scale wind-driven cyclonic gyre in the Nordic Seas. In addition, the volume transport at 78°50?N showed a clear seasonal cycle which was absent at 79°N. Estimates of the wind-driven Sverdrup transport at two different latitudes show that the difference in total volume transport and seasonality can largely be explained by the wind-stress curl. However, weak transport in 2003 was only partially related with weak Sverdrup transport and coincided also with anomalously weak northerly winds. The stronger recirculation at 78°50?N has also consequences for the observed Atlantic Water: there is significantly more Atlantic derived water present at the southerly latitude. In addition, the warm anomaly in Fram Strait between 2005 and 2007 doubled the amount of Recirculated Atlantic Water temporarily. Finally, we estimate that close to 2.7 Sv, or 50%, of Atlantic derived water recirculates in Fram Strait.

de Steur, L.; Hansen, E.; Mauritzen, C.; Beszczynska-Möller, A.; Fahrbach, E.

2014-10-01

365

Experimental Study of the Circulation Air Volume of Recirculation Evaporative Cooling  

E-print Network

This paper introduces the technology of re-circulation evaporative cooling (REC), which uses a portion of supply air as secondary air to make cool water used to indirectly cool outside air through a heat exchanger. The circulation volume...

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

2006-01-01

366

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

367

Ozone (o3) efficacy on reduction of phytophthora capsici in recirculated horticultural irrigation water  

E-print Network

Microorganisms that cause plant disease have been isolated in recirculated irrigation water and increase the risks of disease incidence in horticultural operations. Ozone is an effective oxidizer used to disinfect drinking water supplies and treat...

McDonald, Garry Vernon

2009-05-15

368

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

369

Halogen compatible treatment programs for open recirculating cooling water systems  

SciTech Connect

Stabilized phosphate cooling water programs have been exceptionally effective and well established in the marketplace for close to twenty years. Identification of this technology allowed chromate to be eliminated from open recirculating systems, providing less toxic operating conditions. However, very good control of stabilized phosphate applications is necessary in order to ensure chrome-like corrosion and deposit control performance. Difficulties with stabilized phosphate technology have occurred when it is used along with chlorine. Elevated chlorine dosages are sometimes necessary for microbial control. When this occurs, copper induced pitting becomes a concern as does the degradation of the cooling water program itself, i.e. phosphonate reversion. New programs have been identified which maintain their component integrity in the presence of chlorine. They offer improved deposit control performance under a variety of stressed cooling water conditions by using select polymer blends, as opposed to a single polymer. They also incorporate a new azole corrosion inhibition chemistry which minimizes copper-induced pitting associated with over-chlorination. Laboratory and field experience with this technology is discussed.

Kessler, S.M.; Given, K.M.

1999-07-01

370

Design of a computerized, temperature-controlled, recirculating aquaria system  

USGS Publications Warehouse

We built a recirculating aquaria system with computerized temperature control to maintain static temperatures, increase temperatures 1 ??C/day, and maintain diel temperature fluctuations up to 10 ??C. A LabVIEW program compared the temperature recorded by thermocouples in fish tanks to a desired set temperature and then calculated the amount of hot or cold water to add to tanks to reach or maintain the desired temperature. Intellifaucet?? three-way mixing valves controlled temperature of the input water and ensured that all fish tanks had the same turnover rate. The system was analyzed over a period of 50 days and was fully functional for 96% of that time. Six different temperature treatments were run simultaneously in 18, 72 L fish tanks and temperatures stayed within 0.5 ??C of set temperature. We used the system to determine the upper temperature tolerance of fishes, but it could be used in aquaculture, ecological studies, or other aquatic work where temperature control is required. ?? 2005 Elsevier B.V. All rights reserved.

Widmer, A.M.; Carveth, C.J.; Keffler, J.W.; Bonar, S.A.

2006-01-01

371

AMTEC recirculating test cell component testing and operation  

NASA Technical Reports Server (NTRS)

Alkali metal thermoelectric converter operation in a recirculating test cell (RTC), which requires a small electromagnetic pump (EM) and a high-temperature beta-double-prime alumina-solid-electrolyte (BASE)-to-metal seal, is discussed. The design of a pump and an active metal braze seal and the initial operation of a cell using these components are described. The pump delivered 0.25 cu cm/min against a 28-psia head. A braze seal system was selected after shear strength tests of Ta or Nb brazed to BASE by a variety of fillers including TiCuNi, TiNi, and TiNiCr. The TiCuNi filler was chosen for environment cell testing and showed no failure or observable degradation after short-term tests up to 1055 K. The pump and the Nb/TiCuNi/BASE seal were used in a test that demonstrated all the operational functions of the RTC for the first time. An increase in the radiation reduction factor at constant input power was observed, indicating that the condenser was being wet by sodium resulting in an increased reflectivity.

Underwood, M. L.; Sievers, R. K.; O'Connor, D.; Williams, R. M.; Jeffries-Nakamura, B.; Bankston, C. P.

1989-01-01

372

Efficiency of an AMTEC recirculating test cell, experiments and projections  

SciTech Connect

The alkali metal thermal to electric converter (AMTEC) is an electrochemical device for the direct conversion of heat to electrical energy with efficiencies potentially near Carnot. The future usefulness of AMTEC for space power conversion depends on the efficiency of the devices. Systems studies have projected from 15% to 35% thermal to electric conversion efficiencies, and one experiment has demonstrated 19% efficiency for a short period of time. Recent experiments in a recirculating test cell (RTC) have demonstrated sustained conversion efficiencies as high as 10.2% early in cell life and 9.7% after maturity. Extensive thermal and electrochemical analysis of the cell during several experiments demonstrated that the efficiency could be improved in two ways. First, the electrode performance could be improved. The electrode for these tests operated at about one third the power density of state of the art electrodes. The low power density was caused by a combination of high series resistance and high mass flow resistance. Reducing these resistances could improve the efficiency to greater than 10%. Second, the cell thermal performance could be improved. Efficiencies greater than 14% could be realized through reducing the radiative thermal loss. Further improvements to the efficiency range predicted by systems studies can be accomplished through the development and use of an advanced condenser with improved reflectivity, close to that of a smooth sodium film, and the series connecting of individual cells to further reduce thermal losses.

Underwood, M.L.; O`Connor, D.; Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.

1992-05-01

373

Improvement of Waste Decomposition in Leachate Recirculation Simulated Landfill by High Water Addition  

Microsoft Academic Search

A considerable amount of research has been conducted to demonstrate the development of bioreactor landfills promoted by leachate recirculation (1-10). The effectiveness of leachate recirculation has been well documented in lysimeter studies (1, 5, 11, 12), test cell studies (2, 13, 14-16) and full-scale studies (17-20). However, the results from these investigations might not be applied appropriately to Thailand

N. Sanphoti; S. Towprayoon; P. Chaiprasert; A. Nopharatana

374

Long term\\/low dose formalin exposure to small-scale recirculation aquaculture systems  

Microsoft Academic Search

Repetitive long term formalin application at low dose was investigated to determine the effect on formaldehyde removal rate, biofilter nitrification and the microbial composition in small-scale recirculation aquaculture biofilters. Six pilot-scale recirculation aquaculture systems holding rainbow trout (Oncorhynchus mykiss) were designated to formalin treatments (C0 at 10 and 20mg\\/L formaldehyde) on a daily or weekly basis. Formaldehyde removal rates were

Lars-Flemming Pedersen; Per B. Pedersen; Jeppe L. Nielsen; Per H. Nielsen

2010-01-01

375

Modeling gas transfer and biological respiration in a recirculating aquaculture system  

Microsoft Academic Search

Recirculating aquaculture system applications of oxygen absorption equipment require consideration of the combined effects of the system's physical, chemical and biological components. Interactions of this type were modeled within a recirculating system incorporating a mixed-flow type rearing vessel, a multi-tube clarifier, a rotating biological contactor (RBC) and a U-tube oxygenator. Finite difference mass transfer calculations, based on reactor theory, were

Luther G. Wood; Barnaby J. Watten; C. Gene Haugh; George S. Libey; Theo A. Dillaha

1996-01-01

376

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

377

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

E-print Network

: C vin B. Parnell, Jr. (Chair of Committee) -Albert arcta III (Member) Stephen W. Fuller (Member) Don . R de 1 (Head of Department) December 1992 ABSTRACT Grain Quality Impacts of Prohibiting Recombination Recirculation Dust at Export Grain...: C vin B. Parnell, Jr. (Chair of Committee) -Albert arcta III (Member) Stephen W. Fuller (Member) Don . R de 1 (Head of Department) December 1992 ABSTRACT Grain Quality Impacts of Prohibiting Recombination Recirculation Dust at Export Grain...

Spillmann, Daryl Drew

2012-06-07

378

A Semiclosed Recirculating-Water System for High-Density Culture of Rainbow Trout  

Microsoft Academic Search

Water recirculating systems for fish culture are potentially desirable for conserving water and reducing heating requirements, maximizing production of fish under water and space limitations, minimizing effluent problems, and maintaining better control over environmental factors. A semiclosed recirculating-water system for intensive culture of rainbow trout Oncorhynchus mykiss is described. The system used self-cleaning, rectangular, cross-flow rearing tanks (water volume, 9

John M. Heinen; Joseph A. Hankins; Amy L. Weber; Barnaby J. Watten

1996-01-01

379

Final cooling of coke oven gas using a closed-loop, recirculated wash-water system  

Microsoft Academic Search

Bethlehem Steel Corporation has developed a closed-loop, recirculated wash-water system for the final cooling of coke oven gas streams. The system employs physical separation of suspended solids from the cooling water, indirect cooling of the recirculating water, and injection of a small amount of a water-immiscible solvent to minimise the deposition of naphthalenic solids in the indirect heat exchanger. A

R. E. Watkins; K. R. Burcaw

1983-01-01

380

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

381

Marginal zone B cells transport IgG3-immune complexes to splenic follicles.  

PubMed

Ag administered together with specific IgG3 induces a higher Ab response than Ag administered alone, an effect requiring the presence of complement receptors 1 and 2 (CR1/2). In this study, we have investigated the fate of Ag, the development of germinal centers (GCs), and the Ab response after i.v. administration of IgG3 anti-trinitrophenyl (TNP) in complex with OVA-TNP. After 2 h, OVA-TNP was detected on marginal zone (MZ) B cells, and a substantial amount of Ag was detected in splenic follicles and colocalized with follicular dendritic cells (FDCs). After 10 d, the percentage of GCs and the IgG responses were markedly higher than in mice immunized with uncomplexed OVA-TNP. The effects of IgG3 were dependent on CR1/2 known to be expressed on B cells and FDCs. Using bone marrow chimeric mice, we demonstrate that an optimal response to IgG3-Ag complexes requires that CR1/2 is expressed on both cell types. These data suggest that CR1/2(+) MZ B cells transport IgG3-Ag-C complexes from the MZ to the follicles, where they are captured by FDCs and induce GCs and IgG production. This pathway for initiating the transport of Ags into splenic follicles complements previously known B-cell dependent pathways where Ag is transported by 1) MZ B cells, binding large Ags-IgM-C complexes via CR1/2; 2) recirculating B cells, binding Ag via BCR; or 3) recirculating B cells, binding IgE-Ag complexes via the low-affinity receptor for IgE, CD23. PMID:25015822

Zhang, Lu; Ding, Zhoujie; Xu, Hui; Heyman, Birgitta

2014-08-15

382

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

383

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

384

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

385

Energy stability in recirculating, energy-recovering linacs in the presence of a FEL  

SciTech Connect

Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs (free electron lasers). Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M{sub 56}, phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. An analytical model which includes amplitude and phase feedback, has been developed to study the stability of the system for small perturbations from equilibrium. The interaction of the electron beam with the FEL is a major perturbation which affects both the stability of the system and development of startup and recovery scenarios. To simulate the system`s response to such large parameter variations, a numerical model of the beam-cavity interaction has been developed which includes low level rf feedback, phase oscillations and beam loss instabilities and the FEL interaction. Agreement between the numerical model and the linear theory has been demonstrated in the limit of small perturbations. In addition, the model has been benchmarked against experimental data obtained during CEBAF`s high current operation. Numerical simulations have been performed for the high power IR DEMO approved for construction at CEBAF.

Merminga, L.; Bisognano, J.; Delayen, J.R. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

1996-07-01

386

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

387

Passive sampler used for simultaneous measurement of breathing zone size distribution, inhalable dust concentration and other size fractions involving large particles.  

PubMed

The particle size-dependent sampling velocity of the passive dust sampler developed by Vinzents (1996) is investigated under field conditions. Microscopical determination of the projected area equivalent diameter is used to quantify particles deposited on the sampler foils. Parameters for a semi-empirical model for particle deposition velocities on upward and forward facing foils are fitted to the data and it is shown that deposition mechanisms other than gravitational settling on the upward facing foil can be neglected. For calculation of airborne mass concentration no information on particle density is needed and only the ratio between the dynamic and volume shape factors needs to be known. Given the sampling velocity, the airborne mass per diameter interval is calculated from samples obtained in the wood industry, from which inhalable dust concentrations are calculated. The results are in line with parallel samples obtained with an inhalable dust sampler. A 'total' dust sampling characteristic can be fitted which reproduces measured 'total' dust with a closed face monitor. The results of this study demonstrate the validity of the passive dust sampling principle in environments involving even large (>100 microm) particles and the potential to predict the concentration of several size fractions. PMID:12074028

Schneider, T; Schlünssen, V; Vinzents, P S; Kildesø, J

2002-03-01

388

Formation and erosion of the seasonal thermocline in the Kuroshio Extension Recirculation Gyre  

NASA Astrophysics Data System (ADS)

Data from the Kuroshio Extension Observatory (KEO) surface mooring are used to analyze the balance of processes affecting the upper ocean heat content and surface mixed layer temperature variations in the Recirculation Gyre (RG) south of the Kuroshio Extension (KE). Cold and dry air blowing across the KE and its warm RG during winter cause very large heat fluxes out of the ocean that result in the erosion of the seasonal thermocline in the RG. Some of this heat is replenished through horizontal heat advection, which may enable the seasonal thermocline to begin restratifying while the net surface heat flux is still acting to cool the upper ocean. Once the surface heat flux begins warming the ocean, restratification occurs rapidly due to the low thermal inertia of the shallow mixed layer depth. Enhanced diffusive mixing below the mixed layer tends to transfer some of the mixed layer heat downward, eroding and potentially modifying sequestered subtropical mode water and even the deeper waters of the main thermocline during winter. Diffusivity at the base of the mixed layer, estimated from the residual of the mixed layer temperature balance, is roughly 3×10-4 m2/s during the summer and up to two orders of magnitude larger during winter. The enhanced diffusivities appear to be due to large inertial shear generated by wind events associated with winter storms and summer tropical cyclones. The diffusivity's seasonality is likely due to seasonal variations in stratification just below the mixed layer depth, which is large during the summer when the seasonal thermocline is fully developed and low during the winter when the mixed layer extends to the top of the thermocline.

Cronin, Meghan F.; Bond, Nicholas A.; Thomas Farrar, J.; Ichikawa, Hiroshi; Jayne, Steven R.; Kawai, Yoshimi; Konda, Masanori; Qiu, Bo; Rainville, Luc; Tomita, Hiroyuki

2013-01-01

389

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

390

Diversity and Phylogenetic Affiliations of Morphologically Conspicuous Large Filamentous Bacteria Occurring in the Pelagic Zones of a Broad Spectrum of Freshwater Habitats  

PubMed Central

Filamentous bacteria with a conspicuous morphology were found in the majority of the bacterioplankton samples from a variety of freshwater habitats that were studied. These heterotrophic filaments typically account for <1 to 11% of the total number of bacteria. The biovolume of this morphotype can exceed 40% of the biovolume for all bacteria. Surprisingly, we found hardly any data on these morphologically conspicuous filaments in the literature. Mixed cultures containing these filamentous bacteria were established by cultivation and isolation experiments with samples from different freshwater lakes. Nearly full-length 16S rRNA gene sequences were obtained from several mixed cultures and environmental samples from habitats in Europe, Africa, China, Australia, and New Zealand. Phylogenetic analysis of the sequences showed that three groups form a single monophyletic cluster, the SOL cluster, in the family Saprospiraceae. We developed a set of six nested probes for fluorescence in situ hybridization. Of the six probes, one probe was specific for Haliscomenobacter hydrossis, three probes were specific for the three subclusters (each probe was specific for one subcluster), one probe was specific for the entire SOL cluster, and another probe targeted almost the entire Saprospiraceae family. Specific hybridization of environmental samples and enrichments showed that the members of the three subclusters exhibited the same filamentous morphology. So far, using the subcluster-specific probes, we have not been able to detect any bacteria with a differing morphology. We conclude that the SOL cluster bacteria are an integral part of bacterioplankton in many freshwater habitats. They potentially account for a large fraction of the total bacterial biomass but have been underrepresented in molecular diversity studies so far. PMID:15812022

Schauer, Michael; Hahn, Martin W.

2005-01-01

391

Earthquake hazards on the cascadia subduction zone  

Microsoft Academic Search

Large subduction earthquakes on the Cascadia subduction zone pose a potential seismic hazard. Very young oceanic lithosphere (10 million years old) is being subducted beneath North America at a rate of approximately 4 centimeters per year. The Cascadia subduction zone shares many characteristics with subduction zones in southern Chile, southwestern Japan, and Colombia, where comparably young oceanic lithosphere is also

T. H. Heaton; S. H. Hartzell

1987-01-01

392

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

393

The chemistry of a new water-recirculation aquaculture system with emphasis on the influence of ozone on water quality.  

E-print Network

??Water quality changes that occur during establishment and maintenance of nitrification in two identical recirculating aquaculture systems containing rainbow trout are described. The time taken… (more)

Stobart, Michael David

1992-01-01

394

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

395

Enhancement of denitrification in a down-flow hanging sponge reactor by effluent recirculation.  

PubMed

A down-flow hanging sponge reactor, constructed by connecting three identical units in series, was applied to the treatment of artificial wastewater containing phenol and ammonia under high salinity conditions (10.9 g-Cl(-)/L). The theoretical hydraulic retention time (HRT) of each unit was 4 h (total HRT = 12 h). To enhance denitrification by effluent recirculation, the effluent recirculation ratio was increased in increments ranging from 0.0 to 2.0. The concentration of total ammonia nitrogen (TAN), NO2-N, and NO3-N in the final effluent as a proportion of the TAN in the influent was determined to calculate the unrecovered, or denitrification, proportion. The denitrification proportion of the reactor was equivalent to 19.1 ± 14.1% with no effluent recirculation; however, this was increased to 58.6 ± 6.2% when the effluent recirculation ratio was increased to 1.5. Further increasing the effluent recirculation ratio to 2.0 resulted in a decrease in the denitrification proportion to 50.9 ± 9.3%. Activity assays of nitrification and denitrification, as well as 16S rRNA gene sequence analysis, revealed that denitrification occurred primarily in the upper sections of the reactor, while nitrification increased in the lower sections of the reactor. Gene sequence analysis revealed that denitrification by Azoarcus-like species using phenol as an electron donor was dominant. PMID:23925187

Ikeda, N; Natori, T; Okubo, T; Sugo, A; Aoki, M; Kimura, M; Yamaguchi, T; Harada, H; Ohashi, A; Uemura, S

2013-01-01

396

Low NOx Combustion of DME by Means of Flue Gas Recirculation  

NASA Astrophysics Data System (ADS)

This study focuses on the fundamental characteristics of DME (Dimethyl Ether) combustion aiming at development of low-NOx combustion technology with flue gas recirculation, FGR. The flue gas is recirculated into the combustion chamber to reduce the oxygen concentration and to suppress the combustion gas temperature, so that NOx emission is significantly reduced. The fuel gas recirculation at high mixing ratio, however, may lead to unstable combustion of conventional fuels, methane or city gas. On the other hand, DME has very high potential of applicability for the flue gas recirculation even at high mixing ratio because of its high burning velocity and low ignition temperature. Combustion tests were conducted with laboratory-scale 11kW combustor. The maximum FGR ratio is 85% at the initial air ratio of 1.5 with preheated diluted air about 600K. The NOx emission reduced to 13ppm at 0%-O2, which corresponds to about 9% of NOx emission at FGR=0%. The stable combustion is sustained even in the low oxygen concentration by preheating diluted-air up to near the auto-ignition temperature of DME. Finally, the effect of the flue gas recirculation on the NOx and CO emission is discussed with reference to the industrial-scale water-tube boilers.

Matsumoto, Ryosuke; Ozawa, Mamoru; Terada, Shinya; Iio, Takenori

397

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

398

Impact of Exhaust Gas Recirculation on the Performances of Diesel Engine  

E-print Network

“Worldwide emission regulation has been tightening year after year. Numbers of researchers are trying to work out combinations of key technologies to meet the forth-coming emission norms. Exhaust gas recirculation (EGR) for diesel engine to reduce oxides of nitrogen is chosen for present work. The emphasis is given on oxides of nitrogen (NOx). Experiments were carried out on computerized single cylinder four- stroke diesel engine with eddy current dynamometer (10 BHP 7.4 KW).” “Exhaust gas re-circulation set-up is developed. It consists of EGR cooler; air filters box, rota-meter, exhaust control valve, pressure gauge and temperature indicator etc. Engine set-up was modified and coupled with EGR setup. Exhaust gas recirculation system was tested with different EGR

P. V. Walke; Dr. N. V. Deshp; R. G. Bodkhe

399

Controlled reattachment in separated flows: a variational approach to recirculation length reduction  

E-print Network

A variational technique is used to derive analytical expressions for the sensitivity of recirculation length to steady forcing in separated flows. Linear sensitivity analysis is applied to the two-dimensional steady flow past a circular cylinder for Reynolds numbers $40 \\leq Re \\leq 120$, both in the subcritical and supercritical regimes. Regions which are the most sensitive to volume forcing and wall blowing/suction are identified. Control configurations which reduce the recirculation length are designed based on the sensitivity information, in particular small cylinders used as control devices in the wake of the main cylinder, and fluid suction at the cylinder wall. Validation against full non-linear Navier-Stokes calculations shows excellent agreement for small-amplitude control. The linear stability properties of the controlled flow are systematically investigated. At moderate Reynolds numbers, we observe that regions where control reduces the recirculation length correspond to regions where it has a stab...

Boujo, E

2014-01-01

400

Final cooling of coke oven gas using a closed-loop, recirculated wash-water system  

SciTech Connect

Bethlehem Steel Corporation has developed a closed-loop, recirculated wash-water system for the final cooling of coke oven gas streams. The system employs physical separation of suspended solids from the cooling water, indirect cooling of the recirculating water, and injection of a small amount of a water-immiscible solvent to minimise the deposition of naphthalenic solids in the indirect heat exchanger. A process patent (US Patent 4.234.389) has been awarded to Bethlehem for the solvent-injection portion of the process. Based on the results of plant trials, the system has been proven to require less capital investment and to be more economical and more reliable to operate than the standard recirculated wash-oil systems. When compared with existing wash-water systems, the system has the advantage of eliminating the atmospheric discharges associated with open cooling towers.

Watkins, R.E.; Burcaw, K.R.

1983-01-01

401

Four-Nozzle Benchmark Wind Tunnel Model USA Code Solutions for Simulation of Multiple Rocket Base Flow Recirculation at 145,000 Feet Altitude  

NASA Technical Reports Server (NTRS)

Multiple rocket exhaust plume interactions at high altitudes can produce base flow recirculation with attendant alteration of the base pressure coefficient and increased base heating. A search for a good wind tunnel benchmark problem to check grid clustering technique and turbulence modeling turned up the experiment done at AEDC in 1961 by Goethert and Matz on a 4.25-in. diameter domed missile base model with four rocket nozzles. This wind tunnel model with varied external bleed air flow for the base flow wake produced measured p/p(sub ref) at the center of the base as high as 3.3 due to plume flow recirculation back onto the base. At that time in 1961, relatively inexpensive experimentation with air at gamma = 1.4 and nozzle A(sub e)/A of 10.6 and theta(sub n) = 7.55 deg with P(sub c) = 155 psia simulated a LO2/LH2 rocket exhaust plume with gamma = 1.20, A(sub e)/A of 78 and P(sub c) about 1,000 psia. An array of base pressure taps on the aft dome gave a clear measurement of the plume recirculation effects at p(infinity) = 4.76 psfa corresponding to 145,000 ft altitude. Our CFD computations of the flow field with direct comparison of computed-versus-measured base pressure distribution (across the dome) provide detailed information on velocities and particle traces as well eddy viscosity in the base and nozzle region. The solution was obtained using a six-zone mesh with 284,000 grid points for one quadrant taking advantage of symmetry. Results are compared using a zero-equation algebraic and a one-equation pointwise R(sub t) turbulence model (work in progress). Good agreement with the experimental pressure data was obtained with both; and this benchmark showed the importance of: (1) proper grid clustering and (2) proper choice of turbulence modeling for rocket plume problems/recirculation at high altitude.

Dougherty, N. S.; Johnson, S. L.

1993-01-01

402

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

403

2001 TRAFFIC ZONE BOUNDARIES Zone Numbers  

E-print Network

TTS. It has been customised for the 2001 TTS data. The 2001 traffic zones are similar to the 1996 GTA zones. Within the GTA, minor modifications have been made to the zones in the City of Toronto, Peel.............................................................................A1 2001 Traffic Zones Region in GTA

Toronto, University of

404

Exhaust gas recirculation system in compression-ignition internal combustion engine  

SciTech Connect

In an exhaust gas recirculation system of a compression ignition internal combustion engine, there are provided two passages, that is, an EGR passage for recirculation of exhaust gases and a bypass passage by-passing the throttle valve in the induction passage to allow a supplemental air flow to the engine when EGR is cut off in definite engine operating conditions. These two passages are arranged to join together at a junction, in which there is provided a valve to open and close these two passages alternatively so that an adequate egr control is performed in accordance with engine operating conditions with a simplified mechanism.

Shinzawa, M.

1982-02-02

405

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

406

Un formalisme de systemes a sauts pour la recirculation optimale des casses dans une machine a papier  

NASA Astrophysics Data System (ADS)

Increasing closure of white water circuits is making mill productivity and quality of paper produced increasingly affected by the occurrence of paper breaks. In this thesis the main objective is the development of white water and broke recirculation policies. The thesis consists of three main parts, respectively corresponding to the synthesis of a statistical model of paper breaks in a paper mill, the basic mathematical setup for the formulation of white water and broke recirculation policies in the mill as a jump linear quadratic regulation problem, and finally the tuning of the control law based on first passage-time theory, and its extension to the case of control sensitive paper break rates. More specifically, in the first part a statistical model of paper machine breaks is developed. We start from the hypothesis that the breaks process is a Markov chain with three states: the first state is the operational one, while the two others are associated with the general types of paper-breaks that can take place in the mill (wet breaks and dry breaks). The Markovian hypothesis is empirically validated. We also establish how paper-break rates are correlated with machine speed and broke recirculation ratio. Subsequently, we show how the obtained Markov chain model of paper-breaks can be used to formulate a machine operating speed parameter optimization problem. In the second part, upon recognizing that paper breaks can be modelled as a Markov chain type of process which, when interacting with the continuous mill dynamics, yields a jump Markov model, jump linear theory is proposed as a means of constructing white water and broke recirculation strategies which minimize process variability. Reduced process variability comes at the expense of relatively large swings in white water and broke tanks level. Since the linear design does not specifically account for constraints on the state-space, under the resulting law, damaging events of tank overflow or emptiness can occur. A heuristic simulation-based approach is proposed to choose the performance measure design parameters to keep the mean time between incidents of fluid in broke and white water tanks either overflowing, or reaching dangerously low levels, sufficiently long. In the third part, a methodology, mainly founded on the first passage-time theory of stochastic processes, is proposed to choose the performance measure design parameters to limit process variability while accounting for the possibility of undesirable tank overflows or tank emptiness. The heart of the approach is an approximation technique for evaluating mean first passage-times of the controlled tanks levels. This technique appears to have an applicability which largely exceeds the problem area it was designed for. Furthermore, the introduction of control sensitive break rates and the analysis of the ensuing control problem are presented. This is to account for the experimentally observed increase in breaks concomitant with flow rate variability.

Khanbaghi, Maryam

407

Earthquake hazards on the Cascadia subduction zone  

Microsoft Academic Search

Large subjection earthquakes on the Cascadia subduction zone pose a potential seismic hazard. Very young oceanic lithosphere (10 million years old) is being subducted beneath North America at a rate of approximately 4 cm per year. Very large subduction earthquakes, ranging in energy magnitude M(w) between 8 and 9.5 have occurred along these other subduction zones. If the Cascadia subjection

Thomas H. Heaton; Stephen H. Hartzell

1987-01-01

408

Breathing of a coral cay: Tracing tidally driven seawater recirculation in permeable coral reef sediments  

NASA Astrophysics Data System (ADS)

Coral reefs are characterized by high gross productivity in spite of low nutrient concentrations. This apparent paradox may be partially reconciled if seawater recirculation in permeable sediments over large (meters) and long (hours to days) scales is an important source of recycled nitrogen and phosphorus to coral reefs. In this paper we use radon (222Rn, a natural tracer) to quantify tidally driven pore water (or groundwater) exchange between (1) an offshore coral cay island and its fringing reef lagoon and (2) a reef lagoon and the surrounding ocean. As seawater infiltrates Heron Island at high tide, it acquires a radon signal that can be detected when pore waters emerge from carbonate sands at low tide. A nonsteady state model indicated that vertical pore water upwelling rates (or saline submarine groundwater discharge) were >40 cm/d within the reef lagoon and >100 cm/d outside the lagoon at low tide. Within the lagoon, tidal pumping and temperature-driven convection were the main driving forces of pore water advection. At low tide, the reef lagoon level is about 1 m higher than the surrounding ocean. As a result, a steep hydraulic gradient develops at the reef edge, driving unidirectional filtration through the reef framework. Groundwaters were highly enriched in nitrate (average of 530 ?mol, likely influenced by bird guano) relative to lagoon waters (1.9 ?mol). Rough but conservative estimates indicated that groundwater-derived nitrate fluxes (7.9 mmol/m2/d) can replace the entire lagoon nitrate inventory every <19 days. We speculate that as offshore coral islands "breath" (inhale seawater at high tide and exhale groundwater at low tide), they release nutrients that lead to sustained productivity within coral reefs.

Santos, Isaac R.; Erler, Dirk; Tait, Douglas; Eyre, Bradley D.

2010-12-01

409

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

410

Control of a turbocharged Diesel engine fitted with high pressure and low pressure exhaust gas recirculation systems  

Microsoft Academic Search

Exhaust gas recirculation is an effective way for reducing nitric oxides emissions in Diesel engine achieving low temperature combustion (LTC). Two strategies can be applied to recirculate burnt gas in a turbocharged Diesel engine using the high pressure loop or the low pressure loop. This paper describes a generic model based control structure for Diesel engines with dual-loop exhaust gas

Olivier Grondin; Philippe Moulin; Jonathan Chauvin

2009-01-01

411

Observer design of critical states for air path flow regulation in a variable geometry turbocharger exhaust gas recirculation diesel engine  

Microsoft Academic Search

Modern automotive diesel engines rely on control strategies that must optimally manage the flows of fresh air and recirculated exhaust gas to achieve the best trade-off between torque demand and engine out emissions. An important aspect of the gas exchange regulation problem is the complex interaction between the variable geometry turbocharger (VGT) and the exhaust gas recirculation (EGR) valve and

B C Glenn; D Upadhyay; V I Utkin; G N Washington; M B Hopka

2011-01-01

412

NO x emission characteristics and aerodynamic structure of a self-recirculation type burner for small boilers  

Microsoft Academic Search

To meet the coming, more stringent NOx emission standards for small boilers, a self-recirculation type burner, in which a fresh air is injected through eight nozzles, arrayed peripherally around a liquid fuel-spray nozzle, while the hot burned gas is recirculated within the furnace and entrained into the injected air streams has been experimentally investigated. The flowfield has been determined with

Kenichi Shinomori; Kousuke Katou; Daisuke Shimokuri; Satoru Ishizuka

2011-01-01

413

Intake manifold for internal combustion engine having exhaust gas recirculation system  

Microsoft Academic Search

An intake manifold is described of an internal combustion engine which has an exhaust gas recirculation system. It introduces a part of exhaust gas from an exhaust passage through an EGR gas supply passage into the intake manifold. The intake manifold is provided with an EGR gas outlet opened thereto and connected to the EGR gas supply passage. The EGR

T. Yokoi; E. Takeya; K. Hattori; K. Abe; H. Osawa

1987-01-01

414

Exhaust gas recirculation system with control apparatus for exhaust gas flow control valve  

Microsoft Academic Search

An exhaust gas recirculation system for an internal combustion engine comprises an exhaust gas flow control valve; a vacuum actuator for operation of the flow control valve; and a control apparatus which provides an output vacuum to be applied to the vacuum actuator which is an amplification of the venturi vacuum.

Y. Nakajima; Y. Hayashi; Y. Takagi; K. Sugihara; S. Aoyama

1977-01-01

415

Findings from long-term monitoring studies at MSW landfill facilities with leachate recirculation.  

PubMed

This paper presents findings from long-term monitoring studies performed at full-scale municipal solid waste landfill facilities with leachate recirculation. Data from two facilities at a landfill site in Delaware, USA were evaluated as part of this study: (1) Area A/B landfill cells; and (2) two test cells (one with leachate recirculation and one control cell). Data from Area A/B were compared with proposed waste stability criteria for leachate quality, landfill gas production, and landfill settlement. Data from the test cells were directly compared with each other. Overall, the trends at Area A/B pointed to the positive effects (i.e., more rapid waste degradation) that may be realized through increasing moisture availability in a landfill relative to the reported behavior of more traditionally operated (i.e., drier) landfills. Some significant behavioral differences between the two test cells were evident, including dissimilarities in total landfill gas production quantity and the extent of waste degradation observed in recovered time capsules. Differences in leachate quality were not as dramatic as anticipated, probably because the efficiency of the leachate recirculation system at distributing leachate throughout the waste body in the recirculation cell was low. PMID:12957160

Morris, J W F; Vasuki, N C; Baker, J A; Pendleton, C H

2003-01-01

416

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

Microsoft Academic Search

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 (3Å+4Å). 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

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

417

Exhaust gas recirculation system with control apparatus for exhaust gas flow control valve  

Microsoft Academic Search

An exhaust gas recirculation system comprises an exhaust gas flow control valve; a vacuum actuator for operation of the flow control valve; and a control apparatus for the vacuum actuator. The control apparatus comprises a vacuum regulator and a vacuum motor for actuating the vacuum regulator in response not only to the venturi vacuum but also to the intake manifold

K. Sugihara; Y. Nakajima; Y. Hayashi

1977-01-01

418

Exhaust gas recirculation system with control apparatus for exhaust gas flow control valve  

Microsoft Academic Search

An exhaust gas recirculation system comprises an exhaust gas flow control valve; a vacuum actuator for operation of the flow control valve; and a control apparatus constructed and arranged such that an output vacuum of the control apparatus applied to the vacuum actuator is an amplification of the venturi vacuum modified by the intake manifold vacuum.

Y. Hayashi; Y. Nakajima; K. Sugihara; S. Nagumo

1977-01-01

419

Intake manifold for internal combustion engine having exhaust gas recirculation system  

Microsoft Academic Search

An intake manifold is described for an internal combustion engine equipped with an exhaust gas recirculation system for introducing a part of the exhaust from an exhaust gas passage through an EGR pipe into an intake manifold. The intake manifold is provided with an EGR gas outlet port opened thereto and connected to the EGR pipe, and is also provided

Y. Noguchi; T. Yokoi; E. Takeya; H. Osawa

1987-01-01

420

Multiple trophic levels fueled by recirculation in the Columbia River plume  

E-print Network

positively and negatively impacted by physical retention mechanisms occurring at multiple scales. These include 1 day recirculation in the tidal plume formed on every ebb; 3­4 day retention within in the Pacific Northwest [Naik and Jay, 2005]. At times, it serves as a moderate source of nutrients

Kurapov, Alexander

421

A population pharmacokinetic model that describes multiple peaks due to enterohepatic recirculation of ezetimibe  

Microsoft Academic Search

Background: Ezetimibe, a selective inhibitor of intestinal cholesterol absorption, is in clinical development for the treatment of hypercholesterolemia. It is rapidly absorbed and glucuronidated in the intestine. The parent compound and its conjugated metabolite undergo enterohepatic recirculation, resulting in multiple peaks in the plasma concentration-time profile.Objective: The purpose of this study was to develop a population pharmacokinetic (PPK) model for

Farkad Ezzet; Gopal Krishna; David B. Wexler; Paul Statkevich; Teddy Kosoglou; Vijay K. Batra

2001-01-01

422

Use of Hydroponics to Maintain Quality of Recirculated Water in a Fish Culture System  

Microsoft Academic Search

Fish production, biofiltration, and hydroponics were linked in a closed system of recirculating water. Fish tanks were stocked with channel catfish (Ictalurus punctatus) and the fish were fed daily. A revolving plate-type biofilter was used. Three field varieties of tomatoes (Lycopericon esculentum) were planted in outdoor hydroponic tanks. Three production units were operated during the 1976 growing season. All significant

William M. Lewis; John H. Yopp; Harold L. Schramm JR; Alan M. Brandenburg

1978-01-01

423

Stress corrosion cracking of stainless steels recommended for building brine recirculation pumps  

Microsoft Academic Search

In earlier works, characterization and stress corrosion cracking (SCC) of casings of brine recirculation pumps, used in desalination plants, had been investigated. These casings which were manufactured from two types of Ni resist ductile irons have been reported to show different service lives. Material selection is believed to be one of possible factors to extend the service life of these

A. I. Aljoboury; A.-H. I. Mourad; A. Alawar; M. Abou Zour; O. A. Abuzeid

2010-01-01

424

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

E-print Network

preventative medicine principles and explains purpose-built recirculat- ing systems for different uses. Part 3 with suppressed immune systems. However, if pathogens become suf- ficiently numerous they can also cause Cir 121 Fish Health Management Considerations in Recirculating Aquaculture Systems - Part 2

Watson, Craig A.

425

Energization and anisotropization of energetic electrons in the earth's radiation belt by the recirculation process  

Microsoft Academic Search

Energetic electrons with energies above 1 MeV have been observed to become harder and to develop the dumbbell-type anisotropy a few days after the injection in the trapping region (Baker et al., 1989). A Monte Carlo simulation has been carried out to see if these features can be explained by the recirculation process which was originally proposed to explain the

M. Fujimoto; A. Nishida

1990-01-01

426

Asymmetric loads on a BWR shroud during blowdown after a recirculation line break  

SciTech Connect

The reactor core in boiling water reactors is surrounded by a cylindrical steel shroud. In 1994 routine inspection revealed surface cracks in the shroud welds. These cracks have led to the concern that the damaged shrouds would not be able to withstand the loads encountered during loss of coolant accidents. This paper discusses the load caused by a recirculation line break.

Gillis, J.C. [Levy Associates, Campbell, CA (United States)

1995-12-31

427

Removal efficiency and balance of nitrogen in a recirculating aquaculture system integrated with constructed wetlands  

Microsoft Academic Search

The nitrogen (N) balance for aquaculture is an important aspect, especially in China, and it is attributed to the eutrophication in many freshwater bodies. In recent years, constructed wetlands (CWs) have been widely used in wastewater treatment and ecosystem restoration. A recirculating aquaculture system (RAS) consisting of CWs and 4 fish ponds was set up in Wuhan, China. Channel catfish

Fei Zhong; Wei Liang; Tao Yu; Shui P. Cheng; Feng He; Zhen B. Wu

2011-01-01

428

The use of ozone in a high density recirculation system for rotifers  

Microsoft Academic Search

The use of ozone in the effluent treatment of a closed recirculation system for rotifers resulted in a significant improvement of rotifer production and water quality. Compared to a control treatment, the rotifer culture exposed to ozone did not only support a higher rotifer biomass (16000 vs. 8000 rotifers ml?1), it also allowed a prolongation of the culture period for

G Suantika; P Dhert; G Rombaut; J Vandenberghe; T De Wolf; P Sorgeloos

2001-01-01

429

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

430

Parametric studies for recirculating induction accelerators as drivers for heavy-ion fusion  

Microsoft Academic Search

A computer model for the cost and performance of a recirculating induction heavy-ion accelerator for driving inertial fusion reactions has been developed This code has been used to examine the driver design space in an effort to reduce driver costs while maintaining high driver efficiency and target gain. The driver model is described, and the results of parametric studies are

Robert L. Bieri; W. J. Schafer

1993-01-01

431

Response of Bacterial Biofilms in Recirculating Aquaculture Systems to Various Sanitizers  

Microsoft Academic Search

Pathogenic microorganisms may be incorporated into biofilms found in aquaculture systems, causing recurring exposure to potential disease agents. Aerobic plate counts, the presence of Enterobacteriaceae, and the presence of Escherichia coli, modified to express a green fluorescent protein (GFP E. coli), was used to evaluate the effectiveness of various sanitizers in decreasing bacterial incorporation into newly generated biofilms in recirculating

Robin K. King; George J. Flick Jr; Stephen A. Smith; Merle D. Pierson; Gregory D. Boardman; Charles W. Coale Jr

2008-01-01

432

Evaluation of nitrifying bacteria product to improve nitrification efficacy in recirculating aquaculture systems  

Microsoft Academic Search

Recirculating aquaculture systems (RASs) rely on nitrification to convert toxic ammonia and nitrite to less toxic nitrate. Nitrification is accomplished using biofilters with nitrifying bacteria and can be inefficient in biofilters that are new or that have been compromised due to stressors. Failure in a biofilter can result in very high levels of ammonia or nitrite, both of which are

David D. Kuhn; David D. Drahos; Lori Marsh; George J. Flick Jr.

2010-01-01

433

THE PRESENCE OF BACTERIAL PATHOGENS IN RECIRCULATING AQUACULTURE SYSTEM BIOFILMS AND THEIR RESPONSE TO VARIOUS SANITIZERS  

Microsoft Academic Search

ABSTRACT Recirculating aquaculture offers a prospect for successful fish farming, but this form of aquaculture presents a great potential for pathogenic microorganisms,to become established in the system through the formation of biofilms. Biofilms are capable of forming on all aquaculture system components, incorporating the various microflora present in the water. Pathogenic microorganisms,released from the biofilms are capable of causing recurring

Robin K. King

434

Growth and survival of juvenile cobia, Rachycentron canadum, at different salinities in a recirculating aquaculture system  

Microsoft Academic Search

Cobia (Rachycentron canadum) is an emerging aquaculture candidate for both offshore cage culture and land-based systems such as recirculating aquaculture systems. The ability to grow cobia at salinities other than oceanic (?34 ppt) could present culturists with additional production opportunities with this species. Culture at low salinities could also reduce the incidence of disease and simplify water management. In two

Matthew J. Resley; Kenneth A. Webb; G. Joan Holt

2006-01-01

435

Membrane Filtration Coupled with Chemical Precipitation to Treat Recirculating Aquaculture System Effluents  

Microsoft Academic Search

Effluents from recirculating aquaculture systems (RAS) contain high concentrations of nitrogen and phosphorous wastes and thus of- ten require proper treatment to prevent potential detrimental impacts on receiving water bodies. The purpose of this study was to evaluate the feasibility of membrane filtration coupled with chemical precip- itation as a pretreatment step with emphasis on phosphorus removal from RAS effluents.

Ling Yang; Hongde Zhou; Richard Moccia

2006-01-01

436

Quantification of anammox activity in a denitrification reactor for a recirculating aquaculture system  

Microsoft Academic Search

The activity of anammox bacteria in a denitrification reactor in a recirculating aquaculture system (RAS) for gilthead seabream production was investigated. Organic matter, extracted from the pond's solid filter, was used as the electron donor and carbon source for the denitrification reaction. The reactor was operated at four solid retention times (SRT). At steady state, anammox activity showed similar activity

Ori Lahav; Iris Bar Massada; Dimitry Yackoubov; Ruth Zelikson; Noam Mozes; Yossi Tal; Sheldon Tarre

2009-01-01

437

Nephrocalcinosis in Nile Tilapia from a Recirculation Aquaculture System: A Case Report  

Microsoft Academic Search

Nile tilapia Oreochromis niloticus were presented to the Fish Disease Diagnostic Laboratory with the complaint of chronic low-level mortalities in a recirculation aquaculture system. Microscopic examination of kidneys revealed moderate to severe nephrocalcinosis. Salient information from the case history was the utilization of agricultural-grade lime (calcium carbonate) to maintain alkalinity in the water of the culture system for the 4

Chun-Yao Chen; Gregory A. Wooster; Rodman G. Getchell; Paul R. Bowser; Michael B. Timmons

2001-01-01

438

Reduction in the make-up water in semi-closed recirculating aquaculture systems  

Microsoft Academic Search

Three feeding trials with rainbow trout (Oncorhynchus mykiss) were run in a closed recirculating aquaculture system with a nitrification unit and a sedimentation tank. The used trout feed had first a protein content of 47.9% (no. 1) and afterwards a protein content of 38.5% (no. 2). The effects of different protein contents of the feeds (trial I and II) and

C Schuster; H Stelz

1998-01-01

439

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

440

A design study on the optimal water refreshment rate in recirculating aquaculture systems  

Microsoft Academic Search

Refreshment (make-up) water is used in recirculating aquaculture systems (RAS) mainly to purge off-flavors, to add alkalinity and sometimes for temperature control. Alternatively, alkalinity may be added by means of a chemical base and heat may be supplied by a heating system. The objective of this study is to show how the optimal (minimizing cost) mix of the three controls:

Ido Seginer; Noam Mozes; Ori Lahav

2008-01-01

441

Growth of juvenile cobia, Rachycentron canadum, at three different densities in a recirculating aquaculture system  

Microsoft Academic Search

Cobia (Rachycentron canadum) is an excellent aquaculture candidate and culture of this species continues to develop worldwide. Current culture practices generally include larviculture and production of early juveniles on land with final growout occurring in ocean cages. Data indicate that production and\\/or growout of juveniles in land based recirculating systems may be hampered by growth depression in fish held at

Kenneth A. Webb; Glenn M. Hitzfelder; Cynthia K. Faulk; G. Joan Holt

2007-01-01

442

HRT and nutrients affect bacterial communities grown on recirculation aquaculture system effluents  

Microsoft Academic Search

In a recirculation aquaculture system the drumfilter effluent can be used as substrate for heterotrophic bacterial production, which can be recycled as feed. Because the bacteria might contain pathogens, which could reduce its suitability as feed, it is important to characterize these communities. Bacteria were produced in growth reactors under different conditions: 7¿h hydraulic retention time (HRT) vs. 2¿h, sodium

O. Schneider; M. Chabrillon-Popelka; H. Smidt; O. L. M. Haenen; V. Sereti; E. H. Eding; J. A. J. Verreth

2007-01-01

443

Microparticles in recirculating aquaculture systems: determination of particle density by density gradient centrifugation  

Microsoft Academic Search

Solid particulates in aquaculture waters are often separated from the culture water on a basis of density. The character and density of particles in such systems are not well defined. A method of determining the density of organic-based solids in aquaculture systems using density gradient centrifugation is demonstrated. The density of the two main particle fractions in one cold-water recirculating

R. N Patterson; K. C Watts; T. A Gill

2003-01-01

444

A conceptual, stoichiometry-based model for single-sludge denitrification in recirculating aquaculture systems  

Microsoft Academic Search

In the near future, the discharge of nitrate from recirculating aquaculture systems (RAS) to receiving water bodies is expected to be constrained by environmental regulations. Following wastewater treatment terminology, nitrate removal that makes use of the organic solid wastes generated within the RAS as the energy source for denitrification, may be termed ‘single-sludge denitrification’. In this approach, the costs associated

Sivan Klas; Noam Mozes; Ori Lahav

2006-01-01

445

New developments in recirculating aquaculture systems in Europe: A perspective on environmental sustainability  

Microsoft Academic Search

The dual objective of sustainable aquaculture, i.e., to produce food while sustaining natural resources is achieved only when production systems with a minimum ecological impact are used. Recirculating aquaculture systems (RASs) provide opportunities to reduce water usage and to improve waste management and nutrient recycling. RAS makes intensive fish production compatible with environmental sustainability. This review aims to summarize the

C. I. M. Martins; E. H. Eding; M. C. J. Verdegem; L. T. N. Heinsbroek; O. Schneider; J. P. Blancheton; E. Roque d’Orbcastel; J. A. J. Verreth

2010-01-01

446

Comparison of Bacterial Presence in Biofilms on Different Materials Commonly Found in Recirculating Aquaculture Systems  

Microsoft Academic Search

Recirculating aquaculture offers an economic potential for successful fish farming requiring limited resources. However, this form of aquaculture may present a potential unacceptable health risk for the fish. Pathogenic microorganisms may be incorporated into biofilms found in aquaculture systems, causing recurring exposure to disease agents. The presence of E. colimodified to express a green fluorescent protein (GFP E. coli) was

Robin K. King; George J. Flick; Stephen A. Smith; Merle D. Pierson; Gregory D. Boardman; Charles W. Coale

2006-01-01

447

Systems engineering for ornamental fish production in a recirculating aquaculture system  

Microsoft Academic Search

The aim was to develop a simulation model for determining the optimal layout and management regime for ornamental fish recirculating aquaculture system (ORAS). The work plan involved: (1) quantifying the effects of fish growth rates, the nature of the products, and the management practices; (2) developing a mathematical simulation model of the ORAS, taking into account all factors that directly

Ilan Halachmi

2006-01-01

448

Efficacy of Hydrogen Peroxide in Marine Recirculating Aquaculture Systems Holding Summer Flounder, Paralichthys dentatus  

Microsoft Academic Search

The effect of continuous dosing of hydrogen peroxide to a marine recirculating aquaculture system holding summer flounder was examined. Hydrogen peroxide is a strong oxidizing agent that may affect many chemical and biological processes. Results indicate that continuous dosing of hydrogen peroxide at the level tested is not an effective method to improve water quality in marine systems.

David E. Mowry; Michael H. Schwarz; Kathleen H. Hartman; Michael L. Jahncke; Stephen A. Smith

2005-01-01

449

Part-day ozonation for nitrogen and organic carbon control in recirculating aquaculture systems  

Microsoft Academic Search

Recent work on ozone application in recirculating aquaculture systems (RAS) gives guidelines as to the daily ozone dose as a function of feed rates, but does not indicate whether the ozone should be added continuously throughout the day or in shorter, more intense doses. This study examined the effect of adding the same total amount of ozone (15 g ozone

Valdis Krumins; James Ebeling; Fred Wheaton

2001-01-01

450

Biodegradable polymers as solid substrate and biofilm carrier for denitrification in recirculated aquaculture systems  

Microsoft Academic Search

A simple process for nitrate removal is proposed for its application in aquaculture. Biodegradable polymer pellets are acting as solid substrate and biofilm carrier for denitrification. Laboratory experiments with conventional aquaria and fish were used to examine the feasibility and a first evaluation of the process performance in a recirculated aquaculture system. All over the test-period the fish were in

A. Boley; W.-R. Müller; G. Haider

2000-01-01

451

a Study of Recirculating Flow Computation Using Body-Fitted Coordinates: Consistency Aspects and Mesh Skewness  

Microsoft Academic Search

A study of the computation of recirculating flows using body-fitted coordinates has been conducted with a numerical algorithm developed previously. Both the consistent treatment of the continuity equation and the effects of the grid skewness on the calculated flow field have been investigated. A more consilient method has been developed that formally satisfies the conservation laws more closely, allowing the

M. Braaten; W. Shyy

1986-01-01

452

A study of recirculating flow computation using body-fitted coordinates - Consistency aspects and mesh skewness  

Microsoft Academic Search

A study of the computation of recirculating flows using body-fitted coordinates has been conducted with a numerical algorithm developed previously. Both the consistent treatment of the continuity equation and the effects of the grid skewness on the calculated flow field have been investigated. A more consistent method has been developed that formally satisfies the conservation laws more closely, allowing the

M. Braaten; W. Shyy

1986-01-01

453

Prediction-based trajectory tracking of External Gas Recirculation for turbocharged SI Engines  

E-print Network

. The amount of reintroduced burned gases is controlled by the EGR Valve. The addition of exhaust gas with direct injection, turbocharger and Variable Valve Timing (VVT) actuators [21]. Such a setup strategies to use exhaust gas recirculation (EGR) through a low-pressure circuit, represented in Fig. 1

454

Practical delay modeling of externally recirculated burned gas fraction for Spark-Ignited Engines  

E-print Network

by the EGR Valve, an actuator which is located upstream of the compressor. Consequently, the relative long Turbocharger Spark Plug Injector Pdc Tdc Tint NeNe EGR Valve Dair Degr Dasp Tuv Heat Exchanger Lambda Sensor industry consists in using exhaust gas recirculation (EGR) through a low-pressure circuit (see Hoepke et al

455

Valve device for an exhaust gas recirculation system of an internal combustion engine  

Microsoft Academic Search

A valve device for an exhaust gas recirculation system of an internal combustion engine to disclosed. This device has a diaphragm mechanism having a diaphragm to form at least one chamber which is connected to an engine port and has a valve member connected to said diaphragm via a rod to open the valve member against a force caused by

M. Ando; K. Katow; M. Yamazaki

1978-01-01

456

Diagnosing system for an exhaust gas recirculation system of an automotive engine  

Microsoft Academic Search

A diagnosing system is described for an exhaust gas recirculation system, comprising: means for detecting the position of the EGR valve and for producing a position signal dependent on the position of the EGR valve; and trouble detector means responsive to the valve operating signal and to the position signal for producing a trouble signal as an alarm signal when

1989-01-01

457

Air Charge Control for Turbocharged Spark Ignition Engines with Internal Exhaust Gas Recirculation  

E-print Network

valve timing on the cylinder charge over part-load and lightly boosted conditions are first analyzed to investigate the dynamic inter- actions between the electronic throttle and the valve overlap through variable an effort to minimize the detri- mental effects of high levels of exhaust gas recirculation (EGR

Stefanopoulou, Anna

458

A Recirculated Fish Production Unit in Combination with a Hydroponic Unit.  

National Technical Information Service (NTIS)

In two years of investigation, it has been demonstrated that it is feasible to use hydroponically grown plants to aid in maintaining water quality in a closed fish culture system supported by recirculated water. It has also been shown that the vegetable c...

W. M. Lewis, J. H. Yopp

1978-01-01

459

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

460

An economic and technical evaluation of integrating hydroponics in a recirculation fish production system  

Microsoft Academic Search

The economic and technical viability of incorporating tomatoes grown hydroponically into a recirculation system for channel catfish production were studied. A unit was planned and budgeted for an annual production of 20 tonnes of fish. A high internal rate of return (IRR) of 27.32% was indicated. Comparative results were derived for a system producing the catfish alone. This showed little

P. A. Chaves; R. M. Sutherland; L. M. Laird

1999-01-01

461

A Multi-Orbit Recirculation System for a Superconducting Linear Accelerator - The Recyclotron  

Microsoft Academic Search

The energy available from a superconducting linear electron accelerator (SCA) may be increased many times by means of an economical multi-orbit recirculation system, which preserves the most desirable characteristics of the SCA: good energy resolution (~10-4), high current and unity duty cycle. Furthermore, these properties of the SCA and its excellent emittance considerably simplify the design of the transport system

R. E. Rand

1973-01-01

462

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...

463

Treatment of trichodiniasis in eel ( Anguilla anguilla) reared in recirculation systems in Denmark: alternatives to formaldehyde  

Microsoft Academic Search

Treatment of trichodiniasis in recirculation eel farms using formalin (37%) has been found insufficient. We have screened 30 different chemical substances for efficacy against natural infections with trichodinids (Trichodina jadranica) on skin and gills of eels. The following substances showed high parasiticidal effect: acriflavin (25 ppm), bithionol (0.1 ppm), chloramine T (50 ppm), Detarox AP® (45 ppm), malachite green (1

Hans C. K Madsen; Kurt Buchmann; Stig Mellergaard

2000-01-01

464

The development of a TESLA recirculator with superconducting accelerating structures in Ukraine  

NASA Astrophysics Data System (ADS)

The recirculator project, which is to be built at the National Science Center, Kharkov Institute of Physics and Technology (NSC KIPT), is presented. The basic solutions incorporated in the design are given. The TESLA superconducting section is chosen as the accelerating structure of an accelerating complex.

Guk, I. S.; Dovbnya, A. N.

2008-12-01

465

Morphological characteristics of changes in limb skeletal muscle tissue during experimental postischemic recirculation  

Microsoft Academic Search

In a previous communication the writers gave data on changes in skeletal muscles in the ischemic period of acute arterial occlusion of the limbs, and the microscopic picture and functional morphology of the ischemic skeletal muscles 2 h after restoration of the blood flow to the limbs were stugied. Early postischemic recirculation is undoubtedly the most reliable test of viability

V. S. Savel'ev; G. A. Chekareva; O. D. Mishnev; O. A. Bogdanov

1985-01-01

466

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

467

Re-circulating power, unit costs and thermal pollution of fusion power stations  

Microsoft Academic Search

The fraction ? of electrical power re-circulated is shown to be of crucial importance in assessing the credibility of fusion systems as commercial reactors, and it is advocated that ? should replace the more commonly used criterion Q, the energy amplification in the fusion reactor itself. Both unit costs and thermal pollution are shown to scale as (constant + ?)\\/(1-?)

P. A. Davenport

1978-01-01