Modeling of leachate recirculation using combined drainage blanket-horizontal trench systems in bioreactor landfills.

PubMed

Feng, Shi-Jin; Cao, Ben-Yi; Xie, Hai-Jian

2017-10-01

Leachate recirculation in municipal solid waste (MSW) landfills operated as bioreactors offers significant economic and environmental benefits. Combined drainage blanket (DB)-horizontal trench (HT) systems can be an alternative to single conventional recirculation approaches and can have competitive advantages. The key objectives of this study are to investigate combined drainage blanket -horizontal trench systems, to analyze the effects of applying two recirculation systems on the leachate migration in landfills, and to estimate some key design parameters (e.g., the steady-state flow rate, the influence width, and the cumulative leachate volume). It was determined that an effective recirculation model should consist of a moderate horizontal trench injection pressure head and supplementary leachate recirculated through drainage blanket, with an objective of increasing the horizontal unsaturated hydraulic conductivity and thereby allowing more leachate to flow from the horizontal trench system in a horizontal direction. In addition, design charts for engineering application were established using a dimensionless variable formulation.

An evaluation of a micro programmable logic controller for oxygen monitoring and control in tanks of a recirculating aquaculture system

USDA-ARS?s Scientific Manuscript database

Control of dissolved gases, especially oxygen is an essential component of recirculating aquaculture systems. The use of pure oxygen in a recirculating aquaculture system creates supersaturated concentrations of dissolved oxygen and can reduce fish production costs by supporting greater fish and fee...

Simultaneously reducing CO2 and particulate exposures via fractional recirculation of vehicle cabin air.

PubMed

Jung, Heejung S; Grady, Michael L; Victoroff, Tristan; Miller, Arthur L

2017-07-01

Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO 2 ) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO 2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle. Operating the recirculation system with a standard cabin filter reduced particle concentrations to 1000 particles/cm 3 , although CO 2 levels rose to 3000 ppm. When as little as 25% fresh air was introduced (75% recirculation), CO 2 levels dropped to 1000 ppm, while particle concentrations remained below 5000 particles/cm 3 . We found that nanoparticles were removed selectively during recirculation and demonstrated the trade-off between cabin CO 2 concentration and cabin particle concentration using fractional air recirculation. Data showed significant increases in CO 2 levels during 100% recirculation. For various fan speeds, recirculation fractions of 50-75% maintained lower CO 2 levels in the cabin, while still reducing particulate levels. We recommend fractional recirculation as a simple method to reduce occupants' exposures to particulate matter and CO 2 in vehicles. A design with several fractional recirculation settings could allow air exchange adequate for reducing both particulate and CO 2 exposures. Developing this technology could lead to reductions in airborne nanoparticle exposure, while also mitigating safety risks from CO 2 accumulation.

Simultaneously reducing CO2 and particulate exposures via fractional recirculation of vehicle cabin air

PubMed Central

Jung, Heejung S.; Grady, Michael L.; Victoroff, Tristan; Miller, Arthur L.

2017-01-01

Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO2) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle. Operating the recirculation system with a standard cabin filter reduced particle concentrations to 1000 particles/cm3, although CO2 levels rose to 3000 ppm. When as little as 25% fresh air was introduced (75% recirculation), CO2 levels dropped to 1000 ppm, while particle concentrations remained below 5000 particles/cm3. We found that nanoparticles were removed selectively during recirculation and demonstrated the trade-off between cabin CO2 concentration and cabin particle concentration using fractional air recirculation. Data showed significant increases in CO2 levels during 100% recirculation. For various fan speeds, recirculation fractions of 50–75% maintained lower CO2 levels in the cabin, while still reducing particulate levels. We recommend fractional recirculation as a simple method to reduce occupants’ exposures to particulate matter and CO2 in vehicles. A design with several fractional recirculation settings could allow air exchange adequate for reducing both particulate and CO2 exposures. Developing this technology could lead to reductions in airborne nanoparticle exposure, while also mitigating safety risks from CO2 accumulation. PMID:28781568

Simultaneously reducing CO2 and particulate exposures via fractional recirculation of vehicle cabin air

NASA Astrophysics Data System (ADS)

Jung, Heejung S.; Grady, Michael L.; Victoroff, Tristan; Miller, Arthur L.

2017-07-01

Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO2) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle. Operating the recirculation system with a standard cabin filter reduced particle concentrations to 1000 particles/cm3, although CO2 levels rose to 3000 ppm. When as little as 25% fresh air was introduced (75% recirculation), CO2 levels dropped to 1000 ppm, while particle concentrations remained below 5000 particles/cm3. We found that nanoparticles were removed selectively during recirculation and demonstrated the trade-off between cabin CO2 concentration and cabin particle concentration using fractional air recirculation. Data showed significant increases in CO2 levels during 100% recirculation. For various fan speeds, recirculation fractions of 50-75% maintained lower CO2 levels in the cabin, while still reducing particulate levels. We recommend fractional recirculation as a simple method to reduce occupants' exposures to particulate matter and CO2 in vehicles. A design with several fractional recirculation settings could allow air exchange adequate for reducing both particulate and CO2 exposures. Developing this technology could lead to reductions in airborne nanoparticle exposure, while also mitigating safety risks from CO2 accumulation.

Combustion-gas recirculation system

DOEpatents

Baldwin, Darryl Dean

2007-10-09

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.

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

DOEpatents

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

2014-05-13

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

Automation of water supply and recirculation-filtration of water at a swimming pool using Zelio PLC

NASA Astrophysics Data System (ADS)

Diniş, C. M.; Popa, G. N.; Iagăr, A.

2018-01-01

The paper proposes the use of the Zelio PLC for the automation of the water supply and recirculation-filtration system of a swimming pool. To do this, the Zelio SR3B261BD - 24V DC with 10 digital inputs (24V DC) and 10 digital outputs (relay contacts) was used. The proposed application makes the control of the water supply pumps and the water recirculation-filtration from a swimming pool. The recirculation-filtration systems for pools and swimming pools are designed to ensure water cleaning and recirculation to achieve optimum quality and lasting service life. The water filtration process is one of the important steps in water treatment in polls and swimming pools. It consists in recirculation of the entire volume of water and begins by absorbing the water in the pool by means of a pump followed by the passing of water through the filter, disinfectant and pH dosing, and reintroducing the water back into the pool or swimming pool through the discharge holes. Filters must to work 24 hours a day to remove pollutants from pools or swimming pools users. Filtration removes suspension particles with different origins. All newly built pools and swimming pools must be fitted with water recirculation systems, and existing ones will be equipped with water recirculation and water treatment systems.

Quantification of wind flow in the European Mars Simulation Wind Tunnel Facility

NASA Astrophysics Data System (ADS)

Holstein-Rathlou, C.; Merrison, J. P.; Iversen, J. J.; Nornberg, P.

2012-04-01

We present the European Mars Simulation Wind Tunnel facility, a unique prototype facility capable of simulating a wide range of environmental conditions, such as those which can be found at the surface of Earth or Mars. The chamber complements several other large-scale simulation facilities at Aarhus University, Denmark. The facility consists of a 50 m3 environmental chamber capable of operating at low pressure (0.02 - 1000 mbar) and cryogenic temperatures (-130 °C up to +60 °C). This chamber houses a re-circulating wind tunnel capable of generating wind speeds up to 25 m/s and has a dust injection system that can produce suspended particulates (aerosols). It employs a unique LED based optical illumination system (solar simulator) and an advanced network based control system. Laser based optoelectronic instrumentation is used to quantify and monitor wind flow, dust suspension and deposition. This involves a commercial Laser Doppler Anemometer (LDA) and a Particle Dynamics Analysis receiver (PDA), which are small laser based instruments specifically designed for measuring wind speed and sizes of particles situated in a wind flow. Wind flow calibrations will be performed with the LDA system and presented. Pressure and temperature calibrations will follow in order to enable the facility to be used for the testing, development, calibration and comparison of e.g. meteorological sensors under a wide range of environmental conditions as well as multi-disciplinary scientific studies. The wind tunnel is accessible to international collaborators and space agencies for instrument testing, calibration and qualification. It has been financed by the European Space Agency (ESA) as well as the Aarhus University Science Faculty and the Villum Kann Rasmussen Foundation.

Investigation of induced recirculation during planned ventilation system maintenance

PubMed Central

Pritchard, C.J.; Scott, D.F.; Noll, J.D.; Voss, B.; Leonis, D.

2015-01-01

The Office of Mine Safety and Health Research (OMSHR) investigated ways to increase mine airflow to underground metal/nonmetal (M/NM) mine working areas to improve miners’ health and safety. One of those areas is controlled recirculation. Because the quantity of mine air often cannot be increased, reusing part of the ventilating air can be an effective alternative, if implemented properly, until the capacity of the present system is improved. The additional airflow can be used to provide effective dilution of contaminants and higher flow velocities in the underground mine environment. Most applications of controlled recirculation involve taking a portion of the return air and passing it back into the intake to increase the air volume delivered to the desired work areas. OMSHR investigated a Nevada gold mine where shaft rehabilitation was in progress and one of the two main fans was shut down to allow reduced air velocity for safe shaft work. Underground booster fan operating pressures were kept constant to maintain airflow to work areas, inducing controlled recirculation in one work zone. Investigation into system behavior and the effects of recirculation on the working area during times of reduced primary ventilation system airflow would provide additional information on implementation of controlled recirculation into the system and how these events affect M/NM ventilation systems. The National Institute for Occupational Safety and Health monitored the ventilation district when both main fans were operating and another scenario with one of the units turned off for maintenance. Airflow and contaminants were measured to determine the exposure effects of induced recirculation on miner health. Surveys showed that 19% controlled recirculation created no change in the overall district airflow distribution and a small reduction in district fresh air intake. Total dust levels increased only modestly and respirable dust levels were also low. Diesel particulate matter (DPM) levels showed a high increase in district intake mass flow, but minor increases in exposure levels related to the recirculation percentage. Utilization of DPM mass flow rates allows input into ventilation modeling programs to better understand and plan for ventilation changes and district recirculation effects on miners’ health. PMID:26190862

Effect of recirculation on organic matter removal in a hybrid constructed wetland system.

PubMed

Ayaz, S C; Findik, N; Akça, L; Erdoğan, N; Kinaci, C

2011-01-01

This research project aimed to determine the technologically feasible and applicable wastewater treatment systems which will be constructed to solve environmental problems caused by small communities in Turkey. Pilot-scale treatment of a small community's wastewater was performed over a period of more than 2 years in order to show applicability of these systems. The present study involves removal of organic matter and suspended solids in serially operated horizontal (HFCW) and vertical (VFCW) sub-surface flow constructed wetlands. The pilot-scale wetland was constructed downstream of anaerobic reactors at the campus of TUBITAK-MRC. Anaerobically pretreated wastewater was introduced into this hybrid two-stage sub-surface flow wetland system (TSCW). Wastewater was first introduced into the horizontal sub-surface flow system and then the vertical flow system before being discharged. Recirculation of the effluent was tested in the system. When the recirculation ratio was 100%, average removal efficiencies for TSCW were 91 +/- 4% for COD, 83 +/- 10% for BOD and 96 +/- 3% for suspended solids with average effluent concentrations of 9 +/- 5 mg/L COD, 6 +/- 3 mg/L BOD and 1 mg/L for suspended solids. Comparing non-recirculation and recirculation periods, the lowest effluent concentrations were obtained with a 100% recirculation ratio. The effluent concentrations met the Turkish regulations for discharge limits of COD, BOD and TSS in each case. The study showed that a hybrid constructed wetland system with recirculation is a very effective method of obtaining very low effluent organic matter and suspended solids concentrations downstream of anaerobic pretreatment of domestic wastewaters in small communities.

Use of a micro programmable logic controller for oxygen monitoring and control in multiple tanks of a recirculating aquaculture system

USDA-ARS?s Scientific Manuscript database

In intensive recirculating aquaculture systems the use of supplemental oxygen, specifically pure liquid oxygen, increases the mass of fish that can be supported and eliminates oxygen as a major limiting factor to a system’s carrying capacity. The use of pure oxygen in a recirculating aquaculture sys...

High ratio recirculating gas compressor

DOEpatents

Weinbrecht, J.F.

1989-08-22

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.

Engine with pulse-suppressed dedicated exhaust gas recirculation

DOEpatents

Keating, Edward J.; Baker, Rodney E.

2016-06-07

An engine assembly includes an intake assembly, a spark-ignited internal combustion engine, and an exhaust assembly. The intake assembly includes a charge air cooler disposed between an exhaust gas recirculation (EGR) mixer and a backpressure valve. The charge air cooler has both an inlet and an outlet, and the back pressure valve is configured to maintain a minimum pressure difference between the inlet of the charge air cooler and an outlet of the backpressure valve. A dedicated exhaust gas recirculation system is provided in fluid communication with at least one cylinder and with the EGR mixer. The dedicated exhaust gas recirculation system is configured to route all of the exhaust gas from the at least one cylinder to the EGR mixer for recirculation back to the engine.

Analyzing the Use of Gaseous Helium as a Pressurant with Cryogenic Propellants with Thermodynamic Venting System Modelling and Test Data

NASA Technical Reports Server (NTRS)

Hedayat, A.; Nelson, S.L.; Hastings, L.J.; Flachbart, R.H.; Vermillion, D.J.; Tucker, S.P.

2007-01-01

Cryogens are viable candidate propellants for NASA's Lunar and Mars exploration programs. To provide adequate mass flow to the system's engines and/or to prevent feed system cavitation, gaseous helium (GHe) is frequently considered as a pressurant. During low gravity operations, a Thermodynamic Venting System (TVS) is designed to maintain tank pressure during low gravity operations without propellant resettling. Therefore, a series of tests were conducted in the Multi-purpose Hydrogen Test Bed (MHTB) of Marshall Space Flight Center (MSFC) in order to evaluate the effects of GHe pressurant on pressure control performance of a TVS with liquid hydrogen (LH2) and nitrogen (LN2) as the test liquids. The TVS used in these test series consists of a recirculation pump, Joule-Thomson (J-T) expansion valve, and a parallel flow concentric tube heat exchanger combined with a longitudinal spray bar. Using a small amount of liquid extracted from the tank recirculation line, passing it through the J-T valve, and then through the heat exchanger, thermal energy is extracted from the bulk liquid and ullage thereby enabling pressure control. The LH2/GHe tests were performed at fill levels of 90%, 50%, and 25% and LN2/GHe tests were conducted at fill levels of 50% and 25%. Moreover, each test was conducted with a specified tank ullage pressure control band. A one-dimensional TVS performance program was used to analyze and correlate the test data. Predictions and comparisons with test data of ullage pressure and temperature and bulk liquid saturation pressure and temperature with test data are presented.

The impact of recirculating industrial air on aircraft painting operations.

PubMed

LaPuma, P T; Bolch, W E

1999-10-01

The 1990 Clean Air Act Amendments resulted in new environmental regulations for hazardous air pollutants. Industries such as painting facilities may have to treat large volumes of air, which increases the cost of an air control system. Recirculating a portion of the air back into the facility is an option to reduce the amount of air to be treated. The authors of this study developed a computer model written in Microsoft Excel 97 to analyze the impact of recirculation on worker safety and compliance costs. The model has a chemical database with over 1300 chemicals. The model will predict indoor air concentrations using mass balance calculations and results are compared to occupational exposure limits. A case study is performed on a C-130 aircraft painting facility at Hill Air Force Base, Utah. The model predicts strontium chromate concentrations found in primer paints will reach 1000 times the exposure limit. Strontium chromate and other solid particulates are nearly unaffected by recirculation because the air is filtered during recirculation. The next highest chemical, hexamethylene diisocyanate, increases from 2.6 to 10.5 times the exposure limit at 0 percent and 75 percent recirculation, respectively. Due to the level of respiratory protection required for the strontium chromate, workers are well protected from the modest increases in concentrations caused by recirculating 75 percent of the air. The initial cost of an air control system is $4.5 million with no recirculation and $1.8 million at 75 percent recirculation. The model is an excellent tool to evaluate air control options with a focus on worker safety. In the case study, the model highlights strontium chromate primers as good candidates for substitution. The model shows that recirculating 75 percent of the air at the Hill painting facility has a negligible impact on safety and could save $2.7 million on the initial expenses of a thermal treatment system.

Three-dimensional modelling of leachate recirculation using vertical wells in bioreactor landfills.

PubMed

Feng, Shi-Jin; Chen, Zheng-Wei; Cao, Ben-Yi

2016-12-01

Bioreactor landfills use leachate recirculation to enhance the biodegradation of municipal solid waste and accelerate landfill stabilisation, which can provide significant environmental and economic benefits. Vertical wells are operated as a major method for leachate recirculation systems. The objectives of this article are to analyse the leachate migration in bioreactor landfills using vertical wells and to offer theoretical basis for the design of leachate recirculation systems. A three-dimensional numerical model was built using FLAC-3D, and this model can consider the saturated and unsaturated flow of leachate within anisotropic waste to reflect the actual conditions. First, main influence factors of leachate migration were analysed, including the vertical well height, hydraulic conductivity, and anisotropic coefficient, in a single-well recirculation system. Then, the effects of different configurations of a group-well system were studied and the optimal well spacing was obtained. Some key design parameters (e.g. the recirculation flow rate, volume of impact zone, radius of impact zone and time to reach steady state) were also evaluated. The results show that the hydraulic conductivity has a great impact on the optimal height of vertical wells and uniform configuration is the best option in terms of both volume of impact zone and time to reach steady state. © The Author(s) 2016.

Role of Hot Water System Design on Factors Influential to Pathogen Regrowth: Temperature, Chlorine Residual, Hydrogen Evolution, and Sediment

PubMed Central

Brazeau, Randi H.; Edwards, Marc A.

2013-01-01

Abstract Residential water heating is linked to growth of pathogens in premise plumbing, which is the primary source of waterborne disease in the United States. Temperature and disinfectant residual are critical factors controlling increased concentration of pathogens, but understanding of how each factor varies in different water heater configurations is lacking. A direct comparative study of electric water heater systems was conducted to evaluate temporal variations in temperature and water quality parameters including dissolved oxygen levels, hydrogen evolution, total and soluble metal concentrations, and disinfectant decay. Recirculation tanks had much greater volumes of water at temperature ranges with potential for increased pathogen growth when set at 49°C compared with standard tank systems without recirculation. In contrast, when set at the higher end of acceptable ranges (i.e., 60°C), this relationship was reversed and recirculation systems had less volume of water at risk for pathogen growth compared with conventional systems. Recirculation tanks also tended to have much lower levels of disinfectant residual (standard systems had 40–600% higher residual), 4–6 times as much hydrogen, and 3–20 times more sediment compared with standard tanks without recirculation. On demand tankless systems had very small volumes of water at risk and relatively high levels of disinfectant residual. Recirculation systems may have distinct advantages in controlling pathogens via thermal disinfection if set at 60°C, but these systems have lower levels of disinfectant residual and greater volumes at risk if set at lower temperatures. PMID:24170969

Recurrent amoebic gill infestation in rainbow trout cultured in a semiclosed water recirculation system

USGS Publications Warehouse

Noble, A.C.; Herman, R.L.; Noga, E.J.; Bullock, G.L.

1997-01-01

Five lots of commercially purchased juvenile rainbow trout Oncorhynchus mykiss (17-44 g) stocked in a continuous-production water recirculation system became infested with gilt amoebae. The amoebae were introduced into the recirculation system, as evidenced by their presence on gills of fish held in quarantine tanks. Based on their morphology, as seen in histological sections and by electron microscopy, the amoebae appeared to be more closely related to the family Cochliopodiidae than to other taxa of free living amoebae. Attempts to culture the amoebae in different media, at different temperatures of incubation, and in fish cell culture were not successful. Initial treatment of the recirculation system with formalin at 167 parts per million (ppm) for 1 h eliminated amoebae from the gills. Subsequent treatments of the entire system with formalin at 50-167 ppm reduced the intensity of further infestations.

Increasing EDV Range through Intelligent Cabin Air Handling Strategies: Annual Progress Report

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

Leighton, Daniel; Rugh, John

Computational fluid dynamics (CFD) simulations of a Ford Focus Electric demonstrated that a split flow heating, ventilating and air conditioning (HVAC) system with rear recirculation ducts can reduce cabin heating loads by up to 57.4% relative to full fresh air usage under some conditions (steady state, four passengers, ambient temperature of -5 deg C). Simulations also showed that implementing a continuous recirculation fraction control system into the original equipment manufacturer (OEM) HVAC system can reduce cabin heating loads by up to 50.0% relative to full fresh air usage under some conditions (steady state, four passengers, ambient temperature of -5 degmore » C). Identified that continuous fractional recirculation control of the OEM system can provide significant energy savings for EVs at minimal additional cost, while a split flow HVAC system with rear recirculation ducts only provides minimal additional improvement at significant additional cost.« less

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

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

Semenov, V. A.

2009-06-12

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.

An Inexpensive Recirculating Aquaculture System with Multiple Use Capabilities.

ERIC Educational Resources Information Center

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

1999-01-01

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)

Off-flavor characterization and depuration in Atlantic salmon cultured to food-size within closed-containment systems

USDA-ARS?s Scientific Manuscript database

Atlantic salmon are typically cultured in marine net pens. However, technological advancements in recirculating aquaculture systems have increased the feasibility of culturing Atlantic salmon in land-based systems. One problem encountered when fish are harvested from recirculating systems is the pre...

Sensitivity of bandpass filters using recirculating delay-line structures

NASA Astrophysics Data System (ADS)

Heyde, Eric C.

1996-12-01

Recirculating delay lines have value notably as sensors and optical signal processors. Most useful applications depend on a high-finesse response from a network. A proof that, with given response parameters, more complex systems can produce behavior that is more stable to the effects of nonidealities than a single recirculating loop is presented.

Controlling Factors of the Fate of Ionospheric Outflow at Earth and Mars

NASA Astrophysics Data System (ADS)

Liemohn, M. W.; Welling, D. T.; Ilie, R.; Ganushkina, N. Y.; Johnson, B. C.; Xu, S.; Dong, C.

2015-12-01

Both Earth and Mars experience ionospheric outflow, but the radically different magnetic field configurations at the two planets yield significantly different patterns of outflow and processes governing outflow. This study examines a set of numerical simulations for Earth and Mars to explore the factors controlling ionospheric outflow and the fate of the escaping ions (immediate precipitation, magnetospheric recirculation, or loss to deep space). Specifically, simulation results from the Space Weather Modeling Framework (SWMF), which is capable of handling both planetary space environments, are analyzed to assess the physical processes governing the fate of ionospheric ions. Velocity streamlines from the SWMF results are traced from the high-latitude inner boundary of the BATS-R-US MHD simulation domain and followed through geospace. Some of these streamlines return to the inner boundary of the simulation domain, others extend to the outer boundary of the domain, while most others eventually cross (or at least approach) the magnetospheric equatorial plane. At Earth, this plane is well defined, while at Mars there are multiple mini-magnetospheres in which ionospheric ions can become trapped. These streamlines are categorized according to their eventual destination. Multi-fluid MHD simulations are examined in this study, assessing the influence of species mass on trajectories through near-planet space. Steady-state numerical experiments with different levels of solar driving are examined to quantify the influence of each driver on outflow characteristics and the fate of outflowing ions. Real event intervals are considered to assess flows in a time-varying magnetospheric system. For Earth, as solar wind dynamic pressure increases, the dominant outflow region moves to lower latitudes and significantly more of the outflowing ions escape to deep space. As the interplanetary magnetic field increases in southward magnitude, the region of dominant outflow shifts to lower latitudes and more is injected into the inner magnetosphere. The ionospheric regions dominantly contributing to mass within the magnetosphere are assessed and compared for the different driving conditions. At Mars, the situation is much more complicated.

Nitrate removal effectiveness of fluidized sulfur-based autotrophic denitrification biofilters for recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

There is a need to develop practical methods to reduce nitrate -nitrogen loads from recirculating aqua-culture systems to facilitate increased food protein production simultaneously with attainment of water quality goals. The most common wastewater denitrification treatment systems utilize methanol-...

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

NASA Astrophysics Data System (ADS)

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

2002-04-01

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

Systemic granuloma observed in Atlantic salmon Salmo salar raised to market size in a freshwater recirculation aquaculture system

USDA-ARS?s Scientific Manuscript database

Systemic granuloma was observed in sampled adult Atlantic salmon Salmo salar raised to harvest size in a freshwater recirculation aquaculture system. The prevalence of this condition was estimated at 10-20% of the population, with affected individuals grossly demonstrating pathology in varying degre...

Effects of recirculation in a three-tank pilot-scale system for pharmaceutical removal with powdered activated carbon.

PubMed

Kårelid, Victor; Larsson, Gen; Björlenius, Berndt

2017-05-15

The removal of pharmaceutically active compounds by powdered activated carbon (PAC) in municipal wastewater is a promising solution to the problem of polluted recipient waters. Today, an efficient design strategy is however lacking with regard to high-level overall, and specific, substance removal in the large scale. The performance of PAC-based removal of pharmaceuticals was studied in pilot-scale with respect to the critical parameters; contact time and PAC dose using one PAC product selected by screening in bench-scale. The goal was a minimum of 95% removal of the pharmaceuticals present in the evaluated municipal wastewater. A set of 21 pharmaceuticals was selected from an initial 100 due to their high occurrence in the effluent water of two selected wastewater treatment plants (WWTPs) in Sweden, whereof candidates discussed for future EU regulation directives were included. By using recirculation of PAC over a treatment system using three sequential contact tanks, a combination of the benefits of powdered and granular carbon performance was achieved. The treatment system was designed so that recirculation could be introduced to any of the three tanks to investigate the effect of recirculation on the adsorption performance. This was compared to use of the setup, but without recirculation. A higher degree of pharmaceutical removal was achieved in all recirculation setups, both overall and with respect to specific substances, as compared to without recirculation. Recirculation was tested with nominal contact times of 30, 60 and 120 min and the goal of 95% removal could be achieved already at the shortest contact times at a PAC dose of 10-15 mg/L. In particular, the overall removal could be increased even to 97% and 99%, at 60 and 120 min, respectively, when the recirculation point was the first tank. Recirculation of PAC to either the first or the second contact tank proved to be comparable, while a slightly lower performance was observed with recirculation to the third tank. With regards to individual substances, clarithromycin and diclofenac were ubiquitously removed according to the set goal and in contrast, a few substances (fluconazole, irbesartan, memantine and venlafaxine) required specific settings to reach an acceptable removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

Adsorption of Selected Antibiotics to Resins in Extracorporeal Blood Purification.

PubMed

Harm, Stephan; Gruber, Anna; Gabor, Franz; Hartmann, Jens

2016-01-01

Extracorporeal blood purification systems (EBS) use specific adsorbents for the elimination of toxins and cytokines. The aim of this study was to test different adsorbents for their ability to reduce antibiotics in parallel to extracorporeal blood purification therapy. The in vitro adsorption experiments were carried out in human plasma with a newly established hydrophobic resin (Amberchrom CG161c) and adsorbents commercially available and approved in the clinics. The concentration of antibiotic was chosen equivalent to the recommended therapeutic dosage applied intravenously and was measured in plasma using ELISA test kits and high-performance liquid chromatography methods. The adsorbent that reduced all tested antibiotics in plasma close to the detection limit was the dia MARS AC250, which is an activated charcoal involved in the Molecular Adsorbents Recirculation System. For better antibiotic monitoring in sepsis treatment, further investigations have to be performed to determine the clearance rate of antibiotics by different EBS devices. © 2015 S. Karger AG, Basel.

Better Management Practices for Recirculating Aquaculture Systems

USDA-ARS?s Scientific Manuscript database

Under the 2004 federal aquaculture effluent limitation guidelines (Federal Register 2004), recirculating aquaculture systems with an annual production exceeding 45,454 kg (100,000 pounds) are classified as concentrated aquatic animal production (CAAP) facilities and are required to obtain a National...

Production of cobia in recirculating systems

USDA-ARS?s Scientific Manuscript database

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

Freshwater Institute: Focused on improving recirculating aquaculture system technology

USDA-ARS?s Scientific Manuscript database

Recirculating aquaculture system (RAS) technologies help to overcome barriers to domestic aquaculture expansion and enhance the sustainability of the modern fish farming industry through reduction in environmental impacts. With RAS, fish farm expansion is no longer highly constrained by competition ...

Effect of recirculation rate on methane production and SEBAR system performance using active stage digester.

PubMed

Tubtong, Cheevanuch; Towprayoon, Sirintornthep; Connor, Michael Anthony; Chaiprasert, Pawinee; Nopharatana, Annop

2010-09-01

A project was undertaken to examine the feasibility of treating organic wastes from Thai fruit and vegetable markets using the sequential batch anaerobic digester (SEBAR) approach. A key feature of the SEBAR system is the regular interchanging, or recirculation, of portions of leachate between each freshly filled digester and a support digester to which it is coupled until it is ready to operate independently. Leachate transfer from this support digester to the fresh waste digester provides additional alkalinity to help counteract the effects of early high acid release rates; it also helps build a balanced microbial population in the fresh waste digester. To optimize the leachate recirculation process, the effect of varying the quantities of leachate interchanged between freshly filled waste digesters and the still highly active support digesters to which they were coupled was studied. It was found that increasing the recirculation rate accelerated the onset of both waste degradation and methane production. The increasing of recirculation rate from 10% to 20% and 10% to 30% could reduce the SEBAR cycle period by approximately 7% and 22% without significant reduction in the amount of methane obtained from the systems. The methane yields were 0.0063, 0.0068 and 0.0077 l g(-1) VS added in the NEW digester per day using leachate recirculation rates of 10%, 20% and 30%, respectively. This finding has potentially important practical and economic implications for those using the SEBAR system to add value to market waste.

Liquid-metal flows: Magnetohydrodynamics and applications; Proceedings of the Fifth Beersheba International Seminar on Magnetohydrodynamic Flows and Turbulence, University of the Negev, Beersheba, Israel, Mar. 2-6, 1987

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

Branover, H.; Mond, M.; Unger, Y.

The present collection of papers on MHD-related uses of liquid metal flows and their applications discusses topics in laminar MHD flows, MHD power generation, metallurgical MHD applications, and two-phase MHD flows. Attention is given to MHD flows with closed streamlines, nonlinear waves in liquid metals under a transverse magnetic field, liquid-metal MHD conversion of nuclear energy to electricity, the testing of optimized MHD conversion (OMACON) systems, and aspects of a liquid-metal induction generator. Also discussed are MHD effects in liquid-metal breeder reactors, a plasma-driven MHD powerplant, modeling the recirculating flows in channel-induction surfaces, the hydrodynamics of aluminum reduction cells, free-surfacemore » determination in a levitation-melting process, the parametric interactions of waves in bubbly liquid metals, and the occurrence of cavitation in water jets.« less

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

NASA Technical Reports Server (NTRS)

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

2008-01-01

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.

Simultaneous carbon and nitrogen removal from anaerobic effluent of the cassava ethanol industry.

PubMed

Yin, Zhixuan; Xie, Li; Zhou, Qi; Bi, Xuejun

2018-03-01

This study investigated the simultaneous carbon and nitrogen removal from anaerobic effluent of cassava stillage using a lab-scale integrated system consisting of an upflow anaerobic sludge blanket (UASB) reactor and an activated sludge (AS) process. Simultaneous denitrification and methanogenesis (SDM) was observed in the UASB with nitrate recirculation. Compared with the blank reactor without recirculation, the overall chemical oxygen demand (COD) removal efficiencies in the combined system with nitrate recirculation were similar (80-90%), while the TN removal efficiencies were significantly improved from 4.7% to 71.0%. Additionally, the anaerobic COD removal efficiencies increased from 21% to 40% as the recirculation ratio decreased from 3 to 1. Although the influent nitrate concentrations fluctuated (60-140 mg N/L), the nitrate removal efficiencies could be maintained at about 97% under different recirculation conditions. With the decreasing recirculation ratio from 3 to 1, the CH 4 content in biogas improved from 2% to 40% while the N 2 content reduced from 95.8% to 50.6%. The 16S rDNA sequencing results indicated that bacteria diversity in anaerobic SDM granular sludge was much higher than archaea. The effect of recirculation ratios on the bacterial and archaeal communities in SDM granular sludge could be further confirmed by the relative abundance of denitrifying bacteria. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Method and apparatus for control of coherent synchrotron radiation effects during recirculation with bunch compression

DOEpatents

Douglas, David R; Tennant, Christopher

2015-11-10

A modulated-bending recirculating system that avoids CSR-driven breakdown in emittance compensation by redistributing the bending along the beamline. The modulated-bending recirculating system includes a) larger angles of bending in initial FODO cells, thereby enhancing the impact of CSR early on in the beam line while the bunch is long, and 2) a decreased bending angle in the final FODO cells, reducing the effect of CSR while the bunch is short. The invention describes a method for controlling the effects of CSR during recirculation and bunch compression including a) correcting chromatic aberrations, b) correcting lattice and CSR-induced curvature in the longitudinal phase space by compensating T.sub.566, and c) using lattice perturbations to compensate obvious linear correlations x-dp/p and x'-dp/p.

Simplified liquid oxygen propellant conditioning concepts

NASA Technical Reports Server (NTRS)

Cleary, N. L.; Holt, K. A.; Flachbart, R. H.

1995-01-01

Current liquid oxygen feed systems waste propellant and use hardware, unnecessary during flight, to condition the propellant at the engine turbopumps prior to launch. Simplified liquid oxygen propellant conditioning concepts are being sought for future launch vehicles. During a joint program, four alternative propellant conditioning options were studied: (1) passive recirculation; (2) low bleed through the engine; (3) recirculation lines; and (4) helium bubbling. The test configuration for this program was based on a vehicle design which used a main recirculation loop that was insulated on the downcomer and uninsulated on the upcomer. This produces a natural convection recirculation flow. The test article for this program simulated a feedline which ran from the main recirculation loop to the turbopump. The objective was to measure the temperature profile of this test article. Several parameters were varied from the baseline case to determine their effects on the temperature profile. These parameters included: flow configuration, feedline slope, heat flux, main recirculation loop velocity, pressure, bleed rate, helium bubbling, and recirculation lines. The heat flux, bleed rate, and recirculation configurations produced the greatest changes from the baseline temperature profile. However, the temperatures in the feedline remained subcooled. Any of the options studied could be used in future vehicles.

Design and performance of recirculating systems for Atlantic salmon (Salmo salar) at the USDA ARS National Cold Water Marine Aquaculture Center (Franklin, Maine)

USDA-ARS?s Scientific Manuscript database

Atlantic salmon cultured in the NCWMAC breeding program have grown well in the fish culture systems during the first 3 years of operation. The systems were operated at approximately 98% reuse (2% makeup water on the basis of flow rate). The water recirculating systems maintained acceptable water qua...

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

USDA-ARS?s Scientific Manuscript database

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

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...

The study of recirculating aquaculture system in pond and its purification effect

NASA Astrophysics Data System (ADS)

Qu, Jiangqi; Zhang, Qingjing; Jia, Chengxia; Liu, Pan; Yang, Mu

2017-05-01

In this paper, a recirculating aquaculture purification system (RAPS) was designed to solve the problems of aquaculture pollution and shortage of freshwater resource according to the characteristic of northern freshwater ponds of China. The system were arranged in series and composed of high density culture pond, deposit pond, floating and submerged plant pond, ecological floating bed pond and biofilm filtrate pond. At the fish density of 20~30kg/m3 in the high density culture pond, the water quality parameters were monitored seasonally. The results indicated that the removal rate of total nitrogen, total phosphorus, ammonia nitrogen and nitrite nitrogen in the recirculating aquaculture system were 69.59%, 77.89%, 72.54% and 68.68%, respectively. The floating and submerged plant pond and ecological floating bed pond can remove TN and TP obviously, and increase dissolved oxygen and transparency significantly. And the biofilm filtrate pond has good effect of removing ammonium nitrogen and nitrite nitrogen, meanwhile, the microbial communities in the recirculating aquaculture system regulate on the water quality. Therefore, the RAPS show significant effects on water saving and pollution emission reducing.

Production of market-size North American strain Atlantic salmon Salmo salar in a land-based recirculation aquaculture system using freshwater

USDA-ARS?s Scientific Manuscript database

There is interest in culturing Atlantic salmon Salmo salar to market-size in land-based, closed containment systems that use recirculation aquaculture systems (RAS), as this technology often enables facilities to locate near major markets, obtain permits, exclude obligate pathogens, and/or reduce en...

Process Requirements for Achieving Full-Flow Disinfection of Recirculating Water Using Ozonation and UV Irradiation

USDA-ARS?s Scientific Manuscript database

A continuous water disinfection process can be used to prevent the introduction and accumulation of obligate and opportunistic fish pathogens in recirculating aquaculture systems (RAS), especially during a disease outbreak when the causative agent would otherwise proliferate within the system. To p...

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

USDA-ARS?s Scientific Manuscript database

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

Low head oxygenator performance characterization for marine recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

This study evaluated the effect of temperature (20 and 25 ºC), salinity (10, 15, and 20 ppt), and dissolved oxygen levels within low head oxygenator (LHO) outlet water on oxygen transfer efficiency (OTE) of LHOs for a planned marine recirculating aquaculture system (RAS). Test results indicated tha...

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

USDA-ARS?s Scientific Manuscript database

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

Open-RAC: Open-Design, Recirculating and Auto-Cleaning Zebrafish Maintenance System.

PubMed

Nema, Shubham; Bhargava, Yogesh

2017-08-01

Zebrafish is a vertebrate animal model. Their maintenance in large number under laboratory conditions is a daunting task. Commercially available recirculating zebrafish maintenance systems are used to efficiently handle the tasks of automatic sediment cleaning from zebrafish tanks with minimal waste of water. Due to their compact nature, they also ensure the maximal use of available lab space. However, the high costs of commercial systems present a limitation to researchers with limited funds. A cost-effective zebrafish maintenance system with major features offered by commercially available systems is highly desirable. Here, we describe a compact and recirculating zebrafish maintenance system. Our system is composed of cost-effective components, which are available in local markets and/or can be procured via online vendors. Depending on the expertise of end users, the system can be assembled in 2 days. The system is completely customizable as it offers geometry independent zebrafish tanks that are capable of auto-cleaning the sediments. Due to these features, we called our setup as Open-RAC (Open-design, Recirculating and Auto-Cleaning zebrafish maintenance system). Open-RAC is a cost-effective and viable alternative to the currently available zebrafish maintenance systems. Thus, we believe that the use of Open-RAC could promote the zebrafish research by removing the cost barrier for researchers.

Recirculating Air Filtration Significantly Reduces Exposure to Airborne Nanoparticles

PubMed Central

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

2008-01-01

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

A portable gas recirculation unit for gaseous detectors

NASA Astrophysics Data System (ADS)

Guida, R.; Mandelli, B.

2017-10-01

The use of greenhouse gases (usually C2H2F4, CF4 and SF6) is sometimes necessary to achieve the required performance for some gaseous detectors. The consumption of these gases in the LHC systems is reduced by recycling the gas mixture thanks to a complex gas recirculation system. Beyond greenhouse gas consumption due to LHC systems, a considerable contribution is generated by setups used for LHC detector upgrade projects, R&D activities, detector quality assurance or longevity tests. In order to minimise this emission, a new flexible and portable gas recirculation unit has been developed. Thanks to its low price, flexibility and user-friendly operation it can be easily adapted for the different types of detector systems and set-ups.

Production of polycaprolactone nanoparticles with low polydispersity index in a tubular recirculating system by using a multifactorial design of experiments

NASA Astrophysics Data System (ADS)

Colmenares Roldán, Gabriel Jaime; Agudelo Gomez, Liliana María; Carlos Cornelio, Jesús Antonio; Rodriguez, Luis Fernando; Pinal, Rodolfo; Hoyos Palacio, Lina Marcela

2018-03-01

Encapsulation and controlled release of substances using polymeric nanoparticles require that these have a high reproducibility, homogeneity, and control over their properties (diameter and polydispersity), especially when they are to be used in medical, pharmaceutical, or nutritional applications among others. In conventional production systems, it is tough to ensure these characteristics; hence, the cost increases when we try to control these properties. This paper shows a comparison between a recirculating system and the standard nanoprecipitation technique for producing polymeric nanoparticles. In previous investigations, we evaluate the effect of recirculating flow and the ratio between the organic and aqueous phase. For this paper, we evaluated the effect of polymer and surfactant concentrations using a multifactorial design of experiments on the recirculating system and on the standard nanoprecipitation system. The response of the design was the average diameter of the nanoparticles and polydispersity index. Finally, we found that the polymer and surfactant concentrations could change the average diameter and polydispersity index of the nanoparticles obtained. On the other hand, it was found that the effect of the polymer concentration was stronger than the surfactant concentration to reduce the average diameter of the nanoparticles. The results of the present study show that the proposed recirculation system presents a high potential to produce polymer nanoparticles with good morphological characteristics, particle size distributions in the nano range, and with a low polydispersity. The average mean size of nanoparticles of polycaprolactone for the design using the recirculating system was of 61 to 140 nm and the values of polydispersity index PDI for this design were between 0.097 and 0.22, while for the design using the standard nanoprecipitation technique, the obtained diameters were 74 to 176 nm and the polydispersity was between 0.26 and 0.41.

Biofouling reduction in recirculating cooling systems through biofiltration of process water.

PubMed

Meesters, K P H; Van Groenestijn, J W; Gerritse, J

2003-02-01

Biofouling is a serious problem in industrial recirculating cooling systems. It damages equipment, through biocorrosion, and causes clogging and increased energy consumption, through decreased heat transfer. In this research a fixed-bed biofilter was developed which removed assimilable organic carbon (AOC) from process water, thus limiting the major substrate for the growth of biofouling. The biofilter was tested in a laboratory model recirculating cooling water system, including a heat exchanger and a cooling tower. A second identical model system without a biofilter served as a reference. Both installations were challenged with organic carbon (sucrose and yeast extract) to provoke biofouling. The biofilter improved the quality of the recirculating cooling water by reducing the AOC content, the ATP concentration, bacterial numbers (30-40 fold) and the turbidity (OD660). The process of biofouling in the heat exchangers, the process water pipelines and the cooling towers, was monitored by protein increase, heat transfer resistance, and chlorine demanded for maintenance. This revealed that biofouling was lower in the system with the biofilter compared to the reference installation. It was concluded that AOC removal through biofiltration provides an attractive, environmental-friendly means to reduce biofouling in industrial cooling systems.

Production characteristics and body composition of juvenile cobia fed three different commercial diets in recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

The effect of feeding three commercial diets on production characteristics and body composition of juvenile cobia Rachycentron canadum reared using recirculating aquaculture systems (RAS) was evaluated in a 56 d growth trial. Juvenile cobia (29.2 +/= 0.7 g, mean weight +/= SE) were stocked into thr...

Assessing peracetic acid as a means to control post-vaccination Saprolegniasis in Atlantic salmon Salmo salar parr in recirculation aquaculture systems

USDA-ARS?s Scientific Manuscript database

Land-based closed containment facilities, utilizing recirculation aquaculture system (RAS) technologies, can reduce or eliminate the introduction of obligate fish pathogens. Regardless, the presence of opportunistic pathogens must be assumed, and these agents can cause disease during unfavorable con...

Abnormal swimming behavior and increased deformities in rainbow trout Oncorhynchus mykiss cultured in low exchange water recirculation aquaculture systems

USDA-ARS?s Scientific Manuscript database

Two studies were conducted to determine if accumulating water quality parameters would negatively impact rainbow trout Oncorhynchus mykiss health and welfare within water recirculation aquaculture systems (WRAS) that were operated at low and near-zero water exchange, with and without ozonation, and ...

Effects of semi-continous peracetic acid dosing on rainbow trout Oncorhynchus mykiss performance, water quality, and off-flavor compounds in recirculation aquaculture systems

USDA-ARS?s Scientific Manuscript database

Water clarifying and disinfection techniques such as ozonation and ultraviolet irradiation are commonly used in recirculation aquaculture systems (RAS); however, the capital and operating costs of these technologies are expensive. Cost-effective treatment options that maintain fish health and simult...

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

USDA-ARS?s Scientific Manuscript database

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

Temperature effects on biomass, geosmin, and 2-methylisoborneol production and cellular activity by Nocardia spp. and Streptomyces spp. isolated from rainbow trout recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

Isolates of Nocardia cummidelens, Nocardia fluminea, Streptomyces albidoflavus, and Streptomyces luridiscabiei attributing to geosmin-related off-flavor in rainbow trout (Oncorhynchus mykiss) raised in recirculating aquaculture systems (RAS) were evaluated for the effect of temperature (10-30 degree...

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

Hwang, Kilean; Qiang, Ji

A recirculating superconducting linear accelerator with the advantage of both straight and circular accelerator has been demonstrated with relativistic electron beams. The acceleration concept of a recirculating proton beam was recently proposed and is currently under study. In order to further support the concept, the beam dynamics study on a recirculating proton linear accelerator has to be carried out. In this paper, we study the feasibility of a two-pass recirculating proton linear accelerator through the direct numerical beam dynamics design optimization and the start-to-end simulation. This study shows that the two-pass simultaneous focusing without particle losses is attainable including fullymore » 3D space-charge effects through the entire accelerator system.« less

Wave energetics of the southern hemisphere of Mars

NASA Astrophysics Data System (ADS)

Battalio, Michael; Szunyogh, Istvan; Lemmon, Mark

2018-07-01

An assessment of the energetics of transient waves in the southern hemisphere of Mars is presented using the Mars Analysis Correction Data Assimilation (MACDA) dataset (v1.0) and the eddy kinetic energy equation. The dataset is divided into four representative periods covering the summer and winter solstices, a late fall period, and an early spring period for three Mars years. Spring eddies are the most intense, with eddies during the fall being less intense due to a marginally more stable mean-temperature profile and reduced recirculation of ageostrophic geopotential fluxes compared to the spring. Eddy kinetic energy during winter is reduced in intensity as a result of the winter solstitial pause in wave activity, and eddy kinetic energy during the summer is limited. Baroclinic energy conversion acts as a source in fall and spring but disappears during the winter as a result of a stabilized vertical temperature profile. Barotropic energy conversion acts as both a source and a sink of eddy kinetic energy, being most positive during the solstitial pause. Eddies take a northwest to southeast track across the southern highlands in the fall but have a more zonal track in the spring due to stronger eddy kinetic energy advection. Wave energetics is less intense in the southern compared to the northern hemisphere as a result of a shallower baroclinically unstable vertical profile.

Albumin Dialysis for Liver Failure: A Systematic Review.

PubMed

Tsipotis, Evangelos; Shuja, Asim; Jaber, Bertrand L

2015-09-01

Albumin dialysis is the best-studied extracorporeal nonbiologic liver support system as a bridge or destination therapy for patients with liver failure awaiting liver transplantation or recovery of liver function. We performed a systematic review to examine the efficacy and safety of 3 albumin dialysis systems (molecular adsorbent recirculating system [MARS], fractionated plasma separation, adsorption and hemodialysis [Prometheus system], and single-pass albumin dialysis) in randomized trials for supportive treatment of liver failure. PubMed, Ovid, EMBASE, Cochrane's Library, and ClinicalTrials.gov were searched. Two authors independently screened citations and extracted data on patient characteristics, quality of reports, efficacy, and safety end points. Ten trials (7 of MARS and 3 of Prometheus) were identified (620 patients). By meta-analysis, albumin dialysis achieved a net decrease in serum total bilirubin level relative to standard medical therapy of 8.0 mg/dL (95% confidence interval [CI], -10.6 to -5.4) but not in serum ammonia or bile acids. Albumin dialysis achieved an improvement in hepatic encephalopathy relative to standard medical therapy with a risk ratio of 1.55 (95% CI, 1.16-2.08) but had no effect survival with a risk ratio of 0.95 (95% CI, 0.84-1.07). Because of inconsistency in the reporting of adverse events, the safety analysis was limited but did not demonstrate major safety concerns. Use of albumin dialysis as supportive treatment for liver failure is successful at removing albumin-bound molecules, such as bilirubin and at improving hepatic encephalopathy. Additional experience is required to guide its optimal use and address safety concerns. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Effects of alkalinity on ammonia removal, carbon dioxide stripping, and system pH in semi-commercial scale water recirculating aquaculture systems operated with moving bed bioreactors

USDA-ARS?s Scientific Manuscript database

When operating water recirculating systems (RAS) with high make-up water flushing rates in locations that have low alkalinity in the raw water, such as Norway, knowledge about the required RAS alkalinity concentration is important. Flushing RAS with make-up water containing low alkalinity washes out...

The impact of recirculation, ventilation and filters on secondary organic aerosols generated by indoor chemistry

NASA Astrophysics Data System (ADS)

Fadeyi, M. O.; Weschler, C. J.; Tham, K. W.

This study examined the impact of recirculation rates (7 and 14 h -1), ventilation rates (1 and 2 h -1), and filtration on secondary organic aerosols (SOAs) generated by ozone of outdoor origin reacting with limonene of indoor origin. Experiments were conducted within a recirculating air handling system that serviced an unoccupied, 236 m 3 environmental chamber configured to simulate an office; either no filter, a new filter or a used filter was located downstream of where outdoor air mixed with return air. For otherwise comparable conditions, the SOA number and mass concentrations at a recirculation rate of 14 h -1 were significantly smaller than at a recirculation rate of 7 h -1. This was due primarily to lower ozone concentrations, resulting from increased surface removal, at the higher recirculation rate. Increased ventilation increased outdoor-to-indoor transport of ozone, but this was more than offset by the increased dilution of SOA derived from ozone-initiated chemistry. The presence of a particle filter (new or used) strikingly lowered SOA number and mass concentrations compared with conditions when no filter was present. Even though the particle filter in this study had only 35% single-pass removal efficiency for 100 nm particles, filtration efficiency was greatly amplified by recirculation. SOA particle levels were reduced to an even greater extent when an activated carbon filter was in the system, due to ozone removal by the carbon filter. These findings improve our understanding of the influence of commonly employed energy saving procedures on occupant exposures to ozone and ozone-derived SOA.

Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Rector, Tony; Peyton, Barbara M.; Steele, John W.; Makinen, Janice; Bue, Grant C.; Campbell, Colin

2014-01-01

Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a recirculating control loop which had no water quality maintenance. Results show that periodic water maintenance can improve performance of the SWME. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage of this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the evaluation of water recirculation maintenance components was to enhance the robustness of the SWME through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A patented bed design that was developed for a United Technologies Aerospace System military application provided a low pressure drop means for water maintenance in the SWME recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for the ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Heat Exchanger Cleaning in Support of Ocean Thermal Energy Conversion (OTEC) - Mechanical Subsystem.

DTIC Science & Technology

1980-12-01

sponge rubber ball, and chlorination systems. In addition, the maintenance procedures utilized at the NCSC test site are provided. jAN 7 1473 EDITION OF...Recirculating Sponge Rubber Balls .. .... ............. 17 Chlorination .. .............. ............. 19 OTEC MAINTENANCE PROCEDURES...C-1 APPENDIX D - RECIRCULATING SPONGE RUBBER BALL. ............... D-1 APPENDIX E - CHLORINATION SYSTEM .. .. ................. E-1 i 1

Periodic bacterial control with peracetic acid in a recirculating aquaculture system and its long-term beneficial effect on fish health

USDA-ARS?s Scientific Manuscript database

Peracetic acid (PAA) is being introduced to aquaculture as a sustainable disinfectant. It is suitable for recirculating aquaculture systems (RAS) because of the low effective concentrations and its minimal impact on biofilter function. The application of PAA in a RAS has a combined impact on fish an...

The impact of water exchange rate on the health and performance of rainbow trout Oncorhynchus mykiss in recirculation aquaculture systems

USDA-ARS?s Scientific Manuscript database

Fish mortality in recirculating aquaculture systems (RAS) has been observed by the authors to increase when RAS are managed at low makeup water exchange rates with relatively high feed loading. The precise etiology of this elevated mortality was unknown, all typical water quality parameters were wit...

The effects of ozonation on select waterborne steroid hormones in recirculation aquaculture systems containing sexually mature Atlantic salmon Salmo salar

USDA-ARS?s Scientific Manuscript database

A controlled 3-month study was conducted in 6 replicated water recirculation aquaculture systems (RAS) containing a mixture of sexually mature and immature Atlantic salmon Salmo salar to determine whether water ozonation is associated with a reduction in waterborne hormones. Post-smolt Atlantic salm...

Investigating the effectiveness of peracetic acid to reduce post-vaccination Saprolegnia spp.-associated mortality in Atlantic salmon parr while assessing impact on nitrification in recirculation aquaculture systems

USDA-ARS?s Scientific Manuscript database

Closed containment operations utilizing recirculation aquaculture systems (RAS) can provide critical barriers to the introduction of obligate fish pathogens (Timmons and Ebeling, 2010); however, opportunistic pathogens will be present and can cause disease when conditions favor these agents. One par...

Evaluating the chronic effects of nitrate on the health and performance of post-smolt Atlantic salmon Salmo salar in freshwater recirculation aquaculture systems

USDA-ARS?s Scientific Manuscript database

Commercial production of Atlantic salmon smolts, post-smolts, and market-size fish using land-based recirculation aquaculture systems (RAS) is expanding. RAS generally provide a nutrient-rich environment in which nitrate accumulates as an end-product of nitrification. An 8-month study was conducted ...

Membrane biological reactors to remove nitrate, digest biosolids, and eliminate water flushing requirements within replicated recirculation systems culturing rainbow trout

USDA-ARS?s Scientific Manuscript database

Nutrients, particularly nitrate (NO3), can accumulate to very high levels within low exchange recirculation aquaculture systems (RAS) and negatively impact a number of cultured species. To prevent the harmful effects of nitrate accumulation and to dispose of concentrated waste biosolids, many RAS ar...

Evaluating standard operating procedures to mitigate off-flavor from Atlantic salmon Salmo salar cultured in a semi-commercial scale recirculating aquaculture system

USDA-ARS?s Scientific Manuscript database

Fish cultured within water recirculating aquaculture systems (RAS) can acquire “earthy” or “musty” off-flavors due to bioaccumulation of the compounds geosmin and 2-methylisoborneol (MIB), respectively, which are produced by certain bacterial species present in RAS biosolids and microbial biofilms. ...

Fillet quality and processing attributes of postsmolt Atlantic salmon, Salmo salar, fed a fishmeal-free diet and a fishmeal-based diet in recirculation aquaculture systems

USDA-ARS?s Scientific Manuscript database

Many studies have evaluated the adequacy of alternate ingredient diets for Atlantic salmon, Salmo salar, mainly with focus on fish performance and health; however, comprehensive analysis of fillet quality is lacking, particularly for salmon fed these diets in recirculation aquaculture systems (RAS)....

Characterization of Mycobacterium salmoniphilum as causal agent of mycobacteriosis in Atlantic salmon, Salmo salar L., from a freshwater recirculation system.

PubMed

Aro, L; Correa, K; Martínez, A; Ildefonso, R; Yáñez, J M

2014-04-01

Thirty Atlantic salmon, Salmo salar L., with low corporal condition relative to other fish present in the culture system, were sampled from a freshwater recirculation pisciculture located in Chile. The most characteristic signs and lesions were cachexia and presence of multiple greyish-white granulomas within internal organs. The external and internal lesions, along with the microscopic, histologic and biochemical findings, were consistent with mycobacteriosis. The identification of Mycobacterium salmoniphilum as the causal agent of the lesions was possible through the use of molecular analyses. This study represents the first report of Mycobacterium salmoniphilum in a freshwater recirculation system and the first case of fish mycobacteriosis described in Chile. © 2013 John Wiley & Sons Ltd.

Heat recirculating cooler for fluid stream pollutant removal

DOEpatents

Richards, George A.; Berry, David A.

2008-10-28

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.

Evaluation of depuration procedures to mitigate the off-flavor compounds geosmin and 2-methylisoborneol from Atlantic salmon Salmo salar raised to market-size in recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

Fish cultured within water recirculating aquaculture systems (RAS) can acquire “earthy” or “musty” off-flavors due to bioaccumulation of the compounds geosmin and 2-methylisoborneol (MIB), respectively, which are produced by certain bacterial species present in RAS biosolids and microbial biofilms. ...

Effects of pH on biomass, geosmin, and 2-methylisoborneol production and cellular activity by Streptomyces luridiscabiei isolated from a rainbow trout recirculating aquaculture system

USDA-ARS?s Scientific Manuscript database

Rainbow trout (Oncorhynchus mykiss) grown in recirculating aquaculture systems (RAS) can acquire “earthy” and “musty” taints due to bioaccumulation of geosmin and 2-methyisoborneol (MIB), respectively, in the fish flesh. Certain species of actinomycetes which produce these compounds are attributed a...

The effects of long-term 20 mg/L carbon dioxide exposure on the health and performance of Atlantic salmon Salmo salar post-smolts in water recirculation aquaculture systems

USDA-ARS?s Scientific Manuscript database

Previous research and experience has linked elevated dissolved carbon dioxide (CO2) to reduced growth performance, poor feed conversion, and a variety of health issues in farm-raised fish, including Atlantic salmon Salmo salar. Supplemental control measures in water recirculation aquaculture systems...

Carbon and nutrient removal from on-site wastewater using extended-aeration activated sludge and ion exchange.

PubMed

Safferman, Steven I; Burks, Bennette D; Parker, Robert A

2004-01-01

The need to improve on-site wastewater treatment processes is being realized as populations move into more environmentally sensitive regions and regulators adopt the total maximum daily load approach to watershed management. Under many conditions, septic systems do not provide adequate treatment; therefore, advanced systems are required. These systems must remove significant amounts of biochemical oxygen demand (BOD) and suspended solids, and substantially nitrify, denitrify, and remove phosphorus. Many existing advanced on-site wastewater systems effectively remove BOD, suspended solids, and ammonia, but few substantially denitrify and uptake phosphorus. The purpose of this research was to design and test modifications to an existing on-site wastewater treatment system to improve denitrification and phosphorus removal. The Nayadic (Consolidated Treatment Systems, Inc., Franklin, Ohio), an established, commercially available, extended-aeration, activated sludge process, was used to represent a typical existing system. Several modifications were considered based on a literature review, and the option with the best potential was tested. To improve denitrification, a supplemental treatment tank was installed before the Nayadic and a combination flow splitter, sump, and pump box with a recirculation system was installed after it. A recirculation pump returned a high proportion of the system effluent back to the supplemental treatment tank. Two supplemental treatment tank sizes, three flowrates, and three recirculation rates were tested. Actual wastewater was dosed as brief slugs to the system in accordance with a set schedule. Several ion-exchange resins housed in a contact column were tested on the effluent for their potential to remove phosphorus. Low effluent levels of five-day biochemical oxygen demand, suspended solids, and total nitrogen were achieved and substantial phosphorous removal was also achieved using a 3780-L supplemental treatment tank, a recirculation ratio of 5:1, and a fine-grain activated aluminum-oxide-exchange media. Good results were also obtained with an 1890-L supplemental treatment tank and a recirculation ratio of 3:1. The most significant benefit of the supplemental treatment tank, in combination with the recirculation system, appears to be the low nitrogen concentration dosed to the Nayadic. By reducing the nitrogen concentration and spreading out its mass over time during no-flow periods, the Nayadic's inherent low-level denitrifying capacity was more closely matched and effective treatment was achieved.

Zero-G Thermodynamic Venting System (TVS) Performance Prediction Program

NASA Technical Reports Server (NTRS)

Nguyen, Han

1994-01-01

This report documents the Zero-g Thermodynamic Venting System (TVS) performance prediction computer program. The zero-g TVS is a device that destratifies and rejects environmentally induced zero-g thermal gradients in the LH2 storage transfer system. A recirculation pump and spray injection manifold recirculates liquid throughout the length of the tank thereby destratifying both the ullage gas and liquid bulk. Heat rejection is accomplished by the opening of the TVS control valve which allows a small flow rate to expand to a low pressure thereby producing a low temperature heat sink which is used to absorb heat from the recirculating liquid flow. The program was written in FORTRAN 77 language on the HP-9000 and IBM PC computers. It can be run on various platforms with a FORTRAN compiler.

A dented LH2 recirculation line is removed from Discovery

NASA Technical Reports Server (NTRS)

1999-01-01

Workers with United Space Alliance remove Shuttle Discovery's dented main propulsion system liquid hydrogen recirculation line. From left are James Stickley, George Atkins, and Todd Biddle. The 12-inch-long dent was discovered during routine aft compartment inspections Tuesday, Dec. 7. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. The line is being replaced and managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope.

Reduced bleed air extraction for DC-10 cabin air conditioning

NASA Technical Reports Server (NTRS)

Newman, W. H.; Viele, M. R.; Hrach, F. J.

1980-01-01

It is noted that a significant fuel savings can be achieved by reducing bleed air used for cabin air conditioning. Air in the cabin can be recirculated to maintain comfortable ventilation rates but the quality of the air tends to decrease due to entrainment of smoke and odors. Attention is given to a development system designed and fabricated under the NASA Engine Component Improvement Program to define the recirculation limit for the DC-10. It is shown that with the system, a wide range of bleed air reductions and recirculation rates is possible. A goal of 0.8% fuel savings has been achieved which results from a 50% reduction in bleed extraction from the engine.

Suicidal intoxication with potassium chlorate successfully treated with renal replacement therapy and extracorporeal liver support.

PubMed

Sein Anand, Jacek; Barwina, Małgorzata; Zajac, Maciej; Kaletha, Krystian

2012-01-01

We present a case of a 22-year-old male who, in a suicide attempt, ingested approximately 200 g of potassium chlorate. Upon admission to the hospital, he presented in full respiratory failure with cyanosis. Methylene blue antidote was given but found to be ineffective. The patient was intubated and mechanical ventilation was initiated. Because of renal failure with anuria, intermittent haemodialysis (iHD) followed by continuous venovenous hemodiafiltration (CVVHDF) was performed. His hospital stay was also complicated by hemolysis, disseminated intravascular coagulation, and atrial fibrillation. Transfusions of packed red blood cells, platelets, and fresh frozen plasma were necessary to correct the deficits. He also developed liver failure and required two sessions of molecular adsorbent recirculating system (MARS) therapy. On day 14 of his hospitalization, he regained consciousness, as well as full respiratory and circulatory function. There are no controlled studies addressing management of potassium chlorate poisoning. We suggest that early renal replacement therapy should be strongly considered.

Beam dynamics simulation of a double pass proton linear accelerator

DOE PAGES

Hwang, Kilean; Qiang, Ji

2017-04-03

A recirculating superconducting linear accelerator with the advantage of both straight and circular accelerator has been demonstrated with relativistic electron beams. The acceleration concept of a recirculating proton beam was recently proposed and is currently under study. In order to further support the concept, the beam dynamics study on a recirculating proton linear accelerator has to be carried out. In this paper, we study the feasibility of a two-pass recirculating proton linear accelerator through the direct numerical beam dynamics design optimization and the start-to-end simulation. This study shows that the two-pass simultaneous focusing without particle losses is attainable including fullymore » 3D space-charge effects through the entire accelerator system.« less

Lunar Water Resource Demonstration (LWRD) Test Results

NASA Technical Reports Server (NTRS)

Muscatello, Anthony C.; Captain, Janine E.; Quinn, Jacqueline W.; Gibson, Tracy L.; Perusich, Stephen A.; Weis, Kyle H.

2009-01-01

NASA has undertaken the In-Situ Resource Utilization (lSRU) project called RESOLVE (Regolith and Environment Science & Oxygen and Lunar Volatile Extraction). This project is an Earth-based lunar precursor demonstration of a system that could be sent to explore permanently shadowed polar lunar craters, where it would drill into regolith, quantify the volatiles that are present, and extract oxygen by hydrogen reduction of iron oxides. The RESOLVE chemical processing system was mounted within the CMU rover "Scarab" and successfully demonstrated on Hawaii's Mauna Kea volcano in November 2008. This technology could be used on Mars as well. As described at the 2008 Mars Society Convention, the Lunar Water Resource Demonstration (LWRD) supports the objectives of the RESOLVE project by capturing and quantifying water and hydrogen released by regolith upon heating. Field test results for the quantification of water using LWRD showed that the volcanic ash (tephra) samples contained 0.15-0.41% water, in agreement with GC water measurements. Reduction of the RH in the surge tank to near zero during recirculation show that the water is captured by the water beds as desired. The water can be recovered by heating the Water Beds to 230 C or higher. Test results for the capture and quantification of pure hydrogen have shown that over 90% of the hydrogen can be captured and 98% of the absorbed hydrogen can be recovered upon heating the hydride to 400 C and desorbing the hydrogen several times into the evacuated surge tank. Thus, the essential requirement of capturing hydrogen and recovering it has been demonstrated. ,

Investigating the influence of nitrate nitrogen on post-smolt Atlantic salmon Salmo salar reproductive physiology in freshwater recirculation aquaculture systems

USDA-ARS?s Scientific Manuscript database

An 8-month trial was carried out to assess the effects of NO3-N on a variety of performance and physiological outcomes in post-smolt Atlantic salmon Salmo salar (initial weight 102 plus or minus 1 g) reared in six replicated laboratory-scale water recirculation aquaculture systems (RAS). Three RAS r...

Walleye Sander vitreus performance, water quality, and waste production in replicated recirculation aquaculture systems when feeding a low phosphorus diet without fishmeal versus a traditional fishmeal-based diet

USDA-ARS?s Scientific Manuscript database

Walleye Sander vitreus is a popular sport- and food-fish in areas surrounding the Great Lakes. Walleye are mainly provided as food-fish by limited capture fisheries, but have potential for profitable production to market-size in recirculation aquaculture systems (RAS). Walleye are piscivorous with a...

Effect of high-pressure homogenization preparation on mean globule size and large-diameter tail of oil-in-water injectable emulsions.

PubMed

Peng, Jie; Dong, Wu-Jun; Li, Ling; Xu, Jia-Ming; Jin, Du-Jia; Xia, Xue-Jun; Liu, Yu-Ling

2015-12-01

The effect of different high pressure homogenization energy input parameters on mean diameter droplet size (MDS) and droplets with > 5 μm of lipid injectable emulsions were evaluated. All emulsions were prepared at different water bath temperatures or at different rotation speeds and rotor-stator system times, and using different homogenization pressures and numbers of high-pressure system recirculations. The MDS and polydispersity index (PI) value of the emulsions were determined using the dynamic light scattering (DLS) method, and large-diameter tail assessments were performed using the light-obscuration/single particle optical sensing (LO/SPOS) method. Using 1000 bar homogenization pressure and seven recirculations, the energy input parameters related to the rotor-stator system will not have an effect on the final particle size results. When rotor-stator system energy input parameters are fixed, homogenization pressure and recirculation will affect mean particle size and large diameter droplet. Particle size will decrease with increasing homogenization pressure from 400 bar to 1300 bar when homogenization recirculation is fixed; when the homogenization pressure is fixed at 1000 bar, the particle size of both MDS and percent of fat droplets exceeding 5 μm (PFAT 5 ) will decrease with increasing homogenization recirculations, MDS dropped to 173 nm after five cycles and maintained this level, volume-weighted PFAT 5 will drop to 0.038% after three cycles, so the "plateau" of MDS will come up later than that of PFAT 5 , and the optimal particle size is produced when both of them remained at plateau. Excess homogenization recirculation such as nine times under the 1000 bar may lead to PFAT 5 increase to 0.060% rather than a decrease; therefore, the high-pressure homogenization procedure is the key factor affecting the particle size distribution of emulsions. Varying storage conditions (4-25°C) also influenced particle size, especially the PFAT 5 . Copyright © 2015. Published by Elsevier B.V.

Conceptual design of the cryogenic system and estimation of the recirculated power for CFETR

NASA Astrophysics Data System (ADS)

Liu, Xiaogang; Qiu, Lilong; Li, Junjun; Wang, Zhaoliang; Ren, Yong; Wang, Xianwei; Li, Guoqiang; Gao, Xiang; Bi, Yanfang

2017-01-01

The China Fusion Engineering Test Reactor (CFETR) is the next tokamak in China’s roadmap for realizing commercial fusion energy. The CFETR cryogenic system is crucial to creating and maintaining operational conditions for its superconducting magnet system and thermal shields. The preliminary conceptual design of the CFETR cryogenic system has been carried out with reference to that of ITER. It will provide an average capacity of 75 to 80 kW at 4.5 K and a peak capacity of 1300 kW at 80 K. The electric power consumption of the cryogenic system is estimated to be 24 MW, and the gross building area is about 7000 m2. The relationships among the auxiliary power consumed by the cryogenic system, the fusion power gain and the recirculated power of CFETR are discussed, with the suggestion that about 52% of the electric power produced by CFETR in phase II must be recirculated to run the fusion test reactor.

Building America Case Study: Control Retrofits for Multifamily Domestic Hot Water Recirculation Systems, Brooklyn, New York

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

Domestic hot water (DHW) heating is the second largest energy end use in U.S. buildings, exceeded only by space conditioning. Recirculation systems consisting of a pump and piping loop(s) are commonly used in multifamily buildings to reduce wait time for hot water at faucets; however, constant pumping increases energy consumption by exposing supply and return line piping to continuous heat loss, even during periods when there is no demand for hot water. In this study, ARIES installed and tested two types of recirculation controls in a pair of buildings in order to evaluate their energy savings potential. Demand control, temperaturemore » modulation controls, and the simultaneous operation of both were compared to the baseline case of constant recirculation. Additionally, interactive effects between DHW control fuel reductions and space conditioning (heating and cooling) were estimated in order to make more realistic predictions of the payback and financial viability of retrofitting DHW systems with these controls. Results showed that DHW fuel consumption reduced by 7 percent after implementing the demand control technique, 2 percent after implementing temperature modulation, and 15 percent after implementing demand control and temperature modulation techniques simultaneously; recirculation pump runtime was reduced to 14 minutes or less per day. With space heating and cooling interactions included, the estimated annual cost savings were 8 percent, 1 percent, and 14 percent for the respective control techniques. Possible complications in the installation, commissioning and operation of the controls were identified and solutions offered.« less

Building America Case Study: Control Retrofits for Multifamily Domestic Hot Water Recirculation Systems, Brooklyn, New York

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

J. Dentz; E. Ansanelli, H. Henderson, Jr.; K. Varshney

Domestic hot water (DHW) heating is the second largest energy end use in U.S. buildings, exceeded only by space conditioning. Recirculation systems consisting of a pump and piping loop(s) are commonly used in multifamily buildings to reduce wait time for hot water at faucets; however, constant pumping increases energy consumption by exposing supply and return line piping to continuous heat loss, even during periods when there is no demand for hot water. In this study, ARIES installed and tested two types of recirculation controls in a pair of buildings in order to evaluate their energy savings potential. Demand control, temperaturemore » modulation controls, and the simultaneous operation of both were compared to the baseline case of constant recirculation. Additionally, interactive effects between DHW control fuel reductions and space conditioning (heating and cooling) were estimated in order to make more realistic predictions of the payback and financial viability of retrofitting DHW systems with these controls. Results showed that DHW fuel consumption reduced by 7% after implementing the demand control technique, 2% after implementing temperature modulation, and 15% after implementing demand control and temperature modulation techniques simultaneously; recirculation pump runtime was reduced to 14 minutes or less per day. With space heating and cooling interactions included, the estimated annual cost savings were 8%, 1%, and 14% for the respective control techniques. Possible complications in the installation, commissioning and operation of the controls were identified and solutions offered.« less

Changes in sex steroids, growth hormone, and insulin-like growth factor-I during ovarian development in Rainbow Trout cultured within a recirculating system with 24-hour Light

USDA-ARS?s Scientific Manuscript database

Female rainbow trout (Onchorynchus mykiss) were cultured within a freshwater recirculating aquaculture system under 24-h constant lighting in 13oC water, and they were fed every six hours to near satiation. An opaque roof allowed surface light intensity to vary between <200 to ~1500 lx. Growth per...

Performance of Water Recirculation Loop Maintenance Components for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Rector, Tony; Peyton, Barbara M.; Steele, John W.; Makinen, Janice; Bue, Grant C.; Campbell, Colin

2014-01-01

Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Performance of Water Recirculation Loop Maintentance Components for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Rector, Tony; Peyton, Barbara; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2014-01-01

Water loop maintenance components to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop have undergone a comparative performance evaluation with a second SWME water recirculation loop with no water quality maintenance. Results show the benefits of periodic water maintenance. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the evaluation of water recirculation maintenance components was to further enhance this advantage through the leveraging of fluid loop management lessonslearned from the International Space Station (ISS). A bed design that was developed for a UTAS military application, and considered for a potential ISS application with the Urine Processor Assembly, provided a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance cycle included the use of a biocide delivery component developed for ISS to introduce a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Comprehensive Evaluation of Biological Growth Control by Chlorine-Based Biocides in Power Plant Cooling Systems Using Tertiary Effluent

PubMed Central

Chien, Shih-Hsiang; Dzombak, David A.; Vidic, Radisav D.

2013-01-01

Abstract Recent studies have shown that treated municipal wastewater can be a reliable cooling water alternative to fresh water. However, elevated nutrient concentration and microbial population in wastewater lead to aggressive biological proliferation in the cooling system. Three chlorine-based biocides were evaluated for the control of biological growth in cooling systems using tertiary treated wastewater as makeup, based on their biocidal efficiency and cost-effectiveness. Optimal chemical regimens for achieving successful biological growth control were elucidated based on batch-, bench-, and pilot-scale experiments. Biocide usage and biological activity in planktonic and sessile phases were carefully monitored to understand biological growth potential and biocidal efficiency of the three disinfectants in this particular environment. Water parameters, such as temperature, cycles of concentration, and ammonia concentration in recirculating water, critically affected the biocide performance in recirculating cooling systems. Bench-scale recirculating tests were shown to adequately predict the biocide residual required for a pilot-scale cooling system. Optimal residuals needed for proper biological growth control were 1, 2–3, and 0.5–1 mg/L as Cl2 for NaOCl, preformed NH2Cl, and ClO2, respectively. Pilot-scale tests also revealed that Legionella pneumophila was absent from these cooling systems when using the disinfectants evaluated in this study. Cost analysis showed that NaOCl is the most cost-effective for controlling biological growth in power plant recirculating cooling systems using tertiary-treated wastewater as makeup. PMID:23781129

Comprehensive Evaluation of Biological Growth Control by Chlorine-Based Biocides in Power Plant Cooling Systems Using Tertiary Effluent.

PubMed

Chien, Shih-Hsiang; Dzombak, David A; Vidic, Radisav D

2013-06-01

Recent studies have shown that treated municipal wastewater can be a reliable cooling water alternative to fresh water. However, elevated nutrient concentration and microbial population in wastewater lead to aggressive biological proliferation in the cooling system. Three chlorine-based biocides were evaluated for the control of biological growth in cooling systems using tertiary treated wastewater as makeup, based on their biocidal efficiency and cost-effectiveness. Optimal chemical regimens for achieving successful biological growth control were elucidated based on batch-, bench-, and pilot-scale experiments. Biocide usage and biological activity in planktonic and sessile phases were carefully monitored to understand biological growth potential and biocidal efficiency of the three disinfectants in this particular environment. Water parameters, such as temperature, cycles of concentration, and ammonia concentration in recirculating water, critically affected the biocide performance in recirculating cooling systems. Bench-scale recirculating tests were shown to adequately predict the biocide residual required for a pilot-scale cooling system. Optimal residuals needed for proper biological growth control were 1, 2-3, and 0.5-1 mg/L as Cl 2 for NaOCl, preformed NH 2 Cl, and ClO 2 , respectively. Pilot-scale tests also revealed that Legionella pneumophila was absent from these cooling systems when using the disinfectants evaluated in this study. Cost analysis showed that NaOCl is the most cost-effective for controlling biological growth in power plant recirculating cooling systems using tertiary-treated wastewater as makeup.

Preoperational test report, recirculation ventilation systems

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

Clifton, F.T.

1997-11-11

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

Dedicated exhaust gas recirculation control systems and methods

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

Sczomak, David P.; Narayanaswamy, Kushal; Keating, Edward J.

An engine control system of a vehicle includes a fuel control module that controls fuel injection of a first cylinder of an engine based on a first target air/fuel ratio that is fuel lean relative to a stoichiometric air/fuel ratio and that controls fuel injection of a second cylinder of the engine based on a second target air/fuel ratio that is fuel rich relative to stoichiometry. The first cylinder outputs exhaust to a first three way catalyst (TWC), and the second cylinder outputs exhaust to an exhaust gas recirculation (EGR) valve. An EGR control module controls opening of the EGRmore » valve to: (i) a second TWC that reacts with nitrogen oxides (NOx) in the exhaust and outputs ammonia to a selective catalytic reduction (SCR) catalyst; and (ii) a conduit that recirculates exhaust back to an intake system of the engine.« less

Engine with exhaust gas recirculation system and variable geometry turbocharger

DOEpatents

Keating, Edward J.

2015-11-03

An engine assembly includes an intake assembly, an internal combustion engine defining a plurality of cylinders and configured to combust a fuel and produce exhaust gas, and an exhaust assembly in fluid communication with a first subset of the plurality of cylinders. Each of the plurality of cylinders are provided in fluid communication with the intake assembly. The exhaust assembly is provided in fluid communication with a first subset of the plurality of cylinders, and a dedicated exhaust gas recirculation system in fluid communication with both a second subset of the plurality of cylinders and with the intake assembly. The dedicated exhaust gas recirculation system is configured to route all of the exhaust gas from the second subset of the plurality of cylinders to the intake assembly. Finally, the engine assembly includes a turbocharger having a variable geometry turbine in fluid communication with the exhaust assembly.

Stocking density effects on production characteristics and body composition of market size cobia, Rachycentron canadum, reared in recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

Production density in excess of a critical threshold can result in a negative relationship between stocking density and fish production. This study was conducted to evaluate production characteristics of juvenile cobia Rachycentron canadum, reared to market size in production-scale recirculating aq...

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

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

Tallec, G.; Bureau, C.; Peu, P.

2009-07-15

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

Case study of controlled recirculation at a Wyoming trona mine

PubMed Central

Pritchard, C.; Scott, D.; Frey, G.

2015-01-01

Controlled recirculation has been used in the metal/nonmetal mining industry for energy savings when heating and cooling air, in undersea mining and for increasing airflow to mining areas. For safe and effective use of controlled district recirculation, adequate airflow to dilute contaminants must exist prior to implementation, ventilation circuit parameters must be accurately quantified, ventilation network modeling must be up to date, emergency planning scenarios must be performed and effective monitoring and control systems must be installed and used. Safety and health issues that must be considered and may be improved through the use of controlled district recirculation include blasting fumes, dust, diesel emissions, radon and contaminants from mine fires. Controlled recirculation methods are expected to become more widely used as mines reach greater working depths, requiring that these health and safety issues be well understood. The U.S. National Institute for Occupational Safety and Health (NIOSH) conducted two controlled recirculation tests over three days at a Wyoming trona mine, utilizing an inline booster fan to improve airflow to a remote and difficult-to-ventilate development section. Test results were used to determine the effect that recirculation had on air qualities and quantities measured in that section and in other adjacent areas. Pre-test conditions, including ventilation quantities and pressures, were modeled using VnetPC. During each test, ventilation quantities and pressures were measured, as well as levels of total dust. Sulfur hexafluoride (SF6) tracer gas was used to simulate a mine contaminant to monitor recirculation wave cycles. Results showed good correlation between the model results and measured values for airflows, pressure differentials, tracer gas arrival times, mine gasses and dust levels. PMID:26251567

Impact of different supply air and recirculating air filtration systems on stable climate, animal health, and performance of fattening pigs in a commercial pig farm

PubMed Central

Wenke, Cindy; Pospiech, Janina; Reutter, Tobias; Altmann, Bettina; Truyen, Uwe

2018-01-01

Biosecurity is defined as the implementation of measures that reduce the risk of disease agents being introduced and/or spread. For pig production, several of these measures are routinely implemented (e.g. cleaning, disinfection, segregation). However, air as a potential vector of pathogens has long been disregarded. Filters for incoming and recirculating air were installed into an already existing ventilation plant at a fattening piggery (3,840 pigs at maximum) in Saxony, Germany. Over a period of three consecutive fattening periods, we evaluated various parameters including air quality indices, environmental and operating parameters, and pig performance. Animal data regarding respiratory diseases, presence of antibodies against influenza A viruses, PRRSV, and Actinobacillus pleuropneumoniae and lung health score at slaughter were recorded, additionally. There were no significant differences (p = 0.824) in total bacterial counts between barns with and without air filtration. Recirculating air filtration resulted in the lowest total dust concentration (0.12 mg/m3) and lung health was best in animals from the barn equipped with recirculating air filtration modules. However, there was no difference in animal performance. Antibodies against all above mentioned pathogens were detected but mostly animals were already antibody-positive at re-stocking. We demonstrated that supply air filtration as well as recirculating air filtration technique can easily be implemented in an already existing ventilation system and that recirculating air filtration resulted in enhanced lung health compared to supply air-filtered and non-filtered barns. A more prominent effect might have been obtained in a breeding facility because of the longer life span of sows and a higher biosecurity level with air filtration as an add-on measure. PMID:29558482

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

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

Bruno, Mike S.; Detwiler, Russell L.; Lao, Kang

2012-12-13

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. The primary objectives of this DOE research effort are to develop and document optimum design configurations and operating practices to produce geothermal power from hot permeable sedimentary and crystalline formations using advancedmore » horizontal well recirculation systems. During Phase I of this research project Terralog Technologies USA and The University of California, Irvine (UCI), have completed preliminary investigations and documentation of 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. We have also identified significant geologic resources appropriate for application of such technology. The main challenge for such recirculation systems is to optimize both the design configuration and the operating practices for cost-effective geothermal energy recovery. These will be strongly influenced by sedimentary formation properties, including thickness and dip, temperature, thermal conductivity, heat capacity, permeability, and porosity; and by working fluid properties.« less

Marginal costs of water savings from cooling system retrofits: a case study for Texas power plants

NASA Astrophysics Data System (ADS)

Loew, Aviva; Jaramillo, Paulina; Zhai, Haibo

2016-10-01

The water demands of power plant cooling systems may strain water supply and make power generation vulnerable to water scarcity. Cooling systems range in their rates of water use, capital investment, and annual costs. Using Texas as a case study, we examined the cost of retrofitting existing coal and natural gas combined-cycle (NGCC) power plants with alternative cooling systems, either wet recirculating towers or air-cooled condensers for dry cooling. We applied a power plant assessment tool to model existing power plants in terms of their key plant attributes and site-specific meteorological conditions and then estimated operation characteristics of retrofitted plants and retrofit costs. We determined the anticipated annual reductions in water withdrawals and the cost-per-gallon of water saved by retrofits in both deterministic and probabilistic forms. The results demonstrate that replacing once-through cooling at coal-fired power plants with wet recirculating towers has the lowest cost per reduced water withdrawals, on average. The average marginal cost of water withdrawal savings for dry-cooling retrofits at coal-fired plants is approximately 0.68 cents per gallon, while the marginal recirculating retrofit cost is 0.008 cents per gallon. For NGCC plants, the average marginal costs of water withdrawal savings for dry-cooling and recirculating towers are 1.78 and 0.037 cents per gallon, respectively.

Commercialization of the Stone and Webster/Conoco SCB technology

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

Stone, R.C.; Johnson, W.B.; Ratliff, B.D.

1982-06-01

Stone and Webster have developed a second generation recirculating fluidized bed boiler system, named Solids Circulation Boiler (SCB). The heart of the system is the recirculating fluidized bed, which is schematized, and explained. In November 1981 Conoco announced plans to construct an SCB at Lake Charles LA. Preliminary plot plan and elevation drawings are provided. The advantages of SCB are its rapid and controlled turn on and turn down capability, high carbon efficiency, simple coal and limestone feed system, high sulphur capture, compact design, and low NOx emission.

77 FR 20059 - License Amendment To Increase the Maximum Reactor Power Level, Florida Power & Light Company...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-03

... surface evaporation. The canals are a closed recirculating loop that serves as the ultimate heat sink for...) for water discharges to an onsite closed-loop recirculation cooling canal system. The seasonal... to 90 [deg]F (21 [deg]C to 32 [deg]C). Additionally, the CCS water is hyper-saline (twice the...

Glovebox stripper system tritium capture efficiency-literature review

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

James, D. W.; Poore, A. S.

2015-09-28

Glovebox Stripper Systems (GBSS) are intended to minimize tritium emissions from glovebox confinement systems in Tritium facilities. A question was raised to determine if an assumed 99% stripping (decontamination) efficiency in the design of a GBBS was appropriate. A literature review showed the stated 99% tritium capture efficiency used for design of the GBSS is reasonable. Four scenarios were indicated for GBSSs. These include release with a single or dual stage setup which utilizes either single-pass or recirculation for stripping purposes. Examples of single-pass as well as recirculation stripper systems are presented and reviewed in this document.

A dented LH2 recirculation line is removed from Discovery

NASA Technical Reports Server (NTRS)

1999-01-01

In the Payload Changeout Room, Launch Pad 39B, United Space Alliance and NASA workers look at the replacement main propulsion system liquid hydrogen recirculation line (left) to be installed in Shuttle Discovery's aft compartment. At right is the dented line that has been removed. The 12-inch-long dent was discovered during routine aft compartment inspections Tuesday, Dec. 7. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. The line is being replaced and managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope.

Design Concept for a Compact ERL to Drive a VUV/Soft X-Ray FEL

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

Christopher Tennant ,David Douglas

2011-03-01

We explore possible upgrades of the existing Jefferson Laboratory IR/UV FEL driver to higher electron beam energy and shorter wavelength through use of multipass recirculation to drive an amplifier FEL. The system would require beam energy at the wiggler of 600 MeV with 1 mA of average current. The system must generate a high brightness beam, configure it appropriately, and preserve beam quality through the acceleration cycle ? including multiple recirculations ? and appropriately manage the phase space during energy recovery. The paper will discuss preliminary design analysis of the longitudinal match, space charge effects in the linac, and recirculatormore » design issues, including the potential for the microbunching instability. A design concept for the low energy recirculator and an emittance preserving lattice solution will be presented.« less

Method and device for measuring single-shot transient signals

DOEpatents

Yin, Yan

2004-05-18

Methods, apparatus, and systems, including computer program products, implementing and using techniques for measuring multi-channel single-shot transient signals. A signal acquisition unit receives one or more single-shot pulses from a multi-channel source. An optical-fiber recirculating loop reproduces the one or more received single-shot optical pulses to form a first multi-channel pulse train for circulation in the recirculating loop, and a second multi-channel pulse train for display on a display device. The optical-fiber recirculating loop also optically amplifies the first circulating pulse train to compensate for signal losses and performs optical multi-channel noise filtration.

Characterization of a joint recirculation of concentrated leachate and leachate to landfills with a microaerobic bioreactor for leachate treatment.

PubMed

He, Ruo; Wei, Xiao-Meng; Tian, Bao-Hu; Su, Yao; Lu, Yu-Lan

2015-12-01

With comparison of a traditional landfill, a joint recirculation of concentrated leachate and leachate to landfills with or without a microaerobic reactor for leachate treatment was investigated in this study. The results showed that the joint recirculation of concentrated leachate and leachate with a microaerobic reactor for leachate treatment could not only utilize the microaerobic reactor to buffer the fluctuation of quality and quantity of leachate during landfill stabilization, but also reduce the inhibitory effect of acidic pH and high concentrations of ammonium in recycled liquid on microorganisms and accelerate the degradation of landfilled waste. After 390 days of operation, the discharge of COD and total nitrogen (TN) from the landfill with leachate pretreatment by a microaerobic reactor was 7.4 and 0.9 g, respectively, which accounted for 0.7% and 2.6% of COD, 1.9% and 7.5% of the TN discharge from the landfills without recirculation and directly recirculated with leachate and concentrated leachate, respectively. The degradation of the organic matter and biodegradable matter (BDM) in the landfill reactors could fit well with the first-order kinetics. The highest degradation of the organic matter and BDM was observed in the joint recirculation system with a microaerobic reactor for leachate treatment with the degradation constant of the first-order kinetics of 0.001 and 0.002. Copyright © 2015 Elsevier Ltd. All rights reserved.

Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2013-01-01

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2012-01-01

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high-capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit Transport Water Loop. The bed design further leverages a sorbent developed for the ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System. The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of crewed spaceflight Environmental Control and Life Support System hardware.

Design and Evaluation of a Water Recirculation Loop Maintenance Device for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Steele, John W.; Rector, Tony; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2011-01-01

A dual-bed device to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been designed and is undergoing testing. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the development of a water recirculation maintenance device is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The bed design further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a clear demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware.

Performance of a Water Recirculation Loop Maintenance Device and Process for the Advanced Spacesuit Water Membrane Evaporator

NASA Technical Reports Server (NTRS)

Rector, Tony; Steele, John W.; Bue, Grant C.; Campbell, Colin; Makinen, Janice

2012-01-01

A water loop maintenance device and process to maintain the water quality of the Advanced Spacesuit Water Membrane Evaporation (SWME) water recirculation loop has been undergoing a performance evaluation. The SWME is a heat rejection device under development at the NASA Johnson Space Center to perform thermal control for advanced spacesuits. One advantage to this technology is the potential for a significantly greater degree of tolerance to contamination when compared to the existing Sublimator technology. The driver for the water recirculation maintenance device and process is to further enhance this advantage through the leveraging of fluid loop management lessons-learned from the International Space Station (ISS). A bed design that was developed for a Hamilton Sundstrand military application, and considered for a potential ISS application with the Urine Processor Assembly, provides a low pressure drop means for water maintenance in a recirculation loop. The bed design is coupled with high capacity ion exchange resins, organic adsorbents, and a cyclic methodology developed for the Extravehicular Mobility Unit (EMU) Transport Water loop. The maintenance process further leverages a sorbent developed for ISS that introduces a biocide in a microgravity-compatible manner for the Internal Active Thermal Control System (IATCS). The leveraging of these water maintenance technologies to the SWME recirculation loop is a unique demonstration of applying the valuable lessons learned on the ISS to the next generation of manned spaceflight Environmental Control and Life Support System (ECLSS) hardware. This

Engine bleed air reduction in DC-10

NASA Technical Reports Server (NTRS)

Newman, W. H.; Viele, M. R.

1980-01-01

An 0.8 percent fuel savings was achieved by a reduction in engine bleed air through the use of cabin air recirculation. The recirculation system was evaluated in revenue service on a DC-10. The cabin remained comfortable with reductions in cabin fresh air (engine bleed air) as much as 50 percent. Flight test verified the predicted fuel saving of 0.8 percent.

Removal of Nutrients from Septic Effluent with Re-circulated Hybrid Tidal Flow Constructed Wetland

Treesearch

Lihua Cui; Jigkun Feng; Ying Ouyang; Peiwen Deng

2012-01-01

Hybrid tidal flow constructed wetland (CW) with recirculation is an improved biological and engineering technique for removal of excess nutrients and certain pollutants from wastewater. This study investigated the removal efficiency of total phosphorus (TP), ammonia-nitrogen (NH3-N), and total nitrogen (TN) from septic tank effluent with the hybrid tidal flow CW system...

Bioartificial liver: current status.

PubMed

Pless, G; Sauer, I M

2005-11-01

Liver failure remains a life-threatening syndrome. With the growing disparity between the number of suitable donor organs and the number of patients awaiting transplantation, efforts have been made to optimize the allocation of organs, to find alternatives to cadaveric liver transplantation, and to develop extracorporeal methods to support or replace the function of the failing organ. An extracorporeal liver support system has to provide the main functions of the liver: detoxification, synthesis, and regulation. The understanding that the critical issue of the clinical syndrome in liver failure is the accumulation of toxins not cleared by the failing liver led to the development of artificial filtration and adsorption devices (artificial liver support). Based on this hypothesis, the removal of lipophilic, albumin-bound substances, such as bilirubin, bile acids, metabolites of aromatic amino acids, medium-chain fatty acids, and cytokines, should be beneficial to the clinical course of a patient in liver failure. Artificial detoxification devices currently under clinical evaluation include the Molecular Adsorbent Recirculating System (MARS), Single-Pass Albumin Dialysis (SPAD), and the Prometheus system. The complex tasks of regulation and synthesis remain to be addressed by the use of liver cells (bioartificial liver support). The Extracorporeal Liver Assist Device (ELAD), HepatAssist, Modular Extracorporeal Liver Support system (MELS), and the Amsterdam Medical Center Bioartificial Liver (AMC-BAL) are bioartificial systems. This article gives a brief overview on these artificial and bioartificial devices and discusses remaining obstacles.

The benefits of flue gas recirculation in waste incineration.

PubMed

Liuzzo, Giuseppe; Verdone, Nicola; Bravi, Marco

2007-01-01

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%.

Trace Gas Analyzer (TGA) program

NASA Technical Reports Server (NTRS)

1977-01-01

The design, fabrication, and test of a breadboard trace gas analyzer (TGA) is documented. The TGA is a gas chromatograph/mass spectrometer system. The gas chromatograph subsystem employs a recirculating hydrogen carrier gas. The recirculation feature minimizes the requirement for transport and storage of large volumes of carrier gas during a mission. The silver-palladium hydrogen separator which permits the removal of the carrier gas and its reuse also decreases vacuum requirements for the mass spectrometer since the mass spectrometer vacuum system need handle only the very low sample pressure, not sample plus carrier. System performance was evaluated with a representative group of compounds.

Flowing recirculated-water system for inducing laboratory spawning of sea lampreys

USGS Publications Warehouse

Fredricks, Kim T.; Seelye, James G.

1995-01-01

We describe a water-recirculating system for inducing spawning of sea lampreys (Petromyzon marinus) held under laboratory conditions. Water temperature in the system was gradually increased to and maintained at 18 +/- 2 degrees C, the optimal temperature for spawning. About 10% freshwater was added daily to prevent buildup of waste products. Sea lampreys were provided substrate (approximately 3-6 cm in diameter) to build nests, and a water velocity of 0.2-0.3 m/s was maintained with an electric trolling motor. Sea lampreys held in this system exhibited characteristic spawning behavior. Prolarvae produced from artificial fertilization of gametes developed according to the standard timeline.

Enhancing biogas production from anaerobic biodegradation of the organic fraction of municipal solid waste through leachate blending and recirculation.

PubMed

Nair, Arjun; Sartaj, Majid; Kennedy, Kevin; Coelho, Nuno M G

2014-10-01

Leachate recirculation has a profound advantage on biodegradation of the organic fraction of municipal solid waste in landfills. Mature leachate from older sections of landfills (>10 years) and young leachate were blended and added to organic fraction of municipal solid waste in a series of biomethane potential assay experiments with different mixing ratios of mature and young leachate and their effect on biogas production was monitored. The improvement in biogas production was in the range of 19%-41% depending on the ratio of mixing old and new leachate. The results are conclusive that the biogas generation could be improved by blending the old and new leachate in a bioreactor landfill system as compared with a conventional system employed in bioreactor landfills today for recirculating the same age leachate. © The Author(s) 2014.

Monitoring extent of moisture variations due to leachate recirculation in an ELR/bioreactor landfill using resistivity imaging.

PubMed

Manzur, Shahed Rezwan; Hossain, Md Sahadat; Kemler, Vance; Khan, Mohammad Sadik

2016-09-01

Bioreactor or enhanced leachate recirculation (ELR) landfills are designed and operated for accelerated waste stabilization, accelerated decomposition, and an increased rate of gas generation. The major aspects of a bioreactor landfill are the addition of liquid and the recirculation of collected leachate back into the waste mass through the subsurface leachate recirculation system (LRS). The performance of the ELR landfill largely depends on the existing moisture content within the waste mass; therefore, it is of utmost importance to determine the moisture variations within the landfill. Traditionally, the moisture variation of the ELR landfill is determined by collecting samples through a bucket auger boring from the landfill, followed by laboratory investigation. Collecting the samples through a bucket auger boring is time consuming, labor intensive, and cost prohibitive. Moreover, it provides the information for a single point within the waste mass, but not for the moisture distribution within the landfill. Fortunately, 2D resistivity imaging (RI) can be performed to assess the moisture variations within the landfill and provide a continuous image of the subsurface, which can be utilized to evaluate the performance of the ELR landfill. During this study, the 2D resistivity imaging technique was utilized to determine the moisture distribution and moisture movement during the recirculation process of an ELR landfill in Denton, Texas, USA. A horizontal recirculation pipe was selected and monitored periodically for 2.5years, using the RI technique, to investigate the performance of the leachate recirculation. The RI profile indicated that the resistivity of the solid waste decreased as much as 80% with the addition of water/leachate through the recirculation pipe. In addition, the recirculated leachate traveled laterally between 11m and 16m. Based on the resistivity results, it was also observed that the leachate flow throughout the pipe was non-uniform. The non-uniformity of the leachate flow confirms that the flow of leachate through waste is primarily through preferential flow paths due the heterogeneous nature of the waste. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ammonia-oxidizing bacteria and archaea within biofilters of a commercial recirculating marine aquaculture system.

PubMed

Huang, Zhitao; Jiang, Yuli; Song, Xiefa; Hallerman, Eric; Peng, Lei; Dong, Dengpan; Ma, Teng; Zhai, Jieming; Li, Wensheng

2018-02-10

While biofilters are widely used to metabolize ammonia and other wastes in marine recirculating aquaculture systems, the ammonia-oxidizing bacterial and archaeal communities have not been characterized across a diversity of production systems. Using a metagenomics approach, we characterized the ammonia-oxidizing microbiological community of biofilters in a commercial recirculating marine aquaculture system producing hybrid grouper (Epinephelus lanceolatus × E. fuscoguttatus). Cloning and sequencing of the amoA gene showed that nitrifying bacteria included Nitrosomonas europea, N. stercoris, N. cryotolerans, N. eutropha, N. estuarii, eight strains of N. marina, and 15 strains not associated with described species. Nitrifying archaea included eight strains of Nitrosopumilus maritimus, N. koreensis, N. piranensis, N. adriaticus, undescribed congeners, and other undescribed archaea. The species composition of the bacterial and especially the archaeal communities was beyond that yet reported for aquaculture biofilters. While ammonia flux through the respective communities has yet to be estimated, the diverse environmental adaptations of the bacterial and archaeal communities suggest resilience of function under a range of environmental conditions.

Impact of the injection dose of exhaust gases, on work parameters of combustion engine

NASA Astrophysics Data System (ADS)

Marek, W.; Śliwiński, K.

2016-09-01

This article is another one from the series in which were presented research results indicated the possible areas of application of the pneumatic injection using hot combustion gases proposed by Professor Jarnuszkiewicz. This publication present the results of the control system of exhaust gas recirculation. The main aim of this research was to determine the effect of exhaust gas recirculation to the operating parameters of the internal combustion engine on the basis of laboratory measurements. All measurements were performed at a constant engine speed. These conditions correspond to the operation of the motor operating an electrical generator. The study was conducted on the four-stroke two-cylinder engine with spark ignition. The study were specifically tested on the air injection system and therefore the selection of the rotational speed was not bound, as in conventional versions of operating parameters of the electrical machine. During the measurement there were applied criterion which used power control corresponding to the requirements of load power, at minimal values of engine speed. Recirculation value determined by the following recurrent position control valve of the injection doses inflator gas for pneumatic injection system. They were studied and recorded, the impact of dose of gases recirculation to the operating and ecological engine parameters such as power, torque, specific fuel consumption, efficiency, air fuel ratio, exhaust gas temperature and nitrogen oxides and hydrocarbons.

A concentrated solar cavity absorber with direct heat transfer through recirculating metallic particles

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

Sarker, M. R. I., E-mail: islamrabiul@yahoo.com; Saha, Manabendra, E-mail: manabendra.saha@adelaide.edu.au, E-mail: manab04me@gmail.com; Beg, R. A.

A recirculating flow solar particle cavity absorber (receiver) is modeled to investigate the flow behavior and heat transfer characteristics of a novel developing concept. It features a continuous recirculating flow of non-reacting metallic particles (black silicon carbide) with air which are used as a thermal enhancement medium. The aim of the present study is to numerically investigate the thermal behavior and flow characteristics of the proposed concept. The proposed solar particle receiver is modeled using two phase discrete particle model (DPM), RNG k-flow model and discrete ordinate (DO) radiation model. Numerical analysis is carried out considering a solar receiver withmore » only air and the mixture of non-reacting particles and air as a heat transfer as well as heat carrying medium. The parametric investigation is conducted considering the incident solar flux on the receiver aperture and changing air flow rate and recirculation rate inside the receiver. A stand-alone feature of the recirculating flow solar particle receiver concept is that the particles are directly exposed to concentrated solar radiation monotonously through recirculating flow inside the receiver and results in efficient irradiation absorption and convective heat transfer to air that help to achieve high temperature air and consequently increase in thermal efficiency. This paper presents, results from the developed concept and highlights its flow behavior and potential to enhance the heat transfer from metallic particles to air by maximizing heat carrying capacity of the heat transfer medium. The imposed milestones for the present system will be helpful to understand the radiation absorption mechanism of the particles in a recirculating flow based receiver, the thermal transport between the particles, the air and the cavity, and the fluid dynamics of the air and particle in the cavity.« less

Dynamic effect of leachate recirculation on batch mode solid state anaerobic digestion: Influence of recirculated volume, leachate to substrate ratio and recirculation periodicity.

PubMed

Degueurce, Axelle; Trémier, Anne; Peu, Pascal

2016-09-01

Performances of batch mode solid state anaerobic digestion (SSAD) were investigated through several leachate recirculation strategies. Three parameters were shown to particularly influence methane production rates (MPR) and methane yields: the length of the interval between two recirculation events, the leachate to substrate (L:S) ratio and the volume of leachate recirculated. A central composite factor design was used to determine the influence of each parameter on methane production. Results showed that lengthening the interval between two recirculation events reduced methane yield. This effect can be counteracted by recirculating a large volume of leachate at a low L:S ratio. Steady methane production can be obtained by recirculating small amounts of leachate, and by lengthening the interval between two recirculations, regardless of the L:S ratio. However, several combinations of these parameters led to similar performances meaning that leachate recirculation practices can be modified as required by the specific constraints SSAD plants configurations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Advanced deep sea diving equipment

NASA Technical Reports Server (NTRS)

Danesi, W. A.

1972-01-01

Design requirements are generated for a deep sea heavy duty diving system to equip salvage divers with equipment and tools that permit work of the same quality and in times approaching that done on the surface. The system consists of a helmet, a recirculator for removing carbon dioxide, and the diver's dress. The diver controls the inlet flow by the recirculatory control valve and is able to change closed cycle operation to open cycle if malfunction occurs. Proper function of the scrubber in the recirculator minimizes temperature and humidity effects as it filters the returning air.

In-tank recirculating arsenic treatment system

DOEpatents

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

2009-04-07

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.

Understanding Single-Thread Meandering Rivers with High Sinuosity on Mars through Chemical Precipitation Experiments

NASA Astrophysics Data System (ADS)

Lim, Y.; Kim, W.

2015-12-01

Meandering rivers are extremely ubiquitous on Earth, yet it is only recently that single-thread experimental channels with low sinuosity have been created. In these recent experiments, as well as in natural rivers, vegetation plays a crucial role in maintaining a meandering pattern by adding cohesion to the bank and inhibiting erosion. The ancient, highly sinuous channels found on Mars are enigmatic because presumably vegetation did not exist on ancient Mars. Under the hypothesis that Martian meandering rivers formed by chemical precipitation on levees and flood plain deposits, we conducted carbonate flume experiments to investigate the formation and evolution of a single-thread meander pattern without vegetation. The flow recirculating in the flume is designed to accelerate chemical reactions - dissolution of limestone using CO2 gas to produce artificial spring water and precipitation of carbonates to increase cohesion- with precise control of water discharge, sediment discharge, and temperature. Preliminary experiments successfully created a single-thread meandering pattern through chemical processes. Carbonate deposits focused along the channel sides improved the bank stability and made them resistant to erosion, which led to a stream confined in a narrow path. The experimental channels showed lateral migration of the bend through cut bank and point bar deposits; intermittent floods created overbank flow and encouraged cut bank erosion, which enhanced lateral migration of the channel, while increase in sediment supply improved lateral point bar deposition, which balanced erosion and deposition rates. This mechanism may be applied to terrestrial single-thread and/or meandering rivers with little to no vegetation or before its introduction to Earth and also provide the link between meandering river records on Mars to changes in Martian surface conditions.

Flowing-recirculated water system for inducing spawning phase sea lampreys to spawn in the laboratory

USGS Publications Warehouse

Fredricks, Kim T.; Seelye, James G.

1995-01-01

We describe a water-recirculating system for inducing spawning of sea lampreys (Petromyzon marinus) held under laboratory conditions. Water temperature in the system was gradually increased to and maintained at 18 ± 2°C, the optimal temperature for spawning. About 10% freshwater was added daily to prevent buildup of waste products. Sea lampreys were provided substrate (approximately 3–6 cm in diameter) to build nests, and a water velocity of 0.2–0.3 m!s was maintained with an electric trolling motor. Sea lampreys held in this system exhibited characteristic spawning behavior. Prolarvae produced from artificial fertilization of gametes developed according to the standard timeline.

Thermophysical fundamentals of cyclonic recirculating heating devices

NASA Astrophysics Data System (ADS)

Karpov, S. V.; Zagoskin, A. A.

2017-10-01

This report presents the results of experimental and theoretical research of aerodynamics and convective heat transfer in cyclone devices with the new system of external recirculation of heating gas under the influence of radial pressure gradient in a heat carrier’s swirling turbulent flow. The dynamic problem of tangential velocity distribution in a clearance volume is solved at various re-circulation ratio values including limiting quantities (kr = 0; 1) and variations in cyclonic combustion chamber’s design parameters and operating conditions (Rer); the integrated calculation ratios for fundamental aerodynamic characteristics of a recirculation device are derived. The first experimental and numerical studies of convective heat transfer on internal and external surfaces of a hollow shaft in a swirling recirculation flow are derived through the instrumentality of OpenFOAM, these studies are also conducted for a setting of several cylindrical solid inserts. The external surface heat problem of a hollow cylindrical insert is solved with integral and digital methods; generalized similarity equations for the internal and external surfaces extended in range of Reynolds number are derived. The experimental data is in reasonable agreement with the derived curves and the results of mathematic modelling of convective heat transfer. Calculation recommendations for optimal selection of kr values at various ratios of their geometric characteristics and products utilization rate are obtained.

Pilot-scale study of powdered activated carbon recirculation for micropollutant removal.

PubMed

Meinel, F; Sperlich, A; Jekel, M

Adsorption onto powdered activated carbon (PAC) is a promising technique for the removal of organic micropollutants (OMPs) from treated wastewater. To enhance the adsorption efficiency, PAC is recycled back into the adsorption stage. This technique was examined in pilot scale in comparison to a reference without recirculation. Coagulation with Fe(3+) was carried out simultaneously to adsorption. Extensive OMP measurements showed that recirculation significantly increased OMP eliminations. Thus, significant PAC savings were feasible. The PAC concentration in the contact reactor proved to be an important operating parameter that can be surrogated by the easily measurable total suspended solids (TSS) concentration. OMP eliminations increased with increasing TSS concentrations. At 20 mg PAC L(-1) and 2.8 g TSS L(-1) in the contact reactor, well-adsorbable carbamazepine was eliminated by 97%, moderately adsorbable diclofenac was eliminated by 92% and poorly-adsorbable acesulfame was eliminated by 54% in comparison to 49%, 35% and 18%, respectively, without recirculation. The recirculation system represents an efficient technique, as the PAC's adsorption capacity is practically completely used. Small PAC dosages yield high OMP eliminations. Poorly-adsorbable gabapentin was eliminated to an unexpectedly high degree. A laboratory-scale biomass inhibition study showed that aerobic biodegradation removed gabapentin in addition to adsorption.

Circulation of the gyres of the world ocean: Observation modeling using TOPEX/Poseidon altimeter data

NASA Technical Reports Server (NTRS)

Fu, Lee-Lueng; Zlotnicki, V.; Holland, W. R.; Malanotte-Rizzoli, P.

1991-01-01

The overall objectives of the proposed investigation are to study the dynamics of the large-scale recirculating cells of water in the ocean, which are loosely defined as 'gyres' in this study. A gyre is normally composed of a swift western boundary current (e.g., the Gulf Stream and the Kuroshio), a tight recirculating cell attached to the current, and a large-scale sluggish return flow. The water, of course, is not entirely recirculating within a gyre. The exchange of water among gyres is an important process in maintaining the meridional heat transport of the ocean. The gyres constitute a major mode of water movement in the ocean and play significant roles in the global climate system.

A replacement LH2 recirculation line before installation in Discovery

NASA Technical Reports Server (NTRS)

1999-01-01

A spare four-inch diameter LH2 recirculation line (shown in photo) will be used to replace a damaged LH2 line in the orbiter Discovery. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. Workers noted a dent in the line during routine aft compartment inspections Tuesday, Dec. 7. The dent measures 12 inches long and about =-inch deep. Managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope.

Removal of sodium chloride from human urine via batch recirculation electrodialysis at constant applied voltage

NASA Technical Reports Server (NTRS)

Gordils-Striker, Nilda E.; Colon, Guillermo

2003-01-01

The removal of sodium chloride (NaCl) from human urine using a six-compartment electrodialysis cell with batch recirculation mode of operation for use in advanced life support systems (ALSS) was studied. From the results obtained, batch recirculation at constant applied voltage yields high values (approximately 94% of NaCl removal. Based on the results, the initial rate of NaCl removal was correlated to a power function of the applied voltage: -r=2.0 x 10(-4)E(3.8). With impedance spectroscopy methods, it was also found that the anion membranes were more affected by fouling with an increase of the ohmic resistance of almost 11% compared with 7.4% for the cationic ones.

Argon purification studies and a novel liquid argon re-circulation system

NASA Astrophysics Data System (ADS)

Mavrokoridis, K.; Calland, R. G.; Coleman, J.; Lightfoot, P. K.; McCauley, N.; McCormick, K. J.; Touramanis, C.

2011-08-01

Future giant liquid argon (LAr) time projection chambers (TPCs) require a purity of better than 0.1 parts per billion (ppb) to allow the ionised electrons to drift without significant capture by any electronegative impurities. We present a comprehensive study of the effects of electronegative impurity on gaseous and liquid argon scintillation light, an analysis of the efficiency of various purification chemicals, as well as the Liverpool LAr setup, which utilises a novel re-circulation purification system. Of the impurities tested - Air, O2, H2O, N2 and CO2 in the range of between 0.01 ppm to 1000 ppm - H2O was found to have the most profound effect on gaseous argon scintillation light, and N2 was found to have the least. Additionally, a correlation between the slow component decay time and the total energy deposited with 0.01 ppm - 100 ppm O2 contamination levels in liquid argon has been established. The superiority of molecular sieves over anhydrous complexes at absorbing Ar gas, N2 gas and H2O vapour has been quantified using BET isotherm analysis. The efficiency of Cu and P2O5 at removing O2 and H2O impurities from 1 bar N6 argon gas at both room temperature and -130 °C was investigated and found to be high. A novel, highly scalable LAr re-circulation system has been developed. The complete system, consisting of a motorised bellows pump operating in liquid and a purification cartridge, were designed and built in-house. The system was operated successfully over many days and achieved a re-circulation rate of 27 litres/hour and high purity.

Biogas recirculation for simultaneous calcium removal and biogas purification within an expanded granular sludge bed system treating leachate.

PubMed

Luo, Jinghuan; Lu, Xueqin; Liu, Jianyong; Qian, Guangren; Lu, Yongsheng

2014-12-01

Biogas, generated from an expanded granular sludge bed (EGSB) reactor treating municipal solid waste (MSW) leachate, was recirculated for calcium removal from the leachate via a carbonation process with simultaneous biogas purification. Batch trials were performed to optimize the solution pH and imported biogas (CO2) for CaCO3 precipitation. With applicable pH of 10-11 obtained, continuous trials achieved final calcium concentrations of 181-375 mg/L (removal efficiencies≈92.8-96.5%) in the leachate and methane contents of 87.1-91.4% (purification efficiencies≈65.4-82.2%) in the biogas. Calcium-balance study indicates that 23-986 mg Ca/d was released from the bio-system under the carbonized condition where CaCO3 precipitating was moved outside the bioreactor, whereas 7918-9517 mg Ca/d was trapped into the system for the controlled one. These findings demonstrate that carbonation removal of calcium by biogas recirculation could be a promising alternative to pretreat calcium-rich MSW leachate and synergistically to improve methane content. Copyright © 2014 Elsevier Ltd. All rights reserved.

Control Strategies to Reduce the Energy Consumption of Central Domestic Hot Water Systems

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

Dentz, Jordan; Ansanelli, Eric; Henderson, Hugh

Domestic hot water (DHW) heating is the second largest energy end use in U.S. buildings, exceeded only by space conditioning. Recirculation systems consisting of a pump and piping loop(s) are commonly used in multifamily buildings to reduce wait time for hot water at faucets; however, constant pumping increases energy consumption by exposing supply and return line piping to continuous heat loss, even during periods when there is no demand for hot water. In this study, ARIES installed and tested two types of recirculation controls in a pair of buildings in order to evaluate their energy savings potential. Demand control, temperaturemore » modulation controls, and the simultaneous operation of both were compared to the baseline case of constant recirculation. Additionally, interactive effects between DHW control fuel reductions and space conditioning (heating and cooling) were estimated in order to make more realistic predictions of the payback and financial viability of retrofitting DHW systems with these controls. Results showed that DHW fuel consumption reduced by 7% after implementing the demand control technique, 2% after implementing temperature modulation, and 15% after implementing demand control and temperature modulation techniques simultaneously; recirculation pump runtime was reduced to 14 minutes or less per day. With space heating and cooling interactions included, the estimated annual cost savings were 8%, 1%, and 14% for the respective control techniques. Possible complications in the installation, commissioning and operation of the controls were identified and solutions offered.« less

Tide-induced fingering flow during submarine groundwater discharge

NASA Astrophysics Data System (ADS)

Greskowiak, Janek

2013-04-01

Submarine groundwater discharge (SGD) is a relevant component of the hydrological cycle (Moore, 2010). The discharge of fresh groundwater that originated from precipitation on the land typically occurs at the near shore scale (~ 10m-100m) and the embayment scale (~ 100m - 10km) (Bratton, 2010). In the recent years a number of studies revealed that tidal forcing has an important effect on the fresh SGD pattern in the beach zone, i.e., it leads to the formation of an upper saline recirculation cell and a lower "freshwater discharge tube" (Boufadel, 2000, Robinson et al., 2007; Kuan et al., 2012). Thereby the discharge of the fresh groundwater occurs near the low-tide mark. The shape and extent of the upper saline recirculation cell is mainly defined by the tidal amplitude, beach slope, fresh groundwater discharge rate and hydraulic conductivity (Robinson et al., 2007). In spite of fact that in this case sea water overlies less denser freshwater, all previous modeling studies suggested that the saline recirculation cell and the freshwater tube are rather stable. However, new numerical investigations indicate that there maybe realistic cases where the upper saline recirculation cell becomes unstable as a result of the density contrast to the underlying freshwater tube. In these cases salt water fingers develop and move downward, thereby penetrating the freshwater tube. To the author's knowledge, the present study is the first that illustrate the possibility of density induced fingering flow during near shore SGD. A total of 240 high resolution simulations with the density dependent groundwater modelling software SEAWAT-2000 (Langevin et al., 2007) has been carried out to identify the conditions under which salt water fingering starts to occur. The simulations are based on the field-scale model setup employed in Robinson et al. (2007). The simulation results indicate that a very flat beach slope of less than 1:35, a hydraulic conductivity of 10 m/d and already a tidal range of 2 m initiates fingering flow. Flatter beach slope, higher hydraulic conductivity and increasing tidal range support this behavior. In the cases of fingering flow, freshwater is squeezed upward and pinches out within the inter-tidal zone. Once pinched out, the discharge point slowly moves along at the beach surface towards the low-tide mark. Overall, the fingering process further complicates the flow pattern and the mixing of salt and freshwater in the inter-tidal zone compared to the cases where the saline recirculation cell remains stable. This may have an important implication for the hydrogeochemical processes in this zone and thus the mass flux of reactive chemicals from the land to the ocean. Boufadel, M. C. (2000). A mechanistic study of nonlinear solute transport in a groundwater-surface water system under steady state and transient hydraulic conditions, Water Resour. Res., 36(9), 2549 2565. Bratton, J.F. (2010). The Three Scales of Submarine Groundwater Flow and Discharge across Passive Continental Margins, The Journal of Geology, 2010, 118, 565-575. Kuan, W. K., G. Jin, P. Xin, C. Robinson, B. Gibbes, and L. Li (2012). Tidal influence on seawater intrusion in unconfined coastal aquifers, Water Resour. Res., 48, W02502, doi:10.1029/2011WR010678. Langevin, C.D., D.T. Thorne, Jr., A.M. Dausman, M.C. Sukop, and G. Weixing (2007). Seawat version 4: a computer program for simulation of multi-species solute and heat transport, Technical Report, U.S. Geological Survey Techniques and Methods Book 6, Chapter A22, 39 pp. Robinson, C., L. Li, and H. Prommer (2007). Tide-induced recirculation across the aquifer-ocean interface, Water Resour. Res., 43, W07428, doi:10.1029/2006WR005679. Moore, W.S. (2010). The Effect of Submarine Groundwater Discharge on the Ocean, Annu. Rev. Mar. Sci., 2, 59-88.

Calcification in Caribbean reef-building corals at high pCO2 levels in a recirculating ocean acidification exposure system.

PubMed

Enzor, Laura A; Hankins, Cheryl; Vivian, Deborah N; Fisher, William S; Barron, Mace G

2018-02-01

Projected increases in ocean p CO 2 levels are anticipated to affect calcifying organisms more rapidly and to a greater extent than other marine organisms. The effects of ocean acidification (OA) have been documented in numerous species of corals in laboratory studies, largely tested using flow-through exposure systems. We developed a recirculating ocean acidification exposure system that allows precise p CO 2 control using a combination of off-gassing measures including aeration, water retention devices, venturi injectors, and CO 2 scrubbing. We evaluated the recirculating system performance in off-gassing effectiveness and maintenance of target p CO 2 levels over an 84-day experiment. The system was used to identify changes in calcification and tissue growth in response to elevated p CO 2 (1000 μatm) in three reef-building corals of the Caribbean: Pseudodiploria clivosa , Montastraea cavernosa , and Orbicella faveolata . All three species displayed an overall increase in net calcification over the 84-day exposure period regardless of p CO 2 level (control +0.28- 1.12 g, elevated p CO 2 +0.18- 1.16 g), and the system was effective at both off-gassing acidified water to ambient p CO 2 levels, and maintaining target elevated p CO 2 levels over the 3-month experiment.

STS-56 inflight maintenance (IFM) air duct routing on OV-103's middeck

NASA Technical Reports Server (NTRS)

1993-01-01

STS-56 inflight maintenance (IFM) repair on Discovery's, Orbiter Vehicle (OV) 103's, middeck was required to offset overheating problems with one of the onboard experiments -- Detailed Supplementary Objective (DSO) 322, Human lymphocyte locomotion in microgravity. This 'elephant's trunk' fix was rigged from the airlock's air recirculation duct to DSO 322's forward locker location by Commander Kenneth Cameron. The 'elephant's trunk' was fashioned from trash bags and other plastic items to extend an airline to the troubled area. DSO 322 is collecting data on the locomotion and migration of human lymphocytes through intercellular matrix and is testing the rotating wall vessel and the specimen temperature controller. In the background is the port side wall with the side hatch, middeck accomodations rack (MAR), and shuttle orbiter repackaged galley (SORG) visible.

A magnetically driven piston pump for ultra-clean applications

NASA Astrophysics Data System (ADS)

LePort, F.; Neilson, R.; Barbeau, P. S.; Barry, K.; Bartoszek, L.; Counts, I.; Davis, J.; deVoe, R.; Dolinski, M. J.; Gratta, G.; Green, M.; Díez, M. Montero; Müller, A. R.; O'Sullivan, K.; Rivas, A.; Twelker, K.; Aharmim, B.; Auger, M.; Belov, V.; Benitez-Medina, C.; Breidenbach, M.; Burenkov, A.; Cleveland, B.; Conley, R.; Cook, J.; Cook, S.; Craddock, W.; Daniels, T.; Dixit, M.; Dobi, A.; Donato, K.; Fairbank, W.; Farine, J.; Fierlinger, P.; Franco, D.; Giroux, G.; Gornea, R.; Graham, K.; Green, C.; Hägemann, C.; Hall, C.; Hall, K.; Hallman, D.; Hargrove, C.; Herrin, S.; Hughes, M.; Hodgson, J.; Juget, F.; Kaufman, L. J.; Karelin, A.; Ku, J.; Kuchenkov, A.; Kumar, K.; Leonard, D. S.; Lutter, G.; Mackay, D.; MacLellan, R.; Marino, M.; Mong, B.; Morgan, P.; Odian, A.; Piepke, A.; Pocar, A.; Prescott, C. Y.; Pushkin, K.; Rollin, E.; Rowson, P. C.; Schmoll, B.; Sinclair, D.; Skarpaas, K.; Slutsky, S.; Stekhanov, V.; Strickland, V.; Swift, M.; Vuilleumier, J.-L.; Vuilleumier, J.-M.; Wichoski, U.; Wodin, J.; Yang, L.; Yen, Y.-R.

2011-10-01

A magnetically driven piston pump for xenon gas recirculation is presented. The pump is designed to satisfy extreme purity and containment requirements, as is appropriate for the recirculation of isotopically enriched xenon through the purification system and large liquid xenon time projection chamber of EXO-200. The pump, using sprung polymer gaskets, is capable of pumping more than 16 standard liters per minute of xenon gas with 750 Torr differential pressure.

A magnetically driven piston pump for ultra-clean applications.

PubMed

LePort, F; Neilson, R; Barbeau, P S; Barry, K; Bartoszek, L; Counts, I; Davis, J; deVoe, R; Dolinski, M J; Gratta, G; Green, M; Montero Díez, M; Müller, A R; O'Sullivan, K; Rivas, A; Twelker, K; Aharmim, B; Auger, M; Belov, V; Benitez-Medina, C; Breidenbach, M; Burenkov, A; Cleveland, B; Conley, R; Cook, J; Cook, S; Craddock, W; Daniels, T; Dixit, M; Dobi, A; Donato, K; Fairbank, W; Farine, J; Fierlinger, P; Franco, D; Giroux, G; Gornea, R; Graham, K; Green, C; Hägemann, C; Hall, C; Hall, K; Hallman, D; Hargrove, C; Herrin, S; Hughes, M; Hodgson, J; Juget, F; Kaufman, L J; Karelin, A; Ku, J; Kuchenkov, A; Kumar, K; Leonard, D S; Lutter, G; Mackay, D; MacLellan, R; Marino, M; Mong, B; Morgan, P; Odian, A; Piepke, A; Pocar, A; Prescott, C Y; Pushkin, K; Rollin, E; Rowson, P C; Schmoll, B; Sinclair, D; Skarpaas, K; Slutsky, S; Stekhanov, V; Strickland, V; Swift, M; Vuilleumier, J-L; Vuilleumier, J-M; Wichoski, U; Wodin, J; Yang, L; Yen, Y-R

2011-10-01

A magnetically driven piston pump for xenon gas recirculation is presented. The pump is designed to satisfy extreme purity and containment requirements, as is appropriate for the recirculation of isotopically enriched xenon through the purification system and large liquid xenon time projection chamber of EXO-200. The pump, using sprung polymer gaskets, is capable of pumping more than 16 standard liters per minute of xenon gas with 750 Torr differential pressure.

Cabin air filtration: helping to protect occupants from infectious diseases.

PubMed

Bull, Karen

2008-05-01

Presentation made at the Aviation Health Conference, London, November 2006. In modern aircraft, the air in the cabin is provided by the environmental control system (ECS) and consists of approximately 50% outside air (engine 'bleed air') mixed with approximately 50% filtered, recirculated air. This paper describes how modern aircraft cabin air filters are effective at removing airborne particulate contamination (such as bacteria and viruses) from the recirculated air system. It also describes one of the technological solutions that is currently available to treat any odours or volatile organic compounds (VOCs) that may be present in the aircraft ECS.

On Orbit ISS Oxygen Generation System Operation Status

NASA Technical Reports Server (NTRS)

Diderich, Greg S.; Polis, Pete; VanKeuren, Steven P.; Erickson, Robert; Mason, Richard

2011-01-01

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) has accumulated almost a year of operation at varied oxygen production rates within the US Laboratory Module (LAB) since it was first activated in July 2007. It was operated intermittently through 2009 and 2010, due to filter clogging and acid accumulation in the recirculation loop. Since the installation of a deionizing bed in the recirculation loop in May of 2011 the OGA has been operated continuously. Filters in the recirculation loop have clogged and have been replaced. Hydrogen sensors have drifted apart, and a power failure may have condensed water on a hydrogen sensor. A pump delta pressure sensor failed, and a replacement new spare pump failed to start. Finally, the voltage across the cell stack increased out of tolerance due to cation contamination, and the cell stack was replaced. This paper will discuss the operating experience and characteristics of the OGS, as well as operational issues and their resolution.

Does an Open Recirculation Line Affect the Flow Rate and Pressure in a Neonatal Extracorporeal Life Support Circuit With a Centrifugal or Roller Pump?

PubMed

Wang, Shigang; Spencer, Shannon B; Woitas, Karl; Glass, Kristen; Kunselman, Allen R; Ündar, Akif

2017-01-01

The objective of this study is to evaluate the impact of an open or closed recirculation line on flow rate, circuit pressure, and hemodynamic energy transmission in simulated neonatal extracorporeal life support (ECLS) systems. The two neonatal ECLS circuits consisted of a Maquet HL20 roller pump (RP group) or a RotaFlow centrifugal pump (CP group), Quadrox-iD Pediatric oxygenator, and Biomedicus arterial and venous cannulae (8 Fr and 10 Fr) primed with lactated Ringer's solution and packed red blood cells (hematocrit 35%). Trials were conducted at flow rates ranging from 200 to 600 mL/min (200 mL/min increments) with a closed or open recirculation line at 36°C. Real-time pressure and flow data were recorded using a custom-based data acquisition system. In the RP group, the preoxygenator flow did not change when the recirculation line was open while the prearterial cannula flow decreased by 15.7-20.0% (P < 0.01). Circuit pressure, total circuit pressure drop, and hemodynamic energy delivered to patients also decreased (P < 0.01). In the CP group, the prearterial cannula flow did not change while preoxygenator flow increased by 13.6-18.8% (P < 0.01). Circuit pressure drop and hemodynamic energy transmission remained the same. The results showed that the shunt of an open recirculation line could decrease perfusion flow in patients in the ECLS circuit using a roller pump, but did not change perfusion flow in the circuit using a centrifugal pump. An additional flow sensor is needed to monitor perfusion flow in patients if any shunts exist in the ECLS circuit. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Investigation on inlet recirculation characteristics of double suction centrifugal compressor with unsymmetrical inlet

NASA Astrophysics Data System (ADS)

Yang, Ce; Wang, Yingjun; Lao, Dazhong; Tong, Ding; Wei, Longyu; Liu, Yixiong

2016-08-01

The inlet recirculation characteristics of double suction centrifugal compressor with unsymmetrical inlet structures were studied in numerical method, mainly focused on three issues including the amounts and differences of the inlet recirculation in different working conditions, the circumferential non-uniform distributions of the inlet recirculation, the recirculation velocity distributions of the upstream slot of the rear impeller. The results show that there are some differences between the recirculation of the front impeller and that of the rear impeller in whole working conditions. In design speed, the recirculation flow rate of the rear impeller is larger than that of the front impeller in the large flow range, but in the small flow range, the recirculation flow rate of the rear impeller is smaller than that of the front impeller. In different working conditions, the recirculation velocity distributions of the front and rear impeller are non-uniform along the circumferential direction and their non-uniform extents are quite different. The circumferential non-uniform extent of the recirculation velocity varies with the working conditions change. The circumferential non-uniform extent of the recirculation velocity of front impeller and its distribution are determined by the static pressure distribution of the front impeller, but that of the rear impeller is decided by the coupling effects of the inlet flow distortion of the rear impeller, the circumferential unsymmetrical distribution of the upstream slot and the asymmetric structure of the volute. In the design flow and small flow conditions, the recirculation velocities at different circumferential positions of the mean line of the upstream slot cross-section of the rear impeller are quite different, and the recirculation velocities distribution forms at both sides of the mean line are different. The recirculation velocity distributions in the cross-section of the upstream slot depend on the static pressure distributions in the intake duct.

Liquid hydrogen and liquid oxygen feedline passive recirculation analysis

NASA Astrophysics Data System (ADS)

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

The primary goal of the National Launch System (NLS) program was to design an operationally efficient, highly reliable vehicle with minimal recurring launch costs. To achieve this goal, trade studies of key main propulsion subsystems were performed to specify vehicle design requirements. These requirements include the use of passive recirculation to thermally condition the liquid hydrogen (LH2) and liquid oxygen (LO2) propellant feed systems and Space Transportation Main Engine (STME) fuel pumps. Rockwell International (RI) proposed a joint independent research and development (JIRAD) program with Marshall Space Flight Center (MSFC) to study the LH2 feed system passive recirculation concept. The testing was started in July 1992 and completed in November 1992. Vertical and sloped feedline designs were used. An engine simulator was attached at the bottom of the feedline. This simulator had strip heaters that were set to equal the corresponding heat input from different engines. A computer program is currently being used to analyze the passive recirculation concept in the LH2 vertical feedline tests. Four tests, where the heater setting is the independent variable, were chosen. While the JIRAD with RI was underway, General Dynamics Space Systems (GDSS) proposed a JIRAD with MSFC to explore passive recirculation in the LO2 feed system. Liquid nitrogen (LN2) is being used instead of LO2 for safety and economic concerns. To date, three sets of calibration tests have been completed on the sloped LN2 test article. The environmental heat was calculated from the calibration tests in which the strip heaters were turned off. During the LH2 testing, the environmental heat was assumed to be constant. Therefore, the total heat was equal to the environmental heat flux plus the heater input. However, the first two sets of LN2 calibration tests have shown that the environmental heat flux varies with heater input. A Systems Improved Numerical Differencing Analyzer and Fluid Integrator (SINDA/FLUINT) model is currently being built to determine if this variation in environmental heat is due to a change in the wall temperature.

40 CFR Appendix I to Part 1068 - Emission-Related Components

Code of Federal Regulations, 2010 CFR

2010-07-01

... system. 2. Fuel system. 3. Ignition system. 4. Exhaust gas recirculation systems. II. The following parts.... Crankcase ventilation valves. 3. Sensors. 4. Electronic control units. III. The following parts are...

40 CFR Appendix I to Part 1068 - Emission-Related Components

Code of Federal Regulations, 2011 CFR

2011-07-01

... system. 2. Fuel system. 3. Ignition system. 4. Exhaust gas recirculation systems. II. The following parts.... Crankcase ventilation valves. 3. Sensors. 4. Electronic control units. III. The following parts are...

Recirculation of Laser Power in an Atomic Fountain

NASA Technical Reports Server (NTRS)

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

2007-01-01

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

Continuous hydroponic wheat production using a recirculating system

NASA Technical Reports Server (NTRS)

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

1989-01-01

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.

A replacement LH2 recirculation line before installation in Discovery

NASA Technical Reports Server (NTRS)

1999-01-01

Gary Hamilton (left) and James Stickley, both with United Space Alliance, check out a spare four-inch diameter LH2 recirculation line that will be used to replace a damaged LH2 line in the orbiter Discovery. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. Workers noted a dent in the line during routine aft compartment inspections Tuesday, Dec. 7. The dent measures 12 inches long and about =-inch deep. Managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope.

A replacement LH2 recirculation line before installation in Discovery

NASA Technical Reports Server (NTRS)

1999-01-01

James Stickley (left) and Derry Dilby (right), who are with United Space Alliance, check over a spare four-inch diameter LH2 recirculation line that will be used to replace a damaged LH2 line in the orbiter Discovery. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. Workers noted a dent in the line during routine aft compartment inspections Tuesday, Dec. 7. The dent measures 12 inches long and about =-inch deep. Managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope.

Back to the Thymus: Peripheral T Cells Come Home

PubMed Central

Hale, J. Scott; Fink, Pamela J.

2009-01-01

The thymus has long been known as the generative organ for the T cell arm of the immune system. To perform this role, the thymus was thought to require protection from antigenic and cellular insult from the “outside world”, with the notable exception of the continual influx of progenitor cells required to initiate the complicated process of T cell differentiation. Overwhelming evidence that mature T cells can recirculate and persist in the thymus has required us to revamp this earlier view of the thymus as detached from outside influence. In this review, we consider the evidence for T cell recirculation into the thymus, discuss the likely means and location of mature T cell entry, and speculate on the potential consequences of such close apposition between differentiating thymocytes and mature recirculating lymphocytes. PMID:19030016

Back to the thymus: peripheral T cells come home.

PubMed

Hale, J Scott; Fink, Pamela J

2009-01-01

The thymus has long been known as the generative organ for the T-cell arm of the immune system. To perform this role, the thymus was thought to require protection from antigenic and cellular insult from the 'outside world', with the notable exception of the continual influx of progenitor cells required to initiate the complicated process of T-cell differentiation. Overwhelming evidence that mature T cells can recirculate and persist in the thymus has required us to revamp this earlier view of the thymus as detached from outside influence. In this review, we consider the evidence for T-cell recirculation into the thymus, discuss the likely means and location of mature T-cell entry, and speculate on the potential consequences of such close apposition between differentiating thymocytes and mature recirculating lymphocytes.

Groundwater-driven nutrient inputs to coastal lagoons: The relevance of lagoon water recirculation as a conveyor of dissolved nutrients.

PubMed

Rodellas, Valentí; Stieglitz, Thomas C; Andrisoa, Aladin; Cook, Peter G; Raimbault, Patrick; Tamborski, Joseph J; van Beek, Pieter; Radakovitch, Olivier

2018-06-16

Evaluating the sources of nutrient inputs to coastal lagoons is required to understand the functioning of these ecosystems and their vulnerability to eutrophication. Whereas terrestrial groundwater processes are increasingly recognized as relevant sources of nutrients to coastal lagoons, there are still limited studies evaluating separately nutrient fluxes driven by terrestrial groundwater discharge and lagoon water recirculation through sediments. In this study, we assess the relative significance of these sources in conveying dissolved inorganic nutrients (NO 3 - , NH 4 + and PO 4 3- ) to a coastal lagoon (La Palme lagoon; France, Mediterranean Sea) using concurrent water and radon mass balances. The recirculation of lagoon water through sediments represents a source of NH 4 + (1900-5500 mol d -1 ) and PO 4 3- (22-71 mol d -1 ), but acts as a sink of NO 3 - . Estimated karstic groundwater-driven inputs of NO 3 - , NH 4 + and PO 4 3- to the lagoon are on the order of 200-1200, 1-12 and 1.5-8.7 mol d -1 , respectively. A comparison between the main nutrient sources to the lagoon (karstic groundwater, recirculation, diffusion from sediments, inputs from a sewage treatment plant and atmospheric deposition) reveals that the recirculation of lagoon water through sediments is the main source of both dissolved inorganic nitrogen (DIN) and phosphorous (DIP) to La Palme lagoon. These results are in contrast with several studies conducted in systems influenced by terrestrial groundwater inputs, where groundwater is often assumed to be the main pathway for dissolved inorganic nutrient loads. This work highlights the important role of lagoon water recirculation through permeable sediments as a major conveyor of dissolved nutrients to coastal lagoons and, thus, the need for a sound understanding of the recirculation-driven nutrient fluxes and their ecological implications to sustainably manage lagoonal ecosystems. Copyright © 2018. Published by Elsevier B.V.

Steam atmosphere drying exhaust steam recompression system

DOEpatents

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

1994-03-08

This invention relates to a heated steam atmosphere drying system comprising dryer in combination with an exhaust recompression system which is extremely energy efficient and eliminates dangers known to air dryers. The system uses superheated steam as the drying medium, which recirculates through the system where its heat of evaporation and heat of compression is recovered, thereby providing a constant source of heat to the drying chamber. The dryer has inlets whereby feedstock and superheated steam are fed therein. High heat transfer and drying rates are achieved by intimate contact of the superheated steam with the particles being dried. The dryer comprises a vessel which enables the feedstock and steam to enter and recirculate together. When the feedstock becomes dry it will exit the dryer with the steam and become separated from the steam through the use of a curvilinear louver separator (CLS). The CLS enables removal of fine and ultrafine particles from the dryer. Water vapor separated from the particles in the CLS as superheated steam, may then be recovered and recirculated as steam through the use of a compressor to either directly or indirectly heat the dryer, and a heat exchanger or a heater to directly provide heat to the dryer. This system not only provides a very efficient heat transfer system but results in a minimum carry-over of ultrafine particles thereby eliminating any explosive hazard. 17 figures.

Steam atmosphere drying exhaust steam recompression system

DOEpatents

Becker, Frederick E.; Smolensky, Leo A.; Doyle, Edward F.; DiBella, Francis A.

1994-01-01

This invention relates to a heated steam atmosphere drying system comprising dryer in combination with an exhaust recompression system which is extremely energy efficient and eliminates dangers known to air dryers. The system uses superheated steam as the drying medium, which recirculated through the system where its heat of evaporation and heat of compression is recovered, thereby providing a constant source of heat to the drying chamber. The dryer has inlets whereby feedstock and superheated steam are fed therein. High heat transfer and drying rates are achieved by intimate contact of the superheated steam with the particles being dried The dryer comprises a vessel which enables the feedstock and steam to enter recirculate together. When the feedstock becomes dry it will exit the dryer with the steam and become separated from the steam through the use of a curvilinear louver separator (CLS). The CLS enables removal of fine and ultrafine particles from the dryer. Water vapor separated from the particles in the CLS as superheated steam, may then be recovered and recirculated as steam through the use of a compressor to either directly or indirectly heat the dryer, and a heat exchanger or a heater to directly provide heat to the dryer. This system not only provides a very efficient heat transfer system but results in a minimum carry-over of ultrafine particles thereby eliminating any explosive hazard.

Project W-320, 241-C-106 sluicing HVAC calculations, Volume 1

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

Bailey, J.W.

1998-08-07

This supporting document has been prepared to make the FDNW calculations for Project W-320, readily retrievable. The report contains the following calculations: Exhaust airflow sizing for Tank 241-C-106; Equipment sizing and selection recirculation fan; Sizing high efficiency mist eliminator; Sizing electric heating coil; Equipment sizing and selection of recirculation condenser; Chiller skid system sizing and selection; High efficiency metal filter shielding input and flushing frequency; and Exhaust skid stack sizing and fan sizing.

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

Dentz, Jordan; Ansanelli, Eric; Henderson, Hugh

Domestic hot water (DHW) heating is the second largest energy end use in U.S. buildings, exceeded only by space conditioning. Recirculation systems consisting of a pump and piping loop(s) are commonly used in multifamily buildings to reduce wait time for hot water at faucets; however, constant pumping increases energy consumption by exposing supply and return line piping to continuous heat loss, even during periods when there is no demand for hot water. In this study, ARIES installed and tested two types of recirculation controls in a pair of buildings in order to evaluate their energy savings potential. Demand control, temperaturemore » modulation controls, and the simultaneous operation of both were compared to the baseline case of constant recirculation. Additionally, interactive effects between DHW control fuel reductions and space conditioning (heating and cooling) were estimated in order to make more realistic predictions of the payback and financial viability of retrofitting DHW systems with these controls. Results showed that DHW fuel consumption reduced by 7% after implementing the demand control technique, 2% after implementing temperature modulation, and 15% after implementing demand control and temperature modulation techniques simultaneously; recirculation pump runtime was reduced to 14 minutes or less per day. With space heating and cooling interactions included, the estimated annual cost savings were 8%, 1%, and 14% for the respective control techniques. Possible complications in the installation, commissioning and operation of the controls were identified and solutions offered.« less

Zero Gravity Cryogenic Vent System Concepts for Upper Stages

NASA Technical Reports Server (NTRS)

Flachbart, Robin H.; Holt, James B.; Hastings, Leon J.

1999-01-01

The capability to vent in zero gravity without resettling is a technology need that involves practically all uses of sub-critical cryogenics in space. Venting without resettling would extend cryogenic orbital transfer vehicle capabilities. However, the lack of definition regarding liquid/ullage orientation coupled with the somewhat random nature of the thermal stratification and resulting pressure rise rates, lead to significant technical challenges. Typically a zero gravity vent concept, termed a thermodynamic vent system (TVS), consists of a tank mixer to destratify the propellant, combined with a Joule-Thomson (J-T) valve to extract thermal energy from the propellant. Marshall Space Flight Center's (MSFC's) Multipurpose Hydrogen Test Bed (MHTB) was used to test both spray bar and axial jet TVS concepts. The axial jet system consists of a recirculation pump heat exchanger unit. The spray bar system consists of a recirculation pump, a parallel flow concentric tube, heat exchanger, and a spray bar positioned close to the longitudinal axis of the tank. The operation of both concepts is similar. In the mixing mode, the recirculation pump withdraws liquid from the tank and sprays it into the tank liquid, ullage, and exposed tank surfaces. When energy is required. a small portion of the recirculated liquid is passed sequentially through the J-T expansion valve, the heat exchanger, and is vented overboard. The vented vapor cools the circulated bulk fluid, thereby removing thermal energy and reducing tank pressure. The pump operates alone, cycling on and off, to destratify the tank liquid and ullage until the liquid vapor pressure reaches the lower set point. At that point. the J-T valve begins to cycle on and off with the pump. Thus, for short duration missions, only the mixer may operate, thus minimizing or even eliminating, boil-off losses.

Zero Gravity Cryogenic Vent System Concepts for Upper Stages

NASA Technical Reports Server (NTRS)

Flachbart, Robin H.; Holt, James B.; Hastings, Leon J.

2001-01-01

The capability to vent in zero gravity without resettling is a technology need that involves practically all uses of sub-critical cryogenics in space, and would extend cryogenic orbital transfer vehicle capabilities. However, the lack of definition regarding liquid/ullage orientation coupled with the somewhat random nature of the thermal stratification and resulting pressure rise rates, lead to significant technical challenges. Typically a zero gravity vent concept, termed a thermodynamic vent system (TVS), consists of a tank mixer to destratify the propellant, combined with a Joule-Thomson (J-T) valve to extract thermal energy from the propellant. Marshall Space Flight Center's (MSFC's) Multipurpose Hydrogen Test Bed (MHTB) was used to test both spray-bar and axial jet TVS concepts. The axial jet system consists of a recirculation pump heat exchanger unit. The spray-bar system consists of a recirculation pump, a parallel flow concentric tube heat exchanger, and a spray-bar positioned close to the longitudinal axis of the tank. The operation of both concepts is similar. In the mixing mode, the recirculation pump withdraws liquid from the tank and sprays it into the tank liquid, ullage, and exposed tank surfaces. When energy extraction is required, a small portion of the recirculated liquid is passed sequentially through the J-T expansion valve, the heat exchanger, and is vented overboard. The vented vapor cools the circulated bulk fluid, thereby removing thermal energy and reducing tank pressure. The pump operates alone, cycling on and off, to destratify the tank liquid and ullage until the liquid vapor pressure reaches the lower set point. At that point, the J-T valve begins to cycle on and off with the pump. Thus, for short duration missions, only the mixer may operate, thus minimizing or even eliminating boil-off losses.

Nitrogen oxides emissions from the MILD combustion with the conditions of recirculation gas.

PubMed

Park, Min; Shim, Sung Hoon; Jeong, Sang Hyun; Oh, Kwang-Joong; Lee, Sang-Sup

2017-04-01

The nitrogen oxides (NO x ) reduction technology by combustion modification which has economic benefits as a method of controlling NO x emitted in the combustion process, has recently been receiving a lot of attention. Especially, the moderate or intense low oxygen dilution (MILD) combustion which applied high temperature flue gas recirculation has been confirmed for its effectiveness with regard to solid fuel as well. MILD combustion is affected by the flue gas recirculation ratio and the composition of recirculation gas, so its NO x reduction efficiency is determined by them. In order to investigate the influence of factors which determine the reduction efficiency of NO x in MILD coal combustion, this study changed the flow rate and concentration of nitrogen (N 2 ), carbon dioxide (CO 2 ) and steam (H 2 O) which simulate the recirculation gas during the MILD coal combustion using our lab-scale drop tube furnace and performed the combustion experiment. As a result, its influence by the composition of recirculation gas was insignificant and it was shown that flue gas recirculation ratio influences the change of NO x concentration greatly. We investigated the influence of factors determining the nitrogen oxides (NO x ) reduction efficiency in MILD coal combustion, which applied high-temperature flue gas recirculation. Using a lab-scale drop tube furnace and simulated recirculation gas, we conducted combustion testing changing the recirculation gas conditions. We found that the flue gas recirculation ratio influences the reduction of NO x emissions the most.

Proton Exchange Membrane (PEM) Fuel Cells for Space Applications

NASA Technical Reports Server (NTRS)

Bradley, Karla

2004-01-01

This presentation will provide a summary of the PEM fuel cell development at the National Aeronautics and Space Administration, Johnson Space Center (NASA, JSC) in support of future space applications. Fuel cells have been used for space power generation due to their high energy storage density for multi-day missions. The Shuttle currently utilizes the alkaline fuel cell technology, which has highly safe and reliable performance. However, the alkaline technology has a limited life due to the corrosion inherent to the alkaline technology. PEM fuel cells are under development by industry for transportation, residential and commercial stationary power applications. NASA is trying to incorporate some of this stack technology development in the PEM fuel cells for space. NASA has some unique design and performance parameters which make developing a PEM fuel cell system more challenging. Space fuel cell applications utilize oxygen, rather than air, which yields better performance but increases the hazard level. To reduce the quantity of reactants that need to be flown in space, NASA also utilizes water separation and reactant recirculation. Due to the hazards of utilizing active components for recirculation and water separation, NASA is trying to develop passive recirculation and water separation methods. However, the ability to develop recirculation components and water separators that are gravity-independent and successfully operate over the full range of power levels is one of the greatest challenges to developing a safe and reliable PEM fuel cell system. PEM stack, accessory component, and system tests that have been performed for space power applications will be discussed.

System and method for regeneration and recirculation of a reducing agent using highly exothermic reactions induced by mixed industrial slags

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

Nakano, Jinichiro; Bennett, James P.; Nakano, Anna

Embodiments relate to systems and methods for regenerating and recirculating a CO, H.sub.2 or combinations thereof utilized for metal oxide reduction in a reduction furnace. The reduction furnace receives the reducing agent, reduces the metal oxide, and generates an exhaust of the oxidized product. The oxidized product is transferred to a mixing vessel, where the oxidized product, a calcium oxide, and a vanadium oxide interact to regenerate the reducing agent from the oxidized product. The regenerated reducing agent is transferred back to the reduction furnace for continued metal oxide reductions.

Randomized controlled study of extracorporeal albumin dialysis for hepatic encephalopathy in advanced cirrhosis.

PubMed

Hassanein, Tarek I; Tofteng, Flemming; Brown, Robert S; McGuire, Brendan; Lynch, Patrick; Mehta, Ravindra; Larsen, Fin S; Gornbein, Jeff; Stange, Jan; Blei, Andres T

2007-12-01

Extracorporeal albumin dialysis (ECAD) may improve severe hepatic encephalopathy (HE) in patients with advanced cirrhosis via the removal of protein or non-protein-bound toxins. A prospective, randomized, controlled, multicenter trial of the efficacy, safety, and tolerability of ECAD using molecular adsorbent recirculating system (MARS) was conducted in such patients. Patients were randomized to ECAD and standard medical therapy (SMT) or SMT alone. ECAD was provided daily for 6 hours for 5 days or until the patient had a 2-grade improvement in HE. HE grades (West Haven criteria) were evaluated every 12 hours using a scoring algorithm. The primary endpoint was the difference in improvement proportion of HE between the 2 groups. A total of 70 subjects [median age, 53; 56% male; 56% HE grade 3; 44% HE grade 4; median model for end-stage liver disease (MELD) 32 (11-50) and CPT 13 (10-15)] were enrolled in 8 tertiary centers. Patients were randomized to ECAD + SMT (n = 39) or SMT alone (n = 31). Groups were matched in demographics and clinical variables. The improvement proportion of HE was higher in ECAD (mean, 34%; median, 30%) versus the SMT group (mean, 18.9%; median, 0%) (P = 0.044) and was reached faster and more frequently than in the SMT group (P = 0.045). Subjects receiving ECAD tolerated treatment well with no unexpected adverse events. The use of ECAD may be associated with an earlier and more frequent improvement of HE (grade 3/4). Because this 5-day study was not designed to examine the impact of MARS on survival, a full assessment of the role of albumin dialysis awaits the results of additional controlled trials.

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

NASA Technical Reports Server (NTRS)

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

1998-01-01

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

21 CFR 880.5045 - Medical recirculating air cleaner.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Medical recirculating air cleaner. 880.5045... Therapeutic Devices § 880.5045 Medical recirculating air cleaner. (a) Identification. A medical recirculating air cleaner is a device used to remove particles from the air for medical purposes. The device may...

21 CFR 880.5045 - Medical recirculating air cleaner.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Medical recirculating air cleaner. 880.5045... Therapeutic Devices § 880.5045 Medical recirculating air cleaner. (a) Identification. A medical recirculating air cleaner is a device used to remove particles from the air for medical purposes. The device may...

21 CFR 880.5045 - Medical recirculating air cleaner.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Medical recirculating air cleaner. 880.5045... Therapeutic Devices § 880.5045 Medical recirculating air cleaner. (a) Identification. A medical recirculating air cleaner is a device used to remove particles from the air for medical purposes. The device may...

21 CFR 880.5045 - Medical recirculating air cleaner.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Medical recirculating air cleaner. 880.5045 Section 880.5045 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Therapeutic Devices § 880.5045 Medical recirculating air cleaner. (a) Identification. A medical recirculating...

21 CFR 880.5045 - Medical recirculating air cleaner.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Medical recirculating air cleaner. 880.5045 Section 880.5045 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Therapeutic Devices § 880.5045 Medical recirculating air cleaner. (a) Identification. A medical recirculating...

Cycle O(CY1991) NLS trade studies and analyses report. Book 2, part 2: Propulsion

NASA Technical Reports Server (NTRS)

Cronin, R.; Werner, M.; Bonson, S.; Spring, R.; Houston, R.

1992-01-01

This report documents the propulsion system tasks performed in support of the National Launch System (NLS) Cycle O preliminary design activities. The report includes trades and analyses covering the following subjects: (1) Maximum Tank Stretch Study; (2) No LOX Bleed Performance Analysis; (3) LOX Bleed Trade Study; (4) LO2 Tank Pressure Limits; (5) LOX Tank Pressurization System Using Helium; (6) Space Transportation Main Engine (STME) Heat Exchanger Performance; (7) LH2 Passive Recirculation Performance Analysis; (8) LH2 Bleed/Recirculation Study; (9) LH2 Tank Pressure Limits; and (10) LH2 Pressurization System. For each trade study an executive summary and a detailed trade study are provided. For the convenience of the reader, a separate section containing a compilation of only the executive summaries is also provided.

Design validation and performance of closed loop gas recirculation system

NASA Astrophysics Data System (ADS)

Kalmani, S. D.; Joshi, A. V.; Majumder, G.; Mondal, N. K.; Shinde, R. R.

2016-11-01

A pilot experimental set up of the India Based Neutrino Observatory's ICAL detector has been operational for the last 4 years at TIFR, Mumbai. Twelve glass RPC detectors of size 2 × 2 m2, with a gas gap of 2 mm are under test in a closed loop gas recirculation system. These RPCs are continuously purged individually, with a gas mixture of R134a (C2H2F4), isobutane (iC4H10) and sulphur hexafluoride (SF6) at a steady rate of 360 ml/h to maintain about one volume change a day. To economize gas mixture consumption and to reduce the effluents from being released into the atmosphere, a closed loop system has been designed, fabricated and installed at TIFR. The pressure and flow rate in the loop is controlled by mass flow controllers and pressure transmitters. The performance and integrity of RPCs in the pilot experimental set up is being monitored to assess the effect of periodic fluctuation and transients in atmospheric pressure and temperature, room pressure variation, flow pulsations, uniformity of gas distribution and power failures. The capability of closed loop gas recirculation system to respond to these changes is also studied. The conclusions from the above experiment are presented. The validations of the first design considerations and subsequent modifications have provided improved guidelines for the future design of the engineering module gas system.

Enhancement of total nitrogen removal through effluent recirculation and fate of PPCPs in a hybrid constructed wetland system treating urban wastewater.

PubMed

Ávila, Cristina; Pelissari, Catiane; Sezerino, Pablo H; Sgroi, Massimiliano; Roccaro, Paolo; García, Joan

2017-04-15

The effect of effluent recirculation on the removal of total nitrogen (TN) and eight pharmaceuticals and personal care products (PPCPs) was evaluated during 9months in an experimental hybrid constructed wetland (CW) system applied in the treatment of urban wastewater. An Imhoff tank was followed by three stages of CWs (two 1.5-m 2 vertical subsurface flow (VF) beds alternating feed-rest cycles, a 2-m 2 horizontal (HF) and a 2-m 2 free water surface (FWS) wetland in series). A fraction of the final effluent was recycled back to the Imhoff tank with a recirculation rate of 50% (hydraulic loading rate=0.37md -1 ). The system's performance varied throughout the study. In Period I (summer) consistently high load removal efficiencies of TN (89±5%) and a removal rate of 6.6±1.4gTNm -2 d -1 were exhibited. In Period II (fall), the poor performance of the FWS during the senescence of macrophytes caused a large increase in organic matter, solids and nutrient concentrations, drastically deteriorating water quality. The determination of PPCPs was conducted during this period. Recalcitrant compounds, namely sulfamethoxazole, carbamazapine, TCEP and sucralose were negligibly removed in all CWs. However, noteworthy was the ≈30% removal of sucralose in the VF wetland. Caffeine (80%) and fluoxetine (27%) showed similar elimination rates in both VF and HF units, whereas trimethoprim and DEET were significantly better removed in the VF than in the HF. The concentration of the four latter compounds showed a severe increase in the FWS, indicating possible desorption from the sediment/biomass during adverse conditions. Harvesting of the aboveground biomass in this unit returned the system's performance back to normality (Period III), achieving 77±7% TN removal despite the winter season, proving effluent recirculation as an effective strategy for TN removal in hybrid CW systems when stringent restrictions are in place. Copyright © 2017 Elsevier B.V. All rights reserved.

Production of Tuber-Inducing Factor

NASA Technical Reports Server (NTRS)

Stutte, Gary W.; Yorio, Neil C.

2006-01-01

A process for making a substance that regulates the growth of potatoes and some other economically important plants has been developed. The process also yields an economically important by-product: potatoes. The particular growth-regulating substance, denoted tuber-inducing factor (TIF), is made naturally by, and acts naturally on, potato plants. The primary effects of TIF on potato plants are reducing the lengths of the main shoots, reducing the numbers of nodes on the main stems, reducing the total biomass, accelerating the initiation of potatoes, and increasing the edible fraction (potatoes) of the overall biomass. To some extent, these effects of TIF can override environmental effects that typically inhibit the formation of tubers. TIF can be used in the potato industry to reduce growth time and increase harvest efficiency. Other plants that have been observed to be affected by TIF include tomatoes, peppers, radishes, eggplants, marigolds, and morning glories. In the present process, potatoes are grown with their roots and stolons immersed in a nutrient solution in a recirculating hydroponic system. From time to time, a nutrient replenishment solution is added to the recirculating nutrient solution to maintain the required nutrient concentration, water is added to replace water lost from the recirculating solution through transpiration, and an acid or base is added, as needed, to maintain the recirculating solution at a desired pH level. The growing potato plants secrete TIF into the recirculating solution. The concentration of TIF in the solution gradually increases to a range in which the TIF regulates the growth of the plants.

Fan Performance From Duct Rake Instrumentation on a 1.294 Pressure Ratio, 725 ft/sec Tip Speed Turbofan Simulator Using Vaned Passage Casing Treatment

NASA Technical Reports Server (NTRS)

Fite, E. Brian

2006-01-01

A 1.294 pressure ratio, 725 ft/sec tip speed, variable pitch low noise fan was designed and tested in the NASA Glenn 9- by 15-foot Wind Tunnel. The design included a casing treatment that used recirculation to extend the fan stall line and provide an acceptable operating range. Overall aerodynamic experimental results are presented for this low tip speed, low noise fan without casing treatment as well as using several variants of the casing treatment that moved the air extraction and insertion axial locations. Measurements were made to assess effects on performance, operability, and noise. An unusual instability was discovered near the design operating line and is documented in the fan operating range. Measurements were made to compare stall margin improvements as well as measure the performance impact of the casing treatments. Experimental results in the presence of simulated inlet distortion, via screens, are presented for the baseline and recirculation casing treatment configurations. Estimates are made for the quantity of recirculation weight flow based on limited instrumentation in the recirculation system along with discussion of results and conclusions

Unravelling the active microbial community in a thermophilic anaerobic digester-microbial electrolysis cell coupled system under different conditions.

PubMed

Cerrillo, Míriam; Viñas, Marc; Bonmatí, August

2017-03-01

Thermophilic anaerobic digestion (AD) of pig slurry coupled to a microbial electrolysis cell (MEC) with a recirculation loop was studied at lab-scale as a strategy to increase AD stability when submitted to organic and nitrogen overloads. The system performance was studied, with the recirculation loop both connected and disconnected, in terms of AD methane production, chemical oxygen demand removal (COD) and volatile fatty acid (VFA) concentrations. Furthermore, the microbial population was quantitatively and qualitatively assessed through DNA and RNA-based qPCR and high throughput sequencing (MiSeq), respectively to identify the RNA-based active microbial populations from the total DNA-based microbial community composition both in the AD and MEC reactors under different operational conditions. Suppression of the recirculation loop reduced the AD COD removal efficiency (from 40% to 22%) and the methane production (from 0.32 to 0.03 m 3  m -3  d -1 ). Restoring the recirculation loop led to a methane production of 0.55 m 3  m -3  d -1 concomitant with maximum MEC COD and ammonium removal efficiencies of 29% and 34%, respectively. Regarding microbial analysis, the composition of the AD and MEC anode populations differed from really active microorganisms. Desulfuromonadaceae was revealed as the most active family in the MEC (18%-19% of the RNA relative abundance), while hydrogenotrophic methanogens (Methanobacteriaceae) dominated the AD biomass. Copyright © 2016 Elsevier Ltd. All rights reserved.

Slope stability of bioreactor landfills during leachate injection: effects of heterogeneous and anisotropic municipal solid waste conditions.

PubMed

Giri, Rajiv K; Reddy, Krishna R

2014-03-01

In bioreactor landfills, leachate recirculation can significantly affect the stability of landfill slope due to generation and distribution of excessive pore fluid pressures near side slope. The current design and operation of leachate recirculation systems do not consider the effects of heterogeneous and anisotropic nature of municipal solid waste (MSW) and the increased pore gas pressures in landfilled waste caused due to leachate recirculation on the physical stability of landfill slope. In this study, a numerical two-phase flow model (landfill leachate and gas as immiscible phases) was used to investigate the effects of heterogeneous and anisotropic nature of MSW on moisture distribution and pore-water and capillary pressures and their resulting impacts on the stability of a simplified bioreactor landfill during leachate recirculation using horizontal trench system. The unsaturated hydraulic properties of MSW were considered based on the van Genuchten model. The strength reduction technique was used for slope stability analyses as it takes into account of the transient and spatially varying pore-water and gas pressures. It was concluded that heterogeneous and anisotropic MSW with varied unit weight and saturated hydraulic conductivity significantly influenced the moisture distribution and generation and distribution of pore fluid pressures in landfill and considerably reduced the stability of bioreactor landfill slope. It is recommended that heterogeneous and anisotropic MSW must be considered as it provides a more reliable approach for the design and leachate operations in bioreactor landfills.

Control of biological growth in recirculating cooling systems using treated secondary effluent as makeup water with monochloramine.

PubMed

Chien, Shih-Hsiang; Chowdhury, Indranil; Hsieh, Ming-Kai; Li, Heng; Dzombak, David A; Vidic, Radisav D

2012-12-01

Secondary-treated municipal wastewater, an abundant and widely distributed impaired water source, is a promising alternative water source for thermoelectric power plant cooling. However, excessive biological growth is a major challenge associated with wastewater reuse in cooling systems as it can interfere with normal system operation as well as enhance corrosion and scaling problems. Furthermore, possible emission of biological aerosols (e.g., Legionella pneumophila) with the cooling tower drift can lead to public health concerns within the zone of aerosol deposition. In this study, the effectiveness of pre-formed and in-situ-formed monochloramine was evaluated for its ability to control biological growth in recirculating cooling systems using secondary-treated municipal wastewater as the only makeup water source. Bench-scale studies were compared with pilot-scale studies for their ability to predict system behavior under realistic process conditions. Effectiveness of the continuous addition of pre-formed monochloramine and monochloramine formed in-situ through the reaction of free chlorine with ammonia in the incoming water was evaluated in terms of biocide residual and its ability to control both planktonic and sessile microbial populations. Results revealed that monochloramine can effectively control biofouling in cooling systems employing secondary-treated municipal wastewater and has advantages relative to use of free chlorine, but that bench-scale studies seriously underestimate biocide dose and residual requirements for proper control of biological growth in full-scale systems. Pre-formed monochloramine offered longer residence time and more reliable performance than in-situ-formed monochloramine due to highly variable ammonia concentration in the recirculating water caused by ammonia stripping in the cooling tower. Pilot-scale tests revealed that much lower dosing rate was required to maintain similar total chlorine residual when pre-formed monochloramine was used as compared to in-situ-formed monochloramine. Adjustment of biocide dose to maintain monochloramine residual above 3mg/L is needed to achieve successful biological growth control in recirculating cooling systems using secondary-treated municipal effluent as the only source of makeup water. Copyright © 2012 Elsevier Ltd. All rights reserved.

40 CFR 451.2 - General definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

..., constructed of earth, concrete, plastic, or metal to which water is supplied by nearby rivers or springs... constitute real-time monitoring. (n) Recirculating system means a system that filters and reuses water in...

40 CFR 451.2 - General definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., constructed of earth, concrete, plastic, or metal to which water is supplied by nearby rivers or springs... constitute real-time monitoring. (n) Recirculating system means a system that filters and reuses water in...

40 CFR 451.2 - General definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

..., constructed of earth, concrete, plastic, or metal to which water is supplied by nearby rivers or springs... constitute real-time monitoring. (n) Recirculating system means a system that filters and reuses water in...

40 CFR 451.2 - General definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

..., constructed of earth, concrete, plastic, or metal to which water is supplied by nearby rivers or springs... constitute real-time monitoring. (n) Recirculating system means a system that filters and reuses water in...

40 CFR 451.2 - General definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., constructed of earth, concrete, plastic, or metal to which water is supplied by nearby rivers or springs... constitute real-time monitoring. (n) Recirculating system means a system that filters and reuses water in...

Effect of self recirculation casing treatment on the performance of a turbocharger centrifugal compressor

NASA Astrophysics Data System (ADS)

Gancedo, Matthieu

Increase in emission regulations in the transport industry brings the need to have more efficient engines. A path followed by the automobile industry is to downsize the size of the internal combustion engine and increase the air density at the intake to keep the engine power when needed. Typically a centrifugal compressor is used to force the air into the engine, it can be powered from the engine shaft (superchargers) or extracting energy contained into the hot exhaust gases with a turbine (turbochargers). The flow range of the compressor needs to match the one of the engine. However compressors mass flow operating range is limited by choke on the high end and surge on the low end. In order to extend the operation at low mass flow rates, the use of passive devices for turbocharger centrifugal compressors was explored since the late 80's. Hence, casing treatments including flow recirculation from the inducer part of the compressor have been shown to move the surge limit to lower flows. Yet, the working mechanisms are still not well understood and thus, to optimize the design of this by-pass system, it is necessary to determine the nature of the changes induced by the device both on the dynamic stability of the pressure delivery and on the flow at the inlet. The compressor studied here features a self-recirculating casing treatment at the inlet. The recirculation passage could be blocked to carry a direct comparison between the cases with and without the flow feature. To grasp the effect on compressor stability, pressure measurements were taken in the different constituting elements of the compressor. The study of the mean pressure variations across the operating map showed that the tongue region is a limiting element. Dynamic pressure measurements revealed that the instabilities generated near the inducer when the recirculation is blocked increase the overall instability levels at the compressor outlet and propagating pressure waves starting at the tongue occurred, different in nature from rotating stall. The flow velocity was also measured at the inlet of the compressor by means of planar PIV measurements. The case without recirculation showed strong back flow occurrence at low MFR on the shroud of the inlet passage due to tip recirculation. With recirculation, this back flow was significantly reduced improving the overall stability. However, with the current recirculation channels design, there is an efficiency penalty and the recirculated flow introduces non-homogeneities in the mixing region. Finally, to explore experimentally the effect of variations of the casing treatment, several different designs were tested. It was seen that modifications of the supporting rib shape impacted the efficiency. Also, improvements on the surge line were obtained with flow reinjection near the inducer in the direction of the main flow at low speeds and with induced counter swirl for all speeds.

Process for producing vegetative and tuber growth regulator

NASA Technical Reports Server (NTRS)

Yorio, Neil C. (Inventor); Stutte, Gary W. (Inventor)

1999-01-01

A process of making a vegetative and tuber growth regulator. The vegetative and tuber growth regulator is made by growing potato plants in a recirculating hydroponic system for a sufficient time to produce the growth regulator. Also, the use of the vegetative and growth regulator on solanaceous plants, tuber forming plants and ornamental seedlings by contacting the roots or shoots of the plant with a sufficient amount of the growth regulator to regulate the growth of the plant and one more of canopy size, plant height, stem length, internode number and presence of tubers in fresh mass. Finally, a method for regulating the growth of potato plants using a recirculating hydroponic system is described.

Convective Mixing in Distal Pipes Exacerbates Legionella pneumophila Growth in Hot Water Plumbing.

PubMed

Rhoads, William J; Pruden, Amy; Edwards, Marc A

2016-03-12

Legionella pneumophila is known to proliferate in hot water plumbing systems, but little is known about the specific physicochemical factors that contribute to its regrowth. Here, L. pneumophila trends were examined in controlled, replicated pilot-scale hot water systems with continuous recirculation lines subject to two water heater settings (40 °C and 58 °C) and three distal tap water use frequencies (high, medium, and low) with two pipe configurations (oriented upward to promote convective mixing with the recirculating line and downward to prevent it). Water heater temperature setting determined where L. pneumophila regrowth occurred in each system, with an increase of up to 4.4 log gene copies/mL in the 40 °C system tank and recirculating line relative to influent water compared to only 2.5 log gene copies/mL regrowth in the 58 °C system. Distal pipes without convective mixing cooled to room temperature (23-24 °C) during periods of no water use, but pipes with convective mixing equilibrated to 30.5 °C in the 40 °C system and 38.8 °C in the 58 °C system. Corresponding with known temperature effects on L. pneumophila growth and enhanced delivery of nutrients, distal pipes with convective mixing had on average 0.2 log more gene copies/mL in the 40 °C system and 0.8 log more gene copies/mL in the 58 °C system. Importantly, this work demonstrated the potential for thermal control strategies to be undermined by distal taps in general, and convective mixing in particular.

Coastal recirculation potential affecting air pollutants in Portugal: The role of circulation weather types

NASA Astrophysics Data System (ADS)

Russo, Ana; Gouveia, Célia; Levy, Ilan; Dayan, Uri; Jerez, Sonia; Mendes, Manuel; Trigo, Ricardo

2016-06-01

Coastal zones are under increasing development and experience air pollution episodes regularly. These episodes are often related to peaks in local emissions from industry or transportation, but can also be associated with regional transport from neighbour urban areas influenced by land-sea breeze recirculation. This study intends to analyze the relation between circulation weather patterns, air mass recirculation and pollution levels in three coastal airsheds of Portugal (Lisbon, Porto and Sines) based on the application of an objective quantitative measure of potential recirculation. Although ventilation events have a dominant presence throughout the studied 9-yrs period on all the three airsheds, recirculation and stagnation conditions occur frequently. The association between NO2, SO2 and O3 levels and recirculation potential is evident during summer months. Under high average recirculation potential and high variability, NO2 and SO2 levels are higher for the three airsheds, whilst for O3 each airshed responds differently. This indicates a high heterogeneity among the three airsheds in (1) the type of emission - traffic or industry - prevailing for each contaminant, and (2) the response to the various circulation weather patterns and recirculation situations. Irrespectively of that, the proposed methodology, based on iterative K-means clustering, allows to identify which prevailing patterns are associated with high recirculation potential, having the advantage of being applicable to any geographical location.

Benefits of Using a Mars Forward Strategy for Lunar Surface Systems

NASA Technical Reports Server (NTRS)

Mulqueen, Jack; Griffin, Brand; Smitherman, David; Maples, Dauphne

2009-01-01

This paper identifies potential risk reduction, cost savings and programmatic procurement benefits of a Mars Forward Lunar Surface System architecture that provides commonality or evolutionary development paths for lunar surface system elements applicable to Mars surface systems. The objective of this paper is to identify the potential benefits for incorporating a Mars Forward development strategy into the planned Project Constellation Lunar Surface System Architecture. The benefits include cost savings, technology readiness, and design validation of systems that would be applicable to lunar and Mars surface systems. The paper presents a survey of previous lunar and Mars surface systems design concepts and provides an assessment of previous conclusions concerning those systems in light of the current Project Constellation Exploration Architectures. The operational requirements for current Project Constellation lunar and Mars surface system elements are compared and evaluated to identify the potential risk reduction strategies that build on lunar surface systems to reduce the technical and programmatic risks for Mars exploration. Risk reduction for rapidly evolving technologies is achieved through systematic evolution of technologies and components based on Moore's Law superimposed on the typical NASA systems engineering project development "V-cycle" described in NASA NPR 7120.5. Risk reduction for established or slowly evolving technologies is achieved through a process called the Mars-Ready Platform strategy in which incremental improvements lead from the initial lunar surface system components to Mars-Ready technologies. The potential programmatic benefits of the Mars Forward strategy are provided in terms of the transition from the lunar exploration campaign to the Mars exploration campaign. By utilizing a sequential combined procurement strategy for lunar and Mars exploration surface systems, the overall budget wedges for exploration systems are reduced and the costly technological development gap between the lunar and Mars programs can be eliminated. This provides a sustained level of technological competitiveness as well as maintaining a stable engineering and manufacturing capability throughout the entire duration of Project Constellation.

Evaluation of a cost effective technique for treating aquaculture water discharge using Lolium perenne Lam as a biofilter.

PubMed

Nduwimana, André; Yang, Xiang-Long; Wang, Li-Ren

2007-01-01

Wastewater stabilization ponds generate low cost by-products that are useful for agriculture. The utilization of these by-products for soil amendment and as a source of nutrients for plants requires a high level of sanitation and stabilization of the organic matter, to maintain acceptable levels of soil, water and air quality. In this study, two aquaculture wastewater treatment systems; recirculating system and a floating plant bed system were designed to improve the quality of irrigation water in local communities with low income. In both systems the grass species Lolium perenne Lam was used as a plant biofilter while vegetable specie Amaranthus viridis was used to evaluate the performance of the system and the suitability of the phyto-treated water for irrigation. It was found that the harmful material removal rate for recirculating system was 88.9% for TAN (total ammonia nitrogen), 90% for NO2(-)-N, 64.8% for NO3(-)-N while for floating plant bed system 82.7% for TAN, 82% for NO2(-)-N and 60.5% for NO3(-)-N. Comparative analysis of the efficiency of waste element removal between the two systems revealed that both systems performed well, however, plant growth was not robust for floating plant bed system while recirculating system is energy consuming. Although both systems did not attain sufficient levels of TN (total nitrogen) and TP (total phosphorus) load reduction, the treatment with L. perenne remarkably improved the irrigation water quality. A. viridis plants irrigated with the phyto-treated discharge water had lesser concentrations of heavy metals in their tissues compared to those irrigated with untreated discharge. The control plants irrigated with untreated discharge were also found to be highly lignified with few stems and small leaves.

Metagenomic analysis of antibiotic resistance genes in coastal industrial mariculture systems.

PubMed

Wang, Jian-Hua; Lu, Jian; Zhang, Yu-Xuan; Wu, Jun; Luo, Yongming; Liu, Hao

2018-04-01

The overuse of antibiotics has posed a propagation of antibiotic resistance genes (ARGs) in aquaculture systems. This study firstly explored the ARGs profiles of the typical mariculture farms including conventional and recirculating systems using metagenomics approach. Fifty ARGs subtypes belonging to 21 ARGs types were identified, showing the wide-spectrum profiles of ARGs in the coastal industrial mariculture systems. ARGs with multiple antibiotics resistance have emerged in the mariculure systems. The co-occurrence pattern between ARGs and microbial taxa showed that Proteobacteria and Bacteroidetes were potential dominant hosts of ARGs in the industrial mariculture systems. Typical nitrifying bacteria such as Nitrospinae in mariculture systems also carried with some resistance genes. Relative abundance of ARGs in fish ponds and wastewater treatment units was relatively high. The investigation showed that industrial mariculture systems were important ARGs reservoirs in coastal area, indicating the critical role of recirculating systems in the terms of ARGs pollution control. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparison of recirculation configurations for biological nutrient removal in a membrane bioreactor.

PubMed

Bekir Ersu, Cagatayhan; Ong, Say Kee; Arslankaya, Ertan; Brown, Patrick

2008-03-01

A 12-L lab-scale membrane bioreactor (MBR), consisting of an anaerobic and anoxic compartment followed by an oxic plate-frame membrane compartment, was evaluated for carbonaceous and nutrient removals by varying the recirculation of mixed liquor and permeate. The hydraulic retention times (HRTs) for the anaerobic, anoxic, and oxic compartments were 2, 2, and 8h, respectively. The solids residence time (SRT) for the oxic compartment was 25 days. Five different recirculation configurations were tested by recirculating mixed liquor and/or permeate recirculation equal to the influent flow rate (identified as 100%) into different locations of the anaerobic and anoxic compartments. Of the five configurations, the configuration with 100% mixed liquor recirculation to the anaerobic compartment and 100% permeate recirculation to the anoxic compartment gave the highest percentage removal with an average 92.3+/-0.5% soluble chemical oxygen demand (sCOD), 75.6+/-0.4% total nitrogen (TN), and 62.4+/-1.3% total phosphorus (TP) removal. When the mixed liquor and permeate recirculation rates were varied for the same configuration, the highest TP removal was obtained for 300% mixed liquor recirculation and 100% permeate recirculation (300%/100%) with a TP removal of 88.1+/-1.3% while the highest TN removal (90.3+/-0.3%) was obtained for 200%/300% recirculation. TN and TP concentrations as low as 4.2+/-0.1 and 1.4+/-0.2mg/L respectively were obtained. Mass loading rates were generally low in the range of 0.11-0.22kgCOD/kgMLSS/d due to high biomass concentrations within the oxic reactor (approx. 8000mg/L). The BioWin model was calibrated against one set of the experimental data and was found to predict the experimental data of effluent TN, TP, and NO(3)(-)-N but over-predicted sCOD and NH(3)-N for various recirculation rates. The anoxic heterotrophic yield for the calibrated model was 0.2kg biomass COD/kg COD utilized while the maximum growth rates were found to be 0.45day(-1) for mu(max-autotroph), 3.2day(-1) for mu(max-heterotroph), and 1.5day(-1) for mu(max-PAO).

Evaluation of a recirculating pond system for rearing juvenile freshwater mussels at White Sulphur Springs National Fish Hatchery, West Virginia, U.S.A.

USGS Publications Warehouse

Mummert, A.; Newcomb, T.J.; Neves, R.J.; Parker, B.

2006-01-01

A recirculating double-pond system at White Sulphur Springs National Fish Hatchery in West Virginia, U.S.A., was evaluated for suitability for culturing juvenile freshwater mussels. Newly metamorphosed juveniles of Villosa iris and Lampsilis fasciola were placed in the system, and their growth and survival were evaluated for 94 days. Throughout the study, parameters of water quality remained within ranges suitable for mussel survival. Planktonic algal densities in the pond system ranged from 2850 to 6892 cells/ml. Thirty-seven algal taxa were identified, primarily green algae (Chlorophyta), diatoms (Bacillariophyceae), and blue-green algae (Cyanoprokaryota). Over the culture period, juveniles of L. fasciola experienced significantly lower (p < 0.001) survival (6.3% ?? 4.5) than those of V. iris (49.8% ?? 14.5). The very low survival rate of L. fasciola may indicate a failure of the flow-through pond environment to meet its habitat requirements or that variable microhabitat conditions within culture containers existed. Growth did not differ significantly between the species (p = 0.13). Survival of V. iris and growth of both species were similar to previous trials to culture juvenile mussels. Survival rates as high as 66.4% at 93 days for V. iris suggest that juveniles of some riverine species can be successfully cultured in a recirculating pond environment.

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

PubMed

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

2014-01-01

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. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

Pumps vs. airlifts: Theoretical and practical energy implications

USDA-ARS?s Scientific Manuscript database

In the design of a recirculating aquaculture system five life-supporting issues should be considered which include aeration, degasification, circulation, biofiltration, and clarification. The implications associated with choosing a pumped system versus an airlift system to address these issues was e...

Semi-continuous anaerobic co-digestion of cow manure and steam-exploded Salix with recirculation of liquid digestate.

PubMed

Estevez, Maria M; Sapci, Zehra; Linjordet, Roar; Schnürer, Anna; Morken, John

2014-04-01

The effects of recirculating the liquid fraction of the digestate during mesophilic anaerobic co-digestion of steam-exploded Salix and cow manure were investigated in laboratory-scale continuously stirred tank reactors. An average organic loading rate of 2.6 g VS L(-1) d(-1) and a hydraulic retention time (HRT) of 30 days were employed. Co-digestion of Salix and manure gave better methane yields than digestion of manure alone. Also, a 16% increase in the methane yield was achieved when digestate was recirculated and used instead of water to dilute the feedstock (1:1 dilution ratio). The reactor in which the larger fraction of digestate was recirculated (1:3 dilution ratio) gave the highest methane yields. Ammonia and volatile fatty acids did not reach inhibitory levels, and some potentially inhibitory compounds released during steam explosion (i.e., furfural and 5-hydroxy methyl furfural) were only detected at trace levels throughout the entire study period. However, accumulation of solids, which was more pronounced in the recycling reactors, led to decreased methane yields in those systems after three HRTs. Refraining from the use of fresh water to dilute biomass with a high-solids content and obtaining a final digestate with increased dry matter content might offer important economic benefits in full-scale processes. To ensure long-term stability in such an approach, it would be necessary to optimize separation of the fraction of digestate to be recirculated and also perform proper monitoring to avoid accumulation of solids. Copyright © 2014 Elsevier Ltd. All rights reserved.

Calculation of recirculating flow behind flame-holders

NASA Astrophysics Data System (ADS)

Zeng, Q.; Sheng, Y.; Zhou, Q.

1985-10-01

Adoptability of standard K-epsilon turbulence model for numerical calculation of recirculating flow is discussed. Many computations of recirculating flows behind bluff-bodies used as flame-holders in afterburner of aeroengine have been completed. Blocking-off method to treat the incline walls of the flame-holder gives good results. In isothermal recirculating flows the flame-holder wall is assumed to be isolated. Therefore, it is possible to remove the inactive zone from the calculation domain in programming to save computer time. The computation for a V-shaped flame-holder exhibits an interesting phenomenon that the recirculation zone extends to the cavity of the flame-holder.

Novel recirculating loop reactor for studies on model catalysts: CO oxidation on Pt/TiO2(110)

NASA Astrophysics Data System (ADS)

Tenney, Samuel A.; Xie, Kangmin; Monnier, John R.; Rodriguez, Abraham; Galhenage, Randima P.; Duke, Audrey S.; Chen, Donna A.

2013-10-01

A novel recirculating loop microreactor coupled to an ultrahigh vacuum (UHV) chamber has been constructed for the kinetic evaluation of model catalysts, which can be fully characterized by UHV surface science techniques. The challenge for this reactor design is to attain sufficient sensitivity to detect reactions on model single-crystal surfaces, which have a low number of active sites compared to conventional catalysts of equivalent mass. To this end, the total dead volume of the reactor system is minimized (32 cm3), and the system is operated in recirculation mode so that product concentrations build up to detectable levels over time. The injection of gas samples into the gas chromatography column and the refilling of the recirculation loop with fresh feed gas are achieved with computer-controlled, automated switching valves. In this manner, product concentrations can be followed over short time intervals (15 min) for extended periods of time (24 h). A proof of principle study in this reactor for CO oxidation at 145-165 °C on Pt clusters supported on a rutile TiO2(110) single crystal yields kinetic parameters that are comparable to those reported in the literature for CO oxidation on Pt clusters on powdered oxide supports, as well as on Pt(100). The calculated activation energy is 16.4 ± 0.7 kcal/mol, the turnover frequency is 0.03-0.06 molecules/(site.s) over the entire temperature range, and the reaction orders in O2 and CO at 160 °C are 0.9 ± 0.2 and -0.82 ± 0.03, respectively.

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

PubMed

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

2015-03-01

Two identical microbial fuel cells (MFCs) with a floating air-cathode were operated under either buffered (MFC-B) or bufferless (MFC-BL) conditions to investigate anolyte recirculation effects on enhancing proton transfer. With an external resistance of 50 Ω and recirculation rate of 1.0 ml/min, MFC-BL had a 27% lower voltage (9.7% lower maximal power density) but a 64% higher Coulombic efficiency (CE) than MFC-B. MFC-B had a decreased voltage output, batch time, and CE with increasing recirculation rate resulting from more oxygen transfer into the anode. However, increasing the recirculation rate within a low range significantly enhanced proton transfer in MFC-BL, resulting in a higher voltage output, a longer batch time, and a higher CE. A further increase in recirculation rate decreased the batch time and CE of MFC-BL due to excess oxygen transfer into anode outweighing the proton-transfer benefits. The unbuffered MFC had an optimal recirculation rate of 0.35 ml/min. Copyright © 2014 Elsevier Ltd. All rights reserved.

The case for Mars III: Strategies for exploration - General interest and overview

NASA Technical Reports Server (NTRS)

Stoker, Carol R. (Editor)

1989-01-01

Papers on the possibilities for manned Mars missions are presented, covering topics such as space policy, space education and Mars exploration, economic issues, international cooperation, life support, biomedical factors, human factors, the Mars Rover Sample Return Mission, and possible unmanned precursor missions to Mars. Other topics include the scientific objectives for human exploration of Mars, mission strategies, possible transportation systems for manned Mars flight, advanced propulsion techniques, and the utilization of Mars resources. Additional subjects include the construction and maintenance of a Martian base, possible systems for mobility on the Martian surface, space power systems, and the use of the Space Station for a Mars mission.

National Combustion Code Validated Against Lean Direct Injection Flow Field Data

NASA Technical Reports Server (NTRS)

Iannetti, Anthony C.

2003-01-01

Most combustion processes have, in some way or another, a recirculating flow field. This recirculation stabilizes the reaction zone, or flame, but an unnecessarily large recirculation zone can result in high nitrogen oxide (NOx) values for combustion systems. The size of this recirculation zone is crucial to the performance of state-of-the-art, low-emissions hardware. If this is a large-scale combustion process, the flow field will probably be turbulent and, therefore, three-dimensional. This research dealt primarily with flow fields resulting from lean direct injection (LDI) concepts, as described in Research & Technology 2001. LDI is a concept that depends heavily on the design of the swirler. The LDI concept has the potential to reduce NOx values from 50 to 70 percent of current values, with good flame stability characteristics. It is cost effective and (hopefully) beneficial to do most of the design work for an LDI swirler using computer-aided design (CAD) and computer-aided engineering (CAE) tools. Computational fluid dynamics (CFD) codes are CAE tools that can calculate three-dimensional flows in complex geometries. However, CFD codes are only beginning to correctly calculate the flow fields for complex devices, and the related combustion models usually remove a large portion of the flow physics.

In-vehicle carbon dioxide concentration in commuting cars in Bangkok, Thailand.

PubMed

Luangprasert, Maytat; Vasithamrong, Chainarin; Pongratananukul, Suphasit; Chantranuwathana, Sunhapos; Pumrin, Suree; De Silva, I P D

2017-05-01

It is known that in-vehicle carbon dioxide (CO 2 ) concentration tends to increase due to occupant exhalation when the HVAC (heating, ventilation, and air conditioning) air is in recirculation mode. Field experiments were conducted to measure CO 2 concentration during typical commute in Bangkok, Thailand. The measured concentrations agreed with the concentration predicted using first-order mass balance equation, in both recirculating and outside air modes. The long-term transient decay of the concentration when the vehicle was parked and the HVAC system was turned off was also studied. This decay was found to follow Fickian diffusion process. The paper also provides useful operational details of the automotive HVAC system and fresh air ventilation exchange between cabin interior and exterior. Drivers in tropical Asian countries typically use HVAC recirculation mode in their automobiles. This behavior leads to excessive buildup of cabin CO 2 concentration levels. The paper describes the CO 2 buildup in a typical commute in Bangkok, Thailand. Auto manufacturers can potentially take measures to alleviate such high concentration levels. The paper also discusses the diffusion of CO 2 through the vehicle envelope, an area that has never been investigated before.

Telecommunications systems evolution for Mars Exploration

NASA Technical Reports Server (NTRS)

Noreen, Gary; De Paula, Ramon P.; Edwards, Charles D. Jr; Komarek, Thomas; Edwards, Bernard L.; Edwards, Bernard L.; Kerridge, Stuart J.; Diehl, Roger; Franklin, Stephen F.

2003-01-01

This paper describes the evolution of telecommunication systems at Mars. It reviews the telecommunications capabilities, technology and limiting factors of current and planned Mars orbiters from Mars Global Surveyor to the planned Mars Telecommunications Orbiter (MTO).

The NASA Mars Conference

NASA Astrophysics Data System (ADS)

Reiber, Duke B.

Papers about Mars and Mars exploration are presented, covering topics such as Martian history, geology, volcanism, channels, moons, atmosphere, meteorology, water on the planet, and the possibility of life. The unmanned exploration of Mars is discussed, including the Phobos Mission, the Mars Observer, the Mars Aeronomy Observer, the seismic network, Mars sample return missions, and the Mars Ball, an inflatable-sectored-tire rover concept. Issues dealing with manned exploration of Mars are examined, such as the reasons for exploring Mars, mission scenarios, a transportation system for routine visits, technologies for Mars expeditions, the human factors for Mars missions, life support systems, living and working on Mars, and the report of the National Commission on Space.

Automated information-analytical system for thunderstorm monitoring and early warning alarms using modern physical sensors and information technologies with elements of artificial intelligence

NASA Astrophysics Data System (ADS)

Boldyreff, Anton S.; Bespalov, Dmitry A.; Adzhiev, Anatoly Kh.

2017-05-01

Methods of artificial intelligence are a good solution for weather phenomena forecasting. They allow to process a large amount of diverse data. Recirculation Neural Networks is implemented in the paper for the system of thunderstorm events prediction. Large amounts of experimental data from lightning sensors and electric field mills networks are received and analyzed. The average recognition accuracy of sensor signals is calculated. It is shown that Recirculation Neural Networks is a promising solution in the forecasting of thunderstorms and weather phenomena, characterized by the high efficiency of the recognition elements of the sensor signals, allows to compress images and highlight their characteristic features for subsequent recognition.

Convective Mixing in Distal Pipes Exacerbates Legionella pneumophila Growth in Hot Water Plumbing

PubMed Central

Rhoads, William J.; Pruden, Amy; Edwards, Marc A.

2016-01-01

Legionella pneumophila is known to proliferate in hot water plumbing systems, but little is known about the specific physicochemical factors that contribute to its regrowth. Here, L. pneumophila trends were examined in controlled, replicated pilot-scale hot water systems with continuous recirculation lines subject to two water heater settings (40 °C and 58 °C) and three distal tap water use frequencies (high, medium, and low) with two pipe configurations (oriented upward to promote convective mixing with the recirculating line and downward to prevent it). Water heater temperature setting determined where L. pneumophila regrowth occurred in each system, with an increase of up to 4.4 log gene copies/mL in the 40 °C system tank and recirculating line relative to influent water compared to only 2.5 log gene copies/mL regrowth in the 58 °C system. Distal pipes without convective mixing cooled to room temperature (23–24 °C) during periods of no water use, but pipes with convective mixing equilibrated to 30.5 °C in the 40 °C system and 38.8 °C in the 58 °C system. Corresponding with known temperature effects on L. pneumophila growth and enhanced delivery of nutrients, distal pipes with convective mixing had on average 0.2 log more gene copies/mL in the 40 °C system and 0.8 log more gene copies/mL in the 58 °C system. Importantly, this work demonstrated the potential for thermal control strategies to be undermined by distal taps in general, and convective mixing in particular. PMID:26985908

Control of the mixing time in vessels agitated by submerged recirculating jets.

PubMed

Kennedy, Stephen; Bhattacharjee, Pradipto K; Bhattacharya, Sati N; Eshtiaghi, Nicky; Parthasarathy, Rajarathinam

2018-01-01

Submerged recirculating jet mixing systems are an efficient and economical method of agitating large tanks with a high hydraulic residence time. Much work has been carried out in developing design correlations to aid the predictions of the mixing time in such systems, with the first such correlation being developed nearly 70 years ago. In most of these correlations, the mixing time depends directly on the volume of the vessel and inversely on the injection velocity of the submerged jet. This work demonstrates, for the first time, that the distance between the injection and suction nozzles also significantly affects the mixing time and can be used to control this time scale. The study introduces a non-dimensional quantity that can be used as an adjustable parameter in systems where such control is desired.

Control of the mixing time in vessels agitated by submerged recirculating jets

PubMed Central

Bhattacharjee, Pradipto K.; Bhattacharya, Sati N.; Eshtiaghi, Nicky; Parthasarathy, Rajarathinam

2018-01-01

Submerged recirculating jet mixing systems are an efficient and economical method of agitating large tanks with a high hydraulic residence time. Much work has been carried out in developing design correlations to aid the predictions of the mixing time in such systems, with the first such correlation being developed nearly 70 years ago. In most of these correlations, the mixing time depends directly on the volume of the vessel and inversely on the injection velocity of the submerged jet. This work demonstrates, for the first time, that the distance between the injection and suction nozzles also significantly affects the mixing time and can be used to control this time scale. The study introduces a non-dimensional quantity that can be used as an adjustable parameter in systems where such control is desired. PMID:29410817

40 CFR 98.468 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-07-01

... applicable climate classification is determined based on the annual rainfall plus the recirculated leachate... [with appropriate unit conversions]. (1) Dry climate = precipitation plus recirculated leachate less than 20 inches/year. (2) Moderate climate = precipitation plus recirculated leachate from 20 to 40...

Numerical analysis of biomass torrefaction reactor with recirculation of heat carrier

NASA Astrophysics Data System (ADS)

Director, L. B.; Ivanin, O. A.; Sinelshchikov, V. A.

2018-01-01

In this paper, results of numerical analysis of the energy-technological complex consisting of the gas piston power plant, the torrefaction reactor with recirculation of gaseous heat carrier and the heat recovery boiler are presented. Calculations of the reactor without recirculation and with recirculation of the heat carrier in torrefaction zone at different frequencies of unloading of torrefied biomass were held. It was shown that in recirculation mode the power of the gas piston power plant, required for providing given reactor productivity, is reduced several times and the consumption of fuel gas, needed for combustion of volatile torrefaction products in the heat recovery boiler, is reduced by an order.

Exhaust gas recirculation in a homogeneous charge compression ignition engine

DOEpatents

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

2008-05-27

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

Flow field in the wake of a bluff body driven through a steady recirculating flow

NASA Astrophysics Data System (ADS)

Poussou, Stephane B.; Plesniak, Michael W.

2015-02-01

The wake produced by a bluff body driven through a steady recirculating flow is studied experimentally in a water facility using particle image velocimetry. The bluff body has a rectangular cross section of height, , and width, , such that the aspect ratio, AR = H/ D, is equal to 3. The motion of the bluff body is uniform and rectilinear, and corresponds to a Reynolds number based on width, Re D = 9,600. The recirculating flow is confined within a hemicylindrical enclosure and is generated by planar jets emanating from slots of width, , such that . Under these conditions, experiments are performed in a closed-loop facility that enables complete optical access to the near-wake. Velocity fields are obtained up to a distance of downstream of the moving body. Data include a selection of phase-averaged velocity fields representative of the wake for a baseline case (no recirculation) and an interaction case (with recirculation). Results indicate that the transient downwash flow typically observed in wakes behind finite bodies of small aspect ratio is significantly perturbed by the recirculating flow. The wake is displaced from the ground plane and exhibits a shorter recirculation zone downstream of the body. In summary, it was found that the interaction between a bluff body wake and a recirculating flow pattern alters profoundly the dynamics of the wake, which has implications on scalar transport in the wake.

Controlling And Operating Homogeneous Charge Compression Ignition (Hcci) Engines

DOEpatents

Flowers, Daniel L.

2005-08-02

A Homogeneous Charge Compression Ignition (HCCI) engine system includes an engine that produces exhaust gas. A vaporization means vaporizes fuel for the engine an air induction means provides air for the engine. An exhaust gas recirculation means recirculates the exhaust gas. A blending means blends the vaporized fuel, the exhaust gas, and the air. An induction means inducts the blended vaporized fuel, exhaust gas, and air into the engine. A control means controls the blending of the vaporized fuel, the exhaust gas, and the air and for controls the inducting the blended vaporized fuel, exhaust gas, and air into the engine.

40 CFR 1039.801 - What definitions apply to this part?

Code of Federal Regulations, 2013 CFR

2013-07-01

... the environment. Exhaust-gas recirculation (EGR) and turbochargers are not aftertreatment. Aircraft..., modulating, delaying, or deactivating the operation of any part of the emission-control system. Brake power... suppression operations. Emission-control system means any device, system, or element of design that controls...

29 CFR 1910.1027 - Cadmium.

Code of Federal Regulations, 2011 CFR

2011-07-01

..., measurements that demonstrate the effectiveness of the system in controlling exposure, such as capture velocity...) Measurements of the system's effectiveness in controlling exposure shall be made as necessary within five... recirculated into the workplace, the system shall have a high efficiency filter and be monitored to assure...

An Interactive Real-time Decision Support System for Leachate Irrigation on Evapotranspiration Landfill Covers

NASA Astrophysics Data System (ADS)

Wang, Y.

2015-12-01

Landfill disposal is still the most common and economical practice for municipal solid waste in most countries. However, heavily polluted leachate generated by excess rainwater percolating through the landfill waste is the major drawback of this practice. Evapotranspiration (ET) cover systems are increasingly being used as alternative cover systems to minimize percolation by evapotranspiration. Leachate recirculation is one of the least expensive options for leachate treatment. The combination of ET cover systems and leachate recirculation can be an economical and environment-friendly practice for landfill leachate management. An interactive real-time decision support system is being developed to better manage leachate irrigation using historical and forecasting weather data, and real time soil moisture data. The main frame of this system includes soil water modules, and plant-soil modules. An inverse simulation module is also included to calibrate certain parameters based on observed data when necessary. It would be an objectives-oriented irrigation management tool to minimize landfill operation costs and negative environmental impacts.

An Overview of Mars Vicinity Transportation Concepts for a Human Mars Mission

NASA Technical Reports Server (NTRS)

Dexter, Carol E.; Kos, Larry

1998-01-01

To send a piloted mission to Mars, transportation systems must be developed for the Earth to Orbit, trans Mars injection (TMI), capture into Mars orbit, Mars descent, surface stay, Mars ascent, trans Earth injection (TEI), and Earth return phases. This paper presents a brief overview of the transportation systems for the Human Mars Mission (HMM) only in the vicinity of Mars. This includes: capture into Mars orbit, Mars descent, surface stay, and Mars ascent. Development of feasible mission scenarios now is important for identification of critical technology areas that must be developed to support future human missions. Although there is no funded human Mars mission today, architecture studies are focusing on missions traveling to Mars between 2011 and the early 2020's.

The effects of aquaculture production noise on the growth, condition factor, feed conversion, and survival of rainbow trout, Oncorhynchus mykiss

USDA-ARS?s Scientific Manuscript database

Intensive aquaculture systems, particularly recirculating systems, utilize equipment such as aerators, air and water pumps, blowers, and filtration systems that inadvertently increase noise levels in fish culture tanks. Sound levels and frequencies measured within intensive aquaculture systems are w...

Human skin is protected by four functionally and phenotypically discrete populations of resident and recirculating memory T cells

PubMed Central

Watanabe, Rei; Gehad, Ahmed; Yang, Chao; Campbell, Laura; Teague, Jessica E.; Schlapbach, Christoph; Elco, Christopher; Huang, Victor; Matos, Tiago R.; Kupper, Thomas S.; Clark, Rachael A.

2015-01-01

The skin of an adult human contains approximately 20 billion memory T cells. Epithelial barrier tissues are infiltrated by a combination of resident and recirculating T cells in mice but the relative proportions and functional activities of resident versus recirculating T cells have not been evaluated in human skin. We discriminated resident from recirculating T cells in human engrafted mice and lymphoma patients using alemtuzumab, a medication that depletes recirculating T cells from skin, and then analyzed these T cell populations in healthy human skin. All non-recirculating resident memory T cells (TRM) expressed CD69, but the majority were CD4+, CD103− and located in the dermis, in contrast to studies in mice. Both CD4+ and CD8+ CD103+ TRM were enriched in the epidermis, had potent effector functions and had a limited proliferative capacity compared to CD103− TRM. TRM of both types had more potent effector functions than recirculating T cells. Induction of CD103 on human T cells was enhanced by keratinocyte contact, depended on TGFβ and was independent of T cell keratinocyte adhesive interactions. We observed two distinct populations of recirculating T cells, CCR7+/L-selectin+ central memory T cells (TCM) and CCR7+/L-selectin− T cells, which we term migratory memory T cells (TMM). Circulating skin-tropic TMM were intermediate in cytokine production between TCM and effector memory T cells. In patients with cutaneous T cell lymphoma, malignant TCM and TMM induced distinct inflammatory skin lesions and TMM were depleted more slowly from skin after alemtuzumab, suggesting TMM may recirculate more slowly. In summary, human skin is protected by four functionally distinct populations of T cells, two resident and two recirculating, with differing territories of migration and distinct functional activities. PMID:25787765

Enhanced leachate recirculation and stabilization in a pilot landfill bioreactor in Taiwan.

PubMed

Huang, Fu-Shih; Hung, Jui-Min; Lu, Chih-Jen

2012-08-01

This study focused on the treatment of municipal solid waste (MSW) by modification and recirculation of leachate from a simulated landfill bioreactor. Hydrogen peroxide was added to recirculated leachate to maintain a constant oxygen concentration as the leachate passed again through the simulated landfill bioreactor. The results showed that leachate recirculation increased the dissolved oxygen concentration in the test landfill bioreactor. Over a period of 405 days, the biochemical oxygen demand (BOD(5)) in the collected leachate reduced by 99.7%, whereas the chemical oxygen demand (COD) reduced by 96%. The BOD(5)/COD ratio at the initial stage of 0.9 improved to 0.09 under aerobic conditions (leachate recirculation with added hydrogen peroxide) compared with the anaerobic test cell 0.11 (leachate recirculation alone without hydrogen peroxide). The pH increased from 5.5 to 7.6, and the degradation rate of organic carbon was 93%. Leachate recirculation brings about the biodegradation of MSW comparatively faster than the conventional landfill operation. The addition of a constant concentration of hydrogen peroxide was found to further increase the biodegradation. This increased biodegradation rate ultimately enables an MSW landfill to reach a stable state sooner and free up the land for further reuse.

Effect of hydrothermal liquefaction aqueous phase recycling on bio-crude yields and composition.

PubMed

Biller, Patrick; Madsen, René B; Klemmer, Maika; Becker, Jacob; Iversen, Bo B; Glasius, Marianne

2016-11-01

Hydrothermal liquefaction (HTL) is a promising thermo-chemical processing technology for the production of biofuels but produces large amounts of process water. Therefore recirculation of process water from HTL of dried distillers grains with solubles (DDGS) is investigated. Two sets of recirculation on a continuous reactor system using K2CO3 as catalyst were carried out. Following this, the process water was recirculated in batch experiments for a total of 10 rounds. To assess the effect of alkali catalyst, non-catalytic HTL process water recycling was performed with 9 recycle rounds. Both sets of experiments showed a large increase in bio-crude yields from approximately 35 to 55wt%. The water phase and bio-crude samples from all experiments were analysed via quantitative gas chromatography-mass spectrometry (GC-MS) to investigate their composition and build-up of organic compounds. Overall the results show an increase in HTL conversion efficiency and a lower volume, more concentrated aqueous by-product following recycling. Copyright © 2016 Elsevier Ltd. All rights reserved.

Improving indoor air quality and thermal comfort in office building by using combination filters

NASA Astrophysics Data System (ADS)

Kabrein, H.; Yusof, M. Z. M.; Hariri, A.; Leman, A. M.; Afandi, A.

2017-09-01

Poor indoor air quality and thermal comfort condition in the workspace affected the occupants’ health and work productivity, especially when adapting the recirculation of air in heating ventilation and air-conditioning (HVAC) system. The recirculation of air was implemented in this study by mixing the circulated returned indoor air with the outdoor fresh air. The aims of this study are to assess the indoor thermal comfort and indoor air quality (IAQ) in the office buildings, equipped with combination filters. The air filtration technique consisting minimum efficiency reporting value (MERV) filter and activated carbon fiber (ACF) filter, located before the fan coil units. The findings of the study show that the technique of mixing recirculation air with the fresh air through the combination filters met the recommended thermal comfort condition in the workspace. Furthermore, the result of the post-occupancy evaluation (POE) and the environmental measurements comply with the ASHRAE 55 standard. In addition, the level of CO2 concentration continued to decrease during the period of the measurement.

40 CFR 1065.127 - Exhaust gas recirculation.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Exhaust gas recirculation. 1065.127 Section 1065.127 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.127 Exhaust gas recirculation. Use the...

40 CFR 1065.127 - Exhaust gas recirculation.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Exhaust gas recirculation. 1065.127 Section 1065.127 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.127 Exhaust gas recirculation. Use the...

40 CFR 1065.127 - Exhaust gas recirculation.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Exhaust gas recirculation. 1065.127 Section 1065.127 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.127 Exhaust gas recirculation. Use the...

40 CFR 1065.127 - Exhaust gas recirculation.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Exhaust gas recirculation. 1065.127 Section 1065.127 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.127 Exhaust gas recirculation. Use the...

40 CFR 1065.127 - Exhaust gas recirculation.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Exhaust gas recirculation. 1065.127 Section 1065.127 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Equipment Specifications § 1065.127 Exhaust gas recirculation. Use the...

Demonstration of Split-Flow Ventilation and Recirculation as Flow- Reduction Methods in an Air Force Paint Spray Booth. Volume 1

DTIC Science & Technology

1994-07-27

of the split-flow and recirculation modifications in typical Air Force painting operations; itwas a proof-of- concept study only. It is recognized...recirculating ventilation. 4 To Implement this flow-reduction concept , it must first be established that recirculation does not cause an accumulation of toxic...ventilation concept . The concentration gradient is determined by height and direction of paint application. If the concentration in the top portion is

Application of a fluidized bed reactor charged with aragonite for control of alkalinity, pH and carbon dioxide in marine recirculating aquaculture systems

USGS Publications Warehouse

Paul S Wills, PhD; Pfeiffer, Timothy; Baptiste, Richard; Watten, Barnaby J.

2016-01-01

Control of alkalinity, dissolved carbon dioxide (dCO2), and pH are critical in marine recirculating aquaculture systems (RAS) in order to maintain health and maximize growth. A small-scale prototype aragonite sand filled fluidized bed reactor was tested under varying conditions of alkalinity and dCO2 to develop and model the response of dCO2 across the reactor. A large-scale reactor was then incorporated into an operating marine recirculating aquaculture system to observe the reactor as the system moved toward equilibrium. The relationship between alkalinity dCO2, and pH across the reactor are described by multiple regression equations. The change in dCO2 across the small-scale reactor indicated a strong likelihood that an equilibrium alkalinity would be maintained by using a fluidized bed aragonite reactor. The large-scale reactor verified this observation and established equilibrium at an alkalinity of approximately 135 mg/L as CaCO3, dCO2 of 9 mg/L, and a pH of 7.0 within 4 days that was stable during a 14 day test period. The fluidized bed aragonite reactor has the potential to simplify alkalinity and pH control, and aid in dCO2 control in RAS design and operation. Aragonite sand, purchased in bulk, is less expensive than sodium bicarbonate and could reduce overall operating production costs.

Using mushroom farm and anaerobic digestion wastewaters as supplemental fertilizer sources for growing container nursery stock in a closed system.

PubMed

Chong, C; Purvis, P; Lumis, G; Holbein, B E; Voroney, R P; Zhou, H; Liu, H-W; Alam, M Z

2008-04-01

Wastewaters from farm and composting operations are often rich in select nutrients that potentially can be reutilized in crop production. Liners of silverleaf dogwood (Cornus alba L. 'Argenteo-marginata'), common ninebark [Physocarpus opulifolius (L.) Maxim.], and Anthony Waterer spirea (Spiraeaxbumalda Burvénich 'Anthony Waterer') were grown in 6L containers filled with a bark-based commercial mix. Plants were fertigated daily via a computer-controlled multi-fertilizer injector with three recirculated fertilizer treatments: (1) a stock (control) solution with complete macro- and micro-nutrients, electrical conductivity (EC) 2.2 dS m(-1); (2) wastewater from a mushroom farm; and (3) process wastewater from anaerobic digestion of municipal solid waste. The wastewaters used in both treatments 2 and 3 were diluted with tap water, and the computer was programmed to amend, dispense and recirculate nutrients based on the same target EC as in treatment 1. For comparison, there was a traditional controlled-release fertilizer treatment [Nutryon 17-5-12 (17N-2P-10K) plus micro-nutrients topdressed at a rate of 39 g/plant, nutrients not recirculated]. All three species responded similarly to the three recirculated fertilizer treatments. Growth with the recirculated treatments was similar and significantly higher than that obtained with controlled-release fertilizer. Throughout the study, the EC measured in wastewater-derived nutrient solutions, and also in the container substrate, were similar or close to those of the control treatment, although there were small to large differences among individual major nutrients. There was no sign of nutrient deficiency or toxicity symptoms to the plants. Small to moderate excesses in concentrations of SO(4), Na, and/or Cl were physiologically tolerable to the species.

Human skin is protected by four functionally and phenotypically discrete populations of resident and recirculating memory T cells.

PubMed

Watanabe, Rei; Gehad, Ahmed; Yang, Chao; Scott, Laura L; Teague, Jessica E; Schlapbach, Christoph; Elco, Christopher P; Huang, Victor; Matos, Tiago R; Kupper, Thomas S; Clark, Rachael A

2015-03-18

The skin of an adult human contains about 20 billion memory T cells. Epithelial barrier tissues are infiltrated by a combination of resident and recirculating T cells in mice, but the relative proportions and functional activities of resident versus recirculating T cells have not been evaluated in human skin. We discriminated resident from recirculating T cells in human-engrafted mice and lymphoma patients using alemtuzumab, a medication that depletes recirculating T cells from skin, and then analyzed these T cell populations in healthy human skin. All nonrecirculating resident memory T cells (TRM) expressed CD69, but most were CD4(+), CD103(-), and located in the dermis, in contrast to studies in mice. Both CD4(+) and CD8(+) CD103(+) TRM were enriched in the epidermis, had potent effector functions, and had a limited proliferative capacity compared to CD103(-) TRM. TRM of both types had more potent effector functions than recirculating T cells. We observed two distinct populations of recirculating T cells, CCR7(+)/L-selectin(+) central memory T cells (TCM) and CCR7(+)/L-selectin(-) T cells, which we term migratory memory T cells (TMM). Circulating skin-tropic TMM were intermediate in cytokine production between TCM and effector memory T cells. In patients with cutaneous T cell lymphoma, malignant TCM and TMM induced distinct inflammatory skin lesions, and TMM were depleted more slowly from skin after alemtuzumab, suggesting that TMM may recirculate more slowly. In summary, human skin is protected by four functionally distinct populations of T cells, two resident and two recirculating, with differing territories of migration and distinct functional activities. Copyright © 2015, American Association for the Advancement of Science.

Effects of leachate recirculation on biogas production from landfill co-disposal of municipal solid waste, sewage sludge and marine sediment.

PubMed

Chan, G Y S; Chu, L M; Wong, M H

2002-01-01

Leachate recirculation is an emerging technology associated with the management of landfill. The impact of leachate recirculation on the co-disposal of three major wastes (municipal solid waste, sewage sludge and sediment dredgings) was investigated using a laboratory column study. Chemical parameters (pH, COD, ammoniacal-N, total-P) and gas production (total gas volume, production rates and concentrations of CH4 and CO2) were monitored for 11 weeks. Leachate recirculation reduced waste-stabilization time and was effective in enhancing gas production and improving leachate quality, especially in terms of COD. The results also indicated that leachate recirculation could maximize the efficiency and waste volume reduction rate of landfill sites.

Define of internal recirculation coefficient for biological wastewater treatment in anoxic and aerobic bioreactors

NASA Astrophysics Data System (ADS)

Rossinskyi, Volodymyr

2018-02-01

The biological wastewater treatment technologies in anoxic and aerobic bioreactors with recycle of sludge mixture are used for the effective removal of organic compounds from wastewater. The change rate of sludge mixture recirculation between bioreactors leads to a change and redistribution of concentrations of organic compounds in sludge mixture in bioreactors and change hydrodynamic regimes in bioreactors. Determination of the coefficient of internal recirculation of sludge mixture between bioreactors is important for the choice of technological parameters of biological treatment (wastewater treatment duration in anoxic and aerobic bioreactors, flow capacity of recirculation pumps). Determination of the coefficient of internal recirculation of sludge mixture requires integrated consideration of hydrodynamic parameter (flow rate), kinetic parameter (rate of oxidation of organic compounds) and physical-chemical parameter of wastewater (concentration of organic compounds). The conducted numerical experiment from the proposed mathematical equations allowed to obtain analytical dependences of the coefficient of internal recirculation sludge mixture between bioreactors on the concentration of organic compounds in wastewater, the duration of wastewater treatment in bioreactors.

Survival of Listeria monocytogenes in a simulated recirculating brine chiller system.

PubMed

Gailey, J K; Dickson, J S; Dorsa, W

2003-10-01

Contamination by Listeria monocytogenes of processed meats after cooking presents a significant food safety risk. The purpose of this study was to determine the survival of L. monocytogenes in a simulated recirculating brine chiller system using pH values of 5, 6, and 7 with free chlorine concentrations of 0, 3, 5, and 10 ppm in 20% salt brine at -12 degrees C. At pH values of 5, 6, and 7 with chlorine concentrations of 2 and 3 ppm, using 10(8) CFU in a test tube system, an immediate drop of 0.28 log CFU/ml with no significance between treatments (P > 0.05), followed by a steady survival phase with a slope close to 0, was observed. In brine at a pH of 5 with 5 and 10 ppm of chlorine, an initial drop of 0.8 log CFU/ml was observed, which was followed by a steady survival phase with a destruction slope close to zero. At an inoculation concentration of 10(2) CFU in a test tube system (pH values of 5 and 7 with 0 and 10 ppm of chlorine), the average initial drop for all treatments was 0.1 log CFU/ml, which was followed by a steady survival phase. In a recirculating system, very few cells were destroyed during the brine chilling process, but only low numbers of L. monocytogenes were recovered from the brine and uninoculated hot dogs. Although little destruction of L. monocytogenes was noted, the dilution effect observed during the study indicates that environmental contamination of a brine chiller system poses little danger of postcooking contamination for processed meats if the system is regularly cleaned and sanitized.

Technology Solutions for New and Existing Homes Case Study: Addressing Multifamily Piping Losses with Solar Hot Water

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

D. Springer, M. Seitzler, and C. Backman

2016-12-01

Sun Light & Power, a San Francisco Bay Area solar design-build contractor, teamed with the U.S. Department of Energy’s Building America partner the Alliance for Residential Building Innovation (ARBI) to study this heat-loss issue. The team added three-way valves to the solar water heating systems for two 40-unit multifamily buildings. In these systems, when the stored solar hot water is warmer than the recirculated hot water returning from the buildings, the valves divert the returning water to the solar storage tank instead of the water heater. This strategy allows solar-generated heat to be applied to recirculation heat loss in additionmore » to heating water that is consumed by fixtures and appliances.« less

Coal slurry fuel supply and purge system

DOEpatents

McDowell, Robert E.; Basic, Steven L.; Smith, Russel M.

1994-01-01

A coal slurry fuel supply and purge system for a locomotive engines is disclosed which includes a slurry recirculation path, a stand-by path for circulating slurry during idle or states of the engine when slurry fuel in not required by the engine, and an engine header fluid path connected to the stand-by path, for supplying and purging slurry fuel to and from fuel injectors. A controller controls the actuation of valves to facilitate supply and purge of slurry to and from the fuel injectors. A method for supplying and purging coal slurry in a compression ignition engine is disclosed which includes controlling fluid flow devices and valves in a plurality of fluid paths to facilitate continuous slurry recirculation and supply and purge of or slurry based on the operating state of the engine.

Advanced water iodinating system. [for potable water aboard manned spacecraft

NASA Technical Reports Server (NTRS)

Davenport, R. J.; Schubert, F. H.; Wynveen, R. A.

1975-01-01

Potable water stores aboard manned spacecraft must remain sterile. Suitable sterilization techniques are needed to prevent microbial growth. The development of an advanced water iodinating system for possible application to the shuttle orbiter and other advanced spacecraft, is considered. The AWIS provides a means of automatically dispensing iodine and controlling iodination levels in potable water stores. In a recirculation mode test, simulating application of the AWIS to a water management system of a long term six man capacity space mission, noniodinated feed water flowing at 32.2 cu cm min was iodinated to 5 + or - ppm concentrations after it was mixed with previously iodinated water recirculating through a potable water storage tank. Also, the AWIS was used to successfully demonstrate its capability to maintain potable water at a desired I2 concentration level while circulating through the water storage tank, but without the addition of noniodinated water.

Introduction of filtration systems in container nurseries for nonchemical elimination of Phytophthora spp. from irrigation water

Treesearch

Thorsten Ufer; Heinrich Beltz; Thomas Brand; Katrin Kaminski; Ralf Lüttmann; Martin Posner; Stefan Wagner; Sabine Werres; Hans-Peter Wessels

2006-01-01

In a 3-year project the elimination of Phytophthora spp. from the recirculation water with different kinds of filtration systems will be tested under commercial conditions in container nurseries. First results indicate that the filtration systems eliminate Phytophthora spp. from the water.

Water supply rates for recirculating evaporative cooling systems in poultry housing

USDA-ARS?s Scientific Manuscript database

Evaporative cooling (EC) is an important tool to reduce heat stress in animal housing systems. Expansion of ventilation capacity in tunnel ventilated poultry facilities has resulted in increased water demand for EC systems. As water resources become more limited and costly, proper planning and des...

Methane generation from waste materials

DOEpatents

Samani, Zohrab A.; Hanson, Adrian T.; Macias-Corral, Maritza

2010-03-23

An organic solid waste digester for producing methane from solid waste, the digester comprising a reactor vessel for holding solid waste, a sprinkler system for distributing water, bacteria, and nutrients over and through the solid waste, and a drainage system for capturing leachate that is then recirculated through the sprinkler system.

9 CFR 93.412 - Ruminant quarantine facilities.

Code of Federal Regulations, 2014 CFR

2014-01-01

... (HVAC) system capable of controlling and maintaining the ambient temperature, air quality, moisture, and... to lot-holding areas must not be recirculated or reused for other ventilation needs. HVAC systems for... at a time, each lot-holding area must have its own separate HVAC system that is designed to prevent...

33 CFR 159.127 - Safety coliform count: Recirculating devices.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Safety coliform count....127 Safety coliform count: Recirculating 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...

Recirculating rotary gas compressor

DOEpatents

Weinbrecht, John F.

1992-01-01

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.

Recirculating rotary gas compressor

DOEpatents

Weinbrecht, J.F.

1992-02-25

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.

Cluster formation and drag reduction-proposed mechanism of particle recirculation within the partition column of the bottom spray fluid-bed coater.

PubMed

Wang, Li Kun; Heng, Paul Wan Sia; Liew, Celine Valeria

2015-04-01

Bottom spray fluid-bed coating is a common technique for coating multiparticulates. Under the quality-by-design framework, particle recirculation within the partition column is one of the main variability sources affecting particle coating and coat uniformity. However, the occurrence and mechanism of particle recirculation within the partition column of the coater are not well understood. The purpose of this study was to visualize and define particle recirculation within the partition column. Based on different combinations of partition gap setting, air accelerator insert diameter, and particle size fraction, particle movements within the partition column were captured using a high-speed video camera. The particle recirculation probability and voidage information were mapped using a visiometric process analyzer. High-speed images showed that particles contributing to the recirculation phenomenon were behaving as clustered colonies. Fluid dynamics analysis indicated that particle recirculation within the partition column may be attributed to the combined effect of cluster formation and drag reduction. Both visiometric process analysis and particle coating experiments showed that smaller particles had greater propensity toward cluster formation than larger particles. The influence of cluster formation on coating performance and possible solutions to cluster formation were further discussed. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

40 CFR 94.211 - Emission-related maintenance instructions for purchasers.

Code of Federal Regulations, 2011 CFR

2011-07-01

... filter change, fuel filter change, air filter change, cooling system maintenance, adjustment of idle... (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM MARINE COMPRESSION-IGNITION ENGINES... at 1,500-hour intervals thereafter. (i) Exhaust gas recirculation system-related filters and coolers...

7 CFR 2902.41 - Metalworking fluids.

Code of Federal Regulations, 2011 CFR

2011-01-01

..., lubrication, corrosion prevention, and reduced wear on the contact parts of machinery used for metalworking... for use in a re-circulating fluid system to provide cooling, lubrication, and corrosion prevention... fluid system to provide cooling, lubrication, and corrosion prevention when applied to metal feedstock...

7 CFR 2902.41 - Metalworking fluids.

Code of Federal Regulations, 2010 CFR

2010-01-01

..., lubrication, corrosion prevention, and reduced wear on the contact parts of machinery used for metalworking... for use in a re-circulating fluid system to provide cooling, lubrication, and corrosion prevention... fluid system to provide cooling, lubrication, and corrosion prevention when applied to metal feedstock...

Numerical investigation of the effect of the configuration of ExoMars landing platform propulsion system on the interaction of supersonic jets with the surface of Mars

NASA Astrophysics Data System (ADS)

Kagenov, Anuar; Glazunov, Anatoliy; Kostyushin, Kirill; Eremin, Ivan; Shuvarikov, Vladimir

2017-10-01

This paper presents the results of numerical investigations of the interaction with the Mars surface of four supersonic jets of ExoMars landing platform propulsion system. The cases of impingement of supersonic jets on a curved surface are considered depending on the values of propulsion system thrust. According to the results of numerical studies are obtained the values of normal stresses on the surface of Mars at altitudes of 1.0, 0.5 and 0.3 meter to the surface of the landing. To define the occurring shear stresses Mohr-Coulomb theory was used. The maximum values of shear stresses were defined for the following types of soil of Mars: drift material, crusty to cloddy material, blocky material, sand and Mojave Mars simulant. The conducted evaluations showed, regardless of the propulsion system configuration, that when the final stage of the controlled landing of the ExoMars landing platform, the erosion of the Mars regolith would be insignificant. The estimates are consistent with the available data from previous Mars missions.

Use of off-axis injection as an alternative to geometrically merging beams in an energy-recovering linac

DOEpatents

Douglas, David R [York County, VA

2012-01-10

A method of using off-axis particle beam injection in energy-recovering linear accelerators that increases operational efficiency while eliminating the need to merge the high energy re-circulating beam with an injected low energy beam. In this arrangement, the high energy re-circulating beam and the low energy beam are manipulated such that they are within a predetermined distance from one another and then the two immerged beams are injected into the linac and propagated through the system. The configuration permits injection without geometric beam merging as well as decelerated beam extraction without the use of typical beamline elements.

Hydraulic design of a re-circulating water cooling system of a combined cycle power plant in Thailand

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

Sarkar, C.K.; Pandit, D.R.; Kwon, S.G.

The paper describes the hydraulic design and hydraulic transient analysis of the re-circulating water cooling system of the combined cyclo Sipco power cogeneration plant in Thailand. The power plant of 450 MW total capacity is proposed to be built in two stages. Stage one will produce 300 MW of power and will consist of two gas turbine generators (GTG) and one steam turbine generator (STG). Stage two will produce 150 MW of power and will consist of one GTG and one STG. The cooling system will consist of one GTG and one STG. The cooling system will consist of coolingmore » towers, a combined collecting basin and pump intake sump, pumps and motors, and separate conveyance systems and condensers for the generator units in the two stages. In a re-circulating water cooling system, cold water is pumped from the pump intake sump to the condensers through the conveyance system and hot water from the condensers is carried through the returning pipeline system to the cooling towers, whence the water after cooling is drained into the sump at the base of the towers. Total cooling water requirement for the system in stage one is estimated to be 112,000 gallons per minute (GPM), and that in stage two, 56,000 GPM. The sump is designed using the computer program HEC-2, developed by the US Army Corps of Engineers (COE) and the pump intake basin, following the recommendations of the Hydraulic Institute. The pumps were sized by computing the head loss in the system, and, the steady state and transient performances (during pump start-up and shut-down procedures and due to possible power or mechanical failure of one or all pumps) of the system were analyzed by mathematically modeling the system using the computer program WHAMO (Water Hammer nd Mass Oscillations), also developed by the COE.« less

Evaluation of a Shaker Dust Collector for Use in a Recirculating Ventilation System

PubMed Central

Sawvel, Russell A.; Park, Jae Hong; Anthony, T. Renée

2016-01-01

General ventilation with recirculated air may be cost-effective to control the concentration of low-toxicity, contaminants in workplaces with diffuse, dusty operations, such as in agriculture. Such systems are, however, rarely adopted with little evidence showing improved air quality and ability to operate under harsh conditions. The goal of this work was to examine the initial and long-term performance of a fabric-filter shaker dust collector (SDC) in laboratory tests and as deployed within a recirculating ventilation system in an agricultural building. In laboratory tests, collection efficiency and pressure drop were tracked over several filter loading cycles, and the recovery of filter capacity (pressure drop) from filter shaking was examined. Collection efficiencies of particles larger than 5 μm was high (>95%) even when the filter was pristine, showing effective collection of large particles that dominate inhalable concentrations typical of agricultural dusts. For respirable-sized particles, collection efficiencies were low when the filter was pristine (e.g., 27% for 1 μm) but much higher when a dust cake developed on the filter (>99% for all size particles), even after shaking (e.g., 90% for 1 μm). The first shake of a filter was observed to recovery a substantial fraction of filter capacity, with subsequent shakes providing little benefit. In field tests, the SDC performed effectively over a period of three months in winter when incorporated in a recirculating ventilation system of a swine farrowing room. Trends in collection efficiency and pressure drop with loading were similar to those observed in the laboratory with overall collection efficiencies high (>80%) when pressure drop exceeded 230 Pa, or 23% of the maximum loading recommended by the manufacturer. This work shows that the SDC can function effectively over the harsh winter in swine rearing operations. Together with findings of improved air quality in the farrowing room reported in a companion manuscript, this article provides evidence that an SDC represents a cost-effective solution to improve air quality in agricultural settings. PMID:25955507

The Advantages of Non-Flow-Through Fuel Cell Power Systems for Aerospace Applications

NASA Technical Reports Server (NTRS)

Hoberecht, Mark; Burke, Kenneth; Jakupca, Ian

2011-01-01

NASA has been developing proton-exchange-membrane (PEM) fuel cell power systems for the past decade, as an upgraded technology to the alkaline fuel cells which presently provide power for the Shuttle Orbiter. All fuel cell power systems consist of one or more fuel cell stacks in combination with appropriate balance-of-plant hardware. Traditional PEM fuel cells are characterized as flow-through, in which recirculating reactant streams remove product water from the fuel cell stack. NASA recently embarked on the development of non-flow-through fuel cell systems, in which reactants are dead-ended into the fuel cell stack and product water is removed by internal wicks. This simplifies the fuel cell power system by eliminating the need for pumps to provide reactant circulation, and mechanical water separators to remove the product water from the recirculating reactant streams. By eliminating these mechanical components, the resulting fuel cell power system has lower mass, volume, and parasitic power requirements, along with higher reliability and longer life. These improved non-flow-through fuel cell power systems therefore offer significant advantages for many aerospace applications.

Survival and Transfer of Murine Norovirus within a Hydroponic System during Kale and Mustard Microgreen Harvesting.

PubMed

Wang, Qing; Kniel, Kalmia E

2016-01-15

Hydroponically grown microgreens are gaining in popularity, but there is a lack of information pertaining to their microbiological safety. The potential risks associated with virus contamination of crops within a hydroponic system have not been studied to date. Here a human norovirus (huNoV) surrogate (murine norovirus [MNV]) was evaluated for its ability to become internalized from roots to edible tissues of microgreens. Subsequently, virus survival in recirculated water without adequate disinfection was assessed. Kale and mustard seeds were grown on hydroponic pads (for 7 days with harvest at days 8 to 12), edible tissues (10 g) were cut 1 cm above the pads, and corresponding pieces (4 cm by 4 cm) of pads containing only roots were collected separately. Samples were collected from a newly contaminated system (recirculated water inoculated with ∼3 log PFU/ml MNV on day 8) and from a previously contaminated system. (A contaminated system without adequate disinfection or further inoculation was used for production of another set of microgreens.) Viral titers and RNA copies were quantified by plaque assay and real-time reverse transcription (RT)-PCR. The behaviors of MNV in kale and mustard microgreens were similar (P > 0.05). MNV was detected in edible tissues and roots after 2 h postinoculation, and the levels were generally stable during the first 12 h. Relatively low levels (∼2.5 to ∼1.5 log PFU/sample of both edible tissues and roots) of infectious viruses were found with a decreasing trend over time from harvest days 8 to 12. However, the levels of viral RNA present were higher and consistently stable (∼4.0 to ∼5.5 log copies/sample). Recirculated water maintained relatively high levels of infectious MNV over the period of harvest, from 3.54 to 2.73 log PFU/ml. Importantly, cross-contamination occurred easily; MNV remained infectious in previously contaminated hydroponic systems for up to 12 days (2.26 to 1.00 PFU/ml), and MNV was detected in both edible tissues and roots. Here we see that viruses can be recirculated in water, even after an initial contamination event is removed, taken up through the roots of microgreens, and transferred to edible tissues. The ease of product contamination shown here reinforces the need for proper sanitation. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Survival and Transfer of Murine Norovirus within a Hydroponic System during Kale and Mustard Microgreen Harvesting

PubMed Central

Wang, Qing

2015-01-01

Hydroponically grown microgreens are gaining in popularity, but there is a lack of information pertaining to their microbiological safety. The potential risks associated with virus contamination of crops within a hydroponic system have not been studied to date. Here a human norovirus (huNoV) surrogate (murine norovirus [MNV]) was evaluated for its ability to become internalized from roots to edible tissues of microgreens. Subsequently, virus survival in recirculated water without adequate disinfection was assessed. Kale and mustard seeds were grown on hydroponic pads (for 7 days with harvest at days 8 to 12), edible tissues (10 g) were cut 1 cm above the pads, and corresponding pieces (4 cm by 4 cm) of pads containing only roots were collected separately. Samples were collected from a newly contaminated system (recirculated water inoculated with ∼3 log PFU/ml MNV on day 8) and from a previously contaminated system. (A contaminated system without adequate disinfection or further inoculation was used for production of another set of microgreens.) Viral titers and RNA copies were quantified by plaque assay and real-time reverse transcription (RT)-PCR. The behaviors of MNV in kale and mustard microgreens were similar (P > 0.05). MNV was detected in edible tissues and roots after 2 h postinoculation, and the levels were generally stable during the first 12 h. Relatively low levels (∼2.5 to ∼1.5 log PFU/sample of both edible tissues and roots) of infectious viruses were found with a decreasing trend over time from harvest days 8 to 12. However, the levels of viral RNA present were higher and consistently stable (∼4.0 to ∼5.5 log copies/sample). Recirculated water maintained relatively high levels of infectious MNV over the period of harvest, from 3.54 to 2.73 log PFU/ml. Importantly, cross-contamination occurred easily; MNV remained infectious in previously contaminated hydroponic systems for up to 12 days (2.26 to 1.00 PFU/ml), and MNV was detected in both edible tissues and roots. Here we see that viruses can be recirculated in water, even after an initial contamination event is removed, taken up through the roots of microgreens, and transferred to edible tissues. The ease of product contamination shown here reinforces the need for proper sanitation. PMID:26567309

77 FR 19740 - Water Sources for Long-Term Recirculation Cooling Following a Loss-of-Coolant Accident

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-02

... NUCLEAR REGULATORY COMMISSION [NRC-2010-0249] Water Sources for Long-Term Recirculation Cooling... Regulatory Guide (RG) 1.82, ``Water Sources for Long-Term Recirculation Cooling Following a Loss-of-Coolant... regarding the sumps and suppression pools that provide water sources for emergency core cooling, containment...

40 CFR 89.109 - Maintenance instructions and minimum allowable maintenance intervals.

Code of Federal Regulations, 2011 CFR

2011-07-01

... change, oil filter change, fuel filter change, air filter change, cooling system maintenance, adjustment... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION...) Exhaust gas recirculation system-related filters and coolers. (ii) Positive crankcase ventilation valve...

40 CFR 89.109 - Maintenance instructions and minimum allowable maintenance intervals.

Code of Federal Regulations, 2010 CFR

2010-07-01

... change, oil filter change, fuel filter change, air filter change, cooling system maintenance, adjustment... AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION...) Exhaust gas recirculation system-related filters and coolers. (ii) Positive crankcase ventilation valve...

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

USGS Publications Warehouse

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

2006-01-01

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.

MarsSI: Martian surface data processing information system

NASA Astrophysics Data System (ADS)

Quantin-Nataf, C.; Lozac'h, L.; Thollot, P.; Loizeau, D.; Bultel, B.; Fernando, J.; Allemand, P.; Dubuffet, F.; Poulet, F.; Ody, A.; Clenet, H.; Leyrat, C.; Harrisson, S.

2018-01-01

MarsSI (Acronym for Mars System of Information, https://emars.univ-lyon1.fr/MarsSI/, is a web Geographic Information System application which helps managing and processing martian orbital data. The MarsSI facility is part of the web portal called PSUP (Planetary SUrface Portal) developed by the Observatories of Paris Sud (OSUPS) and Lyon (OSUL) to provide users with efficient and easy access to data products dedicated to the martian surface. The portal proposes 1) the management and processing of data thanks to MarsSI and 2) the visualization and merging of high level (imagery, spectral, and topographic) products and catalogs via a web-based user interface (MarsVisu). The portal PSUP as well as the facility MarsVisu is detailed in a companion paper (Poulet et al., 2018). The purpose of this paper is to describe the facility MarsSI. From this application, users are able to easily and rapidly select observations, process raw data via automatic pipelines, and get back final products which can be visualized under Geographic Information Systems. Moreover, MarsSI also contains an automatic stereo-restitution pipeline in order to produce Digital Terrain Models (DTM) on demand from HiRISE (High Resolution Imaging Science Experiment) or CTX (Context Camera) pair-images. This application is funded by the European Union's Seventh Framework Programme (FP7/2007-2013) (ERC project eMars, No. 280168) and has been developed in the scope of Mars, but the design is applicable to any other planetary body of the solar system.

External Device to Incrementally Skid the Habitat (E-DISH)

NASA Technical Reports Server (NTRS)

Brazell, J. W.; Introne, Steve; Bedell, Lisa; Credle, Ben; Holp, Graham; Ly, Siao; Tait, Terry

1994-01-01

A Mars habitat transport system was designed as part of the NASA Mars exploration program. The transport system, the External Device to Incrementally Skid the Habitat (E - DISH), will be used to transport Mars habitats from their landing sites to the colony base and will be detached after unloading. The system requirements for Mars were calculated and scaled for model purposes. Specific model materials are commonly found and recommendations for materials for the Mars design are included.

Mars NanoOrbiter: A CubeSat for Mars System Science

NASA Astrophysics Data System (ADS)

Ehlmann, Bethany; Klesh, Andrew; Alsedairy, Talal

2017-10-01

The Mars NanoOrbiter mission consists of two identical 12U spacecraft, launched simultaneously as secondary payloads on a larger planetary mission launch, and deployed to Earth-escape, as early as with Mars 2020. The nominal mission will last for 1 year, during which time the craft will independently navigate to Mars, enter into elliptical orbit, and achieve close flybys of Phobos and Deimos, obtaining unprecedented coverage of each moon. The craft will additionally provide high temporal resolution data of Mars clouds and atmospheric phenomena at multiple times of day. Two spacecraft provide redundancy to reduce the risk in meeting the science objectives at the Mars moons and enhanced coverage of the dynamic Mars atmosphere. This technology is enabled by recent advances in CubeSat propulsion technology, attitude control systems, guidance, navigation and control. NanoOrbiter builds directly on the systems heritage of the MarCO mission, scheduled to launch with the 2018 Discovery mission Insight.

Proceedings of the 38th Lunar and Planetary Science Conference

NASA Technical Reports Server (NTRS)

2007-01-01

The sessions in the conference include: Titan, Mars Volcanism, Mars Polar Layered Deposits, Early Solar System Isotopes, SPECIAL SESSION: Mars Reconnaissance Orbiter: New Ways of Studying the Red Planet, Achondrites: Exploring Oxygen Isotopes and Parent-Body Processes, Solar System Formation and Evolution, SPECIAL SESSION: SMART-1, . Impact Cratering: Observations and Experiments, SPECIAL SESSION: Volcanism and Tectonism on Saturnian Satellites, Solar Nebula Composition, Mars Fluvial Geomorphology, Asteroid Observations: Spectra, Mostly, Mars Sediments and Geochemistry: View from the Surface, Mars Tectonics and Crustal Dichotomy, Stardust: Wild-2 Revealed, Impact Cratering from Observations and Interpretations, Mars Sediments and Geochemistry: The Map View, Chondrules and Their Formation, Enceladus, Asteroids and Deep Impact: Structure, Dynamics, and Experiments, Mars Surface Process and Evolution, Martian Meteorites: Nakhlites, Experiments, and the Great Shergottite Age Debate, Stardust: Mainly Mineralogy, Astrobiology, Wind-Surface Interactions on Mars and Earth, Icy Satellite Surfaces, Venus, Lunar Remote Sensing, Space Weathering, and Impact Effects, Interplanetary Dust/Genesis, Mars Cratering: Counts and Catastrophes?, Chondrites: Secondary Processes, Mars Sediments and Geochemistry: Atmosphere, Soils, Brines, and Minerals, Lunar Interior and Differentiation, Mars Magnetics and Atmosphere: Core to Ionosphere, Metal-rich Chondrites, Organics in Chondrites, Lunar Impacts and Meteorites, Presolar/Solar Grains, Topics for Print Only papers are: Outer Planets/Satellites, Early Solar System, Interplanetary Dust, Comets and Kuiper Belt Objects, Asteroids and Meteoroids, Chondrites, Achondrites, Meteorite Related, Mars Reconnaissance Orbiter, Mars, Astrobiology, Planetary Differentiation, Impacts, Mercury, Lunar Samples and Modeling, Venus, Missions and Instruments, Global Warming, Education and Public Outreach, Poster sessions are: Asteroids/Kuiper Belt Objects, Galilean Satellites: Geology and Mapping, Titan, Volcanism and Tectonism on Saturnian Satellites, Early Solar System, Achondrite Hodgepodge, Ordinary Chondrites, Carbonaceous Chondrites, Impact Cratering from Observations and Interpretations, Impact Cratering from Experiments and Modeling, SMART-1, Planetary Differentiation, Mars Geology, Mars Volcanism, Mars Tectonics, Mars: Polar, Glacial, and Near-Surface Ice, Mars Valley Networks, Mars Gullies, Mars Outflow Channels, Mars Sediments and Geochemistry: Spirit and Opportunity, Mars Reconnaissance Orbiter: New Ways of Studying the Red Planet, Mars Reconnaissance Orbiter: Geology, Layers, and Landforms, Oh, My!, Mars Reconnaissance Orbiter: Viewing Mars Through Multicolored Glasses; Mars Science Laboratory, Phoenix, and ExoMars: Science, Instruments, and Landing Sites; Planetary Analogs: Chemical and Mineral, Planetary Analogs: Physical, Planetary Analogs: Operations, Future Mission Concepts, Planetary Data, Imaging, and Cartography, Outer Solar System, Presolar/Solar Grains, Stardust Mission; Interplanetary Dust, Genesis, Asteroids and Comets: Models, Dynamics, and Experiments, Venus, Mercury, Laboratory Instruments, Methods, and Techniques to Support Planetary Exploration; Instruments, Techniques, and Enabling Techologies for Planetary Exploration; Lunar Missions and Instruments, Living and Working on the Moon, Meteoroid Impacts on the Moon, Lunar Remote Sensing, Lunar Samples and Experiments, Lunar Atmosphere, Moon: Soils, Poles, and Volatiles, Lunar Topography and Geophysics, Lunar Meteorites, Chondrites: Secondary Processes, Chondrites, Martian Meteorites, Mars Cratering, Mars Surface Processes and Evolution, Mars Sediments and Geochemistry: Regolith, Spectroscopy, and Imaging, Mars Sediments and Geochemistry: Analogs and Mineralogy, Mars: Magnetics and Atmosphere, Mars Aeolian Geomorphology, Mars Data Processing and Analyses, Astrobiology, Engaging Student Educators and the Public in Planetary Science,

Mars Ascent Vehicle Gross Lift-off Mass Sensitivities for Robotic Mars Sample Return

NASA Technical Reports Server (NTRS)

Dux, Ian J.; Huwaldt, Joseph A.; McKamey, R. Steve; Dankanich, John W.

2011-01-01

The Mars ascent vehicle is a critical element of the robotic Mars Sample Return (MSR) mission. The Mars ascent vehicle must be developed to survive a variety of conditions including the trans-Mars journey, descent through the Martian atmosphere and the harsh Martian surface environments while maintaining the ability to deliver its payload to a low Mars orbit. The primary technology challenge of developing the Mars ascent vehicle system is designing for all conditions while ensuring the mass limitations of the entry descent and landing system are not exceeded. The NASA In-Space Propulsion technology project has initiated the development of Mars ascent vehicle technologies with propulsion system performance and launch environments yet to be defined. To support the project s evaluation and development of various technology options the sensitivity of the Mars ascent vehicle gross lift-off mass to engine performance, inert mass, target orbits, and launch conditions has been completed with the results presented herein.

Efficient volatile metal removal from low rank coal in gasification, combustion, and processing systems and methods

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

Bland, Alan E.; Sellakumar, Kumar Muthusami; Newcomer, Jesse D.

Efficient coal pre-processing systems (69) integrated with gasification, oxy-combustion, and power plant systems include a drying chamber (28), a volatile metal removal chamber (30), recirculated gases, including recycled carbon dioxide (21), nitrogen (6), and gaseous exhaust (60) for increasing the efficiencies and lowering emissions in various coal processing systems.

Integral reactor system and method for fuel cells

DOEpatents

Fernandes, Neil Edward; Brown, Michael S.; Cheekatamaria, Praveen; Deng, Thomas; Dimitrakopoulos, James; Litka, Anthony F.

2017-03-07

A reactor system is integrated internally within an anode-side cavity of a fuel cell. The reactor system is configured to convert higher hydrocarbons to smaller species while mitigating the lower production of solid carbon. The reactor system may incorporate one or more of a pre-reforming section, an anode exhaust gas recirculation device, and a reforming section.

Integral reactor system and method for fuel cells

DOEpatents

Fernandes, Neil Edward; Brown, Michael S; Cheekatamarla, Praveen; Deng, Thomas; Dimitrakopoulos, James; Litka, Anthony F

2013-11-19

A reactor system is integrated internally within an anode-side cavity of a fuel cell. The reactor system is configured to convert hydrocarbons to smaller species while mitigating the lower production of solid carbon. The reactor system may incorporate one or more of a pre-reforming section, an anode exhaust gas recirculation device, and a reforming section.

75 FR 10866 - Notice of a Project Waiver of Section 1605 (Buy American Requirement) of the American Recovery...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-03-09

... rotating drum filter upgrades and a water quality monitoring system expansion, are not available from... quality. Expansion of the recirculation system requires adding a second drum filter for aquaculture water treatment. The existing system uses a drum filter manufactured by PRAqua Supplies Ltd.--Nanaimo, British...

Recirculating Etalon Spectrometer

NASA Technical Reports Server (NTRS)

Stephen, Mark A. (Inventor); Fahey, Molly E. (Inventor); Krainak, Michael A. (Inventor)

2017-01-01

Systems, methods, and devices may provide an optical scheme that achieves simultaneous wavelength channels and maintains the resolution and luminosity of an etalon. Various embodiments may provide a method to optically recirculate the light reflected from the etalon back through the same etalon at new angles. Various embodiments create an etalon spectrometer based on angular dispersion without moving parts and without losing the light that is not initially transmitted. Various embodiments may provide a spectrally-resolved receiver and/or transmitter. Various embodiments may provide a system including a retro-reflector, a detector or transmitter array, and an etalon disposed between the retro-reflector and the detector or transmitter array, wherein the retro-reflector is configured to redirect light reflected by the etalon back to the etalon at a different angle of incidence than an original angle of incidence on the etalon of the light reflected by the etalon.

Dynamics of microorganism populations in recirculating nutrient solutions

NASA Technical Reports Server (NTRS)

Strayer, R. F.

1994-01-01

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.

Investigation of the Makeup, Source, and Removal Strategies for Total Organic Carbon in the Oxygen Generation System Recirculation Loop

NASA Technical Reports Server (NTRS)

Bowman, Elizabeth M.; Carpenter, Joyce; Roy, Robert J.; Van Keuren, Steve; Wilson, Mark E.

2015-01-01

Since 2007, the Oxygen Generation System (OGS) on board the International Space Station (ISS) has been producing oxygen for crew respiration via water electrolysis. As water is consumed in the OGS recirculating water loop, make-up water is furnished by the ISS potable water bus. A rise in Total Organic Carbon (TOC) was observed beginning in February, 2011, which continues through the present date. Increasing TOC is of concern because the organic constituents responsible for the TOC were unknown and had not been identified; hence their impacts on the operation of the electrolytic cell stack components and on microorganism growth rates and types are unknown. Identification of the compounds responsible for the TOC increase, their sources, and estimates of their loadings in the OGA as well as possible mitigation strategies are presented.

A closed recirculated sea-water system

USGS Publications Warehouse

1967-01-01

Study of a virus disease in the chinook salmon (Oncorhynchus tshawytscha) necessitated the use of a marine environment to study the long range effects of the disease and to complete the life cycle of its etiologic agent. A closed recirculated sea-water system was designed for use under experimental laboratory conditions so that controlled studies of the disease could be made. As others may wish to do marine environment studies in the laboratory, the design and operation of our system are presented. Other systems currently in use have been described by Chin (1959), DeWitt and Salo (1960), McCrimmon and Berst (1966), and the authors of collected papers edited by Clark and Clark (1964). Preparatory to the design and construction of the system in use in this laboratory, visits were made to marine systems in use at the University of Washington's College of Fisheries, Seattle, -washington, and Friday Harbor Laboratory, San Juan Island, Washington; the Washington State Department of Fisheries' Point whitney Shellfish Laboratory, Brinnon, Washington; Humboldt State College, Arcata, California; and the Steinhart Aquarium of the California Academy of Science, San Francisco, California.

Fiber-optic perimeter security system based on WDM technology

NASA Astrophysics Data System (ADS)

Polyakov, Alexandre V.

2017-10-01

Intelligent underground fiber optic perimeter security system is presented. Their structure, operation, software and hardware with neural networks elements are described. System allows not only to establish the fact of violation of the perimeter, but also to locate violations. This is achieved through the use of WDM-technology division spectral information channels. As used quasi-distributed optoelectronic recirculation system as a discrete sensor. The principle of operation is based on registration of the recirculation period change in the closed optoelectronic circuit at different wavelengths under microstrain exposed optical fiber. As a result microstrain fiber having additional power loss in a fiber optical propagating pulse, which causes a time delay as a result of switching moments of the threshold device. To separate the signals generated by intruder noise and interference, the signal analyzer is used, based on the principle of a neural network. The system detects walking, running or crawling intruder, as well as undermining attempts to register under the perimeter line. These alarm systems can be used to protect the perimeters of facilities such as airports, nuclear reactors, power plants, warehouses, and other extended territory.

Impact of water boundary layer diffusion on the nitrification rate of submerged biofilter elements from a recirculating aquaculture system.

PubMed

Prehn, Jonas; Waul, Christopher K; Pedersen, Lars-Flemming; Arvin, Erik

2012-07-01

Total ammonia nitrogen (TAN) removal by microbial nitrification is an essential process in recirculating aquaculture systems (RAS). In order to protect the aquatic environment and fish health, it is important to be able to predict the nitrification rates in RAS's. The aim of this study was to determine the impact of hydraulic film diffusion on the nitrification rate in a submerged biofilter. Using an experimental batch reactor setup with recirculation, active nitrifying biofilter units from a RAS were exposed to a range of hydraulic flow velocities. Corresponding nitrification rates were measured following ammonium chloride, NH₄Cl, spikes and the impact of hydraulic film diffusion was quantified. The nitrification performance of the tested biofilter could be significantly increased by increasing the hydraulic flow velocity in the filter. Area based first order nitrification rate constants ranged from 0.065 m d⁻¹ to 0.192 m d⁻¹ for flow velocities between 2.5 m h⁻¹ and 40 m h⁻¹ (18 °C). This study documents that hydraulic film diffusion may have a significant impact on the nitrification rate in fixed film biofilters with geometry and hydraulic flows corresponding to our experimental RAS biofilters. The results may thus have practical implications in relation to the design, operational strategy of RAS biofilters and how to optimize TAN removal in fixed film biofilter systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Cannulation for veno-venous extracorporeal membrane oxygenation

PubMed Central

2018-01-01

Extracorporeal membrane oxygenation (ECMO) is described as a modified, smaller cardiopulmonary bypass circuit. The veno-venous (VV) ECMO circuit drains venous blood, oxygenate the blood, and pump the blood back into the same venous compartment. Draining and reinfusing in the same compartment means there are a risk of recirculation. The draining position within the venous system, ECMO pump flow, return flow position within the venous system and the patients cardiac output (CO) all have an impact on recirculation. Using two single lumen cannulas or one dual lumen cannula, but also the design of the venous cannula, can have an impact on where within the venous system the cannula is draining blood and will affect the efficiency of the ECMO circuit. VV ECMO can be performed with different cannulation strategies. The use of two single lumen cannulas draining in inferior vena cava (IVC) and reinfusing in superior vena cava (SVC) or draining in SVC and reinfusing in IVC, or one dual lumen cannula inserted in right jugular vein is all possible cannulation strategies. Independent of cannulation strategy there will be a risk of recirculation. Efficiency can be reasonable in either strategy if the cannulas are carefully positioned and monitored during the dynamic procedure of pulmonary disease. The disadvantage draining from IVC only occurs when there is a need for converting from VV to veno-arterial (VA) ECMO, reinfusing in the femoral artery. Then draining from SVC is the most efficient strategy, draining low saturated venous blood, and also means low risk of dual circulation. PMID:29732177

Water System Architectures for Moon and Mars Bases

NASA Technical Reports Server (NTRS)

Jones, Harry W.; Hodgson, Edward W.; Kliss, Mark H.

2015-01-01

Water systems for human bases on the moon and Mars will recycle multiple sources of wastewater. Systems for both the moon and Mars will also store water to support and backup the recycling system. Most water system requirements, such as number of crew, quantity and quality of water supply, presence of gravity, and surface mission duration of 6 or 18 months, will be similar for the moon and Mars. If the water system fails, a crew on the moon can quickly receive spare parts and supplies or return to Earth, but a crew on Mars cannot. A recycling system on the moon can have a reasonable reliability goal, such as only one unrecoverable failure every five years, if there is enough stored water to allow time for attempted repairs and for the crew to return if repair fails. The water system that has been developed and successfully operated on the International Space Station (ISS) could be used on a moon base. To achieve the same high level of crew safety on Mars without an escape option, either the recycling system must have much higher reliability or enough water must be stored to allow the crew to survive the full duration of the Mars surface mission. A three loop water system architecture that separately recycles condensate, wash water, and urine and flush can improve reliability and reduce cost for a Mars base.

Inheriting Curiosity: Leveraging MBSE to Build Mars2020

NASA Technical Reports Server (NTRS)

Fosse, Elyse; Harmon, Corey; Lefland, Mallory; Castillo, Robert; Devereaux, Ann

2015-01-01

The success of the Jet Propulsion Laboratory's (JPL) Martian mission Mars Science Laboratory (MSL) prompted NASA to challenge JPL to build a second rover, Mars2020. Mars2020 has chosen to infuse Model Based Systems Engineering (MBSE) in pursuit of aiding the design of the Flight System. This paper will derive the motivation for MBSE infusion and will explain the current state of the Mars2020 Flight System Model. Successes in MBSE adoption will be discussed, as will limitations to the methodology.

Off-flavors in salmonids raised in recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

Producers of aquaculture products will typically verify the flavor quality of their product by sensory evaluation (flavor testing) before harvesting the crop for market. “Off-flavors” detected in the product may require holding the fish in a purging system containing fresh, clean water to depurate ...

Apparatus for controlling air/fuel ratio for internal combustion engine

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

Kato, K.; Mizuno, T.

1986-07-08

This patent describes an apparatus for controlling air-fuel ratio of an air-fuel mixture to be supplied to an internal combustion engine having an intake passage, an exhaust passage, an an exhaust gas recirculation passage for recirculating exhaust gases in the exhaust passage to the intake passage therethrough. The apparatus consists of: (a) means for sensing rotational speed of the engine; (b) means for sensing intake pressure in the intake passage; (c) means for sensing atmospheric pressure; (d) means for enabling and disabling exhaust gas recirculation through the exhaust gas recirculation passage in accordance with operating condition of the engine; (e)more » means for determining required amount of fuel in accordance with the sensed rotational speed and the sensed intake pressure; (f) means for determining, when the exhaust gas recirculation is enabled, a first correction value in accordance with the sensed rotational speed, the sensed intake pressure and the sensed atmospheric pressure, the first correction factor being used for correcting fuel amount so as to compensate for the decrease of fuel due to the performance of exhaust gas recirculation and also to compensate for the change in atmospheric pressure; (g) means for determining, when the exhaust gas recirculation is disabled, a second correction value in accordance with the atmospheric pressure, the second correction factor being used so as to compensate for the change in atmospheric pressure; (h) means for correcting the required amount of fuel by the first correction value and the second correction value when the exhaust gas recirculation is enabled and disabled respectively; and (i) means for supplying the engine with the corrected amount of fuel.« less

Experimental investigation of aerodynamics, combustion, and emissions characteristics within the primary zone of a gas turbine combustor

NASA Astrophysics Data System (ADS)

Elkady, Ahmed M.

2006-04-01

The present work investigates pollutant emissions production, mainly nitric oxides and carbon monoxide, within the primary zone of a highly swirling combustion and methods with which to reduce their formation. A baseline study was executed at different equivalence ratios and different inlet air temperatures. The study was then extended to investigate the effects of utilizing transverse air jets on pollutant emission characteristics at different jet locations, jet mass ratio, and overall equivalence ratio as well as to investigate the jets' overall interactions with the recirculation zone. A Fourier Transform Infrared (FTIR) spectrometer was employed to measure emissions concentrations generated during combustion of Jet-A fuel in a swirl-cup assembly. Laser Doppler Velocimetry (LDV) was employed to investigate the mean flow aerodynamics within the combustor. Particle Image Velocimetry (PIV) was utilized to capture the instantaneous aerodynamic behavior of the non-reacting primary zone. Results illustrate that NOx production is a function of both the recirculation zone and the flame length. At low overall equivalence ratios, the recirculation zone is found to be the main producer of NOx. At near stoichiometric conditions, the post recirculation zone appears to be responsible for the majority of NOx produced. Results reveal the possibility of injecting air into the recirculation zone without altering flame stability to improve emission characteristics. Depending on the jet location and strength, nitric oxides as well as carbon monoxide can be reduced simultaneously. Placing the primary air jet just downstream of the fuel rich recirculation zone can lead to a significant reduction in both nitric oxides and carbon monoxide. In the case of fuel lean recirculation zone, reduction of nitric oxides can occur by placing the jets below the location of maximum radius of the recirculation zone.

Characterisation of recirculation zones in complex terrain using multi-lidar measurements

NASA Astrophysics Data System (ADS)

Menke, R.; Mann, J.; Vasiljevic, N.

2017-12-01

Wind fields in complex terrain show a higher complexity compared to sites with simpler geometries. It is imperative to understand well the characteristics of complex flows to account for them during the site validation to ensure the wind turbines can withstand the local flow conditions. This study focuses on the description of recirculation zones occurring on lee sides of hills. The flow recirculation can have a significant impact on the success of wind energy projects since it represents one of the main contributors to the turbulence generation. An extensive dataset of observation of flow over complex terrain is available from the Perdigão 2017 field campaign (https://www.nature.com/news/world-s-largest-wind-mapping-project-spins-up-in-portugal-1.21481). A setup of 8 long-range WindScanners (Vasiljević et al., 2016), scanning lidars deployed by DTU performed RHI scans at several positions along two parallel ridges probing the flow field in two vertical planes, in addition data from several meteorological masts is available. With the above-mentioned lidar setup we achieved simultaneous dual-Doppler scans of the recirculation zone at three positions and simultaneous observations of recirculation behind two parallel ridges. Methods are developed to identify and define the extent of recirculation bubbles. Different parameters are defined to characterise the dimensions of the recirculation zone. The change of these parameters along the ridges is studied. In particular, the impact of atmospheric stability and the changes of the wind field at the position of the downwind ridge are investigated. Furthermore, the geometry of the recirculation zone for different wind directions and in connection to the upstream wind conditions is investigated.

Effect of hydraulic retention time and sludge recirculation on greenhouse gas emission and related microbial communities in two-stage membrane bioreactor treating solid waste leachate.

PubMed

Nuansawan, Nararatchporn; Boonnorat, Jarungwit; Chiemchaisri, Wilai; Chiemchaisri, Chart

2016-06-01

Methane (CH4) and nitrous oxide (N2O) emissions and responsible microorganisms during the treatment of municipal solid waste leachate in two-stage membrane bioreactor (MBR) was investigated. The MBR system, consisting of anaerobic and aerobic stages, were operated at hydraulic retention time (HRT) of 5 and 2.5days in each reactor under the presence and absence of sludge recirculation. Organic and nitrogen removals were more than 80% under all operating conditions during which CH4 emission were found highest under no sludge recirculation condition at HRT of 5days. An increase in hydraulic loading resulted in a reduction in CH4 emission from anaerobic reactor but an increase from the aerobic reactor. N2O emission rates were found relatively constant from anaerobic and aerobic reactors under different operating conditions. Diversity of CH4 and N2O producing microorganisms were found decreasing when hydraulic loading rate to the reactors was increased. Copyright © 2016 Elsevier Ltd. All rights reserved.

Providing Internet Access to High-Resolution Mars Images

NASA Technical Reports Server (NTRS)

Plesea, Lucian

2008-01-01

The OnMars server is a computer program that provides Internet access to high-resolution Mars images, maps, and elevation data, all suitable for use in geographical information system (GIS) software for generating images, maps, and computational models of Mars. The OnMars server is an implementation of the Open Geospatial Consortium (OGC) Web Map Service (WMS) server. Unlike other Mars Internet map servers that provide Martian data using an Earth coordinate system, the OnMars WMS server supports encoding of data in Mars-specific coordinate systems. The OnMars server offers access to most of the available high-resolution Martian image and elevation data, including an 8-meter-per-pixel uncontrolled mosaic of most of the Mars Global Surveyor (MGS) Mars Observer Camera Narrow Angle (MOCNA) image collection, which is not available elsewhere. This server can generate image and map files in the tagged image file format (TIFF), Joint Photographic Experts Group (JPEG), 8- or 16-bit Portable Network Graphics (PNG), or Keyhole Markup Language (KML) format. Image control is provided by use of the OGC Style Layer Descriptor (SLD) protocol. The OnMars server also implements tiled WMS protocol and super-overlay KML for high-performance client application programs.

Altering rainfall patterns through aerosol dispersion

NASA Astrophysics Data System (ADS)

Emetere, M. E.; Bakeko, M.; Onyechekwa, L.; Ayara, W.

2017-05-01

The possibility of recirculation mechanism on rainfall patterns is salient for sustenance of the human race through agricultural produce. The peculiarity of the lower atmosphere of south west region of Nigeria was explored using theoretical and experimental approach. In the theoretical approach, the reconstruction of 1D model as an extraction from the 3D aerosol dispersion model was used to examine the physics of the recirculation theory. The experimental approach which consists of obtaining dataset from ground instruments was used to provide on-site guide for developing the new recirculation theories. The data set was obtained from the Davis weather station, Nigeria Meteorological agency and Multi-angle Imaging Spectro-radiometer (MISR). We looked at the main drivers of recirculation and propounded that recirculation is a complex process which triggers a reordering of the mixing layer- a key factor for initiating the type of rainfall in this region.

Human Exploration of Mars Design Reference Architecture 5.0

NASA Technical Reports Server (NTRS)

Drake, Bret G.; Hoffman, Stephen J.; Beaty, David W.

2009-01-01

This paper provides a summary of the 2007 Mars Design Reference Architecture 5.0 (DRA 5.0), which is the latest in a series of NASA Mars reference missions. It provides a vision of one potential approach to human Mars exploration including how Constellation systems can be used. The reference architecture provides a common framework for future planning of systems concepts, technology development, and operational testing as well as Mars robotic missions, research that is conducted on the International Space Station, and future lunar exploration missions. This summary the Mars DRA 5.0 provides an overview of the overall mission approach, surface strategy and exploration goals, as well as the key systems and challenges for the first three human missions to Mars.

Mars Greenhouses: Concepts and Challenges. Proceedings from a 1999 Workshop

NASA Technical Reports Server (NTRS)

Wheeler, Ray M. (Editor); Martin-Brennan, Cindy (Editor)

2000-01-01

Topic covered include :Plants on Mars: On the Next Mission and in the Long Term Future; Bubbles in the Rocks: Natural and Artificial Caves and Cavities as Like Support Structures; Challenges for Bioregenerative Life Support on Mars; Cost Effectiveness Issues; Low Pressure Systems for Plant Growth; Plant Responses to Rarified Atmospheres; Can CO2 be Used as a Pressurizing Gas for Mars Greenhouses?; Inflatable Habitats Technology Development; Development of an Inflatable Greenhouse for a Modular Crop Production System; Mars Inflatable Greenhouse Workshop; Design Needs for Mars Deployable Greenhouse; Preliminary Estimates of the Possibilities for Developing a Deployable Greenhouse for a Planetary Surface Mars; Low Pressure Greenhouse Concepts for Mars; Mars Greenhouse Study: Natural vs. Artificial Lighting; and Wire Culture for an Inflatable Mars Greenhouse and Other Future Inflatable Space Growth Chambers.

Electrical power systems for Mars

NASA Technical Reports Server (NTRS)

Giudici, Robert J.

1986-01-01

Electrical power system options for Mars Manned Modules and Mars Surface Bases were evaluated for both near-term and advanced performance potential. The power system options investigated for the Mission Modules include photovoltaics, solar thermal, nuclear reactor, and isotope power systems. Options discussed for Mars Bases include the above options with the addition of a brief discussion of open loop energy conversion of Mars resources, including utilization of wind, subsurface thermal gradients, and super oxides. Electrical power requirements for Mission Modules were estimated for three basic approaches: as a function of crew size; as a function of electric propulsion; and as a function of transmission of power from an orbiter to the surface of Mars via laser or radio frequency. Mars Base power requirements were assumed to be determined by production facilities that make resources available for follow-on missions leading to the establishment of a permanently manned Base. Requirements include the production of buffer gas and propellant production plants.

Electrical power systems for Mars

NASA Astrophysics Data System (ADS)

Giudici, Robert J.

1986-05-01

Electrical power system options for Mars Manned Modules and Mars Surface Bases were evaluated for both near-term and advanced performance potential. The power system options investigated for the Mission Modules include photovoltaics, solar thermal, nuclear reactor, and isotope power systems. Options discussed for Mars Bases include the above options with the addition of a brief discussion of open loop energy conversion of Mars resources, including utilization of wind, subsurface thermal gradients, and super oxides. Electrical power requirements for Mission Modules were estimated for three basic approaches: as a function of crew size; as a function of electric propulsion; and as a function of transmission of power from an orbiter to the surface of Mars via laser or radio frequency. Mars Base power requirements were assumed to be determined by production facilities that make resources available for follow-on missions leading to the establishment of a permanently manned Base. Requirements include the production of buffer gas and propellant production plants.

Human Mars Transportation Applications Using Solar Electric Propulsion

NASA Technical Reports Server (NTRS)

Donahue, Benjamin B.; Martin, Jim; Potter, Seth; Henley, Mark; Carrington, Connie (Technical Monitor)

2000-01-01

Advanced solar electric power systems and electric propulsion technology constitute viable elements for conducting human Mars transfer missions that are roughly comparable in performance to similar missions utilizing alternative high thrust systems, with the one exception being their inability to achieve short Earth-Mars trip times. A modest solar electric propulsion human Mars scenario is presented that features the use of conjunction class trajectories in concert with pre-emplacement of surface assets that can be used in a series of visits to Mars. Major elements of the Mars solar electric transfer vehicle can be direct derivatives of present state-of-the-art Solar array and electric thruster systems. During the study, several elements affecting system performance were evaluated, including varying Earth orbit altitude for departure, recapturing the transfer stage at Earth for reuse, varying power system mass-to-power ratio, and assessing solar array degradation on performance induced by Van Allen belt passage. Comparisons are made to chemical propulsion and nuclear thermal propulsion Mars vehicles carrying similar payloads.

Validation of enhanced stabilization of municipal solid waste under controlled leachate recirculation using FTIR and XRD.

PubMed

Sethi, Sapna; Kothiyal, N C; Nema, Arvind K

2012-07-01

Leachate recirculation at neutral PH accompanied with buffer/nutrients addition has been used successfully in earlier stabilization of municipal solid waste in bioreactor landfills. In the present study, efforts were made to enhance the stabilization rate of municipal solid waste (MSW) and organic solid waste (OSW) in simulated landfill bioreactors by controlling the pH of recirculated leachate towards slightly alkaline side in absence of additional buffer and nutrients addition. Enhanced stabilization in waste samples was monitored with the help of analytical tools like Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD). Predominance of bands assigned to inorganic compounds and comparatively lower intensities of bands for organic compounds in the FTIR spectra of waste samples degraded with leachate recirculation under controlled pH confirmed higher rate of biodegradation and mineralization of waste than the samples degraded without controlled leachate recirculation. XRD spectra also confirmed to a greater extent of mineralization in the waste samples degraded under leachate recirculation with controlled pH. Comparison of XRD spectra of two types of wastes pointed out higher degree of mineralization in organic solid waste as compared to municipal solid waste.

40 CFR 63.401 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

..., ventilation, or air conditioning system. Initial startup means the initiation of recirculation water flow... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) NATIONAL EMISSION STANDARDS FOR HAZARDOUS AIR POLLUTANTS FOR SOURCE CATEGORIES National Emission Standards for...

Mars Telecommunications Orbiter Ka-band system design and operations

NASA Technical Reports Server (NTRS)

Noreen, Gary; Komarek, Tomas; Diehl, Roger; Shambayati, Shervin; Breidenthal, Julian; Lopez, Saturnino; Jordan, Frank

2003-01-01

NASA's Mars Telecommunications Orbiter (MTO) will relay broadband communications from landers, rovers and spacecraft in the vicinity of Mars to Earth. This paper describes the MTO communications system and how the MTO Ka-band system will be operated.

Hydrodynamics of octagonal culture tanks with Cornell-type dual-drain system

USDA-ARS?s Scientific Manuscript database

Large culture tanks of several hundred or thousand m3 size are generally encouraged for economic advantages in Recirculation Aquaculture Systems (RAS). Out of numerous possibilities in designing the inlet and outlet configurations in octagonal culture tanks, the inlet pipes near the corner walls and...

Processes to improve energy efficiency during pumping and aeration of recirculating water in circular tank systems

USDA-ARS?s Scientific Manuscript database

Conventional gas transfer technologies for aquaculture systems occupy a large amount of space, require considerable capital investment, and can contribute to high electricity demand. In addition, diffused aeration in a circular tank can interfere with the hydrodynamics of water rotation and the spee...

40 CFR 63.104 - Heat exchange system requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... heat exchange system or at locations where the cooling water enters and exits each heat exchanger or any combination of heat exchangers. (i) For samples taken at the entrance and exit of recirculating... manufacturing process units. (iii) For samples taken at the entrance and exit of each heat exchanger or any...

Performance Tests of High Speed ZRV Oil Skimmer.

DTIC Science & Technology

1980-06-01

clarified by recirculation through a 2,000 gpm diatomaceous earth filter system to permit full use of a sophisticated underwater photography and video...generator and beach, and a filter system. The wave generator and adsorber beach have capabilities of producing regular waves to 2.25 feet high and to 92

77 FR 488 - Control of Emissions From New Highway Vehicles and Engines; Approval of New Scheduled Maintenance...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-05

... and engine manufacturers began planning to meet those requirements by optimizing engine designs for low emissions and adding high-efficiency aftertreatment systems. Manufacturers examined the use of... recirculation, and selective catalytic reduction (SCR). SCR systems use a nitrogen-containing reducing agent...

Optimizing hydraulic retention times in denitrifying woodchip bioreactors treating recirculating aquaculture system wastewater

USDA-ARS?s Scientific Manuscript database

The performance of wood-based denitrifying bioreactors to treat high-nitrate wastewaters from aquaculture systems has not previously been demonstrated. Four pilot-scale woodchip bioreactors (approximately 1:10 scale) were constructed and operated for 268 d to determine the optimal range of design hy...

Weight loss and fillet quality characteristics of Atlantic salmon (Salmo salar) after purging for 5, 10, 15 or 20 days

USDA-ARS?s Scientific Manuscript database

Atlantic salmon, Salmo salar, are typically cultured in marine net pens. However, technological advancements in recirculating aquaculture systems have increased the feasibility of culturing Atlantic salmon in land-based systems to alleviate environmental and disease issues limiting sustainability. ...

KSC-99pp1397

NASA Image and Video Library

1999-12-09

A spare four-inch diameter LH2 recirculation line (shown in photo) will be used to replace a damaged LH2 line in the orbiter Discovery. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. Workers noted a dent in the line during routine aft compartment inspections Tuesday, Dec. 7. The dent measures 12 inches long and about ½-inch deep. Managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope

Recirculating Molten Metal Supply System And Method

DOEpatents

Kinosz, Michael J.; Meyer, Thomas N.

2003-07-01

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).

A simple method to recover Norovirus from fresh produce with large sample size by using histo-blood group antigen-conjugated to magnetic beads in a recirculating affinity magnetic separation system (RCAMS).

PubMed

Tian, Peng; Yang, David; Mandrell, Robert

2011-06-30

Human norovirus (NoV) outbreaks are major food safety concerns. The virus has to be concentrated from food samples in order to be detected. PEG precipitation is the most common method to recover the virus. Recently, histo-blood group antigens (HBGA) have been recognized as receptors for human NoV, and have been utilized as an alternative method to concentrate human NoV for samples up to 40 mL in volume. However, to wash off the virus from contaminated fresh food samples, at least 250 mL of wash volume is required. Recirculating affinity magnetic separation system (RCAMS) has been tried by others to concentrate human NoV from large-volume samples and failed to yield consistent results with the standard procedure of 30 min of recirculation at the default flow rate. Our work here demonstrates that proper recirculation time and flow rate are key factors for success in using the RCAMS. The bead recovery rate was increased from 28% to 47%, 67% and 90% when recirculation times were extended from 30 min to 60 min, 120 min and 180 min, respectively. The kinetics study suggests that at least 120 min recirculation is required to obtain a good recovery of NoV. In addition, different binding and elution conditions were compared for releasing NoV from inoculated lettuce. Phosphate-buffered saline (PBS) and water results in similar efficacy for virus release, but the released virus does not bind to RCAMS effectively unless pH was adjusted to acidic. Either citrate-buffered saline (CBS) wash, or water wash followed by CBS adjustment, resulted in an enhanced recovery of virus. We also demonstrated that the standard curve generated from viral RNA extracted from serially-diluted virus samples is more accurate for quantitative analysis than standard curves generated from serially-diluted plasmid DNA or transcribed-RNA templates, both of which tend to overestimate the concentration power. The efficacy of recovery of NoV from produce using RCAMS was directly compared with that of the PEG method in NoV inoculated lettuce. 40, 4, 0.4, and 0.04 RTU can be detected by both methods. At 0.004 RTU, NoV was detectable in all three samples concentrated by the RCAMS method, while none could be detected by the PEG precipitation method. RCAMS is a simple and rapid method that is more sensitive than conventional methods for recovery of NoV from food samples with a large sample size. In addition, the RTU value detected through RCAMS-processed samples is more biologically relevant. Published by Elsevier B.V.

Diesel NO(x) aftertreatment by combined process using temperature swing adsorption, NO(x) reduction by nonthermal plasma, and NO(x) recirculation: improvement of the recirculation process.

PubMed

Yoshida, Keiichiro; Kuwahara, Takuya; Kuroki, Tomoyuki; Okubo, Masaaki

2012-09-15

NO(x) emitted from a stationary diesel engine generator was treated with a hybrid system comprising NO(x) reduction by nonthermal plasma (NTP) and temperature swing adsorption (TSA) driven by engine waste heat. TSA produces a low-volume gas mixture of N(2) and highly concentrated NO(x), which is effectively reduced by NTP treatment. Improved treatment performance and efficiency are achieved by re-injecting the NTP-treated gas mixture into the engine intake. The system comprises two switchable adsorption chambers; the operation of this system was simulated by using a one-chamber system. The maximum energy efficiency for NO(x) treatment is 200 g(NO(2))/kWh. The respective contributions of NTP and injection of N(2) and NO(x) to the performance were theoretically analyzed. The analysis predicts that high energy efficiency and high NO(x)-removal efficiency can be simultaneously achieved with this system but miniaturization of the adsorption chambers will be a challenge. Copyright © 2012 Elsevier B.V. All rights reserved.

Mobile Audience Response Systems at a Continuing Medical Education Conference.

PubMed

Beaumont, Alexandra; Gousseau, Michael; Sommerfeld, Connor; Leitao, Darren; Gooi, Adrian

2017-01-01

Mobile audience response systems (mARS) are electronic systems allowing speakers to ask questions and audience members to respond anonymously and immediately on a screen which enables learners to view their peers' responses as well as their own. mARS encourages increased interaction and active learning. This study aims to examine the perceptions of audience members and speakers towards the implementation of mARS at a national medical conference. mARS was implemented at the CSO Annual Meeting in Winnipeg 2015. Eleven presenters agreed to participate in the mARS trial. Both audience and presenters received instructions. Five-point Likert questions and short answer questions were emailed to all conference attendees and the data was evaluated. Twenty-seven participants responded, 23 audience members and 4 instructors. Overall, responders indicated improved attention, involvement, engagement and recognition of audience's understanding of topics with the use of mARS. mARS was perceived as easy to use, with clear instructions, and the majority of respondents expressed an interest in using mARS in more presentations and in future national medical conferences. Most respondents preferred lectures with mARS over lectures without mARS. Some negative feedback on mARS involved dissatisfaction with how some presenters implemented mARS into the workshops. Overall mARS was perceived positively with the majority of respondents wanting mARS implemented in more national medical conferences. Future studies should look at how mARS can be used as an educational tool to help improve patient outcomes.

The Role of Water Chemistry in Marine Aquarium Design: A Model System for a General Chemistry Class

ERIC Educational Resources Information Center

Keaffaber, Jeffrey J.; Palma, Ramiro; Williams, Kathryn R.

2008-01-01

Water chemistry is central to aquarium design, and it provides many potential applications for discussion in undergraduate chemistry and engineering courses. Marine aquaria and their life support systems feature many chemical processes. A life support system consists of the entire recirculation system, as well as the habitat tank and all ancillary…

Four years experience with filtration systems in commercial nurseries for eliminating Phytophthora species from recirculation water

Treesearch

T. Ufer; M. Posner; H.-P. Wessels; S. Wagner; K. Kaminski; T. Brand; Werres S.

2008-01-01

In a four year project, three different filtration systems were tested under commercial nursery conditions to eliminate Phytophthora spp. from irrigation water. Five nurseries were involved in the project. Slow sand filtration systems were tested in three nurseries. In the fourth nursery, a filtration system with lava grains (Shieer® Bio filtration)...

Study of advanced fuel system concepts for commercial aircraft

NASA Technical Reports Server (NTRS)

Coffinberry, G. A.

1985-01-01

An analytical study was performed in order to assess relative performance and economic factors involved with alternative advanced fuel systems for future commercial aircraft operating with broadened property fuels. The DC-10-30 wide-body tri-jet aircraft and the CF6-8OX engine were used as a baseline design for the study. Three advanced systems were considered and were specifically aimed at addressing freezing point, thermal stability and lubricity fuel properties. Actual DC-10-30 routes and flight profiles were simulated by computer modeling and resulted in prediction of aircraft and engine fuel system temperatures during a nominal flight and during statistical one-day-per-year cold and hot flights. Emergency conditions were also evaluated. Fuel consumption and weight and power extraction results were obtained. An economic analysis was performed for new aircraft and systems. Advanced system means for fuel tank heating included fuel recirculation loops using engine lube heat and generator heat. Environmental control system bleed air heat was used for tank heating in a water recirculation loop. The results showed that fundamentally all of the three advanced systems are feasible but vary in their degree of compatibility with broadened-property fuel.

Engine Performance (Section C: Emission Control Systems). Auto Mechanics Curriculum Guide. Module 3. Instructor's Guide.

ERIC Educational Resources Information Center

Rains, Larry

This engine performance (emission control systems) module is one of a series of competency-based modules in the Missouri Auto Mechanics Curriculum Guide. Topics of this module's five units are: positive crankcase ventilation (PCV) and evaporative emission control systems; exhaust gas recirculation (EGR); air injection and catalytic converters;…

Zero Gravity Cryogenic Vent System Concepts for Upper Stages

NASA Astrophysics Data System (ADS)

Ravex, Alain; Flachbart, Robin; Holt, Barney

The capability to vent in zero gravity without resettling is a technology need that involves practically all uses of sub-critical cryogenics in space. Venting without resettling would extend cryogenic orbital transfer vehicle capabilities. However, the lack of definition regarding liquid/ullage orientation coupled with the somewhat random nature of the thermal stratification and resulting pressure rise rates, lead to significant technical challenges. Typically a zero gravity vent concept, termed a thermodynamic vent system (TVS), consists of a tank mixer to destratify the propellant, combined with a Joule-Thomson (J-T) valve to extract thermal energy from the propellant. Marshall Space Flight Center's (MSFC's) Multipurpose Hydrogen Test Bed (MHTB) was used to test both spray bar and axial jet TVS concepts. The axial jet system consists of a recirculation pump heat exchanger unit. The spray bar system consists of a recirculation pump, a parallel flow concentric tube, heat exchanger, and a spray bar positioned close to the longitudinal axis of the tank. The operation of both concepts is similar. In the mixing mode, the recirculation pump withdraws liquid from the tank and sprays it into the tank liquid, ullage, and exposed tank surfaces. When energy extraction is required, a small portion of the recirculated liquid is passed sequentially through the J-T expansion valve, the heat exchanger, and is vented overboard. The vented vapor cools the circulated bulk fluid, thereby removing thermal energy and reducing tank pressure. The pump operates alone, cycling on and off, to destratify the tank liquid and ullage until the liquid vapor pressure reaches the lower set point. At that point, the J-T valve begins to cycle on and off with the pump. Thus, for short duration missions, only the mixer may operate, thus minimizing or even eliminating boil-off losses. TVS performance testing demonstrated that the spray bar was effective in providing tank pressure control within a 6.89 kPa (1psi) band for fill levels of 90%, 50%, and 25%. Complete destratification of the liquid and ullage was achieved at these fill levels. The axial jet was effective in providing tank pressure control within the same pressure control band at the 90% fill level. However, at the 50% level, the system reached a point at which it was unable to extract enough energy to keep up with the heat leak into the tank. Due to a hardware problem, the recirculation pump operated well below the axial jet design flow rate. Therefore, it is likely that the performance of the axial jet would have improved had the pump operated at the proper flow rate. A CFD model is being used to determine if the desired axial jet performance would be achieved if a higher pump flow rate were available. Testing conducted thus far has demonstrated that both TVS concepts can be effective in destratifying a propellant tank, rejecting stored heat energy, and thus, controlling tank pressure.

Experimental Investigation of Combustion Stabilization in Supersonic Flow Using Free Recirculation Zones

DTIC Science & Technology

1997-08-01

NUMBERS Experimental Investigation of Combustion Stabilization in Supersonic Flow Using Free F6170896W0291 Recirculation Zones 6. AUTHOR(S) Dr...stabilization in supersonic flow using free recirculation zones Special contract (SPC-96-4043) with Air Force Office of Scientific Research (AFMC), USA, EOARD...of three quarterly reports and presents experimental results on self-ignition and combustion stabilization in supersonic flow using free

Use of hemodialysis in meprobamate overdosage.

PubMed

Lobo, P I; Spyker, D; Surratt, P; Westervelt, F B

1977-02-01

A case of meprobamate overdosage successfully treated with hemodialysis is described. The patient was admitted 4 hours after an overdosage of meprobamate (30-40 g) deeply unconscious, hypotensive, in respiratory failure and with a serum meprobamate level of 50 mg/100 ml. Hemodialysis was instituted using a Gambro parallel flow dialyzer and a portable re-circulating dialyzate delivery system (Redy, CCi Life Systems). Meprobamate removal with hemodialysis was 672+/-167 mg/hr with a corresponding clearance of 61.97+/-9.9 ml/min. Drug removal with forced diuresis was 177+/-23.4 mg/hr. Metabolic degradation of the drug was approximately 482 mg/hr with a plasma disappearance rate of 5.2%/hr. No drug could be detected in the dialyzate fluid after its passage through the Redy re-circulating dialyzate system. Because of the rapidity of metabolic degradation of meprobamate, we feel that hemodialysis should be reserved for severe clinical intoxication and either compromised normal excretory routes or progressive clinical deterioration.

Solar heated office complex--Greenwood, South Carolina

NASA Technical Reports Server (NTRS)

1981-01-01

Report contains thorough docuumentation of project meeting 85 percent of building heat requirements. System uses roof mounted recirculating water solar panels and underground hot water energy storage. Aluminum film reflectors increase total solar flux captured by panels.

Fungal biodiversity and mycotoxigenic fungi in cooling-tower water systems in Istanbul, Turkey.

PubMed

Kadaifciler, Duygu Göksay; Demirel, Rasime

2017-04-01

This is the first study to assess fungal diversity and mycotoxigenic fungi in open recirculating cooling-tower (CT) water systems (biofilm and water phase). The production capability of mycotoxin from fungal isolates was also examined. The mean fungal count in 21 different water and biofilm samples was determined as 234 CFU/100 mL and 4 CFU/cm 2 . A total of 32 species were identified by internal transcribed spacer (ITS) sequencing. The most common isolated fungi belonged to the genera Aspergillus and Penicillium, of which the most prevalent fungi were Aspergillus versicolor, Aspergillus niger, and Penicillium dipodomyicola. From 42% of the surveyed CTs, aflatoxigenic A. flavus isolates were identified. The detection of opportunistic pathogens and/or allergen species suggests that open recirculating CTs are a possible source of fungal infection for both the public and for occupational workers via the inhalation of aerosols and/or skin contact.

Low pressure EGR system having full range capability

DOEpatents

Easley, Jr., William Lanier; Milam, David Michael; Roozenboom, Stephan Donald; Bond, Michael Steven; Kapic, Amir

2009-09-22

An exhaust treatment system for an engine is disclosed and may have an air induction circuit, an exhaust circuit, and an exhaust recirculation circuit. The air induction circuit may be configured to direct air into the engine. The exhaust circuit may be configured to direct exhaust from the engine and include a turbine driven by the exhaust, a particulate filter disposed in series with and downstream of the turbine, and a catalytic device disposed in series with and downstream of the particulate filter. The exhaust recirculation circuit may be configured to selectively redirect at least some of the exhaust from between the particulate filter and the catalytic device to the air induction circuit. The catalytic device is selected to create backpressure within the exhaust circuit sufficient to ensure that, under normal engine operating conditions above low idle, exhaust can flow into the air induction circuit without throttling of the air.

Use of Martian resources in a Controlled Ecological Life Support System (CELSS)

NASA Technical Reports Server (NTRS)

Smernoff, David T.; Macelroy, Robert D.

1989-01-01

Possibile crew life support systems for Mars are reviewed, focusing on ways to use Martian resources as life support materials. A system for bioregenerative life support using photosynthetic organisms, known as the Controlled Ecological Life Support System (CELSS), is examined. The possible use of higher plants or algae to produce oxygen on Mars is investigated. The specific requirements for a CELSS on Mars are considered. The exploitation of water, respiratory gases, and mineral nutrients on Mars is discussed.

Design challenges for electronic medication administration record systems in residential aged care facilities: a formative evaluation.

PubMed

Tariq, A; Lehnbom, E; Oliver, K; Georgiou, A; Rowe, C; Osmond, T; Westbrook, J

2014-01-01

Electronic medication administration record (eMAR) systems are promoted as a potential intervention to enhance medication safety in residential aged care facilities (RACFs). The purpose of this study was to conduct an in-practice evaluation of an eMAR being piloted in one Australian RACF before its roll out, and to provide recommendations for system improvements. A multidisciplinary team conducted direct observations of workflow (n=34 hours) in the RACF site and the community pharmacy. Semi-structured interviews (n=5) with RACF staff and the community pharmacist were conducted to investigate their views of the eMAR system. Data were analysed using a grounded theory approach to identify challenges associated with the design of the eMAR system. The current eMAR system does not offer an end-to-end solution for medication management. Many steps, including prescribing by doctors and communication with the community pharmacist, are still performed manually using paper charts and fax machines. Five major challenges associated with the design of eMAR system were identified: limited interactivity; inadequate flexibility; problems related to information layout and semantics; the lack of relevant decision support; and system maintenance issues. We suggest recommendations to improve the design of the eMAR system and to optimize existing workflows. Immediate value can be achieved by improving the system interactivity, reducing inconsistencies in data entry design and offering dedicated organisational support to minimise connectivity issues. Longer-term benefits can be achieved by adding decision support features and establishing system interoperability requirements with stakeholder groups (e.g. community pharmacies) prior to system roll out. In-practice evaluations of technologies like eMAR system have great value in identifying design weaknesses which inhibit optimal system use.

Design Challenges for Electronic Medication Administration Record Systems in Residential Aged Care Facilities

PubMed Central

Lehnbom, E.; Oliver, K.; Georgiou, A.; Rowe, C.; Osmond, T.; Westbrook, J.

2014-01-01

Summary Introduction Electronic medication administration record (eMAR) systems are promoted as a potential intervention to enhance medication safety in residential aged care facilities (RACFs). The purpose of this study was to conduct an in-practice evaluation of an eMAR being piloted in one Australian RACF before its roll out, and to provide recommendations for system improvements. Methods A multidisciplinary team conducted direct observations of workflow (n=34 hours) in the RACF site and the community pharmacy. Semi-structured interviews (n=5) with RACF staff and the community pharmacist were conducted to investigate their views of the eMAR system. Data were analysed using a grounded theory approach to identify challenges associated with the design of the eMAR system. Results The current eMAR system does not offer an end-to-end solution for medication management. Many steps, including prescribing by doctors and communication with the community pharmacist, are still performed manually using paper charts and fax machines. Five major challenges associated with the design of eMAR system were identified: limited interactivity; inadequate flexibility; problems related to information layout and semantics; the lack of relevant decision support; and system maintenance issues. We suggest recommendations to improve the design of the eMAR system and to optimize existing workflows. Discussion Immediate value can be achieved by improving the system interactivity, reducing inconsistencies in data entry design and offering dedicated organisational support to minimise connectivity issues. Longer-term benefits can be achieved by adding decision support features and establishing system interoperability requirements with stakeholder groups (e.g. community pharmacies) prior to system roll out. In-practice evaluations of technologies like eMAR system have great value in identifying design weaknesses which inhibit optimal system use. PMID:25589911

Boosting devices with integral features for recirculating exhaust gas

DOEpatents

Wu, Ko-Jen

2015-12-22

According to one embodiment of the invention, a turbine housing includes a turbine inlet in fluid communication with a turbine volute configured to house a turbine wheel, the turbine inlet configured to direct an exhaust gas flow from an engine to the turbine wheel. The turbine housing also includes a turbine outlet in fluid communication with the turbine volute, the turbine outlet configured to direct the exhaust gas flow to an exhaust gas conduit and a first exhaust gas recirculation supply port located on and in fluid communication with the turbine outlet, the first exhaust gas recirculation supply port being configured to direct a portion of the exhaust gas flow to an exhaust gas recirculation supply conduit.

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

NASA Technical Reports Server (NTRS)

Nallasamy, M.

1987-01-01

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.

Perspective for Aquaponic Systems: "Omic" Technologies for Microbial Community Analysis.

PubMed

Munguia-Fragozo, Perla; Alatorre-Jacome, Oscar; Rico-Garcia, Enrique; Torres-Pacheco, Irineo; Cruz-Hernandez, Andres; Ocampo-Velazquez, Rosalia V; Garcia-Trejo, Juan F; Guevara-Gonzalez, Ramon G

2015-01-01

Aquaponics is the combined production of aquaculture and hydroponics, connected by a water recirculation system. In this productive system, the microbial community is responsible for carrying out the nutrient dynamics between the components. The nutrimental transformations mainly consist in the transformation of chemical species from toxic compounds into available nutrients. In this particular field, the microbial research, the "Omic" technologies will allow a broader scope of studies about a current microbial profile inside aquaponics community, even in those species that currently are unculturable. This approach can also be useful to understand complex interactions of living components in the system. Until now, the analog studies were made to set up the microbial characterization on recirculation aquaculture systems (RAS). However, microbial community composition of aquaponics is still unknown. "Omic" technologies like metagenomic can help to reveal taxonomic diversity. The perspectives are also to begin the first attempts to sketch the functional diversity inside aquaponic systems and its ecological relationships. The knowledge of the emergent properties inside the microbial community, as well as the understanding of the biosynthesis pathways, can derive in future biotechnological applications. Thus, the aim of this review is to show potential applications of current "Omic" tools to characterize the microbial community in aquaponic systems.

Enabling technologies for Chinese Mars lander guidance system

NASA Astrophysics Data System (ADS)

Jiang, Xiuqiang; Li, Shuang

2017-04-01

Chinese first Mars exploration activity, orbiting landing and roaming collaborative mission, has been programmed and started. As a key technology, Mars lander guidance system is intended to serve atmospheric entry, descent and landing (EDL) phases. This paper is to report the formation process of enabling technology road map for Chinese Mars lander guidance system. First, two scenarios of the first-stage of the Chinese Mars exploration project are disclosed in detail. Second, mission challenges and engineering needs of EDL guidance, navigation, and control (GNC) are presented systematically for Chinese Mars exploration program. Third, some useful related technologies developed in China's current aerospace projects are pertinently summarized, especially on entry guidance, parachute descent, autonomous hazard avoidance and safe landing. Finally, an enabling technology road map of Chinese Mars lander guidance is given through technological inheriting and improving.

The abundance and diversity of heterotrophic bacteria as a function of harvesting frequency of duckweed (Lemna minor L.) in recirculating aquaculture systems.

PubMed

Ardiansyah, A; Fotedar, R

2016-07-01

Duckweed (Lemna minor L.) is a potential biofilter for nutrient removal and acts as a substrate for heterotrophic bacteria in recirculating aquaculture systems (RAS). Here, we determined the effects of harvesting frequency of duckweed on heterotrophic bacteria in RAS. Twelve independent RAS consisting of fish-rearing tank, biofilter tank and waste-collection tank were used to study the interactions between duckweed harvest frequencies up to 6 days and the composition, abundance and diversity of heterotrophic bacteria. After 36 days, heterotrophic bacteria in the biofilter tank were primarily Gram-negative cocci or ovoid, coccobacilli, Gram-negative bacilli and Gram-positive bacilli. Most bacterial genera were Bacillus and Pseudomonas while the least common was Acinetobacter. Duckweed harvested after every 2 days produced the highest specific growth rates (SGR) and total harvested biomass of duckweed, but harboured less abundant bacteria, whereas 6-day harvests had a higher growth index (GI) of duckweed than 2-day harvests, but caused a poor relationship between SGR and biomass harvest with the abundance and diversity of heterotrophic bacteria. Stronger correlations (R(2)  > 0·65) between duckweed SGR and biomass harvest with the heterotrophic bacteria diversity were observed at 4-day harvest frequency and the control. This study provides significant information on the interaction between the harvest frequency of duckweed and the composition, abundance and diversity of heterotrophic bacteria in recirculating aquaculture systems (RAS). Different harvest frequencies significantly influence the abundance and diversity of heterotrophic bacteria, which in turn may influence the nitrogen uptake efficiency of the system. The research is useful in improving the efficiency of removing nitrogenous metabolites in RAS directly by the duckweed and associated heterotrophic bacteria. © 2016 The Society for Applied Microbiology.

Multi-point optimization of recirculation flow type casing treatment in centrifugal compressors

NASA Astrophysics Data System (ADS)

Tun, Min Thaw; Sakaguchi, Daisaku

2016-06-01

High-pressure ratio and wide operating range are highly required for a turbocharger in diesel engines. A recirculation flow type casing treatment is effective for flow range enhancement of centrifugal compressors. Two ring grooves on a suction pipe and a shroud casing wall are connected by means of an annular passage and stable recirculation flow is formed at small flow rates from the downstream groove toward the upstream groove through the annular bypass. The shape of baseline recirculation flow type casing is modified and optimized by using a multi-point optimization code with a metamodel assisted evolutionary algorithm embedding a commercial CFD code CFX from ANSYS. The numerical optimization results give the optimized design of casing with improving adiabatic efficiency in wide operating flow rate range. Sensitivity analysis of design parameters as a function of efficiency has been performed. It is found that the optimized casing design provides optimized recirculation flow rate, in which an increment of entropy rise is minimized at grooves and passages of the rotating impeller.

Recirculating linacs for a neutrino factory - Arc optics design and optimization

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

Alex Bogacz; Valeri Lebedev

2001-10-21

A conceptual lattice design for a muon accelerator based on recirculating linacs (Nucl. Instr. and Meth. A 472 (2001) 499, these proceedings) is presented here. The challenge of accelerating and transporting a large phase space of short-lived muons is answered here by presenting a proof-of-principle lattice design for a recirculating linac accelerator. It is the centerpiece of a chain of accelerators consisting of a 3GeV linac and two consecutive recirculating linear accelerators, which facilitates acceleration starting after ionization cooling at 190MeV/c and proceeding to 50GeV. Beam transport issues for large-momentum-spread beams are accommodated by appropriate lattice design choices. The resultingmore » arc optics is further optimized with a sextupole correction to suppress chromatic effects contributing to the emittance dilution. The presented proof-of-principle design of the arc optics with horizontal separation of multi-pass beams can be extended to all passes in both recirculating linacs.« less

Recirculating linacs for a neutrino factory - Arc optics design and optimization

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

Valeri Lebedev; S. Bogacz

2001-10-25

A conceptual lattice design for a muon accelerator based on recirculating linacs (Nucl. Instr. and Meth. A 472 (2001) 499, these proceedings) is presented here. The challenge of accelerating and transporting a large phase space of short-lived muons is answered here by presenting a proof-of-principle lattice design for a recirculating linac accelerator. It is the centerpiece of a chain of accelerators consisting of a 3 GeV linac and two consecutive recirculating linear accelerators, which facilitates acceleration starting after ionization cooling at 190 MeV/c and proceeding to 50 GeV. Beam transport issues for large-momentum-spread beams are accommodated by appropriate lattice designmore » choices. The resulting arc optics is further optimized with a sextupole correction to suppress chromatic effects contributing to the emittance dilution. The presented proof-of-principle design of the arc optics with horizontal separation of multi-pass beams can be extended to all passes in both recirculating linacs.« less

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

NASA Technical Reports Server (NTRS)

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

1985-01-01

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

Mission to Mars using integrated propulsion concepts: considerations, opportunities, and strategies.

PubMed

Accettura, Antonio G; Bruno, Claudio; Casotto, Stefano; Marzari, Francesco

2004-04-01

The aim of this paper is to evaluate the feasibility of a mission to Mars using the Integrated Propulsion Systems (IPS) which means to couple Nuclear-MPD-ISPU propulsion systems. In particular both mission analysis and propulsion aspects are analyzed together with technological aspects. Identifying possible mission scenarios will lead to the study of possible strategies for Mars Exploration and also of methods for reducing cost. As regard to IPS, the coupling between Nuclear Propulsion (Rubbia's engine) and Superconductive MPD propulsion is considered for the Earth-Mars trajectories: major emphasis is given to the advantages of such a system. The In Situ Resource Utilization (ISRU) concerns on-Mars operations; In Situ Propellant Utilization (ISPU) is foreseen particularly for LOX-CH4 engines for Mars Ascent Vehicles and this possibility is analyzed from a technological point of view. Tether Systems are also considered during interplanetary trajectories and as space elevators on Mars orbit. Finally strategic considerations associated to this mission are considered also. c2003 Elsevier Ltd. All rights reserved.

The New LMK Primary Standard for Dew-Point Sensor Calibration: Evaluation of the High-Range Saturator Efficiency

NASA Astrophysics Data System (ADS)

Hudoklin, Domen; Drnovšek, Janko

2008-10-01

In the field of hygrometry, a primary dew-point standard can be realized according to several proven principles, such as single-pressure (1-P), two-pressure (2-P), or divided flow. Different realizations have been introduced by various national laboratories, each resulting in a stand-alone complex generation system. Recent trends in generator design favor the single-pressure principle without recirculation because it promises theoretically lower uncertainty and because it avoids problems regarding the leak tightness of the recirculation. Instead of recirculation, the efficiency of saturation, the key factor, is increased by preconditioning the inlet gas entering the saturator. For preconditioning, a presaturator or purifier is used to bring the dew point of the inlet stream close to the saturator temperature. The purpose of the paper is to identify the minimum requirements for the preconditioning system and the main saturator to assure efficient saturation for the LMK generator. Moreover, the aim is also to find out if the preconditioning system can be avoided despite the rather simple construction of the main saturator. If this proves to be the case, the generator design can be simplified while maintaining an accurate value of the generated dew point. Experiments were carried out within the scope of improving our existing primary generator in the above-ambient dew-point range up to +70°C. These results show the generated dew point is within the measurement uncertainty for any dew-point value of the inlet gas. Thus, the preconditioning subsystem can be avoided, which leads to a simplified generator design.

Speciation, behaviour, and fate of mercury under oxy-fuel combustion conditions.

PubMed

Córdoba, Patricia; Maroto-Valer, M; Delgado, Miguel Angel; Diego, Ruth; Font, Oriol; Querol, Xavier

2016-02-01

The work presented here reports the first study in which the speciation, behaviour and fate of mercury (Hg) have been evaluated under oxy-fuel combustion at the largest oxy-Pulverised Coal Combustion (oxy-PCC) demonstration plant to date during routine operating conditions and partial exhaust flue gas re-circulation to the boiler. The effect of the CO2-rich flue gas re-circulation on Hg has also been evaluated. Results reveal that oxy-PCC operational conditions play a significant role on Hg partitioning and fate because of the continuous CO2-rich flue gas re-circulations to the boiler. Mercury escapes from the cyclone in a gaseous form as Hg(2+) (68%) and it is the prevalent form in the CO2-rich exhaust flue gas (99%) with lower proportions of Hg(0) (1.3%). The overall retention rate for gaseous Hg is around 12%; Hg(0) is more prone to be retained (95%) while Hg(2+) shows a negative efficiency capture for the whole installation. The negative Hg(2+) capture efficiencies are due to the continuous CO2-rich exhaust flue gas recirculation to the boiler with enhanced Hg contents. Calculations revealed that 44mg of Hg were re-circulated to the boiler as a result of 2183 re-circulations of CO2-rich flue gas. Especial attention must be paid to the role of the CO2-rich exhaust flue gas re-circulation to the boiler on the Hg enrichment in Fly Ashes (FAs). Copyright © 2015 Elsevier Inc. All rights reserved.

Known Locations of Carbonate Rocks on Mars

NASA Technical Reports Server (NTRS)

2008-01-01

Green dots show the locations of orbital detections of carbonate-bearing rocks on Mars, determined by analysis of targeted observations by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) acquired through January 2008. The spectrometer is on NASA's Mars Reconnaissance Orbiter.

The base map is color-coded global topography (red is high, blue is low) overlain on mosaicked daytime thermal infrared images. The topography data are from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor. The thermal infrared imagery is from the Thermal Emission Imaging System camera on NASA's Mars Odyssey orbiter.

The CRISM team, led by The Johns Hopkins University Applied Physics Laboratory, Laurel, Md., includes expertise from universities, government agencies and small businesses in the United States and abroad. Arizona State University, Tempe, operates the Thermal Emission Imaging System, which the university developed in collaboration with Raytheon Santa Barbara Remote Sensing.

NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter and Mars Odyssey projects for the NASA Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiters.

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

Córdoba, Patricia, E-mail: pc247@hw.ac.uk; Maroto-Valer, M.; Delgado, Miguel Angel

The work presented here reports the first study in which the speciation, behaviour and fate of mercury (Hg) have been evaluated under oxy-fuel combustion at the largest oxy-Pulverised Coal Combustion (oxy-PCC) demonstration plant to date during routine operating conditions and partial exhaust flue gas re-circulation to the boiler. The effect of the CO{sub 2}-rich flue gas re-circulation on Hg has also been evaluated. Results reveal that oxy-PCC operational conditions play a significant role on Hg partitioning and fate because of the continuous CO{sub 2}-rich flue gas re-circulations to the boiler. Mercury escapes from the cyclone in a gaseous form asmore » Hg{sup 2+} (68%) and it is the prevalent form in the CO{sub 2}-rich exhaust flue gas (99%) with lower proportions of Hg{sup 0} (1.3%). The overall retention rate for gaseous Hg is around 12%; Hg{sup 0} is more prone to be retained (95%) while Hg{sup 2+} shows a negative efficiency capture for the whole installation. The negative Hg{sup 2+} capture efficiencies are due to the continuous CO{sub 2}-rich exhaust flue gas recirculation to the boiler with enhanced Hg contents. Calculations revealed that 44 mg of Hg were re-circulated to the boiler as a result of 2183 re-circulations of CO{sub 2}-rich flue gas. Especial attention must be paid to the role of the CO{sub 2}-rich exhaust flue gas re-circulation to the boiler on the Hg enrichment in Fly Ashes (FAs). - Highlights: • The fate of gaseous Hg has been evaluated under oxy-fuel combustion. • The Hg oxidation process is enhanced in CO{sub 2}-rich flue gas recirculation. • Hg{sup 2+} is the prevalent gas species in the CO{sub 2}-rich exhaust flue gas. • Hg{sup 2+}{sub (g)} shows a negative efficiency capture for the whole installation. • Especial attention must be paid to the Hg enrichment in Fly Ashes.« less

The Design of Exhaust Systems and Discharge Stacks [With Comments].

ERIC Educational Resources Information Center

Clarke, John H.

1963-01-01

An important part of ventilating for safety consists of providing the necessary exhaust systems to remove building contaminants safely. Further, the effluent must be cleaned within practical limits by means of filters, collectors, and scrubbers. Where recirculation is not safe or feasible, the effluent must be discharged to the outside in a manner…

A review of factors influencing maturation of atlantic salmon salmo salar with focus on water recirculation aquaculture system environments

USDA-ARS?s Scientific Manuscript database

Maturation of Atlantic salmon Salmo salar is an extremely complex process, particularly in aquaculture systems, with many variables (known or otherwise) having the capacity to influence the timing and prevalence of maturation, and acting as promoters and/or inhibitors of sexual development. The vast...

For operation of the Computer Software Management and Information Center (COSMIC)

NASA Technical Reports Server (NTRS)

Carmon, J. L.

1983-01-01

Computer programs for large systems of normal equations, an interactive digital signal process, structural analysis of cylindrical thrust chambers, swirling turbulent axisymmetric recirculating flows in practical isothermal combustor geometrics, computation of three dimensional combustor performance, a thermal radiation analysis system, transient response analysis, and a software design analysis are summarized.

Simultaneous carbon and nitrogen removal using an oxic/anoxic-biocathode microbial fuel cells coupled system.

PubMed

Xie, Shan; Liang, Peng; Chen, Yang; Xia, Xue; Huang, Xia

2011-01-01

A coupled microbial fuel cell (MFC) system comprising of an oxic-biocathode MFC (O-MFC) and an anoxic-biocathode MFC (A-MFC) was implemented for simultaneous removal of carbon and nitrogen from a synthetic wastewater. The chemical oxygen demand (COD) of the influent was mainly reduced at the anodes of the two MFCs; ammonium was oxidized to nitrate in the O-MFC's cathode, and nitrate was electrochemically denitrified in the A-MFC's cathode. The coupled MFC system reached power densities of 14 W/m(3) net cathodic compartment (NCC) and 7.2 W/m(3) NCC for the O-MFC and the A-MFC, respectively. In addition, the MFC system obtained a maximum COD, NH(4)(+)-N and TN removal rate of 98.8%, 97.4% and 97.3%, respectively, at an A-MFC external resistance of 5 Ω, a recirculation ratio (recirculated flow to total influent flow) of 2:1, and an influent flow ratio (O-MFC anode flow to A-MFC anode flow) of 1:1. Copyright © 2010 Elsevier Ltd. All rights reserved.

Microbial Community Dynamics and Response to Plant Growth-Promoting Microorganisms in the Rhizosphere of Four Common Food Crops Cultivated in Hydroponics.

PubMed

Sheridan, C; Depuydt, P; De Ro, M; Petit, C; Van Gysegem, E; Delaere, P; Dixon, M; Stasiak, M; Aciksöz, S B; Frossard, E; Paradiso, R; De Pascale, S; Ventorino, V; De Meyer, T; Sas, B; Geelen, D

2017-02-01

Plant growth promoting microorganisms (PGPMs) of the plant root zone microbiome have received limited attention in hydroponic cultivation systems. In the framework of a project aimed at the development of a biological life support system for manned missions in space, we investigated the effects of PGPMs on four common food crops (durum and bread wheat, potato and soybean) cultivated in recirculating hydroponic systems for a whole life cycle. Each crop was inoculated with a commercial PGPM mixture and the composition of the microbial communities associated with their root rhizosphere, rhizoplane/endosphere and with the recirculating nutrient solution was characterised through 16S- and ITS-targeted Illumina MiSeq sequencing. PGPM addition was shown to induce changes in the composition of these communities, though these changes varied both between crops and over time. Microbial communities of PGPM-treated plants were shown to be more stable over time. Though additional development is required, this study highlights the potential benefits that PGPMs may confer to plants grown in hydroponic systems, particularly when cultivated in extreme environments such as space.

An ISRU Propellant Production System to Fully Fuel a Mars Ascent Vehicle

NASA Technical Reports Server (NTRS)

Kleinhenz, Julie E.; Paz, Aaron

2017-01-01

In-Situ Resource Utilization (ISRU) will enable the long term presence of humans beyond low earth orbit. Since 2009, oxygen production from the Mars atmosphere has been baselined as an enabling technology for Mars human exploration by NASA. However, using water from the Martian regolith in addition to the atmospheric CO2 would enable the production of both liquid Methane and liquid Oxygen, thus fully fueling a Mars return vehicle. A case study was performed to show how ISRU can support NASA's Evolvable Mars Campaign (EMC) using methane and oxygen production from Mars resources. A model was built and used to generate mass and power estimates of an end-to-end ISRU system including excavation and extraction water from Mars regolith, processing the Mars atmosphere, and liquefying the propellants. Even using the lowest yield regolith, a full ISRU system would weigh 1.7 mT while eliminating the need to transport 30 mT of ascent propellants from earth.

Heterotrophic denitrification of aquaculture effluent using fluidized sand biofilters

USDA-ARS?s Scientific Manuscript database

The ability to consistently and cost-effectively reduce nitrate-nitrogen loads in effluent from recirculating aquaculture systems would enhance the industry's environmental stewardship and allow improved facility proximity to large markets in sensitive watersheds. Heterotrophic denitrification techn...

Optimizing depuration of salmon in RAS

USDA-ARS?s Scientific Manuscript database

Fish cultured within water recirculating aquaculture systems (RAS) can acquire "earthy" or "musty" off-flavors due to bioaccumulation of the compounds geosmin and 2-methylisoborneol (MIB), respectively, which are produced by certain bacterial species present in RAS biosolids and microbial biofilms. ...

Turbulent Recirculating Flows in Isothermal Combustor Geometries

NASA Technical Reports Server (NTRS)

Lilley, D.; Rhode, D.

1985-01-01

Computer program developed that provides mathematical solution to design and construction of combustion chambers for jet engines. Improved results in areas of combustor flow fields accomplished by this computerprogram solution, cheaper and quicker than experiments involving real systems for models.

Human and Robotic Exploration Missions to Phobos Prior to Crewed Mars Surface Missions

NASA Technical Reports Server (NTRS)

Gernhardt, Michael L.; Chappell, Steven P.; Bekdash, Omar S.; Abercromby, Andrew F. J.; Crues, Edwin Z.; Li, Zu Qun; Bielski, Paul; Howe, A. Scott

2016-01-01

Phobos is a scientifically significant destination that would facilitate the development and operation of the human Mars transportation infrastructure, unmanned cargo delivery systems and other Mars surface systems. In addition to developing systems relevant to Mars surface missions, Phobos offers engineering, operational, and public engagement opportunities that could enhance subsequent Mars surface operations. These opportunities include the use of low latency teleoperations to control Mars surface assets associated with exploration science, human landing-site selection and infrastructure development, which may include in situ resource utilization (ISRU) to provide liquid oxygen for the Mars Ascent Vehicle (MAV). A human mission to Mars' moons would be preceded by a cargo pre-deploy of a surface habitat and a pressurized excursion vehicle (PEV) to Mars orbit. Once in Mars orbit, the habitat and PEV would spiral to Phobos using solar electric propulsion based systems, with the habitat descending to the surface and the PEV remaining in orbit. When a crewed mission is launched to Phobos, it would include the remaining systems to support the crew during the Earth-Mars transit and to reach Phobos after insertion in to Mars orbit. The crew would taxi from Mars orbit to Phobos to join with the predeployed systems in a spacecraft that is based on a MAV, dock with and transfer to the PEV in Phobos orbit, and descend in the PEV to the surface habitat. A static Phobos surface habitat was chosen as a baseline architecture, in combination with the PEV that was used to descend from orbit as the main exploration vehicle. The habitat would, however, have limited capability to relocate on the surface to shorten excursion distances required by the PEV during exploration and to provide rescue capability should the PEV become disabled. To supplement exploration capabilities of the PEV, the surface habitat would utilize deployable EVA support structures that allow astronauts to work from portable foot restraints or body restrain tethers in the vicinity of the habitat. Prototype structures were tested as part of NEEMO 20.

Power plant emissions reduction

DOEpatents

Anand, Ashok Kumar; Nagarjuna Reddy, Thirumala Reddy

2015-10-20

A system for improved emissions performance of a power plant generally includes an exhaust gas recirculation system having an exhaust gas compressor disposed downstream from the combustor, a condensation collection system at least partially disposed upstream from the exhaust gas compressor, and a mixing chamber in fluid communication with the exhaust gas compressor and the condensation collection system, where the mixing chamber is in fluid communication with the combustor.

Human Exploration of Mars Design Reference Architecture 5.0

NASA Technical Reports Server (NTRS)

Drake, Bret G.

2010-01-01

This paper provides a summary of the Mars Design Reference Architecture 5.0 (DRA 5.0), which is the latest in a series of NASA Mars reference missions. It provides a vision of one potential approach to human Mars exploration. The reference architecture provides a common framework for future planning of systems concepts, technology development, and operational testing as well as Mars robotic missions, research that is conducted on the International Space Station, and future lunar exploration missions. This summary the Mars DRA 5.0 provides an overview of the overall mission approach, surface strategy and exploration goals, as well as the key systems and challenges for the first three human missions to Mars.

Mars Solar Power

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Kerslake, Thomas W.; Jenkins, Phillip P.; Scheiman, David A.

2004-01-01

NASA missions to Mars, both robotic and human, rely on solar arrays for the primary power system. Mars presents a number of challenges for solar power system operation, including a dusty atmosphere which modifies the spectrum and intensity of the incident solar illumination as a function of time of day, degradation of the array performance by dust deposition, and low temperature operation. The environmental challenges to Mars solar array operation will be discussed and test results of solar cell technology operating under Mars conditions will be presented, along with modeling of solar cell performance under Mars conditions. The design implications for advanced solar arrays for future Mars missions is discussed, and an example case, a Martian polar rover, are analyzed.

Mars integrated transportation system multistage Mars mission

NASA Technical Reports Server (NTRS)

1991-01-01

In accordance with the objective of the Mars Integrated Transport System (MITS) program, the Multistage Mars Mission (MSMM) design team developed a profile for a manned mission to Mars. The purpose of the multistage mission is to send a crew of five astronauts to the martian surface by the year 2019. The mission continues man's eternal quest for exploration of new frontiers. This mission has a scheduled duration of 426 days that includes experimentation en route as well as surface exploration and experimentation. The MSMM is also designed as a foundation for a continuing program leading to the colonization of the planet Mars.

Study of advanced atmospheric entry systems for Mars

NASA Technical Reports Server (NTRS)

1978-01-01

Entry system designs are described for various advanced Mars missions including sample return, hard lander, and Mars airplane. The Mars exploration systems for sample return and the hard lander require decleration from direct approach entry velocities of about 6 km/s to terminal velocities consistent with surface landing requirements. The Mars airplane entry system is decelerated from orbit at 4.6 km/s to deployment near the surface. Mass performance characteristics of major elements of the Mass performance characteristics are estimated for the major elements of the required entry systems using Viking technology or logical extensions of technology in order to provide a common basis of comparison for the three entry modes mission mode approaches. The entry systems, although not optimized, are based on Viking designs and reflect current hardware performance capability and realistic mass relationships.

Demonstration of Critical Systems for Propellant Production on Mars for Science and Exploration Missions

NASA Technical Reports Server (NTRS)

Linne, Diane L.; Gaier, James R.; Zoeckler, Joseph G.; Kolacz, John S.; Wegeng, Robert S.; Rassat, Scot D.; Clark, D. Larry

2013-01-01

A Mars hopper has been proposed as a Mars mobility concept that will also demonstrate and advance in-situ resource utilization. The components needed in a Mars propellant production plant have been developed to various levels of technology maturity, but there is little experience with the systems in a Mars environment. Two systems for the acquisition and compression of the thin carbon dioxide atmosphere were designed, assembled, and tested in a Mars environment chamber. A microchannel sorption pump system was able to raise the pressure from 7 Torr to 450 Torr or from 12 Torr to over 700 Torr in two stages. This data now provides information needed to make additional improvements in the sorption pump technology to increase performance, although a system-level analysis might prove that some amount of pre- or post-compression may be a preferred solution. A mini cryofreezer system was also evaluated as an alternative method for carbon dioxide acquisition and compression. Finally, an electrolysis system was tested and successfully demonstrated start-up operation and thermal stability of all components during long-term operation in the chamber.

Effects of elevated atmospheric carbon dioxide concentrations on water and acid requirements of soybeans grown in a recirculating hydroponic system

NASA Technical Reports Server (NTRS)

Mackowiak, C. L.; Wheeler, R. M.; Lowery, W.; Sager, J. C.

1990-01-01

Establishing mass budgets of various crop needs, i.e. water and nutrients, in different environments is essential for the Controlled Ecological Life Support System (CELSS). The effects of CO2 (500 and 1000 umol mol (exp -1)) on water and acid use (for pH control) by soybeans in a recirculating hydroponic system were examined. Plants of cvs. McCall and Pixie were grown for 90 days using the nutrient film technique (NFT) and a nitrate based nutrient solution. System acid use for both CO2 levels peaked near 4 weeks during a phase of rapid vegetative growth, but acid use decreased more rapidly under 500 compared to 1000 umol mol (exp GR) CO2. Total system water use by 500 and 1000 umol mol (exp -1) plants was similar, leaving off at 5 weeks and declining as plants senesced (ca. 9 weeks). However, single leaf transpiration rates were consistently lower at 1000 umol mol (exp -1). The data suggest that high CO2 concentrations increase system acid (and nutrient) use because of increased vegetative growth, which in turn negates the benefit of reduced water use (lower transpiration rates) per unit leaf area.

Mars Aerocapture and Validation of Mars-GRAM with TES Data

NASA Technical Reports Server (NTRS)

Justus, C. G.; Duvall, Aleta; Keller, Vernon W.

2005-01-01

Mars Global Reference Atmospheric Model (Mars-GRAM) is a widely-used engineering- level Mars atmospheric model. Applications include systems design, performance analysis, and operations planning for aerobraking, entry descent and landing, and aerocapture. Typical Mars aerocapture periapsis altitudes (for systems with rigid-aeroshell heat shields) are about 50 km. This altitude is above the 0-40 km height range covered by Mars Global Surveyor Thermal Emission Spectrometer (TES) nadir observations. Recently, TES limb sounding data have been made available, spanning more than two Mars years (more than 200,000 data profiles) with altitude coverage up to about 60 km, well within the height range of interest for aerocapture. Results are presented comparing Mars-GRAM atmospheric density with densities from TES nadir and limb sounding observations. A new Mars-GRAM feature is described which allows individual TES nadir or limb profiles to be extracted from the large TES databases, and to be used as an optional replacement for standard Mars-GRAM background (climatology) conditions. For Monte-Carlo applications such as aerocapture guidance and control studies, Mars-GRAM perturbations are available using these TES profile background conditions.

Simultaneous energy generation and UV quencher removal from landfill leachate using a microbial fuel cell.

PubMed

Iskander, Syeed Md; Novak, John T; Brazil, Brian; He, Zhen

2017-11-01

The presence of UV quenching compounds in landfill leachate can negatively affect UV disinfection in a wastewater treatment plant when leachate is co-treated. Herein, a microbial fuel cell (MFC) was investigated to remove UV quenchers from a landfill leachate with simultaneous bioelectricity generation. The key operating parameters including hydraulic retention time (HRT), anolyte recirculation rate, and external resistance were systematically studied to maximize energy recovery and UV absorbance reduction. It was found that nearly 50% UV absorbance was reduced under a condition of HRT 40 days, continuous anolyte recirculation, and 10 Ω external resistance. Further analysis showed a total reduction of organics by 75.3%, including the reduction of humic acids, fulvic acids, and hydrophilic fraction concentration as TOC. The MFC consumed 0.056 kWh m -3 by its pump system for recirculation and oxygen supply. A reduced HRT of 20 days with periodical anode recirculation (1 hour in every 24 hours) and 39 Ω external resistance (equal to the internal resistance of the MFC) resulted in the highest net energy of 0.123 kWh m -3 . Granular activated carbon (GAC) was used as an effective post-treatment step and could achieve 89.1% UV absorbance reduction with 40 g L -1 . The combined MFC and GAC treatment could reduce 92.9% of the UV absorbance and remove 89.7% of the UV quenchers. The results of this study would encourage further exploration of using MFCs as an energy-efficient method for removing UV quenchers from landfill leachate.

Energy consumption by forward osmosis treatment of landfill leachate for water recovery.

PubMed

Iskander, Syeed Md; Zou, Shiqiang; Brazil, Brian; Novak, John T; He, Zhen

2017-05-01

Forward osmosis (FO) is an alternative approach for treating landfill leachate with potential advantages of reducing leachate volume and recovering high quality water for direct discharge or reuse. However, energy consumption by FO treatment of leachate has not been examined before. Herein, the operational factors such as recirculation rates and draw concentrations were studied for their effects on the quantified energy consumption by an FO system treating actual leachate collected from two different landfills. It was found that the energy consumption increased with a higher recirculation rate and decreased with a higher draw concentration, and higher water recovery tended to reduce energy consumption. The highest energy consumption was 0.276±0.033kWhm -3 with the recirculation rate of 110mLmin -1 and 1-M draw concentration, while the lowest of 0.005±0.000kWhm -3 was obtained with 30mLmin -1 recirculation and 3-M draw concentration. The leachate with lower concentrations of the contaminants had a much lower requirement for energy, benefited from its higher water recovery. Osmotic backwashing appeared to be more effective for removing foulants, but precise understanding of membrane fouling and its controlling methods will need a long-term study. The results of this work have implied that FO treatment of leachate could be energy efficient, especially with the use of a suitable draw solute that can be regenerated in an energy efficient way and/or through combination with other treatment technologies that can reduce contaminant concentrations before FO treatment, which warrants further investigation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multivariate Analysis, Retrieval, and Storage System (MARS). Volume 6: MARS System - A Sample Problem (Gross Weight of Subsonic Transports)

NASA Technical Reports Server (NTRS)

Hague, D. S.; Woodbury, N. W.

1975-01-01

The Mars system is a tool for rapid prediction of aircraft or engine characteristics based on correlation-regression analysis of past designs stored in the data bases. An example of output obtained from the MARS system, which involves derivation of an expression for gross weight of subsonic transport aircraft in terms of nine independent variables is given. The need is illustrated for careful selection of correlation variables and for continual review of the resulting estimation equations. For Vol. 1, see N76-10089.

Mars Aerocapture Systems Study

NASA Technical Reports Server (NTRS)

Wright, Henry S.; Oh, David Y.; Westhelle, Carlos H.; Fisher, Jody L.; Dyke, R. Eric; Edquist, Karl T.; Brown, James L.; Justh, Hilary L.; Munk, Michelle M.

2006-01-01

Mars Aerocapture Systems Study (MASS) is a detailed study of the application of aerocapture to a large Mars robotic orbiter to assess and identify key technology gaps. This study addressed use of an Opposition class return segment for use in the Mars Sample Return architecture. Study addressed mission architecture issues as well as system design. Key trade studies focused on design of aerocapture aeroshell, spacecraft design and packaging, guidance, navigation and control with simulation, computational fluid dynamics, and thermal protection system sizing. Detailed master equipment lists are included as well as a cursory cost assessment.

Software for Tracking Costs of Mars Projects

NASA Technical Reports Server (NTRS)

Wong, Alvin; Warfield, Keith

2003-01-01

The Mars Cost Tracking Model is a computer program that administers a system set up for tracking the costs of future NASA projects that pertain to Mars. Previously, no such tracking system existed, and documentation was written in a variety of formats and scattered in various places. It was difficult to justify costs or even track the history of costs of a spacecraft mission to Mars. The present software enables users to maintain all cost-model definitions, documentation, and justifications of cost estimates in one computer system that is accessible via the Internet. The software provides sign-off safeguards to ensure the reliability of information entered into the system. This system may eventually be used to track the costs of projects other than only those that pertain to Mars.

Summary Report on the Navy Emergency Escape Breathing Device

DTIC Science & Technology

1983-08-08

recirculated cas. The device produces pure oxygen (02) and uses a venturi to recirculate unused and expired gases through the purifier. A rubber...passing the recirculated air through a lithium hydroxide (LiOH) scrubber . The scrubber reduces the CO. level by forming either lithium bicarbonate (LiSCO...transparent visor and an elastromeric neck seal; a chlorate candle-based 02 generator; an air purification filter or scrubberl and a venturi arrangement to

Recirculating Electron Accelerators with Noncircular Electron Orbits as Radiation Sources for Applications (a Review)

NASA Astrophysics Data System (ADS)

Dubinov, Alexander E.; Ochkina, Elena I.

2018-05-01

State-of-the-art compact recirculating electron accelerators operating at intermediate energies (tens of MeV) are reviewed. The acceleration schemes implemented in the rhodotron, ridgetron, fantron, and cylindertron machines are discussed. Major accelerator components such as the electron guns, accelerating cavities, and bending magnets are described. The parameters of currently operating recirculating accelerators are tabulated, and applications of these accelerators in different processes of irradiation are exemplified.

Transport driven by eddy momentum fluxes in the Gulf Stream Extension region

NASA Astrophysics Data System (ADS)

Greatbatch, R. J.; Zhai, X.; Claus, M.; Czeschel, L.; Rath, W.

2010-12-01

The importance of the Gulf Stream Extension region in climate and seasonal prediction research is being increasingly recognised. Here we use satellite-derived eddy momentum fluxes to drive a shallow water model for the North Atlantic Ocean that includes the realistic ocean bottom topography. The results show that the eddy momentum fluxes can drive significant transport, sufficient to explain the observed increase in transport of the Gulf Stream following its separation from the coast at Cape Hatteras, as well as the observed recirculation gyres. The model also captures recirculating gyres seen in the mean sea surface height field within the North Atlantic Current system east of the Grand Banks of Newfoundland, including a representation of the Mann Eddy.

Degradation of trichloroethylene by photocatalysis in an internally circulating slurry bubble column reactor.

PubMed

Jeon, Jin Hee; Kim, Sang Done; Lim, Tak Hyoung; Lee, Dong Hyun

2005-08-01

The effects of initial trichloroethylene (TCE) concentration, recirculating liquid flow rate and gas velocity on photodegradation of TCE have been determined in an internally circulating slurry bubble column reactor (0.15m-ID x 0.85 m-high). Titanium dioxide (TiO2) powder was employed as a photocatalyst and the optimum loading of TiO2 in the present system is found to be approximately 0.2 wt%. The stripping fraction of TCE by air flow increases but photodegradation fraction of TCE decreases with increasing the initial TCE concentration, recirculating liquid flow rate and gas velocity. The average removal efficiency of TCE is found to be approximately 97% in an internally circulating slurry bubble column reactor.

Research on lunar and planet development and utilization

NASA Astrophysics Data System (ADS)

Iwata, Tsutomu; Etou, Takao; Imai, Ryouichi; Oota, Kazuo; Kaneko, Yutaka; Maeda, Toshihide; Takano, Yutaka

1992-08-01

Status of the study on unmanned and manned lunar missions, unmanned Mars missions, lunar resource development and utilization missions, remote sensing exploration missions, survey and review to elucidate the problems of research and development for lunar resource development and utilization, and the techniques and equipment for lunar and planet exploration are presented. Following items were studied respectively: (1) spacecraft systems for unmanned lunar missions, such as lunar observation satellites, lunar landing vehicles, lunar surface rovers, lunar surface hoppers, and lunar sample retrieval; (2) spacecraft systems for manned lunar missions, such as manned lunar bases, lunar surface operation robots, lunar surface experiment systems, manned lunar take-off and landing vehicles, and lunar freight transportation ships; (3) spacecraft systems for Mars missions, such as Mars satellites, Phobos and Deimos sample retrieval vehicles, Mars landing explorers, Mars rovers, Mars sample retrieval; (4) lunar resource development and utilization; and (5) remote sensing exploration technologies.

Effect of ammoniacal nitrogen on one-stage and two-stage anaerobic digestion of food waste

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

Ariunbaatar, Javkhlan, E-mail: jaka@unicas.it; UNESCO-IHE Institute for Water Education, Westvest 7, 2611 AX Delft; Scotto Di Perta, Ester

Highlights: • Almost 100% of the biomethane potential of food waste was recovered during AD in a two-stage CSTR. • Recirculation of the liquid fraction of the digestate provided the necessary buffer in the AD reactors. • A higher OLR (0.9 gVS/L·d) led to higher accumulation of TAN, which caused more toxicity. • A two-stage reactor is more sensitive to elevated concentrations of ammonia. • The IC{sub 50} of TAN for the AD of food waste amounts to 3.8 g/L. - Abstract: This research compares the operation of one-stage and two-stage anaerobic continuously stirred tank reactor (CSTR) systems fed semi-continuouslymore » with food waste. The main purpose was to investigate the effects of ammoniacal nitrogen on the anaerobic digestion process. The two-stage system gave more reliable operation compared to one-stage due to: (i) a better pH self-adjusting capacity; (ii) a higher resistance to organic loading shocks; and (iii) a higher conversion rate of organic substrate to biomethane. Also a small amount of biohydrogen was detected from the first stage of the two-stage reactor making this system attractive for biohythane production. As the digestate contains ammoniacal nitrogen, re-circulating it provided the necessary alkalinity in the systems, thus preventing an eventual failure by volatile fatty acids (VFA) accumulation. However, re-circulation also resulted in an ammonium accumulation, yielding a lower biomethane production. Based on the batch experimental results the 50% inhibitory concentration of total ammoniacal nitrogen on the methanogenic activities was calculated as 3.8 g/L, corresponding to 146 mg/L free ammonia for the inoculum used for this research. The two-stage system was affected by the inhibition more than the one-stage system, as it requires less alkalinity and the physically separated methanogens are more sensitive to inhibitory factors, such as ammonium and propionic acid.« less

Effect of copper on the growth of shrimps Litopenaeus vannamei: water parameters and copper budget in a recirculating system

NASA Astrophysics Data System (ADS)

Cheng, Bo; Liu, Ying; Yang, Hongsheng; Song, Yi; Li, Xian

2014-09-01

Shrimps ( Litopenaeus vannamei) were intensively cultured in a recirculating aquaculture system for 98 days to investigate effects of 0.3 mg/L Cu on its performance, Cu budget, and Cu distribution. Shrimps in Cu-treated systems had greater mean final weight (11.10 vs 10.50 g), body length (107.23 vs 106.42 mm), survival rate (67.80% vs 66.40%), and yield (6.42 vs 5.99 kg/m3), and lower feed conversion ratio (1.20 vs 1.29) than those in control systems but the differences were not significant. Vibrio numbers remained stable (104-106 colony forming units/mL) in the rearing tanks of both control and treated systems. Total ammonium-N, nitrite-N, nitrate-N, pH, chemical oxygen demand, 5-day carbonaceous biochemical oxygen demand, and total suspended solids were similar in controls and treatments. Dissolved Cu concentration in the treated systems decreased from 0.284 to 0.089 mg/L while in the control systems it increased from 0.006 2 to 0.018 mg/L. The main sources of Cu in the treated systems were the artificially added component (75.7% of total input), shrimp feed (21.0%), water (2.06%), and shrimp biomass (1.22%). The major outputs of Cu occurred via the mechanical filter (41.7%), water renewal (15.6%), and draining of the sediment trap (15.1%). The foam fractionator removed only 0.69% of total Cu input. Harvested shrimp biomass accounted for 11.68% of Cu input. The Cu concentration of shrimps in the Cu-treated systems (30.70 mg/kg wet weight) was significantly higher than that in control systems (22.02 mg/kg). Both were below the maximum permissible concentration (50 mg/kg) for Cu in seafood for human consumption in China. Therefore, recirculating systems can be used for commercial on-growing of Litopenaeus vannamei without loss of shrimp quality, even in water polluted by 0.30 mg/L Cu. The mechanical filter is the main route for Cu removal.

Mars Hybrid Propulsion System Trajectory Analysis. Part I; Crew Missions

NASA Technical Reports Server (NTRS)

Chai, Patrick R.; Merrill, Raymond G.; Qu, Min

2015-01-01

NASAs Human spaceflight Architecture team is developing a reusable hybrid transportation architecture in which both chemical and electric propulsion systems are used to send crew and cargo to Mars destinations such as Phobos, Deimos, the surface of Mars, and other orbits around Mars. By combining chemical and electrical propulsion into a single space- ship and applying each where it is more effective, the hybrid architecture enables a series of Mars trajectories that are more fuel-efficient than an all chemical architecture without significant increases in flight times. This paper provides the analysis of the interplanetary segments of the three Evolvable Mars Campaign crew missions to Mars using the hybrid transportation architecture. The trajectory analysis provides departure and arrival dates and propellant needs for the three crew missions that are used by the campaign analysis team for campaign build-up and logistics aggregation analysis. Sensitivity analyses were performed to investigate the impact of mass growth, departure window, and propulsion system performance on the hybrid transportation architecture. The results and system analysis from this paper contribute to analyses of the other human spaceflight architecture team tasks and feed into the definition of the Evolvable Mars Campaign.

On the effects of mass and momentum transfer from droplets impacting on steady two-dimensional rimming flow in a horizontal cylinder

NASA Astrophysics Data System (ADS)

Williams, J.; Hibberd, S.; Power, H.; Riley, D. S.

2012-05-01

Motivated by applications in aero-engines, steady two-dimensional thin-film flow on the inside of a circular cylinder is studied when the film surface is subject to mass and momentum transfer from impacting droplets. Asymptotic analysis is used systematically to identify distinguished limits that incorporate these transfer effects at leading order and to provide a new mathematical model. Applying both analytical and numerical approaches to the model, a set of stable steady, two-dimensional solutions that fit within the rational framework is determined. A number of these solutions feature steep fronts and associated recirculating pools, which are undesirable in an aeroengine since oil may be stripped away from the steep fronts when there is a core flow external to the film, and recirculation may lead to oil degradation. The model, however, provides a means of investigating whether the formation of the steep fronts on the film surface and of internal recirculation pools can be delayed, or inhibited altogether, by designing jets to deliver prescribed distributions of oil droplets or by the judicious siting of oil sinks. Moreover, by studying pathlines, oil-residence times can be predicted and systems optimized.

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

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

Korte, N.; Muck, M.; Kearl, P.

1998-08-01

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 becausemore » 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).« less

Designing and Testing of Self-Cleaning Recirculating Zebrafish Tanks.

PubMed

Nema, Shubham; Bhargava, Yogesh

2016-08-01

Maintenance of large number of zebrafish in captive conditions is a daunting task. This can be eased by the use of recirculating racks with self-cleaning zebrafish tanks. Commercially available systems are costly, and compatibility of intercompany products has never been investigated. Although various cost-effective designs and methods of construction of custom-made recirculating zebrafish racks are available in literature, the design of self-cleaning zebrafish tanks is still not available. In this study, we report the design and method of construction of the self-cleaning unit, which can be fitted in any zebrafish tank. We validated the design by investigating sediment cleaning process in rectangular and cylindrical tank geometries using time lapse imaging. Our results suggest that for both tank geometries, the tanks fitted with self-cleaning unit provided superior sediment cleaning than the tanks fitted with overflow-drain unit. Although the self-cleaning unit could clean the sediment completely from both geometries over prolonged period, the cleaning of sediments was faster in the cylindrical tank than the rectangular tank. In conclusion, cost and efforts of zebrafish maintenance could be significantly reduced through the installation of our self-cleaning unit in any custom-made zebrafish tank.

Interactions between pool geometry and hydraulics

USGS Publications Warehouse

Thompson, Douglas M.; Nelson, Jonathan M.; Wohl, Ellen E.

1998-01-01

An experimental and computational research approach was used to determine interactions between pool geometry and hydraulics. A 20-m-long, 1.8-m-wide flume was used to investigate the effect of four different geometric aspects of pool shape on flow velocity. Plywood sections were used to systematically alter constriction width, pool depth, pool length, and pool exit-slope gradient, each at two separate levels. Using the resulting 16 unique geometries with measured pool velocities in four-way factorial analyses produced an empirical assessment of the role of the four geometric aspects on the pool flow patterns and hence the stability of the pool. To complement the conclusions of these analyses, a two-dimensional computational flow model was used to investigate the relationships between pool geometry and flow patterns over a wider range of conditions. Both experimental and computational results show that constriction and depth effects dominate in the jet section of the pool and that pool length exhibits an increasing effect within the recirculating-eddy system. The pool exit slope appears to force flow reattachment. Pool length controls recirculating-eddy length and vena contracta strength. In turn, the vena contracta and recirculating eddy control velocities throughout the pool.

Atmospheric Risk Assessment for the Mars Science Laboratory Entry, Descent, and Landing System

NASA Technical Reports Server (NTRS)

Chen, Allen; Vasavada, Ashwin; Cianciolo, Alicia; Barnes, Jeff; Tyler, Dan; Hinson, David; Lewis, Stephen

2010-01-01

In 2012, the Mars Science Laboratory (MSL) mission will pioneer the next generation of robotic Entry, Descent, and Landing (EDL) systems, by delivering the largest and most capable rover to date to the surface of Mars. As with previous Mars landers, atmospheric conditions during entry, descent, and landing directly impact the performance of MSL's EDL system. While the vehicle's novel guided entry system allows it to "fly out" a range of atmospheric uncertainties, its trajectory through the atmosphere creates a variety of atmospheric sensitivities not present on previous Mars entry systems and landers. Given the mission's stringent landing capability requirements, understanding the atmosphere state and spacecraft sensitivities takes on heightened importance. MSL's guided entry trajectory differs significantly from recent Mars landers and includes events that generate different atmospheric sensitivities than past missions. The existence of these sensitivities and general advancement in the state of Mars atmospheric knowledge has led the MSL team to employ new atmosphere modeling techniques in addition to past practices. A joint EDL engineering and Mars atmosphere science and modeling team has been created to identify the key system sensitivities, gather available atmospheric data sets, develop relevant atmosphere models, and formulate methods to integrate atmosphere information into EDL performance assessments. The team consists of EDL engineers, project science staff, and Mars atmospheric scientists from a variety of institutions. This paper provides an overview of the system performance sensitivities that have driven the atmosphere modeling approach, discusses the atmosphere data sets and models employed by the team as a result of the identified sensitivities, and introduces the tools used to translate atmospheric knowledge into quantitative EDL performance assessments.

Comparison of Mars Aircraft Propulsion Systems

NASA Technical Reports Server (NTRS)

Colozza, Anthony J.

2003-01-01

The propulsion system is a critical aspect of the performance and feasibility of a Mars aircraft. Propulsion system mass and performance greatly influence the aircraft s design and mission capabilities. Various propulsion systems were analyzed to estimate the system mass necessary for producing 35N of thrust within the Mars environment. Three main categories of propulsion systems were considered: electric systems, combustion engine systems and rocket systems. Also, the system masses were compared for mission durations of 1, 2, and 4 h.

40 CFR 1036.801 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS CONTROL OF... the environment. Exhaust-gas recirculation (EGR) and turbochargers are not aftertreatment. Aircraft... operation of any part of the emission control system. Averaging set has the meaning given in § 1036.740...

Aquaculture research at the Conservation Fund Freshwater Institute

USDA-ARS?s Scientific Manuscript database

The Conservation Fund Freshwater Institute (TCFFI), working through cooperative agreements with the USDA Agriculture Research Service, has become a global leader in research and development of land-based closed containment water recirculation aquaculture systems (RAS) following three decades of appl...

Design and Development of a Methane Cryogenic Propulsion Stage for Human Mars Exploration

NASA Technical Reports Server (NTRS)

Percy, Thomas K.; Polsgrove, Tara; Turpin, Jason; Alexander, Leslie

2016-01-01

NASA is currently working on the Evolvabe Mars Campaign (EMC) study to outline transportation and mission options for human exploration of Mars. One of the key aspects of the EMC is leveraging current and planned near-term technology investments to build an affordable and evolvable approach to Mars exploration. This leveraging of investments includes the use of high-power Solar Electric Propulsion (SEP) systems, evolved from those currently under development in support of the Asteroid Redirect Mission (ARM), to deliver payloads to Mars. The EMC is considering several transportation options that combine solar electric and chemical propulsion technologies to deliver crew and cargo to Mars. In one primary architecture option, the SEP propulsion system is used to pre-deploy mission elements to Mars while a high-thrust chemical propulsion system is used to send crew on faster ballistic transfers between Earth and Mars. This high-thrust chemical system uses liquid oxygen - liquid methane main propulsion and reaction control systems integrated into the Methane Cryogenic Propulsion Stage (MCPS). Over the past year, there have been several studies completed to provide critical design and development information related to the MCPS. This paper is intended to provide a summary of these efforts. A summary of the current point of departure design for the MCPS is provided as well as an overview of the mission architecture and concept of operations that the MCPS is intended to support. To leverage the capabilities of solar electric propulsion to the greatest extent possible, the EMC architecture pre-deploys to Mars orbit the stages required for returning crew from Mars. While this changes the risk posture of the architecture, it can provide some mass savings by using higher-efficiency systems for interplanetary transfer. However, this does introduce significantly longer flight times to Mars which, in turn, increases the overall lifetime of the stages to as long as 2500 days. This unique aspect to the concept of operations introduces several challenges, specifically related to propellant storage and engine reliability. These challenges and some potential solutions are discussed. Specific focus is provided on two key technology areas; propulsion and cryogenic fluid management. In the area of propulsion development, the development of an integrated methane propulsion system that combines both main propulsion and reaction control is discussed. This includes an overview of potential development paths, areas where development for Mars applications are complementary to development efforts underway in other parts of the aerospace industry, and commonality between the MCPS methane propulsion applications and other Mars elements, including the Mars lander systems. This commonality is a key affordability aspect of the Evolvable Mars Campaign. A similar discussion is provided for cryogenic fluid management technologies including a discussion of how using cryo propulsion in the Mars transportation application not only provides performance benefits but also leverages decades of technology development investments made by NASA and its aerospace contractor community.

Contribution of seawater recirculation to submarine groundwater discharge and related nutrient fluxes in two tropical bays

NASA Astrophysics Data System (ADS)

Vautier, Camille; Dulaiova, Henrietta

2017-04-01

Hawaiian coastal waters suffer from excess terrestrial nutrient loading, most of which comes from submarine groundwater discharge (SGD). This study quantifies and distinguishes the role of the fresh terrestrial and tidally pumped salt water components of SGD into the nearshore zone of two reefs on the island of Oahu: Maunalua Bay and Kāneohe Bay. The two components of SGD are characterized using isotopic techniques, and the study mainly focuses on the less understood recirculation component. A two-step approach is implemented: first, a conceptual model of groundwater circulation is established; second, nutrient fluxes associated with seawater recirculation are quantified. Groundwater circulation through the beach berm is quantified and characterized using 222Rn and 224Ra activity measurements. Nutrient fluxes are obtained by coupling nutrient concentration measurements and discharge estimates. The isotopic signatures inform us about the influence of the tidal cycle on groundwater circulation. 222Rn, 224Ra, and δ18O isotopes are used to derive apparent ages of the infiltrated seawater and allow us to quantify recirculation rates. The method is also complemented with the use of silicate concentration as tracers of the recirculation process. The trends in apparent ages observed in pore water in Maunalua match previously published conceptual groundwater circulation models and show a sequentially aging pore water circulation loop. However, the ages obtained in Kāneohe suggest a different tidal pumping dynamic that lacks a circulation loop, perhaps resulting from the absence of freshwater discharge. Derived nutrient fluxes show that the autochthonous production of inorganic nitrogen and phosphorus that occurs during seawater recirculation has a significant impact on nutrient cycles in the nearshore areas of the bays. This result suggests that seawater recirculation should be taken into account in biogeochemical studies of coastal areas.

Removal of non-biodegradable organic matter from landfill leachates by adsorption.

PubMed

Rodríguez, J; Castrillón, L; Marañón, E; Sastre, H; Fernández, E

2004-01-01

Leachates produced at the La Zoreda landfill in Asturias, Spain, were recirculated through a simulated landfill pilot plant. Prior to recirculation, three loads of different amounts of Municipal Solid Waste (MSW) were added to the plant, forming in this way consecutive layers. When anaerobic digestion was almost completed, the leachates from the landfill were recirculated. After recirculation, a new load of MSW was added and two new recirculations were carried out. The organic load of the three landfill leachates recirculated through the anaerobic pilot plant decreased from initial values of 5108, 3782 and 2560 mg/l to values of between 1500 and 1600 mg/l. Despite achieving reductions in the organic load of the leachate, a residual organic load still remained that was composed of non-biodegradable organic constituents such as humic substances. Similar values of the chemical oxygen demand (COD) were obtained when the landfill leachate was treated by a pressurised anoxic-aerobic process followed by ultrafiltration. After recirculation through the pilot plant, physico-chemical treatment was carried out to reduce the COD of the leachate. The pH of the leachate was decreased to a value of 1.5 to precipitate the humic fraction, obtaining a reduction in COD of about 13.5%. The supernatant liquid was treated with activated carbon and different resins, XAD-8, XAD-4 and IR-120. Activated carbon presented the highest adsorption capacities, obtaining COD values for the treated leachate in the order of 200mg/l. Similar results were obtained when treating with activated carbon, the leachate from the biological treatment plant at the La Zoreda landfill; in this case without decreasing the pH.

An advanced anaerobic biofilter with effluent recirculation for phenol removal and methane production in treatment of coal gasification wastewater.

PubMed

Li, Yajie; Tabassum, Salma; Zhang, Zhenjia

2016-09-01

An advanced anaerobic biofilter (AF) was introduced for the treatment of coal gasification wastewater (CGW), and effluent recirculation was adopted to enhance phenol removal and methane production. The results indicated that AF was reliable in treating diluted CGW, while its efficiency and stability were seriously reduced when directly treating raw CGW. However, its performance could be greatly enhanced by effluent recirculation. Under optimal effluent recirculation of 0.5 to the influent, concentrations of chemical oxygen demand (COD) and total phenol in the effluent could reach as low as 234.0 and 14.2mg/L, respectively. Also, the rate of methane production reached 169.0mLCH4/L/day. Though CGW seemed to restrain the growth of anaerobic microorganisms, especially methanogens, the inhibition was temporary and reversible, and anaerobic bacteria presented strong tolerance. The activities of methanogens cultivated in CGW could quickly recover on feeding with glucose wastewater (GW). However, the adaptability of anaerobic bacteria to the CGW was very poor and the activity of methanogens could not be improved by long-term domestication. By analysis using the Haldane model, it was further confirmed that high effluent recirculation could result in high activity for hydrolytic bacteria and substrate affinity for toxic matters, but only suitable effluent recirculation could result in high methanogenic activity. Copyright © 2016. Published by Elsevier B.V.

Automated Electrostatics Environmental Chamber

NASA Technical Reports Server (NTRS)

Calle, Carlos; Lewis, Dean C.; Buchanan, Randy K.; Buchanan, Aubri

2005-01-01

The Mars Electrostatics Chamber (MEC) is an environmental chamber designed primarily to create atmospheric conditions like those at the surface of Mars to support experiments on electrostatic effects in the Martian environment. The chamber is equipped with a vacuum system, a cryogenic cooling system, an atmospheric-gas replenishing and analysis system, and a computerized control system that can be programmed by the user and that provides both automation and options for manual control. The control system can be set to maintain steady Mars-like conditions or to impose temperature and pressure variations of a Mars diurnal cycle at any given season and latitude. In addition, the MEC can be used in other areas of research because it can create steady or varying atmospheric conditions anywhere within the wide temperature, pressure, and composition ranges between the extremes of Mars-like and Earth-like conditions.

DEVELOPMENT AND DEPLOYMENT OF THE MOBILE ARM RETRIEVAL SYSTEM (MARS) - 12187

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

BURKE CA; LANDON MR; HANSON CE

Washington River Protection Solutions (WRPS) is developing and deploying Mobile Arm Retrieval System (MARS) technologies solutions to support retrieval of radioactive and chemical waste from underground single shell storage tanks (SST) located at the Hanford Site, which is near Richland, Washington. WRPS has developed the MARS using a standardized platform that is capable of deploying multiple retrieval technologies. To date, WRPS, working with their mentor-protege company, Columbia Energy and Environmental Services (CEES), has developed two retrieval mechanisms, MARS-Sluicing (MARS-S) and MARS-Vacuum (MARS-V). MARS-S uses pressurized fluids routed through spray nozzles to mobilize waste materials to a centrally located slurry pumpmore » (deployed in 2011). MARS-V uses pressurized fluids routed through an eductor nozzle. The eductor nozzle allows a vacuum to be drawn on the waste materials. The vacuum allows the waste materials to be moved to an in-tank vessel, then extracted from the SST and subsequently pumped to newer and safer double shell tanks (DST) for storage until the waste is treated for disposal. The MARS-S system is targeted for sound SSTs (i.e., non leaking tanks). The MARS-V is targeted for assumed leaking tanks or those tanks that are of questionable integrity. Both versions of MARS are beinglhave been developed in compliance with WRPS's TFC-PLN-90, Technology Development Management Plan [1]. TFC-PLN-90 includes a phased approach to design, testing, and ultimate deployment of new technologies. The MARS-V is scheduled to be deployed in tank 241-C-105 in late 2012.« less

Development and Deployment of the Mobile Arm Retrieval System (MARS) - 12187

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

Burke, Christopher A.; Landon, Matthew R.; Hanson, Carl E.

Washington River Protection Solutions (WRPS) is developing and deploying Mobile Arm Retrieval System (MARS) technologies solutions to support retrieval of radioactive and chemical waste from underground single shell storage tanks (SST) located at the Hanford Site, which is near Richland, Washington. WRPS has developed the MARS using a standardized platform that is capable of deploying multiple retrieval technologies. To date, WRPS, working with their mentor-protege company, Columbia Energy and Environmental Services (CEES), has developed two retrieval mechanisms, MARS-Sluicing (MARS-S) and MARS-Vacuum (MARS-V). MARS-S uses pressurized fluids routed through spray nozzles to mobilize waste materials to a centrally located slurry pumpmore » (deployed in 2011). MARS-V uses pressurized fluids routed through an eductor nozzle. The eductor nozzle allows a vacuum to be drawn on the waste materials. The vacuum allows the waste materials to be moved to an in-tank vessel, then extracted from the SST and subsequently pumped to newer and safer double shell tanks (DST) for storage until the waste is treated for disposal. The MARS-S system is targeted for sound SSTs (i.e., non leaking tanks). The MARS-V is targeted for assumed leaking tanks or those tanks that are of questionable integrity. Both versions of MARS are being/have been developed in compliance with WRPS's TFC-PLN-90, Technology Development Management Plan [1]. TFC-PLN-90 includes a phased approach to design, testing, and ultimate deployment of new technologies. The MARS-V is scheduled to be deployed in tank 241-C-105 in late 2012. (authors)« less

DEVELOPMENT AND DEPLOYMENT OF THE MOBILE ARM RETRIEVAL SYSTEM (MARS) - 12187

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

BURKE CA; LANDON MR; HANSON CE

Washington River Protection Solutions (WRPS) is developing and deploying Mobile Arm Retrieval System (MARS) technologies solutions to support retrieval of radioactive and chemical waste from underground single shell storage tanks (SST) located at the Hanford Site, which is near Richland, Washington. WRPS has developed the MARS using a standardized platform that is capable of deploying multiple retrieval technologies. To date, WRPS, working with their mentor-protege company, Columbia Energy and Environmental Services (CEES), has developed two retrieval mechanisms, MARS-Sluicing (MARS-S) and MARS-Vacuum (MARS-V). MARS-S uses pressurized fluids routed through spray nozzles to mobilize waste materials to a centrally located slurry pumpmore » (deployed in 2011). MARS-V uses pressurized fluids routed through an eductor nozzle. The eductor nozzle allows a vacuum to be drawn on the waste materials. The vacuum allows the waste materials to be moved to an in-tank vessel, then extracted from the SST and subsequently pumped to newer and safer double shell tanks (DST) for storage until the waste is treated for disposal. The MARS-S system is targeted for sound SSTs (i.e., non leaking tanks). The MARS-V is targeted for assumed leaking tanks or those tanks that are of questionable integrity. Both versions of MARS are being/have been developed in compliance with WRPS's TFC-PLN-90, Technology Development Management Plan. TFC-PLN-90 includes a phased approach to design, testing, and ultimate deployment of new technologies. The MARS-V is scheduled to be deployed in tank 241-C-105 in late 2012.« less

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

DOEpatents

Kolb, Gregory J [Albuquerque, NM

2012-02-07

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

Recirculation zone length in renal artery is affected by flow spirality and renal-to-aorta flow ratio.

PubMed

Javadzadegan, Ashkan; Fulker, David; Barber, Tracie

2017-07-01

Haemodynamic perturbations such as flow recirculation zones play a key role in progression and development of renal artery stenosis, which typically originate at the aorta-renal bifurcation. The spiral nature of aortic blood flow, division of aortic blood flow in renal artery as well as the exercise conditions have been shown to alter the haemodynamics in both positive and negative ways. This study focuses on the combinative effects of spiral component of blood flow, renal-to-aorta flow ratio and the exercise conditions on the size and distribution of recirculation zones in renal branches using computational fluid dynamics technique. Our findings show that the recirculation length was longest when the renal-to-aorta flow ratio was smallest. Spiral flow and exercise conditions were found to be effective in reducing the recirculation length in particular in small renal-to-aorta flow ratios. These results support the hypothesis that in renal arteries with small flow ratios where a stenosis is already developed an artificially induced spiral flow within the aorta may decelerate the progression of stenosis and thereby help preserve kidney function.

Wall shear stress characterization of a 3D bluff-body separated flow

NASA Astrophysics Data System (ADS)

Fourrié, Grégoire; Keirsbulck, Laurent; Labraga, Larbi

2013-10-01

Efficient flow control strategies aimed at reducing the aerodynamic drag of road vehicles require a detailed knowledge of the reference flow. In this work, the flow around the rear slanted window of a generic car model was experimentally studied through wall shear stress measurements using an electrochemical method. The mean and fluctuating wall shear stress within the wall impact regions of the recirculation bubble and the main longitudinal vortex structures which develop above the rear window are presented. Correlations allow a more detailed characterization of the recirculation phenomenon within the separation bubble. In the model symmetry plane the recirculation structure compares well with simpler 2D configurations; specific lengths, flapping motion and shedding of large-scale vortices are observed, these similarities diminish when leaving the middle plane due to the strong three-dimensionality of the flow. A specific attention is paid to the convection processes occurring within the recirculation: a downstream convection velocity is observed, in accordance with 2D recirculations from the literature, and an upstream convection is highlighted along the entire bubble length which has not been underlined in some previous canonical configurations.

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

PubMed

Moroni, Monica; Cicci, Agnese; Bravi, Marco

2014-04-01

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. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of sludge recirculation rate and mixing time on performance of a prototype single-stage anaerobic digester for conversion of food wastes to biogas and energy recovery.

PubMed

Ratanatamskul, Chavalit; Saleart, Tawinan

2016-04-01

Food wastes have been recognized as the largest waste stream and accounts for 39.25 % of total municipal solid waste in Thailand. Chulalongkorn University has participated in the program of in situ energy recovery from food wastes under the Ministry of Energy (MOE), Thailand. This research aims to develop a prototype single-stage anaerobic digestion system for biogas production and energy recovery from food wastes inside Chulalongkorn University. Here, the effects of sludge recirculation rate and mixing time were investigated as the main key parameters for the system design and operation. From the results obtained in this study, it was found that the sludge recirculation rate of 100 % and the mixing time of 60 min per day were the most suitable design parameters to achieve high efficiencies in terms of chemical oxygen demand (COD), total solids (TS), and total volatile solid (TVS) removal and also biogas production by this prototype anaerobic digester. The obtained biogas production was found to be 0.71 m(3)/kg COD and the composition of methane was 61.6 %. Moreover, the efficiencies of COD removal were as high as 82.9 % and TVS removal could reach 83.9 % at the optimal condition. Therefore, the developed prototype single-stage anaerobic digester can be highly promising for university canteen application to recover energy from food wastes via biogas production.

Recirculating 1-K-Pot for Pulse-Tube Cryostats

NASA Technical Reports Server (NTRS)

Paine, Christopher T.; Naylor, Bret J.; Prouve, Thomas

2013-01-01

A paper describes a 1-K-pot that works with a commercial pulse tube cooler for astrophysics instrumentation testbeds that require temperatures <1.7 K. Pumped liquid helium-4 cryostats were commonly used to achieve this temperature. However, liquid helium-4 cryostats are being replaced with cryostats using pulse tube coolers. The closed-cycle 1K-pot system for the pulse tube cooler requires a heat exchanger on the pulse tube, a flow restriction, pump-out line, and pump system that recirculates helium-4. The heat exchanger precools and liquefies helium- 4 gas at the 2.5 to 3.5 K pulse tube cold head. This closed-cycle 1-K-pot system was designed to work with commercially available laboratory pulse tube coolers. It was built using common laboratory equipment such as stainless steel tubing and a mechanical pump. The system is self-contained and requires only common wall power to operate. The lift of 15 mW at 1.1 K and base temperature of 0.97 K are provided continuously. The system can be scaled to higher heat lifts of .30 to 50 mW if desired. Ground-based telescopes could use this innovation to improve the efficiency of existing cryo

Thermal Analysis of of Near-Isothermal Compressed Gas Energy Storage System

DOE PAGES

Odukomaiya, Adewale; Abu-Heiba, Ahmad; Gluesenkamp, Kyle R.; ...

2016-01-01

In this paper, alternative system configurations for a novel Ground-Level Integrated Diverse Energy Storage (GLIDES) system, which can store energy via input of electricity and heat and deliver dispatchable electricity, is presented. The proposed system is low-cost and hybridizes compressed air and pumped hydro storage approaches that will allow for the off-peak storage of intermittent renewable energy for use during peak times. This study reveals that implementing direct-contact low grade heat exchange via sprayed falling droplets to cool the gas during charging (compression) and warm the gas during discharging (expansion) can be achieved through a secondary recirculating loop of liquid.more » This study shows that if the recirculating liquid loop is pre-conditioned with waste-heat prior to spraying during gas expansion and considering all the round trip conversion losses from standard 120 V 60 HZ electricity input and output with utilization of low grade heat at 90 C the alternative system design leads to a 16% boost in round trip efficiency of the electricity storage to elec = 82% with an energy density of ED = 3.59 MJ/m3.« less

Multivariate Analysis, Retrieval, and Storage System (MARS). Volume 1: MARS System and Analysis Techniques

NASA Technical Reports Server (NTRS)

Hague, D. S.; Vanderberg, J. D.; Woodbury, N. W.

1974-01-01

A method for rapidly examining the probable applicability of weight estimating formulae to a specific aerospace vehicle design is presented. The Multivariate Analysis Retrieval and Storage System (MARS) is comprised of three computer programs which sequentially operate on the weight and geometry characteristics of past aerospace vehicles designs. Weight and geometric characteristics are stored in a set of data bases which are fully computerized. Additional data bases are readily added to the MARS system and/or the existing data bases may be easily expanded to include additional vehicles or vehicle characteristics.

Manned Mars mission crew factors

NASA Technical Reports Server (NTRS)

Santy, Patricia A.

1986-01-01

Crew factors include a wide range of concerns relating to the human system and its role in a Mars mission. There are two important areas which will play a large part in determining the crew for a Mars mission. The first relates to the goals and priorities determined for such a vast endeavor. The second is the design of the vehicle for the journey. The human system cannot be separated from the other systems in that vehicle. In fact it will be the human system which drives the development of many of the technical breakthroughs necessary to make a Mars mission successful. As much as possible, the engineering systems must adapt to the needs of the human system and its individual components.

40 CFR 125.84 - As an owner or operator of a new facility, what must I do to comply with this subpart?

Code of Federal Regulations, 2011 CFR

2011-07-01

... ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) WATER PROGRAMS CRITERIA AND STANDARDS FOR THE NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM Requirements Applicable to Cooling Water Intake Structures for New Facilities... that which can be attained by a closed-cycle recirculating cooling water system; (2) You must design...

COST EFFECTIVE VOC EMISSION CONTROL STARTEGIES FOR MILITARY, AEROSPACE,AND INDUSTRIAL PAINT SPRAY BOOTH OPERATIONS: COMBINING IMPROVED VENTILATION SYSTEMS WITH INNOVATIVE, LOW COST EMISSION CONTROL TECHNOLOGIES

EPA Science Inventory

The paper describes a full-scale demonstration program in which several paint booths were modified for recirculation ventilation; the booth exhaust streams are vented to an innovative volatile organic compound (VOC) emission control system having extremely low operating costs. ...

76 FR 57696 - Approval and Promulgation of Implementation Plans; New York; Motor Vehicle Enhanced Inspection...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-16

..., oxygen sensor, heated oxygen sensor, and exhaust gas recirculation or EGR system) while the remaining...: Emissions Test Type: light-duty vehicles ( 18,000 lbs. ECD Checks for or gas cap checks). GVWR), 25 MYs old..., CAT, EVAP system disablement. Gas Cap: NYTEST Pressure Test. Note: The reader is referred to the...

Method and apparatus for thermal power generation

DOEpatents

Mangus, James D.

1979-01-01

A method and apparatus for power generation from a recirculating superheat-reheat circuit with multiple expansion stages which alleviates complex control systems and minimizes thermal cycling of system components, particularly the reheater. The invention includes preheating cold reheat fluid from the first expansion stage prior to its entering the reheater with fluid from the evaporator or drum component.

Growth and fillet quality attributes of five genetic strains of rainbow trout (Oncorhynchus mykiss) reared in a partial water reuse system and harvested at different sizes

USDA-ARS?s Scientific Manuscript database

Genetics and environment can interact to influence fish growth performance and product quality attributes. Interaction in recirculating aquaculture systems (RAS) makes selection of fish strain and harvest sizes critical for optimizing fish quality. Definition of growth performance and quality outcom...

Use of recirculating aquaculture systems to increase production and quality of hatchery reared juvenile red drum for marine stock enhancement

USDA-ARS?s Scientific Manuscript database

The abundance of economically important marine sportfish has declined in Florida’s waters due to factors such as over-fishing and critical habitat disturbance. Hatchery production and enhancement stocking has traditionally been used in freshwater systems as a means of mitigating for effects such as ...

Temporal nitrous oxide emissions from beef cattle feedlot manure following a simulated rainfall event

USDA-ARS?s Scientific Manuscript database

A pilot-scale, recirculating-flow-through, non-steady-state (RFT-NSS) chamber system was designed for quantifying nitrous oxide (N2O) emissions from simulated open-lot beef cattle feedlot pens. The system employed five 1 square meter steel pans. A lid was placed systematically on each pan and heads...

A new mechanism for periodic bursting of the recirculation region in the flow through a sudden expansion in a circular pipe

NASA Astrophysics Data System (ADS)

Lebon, Benoit; Nguyen, Minh Quan; Peixinho, Jorge; Shadloo, Mostafa Safdari; Hadjadj, Abdellah

2018-03-01

We report the results of a combined experimental and numerical study of specific finite-amplitude disturbances for transition to turbulence in the flow through a circular pipe with a sudden expansion. The critical amplitude thresholds for localized turbulent patch downstream of the expansion scale with the Reynolds number with a power law exponent of -2.3 for experiments and -2.8 for simulations. A new mechanism for the periodic bursting of the recirculation region is uncovered where the asymmetric recirculation flow develops a periodic dynamics: a secondary recirculation breaks the symmetry along the pipe wall and bursts into localized turbulence, which travels downstream and relaminarises. Flow visualizations show a simple flow pattern of three waves forming, growing, and bursting.

MW-Class Electric Propulsion System Designs for Mars Cargo Transport

NASA Technical Reports Server (NTRS)

Gilland, James H.; LaPointe, Michael R.; Oleson, Steven; Mercer, Carolyn; Pencil, Eric; Maosn, Lee

2011-01-01

Multi-kilowatt electric propulsion systems are well developed and have been used on commercial and military satellites in Earth orbit for several years. Ion and Hall thrusters have also propelled robotic spacecraft to encounters with asteroids, the Moon, and minor planetary bodies within the solar system. High power electric propulsion systems are currently being considered to support piloted missions to near earth asteroids, as cargo transport for sustained lunar or Mars exploration, and for very high-power piloted missions to Mars and the outer planets. Using NASA Mars Design Architecture 5.0 as a reference, a preliminary parametric analysis was performed to determine the suitability of a nuclear powered, MW-class electric propulsion system for Mars cargo transport. For this initial analysis, high power 100-kW Hall thrusters and 250-kW VASIMR engines were separately evaluated to determine optimum vehicle architecture and estimated performance. The DRA 5.0 cargo mission closed for both propulsion options, delivering a 100 t payload to Mars orbit and reducing the number of heavy lift launch vehicles from five in the baseline DRA 5.0 architecture to two using electric propulsion. Under an imposed single engine-out mission success criteria, the VASIMR system took longer to reach Mars than did the Hall system, arising from the need to operate the VASIMR thrusters in pairs during the spiral out from low Earth orbit.

MARS PATHFINDER PYRO SYSTEMS SWITCHING ACTIVITY

NASA Technical Reports Server (NTRS)

1996-01-01

The Mars Pathfinder lander is subjected to a electrical and functional tests of its pyrotechic petal deployer system by Jet Propulsion Laboratory (JPL) engineers and technicians in KSC's Spacecraft Assembly and Encapsulation Facility (SAEF-2). In the background is the Pathfinder cruise stage, which the lander will be mated to once its functional tests are complete. The lander will remain attached to this stage during its six-to-seven-month journey to Mars. When the lander touches down on the surface of Mars next year, the pyrotechnic system will deploy its three petals open like a flower and allow the Sojourner autonomous rover to explore the Martian surface. The Mars Pathfinder is scheduled for launch aboard a Delta II expendable launch vehicle on Dec. 2, the beginning of a 24-day launch period. JPL is managing the Mars Pathfinder project for NASA.

Trials advance low-salinity culture of cobia, pompano, other species

USDA-ARS?s Scientific Manuscript database

A collaborative effort between the Agricultural Research Service of USDA and Harbor Branch Oceanographic Institute of Florida Atlantic University, which was established to develop technologies for rearing marine fish in low-cost, energy efficient low-salinity recirculating aquaculture systems (RAS) ...

Trials advance low-salinity culture of Cobia, Pompano, and other species

USDA-ARS?s Scientific Manuscript database

An ongoing collaborative research effort between scientists of the USDA Agricultural Research Service and aquaculture researchers of the Harbor Branch Oceanographic Institute at Florida Atlantic University to develop technologies for rearing fish in low salinity recirculating aquaculture systems is ...

How research is fueling the RAS boom

USDA-ARS?s Scientific Manuscript database

The Conservation Fund’s Freshwater Institute has been researching water recirculating aquaculture system (RAS) technologies and practices for salmonids for nearly 30 years using strong funding support from the U.S. Department of Agriculture’s Agricultural Research Service. These early efforts to pio...

40 CFR 86.094-25 - Maintenance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... sensors (including oxygen sensor if installed) and actuators. (D) Exhaust gas recirculation system..., and for 1985 and Later Model Year New Gasoline Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas... trucks and heavy-duty engines, the adjustment, cleaning, repair, or replacement of the oxygen sensor...

40 CFR 86.094-25 - Maintenance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... sensors (including oxygen sensor if installed) and actuators. (D) Exhaust gas recirculation system..., and for 1985 and Later Model Year New Gasoline Fueled, Natural Gas-Fueled, Liquefied Petroleum Gas... trucks and heavy-duty engines, the adjustment, cleaning, repair, or replacement of the oxygen sensor...

Inland marine fish culture in low-salinity recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

Expansion of marine aquaculture is challenged by the high cost and limited availability of coastal land and water resources, effluent concerns, high production costs, restricted growing seasons, lack of quality seedstock, and inadequate regulatory and permitting processes. Many of these constraints...

40 CFR 418.15 - Standards of performance for new sources.

Code of Federal Regulations, 2012 CFR

2012-07-01

...) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Phosphate Subcategory... calcium sulfate storage pile runoff facility operated separately or in combination with a water recirculation system designed, constructed and operated to maintain a surge capacity equal to the runoff from...

40 CFR 418.15 - Standards of performance for new sources.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Phosphate Subcategory... calcium sulfate storage pile runoff facility operated separately or in combination with a water recirculation system designed, constructed and operated to maintain a surge capacity equal to the runoff from...

40 CFR 418.15 - Standards of performance for new sources.

Code of Federal Regulations, 2013 CFR

2013-07-01

...) EFFLUENT GUIDELINES AND STANDARDS FERTILIZER MANUFACTURING POINT SOURCE CATEGORY Phosphate Subcategory... calcium sulfate storage pile runoff facility operated separately or in combination with a water recirculation system designed, constructed and operated to maintain a surge capacity equal to the runoff from...

Mars ISRU for Production of Mission Critical Consumables - Options, Recent Studies, and Current State of the Art

NASA Technical Reports Server (NTRS)

Sanders, G. B.; Paz, A.; Oryshchyn, L.; Araghi, K.; Muscatello, A.; Linne, D.; Kleinhenz, J.; Peters, T.

2015-01-01

In 1978, a ground breaking paper titled, "Feasibility of Rocket Propellant Production on Mars" by Ash, Dowler, and Varsi discussed how ascent propellants could be manufactured on the Mars surface from carbon dioxide collected from the atmosphere to reduce launch mass. Since then, the concept of making mission critical consumables such as propellants, fuel cell reactants, and life support consumables from local resources, commonly known as In-Situ Resource Utilization (ISRU), for robotic and human missions to Mars has been studied many times. In the late 1990's, NASA initiated a series of Mars Human Design Reference Missions (DRMs), the first of which was released in 1997. These studies primarily focused on evaluating the impact of making propellants on Mars for crew ascent to Mars orbit, but creating large caches of life support consumables (water & oxygen) as a backup for regenerative life support systems for long-duration surface stays (>500 days) was also considered in Mars DRM 3.0. Until science data from the Mars Odyssey orbiter and subsequent robotic missions revealed that water may be widely accessable across the surface of Mars, prior Mars ISRU studies were limited to processing Mars atmospheric resources (carbon dioxide, nitrogen, argon, oxygen, and water vapor). In December 2007, NASA completed the Mars Human Design Reference Architecture (DRA) 5.0 study which considered water on Mars as a potential resource for the first time in a human mission architecture. While knowledge of both water resources on Mars and the hardware required to excavate and extract the water were very preliminary, the study concluded that a significant reduction in mass and significant enhancements to the mission architecture were possible if Mars water resources were utilized. Two subsequent Mars ISRU studies aimed at reexamining ISRU technologies, processing options, and advancements in the state-of-the-art since 2007 and to better understand the volume and packaging associated with Mars ISRU systems further substantiated the preliminary results from the Mars DRA 5.0 study. This paper will provide an overview of Mars ISRU consumable production options, the analyses, results, and conclusions from the Mars DRA 5.0 (2007), Mars Collaborative (2013), and Mars ISRU Payload for the Supersonic Retro Propulsion (2014) mission studies, and the current state-of-the-art of Mars ISRU technologies and systems. The paper will also briefly discuss the mission architectural implications associated with Mars resource and ISRU processing options.

Mars Lander/Rover vehicle development: An advanced space design project for USRA and NASA/OAST

NASA Technical Reports Server (NTRS)

1987-01-01

The accomplishments of the Utah State University (USU) Mars Lander/Rover (MLR) design class during the Winter Quarter are delineated and explained. Environment and trajectory, ground systems, balloon system, and payload system are described. Results from this effort will provide a valid and useful basis for further studies of Mars exploratory vehicles.

Mars Ascent Vehicle Test Requirements and Terrestrial Validation

NASA Technical Reports Server (NTRS)

Dankanich, John W.; Cathey, Henry M.; Smith, David A.

2011-01-01

The Mars robotic sample return mission has been a potential flagship mission for NASA s science mission directorate for decades. The Mars Exploration Program and the planetary science decadal survey have highlighted both the science return of the Mars Sample Return mission, but also the need for risk reduction through technology development. One of the critical elements of the MSR mission is the Mars Ascent Vehicle, which must launch the sample from the surface of Mars and place it into low Mars orbit. The MAV has significant challenges to overcome due to the Martian environments and the Entry Descent and Landing system constraints. Launch vehicles typically have a relatively low success probability for early flights, and a thorough system level validation is warranted. The MAV flight environments are challenging and in some cases impossible to replicate terrestrially. The expected MAV environments have been evaluated and a first look of potential system test options has been explored. The terrestrial flight requirements and potential validation options are presented herein.

Telecommunications and navigation systems design for manned Mars exploration missions

NASA Astrophysics Data System (ADS)

Hall, Justin R.; Hastrup, Rolf C.

1989-06-01

This paper discusses typical manned Mars exploration needs for telecommunications, including preliminary navigation support functions. It is a brief progress report on an ongoing study program within the current NASA JPL Deep Space Network (DSN) activities. A typical Mars exploration case is defined, and support approaches comparing microwave and optical frequency performance for both local in situ and Mars-earth links are described. Optical telecommunication and navigation technology development opportunities in a Mars exploration program are also identified. A local Mars system telecommunication relay and navigation capability for service support of all Mars missions has been proposed as part of an overall solar system communications network. The effects of light-time delay and occultations on real-time mission decision-making are discussed; the availability of increased local mass data storage may be more important than increasing peak data rates to earth. The long-term frequency use plan will most likely include a mix of microwave, millimeter-wave and optical link capabilities to meet a variety of deep space mission needs.

Telecommunications and navigation systems design for manned Mars exploration missions

NASA Technical Reports Server (NTRS)

Hall, Justin R.; Hastrup, Rolf C.

1989-01-01

This paper discusses typical manned Mars exploration needs for telecommunications, including preliminary navigation support functions. It is a brief progress report on an ongoing study program within the current NASA JPL Deep Space Network (DSN) activities. A typical Mars exploration case is defined, and support approaches comparing microwave and optical frequency performance for both local in situ and Mars-earth links are described. Optical telecommunication and navigation technology development opportunities in a Mars exploration program are also identified. A local Mars system telecommunication relay and navigation capability for service support of all Mars missions has been proposed as part of an overall solar system communications network. The effects of light-time delay and occultations on real-time mission decision-making are discussed; the availability of increased local mass data storage may be more important than increasing peak data rates to earth. The long-term frequency use plan will most likely include a mix of microwave, millimeter-wave and optical link capabilities to meet a variety of deep space mission needs.

Design and Development of a Methane Cryogenic Propulsion Stage for Human Mars Exploration

NASA Technical Reports Server (NTRS)

Percy, Thomas K.; Polsgrove, Tara; Turpin, Jason; Alexander, Leslie

2016-01-01

NASA is currently working on the Evolvabe Mars Campaign (EMC) study to outline transportation and mission options for human exploration of Mars. One of the key aspects of the EMC is leveraging current and planned near-term technology investments to build an affordable and evolvable approach to Mars exploration. This leveraging of investments includes the use of high-power Solar Electric Propulsion (SEP) systems evolved from those currently under development in support of the Asteroid Redirect Mission to deliver payloads to Mars. The EMC is considering several transportation options that combine solar electric and chemical propulsion technologies to deliver crew and cargo to Mars. In one primary architecture option, the SEP propulsion system is used to pre-deploy mission elements to Mars while a high-thrust chemical propulsion system is used to send crew on faster ballistic transfers between Earth and Mars. This high-thrust chemical system uses liquid oxygen - liquid methane main propulsion and reaction control systems integrated into the Methane Cryogenic Propulsion Stage (MCPS). Over the past year, there have been several studies completed to provide critical design and development information related to the MCPS. This paper is intended to provide a summary of these efforts. A summary of the current point of departure design for the MCPS is provided as well as an overview of the mission architecture and concept of operations that the MCPS is intended to support. To leverage the capabilities of solar electric propulsion to the greatest extent possible, the EMC architecture pre-deploys the required stages for returning crew from Mars. While this changes the risk posture of the architecture, it provides mass savings by using higher-efficiency systems for interplanetary transfer. However, this does introduce significantly longer flight times to Mars which, in turn, increases the overall lifetime of the stages to as long as 3000 days. This unique aspect to the concept of operations introduces several challenges, specifically related to propellant storage and engine reliability. These challenges and some potential solutions are discussed. Specific focus is provided on two key technology areas; propulsion and cryogenic fluid management. In the area of propulsion development, the development of an integrated methane propulsion system that combines both main propulsion and reaction control is discussed. This includes an overview of potential development paths, areas where development for Mars applications are complementary to development efforts underway in other parts of the aerospace industry, and commonality between the MCPS methane propulsion applications and other Mars elements, including the Mars lander systems. This commonality is a key affordability aspect of the Evolvable Mars Campaign. A similar discussion is provided for cryogenic fluid management technologies including a discussion of how using cryo-propulsion in the Mars transportation application not only provides performance benefits but also leverages decades of technology development investments made by NASA and its aerospace contractor community.

The space exploration initiative

NASA Technical Reports Server (NTRS)

Priest, Pete

1991-01-01

A number of view graph charts are presented which outline the presentation. Outlined are reasons for going to Mars, why it is necessary to go to the Moon first, and the presidential decision on the space exploration initiative. Other representative charts are entitled: Lunar transportation system requirement drivers; Mars transportation system requirement drivers; National space policy goals; Exploration hardware needed; Mars mission profile; Science on the Moon and Mars; and Two independent reviews.

The effects of leachate recirculation with supplemental water addition on methane production and waste decomposition in a simulated tropical landfill.

PubMed

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

2006-10-01

In order to increase methane production efficiency, leachate recirculation is applied in landfills to increase moisture content and circulate organic matter back into the landfill cell. In the case of tropical landfills, where high temperature and evaporation occurs, leachate recirculation may not be enough to maintain the moisture content, therefore supplemental water addition into the cell is an option that could help stabilize moisture levels as well as stimulate biological activity. The objectives of this study were to determine the effects of leachate recirculation and supplemental water addition on municipal solid waste decomposition and methane production in three anaerobic digestion reactors. Anaerobic digestion with leachate recirculation and supplemental water addition showed the highest performance in terms of cumulative methane production and the stabilization period time required. It produced an accumulated methane production of 54.87 l/kg dry weight of MSW at an average rate of 0.58 l/kg dry weight/d and reached the stabilization phase on day 180. The leachate recirculation reactor provided 17.04 l/kg dry weight at a rate of 0.14l/kg dry weight/d and reached the stabilization phase on day 290. The control reactor provided 9.02 l/kg dry weight at a rate of 0.10 l/kg dry weight/d, and reached the stabilization phase on day 270. Increasing the organic loading rate (OLR) after the waste had reached the stabilization phase made it possible to increase the methane content of the gas, the methane production rate, and the COD removal. Comparison of the reactors' efficiencies at maximum OLR (5 kgCOD/m(3)/d) in terms of the methane production rate showed that the reactor using leachate recirculation with supplemental water addition still gave the highest performance (1.56 l/kg dry weight/d), whereas the leachate recirculation reactor and the control reactor provided 0.69 l/kg dry weight/d and 0.43 l/kg dry weight/d, respectively. However, when considering methane composition (average 63.09%) and COD removal (average 90.60%), slight differences were found among these three reactors.

Geographic Information Systems and Martian Data: Compatibility and Analysis

NASA Technical Reports Server (NTRS)

Jones, Jennifer L.

2005-01-01

Planning future landed Mars missions depends on accurate, informed data. This research has created and used spatially referenced instrument data from NASA missions such as the Thermal Emission Imaging System (THEMIS) on the Mars Odyssey Orbiter and the Mars Orbital Camera (MOC) on the Mars Global Surveyor (MGS) Orbiter. Creating spatially referenced data enables its use in Geographic Information Systems (GIS) such as ArcGIS. It has then been possible to integrate this spatially referenced data with global base maps and build and populate location based databases that are easy to access.

Optimization and evaluation of a bottom substrate denitrification tank for nitrate removal from a recirculating aquaculture system.

PubMed

Pungrasmi, Wiboonluk; Playchoom, Cholticha; Powtongsook, Sorawit

2013-08-01

A bottom substrate denitrification tank for a recirculating aquaculture system was developed. The laboratory scale denitrification tank was an 8 L tank (0.04 m2 tank surface area), packed to a depth of 5 cm with a bottom substrate for natural denitrifying bacteria. An aquarium pump was used for gentle water mixing in the tank; the dissolved oxygen in the water was maintained in aerobic conditions (e.g. > 2 mg/L) while anoxic conditions predominated only at the bottom substrate layer. The results showed that, among the four substrates tested (soil, sand, pumice stone and vermiculite), pumice was the most preferable material. Comparing carbon supplementation using methanol and molasses, methanol was chosen as the carbon source because it provided a higher denitrification rate than molasses. When methanol was applied at the optimal COD:N ratio of 5:1, a nitrate removal rate of 4591 +/- 133 mg-N/m2 tank bottom area/day was achieved. Finally, nitrate removal using an 80 L denitrification tank was evaluated with a 610 L recirculating tilapia culture system. Nitrate treatment was performed by batch transferring high nitrate water from the nitrification tank into the denitrification tank and mixing with methanol at a COD:N ratio of 5:1. The results from five batches of nitrate treatment revealed that nitrate was successfully removed from water without the accumulation of nitrite and ammonia. The average nitrate removal efficiency was 85.17% and the average denitrification rate of the denitrification tank was 6311 +/- 945 mg-N/m2 tank bottom area/day or 126 +/- 18 mg-N/L of pumice packing volume/day.

Modeled Effectiveness of Ventilation with Contaminant Control Devices on Indoor Air Quality in a Swine Farrowing Facility

PubMed Central

Anthony, T. Renée; Altmaier, Ralph; Park, Jae Hong; Peters, Thomas M.

2016-01-01

Because adverse health effects experienced by swine farm workers in concentrated animal feeding operations (CAFOs) have been associated with exposure to dust and gases, efforts to reduce exposures are warranted, particularly in winter seasons when exposures increase due to decreased ventilation. Simulation of air quality and operating costs for ventilating swine CAFO, including treating and recirculating air through a farrowing room, was performed using mass and energy balance equations over a 90-day winter season. System operation required controlling heater operation to achieve room temperatures optimal to ensure animal health (20 to 22.5°C). Five air pollution control devices, four room ventilation rates, and five recirculation patterns were examined. Inhalable dust concentrations were easily reduced using standard industrial air pollution control devices, including a cyclone, filtration, and electrostatic precipitator. Operating ventilation systems at 0.94 m3 s−1 (2000 cfm) with 75 to 100% recirculation of treated air from cyclone, electrostatic precipitator, and shaker dust filtration system achieves adequate particle control with operating costs under $1.00 per pig produced ($0.22 to 0.54), although carbon dioxide (CO2) concentrations approach 2000 ppm using in-room ventilated gas fired heaters. In no simulation were CO2 concentrations below industry recommended concentrations (1540 ppm), but alternative heating devices could reduce CO2 to acceptable concentrations. While this investigation does not represent all production swine farrowing barns, which differ in characteristics including room dimensions and swine occupancy, the simulation model and ventilation optimization methods can be applied to other production sites. This work shows that ventilation may be a cost-effective control option in the swine industry to reduce exposures. PMID:24433305

Algal Foams Applied in Fixed-Bed Process for Lead(II) Removal Using Recirculation or One-Pass Modes

PubMed Central

Wang, Shengye; Vincent, Thierry; Faur, Catherine; Guibal, Eric

2017-01-01

The incorporation of brown algae into biopolymer beads or foams for metal sorption has been previously reported. However, the direct use of these biomasses for preparing foams is a new approach. In this study, two kinds of porous foams were prepared by ionotropic gelation using algal biomass (AB, Laminaria digitata) or alginate (as the reference) and applied for Pb(II) sorption. These foams (manufactured as macroporous discs) were packed in filtration holders (simulating fixed-bed column) and the system was operated in either a recirculation or a one-pass mode. Sorption isotherms, uptake kinetics and sorbent reuse were studied in the recirculation mode (analogous to batch system). In the one-pass mode (continuous fixed-bed system), the influence of parameters such as flow rate, feed metal concentration and bed height were investigated on both sorption and desorption. In addition, the effect of Cu(II) on Pb(II) recovery from binary solutions was also studied in terms of both sorption and desorption. Sorption isotherms are well fitted by the Langmuir equation while the pseudo-second order rate equation described well both sorption and desorption kinetic profiles. The study of material regeneration confirms that the reuse of the foams was feasible with a small mass loss, even after 9 cycles. In the one-pass mode, for alginate foams, a slower flow rate led to a smaller saturation volume, while the effect of flow rate was less marked for AB foams. Competitive study suggests that the foams have a preference for Pb(II) over Cu(II) but cannot selectively remove Pb(II) from the binary solution. PMID:29039806

Modeled effectiveness of ventilation with contaminant control devices on indoor air quality in a swine farrowing facility.

PubMed

Anthony, T Renée; Altmaier, Ralph; Park, Jae Hong; Peters, Thomas M

2014-01-01

Because adverse health effects experienced by swine farm workers in concentrated animal feeding operations (CAFOs) have been associated with exposure to dust and gases, efforts to reduce exposures are warranted, particularly in winter seasons when exposures increase due to decreased ventilation. Simulation of air quality and operating costs for ventilating swine CAFO, including treating and recirculating air through a farrowing room, was performed using mass and energy balance equations over a 90-day winter season. System operation required controlling heater operation to achieve room temperatures optimal to ensure animal health (20 to 22.5 °C). Five air pollution control devices, four room ventilation rates, and five recirculation patterns were examined. Inhalable dust concentrations were easily reduced using standard industrial air pollution control devices, including a cyclone, filtration, and electrostatic precipitator. Operating ventilation systems at 0.94 m3 s(-1) (2000 cfm) with 75 to 100% recirculation of treated air from cyclone, electrostatic precipitator, and shaker dust filtration system achieves adequate particle control with operating costs under $1.00 per pig produced ($0.22 to 0.54), although carbon dioxide (CO2) concentrations approach 2000 ppm using in-room ventilated gas fired heaters. In no simulation were CO2 concentrations below industry recommended concentrations (1540 ppm), but alternative heating devices could reduce CO2 to acceptable concentrations. While this investigation does not represent all production swine farrowing barns, which differ in characteristics including room dimensions and swine occupancy, the simulation model and ventilation optimization methods can be applied to other production sites. This work shows that ventilation may be a cost-effective control option in the swine industry to reduce exposures.

Perspective for Aquaponic Systems: “Omic” Technologies for Microbial Community Analysis

PubMed Central

Munguia-Fragozo, Perla; Alatorre-Jacome, Oscar; Rico-Garcia, Enrique; Cruz-Hernandez, Andres; Ocampo-Velazquez, Rosalia V.; Garcia-Trejo, Juan F.; Guevara-Gonzalez, Ramon G.

2015-01-01

Aquaponics is the combined production of aquaculture and hydroponics, connected by a water recirculation system. In this productive system, the microbial community is responsible for carrying out the nutrient dynamics between the components. The nutrimental transformations mainly consist in the transformation of chemical species from toxic compounds into available nutrients. In this particular field, the microbial research, the “Omic” technologies will allow a broader scope of studies about a current microbial profile inside aquaponics community, even in those species that currently are unculturable. This approach can also be useful to understand complex interactions of living components in the system. Until now, the analog studies were made to set up the microbial characterization on recirculation aquaculture systems (RAS). However, microbial community composition of aquaponics is still unknown. “Omic” technologies like metagenomic can help to reveal taxonomic diversity. The perspectives are also to begin the first attempts to sketch the functional diversity inside aquaponic systems and its ecological relationships. The knowledge of the emergent properties inside the microbial community, as well as the understanding of the biosynthesis pathways, can derive in future biotechnological applications. Thus, the aim of this review is to show potential applications of current “Omic” tools to characterize the microbial community in aquaponic systems. PMID:26509157

Overview of the Mars Science Laboratory Parachute Decelerator Subsystem

NASA Technical Reports Server (NTRS)

Sengupta, Anita; Steltzner, Adam; Witkowski, Al; Rowan, Jerry; Cruz, Juan

2007-01-01

In 2010 the Mars Science Laboratory (MSL) mission will deliver NASA's largest and most capable rover to the surface of Mars. MSL will explore previously unattainable landing sites due to the implementation of a high precision Entry, Descent, and Landing (EDL) system. The parachute decelerator subsystem (PDS) is an integral prat of the EDL system, providing a mass and volume efficient some of aerodynamic drag to decelerate the entry vehicle from Mach 2 to subsonic speeds prior to final propulsive descent to the sutface. The PDS for MSL is a mortar deployed 19.7m Viking type Disk-Gap-Band (DGB) parachute; chosen to meet the EDL timeline requirements and to utilize the heritage parachute systems from Viking, Mars Pathfinder, Mars Exploration Rover, and Phoenix NASA Mars Lander Programs. The preliminary design of the parachute soft goods including materials selection, stress analysis, fabrication approach, and development testing will be discussed. The preliminary design of mortar deployment system including mortar system sizing and performance predictions, gas generator design, and development mortar testing will also be presented.

Building America Case Study: Ventilation System Effectiveness and Tested Indoor Air Quality Impacts, Tyler, Texas

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

?Ventilation system effectiveness testing was conducted at two unoccupied, single-family, detached lab homes at the University of Texas - Tyler. Five ventilation system tests were conducted with various whole-building ventilation systems. Multizone fan pressurization testing characterized building and zone enclosure leakage. PFT testing showed multizone air change rates and interzonal airflow filtration. Indoor air recirculation by a central air distribution system can help improve the exhaust ventilation system by way of air mixing and filtration. In contrast, the supply and balanced ventilation systems showed that there is a significant benefit to drawing outside air from a known outside location, andmore » filtering and distributing that air. Compared to the Exhaust systems, the CFIS and ERV systems showed better ventilation air distribution and lower concentrations of particulates, formaldehyde and other VOCs. System improvement percentages were estimated based on four System Factor Categories: Balance, Distribution, Outside Air Source, and Recirculation Filtration. Recommended System Factors could be applied to reduce ventilation fan airflow rates relative to ASHRAE Standard 62.2 to save energy and reduce moisture control risk in humid climates. HVAC energy savings were predicted to be 8-10%, or $50-$75/year. Cumulative particle counts for six particle sizes, and formaldehyde and other Top 20 VOC concentrations were measured in multiple zones. The testing showed that single-point exhaust ventilation was inferior as a whole-house ventilation strategy.« less

Experimental and Computational Aerothermodynamics of a Mars Entry Vehicle

NASA Technical Reports Server (NTRS)

Hollis, Brian R.

1996-01-01

An aerothermodynamic database has been generated through both experimental testing and computational fluid dynamics simulations for a 70 deg sphere-cone configuration based on the NASA Mars Pathfinder entry vehicle. The aerothermodynamics of several related parametric configurations were also investigated. Experimental heat-transfer data were obtained at hypersonic test conditions in both a perfect gas air wind tunnel and in a hypervelocity, high-enthalpy expansion tube in which both air and carbon dioxide were employed as test gases. In these facilities, measurements were made with thin-film temperature-resistance gages on both the entry vehicle models and on the support stings of the models. Computational results for freestream conditions equivalent to those of the test facilities were generated using an axisymmetric/2D laminar Navier-Stokes solver with both perfect-gas and nonequilibrium thermochemical models. Forebody computational and experimental heating distributions agreed to within the experimental uncertainty for both the perfect-gas and high-enthalpy test conditions. In the wake, quantitative differences between experimental and computational heating distributions for the perfect-gas conditions indicated transition of the free shear layer near the reattachment point on the sting. For the high enthalpy cases, agreement to within, or slightly greater than, the experimental uncertainty was achieved in the wake except within the recirculation region, where further grid resolution appeared to be required. Comparisons between the perfect-gas and high-enthalpy results indicated that the wake remained laminar at the high-enthalpy test conditions, for which the Reynolds number was significantly lower than that of the perfect-gas conditions.

Back to the roots: the integration of a constructed wetland into a recirculating hatchery - a case study.

PubMed

Buřič, Miloš; Bláhovec, Josef; Kouřil, Jan

2015-01-01

Aquaculture is currently one of the fastest growing food-producing sectors, accounting for around 50% of the world's food fish. Limited resources, together with climatic change, have stimulated the search for solutions to support and sustain the production of fish as a nutritious food. The integration of a constructed wetland (CW) into a recirculating hatchery (RHS) was evaluated with respect to its economic feasibility and environmental impact. The outcome of eight production cycles showed the potential of CW integration for expanded production without increased operation costs or environmental load. Concretely, the use of constructed wetland allows the rearing about 40% more fish biomass, resulting in higher production and profitability. The low requirements for space, fresh water, and energy enable the establishment of such systems almost anywhere. Constructed wetlands could enhance the productivity of existing small scale facilities, as well as larger systems, to address economic and environmental issues in aquaculture. Such systems have potential to be sustainable in the context of possible future climate change and resource limitations.

Back to the Roots: The Integration of a Constructed Wetland into a Recirculating Hatchery - A Case Study

PubMed Central

Buřič, Miloš; Bláhovec, Josef; Kouřil, Jan

2015-01-01

Aquaculture is currently one of the fastest growing food-producing sectors, accounting for around 50% of the world's food fish. Limited resources, together with climatic change, have stimulated the search for solutions to support and sustain the production of fish as a nutritious food. The integration of a constructed wetland (CW) into a recirculating hatchery (RHS) was evaluated with respect to its economic feasibility and environmental impact. The outcome of eight production cycles showed the potential of CW integration for expanded production without increased operation costs or environmental load. Concretely, the use of constructed wetland allows the rearing about 40% more fish biomass, resulting in higher production and profitability. The low requirements for space, fresh water, and energy enable the establishment of such systems almost anywhere. Constructed wetlands could enhance the productivity of existing small scale facilities, as well as larger systems, to address economic and environmental issues in aquaculture. Such systems have potential to be sustainable in the context of possible future climate change and resource limitations. PMID:25853416

Mars Pathfinder Rover-Lewis Research Center Technology Experiments Program

NASA Technical Reports Server (NTRS)

Stevenson, Steven M.

1997-01-01

An overview of NASA's Mars Pathfinder Program is given and the development and role of three technology experiments from NASA's Lewis Research Center and carried on the Mars Pathfinder rover is described. Two recent missions to Mars were developed and managed by the Jet Propulsion Laboratory, and launched late last year: Mars Global Surveyor in November 1996 and Mars Pathfinder in December 1996. Mars Global Surveyor is an orbiter which will survey the planet with a number of different instruments, and will arrive in September 1997, and Mars Pathfinder which consists of a lander and a small rover, landing on Mars July 4, 1997. These are the first two missions of the Mars Exploration Program consisting of a ten year series of small robotic martian probes to be launched every 26 months. The Pathfinder rover will perform a number of technology and operational experiments which will provide the engineering information necessary to design and operate more complex, scientifically oriented surface missions involving roving vehicles and other machinery operating in the martian environment. Because of its expertise in space power systems and technologies, space mechanisms and tribology, Lewis Research Center was asked by the Jet Propulsion Laboratory, which is heading the Mars Pathfinder Program, to contribute three experiments concerning the effects of the martian environment on surface solar power systems and the abrasive qualities of the Mars surface material. In addition, rover static charging was investigated and a static discharge system of several fine Tungsten points was developed and fixed to the rover. These experiments and current findings are described herein.

Mars

NASA Technical Reports Server (NTRS)

Kieffer, Hugh H. (Editor); Jakosky, Bruce M. (Editor); Snyder, Conway W. (Editor); Matthews, Mildred S. (Editor)

1992-01-01

The present volume on Mars discusses visual, photographic and polarimetric telescopic observations, spacecraft exploration of Mars, the origin and thermal evolution of Mars, and the bulk composition, mineralogy, and internal structure of the planet. Attention is given to Martian gravity and topography, stress and tectonics on Mars, long-term orbital and spin dynamics of Mars, and Martian geodesy and cartography. Topics addressed include the physical volcanology of Mars, the canyon system on planet, Martian channels and valley networks, and ice in the Martian regolith. Also discussed are Martian aeolian processes, sediments, and features, polar deposits of Mars, dynamics of the Martian atmosphere, and the seasonal behavior of water on Mars.

Human Support Technology Research to Enable Exploration

NASA Technical Reports Server (NTRS)

Joshi, Jitendra

2003-01-01

Contents include the following: Advanced life support. System integration, modeling, and analysis. Progressive capabilities. Water processing. Air revitalization systems. Why advanced CO2 removal technology? Solid waste resource recovery systems: lyophilization. ISRU technologies for Mars life support. Atmospheric resources of Mars. N2 consumable/make-up for Mars life. Integrated test beds. Monitoring and controlling the environment. Ground-based commercial technology. Optimizing size vs capability. Water recovery systems. Flight verification topics.

Vortex dynamics and scalar transport in the wake of a bluff body driven through a steady recirculating flow

NASA Astrophysics Data System (ADS)

Poussou, Stephane B.; Plesniak, Michael W.

2012-09-01

The air ventilation system in wide-body aircraft cabins provides passengers with a healthy breathing environment. In recent years, the increase in global air traffic has amplified contamination risks by airborne flu-like diseases and terrorist threats involving the onboard release of noxious materials. In particular, passengers moving through a ventilated cabin may transport infectious pathogens in their wake. This paper presents an experimental investigation of the wake produced by a bluff body driven through a steady recirculating flow. Data were obtained in a water facility using particle image velocimetry and planar laser induced fluorescence. Ventilation attenuated the downward convection of counter-rotating vortices produced near the free-end corners of the body and decoupled the downwash mechanism from forward entrainment, creating stagnant contaminant regions.

KSC-99pp1398

NASA Image and Video Library

1999-12-06

James Stickley (left) and Derry Dilby (right), who are with United Space Alliance, check over a spare four-inch diameter LH2 recirculation line that will be used to replace a damaged LH2 line in the orbiter Discovery. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. Workers noted a dent in the line during routine aft compartment inspections Tuesday, Dec. 7. The dent measures 12 inches long and about ½-inch deep. Managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope

KSC-99pp1396

NASA Image and Video Library

1999-12-09

Gary Hamilton (left) and James Stickley, both with United Space Alliance, check out a spare four-inch diameter LH2 recirculation line that will be used to replace a damaged LH2 line in the orbiter Discovery. The line recirculates hydrogen from the Shuttle main engines back to the external tank during prelaunch engine conditioning. Workers noted a dent in the line during routine aft compartment inspections Tuesday, Dec. 7. The dent measures 12 inches long and about ½-inch deep. Managers expect the replacement work to take about 3 days, followed by system retests and final aft compartment close-outs. Preliminary assessments reflect a launch date of Space Shuttle Discovery on mission STS-103 no earlier than Dec. 16. STS-103 is the third servicing mission for the Hubble Space Telescope

A feasibility study of a NBI photoneutralizer based on nonlinear gating laser recirculation

NASA Astrophysics Data System (ADS)

Fassina, A.; Pretato, F.; Barbisan, M.; Giudicotti, L.; Pasqualotto, R.

2016-02-01

The neutralization efficiency of negative ion neutral beam injectors is a major issue for future fusion reactors. Photon neutralization might be a valid alternative to present gas neutralizers, but still with several challenges for a valid implementation. Some concepts have been presented so far but none has been validated yet. A novel photoneutralization concept is discussed here, based on an annular cavity and a duplicated frequency laser beam (recirculation injection by nonlinear gating). The choice of lithium triborate as the material for the second harmonic extractor is discussed and a possible cooling method via crystal slicing is presented; laser intensity enhancement within the cavity is evaluated in order to quantify the achievable neutralization rate. Mockups of the critical components are proposed as intermediate steps toward system realization.

Dynamics of microorganism populations in recirculating nutrient solutions

NASA Technical Reports Server (NTRS)

Strayer, R. F.

1994-01-01

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.

Innovative method and equipment for personalized ventilation.

PubMed

Kalmár, F

2015-06-01

At the University of Debrecen, a new method and equipment for personalized ventilation has been developed. This equipment makes it possible to change the airflow direction during operation with a time frequency chosen by the user. The developed office desk with integrated air ducts and control system permits ventilation with 100% outdoor air, 100% recirculated air, or a mix of outdoor and recirculated air in a relative proportion set by the user. It was shown that better comfort can be assured in hot environments if the fresh airflow direction is variable. Analyzing the time step of airflow direction changing, it was found that women prefer smaller time steps and their votes related to thermal comfort sensation are higher than men's votes. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Technicians test OV-102's aft fuselage LRU hydrogen recirculation pump

NASA Technical Reports Server (NTRS)

1990-01-01

Donald C. Buckner, a Lockheed mechanical lead technician, installs an aft fuselage line replaceable unit (LRU) liquid hydrogen recirculation pump from Columbia, Orbiter Vehicle (OV) 102 into JSC's Thermochemical Test Area (TTA) Support Laboratory Bldg 350 test stand. Technicians ran the pump package through the battery of leak tests. Preliminary indications showed only minor, acceptable leakage from the package and Kennedy Space Center (KSC) technicians have replaced a crushed seal on the prevalve of the main propulsion system they believe may have caused the STS-35 hydrogen leak. In addition to Buckner, (left to right) Larry Kilbourn, a Rockwell Service Center lead mechanical technician from Cape Canaveral, and John Dickerson, a quality inspector with EBASCO Services, also monitored the test at JSC. Photo taken by JSC photographer Benny Benavides.

Solar Electric Power System Analyses for Mars Surface Missions

NASA Technical Reports Server (NTRS)

Kerslake, Thomas W.; Kohout, Lisa L.

1999-01-01

The electric power system is a crucial element of any architecture supporting human surface exploration of Mars. In this paper, we describe the conceptual design and detailed analysis of solar electric power system using photovoltaics and regenerative fuel cells to provide surface power on Mars. System performance, mass and deployed area predictions are discussed along with the myriad environmental factors and trade study results that helped to guide system design choices. Based on this work, we have developed a credible solar electric power option that satisfies the surface power requirements of a human Mars mission. The power system option described in this paper has a mass of approximately 10 metric tons, a approximately 5000-sq m deployable photovoltaic array using thin film solar cell technology.

Usefulness of thermographic analysis to control temperature homogeneity in the development and implementation of a closed recirculating CO2 chemohyperthermia model.

PubMed

Padilla-Valverde, David; Sanchez-Garcia, Susana; García-Santos, Esther; Marcote-Ibañez, Carlos; Molina-Robles, Mercedes; Martín-Fernández, Jesús; Villarejo-Campos, Pedro

2016-09-30

To determine the effectiveness of thermography to control the distribution of abdominal temperature in the development of a closed chemohyperthermia model. For thermographic analysis, we divided the abdominopelvic cavity into nine regions according to a modification of carcinomatosis peritoneal index. A difference of 2.5 °C between and within the quadrants, and thermographic colours, were used as asymmetric criteria. Preclinical study:· Rats Model: Six athymic nude rats, male, rnu/rnu. They were treated with closed technique and open technique. Porcine Model: 12 female large white pigs. Four were treated with open technique and eight with closed recirculation CO 2 technique. Clinical Pilot Study, EUDRACT 2011-006319-69: 18 patients with ovarian cancer were treated with cytoreductive surgery and hyperthermia intraperitoneal chemotherapy, HIPEC, with a closed recirculating CO 2 system. Thermographic control and intra-abdominal temperature assessment was performed at the baseline, when outflow temperature reached 41 °C, and at 30´. The thermographic images showed a higher homogeneity of the intra-abdominal temperature in the closed model respect to the open technique. The thermogram showed a temperature distribution homogeneity when starting the circulation of chemotherapy. There was correlation between the temperature thermographic map in the closed porcine model and pilot study, and reached inflow and outflow temperatures, at half time of HIPEC, of 42/41.4 °C and 42 ± 0.2/41 ± 0.8 °C, respectively. There was no significant impact to the core temperature of patients after reaching the homogeneous temperature distribution. To control homogeneity of temperature distribution is feasible using infra-red digital images in a closed HIPEC with CO 2 recirculation.

Operation and performance of the Mars Exploration Rover imaging system on the Martian surface

NASA Technical Reports Server (NTRS)

Maki, Justin N.; Litwin, Todd; Herkenhoff, Ken

2005-01-01

The Imaging System on the Mars Exploration Rovers has successfully operated on the surface of Mars for over one Earth year. An overview of the surface imaging activities is provided, along with a summary of the image data acquired to date.

Mars Science Laboratory Entry, Descent and Landing System Overview

NASA Technical Reports Server (NTRS)

Steltzner, Adam D.; San Martin, A. Miguel; Rivellini, Tomasso P.; Chen, Allen

2013-01-01

The Mars Science Laboratory project recently places the Curiosity rove on the surface of Mars. With the success of the landing system, the performance envelope of entry, descent and landing capabilities has been extended over the previous state of the art. This paper will present an overview to the MSL entry, descent and landing system design and preliminary flight performance results.

Mars’ Growth Stunted by an Early Giant Planet Instability

NASA Astrophysics Data System (ADS)

Clement, Matthew; Kaib, Nathan A.; Raymond, Sean N.; Walsh, Kevin J.

2017-10-01

Many dynamical aspects of the solar system can be explained by the outer planets experiencing a period of orbital instability. Though often correlated with a perceived delayed spike in the lunar cratering record known as the Late Heavy Bombardment (LHB), recent work suggests that this event may have occurred during the epoch of terrestrial planet formation. Though current simulations of terrestrial accretion can reproduce many observed qualities of the solar system, replicating the small mass of Mars requires modification to standard planet formation models. Here we use direct numerical simulations to show that an early instability in the outer solar system regularly yields properly sized Mars analogues. In 80% of simulations, we produce a Mars of the appropriate mass. Our most successful outcomes occur when the terrestrial planets evolve 10 million years (Myr), and accrete several Mars sized embryos in the Mars forming region before the instability takes place. Mars is left behind as a stranded embryo, while the remainder of these bodies are either ejected from the system or scattered towards the inner solar system where they deliver water to Earth. An early giant planet instability can thus replicate both the inner and outer solar system in a single model.

Entry System Design Considerations for Mars Landers

NASA Technical Reports Server (NTRS)

Lockwood, Mary Kae; Powell, Richard W.; Graves, Claude A.; Carman, Gilbert L.

2001-01-01

The objective for the next generation or Mars landers is to enable a safe landing at specific locations of scientific interest. The 1st generation entry, descent and landing systems, ex. Viking and Pathfinder, provided successful landing on Mars but by design were limited to large scale, 100s of km, landing sites with minimal local hazards. The 2 nd generation landers, or smart landers, will provide scientists with access to previously unachievable landing sites by providing precision landing to less than 10 km of a target landing site, with the ability to perform local hazard avoidance, and provide hazard tolerance. This 2nd generation EDL system can be utilized for a range of robotic missions with vehicles sized for science payloads from the small 25-70 kg, Viking, Pathfinder, Mars Polar Lander and Mars Exploration Rover-class, to the large robotic Mars Sample Return, 300 kg plus, science payloads. The 2nd generation system can also be extended to a 3nd generation EDL system with pinpoint landing, 10's of meters of landing accuracy, for more capable robotic or human missions. This paper will describe the design considerations for 2nd generation landers. These landers are currently being developed by a consortium of NASA centers, government agencies, industry and academic institutions. The extension of this system and additional considerations required for a 3nd generation human mission to Mars will be described.

Instrumentation for Mars Environments

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.

1997-01-01

The main portion of the project was to support the "MAE" experiment on the Mars Pathfinder mission and to design instrumentation for future space missions to measure dust deposition on Mars and to characterize the properties of the dust. A second task was to analyze applications for photovoltaics in new space environments, and a final task was analysis of advanced applications for solar power, including planetary probes, photovoltaic system operation on Mars, and satellite solar power systems.

Methane Propulsion Elements for Mars

NASA Technical Reports Server (NTRS)

Percy, Tom; Polsgrove, Tara; Thomas, Dan

2017-01-01

Human exploration beyond LEO relies on a suite of propulsive elements to: (1) Launch elements into space, (2) Transport crew and cargo to and from various destinations, (3) Provide access to the surface of Mars, (4) Launch crew from the surface of Mars. Oxygen/Methane propulsion systems meet the unique requirements of Mars surface access. A common Oxygen/Methane propulsion system is being considered to reduce development costs and support a wide range of primary & alternative applications.

Electrical and Chemical Interactions at Mars Workshop. Part 2: Appendix

NASA Technical Reports Server (NTRS)

1992-01-01

The objectives of the workshop were the following: (1) to identify issues related to electrical and chemical interactions between systems and their local environments at Mars; and (2) to recommend means of addressing those issues, including the dispatch of robotic spacecraft to Mars to acquire necessary information. Presentations about Mars' surface and orbital environments, Space Exploration Initiative (SEI) systems, environmental interactions, modeling and analysis, and plans for exploration are presented in viewgraph form.

A High Efficiency System for Science Instrument Commanding for the Mars Global Surveyor Mission

NASA Technical Reports Server (NTRS)

Jr., R. N. Brooks

1995-01-01

The Mars Global Surveyor (MGS) mission will return to Mars to re- cover most of the science lost when the ill fated Mars Observer space- craft suffered a catastrophic anomaly in its propulsion system and did not go into orbit. Described in detail are the methods employed by the MGS Sequence Team to accelerate science command processing by using standard command generation process and standard UNIX control scripts.

Lunar and Planetary Science XXXV: Mars: Hydrology, Drainage, and Valley Systems

NASA Technical Reports Server (NTRS)

2004-01-01

The titles in this section include: 1) Analysis of Orientation Dependence of Martian Gullies; 2) A Preliminary Relationship between the Depth of Martian Gullies and the Abundance of Hydrogen on Near-Surface Mars; 3) Water Indicators in Sirenum Terra and around the Argyre Impact Basin, Mars; 4) The Distribution of Gullies and Tounge-shaped Ridges and Their Role in the Degradation of Martian Craters; 5) A Critical Evaluation of Crater Lake Systems in Memnonia Quadrangle, Mars; 6) Impact-generated Hydrothermal Activity at Gusev Crater: Implications for the Spirit Mission; 7) Characterization of the Distributary Fan in Holden NE Crater using Stereo Analysis; 8) Computational Analysis of Drainage Basins on Mars: Appraising the Drainage Density; 9) Hypsometric Analyses of Martian Basins: A Comparison to Terrestrial, Lunar, and Venusian Hypsometry; 10) Morphologic Development of Harmakhis Vallis, Mars; 11) Mangala Valles, Mars: Investigations of the source of Flood Water and Early Stages of Flooding; 12) The Formation of Aromatum Chaos and the Water Discharge Rate at Ravi Vallis; 13) Inferring Hydraulics from Geomorphology for Athabasca Valles, Mars; 14) The Origin and Evolution of Dao Vallis: Formation and Modification of Martian Channels by Structural Collapse and Glaciation; 15) Snowmelt and the Formation of Valley Networks on Martian Volcanoes; 16) Extent of Floating Ice in an Ancient Echus Chasma/Kasei Valley System, Mars.

Apparatus for diffusion separation

DOEpatents

Nierenberg, William A.; Pontius, Rex B.

1976-08-10

1. The method of testing the separation efficiency of porous permeable membranes which comprises causing a stream of a gaseous mixture to flow into contact with one face of a finely porous permeable membrane under such conditions that a major fraction of the mixture diffuses through the membrane, maintaining a rectangular cross section of the gaseous stream so flowing past said membrane, continuously recirculating the gas that diffuses through said membrane and continuously withdrawing the gas that does not diffuse through said membrane and maintaining the volume of said recirculating gas constant by continuously introducing into said continuously recirculating gas stream a mass of gas equivalent to that which is continuously withdrawn from said gas stream and comparing the concentrations of the light component in the entering gas, the withdrawn gas and the recirculated gas in order to determine the efficiency of said membrane.

CFD modeling of hydro-biochemical behavior of MSW subjected to leachate recirculation.

PubMed

Feng, Shi-Jin; Cao, Ben-Yi; Li, An-Zheng; Chen, Hong-Xin; Zheng, Qi-Teng

2018-02-01

The most commonly used method of operating landfills more sustainably is to promote rapid biodegradation and stabilization of municipal solid waste (MSW) by leachate recirculation. The present study is an application of computational fluid dynamics (CFD) to the 3D modeling of leachate recirculation in bioreactor landfills using vertical wells. The objective is to model and investigate the hydrodynamic and biochemical behavior of MSW subject to leachate recirculation. The results indicate that the maximum recirculated leachate volume can be reached when vertical wells are set at the upper middle part of a landfill (H W /H T  = 0.4), and increasing the screen length can be more helpful in enlarging the influence radius than increasing the well length (an increase in H S /H W from 0.4 to 0.6 results in an increase in influence radius from 6.5 to 7.7 m). The time to reach steady state of leachate recirculation decreases with the increase in pressure head; however, the time for leachate to drain away increases with the increase in pressure head. It also showed that methanogenic biomass inoculum of 1.0 kg/m 3 can accelerate the volatile fatty acid depletion and increase the peak depletion rate to 2.7 × 10 -6  kg/m 3 /s. The degradation-induced void change parameter exerts an influence on the processes of MSW biodegradation because a smaller parameter value results in a greater increase in void space.

Production of cobia in recirculating aquaculture systems

USDA-ARS?s Scientific Manuscript database

Interest in cobia Rachycentron canadum aquaculture in the US has increased greatly in the last decade due to their excellent consumer appeal, extremely rapid growth rates, and the observed success of rearing this species in Taiwan and other southeastern Asian countries. Because most cobia are grown...

Comparative sensitivity of six scleractinian corals to temperature and solar radiation

EPA Science Inventory

Scleractinian corals were subjected to six combinations of temperature and solar radiation regimes to evaluate their effects on coral bleaching, survival, and tissue surface area changes during and after an exposure period. A recirculating coral exposure system was coupled to a ...

PERFORMANCE OF NORTH AMERICAN BIOREACTOR LANDFILLS: I. LEACHATE HYDROLOGY AND WASTE SETTLEMENT

EPA Science Inventory

An assessment of state-of-the-practice at five full-scale North American landfills operating as bioreactors is presented in this two-paper set. This paper focuses on effectiveness of liners and leachate collection systems, leachate generation rates, leachate recirculation practi...

Design of a New Superconducting Magnet System for High Strength Minimum-B Fields for ECRIS

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

Xie, D. Z.; Benitez, J. Y.; Hodgkinson, A.

A novel Mixed Axial and Radial field System (MARS) seeks to enhance the B fields inside the plasma chamber within the limits of a given conductor, thereby making it possible to raise the operating fields for Electron Cyclotron Resonance Ion Sources (ECRISs). The MARS concept consists of a hexagonally shaped closed-loop coil and a set of auxiliary solenoids. The application of MARS will be combined with a hexagonal plasma chamber to maximize the use of the radial fields at the chamber inner surfaces. Calculations using Opera's TOSCA-3D solver have shown that MARS can potentially generate up to 50% higher fieldsmore » and use of only about one half of the same superconducting wire, as compared with existing magnet designs in ECRISs. A MARS magnet system built with Nb 3 Sn coils could generate a high strength minimum-B field of maxima of ≥ 10 T on axis and ~6 T radially in an ECRIS plasma chamber. Following successful development, the MARS magnet system will be the best magnet scheme for the next generation of ECRISs. This paper will present the MARS concept, magnet design, prototyping a copper closed-loop coil, and discussions.« less

Design of a New Superconducting Magnet System for High Strength Minimum-B Fields for ECRIS

DOE PAGES

Xie, D. Z.; Benitez, J. Y.; Hodgkinson, A.; ...

2016-06-01

A novel Mixed Axial and Radial field System (MARS) seeks to enhance the B fields inside the plasma chamber within the limits of a given conductor, thereby making it possible to raise the operating fields for Electron Cyclotron Resonance Ion Sources (ECRISs). The MARS concept consists of a hexagonally shaped closed-loop coil and a set of auxiliary solenoids. The application of MARS will be combined with a hexagonal plasma chamber to maximize the use of the radial fields at the chamber inner surfaces. Calculations using Opera's TOSCA-3D solver have shown that MARS can potentially generate up to 50% higher fieldsmore » and use of only about one half of the same superconducting wire, as compared with existing magnet designs in ECRISs. A MARS magnet system built with Nb 3 Sn coils could generate a high strength minimum-B field of maxima of ≥ 10 T on axis and ~6 T radially in an ECRIS plasma chamber. Following successful development, the MARS magnet system will be the best magnet scheme for the next generation of ECRISs. This paper will present the MARS concept, magnet design, prototyping a copper closed-loop coil, and discussions.« less

Influence of the single EGR valve usability on development of the charge directed to individual cylinders of an internal combustion engine

NASA Astrophysics Data System (ADS)

Krakowian, Konrad; Kaźmierczak, Andrzej; Górniak, Aleksander; Wróbel, Radosław

2017-11-01

Exhaust gas recirculation systems (EGR), aside to a catalytic converters, are nowadays widely used in piston internal combustion engines to reduce nitrogen oxides (NOx) in the exhaust gas. They are characterized in that a portion of exhaust gases from the exhaust manifold is recirculated (via a condenser), and directed to a particular valve. The valve, depending on the current engine load and speed, doses the appropriate amount of exhaust gas into the exhaust manifold. Moreover, its location has a significant impact on the diverse formation of nitrogen oxides and fumes smokiness from the individual cylinders of the engine, which is a result of uneven propagation of exhaust gas into the channels of the intake manifold. This article contains the results of numerical characterized charges formed in symmetrical intake manifold with a centrally-placed EGR valve. Simulations were performed for the original intake system derived from the two-liter, turbocharged VW diesel engine.

Mars Exploration Rover Mission: Entry, Descent, and Landing System Validation

NASA Technical Reports Server (NTRS)

Mitcheltree, Robert A.; Lee, Wayne; Steltzner, Adam; SanMartin, Alejanhdro

2004-01-01

System validation for a Mars entry, descent, and landing system is not simply a demonstration that the electrical system functions in the associated environments. The function of this system is its interaction with the atmospheric and surface environment. Thus, in addition to traditional test-bed, hardware-in-the-loop, testing, a validation program that confirms the environmental interaction is required. Unfortunately, it is not possible to conduct a meaningful end-to-end test of a Mars landing system on Earth. The validation plan must be constructed from an interconnected combination of simulation, analysis and test. For the Mars Exploration Rover mission, this combination of activities and the logic of how they combined to the system's validation was explicitly stated, reviewed, and tracked as part of the development plan.

A Mission Concept: Re-Entry Hopper-Aero-Space-Craft System on-Mars (REARM-Mars)

NASA Technical Reports Server (NTRS)

Davoodi, Faranak

2013-01-01

Future missions to Mars that would need a sophisticated lander, hopper, or rover could benefit from the REARM Architecture. The mission concept REARM Architecture is designed to provide unprecedented capabilities for future Mars exploration missions, including human exploration and possible sample-return missions, as a reusable lander, ascend/descend vehicle, refuelable hopper, multiple-location sample-return collector, laboratory, and a cargo system for assets and humans. These could all be possible by adding just a single customized Re-Entry-Hopper-Aero-Space-Craft System, called REARM-spacecraft, and a docking station at the Martian orbit, called REARM-dock. REARM could dramatically decrease the time and the expense required to launch new exploratory missions on Mars by making them less dependent on Earth and by reusing the assets already designed, built, and sent to Mars. REARM would introduce a new class of Mars exploration missions, which could explore much larger expanses of Mars in a much faster fashion and with much more sophisticated lab instruments. The proposed REARM architecture consists of the following subsystems: REARM-dock, REARM-spacecraft, sky-crane, secure-attached-compartment, sample-return container, agile rover, scalable orbital lab, and on-the-road robotic handymen.

Secular Effect of Sun Oblateness on the Orbital Parameters of Mars and Jupiter

NASA Astrophysics Data System (ADS)

Vaishwar, Avaneesh; Kushvah, Badam Singh; Mishra, Devi Prasad

2018-01-01

In this paper we considered the Mars-Jupiter system to study the behaviour of Near Earth Asteroids (NEAs) as most of the NEAs originate in the main asteroid belt located between Mars and Jupiter. The materials obtained from NEAs are very useful for space industrialisation. The variations in orbital parameters, such as eccentricity, inclination, longitude of pericenter and longitude of ascending node of Mars and Jupiter were investigated for a time span of 200,000 years centered on J2000 (January 2000) using secular perturbation theory. We considered the Sun oblateness and studied the effect of Sun oblateness on orbital parameters of Mars and Jupiter. Moreover, we determined the orbital parameters for asteroids moving under the perturbation effect of Mars and Jupiter by using a secular solution of Mars-Jupiter system.

ANALYSIS OF MATERIALS IN AN EXPERIMENTAL TESTING PIPE SYSTEM FOR AN INHIBITOR OF MUSSEL KILL

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

Daniel P. Molloy

2003-06-04

A comprehensive series of 16 laboratory experiments demonstrated that the presence of vinyl tubing within a recirculating pipe system was responsible for lowering zebra mussel kill following treatment with the bacterium Pseudomonas fluorescens. All vinyl tubing was replaced in all testing units with silicone tubing, and high mussel kill (>95%) was then obtained.

Kinetics of process of product separation in closed system with recirculation

NASA Astrophysics Data System (ADS)

Prokopenko, V. S.; Orekhova, T. N.; Goncharov, E. I.; Odobesko, I. A.

2018-03-01

The object of an article is the extrapolation of the process of classifying material while passing in a model with the separation of the products of milling in the cleaning system includes a separator, concentrator, cyclone and a recycle loop. The model allows for the given parameters to predict the coarseness of grading of the finished product.

Evaluation of three types of structured floating plastic media in moving bed biofilters for total ammonia nitrogen removal in a low salinity hatchery recirculating aquaculture system

USDA-ARS?s Scientific Manuscript database

Three different commercially available structural plastic media were evaluated in triplicate in moving bed toriod filters under low salinity (11-12 ppt) warm water culture conditions and two different feed loading rates. The culture system consisted of nine separate modules that include a double dra...

Growth evaluation of Atlantic Salmon (Salmo salar) raised in seawater or freshwater and fed either fishmeal based or marine-free diets

USDA-ARS?s Scientific Manuscript database

A forty week feeding study was conducted with Atlantic salmon (Salmo salar) smolts in two recirculating aquaculture systems. Two identical systems were used and contained either freshwater (0 ppt) or seawater (about 30 ppt). Fish were fed one of two diets, a control diet containing fishmeal and fi...

Growth evaluation of atlantic salmon (Salmo salar) raised in seawater or freshwater and fed either fishmeal based on marine-free diets

USDA-ARS?s Scientific Manuscript database

A forty week feeding study was conducted with Atlantic salmon (Salmo salar) smolts in two recirculating aquaculture systems. Twelve salmon (average initial weight 117 g; initial density 9.4 kg/m3) were stocked per tank. Two identical systems were used and contained either freshwater (0 ppt) or sea...

The effects of the pulsatile period on the size of recirculation bubble in the vicinity of stent struts

NASA Astrophysics Data System (ADS)

Jiang, B.; Thondapu, V.; Barlis, P.; Poon, E. K. W.; Ooi, A. S. H.

2017-04-01

Incomplete stent apposition (ISA) is sometimes found in stent deployment at complex lesions, and it is considered to be one of the causes of post-stenting complications, such as late stent thrombosis and restenosis. The presence of ISA leads to large recirculation bubbles behind the stent struts, which can reduce shear stress at the arterial wall that retards neointimal formation process and thus lead to complications. Computational fluid dynamics (CFD) simulations are performed on simplified two-dimensional axisymmetric arterial models with stents struts of square and circular cross-sectional shapes at a malapposition distance of 120 μm from the arterial wall. To investigate the effects of pulsatile flow period on the dynamics of the recirculation bubbles, high fidelity simulations are carried out with pulsatile flows of period 0.4 s and 0.8 s. Under the condition of the same flow rate, both square and circular strut cases show that shorter period provides greater flow deceleration, leading to the formation of a larger recirculation bubble. With the same thickness, circular strut has a significant improvement over the square strut in terms of the size of the recirculation bubble, and therefore less likely to lead to complications.

Correlation between Reynolds number and eccentricity effect in stenosed artery models.

PubMed

Javadzadegan, Ashkan; Shimizu, Yasutomo; Behnia, Masud; Ohta, Makoto

2013-01-01

Flow recirculation and shear strain are physiological processes within coronary arteries which are associated with pathogenic biological pathways. Distinct Quite apart from coronary stenosis severity, lesion eccentricity can cause flow recirculation and affect shear strain levels within human coronary arteries. The aim of this study is to analyse the effect of lesion eccentricity on the transient flow behaviour in a model of a coronary artery and also to investigate the correlation between Reynolds number (Re) and the eccentricity effect on flow behaviour. A transient particle image velocimetry (PIV) experiment was implemented in two silicone based models with 70% diameter stenosis, one with eccentric stenosis and one with concentric stenosis. At different times throughout the flow cycle, the eccentric model was always associated with a greater recirculation zone length, maximum shear strain rate and maximum axial velocity; however, the highest and lowest impacts of eccentricity were on the recirculation zone length and maximum shear strain rate, respectively. Analysis of the results revealed a negative correlation between the Reynolds number (Re) and the eccentricity effect on maximum axial velocity, maximum shear strain rate and recirculation zone length. As Re number increases the eccentricity effect on the flow behavior becomes negligible.

Effects of aeration and leachate recirculation on methyl mercaptan emissions from landfill.

PubMed

Zhang, Siyuan; Long, Yuyang; Fang, Yuan; Du, Yao; Liu, Weijia; Shen, Dongsheng

2017-10-01

The issue of odorous volatile organic sulfur compound methyl mercaptan (MM) released from landfill sites cannot be ignored for its extremely low odor threshold and high toxicity. In this study, we focused on the formation and emission of MM in four lab-scaled simulated landfill reactors running in different operation modes, namely, R1 and R2, without leachate recirculation, running under anaerobic and semi-aerobic atmosphere, R3 and R4, with leachate recirculation, running under anaerobic and semi-aerobic atmosphere, respectively. From the perspective of odor abatement, the semi-aerobic operation mode can efficiently lower the emitted MM concentration by 87.4-94.9%, relative to the semi-aerobic operation mode. Furthermore, under semi-aerobic conditions, leachate recirculation substantially shortened the period of MM influence by 12.7%, thus reducing the risk of affecting the surrounding atmospheric environment. The formation of MM was dependent on the characteristics such as the volatile fatty acid concentration and chemical oxygen demand in the leachate and sulfide concentration of the refuse. Overall, MM release can be effectively controlled with semi-aerobic operation mode and leachate recirculation. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of flow recirculation on abdominal aortic aneurysm

NASA Astrophysics Data System (ADS)

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

2012-06-01

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

Task 4 supporting technology. Densification requirements definition and test objectives. Propellant densification requirements definition

NASA Technical Reports Server (NTRS)

Lak, Tibor; Weeks, D. P.

1995-01-01

The primary challenge of the X-33 CAN is to build and test a prototype LO2 and LH2 densification ground support equipment (GSE) unit, and perform tank thermodynamic testing within the 15 month phase 1 period. The LO2 and LH2 propellant densification system will be scaled for the IPTD LO2 and LH2 tank configurations. The IPTD tanks were selected for the propellant technology demonstration because of the potential benefits to the phase 1 plan: tanks will be built in time to support thermodynamic testing; minimum cost; minimum schedule risk; future testing at MSFC will build on phase 1 data base; and densification system will be available to support X-33 and RLV engine test at IPTD. The objective of the task 1 effort is to define the preliminary requirements of the propellant densification GSE and tank recirculation system. The key densification system design parameters to be established in Task 1 are: recirculation flow rate; heat exchanger inlet temperature; heat exchanger outlet temperature; maximum heat rejection rate; vent flow rate (GN2 and GH2); densification time; and tank pressure level.

Dry low combustion system with means for eliminating combustion noise

DOEpatents

Verdouw, Albert J.; Smith, Duane; McCormick, Keith; Razdan, Mohan K.

2004-02-17

A combustion system including a plurality of axially staged tubular premixers to control emissions and minimize combustion noise. The combustion system includes a radial inflow premixer that delivers the combustion mixture across a contoured dome into the combustion chamber. The axially staged premixers having a twist mixing apparatus to rotate the fluid flow and cause improved mixing without causing flow recirculation that could lead to pre-ignition or flashback.

System and method for regulating EGR cooling using a Rankine cycle

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

Ernst, Timothy C.; Morris, Dave

This disclosure relates to a waste heat recovery (WHR) system and method for regulating exhaust gas recirculation (EGR) cooling, and more particularly, to a Rankine cycle WHR system and method, including a recuperator bypass arrangement to regulate EGR exhaust gas cooling for engine efficiency improvement and thermal management. This disclosure describes other unique bypass arrangements for increased flexibility in the ability to regulate EGR exhaust gas cooling.

System and method for regulating EGR cooling using a rankine cycle

DOEpatents

Ernst, Timothy C.; Morris, Dave

2015-12-22

This disclosure relates to a waste heat recovery (WHR) system and method for regulating exhaust gas recirculation (EGR) cooling, and more particularly, to a Rankine cycle WHR system and method, including a recuperator bypass arrangement to regulate EGR exhaust gas cooling for engine efficiency improvement and thermal management. This disclosure describes other unique bypass arrangements for increased flexibility in the ability to regulate EGR exhaust gas cooling.

Water extraction on Mars for an expanding human colony

NASA Astrophysics Data System (ADS)

Ralphs, M.; Franz, B.; Baker, T.; Howe, S.

2015-11-01

In-situ water extraction is necessary for an extended human presence on Mars. This study looks at the water requirements of an expanding human colony on Mars and the general systems needed to supply that water from the martian atmosphere and regolith. The proposed combination of systems in order to supply the necessary water includes a system similar to Honeybee Robotics' Mobile In-Situ Water Extractor (MISWE) that uses convection, a system similar to MISWE but that directs microwave energy down a borehole, a greenhouse or hothouse type system, and a system similar to the Mars Atmospheric Resource Recovery System (MARRS). It is demonstrated that a large water extraction system that can take advantage of large deposits of water ice at site specific locations is necessary to keep up with the demands of a growing colony.

Proceedings of the 40th Lunar and Planetary Science Conference

NASA Technical Reports Server (NTRS)

2009-01-01

The 40th Lunar and Planetary Science Conference included sessions on: Phoenix: Exploration of the Martian Arctic; Origin and Early Evolution of the Moon; Comet Wild 2: Mineralogy and More; Astrobiology: Meteorites, Microbes, Hydrous Habitats, and Irradiated Ices; Phoenix: Soil, Chemistry, and Habitability; Planetary Differentiation; Presolar Grains: Structures and Origins; SPECIAL SESSION: Venus Atmosphere: Venus Express and Future Missions; Mars Polar Caps: Past and Present; SPECIAL SESSION: Lunar Missions: Results from Kaguya, Chang'e-1, and Chandrayaan-1, Part I; 5 Early Nebula Processes and Models; SPECIAL SESSION: Icy Satellites of Jupiter and Saturn: Cosmic Gymnasts; Mars: Ground Ice and Climate Change; SPECIAL SESSION: Lunar Missions: Results from Kaguya, Chang'e-1, and Chandrayaan-1, Part II; Chondrite Parent-Body Processes; SPECIAL SESSION: Icy Satellites of Jupiter and Saturn: Salubrious Surfaces; SNC Meteorites; Ancient Martian Crust: Primary Mineralogy and Aqueous Alteration; SPECIAL SESSION: Messenger at Mercury: A Global Perspective on the Innermost Planet; CAIs and Chondrules: Records of Early Solar System Processes; Small Bodies: Shapes of Things to Come; Sulfur on Mars: Rocks, Soils, and Cycling Processes; Mercury: Evolution and Tectonics; Venus Geology, Volcanism, Tectonics, and Resurfacing; Asteroid-Meteorite Connections; Impacts I: Models and Experiments; Solar Wind and Genesis: Measurements and Interpretation; Mars: Aqueous Processes; Magmatic Volatiles and Eruptive Conditions of Lunar Basalts; Comparative Planetology; Interstellar Matter: Origins and Relationships; Impacts II: Craters and Ejecta Mars: Tectonics and Dynamics; Mars Analogs I: Geological; Exploring the Diversity of Lunar Lithologies with Sample Analyses and Remote Sensing; Chondrite Accretion and Early History; Science Instruments for the Mars Science Lander; . Martian Gullies: Morphology and Origins; Mars: Dunes, Dust, and Wind; Mars: Volcanism; Early Solar System Chronology; Seek Out and Explore: Upcoming and Future Missions; Mars: Early History and Impact Processes; Mars Analogs II: Chemical and Spectral; Achondrites and their Parent Bodies; and Planning for Future Exploration of the Moon The poster sessions were: Lunar Missions: Results from Kaguya, Chang'e-1, and Chandrayaan-1; LRO and LCROSS; Geophysical Analysis of the Lunar Surface and Interior; Remote Observation and Geologic Mapping of the Lunar Surface; Lunar Spectroscopy; Venus Geology, Geophysics, Mapping, and Sampling; Planetary Differentiation; Bunburra and Buzzard Coulee: Recent Meteorite Falls; Meteorites: Terrestrial History; CAIs and Chondrules: Records of Early Solar System Processes; Volatile and Organic Compounds in Chondrites; Crashing Chondrites: Impact, Shock, and Melting; Ureilite Studies; Petrology and Mineralogy of the SNC Meteorites; Martian Meteorites; Phoenix Landing Site: Perchlorate and Other Tasty Treats; Mars Polar Atmospheres and Climate Modeling; Mars Polar Investigations; Mars Near-Surface Ice; Mars: A Volatile-Rich Planet; Mars: Geochemistry and Alteration Processes; Martian Phyllosilicates: Identification, Formation, and Alteration; Astrobiology; Instrument Concepts, Systems, and Probes for Investigating Rocks and Regolith; Seeing is Believing: UV, VIS, IR, X- and Gamma-Ray Camera and Spectrometer Instruments; Up Close and Personal: In Situ Analysis with Laser-Induced Breakdown Spectroscopy and Mass Spectrometry; Jupiter and Inscrutable Io; Tantalizing Titan; Enigmatic Enceladus and Intriguing Iapetus; Icy Satellites: Cryptic Craters; Icy Satellites: Gelid Geology/Geophysics; Icy Satellites: Cool Chemistry and Spectacular Spectroscopy; Asteroids and Comets; Comet Wild 2: Mineralogy and More; Hypervelocity Impacts: Stardust Models, LDEF, and ISPE; Presolar Grains; Early Nebular Processes: Models and Isotopes; Solar Wind and Genesis: Measurements and Interpretation; Education and Public Outreach; Mercury; Pursuing Lunar Exploration; Sources and Eruptionf Lunar Basalts; Chemical and Physical Properties of the Lunar Regolith; Lunar Dust and Transient Surface Phenomena; Lunar Databases and Data Restoration; Meteoritic Samples of the Moon; Chondrites, Their Clasts, and Alteration; Achondrites: Primitive and Not So Primitive; Iron Meteorites; Meteorite Methodology; Antarctic Micrometeorites; HEDs and Vesta; Dust Formation and Transformation; Interstellar Organic Matter; Early Solar System Chronology; Comparative Planetology; Impacts I: Models and Experiments; Impacts II: Craters and Ejecta; Mars: Volcanism; Mars: Tectonics and Dynamics; Martian Stratigraphy: Understanding the Geologic History of Mars Through the Sedimentary Rock Record; Mars: Valleys and Valley Networks; Mars: Aqueous Processes in Valles Marineris and the Southern Highlands; Mars: Aqueous Geomorphology; Martian Gullies: Morphology and Origins; Mars: Dunes, Dust, and Wind; Mars: Remote Sensing; Mars: Geologic Mapping, Photogrammetry, and Cratering; Martian Mineralogy: Constraints from Missions and Laboratory Investigations; Mars Analogs: Chemical and Physical; Mars Analogs: Sulfates and Sulfides; Missions: Approaches, Architectures, Analogs, and Actualities; Not Just Skin Deep: Electron Microscopy, Heat Flow, Radar, and Seismology Instruments and Planetary Data Systems, Techniques, and Interpretation.

Human Mars Mission: SEP Architecture Crew Taxi Propulsion Stage Study and Design and Technology for Reaction and Control System. Part 1

NASA Technical Reports Server (NTRS)

Young, Archie

1999-01-01

The Mars exploration is a candidate pathway to expand human presence and useful activities in the solar system. There are several propulsion system options being considered to place the Mars payload on its inter-planetary transfer trajectory. One propulsion option is the use of Solar Electric Propulsion (SEP) to spiral out with the Mars payload from an initial Low Earth Orbit (LEO) to an elliptical High Earth Orbit (HEO). This report, presented in annotated facing page format, describes the work completed on the design of a crew taxi propulsion stage used in conjunction with the SEP. Transportation system/mission analysis topics covered in this report include sub-system analysis, trajectory profile description, mass performance and crew taxi stage sizing, stage configuration, stage cost, and Trans-Mars Injection (TMI) launch window. The high efficiency of SEP is used to provide the major part of the TMI propulsion maneuver. Orbital energy is continuously added over a period of approximately twelve months. The SEP and Mars payload follow a spiral trajectory from an initial LEO to a final elliptical HEO. A small chemical stage is then used to provide the final part of the TMI. The now unloaded SEP returns to LEO to repeat another spiral trajectory with payload to HEO. The spiral phase of the SEP's trajectory takes several months to reach HEO, thus significantly increasing the exposure time of the crew to zero-gravity. In order to minimize the long zero-gravity effects, a high thrust chemical stage delivers the crew to the SEP's HEO. The crew rendezvous with the Mars payload in HEO. After a checkout period the Mars payload with the crew is injected onto a Trans-Mars Trajectory by a small chemical stage.

Human Mars Mission: SEP Architecture, Crew Taxi Propulsion Stage Study and Design and Technology for Reaction and Control System. Pt. 1

NASA Technical Reports Server (NTRS)

Young, Archie

1999-01-01

The Mars exploration is a candidate pathway to expand human presence and useful activities in the solar system. There are several propulsion system options being considered to place the Mars payload on its interplanetary transfer trajectory. One propulsion option is the use of Solar Electric Propulsion (SEP) to spiral out with the Mars payload from an initial Low Earth Orbit (LEO) to an elliptical High Earth Orbit (HEO). This report, presented in annotated facing page format, describes the work completed on the design of a crew taxi propulsion stage used in conjunction with the SEP. Transportation system/mission analysis topics covered in this report include sub-system analysis, trajectory profile description, mass performance and crew taxi stage sizing, stage configuration, stage cost, and Trans-Mars Injection (TMI) launch window. The high efficiency of SEP is used to provide the major part of the TMI propulsion maneuver. Orbital energy is continuously added over a period of approximately twelve months. The SEP and Mars payload follow a spiral trajectory from an initial LEO to a final elliptical HEO. A small chemical stage is then used to provide the final part of the TMI. The now unloaded SEP returns to LEO to repeat another spiral trajectory with payload to HEO. The spiral phase of the SEP's trajectory takes several months to reach HEO, thus significantly increasing the exposure time of the crew to zero-gravity. In order to minimize the long zero-gravity effects, a high thrust chemical stage delivers the crew to the SEP's HEO. The crew rendezvous with the Mars payload in HEO. After a checkout period the Mars payload with the crew is injected onto a Trans-Mars Trajectory by a small chemical stage.

The fate of H2O2 during managed aquifer recharge: A residual from advanced oxidation processes for drinking water production.

PubMed

Wang, F; van Halem, D; van der Hoek, J P

2016-04-01

The fate of H2O2 residual from advanced oxidation process (AOP) preceding managed aquifer recharge (MAR) is of concern because H2O2 could lead to undesired effects on organisms in the MAR aquatic and soil ecosystem. The objective of this study was to distinguish between factors affecting H2O2 decomposition in MAR systems, simulated in batch reactors with synthetic MAR water and slow sand filter sand. The results showed that pure sand and soil organic matter had no considerable effect on H2O2 decomposition, whereas naturally occurring inorganic substances on the surface of sand grains and microbial biomass are the two main factors accelerating H2O2 decomposition in MAR systems. Additionally, the results showed that the H2O2 decompositions with different initial concentrations fitted first-order kinetics in 2-6 h in a mixture of slow sand filter sand (as a substitute for sand from a MAR system) and synthetic MAR water with high bacterial population. An estimation indicated that low concentrations of H2O2 (<3 mg/L) could decompose to the provisional standard of 0.25 mg/L in the first centimeters of MAR systems with the influent water containing high microbial biomass 38 ng ATP/mL. Copyright © 2016 Elsevier Ltd. All rights reserved.