Science.gov

Sample records for gas distribution mains

  1. Airflow Model Testing to Determine the Distribution of Hot Gas Flow and O/F Ratio Across the Space Shuttle Main Engine Main Injector Assembly

    NASA Technical Reports Server (NTRS)

    Mahorter, L.; Chik, J.; McDaniels, D.; Dill, C.

    1990-01-01

    Engine 0209, the certification engine for the new Phase 2+ Hot Gas Manifold (HGM), showed severe deterioration of the Main Combustion Chamber (MCC) liner during hot fire tests. One theory on the cause of the damage held that uneven local distribution of the fuel rich hot gas flow through the main injector assembly was producing regions of high oxidizer/fuel (O/F) ratio near the wall of the MCC liner. Airflow testing was proposed to measure the local hot gas flow rates through individual injector elements. The airflow tests were conducted using full scale, geometrically correct models of both the current Phase 2 and the new Phase 2+ HGMs. Different main injector flow shield configurations were tested for each HGM to ascertain their effect on the pressure levels and distribution of hot gas flow. Instrumentation located on the primary faceplate of the main injector measured hot gas flow through selected injector elements. These data were combined with information from the current space shuttle main engine (SSME) power balances to produce maps of pressure, hot gas flow rate, and O/F ratio near the main injector primary plate. The O/F distributions were compared for the different injector and HGM configurations.

  2. Wireless Self-powered Visual and NDE Robotic Inspection System for Live Gas Distribution Mains

    SciTech Connect

    Susan Burkett; Hagen Schempf

    2006-01-31

    Carnegie Mellon University (CMU) under contract from Department of Energy/National Energy Technology Laboratory (DoE/NETL) and co-funding from the Northeast Gas Association (NGA), has completed the overall system design of the next-generation Explorer-II (X-II) live gas main NDE and visual inspection robot platform. The design is based on the Explorer-I prototype which was built and field-tested under a prior (also DoE- and NGA co-funded) program, and served as the validation that self-powered robots under wireless control could access and navigate live natural gas distribution mains. The X-II system design ({approx}8 ft. and 66 lbs.) was heavily based on the X-I design, yet was substantially expanded to allow the addition of NDE sensor systems (while retaining its visual inspection capability), making it a modular system, and expanding its ability to operate at pressures up to 750 psig (high-pressure and unpiggable steel-pipe distribution mains). A new electronics architecture and on-board software kernel were added to again improve system performance. A locating sonde system was integrated to allow for absolute position-referencing during inspection (coupled with external differential GPS) and emergency-locating. The power system was upgraded to utilize lithium-based battery-cells for an increase in mission-time. The system architecture now relies on a dual set of end camera-modules to house the 32-bit processors (Single-Board Computer or SBC) as well as the imaging and wireless (off-board) and CAN-based (on-board) communication hardware and software systems (as well as the sonde-coil and -electronics). The drive-module (2 ea.) are still responsible for bracing (and centering) to drive in push/pull fashion the robot train into and through the pipes and obstacles. The steering modules and their arrangement, still allow the robot to configure itself to perform any-angle (up to 90 deg) turns in any orientation (incl. vertical), and enable the live launching and

  3. Explorer-II: Wireless Self-Powered Visual and NDE Robotic Inspection System for Live Gas Distribution Mains

    SciTech Connect

    Carnegie Mellon University

    2008-09-30

    Carnegie Mellon University (CMU) under contract from Department of Energy/National Energy Technology Laboratory (DoE/NETL) and co-funding from the Northeast Gas Association (NGA), has completed the overall system design, field-trial and Magnetic Flux Leakage (MFL) sensor evaluation program for the next-generation Explorer-II (X-II) live gas main Non-destructive Evaluation (NDE) and visual inspection robot platform. The design is based on the Explorer-I prototype which was built and field-tested under a prior (also DoE- and NGA co-funded) program, and served as the validation that self-powered robots under wireless control could access and navigate live natural gas distribution mains. The X-II system design ({approx}8 ft. and 66 lbs.) was heavily based on the X-I design, yet was substantially expanded to allow the addition of NDE sensor systems (while retaining its visual inspection capability), making it a modular system, and expanding its ability to operate at pressures up to 750 psig (high-pressure and unpiggable steel-pipe distribution mains). A new electronics architecture and on-board software kernel were added to again improve system performance. A locating sonde system was integrated to allow for absolute position-referencing during inspection (coupled with external differential GPS) and emergency-locating. The power system was upgraded to utilize lithium-based battery-cells for an increase in mission-time. The resulting robot-train system with CAD renderings of the individual modules. The system architecture now relies on a dual set of end camera-modules to house the 32-bit processors (Single-Board Computer or SBC) as well as the imaging and wireless (off-board) and CAN-based (on-board) communication hardware and software systems (as well as the sonde-coil and -electronics). The drive-module (2 ea.) are still responsible for bracing (and centering) to drive in push/pull fashion the robot train into and through the pipes and obstacles. The steering modules

  4. GAS MAIN SENSOR AND COMMUNICATIONS NETWORK SYSTEM

    SciTech Connect

    Hagen Schempf, Ph.D.

    2003-02-27

    Automatika, Inc. was contracted by the Department of Energy (DOE) and with co-funding from the New York Gas Group (NYGAS), to develop an in-pipe natural gas prototype measurement and wireless communications system for assessing and monitoring distribution networks. A prototype system was built for low-pressure cast-iron mains and tested in a spider- and serial-network configuration in a live network in Long Island with the support of Keyspan Energy, Inc. The prototype unit combined sensors capable of monitoring pressure, flow, humidity, temperature and vibration, which were sampled and combined in data-packages in an in-pipe master-slave architecture to collect data from a distributed spider-arrangement, and in a master-repeater-slave configuration in serial or ladder-network arrangements. It was found that the system was capable of performing all data-sampling and collection as expected, yielding interesting results as to flow-dynamics and vibration-detection. Wireless in-pipe communications were shown to be feasible and valuable data was collected in order to determine how to improve on range and data-quality in the future.

  5. Distributed PV Adoption in Maine Through 2021

    SciTech Connect

    Gagnon, Pieter; Sigrin, Ben

    2015-11-06

    NREL has used its dSolar (distributed solar) model to generate low-medium-high estimates of distributed PV adoption in Maine through 2021. This presentation gives a high-level overview of the model and modeling results.

  6. Automated Gas Distribution System

    NASA Astrophysics Data System (ADS)

    Starke, Allen; Clark, Henry

    2012-10-01

    The cyclotron of Texas A&M University is one of the few and prized cyclotrons in the country. Behind the scenes of the cyclotron is a confusing, and dangerous setup of the ion sources that supplies the cyclotron with particles for acceleration. To use this machine there is a time consuming, and even wasteful step by step process of switching gases, purging, and other important features that must be done manually to keep the system functioning properly, while also trying to maintain the safety of the working environment. Developing a new gas distribution system to the ion source prevents many of the problems generated by the older manually setup process. This developed system can be controlled manually in an easier fashion than before, but like most of the technology and machines in the cyclotron now, is mainly operated based on software programming developed through graphical coding environment Labview. The automated gas distribution system provides multi-ports for a selection of different gases to decrease the amount of gas wasted through switching gases, and a port for the vacuum to decrease the amount of time spent purging the manifold. The Labview software makes the operation of the cyclotron and ion sources easier, and safer for anyone to use.

  7. Gas Main Sensor and Communications Network System

    SciTech Connect

    Hagen Schempf

    2006-05-31

    Automatika, Inc. was contracted by the Department of Energy (DOE) and with co-funding from the Northeast Gas Association (NGA), to develop an in-pipe natural gas prototype measurement and wireless communications system for assessing and monitoring distribution networks. This projected was completed in April 2006, and culminated in the installation of more than 2 dozen GasNet nodes in both low- and high-pressure cast-iron and steel mains owned by multiple utilities in the northeastern US. Utilities are currently logging data (off-line) and monitoring data in real time from single and multiple networked sensors over cellular networks and collecting data using wireless bluetooth PDA systems. The system was designed to be modular, using in-pipe sensor-wands capable of measuring, flow, pressure, temperature, water-content and vibration. Internal antennae allowed for the use of the pipe-internals as a waveguide for setting up a sensor network to collect data from multiple nodes simultaneously. Sensor nodes were designed to be installed with low- and no-blow techniques and tools. Using a multi-drop bus technique with a custom protocol, all electronics were designed to be buriable and allow for on-board data-collection (SD-card), wireless relaying and cellular network forwarding. Installation options afforded by the design included direct-burial and external polemounted variants. Power was provided by one or more batteries, direct AC-power (Class I Div.2) and solar-array. The utilities are currently in a data-collection phase and intend to use the collected (and processed) data to make capital improvement decisions, compare it to Stoner model predictions and evaluate the use of such a system for future expansion, technology-improvement and commercialization starting later in 2006.

  8. GAS MAIN SENSOR AND COMMUNICATIONS NETWORK SYSTEM

    SciTech Connect

    Hagen Schempf

    2004-09-30

    Automatika, Inc. was contracted by the Department of Energy (DOE) and with co-funding from the New York Gas Group (NYGAS), to develop an in-pipe natural gas prototype measurement and wireless communications system for assessing and monitoring distribution networks. In Phase II of this three-phase program, an improved prototype system was built for low-pressure cast-iron and high-pressure steel (including a no-blow installation system) mains and tested in a serial-network configuration in a live network in Long Island with the support of Keyspan Energy, Inc. The experiment was carried out in several open-hole excavations over a multi-day period. The prototype units (3 total) combined sensors capable of monitoring pressure, flow, humidity, temperature and vibration, which were sampled and combined in data-packages in an in-pipe master-repeater-slave configuration in serial or ladder-network arrangements. It was verified that the system was capable of performing all data-sampling, data-storage and collection as expected, yielding interesting results as to flow-dynamics and vibration-detection. Wireless in-pipe communications were shown to be feasible and the system was demonstrated to run off in-ground battery- and above-ground solar power. The remote datalogger access and storage-card features were demonstrated and used to log and post-process system data. Real-time data-display on an updated Phase-I GUI was used for in-field demonstration and troubleshooting.

  9. Upgraded SCADA for Yugoslav main gas pipeline

    SciTech Connect

    Atlagic, B.S.; Kovacevic, V.V.; Maruna, V.S.; Mihic, V.M.; Adjanski, B.D.

    1996-12-31

    This paper presents the configuration of a SCADA based telemetry system for the main Yugoslav gas pipeline network. A central supervising SCADA station is realized by using reliable industrial PC stations interconnected via a LAN. The key features of this SCADA are open architecture, hot stand-by, an effective MMI subsystem and an information link to the Enterprise Information System. In order to achieve better supervision and control over the gas-transport process, basic SCADA functions are supplemented with a decision support system based on trend analysis and a steady-state simulation model.

  10. Multiple complementary gas distribution assemblies

    DOEpatents

    Ng, Tuoh-Bin; Melnik, Yuriy; Pang, Lily L; Tuncel, Eda; Nguyen, Son T; Chen, Lu

    2016-04-05

    In one embodiment, an apparatus includes a first gas distribution assembly that includes a first gas passage for introducing a first process gas into a second gas passage that introduces the first process gas into a processing chamber and a second gas distribution assembly that includes a third gas passage for introducing a second process gas into a fourth gas passage that introduces the second process gas into the processing chamber. The first and second gas distribution assemblies are each adapted to be coupled to at least one chamber wall of the processing chamber. The first gas passage is shaped as a first ring positioned within the processing chamber above the second gas passage that is shaped as a second ring positioned within the processing chamber. The gas distribution assemblies may be designed to have complementary characteristic radial film growth rate profiles.

  11. 34. ROUGH GAS MAIN RUNNING SOUTHEAST FROM THE BOP SHOP ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. ROUGH GAS MAIN RUNNING SOUTHEAST FROM THE BOP SHOP TO THE DUAL VENTURI GAS WASHERS. - U.S. Steel Duquesne Works, Basic Oxygen Steelmaking Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  12. 14. DETAIL OF CLEAN GAS MAIN (UPPER PIPE) AND ROUGH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    14. DETAIL OF CLEAN GAS MAIN (UPPER PIPE) AND ROUGH GAS MAIN FOR BLAST FURNACE No. 2 AT THE BASE OF HOT BLAST STOVES LOOKING EAST. (Jet Lowe) - U.S. Steel Duquesne Works, Blast Furnace Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  13. Distributions of Quasar Hosts on the Galaxy Main Sequence Plane

    NASA Astrophysics Data System (ADS)

    Zhang, Zhoujian; Shi, Yong; Rieke, George H.; Xia, Xiaoyang; Wang, Yikang; Sun, Bingqing; Wan, Linfeng

    2016-03-01

    The relation between star formation rates (SFRs) and stellar masses, i.e., the galaxy main sequence, is a useful diagnostic of galaxy evolution. We present the distributions relative to the main sequence of 55 optically selected PG and 12 near-IR-selected Two Micron All Sky Survey (2MASS) quasars at z ≤ 0.5. We estimate the quasar host stellar masses from Hubble Space Telescope or ground-based AO photometry, and the SFRs through the mid-infrared aromatic features and far-IR photometry. We find that PG quasar hosts more or less follow the main sequence defined by normal star-forming galaxies while 2MASS quasar hosts lie systematically above the main sequence. PG and 2MASS quasars with higher nuclear luminosities seem to have higher specific SFRs (sSFRs), although there is a large scatter. No trends are seen between sSFRs and SMBH masses, Eddington ratios, or even morphology types (ellipticals, spirals, and mergers). Our results could be placed in an evolutionary scenario with quasars emerging during the transition from ULIRGs/mergers to ellipticals. However, combined with results at higher redshift, they suggest that quasars can be widely triggered in normal galaxies as long as they contain abundant gas and have ongoing star formation.

  14. MEASUREMENT OF METHANE EMISSIONS FROM UNDERGROUND DISTRIBUTION MAINS AND SERVICES

    EPA Science Inventory

    The paper reports results of measurements of methane emissions from underground distribution mains and services. In the program, leakage from underground distribution systems is estimated by combining leak measurements with historical leak record data and the length of undergroun...

  15. 51. View looking west down ladle car rightofway; gas main ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. View looking west down ladle car right-of-way; gas main at right, Babcock & Wilcox boilers at left. - Sloss-Sheffield Steel & Iron, First Avenue North Viaduct at Thirty-second Street, Birmingham, Jefferson County, AL

  16. Fuel gas main replacement at Acme Steel's coke plant

    SciTech Connect

    Trevino, O. . Chicago Coke Plant)

    1994-09-01

    ACME Steel's Chicago coke plant consists of two 4-meter, 50-oven Wilputte underjet coke-oven batteries. These batteries were constructed in 1956--1957. The use of blast furnace gas was discontinued in the late 1960's. In 1977--1978, the oven walls in both batteries were reconstructed. Reconstruction of the underfire system was limited to rebuilding the coke-oven gas reversing cocks and meter in orifices. By the early 1980's, the 24-in. diameter underfire fuel gas mains of both batteries developed leaks at the Dresser expansion joints. These leaks were a result of pipe loss due to corrosion. Leaks also developed along the bottoms and sides of both mains. A method is described that permitted pushing temperatures to be maintained during replacement of underfire fuel gas mains. Each of Acme's two, 50-oven, 4-metric Wilputte coke-oven, gas-fired batteries were heated by converting 10-in. diameter decarbonizing air mains into temporary fuel gas mains. Replacement was made one battery at a time, with the temporary 10-in. mains in service for five to eight weeks.

  17. Catalogue of the main gas manifestation of Greece: Geochemical characterisation and preliminary gas hazard assessment

    NASA Astrophysics Data System (ADS)

    D'Alessandro, Walter; Kyriakopoulos, Konstantinos; Calabrese, Sergio

    2014-05-01

    Like other geodynamically active areas, the Hellenic territory is also affected by a large number of geogenic gas manifestations. These occur either in form of point sources (fumaroles, mofettes, bubbling gases) or as diffuse soil gas emanations. The present work produced a first catalogue of the geogenic gas manifestations of the whole Hellenic territory also considering a few literature data. All collected samples were analysed for their chemical composition (He, Ne, Ar, O2, N2, H2, H2S, CO, CH4 and CO2) and isotopic composition (He, CO2-C, CH4-C, N2-N). Geogenic sources release huge amounts of gases, which, apart from having important influences on the global climate, could have strong impact on human health. Gases have both acute and chronic effects. Carbon Dioxide and Hydrogen Sulphide are the main gases responsible for acute mortality due to their asphyxiating and/or toxic properties. Methane instead represents a risk for its explosive properties. Gas hazard is often disregarded because in fatal episodes connected to geogenic gases the death cause is often not correctly attributed. Due to the fact that geodynamic active areas can release geogenic gases for million years over wide areas, it is important not to underestimate potential risks. A preliminary estimation of the gas hazard has been made for the time period of the last 20 years considering the whole population of Greece. In this period at least two fatal episodes with a total of three victims could be certainly attributed to geogenic gases (specifically CO2). This would give a risk of 1.3×10-8 fatality from geogenic gas manifestations per annum. Such value, although probably underestimated, is much lower than most other natural or anthropogenic risks. Nevertheless this risk, being unevenly distributed along the whole territory, should not be overlooked especially in areas with high density of gas manifestations and high soil gas fluxes.

  18. Identification of gas mains and potential gas customers using a GIS approach

    SciTech Connect

    Stanton, M.; Spraker, L.; Fisher, A.

    1996-08-01

    The objective of this project was to identify potential gas customers (current electric customers not currently receiving gas service) that were located along an existing gas main. The geographic information system (GIS) approach used by Niagara Mohawk Power Corporation in New York to identify natural gas marketing areas is briefly described in this paper. Over 140,000 potential gas customers were identified as being along an existing main. The procedures used proved to be an extremely efficient and cost effective means of identifying gas main locations and potential customers.

  19. 46 CFR 169.678 - Main distribution panels and switchboards.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Main distribution panels and switchboards. 169.678 Section 169.678 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Machinery and Electrical Electrical Installations Operating at Potentials of 50 Volts Or More on Vessels of Less Than 100 Gross...

  20. 46 CFR 169.678 - Main distribution panels and switchboards.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Main distribution panels and switchboards. 169.678 Section 169.678 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Machinery and Electrical Electrical Installations Operating at Potentials of 50 Volts Or More on Vessels of Less Than 100 Gross...

  1. 46 CFR 169.678 - Main distribution panels and switchboards.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Main distribution panels and switchboards. 169.678 Section 169.678 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS SAILING SCHOOL VESSELS Machinery and Electrical Electrical Installations Operating at Potentials of 50 Volts Or More on Vessels of Less Than 100 Gross...

  2. The Size Frequency Distribution of Small Main-Belt Asteroids

    NASA Technical Reports Server (NTRS)

    Burt, Brian J.; Trilling, David E.; Hines, Dean C.; Stapelfeldt, Karl R.; Rebull, Luisa M.; Fuentes, Cesar I.; Hulsebus, Alan

    2012-01-01

    The asteroid size distribution informs us about the formation and composition of the Solar System. We build on our previous work in which we harvest serendipitously observed data of the Taurus region and measure the brightness and size distributions of Main-belt asteroids. This is accomplished with the highly sensitive MIPS 24 micron channel. We expect to catalog 104 asteroids, giving us a statistically significant data set. Results from this investigation will allow us to characterize the total population of small, Main-belt asteroids. Here we will present new results on the completeness of our study; on the presence of size distribution variations with inclination and radial distance in the belt; and early result on other archival fields.

  3. The Fossilized Size Distribution of the Main Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Bottke, W. F.; Durda, D.; Nesvorny, D.; Jedicke, R.; Morbidelli, A.

    2004-05-01

    The main asteroid belt evolved into its current state via two processes: dynamical depletion and collisional evolution. During the planet formation epoch, the primordial main belt (PMB) contained several Earth masses of material, enough to allow the asteroids to accrete on relatively short timescales (e.g., Weidenschilling 1977). The present-day main belt, however, only contains 5e-4 Earth masses of material (Petit et al. 2002). To explain this mass loss, we suggest the PMB evolved in the following manner: Planetesimals and planetary embryos accreted (and differentiated) in the PMB during the first few Myr of the solar system. Gravitational perturbations from these embryos dynamically stirred the main belt, enough to initiate fragmentation. When Jupiter reached its full size, some 10 Myr after the solar system's birth, its perturbations, together with those of the embryos, dynamically depleted the main belt region of > 99% of its bodies. Much of this material was sent to high (e,i) orbits, where it continued to pummel the surviving main belt bodies at high impact velocities for more than 100 Myr. While some differentiated bodies in the PMB were disrupted, most were instead scattered; only small fragments from this population remain. This period of comminution and dynamical evolution in the PMB created, among other things, the main belt's wavy size-frequency distribution, such that it can be considered a "fossil" from this violent early epoch. From this time forward, however, relatively little collisional evolution has taken place in the main belt, consistent with the surprising paucity of prominent asteroid families. We will show that the constraints provided by asteroid families and the shape of the main belt size distribution are essential to obtaining a unique solution from our model's initial conditions. We also use our model results to solve for the asteroid disruption scaling law Q*D, a critical function needed in all planet formation codes that include

  4. The fossilized size distribution of the main asteroid belt

    NASA Astrophysics Data System (ADS)

    Bottke, William F.; Durda, Daniel D.; Nesvorný, David; Jedicke, Robert; Morbidelli, Alessandro; Vokrouhlický, David; Levison, Hal

    2005-05-01

    Planet formation models suggest the primordial main belt experienced a short but intense period of collisional evolution shortly after the formation of planetary embryos. This period is believed to have lasted until Jupiter reached its full size, when dynamical processes (e.g., sweeping resonances, excitation via planetary embryos) ejected most planetesimals from the main belt zone. The few planetesimals left behind continued to undergo comminution at a reduced rate until the present day. We investigated how this scenario affects the main belt size distribution over Solar System history using a collisional evolution model (CoEM) that accounts for these events. CoEM does not explicitly include results from dynamical models, but instead treats the unknown size of the primordial main belt and the nature/timing of its dynamical depletion using innovative but approximate methods. Model constraints were provided by the observed size frequency distribution of the asteroid belt, the observed population of asteroid families, the cratered surface of differentiated Asteroid (4) Vesta, and the relatively constant crater production rate of the Earth and Moon over the last 3 Gyr. Using CoEM, we solved for both the shape of the initial main belt size distribution after accretion and the asteroid disruption scaling law QD∗. In contrast to previous efforts, we find our derived QD∗ function is very similar to results produced by numerical hydrocode simulations of asteroid impacts. Our best fit results suggest the asteroid belt experienced as much comminution over its early history as it has since it reached its low-mass state approximately 3.9-4.5 Ga. These results suggest the main belt's wavy-shaped size-frequency distribution is a "fossil" from this violent early epoch. We find that most diameter D≳120 km asteroids are primordial, with their physical properties likely determined during the accretion epoch. Conversely, most smaller asteroids are byproducts of fragmentation

  5. Gas pockets in a wastewater rising main: a case study.

    PubMed

    Pozos-Estrada, Oscar; Fuentes-Mariles, Oscar A; Pozos-Estrada, Adrian

    2012-01-01

    This paper presents a case study of an existing wastewater rising main (WWRM) in which an extreme transient event produced by simultaneous power failure of the pumps caused the rupture of a 1.2 m (48 in) prestressed concrete cylinder pipe (PCCP), causing an important leakage of sewage. The event and the methodology followed in order to validate the diagnostics of the failure are described. The detail study included in situ observation of the system, experimental investigation in a setup, hydraulic analysis, as well as details of the structural strength of the WWRM. After the extensive investigation and several simulations of fluid transients for different scenarios and flow conditions, it was found that stationary small gas pockets accumulated at high points of the WWRM were identified as the principal contributory factor of the failure. This case study serves as clear warning of the consequences of operating a WWRM with gas pockets at its high points. PMID:22949261

  6. The Fossilized Size Distribution of the Main Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Bottke, W. F.; Durda, D.; Nesvorny, D.; Jedicke, R.; Morbidelli, A.

    2003-05-01

    At present, we do not understand how the main asteroid belt evolved into its current state. During the planet formation epoch, the primordial main belt (PMB) contained several Earth masses of material, enough to allow the asteroids to accrete on relatively short timescales (e.g., Weidenschilling 1977). The present-day main belt, however, only contains 5e-4 Earth masses of material (Petit et al. 2002). Constraints on this evolution come from (i) the observed fragments of differentiated asteroids, (ii) meteorites collected from numerous differentiated parent bodies, (iii) the presence of ˜ 10 prominent asteroid families, (iv) the "wavy" size-frequency distribution of the main belt, which has been shown to be a by-product of substantial collisional evolution (e.g., Durda et al. 1997), and (v) the still-intact crust of (4) Vesta. To explain the contradictions in the above constraints, we suggest the PMB evolved in this fashion: Planetesimals and planetary embryos accreted (and differentiated) in the PMB during the first few Myr of the solar system. Gravitational perturbations from these embryos dynamically stirred the main belt, enough to initiate fragmentation. When Jupiter reached its full size, some 10 Myr after the solar system's birth, its perturbations, together with those of the embryos, dynamically depleted the main belt region of ˜ 99% of its bodies. Much of this material was sent to high (e,i) orbits, where it continued to pummel the surviving main belt bodies at high impact velocities for more than 100 Myr. While some differentiated bodies in the PMB were disrupted, most were instead scattered; only small fragments from this population remain. This period of comminution and dynamical evolution in the PMB created, among other things, the main belt's wavy size distribution, such that it can be considered a "fossil" from this violent early epoch. From this time forward, however, relatively little collisional evolution has taken place in the main belt

  7. Main Ustilaginoidins and Their Distribution in Rice False Smut Balls

    PubMed Central

    Meng, Jiajia; Sun, Weibo; Mao, Ziling; Xu, Dan; Wang, Xiaohan; Lu, Shiqiong; Lai, Daowan; Liu, Yang; Zhou, Ligang; Zhang, Guozhen

    2015-01-01

    Rice false smut has become an increasingly serious fungal disease in rice (Oryza sativa L.) production worldwide. Ustilaginoidins are bis-naphtho-γ-pyrone mycotoxins previously isolated from the rice false smut balls (FSBs) infected by the pathogen Villosiclava virens in rice spikelets on panicles. To investigate the main ustilaginoidins and their distribution in rice FSBs, five main bis-naphtho-γ-pyrones, namely ustilaginoidins A (1), G (2), B (3), I (4) and C (5), were isolated and identified by NMR and high-resolution mass spectrometry as well as by comparison with the data in the literature. The rice FSBs at early, middle and late maturity stages were divided into their different parts and the contents of five main ustilaginoidins for each part were determined by HPLC analysis. The results revealed that the highest levels of ustilaginoidins were in late stage rice FSBs, followed by those at middle stage. Most ustilaginoidins, 96.4% of the total quantity, were distributed in the middle layer at early stage. However, ustilaginoidins were mainly distributed in the outer and middle layers at middle and late stages. Small amounts of ustilaginoidins A (1) and G (2) were found in the inner part of rice FSBs at each maturity stage. The contents of ustilaginoidins A (1) and G (2) without hydroxymethyl groups at C-2 and C-2’ of the γ-pyrone rings in rice FSBs were relatively high at early stage, while the contents of ustilaginoidins B (3), I (4), and C (5) with hydroxymethyl groups at C-2 or C-2’ were relatively high at late stage. PMID:26473920

  8. Gas in developing countries: Volume 1, Main report

    SciTech Connect

    Not Available

    1987-12-17

    When gas is discovered in a developing country, and there is either insufficient to justify an Liquified Natural Gas (LNG) export project, or a surplus over-and-above LNG requirements, what are the problems that hinder its development for the internal market in that country. Are there positive steps that can be taken to facilitate such development. The major focus of this study is therefore on the problems that arise in negotiating and implementing agreements between companies and governments. The asymmetries and differences between the behavior and perceptions of the two groups impinge on the conduct of negotiations and the nature of agreements reached between the parties. Objectives are examined for each group as well as the procedures they follow and the constraints under which they operate. The effect of differences on exploration contracts, on pricing and on fiscal regimes are examined and practical ways in which the different objectives of governments and companies can be reconciled to their mutual advantage are suggested. The report is divided into two parts. This Volume, Part One of the report, contains a synthesis of our views on the issues raised by research, and the main conclusions.

  9. Distribution of the main malaria vectors in Kenya

    PubMed Central

    2010-01-01

    Background A detailed knowledge of the distribution of the main Anopheles malaria vectors in Kenya should guide national vector control strategies. However, contemporary spatial distributions of the locally dominant Anopheles vectors including Anopheles gambiae, Anopheles arabiensis, Anopheles merus, Anopheles funestus, Anopheles pharoensis and Anopheles nili are lacking. The methods and approaches used to assemble contemporary available data on the present distribution of the dominant malaria vectors in Kenya are presented here. Method Primary empirical data from published and unpublished sources were identified for the period 1990 to 2009. Details recorded for each source included the first author, year of publication, report type, survey location name, month and year of survey, the main Anopheles species reported as present and the sampling and identification methods used. Survey locations were geo-positioned using national digital place name archives and on-line geo-referencing resources. The geo-located species-presence data were displayed and described administratively, using first-level administrative units (province), and biologically, based on the predicted spatial margins of Plasmodium falciparum transmission intensity in Kenya for the year 2009. Each geo-located survey site was assigned an urban or rural classification and attributed an altitude value. Results A total of 498 spatially unique descriptions of Anopheles vector species across Kenya sampled between 1990 and 2009 were identified, 53% were obtained from published sources and further communications with authors. More than half (54%) of the sites surveyed were investigated since 2005. A total of 174 sites reported the presence of An. gambiae complex without identification of sibling species. Anopheles arabiensis and An. funestus were the most widely reported at 244 and 265 spatially unique sites respectively with the former showing the most ubiquitous distribution nationally. Anopheles gambiae

  10. The distribution of mantle material among main-belt asteroids

    NASA Astrophysics Data System (ADS)

    DeMeo, Francesca E.; Carry, Benoit; Binzel, Richard P.; Moskovitz, Nicholas; Polishook, David; Burt, Brian J.

    2014-06-01

    We expect there to have been many bodies in the Main Asteroid Belt (MB) sufficiently heated at the time of solar system formation to allow their interiors to differentiate into an iron core and silicate-rich crust and mantle. Evidence for early solar system differentiation includes the diversity of iron meteorites that imply the existence of over 60 distinct parent bodies (Mittlefehldt et al. 2006). Searches have been performed to identify silicate-rich basaltic crust material (spectral V-type asteroids) in the outer MB have been successful (e.g., Roig et al. 2006, Masi et al. 2008, Moskovitz et al. 2008, Solontoi et al. 2012). The olivine-rich mantles of differentiated asteroids should have produced substantially greater volumes (and therefore substantially greater numbers) of remnant asteroids compared with basaltic and iron samples. Yet olivine-rich asteroids (A-types) are one of the rarest asteroid types (Bus & Binzel 2002, DeMeo et al. 2009). An alternative way to search for differentiated bodies that have been heavily or completely disrupted is to identify these spectral A-type asteroids, characterized by a very wide and deep 1 micron absorption indicative of large amounts (> 80%) of olivine. Burbine et al. (1996) proposed that these asteroids are only found among the largest because most were “battered to bits” due to collisions, so smaller A-types were below our detection limit. Using the Sloan Digital Sky Survey Moving Object Catalog to select A-type asteroid candidates, we have conducted a near-infrared spectral survey of asteroids over 12 nights in the near-infrared in an effort to determine the distribution and abundance of crustal and mantle material across the Main Asteroid Belt (MB). From three decades of asteroid spectral observations only ~10 A-type asteroids have been discovered. In our survey we have detected >20 A-type asteroids thus far throughout the belt, tripling the number of known A-types. We present these spectra and their

  11. Size Distribution of Main-Belt Asteroids with High Inclination

    NASA Astrophysics Data System (ADS)

    Terai, Tsuyoshi; Itoh, Yoichi

    2011-04-01

    We investigated the size distribution of high-inclination main-belt asteroids (MBAs) so as to explore asteroid collisional evolution under hypervelocity collisions of around 10 km s-1. We performed a wide-field survey for high-inclination sub-km MBAs using the 8.2-m Subaru Telescope with the Subaru Prime Focus Camera (Suprime-Cam). Suprime-Cam archival data were also used. A total of 616 MBA candidates were detected in an area of 9.0 deg² with a limiting magnitude of 24.0 mag in the SDSS r filter. Most of the candidate diameters were estimated to be smaller than 1 km. We found a scarcity of sub-km MBAs with high inclination. Cumulative size distributions (CSDs) were constructed using Subaru data and published asteroid catalogs. The power-law indexes of the CSDs were 2.17±0.02 for low-inclination (<15°) MBAs and 2.02±0.03 for high-inclination (>15°) MBAs in the 0.7-50 km diameter range. The high-inclination MBAs had a shallower CSD. We also found that the CSD of S-like MBAs had a small slope with high inclination, whereas the slope did not vary with the inclination in the C-like group. The most probable cause of the shallow CSD of the high-inclination S-like MBAs is the large power-law index in the diameter-impact strength curve in hypervelocity collisions. The collisional evolution of MBAs may have advanced with oligopolistic survival during the dynamical excitation phase in the final stage of planet formation.

  12. Orbital Distribution of Main-belt S-type Asteroids

    NASA Astrophysics Data System (ADS)

    Bus, S. J.; Binzel, R. P.; Volquardsen, E. L.; Berghuis, J. L.

    2004-11-01

    We present preliminary results from an ongoing near-infrared spectroscopic survey of silicate-rich asteroids. The goals of this survey are to sample the full range of silicate mineralogies present in the main belt for asteroids with diameters larger than 5 km, and to map the distributions of these mineralogies as functions of orbital elements. Results from this work will help place constraints on conditions in the inner solar system during proto-planetary formation, and on the degree of heating/differentiation that occurred in the asteroid belt. The largest class of silicate-rich asteroids is the S-types. Members of this class have spectra containing diagnostic absorption bands centered near 1- and 2-microns. Variations in these bands are indicative of a wide range in pyroxene/olivine compositions (i.e. Gaffey et al. 1993, Icarus 106, 573). Our study of the S-type asteroids combines visible-wavelength spectra from the SMASSII survey (Bus and Binzel 2002, Icarus 158, 106) with high S/N near-IR (0.8 - 2.5 micron) spectra that are being obtained with SpeX (Rayner et al. 2003, PASP 115, 362) at the NASA Infrared Telescope Facility. The analysis presented here uses both band-parameter measurements (Cloutis et al. 1986, JGR 91, 11641) and principal component analysis (PCA) to group the S-type asteroids into sub-classes based on their spectral properties and inferred compositions. Based on our present sample of over 150 asteroids, we examine the distributions of these groupings as functions of orbital semi-major axis, eccentricity and inclination. Our goal is to determine the amount of spectral variation present among members of several dynamical families, and to look for larger-scale trends in olivine/pyroxene composition with heliocentric distance that may provide clues about heating across the early asteroid belt. This work was supported by NSF grant AST-0307688.

  13. Flow Distribution Around the SSME Main Injector Assembly Using Porosity Formulation

    NASA Technical Reports Server (NTRS)

    Cheng, Gary C.; Chen, Yen-Sen; Wang, Ten-See

    1995-01-01

    Hot gas turbulent flow distribution around the main injector assembly of the Space Shuttle Main Engine (SSME) and Liquid Oxidizer (LOX) flow distribution through the LOX posts have a great effect on the combustion phenomena inside the main combustion chamber. In order to design a CFD model to be an effective engineering analysis tool with good computational turn-around time (especially for 3-D flow problems) and still maintain good accuracy in describing the flow features, the concept of porosity was employed to describe the effects of blockage and drag force due to the presence of the LOX posts in the turbulent flow field around the main injector assembly of the SSME. 2-D numerical studies were conducted to identify the drag coefficients of the flows both through tube banks and around the shielded posts over a wide range of Reynolds numbers. Empirical, analytical expressions of the drag coefficient as a function of local flow Reynolds number were then deduced. The porosity model was applied to the turbulent flow around the main injector assembly of the SSME, and analyses were performed. The 3-D CFD analysis was divided into three parts, LOX dome, hot gas injector assembly, and hydrogen cavity. The numerical results indicate that the mixture ratio at the downstream of injector face was close to stoichiometric around baffle elements.

  14. Flow Distribution Around the SSME Main Injector Assembly Using Porosity Formulation

    NASA Technical Reports Server (NTRS)

    Cheng, Gary C.; Chen, Yen-Sen; Wang, Ten-See

    1995-01-01

    Hot gas turbulent flow distribution around the main injector assembly of the Space Shuttle Main Engine (SSME) and Liquid Oxidizer (LOX) flow distribution through the LOX posts have a great effect on the combustion phenomena inside the main combustion chamber. In order to design a CFD model to be an effective engineering analysis tool with good computational turn- around time (especially for 3-D flow problems) and still maintain good accuracy in describing the flow features, the concept of porosity was employed to describe the effects of blockage and drag force due to the presence of the LOX posts in the turbulent flow field around the main injector assembly of the SSME. 2-D numerical studies were conducted to identify the drag coefficients of the flows both through tube banks and around the shielded posts over a wide range of Reynolds numbers. Empirical, analytical expressions of the drag coefficient as a function of local flow Reynolds number were then deduced. The porosity model was applied to the turbulent flow around the main injector assembly of the SSME, and analyses were performed. The 3-D CFD analysis was divided into three parts, LOX dome, hot gas injector assembly, and hydrogen cavity. The numerical results indicate that the mixture ratio at the downstream of injector face was close to stoichiometric around baffle elements.

  15. 46 CFR 169.678 - Main distribution panels and switchboards.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... distribution panel to which the generator leads are connected, and from which the electric leads throughout the vessel directly or indirectly receive their electric power is a switchboard. (b) Each switchboard...

  16. Gas main installed under a major four-lane highway

    SciTech Connect

    Tremblay, G.R. )

    1994-06-01

    This paper discusses the design and installation of a natural gas pipeline in Richmond, British Columbia. Because of problems with existing utility lines, pressure requirements, safety concerns, socio-economic interests, it was decided that the only alternative was down the center-line of the highway. The paper reviews the geologic site conditions which favored directional drilling operations along with the actual drilling equipment involved. It reviews the problems encountered and how such problems were overcome.

  17. Condition Assessment for Drinking Water Transmission and Distribution Mains

    EPA Science Inventory

    This project seeks to improve the capability to characterize the condition of water infrastructure. The integrity of buried drinking water mains is critical, as it influences water quality, losses, pressure and cost. This research complements the U.S. Environmental Protection A...

  18. Reconstructing the spin distributions of main-belt asteroids

    NASA Astrophysics Data System (ADS)

    Holsapple, K.

    2014-07-01

    INTRODUCTION: We now have spin data for almost six thousand asteroids, each value being a result of that asteroid's history. Some features of that distribution are now evident. The gravity spin limit at the period of about 2.3 h for asteroids with a diameter greater than a few kilometers is well established (Harris 1996, Pravec and Harris 2000, Holsapple 2001, and others). The strength of smaller asteroids as inferred from the ''fast spinners'' has been presented by Holsapple (2007), Sanchez and Scheeres (2014), and others. Several statistical analyses of the database have been presented (e.g., Pravec and Harris 2002). Here that database is used as a means of investigating the prior history of the asteroid belt. THEORETICAL APPROACHES: A way to understand the data is to attempt to reproduce it using theoretical models and numerical simulations of the physics of the processes that created it. Such studies have evolved since McAdoo and Burns (1973) first suggested collisions as a source of the spins; they include Davis et al. (1979), Dobrovolskis and Burns (1984), Harris (1979), Davis et al. (1989), Farinella et al. (1992), Henych and Pravec (2013), and others. These analyses are based upon averaging the effects of a number of individual impacts into a given target asteroid. I retrace the path and analyses of those authors in this work, but make important modifications and updates. The primary elements introduced in those prior studies include: 1) a population of asteroids in a given space; 2) a distribution of impact velocities and angles; 3) the efficiency of angular-momentum transfer in an impact; 4) the loss or gain of mass and angular inertia; 5) the amount, direction, and speed of the cratering ejecta. The characteristics of the ejecta are especially important: they determine the ''angular-momentum drain'' first identified by Dobrovolskis and Burns (1984). It is caused by the preferential escape of ejecta in the downrange spin direction. Here I revisit, update

  19. Reconstructing the spin distributions of main-belt asteroids

    NASA Astrophysics Data System (ADS)

    Holsapple, K.

    2014-07-01

    INTRODUCTION: We now have spin data for almost six thousand asteroids, each value being a result of that asteroid's history. Some features of that distribution are now evident. The gravity spin limit at the period of about 2.3 h for asteroids with a diameter greater than a few kilometers is well established (Harris 1996, Pravec and Harris 2000, Holsapple 2001, and others). The strength of smaller asteroids as inferred from the ''fast spinners'' has been presented by Holsapple (2007), Sanchez and Scheeres (2014), and others. Several statistical analyses of the database have been presented (e.g., Pravec and Harris 2002). Here that database is used as a means of investigating the prior history of the asteroid belt. THEORETICAL APPROACHES: A way to understand the data is to attempt to reproduce it using theoretical models and numerical simulations of the physics of the processes that created it. Such studies have evolved since McAdoo and Burns (1973) first suggested collisions as a source of the spins; they include Davis et al. (1979), Dobrovolskis and Burns (1984), Harris (1979), Davis et al. (1989), Farinella et al. (1992), Henych and Pravec (2013), and others. These analyses are based upon averaging the effects of a number of individual impacts into a given target asteroid. I retrace the path and analyses of those authors in this work, but make important modifications and updates. The primary elements introduced in those prior studies include: 1) a population of asteroids in a given space; 2) a distribution of impact velocities and angles; 3) the efficiency of angular-momentum transfer in an impact; 4) the loss or gain of mass and angular inertia; 5) the amount, direction, and speed of the cratering ejecta. The characteristics of the ejecta are especially important: they determine the ''angular-momentum drain'' first identified by Dobrovolskis and Burns (1984). It is caused by the preferential escape of ejecta in the downrange spin direction. Here I revisit, update

  20. Ant diversity and distribution in Acadia National Park, Maine.

    PubMed

    Ouellette, Gary D; Drummond, Francis A; Choate, Beth; Groden, Eleanor

    2010-10-01

    Exotic ant species are a primary threat to ant biological diversity, posing a negative impact to native ant communities. In this study, we examine species richness of ants (family Formicidae) in Acadia National Park, ME, as a fundamental step toward understanding the present impact of the exotic species Myrmica rubra on native ant species. Twelve habitat types were sampled, along six transects, with pitfall traps, visual searching, bait traps, and leaf litter extraction, and the aid of 34 volunteers. We report 42 species of ants in Acadia National Park, comprising five subfamilies (Amblyoponinae, Dolichoderinae, Formicinae, Myrmicinae, and Ponerinae) and 15 genera; the cataloged species represents 75% of the species originally recorded in the area by Procter (1946). Our findings suggest M. rubra is currently not a dominant species throughout the entire island. However, where this species has invaded locally, few competing native species coexist. The species Lasius alienus, Formica subsericea, Myrmica detritinodis, Camponotus herculeanus, Formica argentea, Formica aserva, and Tapinoma sessile occurred most often in our survey. We report the ant species Amblyopone pallipes and Dolichoderus mariae as two new records for the state of Maine. PMID:22546439

  1. The Galactic Dense Gas Distribution and Properties

    NASA Astrophysics Data System (ADS)

    Glenn, Jason

    2015-08-01

    As the nearest spiral galaxy, the Milky Way provides a foundation for understanding galactic astrophysics. However, our position within the Galactic plane makes it challenging to decipher the detailed disk structure. The Galactic distribution of dense gas is relatively poorly known; thus, it is difficult to assess models of galaxy evolution by comparison to the Milky Way. Furthermore, fundamental aspects of star formation remain unknown, such as why the stellar and star cluster initial mass functions appear to be ubiquitous.Sub/millimeter dust continuum surveys, coupled with molecular gas surveys, are revealing the 3D distribution and properties of dense, star-forming gas throughout the disk. Here we report on the use of BGPS and Hi-GAL. BGPS is a 1.1 mm survey of the 1st Galactic quadrant and some lines of sight in the 2nd quadrant, totalling 200 deg2. We developed a technique using the Galactic rotation curve to derive distance probability density functions (DPDFs) to molecular cloud structures identified with continuum surveys. DPDFs combine vLSR measures from dense gas tracers and 13CO with distance discriminators, such as 8 μm extinction, HI self absorption, and (l, b, vLSR) associations with objects of known distances. Typical uncertainties are σdist ≤ 1 kpc for 1,710 BGPS objects with well-constrained distances.From DPDFs we derived the dense gas distribution and the dense gas mass function. We find evidence for dense gas in and between putative spiral arms. A log-normal distribution describes the mass function, which ranges from cores to clouds, but is primarily comprised of clumps. High-mass power laws do not fit the entire data set well, although power-law behavior emerges for sources nearer than 6.5 kpc (α = 2.0±0.1) and for objects between 2 kpc and 10 kpc (α = 1.9±0.1). The power law indices are generally between those of GMC and the stellar IMF. We have begun to apply this approach to the Hi-GAL (70 - 500 μm). With coverage of the entire

  2. Measurement of gas distributions from PRS nozzles

    SciTech Connect

    Weber, B.V.; Stephanakis, S.J.; Commisso, R.J.; Fisher, A. Peterson, G.G.

    1997-05-01

    A high-sensitivity laser interferometer has been used to measure gas distributions from nozzles used in high-power plasma radiation source experiments. These measurements are important for determining experimental parameters and for modeling implosions. The integral of the gas density along the laser beam line of sight is measured as a function of time at one axial distance, z, and one radial displacement, r. The nozzle is moved to scan the (r,z) cross section. The measurements are Abel-inverted to compute the local density n(r,z,t). Several examples are shown to illustrate the technique. {copyright} {ital 1997 American Institute of Physics.}

  3. Measurement of gas distributions from PRS nozzles

    SciTech Connect

    Weber, B. V.; Stephanakis, S. J.; Commisso, R. J.; Fisher, A.; Peterson, G. G.

    1997-05-05

    A high-sensitivity laser interferometer has been used to measure gas distributions from nozzles used in high-power plasma radiation source experiments. These measurements are important for determining experimental parameters and for modeling implosions. The integral of the gas density along the laser beam line of sight is measured as a function of time at one axial distance, z, and one radial displacement, r. The nozzle is moved to scan the (r,z) cross section. The measurements are Abel-inverted to compute the local density n(r,z,t). Several examples are shown to illustrate the technique.

  4. Radon gas distribution in natural gas processing facilities and workplace air environment.

    PubMed

    Al-Masri, M S; Shwiekani, R

    2008-04-01

    Evaluation was made of the distribution of radon gas and radiation exposure rates in the four main natural gas treatment facilities in Syria. The results showed that radiation exposure rates at contact of all equipment were within the natural levels (0.09-0.1 microSvh(-1)) except for the reflex pumps where a dose rate value of 3 microSvh(-1) was recorded. Radon concentrations in Syrian natural gas varied between 15.4 Bq m(-3) and 1141 Bq m(-3); natural gas associated with oil production was found to contain higher concentrations than the non-associated natural gas. In addition, radon concentrations were higher in the central processing facilities than the wellheads; these high levels are due to pressurizing and concentrating processes that enhance radon gas and its decay products. Moreover, the lowest 222Rn concentration was in the natural gas fraction used for producing sulfur; a value of 80 Bq m(-3) was observed. On the other hand, maximum radon gas and its decay product concentrations in workplace air environments were found to be relatively high in the gas analysis laboratories; a value of 458 Bq m(-3) was observed. However, all reported levels in the workplaces in the four main stations were below the action level set by IAEA for chronic exposure situations involving radon, which is 1000 Bq m(-3). PMID:17905489

  5. Sour gas distribution in the Amudaria Basin, Central Asia

    SciTech Connect

    Marina, D.; Ivlev, A.; Shkutnik, E.

    1995-08-01

    The Amudaria Basin is the main sour-gas bearing region in Central Asia. In this region, sour gases occur in Upper Jurassic carbonate-reservoir rocks as well as in terrigenous rocks of Cretareous age, but the Upper Jurassic sulfate-carbonate complex is the main sour-gas bearing and producing complex. The chemical and isotopic composition of fluids in Upper Jurassic rocks show that sulfate reduction is the main process responsible for sour gas formation in the central part of the basin, where Kimmeridgian-Tithonian evaporites occur. The H{sub 2}S content of gases varies widely (0 to 10 percent by volume), even within similar carbonate traps located close to one another in the same temperature zone. Analyses of sour-gas distribution and composition in fluids in these areas indicate the main factors which control the variation of H{sub 2}S content in Upper Jurassic hydrocarbon pools in the same temperature zones. These factors include (1) the carbonate sediment facies type (shelf, barrier reef, deep water facies), and (2) within the same facies, the characteristics of traps and pools (tight, gentle, structural, phase-type, etc). The most favorable conditions for H{sub 2}S accumulation occur in hydrocarbon pools confined to the barrier reef flat and the parts of the shelf closest to it. The least favorable conditions are in pools confined to local reefs or carbonate build-ups located within the deep-water facies zone. These results are important for the prediction of H{sub 2}S in hydrocarbon pools. In most cases, H{sub 2}S in the Cretaceous complex is epigenetic. With the exception of Central Karakum zone H{sub 2}S distribution in this complex depends on the distribution and composition of Upper Jurassic evaporites.

  6. Gas distribution and starbursts in shell galaxies

    NASA Technical Reports Server (NTRS)

    Weil, Melinda L.; Hernquist, Lars

    1993-01-01

    Detailed maps of most elliptical galaxies reveal that, whereas the greatest part of their luminous mass originates from a smooth distribution with a surface brightness approximated by a de Vaucouleurs law, a small percentage of their light is contributed by low surface brightness distortions termed 'fine structures'. The sharp-edged features called 'shells' are successfully reproduced by merger and infall models involving accretion from less massive companions. In this context, dwarf spheroidal and compact disk galaxies are likely progenitors of these stellar phenomena. However, it is probable that the sources of shell-forming material also contain significant amounts of gas. This component may play an important role in constraining the formation and evolution of shell galaxies. To investigate the effects of the gaseous component, numerical simulations were performed to study the tidal disruption of dwarf galaxies containing both gas and stars by more massive primaries, and the evolution of the ensuing debris. The calculations were performed with a hybrid N-body/hydrodynamics code. Collisionless matter is evolved using a conventional N-body technique and gas is treated using smoothed particle hydrodynamics in which self-gravitating fluid elements are represented as particles evolving according to Lagrangian hydrodynamic equations. An isothermal equation of state is employed so the gas remains at a temperature 104 K. Owing to the large mass ratio between the primary and companion, the primary is modeled as a rigid potential and the self-gravity of both galaxies is neglected.

  7. Numerical analysis of flow in the hot gas manifold of the Space Shuttle main engine

    NASA Technical Reports Server (NTRS)

    Owens, S. F.; Mukerjee, T.; Singhal, A. K.; Przekwas, A. J.; Glynn, D. R.; Costes, N. C.

    1986-01-01

    This paper presents a numerical model and results of analyses carried out to characterize the flow through the two duct configuration of the Hot Gas Manifold of the Space Shuttle Main Engine. Three dimensional computations have been performed for a half-scale air test model using a nonorthogonal body-fitted coordinate system. The calculation domain is extended from the inlet of the turnaround duct to the exit of the transfer duct. Three test cases, one for laminar flow and two for turbulent flow, have been considered. For turbulent flows, constant eddy viscosity and the k-epsilon model of turbulence were employed. As expected, laminar flow calculation predicts much larger pressure drop than turbulent flow cases. The turbulent flow results are in good agreement with the available flow-visualization data. This study and experimental data indicate that the two-transfer duct design will significantly improve the flow distribution in the Hot Gas Manifold and thereby enhance the overall performance of the SSME.

  8. Preliminary analysis of selected gas dynamic problems. [space shuttle main engine main combustion transients and IUS nozzle flow

    NASA Technical Reports Server (NTRS)

    Prozan, R. J.; Farmer, R. C.

    1985-01-01

    The VAST computer code was used to analyze SSME main combustion chamber start-up transients and the IUS flow field for a damaged nozzle was investigated to better understand the gas dynamic considerations involved in vehicle problems, the effect of start transients on the nozzle flow field for the SSME, and the possibility that a damaged nozzle could account for the acceleration anomaly noted on IUS burn. The results obtained were compared with a method of characteristics prediction. Pressure solutions from both codes were in very good agreement and the Mach number solution on the nozzle centerline deviates substantially for the high expansions for the SSME. Since this deviation was unexpected, the phenomenon is being further examined.

  9. Subaru Main Belt Asteroid Survey (SMBAS)—Size and color distributions of small main-belt asteroids

    NASA Astrophysics Data System (ADS)

    Yoshida, F.; Nakamura, T.

    2007-06-01

    Since February, 2001, we have been conducting a series of survey observations to investigate the physical property of very small Main Belt Asteroids (sub-km MBAs) using the Subaru prime-focus camera (Suprime-Cam) attached to the 8.2 m Subaru telescope. We call our surveys "SMBAS: Subaru Main-Belt Asteroids Survey". This paper presents the results of the second SMBAS (SMBAS-II) which was performed in October 2001. In SMBAS-II, a˜4.0deg2 sky area near the opposition and near the ecliptic was surveyed with the R- and B-bands. We detected 1838 moving objects up to R˜25mag. In SMBAS-II, we could not determine the exact orbits of the objects, because of the short observational arc of only ˜40min. Instead, we statistically estimated the semi-major axis ( a) of each moving object from its apparent sky-motion vector assuming its circular orbit and then, we used the a's to select MBAs and to estimate their absolute magnitudes ( H). The limiting magnitude of SMBAS-II for MBAs was R˜24.2 mag. It corresponds to H˜20 mag at the outer edge of main belt. Thus, assuming their mean albedos, down to D˜0.3 km of S-type asteroids and 0.6 km of C-type asteroids were detected in SMBAS-II. We found that the slopes ( b) of the cumulative size distribution (CSD) (i.e. N(>D)∝D, D: diameter) for sub-km MBAs ranging from 0.6 to 1 km in diameter is 1.29±0.02. Our b value (1.29) is much shallower than those ( ˜ 1.8) of the Palomer Leiden Survey (PLS) [van Houten, C.J., van Houten, G.I., Herget, P., Gehrels, T., 1970. The Palomar-Leiden survey of faint minor planets. Astr. Astrophys. Suppl. 2, 339-448] and Spacewatch surveys [Jedicke, R., Metcalfe, T.S., 1998. The orbital and absolute magnitude distributions of main belt asteroids. Icarus 131, 245-260.] for larger asteroids ( D>5 km) and almost consistent with that (1.3) of SDSS [Ivezić, Ž., Tabachnik, S., Rafikov, R., Lupton, R.H., Quinn, T., Hammergren, M., Eyer, L., Chu, J., Armstrong, J.C., Fan, X., Finlator, K., Geballe, T

  10. Inspiratory flow and intrapulmonary gas distribution

    SciTech Connect

    Rehder, K.; Knopp, T.J.; Brusasco, V.; Didier, E.P.

    1981-01-01

    The effect of flow of inspired gas on intrapulmonary gas distribution was examined by analysis of regional pulmonary /sup 133/Xe clearances and of total pulmonary /sup 133/Xe clearance measured at the mouth after equilibration of the lungs with /sup 133/Xe. Five awake healthy volunteers (24 to 40 yr of age) and another 5 healthy, anesthetized-paralyzed volunteers (26 to 28 yr of age) were studied while they were in the right lateral decubitus position. The awake subjects were studied at 3 inspiratory flows (0.4, 0.7, and 1.0 L/s) and the anesthetized-paralyzed subjects at 4 inspiratory flows (0.2, 0.5, 1.1, and 1.6 L/s). Interregional differences in /sup 133/Xe clearances along the vertical axis were significantly less during anesthesia-paralysis and mechanical ventilation than during spontaneous breathing in the awake state. No differences in the regional or total pulmonary /sup 133/Xe clearances were detected at these different flows in either of the two states, i.e., the difference between the awake and anesthetized-paralyzed states persisted.

  11. Karst hazard assessment in the design of the main gas pipeline (South Yakutia)

    NASA Astrophysics Data System (ADS)

    Strokova, L. A.; Dutova, E. M.; Ermolaeva, A. V.; Alimova, I. N.; Strelnikova, A. B.

    2015-11-01

    The paper represents the description of the zonal and regional geological factors of geoengineering conditions which characterize the territory in South Yakutia crossed by the designed main gas pipeline. Cryogenic processes and karst are considered to be the most dangerous hazards for gas pipeline maintenance. Karst hazard assessment of the gas pipeline section made in the course of the research has involved a complex of geological methods: geoengineering, geophysical, hydrogeological, and mapping. Sections prone to karst development have been identified. The authors have suggested the measures to protect potentially hazardous sections and to ensure timely informing on sinkhole collapses.

  12. Recent and historical distributions of Canada lynx in Maine and the Northeast

    USGS Publications Warehouse

    Hoving, C.L.; Joseph, R.A.; Krohn, W.B.

    2003-01-01

    The contiguous United States population of Canada lynx (Lynx canadensis Kerr) is listed as threatened under the federal Endangered Species Act. However, the historic distribution of lynx in the Northeast is poorly understood. We used museum records, bibliographic records, and interviews to reconstruct the past distribution of lynx in Maine, which is at the current southern limit of the species' distribution in the eastern United States. We found a total of 118 records, representing at least 509 lynx in Maine. Lynx were observed throughout Maine, 1833-1912, with the exception of coastal areas. After 1913, lynx were most common in the forests of western and northern Maine, and absent to rare along the coast, but had not returned to southern Maine by 1999. Thirty-nine kittens representing at least 21 litters were distributed throughout northern and western Maine, 1864-1999. Populations apparently fluctuated, and in some years 200-300 lynx were harvested in Maine. Prior to the 1900s, lynx were much more widely distributed in the Northeast, ranging from Pennsylvania north into Quebec. Because Canada lynx have had a long presence in northern New England, and at times were relatively common, this species merits serious consideration in conservation planning in this region.

  13. 157. ARAIII Reactor building (ARA608) Main gas loop mechanical flow ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    157. ARA-III Reactor building (ARA-608) Main gas loop mechanical flow sheet. This drawing was selected as a typical example of mechanical arrangements within reactor building. Aerojet-general 880-area/GCRE-0608-50-013-102634. - Idaho National Engineering Laboratory, Army Reactors Experimental Area, Scoville, Butte County, ID

  14. Main fans for wood-gas systems: evaluation and design. Special report

    SciTech Connect

    Hose, F.R.

    1985-03-01

    The performance of a centrifugal fan, which had been successfully used as the main fan of a wood-gas system, was measured under a variety of test conditions. The aim of the tests was to derive a fan characteristic curve that allows the evaluation or prediction of fan performance under different circumstances. In addition, information on impeller materials have been included.

  15. Electrical Conduit Distributes Weld Gas Evenly

    NASA Technical Reports Server (NTRS)

    Ambrisco, D. P.

    1983-01-01

    Purge-gas distributor, made from flexible electrical conduit by drilling small holes along its length, provides even gas flow for welding. Flexible conduit adjusts to accomodate almost any shape and is used for gas coverage in other applications that previously needed formed and drilled solid tubing.

  16. Clouds and trace gas distributions during TRACE-P

    NASA Astrophysics Data System (ADS)

    Crawford, J.; Olson, J.; Davis, D.; Chen, G.; Barrick, J.; Shetter, R.; Lefer, B.; Jordan, C.; Anderson, B.; Clarke, A.; Sachse, G.; Blake, D.; Singh, H.; Sandolm, S.; Tan, D.; Kondo, Y.; Avery, M.; Flocke, F.; Eisele, F.; Mauldin, L.; Zondlo, M.; Brune, W.; Harder, H.; Martinez, M.; Talbot, R.; Bandy, A.; Thornton, D.

    2003-11-01

    This paper addresses the question: To what extent do trace gas distributions correspond to cloudiness? Observations taken during NASA's TRACE-P experiment indicate that there can be statistically significant differences in trace gas concentrations between clear-sky and cloudy areas. During the TRACE-P mission, frontal outflow of Asian emissions from the Pacific Rim to the western, North Pacific was sampled by NASA's DC-8 and P-3B aircraft. On several occasions, enhanced CO mixing ratios were observed in and around frontal clouds. A more detailed analysis of trace gas distributions revealed CO enhancements of 30% in the lower free troposphere (1-5 km) for cloudy regions as compared to clear areas. These enhancements exist within clouds as well as above and below clouds. In the upper free troposphere (5-11 km), overall enhancement in CO of 15% was observed although enhancements are mainly restricted to observations within clouds. These in-cloud observations were enhanced by factors of 1.5 to 2 over clear air data. Similar enhancements were seen for many other anthropogenic tracers. By contrast, distributions for O3 revealed no clear differences between cloudy and clear regions suggesting that other influences (e.g., stratosphere-troposphere exchange) might complicate any correspondence with local cloudiness. Expected cloud influences on oxidation chemistry were evident in enhanced OH concentrations above clouds and depressed OH below clouds. These findings are particularly relevant to current and future satellite investigations of the troposphere. Understanding the potential biases created by the inability to probe cloudy regions will improve the interpretation of regional and globally averaged satellite observations.

  17. Natural Gas Hydrates: Occurrence, Distribution, and Detection

    NASA Astrophysics Data System (ADS)

    Paull, Charles K.; Dillon, William P.

    We publish this volume at a time when there is a growing interest in gas hydrates and major expansion in international research efforts. The first recognition of natural gas hydrate on land in Arctic conditions was in the mid-1960s (by I. Makogon) and in the seabed environment only in the early 1970s, after natural seafloor gas hydrate was drilled on the Blake Ridge during Deep Sea Drilling Project Leg 11. Initial scientific investigations were slow to develop because the study of natural gas hydrates is unusually challenging. Gas hydrate exists in nature in conditions of temperature and pressure where human beings cannot survive, and if gas hydrate is transported from its region of stability to normal Earth-surface conditions, it dissociates. Thus, in contrast to most minerals, we cannot depend on drilled samples to provide accurate estimates of the amount of gas hydrate present. Even the heat and changes in chemistry (methane saturation, salinity, etc.) introduced by the drilling process affect the gas hydrate, independent of the changes brought about by moving a sample to the surface. Gas hydrate has been identified in nature generally by inference from indirect evidence in drilling data or by using remotely sensed indications, mostly from seismic data. Obviously, the established techniques ofgeologic analysis, which require direct observation and sampling, do not apply to gas hydrate studies, and controversy has surrounded many interpretations. Pressure/temperature conditions appropriate for the existence of gas hydrate occur over the greater part of the shallow subsurface of the Earth beneath the ocean at water depths exceeding about 500 m (shallower beneath colder Arctic seas) and on land beneath high-latitude permafrost. Gas hydrate actually will be present in such conditions, however, only where methane is present at high concentrations. In the Arctic, these methane concentrations are often associated with petroleum deposits, whereas at continental margins

  18. Neotectonics, sea level change, and Quaternary natural gas occurrence in coastal Maine

    SciTech Connect

    Kelly, J.T.; Belknap, D.F.; Shipp, C.R.

    1985-02-01

    The glaciated, passive continental margin of northern New England is not a likely location for either tectonic activity or hydrocarbon accumulation, but neotectonic action has played a role in creating favorable stratigraphic traps for natural gas in the Quaternary inner-shelf and estuarine deposits of Maine. During late glacial time (13,000 year B.P.), a marine inundation accompanied ice retreat across the isostatically depressed lowlands of coastal Maine and blanketed the area with marine sediment (Presumpscot Formation) up to 50 m thick. Unloading of the ice led to rapid coastal rebound within a few thousand years, and the former sea floor became emergent to present depths of -65 m. A gullied and weathered lag surface on the muddy Presumpscot Formation marks the regression that followed deposition. Since about 8000 years B.P., sea level has risen in Maine, and within historic times it has been accompanied by seismicity and subsidence rates up to 9 mm/yr. Examinations of over 1500 km of seismic reflection profiles and limited coring reveal the presence of abundant natural gas in Holocene sediments filling ravines cut into the Presumpscot Formation during emergence. It appears that the gas is derived from and trapped by mud deposited in estuarine depocenters that migrated landward during the Holocene transgression.

  19. Is the Grand Tack model compatible with the orbital distribution of main belt asteroids?

    NASA Astrophysics Data System (ADS)

    Deienno, Rogerio; Gomes, Rodney S.; Walsh, Kevin J.; Morbidelli, Alessandro; Nesvorný, David

    2016-07-01

    The Asteroid Belt is characterized by the radial mixing of bodies with different physical properties, a very low mass compared to Minimum Mass Solar Nebula expectations and has an excited orbital distribution, with eccentricities and inclinations covering the entire range of values allowed by the constraints of dynamical stability. Models of the evolution of the Asteroid Belt show that the origin of its structure is strongly linked to the process of terrestrial planet formation. The Grand Tack model presents a possible solution to the conundrum of reconciling the small mass of Mars with the properties of the Asteroid Belt, including the mass depletion, radial mixing and orbital excitation. However, while the inclination distribution produced in the Grand Tack model is in good agreement with the one observed, the eccentricity distribution is skewed towards values larger than those found today. Here, we evaluate the evolution of the orbital properties of the Asteroid Belt from the end of the Grand Tack model (at the end of the gas nebula phase when planets emerge from the dispersing gas disk), throughout the subsequent evolution of the Solar System including an instability of the Giant Planets approximately 400 Myr later. Before the instability, the terrestrial planets were modeled on dynamically cold orbits with Jupiter and Saturn locked in a 3:2 mean motion resonance. The model continues for an additional 4.1 Gyr after the giant planet instability. Our results show that the eccentricity distribution obtained in the Grand Tack model evolves towards one very similar to that currently observed, and the semimajor axis distribution does the same. The inclination distribution remains nearly unchanged with a slight preference for depletion at low inclination; this leads to the conclusion that the inclination distribution at the end of the Grand Tack is a bit over-excited. Also, we constrain the primordial eccentricities of Jupiter and Saturn, which have a major influence

  20. Progress on the Size Frequency Distribution of Small Main-belt Asteroids

    NASA Astrophysics Data System (ADS)

    Burt, Brian; Trilling, D. E.; Hines, D. C.; Stapelfeldt, K. R.; Rebull, L. M.; Fuentes, C. I.; Hulsebus, A.

    2012-10-01

    The asteroid size distribution informs us about the formation and composition of the Solar System. We build on our previous work in which we harvest serendipitously obtained Spitzer data of the Taurus region and measure the brightness and size distributions of Main-belt asteroids. This is accomplished with the highly sensitive MIPS 24 micron channel. We expect to catalog 104 asteroids, giving us a statistically significant data set. Results from this investigation will allow us to characterize the total population of small, Main-belt asteroids. Here we will present new results on the completeness of our study and the presence of size distribution variations with inclination and radial distance in the belt. We acknowledge and thank funding from PMDAP through NASA.

  1. On the current distribution of main belt objects: Constraints for evolutionary models

    NASA Astrophysics Data System (ADS)

    Michtchenko, T. A.; Lazzaro, D.; Carvano, J. M.

    2016-04-01

    Context. It is widely accepted that the current distribution of material in the main asteroidal belt (MB) is a product of the evolutionary history of the solar system during its whole lifetime of ~4.5 billions of years and is, consequently, a major witness of the diverse stages of this evolution. Aims: The purpose of this paper is twofold: first, we study the principal aspects of the distribution of the asteroids in proper element space, mass, and, physical composition for a complete picture of the current MB. Second, we analyze if and how these current distributions can be explained by the long-lasting dynamical effects of the planets on this region of the solar system. Methods: We studied the distribution in the proper element space for the sample that consists of about 350 000 objects whose proper orbital elements are available from the database AstDyS. We studied the distribution in size and physical composition using the most recent and large available datasets. We constructed the dynamical portrait of the MB in form of the dynamical and averaged maps via the spectral analysis method. Results: The main properties of the current distributions of MB objects are identified. A comparison of the distributions of real objects with dynamical maps allows us to detect principal mechanisms of the diffusive transportation of the objects. These mechanisms are related to mean-motion resonances (MMRs) and secular resonances (SRs), overlaying with the slow dissipative Yarkovsky/Yorp drift. Conclusions: We identify the most relevant distributions of the material in the MB and show that many of the current features of the MB can be explained by the interplay of diverse dynamical mechanisms due to the planetary perturbations over 4 Gyr with nongravitational effects, without the need of 'catastrophic' events or 'ad hoc' migration mechanisms during the early stages of the solar system. In this sense, the obtained distributions can provide relevant constraints for modeling the

  2. Particle size distribution of main-channel-bed sediments along the upper Mississippi River, USA

    USGS Publications Warehouse

    Remo, Jonathan; Heine, Ruben A.; Ickes, Brian

    2016-01-01

    In this study, we compared pre-lock-and-dam (ca. 1925) with a modern longitudinal survey of main-channel-bed sediments along a 740-km segment of the upper Mississippi River (UMR) between Davenport, IA, and Cairo, IL. This comparison was undertaken to gain a better understanding of how bed sediments are distributed longitudinally and to assess change since the completion of the UMR lock and dam navigation system and Missouri River dams (i.e., mid-twentieth century). The comparison of the historic and modern longitudinal bed sediment surveys showed similar bed sediment sizes and distributions along the study segment with the majority (> 90%) of bed sediment samples having a median diameter (D50) of fine to coarse sand. The fine tail (≤ D10) of the sediment size distributions was very fine to medium sand, and the coarse tail (≥ D90) of sediment-size distribution was coarse sand to gravel. Coarsest sediments in both surveys were found within or immediately downstream of bedrock-floored reaches. Statistical analysis revealed that the particle-size distributions between the survey samples were statistically identical, suggesting no overall difference in main-channel-bed sediment-size distribution between 1925 and present. This was a surprising result given the magnitude of river engineering undertaken along the study segment over the past ~ 90 years. The absence of substantial differences in main-channel-bed-sediment size suggests that flow competencies within the highly engineered navigation channel today are similar to conditions within the less-engineered historic channel.

  3. Particle size distribution of main-channel-bed sediments along the upper Mississippi River, USA

    NASA Astrophysics Data System (ADS)

    Remo, Jonathan W. F.; Heine, Reuben A.; Ickes, Brian S.

    2016-07-01

    In this study, we compared pre-lock-and-dam (ca. 1925) with a modern longitudinal survey of main-channel-bed sediments along a 740-km segment of the upper Mississippi River (UMR) between Davenport, IA, and Cairo, IL. This comparison was undertaken to gain a better understanding of how bed sediments are distributed longitudinally and to assess change since the completion of the UMR lock and dam navigation system and Missouri River dams (i.e., mid-twentieth century). The comparison of the historic and modern longitudinal bed sediment surveys showed similar bed sediment sizes and distributions along the study segment with the majority (> 90%) of bed sediment samples having a median diameter (D50) of fine to coarse sand. The fine tail (≤ D10) of the sediment size distributions was very fine to medium sand, and the coarse tail (≥ D90) of sediment-size distribution was coarse sand to gravel. Coarsest sediments in both surveys were found within or immediately downstream of bedrock-floored reaches. Statistical analysis revealed that the particle-size distributions between the survey samples were statistically identical, suggesting no overall difference in main-channel-bed sediment-size distribution between 1925 and present. This was a surprising result given the magnitude of river engineering undertaken along the study segment over the past ~ 90 years. The absence of substantial differences in main-channel-bed-sediment size suggests that flow competencies within the highly engineered navigation channel today are similar to conditions within the less-engineered historic channel.

  4. Gas Content and Star Formation Efficiency of Massive Main Sequence Galaxies at z~3-4

    NASA Astrophysics Data System (ADS)

    Schinnerer, Eva; Groves, Brent; Karim, Alexander; Sargent, Mark T.; Oesch, Pascal; Le Fevre, Olivier; Tasca, Lidia; Magnelli, Benjamin; Cassata, Paolo; Smolcic, Vernesa

    2016-01-01

    Recent observations have shown that the neutral gas content and star formation efficiency of massive (with log(stellar masses) > 10), normal star forming galaxies, i.e. they reside on the main sequence of star forming galaxies, are steadily decreasing from the peak of star formation activity (at redshifts of z~2) till today. This decrease is coincident with the observed decline in the cosmic star formation rate density over this time range. However, only few observations have probed the evolution of the gas content and star formation efficiency beyond this peak epoch when the cosmic star formation rate density has been increasing, i.e. at redshifts of z~3-4.We will present new ALMA rest-frame 250um continuum detections of 45 massive, normal star forming galaxies in this critical redshift interval selected in the COSMOS deep field. Using the sub-mm continnum as proxy for the cold neutral gas content, we find gas mass fractions and depletions similar to those reported during the peak epoch of star formation. We will discuss our findings in the context of results from lower redshift observations and model expectations.

  5. The relations between natural gas hydrate distribution and structure on Muli basin Qinghai province

    NASA Astrophysics Data System (ADS)

    Yu, C.; Li, Y.; Lu, Z.; Luo, S.; Qu, C.; Tan, S.; Zhang, P.

    2014-12-01

    The Muli area is located in a depression area which between middle Qilian and south Qilian tectonic elements. The natural gas hydrate stratum belongs the Jurassic series coal formation stratum, the main lithological character clamps the purple mudstone, the siltstone, the fine grain sandstone and the black charcoal mudstone for the green gray. The plutonic metamorphism is primarily deterioration function of the Muli area coal, is advantageous in forming the coal-bed gas. Cretaceous system, the Paleogene System and Neogene System mainly include the fine grain red clastic rock and clay stone. The distribution of Quaternary is widespread. The ice water - proluvial and glacier deposit are primarily depositional mode. The Qilian Montanan Muli permafrost area has the good gas source condition (Youhai Zhu 2006) and rich water resources. It is advantage to forming the natural gas hydrate. The natural gas hydrate is one kind of new latent energy, widely distributes in the mainland marginal sea bottom settlings and land permanent tundra. Through researching the area the structure ,the deposition carries on the analysis and responds the characteristic analysis simulation in the rock physics analysis and the seismic in the foundation, and then the reflected seismic data carried by tectonic analysis processing and the AVO characteristic analysis processing reveal that the research area existence natural gas hydrate (already by drilling confirmation) and the natural gas hydrate distribution and the structure relations is extremely close. In the structure development area, the fault and the crevasse crack growing, the natural gas hydrate distribution characteristic is obvious (this is also confirmed the storing space of natural gas hydrate in this area is mainly crevasse crack). This conclusion also agree with the actual drilling result. The research prove that the distribution of natural gas hydrate in this area is mainly controlled by structure control. The possibility of fault

  6. Spatial concentration distribution model for short-range continuous gas leakage of small amount

    NASA Astrophysics Data System (ADS)

    Wang, Meirong; Wang, Lingxue; Li, Jiakun; Long, Yunting; Gao, Yue

    2012-06-01

    Passive infrared gas imaging systems have been utilized in the equipment leak detection and repair in chemical manufacturers and petroleum refineries. The detection performance mainly relates to the sensitivity of infrared detector, optical depth of gas, atmospheric transmission, wind speed, and so on. Based on our knowledge, the spatial concentration distribution of continuously leaking gas plays an important part in leak detection. Several computational model of gas diffusion were proposed by researchers, such as Gaussian model, BM model, Sutton model and FEM3 model. But these models focus on calculating a large scale gas concentration distribution for a great amount of gas leaks above over 100- meter height, and not applicable to assess detection limit of a gas imaging system in short range. In this paper, a wind tunnel experiment is designed. Under different leaking rate and wind speed, concentration in different spatial positions is measured by portable gas detectors. Through analyzing the experimental data, the two parameters σy(x) and σz (x) that determine the plume dispersion in Gaussian model are adjusted to produce the best curve fit to the gas concentration data. Then a concentration distribution model for small mount gas leakage in short range is established. Various gases, ethylene and methane are used to testify this model.

  7. Leaf gas films, underwater photosynthesis and plant species distributions in a flood gradient.

    PubMed

    Winkel, Anders; Visser, Eric J W; Colmer, Timothy D; Brodersen, Klaus P; Voesenek, Laurentius A C J; Sand-Jensen, Kaj; Pedersen, Ole

    2016-07-01

    Traits for survival during flooding of terrestrial plants include stimulation or inhibition of shoot elongation, aerenchyma formation and efficient gas exchange. Leaf gas films form on superhydrophobic cuticles during submergence and enhance underwater gas exchange. The main hypothesis tested was that the presence of leaf gas films influences the distribution of plant species along a natural flood gradient. We conducted laboratory experiments and field observations on species distributed along a natural flood gradient. We measured presence or absence of leaf gas films and specific leaf area of 95 species. We also measured, gas film retention time during submergence and underwater net photosynthesis and dark respiration of 25 target species. The presence of a leaf gas film was inversely correlated to flood frequency and duration and reached a maximum value of 80% of the species in the rarely flooded locations. This relationship was primarily driven by grasses that all, independently of their field location along the flood gradient, possess gas films when submerged. Although the present study and earlier experiments have shown that leaf gas films enhance gas exchange of submerged plants, the ability of species to form leaf gas films did not show the hypothesized relationship with species composition along the flood gradient. PMID:26846194

  8. Distribution of heavy metals from flue gas in algal bioreactor

    NASA Astrophysics Data System (ADS)

    Napan, Katerine

    Flue gas from coal-fired power plants is a major source of CO2 to the atmosphere. Microalgae can use this enriched form of CO2 as carbon source and in turn the biomass can be used to produce food, feed, fertilizer and biofuels. However, along with CO2, coal-based flue gas will inevitably introduce heavy metals, which have a high affinity to bind algal cells, could be toxic to the organisms and if transferred to the products could limit their uses. This study seeks to address the distribution and impact of heavy metals present in flue gas on microalgae production systems. To comprehend its effects, algae Scenedesmus obliquus was grown in batch reactors in a multimetal system. Ten heavy metals (Cu, Co, Zn, Pb, As, Se, Cr, Hg, Ni and Cd) were selected and were evaluated at four concentrations (1X, 2X, 5X and 10X). Results show that most heavy metals accumulated mainly in biomass and were found in very low concentrations in media. Hg was shown to be lost from the culture, with low amounts present in the biomass. An upper limit for As uptake was observed, suggesting its likelihood to build-up in the system during medium recycle. The As limited bioaccumulation was overcome by addition of sulfur to the algal medium. Heavy metal at 2X, 5X and 10X inhibited both growth and lipid production, while at the reference concentration both biomass and lipids yields were increased. Heavy metal concentrations in the medium and biomass were time dependent, and at the end of the cultivation most heavy metals in the supernatant solution complied with the recommendations for irrigation water, while biomass was below limits for cattle and poultry feed, fertilizer, plastic and paper. This research shows that bioremediation of CO2 and heavy metals in combination with energy production can be integrated, which is an environmentally friendly form of biotechnology.

  9. Fugitive methane emissions from leak-prone natural gas distribution infrastructure in urban environments.

    PubMed

    Hendrick, Margaret F; Ackley, Robert; Sanaie-Movahed, Bahare; Tang, Xiaojing; Phillips, Nathan G

    2016-06-01

    Fugitive emissions from natural gas systems are the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. and contribute to the risk of explosions in urban environments. Here, we report on a survey of CH4 emissions from 100 natural gas leaks in cast iron distribution mains in Metro Boston, MA. Direct measures of CH4 flux from individual leaks ranged from 4.0 - 2.3 × 10(4) g CH4•day(-1). The distribution of leak size is positively skewed, with 7% of leaks contributing 50% of total CH4 emissions measured. We identify parallels in the skewed distribution of leak size found in downstream systems with midstream and upstream stages of the gas process chain. Fixing 'superemitter' leaks will disproportionately stem greenhouse gas emissions. Fifteen percent of leaks surveyed qualified as potentially explosive (Grade 1), and we found no difference in CH4 flux between Grade 1 leaks and all remaining leaks surveyed (p = 0.24). All leaks must be addressed, as even small leaks cannot be disregarded as 'safely leaking.' Key methodological impediments to quantifying and addressing the impacts of leaking natural gas distribution infrastructure involve inconsistencies in the manner in which gas leaks are defined, detected, and classified. To address this need, we propose a two-part leak classification system that reflects both the safety and climatic impacts of natural gas leaks. PMID:27023280

  10. COLOR DEPENDENCE IN THE SIZE DISTRIBUTION OF MAIN BELT ASTEROIDS REVISITED

    SciTech Connect

    August, Tyler M.; Wiegert, Paul A.

    2013-06-15

    The size distribution of the asteroid belt is examined with 16956 main belt asteroids detected in data taken from the Canada-France-Hawaii Telescope Legacy Survey in two filters (g' and r'). The cumulative H (absolute magnitude) distribution is examined in both filters, and both match well to simple power laws down to H = 17, with slopes in rough agreement with those reported the literature. This implies that disruptive collisions between asteroids are gravitationally dominated down to at least this size, and probably sub-kilometer scales. The slopes of these distributions appear shallower in the outer belt than the inner belt, and the g' distributions appear slightly steeper than the r'. The slope shallowing in the outer belt may reflect a real compositional difference: the inner asteroid belt has been suggested to consist mostly of stony and/or metallic S-type asteroids, whereas carbonaceous C-types are thought to be more prevalent further from the Sun. No waves are seen in the size distribution above H = 15. Since waves are expected to be produced at the transition from gravitationally-dominated to internal strength-dominated collisions, their absence here may imply that the transition occurs at sub-kilometer scales, much smaller than the H = 17 (diameter {approx} 1.6 km) cutoff of this study.

  11. Long-Range Untethered Real-Time Live Gas Main Robotic Inspection System

    SciTech Connect

    Hagen Schempf; Daphne D'Zurko

    2004-10-31

    Under funding from the Department of Energy (DOE) and the Northeast Gas Association (NGA), Carnegie Mellon University (CMU) developed an untethered, wireless remote controlled inspection robot dubbed Explorer. The project entailed the design and prototyping of a wireless self-powered video-inspection robot capable of accessing live 6- and 8-inch diameter cast-iron and steel mains, while traversing turns and Ts and elbows under real-time control with live video feedback to an operator. The design is that of a segmented actively articulated and wheel-leg powered robot design, with fisheye imaging capability and self-powered battery storage and wireless real-time communication link. The prototype was functionally tested in an above ground pipe-network, in order to debug all mechanical, electrical and software subsystems, and develop the necessary deployment and retrieval, as well as obstacle-handling scripts. A pressurized natural gas test-section was used to certify it for operation in natural gas at up to 60 psig. Two subsequent live-main field-trials in both cast-iron and steel pipe, demonstrated its ability to be safely launched, operated and retrieved under real-world conditions. The system's ability to safely and repeatably exidrecover from angled and vertical launchers, traverse multi-thousand foot long pipe-sections, make T and varied-angle elbow-turns while wirelessly sending live video and handling command and control messages, was clearly demonstrated. Video-inspection was clearly shown to be a viable tool to understand the state of this critical buried infrastructure, irrespective of low- (cast-iron) or high-pressure (steel) conditions. This report covers the different aspects of specifications, requirements, design, prototyping, integration and testing and field-trialing of the Explorer platform.

  12. CARMA LARGE AREA STAR FORMATION SURVEY: STRUCTURE AND KINEMATICS OF DENSE GAS IN SERPENS MAIN

    SciTech Connect

    Lee, Katherine I.; Storm, Shaye; Mundy, Lee G.; Teuben, Peter; Pound, Marc W.; Salter, Demerese M.; Chen, Che-Yu; Fernández-López, Manuel; Looney, Leslie W.; Segura-Cox, Dominique; Rosolowsky, Erik; Arce, Héctor G.; Plunkett, Adele L.; Ostriker, Eve C.; Shirley, Yancy L.; Kwon, Woojin; Kauffmann, Jens; Tobin, John J.; Volgenau, N. H.; Tassis, Konstantinos; and others

    2014-12-20

    We present observations of N{sub 2}H{sup +} (J = 1 → 0), HCO{sup +} (J = 1 → 0), and HCN (J = 1 → 0) toward the Serpens Main molecular cloud from the CARMA Large Area Star Formation Survey (CLASSy). We mapped 150 arcmin{sup 2} of Serpens Main with an angular resolution of ∼7''. The gas emission is concentrated in two subclusters (the NW and SE subclusters). The SE subcluster has more prominent filamentary structures and more complicated kinematics compared to the NW subcluster. The majority of gas in the two subclusters has subsonic to sonic velocity dispersions. We applied a dendrogram technique with N{sub 2}H{sup +}(1-0) to study the gas structures; the SE subcluster has a higher degree of hierarchy than the NW subcluster. Combining the dendrogram and line fitting analyses reveals two distinct relations: a flat relation between nonthermal velocity dispersion and size, and a positive correlation between variation in velocity centroids and size. The two relations imply a characteristic depth of 0.15 pc for the cloud. Furthermore, we have identified six filaments in the SE subcluster. These filaments have lengths of ∼0.2 pc and widths of ∼0.03 pc, which is smaller than a characteristic width of 0.1 pc suggested by Herschel observations. The filaments can be classified into two types based on their properties. The first type, located in the northeast of the SE subcluster, has larger velocity gradients, smaller masses, and nearly critical mass-per-unit-length ratios. The other type, located in the southwest of the SE subcluster, has the opposite properties. Several YSOs are formed along two filaments which have supercritical mass per unit length ratios, while filaments with nearly critical mass-per-unit-length ratios are not associated with YSOs, suggesting that stars are formed on gravitationally unstable filaments.

  13. Model documentation: Natural gas transmission and distribution model of the National Energy Modeling System. Volume 1

    SciTech Connect

    1995-02-17

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of integrated Analysis and Forecasting of the Energy information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. The NGTDM is the model within the NEMS that represents the transmission, distribution, and pricing of natural gas. The model also includes representations of the end-use demand for natural gas, the production of domestic natural gas, and the availability of natural gas traded on the international market based on information received from other NEMS models. The NGTDM determines the flow of natural gas in an aggregate, domestic pipeline network, connecting domestic and foreign supply regions with 12 demand regions. The methodology employed allows the analysis of impacts of regional capacity constraints in the interstate natural gas pipeline network and the identification of pipeline capacity expansion requirements. There is an explicit representation of core and noncore markets for natural gas transmission and distribution services, and the key components of pipeline tariffs are represented in a pricing algorithm. Natural gas pricing and flow patterns are derived by obtaining a market equilibrium across the three main elements of the natural gas market: the supply element, the demand element, and the transmission and distribution network that links them. The NGTDM consists of four modules: the Annual Flow Module, the Capacity F-expansion Module, the Pipeline Tariff Module, and the Distributor Tariff Module. A model abstract is provided in Appendix A.

  14. Two-Phase Refrigerant Flow Distribution in a Multipass Evaporator with Vertical Upward Main Tube

    NASA Astrophysics Data System (ADS)

    Watanabe, Manabu; Katasuta, Masafumi

    In this article, a calculation model that enables to predict two-phaseflow distribution in a multipass evaporator is proposed. The model considers the multipass evaporator as the combination of simple elements, i. e. straight pipes and T-junctions, and utilizes the correlations to predict the pressure drop at the elements. For the T-junction, however, we have so little knowledge, especially for the small diameter T-junction, that we make some experiments to evaluate the existing correlations for the junction pressure drop. We also do not have reliable model for predicting the phase separation characteristics, so that we used the empirical equations for liquid division ratio derived in our previous papers. By this model, gas phase flow distribution to each pass is determined as it makes the pressure at the outlet of each pass equal. Calculation results well predict the previously presented experimental data that were obtained under the condition of larger quality at the header inlet. The suitableness of this model suggests that the complexity of the two-phase flow distribution in multipass tube attributes to the phase separation phenomena in dividing two-phase flow at a T-junction

  15. Gas distribution through injection manifolds in vacuum systems

    NASA Astrophysics Data System (ADS)

    Theil, Jeremy A.

    1995-03-01

    When injecting gas into a vacuum system, quite often the gas is distributed through a gas injection manifold. However, designs normally rely upon practical experience. By considering the manifold arrangement as a network of flow restrictions it is possible to optimize the distribution of gas throughout the manifold. The methodology for determining the flow distribution through the two simplest topologies of gas manifold, single- and double-opening manifolds from a single-gas injection point, is derived in this article. It is shown that the double-opening manifold topology tends to provide more uniform flow distribution than the single-opening manifold topology for similar conductance ratios. The results of this work include a summation formula for the single-opening manifold. In addition, guidelines for one type of tailored flow manifold are given. Finally, three basic design rules are presented: (1) use as few holes in the manifold as possible; (2) use a double opening manifold when possible; and (3) specify tube dimensions such that the tube/spray hole conductance ratio is maximized.

  16. Distribution of the background gas in the MITICA accelerator

    NASA Astrophysics Data System (ADS)

    Sartori, E.; Dal Bello, S.; Serianni, G.; Sonato, P.

    2013-02-01

    MITICA is the ITER neutral beam test facility to be built in Padova for the generation of a 40A D- ion beam with a 16×5×16 array of 1280 beamlets accelerated to 1MV. The background gas pressure distribution and the particle flows inside MITICA accelerator are critical aspects for stripping losses, generation of secondary particles and beam non-uniformities. To keep the stripping losses in the extraction and acceleration stages reasonably low, the source pressure should be 0.3 Pa or less. The gas flow in MITICA accelerator is being studied using a 3D Finite Element code, named Avocado. The gas-wall interaction model is based on the cosine law, and the whole vacuum system geometry is represented by a view factor matrix based on surface discretization and gas property definitions. Pressure distribution and mutual fluxes are then solved linearly. In this paper the result of a numerical simulation is presented, showing the steady-state pressure distribution inside the accelerator when gas enters the system at room temperature. The accelerator model is limited to a horizontal slice 400 mm high (1/4 of the accelerator height). The pressure profile at solid walls and through the beamlet axis is obtained, allowing the evaluation and the discussion of the background gas distribution and nonuniformity. The particle flux at the inlet and outlet boundaries (namely the grounded grid apertures and the lateral conductances respectively) will be discussed.

  17. Energy direct inputs and greenhouse gas emissions of the main industrial trawl fishery of Brazil.

    PubMed

    Port, Dagoberto; Perez, Jose Angel Alvarez; de Menezes, João Thadeu

    2016-06-15

    This study provides first-time estimates of direct fuel inputs and greenhouse gas emissions produced by the trawl fishing fleet operating off southeastern and southern Brazil. Analyzed data comprised vessel characteristics, landings, fishing areas and trawling duration of 10,144 fishing operations monitored in Santa Catarina State from 2003 to 2011. Three main fishing strategies were differentiated: 'shrimp trawling', 'slope trawling' and 'pair trawling'. Jointly these operations burned over 141.5millionl of diesel to land 342.3millionkg of fish and shellfish. Annually, 0.36-0.48l were consumed for every kg of catch landed. Because all fishing strategies relied on multispecific catches to raise total incomes, estimates of fuel use intensity were generally low but increased 316-1025% if only nominal targets were considered. In nine years, trawling operations emitted 104.07GgC to the atmosphere, between 36,800-49,500tons CO2 per year. PMID:27068561

  18. Energy direct inputs and greenhouse gas emissions of the main industrial trawl fishery of Brazil.

    PubMed

    Port, Dagoberto; Perez, Jose Angel Alvarez; de Menezes, João Thadeu

    2014-11-15

    This study provides first-time estimates of direct fuel inputs and greenhouse gas emissions produced by the trawl fishing fleet operating off southeastern and southern Brazil. Analyzed data comprised vessel characteristics, landings, fishing areas and trawling duration of 10,144 fishing operations monitored in Santa Catarina State from 2003 to 2011. Three main fishing strategies were differentiated: 'shrimp trawling', 'slope trawling' and 'pair trawling'. Jointly these operations burned over 9.1 million liters of diesel to land 342.3 million kilograms of fish and shellfish. Annually, 0.023-0.031 l were consumed for every kg of catch landed. Because all fishing strategies relied on multispecific catches to raise total incomes, estimates of fuel use intensity were generally low but increased 200-900% if only nominal targets were considered. In nine years, trawling operations emitted 6.69 GgC to the atmosphere, between 2300 and 3300 tons CO2 per year. PMID:25173595

  19. Geologic framework of oil and gas genesis in main sedimentary basins from Romania Oprea Dicea

    SciTech Connect

    Ionescu, N.; Morariu, C.D. )

    1991-03-01

    Oil and gas fields located in Moldavic nappes are encompassed in Oligocene and lower Miocene formations, mostly in the marginal folds nappe, where Kliwa Sandstone sequences have high porosity, and in the Black Sea Plateau. The origin of the hydrocarbon accumulations from the Carpathian foredeep seems to be connected to the Oligocene-lower Miocene bituminous formations of the marginal folds and sub-Carpathian nappes. In the Gethic depression, the hydrocarbon accumulations originate in Oligocene and Miocene source rocks and host in structural, stratigraphical, and lithological traps. The accumulations connected with tectonic lines that outline the areal extension of the Oligocene, Miocene, and Pliocene formations are in the underthrusted Moesian platform. The hydrocarbon accumulations related to the Carpathian foreland represent about 40% of all known accumulations in Romania. Most of them are located in the Moesian platform. In this unit, the oil and gas fields present a vertical distribution at different stratigraphic levels, from paleozoic to Neogene, and in all types of reservoirs, suggesting multicycles of oleogenesis, migration, accumulation, and sealing conditions. The hydrocarbon deposits known so far on the Black Sea continental plateau are confined in the Albian, Cenomanian, Turonian-Senonian, and Eocene formations. The traps are of complex type structural, lithologic, and stratigraphic. The reservoirs are sandstones, calcareous sandstones, limestones, and sands. The hydrocarbon source rocks are pelitic and siltic Oligocene formations. Other older source rocks are probably Cretaceous.

  20. Volcanic field elongation, vent distribution and tectonic evolution of continental rift: The Main Ethiopian Rift example

    NASA Astrophysics Data System (ADS)

    Mazzarini, Francesco; Le Corvec, Nicolas; Isola, Ilaria; Favalli, Massimiliano

    2015-04-01

    Magmatism and faulting operate in continental rifts and interact at a variety of scales, however their relationship is complex. The African rift, being the best example for both active continental rifting and magmatism, provides the ideal location to study the interplay between the two mechanisms. The Main Ethiopian Rift (MER), which connects the Afar depression in the north with the Turkana depression and Kenya Rift to the south, consists of two distinct systems of normal faults and its floor is scattered with volcanic fields formed by tens to several hundreds monogenetic, generally basaltic, small volcanoes and composite volcanoes and small calderas. The distribution of vents defines the overall shape of the volcanic field. Previous work has shown that the distribution of volcanic vents and the shape of a field are linked to its tectonic environment and its magmatic system. In order to distinguish the impact of each mechanism, we analyzed four volcanic fields located at the boundary between the central and northern MER, three of them (Debre Zeyit, Wonji and Kone) grew in the rift valley and one (Akaki) on the western rift shoulder. The elongation and shape of the fields were analyzed based on their vent distribution using the Principal Component Analysis (PCA), the Vent-to-Vent Distance (VVD), and the two dimensional symmetric Gaussian kernel density estimate methods. We extracted from these methods several parameters characterizing the spatial distribution of points (e.g., eccentricity (e), eigenvector index (evi), angular dispersion (Da)). These parameters allow to define at least three types of shape for volcanic fields: strong elongate (line and ellipse), bimodal/medium elongate (ellipse) and dispersed (circle) shapes. Applied to the natural example, these methods well differentiate each volcanic field. For example, the elongation of the field increases from shoulder to rift axis inversely to the angular dispersion. In addition, the results show that none of

  1. Composition and Distribution of Streambed Sediments in the Penobscot River, Maine, May 1999

    USGS Publications Warehouse

    Dudley, Robert W.; Giffen, Sarah E.

    2001-01-01

    Sediment samples were collected and geophysical surveys were run along 50 miles of the Penobscot River, Maine, in the spring of 1999 to produce maps that describe the composition and distribution of streambed sediments for selected areas in the river channel. The objective of the sediment survey was to locate areas along the river where fine-grained, easily transportable sediment types were deposited between Old Town and Medway, Maine. These data can be used to design future sediment-sampling programs to assess the quality of streambed sediments and evaluate the health of the Penobscot River. This report describes the results of the sediment survey and the methods used to collect, analyze, and interpret the data used to create maps of streambed-sediment types in the study area. Deposits of fine-grained sediments (mud and sand) are scattered along the shorelines of the mainland and the islands and at the downstream ends of islands and at the mouths of brooks and streams. The most extensive depositional areas were found in the Mattaseunk Dam impoundment near Medway. The main areas of the river channel consist primarily of gravel, sand, and rock.

  2. Tidal Mixing and Buoyancy Advection: Joint Influences on Lobster Distribution in Coastal Maine

    NASA Astrophysics Data System (ADS)

    Brooks, D. A.

    2004-12-01

    The Eastern Maine Coastal Current (EMCC) flows southwestward from the mouth of the Bay of Fundy to Penobscot Bay on the central Maine coast. Maximum non-tidal surface speeds reach 20-30 cm/s about 20 km offshore during April-May when the outflow from the Saint John River is strongest. Vigorous tides cause strong vertical and horizontal mixing, so that dispersal of neutral particles is influenced both by advection and tidal mixing. To survive, planktonic lobsters carried southwestward in the surface flow must settle to a nearshore cobble substrate. Larvae hatched near the Bay of Fundy can be advected to the central coast in 2-3 weeks, roughly the time needed to reach settlement stage. Over the same period, transverse tidal mixing is sufficient to raise nearshore larval concentrations to about half that offshore in the axis of the EMCC. Both processes may be necessary to explain the observed lobster distribution, which exhibits a distinct maximum in the central coastal region. The seasonal development of the EMCC is also influenced by winds and the larger circulation of the Gulf of Maine. This work is part of a multidisciplinary synthesis study funded by the NOAA Coastal Ocean Program.

  3. The gas distribution in the high-redshift cluster MS 1054-0321

    NASA Astrophysics Data System (ADS)

    Mirakhor, M. S.; Birkinshaw, M.

    2016-04-01

    We investigate the gas mass distribution in the high-redshift cluster MS 1054-0321 using Chandra X-ray and One Centimetre Receiver array Sunyaev-Zel'dovich (SZ) effect data. We use a superposition of offset β-type models to describe the composite structure of MS 1054-0321. We find gas mass fractions f_{gas}^{X {-}ray} = 0.087_{-0.001}^{+0.005} and f_{gas}^SZ=0.094_{-0.001}^{+0.003} for the (main) eastern component of MS 1054-0321 using X-ray or SZ data, but f_{gas}^{X {-}ray}=0.030_{-0.014}^{+0.010} for the western component. The gas mass fraction for the eastern component is in agreement with some results reported in the literature, but inconsistent with the cosmic baryon fraction. The low-gas mass fraction for the western component is likely to be a consequence of gas stripping during the ongoing merger. The gas mass fraction of the integrated system is 0.060_{-0.009}^{+0.004}: we suggest that the missing baryons from the western component are present as hot diffuse gas which is poorly represented in existing X-ray images. The missing gas could appear in sensitive SZ maps.

  4. Characterization of real gas properties for space shuttle main engine fuel turbine and performance calculations

    NASA Technical Reports Server (NTRS)

    Harloff, G. J.

    1986-01-01

    Real thermodynamic and transport properties of hydrogen, steam, the SSME mixture, and air are developed. The SSME mixture properties are needed for the analysis of the space shuttle main engine fuel turbine. The mixture conditions for the gases, except air, are presented graphically over a temperature range from 800 to 1200 K, and a pressure range from 1 to 500 atm. Air properties are given over a temperature range of 320 to 500 K, which are within the bounds of the thermodynamics programs used, in order to provide mixture data which is more easily checked (than H2/H2O). The real gas property variation of the SSME mixture is quantified. Polynomial expressions, needed for future computer analysis, for viscosity, Prandtl number, and thermal conductivity are given for the H2/H2O SSME fuel turbine mixture at a pressure of 305 atm over a range of temperatures from 950 to 1140 K. These conditions are representative of the SSME turbine operation. Performance calculations are presented for the space shuttle main engine (SSME) fuel turbine. The calculations use the air equivalent concept. Progress towards obtaining the capability to evaluate the performance of the SSME fuel turbine, with the H2/H2O mixture, is described.

  5. The historical distribution of main malaria foci in Spain as related to water bodies.

    PubMed

    Sousa, Arturo; García-Barrón, Leoncio; Vetter, Mark; Morales, Julia

    2014-08-01

    The possible connectivity between the spatial distribution of water bodies suitable for vectors of malaria and endemic malaria foci in Southern Europe is still not well known. Spain was one of the last countries in Western Europe to be declared free of malaria by the World Health Organization (WHO) in 1964. This study combines, by means of a spatial-temporal analysis, the historical data of patients and deceased with the distribution of water bodies where the disease-transmitting mosquitos proliferate. Therefore, data from historical archives with a Geographic Information System (GIS), using the Inverse Distance Weighted (IDW) interpolation method, was analyzed with the aim of identifying regional differences in the distribution of malaria in Spain. The reasons, why the risk of transmission is concentrated in specific regions, are related to worse socioeconomic conditions (Extremadura), the presence of another vector (Anopheles labranchiae) besides A. atroparvus (Levante) or large areas of water bodies in conditions to reproduce theses vectors (La Mancha and Western Andalusia). In the particular case of Western Andalusia, in 1913, the relatively high percentage of 4.73% of the surface, equal to 202362 ha, corresponds to wetlands and other unhealthy water bodies. These wetlands have been reduced as a result of desiccation policies and climate change such as the Little Ice Age and Global Climate Change. The comprehension of the main factors of these wetland changes in the past can help us interpret accurately the future risk of malaria re-emergence in temperate latitudes, since it reveals the crucial role of unhealthy water bodies on the distribution, endemicity and eradication of malaria in southern Europe. PMID:25101771

  6. The Historical Distribution of Main Malaria Foci in Spain as Related to Water Bodies

    PubMed Central

    Sousa, Arturo; García-Barrón, Leoncio; Vetter, Mark; Morales, Julia

    2014-01-01

    The possible connectivity between the spatial distribution of water bodies suitable for vectors of malaria and endemic malaria foci in Southern Europe is still not well known. Spain was one of the last countries in Western Europe to be declared free of malaria by the World Health Organization (WHO) in 1964. This study combines, by means of a spatial-temporal analysis, the historical data of patients and deceased with the distribution of water bodies where the disease-transmitting mosquitos proliferate. Therefore, data from historical archives with a Geographic Information System (GIS), using the Inverse Distance Weighted (IDW) interpolation method, was analyzed with the aim of identifying regional differences in the distribution of malaria in Spain. The reasons, why the risk of transmission is concentrated in specific regions, are related to worse socioeconomic conditions (Extremadura), the presence of another vector (Anopheles labranchiae) besides A. atroparvus (Levante) or large areas of water bodies in conditions to reproduce theses vectors (La Mancha and Western Andalusia). In the particular case of Western Andalusia, in 1913, the relatively high percentage of 4.73% of the surface, equal to 202362 ha, corresponds to wetlands and other unhealthy water bodies. These wetlands have been reduced as a result of desiccation policies and climate change such as the Little Ice Age and Global Climate Change. The comprehension of the main factors of these wetland changes in the past can help us interpret accurately the future risk of malaria re-emergence in temperate latitudes, since it reveals the crucial role of unhealthy water bodies on the distribution, endemicity and eradication of malaria in southern Europe. PMID:25101771

  7. 40 CFR Table W - 7 of Subpart W-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Emission Factors for Natural Gas Distribution W Table W Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) MANDATORY GREENHOUSE GAS REPORTING Petroleum and Natural Gas... for Natural Gas Distribution Natural gas distribution Emission factor (scf/hour/component)...

  8. Main Power Distribution Unit for the Jupiter Icy Moons Orbiter (JIMO)

    NASA Technical Reports Server (NTRS)

    Papa, Melissa R.

    2004-01-01

    Around the year 2011, the Jupiter Icy Moons Orbiter (JIMO) will be launched and on its way to orbit three of Jupiter s planet-sized moons. The mission goals for the JIMO project revolve heavily around gathering scientific data concerning ingredients we, as humans, consider essential: water, energy and necessary chemical elements. The JIM0 is an ambitious mission which will implore propulsion from an ION thruster powered by a nuclear fission reactor. Glenn Research Center is responsible for the development of the dynamic power conversion, power management and distribution, heat rejection and ION thrusters. The first test phase for the JIM0 program concerns the High Power AC Power Management and Distribution (PMAD) Test Bed. The goal of this testing is to support electrical performance verification of the power systems. The test bed will incorporate a 2kW Brayton Rotating Unit (BRU) to simulate the nuclear reactor as well as two ION thrusters. The first module of the PMAD Test Bed to be designed is the Main Power Distribution Unit (MPDU) which relays the power input to the various propulsion systems and scientific instruments. The MPDU involves circuitry design as well as mechanical design to determine the placement of the components. The MPDU consists of fourteen relays of four different variations used to convert the input power into the appropriate power output. The three phase system uses 400 Vo1ts(sub L-L) rms at 1000 Hertz. The power is relayed through the circuit and distributed to the scientific instruments, the ION thrusters and other controlled systems. The mechanical design requires the components to be positioned for easy electrical wiring as well as allowing adequate room for the main buss bars, individual circuit boards connected to each component and power supplies. To accomplish creating a suitable design, AutoCAD was used as a drafting tool. By showing a visual layout of the components, it is easy to see where there is extra room or where the

  9. Relation of adult size to movements and distribution of smallmouth bass in a central Maine Lake

    USGS Publications Warehouse

    Cole, M.B.; Moring, J.R.

    1997-01-01

    Forty-four smallmouth bass Micropterus dolomieu of three size-classes were radiotracked in Green Lake, Maine, during summer 1993 (10 June-1 September) to determine whether adult size influenced distribution and movement. Large smallmouth bass (>406 mm) used deep water (>8 m) more often than did small (248-279 mm) or medium-sized (305-356 mm) smallmouth bass during the late summer (15 July-1 September). Large smallmouth bass also were found at middepths (4-8 m) significantly more often than were small individuals during late summer. Small fish used cover more frequently than large ones during early summer (10 June-13 July). Both small and medium-sized individuals were associated with cover more frequently than large smallmouth bass were during the late summer. Small smallmouth bass exhibited significantly smaller summer total ranges than did large individuals, and mean active displacement differed among all three size-classes.

  10. Performance of marine power plant given generator, main and distribution switchboard failures

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Ram, Mangey

    2015-12-01

    Power generation is one of the most essential functions of any plant for continuous functioning without any interruption. A marine power plant (MPP) is in the same situation. In the present paper, the authors have tried to find the various reliability characteristics of a MPP. Using a marine power plant composed of two generators in which one of them is located at the stern and another at the bow, both associated to the main switch board (MSB). The distributive switch boards (DSB) receive power from the MSB through cables and their respective junctions. Given that arrangement, a working based transition state diagram has been generated. With the help of the Markov process, a number of intro-differential equations are formed and solved by Laplace transform. Various reliability characteristics are calculated and discussed with the help of graphs.

  11. Albedo distribution of main-belt asteroids based on IRAS, AKARI, and WISE

    NASA Astrophysics Data System (ADS)

    Usui, F.; Hasegawa, S.; Ishiguro, M.; Mueller, T.; Ootsubo, T.

    2014-07-01

    Presently, the number of asteroids is known to be more than 630,000, and more than 90 % of asteroids with known orbital elements are classified as main-belt asteroids (MBAs). The spatial distribution of compositions among MBAs is of particular interest, because the main belt is the largest reservoir of asteroids in the solar system. Asteroids are thought to be the remnants of planetesimals formed in the early solar system, and allow us to study the formation and evolution of asteroids, origin of meteoroids and the near-Earth asteroids, as well as the formation of the solar system. Size and albedo are one of the most basic physical quantities of asteroid. Knowledge of size and albedo is essential in many aspects of asteroid research, such as the chemical composition and mineralogy, the size-frequency distribution of dynamical families and populations of asteroids, and the relationship between small bodies in the outer solar system and comets. Several techniques have been developed to determine the size of asteroids; by direct imaging with the Hubble Space Telescope or large ground-based telescopes with adaptive optics, radar observations, speckle interferometry, stellar occultation combined with lightcurve inversion techniques, and spacecraft flyby / rendezvous / sample return. One of the most effective methods for measuring asteroid size and albedo indirectly is through the use of radiometry, which combines information of the thermal emission (infrared flux) and the reflected sunlight (absolute magnitude). This method can provide unique data for asteroid size and albedo. Using radiometric measurements, a large number of objects can be observed in a short period of time, providing coherent data for large populations of asteroids within the asteroid belt. Infrared observations can be made still better under ideal circumstances, from space. The first space-borne infrared telescope is the Infrared Astronomical Satellite (IRAS; [1]), launched in 1983 and performed a

  12. Seismicity along the Main Marmara Fault, Turkey: from space-time distribution to repeating events

    NASA Astrophysics Data System (ADS)

    Schmittbuhl, Jean; Karabulut, Hayrullah; Lengliné, Olivier; Bouchon, Michel

    2016-04-01

    The North Anatolian Fault (NAF) poses a significant hazard for the large cities surrounding the Marmara Sea region particularly the megalopolis of Istanbul. Indeed, the NAF is presently hosting a long unruptured segment below the Sea of Marmara. This seismic gap is approximately 150 km long and corresponds to the Main Marmara Fault (MMF). The seismicity along the Main Marmara Fault (MMF) below the Marmara Sea is analyzed here during the 2007-2012 period to provide insights on the recent evolution of this important regional seismic gap. High precision locations show that seismicity is strongly varying along strike and depth providing fine details of the fault behavior that are inaccessible from geodetic inversions. The activity strongly clusters at the regions of transition between basins. The Central basin shows significant seismicity located below the shallow locking depth inferred from GPS measurements. Its b-value is low and the average seismic slip is high. Interestingly we found also several long term repeating earthquakes in this domain. Using a template matching technique, we evidenced two new families of repeaters: a first family that typically belongs to aftershock sequences and a second family of long lasting repeaters with a multi-month recurrence period. All observations are consistent with a deep creep of this segment. On the contrary, the Kumburgaz basin at the center of the fault shows sparse seismicity with the hallmarks of a locked segment. In the eastern Marmara Sea, the seismicity distribution along the Princes Island segment in the Cinarcik basin, is consistent with the geodetic locking depth of 10km and a low contribution to the regional seismic energy release. The assessment of the locked segment areas provide an estimate of the magnitude of the main forthcoming event to be about 7.3 assuming that the rupture will not enter significantly within creeping domains.

  13. Estimating Predictive Variance for Statistical Gas Distribution Modelling

    SciTech Connect

    Lilienthal, Achim J.; Asadi, Sahar; Reggente, Matteo

    2009-05-23

    Recent publications in statistical gas distribution modelling have proposed algorithms that model mean and variance of a distribution. This paper argues that estimating the predictive concentration variance entails not only a gradual improvement but is rather a significant step to advance the field. This is, first, since the models much better fit the particular structure of gas distributions, which exhibit strong fluctuations with considerable spatial variations as a result of the intermittent character of gas dispersal. Second, because estimating the predictive variance allows to evaluate the model quality in terms of the data likelihood. This offers a solution to the problem of ground truth evaluation, which has always been a critical issue for gas distribution modelling. It also enables solid comparisons of different modelling approaches, and provides the means to learn meta parameters of the model, to determine when the model should be updated or re-initialised, or to suggest new measurement locations based on the current model. We also point out directions of related ongoing or potential future research work.

  14. The Gas Distribution in the Outer Regions of Galaxy Clusters

    NASA Technical Reports Server (NTRS)

    Eckert, D.; Vazza, F.; Ettori, S.; Molendi, S.; Nagai, D.; Lau, E. T.; Roncarelli, M.; Rossetti, M.; Snowden, L.; Gastaldello, F.

    2012-01-01

    Aims. We present our analysis of a local (z = 0.04 - 0.2) sample of 31 galaxy clusters with the aim of measuring the density of the X-ray emitting gas in cluster outskirts. We compare our results with numerical simulations to set constraints on the azimuthal symmetry and gas clumping in the outer regions of galaxy clusters. Methods. We have exploited the large field-of-view and low instrumental background of ROSAT/PSPC to trace the density of the intracluster gas out to the virial radius, We stacked the density profiles to detect a signal beyond T200 and measured the typical density and scatter in cluster outskirts. We also computed the azimuthal scatter of the profiles with respect to the mean value to look for deviations from spherical symmetry. Finally, we compared our average density and scatter profiles with the results of numerical simulations. Results. As opposed to some recent Suzaku results, and confirming previous evidence from ROSAT and Chandra, we observe a steepening of the density profiles beyond approximately r(sub 500). Comparing our density profiles with simulations, we find that non-radiative runs predict density profiles that are too steep, whereas runs including additional physics and/ or treating gas clumping agree better with the observed gas distribution. We report high-confidence detection of a systematic difference between cool-core and non cool-core clusters beyond approximately 0.3r(sub 200), which we explain by a different distribution of the gas in the two classes. Beyond approximately r(sub 500), galaxy clusters deviate significantly from spherical symmetry, with only small differences between relaxed and disturbed systems. We find good agreement between the observed and predicted scatter profiles, but only when the 1% densest clumps are filtered out in the ENZO simulations. Conclusions. Comparing our results with numerical simulations, we find that non-radiative simulations fail to reproduce the gas distribution, even well outside

  15. The Gas Distribution in Galaxy Cluster Outer Regions

    NASA Technical Reports Server (NTRS)

    Eckert, D.; Vazza, F.; Ettori, S.; Molendi, S.; Nagai, D.; Laue, E. T.; Roncarelli, M.; Rossetti, M.; Snowden, S. L.; Gastaldello, F.

    2012-01-01

    Aims. We present the analysis of a local (z = 0.04 - 0.2) sample of 31 galaxy clusters with the aim of measuring the density of the X-ray emitting gas in cluster outskirts. We compare our results with numerical simulations to set constraints on the azimuthal symmetry and gas clumping in the outer regions of galaxy clusters. Methods. We exploit the large field-of-view and low instrumental background of ROSAT/PSPC to trace the density of the intracluster gas out to the virial radius. We perform a stacking of the density profiles to detect a signal beyond r200 and measure the typical density and scatter in cluster outskirts. We also compute the azimuthal scatter of the profiles with respect to the mean value to look for deviations from spherical symmetry. Finally, we compare our average density and scatter profiles with the results of numerical simulations. Results. As opposed to some recent Suzaku results, and confirming previous evidence from ROSAT and Chandra, we observe a steepening of the density profiles beyond approximately r(sub 500). Comparing our density profiles with simulations, we find that non-radiative runs predict too steep density profiles, whereas runs including additional physics and/or treating gas clumping are in better agreement with the observed gas distribution. We report for the first time the high-confidence detection of a systematic difference between cool-core and non-cool core clusters beyond 0.3r(sub 200), which we explain by a different distribution of the gas in the two classes. Beyond r(sub 500), galaxy clusters deviate significantly from spherical symmetry, with only little differences between relaxed and disturbed systems. We find good agreement between the observed and predicted scatter profiles, but only when the 1% densest clumps are filtered out in the simulations. Conclusions. Comparing our results with numerical simulations, we find that non-radiative simulations fail to reproduce the gas distribution, even well outside cluster

  16. Outer Main Belt asteroids: Identification and distribution of four 3-μm spectral groups

    NASA Astrophysics Data System (ADS)

    Takir, Driss; Emery, Joshua P.

    2012-06-01

    This paper examines the distribution and the abundance of hydrated minerals (any mineral that contains H2O or OH) on outer Main Belt asteroids spanning the 2.5 < a < 4.0 AU region. The hypothesis we are testing is whether planetesimals that accreted closer to the Sun experienced a higher degree of aqueous alteration. We would expect then to see a gradual decline of the abundance of hydrated minerals among the outer Main Belt asteroids with increasing heliocentric distance (2.5 < a < 4.0 AU). We measured spectra (0.8-2.5 μm and 1.9-4.1 μm) of 28 outer Main Belt asteroids using the SpeX spectrograph/imager at the NASA Infrared Telescope Facility (IRTF). We identified four groups on the basis of the shape and the band center of the 3-μm feature. The first group, which we call "sharp", exhibits a sharp 3-μm feature, attributed to hydrated minerals (phyllosilicates). Most asteroids in this group are located in the 2.5 < a < 3.3 AU region. The second group, which we call "Ceres-like", consists of 10 Hygiea and 324 Bamberga. Like Asteroid Ceres, these asteroids exhibit a 3-μm feature with a band center of 3.05 ± 0.01 μm that is superimposed on a broader absorption feature from ˜2.8 to 3.7 μm. The third group, which we call "Europa-like", includes 52 Europa, 31 Euphrosyne, and 451 Patientia. Objects in this group exhibit a 3-μm feature with a band center of 3.15 ± 0.01 μm. Both the Ceres-like and Europa-like groups are concentrated in the 2.5 < a < 3.3 AU region. The fourth group, which we call "rounded", is concentrated in the 3.4 < a < 4.0 AU region. Asteroids in this group are characterized by a rounded 3-μm feature, attributed to H2O ice. A similar rounded 3-μm feature was also identified in 24 Themis and 65 Cybele. Unlike the sharp group, the rounded group did not experience aqueous alteration. Of the asteroids observed in this study, 140 Siwa, a P-type, is the only one that does not exhibit a 3-μm feature. These results are important to constrain the

  17. Limits on the size and orbit distribution of main belt comets

    NASA Astrophysics Data System (ADS)

    Sonnett, Sarah; Kleyna, Jan; Jedicke, Robert; Masiero, Joseph

    2011-10-01

    The first of a new class of objects now known as main belt comets (MBCs) or "activated asteroids" was identified in 1996. The seven known members of this class have orbital characteristics of main belt asteroids yet exhibit dust ejection like comets. In order to constrain their physical and orbital properties we searched the Thousand Asteroid Light Curve Survey (TALCS; Masiero, J.R., Jedicke, R., Durech, J., Gwyn, S., Denneau, L., Larsen, J. [2009]. Icarus 204, 145-171) for additional candidates using two diagnostics: tail and coma detection. This was the most sensitive MBC survey effort to date, extending the search from MBCs with H ˜ 18 ( D ˜ 1 km) to MBCs as small as H ˜ 21 ( D ˜ 150 m). We fit each of the 924 objects detected by TALCS to a PSF model incorporating both a coma and nuclear component to measure the fractional contribution of the coma to the total surface brightness. We determined the significance of the coma detection using the same algorithm on a sample of null detections of comparable magnitude and rate of motion. We did not identify any MBC candidates with this technique to a sensitivity limit on the order of cometary mass loss rate of about 0.1 kg/s. Our tail detection algorithm relied on identifying statistically significant flux in a segmented annulus around the candidate object. We show that the technique can detect tail activity throughout the asteroid belt to the level of the currently known MBCs. Although we did not identify any MBC candidates with this technique, we find a statistically significant detection of faint activity in the entire ensemble of TALCS asteroids. This suggests that many main belt asteroids are active at very low levels. Our null detection of MBCs allows us to set 90% upper confidence limits on the number distribution of MBCs as a function of absolute magnitude, semi-major axis, eccentricity, and inclination. There are ≲400,000 MBCs in the main belt brighter than HV = 21 (˜150-m in diameter) and the MBC

  18. Measuring volcanic gases at Taal Volcano Main Crater for monitoring volcanic activity and possible gas hazard

    NASA Astrophysics Data System (ADS)

    Arpa, M.; Hernandez Perez, P. A.; Reniva, P.; Bariso, E.; Padilla, G.; Melian Rodriguez, G.; Barrancos, J.; Calvo, D.; Nolasco, D.; Padron, E.; Garduque, R.; Villacorte, E.; Fajiculay, E.; Perez, N.; Solidum, R.

    2012-12-01

    Taal is an active volcano located in southwest Luzon, Philippines. It consists of mainly tuff cones which have formed an island at the center of a 30 km wide Taal Caldera. Most historical eruptions, since 1572 on Taal Volcano Island, have been characterized as hydromagmatic eruptions. Taal Main Crater, produced during the 1911 eruption, is the largest crater in the island currently filled by a 1.2 km wide, 85 m deep acidic lake. The latest historical eruption occurred in 1965-1977. Monitoring of CO2 emissions from the Main Crater Lake (MCL) and fumarolic areas within the Main Crater started in 2008 with a collaborative project between ITER and PHIVOLCS. Measurements were done by accumulation chamber method using a Westsystem portable diffuse fluxmeter. Baseline total diffuse CO2 emissions of less than 1000 t/d were established for the MCL from 3 campaign-type surveys between April, 2008 to March, 2010 when seismicity was within background levels. In May, 2010, anomalous seismic activity from the volcano started and the total CO2 emission from the MCL increased to 2716±54 t/d as measured in August, 2010. The CO2 emission from the lake was highest last March, 2011 at 4670±159 t/d when the volcano was still showing signs of unrest. Because CO2 emissions increased significantly (more than 3 times the baseline value) at this time, this activity may be interpreted as magmatic and not purely hydrothermal. Most likely deep magma intrusions occurred but did not progress further to shallower depths and no eruption occurred. No large increase in lake water temperature near the surface (average for the whole lake area) during the period when CO2 was above background, it remained at 30-34°C and a few degrees lower than average ambient temperature. Total CO2 emissions from the MCL have decreased to within baseline values since October, 2011. Concentrations of CO2, SO2 and H2S in air in the fumarolic area within the Main Crater also increased in March, 2011. The measurements

  19. Gas-Fired Distributed Energy Resource Technology Characterizations

    SciTech Connect

    Goldstein, L.; Hedman, B.; Knowles, D.; Freedman, S. I.; Woods, R.; Schweizer, T.

    2003-11-01

    The U. S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE) is directing substantial programs in the development and encouragement of new energy technologies. Among them are renewable energy and distributed energy resource technologies. As part of its ongoing effort to document the status and potential of these technologies, DOE EERE directed the National Renewable Energy Laboratory to lead an effort to develop and publish Distributed Energy Technology Characterizations (TCs) that would provide both the department and energy community with a consistent and objective set of cost and performance data in prospective electric-power generation applications in the United States. Toward that goal, DOE/EERE - joined by the Electric Power Research Institute (EPRI) - published the Renewable Energy Technology Characterizations in December 1997.As a follow-up, DOE EERE - joined by the Gas Research Institute - is now publishing this document, Gas-Fired Distributed Energy Resource Technology Characterizations.

  20. Decompression vs. Decomposition: Distribution, Amount, and Gas Composition of Bubbles in Stranded Marine Mammals

    PubMed Central

    de Quirós, Yara Bernaldo; González-Diaz, Oscar; Arbelo, Manuel; Sierra, Eva; Sacchini, Simona; Fernández, Antonio

    2012-01-01

    Gas embolic lesions linked to military sonar have been described in stranded cetaceans including beaked whales. These descriptions suggest that gas bubbles in marine mammal tissues may be more common than previously thought. In this study we have analyzed gas amount (by gas score) and gas composition within different decomposition codes using a standardized methodology. This broad study has allowed us to explore species-specific variability in bubble prevalence, amount, distribution, and composition, as well as masking of bubble content by putrefaction gases. Bubbles detected within the cardiovascular system and other tissues related to both pre- and port-mortem processes are a common finding on necropsy of stranded cetaceans. To minimize masking by putrefaction gases, necropsy, and gas sampling must be performed as soon as possible. Before 24 h post mortem is recommended but preferably within 12 h post mortem. At necropsy, amount of bubbles (gas score) in decomposition code 2 in stranded cetaceans was found to be more important than merely presence vs. absence of bubbles from a pathological point of view. Deep divers presented higher abundance of gas bubbles, mainly composed of 70% nitrogen and 30% CO2, suggesting a higher predisposition of these species to suffer from decompression-related gas embolism. PMID:22675306

  1. Decompression vs. Decomposition: Distribution, Amount, and Gas Composition of Bubbles in Stranded Marine Mammals.

    PubMed

    de Quirós, Yara Bernaldo; González-Diaz, Oscar; Arbelo, Manuel; Sierra, Eva; Sacchini, Simona; Fernández, Antonio

    2012-01-01

    Gas embolic lesions linked to military sonar have been described in stranded cetaceans including beaked whales. These descriptions suggest that gas bubbles in marine mammal tissues may be more common than previously thought. In this study we have analyzed gas amount (by gas score) and gas composition within different decomposition codes using a standardized methodology. This broad study has allowed us to explore species-specific variability in bubble prevalence, amount, distribution, and composition, as well as masking of bubble content by putrefaction gases. Bubbles detected within the cardiovascular system and other tissues related to both pre- and port-mortem processes are a common finding on necropsy of stranded cetaceans. To minimize masking by putrefaction gases, necropsy, and gas sampling must be performed as soon as possible. Before 24 h post mortem is recommended but preferably within 12 h post mortem. At necropsy, amount of bubbles (gas score) in decomposition code 2 in stranded cetaceans was found to be more important than merely presence vs. absence of bubbles from a pathological point of view. Deep divers presented higher abundance of gas bubbles, mainly composed of 70% nitrogen and 30% CO(2), suggesting a higher predisposition of these species to suffer from decompression-related gas embolism. PMID:22675306

  2. A scaling law of radial gas distribution in disk galaxies

    NASA Technical Reports Server (NTRS)

    Wang, Zhong

    1990-01-01

    Based on the idea that local conditions within a galactic disk largely determine the region's evolution time scale, researchers built a theoretical model to take into account molecular cloud and star formations in the disk evolution process. Despite some variations that may be caused by spiral arms and central bulge masses, they found that many late-type galaxies show consistency with the model in their radial atomic and molecular gas profiles. In particular, researchers propose that a scaling law be used to generalize the gas distribution characteristics. This scaling law may be useful in helping to understand the observed gas contents in many galaxies. Their model assumes an exponential mass distribution with disk radius. Most of the mass are in atomic gas state at the beginning of the evolution. Molecular clouds form through a modified Schmidt Law which takes into account gravitational instabilities in a possible three-phase structure of diffuse interstellar medium (McKee and Ostriker, 1977; Balbus and Cowie, 1985); whereas star formation proceeds presumably unaffected by the environmental conditions outside of molecular clouds (Young, 1987). In such a model both atomic and molecular gas profiles in a typical galactic disk (as a result of the evolution) can be fitted simultaneously by adjusting the efficiency constants. Galaxies of different sizes and masses, on the other hand, can be compared with the model by simply scaling their characteristic length scales and shifting their radial ranges to match the assumed disk total mass profile sigma tot(r).

  3. Spatial distribution of pelagic fish larvae in the northern main basin of Lake Huron

    USGS Publications Warehouse

    Roseman, Edward F.; O'Brien, Timothy P.

    2013-01-01

    Larval fish occurrence in inshore and offshore zones in the northern main basin of Lake Huron was assessed during 2007 as part of a larger ecological examination of Lake Huron foodwebs and habitats. Day and night collections using neuston and conical nets at inshore (1.5–15 m depths) and offshore (37 and 91 m depths) locations at De Tour and Hammond Bay to assess the abundance, phenology, and spatial distribution of pelagic ichthyoplankton during spring and early summer were made. In general, densities of larval fishes were higher at De Tour than Hammond Bay during daytime neuston net collections, with the exception of Longnose Sucker, which were only collected at Hammond Bay. Lake Whitefish, Burbot, and Rainbow Smelt dominated inshore catches in early spring with Cisco, Deepwater Sculpin, Emerald Shiner, Bloater, Slimy Sculpin, Ninespine Stickleback, and Yellow Perch larvae also collected. Nighttime nearshore and offshore sampling revealed that Rainbow Smelt and Burbot larvae were present in relatively high abundances compared to inshore densities. Concentrations of larvae of deepwater demersal fishes such as Lake Whitefish and Deepwater Sculpin suggest that inshore zones in northern Lake Huron are important nursery habitats emphasizing a critical production and recruitment linkage between inshore and deepwater zones.

  4. DISTRIBUTION OF ACCRETING GAS AND ANGULAR MOMENTUM ONTO CIRCUMPLANETARY DISKS

    SciTech Connect

    Tanigawa, Takayuki; Ohtsuki, Keiji; Machida, Masahiro N.

    2012-03-01

    We investigate gas accretion flow onto a circumplanetary disk from a protoplanetary disk in detail by using high-resolution three-dimensional nested-grid hydrodynamic simulations, in order to provide a basis of formation processes of satellites around giant planets. Based on detailed analyses of gas accretion flow, we find that most of gas accretion onto circumplanetary disks occurs nearly vertically toward the disk surface from high altitude, which generates a shock surface at several scale heights of the circumplanetary disk. The gas that has passed through the shock surface moves inward because its specific angular momentum is smaller than that of the local Keplerian rotation, while gas near the midplane in the protoplanetary disk cannot accrete to the circumplanetary disk. Gas near the midplane within the planet's Hill sphere spirals outward and escapes from the Hill sphere through the two Lagrangian points L{sub 1} and L{sub 2}. We also analyze fluxes of accreting mass and angular momentum in detail and find that the distributions of the fluxes onto the disk surface are well described by power-law functions and that a large fraction of gas accretion occurs at the outer region of the disk, i.e., at about 0.1 times the Hill radius. The nature of power-law functions indicates that, other than the outer edge, there is no specific radius where gas accretion is concentrated. These source functions of mass and angular momentum in the circumplanetary disk would provide us with useful constraints on the structure and evolution of the circumplanetary disk, which is important for satellite formation.

  5. Modeling natural gas market volatility using GARCH with different distributions

    NASA Astrophysics Data System (ADS)

    Lv, Xiaodong; Shan, Xian

    2013-11-01

    In this paper, we model natural gas market volatility using GARCH-class models with long memory and fat-tail distributions. First, we forecast price volatilities of spot and futures prices. Our evidence shows that none of the models can consistently outperform others across different criteria of loss functions. We can obtain greater forecasting accuracy by taking the stylized fact of fat-tail distributions into account. Second, we forecast volatility of basis defined as the price differential between spot and futures. Our evidence shows that nonlinear GARCH-class models with asymmetric effects have the greatest forecasting accuracy. Finally, we investigate the source of forecasting loss of models. Our findings based on a detrending moving average indicate that GARCH models cannot capture multifractality in natural gas markets. This may be the plausible explanation for the source of model forecasting losses.

  6. Application of groundwater aggressiveness assessment method for estimation of the karst process at main gas pipeline construction

    NASA Astrophysics Data System (ADS)

    Ermolaeva, A. V.

    2016-03-01

    Main pipelines maintenance is connected with hazard engineering and geological working conditions. The article deals with the use of groundwater aggressiveness assessment method to estimate the karst processes development during the construction of main gas pipelines. The possibility of using this method is analyzed on the example of the initial section of the designed gas pipeline “Power of Siberia” (section “Chayanda-Lensk"). The calculation of the nonequilibrium index Ca was made in accordance with the geotechnical survey data. The dependencies between the geomorphological features of the terrain and the natural waters aggressiveness were determined.

  7. Distribution of the Molecular Gas Around SN 1572

    NASA Astrophysics Data System (ADS)

    Cai, Zhi-Yong; Yang, Ji; Lu, Deng-Rong

    2009-10-01

    The early-stage structure and evolution of a supernova remnant (SNR) depends largely on its ambient interstellar medium, so the interstellar medium becomes the valid probe for investigating the evolution of SNRs. We have observed the 12CO ( J = 1 - 0) line emission around the remnant of SN 1572 with the 13.7m millimeter-wave telescope at the Qinghai Station of PMO, in order to investigate the distribution of the CO molecular gas around SN 1572 and provide some observational basis for studying the relationship of SN 1572 with its ambient molecular gas and the evolution of this SNR. The observed result indicates that the molecular gas in the velocity range of V LSR = -69˜ -58 km/s is associated with SN 1572, and this velocity component comes from a large-scale molecular cloud. The molecular gas is distributed along the periphery of the radio shell, continually but not uniformly, and forms a semi-closed molecular shell around the SNR. The enhanced emission exists in its whole eastern half, especially the CO emission is strongest on the northeastern edge. At the emission peak position, the spectral line exhibits a broadened velocity feature (>5 km/s). Combining with available observations in the optical, infrared, X-ray and other wavebands, it is demonstrated that the fast shock wave and ejecta are expanding into the molecular gas on the northeastern edge, and interacting with the dense gas. This interaction will have an important influence on the future evolution of SN 1572.

  8. Gas distribution equipment in hydrogen service - Phase II

    NASA Technical Reports Server (NTRS)

    Jasionowski, W. J.; Huang, H. D.

    1980-01-01

    The hydrogen permeability of three different types of commercially available natural gas polyethylene pipes was determined. Ring tensile tests were conducted on permeability-exposed and as-received samples. Hydrogen-methane leakage experiments were also performed. The results show no selective leakage of hydrogen via Poiseuille, turbulent, or orifice flow (through leaks) on the distribution of blends of hydrogen and methane. The data collected show that the polyethylene pipe is 4 to 6 times more permeable to hydrogen than to methane.

  9. Process for forming a long gas turbine engine blade having a main wall with a thin portion near a tip

    SciTech Connect

    Campbell, Christian X; Thomaidis, Dimitrios

    2014-05-13

    A process is provided for forming an airfoil for a gas turbine engine involving: forming a casting of a gas turbine engine airfoil having a main wall and an interior cavity, the main wall having a wall thickness extending from an external surface of the outer wall to the interior cavity, an outer section of the main wall extending from a location between a base and a tip of the airfoil casting to the tip having a wall thickness greater than a final thickness. The process may further involve effecting movement, using a computer system, of a material removal apparatus and the casting relative to one another such that a layer of material is removed from the casting at one or more radial portions along the main wall of the casting.

  10. The chemical evolution of Dwarf Galaxies with galactic winds - the role of mass and gas distribution

    NASA Astrophysics Data System (ADS)

    Hensler, Gerhard; Recchi, Simone

    2015-08-01

    Energetic feedback from Supernovae and stellar winds can drive galactic winds. Dwarf galaxies (DGs), due to their shallower potential wells, are assumed to be more vulnera-ble to these energetic processes. Metal loss through galactic winds is also commonly invoked to explain the low metal content of DGs.Our main aim in this presentation is to show that galactic mass cannot be the only pa-rameter determining the fraction of metals lost by a galaxy. In particular, the distribution of gas must play an equally important role. We perform 2-D chemo-dynamical simula-tions of galaxies characterized by different gas distributions, masses and gas fractions. The gas distribution can change the fraction of lost metals through galactic winds by up to one order of magnitude. In particular, disk-like galaxies tend to lose metals more easily than roundish ones. Consequently, also the final element abundances attained by models with the same mass but with different gas distributions can vary by up to one dex. Confirming previous studies, we also show that the fate of gas and freshly pro-duced metals strongly depends on the mass of the galaxy. Smaller galaxies (with shal-lower potential wells) more easily develop large-scale outflows; therefore, the fraction of lost metals tends to be higher.Another important issue is that the invoked mechanism to transform central cusps to cored dark-matter distributions by baryon loss due to strong galactic winds cannot work in general, must be critically tested, and should be clearly discernible by the chemical evolution of DGs.

  11. The Distribution of Molecular Gas around SN 1572

    NASA Astrophysics Data System (ADS)

    Cai, Z. Y.; Yang, J.; Lu, D. R.

    2009-04-01

    The structure and evolution of a supernova remnant depends largely upon ambient interstellar medium,so the interstellar medium can be the valid probe of investigating the evolution of SNRs. We have observed the 12CO line emission around the SN 1572 with 13.7m millimeter-wave telescope at Qinghai Station of PMO, in order to reveal distribution features of velocity and density in small scale. It is shown that the CO molecular gas with the velocity of -69 ~ -61km s - 1 is correlated with SN 1572, and the gas surrounds the SN 1572 along the edge of radio shell with the morphology of open shell. Enhanced emission of 12CO line extends along the northeastern boundary. The spectrum of shocked gas has more than 5km s-1 half-width of velocity. Comparing X-ray, infrared and optical observation data, it indicates that fast blast wave and ejecta are expanding into a dense gas toward the northeast direction and interacting with this part of molecular gas.

  12. Truncated shifted pareto distribution in assessing size distribution of oil and gas fields

    SciTech Connect

    Houghton, J.C.

    1988-11-01

    The truncated shifted Pareto (TSP) distribution, a variant of the two-parameter Pareto distribution, in which one parameter is added to shift the distribution right and left and the right-hand side is truncated, is used to model size distributions of oil and gas fields for resource assessment. Assumptions about limits to the left-hand and right-hand side reduce the number of parameters to two. The TSP distribution has advantages over the more customary lognormal distribution because it has a simple analytic expression, allowing exact computation of several statistics of interest, has a J-shape, and has more flexibility in the thickness of the right-hand tail. Oil field sizes from the Minnelusa play in the Powder River Basin, Wyoming and Montana, are used as a case study. Probability plotting procedures allow easy visualization of the fit and help the assessment.

  13. Use of the truncated shifted Pareto distribution in assessing size distribution of oil and gas fields

    USGS Publications Warehouse

    Houghton, J.C.

    1988-01-01

    The truncated shifted Pareto (TSP) distribution, a variant of the two-parameter Pareto distribution, in which one parameter is added to shift the distribution right and left and the right-hand side is truncated, is used to model size distributions of oil and gas fields for resource assessment. Assumptions about limits to the left-hand and right-hand side reduce the number of parameters to two. The TSP distribution has advantages over the more customary lognormal distribution because it has a simple analytic expression, allowing exact computation of several statistics of interest, has a "J-shape," and has more flexibility in the thickness of the right-hand tail. Oil field sizes from the Minnelusa play in the Powder River Basin, Wyoming and Montana, are used as a case study. Probability plotting procedures allow easy visualization of the fit and help the assessment. ?? 1988 International Association for Mathematical Geology.

  14. ANOMALOUSLY PRESSURED GAS DISTRIBUTION IN THE WIND RIVER BASIN, WYOMING

    SciTech Connect

    Dr. Ronald C. Surdam

    2003-03-31

    Anomalously pressured gas (APG) assets, typically called ''basin-center'' gas accumulations, represent either an underdeveloped or undeveloped energy resource in the Rocky Mountain Laramide Basins (RMLB). Historically, the exploitation of these gas resources has proven to be very difficult and costly. In this topical report, an improved exploration strategy is outlined in conjunction with a more detailed description of new diagnostic techniques that more efficiently detect anomalously pressured, gas-charged domains. The ability to delineate gas-charged domains occurring below a regional velocity inversion surface allows operators to significantly reduce risk in the search for APG resources. The Wind River Basin was chosen for this demonstration because of the convergence of public data availability (i.e., thousands of mud logs and DSTs and 2400 mi of 2-D seismic lines); the evolution of new diagnostic techniques; a 175 digital sonic log suite; a regional stratigraphic framework; and corporate interest. In the exploration scheme discussed in this topical report, the basinwide gas distribution is determined in the following steps: (1) A detailed velocity model is established from sonic logs, 2-D seismic lines, and, if available, 3-D seismic data. In constructing the seismic interval velocity field, automatic picking technology using continuous, statistically-derived interval velocity selection, as well as conventional graphical interactive methodologies are utilized. (2) Next, the ideal regional velocity/depth function is removed from the observed sonic or seismic velocity/depth profile. The constructed ideal regional velocity/depth function is the velocity/depth trend resulting from the progressive burial of a rock/fluid system of constant rock/fluid composition, with all other factors remaining constant. (3) The removal of the ideal regional velocity/depth function isolates the anomalously slow velocities and allows the evaluation of (a) the regional velocity

  15. Constraints on Subsurface gas and gas Hydrate Distribution in a Gulf of Mexico Mound

    NASA Astrophysics Data System (ADS)

    Wood, W. T.; Hutchinson, D.; Hart, P.; Snyder, F.; Voss, C.; Dutta, N.; Muller, L.; Lee, M.; Gardner, J.; Dugan, B.; Ruppel, C.; Coffin, R.; Evans, R.; Jones, E.

    2003-12-01

    The Gulf of Mexico is well known for seafloor methane hydrate accumulations associated with hydrocarbon seeps, but the distribution of free gas, gas in solution and gas hydrate below the mounds is poorly known. Numerical simulation of fluid flow and analyses of industry 3-D seismic data (reprocessed for higher resolution in the shallow sediments), and high resolution seismic data recently acquired by the USGS provide some constraints on the distribution of these phases via their significantly different effect on seismic returns. Below an 8 m high, 300 m diameter mound at 1300 m water depth in Atwater Valley lease block 14, lies a convex upward, bell-shaped, subsurface reflection. The reflection can be modeled quite closely as a reflection from the base of hydrate stability (top of gas here) perturbed from about 300 to 45 m below the seafloor by localized, upward fluid and heat flux. The flow modeling therefore predicts free gas much higher below the mound than away from the mound. This is confirmed in the USGS data by a push down of 24 percent on a reflection passing below the perturbation, suggesting a velocity below the mound of less than 1400 m/s, indicative of at least some free gas. A strong upward perturbation to the base of the hydrate stability zone significantly constrains the volume available for methane hydrate formation below the seafloor, potentially impacting volume estimates of methane hydrate below seafloor mounds.

  16. Distributed Fiber Optic Gas Sensing for Harsh Environment

    SciTech Connect

    Juntao Wu

    2008-03-14

    This report summarizes work to develop a novel distributed fiber-optic micro-sensor that is capable of detecting common fossil fuel gases in harsh environments. During the 32-month research and development (R&D) program, GE Global Research successfully synthesized sensing materials using two techniques: sol-gel based fiber surface coating and magnetron sputtering based fiber micro-sensor integration. Palladium nanocrystalline embedded silica matrix material (nc-Pd/Silica), nanocrystalline palladium oxides (nc-PdO{sub x}) and palladium alloy (nc-PdAuN{sub 1}), and nanocrystalline tungsten (nc-WO{sub x}) sensing materials were identified to have high sensitivity and selectivity to hydrogen; while the palladium doped and un-doped nanocrystalline tin oxide (nc-PdSnO{sub 2} and nc-SnO{sub 2}) materials were verified to have high sensitivity and selectivity to carbon monoxide. The fiber micro-sensor comprises an apodized long-period grating in a single-mode fiber, and the fiber grating cladding surface was functionalized by above sensing materials with a typical thickness ranging from a few tens of nanometers to a few hundred nanometers. GE found that the morphologies of such sensing nanomaterials are either nanoparticle film or nanoporous film with a typical size distribution from 5-10 nanometers. nc-PdO{sub x} and alloy sensing materials were found to be highly sensitive to hydrogen gas within the temperature range from ambient to 150 C, while nc-Pd/Silica and nc-WO{sub x} sensing materials were found to be suitable to be operated from 150 C to 500 C for hydrogen gas detection. The palladium doped and un-doped nc-SnO{sub 2} materials also demonstrated sensitivity to carbon monoxide gas at approximately 500 C. The prototyped fiber gas sensing system developed in this R&D program is based on wavelength-division-multiplexing technology in which each fiber sensor is identified according to its transmission spectra features within the guiding mode and cladding modes. The

  17. Composition and distribution of the main active components in selenium-enriched fruit bodies of Cordyceps militaris link.

    PubMed

    Dong, Jing Z; Ding, J; Yu, Pei Z; Lei, Can; Zheng, Xiao J; Wang, Y

    2013-04-15

    Selenium-enriched Cordyceps militaris fruit bodies are industrially cultivated as functional food or medicinal food in China and southeast Asia. However, composition of selenium compounds and distribution of the main bioactive components are still unknown. In the selenium-enriched fruit bodies, the main soluble selenium compounds of low molecular weight were identified as SeMet (selenomethionine), and the main selenium compounds bound in proteins were identified as SeMet and SeCys (methylselenocysteine). Trace minerals as Se (selenium), Zn (zinc), Fe (iron) and the main active components as adenosine, cordycepin and carotenoids were mostly distributed in the terminal of fruit bodies, while P (phosphorus) and K (potassium) were evenly distributed in the fruit bodies. The results indicated that terminal of the fruit bodies should be the better materials for production of advanced functional food. So cultivation of relatively short and thick fruit bodies with bigger terminals deserves further research. PMID:23200005

  18. Distribution and toxicity of Alexandrium ostenfeldii (Dinophyceae) in the Gulf of Maine, USA

    NASA Astrophysics Data System (ADS)

    Gribble, Kristin E.; Keafer, Bruce A.; Quilliam, Michael A.; Cembella, Allan D.; Kulis, David M.; Manahan, Abigail; Anderson, Donald M.

    2005-09-01

    Alexandrium ostenfeldii is a thecate, mixotrophic dinoflagellate recently linked to a novel suite of toxins called spirolides. This study provides the first description of the regional distribution of A. ostenfeldii in the Gulf of Maine (GOM), and the first report and analysis of spirolide toxicity in A. ostenfeldii in waters south of Nova Scotia. Morphological examination of cells in field samples and of clonal cultures isolated from several stations in the GOM confirmed the presence of A. ostenfeldii. A genus-specific antibody probe, and an A. ostenfeldii species-specific oligonucleotide probe labeled these cells; a probe specific for the North American A. fundyense/tamarense/catenella species complex did not label A. ostenfeldii cells. Cell size ranged from 20 to nearly 90 μm, and most cells contained food vacuoles, with a total vacuole size from 1 to 48 μm. The hydrographic forcings controlling the distribution of A. ostenfeldii in the GOM are quite similar to those acting on the A. fundyense population at the same time of the year. The highest concentrations of A. ostenfeldii were observed nearshore, to the east of Penobscot Bay, at times with an offshore-turning branch of high cell concentration to the south of Penobscot Bay. Casco Bay appears to be an area of accumulation for A. ostenfeldii cells advected toward shore from the core of the population to the northeast. Concentrations of A. ostenfeldii were generally higher at the surface than deeper, except at locations where the pooling of lower-salinity water at the surface may have led to the subduction of the population flowing in from the east. PSP toxins were detected in field populations containing A. ostenfeldii and A. fundyense, but not in A. ostenfeldii cultures isolated from the GOM. Spirolide toxins were found in 36 of 60 field samples. More than 83% of samples containing A. ostenfeldii cells had one or more of spirolide congeners A, B, C2 and D2. The total concentration of spirolides per cell at

  19. Distribution of Faint Atomic Gas in Hickson Compact Groups

    NASA Astrophysics Data System (ADS)

    Borthakur, Sanchayeeta; Yun, Min Su; Verdes-Montenegro, Lourdes; Heckman, Timothy M.; Zhu, Guangtun; Braatz, James A.

    2015-10-01

    We present 21 cm H i observations of four Hickson Compact Groups (HCGs) with evidence for a substantial intragroup medium using the Robert C. Byrd Green Bank Telescope (GBT). By mapping H i emission in a region of 25‧ × 25‧ (140–650 kpc) surrounding each HCG, these observations provide better estimates of H i masses. In particular, we detected 65% more H i than that detected in the Karl G. Jansky Very Large Array (VLA) imaging of HCG 92. We also identify whether the diffuse gas has the same spatial distribution as the high surface brightness (HSB) H i features detected in the VLA maps of these groups by comparing the H i strengths between the observed and modeled masses based on VLA maps. We found that the H i observed with the GBT has a similar spatial distribution to the HSB structures in HCG 31 and HCG 68. Conversely, the observed H i distributions in HCG 44 and HCG 92 were extended and showed significant offsets from the modeled masses. Most of the faint gas in HCG 44 lies to the northeast–southwest region and in HCG 92 lies in the northwest region of their respective groups. The spatial and dynamical similarities between the total (faint+HSB) and the HSB H i indicate that the faint gas is of tidal origin. We found that the gas will survive ionization by the cosmic UV background and the escaping ionizing photons from the star-forming regions and stay primarily neutral for at least 500 Myr.

  20. Genetic algorithm to optimize the design of main combustor and gas generator in liquid rocket engines

    NASA Astrophysics Data System (ADS)

    Son, Min; Ko, Sangho; Koo, Jaye

    2014-06-01

    A genetic algorithm was used to develop optimal design methods for the regenerative cooled combustor and fuel-rich gas generator of a liquid rocket engine. For the combustor design, a chemical equilibrium analysis was applied, and the profile was calculated using Rao's method. One-dimensional heat transfer was assumed along the profile, and cooling channels were designed. For the gas-generator design, non-equilibrium properties were derived from a counterflow analysis, and a vaporization model for the fuel droplet was adopted to calculate residence time. Finally, a genetic algorithm was adopted to optimize the designs. The combustor and gas generator were optimally designed for 30-tonf, 75-tonf, and 150-tonf engines. The optimized combustors demonstrated superior design characteristics when compared with previous non-optimized results. Wall temperatures at the nozzle throat were optimized to satisfy the requirement of 800 K, and specific impulses were maximized. In addition, the target turbine power and a burned-gas temperature of 1000 K were obtained from the optimized gas-generator design.

  1. Trenchless rehabilitation: Which choice for gas distribution pipe replacement?

    SciTech Connect

    Kramer, S.R.; Gauthier, S.W.

    1995-01-01

    Replacement or rehabilitation of deteriorating gas piping currently relies largely on open-cut excavation or pipe insertion. Open-cut replacement is satisfactory for communities where adverse environmental impact can be tolerated and road closures and traffic delays are kept to a minimum. However, most of the systems in need of replacement/rehabilitation are in urban areas where environmental impact, traffic delays, and site restoration costs are costly. With these parameters in mind, the Gas Research Institute (GRI); and its member organizations designed a research program to test and evaluate promising trenchless technologies for potential use in gas distribution rehabilitation projects. The programs`s goals were to identify product strengths, weaknesses, cost, applications, and recognition of areas which needed modification or further development. During this research a significant amount of data were gathered. All rehabilitation systems maximize pipe capacity while minimizing surface disruptions. Cost savings realized by some of the participating utilities was significant. This is even more impressive when one considers that this was the first gas installation for some of the methods. A summary of advantages, disadvantages, and lessons learned from each process is shown on Tables 2--6. Comments listed are for field trials conducted and may not be accurate or applicable to other projects. A common limitation of all rehabilitation methods is lack of a complete system with appropriate tees, fittings, transition materials, and other connection devices.

  2. The variation in molecular gas depletion time among nearby galaxies: what are the main parameter dependences?

    NASA Astrophysics Data System (ADS)

    Huang, Mei-Ling; Kauffmann, Guinevere

    2014-09-01

    We re-analyse correlations between global molecular gas depletion time (tdep) and galaxy parameters for nearby galaxies from the COLD GASS survey. We improve on previous work of Saintonge et al. by estimating star formation rates using the combination of Galaxy Evolution Explorer far-ultraviolet and Wide-field Infrared Survey Explorer 22 μm data and by deriving tdep within a fixed aperture set by the beam size of gas observation. In our new study, we find correlations with much smaller scatter. Dependences of the depletion time on galaxy structural parameters such as stellar surface density and concentration index are now weak or absent. We demonstrate that the primary global parameter correlation is between tdep and specific star formation rate (sSFR); all other remaining correlations can be shown to be induced by this primary dependence. This implies that galaxies with high current-to-past-averaged star formation activity, will drain their molecular gas reservoir sooner. We then analyse tdep on 1 kpc scales in galactic discs using data from the HERA CO-Line Extragalactic Survey survey. There is remarkably good agreement between the global tdep-sSFR relation for the COLD GASS galaxies and that derived for 1 kpc scale grids in discs. This leads to the conclusion that the local molecular gas depletion time in galactic discs is dependent on the local fraction of young-to-old stars.

  3. 78 FR 41398 - SourceGas Distribution LLC; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-10

    ... Energy Regulatory Commission SourceGas Distribution LLC; Notice of Filing Take notice that on June 27, 2013, SourceGas Distribution LLC (SourceGas) filed a Rate Election and revised Statement of Operating... and 284.224). SourceGas proposes to revise its fuel reimbursement quantity percentage to reflect...

  4. 78 FR 56685 - SourceGas Distribution LLC; Notice of Application

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-13

    ... Energy Regulatory Commission SourceGas Distribution LLC; Notice of Application Take notice that on August 27, 2013, SourceGas Distribution LLC (SourceGas), 600 12th Street, Suite 300, Golden, Colorado 80401, filed in Docket No. CP13-540-000 an application pursuant to section 7(f) of the Natural Gas Act...

  5. The confinement of star-forming galaxies into a main sequence through episodes of gas compaction, depletion and replenishment

    NASA Astrophysics Data System (ADS)

    Tacchella, Sandro; Dekel, Avishai; Carollo, C. Marcella; Ceverino, Daniel; DeGraf, Colin; Lapiner, Sharon; Mandelker, Nir; Primack Joel, R.

    2016-04-01

    Using cosmological simulations, we address the properties of high-redshift star-forming galaxies (SFGs) across their main sequence (MS) in the plane of star formation rate (SFR) versus stellar mass. We relate them to the evolution of galaxies through phases of gas compaction, depletion, possible replenishment, and eventual quenching. We find that the high-SFR galaxies in the upper envelope of the MS are compact, with high gas fractions and short depletion times (`blue nuggets'), while the lower SFR galaxies in the lower envelope have lower central gas densities, lower gas fractions, and longer depletion times, consistent with observed gradients across the MS. Stellar-structure gradients are negligible. The SFGs oscillate about the MS ridge on time-scales ˜0.4tHubble (˜1 Gyr at z ˜ 3). The propagation upwards is due to gas compaction, triggered, e.g. by mergers, counter-rotating streams, and/or violent disc instabilities. The downturn at the upper envelope is due to central gas depletion by peak star formation and outflows while inflow from the shrunken gas disc is suppressed. An upturn at the lower envelope can occur once the extended disc has been replenished by fresh gas and a new compaction can be triggered, namely as long as the replenishment time is shorter than the depletion time. The mechanisms of gas compaction, depletion, and replenishment confine the SFGs to the narrow (±0.3 dex) MS. Full quenching occurs in massive haloes (Mvir > 1011.5 M⊙) and/or at low redshifts (z < 3), where the replenishment time is long compared to the depletion time, explaining the observed bending down of the MS at the massive end.

  6. Comparison of Multi Disk Exponential Gas Distribution vs. Single Disk

    NASA Astrophysics Data System (ADS)

    Rao, Erica; O'Brien, James

    2013-04-01

    In fitting galactic rotation curves to data, most standard theories make use of a single exponential disk approximation of the gas distribution to account for the HI synthesis data observed at various radio telescope facilities. We take a sample of surface brightness profiles from The HI Nearby Galaxy Survey (THINGS), and apply both single disk exponentials and Multi-Disk exponentials, and use these various models to see how the modelling procedure changes the Newtonian prediction of the mass of the galaxy. Since the missing mass problem has not been fully explained in large spiral galaxies, different modelling procedures could account for some of the missing matter.

  7. Momentum distribution function of the electron gas at metallic densities

    NASA Astrophysics Data System (ADS)

    Takada, Yasutami; Yasuhara, H.

    1991-10-01

    The momentum distribution function n(k) of the electron gas is calculated in the effective-potential-expansion method at metallic densities. The recently established self-consistency relation between n(k) and the correlation energy [Y. Takada and T. Kita, J. Phys. Soc. Jpn. 60, 25 (1991)] is employed to check the accuracy of our results. This check shows that the effective-potential-expansion method provides probably the exact and at least more accurate results of n(k) than all the other methods that have given n(k) thus far.

  8. Direct Energy Exchange Enhancement in Distributed Injection Light Gas Launchers

    SciTech Connect

    Alger, T W; Finucane, R G; Hall, J P; Penetrante, B M; Uphaus, T M

    2000-04-06

    It is not widely acknowledged or appreciated that conventional, two-stage light-gas launchers do not efficiently apply their high breech pressures to the design intent: accelerating the projectile. Our objective in this project was to carry out the analysis, design, construction, and testing of a new class of launchers that will address this limitation. Our particular application is to expand the pressure range of the conventional, two-stage gas launcher to overlap and validate the pressure regimes previously attainable only with shock waves generated by nuclear explosions, lasers, or multistage conventional explosions. That is, these launchers would have the capability to conduct--in a laboratory setting--high-velocity-impact, equation-of-state (EOS) measurements at up to 2-TPa (20 Mbar) pressure levels in high-Z materials. Our design entailed a new class of distributed-injection, gas-dynamic launchers that are designed to use a boat-tail projectile to overcome the fundamental gas-expansion phenomena known as escape velocity (the Riemann limit). Our program included analytical, numerical, and experimental studies of the fast gas release flow technique that is central to the success of our approach. The analyses led us to believe that, in a typical configuration, the pressure will be effectively applied to the projectile in a time short relative to its few-microsecond traverse time; the experimental program we conducted during FY1999 supported these estimates. In addition, our program revealed dramatic increased efficiency in this process that was previously unknown to the launcher community. The most fundamental practical restrictions on the performance of any gas launcher are the ability of the launcher to (1) contain pressure in a reservoir, and (2) effectively apply that pressure to the base of a moving projectile. Our gas-release test-fixture experiments showed that our design was capable of applying nearly twice the pressure to the projectile that is

  9. SOIL ALUMINUM DISTRIBUTION IN THE NEAR-STREAM ZONE AT THE BEAR BROOK WATERSHED IN MAINE

    EPA Science Inventory

    Near-stream and upslope soil chemical properties were analyzed to infer linkages between soil and surface water chemistry at the Bear Brook Watershed in Maine [BBWM]. Organic and mineral soil samples were collected along six 20 m transects perpendicular to the stream and one 200 ...

  10. Outer Main Belt Asteroids: Identification and Distribution of Four Spectral Groups

    NASA Astrophysics Data System (ADS)

    Takir, D.; Emery, J. P.; McSween, H. Y.

    2011-03-01

    VNIR spectra of outer main belt asteroids have revealed an interesting trend spanning the 2.5 < a < 4.6 AU region. Four spectral groups were identified: the Ceres-like group, the sharp OH group, the rounded H2O group, and the featureless group.

  11. Method of fabricating an integral gas seal for fuel cell gas distribution assemblies

    DOEpatents

    Dettling, Charles J.; Terry, Peter L.

    1988-03-22

    A porous gas distribution plate assembly for a fuel cell, such as a bipolar assembly, includes an inner impervious region wherein the bipolar assembly has good surface porosity but no through-plane porosity and wherein electrical conductivity through the impervious region is maintained. A hot-pressing process for forming the bipolar assembly includes placing a layer of thermoplastic sealant material between a pair of porous, electrically conductive plates, applying pressure to the assembly at elevated temperature, and allowing the assembly to cool before removing the pressure whereby the layer of sealant material is melted and diffused into the porous plates to form an impervious bond along a common interface between the plates holding the porous plates together. The distribution of sealant within the pores along the surface of the plates provides an effective barrier at their common interface against through-plane transmission of gas.

  12. Integral gas seal for fuel cell gas distribution assemblies and method of fabrication

    DOEpatents

    Dettling, Charles J.; Terry, Peter L.

    1985-03-19

    A porous gas distribution plate assembly for a fuel cell, such as a bipolar assembly, includes an inner impervious region wherein the bipolar assembly has good surface porosity but no through-plane porosity and wherein electrical conductivity through the impervious region is maintained. A hot-pressing process for forming the bipolar assembly includes placing a layer of thermoplastic sealant material between a pair of porous, electrically conductive plates, applying pressure to the assembly at elevated temperature, and allowing the assembly to cool before removing the pressure whereby the layer of sealant material is melted and diffused into the porous plates to form an impervious bond along a common interface between the plates holding the porous plates together. The distribution of sealant within the pores along the surface of the plates provides an effective barrier at their common interface against through-plane transmission of gas.

  13. Estimation of Biogenic Gas Distribution in a Northern Peatland Using Surface and Borehole Ground Penetrating Radar

    NASA Astrophysics Data System (ADS)

    Comas, X.; Slater, L.; Reeve, A.

    2005-05-01

    A combination of borehole and surface ground penetrating radar (GPR), time domain reflectometry (TDR) and direct gas sampling was performed to detect biogenic gas accumulation areas in Caribou Bog, a multi-unit peatland in central Maine (Orono). Areas of electromagnetic (EM) signal scattering (or shadow zones, similar to those reported with the seismic reflection method) observed in the surface GPR coincide with sampled zones of high CH4 and CO2 concentration. Shadow zones also correlate with areas of high EM wave velocity detected in zero offset profiles (ZOP) conducted with the borehole GPR, and with areas of low water content inferred with TDR. Application of the Complex Refractive Index Model (CRIM) to the EM wave velocities implies that the anomalous high velocity zones results from a volumetric gas content of 7% and 10% for a peat soil porosity of 91% and 94% respectively. In the absence of gas, the CRIM model predicts a porosity value of only 84% to reach the maximum EM wave velocity recorded, a value not supported by our peat porosity measurements in the laboratory and inconsistent with the high porosity of peat recorded by others. Strong reflectors detected with the surface GPR are interpreted as confining layers acting as biogenic gas traps and inducing overpressurized biogenic gas pockets as postulated by others. Spatial gas distribution and volumetric gas content can be roughly estimated considering the areas affected by EM wave blanking. These findings also have implications for the monitoring of temporal behavior of biogenic gas emissions to the atmosphere from peatlands.

  14. Gas and dust in the pre-main-sequence multiple system GG Tauri

    NASA Technical Reports Server (NTRS)

    Koerner, D. W.; Sargent, A. I.; Beckwith, S. V. W.

    1993-01-01

    We present 1.4 and 2.7 mm aperture synthesis maps of the gas and dust continuum emission around GG Tauri, a very young component of a premain-sequence multiple star system; both GG Tau and its apparent companion, GG Tau/c, at 1500 AU separation, are themselves binaries. At 1.4 mm, dust continuum emission of about 750 AU in extent is associated with GG Tau, and a secondary peak is near GG Tau/c. Spectral line images reveal gaseous structure around GG Tau, elongated along the GG Tau-GG Tau/c axis. There is some suggestion that the gas associated with GG Tau/c alone is extended in a different direction. Marked changes in the morphology and velocity structure of the molecular emission near GG Tau/c also indicate that this system is differently oriented. Clumps between the two systems may be vestiges of a connecting bar. GG Tau and GG Tau/c appear to have originated in a common cloud; their different systemic orientations suggest that they formed from an initially prolate cloud rather than from an extensive and highly flattened disk.

  15. [Vertical distribution of main species captured by tuna longline fishery in the southeast Pacific Ocean].

    PubMed

    Zhang, Yan-bo; Dai, Xiao-jie; Zhu, Jiang-feng; Gao, Chun-xia; Wu, Feng; Zheng, Xiao-chun

    2015-03-01

    Information of vertical distribution of longline-hook species is important for the development of effective measures to mitigate bycatch, and very helpful for better understanding of the oceanic ecosystem structure and implementation of ecosystem-based fisheries management. Based on depth data of longline hook and capture hook position of pelagic species, collected by on board scientific observer in the southeast Pacific Ocean from September 2013 to January 2014, shoaling rate of longline hook and vertical distribution of 14 pelagic species were analyzed. The results showed that the relative shoaling rate range of longline hook was 8.9% - 17.1%, and the average relative shoaling rate was 13.5%. The depth ranges of 14 capture species were different. The species with the deepest depth was Opah (Lampris guttatus), and the species with the shallowest depth was skipjack (Katsuwonus pelamis). Except for yellowfin tuna (Thunnus albacares) and striped marlin (Tetrapturus audax), the mean depth and depth distributions of bycatch species were significantly different from that of the targeted albacore tuna (Thunnus alalunga). PMID:26211076

  16. Real gas properties and Space Shuttle Main Engine fuel turbine performance prediction

    NASA Technical Reports Server (NTRS)

    Harloff, G. J.

    1987-01-01

    The H2/H2O mixture thermodynamic and transport properties variations for the Space Shuttle Main Engine (SSME) fuel turbine over a range of temperatures and pressures are examined. The variation of molecular viscosity, specific heat at constant pressure, and Prandtl number for the hydrogen/steam mixture are fitted using polynominal relationships for future turbine performance use. The mixture property variations are calculated using GASP and WASP computer programs. The air equivalent performance of the SSME fuel turbine is computed.

  17. Potential effects of climate change on the distribution range of the main silicate sinker of the Southern Ocean

    PubMed Central

    Pinkernell, Stefan; Beszteri, Bánk

    2014-01-01

    Fragilariopsis kerguelensis, a dominant diatom species throughout the Antarctic Circumpolar Current, is coined to be one of the main drivers of the biological silicate pump. Here, we study the distribution of this important species and expected consequences of climate change upon it, using correlative species distribution modeling and publicly available presence-only data. As experience with SDM is scarce for marine phytoplankton, this also serves as a pilot study for this organism group. We used the maximum entropy method to calculate distribution models for the diatom F. kerguelensis based on yearly and monthly environmental data (sea surface temperature, salinity, nitrate and silicate concentrations). Observation data were harvested from GBIF and the Global Diatom Database, and for further analyses also from the Hustedt Diatom Collection (BRM). The models were projected on current yearly and seasonal environmental data to study current distribution and its seasonality. Furthermore, we projected the seasonal model on future environmental data obtained from climate models for the year 2100. Projected on current yearly averaged environmental data, all models showed similar distribution patterns for F. kerguelensis. The monthly model showed seasonality, for example, a shift of the southern distribution boundary toward the north in the winter. Projections on future scenarios resulted in a moderately to negligibly shrinking distribution area and a change in seasonality. We found a substantial bias in the publicly available observation datasets, which could be reduced by additional observation records we obtained from the Hustedt Diatom Collection. Present-day distribution patterns inferred from the models coincided well with background knowledge and previous reports about F. kerguelensis distribution, showing that maximum entropy-based distribution models are suitable to map distribution patterns for oceanic planktonic organisms. Our scenario projections indicate

  18. Distribution and sources of polycyclic aromatic hydrocarbons in main aquacultural areas in Guangdong, China

    NASA Astrophysics Data System (ADS)

    Maskaoui, Khalid; Hu, Zhong; Zhou, Junliang; Han, Yali

    2007-04-01

    The environmental quality status of Daya Bay (22.56-22.77°N, 114.51-114.73°E), a main aquaculture area in Guangdong of China, was investigated using 16 polycyclic aromatic hydrocarbon (PAH) sediment samples of the bay. The total concentrations of 16 PAHs varied from 115 to 1 134 ng/g dry weight. The PAH composition pattern in sediments suggest dominance of 4-ring PAHs in Sites 2 and 4, and the ratio of certain related PAHs indicated important pyrolytic and petrogenic sources. The results enhance the understanding of current contamination levels and make a better assessment of likely impacts of organic contamination on ecosystems and the sustainability of local aquaculture in the area especially after the establishment of the Nuclear Power Station by the bay.

  19. Energy conservation: The main factor for reducing greenhouse gas emissions in the former Soviet Union

    SciTech Connect

    Bashmakov, I.A.; Chupyatov, V.P.

    1991-12-01

    The energy intensity of the former Soviet Union is more than twice that of other market economics in similar stages of economic development. Low energy efficiency in the Soviet Union has contributed significantly to global carbon and other greenhouse gas emissions. The technological potential for energy conservation in the former Soviet Union is the largest in the world. The inefficiencies of the previously command-system economy, however, have provided little incentive for conserving energy. The present transition to a market-based economy should encourage the incorporation of energy-efficiency improvements in order for the former Soviet Union to successfully lower its energy intensity. There are several obstacles that limit implementing energy conservation: for example, energy prices and discount rates influence the volume of investment in energy efficiency. Nevertheless, cost-effective measures for energy conservative do exist even in the most energy-intensive sectors of the Soviet economy and should form the core of any energy conservation program. The overall cost-effective potential for carbon savings in the former Soviet Union is estimated to be 280 to 367 million tons of carbon per year by the year 2005, or 23 to 29 percent of 1988 energy-related emissions.

  20. 78 FR 6318 - SourceGas Distribution LLC; Notice of Petition for Rate Approval

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-30

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission SourceGas Distribution LLC; Notice of Petition for Rate Approval Take notice that on January 15, 2013, SourceGas Distribution LLC (SourceGas) filed a rate election pursuant...

  1. 77 FR 28374 - SourceGas Distribution LLC; Notice of Compliance Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-14

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission SourceGas Distribution LLC; Notice of Compliance Filing Take notice that on April 30, 2012, SourceGas Distribution LLC (SourceGas) filed a revised Statement of Operating...

  2. Consideration of Grain Size Distribution in the Diffusion of Fission Gas to Grain Boundaries

    SciTech Connect

    Paul C. Millett; Yongfeng Zhang; Michael R. Tonks; S. B. Biner

    2013-09-01

    We analyze the accumulation of fission gas on grain boundaries in a polycrystalline microstructure with a distribution of grain sizes. The diffusion equation is solved throughout the microstructure to evolve the gas concentration in space and time. Grain boundaries are treated as infinite sinks for the gas concentration, and we monitor the cumulative gas inventory on each grain boundary throughout time. We consider two important cases: first, a uniform initial distribution of gas concentration without gas production (correlating with post-irradiation annealing), and second, a constant gas production rate with no initial gas concentration (correlating with in-reactor conditions). The results show that a single-grain-size model, such as the Booth model, over predicts the gas accumulation on grain boundaries compared with a polycrystal with a grain size distribution. Also, a considerable degree of scatter, or variability, exists in the grain boundary gas accumulation when comparing all of the grain boundaries in the microstructure.

  3. Kinetic Equation for Two-Particle Distribution Function in Boltzmann Gas Mixtures and Equation of Motion for Quasiparticle Pairs

    NASA Astrophysics Data System (ADS)

    Saveliev, V. L.

    2011-05-01

    Pair collisions is the main interaction process in the Boltzmann gas dynamics. By making use of exactly the same physical assumptions as was used by Ludwig Boltzmann we write the kinetic equation for two-particle distribution function of molecules in the gas mixtures. Instead of the collision integral, there are the linear scattering operator and the chaos projector in the right part of this equation. Because the scattering operator is more simple then Boltzmann collision integral this equation opens new opportunities for mathematical description of the Boltzmann gas dynamics.

  4. THE MOLECULAR GAS CONTENT OF z = 3 LYMAN BREAK GALAXIES: EVIDENCE OF A NON-EVOLVING GAS FRACTION IN MAIN-SEQUENCE GALAXIES AT z > 2

    SciTech Connect

    Magdis, Georgios E.; Rigopoulou, D.; Daddi, E.; Sargent, M.; Elbaz, D.; Gobat, R.; Tan, Q.; Aussel, H.; Feruglio, C.; Charmandaris, V.; Dickinson, M.; Reddy, N.

    2012-10-10

    We present observations of the CO[J = 3 {yields} 2] emission toward two massive and infrared luminous Lyman break galaxies (LBGs) at z = 3.21 and z = 2.92, using the IRAM Plateau de Bure Interferometer, placing first constraints on the molecular gas masses (M{sub gas}) of non-lensed LBGs. Their overall properties are consistent with those of typical (main-sequence) galaxies at their redshifts, with specific star formation rates {approx}1.6 and {approx}2.2 Gyr{sup -1}, despite their large infrared luminosities (L{sub IR} Almost-Equal-To (2-3) Multiplication-Sign 10{sup 12} L{sub Sun }) derived from Herschel. With one plausible CO detection (spurious detection probability of 10{sup -3}) and one upper limit, we investigate the evolution of the molecular gas-to-stellar mass ratio (M{sub gas}/M{sub *}) with redshift. Our data suggest that the steep evolution of M{sub gas}/M{sub *} of normal galaxies up to z {approx} 2 is followed by a flattening at higher redshifts, providing supporting evidence for the existence of a plateau in the evolution of the specific star formation rate at z > 2.5.

  5. Numerical solutions of ideal quantum gas dynamical flows governed by semiclassical ellipsoidal-statistical distribution

    PubMed Central

    Yang, Jaw-Yen; Yan, Chih-Yuan; Diaz, Manuel; Huang, Juan-Chen; Li, Zhihui; Zhang, Hanxin

    2014-01-01

    The ideal quantum gas dynamics as manifested by the semiclassical ellipsoidal-statistical (ES) equilibrium distribution derived in Wu et al. (Wu et al. 2012 Proc. R. Soc. A 468, 1799–1823 (doi:10.1098/rspa.2011.0673)) is numerically studied for particles of three statistics. This anisotropic ES equilibrium distribution was derived using the maximum entropy principle and conserves the mass, momentum and energy, but differs from the standard Fermi–Dirac or Bose–Einstein distribution. The present numerical method combines the discrete velocity (or momentum) ordinate method in momentum space and the high-resolution shock-capturing method in physical space. A decoding procedure to obtain the necessary parameters for determining the ES distribution is also devised. Computations of two-dimensional Riemann problems are presented, and various contours of the quantities unique to this ES model are illustrated. The main flow features, such as shock waves, expansion waves and slip lines and their complex nonlinear interactions, are depicted and found to be consistent with existing calculations for a classical gas. PMID:24399919

  6. Structural and mechanical defects of materials of offshore and onshore main gas pipelines after long-term operation

    NASA Astrophysics Data System (ADS)

    Maruschak, Pavlo; Panin, Sergey; Danyliuk, Iryna; Poberezhnyi, Lyubomyr; Pyrig, Taras; Bishchak, Roman; Vlasov, Ilya

    2015-10-01

    The study has established the main regularities of a fatigue failure of offshore gas steel pipes installed using S-lay and J-lay methods.We have numerically analyzed the influence of preliminary deformation on the fatigue life of 09Mn2Si steel at different amplitudes of cyclic loading. The results have revealed the regularities of formation and development of a fatigue crack in 17Mn1Si steel after 40 years of underground operation. The quantitative analysis describes the regularities of occurrence and growth of fatigue cracks in the presence of a stress concentration.

  7. Development of capsules and pigs for inspection of small-diameter gas distribution pipelines

    SciTech Connect

    Hosohara, Y.; Seki, A.; Yasui, K.

    1988-01-01

    To inspect external corrosion of small-diameter gas distribution pipelines precisely, the three major gas companies of Japan have jointly developed inspection capsules (very small pigs) and pigs for the first time in the world. The laboratory test has been completed and the field test is now in progress. The inspection techniques developed are the following two methods: 1. Inspection methods for 2- and 3-inch screw-jointed mains: The inspection capsule is inserted through a launcher into a straight pipeline of 30m length on each side (60m total span) in live condition. The remote-field eddy current method and the impressed-current magnetic leakage flux method were adopted. 2. Inspection methods for weld-joint 4-, 8- and 12-inche mains: The pipeline is cut off (down to less than 300m length), and gas is purged by air. The inspection pigs pass through miter bends, short elbows of 1.5 DR and sleeve joints. The magnetic leakage flux method was adopted, while different methods of travel were adopted by the three contractors.

  8. Distributed and decentralized state estimation in gas networks as distributed parameter systems.

    PubMed

    Ahmadian Behrooz, Hesam; Boozarjomehry, R Bozorgmehry

    2015-09-01

    In this paper, a framework for distributed and decentralized state estimation in high-pressure and long-distance gas transmission networks (GTNs) is proposed. The non-isothermal model of the plant including mass, momentum and energy balance equations are used to simulate the dynamic behavior. Due to several disadvantages of implementing a centralized Kalman filter for large-scale systems, the continuous/discrete form of extended Kalman filter for distributed and decentralized estimation (DDE) has been extended for these systems. Accordingly, the global model is decomposed into several subsystems, called local models. Some heuristic rules are suggested for system decomposition in gas pipeline networks. In the construction of local models, due to the existence of common states and interconnections among the subsystems, the assimilation and prediction steps of the Kalman filter are modified to take the overlapping and external states into account. However, dynamic Riccati equation for each subsystem is constructed based on the local model, which introduces a maximum error of 5% in the estimated standard deviation of the states in the benchmarks studied in this paper. The performance of the proposed methodology has been shown based on the comparison of its accuracy and computational demands against their counterparts in centralized Kalman filter for two viable benchmarks. In a real life network, it is shown that while the accuracy is not significantly decreased, the real-time factor of the state estimation is increased by a factor of 10. PMID:26138354

  9. Development of colorless distributed combustion for gas turbine application

    NASA Astrophysics Data System (ADS)

    Arghode, Vaibhav Kumar

    Colorless Distributed Combustion (CDC) is investigated for gas turbine engine application due to its benefit for ultra-low pollutant emission, improved pattern factor, low noise emission, stable combustion and low pressure drop, alleviation of combustion instabilities and increased life of turbine blades with less air cooling requirements. The CDC is characterized by discrete and direct injection of fuel and air at high velocity and the reaction zone is stabilized due to controlled aerodynamics inside the combustor and wider (radially) shear layer mixing. Mixing between the injected air and product gases to form hot and diluted oxidant is required followed by rapid mixing with the fuel. This results in distributed reaction zone instead of a concentrated flame front as observed in conventional diffusion flames and hence, to avoid hot spot regions and provide reduced NOx and CO emissions. The focus of this dissertation is to develop and demonstrate CDC for application to stationary gas turbine combustors which generally operate at thermal intensity of 15MW/m3-atm. However, higher thermal intensity is desirable to reduce hardware costs due to smaller weight and volume of the combustors. Design of high thermal intensity CDC combustor requires careful control of critical parameters, such as, gas recirculation, fuel/oxidizer mixing and residence time characteristics via careful selection of different air and fuel injection configurations to achieve desirable combustion characteristics. This dissertation examines sequential development of low emission colorless distributed combustor operating from thermal intensity of 5MW/m3-atm up to 198MW/m3-atm. Initially, various fuel and air injection configurations were investigated at a low thermal intensity of 5MW/m 3-atm. Further investigations were performed for a simpler combustor having single air and fuel injection ports for medium thermal intensity range of 28-57MW/m3-atm. Among the flow configurations investigated, reverse

  10. Determination of the main parameters of the cyclone separator of the flue gas produced during the smelting of secondary aluminum

    NASA Astrophysics Data System (ADS)

    Matusov, Jozef; Gavlas, Stanislav

    2016-06-01

    One way how is possible to separate the solid particulate pollutants from the flue gas is use the cyclone separators. The cyclone separators are very frequently used separators due to the simplicity of their design and their low operating costs. Separation of pollutants in the form of solids is carried out using three types of forces: inertia force, centrifugal force, gravity force. The main advantage is that cyclone consist of the parts which are resistant to wear and have long life time, e.g. various rotating and sliding parts. Mostly are used as pre-separators, because they have low efficiency in the separation of small particles. Their function is to separate larger particles from the flue gases which are subsequently cleaned in the other device which is capable of removing particles smaller than 1 µm, which is limiting size of particle separation. The article will deal with the issue of calculating the basic dimensions and main parameters of the cyclone separator from flue gas produced during the smelting of secondary aluminum.

  11. Measurements of Gas Bubble Size Distributions in Flowing Liquid Mercury

    SciTech Connect

    Wendel, Mark W; Riemer, Bernie; Abdou, Ashraf A

    2012-01-01

    ABSTRACT Pressure waves created in liquid mercury pulsed spallation targets have been shown to induce cavitation damage on the target container. One way to mitigate such damage would be to absorb the pressure pulse energy into a dispersed population of small bubbles, however, measuring such a population in mercury is difficult since it is opaque and the mercury is involved in a turbulent flow. Ultrasonic measurements have been attempted on these types of flows, but the flow noise can interfere with the measurement, and the results are unverifiable and often unrealistic. Recently, a flow loop was built and operated at Oak Ridge National Labarotory to assess the capability of various bubbler designs to deliver an adequate population of bubbles to mitigate cavitation damage. The invented diagnostic technique involves flowing the mercury with entrained gas bubbles in a steady state through a horizontal piping section with a glass-window observation port located on the top. The mercury flow is then suddenly stopped and the bubbles are allowed to settle on the glass due to buoyancy. Using a bright-field illumination and a high-speed camera, the arriving bubbles are detected and counted, and then the images can be processed to determine the bubble populations. After using this technique to collect data on each bubbler, bubble size distributions were built for the purpose of quantifying bubbler performance, allowing the selection of the best bubbler options. This paper presents the novel procedure, photographic technique, sample visual results and some example bubble size distributions. The best bubbler options were subsequently used in proton beam irradiation tests performed at the Los Alamos National Laboratory. The cavitation damage results from the irradiated test plates in contact with the mercury are available for correlation with the bubble populations. The most effective mitigating population can now be designed into prototypical geometries for implementation into

  12. Effect of solids concentration distribution on the flue gas desulfurization process

    SciTech Connect

    Jie Zhang; Changfu You; Haiying Qi; Changhe Chen; Xuchang Xu

    2006-06-15

    A dry flue gas desulfurization (FGD) process at 600-800{sup o}C was studied in a pilot-scale circulating fluidized bed (CFB) experimental facility. Various fresh sorbent distribution types and internal structures were modeled numerically to investigate their effect on the gas-solid flow and sulfate reaction characteristics. Experimental results show that, after the fresh sorbent supply was stopped, the desulfurization efficiency declined rapidly even though the sorbent recirculation was maintained. Therefore, the fresh sorbent is the main contributor to the desulfurization process and the primary effect of the recirculated sorbent was to evenly distribute the fresh sorbent and to prolong the sorbent particle residence time. The numerical results demonstrate that the desulfurization efficiency varied greatly for the various fresh sorbent bottom injection methods. The desulfurization efficiency of the bottom-even injection method was 1.5 times that of the bottom two-sided injection method. Internal structures effectively improved the fresh sorbent solids concentration distribution and the desulfurization efficiency. Optimized internal structures increased the desulfurization efficiency of the bottom two-sided injection method by 46%, so that it was very close to that of the bottom-even injection method with only a 4.6% difference. 16 refs., 6 figs., 2 tabs.

  13. Effect of solids concentration distribution on the flue gas desulfurization process.

    PubMed

    Zhang, Jie; You, Changfu; Qi, Haiying; Chen, Changhe; Xu, Xuchang

    2006-06-15

    A dry flue gas desulfurization (FGD) process at 600-800 degrees C was studied in a pilot-scale circulating fluidized bed (CFB) experimental facility. Various fresh sorbent distribution types and internal structures were modeled numerically to investigate their effect on the gas-solid flow and sulfate reaction characteristics. Experimental results show that, after the fresh sorbent supply was stopped, the desulfurization efficiency declined rapidly even though the sorbent recirculation was maintained. Therefore, the fresh sorbent is the main contributor to the desulfurization process and the primary effect of the recirculated sorbent was to evenly distribute the fresh sorbent and to prolong the sorbent particle residence time. The numerical results demonstrate thatthe desulfurization efficiency varied greatly for the various fresh sorbent bottom injection methods. The desulfurization efficiency of the bottom-even injection method was 1.5 times that of the bottom two-sided injection method. Internal structures effectively improved the fresh sorbent solids concentration distribution and the desulfurization efficiency. Optimized internal structures increased the desulfurization efficiency of the bottom two-sided injection method by 46%, so that it was very close to that of the bottom-even injection method with only a 4.6% difference. PMID:16830575

  14. Golden mussel Limnoperna fortunei (Bivalvia: Mytilidae) distribution in the main hydrographical basins of Uruguay: update and predictions.

    PubMed

    Brugnoli, Ernesto; Clemente, Juan; Boccardi, Lucía; Borthagaray, Ana; Scarabino, Fabrizio

    2005-06-01

    Limnoperna fortunei, an Asiatic rivers bivalve has become a worldwide problematic invasive species causing several water quality and macrofouling problems. In the Neotropical region it was first recorded in 1991 in the Rio de la Plata coast, Buenos Aires province. Since this, it showed a quick upstream invasion into the principals aquatic systems of the Plata Basin. Nevertheless, there is not a study about its invasion and distribution process in aquatic systems of Uruguay. We describe the new records of Limnoperna fortunei in Uruguayan coast of Rio de la Plata, Santa Lucia, Negro and Uruguay Rivers. With these results we aim to estimate its distributional limits for Uruguay main hydrographical basins. We also deal with the role of salinity as the main abiotic factor in limiting the east distribution of this mussel in Uruguayan coast of Rio de la Plata and as a potential determinant of the "new" colonization on the Atlantic and the Merin Lagoon Basins. Its presence in the ecosystems not only can cause changes at the ecosystem level but also endanger the associated community, favoring the displacement and the disappearance of endemic species. PMID:15895160

  15. A Lagrangian view of stratospheric trace gas distributions

    NASA Astrophysics Data System (ADS)

    Schoeberl, M. R.; Sparling, L. C.; Jackman, C. H.; Fleming, E. L.

    2000-01-01

    As a result of photochemistry, some relationship between the stratospheric age of air or mean age and the amount of tracer contained within an air sample is expected. The existence of such a relationship allows inferences about transport history to be made from observations of chemical tracers. This paper lays down the conceptual foundations for the relationship between age and tracer amount for long-lived tracers, developed within a Lagrangian framework. Although the photochemical loss depends not only on the age of the parcel but also on its path, we show that under the "average path approximation" that the path variations are less important than parcel age. The average path approximation then allows us to develop a formal relationship between the age spectrum and the tracer distribution. Using this relationship, tracer-tracer correlations can be interpreted as the result of mixing which connects parts of the "single-path photochemistry curve," a universal path-independent curve that describes the photochemical loss in terms of the total photon exposure. This geometric interpretation of mixing gives rise to constraints on trace gas correlation curves as can be seen in the atmospheric trace molecule spectroscopy observations.

  16. Blimp Robot for Three-Dimensional Gas Distribution Mapping in Indoor Environment

    NASA Astrophysics Data System (ADS)

    Ishida, Hiroshi

    2009-05-01

    Mobile robots equipped with gas sensors can be used for automated measurement tasks including odor trail following, gas source localization, and gas distribution mapping. This article reports on the development of a blimp robot for mapping three-dimensional gas distribution in indoor environments. The blimp robot is programmed to fly randomly so that its trajectory covers everywhere in the given indoor environment. The blimp is equipped with gas sensors to measure gas concentrations and an ultrasonic sonar to measure the height from the floor. The measured data are transmitted to an external PC via a wireless communication module. At the same time, a camera placed on the floor takes a picture of the blimp, and its location is recorded with the gas sensor responses. The experimental results indicate that the blimp robot is effective in mapping three-dimensional gas concentration distribution in indoor environments.

  17. [The distribution of the radionuclides in the main components of lake ecosystems within the Chernobyl NPP exclusion zone].

    PubMed

    2005-01-01

    The results of the studies devoted to the distribution of radionuclides 90Sr, 137Cs, 238Pu, 239 + 240Pu and 241Am in 1998-2003 in main components of Glubokoe Lake and Dalekoe-1 Lake located within Krasnensky flood lands of the Pripyat River (inner exclusion zone of the Chernobyl NPP) were analysed. The data about the radionuclide content in bottom sediments, in water, in seston, in macrozoobenthos (including bivalvia molluscs), in gasteropods molluscs, in higher aquatic plants and in fish are presented. PMID:16080615

  18. Greenhouse Gas Abatement with Distributed Generation in California's Commercial Buildings

    SciTech Connect

    Stadler, Michael; Marnay, Chris; Cardoso, Goncalo; Megel, Olivier; Siddiqui, Afzal; Lai, Judy

    2009-08-15

    Lawrence Berkeley National Laboratory (LBL) is working with the California Energy Commission (CEC) to determine the role of distributed generation (DG) in greenhouse gas reductions. The impact of DG on large industrial sites is well known, and mostly, the potentials are already harvested. In contrast, little is known about the impact of DG on commercial buildings with peak electric loads ranging from 100 kW to 5 MW. We examine how DG with combined heat and power (CHP) may be implemented within the context of a cost minimizing microgrid that is able to adopt and operate various smart energy technologies, such as thermal and photovoltaic (PV) on-site generation, heat exchangers, solar thermal collectors, absorption chillers, and storage systems. We use a mixed-integer linear program (MILP) that has the minimization of a site's annual energy costs as objective. Using 138 representative commercial sites in California (CA) with existing tariff rates and technology data, we find the greenhouse gas reduction potential for California's commercial sector. This paper shows results from the ongoing research project and finished work from a two year U.S. Department of Energy research project. To show the impact of the different technologies on CO2 emissions, several sensitivity runs for different climate zones within CA with different technology performance expectations for 2020 were performed. The considered sites can contribute between 1 Mt/a and 1.8 Mt/a to the California Air Resources Board (CARB) goal of 6.7Mt/a CO2 abatement potential in 2020. Also, with lower PV and storage costs as well as consideration of a CO2 pricing scheme, our results indicate that PV and electric storage adoption can compete rather than supplement each other when the tariff structure and costs of electricity supply have been taken into consideration. To satisfy the site's objective of minimizing energy costs, the batteries will be charged also by CHP systems during off-peak and mid-peak hours and

  19. Gas and dust hydrodynamical simulations of massive lopsided transition discs - I. Gas distribution

    NASA Astrophysics Data System (ADS)

    Zhu, Zhaohuan; Baruteau, Clément

    2016-06-01

    Motivated by lopsided structures observed in some massive transition discs, we have carried out 2D numerical simulations to study vortex structure in massive discs, including the effects of disc self-gravity and the indirect force which is due to the displacement of the central star from the barycentre of the system by the lopsided structure. When only the indirect force is included, we confirm the finding by Mittal & Chiang that the vortex becomes stronger and can be more than two pressure scale heights wide, as long as the disc-to-star mass ratio is ≳1 per cent. Such wide vortices can excite strong density waves in the disc and therefore migrate inwards rapidly. However, when disc self-gravity is also considered in simulations, self-gravity plays a more prominent role on the vortex structure. We confirm that when the disc Toomre Q parameter is smaller than π/(2h), where h is the disc's aspect ratio, the vortices are significantly weakened and their inward migration slows down dramatically. Most importantly, when the disc is massive enough (e.g. Q ˜ 3), we find that the lopsided gas structure orbits around the star at a speed significantly slower than the local Keplerian speed. This sub-Keplerian pattern speed can lead to the concentration of dust particles at a radius beyond the lopsided gas structure (as shown in Paper II). Overall, disc self-gravity regulates the vortex structure in massive discs and the radial shift between the gas and dust distributions in vortices within massive discs may be probed by future observations.

  20. Numerical analysis of flow non-uniformity in the hot gas manifold of the Space Shuttle main engine

    NASA Technical Reports Server (NTRS)

    Thoenes, J.; Robertson, S. J.; Ratliff, A. W.; Anderson, P. G.

    1985-01-01

    Three-dimensional viscous flow in a conceptual hot gas manifold (HGM) for the Space Shuttle Main Engine High Pressure Fuel Turbopump (SSME HPFTP) was numerically analyzed. A finite difference scheme was used to solve the Navier-Stokes equations. The exact geometry of the SSME HGM was modeled using boundary fitted curvilinear coordinates and the General Interpolants Method (GIM) code. Slight compressibility of the subsonic flow was modeled using a linearized equation of state with artificial compressibility. A time relaxation method was used to obtain a steady state solution. The feasibility and potential usefulness of computational methods in assisting the design of SSME components which involves the flow of fluids within complex geometrical shapes is demonstrated.

  1. 77 FR 34123 - Pipeline Safety: Public Meeting on Integrity Management of Gas Distribution Pipelines

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-08

    ... published on December 4, 2009, (74 FR 63906). The rule required that operators of gas distribution pipelines... Pipeline and Hazardous Materials Safety Administration Pipeline Safety: Public Meeting on Integrity... jointly sponsoring a public meeting on Implementing Integrity Management of Gas Distribution...

  2. 77 FR 10490 - SourceGas Distribution LLC; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-22

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission SourceGas Distribution LLC; Notice of Filing Take notice that on February 14, 2012, SourceGas Distribution LLC submitted a revised baseline filing of their Statement of...

  3. 78 FR 13661 - National Fuel Gas Distribution Corporation; Notice of Petition for Rate Approval

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-28

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission National Fuel Gas Distribution Corporation; Notice of Petition for Rate Approval Take notice that on February 12, 2013, National Fuel Gas Distribution Corporation filed...

  4. 75 FR 51032 - National Fuel Gas Distribution Corporation; Notice of Baseline Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-18

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission National Fuel Gas Distribution Corporation; Notice of Baseline Filing August 12, 2010. Take notice that on August 10, 2010, National fuel Gas Distribution Corporation submitted...

  5. How is Order 636 affecting the gas distribution industry

    SciTech Connect

    Margossian, K.M. )

    1993-12-01

    This paper is part of a six part series on how interstate gas pipelines have been affected by Order 636. These papers are written in an interview format with different individuals representing the pipeline, natural gas, utility, and regulatory side of this new regulation. The issues deal with how it has affected these industries; how the relationships have changed between suppliers, marketers, distributors, etc.; the risks now involved in marketing, shipping, and buying gas products; and new technology developments have resulted to comply with the new regulations. This paper is an interview with Kenneth M. Magossian, president and chief operating officer of Commonwealth Gas Co. and Hopkinton LNG Corp.

  6. A New Efficient Method for Generating Conformations of Unfolded Proteins with Diverse Main-Chain Dihedral-Angle Distributions.

    PubMed

    Seki, Yasutaka; Shimbo, Yudai; Nonaka, Takamasa; Soda, Kunitsugu

    2011-07-12

    A new method for generating polypeptide-chain conformations has been developed for studying structural characteristics of unfolded proteins. It enables us to generate a large number of conformations very rapidly by avoiding atomic collisions efficiently with the use of main-chain dihedral-angle distributions derived from a crystal-structure database of proteins. In addition, combining main-chain dihedral-angle distributions for the amino acid residues incorporated in different secondary structures, we can obtain diverse conformational ensembles with different structural features. Structural characteristics of proteins denatured in high-concentration denaturant solution were analyzed by comparing predictions from this method with results from solution X-ray scattering (SXS) measurement. Analysis of the dependence of the mean square radius (Rsq) of protein on the number of residues and the shape of its Kratky profile has confirmed that the highly denaturing solvent serves as a good solvent in accordance with previous reports. It was also found that, in order for a conformational ensemble to reproduce experimental data, the percentage in which main-chain dihedral angles are found in the α region must be in the range of 20-40%. It agrees with studies on the (3)JHNα coupling constant using the multidimensional NMR method. These results confirm that our method for generating diverse conformations of polypeptide chains is very useful to the conformational analysis of unfolded protein, because it enables us to analyze comprehensively both of the local structural features obtained from NMR and the global ones obtained from SXS. PMID:26606484

  7. Estimation of current density distribution of PAFC by analysis of cell exhaust gas

    SciTech Connect

    Kato, S.; Seya, A.; Asano, A.

    1996-12-31

    To estimate distributions of Current densities, voltages, gas concentrations, etc., in phosphoric acid fuel cell (PAFC) stacks, is very important for getting fuel cells with higher quality. In this work, we leave developed a numerical simulation tool to map out the distribution in a PAFC stack. And especially to Study Current density distribution in the reaction area of the cell, we analyzed gas composition in several positions inside a gas outlet manifold of the PAFC stack. Comparing these measured data with calculated data, the current density distribution in a cell plane calculated by the simulation, was certified.

  8. The distribution of warm ionized gas in NGC 891

    NASA Technical Reports Server (NTRS)

    Rand, Richard J.; Kulkarni, Shrinivas R.; Hester, J. Jeff

    1990-01-01

    Narrow-band imaging is presented of the edge-on spiral NGC 891 in the H-alpha and S II 6716, 6731 A forbidden lines. Emission from H II regions confined to the plane of the galaxy and from diffuse gas up to about 4 kpc off the plane is readily detected. The full radial extent of the diffuse emission in the plane is about 30 kpc. NGC 891 is found to have a surface density of diffuse ionized gas twice the Galactic value, a thicker ionized gas layer, and a larger surface density of ionized gas relative to neutral gas. These are interpreted as consequences of a relatively high level of star formation in this galaxy. Other star formation tracers indicate the same conclusion. Many vertical H-alpha filaments, or 'worms,' extending to over 2 kpc off the plane of the galaxy are seen. These worms are interpreted in terms of chimney models for the interstellar media of spirals.

  9. Changes in the Distribution of Atlantic Bluefin Tuna (Thunnus thynnus) in the Gulf of Maine 1979-2005

    PubMed Central

    Golet, Walter J.; Galuardi, Benjamin; Cooper, Andrew B.; Lutcavage, Molly E.

    2013-01-01

    The Gulf of Maine, NW Atlantic Ocean, is a productive, seasonal foraging ground for Atlantic bluefin tuna (Thunnus thynnus), but commercial landings of adult size classes were up to 40% below the allocated total allowable catch between 2004 to 2008 for the rod and reel, harpoon, and purse seine categories in the Gulf of Maine. Reduction in Atlantic bluefin tuna catches in the Gulf of Maine could represent a decline in spawning stock biomass, but given wide-ranging, complex migration patterns, and high energetic requirements, an alternative hypothesis is that their dispersal patterns shifted to regions with higher prey abundance or profitability, reducing availability to U.S. fishing fleets. This study fit generalized linear models to Atlantic bluefin tuna landings data collected from fishermen’s logbooks (1979-2005) as well as the distances between bluefin tuna schools and Atlantic herring (Clupeaharengus), a primary prey species, to test alternative hypotheses for observed shifts in Atlantic bluefin tuna availability in the Gulf of Maine. For the bluefin model, landings varied by day of year, latitude and longitude. The effect of latitude differed by day of year and the effect of longitude differed by year. The distances between Atlantic bluefin tuna schools and Atlantic herring schools were significantly smaller (p<0.05) than would be expected from a randomly distributed population. A time series of average bluefin tuna school positions was positively correlated with the average number of herring captured per tow on Georges Bank in spring and autumn surveys respectively (p<0.01, r2=0.24, p<0.01, r2=0.42). Fishermen’s logbooks contributed novel spatial and temporal information towards testing these hypotheses for the bluefin tuna fishery. PMID:24069420

  10. Changes in the distribution of atlantic bluefin tuna (Thunnus thynnus) in the Gulf of Maine 1979-2005.

    PubMed

    Golet, Walter J; Galuardi, Benjamin; Cooper, Andrew B; Lutcavage, Molly E

    2013-01-01

    The Gulf of Maine, NW Atlantic Ocean, is a productive, seasonal foraging ground for Atlantic bluefin tuna (Thunnus thynnus), but commercial landings of adult size classes were up to 40% below the allocated total allowable catch between 2004 to 2008 for the rod and reel, harpoon, and purse seine categories in the Gulf of Maine. Reduction in Atlantic bluefin tuna catches in the Gulf of Maine could represent a decline in spawning stock biomass, but given wide-ranging, complex migration patterns, and high energetic requirements, an alternative hypothesis is that their dispersal patterns shifted to regions with higher prey abundance or profitability, reducing availability to U.S. fishing fleets. This study fit generalized linear models to Atlantic bluefin tuna landings data collected from fishermen's logbooks (1979-2005) as well as the distances between bluefin tuna schools and Atlantic herring (Clupeaharengus), a primary prey species, to test alternative hypotheses for observed shifts in Atlantic bluefin tuna availability in the Gulf of Maine. For the bluefin model, landings varied by day of year, latitude and longitude. The effect of latitude differed by day of year and the effect of longitude differed by year. The distances between Atlantic bluefin tuna schools and Atlantic herring schools were significantly smaller (p<0.05) than would be expected from a randomly distributed population. A time series of average bluefin tuna school positions was positively correlated with the average number of herring captured per tow on Georges Bank in spring and autumn surveys respectively (p<0.01, r(2)=0.24, p<0.01, r(2)=0.42). Fishermen's logbooks contributed novel spatial and temporal information towards testing these hypotheses for the bluefin tuna fishery. PMID:24069420

  11. Rock avalanche occurrence in the San Juan province (Argentina): an analysis of their spatial distribution and main forcing factors

    NASA Astrophysics Data System (ADS)

    Penna, Ivanna; Tonini, Marj; Vega Orozco, Carmen D.; Longchamp, Céline; Derron, Marc-Henri; Jaboyedoff, Michel

    2013-04-01

    Rock avalanches are frequent phenomena in the Argentinean Andes and a particular high concentration of these events is observed in the Northwest (~25°S) and in the Central Andes from 30°S until the transition with the Patagonian Andes (~38°S). Tectonic deformation and seismicity are generally proposed as main driving factors, with weather and lithologic conditions playing a subordinate role. From 28°S to 33°S, the subhorizontal subduction of the Nazca plate drives higher shortening rates than in the surrounding areas, and an intense seismicity. Main morphotectonic units in this regions are the Cordillera and Precordillera, separated by the Barreal-Calingasta depression. In the southern central part of the flat subduction area (30°30'°-32°30'S), it is observed high valley incision and maximum local relief of 2900 m, while in the Precordillera main fluvial courses developed in the inter-thrust valleys, where local relief is up to 2400 m. In both mountain ranges, we recognized 34 rock avalanches deposits with volumes up to 0.3 km3. There is no apparent lithologic control on detachments, which involved sedimentary, volcanic and granite rocks, even though ~20% of them were favored by layering orientation. However, about 50% of the inventoried rock avalanches with the greatest volumes, developed along tectonic structures or less than 1 km far from them. The main objective of the present study is to explore the spatial distribution of rock avalanche deposits, and compare it with the instrumental seismicity and landscape conditions by means of statistical tools (e.g. exploratory data analyses, Ripley's K-function). Those analyses allow to highlight the spatial correlation between the geological events. Moreover, to visually display the detected cluster spatial patterns we elaborated kernel density maps. Our findings revealed that most of the rock avalanches show a high spatial aggregation mainly between 31°20'S-31°50'S. Main concentration of bedrock landslides

  12. A Herschel [C ii] Galactic plane survey. I. The global distribution of ISM gas components

    NASA Astrophysics Data System (ADS)

    Pineda, J. L.; Langer, W. D.; Velusamy, T.; Goldsmith, P. F.

    2013-06-01

    Context. The [C ii] 158 μm line is an important tool for understanding the life cycle of interstellar matter. Ionized carbon is present in a variety of phases of the interstellar medium (ISM), including the diffuse ionized medium, warm and cold atomic clouds, clouds in transition from atomic to molecular, and dense and warm photon dominated regions. Aims: Velocity-resolved observations of [C ii] are the most powerful technique available to disentangle the emission produced by these components. These observations can also be used to trace CO-dark H2 gas and determine the total mass of the ISM. Methods: The Galactic Observations of Terahertz C+ (GOT C+) project surveys the [C ii] 158 μm line over the entire Galactic disk with velocity-resolved observations using the Herschel/HIFI instrument. We present the first longitude-velocity maps of the [C ii] emission for Galactic latitudes b = 0°, ±0.5°, and ±1.0°. We combine these maps with those of H i, 12CO, and 13CO to separate the different phases of the ISM and study their properties and distribution in the Galactic plane. Results: [C ii] emission is mostly associated with spiral arms, mainly emerging from Galactocentric distances between 4 and 10 kpc. It traces the envelopes of evolved clouds as well as clouds that are in the transition between atomic and molecular. We estimate that most of the observed [C ii] emission is produced by dense photon dominated regions (~47%), with smaller contributions from CO-dark H2 gas (~28%), cold atomic gas (~21%), and ionized gas (~4%). Atomic gas inside the Solar radius is mostly in the form of cold neutral medium (CNM), while the warm neutral medium gas dominates the outer galaxy. The average fraction of CNM relative to total atomic gas is ~43%. We find that the warm and diffuse CO-dark H2 is distributed over a larger range of Galactocentric distances (4-11 kpc) than the cold and dense H2 gas traced by 12CO and 13CO (4-8 kpc). The fraction of CO-dark H2 to total H2 increases

  13. Evolution of partial ring current ion pitch angle distributions during the main phase of a storm on 17 March 2015

    NASA Astrophysics Data System (ADS)

    Runov, A.; Zhang, X. J.; Angelopoulos, V.

    2016-06-01

    During a severe magnetic storm from 17 to 19 March 2015, three identically instrumented Time History of Events and Macroscale Interactions during Substorms probes crossed the magnetosphere in a string-of-pearls configuration enabling sequential observations of same regions of the magnetosphere with a 2 h time separation. These observations allow us to study the temporal evolution of ion pitch angle distributions (PADs) in the dusk-premidnight sector (between 17 and 20 h magnetic local time) during the storm's main phase. We found that the ion PAD evolved from pancake to isotropic in fewer than 2 h. Analysis of electromagnetic wave spectra revealed the presence of electromagnetic ion cyclotron (EMIC) waves at frequencies below the helium cyclotron frequency. We conclude that the observed pitch angle evolution was due to ion scattering by EMIC waves.

  14. The characteristics of gravity and magnetic fields and the distribution of tight sandstone gas in the Eastern Ordos Basin, China

    NASA Astrophysics Data System (ADS)

    Bingqiang, Yuan; Huaan, Zhang; Chunguan, Zhang; Haihong, Xu; Yunkui, Yan

    2016-02-01

    In order to perform gas exploration and determine the distribution pattern of gas in the Yanchang Oil Field in the eastern part of the North Shaanxi Slope, Ordos Basin, China, gravity and magnetic survey data were systemically collated, processed, and interpreted in combination with the drilling data and recent seismic data. The genesis of gravity and magnetic anomalies and the relationship between the characteristics of the gravity and magnetic fields and known gas distribution were explored in order to predict the favourable exploration targets for gas. Gravity anomalies resulted both from the lateral variation in density of the basement rock and lateral lithologic transformation in the sedimentary cover. The regional magnetic anomalies were mainly caused by the basement metamorphic rocks and the residual magnetic anomalies may reflect the amount and general location of the volcanic materials in the overlying strata. The residual gravity and magnetic anomalies generated by high-density sandstone and high content of volcanics in the gas reservoir of the upper Paleozoic distorted and deformed the anomaly curves when they were stacked onto the primary background anomaly. The gas wells were generally found to be located in the anomaly gradient zones, or the distorted part of contour lines, and the flanks of high and low anomalies, or the transitional zones between anomaly highs and lows. The characteristics of gravity and magnetic fields provide significant information that can be used for guidance when exploring the distribution of gas. Based on these characteristics, five favourable areas for gas exploration were identified; these are quasi-equally spaced like a strip extending from the southeast to the northwest.

  15. The characteristics of gravity and magnetic fields and the distribution of tight sandstone gas in the eastern Ordos Basin, China

    NASA Astrophysics Data System (ADS)

    Yuan, Bingqiang; Zhang, Huaan; Zhang, Chunguan; Xu, Haihong; Yan, Yunkui

    2016-04-01

    In order to perform gas exploration and determine the distribution pattern of gas in the Yanchang Oil Field in the eastern part of the North Shaanxi Slope, Ordos Basin, China, gravity and magnetic survey data were systemically collated, processed and interpreted in combination with the drilling data and recent seismic data. The genesis of gravity and magnetic anomalies and the relationship between the characteristics of the gravity and magnetic fields and known gas distribution were explored in order to predict the favourable exploration targets for gas. Gravity anomalies resulted both from the lateral variation in density of the basement rock and lateral lithologic transformation in the sedimentary cover. The regional magnetic anomalies were mainly caused by the basement metamorphic rocks and the residual magnetic anomalies may reflect the amount and general location of the volcanic materials in the overlying strata. The residual gravity and magnetic anomalies generated by high-density sandstone and high content of volcanics in the gas reservoir of the upper Paleozoic distorted and deformed the anomaly curves when they were stacked onto the primary background anomaly. The gas wells were generally found to be located in the anomaly gradient zones, or the distorted part of contour lines, and the flanks of high and low anomalies, or the transitional zones between anomaly highs and lows. The characteristics of gravity and magnetic fields provide significant information that can be used for guidance when exploring the distribution of gas. Based on these characteristics, five favourable areas for gas exploration were identified; these are quasi-equally spaced like a strip extending from the southeast to the northwest.

  16. The implementation of rare events logistic regression to predict the distribution of mesophotic hard corals across the main Hawaiian Islands.

    PubMed

    Veazey, Lindsay M; Franklin, Erik C; Kelley, Christopher; Rooney, John; Frazer, L Neil; Toonen, Robert J

    2016-01-01

    Predictive habitat suitability models are powerful tools for cost-effective, statistically robust assessment of the environmental drivers of species distributions. The aim of this study was to develop predictive habitat suitability models for two genera of scleractinian corals (Leptoserisand Montipora) found within the mesophotic zone across the main Hawaiian Islands. The mesophotic zone (30-180 m) is challenging to reach, and therefore historically understudied, because it falls between the maximum limit of SCUBA divers and the minimum typical working depth of submersible vehicles. Here, we implement a logistic regression with rare events corrections to account for the scarcity of presence observations within the dataset. These corrections reduced the coefficient error and improved overall prediction success (73.6% and 74.3%) for both original regression models. The final models included depth, rugosity, slope, mean current velocity, and wave height as the best environmental covariates for predicting the occurrence of the two genera in the mesophotic zone. Using an objectively selected theta ("presence") threshold, the predicted presence probability values (average of 0.051 for Leptoseris and 0.040 for Montipora) were translated to spatially-explicit habitat suitability maps of the main Hawaiian Islands at 25 m grid cell resolution. Our maps are the first of their kind to use extant presence and absence data to examine the habitat preferences of these two dominant mesophotic coral genera across Hawai'i. PMID:27441122

  17. The implementation of rare events logistic regression to predict the distribution of mesophotic hard corals across the main Hawaiian Islands

    PubMed Central

    Franklin, Erik C.; Kelley, Christopher; Frazer, L. Neil; Toonen, Robert J.

    2016-01-01

    Predictive habitat suitability models are powerful tools for cost-effective, statistically robust assessment of the environmental drivers of species distributions. The aim of this study was to develop predictive habitat suitability models for two genera of scleractinian corals (Leptoserisand Montipora) found within the mesophotic zone across the main Hawaiian Islands. The mesophotic zone (30–180 m) is challenging to reach, and therefore historically understudied, because it falls between the maximum limit of SCUBA divers and the minimum typical working depth of submersible vehicles. Here, we implement a logistic regression with rare events corrections to account for the scarcity of presence observations within the dataset. These corrections reduced the coefficient error and improved overall prediction success (73.6% and 74.3%) for both original regression models. The final models included depth, rugosity, slope, mean current velocity, and wave height as the best environmental covariates for predicting the occurrence of the two genera in the mesophotic zone. Using an objectively selected theta (“presence”) threshold, the predicted presence probability values (average of 0.051 for Leptoseris and 0.040 for Montipora) were translated to spatially-explicit habitat suitability maps of the main Hawaiian Islands at 25 m grid cell resolution. Our maps are the first of their kind to use extant presence and absence data to examine the habitat preferences of these two dominant mesophotic coral genera across Hawai‘i. PMID:27441122

  18. Optimal Capacity and Location Assessment of Natural Gas Fired Distributed Generation in Residential Areas

    NASA Astrophysics Data System (ADS)

    Khalil, Sarah My

    With ever increasing use of natural gas to generate electricity, installed natural gas fired microturbines are found in residential areas to generate electricity locally. This research work discusses a generalized methodology for assessing optimal capacity and locations for installing natural gas fired microturbines in a distribution residential network. The overall objective is to place microturbines to minimize the system power loss occurring in the electrical distribution network; in such a way that the electric feeder does not need any up-gradation. The IEEE 123 Node Test Feeder is selected as the test bed for validating the developed methodology. Three-phase unbalanced electric power flow is run in OpenDSS through COM server, and the gas distribution network is analyzed using GASWorkS. The continual sensitivity analysis methodology is developed to select multiple DG locations and annual simulation is run to minimize annual average losses. The proposed placement of microturbines must be feasible in the gas distribution network and should not result into gas pipeline reinforcement. The corresponding gas distribution network is developed in GASWorkS software, and nodal pressures of the gas system are checked for various cases to investigate if the existing gas distribution network can accommodate the penetration of selected microturbines. The results indicate the optimal locations suitable to place microturbines and capacity that can be accommodated by the system, based on the consideration of overall minimum annual average losses as well as the guarantee of nodal pressure provided by the gas distribution network. The proposed method is generalized and can be used for any IEEE test feeder or an actual residential distribution network.

  19. Tectonic Controls on Gas Hydrate Distribution off SW Taiwan

    NASA Astrophysics Data System (ADS)

    Berndt, C.; Chi, W. C.; Jegen, M. D.; Muff, S.; Hölz, S.; Lebas, E.; Sommer, M.; Lin, S.; Liu, C. S.; Lin, A. T.; Klaucke, I.; Klaeschen, D.; Chen, L.; Kunath, P.; McIntosh, K. D.; Feseker, T.

    2015-12-01

    The northern part of the South China Sea is characterized by wide-spread occurrence of bottom simulating reflectors (BSR), indicating the presence of marine gas hydrates. Because the area covers both the tectonically inactive passive margin and the northern termination of the Manila Trench subduction zone while sediment input is broadly similar, this area provides an excellent opportunity to study the influence of tectonic processes on the dynamics of gas hydrate systems. Long-offset multi-channel seismic data show that movement along thrust faults and blind thrust faults caused anticlinal ridges on the active margin, while faults are absent on the passive margin. This coincides with high-hydrate saturations derived from ocean bottom seismometer data and controlled source electromagnetic data, and conspicuous high-amplitude reflections in P-Cable 3D seismic data above the BSR in the anticlinal ridges of the active margin. On the contrary, all geophysical evidence for the passive margin points to normal- to low-hydrate saturations. Geochemical analysis of gas samples collected at seep sites on the active margin show methane with heavy δ13C isotope composition, while gas collected on the passive margin shows highly depleted (light) carbon isotope composition. Thus, we interpret the passive margin as a typical gas hydrate province fuelled by biogenic production of methane and the active margin gas hydrate system as a system that is fuelled not only by biogenic gas production but also by additional advection of thermogenic methane from the subduction system. The location of the highest gas hydrate saturations in the hanging wall next to the thrust faults suggests that the thrust faults represent pathways for the migration of methane. Our findings suggest that the most promising gas hydrate occurrences for exploitation of gas hydrate as an energy source may be found in the core of the active margin roll over anticlines immediately above the BSR and that high

  20. A SIMPLE PHYSICAL MODEL FOR THE GAS DISTRIBUTION IN GALAXY CLUSTERS

    SciTech Connect

    Patej, Anna; Loeb, Abraham

    2015-01-01

    The dominant baryonic component of galaxy clusters is hot gas whose distribution is commonly probed through X-ray emission arising from thermal bremsstrahlung. The density profile thus obtained has been traditionally modeled with a β-profile, a simple function with only three parameters. However, this model is known to be insufficient for characterizing the range of cluster gas distributions and attempts to rectify this shortcoming typically introduce additional parameters to increase the fitting flexibility. We use cosmological and physical considerations to obtain a family of profiles for the gas with fewer parameters than the β-model but which better accounts for observed gas profiles over wide radial intervals.

  1. Small turbines in distributed utility application: Natural gas pressure supply requirements

    SciTech Connect

    Goldstein, H.L.

    1996-05-01

    Implementing distributed utility can strengthen the local distribution system and help avoid or delay the expense of upgrading transformers and feeders. The gas turbine-generator set is an attractive option based on its low front-end capital cost, reliable performance at unmanned stations, and environmental performance characteristics. This report assesses gas turbine utilization issues from a perspective of fuel supply pressure requirements and discusses both cost and operational factors. A primary operational consideration for siting gas turbines on the electric distribution system is whether the local gas distribution company can supply gas at the required pressure. Currently available gas turbine engines require gas supply pressures of at least 150 pounds per square inch gauge, more typically, 250 to 350 psig. Few LDCs maintain line pressure in excess of 125 psig. One option for meeting the gas pressure requirements is to upgrade or extend an existing pipeline and connect that pipeline to a high-pressure supply source, such as an interstate transmission line. However, constructing new pipeline is expensive, and the small volume of gas required by the turbine for the application offers little incentive for the LDC to provide this service. Another way to meet gas pressure requirements is to boost the compression of the fuel gas at the gas turbine site. Fuel gas booster compressors are readily available as stand-alone units and can satisfactorily increase the supply pressure to meet the turbine engine requirement. However, the life-cycle costs of this equipment are not inconsequential, and maintenance and reliability issues for boosters in this application are questionable and require further study. These factors may make the gas turbine option a less attractive solution in DU applications than first indicated by just the $/kW capital cost. On the other hand, for some applications other DU technologies, such as photovoltaics, may be the more attractive option.

  2. Study and optimization of gas flow and temperature distribution in a Czochralski configuration

    NASA Astrophysics Data System (ADS)

    Fang, H. S.; Jin, Z. L.; Huang, X. M.

    2012-12-01

    The Czochralski (Cz) method has virtually dominated the entire production of bulk single crystals with high productivity. Since the Cz-grown crystals are cylindrical, axisymmetric hot zone arrangement is required for an ideally high-quality crystal growth. However, due to three-dimensional effects the flow pattern and temperature field are inevitably non-axisymmetric. The grown crystal suffers from many defects, among which macro-cracks and micro-dislocation are mainly related to inhomogeneous temperature distribution during the growth and cooling processes. The task of the paper is to investigate gas partition and temperature distribution in a Cz configuration, and to optimize the furnace design for the reduction of the three-dimensional effects. The general design is found to be unfavorable to obtain the desired temperature conditions. Several different types of the furnace designs, modified at the top part of the side insulation, are proposed for a comparative analysis. The optimized one is chosen for further study, and the results display the excellence of the proposed design in suppression of three-dimensional effects to achieve relatively axisymmetric flow pattern and temperature distribution for the possible minimization of thermal stress related crystal defects.

  3. The distribution of warm ionized gas in NGC 891

    SciTech Connect

    Rand, R.J.; Kulkarni, S.R.; Hester, J.J. Infrared Processing and Analysis Center, Pasadena, CA )

    1990-03-01

    Narrow-band imaging is presented of the edge-on spiral NGC 891 in the H-alpha and S II 6716, 6731 A forbidden lines. Emission from H II regions confined to the plane of the galaxy and from diffuse gas up to about 4 kpc off the plane is readily detected. The full radial extent of the diffuse emission in the plane is about 30 kpc. NGC 891 is found to have a surface density of diffuse ionized gas twice the Galactic value, a thicker ionized gas layer, and a larger surface density of ionized gas relative to neutral gas. These are interpreted as consequences of a relatively high level of star formation in this galaxy. Other star formation tracers indicate the same conclusion. Many vertical H-alpha filaments, or 'worms,' extending to over 2 kpc off the plane of the galaxy are seen. These worms are interpreted in terms of chimney models for the interstellar media of spirals. 19 refs.

  4. Local ISM 3D Distribution and Soft X-ray Background Inferences for Nearby Hot Gas

    NASA Technical Reports Server (NTRS)

    Puspitarini, L.; Lallement, R.; Snowden, Steven L.; Vergely, J.-L.; Snowden, S.

    2014-01-01

    Three-dimensional (3D) interstellar medium (ISM) maps can be used to locate not only interstellar (IS) clouds, but also IS bubbles between the clouds that are blown by stellar winds and supernovae, and are filled by hot gas. To demonstrate this, and to derive a clearer picture of the local ISM, we compare our recent 3D IS dust distribution maps to the ROSAT diffuse Xray background maps after removal of heliospheric emission. In the Galactic plane, there is a good correspondence between the locations and extents of the mapped nearby cavities and the soft (0.25 keV) background emission distribution, showing that most of these nearby cavities contribute to this soft X-ray emission. Assuming a constant dust to gas ratio and homogeneous 106 K hot gas filling the cavities, we modeled in a simple way the 0.25 keV surface brightness along the Galactic plane as seen from the Sun, taking into account the absorption by the mapped clouds. The data-model comparison favors the existence of hot gas in the solar neighborhood, the so-called Local Bubble (LB). The inferred mean pressure in the local cavities is found to be approx.9,400/cu cm K, in agreement with previous studies, providing a validation test for the method. On the other hand, the model overestimates the emission from the huge cavities located in the third quadrant. Using CaII absorption data, we show that the dust to CaII ratio is very small in those regions, implying the presence of a large quantity of lower temperature (non-X-ray emitting) ionized gas and as a consequence a reduction of the volume filled by hot gas, explaining at least part of the discrepancy. In the meridian plane, the two main brightness enhancements coincide well with the LB's most elongated parts and chimneys connecting the LB to the halo, but no particular nearby cavity is found towards the enhancement in the direction of the bright North Polar Spur (NPS) at high latitude. We searched in the 3D maps for the source regions of the higher energy

  5. A New 2D-Advection-Diffusion Model Simulating Trace Gas Distributions in the Lowermost Stratosphere

    NASA Astrophysics Data System (ADS)

    Hegglin, M. I.; Brunner, D.; Peter, T.; Wirth, V.; Fischer, H.; Hoor, P.

    2004-12-01

    Tracer distributions in the lowermost stratosphere are affected by both, transport (advective and non-advective) and in situ sources and sinks. They influence ozone photochemistry, radiative forcing, and heating budgets. In-situ measurements of long-lived species during eight measurement campaigns revealed relatively simple behavior of the tracers in the lowermost stratosphere when represented in an equivalent-latitude versus potential temperature framework. We here present a new 2D-advection-diffusion model that simulates the main transport pathways influencing the tracer distributions in the lowermost stratosphere. The model includes slow diabatic descent of aged stratospheric air and vertical and/or horizontal diffusion across the tropopause and within the lowermost stratosphere. The diffusion coefficients used in the model represent the combined effects of different processes with the potential of mixing tropospheric air into the lowermost stratosphere such as breaking Rossby and gravity waves, deep convection penetrating the tropopause, turbulent diffusion, radiatively driven upwelling etc. They were specified by matching model simulations to observed distributions of long-lived trace gases such as CO and N2O obtained during the project SPURT. The seasonally conducted campaigns allow us to study the seasonal dependency of the diffusion coefficients. Despite its simplicity the model yields a surprisingly good description of the small scale features of the measurements and in particular of the observed tracer gradients at the tropopause. The correlation coefficients between modeled and measured trace gas distributions were up to 0.95. Moreover, mixing across isentropes appears to be more important than mixing across surfaces of constant equivalent latitude (or PV). With the aid of the model, the distribution of the fraction of tropospheric air in the lowermost stratosphere can be determined.

  6. Gas distribution effects on waste properties: Viscosities of bubbly slurries

    SciTech Connect

    Gauglitz, P.A.; Shah, R.R.; Davis, R.L.

    1994-09-01

    The retention and episodic release of flammable gases are critical safety concerns for double-shell tanks that contain waste slurries. The rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles. The presence of gas bubbles is expected to affect the rheology of the sludge, but essentially no literature data are available to assess the effect of bubbles. Accordingly, the objectives of this study are to develop models for the effect of gas bubbles on the viscosity of a particulate slurry, develop an experimental method (capillary rheometer), collect data on the viscosity of a bubbly slurry, and develop a theoretical basis for interpreting the experimental data from the capillary rheometer.

  7. Just fracking: a distributive environmental justice analysis of unconventional gas development in Pennsylvania, USA

    NASA Astrophysics Data System (ADS)

    Clough, Emily; Bell, Derek

    2016-02-01

    This letter presents a distributive environmental justice analysis of unconventional gas development in the area of Pennsylvania lying over the Marcellus Shale, the largest shale gas formation in play in the United States. The extraction of shale gas using unconventional wells, which are hydraulically fractured (fracking), has increased dramatically since 2005. As the number of wells has grown, so have concerns about the potential public health effects on nearby communities. These concerns make shale gas development an environmental justice issue. This letter examines whether the hazards associated with proximity to wells and the economic benefits of shale gas production are fairly distributed. We distinguish two types of distributive environmental justice: traditional and benefit sharing. We ask the traditional question: are there a disproportionate number of minority or low-income residents in areas near to unconventional wells in Pennsylvania? However, we extend this analysis in two ways: we examine income distribution and level of education; and we compare before and after shale gas development. This contributes to discussions of benefit sharing by showing how the income distribution of the population has changed. We use a binary dasymetric technique to remap the data from the 2000 US Census and the 2009-2013 American Communities Survey and combine that data with a buffer containment analysis of unconventional wells to compare the characteristics of the population living nearer to unconventional wells with those further away before and after shale gas development. Our analysis indicates that there is no evidence of traditional distributive environmental injustice: there is not a disproportionate number of minority or low-income residents in areas near to unconventional wells. However, our analysis is consistent with the claim that there is benefit sharing distributive environmental injustice: the income distribution of the population nearer to shale gas wells

  8. Continuous distributions of specific ventilation recovered from inert gas washout

    NASA Technical Reports Server (NTRS)

    Lewis, S. M.; Evans, J. W.; Jalowayski, A. A.

    1978-01-01

    A new technique is described for recovering continuous distributions of ventilation as a function of tidal ventilation/volume ratio from the nitrogen washout. The analysis yields a continuous distribution of ventilation as a function of tidal ventilation/volume ratio represented as fractional ventilations of 50 compartments plus dead space. The procedure was verified by recovering known distributions from data to which noise had been added. Using an apparatus to control the subject's tidal volume and FRC, mixed expired N2 data gave the following results: (a) the distributions of young, normal subjects were narrow and unimodal; (b) those of subjects over age 40 were broader with more poorly ventilated units; (c) patients with pulmonary disease of all descriptions showed enlarged dead space; (d) patients with cystic fibrosis showed multimodal distributions with the bulk of the ventilation going to overventilated units; and (e) patients with obstructive lung disease fell into several classes, three of which are illustrated.

  9. Observed oil and gas field size distributions: a consequence of the discovery process and prices of oil and gas

    SciTech Connect

    Drew, L.J.; Attanasi, E.D.; Schuenemeyer, J.H.

    1988-11-01

    If observed oil and gas field size distributions are obtained by random samplings, the fitted distributions should approximate that of the parent population of oil and gas fields. However, empirical evidence strongly suggests that larger fields tend to be discovered earlier in the discovery process than they would be by random sampling. Economic factors also can limit the number of small fields that are developed and reported. This paper examines observed size distributions in state and federal waters of offshore Texas. Results of the analysis demonstrate how the shape of the observable size distributions change with significant hydrocarbon price changes. Comparison of state and federal observed size distributions in the offshore area shows how production cost differences also affect the shape of the observed size distribution. Methods for modifying the discovery rate estimation procedures when economic factors significantly affect the discovery sequence are presented. A primary conclusion of the analysis is that, because hydrocarbon price changes can significantly affect the observed discovery size distribution, one should not be confident about inferring the form and specific parameters of the parent field size distribution from the observed distributions.

  10. Observed oil and gas field size distributions: A consequence of the discovery process and prices of oil and gas

    USGS Publications Warehouse

    Drew, L.J.; Attanasi, E.D.; Schuenemeyer, J.H.

    1988-01-01

    If observed oil and gas field size distributions are obtained by random samplings, the fitted distributions should approximate that of the parent population of oil and gas fields. However, empirical evidence strongly suggests that larger fields tend to be discovered earlier in the discovery process than they would be by random sampling. Economic factors also can limit the number of small fields that are developed and reported. This paper examines observed size distributions in state and federal waters of offshore Texas. Results of the analysis demonstrate how the shape of the observable size distributions change with significant hydrocarbon price changes. Comparison of state and federal observed size distributions in the offshore area shows how production cost differences also affect the shape of the observed size distribution. Methods for modifying the discovery rate estimation procedures when economic factors significantly affect the discovery sequence are presented. A primary conclusion of the analysis is that, because hydrocarbon price changes can significantly affect the observed discovery size distribution, one should not be confident about inferring the form and specific parameters of the parent field size distribution from the observed distributions. ?? 1988 International Association for Mathematical Geology.

  11. Atomic Gas Distribution in HCG31 and HCG92

    NASA Astrophysics Data System (ADS)

    Borthakur, Sanchayeeta; Yun, M.; Verdes-Montenegro, L.; Heckman, T. M.; Zhu, G.

    2014-01-01

    We present Green Bank Telescope (GBT) 5x5 grid observations surrounding the actively star forming groups Hickson Compact Group, HCG 31 and HCG 92. We find that the total HI content of the groups are 2x10^10 and 2.5x10^10 solar masses respectively. The HI in HCG31 is mostly associated with the central region, however, there is a faint extension of the order of 10^9 solar masses of gas toward the southeast direction detected at the GBT pointing centered at a distance of 185 kpc from the group center. The velocity range of the HI is similar to the HI in the central pixel indicating its kinematic link to the gas in the center of the group. HCG 92 shows strong HI emission at a position of a pointing 4' offset from the center. The ``HI-wing" at velocities 6350-6500 km/s (Borthakur et al. 2010) were found to be confined to a few pointings adjacent to the peak suggesting that the wing as is localized and not extended. However, this must be gas stripped due to interactions and are dynamically connected to the Arc-N (Williams et al. 2002). We comment on the survival of the gas from the ionizing photons of the metagalactic ultraviolet background and those produced by the starburst. The implication of the existence of an HI rich environments surrounding the starbursts support the possibility of continued and future star formation in these groups.

  12. Painting a Picture of Gas Hydrate Distribution with Thermal Images

    SciTech Connect

    Weinberger, Jill L.; Brown, Kevin M.; Long, Philip E.

    2005-02-25

    Large uncertainties about the energy resource potential and role in global climate change of gas hydrates result from uncertainty about how much hydrate is contained in marine sediments. During Leg 204 of the Ocean Drilling Program (ODP) to the accretionary complex of the Cascadia subduction zone, the entire gas hydrate stability zone was sampled in contrasting geological settings defined by a 3D seismic survey. By integrating results from different methods, including several new techniques developed for Leg 204, we overcome the problem of spatial under-sampling inherent in robust methods traditionally used for estimating the hydrate content of cores and obtain a high-resolution, quantitative estimate of the total amount and spatial variability of gas hydrate in this structural system. We conclude that high gas hydrate content (30-40% of pore space of 20-26% of total volume) is restricted to the upper tens of meters below the seafloor near the summit of the structure, where vigorous fluid venting occurs.

  13. Determination of the polar and total surface energy distributions of particulates by inverse gas chromatography.

    PubMed

    Das, Shyamal C; Larson, Ian; Morton, David A V; Stewart, Peter J

    2011-01-18

    This Letter reports a technique of measuring polar surface energy distributions of lactose using inverse gas chromatography (IGC). The significance of this study is that the total surface energy distributions can now be characterized by combining the already known dispersive surface energy distribution with polar surface energy distribution determined in this study. The polar surface energy was calculated from the specific free energies for surface interactions with a monopolar basic probe, ethyl acetate, and a monopolar acidic probe, dichloromethane. PMID:21174410

  14. 78 FR 34703 - Pipeline Safety: Information Collection Activities, Revision to Gas Distribution Annual Report

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-10

    ... TRANSPORTATION Pipeline and Hazardous Materials Safety Administration Pipeline Safety: Information Collection Activities, Revision to Gas Distribution Annual Report AGENCY: Pipeline and Hazardous Materials Safety... the Paperwork Reduction Act of 1995, the Pipeline and Hazardous Materials Safety Administration...

  15. Comparing two micrometeorological techniques for estimating trace gas emissions from distributed sources

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measuring trace gas emission from distributed sources such as treatment lagoons, treatment wetlands, land spread of manure, and feedlots requires micrometeorological methods. In this study, we tested the accuracy of two relatively new micrometeorological techniques, vertical radial plume mapping (VR...

  16. Controls on the distribution of oil, gas, and gas-condensate pools in the Timan-Pechora basin

    SciTech Connect

    Bogatsky, V.; Pankratov, J. )

    1993-09-01

    The distribution of hydrocarbon pool in the Timan Pechora basin is controlled by various aspects of the geological structure and stratigraphy. Oil pools are confined to tectonically stable areas, and there are often stratigraphically trapped (Omra-Lizha saddle in the Izhma Pechora basin, Khoreyyer depression). Structures in more active tectonic areas (Pechora-Kolva aulacogen and Ukhta-Izhma swell) usually contain complex accumulations of oil, gas, and condensate. The mixed character of these pools proves their multistaged origin involving further gas charge during stages of increased subsidence in the kitchen areas and degassing of oil during later stages of uplift. However, active tectonics led not only to gas-cap development but also, in places, to complete loss of hydrocarbons at the surface. The Varandey Adzhva zone is an example, with its considerable volume of heavy and medium-heavy oils. In the Ural foredeep basins, older oil and gas accumulations at the outer edge and on transverse uplifts were enriched later by gas generated from deeply buried formation the axial part of the orogenic trough and its eastern border. Younger fold structures contain gas and gas-condensate pools charged by gas generated in both orogenic and preorogenic formations and by residual oils re-migrated from preorogenic accumulations that once existed in the pericratonic region.

  17. Edge seal for a porous gas distribution plate of a fuel cell

    DOEpatents

    Feigenbaum, Haim; Pudick, Sheldon; Singh, Rajindar

    1984-01-01

    In an improved seal for a gas distribution plate of a fuel cell, a groove is provided extending along an edge of the plate. A member of resinous material is arranged within the groove and a paste comprising an immobilized acid is arranged surrounding the member and substantially filling the groove. The seal, which is impervious to the gas being distributed, is resistant to deterioration by the electrolyte of the cell.

  18. Measurements of gas hydrate formation probability distributions on a quasi-free water droplet

    NASA Astrophysics Data System (ADS)

    Maeda, Nobuo

    2014-06-01

    A High Pressure Automated Lag Time Apparatus (HP-ALTA) can measure gas hydrate formation probability distributions from water in a glass sample cell. In an HP-ALTA gas hydrate formation originates near the edges of the sample cell and gas hydrate films subsequently grow across the water-guest gas interface. It would ideally be desirable to be able to measure gas hydrate formation probability distributions of a single water droplet or mist that is freely levitating in a guest gas, but this is technically challenging. The next best option is to let a water droplet sit on top of a denser, immiscible, inert, and wall-wetting hydrophobic liquid to avoid contact of a water droplet with the solid walls. Here we report the development of a second generation HP-ALTA which can measure gas hydrate formation probability distributions of a water droplet which sits on a perfluorocarbon oil in a container that is coated with 1H,1H,2H,2H-Perfluorodecyltriethoxysilane. It was found that the gas hydrate formation probability distributions of such a quasi-free water droplet were significantly lower than those of water in a glass sample cell.

  19. Measurements of gas hydrate formation probability distributions on a quasi-free water droplet.

    PubMed

    Maeda, Nobuo

    2014-06-01

    A High Pressure Automated Lag Time Apparatus (HP-ALTA) can measure gas hydrate formation probability distributions from water in a glass sample cell. In an HP-ALTA gas hydrate formation originates near the edges of the sample cell and gas hydrate films subsequently grow across the water-guest gas interface. It would ideally be desirable to be able to measure gas hydrate formation probability distributions of a single water droplet or mist that is freely levitating in a guest gas, but this is technically challenging. The next best option is to let a water droplet sit on top of a denser, immiscible, inert, and wall-wetting hydrophobic liquid to avoid contact of a water droplet with the solid walls. Here we report the development of a second generation HP-ALTA which can measure gas hydrate formation probability distributions of a water droplet which sits on a perfluorocarbon oil in a container that is coated with 1H,1H,2H,2H-Perfluorodecyltriethoxysilane. It was found that the gas hydrate formation probability distributions of such a quasi-free water droplet were significantly lower than those of water in a glass sample cell. PMID:24985860

  20. Impact of Higher Natural Gas Prices on Local Distribution Companies and Residential Customers

    EIA Publications

    2007-01-01

    This report examines some of the problems faced by natural gas consumers as a result of increasing heating bills in recent years and problems associated with larger amounts of uncollectible revenue and lower throughput for the local distribution companies (LDCs) supplying the natural gas.

  1. A numerical study of liquid film distribution in wet natural gas pipelines

    NASA Astrophysics Data System (ADS)

    Gao, X. Q.; Zhao, Y. L.; Xu, W. W.; Guan, X. R.; Wang, J. J.; Jin, Y. H.

    2016-05-01

    The software of FLUENT was used to simulate the gas-liquid turbulent flow in wet natural gas pipeline of the Puguang gas field. The RNG k- ɛ model was used to simulate the turbulent flow, the Mixture model was used to simulate gas-liquid mixed phase, and the Eulerian wall film model was used to simulate the formation and development of liquid film. The gas phase flow field characteristics, the distribution of the axial and circumferential film thickness, and the droplet distribution in the pipeline were studied when the gas Reynolds number is 7.72 × 106(10.8m/s). The results can be concluded as followed: Liquid film distributes unevenly along the circumferential direction and mostly distributes under the pipeline wall because of gravity. The impact of the dean vortex and centrifugal force in the straight section can also influence the liquid film distribution. The wall shear stress distributions in horizontal straight pipeline is concerned with liquid membrane volatility, and consistent with the film volatility period, the wall shear stress reached the maximum value in a certain position of wave front. The influence of the wall shear stress on the film fluctuation in inclined pipeline is weakened by gravity and other factors.

  2. Gas and particle size distributions of polychlorinated naphthalenes in the atmosphere of Beijing, China.

    PubMed

    Zhu, Qingqing; Zhang, Xian; Dong, Shujun; Gao, Lirong; Liu, Guorui; Zheng, Minghui

    2016-05-01

    Polychlorinated naphthalenes (PCNs) were listed as persistent organic pollutants in the Stockholm Convention in 2015. Despite numerous studies on PCNs, little is known about their occurrence in atmospheric particulate matter of different sizes. In this study, 49 PCN congeners were investigated for their concentrations and size-specific distributions in an urban atmosphere, and preliminary exposure assessments were conducted. Ambient air samples were collected using a high-volume cascade impactor for division into a gas fraction and four particle size fractions. Samples were collected from October 2013 to June 2014 at an urban site in Beijing, China. The concentration range for PCNs in the atmosphere (gas + particle fractions) was 6.77-25.90 pg/m(3) (average 16.28 pg/m(3)). The particle-bound concentration range was 0.17-2.78 pg/m(3) (average 1.73 pg/m(3)). Therefore, PCNs were mainly found in the gas phase. The concentrations of PCNs in a fraction increased as the particle size decreased (dae > 10 μm, 10 μm ≥ dae > 2.5 μm, 2.5 μm ≥ dae > 1.0 μm and dae ≤ 1.0 μm). Consequently, PCNs were ubiquitous in inhalable fine particles, and the ΣPCNs associated with PM1.0 and PM2.5 reached 68.4% and 84.3%, respectively. Tetra-CNs and penta-CNs (the lower chlorinated homologues) predominated in the atmosphere. The homologue profiles in different size particles were almost similar, but the particulate profiles were different from those in the gas phase. Among the individual PCNs identified, CN38/40, CN52/60 and CN75 were the dominant compounds in the atmosphere. CN66/67 and CN73 collectively accounted for most of the total dioxin-like TEQ concentrations of the PCNs. Exposure to toxic compounds, such as PCNs present in PM1.0 or PM2.5, may affect human health. This work presents the first data on size-specific distributions of PCNs in the atmosphere. PMID:26840526

  3. Spatial distribution of interstellar dust in the Sun's vicinity. Comparison with neutral sodium-bearing gas

    NASA Astrophysics Data System (ADS)

    Vergely, J.-L.; Valette, B.; Lallement, R.; Raimond, S.

    2010-07-01

    Aims: 3D tomography of the interstellar dust and gas may be useful in many respects, from the physical and chemical evolution of the interstellar medium itself to foreground decontamination of the cosmic microwave background, or various studies of the environments of specific objects. However, while spectral data cubes of the galactic emission become increasingly precise, the information on the distance to the emitting regions has not progressed as well and relies essentially on the galactic rotation curve. Our goal here is to bring more precise information on the distance to nearby interstellar dust and gas clouds within 250 pc. Methods: We apply the best available calibration methods to a carefully screened set of stellar Strömgren photometry data for targets possessing a Hipparcos parallax and spectral type classification. We combine the derived interstellar extinctions and the parallax distances for about 6000 stars to build a 3D tomography of the local dust. We use an inversion method based on a regularized Bayesian approach and a least squares criterion, optimized for this specific data set. We apply the same inversion technique to a totally independent set of neutral sodium absorption data available for about 1700 target stars. Results: We obtain 3D maps of the opacity and the distance to the main dust-bearing clouds within 250 pc and identify in those maps well-known dark clouds and high galactic more diffuse entities. We calculate the integrated extinction between the Sun and the cube boundary and compare this with the total galactic extinction derived from infrared 2D maps. The two quantities reach similar values at high latitudes, as expected if the local dust content is satisfyingly reproduced and the dust is closer than 250 pc. Those maps show a larger high latitude dust opacity in the North compared to the South, reinforcing earlier evidences. Interestingly the gas maps do not show the same asymmetry, suggesting a polar asymmetry of the dust to gas

  4. Distributed Control Architecture for Gas Turbine Engine. Chapter 4

    NASA Technical Reports Server (NTRS)

    Culley, Dennis; Garg, Sanjay

    2009-01-01

    The transformation of engine control systems from centralized to distributed architecture is both necessary and enabling for future aeropropulsion applications. The continued growth of adaptive control applications and the trend to smaller, light weight cores is a counter influence on the weight and volume of control system hardware. A distributed engine control system using high temperature electronics and open systems communications will reverse the growing trend of control system weight ratio to total engine weight and also be a major factor in decreasing overall cost of ownership for aeropropulsion systems. The implementation of distributed engine control is not without significant challenges. There are the needs for high temperature electronics, development of simple, robust communications, and power supply for the on-board electronics.

  5. Importance of Pore Size Distribution of Fine-grained Sediments on Gas Hydrate Equilibrium

    NASA Astrophysics Data System (ADS)

    Kwon, T. H.; Kim, H. S.; Cho, G. C.; Park, T. H.

    2015-12-01

    Gas hydrates have been considered as a new source of natural gases. For the gas hydrate production, the gas hydrate reservoir should be depressurized below the equilibrium pressure of gas hydrates. Therefore, it is important to predict the equilibrium of gas hydrates in the reservoir conditions because it can be affected by the pore size of the host sediments due to the capillary effect. In this study, gas hydrates were synthesized in fine-grained sediment samples including a pure silt sample and a natural clayey silt sample cored from a hydrate occurrence region in Ulleung Basin, East Sea, offshore Korea. Pore size distributions of the samples were obtained by the nitrogen adsorption and desorption test and the mercury intrusion porosimetry. The equilibrium curve of gas hydrates in the fine-grained sediments were found to be significantly influenced by the clay fraction and the corresponding small pores (>50 nm in diameter). For the clayey silt sample, the equilibrium pressure was higher by ~1.4 MPa than the bulk equilibrium pressure. In most cases of oceanic gas hydrate reservoirs, sandy layers are found interbedded with fine-grained sediment layers while gas hydrates are intensively accumulated in the sandy layers. Our experiment results reveal the inhibition effect of fine-grained sediments against gas hydrate formation, in which greater driving forces (e.g., higher pressure or lower temperature) are required during natural gas migration. Therefore, gas hydrate distribution in interbedded layers of sandy and fine-grained sediments can be explained by such capillary effect induced by the pore size distribution of host sediments.

  6. Phthalate esters in main source water and drinking water of Zhejiang Province (China): Distribution and health risks.

    PubMed

    Wang, Xiaofeng; Lou, Xiaoming; Zhang, Nianhua; Ding, Gangqiang; Chen, Zhijian; Xu, Peiwei; Wu, Lizhi; Cai, Jianmin; Han, Jianlong; Qiu, Xueting

    2015-10-01

    To evaluate the distributions and health risks of phthalate esters in the main source water and corresponding drinking water of Zhejiang Province, the concentrations of 16 phthalate esters in water samples from 19 sites were measured from samples taken in the dry season and wet season. The concentration of the total phthalate ester congeners in source water ranged from 1.07 μg/L to 7.12 μg/L in the wet season, from 0.01 μg/L to 1.58 μg/L in the dry season, from 1.18 μg/L to 15.28 μg/L from drinking water in the wet season, and from 0.16 μg/L to 1.86 μg/L from drinking water in the dry season. Of the 16 phthalate esters, dimethyl phthalate, dibutyl phthalate, di-(2-ethyl-hexyl) phthalate, di-iso-butyl phthalate, bis-2-n-butoxyethyl phthalate, and dicyclohexyl phthalate were present in the samples analyzed, dominated by di-iso-butyl phthalate and di-(2-ethyl-hexyl) phthalate. The concentrations of phthalate esters in the wet season were all relatively higher than those in the dry season, and the drinking water had higher concentrations of phthalate esters than source water. The phthalate ester congeners studied pose little health risk to nearby citizens. Environ Toxicol Chem 2015;34:2205-2212. © 2015 SETAC. PMID:25988232

  7. Effects of carrier gas dynamics on single wall carbon nanotube chiral distributions during laser vaporization synthesis.

    PubMed

    Landi, Brian J; Raffaelle, Ryne P

    2007-03-01

    We report on the utility of modifying the carrier gas dynamics during laser vaporization synthesis to alter the single wall carbon nanotube (SWNT) chiral distribution. SWNTs produced from an Alexandrite laser using conventional Ni/Co catalysts demonstrate marked differences in chiral distributions due to effects of helium gas and reactor chamber pressure, in comparison to conventional subambient pressures and argon gas. Optical absorption and Raman spectroscopies confirm that the SWNT diameter distribution decreases under higher pressure and with helium gas as opposed to argon. Fluorescence mapping of the raw soots in sodium dodecylbenzene sulfonate (SDBS)-D2O was used to estimate the relative (n, m)-SWNT content of the semiconducting types. A predominance of type II structures for each synthesis condition was observed. The distribution of SWNT chiral angles was observed to shift away from near-armchair configurations under higher pressure and with helium gas. These results illustrate the importance of gas type and pressure on the condensation/cooling rate, which allows for synthesis of specific SWNT chiral distributions. PMID:17450850

  8. Density probability distribution functions of diffuse gas in the Milky Way

    NASA Astrophysics Data System (ADS)

    Berkhuijsen, E. M.; Fletcher, A.

    2008-10-01

    In a search for the signature of turbulence in the diffuse interstellar medium (ISM) in gas density distributions, we determined the probability distribution functions (PDFs) of the average volume densities of the diffuse gas. The densities were derived from dispersion measures and HI column densities towards pulsars and stars at known distances. The PDFs of the average densities of the diffuse ionized gas (DIG) and the diffuse atomic gas are close to lognormal, especially when lines of sight at |b| < 5° and |b| >= 5° are considered separately. The PDF of at high |b| is twice as wide as that at low |b|. The width of the PDF of the DIG is about 30 per cent smaller than that of the warm HI at the same latitudes. The results reported here provide strong support for the existence of a lognormal density PDF in the diffuse ISM, consistent with a turbulent origin of density structure in the diffuse gas.

  9. Airflow, gas deposition, and lesion distribution in the nasal passages

    SciTech Connect

    Morgan, K.T.; Monticello, T.M. )

    1990-04-01

    The nasal passages of laboratory animals and man are complex, and lesions induced in the delicate nasal lining by inhaled air pollutants vary considerably in location and nature. The distribution of nasal lesions is generally a consequence of regional deposition of the inhaled material, local tissue susceptibility, or a combination of these factors. Nasal uptake and regional deposition are are influenced by numerous factors including the physical and chemical properties of the inhaled material, such as water solubility and reactivity; airborne concentration and length of exposure; the presence of other air contaminants such as particulate matter; nasal metabolism, and blood and mucus flow. For certain highly water-soluble or reactive gases, nasal airflow patterns play a major role in determining lesion distribution. Studies of nasal airflow in rats and monkeys, using casting and molding techniques combined with a water-dye model, indicate that nasal airflow patterns are responsible for characteristic differences in the distribution of nasal lesions induced by formaldehyde in these species. Local tissue susceptibility is also a complex issue that may be a consequence of many factors, including physiologic and metabolic characteristics of the diverse cell populations that comprise each of the major epithelial types lining the airways. Identification of the principal factors that influence the distribution and nature of nasal lesions is important when attempting the difficult process of determining potential human risks using data derived from laboratory animals. Toxicologic pathologists can contribute to this process by carefully identifying the site and nature of nasal lesions induced by inhaled materials. 61 references.

  10. Spatial distribution of venous gas emboli in the lungs.

    PubMed

    Souders, J E; Doshier, J B; Polissar, N L; Hlastala, M P

    1999-11-01

    The distribution of gaseous pulmonary emboli is presumed to be determined by their buoyancy. We hypothesized that regional pulmonary blood flow may also influence their distribution. Therefore, pulmonary blood flow was measured in supine, anesthetized dogs with use of 15-microm fluorescent microspheres at baseline and during N(2) embolism. The animals were killed, and the lungs were excised, air-dried, and diced into approximately 2-cm(3) pieces with weights and spatial coordinates recorded. Embolism was defined as a >10% flow decrease relative to baseline. Vertically, the incidence of embolism increased substantially by 6 +/- 1% per additional centimeter in height compared with baseline (P = 0.0003). Embolism also increased radially by 3 +/- 1%/cm from the hilum (P = 0.002). There was a weaker but statistically significant increase in embolism to pieces with greater baseline flow, 9 +/- 2% for every 1. 0 increase in relative baseline flow (P = 0.008). We conclude that the distribution of gaseous emboli is influenced by buoyancy and flow dynamics within the pulmonary vasculature. PMID:10562640

  11. Spatial distribution of venous gas emboli in the lungs

    NASA Technical Reports Server (NTRS)

    Souders, J. E.; Doshier, J. B.; Polissar, N. L.; Hlastala, M. P.

    1999-01-01

    The distribution of gaseous pulmonary emboli is presumed to be determined by their buoyancy. We hypothesized that regional pulmonary blood flow may also influence their distribution. Therefore, pulmonary blood flow was measured in supine, anesthetized dogs with use of 15-microm fluorescent microspheres at baseline and during N(2) embolism. The animals were killed, and the lungs were excised, air-dried, and diced into approximately 2-cm(3) pieces with weights and spatial coordinates recorded. Embolism was defined as a >10% flow decrease relative to baseline. Vertically, the incidence of embolism increased substantially by 6 +/- 1% per additional centimeter in height compared with baseline (P = 0.0003). Embolism also increased radially by 3 +/- 1%/cm from the hilum (P = 0.002). There was a weaker but statistically significant increase in embolism to pieces with greater baseline flow, 9 +/- 2% for every 1. 0 increase in relative baseline flow (P = 0.008). We conclude that the distribution of gaseous emboli is influenced by buoyancy and flow dynamics within the pulmonary vasculature.

  12. Spatially and temporally resolved gas distributions around heterogeneous catalysts using infrared planar laser-induced fluorescence

    PubMed Central

    Zetterberg, Johan; Blomberg, Sara; Gustafson, Johan; Evertsson, Jonas; Zhou, Jianfeng; Adams, Emma C.; Carlsson, Per-Anders; Aldén, Marcus; Lundgren, Edvin

    2015-01-01

    Visualizing and measuring the gas distribution in close proximity to a working catalyst is crucial for understanding how the catalytic activity depends on the structure of the catalyst. However, existing methods are not able to fully determine the gas distribution during a catalytic process. Here we report on how the distribution of a gas during a catalytic reaction can be imaged in situ with high spatial (400 μm) and temporal (15 μs) resolution using infrared planar laser-induced fluorescence. The technique is demonstrated by monitoring, in real-time, the distribution of carbon dioxide during catalytic oxidation of carbon monoxide above powder catalysts. Furthermore, we demonstrate the versatility and potential of the technique in catalysis research by providing a proof-of-principle demonstration of how the activity of several catalysts can be measured simultaneously, either in the same reactor chamber, or in parallel, in different reactor tubes. PMID:25953006

  13. Distribution of a nonstationary electron beam in a dense gas

    SciTech Connect

    Sklyarov, Y.M.; Shelepin, L.A.; Syts'ko, Y.L.

    1986-11-01

    The problem of the temporal and spatial dependences of the parameters of the action of a modulated fast-electron beam on a dense gas is posed on the basis of the transport equation. The problem is simplified by making it nondimensional and by transforming to the Fokker-Planck approximation. A Green's function formalism is developed for this problem and is used to express the solution of the general nonstationary problem in the form of a convolution of a nonstationary boundary flow with a stationary Green's function. The use of the derived equation is illustrated using as an example the solution of a problem with the simplest stationary Green's function corresponding to the ''straight-ahead'' approximation. This approximation is used to consider a general relativistic case with model scattering cross sections. The methods and results of a numerical computer solution of the nonstationary problem of electron retardation in the upper layer of the atmosphere are surveyed.

  14. STAR FORMATION AND DISTRIBUTIONS OF GAS AND DUST IN THE CIRCINUS CLOUD

    SciTech Connect

    Shimoikura, Tomomi; Dobashi, Kazuhito

    2011-04-10

    We present results of a study on the Circinus cloud based on {sup 13}CO (J = 1 - 0) data as well as visual to near-infrared (JHK{sub S}) extinction maps, to investigate the distributions of gas and dust around the cloud. The global {sup 13}CO distribution of the Circinus cloud is revealed for the first time, and the total molecular mass of the cloud is estimated to be 2.5 x 10{sup 4} M{sub sun} for the assumed distance 700 pc. Two massive clumps in the cloud, called Circinus-W and Circinus-E, have a mass of {approx}5 x 10{sup 3} M{sub sun}. These clumps are associated with a number of young stellar objects (YSOs) searched for in the literature, indicating that they are the most active star-forming sites in Circinus. All of the extinction maps show good agreement with the {sup 13}CO distribution. We derived the average N({sup 13}CO)/A{sub V} ratio in the Circinus cloud to be 1.25 x 10{sup 15} cm{sup -2} mag{sup -1} by comparing the extinction maps with the {sup 13}CO data. The extinction maps also allowed us to probe into the reddening law over the Circinus cloud. We found that there is a clear change in dust properties in the densest regions of Circinus-W and Circinus-E, possibly due to grain growth in the dense cloud interior. Among the YSOs found in the literature, we attempted to infer the ages and masses of the H{alpha} emission-line stars forming in the two clumps, and found that they are likely to be younger than 1 Myr, having a relatively small mass of {approx}<2 M{sub sun} at the zero-age main sequence.

  15. Pressure and flow distribution in internal gas manifolds of a fuel-cell stack

    NASA Astrophysics Data System (ADS)

    Koh, Joon-Ho; Seo, Hai-Kyung; Lee, Choong Gon; Yoo, Young-Sung; Lim, Hee Chun

    Gas-flow dynamics in internal gas manifolds of a fuel-cell stack are analyzed to investigate overall pressure variation and flow distribution. Different gas-flow patterns are considered in this analysis. Gas-flow through gas channels of each cell is modeled by means of Darcy's law where permeability should be determined on an experimental basis. Gas-flow in manifolds is modeled from the macroscopic mechanical energy balance with pressure-loss by wall friction and geometrical effects. A systematic algorithm to solve the proposed flow model is suggested to calculate pressure and flow distribution in fuel-cell stacks. Calculation is done for a 100-cell molten carbonate fuel-cell stack with internal manifolds. The results show that the pressure-loss by wall friction is negligible compared with the pressure recovery in inlet manifolds or loss in outlet manifolds due to mass dividing or combining flow at manifold-cell junctions. A more significant effect on manifold pressure possibly arises from the geometrical manifold structure which depends on the manifold size and shape. The geometrical effect is approximated from pressure-loss coefficients of several types of fittings and valves. The overall pressure and flow distribution is significantly affected by the value of the geometrical pressure-loss coefficient. It is also found that the flow in manifolds is mostly turbulent in the 100-cell stack and this way result in an uneven flow distribution when the stack manifold is incorrectly, designed.

  16. Spatial-temporal distribution of the ionospheric perturbations prior to Ms≥6.0 earthquakes in China main land

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Wan, Weixing; Shen, Xuhui; Zhang, Xuemin

    2015-04-01

    Recently, earthquake precursor in the ionosphere is becoming one of the most challenging issues both in earthquake science and ionospheric science field. Based on the analysis of ionospheric data before strong EQs, some perturbations have been found in D, E, F layers respectively over the epicentral areas, including case and statistics studies. For the earthquake monitoring and prediction, we need to understand the evolutional features both in temporal series and spatial distribution in order to build their relationship with earthquakes. In this study, using GPS TEC data (from Jet Populsion Laboratry), we have statistically analyzed the ionospheric perturbations prior to the Ms≥6.0 earthquakes in China main land from November 1st, 1998 to December 31st, 2010. For each earthquake, LB=M-1.5(M-LQ) and UB=M+1.5(UQ-M) were selected as the threshold to abstract the disturbance from 0 to 15 days around the epicenter, and then we summed all the earthquakes results. The obtained results indicated that the GPS TEC had the same variation trend above the epicenter and eastern, southern, western, northern directions 15 days before earthquakes, and decrease occurred in all the 5 directions from 3 days to 5 days. Through different space scale analysis of ±10°, ±20°, ±30°, it was found that the maximum seismo-ionospheric disturbance didn't appear just above the epicenter, but shifted to the magnetic equator, and it was worth to point out that the effected region in ionosphere was about ±15°. Besides this, prior to earthquakes, positive anomalies appeared in the southwestern direction before 14th, 10th days, and there were obviously negative anomalies in the southeastern direction before 5th day. At last, a hypothesis of electrostatic field channel in lithosphere-atmosphere-ionosphere coupling was used to explain the observed phenomena. If there is penetration or secondary electric field in the ionosphere, it will move upward along the magnetic lines, causing E×B motion

  17. Natural Gas Transmission and Distribution Model of the National Energy Modeling System. Volume 1

    SciTech Connect

    1998-01-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. The NGTDM is the model within the NEMS that represents the transmission, distribution, and pricing of natural gas. The model also includes representations of the end-use demand for natural gas, the production of domestic natural gas, and the availability of natural gas traded on the international market based on information received from other NEMS models. The NGTDM determines the flow of natural gas in an aggregate, domestic pipeline network, connecting domestic and foreign supply regions with 12 demand regions. The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic design, provides detail on the methodology employed, and describes the model inputs, outputs, and key assumptions. Subsequent chapters of this report provide: an overview of NGTDM; a description of the interface between the NEMS and NGTDM; an overview of the solution methodology of the NGTDM; the solution methodology for the Annual Flow Module; the solution methodology for the Distributor Tariff Module; the solution methodology for the Capacity Expansion Module; the solution methodology for the Pipeline Tariff Module; and a description of model assumptions, inputs, and outputs.

  18. A Lagrangian View of Stratospheric Trace Gas Distributions

    NASA Technical Reports Server (NTRS)

    Schoeberl, M. R.; Sparling, L.; Dessler, A.; Jackman, C. H.; Fleming, E. L.

    1998-01-01

    As a result of photochemistry, some relationship between the stratospheric age-of-air and the amount of tracer contained within an air sample is expected. The existence of such a relationship allows inferences about transport history to be made from observations of chemical tracers. This paper lays down the conceptual foundations for the relationship between age and tracer amount, developed within a Lagrangian framework. In general, the photochemical loss depends not only on the age of the parcel but also on its path. We show that under the "average path approximation" that the path variations are less important than parcel age. The average path approximation then allows us to develop a formal relationship between the age spectrum and the tracer spectrum. Using the relation between the tracer and age spectra, tracer-tracer correlations can be interpreted as resulting from mixing which connects parts of the single path photochemistry curve, which is formed purely from the action of photochemistry on an irreducible parcel. This geometric interpretation of mixing gives rise to constraints on trace gas correlations, and explains why some observations are do not fall on rapid mixing curves. This effect is seen in the ATMOS observations.

  19. Gas distribution industry survey: Costs of installation, maintenance and repair, and operations, version 1. Topical report, December 1993-March 1995

    SciTech Connect

    Biederman, N.

    1996-05-01

    The U.S. natural gas distribution industry spends $40 - $45 billion each year to buy gas and deliver it to the customers and to expand and renew the distribution piping system. More than half of these expenditures are paid to suppliers and transporters of gas. The way in which the balance (nearly $18 billion) is spent is controlled by the local gas distribution companies. This research is aimed to provide a better understanding of how and why these costs are incurred. It is based on interviews with 24 gas distribution companies and the data collected on a wide variety of maintenance, installation, and operations activities.

  20. PHIBSS: MOLECULAR GAS CONTENT AND SCALING RELATIONS IN z {approx} 1-3 MASSIVE, MAIN-SEQUENCE STAR-FORMING GALAXIES

    SciTech Connect

    Tacconi, L. J.; Genzel, R.; Wuyts, S.; Foerster Schreiber, N. M.; Gracia-Carpio, J.; Lutz, D.; Saintonge, A.; Neri, R.; Cox, P.; Combes, F.; Bolatto, A.; Cooper, M. C.; Bournaud, F.; Comerford, J.; Davis, M.; Newman, S.; Garcia-Burillo, S.; Naab, T.; Omont, A. E-mail: genzel@mpe.mpg.de; and others

    2013-05-01

    We present PHIBSS, the IRAM Plateau de Bure high-z blue sequence CO 3-2 survey of the molecular gas properties in massive, main-sequence star-forming galaxies (SFGs) near the cosmic star formation peak. PHIBSS provides 52 CO detections in two redshift slices at z {approx} 1.2 and 2.2, with log(M{sub *}(M{sub Sun })) {>=} 10.4 and log(SFR(M{sub Sun }/yr)) {>=} 1.5. Including a correction for the incomplete coverage of the M{sub *} -SFR plane, and adopting a ''Galactic'' value for the CO-H{sub 2} conversion factor, we infer average gas fractions of {approx}0.33 at z {approx} 1.2 and {approx}0.47 at z {approx} 2.2. Gas fractions drop with stellar mass, in agreement with cosmological simulations including strong star formation feedback. Most of the z {approx} 1-3 SFGs are rotationally supported turbulent disks. The sizes of CO and UV/optical emission are comparable. The molecular-gas-star-formation relation for the z = 1-3 SFGs is near-linear, with a {approx}0.7 Gyr gas depletion timescale; changes in depletion time are only a secondary effect. Since this timescale is much less than the Hubble time in all SFGs between z {approx} 0 and 2, fresh gas must be supplied with a fairly high duty cycle over several billion years. At given z and M{sub *}, gas fractions correlate strongly with the specific star formation rate (sSFR). The variation of sSFR between z {approx} 0 and 3 is mainly controlled by the fraction of baryonic mass that resides in cold gas.

  1. Distributive and Quantitative Analysis of the Main Active Saponins in Panax notoginseng by UHPLC-QTOF/MS Combining with Fluorescence Microscopy and Laser Microdissection.

    PubMed

    Chen, Quanlan; Liang, Zhitao; Brand, Eric; Chen, Hubiao; Zhao, Zhongzhen

    2016-02-01

    The distribution of the secondary metabolites in different tissues of Panax notoginseng has not yet been investigated. Furthermore, there is no scientific evidence available for the quality assessment of P. notoginseng. This is the first study on the tissue-specific chemicals to identify and determinate the main secondary metabolite profiling of P. notoginseng in order to provide more information for quality evaluation. In this study, the ultrahigh-performance liquid chromatography quadrupole time-of-flight mass spectrometry approach combined with fluorescence microscopy and laser microdissection was developed and validated for distributive and quantitative analyses of the main active saponins of different tissues from P. notoginseng. The results showed that the total content of notoginsenoside R1, ginsenoside Rg1, ginsenoside Rb1, and ginsenoside Rd in the xylem were higher than those in the cork, phloem, and cortex. There was no significant difference in the distribution of saponins between the main roots and the branch roots of the fresh unprocessed materials, nor was there a significant difference in their distribution between the main roots from the fresh unprocessed vs. the dried processed commercial materials. This method illustrated the distribution pattern of the main saponins in the tissues of P. notoginseng, which could help to explain the relationship between its anatomical structures, morphological characteristics, and quality. In summary, this study has significance for the procurement, collection, cultivation, effective management, and quality control of P. notoginseng. PMID:26824619

  2. Gas swelling and deuterium distribution in beryllium implanted with deuterium ions

    SciTech Connect

    Chernikov, V.N.; Alimov, V.Kh.; Zakharov, A.P.

    1995-09-01

    An extensive TEM study of the microstructure of Be TIP-30 irradiated with 3 and 10 keV D ions up to fluences, {Phi}, in the range from 3 x 10{sup 20} to 8 x 10{sup 21} D/m{sup 2} at temperatures T{sub irr} = 300 K, 500 K and 700 K has been carried out. Depth distributions of deuterium in the form of separate D atoms and D{sub 2} molecules have been investigated by means of SIMS and RGA methods, correspondingly. D ion irradiation is accompanied by blistering and gives rise to different kind of destructions depending mainly on the irradiation temperature. Irradiation with D ions at 300 K leads to the formation of tiny highly pressurized D{sub 2} bubbles reminiscent of He bubbles in Be. Under 3 keV D ion irradiation D{sub 2} bubbles ({bar r}{sub b} {approx} 0.7 nm) appear at a fluence as low as 3x10{sup 20} D/m{sup 2}. Irradiation at 500 K results in the development, along with relatively small facetted bubbles, of larger oblate gas-filled cavities accumulating most of injected D atoms and providing for much higher gas swelling values as compared to irradiation at 300 K. The increase of D and/or T{sub irr}, to 700 K causes the further coarsening of large cavities which are transformed into sub-surface labyrinth structures. D and He ion implantation leads to the enhanced growth of porous microcrystalline layers of c.p.h.-BeO oxide with a microstructure which differs considerably from that of oxide layers on electropolished surfaces of Be. Based on the analysis of experimental data questions of deuterium reemission, thermal desorption and trapping in Be have been discussed in detail.

  3. A global survey of the distribution of free gas in marine sediments

    NASA Astrophysics Data System (ADS)

    Fleischer, Peter; Orsi, Tim; Richardson, Michael

    2003-10-01

    Following the work of Aubrey Anderson in the Gulf of Mexico, we have attempted to quantify the global distribution of free gas in shallow marine sediments, and have identified and indexed over one hundred documented cases in the scientific and engineering literature. Our survey confirms previous assumptions, primarily that gas bubbles are ubiquitous in the organic-rich muds of coastal waters and shallow adjacent seas. Acoustic turbidity as recorded during seismo-acoustic surveys is the most frequently cited evidence used to infer the presence of seafloor gas. Biogenic methane predominates within these shallow subbottom deposits. The survey also reveals significant imbalances in the geographic distribution of studies, which might be addressed in the future by accessing proprietary data or local studies with limited distribution. Because of their global prevalence, growing interest in gassy marine sediments is understandable as their presence has profound scientific, engineering and environmental implications.

  4. Minimization of Blast furnace Fuel Rate by Optimizing Burden and Gas Distribution

    SciTech Connect

    Dr. Chenn Zhou

    2012-08-15

    The goal of the research is to improve the competitive edge of steel mills by using the advanced CFD technology to optimize the gas and burden distributions inside a blast furnace for achieving the best gas utilization. A state-of-the-art 3-D CFD model has been developed for simulating the gas distribution inside a blast furnace at given burden conditions, burden distribution and blast parameters. The comprehensive 3-D CFD model has been validated by plant measurement data from an actual blast furnace. Validation of the sub-models is also achieved. The user friendly software package named Blast Furnace Shaft Simulator (BFSS) has been developed to simulate the blast furnace shaft process. The research has significant benefits to the steel industry with high productivity, low energy consumption, and improved environment.

  5. The gas distribution of comet Halley and its relation to the nucleus rotation

    NASA Technical Reports Server (NTRS)

    Cochran, Anita L.; Trout, Anthony P.

    1994-01-01

    We used a set of spatially resolved spectra of comet Halley to explore whether the gas distribution profile could be inverted to yield information on the rotation of the comet. The data were obtained both pre- and post-perihelion. The pre-perihelion data showed reasonable symmetry and so were used to define the lifetimes against photodissociation of the various molecules. These lifetimes were then used to define the lifetimes against photodissociation of the various molecules. These lifetimes were then used along with a nonsteady-state vectorial model to fit the post-perihelion gas distribution profiles. The resulting molecular lightcurves are compared with the photometric lightcurves of Schlicher et al. (1990) to show that the rotational information is encoded in the observed gas distribution within the coma. The molecular lightcurves can differentiate between the preferred Schlicher et al. average period and the period they find for the same time interval as the spectra.

  6. Effects of strong magnetic fields on the electron distribution and magnetisability of rare gas atoms

    NASA Astrophysics Data System (ADS)

    Pagola, G. I.; Caputo, M. C.; Ferraro, M. B.; Lazzeretti, P.

    2004-12-01

    Strong uniform static magnetic fields compress the electronic distribution of rare gas atoms and cause a 'spindle effect', which can be illustrated by plotting charge-density functions which depend quadratically on the flux density of the applied field. The fourth rank hypermagnetisabilities of He, Ne, Ar and Kr are predicted to have small positive values. Accordingly, the diamagnetism of rare gas atoms diminishes by a very little amount in the presence of intense magnetic field.

  7. Numerical Analysis on Effect of Areal Gas Distribution Pipe on Characteristics Inside COREX Shaft Furnace

    NASA Astrophysics Data System (ADS)

    Wu, Shengli; Du, Kaiping; Xu, Jian; Shen, Wei; Kou, Mingyin; Zhang, Zhekai

    2014-07-01

    In recent years, two parallel pipes of areal gas distribution (AGD) were installed into the COREX shaft furnace to improve the furnace efficiency. A three-dimensional mathematical model at steady state, which takes a modified three-interface unreacted core model into consideration, is developed in the current work to describe the effect of the AGD pipe on the inner characteristics of shaft furnace. The accuracy of the model is evaluated using the plant operational data. The AGD pipe effectively improves the uniformity of reducing gas distribution, which leads to an increase in gas temperature and concentration of CO or H2 around the AGD pipe, and hence it further contributes to the iron oxide reduction. As a result, the top gas utilization rate and the solid metallization rate (MR) at the bottom outlet are increased by 0.015 and 0.11, respectively. In addition, the optimizations of the flow volume ratio (FVR) of the reducing gas fed through the AGD inlet and the AGD pipe arrangement are further discussed based on the gas flow distribution and the solid MR. Despite the relative suitability of the current FVR (60%), it is still meaningful to enable a manual adjustment of FVR, instead of having it driven by pressure difference, to solve certain production problems. On the other hand, considering the flatter distribution of gas flow, the higher solid MR, and easy installation and replacement, the cross distribution arrangement of AGD pipe with a length of 3 m is recommended to replace the current AGD pipe arrangement.

  8. Pore scale distribution of gas hydrates in sediments by micro X-ray Computed Tomography (X-CT)

    NASA Astrophysics Data System (ADS)

    Hu, G.; Li, C.; Ye, Y.; Liu, C.; Best, A. I.

    2013-12-01

    A dedicated apparatus was developed to observe in-situ pore scale distribution of gas hydrate directly during hydrate formation in artificial cores. The high-resolution X-ray Computed Tomography (type: GE Sensing & Inspection Technologies GmbH Phoenix x-ray V/tomex/s) was used and the effective resolution for observing gas hydrate bearing sediments can up to about 18μm. Methane gas hydrate was formed in 0.425-0.85mm sands under a pressure of 6MPa and a temperature of 3°C. During the process, CT scanning was conducted if there's a pressure drop (the scanning time is 66 minutes each time), so that the hydrate morphology could be detected. As a result, five scanning CT images of the same section during gas hydrate formation (i.e. hydrate saturation at 3.9%, 24.6%, 35.0%, 51.4% and 97.0%) were obtained. The result shows that at each hydrate saturation level, hydrate morphology models are complicated. The occurrence of 'floating model' (i.e. hydrate floats in pore fluid), 'contact model' (i.e. hydrate contact with the sediment particle), and the 'cementing model' (i.e. hydrates cement the sediment particles) can be found at the same time (Fig. 1). However, it shows that at different hydrate formation stages, the dominant hydrate morphology are not the same. For instance, at the first stage of hydrate formation, although there are some hydrates floating in the pore fluid, most hydrates connect the sediment particles. Consequently, the hydrate morphology at this moment can be described as a cementing model. With this method, it can be obtained that at the higher level of saturation (e.g., hydrate saturation at 24.6% and 35.0%), hydrates are mainly grow as a floating model. As hydrate saturation is much higher (e.g. after hydrate saturation is more than 51.4%), however, the floating hydrates coalesce with each other and the hydrates cement the sediment particle again. The direct observed hydrate morphology presented here may have significant impact on investigating

  9. Evolution of bubble size distribution from gas blowout in shallow water

    NASA Astrophysics Data System (ADS)

    Zhao, Lin; Boufadel, Michel C.; Lee, Kenneth; King, Thomas; Loney, Norman; Geng, Xiaolong

    2016-03-01

    Gas is often emanated from the sea bed during a subsea oil and gas blowout. The size of a gas bubble changes due to gas dissolution in the ambient water and expansion as a result of a decrease in water pressure during the rise. It is important to understand the fate and transport of gas bubbles for the purpose of environmental and safety concerns. In this paper, we used the numerical model, VDROP-J to simulate gas formation in jet/plume upon release, and dissolution and expansion while bubble rising during a relatively shallow subsea gas blowout. The model predictions were an excellent match to the experimental data. Then a gas dissolution and expansion module was included in the VDROP-J model to predict the fate and transport of methane bubbles rising due to a blowout through a 0.10 m vertical orifice. The numerical results indicated that gas bubbles would increase the mixing energy in released jets, especially at small distances and large distances from the orifice. This means that models that predict the bubble size distribution (BSD) should account for this additional mixing energy. It was also found that only bubbles of certain sizes would reach the water surfaces; small bubbles dissolve fast in the water column, while the size of the large bubbles decreases. This resulted in a BSD that was bimodal near the orifice, and then became unimodal.

  10. Full-spectrum k-distribution look-up table for nonhomogeneous gas-soot mixtures

    NASA Astrophysics Data System (ADS)

    Wang, Chaojun; Modest, Michael F.; He, Boshu

    2016-06-01

    Full-spectrum k-distribution (FSK) look-up tables provide great accuracy combined with outstanding numerical efficiency for the evaluation of radiative transfer in nonhomogeneous gaseous media. However, previously published tables cannot be used for gas-soot mixtures that are found in most combustion scenarios since it is impossible to assemble k-distributions for a gas mixed with nongray absorbing particles from gas-only full-spectrum k-distributions. Consequently, a new FSK look-up table has been constructed by optimizing the previous table recently published by the authors and then adding one soot volume fraction to this optimized table. Two steps comprise the optimization scheme: (1) direct calculation of the nongray stretching factors (a-values) using the k-distributions (k-values) rather than tabulating them; (2) deletion of unnecessary mole fractions at many thermodynamic states. Results show that after optimization, the size of the new table is reduced from 5 GB (including the k-values and the a-values for gases only) to 3.2 GB (including the k-values for both gases and soot) while both accuracy and efficiency remain the same. Two scaled flames are used to validate the new table. It is shown that the new table gives results of excellent accuracy for those benchmark results together with cheap computational cost for both gas mixtures and gas-soot mixtures.

  11. Process for forming integral edge seals in porous gas distribution plates utilizing a vibratory means

    NASA Technical Reports Server (NTRS)

    Feigenbaum, Haim (Inventor); Pudick, Sheldon (Inventor)

    1988-01-01

    A process for forming an integral edge seal in a gas distribution plate for use in a fuel cell. A seal layer is formed along an edge of a porous gas distribution plate by impregnating the pores in the layer with a material adapted to provide a seal which is operative dry or when wetted by an electrolyte of a fuel cell. Vibratory energy is supplied to the sealing material during the step of impregnating the pores to provide a more uniform seal throughout the cross section of the plate.

  12. Method for visualizing gas temperature distributions around hypersonic vehicles by using electric discharge

    NASA Astrophysics Data System (ADS)

    Nishio, Masatomi

    1993-06-01

    A method for visualizing qualitative gas temperature distributions around hypersonic vehicles by taking a photograph of the electric discharge is proposed. A gas temperature distribution over a slightly blunted wedge is visualized using the electric discharge generated by a pair of point-line electrodes. A hypersonic tunnel used for the experiment is characterized by Mach 10, a freestream duration of 10 ms, and a stagnation temperature of the tunnel barrel of 1000 K. It is concluded that the photograph shows a radiation spectrum contrast near the model surface, from which a temperature layer is seen.

  13. Inert gas a-A differences: a direct reflection of V/Q distribution.

    PubMed

    Neufeld, G R; Williams, J J; Klineberg, P L; Marshall, B E

    1978-02-01

    A computer model was developed to study the relationship between ventilation-to-perfusion (V/Q) mismatch and the development of inert gas arterial-to-alveolar partial pressure differences (a-A differences). Increasing inhomogeneity of V/Q ratio is revealed directly as an increase in the a-A difference of each gas. The quantitative relationships between the Q vs. V/Q distribution and the fractional a-A difference solubility plot (a-A difference plot) were studied and described. These studies demonstrated that for log normally distributed V/Q ratios, the area under the a-A difference plot is linearly related to the log variance of the V/Q distribution and can be estimated directly from the values obtained from six gases. The maximum a-A difference occurs for a gas whose solubility is numerically equal to the mean V/Q. The effects of departure from log normality and multimodality are discussed. We conclude from these studies that quantitative information regarding the degree of inhomogeneity of V/Q for log normal distribution is available from direct calculations of inert gas retention and excretion data. Qualitative information is also available indicating the departure from log normality and the region toward which the distribution is skewed. PMID:204618

  14. [Spatial distribution pattern of main populations and gap makers in Picea koraiensis and Abies nephrolepis forest of Xiaoxing' an Mountains, Northeast China].

    PubMed

    Jing, Xin; Duan, Wen-biao; Chen, Li-xin; Wang, Ting; Du, Shan; Zhang, Yu-shuan; Chen, Qi-min

    2015-10-01

    Species composition and diameter class structure were investigated in 1.5 hm2 (100 m x 150 n) permanent plot in Picea koraiensis and Abies nephrolepis forest of Xiaoxing' an Mountains. The spatial distribution pattern and spatial association of main populations and gap makers were analyzed by using point pattern analysis. The results showed that there were a total of 13 species with diameters at breast height greater than 2 cm in tree layer, and great differences were observed in the densities of main populations. The importance values of A. nephrolepis, P. koraiensis, Betula platyphylla and Acer ukurunduense were ranked in the first 4 in the plot. The diameter class structure of their populations presented an inverse 'J' curve. The spatial distribution patterns for A. nephrolepis and P. koraiensis were similar, which changed from aggregated, random to uniform distribution with the spatial scale. For B. platyphylla, the distribution was aggregated at ≤40 m scale, and random at >40 m scale, whereas A. ukurunduense presented an aggregated distribution pattern at the whole research scale. Except that the negative correlation between B. platyphylla and A. ukurunduense existed at the whole research scale, positive correlation between the other populations at small scale and negative correlation at large scale were observed. Only A. nephrolepis and B. platyphylla had significant positive correlation, and generally no significant correlation existed between other populations. Spatial distribution pattern of gap makers was characterized as aggregated distribution at small and middle scales, and random distribution with increasing scale. Spatial point pattern of gap makers formed by uprooting exhibited unimodal type distribution, and random, aggregated, and uniform distribution also occurred. Spatial point pattern of gap makers formed by breaking overall presented a little fluctuation, random and aggregated distributions alternatively appeared at small scale, and random

  15. Bulk-density distributions of solids in the freeboard of a gas-solid fluidized bed

    SciTech Connect

    Shen, B.C.; Fan, L.T.; Walawender, W.P.

    1995-05-01

    The freeboard region above the bubbling zone of a gas-solid fluidized bed provides the space not only for the disengagement of particles but also for additional contact and reaction between the particles and gas. The flow pattern and behavior of particles as well as their bulk-density distribution in the freeboard have a significant impact on the efficiency of fluidization. The results of numerous previous experimental studies indicate that the bulk density of solids essentially decreases exponentially as a function of the height of the freeboard. In the present work, this distribution has been obtained by first derived the Fokker-Planck equation from the linearized equation of motion of a single particle and then transforming this Fokker-Planck equation into that for the bulk-density distribution of solids. Its simplification to the one-dimensional case readily gives rise to an exponential distribution and agrees well with the available experimental data.

  16. Fish species and community distributions as proxies for seafloor habitat distributions: The Stellwagen Bank National Marine Sanctuary example (Northwest Atlantic, Gulf of Maine)

    USGS Publications Warehouse

    Auster, P.J.; Joy, K.; Valentine, P.C.

    2001-01-01

    Defining the habitats of fishes and associated fauna on outer continental shelves is problematic given the paucity of data on the actual types and distributions of seafloor habitats. However many regions have good data on the distributions of fishes from resource surveys or catch statistics because of the economic importance of the fisheries. Fish distribution data (species or communities) have been used as a proxy for the distribution of habitats to develop precautionary conservation strategies for habitat protection (e.g., marine protected areas, fishing gear restrictions). In this study we assessed the relationships between the distributions of fish communities and species derived from trawl survey data with the spatial distribution of sediment types determined by sampling and acoustic reflectance derived from multibeam sonar surveys in Stellwagen Bank National Marine Sanctuary. Fish communities were correlated with reflectance values but all communities did not occur in unique sediment types. This suggests that use of community distributions as proxies for habitats should include the caveat that a greater number of communities within an area could indicate a greater range of habitat types. Single species distributions showed relationships between abundance and reflectance values. Trawl catches with low abundances had wide variations in reflectance values while those with high abundances had narrower ranges indicating habitat affinities. Significant non-random frequency-dependent relationships were observed for 17 of 20 species although only 12 of 20 species had significant relationships based on rank correlation. These results suggest that species distributions based on trawl survey data can be used as proxies for the distribution of seafloor habitats. Species with known habitat associations can be used to infer habitat requirements of co-occurring species and can be used to identify a range of habitat types.

  17. Fish species and community distributions as proxies for sea-floor habitat distributions: the Stellwagen Bank National Marine Sanctuary example (northwest Atlantic, Gulf Of Maine)

    USGS Publications Warehouse

    Auster, Peter J.; Joy, Kevin; Valentine, Page C.

    2001-01-01

    Defining the habitats of fishes and associated fauna on outer continental shelves is problematic given the paucity of data on the actual types and distributions of seafloor habitats. However many regions have good data on the distributions of fishes from resource surveys or catch statistics because of the economic importance of the fisheries. Fish distribution data (species or communities) have been used as a proxy for the distribution of habitats to develop precautionary conservation strategies for habitat protection (e.g., marine protected areas, fishing gear restrictions). In this study we assessed the relationships between the distributions of fish communities and species derived from trawl survey data with the spatial distribution of sediment types determined by sampling and acoustic reflectance derived from multibeam sonar surveys in Stellwagen Bank National Marine Sanctuary. Fish communities were correlated with reflectance values but all communities did not occur in unique sediment types. This suggests that use of community distributions as proxies for habitats should include the caveat that a greater number of communities within an area could indicate a greater range of habitat types. Single species distributions showed relationships between abundance and reflectance values. Trawl catches with low abundances had wide variations in reflectance values while those with high abundances had narrower ranges indicating habitat affinities. Significant non-random frequency-dependent relationships were observed for 17 of 20 species although only 12 of 20 species had significant relationships based on rank correlation. These results suggest that species distributions based on trawl survey data can be used as proxies for the distribution of seafloor habitats. Species with known habitat associations can be used to infer habitat requirements of co-occurring species and can be used to identify a range of habitat types.

  18. Catalogue of the main gas manifestations in the Hellenic territory: a first step towards the estimation of the nationwide geogenic gas output

    NASA Astrophysics Data System (ADS)

    Daskalopoulou, Kyriaki; D'Alessandro, Walter; Calabrese, Sergio; Kyriakopoulos, Konstantinos; Parello, Franco

    2015-04-01

    Quantification of gaseous emissions in geological systems is an important branch because it is a major source of greenhouse gas to the atmospheric budget. Of geological environments, there are two different categories: the first category includes emissions of the predominant carbon dioxide (CO2), while the second includes emissions of the predominant methane (CH4). The Hellenic territory has a very complex geodynamic setting deriving from a long and complicated geological history. It is strongly characterized by intense seismic activity and enhanced geothermal gradient. This activity, with the contribution of an active volcanic arc, favours the existence of many cold and thermal gas manifestations. Geogenic sources release huge amounts of gases, which, apart from having important influences on the global climate, could also have a strong impact on human health. Geochemical studies based on the isotopic composition of carbon and hydrogen, along with helium isotopic ratios have become a good indicator of the origin of the gas. The isotopic ratio 13C/12C of CO2 expressed in δ 13C (‰), provides important information about the amount of CO2 released from the Earth's crust or mantle. For methane, carbon and hydrogen isotopic compositions and C1/(C2+C3) hydrocarbon ratios can characterize the origin of methane: biogenic (thermogenic or microbial) or abiogenic. Helium isotopic ratios provide additional information about crustal or mantle origin of the gas. In the present work, a large set of chemical and isotopic data is presented aiming at the identification of areas with geogenic gas emissions and their characterization in terms of different gas composition and origin. The present catalogue should be the base for the estimation total nationwide geogenic CO2 and CH4 fluxes.

  19. Vertical zonation is the main distribution pattern of littoral assemblages on rocky shores at a regional scale

    NASA Astrophysics Data System (ADS)

    Chappuis, Eglantine; Terradas, Marc; Cefalì, Maria Elena; Mariani, Simone; Ballesteros, Enric

    2014-06-01

    Vertical variation in the distribution of rocky shore assemblages is greater than horizontal variation, as shown by univariate and multivariate analysis performed with data obtained along 1000 km of shoreline and covering from the upper supralittoral to the upper infralittoral zone (-1 m). Consequently, vertical littoral zonation is a consistent pattern at a regional scale within the same biogeographical zone. While their distribution varies at the same shore height, marine species and assemblages from rocky shores show a specific vertical sequence known as zonation. A key question in ecology is how consistent is zonation along large spatial scales. The aim of this study is to show distribution patterns of littoral assemblages at a regional scale and to identify the most relevant abiotic factors associated to such patterns. The study is based on a detailed and extensive survey at a regional scale on a tideless rocky shore. Benthic macroflora and macrofauna of 750 relevés were described along the vertical axis of 143 transects distributed across the shoreline of Catalonia (NW Mediterranean). The Detrended Correspondence Analysis (DCA) first axis is highly related to the height on the shore: species, relevés, and assemblages grade from lower to upper height (infralittoral to supralittoral). As observed in nature, different assemblages co-occur at the same height at different sites, which is shown along DCA second axis. The abiotic variables that best explain the assemblage distribution patterns are: height (75% of the model inertia), longitude (14.6%), latitude (7.2%) and transect slope (2.9%). The Canonical Correspondence Analysis (CCA) first axis is related to height on the shore and explains four times more variance than CCA second axis, which is related to the horizontal gradient. Generalized Lineal Model (GLM) results show that height on the shore is the factor explaining most of the variance in species presence. Most studied species show distribution patterns

  20. Warm molecular gas temperature distribution in six local infrared bright Seyfert galaxies

    NASA Astrophysics Data System (ADS)

    Pereira-Santaella, Miguel; Spinoglio, Luigi; van der Werf, Paul P.; Piqueras López, Javier

    2014-06-01

    We simultaneously analyze the spectral line energy distributions (SLEDs) of CO and H2 of six local luminous infrared (IR) Seyfert galaxies. For the CO SLEDs, we used new Herschel/SPIRE FTS data (from J = 4-3 to J = 13-12) and ground-based observations for the lower-J CO transitions. The H2 SLEDs were constructed using archival mid-IR Spitzer/IRS and near-IR VLT/SINFONI data for the rotational and ro-vibrational H2 transitions, respectively. In total, the SLEDs contain 26 transitions with upper level energies between 5 and 15 000 K. A single, constant density, model (nH2 ~ 104.5-6 cm-3) with a broken power-law temperature distribution reproduces well both the CO and H2 SLEDs. The power-law indices are β1 ~ 1-3 for warm molecular gas (20 Kgas (T> 100 K). We show that the steeper temperature distribution (higher β) for hot molecular gas can be explained by shocks and photodissociation region (PDR) models; however, the exact β values are not reproduced by PDR or shock models alone and a combination of both is needed. We find that the three major mergers among our targets have shallower temperature distributions for warm molecular gas than the other three spiral galaxies. This can be explained by a higher relative contribution of shock excitation, with respect to PDR excitation, for the warm molecular gas in these mergers. For only one of the mergers, IRASF 05189-2524, the shallower H2 temperature distribution differs from that of the spiral galaxies. The presence of a bright active galactic nucleus in this source might explain the warmer molecular gas observed. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

  1. Heavy water reactions with atomic transition-metal and main-group cations: gas phase room-temperature kinetics and periodicities in reactivity.

    PubMed

    Cheng, Ping; Koyanagi, Gregory K; Bohme, Diethard K

    2007-09-01

    Reactions of heavy water, D(2)O, have been measured with 46 atomic metal cations at room temperature in a helium bath gas at 0.35 Torr using an inductively coupled plasma/selected ion flow tube tandem mass spectrometer. The atomic cations were produced at ca. 5500 K in an ICP source and were allowed to decay radiatively and thermalize by collisions with Ar and He atoms prior to reaction. Rate coefficients and product distributions are reported for the reactions of fourth-row atomic cations from K+ to Se+, of fifth-row atomic cations from Rb+ to Te+ (excluding Tc+), and of sixth-row atomic cations from Cs+ to Bi+. Primary reaction channels were observed leading to O-atom transfer, OD transfer, and D2O addition. O-Atom transfer occurs almost exclusively (>or=90%) in the reactions with most early transition-metal cations (Sc+, Ti+, V+, Y+, Zr+, Nb+, Mo+, Hf+, Ta+, and W+) and to a minor extent (10%) with one main-group cation (As+). OD transfer is observed to occur only with three cations (Sr+, Ba+, and La+). Other cations, including most late transition and main-group cations, were observed to react with D2O exclusively and slowly by D2O addition or not at all. O-Atom transfer proceeds with rate coefficients in the range of 8.1 x 10(-13) (As+) to 9.5 x 10(-10) (Y+) cm3 molecule(-1)(s-1) and with efficiencies below 0.1 and even below 0.01 for the fourth-row atomic cations V+ (0.0032) and As+ (0.0036). These low efficiencies can be understood in terms of the change in spin required to proceed from the reactant to the product potential energy surfaces. Higher order reactions are also measured. The primary products, NbO+, TaO+, MoO+, and WO+, are observed to react further with D(2)O by O-atom transfer, and ZrO+ and HfO+ react further through OD group abstraction. Up to five D(2)O molecules were observed to add sequentially to selected M+ and MO+ as well as MO2+ cations and four to MO(2)D+. Equilibrium measurements for sequential D(2)O addition to M+ are also reported

  2. Fractal analysis of the dark matter and gas distributions in the Mare-Nostrum universe

    SciTech Connect

    Gaite, José

    2010-03-01

    We develop a method of multifractal analysis of N-body cosmological simulations that improves on the customary counts-in-cells method by taking special care of the effects of discreteness and large scale homogeneity. The analysis of the Mare-Nostrum simulation with our method provides strong evidence of self-similar multifractal distributions of dark matter and gas, with a halo mass function that is of Press-Schechter type but has a power-law exponent -2, as corresponds to a multifractal. Furthermore, our analysis shows that the dark matter and gas distributions are indistinguishable as multifractals. To determine if there is any gas biasing, we calculate the cross-correlation coefficient, with negative but inconclusive results. Hence, we develop an effective Bayesian analysis connected with information theory, which clearly demonstrates that the gas is biased in a long range of scales, up to the scale of homogeneity. However, entropic measures related to the Bayesian analysis show that this gas bias is small (in a precise sense) and is such that the fractal singularities of both distributions coincide and are identical. We conclude that this common multifractal cosmic web structure is determined by the dynamics and is independent of the initial conditions.

  3. Sedimentological control on saturation distribution in Arctic gas-hydrate-bearing sands

    NASA Astrophysics Data System (ADS)

    Behseresht, Javad; Bryant, Steven L.

    2012-08-01

    A mechanistic model is proposed to predict/explain hydrate saturation distribution in “converted free gas” hydrate reservoirs in sub-permafrost formations in the Arctic. This 1-D model assumes that a gas column accumulates and subsequently is converted to hydrate. The processes considered are the volume change during hydrate formation and consequent fluid phase transport within the column, the descent of the base of gas hydrate stability zone through the column, and sedimentological variations with depth. Crucially, the latter enable disconnection of the gas column during hydrate formation, which leads to substantial variation in hydrate saturation distribution. One form of variation observed in Arctic hydrate reservoirs is that zones of very low hydrate saturations are interspersed abruptly between zones of large hydrate saturations. The model was applied to data from Mount Elbert well, a gas hydrate stratigraphic test well drilled in the Milne Point area of the Alaska North Slope. The model is consistent with observations from the well log and interpretations of seismic anomalies in the area. The model also predicts that a considerable amount of fluid (of order one pore volume of gaseous and/or aqueous phases) must migrate within or into the gas column during hydrate formation. This paper offers the first explanatory model of its kind that addresses “converted free gas reservoirs” from a new angle: the effect of volume change during hydrate formation combined with capillary entry pressure variation versus depth.

  4. Continuous distributions of ventilation and gas conductance to perfusion in the lungs.

    PubMed

    Yamaguchi, K; Kawai, A; Mori, M; Asano, K; Takasugi, T; Umeda, A; Yokoyama, T

    1990-01-01

    Theoretical analysis and experimental observations were conducted to establish a method allowing to demonstrate the characteristics of distribution of ventilation (VA) as well as of diffusive conductance (G) to perfusion (Q) in the lungs. O2, CO2 and CO binding to hemoglobin molecules within the erythrocyte together with six inert gases including SF6, ethane, cyclopropane, halothane, diethyl ether and acetone, of varied solubility in blood and different diffusivity in lung tissue, were used as indicator gases. 15 patients with interstitial pneumonia of unknown etiology, placed in the supine position, were given a mixture of 21% O2 and 0.1% CO in N2 as the inspired gas and saline containing appropriate amount of the six inert gases was infused via an antecubital vein. After a steady state was established, the expired gas was collected and the samples of both arterial and mixed venous blood were simultaneously taken through catheters inserted into the femoral and pulmonary artery. The concentrations of the indicator gases in the samples were measured by gas chromatography, with electrodes or with the Scholander gas analyzer. Assuming that the mass transfer efficiency of a given indicator gas at each gas exchange unit would be limited by VA/Q and G/Q ratios, the data obtained from the human subjects were analyzed in terms of a lung model having 20 units along the VA/Q and G/Q axes, respectively. The numerical analysis including the procedure of simultaneous Bohr integration for O2, CO2 and CO in a pulmonary capillary and the method of weighted least-squares combined with constrained optimization permitted the data to be transformed into a virtually continuous distribution of Q against VA/Q and G/Q axes. The numerical procedure was strictly tested using various artificial distributions of VA/Q and G/Q ratios, showing that it could characterize the distributions containing up to at least two modes on VA/Q-G/Q field with a substantial accuracy. Analytical results

  5. Natural gas distribution system leak pinpointing survey. Final report, October 1993-November 1994

    SciTech Connect

    Kinast, J.A.; Kostro, J.H.; Huebler, J.E.; Tamosaitis, V.

    1995-03-01

    The purpose of this effort was to conduct a survey of the top 100 natural gas distribution companies in the United States to collect information about their leak pinpointing procedures and ascertain what, if any, R&D is needed to improve their leak pinpointing operations

  6. 75 FR 5244 - Pipeline Safety: Integrity Management Program for Gas Distribution Pipelines; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-02

    ... final rule published December 4, 2009 (74 FR 63906), is correctly revised from February 2, 2010, to... INFORMATION: In FR Doc. E9-28467 appearing on page 63906 in the Federal Register of Friday, December 4, 2009...: Integrity Management Program for Gas Distribution Pipelines; Correction AGENCY: Pipeline and...

  7. 78 FR 10261 - Pipeline Safety: Information Collection Activities, Revision to Gas Distribution Annual Report

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-13

    ... Privacy Act Statement in the Federal Register published on April 11, 2000, (65 FR 19477) or visit http... TRANSPORTATION Pipeline and Hazardous Materials Safety Administration Pipeline Safety: Information Collection Activities, Revision to Gas Distribution Annual Report AGENCY: Pipeline and Hazardous Materials...

  8. Ecosystem Warming Affects Vertical Distribution of Leaf Gas Exchange Properties and Water Relations of Spring Wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The vertical distribution of gas exchange and water relations responses to full-season in situ infrared (IR) warming were evaluated for hard red spring wheat (Triticum aestivum L. cv. Yecora Rojo) grown in an open field in a semiarid desert region of the Southwest USA. A Temperature Free-Air Contro...

  9. Gas Chromatographic Verification of a Mathematical Model: Product Distribution Following Methanolysis Reactions.

    ERIC Educational Resources Information Center

    Lam, R. B.; And Others

    1983-01-01

    Investigated application of binomial statistics to equilibrium distribution of ester systems by employing gas chromatography to verify the mathematical model used. Discusses model development and experimental techniques, indicating the model enables a straightforward extension to symmetrical polyfunctional esters and presents a mathematical basis…

  10. Study On Temperature Distribution In T Fittings - Polyethylene Natural Gas Pipes Assemblies

    NASA Astrophysics Data System (ADS)

    Avrigean, Eugen

    2015-09-01

    The present paper intends to approach theoretically and experimentally an important topic concerning the operational safety of the polyethylene pipes used in natural gas distribution. We discuss the influence of temperature in the high density polyethylene elbows during welding to the polyethylene pipes.

  11. New Maps of the 3-D Distribution of Cold and Warm Interstellar Gas within 500pc

    NASA Astrophysics Data System (ADS)

    Welsh, Barry; Lallement, R.; Vergely, J.

    2006-12-01

    We present preliminary maps of the 3-D spatial distribution of cold (T <1000K) neutral and warm (T 5000K) partially ionized interstellar gas as traced by the NaI and CaII absorption lines observed towards stars with distances < 500pc from the Sun. These maps have been constructed from high-resolution (R 80,000) spectral data collected towards 1600 sight-lines, with the 3-D local gas density distribution being calculated from an inversion of the derived column density values. Our new maps, which trace the gas density within a 1kpc 3-D data cube surrounding the Sun, clearly show the neutral boundaries to several interstellar cavities that surround our own Local Bubble region (e.g. Loop I) and also reveal several adjacent interstellar tunnels and chimneys. Our final goal is to obtain maps based on 2000 interstellar sight-line measurements, and these data will be a valuable tool in solving several anomalies linked to the distribution of local gas such as the puzzling distribution of D-to-H values as measured within 1kpc by the NASA FUSE satellite.

  12. Temperature distribution in a layer of an active thermal insulation system heated by a gas burner

    SciTech Connect

    Maruyama, Shigenao . Inst. of Fluid Science); Shimizu, Naotaka . Dept. of Mechanical Engineering)

    1993-12-01

    The temperature distribution in a layer of an active thermal insulation system was measured. A semitransparent porous layer was heated by a gas burner, and air was injected from the back face of the layer. The temperature in the layer was measured by thermocouples. The temperature distributions were compared with numerical solutions. The thermal penetration depth of the active thermal insulation layer with gas injection can be reduced to 3 mm. When the surface temperature of a conventional insulation layer without gas injection reached 1,500 K, the temperature at the back surface of a 10-mm-thick layer reached 600 K. The transient temperature of the active thermal insulation reached a steady state very quickly compared with that of the conventional insulation. These characteristics agreed qualitatively with the numerical solutions.

  13. Distribution of gas flow in internally manifolded solid oxide fuel-cell stacks

    NASA Astrophysics Data System (ADS)

    Boersma, R. J.; Sammes, N. M.

    In internally manifolded fuel-cell stacks, there is a non-uniform gas flow distribution along the height of the system. To gain an insight into this distribution an analytical model has been developed. In the model, the stack is viewed as a network of hydraulic resistances. Some of these resistances are constant, while some depend upon the gas velocity and can be determined from the literature. The model consists of equations for the network with counter-current flow in the manifold channels. Only the most important resistances are included, i.e., the resistances due to splitting and combining the flows in the manifold channels, and the resistance in the gas channels of the active cell area. The ratio between the average flow and the flow in the upper cell can be solved from the model. In this manner, a very useful tool for separatorplate design is obtained.

  14. Study of the behavior of gas distribution equipment in hydrogen service, phase 2

    NASA Astrophysics Data System (ADS)

    Jasionowski, W. J.; Huang, H. D.

    1981-03-01

    The characteristics of gas distribution pipe in hydrogen service was studied. In experiments with three types of polyethylene natural gas piping, hydrogen permeation was found to be 4 to 6 times greater than methane permeation. Leakage experiments with methane/hydrogen blends showed no selective leakage of hydrogen via Poiseuille, turbulent, or orifice flow through leaks. Leak rates increased with increasing pressure and decreasing specific gravity. It is concluded that 13.7 x 10 to the 6th power SCF of natural gas could be lost annually in the U.S. by permeation; if hydrogen were distributed, the comparable loss would be 67.4 x 10 to the 6th power.

  15. Distribution and source of main contaminants in surface sediments of tidal flats in the Northern Shandong Province

    NASA Astrophysics Data System (ADS)

    Liu, Zhijie; Li, Peiying; Zhang, Xiaolong; Li, Ping; Xu, Yuanqin

    2014-10-01

    Twenty-nine samples of surface sediments from tidal flats in the Northern Shandong Province were collected for grain size, heavy metal (Hg, Cu, Pb, Zn, Cd, and Cr), and oil pollution analyses. The geoaccumulation index ( I geo) and factor analysis were introduced to evaluate sediment quality and source of contaminants. The mean concentrations of Hg, Cu, Pb, Zn, Cd, Cr, and oil in the surface sediments in the study area are 0.033, 17.756, 19.121, 55.700, 0.291, 59.563, and 14.213 μg g-1, respectively. The heavy metal contamination in the old delta lobe is slightly higher than that in the abandoned delta lobe; however, the opposite was observed for oil pollution. The I geo results revealed that the overall quality of the surface sediments in the study area is in good condition. The heavy metal pollution levels show a descending order: Cd> Hg> Cr> Cu> Zn> Pb, Cd being the main pollutant. The contamination level for in the study area is relatively lower than those for China's other tidal flats. Heavy metals are mainly derived from natural sources of rock weathering and erosion, partly influenced by industrial and agricultural discharge. However, oil pollution is mainly from runoff input, motorized fishing boat sewage, and oil exploitation.

  16. Probing Milky Way's hot gas halo density distribution using the dispersion measure of pulsars

    NASA Astrophysics Data System (ADS)

    Zhezher, Ya. V.; Nugaev, E. Ya.; Rubtsov, G. I.

    2016-03-01

    A number of recent studies indicates a significant amount of ionized gas in a form of the hot gas halo around the Milky Way. The halo extends over the region of 100 kpc and may be acountable for the missing baryon mass. In this paper we calculate the contribution of the proposed halo to the dispersion measure (DM) of the pulsars. The Navarro, Frenk, and White (NFW), Maller and Bullock (MB), and Feldmann, Hooper, and Gnedin (FHG) density distibutions are considered for the gas halo. The data set includes pulsars with the distance known independently from the DM, e.g., pulsars in globular clusters, LMC, SMC and pulsars with known parallax. The results exclude the NFW distribution for the hot gas, while the more realisticMB and FHG models are compatible with the observed dispersion measure.

  17. Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode.

    PubMed

    Poehlmann, Flavio R; Cappelli, Mark A; Rieker, Gregory B

    2010-12-01

    Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma deflagration. The effects of varying the bank capacitance, transmission line inductance, and applied electrode voltage were studied over the range from 14 to 112 μF, 50 to 200 nH, and 1 to 3 kV, respectively. PMID:21267082

  18. Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode

    NASA Astrophysics Data System (ADS)

    Poehlmann, Flavio R.; Cappelli, Mark A.; Rieker, Gregory B.

    2010-12-01

    Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma deflagration. The effects of varying the bank capacitance, transmission line inductance, and applied electrode voltage were studied over the range from 14 to 112 μF, 50 to 200 nH, and 1 to 3 kV, respectively.

  19. Current distribution measurements inside an electromagnetic plasma gun operated in a gas-puff mode

    PubMed Central

    Poehlmann, Flavio R.; Cappelli, Mark A.; Rieker, Gregory B.

    2010-01-01

    Measurements are presented of the time-dependent current distribution inside a coaxial electromagnetic plasma gun. The measurements are carried out using an array of six axially distributed dual-Rogowski coils in a balanced circuit configuration. The radial current distributions indicate that operation in the gas-puff mode, i.e., the mode in which the electrode voltage is applied before injection of the gas, results in a stationary ionization front consistent with the presence of a plasma deflagration. The effects of varying the bank capacitance, transmission line inductance, and applied electrode voltage were studied over the range from 14 to 112 μF, 50 to 200 nH, and 1 to 3 kV, respectively. PMID:21267082

  20. JUPITER WILL BECOME A HOT JUPITER: CONSEQUENCES OF POST-MAIN-SEQUENCE STELLAR EVOLUTION ON GAS GIANT PLANETS

    SciTech Connect

    Spiegel, David S.; Madhusudhan, Nikku E-mail: Nikku.Madhusudhan@yale.edu

    2012-09-10

    When the Sun ascends the red giant branch (RGB), its luminosity will increase and all the planets will receive much greater irradiation than they do now. Jupiter, in particular, might end up more highly irradiated than the hot Neptune GJ 436b and, hence, could appropriately be termed a 'hot Jupiter'. When their stars go through the RGB or asymptotic giant branch stages, many of the currently known Jupiter-mass planets in several-AU orbits will receive levels of irradiation comparable to the hot Jupiters, which will transiently increase their atmospheric temperatures to {approx}1000 K or more. Furthermore, massive planets around post-main-sequence stars could accrete a non-negligible amount of material from the enhanced stellar winds, thereby significantly altering their atmospheric chemistry as well as causing a significant accretion luminosity during the epochs of most intense stellar mass loss. Future generations of infrared observatories might be able to probe the thermal and chemical structure of such hot Jupiters' atmospheres. Finally, we argue that, unlike their main-sequence analogs (whose zonal winds are thought to be organized in only a few broad, planetary-scale jets), red-giant hot Jupiters should have multiple, narrow jets of zonal winds and efficient day-night redistribution.

  1. Brightness variation distributions among main belt asteroids from sparse light-curve sampling with Pan-STARRS 1

    NASA Astrophysics Data System (ADS)

    McNeill, A.; Fitzsimmons, A.; Jedicke, R.; Wainscoat, R.; Denneau, L.; Vereš, P.; Magnier, E.; Chambers, K. C.; Kaiser, N.; Waters, C.

    2016-07-01

    The rotational state of asteroids is controlled by various physical mechanisms including collisions, internal damping and the Yarkovsky-O'Keefe-Radzievskii-Paddack effect. We have analysed the changes in magnitude between consecutive detections of ˜60 000 asteroids measured by the Panoramic Survey Telescope and Rapid Response System (PanSTARRS) 1 survey during its first 18 months of operations. We have attempted to explain the derived brightness changes physically and through the application of a simple model. We have found a tendency towards smaller magnitude variations with decreasing diameter for objects of 1 < D < 8 km. Assuming the shape distribution of objects in this size range to be independent of size and composition our model suggests a population with average axial ratios 1 : 0.85 ± 0.13 : 0.71 ± 0.13, with larger objects more likely to have spin axes perpendicular to the orbital plane.

  2. Brightness variation distributions among main belt asteroids from sparse light curve sampling with Pan-STARRS 1

    NASA Astrophysics Data System (ADS)

    McNeill, A.; Fitzsimmons, A.; Jedicke, R.; Wainscoat, R.; Denneau, L.; Vereš, P.; Magnier, E.; Chambers, K. C.; Kaiser, N.; Waters, C.

    2016-04-01

    The rotational state of asteroids is controlled by various physical mechanisms including collisions, internal damping and the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect. We have analysed the changes in magnitude between consecutive detections of ˜ 60,000 asteroids measured by the PanSTARRS 1 survey during its first 18 months of operations. We have attempted to explain the derived brightness changes physically and through the application of a simple model. We have found a tendency toward smaller magnitude variations with decreasing diameter for objects of 1 < D < 8 km. Assuming the shape distribution of objects in this size range to be independent of size and composition our model suggests a population with average axial ratios 1: 0.85 ± 0.13: 0.71 ± 0.13, with larger objects more likely to have spin axes perpendicular to the orbital plane.

  3. Multiobjective optimization of water distribution systems accounting for economic cost, hydraulic reliability, and greenhouse gas emissions

    NASA Astrophysics Data System (ADS)

    Wu, Wenyan; Maier, Holger R.; Simpson, Angus R.

    2013-03-01

    In this paper, three objectives are considered for the optimization of water distribution systems (WDSs): the traditional objectives of minimizing economic cost and maximizing hydraulic reliability and the recently proposed objective of minimizing greenhouse gas (GHG) emissions. It is particularly important to include the GHG minimization objective for WDSs involving pumping into storages or water transmission systems (WTSs), as these systems are the main contributors of GHG emissions in the water industry. In order to better understand the nature of tradeoffs among these three objectives, the shape of the solution space and the location of the Pareto-optimal front in the solution space are investigated for WTSs and WDSs that include pumping into storages, and the implications of the interaction between the three objectives are explored from a practical design perspective. Through three case studies, it is found that the solution space is a U-shaped curve rather than a surface, as the tradeoffs among the three objectives are dominated by the hydraulic reliability objective. The Pareto-optimal front of real-world systems is often located at the "elbow" section and lower "arm" of the solution space (i.e., the U-shaped curve), indicating that it is more economic to increase the hydraulic reliability of these systems by increasing pipe capacity (i.e., pipe diameter) compared to increasing pumping power. Solutions having the same GHG emission level but different cost-reliability tradeoffs often exist. Therefore, the final decision needs to be made in conjunction with expert knowledge and the specific budget and reliability requirements of the system.

  4. Distribution and controls on gas hydrate in the ocean-floor environment

    SciTech Connect

    Dillon, W.P.

    1995-12-31

    Methane hydrate, a crystalline solid that is formed of water and gas molecules, is widespread in oceanic sediments. It occurs at water depths that exceed 300 to 500 m and in a zone that commonly extends from the sea floor, down several hundred meters - the base of the zone is limited by increased temperature. To determine factors that control gas hydrate concentration, we have mapped its distribution off the U.S. Atlantic coast using acoustic remote-sensing methods. Most natural gas hydrate is formed from biogenic methane, and therefore it is concentrated where there is a rapid accumulation of organic detritus and also where there is a rapid accumulation of sediments (which protect detritus from oxidation). When hydrate fills the pore space of sediment, it can reduce permeability and create a gas trap. Such trapping of gas beneath hydrate may cause the formation of the most concentrated hydrate deposits, perhaps because the gas that is held in the trap can slowly diffuse upwards or migrate through faults. Hydrate-sealed traps are formed by hills on the sea floor, by dipping strata, or by salt(?) domes. Off the southeastern United States, a small area (only 3000 km{sup 2}) beneath a ridge formed by rapidly-deposited sediments appears to contain a volume of methane in hydrate that is equivalent to {approximately}30 times the U.S. annual consumption of gas. The breakdown of hydrate can cause submarine landslides by converting the hydrate to gas plus water and generating a rise of pore pressure. Conversely, sea-floor landslides can cause breakdown of hydrate by reducing the pressure in sediments. These interacting processes may cause cascading slides, which would result in breakdown of hydrate and release of methane to the atmosphere. This addition of methane to the global greenhouse would significantly influence climate. Gas hydrate in sea-floor sediments is potentially significant to climate, energy resources, and sea-floor stability.

  5. Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: Constraints from ODP Leg 204

    USGS Publications Warehouse

    Trehu, A.M.; Long, P.E.; Torres, M.E.; Bohrmann, G.; Rack, F.R.; Collett, T.S.; Goldberg, D.S.; Milkov, A.V.; Riedel, M.; Schultheiss, P.; Bangs, N.L.; Barr, S.R.; Borowski, W.S.; Claypool, G.E.; Delwiche, M.E.; Dickens, G.R.; Gracia, E.; Guerin, G.; Holland, M.; Johnson, J.E.; Lee, Y.-J.; Liu, C.-S.; Su, X.; Teichert, B.; Tomaru, H.; Vanneste, M.; Watanabe, M. E.; Weinberger, J.L.

    2004-01-01

    Large uncertainties about the energy resource potential and role in global climate change of gas hydrates result from uncertainty about how much hydrate is contained in marine sediments. During Leg 204 of the Ocean Drilling Program (ODP) to the accretionary complex of the Cascadia subduction zone, we sampled the gas hydrate stability zone (GHSZ) from the seafloor to its base in contrasting geological settings defined by a 3D seismic survey. By integrating results from different methods, including several new techniques developed for Leg 204, we overcome the problem of spatial under-sampling inherent in robust methods traditionally used for estimating the hydrate content of cores and obtain a high-resolution, quantitative estimate of the total amount and spatial variability of gas hydrate in this structural system. We conclude that high gas hydrate content (30-40% of pore space or 20-26% of total volume) is restricted to the upper tens of meters below the seafloor near the summit of the structure, where vigorous fluid venting occurs. Elsewhere, the average gas hydrate content of the sediments in the gas hydrate stability zone is generally <2% of the pore space, although this estimate may increase by a factor of 2 when patchy zones of locally higher gas hydrate content are included in the calculation. These patchy zones are structurally and stratigraphically controlled, contain up to 20% hydrate in the pore space when averaged over zones ???10 m thick, and may occur in up to ???20% of the region imaged by 3D seismic data. This heterogeneous gas hydrate distribution is an important constraint on models of gas hydrate formation in marine sediments and the response of the sediments to tectonic and environmental change. ?? 2004 Published by Elsevier B.V.

  6. Distribution and origin of groundwater methane in the Wattenberg oil and gas field of northern Colorado.

    PubMed

    Li, Huishu; Carlson, Kenneth H

    2014-01-01

    Public concerns over potential environmental contamination associated with oil and gas well drilling and fracturing in the Wattenberg field in northeast Colorado are increasing. One of the issues of concern is the migration of oil, gas, or produced water to a groundwater aquifer resulting in contamination of drinking water. Since methane is the major component of natural gas and it can be dissolved and transported with groundwater, stray gas in aquifers has elicited attention. The initial step toward understanding the environmental impacts of oil and gas activities, such as well drilling and fracturing, is to determine the occurrence, where it is and where it came from. In this study, groundwater methane data that has been collected in response to a relatively new regulation in Colorado is analyzed. Dissolved methane was detected in 78% of groundwater wells with an average concentration of 4.0 mg/L and a range of 0-37.1 mg/L. Greater than 95% of the methane found in groundwater wells was classified as having a microbial origin, and there was minimal overlap between the C and H isotopic characterization of the produced gas and dissolved methane measured in the aquifer. Neither density of oil/gas wells nor distance to oil/gas wells had a significant impact on methane concentration suggesting other important factors were influencing methane generation and distribution. Thermogenic methane was detected in two aquifer wells indicating a potential contamination pathway from the producing formation, but microbial-origin gas was by far the predominant source of dissolved methane in the Wattenberg field. PMID:24456231

  7. Search for a Lorentz invariant velocity distribution of a relativistic gas

    NASA Astrophysics Data System (ADS)

    Curado, Evaldo M. F.; Germani, Felipe T. L.; Soares, Ivano Damião

    2016-02-01

    We examine the problem of the relativistic velocity distribution in a 1-dim relativistic gas in thermal equilibrium. We use numerical simulations of the relativistic molecular dynamics for a gas with two components, light and heavy particles. However in order to obtain the numerical data our treatment distinguishes two approaches in the construction of the histograms for the same relativistic molecular dynamic simulations. The first, largely considered in the literature, consists in constructing histograms with constant bins in the velocity variable and the second consists in constructing histograms with constant bins in the rapidity variable which yields Lorentz invariant histograms, contrary to the first approach. For histograms with constant bins in the velocity variable the numerical data are fitted accurately by the Jüttner distribution which is also not Lorentz invariant. On the other hand, the numerical data obtained from histograms constructed with constant bins in the rapidity variable, which are Lorentz invariant, are accurately fitted by a Lorentz invariant distribution whose derivation is discussed in this paper. The histograms thus constructed are not fitted by the Jütter distribution (as they should not). Our derivation is based on the special theory of relativity, the central limit theorem and the Lobachevsky structure of the velocity space of the theory, where the rapidity variable plays a crucial role. For v2 /c2 ≪ 1 and 1 / β ≡kB T /m0c2 ≪ 1 the distribution tends to the Maxwell-Boltzmann distribution.

  8. 77 FR 5472 - Pipeline Safety: Expanding the Use of Excess Flow Valves in Gas Distribution Systems to...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-03

    ... FR 72666). The ANPRM sought public comment on several issues related to expanding the use of EFVs in...: Expanding the Use of Excess Flow Valves in Gas Distribution Systems to Applications Other Than Single-Family... Safety: Expanding the Use of Excess Flow Valves (EFVs) in Gas Distribution Systems to Applications...

  9. Analysis of swarm coefficients in a gas for bi-modal electron energy distribution model

    NASA Astrophysics Data System (ADS)

    Govinda-Raju, Gorur

    2015-03-01

    Cross sections for collision between electrons and neutrals in a gas discharge are essential for theoretical and computational developments. They are also required to interpret and analyze the results of experimental studies on swarm parameters namely drift velocity, characteristic energy, and ionization and attachment coefficients. The cross sections and swarm coefficients are interconnected through the most important electron energy distribution function. The traditional method of solving the Boltzmann equation numerically yields the required distribution (EEDF). However there are many situations where a simpler approach is desirable for deriving the energy distribution analytically. Energy distribution in non-uniform electric fields, in crossed electric and magnetic fields, breakdown in mixtures of gases for electrical power or plasma applications, calculation of longitudinal diffusion coefficients are examples. In other studies the swarm parameters are employed to derive the cross sections in an unfolding procedure that also involves the energy distribution function. Application of Boltzmann solution method, though more rigorous, consumes enormous efforts in time and technical expertise. In an attempt to provide a simpler method the present author has previously suggested a bimodal electron energy distribution in gases. In this paper the author has generalized the idea of bi-modal energy distribution by considering a model gas with representative cross sections and adopted numerical methods for greater accuracy. The parameters considered are the nature of the two distributions, their relative ratio, and the dependence of cross sections on electron energy. A new method for determining the combination of distributions has been shown to be adequate for calculation of swarm parameters. The results for argon are shown to yield very good agreement with available experimental and theoretical values.

  10. Central Appalachian basin natural gas database: distribution, composition, and origin of natural gases

    USGS Publications Warehouse

    Román Colón, Yomayra A.; Ruppert, Leslie F.

    2015-01-01

    The U.S. Geological Survey (USGS) has compiled a database consisting of three worksheets of central Appalachian basin natural gas analyses and isotopic compositions from published and unpublished sources of 1,282 gas samples from Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. The database includes field and reservoir names, well and State identification number, selected geologic reservoir properties, and the composition of natural gases (methane; ethane; propane; butane, iso-butane [i-butane]; normal butane [n-butane]; iso-pentane [i-pentane]; normal pentane [n-pentane]; cyclohexane, and hexanes). In the first worksheet, location and American Petroleum Institute (API) numbers from public or published sources are provided for 1,231 of the 1,282 gas samples. A second worksheet of 186 gas samples was compiled from published sources and augmented with public location information and contains carbon, hydrogen, and nitrogen isotopic measurements of natural gas. The third worksheet is a key for all abbreviations in the database. The database can be used to better constrain the stratigraphic distribution, composition, and origin of natural gas in the central Appalachian basin.

  11. Influence of Permian salt dissolution on distribution of shallow Niobrara gas fields, eastern Colorado

    SciTech Connect

    Oldham, D.W.; Smosna, R.A.

    1996-06-01

    Subsurface analysis of Permian salt and related strata in the shallow Niobrara gas area on the eastern flank of the Denver basin reveals that the location of faulted anticlines which produce gas from porous chalk is related to the occurrence of six Nippewalla Group (Leonardian) salt zones. Salt distribution is controlled by the configuration of evaporate basins during the Leonardian, truncation at a sub-Jurassic unconformity (which has completely removed Guadalupian salts), and post-Jurassic subsurface dissolution. Significant dissolution took place in response to Laramide orogeny and subsequent eastward regional groundwater flow within the Lyons (Cedar Hills) Sandstone aquifer. Initially, dissolution occurred along a regional facies change from sandstone to salt. Solution collapse allowed for cross-formational flow and removal of younger salts. Shallow Niobrara gas fields are situated above salt outliers or along regionally updip salt edges. No significant Niobrara production exists in areas where salt is absent. Structural relief across fields is related to Leonardian thickness variations, rather than subsalt offset. Seismic data reveal abrupt Leonardian thinning at the regionally updip limit of Eckley field, which has produced over 33 BCFG. Thickness of residual salt may be important in controlling the amount of gas trapped within the Niobrara. Where thick salts are preserved, structural relief is greater, the gas-water transition zone is thicker, and gas saturation is higher at the crests of faulted anticlines.

  12. Distribution of Organophosphate Esters between the Gas and Particle Phase-Model Predictions vs Measured Data.

    PubMed

    Sühring, Roxana; Wolschke, Hendrik; Diamond, Miriam L; Jantunen, Liisa M; Scheringer, Martin

    2016-07-01

    Gas-particle partitioning is one of the key factors that affect the environmental fate of semivolatile organic chemicals. Many organophosphate esters (OPEs) have been reported to primarily partition to particles in the atmosphere. However, because of the wide range of their physicochemical properties, it is unlikely that OPEs are mainly in the particle phase "as a class". We compared gas-particle partitioning predictions for 32 OPEs made by the commonly used OECD POV and LRTP Screening Tool ("the Tool") with the partitioning models of Junge-Pankow (J-P) and Harner-Bidleman (H-B), as well as recently measured data on OPE gas-particle partitioning. The results indicate that half of the tested OPEs partition into the gas phase. Partitioning into the gas phase seems to be determined by an octanol-air partition coefficient (log KOA) < 10 and a subcooled liquid vapor pressure (log PL) > -5 (PL in Pa), as well as the total suspended particle concentration (TSP) in the sampling area. The uncertainty of the physicochemical property data of the OPEs did not change this estimate. Furthermore, the predictions by the Tool, J-P- and H-B-models agreed with recently measured OPE gas-particle partitioning. PMID:27144674

  13. A dynamical model for the distribution of dark matter and gas in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Rasia, Elena; Tormen, Giuseppe; Moscardini, Lauro

    2004-06-01

    Using the results of an extended set of high-resolution non-radiative hydrodynamic simulations of galaxy clusters, we obtain simple analytic formulae for the dark matter and hot gas distribution, in the spherical approximation. Starting from the dark matter phase-space radial density distribution, we derive fits for the dark matter density, velocity dispersion and velocity anisotropy. We use these models to test the dynamical equilibrium hypothesis through the Jeans equation: we find that this is satisfied to good accuracy by our simulated clusters inside their virial radii. This result also shows that our fits constitute a self-consistent dynamical model for these systems. We then extend our analysis to the hot gas component, obtaining analytic fits for the gas density, temperature and velocity structure, with no further hypothesis on the gas dynamical status or state equation. Gas and dark matter show similar density profiles down to ~0.06Rv (with Rv the virial radius), while at smaller radii the gas flattens, producing a central core. Gas temperatures are almost isothermal out to roughly 0.2 Rv, then steeply decrease, reaching at the virial radius a value almost a factor of 2 lower. We find that the gas is not at rest inside Rv: velocity dispersions are increasing functions of the radius, motions are isotropic to slightly tangential, and contribute non-negligibly to the total pressure support. We test this model using a generalization of the hydrostatic equilibrium equation, where the gas motion is properly taken into account. Again we find that the fits provide an accurate description of the system: the hot gas is in equilibrium and is a good tracer of the overall cluster potential if all terms (density, temperature and velocity) are taken into account, while simpler assumptions cause systematic mass underestimates. In particular, we find that using the so-called β-model underestimates the true cluster mass by up to 50 per cent at large radii. We also find

  14. Distribution and Mass of Diffuse and Dense CO Gas in the Milky Way

    NASA Astrophysics Data System (ADS)

    Roman-Duval, Julia; Heyer, Mark; Brunt, Christopher M.; Clark, Paul; Klessen, Ralf; Shetty, Rahul

    2016-02-01

    Emission from carbon monoxide (CO) is ubiquitously used as a tracer of dense star-forming molecular clouds. There is, however, growing evidence that a significant fraction of CO emission originates from diffuse molecular gas. Quantifying the contribution of diffuse CO-emitting gas is vital for understanding the relation between molecular gas and star formation. We examine the Galactic distribution of two CO-emitting gas components, a high column density component detected in 13CO and 12CO, and a low column density component detected in 12CO, but not in 13CO. The “diffuse” and “dense” components are identified using a combination of smoothing, masking, and erosion/dilation procedures, making use of three large-scale 12CO and 13CO surveys of the inner and outer Milky Way. The diffuse component, which globally represents 25% (1.5 × 108M⊙) of the total molecular gas mass (6.5 × {10}8 M⊙), is more extended perpendicular to the Galactic plane. The fraction of diffuse gas increases from ˜10%-20% at a galactocentric radius of 3-4 kpc to 50% at 15 kpc, and increases with decreasing surface density. In the inner Galaxy, a yet denser component traced by CS emission represents 14% of the total molecular gas mass traced by 12CO emission. Only 14% of the molecular gas mass traced by 12CO emission is identified as part of molecular clouds in 13CO surveys by cloud identification algorithms. This study indicates that CO emission not only traces star-forming clouds, but also a significant diffuse molecular ISM component.

  15. Altitude Investigation of Gas Temperature Distribution at Turbine of Three Similar Axial-Flow Turbojet Engines

    NASA Technical Reports Server (NTRS)

    Prince, W.R.; Schulze, F.W.

    1952-01-01

    An investigation of the effect of inlet pressure, corrected engine speed, and turbine temperature level on turbine-inlet gas temperature distributions was conducted on a J40-WE-6, interim J40-WE-6, and prototype J40-WE-8 turbojet engine in the altitude wind tunnel at the NAC.4 Lewis laboratory. The engines were investigated over a range of simulated pressure altitudes from 15,000 to 55,000 feet, flight Mach numbers from 0.12 to 0.64, and corrected engine speeds from 7198 to 8026 rpm, The gas temperature distribution at the turbine of the three engines over the range of operating conditions investigated was considered satisfactory from the standpoint of desired temperature distribution with one exception - the distribution for the J40-WE-6 engine indicated a trend with decreasing engine-inlet pressure for the temperature to exceed the desired in the region of the blade hub. Installation of a compressor-outlet mixer vane assembly remedied this undesirable temperature distribution, The experimental data have shown that turbine-inlet temperature distributions are influenced in the expected manner by changes in compressor-outlet pressure or mass-flow distribution and by changes in combustor hole-area distribution. The similarity between turbine-inlet and turbine-outlet temperature distribution indicated only a small shift in temperature distribution imposed by the turbine rotors. The attainable jet thrusts of the three engines were influenced in different degrees and directions by changes in temperature distributions with change in engine-inlet pressure. Inability to match the desired temperature distribution resulted, for the J40-WE-6 engine, in an 11-percent thrust loss based on an average turbine-inlet temperature of 1500 F at an engine-inlet pressure of 500 pounds per square foot absolute. Departure from the desired temperature distribution in the Slade tip region results, for the prototype J40-WE-8 engine, in an attainable thrust increase of 3 to 4 percent as

  16. Particle multiplicity distributions: Connections with a Feynman-Wilson gas and a Ginzburg-Landau theory

    NASA Astrophysics Data System (ADS)

    Mekjian, A. Z.

    2002-01-01

    Particle yields and fluctuations are studied in a general framework based on a cycle class picture in a Feynman path integral approach. Various cases such as the disoriented chiral condensate distribution, a negative binomial distribution, partially coherent state emission, and field emission from Lorentzian line shapes are discussed. Generalizations based on these important specific cases are developed. Connections of the cycle class picture with other approaches based on combinants, cumulants, hierarchical models, and clan variables are presented for the specific and general cases. A relation to a Feynman-Wilson gas and to the Ginzburg-Landau model are discussed.

  17. Three-Dimensional Statistical Gas Distribution Mapping in an Uncontrolled Indoor Environment

    SciTech Connect

    Reggente, Matteo; Lilienthal, Achim J.

    2009-05-23

    In this paper we present a statistical method to build three-dimensional gas distribution maps (3D-DM). The proposed mapping technique uses kernel extrapolation with a tri-variate Gaussian kernel that models the likelihood that a reading represents the concentration distribution at a distant location in the three dimensions. The method is evaluated using a mobile robot equipped with three 'e-noses' mounted at different heights. Initial experiments in an uncontrolled indoor environment are presented and evaluated with respect to the ability of the 3D map, computed from the lower and upper nose, to predict the map from the middle nose.

  18. Gas exchange and intrapulmonary distribution of ventilation during continuous-flow ventilation

    SciTech Connect

    Vettermann, J.; Brusasco, V.; Rehder, K.

    1988-05-01

    In 12 anesthetized paralyzed dogs, pulmonary gas exchange and intrapulmonary inspired gas distribution were compared between continuous-flow ventilation (CFV) and conventional mechanical ventilation (CMV). Nine dogs were studied while they were lying supine, and three dogs were studied while they were lying prone. A single-lumen catheter for tracheal insufflation and a double-lumen catheter for bilateral endobronchial insufflation (inspired O2 fraction = 0.4; inspired minute ventilation = 1.7 +/- 0.3 (SD) 1.kg-1.min-1) were evaluated. Intrapulmonary gas distribution was assessed from regional 133Xe clearances. In dogs lying supine, CO2 elimination was more efficient with endobronchial insufflation than with tracheal insufflation, but the alveolar-arterial O2 partial pressure difference was larger during CFV than during CMV, regardless of the type of insufflation. By contrast, endobronchial insufflation maintained both arterial PCO2 and alveolar-arterial O2 partial pressure difference at significantly lower levels in dogs lying prone than in dogs lying supine. In dogs lying supine, the dependent lung was preferentially ventilated during CMV but not during CFV. In dogs lying prone, gas distribution was uniform with both modes of ventilation. The alveolar-arterial O2 partial pressure difference during CFV in dogs lying supine was negatively correlated with the reduced ventilation of the dependent lung, which suggests that increased ventilation-perfusion mismatching was responsible for the increase in alveolar-arterial O2 partial pressure difference. The more efficient oxygenation during CFV in dogs lying prone suggests a more efficient matching of ventilation to perfusion, presumably because the distribution of blood flow is also nearly uniform.

  19. Natural gas transmission and distribution model of the National Energy Modeling System

    SciTech Connect

    1997-02-01

    The Natural Gas Transmission and Distribution Model (NGTDM) is the component of the National Energy Modeling System (NEMS) that is used to represent the domestic natural gas transmission and distribution system. NEMS was developed in the Office of Integrated Analysis and Forecasting of the Energy Information Administration (EIA). NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the EIA and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. From 1982 through 1993, the Intermediate Future Forecasting System (IFFS) was used by the EIA for its analyses, and the Gas Analysis Modeling System (GAMS) was used within IFFS to represent natural gas markets. Prior to 1982, the Midterm Energy Forecasting System (MEFS), also referred to as the Project Independence Evaluation System (PIES), was employed. NEMS was developed to enhance and update EIA`s modeling capability by internally incorporating models of energy markets that had previously been analyzed off-line. In addition, greater structural detail in NEMS permits the analysis of a broader range of energy issues. The time horizon of NEMS is the midterm period (i.e., through 2015). In order to represent the regional differences in energy markets, the component models of NEMS function at regional levels appropriate for the markets represented, with subsequent aggregation/disaggregation to the Census Division level for reporting purposes.

  20. Gas hydrate and P-Wave Velocity Distribution in the Yaquina Basin at the Peruvian margin

    NASA Astrophysics Data System (ADS)

    Huebscher, C.; Gajewski, D.; Grobys, J.; Kukowski, N.; Netzeband, G.; Wagner, M.; Bialas, J.

    2003-04-01

    The lower boundary of the methane hydrate stability zone in continental margin sediments is often marked by a strong, phase reversed reflection subparallel to the seafloor, called the bottom simulating reflector (BSR). High resolution multichannel seismic (MCS) data from the Yaquina Basin offshore Peru at 8 deg S show a BSR that is varying laterally in amplitude as well as in continuity. The amplitudes of the reflections above the BSR also vary with the appearance of the BSR. Where the BSR is strong, the reflections above it are weaker compared to areas where the BSR is weak. And although the strong part of the BSR is underlain immediately by strong reflections, reflections several hundred meters beneath the BSR appear weaker than those where the BSR is weak. This variation indicates significant heterogeneity in the distribution of gas and gas hydrate in this area. Chemoherms observed at the Yaquina Basin sea floor indicate the presence of free gas in the sediments up to the seafloor. The presence of gas and gas hydrate within the sediment sequence significantly influences the P-wave velocity in the affected layers. Therefore a detailed analysis of velocity variations enables to understand the apparently different conditions for the formation of gas hydrate along the BSR and the migration paths of the free gas. Ocean bottom seismometer (OBS) data from profiles coincident with the MCS data can provide such detailed velocity depth information. Velocity analysis from OBS data included 2D-ray tracing and 1D-interval-velocity analysis by means of DIX-inversion. In order to find a trade-off between vertical resolution and minimization of errors caused by the sensitivity of the DIX' formula to velocity variations in thin layers, the data have undergone a Kirchhoff wave-equation datuming and adjacent coherence filtering was applied to the data to eliminate the one sided travel path through the water column of the OBS-observations. The derived velocity structure confirms

  1. Heat Transfer and Pressure Distributions on a Gas Turbine Blade Tip

    NASA Technical Reports Server (NTRS)

    Azad, Gm S.; Han, Je-Chin; Teng, Shuye; Boyle, Robert J.

    2000-01-01

    Heat transfer coefficient and static pressure distributions are experimentally investigated on a gas turbine blade tip in a five-bladed stationary linear cascade. The blade is a 2-dimensional model of a first stage gas turbine rotor blade with a blade tip profile of a GE-E(sup 3) aircraft gas turbine engine rotor blade. The flow condition in the test cascade corresponds to an overall pressure ratio of 1.32 and exit Reynolds number based on axial chord of 1.1 x 10(exp 6). The middle 3-blade has a variable tip gap clearance. All measurements are made at three different tip gap clearances of about 1%, 1.5%, and 2.5% of the blade span. Heat transfer measurements are also made at two different turbulence intensity levels of 6.1 % and 9.7% at the cascade inlet. Static pressure measurements are made in the mid-span and the near-tip regions as well as on the shroud surface, opposite the blade tip surface. Detailed heat transfer coefficient distributions on the plane tip surface are measured using a transient liquid crystal technique. Results show various regions of high and low heat transfer coefficient on the tip surface. Tip clearance has a significant influence on local tip beat transfer coefficient distribution. Heat transfer coefficient also increases about 15-20% along the leakage flow path at higher turbulence intensity level of 9.7% over 6.1 %.

  2. Widely tunable Sampled Grating Distributed Bragg Reflector Quantum Cascade laser for gas spectroscopy applications

    NASA Astrophysics Data System (ADS)

    Diba, Abdou Salam

    Since the advent of semiconductor lasers, the development of tunable laser sources has been subject of many efforts in industry and academia arenas. This interest towards broadly tunable lasers is mainly due to the great promise they have in many applications ranging from telecommunication, to environmental science and homeland security, just to name a few. After the first demonstration of quantum cascade laser (QCL) in the early nineties, QCL has experienced a rapid development, so much so that QCLs are now the most reliable and efficient laser source in the Mid-IR range covering between 3 microm to 30 microm region of the electromagnetic spectrum. QCLs have almost all the desirable characteristics of a laser for spectroscopy applications such as narrow spectral linewidth ideal for high selectivity measurement, high power enabling high sensitivity sensing and more importantly they emit in the finger-print region of most of the trace gases and large molecules. The need for widely tunable QCLs is now more pressing than ever before. A single mode quantum cascade laser (QCL) such as a distributed feedback (DFB) QCL, is an ideal light source for gas sensing in the MIR wavelength range. Despite their performance and reliability, DFB QCLs are limited by their relatively narrow wavelength tuning range determined by the thermal rollover of the laser. An external cavity (EC) QCL, on the other hand, is a widely tunable laser source, and so far is the choice mid-infrared single frequency light sources for detecting multiple species/large molecules. However, EC QCLs can be complex, bulky and expensive. In the quest for finding alternative broadly wavelength tunable sources in the mid-infrared, many monolithic tunable QCLs are recently proposed and fabricated, including SG-DBR, DFB-Arrays, Slot-hole etc. and they are all of potentially of interest as a candidate for multi-gas sensing and monitoring applications, due to their large tuning range (>50 cm-1), and potentially low

  3. DETERMINING ALL GAS PROPERTIES IN GALAXY CLUSTERS FROM THE DARK MATTER DISTRIBUTION ALONE

    SciTech Connect

    Frederiksen, Teddy F.; Hansen, Steen H.; Host, Ole; Roncadelli, Marco

    2009-08-01

    We demonstrate that all properties of the hot X-ray emitting gas in galaxy clusters are completely determined by the underlying dark matter (DM) structure. Apart from the standard conditions of spherical symmetry and hydrostatic equilibrium for the gas, our proof is based on the Jeans equation for the DM and two simple relations which have recently emerged from numerical simulations: the equality of the gas and DM temperatures, and the almost linear relation between the DM velocity anisotropy profile and its density slope. For DM distributions described by the Navarro-Frenk-White or the Sersic profiles, the resulting gas density profile, the gas-to-total-mass ratio profile, and the entropy profile are all in good agreement with X-ray observations. All these profiles are derived using zero free parameters. Our result allows us to predict the X-ray luminosity profile of a cluster in terms of its DM content alone. As a consequence, a new strategy becomes available to constrain the DM morphology in galaxy clusters from X-ray observations. Our results can also be used as a practical tool for creating initial conditions for realistic cosmological structures to be used in numerical simulations.

  4. Mobile Methane Measurements of Natural Gas Distribution and End-use Emissions in Indianapolis

    NASA Astrophysics Data System (ADS)

    Lamb, B. K.; Roscioli, J. R.; Floerchinger, C. R.; Herndon, S. C.; Ferrara, T.

    2015-12-01

    Indianapolis is the site of the INFLUX program to investigate greenhouse gas emissions from a large metropolitan area. A key question in INFLUX is the relative contributions of methane emissions from the local gas distribution system in comparison to biogenic sources, such as the wastewater treatment system and landfills, and of end use emissions from furnaces and other combustion devices downstream of customer gas meters. During February and March, 2015, the Aerodyne van was used to measure methane, ethane, CO2 and other trace gases during mobile sampling traverses through a number of urban and suburban Indianapolis neighborhoods. Signatures of distinct natural gas emissions, biogenic emissions, and combustion emissions were observed in small plumes. In a number of cases, these sources were identified as manhole covers in city streets, where nearby leaks can seep into the local wastewater system. Quantification of ethane and methane from 45 manholes reveal that some had emissions that were clearly biogenic while others had a distinct natural gas signature. This paper describes the results from the analysis of these mobile data in the context of the current Indianapolis methane emission inventory.

  5. WARM GAS IN THE VIRGO CLUSTER. I. DISTRIBUTION OF Ly{alpha} ABSORBERS

    SciTech Connect

    Yoon, Joo Heon; Putman, Mary E.; Bryan, Greg L.; Thom, Christopher; Chen, Hsiao-Wen

    2012-08-01

    The first systematic study of the warm gas (T = 10{sup 4-5} K) distribution across a galaxy cluster is presented using multiple background QSOs in and around the Virgo Cluster. We detect 25 Ly{alpha} absorbers (N{sub HI} = 10{sup 13.1-15.4} cm{sup -2}) in the Virgo velocity range toward 9 of 12 QSO sightlines observed with the Cosmic Origin Spectrograph, with a cluster impact parameter range of 0.36-1.65 Mpc (0.23-1.05 R{sub vir}). Including 18 Ly{alpha} absorbers previously detected by STIS or GHRS toward 7 of 11 background QSOs in and around the Virgo Cluster, we establish a sample of 43 absorbers toward a total of 23 background probes for studying the incidence of Ly{alpha} absorbers in and around the Virgo Cluster. With these absorbers, we find (1) warm gas is predominantly in the outskirts of the cluster and avoids the X-ray-detected hot intracluster medium (ICM). Also, Ly{alpha} absorption strength increases with cluster impact parameter. (2) Ly{alpha}-absorbing warm gas traces cold H I-emitting gas in the substructures of the Virgo Cluster. (3) Including the absorbers associated with the surrounding substructures, the warm gas covering fraction (100% for N{sub HI} > 10{sup 13.1} cm{sup -2}) is in agreement with cosmological simulations. We speculate that the observed warm gas is part of large-scale gas flows feeding the cluster both in the ICM and galaxies.

  6. Fabrication of gas impervious edge seal for a bipolar gas distribution assembly for use in a fuel cell

    DOEpatents

    Kaufman, Arthur; Werth, John

    1986-01-01

    A bipolar gas reactant distribution assembly for use in a fuel cell is disclosed, the assembly having a solid edge seal to prevent leakage of gaseous reactants wherein a pair of porous plates are provided with peripheral slits generally parallel to, and spaced apart from two edges of the plate, the slit being filled with a solid, fusible, gas impervious edge sealing compound. The plates are assembled with opposite faces adjacent one another with a layer of a fusible sealant material therebetween the slits in the individual plates being approximately perpendicular to one another. The plates are bonded to each other by the simultaneous application of heat and pressure to cause a redistribution of the sealant into the pores of the adjacent plate surfaces and to cause the edge sealing compound to flow and impregnate the region of the plates adjacent the slits and comingle with the sealant layer material to form a continuous layer of sealant along the edges of the assembled plates.

  7. Intensity Distribution of Laser Induced Plasma Generated at Different Ambient Gas Preassure

    NASA Astrophysics Data System (ADS)

    Sarmiento, Rafael; Cabanzo, Rafael; Mejia-Ospino, Enrique

    2008-04-01

    In this work, intensity distributions of laser induced plasmas have been measured by emission with two-dimensional spatial resolution and temporal resolution. The plasmas have been generated on the surfaces of steel samples at different pressures of air and argon, in the ranges from l*10-6 to 680 Torr. We compare the features of the intensity spatial and temporal distribution in the two ambient studied here. We observed that the maxima values of intensity are obtained when the pressure is maxima. The features of intensity distribution show a significant change with the ambient and gas pressure. Also, we have measured how change the size of the plasma plume with the pressure at two different ambient.

  8. Correlation energy, structure factor, radial distribution function, and momentum distribution of the spin-polarized uniform electron gas

    NASA Astrophysics Data System (ADS)

    Ortiz, G.; Ballone, P.

    1994-07-01

    The properties of the three-dimensional uniform electron gas in the Fermi liquid regime are analyzed using variational Monte Carlo (VMC) and fixed-node diffusion Monte Carlo methods. Our study extends those of Ceperley [Phys. Rev. B 18, 3126 (1978)] and Ceperley and Alder [Phys. Rev. Lett. 45, 566 (1980)] to larger system sizes with improved statistics and, more importantly, to partial spin polarization. The density range 0.8<=rs<=10, which is the most relevant for density functional computations, is studied in detail. We analyze the size dependence of the simulation results and present an extended set of correlation energies extrapolated to the thermodynamic limit. Using the VMC method we analyze the spin dependence of the correlation energy, and we compare our results to several interpolation formulas used in density functional calculations. We summarize our results by a simple interpolation formula. In addition, we present results for the radial distribution function, the structure factor, the momentum distribution, and triplet correlation functions, and we discuss the comparison with many-body semianalytic theories.

  9. Gas Puff Radiation Performance As a Function of Radial Mass Distribution

    NASA Astrophysics Data System (ADS)

    Coleman, Philip L.; Krishnan, Mahadevan; Prasad, Rahul; Qi, Niansheng; Waisman, Eduardo; Failor, B. H.; Levine, J. S.; Sze, H.

    2002-12-01

    The basic concept of a z-pinch, that JxB forces implode a shell of mass, creating a hot dense plasma on-axis, is coming under closer scrutiny. Wire arrays may start with an initial cold mass in a near "ideal" shell, but in fact they appear to develop complex radial mass distributions well before the final x-ray output [1,2]. We consider here the situation for gas puff z-pinches. While the ideal of a gas "shell" has been the nominal objective for many years, detailed measurements of gas flow show that nozzles used for plasma radiation sources (PRS) also have complex radial distributions. In particular, there are significant data [3] showing that the best x-ray yield comes from the least shell-like distributions. Recent experiments on the Double Eagle generator with argon have further enhanced this view [4]. For those tests with a double "shell" nozzle, there was a factor of almost 4 increase in yield when the relative mass (outer:inner) in the two shells was changed from 2:1 to less than 1:1. We suggest the following explanation. A configuration with most of its mass at large radii is subject to severe disruption by instabilities during the implosion. A more continuous radial mass distribution with dρ/dr < 0 may mitigate instability development (via the "snowplow stabilization" [5] mechanism) and thus enhance the thermalization of the kinetic energy of the imploding mass. In addition, the appropriate balance of outer to inner mass maximizes the formation of a strong shock in the core of the pinch that heats the plasma and leads to x-ray emission.

  10. Regulatory reform for natural gas pipelines: The effect on pipeline and distribution company share prices

    NASA Astrophysics Data System (ADS)

    Jurman, Elisabeth Antonie

    1997-08-01

    The natural gas shortages in the 1970s focused considerable attention on the federal government's role in altering energy consumption. For the natural gas industry these shortages eventually led to the passage of the Natural Gas Policy Act (NGPA) in 1978 as part of the National Energy Plan. A series of events in the decade of the 1980s has brought about the restructuring of interstate natural gas pipelines which have been transformed by regulators and the courts from monopolies into competitive entities. This transformation also changed their relationship with their downstream customers, the LDCs, who no longer had to deal with pipelines as the only merchants of gas. Regulatory reform made it possible for LDCs to buy directly from producers using the pipelines only for delivery of their purchases. This study tests for the existence of monopoly rents by analyzing the daily returns of natural gas pipeline and utility industry stock price data from 1982 to 1990, a period of regulatory reform for the natural gas industry. The study's main objective is to investigate the degree of empirical support for claims that regulatory reforms increase profits in the affected industry, as the normative theory of regulation expects, or decrease profits, as advocates of the positive theory of regulation believe. I also test Norton's theory of risk which predicts that systematic risk will increase for firms undergoing deregulation. Based on a sample of twelve natural gas pipelines, and 25 utilities an event study concept was employed to measure the impact of regulatory event announcements on daily natural gas pipeline or utility industry stock price data using a market model regression equation. The results of this study provide some evidence that regulatory reforms did not increase the profits of pipeline firms, confirming the expectations of those who claim that excess profits result from regulation and will disappear, once that protection is removed and the firms are operating in

  11. GREENHOUSE GAS REDUCTION POTENTIAL WITH COMBINED HEAT AND POWER WITH DISTRIBUTED GENERATION PRIME MOVERS - ASME 2012

    SciTech Connect

    Curran, Scott; Theiss, Timothy J; Bunce, Michael

    2012-01-01

    Pending or recently enacted greenhouse gas regulations and mandates are leading to the need for current and feasible GHG reduction solutions including combined heat and power (CHP). Distributed generation using advanced reciprocating engines, gas turbines, microturbines and fuel cells has been shown to reduce greenhouse gases (GHG) compared to the U.S. electrical generation mix due to the use of natural gas and high electrical generation efficiencies of these prime movers. Many of these prime movers are also well suited for use in CHP systems which recover heat generated during combustion or energy conversion. CHP increases the total efficiency of the prime mover by recovering waste heat for generating electricity, replacing process steam, hot water for buildings or even cooling via absorption chilling. The increased efficiency of CHP systems further reduces GHG emissions compared to systems which do not recover waste thermal energy. Current GHG mandates within the U.S Federal sector and looming GHG legislation for states puts an emphasis on understanding the GHG reduction potential of such systems. This study compares the GHG savings from various state-of-the- art prime movers. GHG reductions from commercially available prime movers in the 1-5 MW class including, various industrial fuel cells, large and small gas turbines, micro turbines and reciprocating gas engines with and without CHP are compared to centralized electricity generation including the U.S. mix and the best available technology with natural gas combined cycle power plants. The findings show significant GHG saving potential with the use of CHP. Also provided is an exploration of the accounting methodology for GHG reductions with CHP and the sensitivity of such analyses to electrical generation efficiency, emissions factors and most importantly recoverable heat and thermal recovery efficiency from the CHP system.

  12. Baryonic distributions in galaxy dark matter haloes - I. New observations of neutral and ionized gas kinematics

    NASA Astrophysics Data System (ADS)

    Richards, Emily E.; van Zee, L.; Barnes, K. L.; Staudaher, S.; Dale, D. A.; Braun, T. T.; Wavle, D. C.; Dalcanton, J. J.; Bullock, J. S.; Chandar, R.

    2016-07-01

    We present a combination of new and archival neutral hydrogen (H I) observations and new ionized gas spectroscopic observations for 16 galaxies in the statistically representative Extended Disk Galaxy Explore Science kinematic sample. H I rotation curves are derived from new and archival radio synthesis observations from the Very Large Array (VLA) as well as processed data products from the Westerbork Radio Synthesis Telescope (WSRT). The H I rotation curves are supplemented with optical spectroscopic integral field unit (IFU) observations using SparsePak on the WIYN 3.5 m telescope to constrain the central ionized gas kinematics in 12 galaxies. The full rotation curves of each galaxy are decomposed into baryonic and dark matter halo components using 3.6μm images from the Spitzer Space Telescope for the stellar content, the neutral hydrogen data for the atomic gas component, and, when available, CO data from the literature for the molecular gas component. Differences in the inferred distribution of mass are illustrated under fixed stellar mass-to-light ratio (M/L) and maximum disc/bulge assumptions in the rotation curve decomposition.

  13. Baryonic Distributions in Galaxy Dark Matter Haloes I: New Observations of Neutral and Ionized Gas Kinematics

    NASA Astrophysics Data System (ADS)

    Richards, Emily E.; van Zee, L.; Barnes, K. L.; Staudaher, S.; Dale, D. A.; Braun, T. T.; Wavle, D. C.; Dalcanton, J. J.; Bullock, J. S.; Chandar, R.

    2016-04-01

    We present a combination of new and archival neutral hydrogen (HI) observations and new ionized gas spectroscopic observations for sixteen galaxies in the statistically representative EDGES kinematic sample. HI rotation curves are derived from new and archival radio synthesis observations from the Very Large Array (VLA) as well as processed data products from the Westerbork Radio Synthesis Telescope (WSRT). The HI rotation curves are supplemented with optical spectroscopic integral field unit (IFU) observations using SparsePak on the WIYN 3.5 m telescope to constrain the central ionized gas kinematics in twelve galaxies. The full rotation curves of each galaxy are decomposed into baryonic and dark matter halo components using 3.6μm images from the Spitzer Space Telescope for the stellar content, the neutral hydrogen data for the atomic gas component, and, when available, CO data from the literature for the molecular gas component. Differences in the inferred distribution of mass are illustrated under fixed stellar mass-to-light ratio (M/L) and maximum disc/bulge assumptions in the rotation curve decomposition.

  14. A trace gas sensor using near infrared distributed feedback laser at 1654 nm

    NASA Astrophysics Data System (ADS)

    Li, Bin; He, Qi-Xin; Liu, Hui-Fang; Wang, Yi-Ding

    2015-08-01

    A cost-effective compact instrument for high-stable and sensitive detection of methane (CH4) based on the tunable diode laser absorption spectroscopy technique was experimentally demonstrated. A distributed feedback laser modulated at 1654 nm and two InGaAs photodiodes were deployed in this instrument. The laser was driven by the self-developed temperature and current controller. Spectrum measurements show that the center wavelength of the laser is stable and linearly controlled. Meanwhile, a self-developed digital lock-in amplifier was developed for the extraction of harmonics (1f, 2f) of the gas absorption signal. Experiments of gas detection were carried out to investigate the sensor performance. Firstly, the relation between gas concentration and 1f and 2f harmonics was measured and the relation curve was plotted for calibration. Then, results of accuracy test in different concentrations show that the maximum relative detection error is less than 5.6% in the range 0%-100%. Keeping the other experimental parameters constant, gas samples of 5% concentration was detected during a period of 8 h. The maximum detection error is less than 2.8%, suggesting good detection stability. The sensor can also be applied to field measurement of other gases by adopting lasers at relative wavelength.

  15. Particle size distribution effects in an irradiated turbulent gas-particle mixture

    NASA Astrophysics Data System (ADS)

    Rahmani, Mona; Geraci, Gianluca; Iaccarino, Gianluca; Mani, Ali

    2015-11-01

    The effects of particle size distribution on thermodynamic and hydrodynamic behavior of solid particle solar receivers, that involve a turbulent mixture of gas and particles in a radiation environment, are investigated, using DNS with point particles. The turbulent flow is seeded with monodisperse and polydisperse particles, where the mass loading and total frontal area of particles are matched between the two systems. The results show that the variability of the Stokes number for polydisperse particles can significantly influence the particle clustering, and consequently the thermal performance of the system. In all cases studied, the preferential concentration is less pronounced for polydisperse as opposed to monodisperse particles. This reduced preferential concentration results in less heating of the particles, but more efficient energy release to the gas phase. Due to their different clustering patterns, polydisperse particles influence the Taylor scale of the flow in the turbulent gas phase. Polydispersity also implies variable thermodynamic and hydrodynamic properties of the particles. Our results show that the thermal behavior of the system with polydisperse particles is set by the integral measures for particle and gas momentum and thermal relaxation times.

  16. Integrated resource planning for local gas distribution companies: A critical review of regulatory policy issues

    SciTech Connect

    Harunuzzaman, M.; Islam, M.

    1994-08-01

    According to the report, public utility commissions (PUCs) are increasingly adopting, or considering the adoption of integrated resource planning (IRP) for local gas distribution companies (LDCs). The Energy Policy Act of 1992 (EPAct) requires PUCs to consider IRP for gas LDCs. This study has two major objectives: (1) to help PUCs develop appropriate regulatory approaches with regard to IRP for gas LDCs; and (2) to help PUCs respond to the EPAct directive. The study finds that it is appropriate for PUCs to pursue energy efficiency within the traditional regulatory framework of minimizing private costs of energy production and delivery; and PUCs should play a limited role in addressing environmental externalities. The study also finds that in promoting energy efficiency, PUCs should pursue policies that are incentive-based, procompetitive, and sensitive to rate impacts. The study evaluates a number of traditional and nontraditional ratemaking mechanisms on the basis of cost minimization, energy efficiency, competitiveness, and other criteria. The mechanisms evaluated include direct recovery of DSM expenses, lost revenue adjustments for DSM options, revenue decoupling mechanisms, sharing of DSM cost savings, performance-based rate of return for DSM, provision of DSM as a separate service, deregulation of DSM service, price caps, and deregulation of the noncore gas market. The study concludes with general recommendations for regulatory approaches and ratemaking mechanisms that PUCs may wish to consider in advancing IRP objectives.

  17. Comparison of Bulk and Compound-Specific Carbon Isotope Analyses and Determination of Carbon Sources to Salt Marsh Sediments Using n-Alkane Distributions (Maine, USA)

    NASA Astrophysics Data System (ADS)

    Tanner, B. R.; Uhle, M. E.; Kelley, J. T.; Mora, C. I.

    2005-12-01

    Sources of sedimentary organic matter to a Morse River, Maine (USA) salt marsh over the last 3390+/-60 RCYBP are determined using distribution patterns of n-alkanes as well as bulk and compound-specific carbon isotopic analysis. Marsh foraminiferal counts indicate the ubiquitous presence of zone 1B deposits, suggesting that the deposits were laid down ~0.2 to 0.5m above mean high water. Distributions of n-alkanes show a primary contribution from higher plants, confirmed by an average ACL value of 27.5 for the core sediments and CPI values above 3. Many sample depths have a maximum abundance at the C25 alkane. Ten low marsh, high marsh, and higher-high marsh plant species common to Maine salt marshes were sampled, including Spartina alterniflora, Spartina patens, Juncus gerardi and Solidago sempervirens. The ACL value for the average of the 10 marsh species is 29.1. Salicornia europa, usually not considered to be a dominant species in Maine marshes, has a similar n-alkane distribution to many of the salt marsh sediments, suggesting that it is an important source to the biomass of the marsh through time. Bacterial degradation or algal inputs to the marsh sediments appear to be minor. Compound specific carbon isotopic analyses of the C27 alkanes are, on average, 7.2ppt. depleted relative to bulk values, but the two records are strongly correlated (R2 = 0.87), suggesting that marsh plants are "swamping" the bulk carbon isotopic signal. The apparent abundance of a subordinate (though common) salt marsh plant species (Salicornia europa) within our core underscores the importance of using caution when applying mixing models of relatively few plant species to marsh sediments.

  18. Systematic Studies of the Gas Humidification Effects on Spatial PEMFC Performance Distributions

    SciTech Connect

    Reshetenko, T. V.; Bender, G.; Bethune, K.; Rocheleau, R.

    2012-05-01

    The overall current density that is measured in a proton exchange membrane fuel cell (PEMFC) represents the average of the local reaction rates. The overall and local PEMFC performances are determined by several primary loss mechanisms, namely activation, ohmic, and mass transfer. Spatial performance and loss variabilities are significant and depend on the cell design and operating conditions. A segmented cell system was used to quantify different loss distributions along the gas channel to understand the effects of gas humidification. A reduction in the reactant stream humidification decreased cell performance and resulted in non-uniform distributions of overpotentials and performance along the flow field. Activation and ohmic overpotentials increased with a relative humidity decrease due to insufficient membrane and catalyst layer hydration. The relative humidity of the cathode had a strong impact on the mass transfer overpotential due to a lower oxygen permeability through the dry Nafion film covering the catalyst surface. The mass transfer loss distribution was non-uniform, and the mass transfer overpotential increased for the outlet segments due to the oxygen consumption at the inlet segments, which reduced the oxygen concentration downstream, and a progressive water accumulation from upstream segments. Electrochemical impedance spectroscopy (EIS) and an equivalent electric circuit (EEC) facilitated the analysis and interpretation of the segmented cell data.

  19. Model documentation Natural Gas Transmission and Distribution Model of the National Energy Modeling System. Volume 1

    SciTech Connect

    1996-02-26

    The Natural Gas Transmission and Distribution Model (NGTDM) of the National Energy Modeling System is developed and maintained by the Energy Information Administration (EIA), Office of Integrated Analysis and Forecasting. This report documents the archived version of the NGTDM that was used to produce the natural gas forecasts presented in the Annual Energy Outlook 1996, (DOE/EIA-0383(96)). The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic approach, and provides detail on the methodology employed. Previously this report represented Volume I of a two-volume set. Volume II reported on model performance, detailing convergence criteria and properties, results of sensitivity testing, comparison of model outputs with the literature and/or other model results, and major unresolved issues.

  20. Bypass of local gas distribution utilities - how can you tell if it is for real

    SciTech Connect

    Kaufman, A.

    1986-08-01

    Natural gas pipelines connecting the deregulated producers and the fully regulated gas distributors had been free to offer various incentives to selected customers in order to compete with alternative fuels. A court finding in 1985 that Order 234-B of the Special Marketing Programs (SMPs) was unduly discriminatory led to Order 436 of the Federal Energy Regulatory Commission (FERC) and its amendments to discontinue SMPs for low priority users, but with high priority users grandfathered. The order is designed to open the industry to competition within itself, but only a few pipelines elected to come under its provisions. Despite the lack of interest, competition within the industry is expanding. Utilities are concerned that large users will leave the distribution system, leaving remaining customers to pay a larger share of fixed costs. Regulators may provide an incentive for customers to stay in the system if they pass screening criteria. 2 tables.

  1. Distribution patterns of water-dissolved gases in oil-gas-bearing sediments

    SciTech Connect

    Panchenko, A.S.

    1982-07-01

    The prospecting significance of water-dissolved gases is dependent on processes of diffusion in the pool-water system, as a result of which gas halos (methane, ethane, propane, butane, pentane, CO/sub 2/, N/sub 2/, H/sub 2/S, He, Ar) are formed around the hydrocarbon accumulations. In the study presented, the authors identify a pattern previously unknown in the distribution of water-dissolved gases accompanying hydrocarbon pools. In this pattern, the concentration and partial pressure of the gaseous hydrocarbons in the water may increase, or at first decrease and then increase. The presence of such gas halos around pools is explained by the peculiarities of formation of hydrocarbon deposits, and should be considered when prospecting for hydrocarbon deposits. (JMT)

  2. Star forming regions towards Gum 31: distribution of the molecular gas

    NASA Astrophysics Data System (ADS)

    Vazzano, M. M.; Cappa, C. E.; Vasquez, J.; Rubio, M.

    2015-08-01

    We analyze the distribution of the molecular gas associated with IRAS and 2MASS sources, young stellar objects linked to the Hii region Gum31. We based our studies on observations obtained with the APEX telescope, located in the north of Chile. We used observations of different CO isotopologues, CS(7-6) and HCO(4-3) lines. The sources are located on the edge of the Gum31 Hii region, whose shock front substantially affects the morphology of their molecular environs. The observations revealed that in the surroundings of the sources there is molecular gas associated with the nebula, which is shown by the CO(3-2) emission, with small high density clumps detected in CO(3-2).

  3. Investigation of the causes for the measurement differences between the natural gas measurement systems of a gas distribution company and of a consumer

    NASA Astrophysics Data System (ADS)

    Kawakita, Kazuto; Silva Telles, Rubens

    2015-10-01

    This paper presents the methodology used, the checked items and the results obtained in an investigation carried out to identify the causes that generated substantial differences between the natural gas volumes measured by two measuring systems, one from a gas distribution company and another from its industrial consumer, both installed in series in a gas pipeline. The investigation showed that the measurement of the volume of gas performed by the gas distributor metering system was influenced by an erroneous measurement of the gas temperature since it was affected by a complex thermodynamic process involving cooling by the Joule-Thomson effect caused by a pressure reducing valve and heating by heat exchange through the pipe walls.

  4. THE SMOOTH Mg II GAS DISTRIBUTION THROUGH THE INTERSTELLAR/EXTRA-PLANAR/HALO INTERFACE

    SciTech Connect

    Kacprzak, Glenn G.; Cooke, Jeff; Ryan-Weber, Emma V.; Churchill, Christopher W.; Nielsen, Nikole M.

    2013-11-01

    We report the first measurements of Mg II absorption systems associated with spectroscopically confirmed z ∼ 0.1 star-forming galaxies at projected distances of D < 6 kpc. We demonstrate that the data are consistent with the well-known anti-correlation between rest-frame Mg II equivalent width, W{sub r} (2796), and impact parameter, D, represented by a single log-linear relation derived by Nielsen et al. (MAGIICAT) that converges to ∼2 Å at D = 0 kpc. Incorporating MAGIICAT, we find that the halo gas covering fraction is unity below D ∼ 25 kpc. We also report that our D < 6 kpc absorbers are consistent with the W{sub r} (2796) distributions of the Milky Way interstellar medium (ISM) and ISM+halo. In addition, quasar sight lines of intermediate redshift galaxies with 6 < D < 25 kpc have an equivalent width distribution similar to that of the Milky Way halo, implying that beyond ∼6 kpc, quasar sight lines are likely probing halo gas and not the ISM. As inferred by the Milky Way and our new data, the gas profiles of galaxies can be fit by a single log-linear W{sub r} (2796)-D relation out to large scales across a variety of gas-phase conditions and is maintained through the halo/extra-planar/ISM interfaces, which is remarkable considering their kinematic complexity. These low-redshift, small impact parameter absorption systems are the first steps to bridge the gap between quasar absorption-line studies and H I observations of the circumgalactic medium.

  5. The Distribution and Kinematics of Cold Near-Nuclear Gas in AGN

    NASA Astrophysics Data System (ADS)

    Gallimore, J.

    1993-12-01

    The kinematics and distribution of near nuclear cold gas in AGN is essentially unknown, in large part because the low emissivity of this gas precludes direct measurement. We have initiated a program to determine the kinematics and spatial distribution of cold nuclear gas in AGN using the technique of synthesis mapping of HI (and OH) in absorption against a spatially resolved radio continuum source. These measurements will allow us to address a number of key astrophysical questions; (1) What are the masses of the `central engines' in Seyfert galaxies, (2) Is there evidence for infalling neutral matter which could fuel the activity and if so, can we trace that inflow from the hundreds of parsec scale inward?, (3) How is the pc scale ionised and neutral gas related in Seyferts?, (4) Can we find evidence for `tori' of cold obscuring matter in Seyfert 2s, as predicted by the unified schemes? We have recently completed HI VLA A array absorption studies of 12 Seyfert galaxies. We have obtained followup Merlin observations for NGC 1068 and NGC 3079. In NGC 1068 we have determined unambiguously the orientation of the linear radio structure; namely the NE lobe is pointed towards us. We have found supportive evidence for an AGN-driven outflow at the SW jet. We also find a kinematic disturbance and optical depth enhancement in the HI in the inner disk which suggests we are witnessing a bar-driven shock. In NGC 3079, the absorption profile is too broad to be explained by disk gas but must instead arise primarily in rapidly moving clouds located near the radio source. Slightly resolved, blue and redshifted absorption lines may be due to a ring of cold gas with a radius of ~ 90 parsecs. The mass interior to this postulated ring is >10(8) solar masses, implying an extremely dense stellar core or a compact central object. We report here on the preliminary results for the sample as a whole, and on the more detailed results for NGC3079 and NGC 1068.

  6. On the work distribution for the adiabatic compression of a diluteclassical gas

    SciTech Connect

    Crooks, Gavin E.; Jarzynski, Christopher

    2006-02-23

    We consider the adiabatic and quasi-static compression of adilute classical gas, confined in a piston and initially equilibratedwith a heat bath. We find that the work performed during this process isdescribed statistically by a gamma distribution. We use this result toshow that the model satisfies the non-equilibrium work and fluctuationtheorems, but not the fluctation-dissipation relation. We discuss therare but dominant realizations that contribute most to the exponentialaverage of the work, and relate our results to potentially universal workdistributions.

  7. Two-Dimensional Plasma Density Distributions in Low-Pressure Gas Discharges

    SciTech Connect

    Berlin, E.V.; Dvinin, S.A.; Mikheev, V.V.; Omarov, M.O.; Sviridkina, V. S.

    2004-12-15

    The plasma density distribution in a two-dimensional nonuniform positive column of a low-pressure gas discharge is studied in the hydrodynamic approximation with allowance for ion inertia. Exact solutions are derived for discharges in a rectangular and a cylindrical chamber. Asymptotic solutions near the coordinate origin and near the critical surface are considered. It is shown that, for potential plasma flows, the flow velocity component normal to the plasma boundary is equal to the ion acoustic velocity. The results obtained can be used to analyze the processes occurring in low-pressure plasmochemical reactors.

  8. MAINE POPULATION

    EPA Science Inventory

    MEPOP250 depicts Maine's 1950-1990 population data by town or Census in unorganized territories. Populations were compiled from US Census Bureau data where available or from Maine Municipal Information (mainly for older records). Unorganized towns with very low or zero pop...

  9. PAH assessment in the main Brazilian offshore oil and gas production area using semi-permeable membrane devices (SPMD) and transplanted bivalves

    NASA Astrophysics Data System (ADS)

    André Lourenço, Rafael; Francisco de Oliveira, Fábio; Haddad Nudi, Adriana; Rebello Wagener, Ângela de Luca; Guadalupe Meniconi, Maria de Fátima; Francioni, Eleine

    2015-06-01

    The Campos Basin is Brazil's main oil and gas production area. In 2013, more than 50 million cubic meters of produced water (PW) was discharged into these offshore waters. Despite the large volumes of PW that are discharged in the Campos Basin each day, the ecological concern of the chemicals in the PW are not completely understood. Polycyclic aromatic hydrocarbons (PAH) are the most important contributors to the ecological hazards that are posed by discharged PW. This study aimed to evaluate the potential bioaccumulation of PAH using transplanted bivalves (Nodipecten nodosus) and semi-permeable membrane devices (SPMD). The study was conducted in two platforms that discharge PW (P19 and P40). Another platform that does not discharge PW (P25) was investigated for comparison with the obtained results. Time-integrated hydrocarbon concentrations using SPMD and transplanted bivalves were estimated from the seawater near the three platforms. The bioaccumulation of the PAH in the transplanted bivalves at platforms P19 and P40 were up to fivefold greater than the bioaccumulation of the PAH at platform P25. The lowest PAH concentrations were estimated for platform P25 (4.3-6.2 ng L-1), and the highest PAH concentrations were estimated for platform P19 (9.2-37.3 ng L-1). Both techniques were effective for determining the bioavailability of the PAH and for providing time-integrated hydrocarbon concentrations regarding oil and gas production activities.

  10. Measurements of radon flux and soil-gas radon concentration along the Main Central Thrust, Garhwal Himalaya, using SRM and RAD7 detectors

    NASA Astrophysics Data System (ADS)

    Bourai, Abhay; Aswal, Sunita; Dangwal, Anoop; Rawat, Mukesh; Prasad, Mukesh; Naithani, Nagendra; Joshi, Veena; Ramola, Rakesh

    2013-08-01

    Radon in the Earth's crust or soil matrix is free to move only if its atoms find their way into pores or capillaries of the matrix. 222Rn atoms from solid mineral grains get into air, filling pores through emanation process. Then 222Rn enters into the atmosphere from air-filled pores by exhalation process. The estimation of radon flux from soil surface is an important parameter for determining the source term for radon concentration modeling. In the present investigation, radon fluxes and soil-gas radon concentration have been measured along and around the Main Central Thrust (MCT) in Uttarkashi district of Garhwal Himalaya, India, by using Scintillation Radon Monitor (SRM) and RAD7 devices, respectively. The soil radon gas concentration measured by RAD7 with soil probe at the constant depth was found to vary from 12 ± 3 to 2330 ± 48 Bq·m-3 with geometrical mean value of 302 ± 84 Bq·m-3. Th significance of this work is its usefulness from radiation protection point of view.

  11. YORP and collisional shaping of the sub-populations, rotation rate and size-frequency distributions in the main-belt

    NASA Astrophysics Data System (ADS)

    Rossi, A.; Marzari, F.; Scheeres, D.; Jacobson, S.; Davis, D.

    In the last several years a comprehensive asteroid-population-evolution model was developed incorporating both the YORP effect and collisional evolution \\citep{rossi_2009}, \\citep{marz_2011}, \\citep{jac_mnras}. From the results of this model we were able to match the observed main belt rotation rate distribution and to give a first plausible explanation of the observed excess of slow rotators, through a random walk-like evolution of the spin, induced by repeated collisions with small projectiles. Moreover, adding to the model the rotational fission hypothesis (i.e. when the rotation rate exceeds a critical value, erosion and binary formation occur; \\citealt{sch_2007}) and binary-asteroid evolution \\citep{jac_sch}, we first showed that the YORP-induced rotational-fission hypothesis has strong repercussions for the small size end of the main-belt asteroid size-frequency distribution. We also concluded that this hypothesis is consistent with observed asteroid-population statistics and with the observed sub-populations of binary asteroids, asteroid pairs and contact binaries. An overview of the results obtained, the modelling uncertainties and the ongoing work will be given.

  12. A Robust Distributed Multipoint Fiber Optic Gas Sensor System Based on AGC Amplifier Structure.

    PubMed

    Zhu, Cunguang; Wang, Rende; Tao, Xuechen; Wang, Guangwei; Wang, Pengpeng

    2016-01-01

    A harsh environment-oriented distributed multipoint fiber optic gas sensor system realized by automatic gain control (AGC) technology is proposed. To improve the photoelectric signal reliability, the electronic variable gain can be modified in real time by an AGC closed-loop feedback structure to compensate for optical transmission loss which is caused by the fiber bend loss or other reasons. The deviation of the system based on AGC structure is below 4.02% when photoelectric signal decays due to fiber bending loss for bending radius of 5 mm, which is 20 times lower than the ordinary differential system. In addition, the AGC circuit with the same electric parameters can keep the baseline intensity of signals in different channels of the distributed multipoint sensor system at the same level. This avoids repetitive calibrations and streamlines the installation process. PMID:27483267

  13. Effects of temperature distribution and elastic properties of materials on gas-turbine-disk stresses

    NASA Technical Reports Server (NTRS)

    Holms, Arthur G; Faldetta, Richard D

    1947-01-01

    Calculations were made to determine the influence of changes in temperature distribution and in elastic material properties on calculated elastic stresses for a typical gas-turbine disk. Severe temperature gradients caused thermal stresses of sufficient magnitude to reduce the operating safety of the disk. Small temperature gradients were found to be desirable because they produced thermal stresses that subtracted from the centrifugal stresses in the region of the rim. The thermal gradients produced a tendency for a severe stress condition to exist near the rim but this stress condition could be shifted away from the region of blade attachment by altering the temperature distribution. The investigation of elastic material properties showed that centrifugal stresses are slightly affected by changes in modulus of elasticity, but that thermal stresses are approximately proportional to modulus of elasticity and to coefficient of thermal expansion.

  14. Net-baryon number fluctuations with the hadron resonance gas model using Tsallis distribution

    NASA Astrophysics Data System (ADS)

    Mishra, D. K.; Garg, P.; Netrakanti, P. K.; Mohanty, A. K.

    2015-10-01

    We explore a hadron resonance gas (HRG) model using the Tsallis non-extensive distribution to study the energy dependence of the product of the moments, Sσ and κ {σ }2 of the net-proton multiplicity distributions of published STAR data for Au+Au collisions at Relativistic Heavy-Ion Collider energies. While excellent agreement was found between model predictions and measurements of Sσ and κ {σ }2 of most peripheral collisions and Sσ of most central collisions, the κ {σ }2 for most central collisions deviates significantly from the predictions particularly at \\sqrt{{s}{{NN}}} = 19.6 GeV and 27 GeV. This could be an indication of the presence of dynamical fluctuations, which are not contained in the HRG-Tsallis model.

  15. Across-shelf distribution of blue mussel larvae in the northern Gulf of Maine: consequences for population connectivity and a species range boundary.

    PubMed

    Yund, Philip O; Tilburg, Charles E; McCartney, Michael A

    2015-12-01

    Studies of population connectivity have largely focused on along-shelf, as opposed to across-shelf, processes. We hypothesized that a discontinuity in across-shelf mixing caused by the divergence of the Eastern Maine Coastal Current (EMCC) from shore acts as an ecological barrier to the supply of mussel larvae to the coast. Existing data on the relative abundance of two congeneric blue mussels, Mytilus edulis and M. trossulus, were analysed to quantify the association of M. trossulus with the colder temperature signal of the EMCC and generate larval distribution predictions. We then sampled the across-shelf distribution of larvae along two transects during 2011. Larvae were identified using restriction digests of PCR amplicons from the mitochondrial 16S rDNA. Mytilus edulis larvae were consistently abundant on either the inshore and offshore transect ends, but not homogeneously distributed across the shelf, while M. trossulus larvae were less common throughout the study area. The divergence of the EMCC from shore appears to create a break in the connectivity of M. edulis populations by isolating those inshore of the EMCC from upstream larval sources. Across-shelf transport processes can thus produce connectivity patterns that would not be predicted solely on the basis of along-shelf processes. PMID:27018654

  16. Across-shelf distribution of blue mussel larvae in the northern Gulf of Maine: consequences for population connectivity and a species range boundary

    PubMed Central

    Yund, Philip O.; Tilburg, Charles E.; McCartney, Michael A.

    2015-01-01

    Studies of population connectivity have largely focused on along-shelf, as opposed to across-shelf, processes. We hypothesized that a discontinuity in across-shelf mixing caused by the divergence of the Eastern Maine Coastal Current (EMCC) from shore acts as an ecological barrier to the supply of mussel larvae to the coast. Existing data on the relative abundance of two congeneric blue mussels, Mytilus edulis and M. trossulus, were analysed to quantify the association of M. trossulus with the colder temperature signal of the EMCC and generate larval distribution predictions. We then sampled the across-shelf distribution of larvae along two transects during 2011. Larvae were identified using restriction digests of PCR amplicons from the mitochondrial 16S rDNA. Mytilus edulis larvae were consistently abundant on either the inshore and offshore transect ends, but not homogeneously distributed across the shelf, while M. trossulus larvae were less common throughout the study area. The divergence of the EMCC from shore appears to create a break in the connectivity of M. edulis populations by isolating those inshore of the EMCC from upstream larval sources. Across-shelf transport processes can thus produce connectivity patterns that would not be predicted solely on the basis of along-shelf processes. PMID:27018654

  17. Methodology to model the energy and greenhouse gas emissions of electronic software distributions.

    PubMed

    Williams, Daniel R; Tang, Yinshan

    2012-01-17

    A new electronic software distribution (ESD) life cycle analysis (LCA) methodology and model structure were constructed to calculate energy consumption and greenhouse gas (GHG) emissions. In order to counteract the use of high level, top-down modeling efforts, and to increase result accuracy, a focus upon device details and data routes was taken. In order to compare ESD to a relevant physical distribution alternative, physical model boundaries and variables were described. The methodology was compiled from the analysis and operational data of a major online store which provides ESD and physical distribution options. The ESD method included the calculation of power consumption of data center server and networking devices. An in-depth method to calculate server efficiency and utilization was also included to account for virtualization and server efficiency features. Internet transfer power consumption was analyzed taking into account the number of data hops and networking devices used. The power consumed by online browsing and downloading was also factored into the model. The embedded CO(2)e of server and networking devices was proportioned to each ESD process. Three U.K.-based ESD scenarios were analyzed using the model which revealed potential CO(2)e savings of 83% when ESD was used over physical distribution. Results also highlighted the importance of server efficiency and utilization methods. PMID:22107078

  18. The nature, distribution, and origin of gas hydrate in the Chile Triple Junction region

    USGS Publications Warehouse

    Brown, K.M.; Bangs, N.L.; Froelich, P.N.; Kvenvolden, K.A.

    1996-01-01

    A bottom simulating reflector (BSR) is regionally distributed throughout much of the Chile Triple Junction (CTJ) region. Downhole temperature and logging data collected during Ocean Drilling Program (ODP) Leg 141 suggest that the seismic BSR is generated by low seismic velocities associated with the presence of a few percent free gas in a ??? 10 m thick zone just beneath the hydrate-bearing zone. The data also indicate that the temperature and pressure at the BSR best corresponds to the seawater/methane hydrate stability field. The origin of the large amounts of methane required to generate the hydrates is, however, problematic. Low total organic carbon contents and low alkalinities argue against significant in situ biogenic methanogenesis, but additional input from thermogenic sources also appears to be precluded. Increasing thermal gradients, associated with the approach of the spreading ridge system, may have caused the base of the hydrate stability field to migrate 300 m upwards in the sediments. We propose that the upward migration of the base of the stability field has concentrated originally widely dispersed hydrate patches into the more continuous hydrate body we see today. The methane can be concentrated if the gas hydrates can form from dissolved methane, transported into the hydrate zone via diffusion or fluid advection. A strong gradient may exist in dissolved methane concentration across the BSR leading to the steady reabsorbtion of the free gas zone during the upward migration of the BSR even in the absence of fluid advection.

  19. Review of performance-based ratemaking plans for US gas distribution companies

    SciTech Connect

    Comnes, G.A.

    1994-11-01

    Performance-Based Ratemaking (PBR) is receiving increasing attention by energy utilities and their regulators. PBR is the industry term for forms of regulation that increase financial incentive for performance relative to traditional cost-of-service/rate-of-return (COS/ROR) regulation. In this report, PBR plans filed by US gas local distribution companies (LDCs) are described and reviewed. The rationale behind energy utility PBR is presented and discussed. Using nine plans that have been proposed by eight LDCs as a basis, a framework (typology) to facilitate understanding of gas utility PBR is presented. Plans are categorized according to the range of services covered by the PBR mechanism and the scope of the mechanism`s cost coverage within a service category. Pivotal design issues are identified and, based on the sample of plans, observations are made. Design issues covered include the length of time that the PBR is in effect (term); the relationship between PBR plans and status quo ratemaking; methods for formulating cost or rate indices, earnings sharing mechanisms, and service quality indices; and compatibility with gas utility DSM programs. The report summarizes observations that may be considered supportive of the rationale behind PBR. PBR is, however, not clearly superior to traditional regulation and few PBRs that are broad in scope have been adopted long enough to allow for a empirical analysis. Thus, the report concludes by identifying and describing commonly-cited pitfalls of PBR.

  20. Analysis of the spatial distribution of stars, gas and dust in nearby galaxies

    NASA Astrophysics Data System (ADS)

    Muñoz-Mateos, J. C.

    2013-05-01

    I summarize the main result of my thesis, which was awarded the Spanish Astronomical Society Award for the best thesis in Astronomy defended in 2010. This thesis was supervised by Armando Gil de Paz and Jaime Zamorano at Universidad Complutense de Madrid. In this work we quantified how the physical properties of stars, gas and dust vary with radius in nearby galactic disks, and used that information to infer the past assembly and evolution of galaxies. To do so we made use of spatially-resolved multi-wavelength images of nearby galaxies, all the way from the far-UV to the far-IR and radio. By comparing extinction- corrected profiles in the UV, optical and IR with models of disk evolution, we concluded that the current stellar population gradients are consistent with an inside-out growth of disks of ˜ 25% since z ˜ 1. We also found that the dust-to-gas ratio decreases with radius, and is tightly correlated with the local gas metallicity, which is again consistent with an inside-out assembly of disks. We measured the fraction of the dust mass which is in the form of PAHs at different radii. The resulting trend agrees with certain models of dust evolution, in which the abundance of PAHs is primarily determined by a delayed injection of carbon into the ISM by AGB stars.

  1. Performance of MEMS-based gas distribution and control systems for semiconductor processing

    NASA Astrophysics Data System (ADS)

    Henning, Albert K.; Fitch, John; Harris, James M.; Arkilic, Errol B.; Cozad, Brad A.; Dehan, Ben

    1998-09-01

    The advent of microelectromechanical systems has enabled dramatic changes in diverse technological areas. In terms of control and distribution of liquids and gases (microfluidics), MEMS-based devices offer opportunities to achieve increased performance, and higher levels of functional integration, at lower cost, with decreased size and increased reliability. This work focuses on recent research and development of high-purity gags distribution and control systems for semiconductor processing. These systems include the following components, based upon both normally-open and normally-closed microvalves: pressure- based mass flow controllers; vacuum leak-rate shut-off valves; and pressure regulators. Advanced packaging techniques enable these components to be integrated into gas sticks and panels which have small size, corrosion-resistant wetted materials, small dead volumes, and minimal particle generation. Principles of operation of components and panels, and performance data at both the component and system level, will be presented. The potential for 10X size reduction (linear dimension), 2X product yield improvement (through increased reliability, improved flow accuracy and repeatability, and contamination reduction), and 5X reduction in process gas consumption, will also be addressed. Particular emphasis on characterization and verification of flow measurements in mass flow controllers (versus NIST standards), and the flow models used in designing and characterizing these systems, will be made.

  2. Preliminary design concepts for an advanced gas distribution system. Task report, August 1989-August 1990

    SciTech Connect

    Lipinsky, E.S.; Hattery, G.R.; Newaz, G.

    1991-01-01

    Studies that were conducted in 1989 (GRI-89/0107.2) showed that the major problems that face the industry are third-party damage, locatability, and pipe supportability. These needs were translated into performance criteria for materials and designs of gas distribution system components. In Phase 2 to date, the performance criteria were refined and used as the basis for generation of concepts for materials and designs for enhancement of the gas distribution system. The screening criteria include long service life, damage tolerance, installation, and manufacturability. A scoring model that allows the criteria to have variable weights was applied to attain normalized scores and rankings for the concepts. The leading concepts include puncture-resistant polyethylene pipe via wrapping with an ultrahigh molecular weight polyethylene fabric or fiber, toughened thermoplastics (especially polyamides or acetal resin or polyester), thermoplastic fiber-reinforced thermoplastic resins, fiberglass-reinforced hose designs, and honeycomb-reinforced thermoplastic elastomer designs. Tentative research and development plans were developed for the leading concepts in which simple tests of manufacturability, impact resistance, and joinability are to be used to determine which concepts should be pursued further and which appear to have serious flaws.

  3. Toward Measuring Galactic Dense Molecular Gas Properties and 3D Distribution with Hi-GAL

    NASA Astrophysics Data System (ADS)

    Zetterlund, Erika; Glenn, Jason; Maloney, Phil

    2016-01-01

    The Herschel Space Observatory's submillimeter dust continuum survey Hi-GAL provides a powerful new dataset for characterizing the structure of the dense interstellar medium of the Milky Way. Hi-GAL observed a 2° wide strip covering the entire 360° of the Galactic plane in broad bands centered at 70, 160, 250, 350, and 500 μm, with angular resolution ranging from 10 to 40 arcseconds. We are adapting a molecular cloud clump-finding algorithm and a distance probability density function distance-determination method developed for the Bolocam Galactic Plane Survey (BGPS) to the Hi-GAL data. Using these methods we expect to generate a database of 105 cloud clumps, derive distance information for roughly half the clumps, and derive precise distances for approximately 20% of them. With five-color photometry and distances, we will measure the cloud clump properties, such as luminosities, physical sizes, and masses, and construct a three-dimensional map of the Milky Way's dense molecular gas distribution.The cloud clump properties and the dense gas distribution will provide critical ground truths for comparison to theoretical models of molecular cloud structure formation and galaxy evolution models that seek to emulate spiral galaxies. For example, such models cannot resolve star formation and use prescriptive recipes, such as converting a fixed fraction of interstellar gas to stars at a specified interstellar medium density threshold. The models should be compared to observed dense molecular gas properties and galactic distributions.As a pilot survey to refine the clump-finding and distance measurement algorithms developed for BGPS, we have identified molecular cloud clumps in six 2° × 2° patches of the Galactic plane, including one in the inner Galaxy along the line of sight through the Molecular Ring and the termination of the Galactic bar and one toward the outer Galaxy. Distances have been derived for the inner Galaxy clumps and compared to Bolocam Galactic Plane

  4. Characterization of gas hydrate distribution using conventional 3D seismic data in the Pearl River Mouth Basin, South China Sea

    USGS Publications Warehouse

    Wang, Xiujuan; Qiang, Jin; Collett, Timothy S.; Shi, Hesheng; Yang, Shengxiong; Yan, Chengzhi; Li, Yuanping; Wang, Zhenzhen; Chen, Duanxin

    2016-01-01

    A new 3D seismic reflection data volume acquired in 2012 has allowed for the detailed mapping and characterization of gas hydrate distribution in the Pearl River Mouth Basin in the South China Sea. Previous studies of core and logging data showed that gas hydrate occurrence at high concentrations is controlled by the presence of relatively coarse-grained sediment and the upward migration of thermogenic gas from the deeper sediment section into the overlying gas hydrate stability zone (BGHSZ); however, the spatial distribution of the gas hydrate remains poorly defined. We used a constrained sparse spike inversion technique to generate acoustic-impedance images of the hydrate-bearing sedimentary section from the newly acquired 3D seismic data volume. High-amplitude reflections just above the bottom-simulating reflectors (BSRs) were interpreted to be associated with the accumulation of gas hydrate with elevated saturations. Enhanced seismic reflections below the BSRs were interpreted to indicate the presence of free gas. The base of the BGHSZ was established using the occurrence of BSRs. In areas absent of well-developed BSRs, the BGHSZ was calculated from a model using the inverted P-wave velocity and subsurface temperature data. Seismic attributes were also extracted along the BGHSZ that indicate variations reservoir properties and inferred hydrocarbon accumulations at each site. Gas hydrate saturations estimated from the inversion of acoustic impedance of conventional 3D seismic data, along with well-log-derived rock-physics models were also used to estimate gas hydrate saturations. Our analysis determined that the gas hydrate petroleum system varies significantly across the Pearl River Mouth Basin and that variability in sedimentary properties as a product of depositional processes and the upward migration of gas from deeper thermogenic sources control the distribution of gas hydrates in this basin.

  5. Model documentation: Natural Gas Transmission and Distribution Model of the National Energy Modeling System; Volume 1

    SciTech Connect

    1994-02-24

    The Natural Gas Transmission and Distribution Model (NGTDM) is a component of the National Energy Modeling System (NEMS) used to represent the domestic natural gas transmission and distribution system. NEMS is the third in a series of computer-based, midterm energy modeling systems used since 1974 by the Energy Information Administration (EIA) and its predecessor, the Federal Energy Administration, to analyze domestic energy-economy markets and develop projections. This report documents the archived version of NGTDM that was used to produce the natural gas forecasts used in support of the Annual Energy Outlook 1994, DOE/EIA-0383(94). The purpose of this report is to provide a reference document for model analysts, users, and the public that defines the objectives of the model, describes its basic design, provides detail on the methodology employed, and describes the model inputs, outputs, and key assumptions. It is intended to fulfill the legal obligation of the EIA to provide adequate documentation in support of its models (Public Law 94-385, Section 57.b.2). This report represents Volume 1 of a two-volume set. (Volume 2 will report on model performance, detailing convergence criteria and properties, results of sensitivity testing, comparison of model outputs with the literature and/or other model results, and major unresolved issues.) Subsequent chapters of this report provide: (1) an overview of the NGTDM (Chapter 2); (2) a description of the interface between the National Energy Modeling System (NEMS) and the NGTDM (Chapter 3); (3) an overview of the solution methodology of the NGTDM (Chapter 4); (4) the solution methodology for the Annual Flow Module (Chapter 5); (5) the solution methodology for the Distributor Tariff Module (Chapter 6); (6) the solution methodology for the Capacity Expansion Module (Chapter 7); (7) the solution methodology for the Pipeline Tariff Module (Chapter 8); and (8) a description of model assumptions, inputs, and outputs (Chapter 9).

  6. Study on two-dimensional tomography algorithm for gas temperature distribution based on TDLAS

    NASA Astrophysics Data System (ADS)

    Lv, Jinwei; Zhou, Tao; Yao, Hongbao

    2013-09-01

    In the combustion flow field, the concentrations of temperature and water vapor are very important in determining combustion efficiency. The traditional contact measurement will induce shock so as to disturb the flow field, and most of the probe can't be used in the high temperature air. So the existing contact measurement method can't meet the measurement requirements of the combustion field, but the tunable laser absorption spectrum technology (TDLAS) can realize non-contact nondestructive measurement of the combustion flow field. Various parameters such as temperature, gas composition and concentration, flow velocity, can be measured at the same time. And there is no temperature limit. It is very good at measuring combustion field parameters in the high temperature and high speed environment. TDLAS can calculate the gas temperature in real-time by scanning both absorption signal of gas absorption lines, but this is one-dimensional path integral measurement, can't reflect the real information of the combustion field. So it can't be used to measure objects with distinct temperature gradient. In order to overcome this deficiency, tunable laser absorption spectrum technology combined with computer tomography technology (called TDLAT) is used to realize the measurement of the two dimensional temperature distribution in the burning flow field. In this paper, the measurement principle and algorithm of the two dimensional temperature field distribution are put forward. In TDLAT system, the measured area is divided into many grids. TDLAS is used to get the laser path integral spectrophotometry along the grid line. In succession, deeply grid information is gotten by non-negative constrained least squares. Thus, assuming that temperature measurement plane within is in smooth transition, interpolation algorithm is used to recreate the high spatial resolution of the two dimensional temperature field distribution. According to the measuring principle and measuring objects

  7. Impact of Intrafractional Bowel Gas Movement on Carbon Ion Beam Dose Distribution in Pancreatic Radiotherapy

    SciTech Connect

    Kumagai, Motoki; Hara, Ryusuke; Mori, Shinichiro Yanagi, Takeshi; Asakura, Hiroshi; Kishimoto, Riwa; Kato, Hirotoshi; Yamada, Shigeru; Kandatsu, Susumu; Kamada, Tadashi

    2009-03-15

    Purpose: To assess carbon ion beam dose variation due to bowel gas movement in pancreatic radiotherapy. Methods and Materials: Ten pancreatic cancer inpatients were subject to diagnostic contrast-enhanced dynamic helical CT examination under breath-holding conditions, which included multiple-phase dynamic CT with arterial, venous, and delayed phases. The arterial-venous phase and arterial-delayed phase intervals were 35 and 145 s, respectively. A compensating bolus was designed to cover the target obtained at the arterial phase. Carbon ion dose distribution was calculated by applying the bolus to the CT data sets at the other two phases. Results: Dose conformation to the clinical target volume was degraded by beam overshoot/undershoot due to bowel gas movement. The D95 for clinical target volume was degraded from 98.2% (range, 98.0-99.1%) of the prescribed dose to 94.7% (range, 88.0-99.0%) at 145 s. Excessive dosing to normal tissues varied among tissues and was, for example, 12.2 GyE/13.1 GyE (0 s/145 s) for the cord and 38.8 GyE/39.8 GyE (0 s/145 s) for the duodenum. The magnitude of beam overshoot/undershoot was particularly exacerbated from the anterior and left directions. Conclusions: Bowel gas movement causes dosimetric variation to the target during treatment for radiotherapy. The effect of bowel gas movement varies with beam angle, with greatest influence on the anterior-posterior and left-right beams.

  8. MAINE AQUIFERS

    EPA Science Inventory

    AQFRS24 contains polygons of significant aquifers in Maine (glacial deposits that are a significant ground water resource) mapped at a scale 1:24,000. This statewide coverage was derived from aquifer boundaries delineated and digitized by the Maine Geological Survey from data com...

  9. FCC main fractionator revamps

    SciTech Connect

    Golden, S.W.; Martin, G.R.; Sloley, A.W. )

    1993-03-01

    Structured packing use in fluid catalytic cracker (FCC) main fractionators significantly impacts unit pressure profile. Unit pressure balance links the FCC main fractionator, reactor, regenerator, air compressor and wet gas compressor. Unit pressure balance should be viewed as a design variable when evaluating FCC unit revamps. Depending upon limitations of the particular FCC unit, capacity increases of 12.5% to 22.5% have been achieved without modifications to major rotating equipment, by revamping FCC main fractionators with structured packing. An examination of three FCC main fractionator revamps show improvements to pressure profiles and unit capacity. The three revamps described included a wet gas compressor volume limit; an air blower limitation; and a wet gas compressor motor limitation.

  10. Space Transportation Main Engine

    NASA Technical Reports Server (NTRS)

    Monk, Jan C.

    1992-01-01

    The topics are presented in viewgraph form and include the following: Space Transportation Main Engine (STME) definition, design philosophy, robust design, maximum design condition, casting vs. machined and welded forgings, operability considerations, high reliability design philosophy, engine reliability enhancement, low cost design philosophy, engine systems requirements, STME schematic, fuel turbopump, liquid oxygen turbopump, main injector, and gas generator. The major engine components of the STME and the Space Shuttle Main Engine are compared.

  11. Determination of main and minor components of silicon based materials by a combustion with elemental fluorine. Separation of gaseous fluorination products by carrier gas distillation and gas mass spectrometry

    PubMed

    Russe; Kipphardt; Broekaert

    2000-08-15

    For the determination of main and minor components in silicon-based ceramic powders, a decomposition by a combustion with elemental fluorine and separation of the volatile fluorination products by a carrier-gas distillation with a subsequent detection by quadrupole mass spectrometry is described. The necessity and success of the separation step is demonstrated for the determination of boron as a minor constituent in SiC, where the spectral interferences of silicon on the boron signals are decreased considerably. The method developed is shown to be directly applicable to determination of silicon in Si3N4, SiC, and SiO2. The determination of nitrogen in Si3N4 requires additional effort, to separate nitrogen from the excess of fluorine. For the determination of boron, a complete mobilization of BF3 is assured by the presence of an adequate amount of GeF4. Analysis results obtained with different types of calibration show a precision of 30 microg for boron at the milligram-per-gram level and a precision between 0.5 and 2% (m/m) for the main components, silicon and nitrogen. Within these standard deviations, the results agree well with the values expected from the stoichiometry, with the results for silicon and boron obtained by wet chemical decomposition and slurry techniques in combination with ICP-OES and with the results for nitrogen obtained by carrier gas heat extraction. PMID:10959976

  12. The velocity distribution of interstellar gas observed in strong UV absorption lines

    NASA Technical Reports Server (NTRS)

    Cowie, L. L.; York, D. G.

    1978-01-01

    Observations of three strong interstellar UV absorption lines of N I (1199 A), N II (1083 A), and Si III (1206 A) in 47 stars of widely varying distance and a variety of spectral types are analyzed to obtain a velocity distribution function for the interstellar gas. A technique based on the maximum and minimum velocities observed along a line of sight is adopted because of heavy line blending, and results are discussed for both power-law and exponential distribution functions. The expected distribution of radiative-phase supernova remnants (SNRs) in the interstellar medium is calculated as a function of SNR birthrate and of the interstellar density in which they evolve. The results are combined with observed distance estimates, and it is shown that an interstellar density in excess of 0.1 per cu cm would be required to keep the SNRs sufficiently confined so that their cross sections are consistent with the observed number of components. The alternative possibility is considered that SNRs do not enter the radiative phase before escaping from the Galaxy or colliding with neighboring remnants.

  13. Direct measurements show decreasing methane emissions from natural gas local distribution systems in the United States.

    PubMed

    Lamb, Brian K; Edburg, Steven L; Ferrara, Thomas W; Howard, Touché; Harrison, Matthew R; Kolb, Charles E; Townsend-Small, Amy; Dyck, Wesley; Possolo, Antonio; Whetstone, James R

    2015-04-21

    Fugitive losses from natural gas distribution systems are a significant source of anthropogenic methane. Here, we report on a national sampling program to measure methane emissions from 13 urban distribution systems across the U.S. Emission factors were derived from direct measurements at 230 underground pipeline leaks and 229 metering and regulating facilities using stratified random sampling. When these new emission factors are combined with estimates for customer meters, maintenance, and upsets, and current pipeline miles and numbers of facilities, the total estimate is 393 Gg/yr with a 95% upper confidence limit of 854 Gg/yr (0.10% to 0.22% of the methane delivered nationwide). This fraction includes emissions from city gates to the customer meter, but does not include other urban sources or those downstream of customer meters. The upper confidence limit accounts for the skewed distribution of measurements, where a few large emitters accounted for most of the emissions. This emission estimate is 36% to 70% less than the 2011 EPA inventory, (based largely on 1990s emission data), and reflects significant upgrades at metering and regulating stations, improvements in leak detection and maintenance activities, as well as potential effects from differences in methodologies between the two studies. PMID:25826444

  14. A Mathematical Model of Gas Flow Distribution in the Grate-Kiln Iron Ore Pellets Induration Process

    NASA Astrophysics Data System (ADS)

    Feng, Junxiao; Zhang, Yu; Zhang, Yiyang; Xie, Zhiyin; Zhang, Cai

    2010-03-01

    Although models for general gas (e.g. natural gas) pipeline networks have been well established, research on another kind of gas networks we named gas passage networks (i.e. GPN; set that gas pass through spaces) in industry is rare. The features of the GPN are hard-determination leakage (i.e. 24.4%), quite-different thermophysical-properties, more cycles and not engaging cycle energy equations directly. And the gas network of grate-kiln-cooler (GKC) plant used for iron ore pellets induration is belong to this type. This paper develops a mathematical model to evaluate the flow distribution in this kind. Further, a field test was systematically carried out on a GKC plant in China. At last, the result shows that good agreement was observed, indicating the validity of the model.

  15. Spatial and non-spatial risk factors associated with cage-level distribution of infectious salmon anaemia at three Atlantic salmon, Salmo salar L., farms in Maine, USA.

    PubMed

    Gustafson, L; Ellis, S; Robinson, T; Marenghi, F; Merrill, P; Hawkins, L; Giray, C; Wagner, B

    2007-02-01

    The distribution of infectious salmon anaemia (ISA) was examined among 80 cages from three Atlantic salmon grow-out farms in Maine, USA that were stocked with smolts from a single hatchery. Cage-level disease was broadly defined as one or more moribund fish testing positive for infectious salmon anaemia virus (ISAV) by RT-PCR and a second confirmatory test (IFAT, culture or genotype sequence). Spatio-temporal and cage-level risks were explored using logistic regression and survival analysis. Non-spatial risk factors associated with ISA, or shortened survival time to disease, included increased predation, trucking company choice for smolt transfers, a finely-sedimented benthic substrate, and smaller average size of smolts at stocking. Univariable analysis identified the time-dependent spatial factor 'adjacency to newly infected cages' to be predictive of new infection in neighbouring cages 11-12 weeks later. However, none of the spatial factors, or their lags retained relevance in multiple-variable models. The results suggest a diffuse distribution of virus exposure throughout infected sites, with host-susceptibility factors probably influencing disease manifestation in individual cages. The narrow focus of the current study may limit application of the findings to other sites and year-classes. However, these data support the relevance of husbandry efforts to optimize fish health in regions affected by ISAV. PMID:17298565

  16. Mass Spectrometric Imaging of Wheat (Triticum spp.) and Barley (Hordeum vulgare L.) Cultivars: Distribution of Major Cell Wall Polysaccharides According to Their Main Structural Features.

    PubMed

    Veličković, Dušan; Saulnier, Luc; Lhomme, Margot; Damond, Aurélie; Guillon, Fabienne; Rogniaux, Hélène

    2016-08-17

    Arabinoxylans (AX) and (1→3),(1→4)-β-glucans (BG) are the main components of cereal cell walls and influence many aspects of their end uses. Important variations in the composition and structure of these polysaccharides have been reported among cereals and cultivars of a given species. In this work, the spatial distribution of AX and BG in the endosperm of mature grains was established for nine wheat varieties and eight barley varieties using enzymatically assisted mass spectrometry imaging (MSI). Important structural features of the AX and BG polymers that were previously shown to influence their physicochemical properties were assessed. Differences in the distribution of AX and BG structures were observed, both within the endosperm of a given cultivar and between wheat and barley cultivars. This study provides a unique picture of the structural heterogeneity of AX and BG polysaccharides at the scale of the whole endosperm in a series of wheat and barley cultivars. Thus, it can participate meaningfully in a strategy aiming at understanding the structure-function relationships of these two polymers. PMID:27463368

  17. Anisotropy of the neutral gas distribution of Comet Halley deduced from NGE/Vega 1 measurements. [Neutral Gas Experiment (NGE)

    NASA Technical Reports Server (NTRS)

    Hsieh, K. C.; Eip, WING-H. AFKEPPLER, E. agrichter, a. k; Eip, WING-H. AFKEPPLER, E. agrichter, a. k

    1986-01-01

    The neutral gas density profile of comet Halley measured by the Neutral Gas Experiment on Vega 1 showed an asymmetry between the inbound and the outbound legs during the fly-by on 6 March 1986. The implications of this asymmetry are discussed, and it is shown how the asymmetry detected by NGE on Vega 1 can be traced back to regions on or near the nucleus to obtain their relative gas production activities at specific times of emission.

  18. Pesticides in the atmosphere: a comparison of gas-particle partitioning and particle size distribution of legacy and current-use pesticides

    NASA Astrophysics Data System (ADS)

    Degrendele, C.; Okonski, K.; Melymuk, L.; Landlová, L.; Kukučka, P.; Audy, O.; Kohoutek, J.; Čupr, P.; Klánová, J.

    2016-02-01

    This study presents a comparison of seasonal variation, gas-particle partitioning, and particle-phase size distribution of organochlorine pesticides (OCPs) and current-use pesticides (CUPs) in air. Two years (2012/2013) of weekly air samples were collected at a background site in the Czech Republic using a high-volume air sampler. To study the particle-phase size distribution, air samples were also collected at an urban and rural site in the area of Brno, Czech Republic, using a cascade impactor separating atmospheric particulates according to six size fractions. Major differences were found in the atmospheric distribution of OCPs and CUPs. The atmospheric concentrations of CUPs were driven by agricultural activities while secondary sources such as volatilization from surfaces governed the atmospheric concentrations of OCPs. Moreover, clear differences were observed in gas-particle partitioning; CUP partitioning was influenced by adsorption onto mineral surfaces while OCPs were mainly partitioning to aerosols through absorption. A predictive method for estimating the gas-particle partitioning has been derived and is proposed for polar and non-polar pesticides. Finally, while OCPs and the majority of CUPs were largely found on fine particles, four CUPs (carbendazim, isoproturon, prochloraz, and terbuthylazine) had higher concentrations on coarse particles ( > 3.0 µm), which may be related to the pesticide application technique. This finding is particularly important and should be further investigated given that large particles result in lower risks from inhalation (regardless the toxicity of the pesticide) and lower potential for long-range atmospheric transport.

  19. Investigation of Colorless Distributed Combustion (CDC) with Swirl for Gas Turbine Application

    NASA Astrophysics Data System (ADS)

    Khalil Hasan, Ahmed Essam ElDin

    Colorless Distributed Combustion (CDC) with swirl is investigated for gas turbine engine applications due to its benefits for ultra-low pollutants emission, improved pattern factor and thermal field uniformity, low noise emission, and stable combustion with the alleviation of combustion instabilities. Adequate and fast mixing between the injected air and internally recirculated hot reactive gases to form hot and diluted oxidant is critical for CDC, followed by rapid mixing with the fuel. This results in distributed reaction zone instead of a concentrated thin flame front as observed in conventional diffusion flames, leading to avoidance of hot spot regions and providing reduced NOx and CO emissions. The focus of this dissertation is to develop and demonstrate CDC in a cylindrical combustor for application to stationary gas turbine combustors. The dissertation examines the sequential development of ultra-low emission colorless distributed combustor operating at a nominal thermal intensity of 36MW/m3-atm. Initially, the role of swirl is evaluated through comparing the performance of swirling and non-swirling configurations with focus on pollutants emission, stability, and isothermal flowfield through particle image velocimetry. Different fuel injection locations have also been examined, and based on performance a swirling configuration have been down selected for further investigations demonstrating emissions as low as 1 PPM of NO with a 40% reduction compared to non-swirling configuration. Further investigations were performed to outline the impact of inlet air temperature and combustor pressure on reaction distribution and combustor performance. Next, Fuel flexibility has been examined with view to develop CDC combustors that can handle different gaseous and liquid fuels, both traditional and renewable. These fuels included diluted methane, hydrogen enriched methane, propane, ethanol, kerosene, JP-8, Hydrogenated Renewable Jet fuel, and novel biofuel. Swirling CDC

  20. Global distribution and Gas-particle Partitioning of Polycyclic Aromatic Hydrocarbons - a Modelling Study

    NASA Astrophysics Data System (ADS)

    Lammel, G.; Sehili, A. M.

    2009-04-01

    Polycyclic aromatic hydrocarbons (PAHs) are emitted in all combustion processes. Some undergo re-volatilisation (multi-hopping). Little is known about degradation pathways and the processes determining gas-particle partitioning (Lohmann & Lammel, 2004). Distribution and fate have no been studied on the global scale so far (except for emissions in Europe and Russia; Sehili & Lammel, 2007). Anthracene (ANT), fluoranthene (FLT) and benzo[a]pyrene (BAP) have been studied under present-day climate and each 3 scenarios of atmospheric degradation and gas-particle partitioning using an atmospheric general circulation model with embedded dynamic aerosol submodel, ECHAM-HAM (Stier et al., 2005) and re-volatilization from ground compartments (Semeena et al., 2006). 10 years were simulated with a time-step of 30 min and 2.8°x2.8° and 19 levels. Emissions were compiled based on emission factors in 27 major types of combustion technologies, scaled to 141 combustion technologies and their global distribution as of 1996 (1°x1°) according to fuel type and the PM1 emission factor (Bond et al., 2004). The emissions were entried uniformly throughout the entire simulation time. Scenarios tested: AD = adsorption (according to the Junge empirical relationship; Pankow, 1987), OB = absorption in organic matter and adsorption to soot (Lohmann & Lammel, 2004) without and DP = with degradation in the atmospheric particulate phase. Gas-particle partitioning in air influences drastically the atmospheric cycling, total environmental fate (e.g. compartmental distributions) and the long-range transport potential (LRTP) of the substances studied. The LRTP is mostly regional. Comparison with observed levels indicate that degradation in the particulate phase must be slower than in the gas-phase. Furthermore, the levels of semivolatile PAHs (ANT and FLT) at high latitudes and a European mid latitude site cannot be explained by partitioning due to adsorption alone, but point to both absorption into

  1. Rapid and simultaneous determination of polychlorinated biphenyls and their main metabolites (hydroxylated and methyl sulfonyl) by gas chromatography coupled to mass spectrometry: comparison of different ionisation modes.

    PubMed

    Castro-Puyana, M; Herrero, L; González, M J; Gómara, B

    2013-07-17

    Instrumental methods based on gas chromatography coupled to mass spectrometry (GC-MS) have been developed and compared using two different MS ionisation modes, electron impact (EI) and electron capture negative ionisation (ECNI), for the fast, quantitative and simultaneous determination of polychlorinated biphenyls (PCBs) and their main metabolites (hydroxylated PCBs, OH-PCBs, and methyl sulfone PCBs, MeSO2-PCBs). Parameters affecting chromatographic separation and MS detection were evaluated in order to achieve the highest selectivity and sensitivity for both operation modes. The analytical characteristics of the developed methods were studied and compared in terms of linear range, limits of detection (LODs), limits of quantification (LOQs), and instrumental precision (repeatability and intermediate precision). Both ionisation methods showed similar precision, being relative standard deviations (RSD, %) lower than 9% and 14% for repeatability and intermediate precision, respectively. However, better LODs (from 0.01 to 0.14 pg injected for the three families of congeners studied) were achieved using ECNI-MS as ionisation mode. The suitability of the developed method was demonstrated through their application to fish liver oil samples. PMID:23830433

  2. The frequency and distribution of high-velocity gas in the Galaxy

    NASA Technical Reports Server (NTRS)

    Nichols, Joy S.

    1995-01-01

    The purpose of this study was to estimate the frequency and distribution of high-velocity gas in the Galaxy using UV absorption line measurements from archival high-dispersion IUE spectra and to identify particularly interesting regions for future study. Approximately 500 spectra have been examined. The study began with the creation of a database of all 0 and B stars with b less than or = to 30 deg observed with IUE at high dispersion over its 18-year lifetime. The original database of 2500 unique objects was reduced to 1200 objects which had optimal exposures available. The next task was to determine the distances of these stars so the high-velocity structures could be mapped in the Galaxy. Spectroscopic distances were calculated for each star for which photometry was available. The photometry was acquired for each star using the SIMBAD database. Preference was given to the ubvy system where available; otherwise the UBV system was used.

  3. The distribution of warm gas in the G327.3-0.6 star forming region

    NASA Astrophysics Data System (ADS)

    Leurini, S.; Wyrowski, F.; van der Tak, F.; Herpin, F.; Herschel WISH Team

    2011-05-01

    Water is a key molecule for determining the physical chemical structure of star forming regions because of its large abundance variations between warm and cold regions. As a part of the HIFI-led Key Program WISH (P.I. E. van Dishoeck), we are mapping six massive star forming region in different H2O lines with HIFI and PACS to investigate the effects of clustered star formation on feedback by protostellar outflow in such regions. Our Herschel observation are complemented by APEX CO and 13CO observations in mid- high-J transitions to study the distribution of warm gas and its physical conditions for comparison with the Herschel data. I will present large scale maps of the massive star forming region G327.3-0.6 obtained with APEX (CO isotopologues) and PACS (H2O) and report on our analysis of the region.

  4. Planning replacement of natural gas distribution systems under constraints on acceptable risk from explosions.

    PubMed

    Noonan, F

    1991-12-01

    Natural gas distribution systems in the United States were developed primarily in the first half of this century, utilizing materials such as cast iron and then steel. Over time, cast iron and steel pipe sections became weak from corrosion and are subject to failure which in turn can lead to explosions and possible injury and loss of life. Gas utilities maintain system integrity through repair-replacement programs where pipe sections are prioritized for replacement in any given year through cost-benefit analysis; however, the total annual amount to be budgeted for replacement is left to engineering judgment. This approach has left some utilities vulnerable to criticism that their current replacement rate on cast iron pipe is not great enough and that public safety is being compromised. This paper addresses the problem situation by formulating a linear programming replacement decision model which augments cost-benefit analysis with explicit constraints on acceptable risk to human life from fire/explosion. The model is illustrated for a hypothetical utility. PMID:1780504

  5. The Case for Natural Gas Fueled Solid Oxide Fuel Cell Power Systems for Distributed Generation

    SciTech Connect

    Chick, Lawrence A.; Weimar, Mark R.; Whyatt, Greg A.; Powell, Michael R.

    2015-02-01

    Natural-gas-fueled solid oxide fuel cell (NGSOFC) power systems yield electrical conversion efficiencies exceeding 60% and may become a viable alternative for distributed generation (DG) if stack life and manufacturing economies of scale can be realized. Currently, stacks last approximately 2 years and few systems are produced each year because of the relatively high cost of electricity from the systems. If mass manufacturing (10,000 units per year) and a stack life of 15 years can be reached, the cost of electricity from an NGSOFC system is estimated to be about 7.7 ¢/kWh, well within the price of commercial and residential retail prices at the national level (9.9-10¢/kWh and 11-12 ¢/kWh, respectively). With an additional 5 ¢/kWh in estimated additional benefits from DG, NGSOFC could be well positioned to replace the forecasted 59-77 gigawatts of capacity loss resulting from coal plant closures due to stricter emissions regulations and low natural gas prices.

  6. Study of quantification and distribution of explosive mixture in a confined space as a result of natural gas leak

    NASA Astrophysics Data System (ADS)

    Tulach, Aleš; Mynarz, Miroslav; Kozubková, Milada

    2014-03-01

    The contribution deals with quantification of natural gas leak from a domestic low pressure pipe to a confined space in relation to formation of explosive concentration. Within the experiments, amount of leak gas was determined considering the character of pipe damage. Leakage coefficients, natural gas expansion and time before reaching the lower explosive limit of a gas-air mixture were taken. Conducted experiments were then modelled using CFD software and the results were verified. In numerical model, several models of flow were used and afterwards following issues were analysed: leakage velocity, spatial distribution of the mixture in a confined space, formation of concentration at the lower explosive limit etc. This work should contribute to better understanding of propagation and distribution of gaseous fuel mixtures in confined spaces and thereby significantly reduce the risk of fires or explosions or prevent them.

  7. Thermodynamic Modeling and Dispatch of Distributed Energy Technologies including Fuel Cell -- Gas Turbine Hybrids

    NASA Astrophysics Data System (ADS)

    McLarty, Dustin Fogle

    Distributed energy systems are a promising means by which to reduce both emissions and costs. Continuous generators must be responsive and highly efficiency to support building dynamics and intermittent on-site renewable power. Fuel cell -- gas turbine hybrids (FC/GT) are fuel-flexible generators capable of ultra-high efficiency, ultra-low emissions, and rapid power response. This work undertakes a detailed study of the electrochemistry, chemistry and mechanical dynamics governing the complex interaction between the individual systems in such a highly coupled hybrid arrangement. The mechanisms leading to the compressor stall/surge phenomena are studied for the increased risk posed to particular hybrid configurations. A novel fuel cell modeling method introduced captures various spatial resolutions, flow geometries, stack configurations and novel heat transfer pathways. Several promising hybrid configurations are analyzed throughout the work and a sensitivity analysis of seven design parameters is conducted. A simple estimating method is introduced for the combined system efficiency of a fuel cell and a turbine using component performance specifications. Existing solid oxide fuel cell technology is capable of hybrid efficiencies greater than 75% (LHV) operating on natural gas, and existing molten carbonate systems greater than 70% (LHV). A dynamic model is calibrated to accurately capture the physical coupling of a FC/GT demonstrator tested at UC Irvine. The 2900 hour experiment highlighted the sensitivity to small perturbations and a need for additional control development. Further sensitivity studies outlined the responsiveness and limits of different control approaches. The capability for substantial turn-down and load following through speed control and flow bypass with minimal impact on internal fuel cell thermal distribution is particularly promising to meet local demands or provide dispatchable support for renewable power. Advanced control and dispatch

  8. MAINE HYDROGRAPHY

    EPA Science Inventory

    Hydronet_me24 and Hydropoly_me24 depict Maine's hydrography data, based on 8-digit hydrological unit codes (HUC's) at the 1:24,000 scale. Some New Hampshire and New Brunswick hydrography data are also included. The NHD hydrography data was compiled from previous ArcIn...

  9. MAINE WOODLOTS

    EPA Science Inventory

    MEOWN250 describes industrial, non-industrial, and public woodlot ownership in Maine at 1:250,000 scale. Industrial owners are those having at least one primary wood processing facility. Non-industrial owners are those with no primary wood processing facility. Public ownership...

  10. Maine Ingredients

    ERIC Educational Resources Information Center

    Waters, John K.

    2009-01-01

    This article features Maine Learning Technology Initiative (MLTI), the nation's first-ever statewide 1-to-1 laptop program which marks its seventh birthday by expanding into high schools, providing an occasion to celebrate--and to examine the components of its success. The plan to put laptops into the hands of every teacher and student in grades 7…

  11. Simultaneous magnetic resonance imaging of ventilation distribution and gas uptake in the human lung using hyperpolarized xenon-129.

    PubMed

    Mugler, John P; Altes, Talissa A; Ruset, Iulian C; Dregely, Isabel M; Mata, Jaime F; Miller, G Wilson; Ketel, Stephen; Ketel, Jeffrey; Hersman, F William; Ruppert, Kai

    2010-12-14

    Despite a myriad of technical advances in medical imaging, as well as the growing need to address the global impact of pulmonary diseases, such as asthma and chronic obstructive pulmonary disease, on health and quality of life, it remains challenging to obtain in vivo regional depiction and quantification of the most basic physiological functions of the lung-gas delivery to the airspaces and gas uptake by the lung parenchyma and blood-in a manner suitable for routine application in humans. We report a method based on MRI of hyperpolarized xenon-129 that permits simultaneous observation of the 3D distributions of ventilation (gas delivery) and gas uptake, as well as quantification of regional gas uptake based on the associated ventilation. Subjects with lung disease showed variations in gas uptake that differed from those in ventilation in many regions, suggesting that gas uptake as measured by this technique reflects such features as underlying pathological alterations of lung tissue or of local blood flow. Furthermore, the ratio of the signal associated with gas uptake to that associated with ventilation was substantially altered in subjects with lung disease compared with healthy subjects. This MRI-based method provides a way to quantify relationships among gas delivery, exchange, and transport, and appears to have significant potential to provide more insight into lung disease. PMID:21098267

  12. The Effects of Bottom Blowing Gas Flow Rate Distribution During the Steelmaking Converter Process on Mixing Efficiency

    NASA Astrophysics Data System (ADS)

    Chu, Kuan-Yu; Chen, Hsing-Hao; Lai, Po-Han; Wu, Hsuan-Chung; Liu, Yung-Chang; Lin, Chi-Cheng; Lu, Muh-Jung

    2016-04-01

    Featuring the advantages of top-blown and bottom-blown oxygen converters, top and bottom combined blown converters are mainstream devices used in steelmaking converter. This study adopted the FLUENT software to develop a numerical model that simulates 3D multiphase flows of gas (air and argon), liquid steel, and slag. Ten numerical experiments were conducted to analyze the effects that the bottom blowing gas flow rate distribution patterns (uniform, linear fixed total flow rate, linear fixed maximal flow rate, and V-type) and bottom blowing gas flow distribution gradients of combined blown converters exert on slag surface stirring heights, flow field patterns, simulation system dynamic pressures, mixing time, and liquid steel-slag interface velocity. The simulation results indicated that the mixing efficiency was highest for the linear fixed total flow rate, followed by the linear fixed maximal flow rate, V-type, and uniform patterns. The bottom blowing gas flow rate distribution exhibited linear patterns and large gradients, and high bottom blowing total flow rates increased the mixing efficiency substantially. In addition, the results suggested that even when bottom blowing total flow rate was reduced, adopting effective bottom blowing gas flow rate distribution patterns and gradients could improve the mixing efficiency.

  13. Searching for gas giant planets on Solar system scales - a NACO/APP L'-band survey of A- and F-type main-sequence stars

    NASA Astrophysics Data System (ADS)

    Meshkat, T.; Kenworthy, M. A.; Reggiani, M.; Quanz, S. P.; Mamajek, E. E.; Meyer, M. R.

    2015-11-01

    We report the results of a direct imaging survey of A- and F-type main-sequence stars searching for giant planets. A/F stars are often the targets of surveys, as they are thought to have more massive giant planets relative to solar-type stars. However, most imaging is only sensitive to orbital separations >30 au, where it has been demonstrated that giant planets are rare. In this survey, we take advantage of the high-contrast capabilities of the Apodizing Phase Plate coronagraph on NACO at the Very Large Telescope. Combined with optimized principal component analysis post-processing, we are sensitive to planetary-mass companions (2-12 MJup) at Solar system scales (≤30 au). We obtained data on 13 stars in the L' band and detected one new companion as part of this survey: an M6.0 ± 0.5 dwarf companion around HD 984. We re-detect low-mass companions around HD 12894 and HD 20385, both reported shortly after the completion of this survey. We use Monte Carlo simulations to determine new constraints on the low-mass (<80 MJup) companion frequency, as a function of mass and separation. Assuming solar-type planet mass and separation distributions, normalized to the planet frequency appropriate for A-stars, and the observed companion mass-ratio distribution for stellar companions extrapolated to planetary masses, we derive a truncation radius for the planetary mass companion surface density of <135 au at 95 per cent confidence.

  14. A perspective on cost-effectiveness of greenhouse gas reduction solutions in water distribution systems

    NASA Astrophysics Data System (ADS)

    Hendrickson, Thomas P.; Horvath, Arpad

    2014-01-01

    Water distribution systems (WDSs) face great challenges as aging infrastructures require significant investments in rehabilitation, replacement, and expansion. Reducing environmental impacts as WDSs develop is essential for utility managers and policy makers. This study quantifies the existing greenhouse gas (GHG) footprint of common WDS elements using life-cycle assessment (LCA) while identifying the greatest opportunities for emission reduction. This study addresses oversights of the related literature, which fails to capture several WDS elements and to provide detailed life-cycle inventories. The life-cycle inventory results for a US case study utility reveal that 81% of GHGs are from pumping energy, where a large portion of these emissions are a result of distribution leaks, which account for 270 billion l of water losses daily in the United States. Pipe replacement scheduling is analyzed from an environmental perspective where, through incorporating leak impacts, a tool reveals that optimal replacement is no more than 20 years, which is in contrast to the US average of 200 years. Carbon abatement costs (CACs) are calculated for different leak reduction scenarios for the case utility that range from -130 to 35 t-1 CO2(eq). Including life-cycle modeling in evaluating pipe materials identified polyvinyl chloride (PVC) and cement-lined ductile iron (DICL) as the Pareto efficient options, however; utilizing PVC presents human health risks. The model developed for the case utility is applied to California and Texas to determine the CACs of reducing leaks to 5% of distributed water. For California, annual GHG savings from reducing leaks alone (3.4 million tons of CO2(eq)) are found to exceed California Air Resources Board’s estimate for energy efficiency improvements in the state’s water infrastructure.

  15. Main Report

    PubMed Central

    2006-01-01

    scientific literature. The criteria were distributed among three main categories for each condition: The availability and characteristics of the screening test;The availability and complexity of diagnostic services; andThe availability and efficacy of treatments related to the conditions. A survey process utilizing a data collection instrument was used to gather expert opinion on the conditions in the first tier of the assessment. The data collection format and survey provided the opportunity to quantify expert opinion and to obtain the views of a diverse set of interest groups (necessary due to the subjective nature of some of the criteria). Statistical analysis of data produced a score for each condition, which determined its ranking and initial placement in one of three categories (high scoring, moderately scoring, or low scoring/absence of a newborn screening test). In the second tier of these analyses, the evidence base related to each condition was assessed in depth (e.g., via systematic reviews of reference lists including MedLine, PubMed and others; books; Internet searches; professional guidelines; clinical evidence; and cost/economic evidence and modeling). The fact sheets reflecting these analyses were evaluated by at least two acknowledged experts for each condition. These experts assessed the data and the associated references related to each criterion and provided corrections where appropriate, assigned a value to the level of evidence and the quality of the studies that established the evidence base, and determined whether there were significant variances from the survey data. Survey results were subsequently realigned with the evidence obtained from the scientific literature during the second-tier analysis for all objective criteria, based on input from at least three acknowledged experts in each condition. The information from these two tiers of assessment was then considered with regard to the overriding principles and other technology or condition

  16. Alexandrium fundyense cysts in the Gulf of Maine: long-term time series of abundance and distribution, and linkages to past and future blooms

    USGS Publications Warehouse

    Anderson, Donald M.; Keafer, Bruce A.; Kleindinst, Judith L.; McGillicuddy, Dennis J., Jr.; Martin, Jennifer L.; Norton, Kerry; Pilskaln, Cynthia H.; Smith, Juliette L.; Sherwood, Christopher R.; Butman, Bradford

    2014-01-01

    Here we document Alexandrium fundyense cyst abundance and distribution patterns over nine years (1997 and 2004–2011) in the coastal waters of the Gulf of Maine (GOM) and identify linkages between those patterns and several metrics of the severity or magnitude of blooms occurring before and after each autumn cyst survey. We also explore the relative utility of two measures of cyst abundance and demonstrate that GOM cyst counts can be normalized to sediment volume, revealing meaningful patterns equivalent to those determined with dry weight normalization. Cyst concentrations were highly variable spatially. Two distinct seedbeds (defined here as accumulation zones with>300 cysts cm−3) are evident, one in the Bay of Fundy (BOF) and one in mid-coast Maine. Overall, seedbed locations remained relatively constant through time, but their area varied 3–4 fold, and total cyst abundance more than 10 fold among years. A major expansion of the mid-coast Maine seedbed occurred in 2009 following an unusually intense A. fundyense bloom with visible red-water conditions, but that feature disappeared by late 2010. The regional system thus has only two seedbeds with the bathymetry, sediment characteristics, currents, biology, and environmental conditions necessary to persist for decades or longer. Strong positive correlations were confirmed between the abundance of cysts in both the 0–1 and the 0–3 cm layers of sediments in autumn and geographic measures of the extent of the bloom that occurred the next year (i.e., cysts→blooms), such as the length of coastline closed due to shellfish toxicity or the southernmost latitude of shellfish closures. In general, these metrics of bloom geographic extent did not correlate with the number of cysts in sediments following the blooms (blooms→cysts). There are, however, significant positive correlations between 0–3 cm cyst abundances and metrics of the preceding bloom that are indicative of bloom intensity or vegetative cell

  17. Alexandrium fundyense cysts in the Gulf of Maine: long-term time series of abundance and distribution, and linkages to past and future blooms

    PubMed Central

    Anderson, Donald M.; Keafer, Bruce A.; Kleindinst, Judith L.; McGillicuddy, Dennis J.; Martin, Jennifer L.; Norton, Kerry; Pilskaln, Cynthia H.; Smith, Juliette L.; Sherwood, Christopher R.; Butman, Bradford

    2013-01-01

    Here we document Alexandrium fundyense cyst abundance and distribution patterns over nine years (1997 and 2004-2011) in the coastal waters of the Gulf of Maine (GOM) and identify linkages between those patterns and several metrics of the severity or magnitude of blooms occurring before and after each autumn cyst survey. We also explore the relative utility of two measures of cyst abundance and demonstrate that GOM cyst counts can be normalized to sediment volume, revealing meaningful patterns equivalent to those determined with dry weight normalization. Cyst concentrations were highly variable spatially. Two distinct seedbeds (defined here as accumulation zones with > 300 cysts cm−3) are evident, one in the Bay of Fundy (BOF) and one in mid-coast Maine. Overall, seedbed locations remained relatively constant through time, but their area varied 3-4 fold, and total cyst abundance more than 10 fold among years. A major expansion of the mid-coast Maine seedbed occurred in 2009 following an unusually intense A. fundyense bloom with visible red-water conditions, but that feature disappeared by late 2010. The regional system thus has only two seedbeds with the bathymetry, sediment characteristics, currents, biology, and environmental conditions necessary to persist for decades or longer. Strong positive correlations were confirmed between the abundance of cysts in both the 0-1 and the 0-3 cm layers of sediments in autumn and geographic measures of the extent of the bloom that occurred the next year (i.e., cysts → blooms), such as the length of coastline closed due to shellfish toxicity or the southernmost latitude of shellfish closures. In general, these metrics of bloom geographic extent did not correlate with the number of cysts in sediments following the blooms (blooms → cysts). There are, however, significant positive correlations between 0-3 cm cyst abundances and metrics of the preceding bloom that are indicative of bloom intensity or vegetative cell abundance

  18. Alexandrium fundyense cysts in the Gulf of Maine: long-term time series of abundance and distribution, and linkages to past and future blooms.

    PubMed

    Anderson, Donald M; Keafer, Bruce A; Kleindinst, Judith L; McGillicuddy, Dennis J; Martin, Jennifer L; Norton, Kerry; Pilskaln, Cynthia H; Smith, Juliette L; Sherwood, Christopher R; Butman, Bradford

    2014-05-01

    Here we document Alexandrium fundyense cyst abundance and distribution patterns over nine years (1997 and 2004-2011) in the coastal waters of the Gulf of Maine (GOM) and identify linkages between those patterns and several metrics of the severity or magnitude of blooms occurring before and after each autumn cyst survey. We also explore the relative utility of two measures of cyst abundance and demonstrate that GOM cyst counts can be normalized to sediment volume, revealing meaningful patterns equivalent to those determined with dry weight normalization. Cyst concentrations were highly variable spatially. Two distinct seedbeds (defined here as accumulation zones with > 300 cysts cm(-3)) are evident, one in the Bay of Fundy (BOF) and one in mid-coast Maine. Overall, seedbed locations remained relatively constant through time, but their area varied 3-4 fold, and total cyst abundance more than 10 fold among years. A major expansion of the mid-coast Maine seedbed occurred in 2009 following an unusually intense A. fundyense bloom with visible red-water conditions, but that feature disappeared by late 2010. The regional system thus has only two seedbeds with the bathymetry, sediment characteristics, currents, biology, and environmental conditions necessary to persist for decades or longer. Strong positive correlations were confirmed between the abundance of cysts in both the 0-1 and the 0-3 cm layers of sediments in autumn and geographic measures of the extent of the bloom that occurred the next year (i.e., cysts → blooms), such as the length of coastline closed due to shellfish toxicity or the southernmost latitude of shellfish closures. In general, these metrics of bloom geographic extent did not correlate with the number of cysts in sediments following the blooms (blooms → cysts). There are, however, significant positive correlations between 0-3 cm cyst abundances and metrics of the preceding bloom that are indicative of bloom intensity or vegetative cell abundance

  19. Alexandrium fundyense cysts in the Gulf of Maine: Long-term time series of abundance and distribution, and linkages to past and future blooms

    NASA Astrophysics Data System (ADS)

    Anderson, Donald M.; Keafer, Bruce A.; Kleindinst, Judith L.; McGillicuddy, Dennis J.; Martin, Jennifer L.; Norton, Kerry; Pilskaln, Cynthia H.; Smith, Juliette L.; Sherwood, Christopher R.; Butman, Bradford

    2014-05-01

    Here we document Alexandrium fundyense cyst abundance and distribution patterns over nine years (1997 and 2004-2011) in the coastal waters of the Gulf of Maine (GOM) and identify linkages between those patterns and several metrics of the severity or magnitude of blooms occurring before and after each autumn cyst survey. We also explore the relative utility of two measures of cyst abundance and demonstrate that GOM cyst counts can be normalized to sediment volume, revealing meaningful patterns equivalent to those determined with dry weight normalization. Cyst concentrations were highly variable spatially. Two distinct seedbeds (defined here as accumulation zones with>300 cysts cm-3) are evident, one in the Bay of Fundy (BOF) and one in mid-coast Maine. Overall, seedbed locations remained relatively constant through time, but their area varied 3-4 fold, and total cyst abundance more than 10 fold among years. A major expansion of the mid-coast Maine seedbed occurred in 2009 following an unusually intense A. fundyense bloom with visible red-water conditions, but that feature disappeared by late 2010. The regional system thus has only two seedbeds with the bathymetry, sediment characteristics, currents, biology, and environmental conditions necessary to persist for decades or longer. Strong positive correlations were confirmed between the abundance of cysts in both the 0-1 and the 0-3 cm layers of sediments in autumn and geographic measures of the extent of the bloom that occurred the next year (i.e., cysts→blooms), such as the length of coastline closed due to shellfish toxicity or the southernmost latitude of shellfish closures. In general, these metrics of bloom geographic extent did not correlate with the number of cysts in sediments following the blooms (blooms→cysts). There are, however, significant positive correlations between 0-3 cm cyst abundances and metrics of the preceding bloom that are indicative of bloom intensity or vegetative cell abundance (e

  20. Updated greenhouse gas and criteria air pollutant emission factors and their probability distribution functions for electricity generating units

    SciTech Connect

    Cai, H.; Wang, M.; Elgowainy, A.; Han, J.

    2012-07-06

    Greenhouse gas (CO{sub 2}, CH{sub 4} and N{sub 2}O, hereinafter GHG) and criteria air pollutant (CO, NO{sub x}, VOC, PM{sub 10}, PM{sub 2.5} and SO{sub x}, hereinafter CAP) emission factors for various types of power plants burning various fuels with different technologies are important upstream parameters for estimating life-cycle emissions associated with alternative vehicle/fuel systems in the transportation sector, especially electric vehicles. The emission factors are typically expressed in grams of GHG or CAP per kWh of electricity generated by a specific power generation technology. This document describes our approach for updating and expanding GHG and CAP emission factors in the GREET (Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation) model developed at Argonne National Laboratory (see Wang 1999 and the GREET website at http://greet.es.anl.gov/main) for various power generation technologies. These GHG and CAP emissions are used to estimate the impact of electricity use by stationary and transportation applications on their fuel-cycle emissions. The electricity generation mixes and the fuel shares attributable to various combustion technologies at the national, regional and state levels are also updated in this document. The energy conversion efficiencies of electric generating units (EGUs) by fuel type and combustion technology are calculated on the basis of the lower heating values of each fuel, to be consistent with the basis used in GREET for transportation fuels. On the basis of the updated GHG and CAP emission factors and energy efficiencies of EGUs, the probability distribution functions (PDFs), which are functions that describe the relative likelihood for the emission factors and energy efficiencies as random variables to take on a given value by the integral of their own probability distributions, are updated using best-fit statistical curves to characterize the uncertainties associated with GHG and CAP emissions in life

  1. Plasma pharmacokinetics and tissue distribution of arctiin and its main metabolite in rats by HPLC-UV and LC-MS.

    PubMed

    He, Fan; Fan, He; Dou, De-Qiang; De-Qiang, Dou; Sun, Yu; Yu, Sun; Zhu, Lin; Lin, Zhu; Xiao, Hong-Bin; Hong-Bin, Xiao; Kang, Ting-Guo; Ting-Guo, Kang

    2012-05-01

    The pharmacokinetic profile of arctiin, the major active lignan in fruits of Arctium lappa L., was investigated. Its main meta"bolite arctigenin was identified by an LC-MS method, and an HPLC-UV technique was developed for the simultaneous quantification of the metabolite and arctiin in plasma and organs. Chromatographic separation was performed on an Agilent™ C₁₈ HPLC column with acetonitrile and water by linear gradient elution. Arctiin and arctigenin were identified on-line by LC-MS. The pharmacokinetics and tissue distribution of arctiin and arctigenin were determined for the first time by using a simple, selective, and accurate HPLC method. The AUC0-t values of arctigenin were larger compared with arctiin after oral administration of arctiin. The concentration of the metabolite was significantly higher than the concentration of arctiin in the stomach and small intestine in rats after oral administration of arctiin, indicating that the stomach and small intestine were the major organs of arctiin metabolism. These findings could provide support for the clinical studies conducted with Fructus Arctii. PMID:22499560

  2. The use of multibeam and split-beam echo sounders for assessing biomass and distribution of spring-spawning Atlantic cod in the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Gurshin, Christopher William Damon

    This research focused on advancing the application of split-beam and multibeam echo sounding to remotely locate and describe spatial distribution, and to provide a relative measure of abundance of the spring-spawning Atlantic cod (Gadus morhua) in the western Gulf of Maine. Specifically, the main objectives of this research were 1) to test the feasibility of a multibeam echo sounder to detect changes in volume backscatter proportional to incrementally decreasing quantities of cod held in a submerged cage, and to compare results to a split-beam echo sounder; 2) to describe the spatio-temporal distribution and estimate biomass of spring-spawning cod in the Gulf of Maine cod spawning protection area (GOMCSPA) by repeated acoustic and trawl surveys; and 3) to determine a predictive relation between target strength and length for 38-kHz and 120-kHz split-beam echo sounders and a 300-kHz multibeam echo sounder, and characterize other factors affecting backscattering of sound. The multibeam echo sounder detected a small and large reduction in volume backscatter proportional to reductions in stocking density of caged cod, while the split-beam echo sounder only detected a large reduction in stocking density. The spatial information from the multibeam echo sounder helped interpret and explain results from the split-beam echo sounder. Repeated acoustic and trawl surveys showed cod were relatively widespread in the survey area in May, but congregated at higher densities in areas adjacent to two elevated bathymetric features. Most cod converged to a single location in June, and were at a higher concentration than observations in May. This congregation decreased in size and density in July. Survey estimates of cod biomass ranged 184-494 mt in May, 138-617 mt in June, and 39-135 mt in July, depending on the estimation method. Based on echo classification and extrapolation, cod biomass to the GOMCSPA ranged 260-466 mt in May, 196-513 mt in June, and 91-198 mt in July. The biomass

  3. Effect of through-plane polytetrafluoroethylene distribution in gas diffusion layers on performance of proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ito, Hiroshi; Iwamura, Takuya; Someya, Satoshi; Munakata, Tetsuo; Nakano, Akihiro; Heo, Yun; Ishida, Masayoshi; Nakajima, Hironori; Kitahara, Tatsumi

    2016-02-01

    This experimental study identifies the effect of through-plane polytetrafluoroethylene (PTFE) distribution in gas diffusion backing (GDB) on the performance of proton exchange membrane fuel cells (PEMFC). PTFE-drying under vacuum pressure created a relatively uniform PTFE distribution in GDB compared to drying under atmospheric pressure. Carbon paper samples with different PTFE distributions due to the difference in drying conditions were prepared and used for the cathode gas diffusion layer (GDL) of PEMFCs. Also investigated is the effect of MPL application on the performance for those samples. The current density (i) - voltage (V) characteristics of these PEMFCs measured under high relative humidity conditions clearly showed that, with or without MPL, the cell using the GDL with PTFE dried under vacuum condition showed better performance than that dried under atmospheric condition. It is suggested that this improved performance is caused by the efficient transport of liquid water through the GDB due to the uniform distribution of PTFE.

  4. Distributions of the particle/gas and dust/gas partition coefficients for seventy-two semi-volatile organic compounds in indoor environment.

    PubMed

    Wei, Wenjuan; Mandin, Corinne; Blanchard, Olivier; Mercier, Fabien; Pelletier, Maud; Le Bot, Barbara; Glorennec, Philippe; Ramalho, Olivier

    2016-06-01

    Particle/gas and dust/gas partition coefficients (Kp and Kd) are two key parameters that address the partitioning of semi-volatile organic compounds (SVOCs) between gas-phase, airborne particles, and settled dust in indoor environment. A number of empirical equations to calculate the values of Kp and Kd have been reported in the literature. Therefore, the difficulty lies in the selection of a specific empirical equation in a given situation. In this study, we retrieved from the literature 38 empirical equations for calculating Kp and Kd values from the SVOC saturation vapor pressure and octanol/air partition coefficient. These values were calculated for 72 SVOCs: 9 phthalates, 9 polybrominated diphenyl ethers (PBDEs), 11 polychlorinated biphenyls (PCBs), 22 biocides, 14 polycyclic aromatic hydrocarbons (PAHs), 3 alkylphenols, 2 synthetic musks, tributylphosphate, and bisphenol A. The mean and median values of log10Kp or log10Kd for most SVOCs were of the same order of magnitude. The distribution of log10Kp values was fitted to either a normal distribution (for 27 SVOCs) or a log-normal distribution (for 45 SVOCs). This work provides a reference distribution of the log10Kp for 72 SVOCs, and its use may reduce the bias associated with the selection of a specific value or equation. PMID:27016817

  5. Polycyclic aromatic hydrocarbons in urban atmosphere of Guangzhou, China: Size distribution characteristics and size-resolved gas-particle partitioning

    NASA Astrophysics Data System (ADS)

    Yu, Huan; Yu, Jian Zhen

    2012-07-01

    Size distributions of thirteen polycyclic aromatic hydrocarbons (PAHs), elemental carbon (EC), and organic carbon (OC) in the range of 0.01-18 μm were measured using a nano Micro-Orifice Uniform Deposit Impactor (nano-MOUDI) in an urban location in Guangzhou, China in July 2006. PAH size distributions were fit with five modes and the respective mass median aerodynamic diameters (MMAD) are: Aitken mode (MMAD: ˜0.05 μm), three accumulation modes AMI, AMII, AMIII (MMAD: 0.13-0.17 μm, 0.4-0.45 μm, and 0.9-1.2 μm, respectively), and coarse mode (MMAD: 4-6 μm). Seven-ring PAH was mainly in AMII and AMIII. Five- and six-ring PAHs were found to be abundant in all the three AM. Three- and four-ring PAHs had a significant presence in the coarse mode in addition to the three AM. Size-resolved gas-particle partition coefficients of PAHs (Kp) were estimated using measured EC and OC data. The Kp values of a given PAH could differ by a factor of up to ˜7 on particles in different size modes, with the highest Kp associated with the AMI particles and the lowest Kp associated with the coarse mode particles. Comparison of calculated overall Kp with measured Kp values in Guangzhou by Yang et al. (2010) shows that adsorption on EC appeared to be the dominant mechanism driving the gas-particle partitioning of three- and four-ring PAHs while absorption in OM played a dominant role for five- and six-ring PAHs. The calculated equilibrium timescales of repartitioning indicate that five- to seven-ring PAHs could not achieve equilibrium partitioning within their typical residence time in urban atmospheres, while three- and four-ring PAHs could readily reach new equilibrium states in particles of all sizes. A partitioning flux is therefore proposed to replace the equilibrium assumption in modeling PAH transport and fate.

  6. Impact of routine episodic emissions on the expected frequency distribution of emissions from oil and gas production sources.

    NASA Astrophysics Data System (ADS)

    Smith, N.; Blewitt, D.; Hebert, L. B.

    2015-12-01

    In coordination with oil and gas operators, we developed a high resolution (< 1 min) simulation of temporal variability in well-pad oil and gas emissions over a year. We include routine emissions from condensate tanks, dehydrators, pneumatic devices, fugitive leaks and liquids unloading. We explore the variability in natural gas emissions from these individual well-pad sources, and find that routine short-term episodic emissions such as tank flashing and liquids unloading result in the appearance of a skewed, or 'fat-tail' distribution of emissions, from an individual well-pad over time. Additionally, we explore the expected variability in emissions from multiple wells with different raw gas composition, gas/liquids production volumes and control equipment. Differences in well-level composition, production volume and control equipment translate into differences in well-level emissions leading to a fat-tail distribution of emissions in the absence of operational upsets. Our results have several implications for recent studies focusing on emissions from oil and gas sources. Time scale of emission estimates are important and have important policy implications. Fat tail distributions may not be entirely driven by avoidable mechanical failures, and are expected to occur under routine operational conditions from short-duration emissions (e.g., tank flashing, liquid unloading). An understanding of the expected distribution of emissions for a particular population of wells is necessary to evaluate whether the observed distribution is more skewed than expected. Temporal variability in well-pad emissions make comparisons to annual average emissions inventories difficult and may complicate the interpretation of long-term ambient fenceline monitoring data. Sophisticated change detection algorithms will be necessary to identify when true operational upsets occur versus routine short-term emissions.

  7. Measurement of ultrafine particle size distributions from coal-, oil-, and gas-fired stationary combustion sources.

    PubMed

    Chang, M C Oliver; Chow, Judith C; Watson, John G; Hopke, Philip K; Yi, Seung-Muk; England, Glenn C

    2004-12-01

    Currently, we have limited knowledge of the physical and chemical properties of emitted primary combustion aerosols and the changes in those properties caused by nucleation, condensation growth of volatile species, and particle coagulations under dilution and cooling in the ambient air. A dilution chamber was deployed to sample exhaust from a pilot-scale furnace burning various fuels at a nominal heat input rate of 160 kW/h(-1) and 3% excess oxygen. The formation mechanisms of particles smaller than 420 nm in electrical mobility diameter were experimentally investigated by measurement with a Scanning Mobility Particle Sizer (SMPS) as a function of aging times, dilution air ratios, combustion exhaust temperatures, and fuel types. Particle formation in the dilution process is a complex mixture of nucleation, coagulation, and condensational growth, depending on the concentrations of available condensable species and solid or liquid particles (such as soot, ash) in combustion exhausts. The measured particle size distributions in number concentrations measured show peaks of particle number concentrations for medium sulfur bituminous coal, No. 6 fuel oil, and natural gas at 40-50 nm, 70-100 nm, and 15-25 nm, respectively. For No. 6 fuel oil and coal, the particle number concentration is constant in the range of a dilution air ratio of 50, but the number decreases as the dilution air ratio decreases to 10. However, for natural gas, the particle number concentration is higher at a dilution air ratio of 10 and decreases at dilution air ratios of 20-50. At a dilution air ratio of 10, severe particle coagulation occurs in a relatively short time. Samples taken at different combustion exhaust temperatures for these fuel types show higher particle number concentrations at 645 K than at 450 K. As the aging time of particles increases, the particles increase in size and the number concentrations decrease. The largest gradient of particle number distribution occurs within the

  8. Combustion of Biosolids in a Bubbling Fluidized Bed, Part 1: Main Ash-Forming Elements and Ash Distribution with a Focus on Phosphorus

    PubMed Central

    2014-01-01

    This is the first in a series of three papers describing combustion of biosolids in a 5-kW bubbling fluidized bed, the ash chemistry, and possible application of the ash produced as a fertilizing agent. This part of the study aims to clarify whether the distribution of main ash forming elements from biosolids can be changed by modifying the fuel matrix, the crystalline compounds of which can be identified in the raw materials and what role the total composition may play for which compounds are formed during combustion. The biosolids were subjected to low-temperature ashing to investigate which crystalline compounds that were present in the raw materials. Combustion experiments of two different types of biosolids were conducted in a 5-kW benchscale bubbling fluidized bed at two different bed temperatures and with two different additives. The additives were chosen to investigate whether the addition of alkali (K2CO3) and alkaline-earth metal (CaCO3) would affect the speciation of phosphorus, so the molar ratios targeted in modified fuels were P:K = 1:1 and P:K:Ca = 1:1:1, respectively. After combustion the ash fractions were collected, the ash distribution was determined and the ash fractions were analyzed with regards to elemental composition (ICP-AES and SEM-EDS) and part of the bed ash was also analyzed qualitatively using XRD. There was no evidence of zeolites in the unmodified fuels, based on low-temperature ashing. During combustion, the biosolid pellets formed large bed ash particles, ash pellets, which contained most of the total ash content (54%–95% (w/w)). This ash fraction contained most of the phosphorus found in the ash and the only phosphate that was identified was a whitlockite, Ca9(K,Mg,Fe)(PO4)7, for all fuels and fuel mixtures. With the addition of potassium, cristobalite (SiO2) could no longer be identified via X-ray diffraction (XRD) in the bed ash particles and leucite (KAlSi2O6) was formed. Most of the alkaline-earth metals calcium and

  9. Influence of Flue Gas Desulfurization Gypsum Amendments on Heavy Metal Distribution in Reclaimed Sodic Soils

    PubMed Central

    Chen, Qun; Wang, Shujuan; Li, Yan; Zhang, Ning; Zhao, Bo; Zhuo, Yuqun; Chen, Changhe

    2015-01-01

    Abstract Although flue gas desulfurization (FGD) gypsum has become an effective soil amendment for sodic soil reclamation, it carries extra heavy metal contamination into the soil environment. The fate of heavy metals introduced by FGD gypsum in sodic or saline–alkali soils is still unclear. This work aims to investigate the effects of FGD gypsum addition on the heavy metal distributions in a sodic soil. Original soil samples were collected from typical sodic land in north China. Soil column leaching tests were conducted to investigate the influence of FGD gypsum addition on the soil properties, especially on distribution profiles of the heavy metals (Pb, Cd, Cr, As, and Hg) in the soil layers. Results showed that pH, electrical conductivity, and exchangeable sodium percentage in amended soils were significantly reduced from 10.2 to 8.46, 1.8 to 0.2 dS/m, and 18.14% to 1.28%, respectively. As and Hg concentrations in the soils were found to be positively correlated with FGD gypsum added. The amount of Hg in the leachate was positively correlated with FGD gypsum application ratio, whereas a negative correlation was observed between the Pb concentration in the leachate and the FGD gypsum ratio. Results revealed that heavy metal concentrations in soils complied well with Environmental Quality Standard for Soils in China (GB15618-1995). This work helps to understand the fate of FGD gypsum-introduced heavy metals in sodic soils and provides a baseline for further environmental risk assessment associated with applying FGD gypsum for sodic soil remediation. PMID:26064038

  10. Products from the reaction of monoterpenes with ozone and their distribution between the gas- and particle-phase

    NASA Astrophysics Data System (ADS)

    Winterhalter, R.; Römpp, A.; Kavouras, I. G.; Moortgat, G. K.

    2003-04-01

    The monoterpene-ozone reaction is an important source of tropospheric aerosols, yet the formation mechanism and physico-chemical properties of the organic aerosol particles are not well understood. In this paper a detailed product study of the gas-phase ozonolysis of various monoterpenes (alpha-pinene, beta-pinene, sabinene, limonene, and 3-carene) is presented, with special focus on the distribution of the products between the gas- and aerosol phase. The reactions were performed in a 570 l glass reactor at 730 Torr and room temperature in synthetic air in the presence and absence of cyclohexane as OH-radical scavenger. The reaction was monitored by FTIR-spectroscopy (ozone, monoterpenes and gas-phase products) and by a Scanning Mobility Particle Sizer (Size distribution, aerosol volume and number concentration). The separation of gas-phase and particulate products was achieved by a combination of gas-phase denuder and filter sampling. Particles were collected with quartz fiber filter coated with 1M NaOH and additionally with teflon filters, while gaseous products were sampled with a diffusion denuder coated with 1M NaOH. The reaction products have been extracted with water, and the extracts have been analysed by LC-MS-MS-TOF using ESI (-) and APCI (+) ionisation. Furthermore the samples have been also analysed by GC-MS after derivatization of the organic acids. The products and their gas-particle partitioning will be presented, and the possible reaction mechanisms will be discussed.

  11. Distribution and chemical fate of 36Cl-chlorine dioxide gas during the fumigation of tomatoes and cantaloupe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The distribution and chemical fate of 36Cl-ClO2 gas subsequent to fumigation of tomatoes or cantaloupe was investigated as was major factors that affect the formation of chloroxyanion byproducts. Approximately 22% of the generated 36Cl-ClO2 was present on fumigated tomatoes after a 2-hour exposure t...

  12. 40 CFR Table W - 7 of Subpart W of Part 98-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 0.772 Open-ended Line 26.131 Population Emission Factors—Below Grade Metering-Regulating station 1..., Inlet Pressure 100 to 300 psig 0.20 Below Grade M&R Station, Inlet Pressure Population....13 Cast Iron 27.25 Population Emission Factors—Distribution Services, Gas Service 4 Unprotected...

  13. 40 CFR Table W - 7 of Subpart W of Part 98-Default Methane Emission Factors for Natural Gas Distribution

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 0.772 Open-ended Line 26.131 Population Emission Factors—Below Grade Metering-Regulating station 1..., Inlet Pressure 100 to 300 psig 0.20 Below Grade M&R Station, Inlet Pressure Population....13 Cast Iron 27.25 Population Emission Factors—Distribution Services, Gas Service 4 Unprotected...

  14. 49 CFR 192.197 - Control of the pressure of gas delivered from high-pressure distribution systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Control of the pressure of gas delivered from high-pressure distribution systems. 192.197 Section 192.197 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) PIPELINE...

  15. SIZE DISTRIBUTIONS OF TRACE METALS IN FLUE GAS PARTICULATE FROM A PILOT-SCALE ROTARY KILN INCINERATOR

    EPA Science Inventory

    The distributions of nine trace metals in flue gas particulate by particle size range were determined as part of a pilot-scale hazardous waste incineration test program. hese tests were conducted in the rotary kiln incinerator system at the U.S. EPA's Incineration Research Facili...

  16. Quantitative time-averaged gas and liquid distributions using x-ray fluorescence and radiography in atomizing sprays.

    PubMed

    Radke, Christopher D; McManamen, J Patrick; Kastengren, Alan L; Halls, Benjamin R; Meyer, Terrence R

    2015-05-01

    A method for quantitative measurements of gas and liquid distributions is demonstrated using simultaneous x-ray fluorescence and radiography of both phases in an atomizing coaxial spray. Synchrotron radiation at 10.1 keV from the Advanced Photon Source at Argonne National Laboratory is used for x-ray fluorescence of argon gas and two tracer elements seeded into the liquid stream. Simultaneous time-resolved x-ray radiography combined with time-averaged dual-tracer fluorescence measurements enabled corrections for reabsorption of x-ray fluorescence photons for accurate, line-of-sight averaged measurements of the distribution of the gas and liquid phases originating from the atomizing nozzle. PMID:25927776

  17. Distribution of Trichloroethylene and Geologic Controls on Contaminant Pathways near the Royal River, McKin Superfund Site Area, Gray, Maine

    USGS Publications Warehouse

    Lyford, Forest P.; Flight, L.E.; Stone, Janet Radway; Clifford, Scott

    1999-01-01

    Vapor-diffusion samplers were used in the autumn of 1997 to determine the lateral extent and distribution of concentrations of a trichloroethylene (TCE) plume in the ground-water discharge area near the McKin Superfund Site, Gray, Maine. Analyses of vapor in the samplers identified a plume about 800 feet wide entering the river near Boiling Springs, an area of ground-water discharge on the flood plain of the Royal River. The highest observed concentration of TCE in vapor was in an area of sand boils on the western bank of the river and about 200 feet downstream from Boiling Springs. Previous studies showed that most of the TCE load in the river originated in the area of the sand boils. In general, highest concentrations were observed on the western side of the river on the upgradient side of the plume, but TCE also was detected at numerous locations in the center and eastern bank of the river. The TCE plume discharges to the river where fine-grained glaciomarine sediments of the Presumpscot Formation are absent and where coarse-grained facies of buried glaciomarine fan deposits provide a pathway for ground-water flow. Based on results of analyses of vapor-diffusion samples and other previous studies, the plume appears to pass under and beyond the river near Boiling Springs and along the river for about 300 feet downstream from the sand boils. A coarse-grained, organic-rich layer at the base of the alluvial flood plain sediments is confined by overlying fine-grained alluvial sediments and may provide a conduit for ground-water leaking upward from buried glaciomarine fan deposits.

  18. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 10: METERING AND PRESSURE REGULATING STATIONS IN NATURAL GAS TRANSMISSIONS AND DISTRIBUTION

    EPA Science Inventory

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  19. Spatially distributed flame transfer functions for predicting combustion dynamics in lean premixed gas turbine combustors

    SciTech Connect

    Kim, K.T.; Lee, J.G.; Quay, B.D.; Santavicca, D.A.

    2010-09-15

    The present paper describes a methodology to improve the accuracy of prediction of the eigenfrequencies and growth rates of self-induced instabilities and demonstrates its application to a laboratory-scale, swirl-stabilized, lean-premixed, gas turbine combustor. The influence of the spatial heat release distribution is accounted for using local flame transfer function (FTF) measurements. The two-microphone technique and CH{sup *} chemiluminescence intensity measurements are used to determine the input (inlet velocity perturbation) and the output functions (heat release oscillation), respectively, for the local flame transfer functions. The experimentally determined local flame transfer functions are superposed using the flame transfer function superposition principle, and the result is incorporated into an analytic thermoacoustic model, in order to predict the linear stability characteristics of a given system. Results show that when the flame length is not acoustically compact the model prediction calculated using the local flame transfer functions is better than the prediction made using the global flame transfer function. In the case of a flame in the compact flame regime, accurate predictions of eigenfrequencies and growth rates can be obtained using the global flame transfer function. It was also found that the general response characteristics of the local FTF (gain and phase) are qualitatively the same as those of the global FTF. (author)

  20. Gas-liquid Phase Distribution and Void Fraction Measurements Using the MRI

    NASA Technical Reports Server (NTRS)

    Daidzic, N. E.; Schmidt, E.; Hasan, M. M.; Altobelli, S.

    2004-01-01

    We used a permanent-magnet MRI system to estimate the integral and spatially- and/or temporally-resolved void-fraction distributions and flow patterns in gas-liquid two-phase flows. Air was introduced at the bottom of the stagnant liquid column using an accurate and programmable syringe pump. Air flow rates were varied between 1 and 200 ml/min. The cylindrical non-conducting test tube in which two-phase flow was measured was placed in a 2.67 kGauss MRI with MRT spectrometer/imager. Roughly linear relationship has been obtained for the integral void-fraction, obtained by volume-averaging of the spatially-resolved signals, and the air flow rate in upward direction. The time-averaged spatially-resolved void fraction has also been obtained for the quasi-steady flow of air in a stagnant liquid column. No great accuracy is claimed as this was an exploratory proof-of-concept type of experiment. Preliminary results show that MRI a non-invasive and non-intrusive experimental technique can indeed provide a wealth of different qualitative and quantitative data and is especially well suited for averaged transport processes in adiabatic and diabatic multi-phase and/or multi-component flows.

  1. Realtime Gas Emission Monitoring at Hazardous Sites Using a Distributed Point-Source Sensing Infrastructure.

    PubMed

    Manes, Gianfranco; Collodi, Giovanni; Gelpi, Leonardo; Fusco, Rosanna; Ricci, Giuseppe; Manes, Antonio; Passafiume, Marco

    2016-01-01

    This paper describes a distributed point-source monitoring platform for gas level and leakage detection in hazardous environments. The platform, based on a wireless sensor network (WSN) architecture, is organised into sub-networks to be positioned in the plant's critical areas; each sub-net includes a gateway unit wirelessly connected to the WSN nodes, hence providing an easily deployable, stand-alone infrastructure featuring a high degree of scalability and reconfigurability. Furthermore, the system provides automated calibration routines which can be accomplished by non-specialized maintenance operators without system reliability reduction issues. Internet connectivity is provided via TCP/IP over GPRS (Internet standard protocols over mobile networks) gateways at a one-minute sampling rate. Environmental and process data are forwarded to a remote server and made available to authenticated users through a user interface that provides data rendering in various formats and multi-sensor data fusion. The platform is able to provide real-time plant management with an effective; accurate tool for immediate warning in case of critical events. PMID:26805832

  2. Determining gas bubble morphology and size distribution in mud using CT imagery

    NASA Astrophysics Data System (ADS)

    Briggs, Kevin B.; Reed, Allen H.

    2003-10-01

    Sampling for the measurement and description of methane gas bubbles in situ was accomplished using the method of Abegg and Anderson [Mar. Geol. 137, 137-147 (1997)]. Sediment cores from East Bay, off the mouth of the Mississippi River, were collected by divers and placed into aluminum pressure transfer chambers while on the seafloor. With the cores at seafloor pressure within the chambers, they were transferred to an x-ray computed tomography (CT) scanner where high-resolution images were made of the sediment within the cores. Data, in the format of series of cross-sectional images of x-ray attenuation reconstructed in 3-D, were evaluated in terms of spatial distribution, sizes, and shapes of bubbles. CT imagery was obtained from a GE LS medical CT scanner at a local hospital and the Naval Research Laboratory's new HD-500 industrial CT scanner specifically designed for core sample imaging. The medical scanner provided images of stationary cores at 625-μm intervals with a rotating x-ray source and was able to resolve bubbles down to 625 μm in diameter. The industrial scanner provided images of rotating cores at 25-μm intervals with a stationary source and was able to resolve bubbles down to 10 μm in diameter.

  3. Realtime Gas Emission Monitoring at Hazardous Sites Using a Distributed Point-Source Sensing Infrastructure

    PubMed Central

    Manes, Gianfranco; Collodi, Giovanni; Gelpi, Leonardo; Fusco, Rosanna; Ricci, Giuseppe; Manes, Antonio; Passafiume, Marco

    2016-01-01

    This paper describes a distributed point-source monitoring platform for gas level and leakage detection in hazardous environments. The platform, based on a wireless sensor network (WSN) architecture, is organised into sub-networks to be positioned in the plant’s critical areas; each sub-net includes a gateway unit wirelessly connected to the WSN nodes, hence providing an easily deployable, stand-alone infrastructure featuring a high degree of scalability and reconfigurability. Furthermore, the system provides automated calibration routines which can be accomplished by non-specialized maintenance operators without system reliability reduction issues. Internet connectivity is provided via TCP/IP over GPRS (Internet standard protocols over mobile networks) gateways at a one-minute sampling rate. Environmental and process data are forwarded to a remote server and made available to authenticated users through a user interface that provides data rendering in various formats and multi-sensor data fusion. The platform is able to provide real-time plant management with an effective; accurate tool for immediate warning in case of critical events. PMID:26805832

  4. Momentum distribution of the uniform electron gas: Improved parametrization and exact limits of the cumulant expansion

    NASA Astrophysics Data System (ADS)

    Gori-Giorgi, Paola; Ziesche, Paul

    2002-12-01

    The momentum distribution of the unpolarized uniform electron gas in its Fermi-liquid regime, n(k,rs), with the momenta k measured in units of the Fermi wave number kF and with the density parameter rs, is constructed with the help of the convex Kulik function G(x). It is assumed that n(0,rs),n(1±,rs), the on-top pair density g(0,rs), and the kinetic energy t(rs) are known (respectively, from accurate calculations for rs=1,…,5, from the solution of the Overhauser model, and from quantum Monte Carlo calculations via the virial theorem). Information from the high- and the low-density limit, corresponding to the random-phase approximation and to the Wigner crystal limit, is used. The result is an accurate parametrization of n(k,rs), which fulfills most of the known exact constraints. It is in agreement with the effective-potential calculations of Takada and Yasuhara [Phys. Rev. B 44, 7879 (1991)], is compatible with quantum Monte Carlo data, and is valid in the density range rs≲12. The corresponding cumulant expansions of the pair density and of the static structure factor are discussed, and some exact limits are derived.

  5. [Determination and distribution of sulfur compounds in coked gasoline by gas chromatography-sulfur chemiluminescence detection].

    PubMed

    Yang, Yongtan; Wang, Zheng

    2007-05-01

    The method for the separation and determination of sulfur compounds in coked gasoline by gas chromatography-sulfur chemiluminescence detection (GC-SCD) was established. Seventy-four sulfur compounds including hydrogen sulfide, mercaptans, sulfides, disulfides, thiophene, alkyl thiophenes, benzothiophene, alkyl benzothiophenes in a coked gasoline sample were identified by standard samples and past identified results. The retention indexes of different sulfur compounds in coked gasoline under programmed temperature condition were calculated based on the retention times of hydrosulfide, ethyl mercaptan, n-propyl mercaptan, thiophene, 2-methyl thiophene, 2-ethylthiophene, 2-propylthiophene, C4-thiophene (t(R) = 40.28 min), benzothiophene, and methylbenzothiophene (t(R) = 58.13 min). The relative standard deviations of the determination results of main sulfur compounds (isopropyl mercaptan, n-propyl mercaptan, n-butyl mercaptan, 2-methylthiophene, 3-methylthiophene, 2, 4-dimethylthiophene, 2,3,4-trimethylthiophene) in coked gasoline were less than 5%, and the detection limit for sulfur was 0.05 mg/L. The linear range of sulfur was 0.2 - 400 mg/L for each sulfur compounds (r2 = 0. 999). The contents of sulfur compounds, especially the content of mercaptan, are much more than those in the catalytic gasoline. There is also a big difference in the sulfur contents between 2-methylthiophene and 3-methylthiophene. The data can be useful for the study of hydrodesulfurizing catalyst and industrial process planning. PMID:17679435

  6. GARROTXA Cosmological Simulations of Milky Way-sized Galaxies: General Properties, Hot-gas Distribution, and Missing Baryons

    NASA Astrophysics Data System (ADS)

    Roca-Fàbrega, Santi; Valenzuela, Octavio; Colín, Pedro; Figueras, Francesca; Krongold, Yair; Velázquez, Héctor; Avila-Reese, Vladimir; Ibarra-Medel, Hector

    2016-06-01

    We introduce a new set of simulations of Milky Way (MW)-sized galaxies using the AMR code ART + hydrodynamics in a Λ cold dark matter cosmogony. The simulation series is called GARROTXA and it follows the formation of a halo/galaxy from z = 60 to z = 0. The final virial mass of the system is ∼7.4 × 1011 M ⊙. Our results are as follows. (a) Contrary to many previous studies, the circular velocity curve shows no central peak and overall agrees with recent MW observations. (b) Other quantities, such as M\\_\\ast (6 × 1010 M ⊙) and R d (2.56 kpc), fall well inside the observational MW range. (c) We measure the disk-to-total ratio kinematically and find that D/T = 0.42. (d) The cold-gas fraction and star formation rate at z = 0, on the other hand, fall short of the values estimated for the MW. As a first scientific exploitation of the simulation series, we study the spatial distribution of hot X-ray luminous gas. We have found that most of this X-ray emitting gas is in a halo-like distribution accounting for an important fraction but not all of the missing baryons. An important amount of hot gas is also present in filaments. In all our models there is not a massive disk-like hot-gas distribution dominating the column density. Our analysis of hot-gas mock observations reveals that the homogeneity assumption leads to an overestimation of the total mass by factors of 3–5 or to an underestimation by factors of 0.7–0.1, depending on the used observational method. Finally, we confirm a clear correlation between the total hot-gas mass and the dark matter halo mass of galactic systems.

  7. The greenhouse gas balance of a drained fen peatland is mainly controlled by land-use rather than soil organic carbon content

    NASA Astrophysics Data System (ADS)

    Eickenscheidt, T.; Heinichen, J.; Drösler, M.

    2015-04-01

    Drained organic soils are considered as hotspots for greenhouse gas (GHG) emissions. Particularly arable lands and intensively used grasslands have been regarded as the main producers of carbon dioxide (CO2) and nitrous oxide (N2O). However, GHG balances of former peatlands and associated organic soils not considered as peatland according to the definition of the Intergovernmental Panel on Climate Change (IPCC) have not been investigated so far. Therefore, our study addressed the question to what extent the soil organic carbon (SOC) content affects the GHG release of drained organic soils under two different land-use types (arable land and intensively used grassland). Both land-use types were established on a mollic Gleysol (named Cmedium) as well as on a sapric Histosol (named Chigh). The two soil types significantly differed in their SOC contents in the topsoil (Cmedium: 9.4-10.9% SOC; Chigh: 16.1-17.2% SOC). We determined GHG fluxes (CO2, N2O and methane (CH4)) over a period of 2 years. The daily and annual net ecosystem exchange (NEE) of CO2 was determined with the closed dynamic chamber technique and by modeling the ecosystem respiration (RECO) and the gross primary production (GPP). N2O and CH4 were determined by the close chamber technique. Estimated NEE of CO2 significantly differed between the two land-use types with lower NEE values (-6 to 1707 g CO2-C m-2 yr-1) at the arable sites and higher values (1354 to 1823 g CO2-C m-2 yr-1) at the grassland sites. No effect on NEE was found regarding the SOC content. Significantly higher annual N2O exchange rates were observed at the arable sites (0.23-0.86 g N m-2 yr-1) compared to the grassland sites (0.12-0.31 g N m-2 yr-1). Furthermore, N2O fluxes from the Chigh sites significantly exceeded those of the Cmedium sites. CH4 fluxes were found to be close to zero at all plots. Estimated global warming potential, calculated for a time horizon of 100 years (GWP100) revealed a very high release of GHGs from all plots

  8. The greenhouse gas balance of a drained fen peatland is mainly controlled by land-use rather than soil organic carbon content

    NASA Astrophysics Data System (ADS)

    Eickenscheidt, T.; Heinichen, J.; Drösler, M.

    2015-09-01

    Drained organic soils are considered to be hotspots for greenhouse gas (GHG) emissions. Arable lands and intensively used grasslands, in particular, have been regarded as the main producers of carbon dioxide (CO2) and nitrous oxide (N2O). However, GHG balances of former peatlands and associated organic soils not considered to be peatland according to the definition of the Intergovernmental Panel on Climate Change (IPCC) have not been investigated so far. Therefore, our study addressed the question to what extent the soil organic carbon (SOC) content affects the GHG release of drained organic soils under two different land-use types (arable land and intensively used grassland). Both land-use types were established on a Mollic Gleysol (labeled Cmedium) as well as on a Sapric Histosol (labeled Chigh). The two soil types differed significantly in their SOC contents in the topsoil (Cmedium: 9.4-10.9 % SOC; Chigh: 16.1-17.2 % SOC). We determined GHG fluxes over a period of 1 or 2 years in case of N2O or methane (CH4) and CO2, respectively. The daily and annual net ecosystem exchange (NEE) of CO2 was determined by measuring NEE and the ecosystem respiration (RECO) with the closed dynamic chamber technique and by modeling the RECO and the gross primary production (GPP). N2O and CH4 were measured with the static closed chamber technique. Estimated NEE of CO2 differed significantly between the two land-use types, with lower NEE values (-6 to 1707 g CO2-C m-2 yr-1) at the arable sites and higher values (1354 to 1823 g CO2-C m-2 yr-1) at the grassland sites. No effect on NEE was found regarding the SOC content. Significantly higher annual N2O exchange rates were observed at the arable sites (0.23-0.86 g N m-2 yr-1) than at the grassland sites (0.12-0.31 g N m-2 yr-1). Furthermore, N2O fluxes from the Chigh sites significantly exceeded those of the Cmedium sites. CH4 fluxes were found to be close to zero at all plots. Estimated global warming potential, calculated for a time

  9. Numerical investigation of oxygen impurity distribution during multicrystalline silicon crystal growth using a gas flow guidance device

    NASA Astrophysics Data System (ADS)

    Teng, Ying-Yang; Chen, Jyh-Chen; Lu, Chung-Wei; Chen, Chi-Yung

    2012-12-01

    Oxygen is one of the most important types of impurities that can cause thermal donor or light-induced degradation in mc-Si solar cells. The objective of this study is to investigate the effect that installing a gas flow guidance device in a mc-Si crystal-growth furnace would have on the oxygen impurity distribution in the melt during the growth process. The installation of such a gas flow guidance device can enhance the gas flow near the free surface, which would allow the argon to carry a greater amount of evaporated SiO gas outside the furnace. Furthermore, the enhanced motion of the gas flow also improves heat transfer near the free surface, which would make the melt vortex separate more easily. The separated melt vortex, which is located near the central region of the melt-crystal interface, directs any oxygen impurity towards the central region of the melt-crystal interface. This is why the oxygen concentration can be reduced by installing the gas flow guidance device. The effectiveness of the gas flow guidance device depends on the vertical distance between it and the free surface (h) as well as the gap between the crucible sidewall and the tip of the device (d). The effect on the oxygen concentration in the melt is significant when smaller values for h and d are adopted.

  10. Performance enhancement of polymer electrolyte fuel cells by combining liquid removal mechanisms of a gas diffusion layer with wettability distribution and a gas channel with microgrooves

    NASA Astrophysics Data System (ADS)

    Utaka, Yoshio; Koresawa, Ryo

    2016-08-01

    Although polymer electrolyte fuel cells (PEFCs) are commercially available, there are still many problems that need to be addressed to improve their performance and increase their usage. At a high current density, generated water accumulates in the gas diffusion layer and in the gas channels of the cathode. This excess water obstructs oxygen transport, and as a result, cell performance is greatly reduced. To improve the cell performance, the effective removal of the generated water and the promotion of oxygen diffusion in the gas diffusion layer (GDL) are necessary. In this study, two functions proposed in previous reports were combined and applied to a PEFC: a hybrid GDL to form an oxygen diffusion path using a wettability distribution and a gas separator with microgrooves to enhance liquid removal. For a PEFC with a hybrid GDL and a gas separator with microgrooves, the concentration overvoltage of the PEFC was reduced, and the current density limit and maximum power density were increased compared with a conventional PEFC. Moreover, the stability of the cell voltage was markedly improved.

  11. Temperature distributions and thermal stresses in a graded zirconia/metal gas path seal system for aircraft gas turbine engines

    NASA Technical Reports Server (NTRS)

    Taylor, C. M.; Bill, R. C.

    1978-01-01

    A ceramic/metallic aircraft gas turbine outer gas path seal designed for improved engine performance was studied. Transient temperature and stress profiles in a test seal geometry were determined by numerical analysis. During a simulated engine deceleration cycle from sea-level takeoff to idle conditions, the maximum seal temperature occurred below the seal surface, therefore the top layer of the seal was probably subjected to tensile stresses exceeding the modulus of rupture. In the stress analysis both two- and three-dimensional finite element computer programs were used. Predicted trends of the simpler and more easily usable two-dimensional element programs were borne out by the three-dimensional finite element program results.

  12. Mapping distribution and thickness of supraglacial debris in the Central Karakoram National Park: main features and implications to model glacier meltwater

    NASA Astrophysics Data System (ADS)

    Minora, Umberto; Mayer, Christoph; Bocchiola, Daniele; D'Agata, Carlo; Maragno, Davide; Lambrecht, Astrid; Vuillermoz, Elisa; smiraglia, claudio; diolaiuti, guglielmina

    2014-05-01

    Supraglacial debris plays a not negligible role in controlling magnitude and rates of buried ice melt (Østrem, 1959; Mattson et al., 1993). Knowledge on rock debris is essential to model ice melt (and consequently meltwater discharge) upon wide glacierized areas, as melt rates are mainly driven by debris thickness variability. This is particularly important for the Pamir-Himalaya-Karakoram area (PHK), where debris-covered glaciers are frequent (Smiraglia et al., 2007; Scherler et al., 2011) and where melt water from glaciers supports agriculture and hydropower production. By means of remote sensing techniques and field data, supraglacial debris can be detected, and then quantified in area and thickness. Supervised classifications of satellite imagery can be used to map debris on glaciers. They use different algorithms to cluster an image based on its pixel values, and Region Of Interests (ROIs) previously selected by the human operator. This can be used to obtain a supraglacial debris mask by which surface extension can be calculated. Moreover, kinetic surface temperature data derived from satellites (such as ASTER and Landsat), can be used to quantify debris thicknesses (Mihalcea et al., 2008). Ground Control Points (GCPs) are essential to validate the obtained debris thicknesses. We took the Central Karakoram National Park (CKNP) as a representative sample for PHK area. The CKNP is 12,000 km2 wide, with more than 700 glaciers, mostly debris covered (Minora et al., 2013). Among those we find some of the widest glaciers of the World (e.g: Baltoro). To improve the knowledge on these glaciers and to better model their melt and water discharge we proceeded as follows. Firstly we ran a Supervised Maximum Likelihood (SML) classification on 2001 and 2010 Landsat images to detect debris presence and distribution. Secondly we analyzed kinetic surface temperature (from Landsat) to map debris depth. This latter attempt took also advantage from field data of debris thickness

  13. Characterization of industrial waste from a natural gas distribution company and management strategies: a case study of the East Azerbaijan Gas Company (Iran).

    PubMed

    Taghipour, Hassan; Aslhashemi, Ahmad; Assadi, Mohammad; Khodaei, Firoz; Mardangahi, Baharak; Mosaferi, Mohammad; Roshani, Babak

    2012-10-01

    Although a fundamental prerequisite for the successful implementation of any waste management plan is the availability of sufficient and accurate data, there are few available studies regarding the characterization and management of gas distribution company waste (GDCW). This study aimed to characterize the industrial waste generated by the East Azerbaijan Gas Distribution Company (EAGDC) and to present environmental management strategies. The EAGDC serves 57 cities and 821 villages with a total population of more than 2.5 million as well as numerous industrial units. The methodology of this study was based on a checklist of data collected from each zone of the company, site visits (observation), and quantity and quality analysis according to the formal data available from different zones. The results indicate that more than 35 different kinds of industrial solid waste are generated in different industrial installations. The most important types of generated waste include empty barrels (including mercaptans, diesel fuel, deionized waters and oil), faulty gas meters and regulators, a variety of industrial oils, sleeves, filter elements and faulty pipes, valves and fittings. The results indicated that, currently, GDCW is generally handled and disposed of with domestic waste, deposited in companies' installation yards and stores or, sometimes, recycled through non-scientific approaches that can create health risks to the public and the environment, even though most of the GDCW was determined to be recyclable or reusable materials. This study concludes that gas distribution companies must pay more attention to source reduction, recycling and reusing of waste to preserve natural resources, landfill space and the environment. PMID:22683949

  14. Gas- and particle-phase distribution of polycyclic aromatic hydrocarbons in two-stroke, 50-cm 3 moped emissions

    NASA Astrophysics Data System (ADS)

    Spezzano, Pasquale; Picini, Paolo; Cataldi, Dario

    Gas- and particle-phase polycyclic aromatic hydrocarbons (PAHs) concentrations evaluated in the exhaust of 10 two-stroke, 50-cm 3 mopeds belonging to three different levels of emission legislation (EURO-0, EURO-1 and EURO-2) were used to assess the prevalent mechanism driving the gas/particle partitioning of PAHs in moped exhaust. Sampling was performed on a dynamometer bench both during the "cold-start" and the "hot" phases of the ECE-47 driving cycle. Gas and particulate phase PAHs were collected on polyurethane foam (PUF) plugs and 47-mm Pallflex T60A20 filters, respectively, under isokinetic conditions by using sampling probes inserted into the dilution tunnel of a Constant Volume Sampling - Critical Flow Venturi (CVS-CFV) system. The results show that semi-volatile PAHs were predominantly partitioned to the particle phase. The soluble organic fraction (SOF) of the collected particulates ranged between 72 and 98%. Measured total suspended particulate matter normalized partition coefficients ( Kp) were predicted within a factor of 3-5 by assuming absorption into the organic fraction according to a model developed by Harner and Bidleman [Harner, T., Bidleman, T.F., 1998. Octanol-air partition coefficient for describing particle/gas partitioning of aromatic compounds in urban air. Environmental Science & Technology 32, 1494-1502.]. This suggests that the gas/particle partitioning in moped exhaust is mainly driven by the high fraction of organic matter of the emitted particles and that absorption could be the main partitioning mechanism of PAHs.

  15. The Carina Nebula and Gum 31 molecular complex - I. Molecular gas distribution, column densities, and dust temperatures

    NASA Astrophysics Data System (ADS)

    Rebolledo, David; Burton, Michael; Green, Anne; Braiding, Catherine; Molinari, Sergio; Wong, Graeme; Blackwell, Rebecca; Elia, Davide; Schisano, Eugenio

    2016-03-01

    We report high-resolution observations of the 12CO(1-0) and 13CO(1-0) molecular lines in the Carina Nebula and the Gum 31 region obtained with the 22-m Mopra telescope as part of The Mopra Southern Galactic Plane CO Survey. We cover 8 deg2 from l = 285° to 290°, and from b = -1.5° to +0.5°. The molecular gas column density distributions from both tracers have a similar range of values. By fitting a grey-body function to the observed infrared spectral energy distribution from Herschel maps, we derive gas column densities and dust temperatures. The gas column density has values in the range from 6.3 × 1020 to 1.4 × 1023 cm-2, while the dust temperature has values in the range from 17 to 43 K. The gas column density derived from the dust emission is approximately described by a lognormal function for a limited range of column densities. A high-column-density tail is clearly evident for the gas column density distribution, which appears to be a common feature in regions with active star formation. There are regional variations in the fraction of the mass recovered by the CO emission lines with respect to the total mass traced by the dust emission. These variations may be related to changes in the radiation field strength, variation of the atomic to molecular gas fraction across the observed region, differences in the CO molecule abundance with respect to H2, and evolutionary stage differences of the molecular clouds that compose the Carina Nebula-Gum 31 complex.

  16. Obtaining the cumulative k-distribution of a gas mixture from those of its components. [radiative transfer in stratosphere

    NASA Technical Reports Server (NTRS)

    Gerstell, M. F.

    1993-01-01

    A review of the convolution theorem for obtaining the cumulative k-distribution of a gas mixture proven in Goody et al. (1989) and a discussion of its application to natural spectra are presented. Computational optimizations for use in analyzing high-altitude gas mixtures are introduced. Comparisons of the results of the optimizations, and criteria for deciding what altitudes are 'high' in this context are given. A few relevant features of the testing support software are examined. Some spectrally integrated results, and the circumstances the might permit substituting the method of principal absorbers are examined.

  17. Evaluation of cased and uncased gas distribution and transmission piping under railroads and highways, Phase 2. Annual report, November 1987

    SciTech Connect

    O'Rourke, T.D.; Stewart, H.E.; Ingraffea, A.R.; Nyman, K.J.; Crossley, C.W.

    1987-11-01

    A comprehensive methodology is being developed for evaluating stresses in natural gas pipelines at railroad and highway crossings. The methodology accounts for soil-structure interaction and the three-dimensional distribution of pipeline stresses. The methodology involves delineating field loads and geometries through detailed site observations and discussions with industry personnel, and using computer graphics to analyze pipeline stresses under the complex three-dimensional conditions which prevail in the field. Field experiments will be performed to substantiate the predicted pipeline stresses at railroad crossings. Guidelines will be developed for pipeline crossings acceptable to representatives of gas, railroad, and highway industries.

  18. 49 CFR 192.1005 - What must a gas distribution operator (other than a master meter or small LPG operator) do to...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false What must a gas distribution operator (other than a master meter or small LPG operator) do to implement this subpart? 192.1005 Section 192.1005...) § 192.1005 What must a gas distribution operator (other than a master meter or small LPG operator) do...

  19. 49 CFR 192.1005 - What must a gas distribution operator (other than a master meter or small LPG operator) do to...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false What must a gas distribution operator (other than a master meter or small LPG operator) do to implement this subpart? 192.1005 Section 192.1005...) § 192.1005 What must a gas distribution operator (other than a master meter or small LPG operator) do...

  20. 49 CFR 192.1005 - What must a gas distribution operator (other than a master meter or small LPG operator) do to...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false What must a gas distribution operator (other than a master meter or small LPG operator) do to implement this subpart? 192.1005 Section 192.1005...) § 192.1005 What must a gas distribution operator (other than a master meter or small LPG operator) do...

  1. 49 CFR 192.1005 - What must a gas distribution operator (other than a master meter or small LPG operator) do to...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 3 2010-10-01 2010-10-01 false What must a gas distribution operator (other than a master meter or small LPG operator) do to implement this subpart? 192.1005 Section 192.1005...) § 192.1005 What must a gas distribution operator (other than a master meter or small LPG operator) do...

  2. 49 CFR 192.1005 - What must a gas distribution operator (other than a master meter or small LPG operator) do to...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false What must a gas distribution operator (other than a master meter or small LPG operator) do to implement this subpart? 192.1005 Section 192.1005...) § 192.1005 What must a gas distribution operator (other than a master meter or small LPG operator) do...

  3. Activity, distribution, and abundance of methane-oxidizing bacteria in the near surface soils of onshore oil and gas fields.

    PubMed

    Xu, Kewei; Tang, Yuping; Ren, Chun; Zhao, Kebin; Wang, Wanmeng; Sun, Yongge

    2013-09-01

    Methane-oxidizing bacteria (MOB) have long been used as an important biological indicator for oil and gas prospecting, but the ecological characteristics of MOB in hydrocarbon microseep systems are still poorly understood. In this study, the activity, distribution, and abundance of aerobic methanotrophic communities in the surface soils underlying an oil and gas field were investigated using biogeochemical and molecular ecological techniques. Measurements of potential methane oxidation rates and pmoA gene copy numbers showed that soils inside an oil and gas field are hot spots of methane oxidation and MOB abundance. Correspondingly, terminal restriction fragment length polymorphism analyses in combination with cloning and sequencing of pmoA genes also revealed considerable differences in the methanotrophic community composition between oil and gas fields and the surrounding soils. Principal component analysis ordination furthermore indicated a coincidence between elevated CH4 oxidation activity and the methanotrophic community structure with type I methanotrophic Methylococcus and Methylobacter, in particular, as indicator species of oil and gas fields. Collectively, our results show that trace methane migrated from oil and gas reservoirs can considerably influence not only the quantity but also the structure of the methanotrophic community. PMID:23090054

  4. Investigating Friction as a Main Source of Entropy Generation in the Expansion of Confined Gas in a Piston-and-Cylinder Device

    ERIC Educational Resources Information Center

    Kang, Dun-Yen; Liou, Kai-Hsin; Chang, Wei-Lun

    2015-01-01

    The expansion or compression of gas confined in a piston-and-cylinder device is a classic working example used for illustrating the First and Second Laws of Thermodynamics. The balance of energy and entropy enables the estimation of a number of thermodynamic properties. The entropy generation (also called entropy production) resulting from this…

  5. Temperature and electron density distributions of laser-induced plasmas generated with an iron sample at different ambient gas pressures

    NASA Astrophysics Data System (ADS)

    Aguilera, J. A.; Aragón, C.

    2002-09-01

    Intensity, temperature and electron density distributions of laser-induced plasmas (LIPs) have been measured by emission spectroscopy with two-dimensional spatial resolution and temporal resolution. The plasmas have been generated with an iron sample at different pressures of air, in the range 10-1000 mbar. An experimental system based in an imaging spectrometer equipped with an intensified CCD detector has been used to obtain the spectra with two-dimensional spatial resolution. The evolution of the intensity distributions is described by the blast wave model only at initial times. The temperature distributions are shown to correspond to a slight difference between the intensity distributions of two Fe I emission lines that have a high difference of their upper energy levels (3.38 eV). The electron density distributions have similar features to those of the temperature distributions. The features of the intensity and temperature distributions show a significant change with the ambient gas pressure: they have separated maxima in the plasmas generated at pressures below 100 mbar, whereas at higher pressures, the maxima of the two distributions coincide.

  6. Steady temperature and density distributions in a gas containing heat sources

    NASA Technical Reports Server (NTRS)

    Davison, H. W.

    1971-01-01

    Computer program, STADDIG, is based on steady state, one dimensional heat transfer calculation using cylindrical coordinates. Program allows for conduction across gas and container walls. Heat is dissipated from walls by forced convection cooling with incompressible coolant. Heat sources are included in coolant, gas, and walls.

  7. A new systems approach to optimizing investments in gas production and distribution

    SciTech Connect

    Dougherty, E.L.

    1983-03-01

    This paper presents a new analytical approach for determining the optimal sequence of investments to make in each year of an extended planning horizon in each of a group of reservoirs producing gas and gas liquids through an interconnected trunkline network and a gas processing plant. The optimality criterion is to maximize net present value while satisfying fixed offtake requirements for dry gas, but with no limits on gas liquids production. The planning problem is broken into n + 2 separate but interrelated subproblems; gas reservoir development and production, gas flow in a trunkline gathering system, and plant separation activities to remove undesirable gas (CO/sub 2/) or to recover valuable liquid components. The optimal solution for each subproblem depends upon the optimal solutions for all of the other subproblems, so that the overall optimal solution is obtained iteratively. The iteration technique used is based upon a combination of heuristics and the decompostion algorithm of mathematical programming. Each subproblem is solved once during each overall iteration. In addition to presenting some mathematical details of the solution approach, this paper describes a computer system which has been developed to obtain solutions.

  8. Evaluation of distributed gas cooling of pressurized PAFC for utility power generation

    NASA Technical Reports Server (NTRS)

    Farooque, M.; Hooper, M.; Maru, H.

    1981-01-01

    A proof-of-concept test for a gas-cooled pressurized phosphoric acid fuel cell is described. After initial feasibility studies in short stacks, two 10 kW stacks are tested. Progress includes: (1) completion of design of the test stations with a recirculating gas cooling loop; (2) atmospheric testing of the baseline stack.

  9. Peculiarities of distribution of gas-dynamic manifestations in mines of the Kuznetsk coal basin by days of the weekly cycle

    SciTech Connect

    Oparin, V.N.; Ludzish, V.S.; Kulakov, G.I.; Rudakov, V.A.

    2005-04-01

    The peculiarities of the origin of gas-dynamic events (rock, coal, and gas outbursts, methane ignition) in the Kuznetsk Basin mines in 1988 - 2004 are analyzed. A review is presented for information on recent accident and injury rate caused by disastrous gas-dynamic manifestations. The effect of bimodal frequency distribution of gas-dynamic events generated by explosion and burning of methane is revealed within a generalized weekly cycle.

  10. Gas and RRR distribution in high purity Niobium EB welded in Ultra-High Vacuum

    SciTech Connect

    Anakhov, S.; Singer, X.; Singer, W.; Wen, H.

    2006-05-24

    Electron beam (EB) welding in UHV (ultra-high vacuum, 10-5 divide 10-8 mbar) is applied in the standard fabrication of high gradient niobium superconducting radio frequency (SRF) cavities of TESLA design. The quality of EB welding is critical for cavity performance. Experimental data of gas content (H2, O2, N2) and RRR (residual resistivity ratio) measurements in niobium (Nb) welding seams are presented. EB welding in UHV conditions allow to preserve low gas content (1 divide 3 wt. ppm hydrogen and 5 divide 7 ppm oxygen and nitrogen), essential for high values of RRR - 350 divide 400 units. Gas content redistribution in the electron beam welded and heat affected region take place in the welding process. Correlation between gas solubility parameters, RRR and thermal conductivity are presented. Mechanisms of gas solubility in EB welding process are discussed.

  11. Application of the Junge- and Pankow-equation for estimating indoor gas/particle distribution and exposure to SVOCs

    NASA Astrophysics Data System (ADS)

    Salthammer, Tunga; Schripp, Tobias

    2015-04-01

    In the indoor environment, distribution and dynamics of an organic compound between gas phase, particle phase and settled dust must be known for estimating human exposure. This, however, requires a detailed understanding of the environmentally important compound parameters, their interrelation and of the algorithms for calculating partitioning coefficients. The parameters of major concern are: (I) saturation vapor pressure (PS) (of the subcooled liquid); (II) Henry's law constant (H); (III) octanol/water partition coefficient (KOW); (IV) octanol/air partition coefficient (KOA); (V) air/water partition coefficient (KAW) and (VI) settled dust properties like density and organic content. For most of the relevant compounds reliable experimental data are not available and calculated gas/particle distributions can widely differ due to the uncertainty in predicted Ps and KOA values. This is not a big problem if the target compound is of low (<10-6 Pa) or high (>10-2 Pa) volatility, but in the intermediate region even small changes in Ps or KOA will have a strong impact on the result. Moreover, the related physical processes might bear large uncertainties. The KOA value can only be used for particle absorption from the gas phase if the organic portion of the particle or dust is high. The Junge- and Pankow-equation for calculating the gas/particle distribution coefficient KP do not consider the physical and chemical properties of the particle surface area. It is demonstrated by error propagation theory and Monte-Carlo simulations that parameter uncertainties from estimation methods for molecular properties and variations of indoor conditions might strongly influence the calculated distribution behavior of compounds in the indoor environment.

  12. The distribution of warm gas in the G327.3-0.6 massive star-forming region

    NASA Astrophysics Data System (ADS)

    Leurini, S.; Wyrowski, F.; Herpin, F.; van der Tak, F.; Güsten, R.; van Dishoeck, E. F.

    2013-02-01

    Aims: Most studies of high-mass star formation focus on massive and/or luminous clumps, but the physical properties of their larger scale environment are poorly known. In this work, we aim at characterising the effects of clustered star formation and feedback of massive stars on the surrounding medium by studying the distribution of warm gas through mid-J12CO and 13CO observations. Methods: We present APEX 12CO(6-5), (7-6), 13CO(6-5), (8-7) and HIFI 13CO(10-9) maps of the star forming region G327.36-0.6 with a linear size of ~3 pc × 4 pc. We infer the physical properties of the emitting gas on large scales through a local thermodynamic equilibrium analysis, while we apply a more sophisticated large velocity gradient approach on selected positions. Results: Maps of all lines are dominated in intensity by the photon dominated region around the Hii region G327.3-0.5. Mid-J12CO emission is detected over the whole extent of the maps with excitation temperatures ranging from 20 K up to 80 K in the gas around the Hii region, and H2 column densities from few 1021 cm-2 in the inter-clump gas to 3 × 1022 cm-2 towards the hot core G327.3-0.6. The warm gas (traced by 12 and 13CO(6-5) emission) is only a small percentage (~10%) of the total gas in the infrared dark cloud, while it reaches values up to ~35% of the total gas in the ring surrounding the Hii region. The 12CO ladders are qualitatively compatible with photon dominated region models for high density gas, but the much weaker than predicted 13CO emission suggests that it comes from a large number of clumps along the line of sight. All lines are detected in the inter-clump gas when averaged over a large region with an equivalent radius of 50''(~0.8 pc), implying that the mid-J12CO and 13CO inter-clump emission is due to high density components with low filling factor. Finally, the detection of the 13CO(10-9) line allows to disentangle the effects of gas temperature and gas density on the CO emission, which are

  13. Methane Content and Distribution of Natural Gas Hydrate Accumulations in the Deep-Water Basins of the Bering Sea

    NASA Astrophysics Data System (ADS)

    Barth, G. A.; Scholl, D. W.; Childs, J. R.

    2005-12-01

    Seismic reflection images from the deep-water (>3500 m) Aleutian and Bowers Basins of the Bering Sea indicate an abundant presence of natural gas and gas hydrate. Distinctive velocity-amplitude anomalies, or VAMPs, stand out as both velocity pseudostructures and gas bright spots within the otherwise horizontal and uniform sedimentary reflection sequences. These are interpreted as methane chimneys overlain by interstitial gas hydrate caps. Hundreds of VAMPs have been imaged throughout the Bering Sea; several thousand are inferred to exist. Ongoing USGS development of an interpretive seismic database presents an opportunity to quantify the hydrate content of individual VAMPs and to explore the distribution of major and minor anomalies relative to basement topography, silica diagenesis features, ancient subduction boundary structures and sediment sources. We present quantitative estimates of the size and methane content of representative large VAMP structures, based on seismic reflection interval-time anomalies. Time-average and frame-component effective medium velocity models are used to relate hydrate concentration to velocity anomaly. For this specific case, differences between the two models are minimal for hydrate concentrations <35% of pore space. To facilitate modeling of sediment dominated by diatomaceous ooze, grain-scale elastic moduli for diatom frustules are back-calculated to be ~5 GPa, assuming shear and bulk modulus are equal. Maximum velocity anomaly observed within the VAMPs is +235 m/s in the hydrate zone, relative to a background P-wave velocity of 1600 m/s. This corresponds to hydrate concentration ~40% of pore space (or ~20% of bulk rock). Hydrate distribution appears to be lithologically controlled within a section of alternating turbidite and diatomaceous sediments. It is preferentially located in a zone ~40 to 90 m above the gas hydrate BSR. Free gas is most concentrated immediately below the hydrate BSR, which lies at ~360 m bsf. Evidence for

  14. Reconstruction of combustion temperature and gas concentration distributions using line-of-sight tunable diode laser absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Zhirong; Sun, Pengshuai; Pang, Tao; Xia, Hua; Cui, Xiaojuan; Li, Zhe; Han, Luo; Wu, Bian; Wang, Yu; Sigrist, Markus W.; Dong, Fengzhong

    2016-07-01

    Spatial temperature and gas concentration distributions are crucial for combustion studies to characterize the combustion position and to evaluate the combustion regime and the released heat quantity. Optical computer tomography (CT) enables the reconstruction of temperature and gas concentration fields in a flame on the basis of line-of-sight tunable diode laser absorption spectroscopy (LOS-TDLAS). A pair of H2O absorption lines at wavelengths 1395.51 and 1395.69 nm is selected. Temperature and H2O concentration distributions for a flat flame furnace are calculated by superimposing two absorption peaks with a discrete algebraic iterative algorithm and a mathematical fitting algorithm. By comparison, direct absorption spectroscopy measurements agree well with the thermocouple measurements and yield a good correlation. The CT reconstruction data of different air-to-fuel ratio combustion conditions (incomplete combustion and full combustion) and three different types of burners (one, two, and three flat flame furnaces) demonstrate that TDLAS has the potential of short response time and enables real-time temperature and gas concentration distribution measurements for combustion diagnosis.

  15. High-Resolution Seismic Definition of the Distribution of Gas in the West Svalbard Margin

    NASA Astrophysics Data System (ADS)

    Minshull, T. A.; Westbrook, G. K.; Marin-Moreno, H.; Marsset, B.; Ker, S.; Sarkar, S.; Vardy, M. E.; Henstock, T.

    2014-12-01

    The widespread presence of gas beneath the seabed west of Svalbard is shown by negative-polarity high-amplitude reflectors (nephars), imaged in high-resolution near-surface and deep-towed seismic reflection data. The principal controls on the presence of gas are the gas hydrate stability zone (GHSZ), from which free gas is generally excluded, and stratigraphic control of permeable layers. A widespread bottom-simulating reflector (BSR) beneath the lower-mid continental slope indicates gas at the base of the GHSZ. The depth of the base of the GHSZ predicted by a numerical model that takes in to account variation in ocean temperature over the past two thousand years, is consistent with the depth of the BSR, even at its shallowest depth, where a steady-state model places base of the GHSZ shallower than the BSR. Similarly, farther up slope, where the BSR loses it coherency, the depths of the shallowest nephars are compatible with the predicted depth of the base of the GHSZ from the time-dependent model, but are about three times deeper than the predicted steady-state depth of the BSR. This approach to defining the limits of the GHSZ is not precise, as it depends upon the presence of gas. In the shallow sediment sequence, which has a high proportion of glacigenic sediments, gas is restricted to a smaller number of permeable units than in the contourite-dominated sequence farther down the continental slope. Where the seabed is shallower than the GHSZ, numerous plumes of methane gas ascend from the seabed, and gas, which has migrated up slope through dipping permeable layers, locally ponds beneath a thin veneer of unconformable glacial and post-glacial sediments on the continental shelf.

  16. Gas-Phase Photoemission With Soft X-Rays: Cross Sections And Angular Distributions

    NASA Astrophysics Data System (ADS)

    Shirley, D. A.; Kobrin, P. H.; Truesdale, C. M.; Lindle, D. W.; F errett, T. A.; Heimann, P. A.; Becker, U.; Kerkhoff, H. G.; Southworth, S. H.

    1984-03-01

    A summary is presented of typical gas-phase photoemission studies based on synchrotron radiation in the 50-5000 eV range, using beam lines at the Stanford Synchrotron Radiation Laboratory. Three topics are addressed: atomic inner-shell photoelectron cross sections and asymmetries, correlation peaks in rare gases, and core-level shape resonances in molecules. Photoelectron cross-section a(nZ) and asymmetry-parameter a(n0 studies in mercury vapor at photon energies up to 270 eV (up to 600 eV for a4f) extend coverage of these parameters to n<5 and 5<3. Comparison with Dirac-Slater and relativistic random-phase approximation calculations reveals systematic discrepancies. For example, distinct Cooper minima in a(n iZ,) are observed but not predicted, while predicted a(n9) values are typically too high. Correlation satellites have been studied for the K shells of helium (hv = 68-90 eV), neon (hv = 870-960 eV) and argon (hv = 3200-3320 eV). In helium the n=2 satellite peak was shown to have mainly 2p character at threshold, and its asymmetry was measured through the autoionizing resonance region. Tentative evidence was obtained that the neon satellites are less intense near threshold than in the high-energy limit, and that their intensities stay constant or decrease with increasing energy near threshold. A new satellite was observed in argon at 24.6 eV which appears to increase in intensity with energy. Molecular core-level shape resonances were observed for the first time by photoemission, yielding a(hv) and a(hv) for core levels from 180 eV binding energy (S 2p in SF6 and OCS) through C is in CO, CO2 and CF4, N ls in N2 and NO, and 0 is in CO and CO2 to 2490 eV (S ls in SF6). Several conclusions can be drawn about the photoelectron and Auger cross sections and asymmetry parameters.

  17. ATLASGAL - Kinematic distances and the dense gas mass distribution of the inner Galaxy

    NASA Astrophysics Data System (ADS)

    Wienen, M.; Wyrowski, F.; Menten, K. M.; Urquhart, J. S.; Csengeri, T.; Walmsley, C. M.; Bontemps, S.; Russeil, D.; Bronfman, L.; Koribalski, B. S.; Schuller, F.

    2015-07-01

    Context. The formation of high mass stars and clusters occurs in giant molecular clouds. Objects in evolved stages of massive star formation such as protostars, hot molecular cores, and ultracompact HII regions have been studied in more detail than earlier, colder objects. Further progress thus requires the analysis of the time before massive protostellar objects can be probed by their infrared emission. With this in mind, the APEX Telescope Large Area Survey of the whole inner Galactic plane at 870 μm (ATLASGAL) has been carried out to provide a global view of cold dust and star formation at submillimetre wavelengths. Aims: We derive kinematic distances to a large sample of massive cold dust clumps from their measured line velocities. We estimate masses and sizes of ATLASGAL sources, for which the kinematic distance ambiguity is resolved. Methods: The ATLASGAL sample is divided into groups of sources, which are located close together, mostly within a radius of 2 pc, and have velocities in a similar range with a median velocity dispersion of ~1 km s-1. We use NH3, N2H+, and CS velocities to calculate near and far kinematic distances to those groups. Results: We obtain 296 groups of ATLASGAL sources in the first quadrant and 393 groups in the fourth quadrant, which are coherent in space and velocity. We analyse HI self-absorption and HI absorption to resolve the kinematic distance ambiguity to 689 complexes of submm clumps. They are associated with 12CO emission probing large-scale structure and 13CO (1-0) line as well as the 870 μm dust continuum on a smaller scale. We obtain a scale height of ~28 ± 2 pc and displacement below the Galactic midplane of ~-7 ± 1 pc. Within distances from 2 to 18 kpc ATLASGAL clumps have a broad range of gas masses with a median of 1050 M⊙ as well as a wide distribution of radii with a median of 0.4 pc. Their distribution in galactocentric radii is correlated with spiral arms. Conclusions: Using a statistically significant

  18. Effects of Burnup and Temperature Distributions to CANDLE Burnup of Block-Type High Temperature Gas Cooled Reactor

    SciTech Connect

    Yasunori Ohoka; Ismile; Hiroshi Sekimoto

    2004-07-01

    The CANDLE burnup strategy is a new reactor burnup concept, where the distributions of fuel nuclide densities, neutron flux, and power density move with the same constant speed along the core axis from bottom to top or from top to bottom of the core and without any change in their shapes. It can be applied easily to the block-type high temperature gas cooled reactor using an appropriate burnable poison mixed with uranium oxide fuel. In the present study, the burnup distribution and the temperature distribution in the core are investigated and their effects on the CANDLE burnup core characteristics are studied. In this study, the natural gadolinium is used as the burnable poison. With the fuel enrichment of 15%, the natural gadolinium concentration of 3.0% and the fuel pin pitch of 6.6 cm, the CANDLE burnup is realized with the burning region moving speed of 29 cm/year and the axial half width of power density distribution of 1.5 m for uniform group constant case at 900 K. When the effect of nuclide change by burnup is considered, the burning region speed becomes 25 cm/year and the axial half-width of power density distribution becomes 1.25 m. When the temperature distributions effect is considered, the effects on the core characteristics are smaller than the burnup distribution effect. The maximum fuel temperature of the parallel flow case is higher than the counter flow case. (authors)

  19. Variability of Disk Emission in Pre-Main Sequence and Related Stars. II. Variability in the Gas and Dust Emission of the Herbig Fe Star SAO 206462

    NASA Technical Reports Server (NTRS)

    Sitko, Michael L.; Day, Amanda N.; Kimes, Robin L.; Beerman, Lori C.; Martus, Cameron; Lynch, David K.; Russell, Ray W.; Grady, Carol A.; Schneider, Glenn; Lisse, Carey M.; Nuth, Joseph A.; Cure, Michel; Henden, Arne A.; Kraus, Stefan; Motta, Veronica; Tamura Motohide; Hornbeck, Jeremy; Williger, Gerard M.; Fugazza, Dino

    2011-01-01

    We present thirteen epochs of near-infrared (0.8-5 microns) spectroscopic observations of the pre-transitional, "gapped" disk system in SAO 206462 (=HD 135344B). In all, six gas emission lines (Br(alpha) , Br(gamma), Pa(beta), Pa(delta), Pa(epsilon), and the 0.8446 microns line of O I) along with continuum measurements made near the standard J, H, K, and L photometric bands were measured. A mass accretion rate of approximately 2 x 10(exp 8)Solar Mass/yr was derived from the Br(gamma) and Pa(beta) lines. However, the fluxes of these lines varied by a factor of over two during the course of a few months. The continuum also varied, but by only approx.30%, and even decreased at a time when the gas emission was increasing. The H I line at 1.083 microns was also found to vary in a manner inconsistent with that of either the hydrogen lines or the dust. Both the gas and dust variabilities indicate significant changes in the region of the inner gas and the inner dust belt that may be common to many young disk systems. If planets are responsible for defining the inner edge of the gap, they could interact with the material on time scales commensurate with what is observed for the variations in the dust, while other disk instabilities (thermal, magneto-rotational) would operate there on longer time scales than we observe for the inner dust belt. For SAO 206462, the orbital period would likely be 1-3 years. If the changes are being induced in the disk material closer to the star than the gap, a variety of mechanisms (disk instabilities, interactions via planets) might be responsible for the changes seen. The He I feature is most likely due to a wind whose orientation changes with respect to the observer on time scales of a day or less. To further constrain the origin of the gas and dust emission will require multiple spectroscopic and interferometric observations on both shorter and longer time scales that have been sampled so far.

  20. VARIABILITY OF DISK EMISSION IN PRE-MAIN SEQUENCE AND RELATED STARS. II. VARIABILITY IN THE GAS AND DUST EMISSION OF THE HERBIG Fe STAR SAO 206462

    SciTech Connect

    Sitko, Michael L.; Day, Amanda N.; Kimes, Robin L.; Beerman, Lori C.; Martus, Cameron; and others

    2012-01-20

    We present 13 epochs of near-infrared (0.8-5 {mu}m) spectroscopic observations of the pre-transitional, 'gapped' disk system in SAO 206462 (=HD 135344B). In all, six gas emission lines (Br{alpha}, Br{gamma}, Pa{beta}, Pa{gamma}, Pa{delta}, Pa{epsilon}, and the 0.8446 {mu}m line of O I) along with continuum measurements made near the standard J, H, K, and L photometric bands were measured. A mass accretion rate of approximately 2 Multiplication-Sign 10{sup -8} M{sub Sun} yr{sup -1} was derived from the Br{gamma} and Pa{beta} lines. However, the fluxes of these lines varied by a factor of over two during the course of a few months. The continuum also varied, but by only {approx}30%, and even decreased at a time when the gas emission was increasing. The H I line at 1.083 {mu}m was also found to vary in a manner inconsistent with that of either the hydrogen lines or the dust. Both the gas and dust variabilities indicate significant changes in the region of the inner gas and the inner dust belt that may be common to many young disk systems. If planets are responsible for defining the inner edge of the gap, they could interact with the material on timescales commensurate with what is observed for the variations in the dust, while other disk instabilities (thermal, magnetorotational) would operate there on longer timescales than we observe for the inner dust belt. For SAO 206462, the orbital period would likely be 1-3 years. If the changes are being induced in the disk material closer to the star than the gap, a variety of mechanisms (disk instabilities, interactions via planets) might be responsible for the changes seen. The He I feature is most likely due to a wind whose orientation changes with respect to the observer on timescales of a day or less. To further constrain the origin of the gas and dust emission will require multiple spectroscopic and interferometric observations on both shorter and longer timescales that have been sampled so far.

  1. The alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE and cosmo-OWLS simulations

    NASA Astrophysics Data System (ADS)

    Velliscig, Marco; Cacciato, Marcello; Schaye, Joop; Crain, Robert A.; Bower, Richard G.; van Daalen, Marcel P.; Dalla Vecchia, Claudio; Frenk, Carlos S.; Furlong, Michelle; McCarthy, I. G.; Schaller, Matthieu; Theuns, Tom

    2015-10-01

    We report the alignment and shape of dark matter, stellar, and hot gas distributions in the EAGLE (Evolution and Assembly of GaLaxies and their Environments) and cosmo-OWLS (OverWhelmingly Large Simulations) simulations. The combination of these state-of-the-art hydrodynamical cosmological simulations enables us to span four orders of magnitude in halo mass (11 ≤ log10(M200/[ h-1 M⊙]) ≤ 15), a wide radial range (-2.3 ≤ log10(r/[ h-1 Mpc]) ≤ 1.3) and redshifts 0 ≤ z ≤ 1. The shape parameters of the dark matter, stellar and hot gas distributions follow qualitatively similar trends: they become more aspherical (and triaxial) with increasing halo mass, radius, and redshift. We measure the misalignment of the baryonic components (hot gas and stars) of galaxies with their host halo as a function of halo mass, radius, redshift, and galaxy type (centrals versus satellites and early- versus late-type). Overall, galaxies align well with the local distribution of the total (mostly dark) matter. However, the stellar distributions on galactic scales exhibit a median misalignment of about 45-50 deg with respect to their host haloes. This misalignment is reduced to 25-30 deg in the most massive haloes (13 ≤ log10(M200/[ h-1 M⊙]) ≤ 15). Half of the disc galaxies in the EAGLE simulations have a misalignment angle with respect to their host haloes larger than 40 deg. We present fitting functions and tabulated values for the probability distribution of galaxy-halo misalignment to enable a straightforward inclusion of our results into models of galaxy formations based on purely collisionless N-body simulations.

  2. Gas phase condensation of superparamagnetic iron oxide-silica nanoparticles - control of the intraparticle phase distribution

    NASA Astrophysics Data System (ADS)

    Stötzel, C.; Kurland, H.-D.; Grabow, J.; Müller, F. A.

    2015-04-01

    consisting of a γ-Fe2O3 and a SiO2 hemisphere to γ-Fe2O3 NPs each carrying one small SiO2 lens on its surface, (ii) the multiple γ-Fe2O3 inclusions accumulate at the NPs' inner surfaces, and (iii) all composite NPs are covered by a thin layer of amorphous SiO2. These morphological characteristics are attributed to (i) the phase segregation of iron oxide and silica within the condensed Fe2O3-SiO2 droplets, (ii) the temperature gradient within these droplets which arises during rapid cooling in the CoLAVA process, and (iii) the significantly lower surface energy of silica when compared to iron oxide. The proposed growth mechanism of these Fe2O3-SiO2 composite NPs during gas phase condensation can be transferred to other systems comprising a glass-network former and another component that is insoluble in the regarding glass. Thus, our model will facilitate the development of novel functional composite NPs for applications in biomedicine, optics, electronics, or catalysis. Electronic supplementary information (ESI) available: Infrared absorption of the raw powders hematite and quartz (section S1), TEM investigation of the spatial distribution of the γ-Fe2O3 inclusions (section S2), particle size distributions of the Fe2O3@SiO2 nanopowder samples (section S3), ζ-potentials of aqueous dispersions of all γ-Fe2O3@SiO2 nanopowder samples (section S4), silanization of Fe2O3@SiO2 composite nanopowders with [3-(2,3-epoxypropoxy)-propyl]trimethoxysilane (section S5), and animation composed of TEM micrographs of Fe2O3@SiO2 NPs recorded at incrementally altered tilt angles (``Rotating Fe2O3@SiO2 NP.avi''). See DOI: 10.1039/c5nr00845j

  3. TOWARD A DETERMINISTIC MODEL OF PLANETARY FORMATION. VII. ECCENTRICITY DISTRIBUTION OF GAS GIANTS

    SciTech Connect

    Ida, S.; Lin, D. N. C.

    2013-09-20

    The ubiquity of planets and diversity of planetary systems reveal that planet formation encompasses many complex and competing processes. In this series of papers, we develop and upgrade a population synthesis model as a tool to identify the dominant physical effects and to calibrate the range of physical conditions. Recent planet searches have led to the discovery of many multiple-planet systems. Any theoretical models of their origins must take into account dynamical interactions between emerging protoplanets. Here, we introduce a prescription to approximate the close encounters between multiple planets. We apply this method to simulate the growth, migration, and dynamical interaction of planetary systems. Our models show that in relatively massive disks, several gas giants and rocky/icy planets emerge, migrate, and undergo dynamical instability. Secular perturbation between planets leads to orbital crossings, eccentricity excitation, and planetary ejection. In disks with modest masses, two or less gas giants form with multiple super-Earths. Orbital stability in these systems is generally maintained and they retain the kinematic structure after gas in their natal disks is depleted. These results reproduce the observed planetary mass-eccentricity and semimajor axis-eccentricity correlations. They also suggest that emerging gas giants can scatter residual cores to the outer disk regions. Subsequent in situ gas accretion onto these cores can lead to the formation of distant (∼> 30 AU) gas giants with nearly circular orbits.

  4. A measurement plan of gas concentration and temperature distribution reconstruction based on the tunable diode laser absorption tomography

    NASA Astrophysics Data System (ADS)

    Liu, Zhao-ran; Jin, Xing; Wang, Guang-yu; Song, Jun-ling

    2014-11-01

    Based on the tunable diode laser absorption tomography, gas concentration and temperature two-dimensional distribution reconstruction is realized using algebraic iterative reconstruction technique (ART). A measurement plan is proposed based on the beam splitting lens, and the corresponding beam arrangement is put forward. The beam splitting lenses are used in the plan to making one laser beam cross the measurement area repeatedly. Thus can raise the utilization ratio of laser beam and simplify the structure of measurement platform. A model for H2O vapor concentration and temperature distribution is assumed, and numerical simulation is utilized using two absorption transitions. The feasibility of the measurement plan is proved by the simulation experiment. The influences of initial beam angle, the number of beams and grids on the reconstructed results are analyzed numerically. A concept of phantom description method using in simulation experiments is proposed in order to getting closer to the real experiments. The phantom description method is used in the numerical simulation to evaluating concentration and temperature field reconstruction. Through this method, expected data is sampled from initial data, and reconstructed result is obtained by interpolation. The influence of random errors in projections on distribution reconstruction is also analyzed. The measurement plan can reconstruct the gas concentration and temperature distribution with a simplified measurement platform using beam splitting lenses. The feasibility of the phantom description method is also proved by the simulation experiment.

  5. Size distribution and concentration of soot generated in oil and gas-fired residential boilers under different combustion conditions

    NASA Astrophysics Data System (ADS)

    Jiménez, Santiago; Barroso, Jorge; Pina, Antonio; Ballester, Javier

    2016-05-01

    In spite of the relevance of residential heating burners in the global emission of soot particles to the atmosphere, relatively little information on their properties (concentration, size distribution) is available in the literature, and even less regarding the dependence of those properties on the operating conditions. Instead, the usual procedure to characterize those emissions is to measure the smoke opacity by several methods, among which the blackening of a paper after filtering a fixed amount of gas (Bacharach test) is predominant. In this work, the size distributions of the particles generated in the combustion of a variety of gaseous and liquid fuels in a laboratory facility equipped with commercial burners have been measured with a size classifier coupled to a particle counter in a broad range of operating conditions (air excesses), with simultaneous determination of the Bacharach index. The shape and evolution of the distribution with progressively smaller oxygen concentrations depends essentially on the state of the fuel: whereas the combustion of the gases results in monomodal distributions that 'shift' towards larger diameters, in the case of the gas-oils an ultrafine mode is always observed, and a secondary mode of coarse particle grows in relevance. In both cases, there is a strong, exponential correlation between the total mass concentration and the Bacharach opacity index, quite similar for both groups of fuels. The empirical expressions proposed may allow other researchers to at least estimate the emissions of numerous combustion facilities routinely characterized by their smoke opacities.

  6. Distribution and geological control of mud volcanoes and other fluid/free gas seepage features in the Mediterranean Sea and nearby Gulf of Cadiz

    NASA Astrophysics Data System (ADS)

    Mascle, Jean; Mary, Flore; Praeg, Daniel; Brosolo, Laetitia; Camera, Laurent; Ceramicola, Silvia; Dupré, Stéphanie

    2014-06-01

    Existing knowledge on the distribution of mud volcanoes (MVs) and other significant fluid/free gas-venting features (mud cones, mud pies, mud-brine pools, mud carbonate cones, gas chimneys and, in some cases, pockmark fields) discovered on the seafloor of the Mediterranean Sea and in the nearby Gulf of Cadiz has been compiled using regional geophysical information (including multibeam coverage of most deepwater areas). The resulting dataset comprises both features proven from geological sampling, or in situ observations, and many previously unrecognized MVs inferred from geophysical evidence. The synthesis reveals that MVs clearly have non-random distributions that correspond to two main geodynamic settings: (1) the vast majority occur along the various tectono-sedimentary accretionary wedges of the Africa-Eurasia subduction zone, particularly in the central and eastern Mediterranean basins (external Calabrian Arc, Mediterranean Ridge, Florence Rise) but also along its westernmost boundary in the Gulf of Cadiz; (2) other MVs characterize thick depocentres along parts of the Mesozoic passive continental margins that border Africa from eastern Tunisia to the Levantine coasts, particularly off Egypt and, locally, within some areas of the western Mediterranean back-arc basins. Meaningfully accounting for MV distribution necessitates evidence of overpressured fluids and mud-rich layers. In addition, cross-correlations between MVs and other GIS-based data, such as maps of the Messinian evaporite basins and/or active (or recently active) tectonic trends, stress the importance of assessing geological control in terms of the presence, or not, of thick seals and potential conduits. It is contended that new MV discoveries may be expected in the study region, particularly along the southern Ionian Sea continental margins.

  7. Local ISM 3D distribution and soft X-ray background. Inferences on nearby hot gas and the North Polar Spur

    NASA Astrophysics Data System (ADS)

    Puspitarini, L.; Lallement, R.; Vergely, J.-L.; Snowden, S. L.

    2014-06-01

    Three-dimensional (3D) interstellar medium (ISM) maps can be used to locate not only interstellar (IS) clouds, but also IS bubbles between the clouds that are blown by stellar winds and supernovae, and that are filled by hot gas. To demonstrate this and to derive a clearer picture of the local ISM, we compare our recent 3D maps of the IS dust distribution to the ROSAT diffuse X-ray background maps after removing heliospheric emission. In the Galactic plane, there is a good correspondence between the locations and extents of the mapped nearby cavities and the soft (0.25 keV) background emission distribution, showing that most of these nearby cavities contribute to this soft X-ray emission. Assuming a constant dust-to-gas ratio and homogeneous 106 K hot gas filling the cavities, we modeled the 0.25 keV surface brightness in a simple way along the Galactic plane as seen from the Sun, taking the absorption by the mapped clouds into account. The data-model comparison favors the existence of hot gas in the solar neighborhood, the so-called Local Bubble (LB). The inferred average mean pressure in the local cavities is found to be on the order of 10 000 cm-3 K, in agreement with previous studies, providing a validation test for the method. On the other hand, the model overestimates the emission from the huge cavities located in the third quadrant. Using CaII absorption data, we show that the dust-to-CaII ratio is very low in this region, implying there is a large quantity of lower temperature (non-X-ray emitting) ionized gas and, as a consequence, a reduction in the volume filled by hot gas, explaining at least part of the discrepancy. In the meridian plane, the main two brightness enhancements coincide well with the LB's most elongated parts and chimneys connecting the LB to the halo, but no particular nearby cavity is found towards the enhancement in the direction of the bright North Polar Spur (NPS) at high latitude. We searched in the 3D maps for the source regions of

  8. Three-dimensional distribution of the ISM in the Milky Way galaxy. III. The total neutral gas disk

    NASA Astrophysics Data System (ADS)

    Nakanishi, Hiroyuki; Sofue, Yoshiaki

    2016-02-01

    We present newly obtained three-dimensional gaseous maps of the Milky Way Galaxy: H I, H2, and total-gas (H I plus H2) maps, which were derived from the H I and 12CO(J = 1-0) survey data and rotation curves based on the kinematic distance. The H I and H2 face-on maps show that the H I disk is extended to a radius of 15-20 kpc and its outskirts are asymmetric to the Galactic center, while most of the H2 gas is distributed inside the solar circle. The total gas mass within a radius of 30 kpc amounts to 8.0 × 109 M⊙, 89% and 11% of which are H I and H2, respectively. The vertical slices show that the outer H I disk is strongly warped and the inner H I and H2 disks are corrugated. The total gas map is advantageous for tracing spiral structures from the inner to outer disk. Spiral structures such as the Norma-Cygnus, the Perseus, the Sagittarius-Carina, the Scutum-Crux, and the Orion arms are more clearly traced in the total gas map than ever. All the spiral arms are well explained by logarithmic spiral arms with pitch angles of 11°-15°. The molecular fraction of the total gas is high near the Galactic center and decreases with Galactocentric distance. The molecular fraction is also locally enhanced at the spiral arms compared with the inter-arm regions.

  9. Fast spatially resolved exhaust gas recirculation (EGR) distribution measurements in an internal combustion engine using absorption spectroscopy.

    PubMed

    Yoo, Jihyung; Prikhodko, Vitaly; Parks, James E; Perfetto, Anthony; Geckler, Sam; Partridge, William P

    2015-09-01

    Exhaust gas recirculation (EGR) in internal combustion engines is an effective method of reducing NOx emissions while improving efficiency. However, insufficient mixing between fresh air and exhaust gas can lead to cycle-to-cycle and cylinder-to-cylinder non-uniform charge gas mixtures of a multi-cylinder engine, which can in turn reduce engine performance and efficiency. A sensor packaged into a compact probe was designed, built and applied to measure spatiotemporal EGR distributions in the intake manifold of an operating engine. The probe promotes the development of more efficient and higher-performance engines by resolving high-speed in situ CO2 concentration at various locations in the intake manifold. The study employed mid-infrared light sources tuned to an absorption band of CO2 near 4.3 μm, an industry standard species for determining EGR fraction. The calibrated probe was used to map spatial EGR distributions in an intake manifold with high accuracy and monitor cycle-resolved cylinder-specific EGR fluctuations at a rate of up to 1 kHz. PMID:26253286

  10. Dependence of Ozone Generation on Gas Temperature Distribution in AC Atmospheric Pressure Dielectric Barrier Discharge in Oxygen

    NASA Astrophysics Data System (ADS)

    Takahashi, Go; Akashi, Haruaki

    AC atmospheric pressure multi-filament dielectric barrier discharge in oxygen has been simulated using two dimensional fluid model. In the discharge, three kinds of streamers have been obtained. They are primary streamers, small scale streamers and secondary streamers. The primary streamers are main streamers in the discharge and the small scale streamers are formed after the ceasing of the primary streamers. And the secondary streamers are formed on the trace of the primary streamers. In these streamers, the primary and the small scale streamers are very effective to generate O(3P) oxygen atoms which are precursor of ozone. And the ozone is generated mainly in the vicinity of the dielectrics. In high gas temperature region, ozone generation decreases in general. However, increase of the O(3P) oxygen atom density in high gas temperature region compensates decrease of ozone generation rate coefficient. As a result, amount of ozone generation has not changed. But if the effect of gas temperature was neglected, amount of ozone generation increases 10%.

  11. Atlas of Northern Gulf of Mexico Gas and Oil Reservoirs: Procedures and examples of resource distribution

    SciTech Connect

    Seni, S.J.; Finley, R.J.

    1995-06-01

    The objective of the program is to produce a reservoir atlas series of the Gulf of Mexico that (1) classifies and groups offshore oil and gas reservoirs into a series of geologically defined reservoir plays, (2) compiles comprehensive reservoir play information that includes descriptive and quantitative summaries of play characteristics, cumulative production, reserves, original oil and gas in place, and various other engineering and geologic data, (3) provides detailed summaries of representative type reservoirs for each play, and (4) organizes computerized tables of reservoir engineering data into a geographic information system (GIS). The primary product of the program will be an oil and gas atlas series of the offshore Northern Gulf of Mexico and a computerized geographical information system of geologic and engineering data linked to reservoir location.

  12. Deev Jahi Model of the Permian Triassic boundary mass extinction: a case for gas hydrates as the main cause of biological crisis on Earth

    NASA Astrophysics Data System (ADS)

    Heydari, E.; Hassanzadeh, J.

    2003-12-01

    The smoking gun revealing the secrets of the end-Permian mass mortality is a unique 1-2-m-thick layer consisting of 5-20-cm-long crystals of calcite that occurs precisely at the Permian-Triassic boundary (PTB) in Iran, Armenia, Turkey, and China. This layer is interpreted as synsedimentary, abiotic, seafloor cement indicative of precipitation from a highly carbonate supersaturated seawater. Its δ13C composition ( δ13C=0‰ PDB) is 4‰ to 5‰ PDB lower than the typical Upper Permian values (4‰ to 5‰ PDB), suggesting the involvement of massive amounts of gas hydrate CH 4 ( δ13C=-60‰ PDB). The temporal coincidence of the cement layer with the PTB suggests that the process that promoted seafloor cementation was also responsible for the biological crisis. A cementation model is developed based on accumulation-dissociation cycle of gas hydrates which also explains the mass extinction at the PTB. The Upper Permian accumulation period of gas hydrates ended abruptly adjacent to the PTB and the dissociation event began releasing 3.2 to 4.7×10 18 g CH 4 into the ocean. Oxidation of CH 4 in the water column created a seawater that was charged with CO 2 (an oceanic acid bath) and had lower than normal O 2 content (but not anoxic). This oceanic acid bath first dissolved suspended fine-grained carbonate particles and small calcareous organisms, followed by extensive dissolution of platform carbonates raising Ca 2+ and HCO 3- concentrations of seawater. When the release of CH 4 declined, the acid-bath ocean became a soda ocean precipitating massive amount of seafloor cements observed globally at the PTB. The study suggests that prior to cement precipitation, the PTB ocean was charged with CO 2, warm, had low oxygen, high Ca 2+, and high HCO 3- concentrations. These conditions collectively created stressful conditions causing the marine mass mortality. The leakage of CH 4 to the atmosphere produced a super-hot climate resulting in the biological devastation on land. The

  13. Spatial distribution of the optogalvanic signal in a microplasma detector for lab-on-a-chip gas analysis

    NASA Astrophysics Data System (ADS)

    Persson, A.; Berglund, M.

    2016-07-01

    Gas sensors are characterized by their sensitivity and selectivity. This is preferably combined with versatility, where the selectivity can be altered, without complex modifications and whiteout losing sensitivity. If aimed at lab-on-a-chip applications, the sensor also must be able to analyze small samples. Today, sensors combining selectivity and versatility for chip-level gas analysis are scarce; however, this paper investigates how miniaturized optogalvanic spectroscopy can fill this gap. By studying the spatial distribution of the optogalvanic signal inside a microplasma, it is shown that the signal is generated in the minuscule gas volume of the sheath surrounding the plasma probe that collects it. Nevertheless, a strong and stable spectroscopic signal can be extracted from the sheath, and the sample concentrations can be calculated using straightforward plasma theory. The minimum detectable absorption and the noise equivalent absorption sensitivity of the system are estimated to be less than 1.4  ×  10‑9 Hz‑0.5 and 2.8  ×  10‑9 cm‑1 Hz‑0.5, respectively, without cavity enhancement. Combined with inherited versatility from absorption spectroscopy and the capability of handling sub-nanogram samples, this makes optogalvanic spectrometry an excellent candidate for future lab-on-a-chip gas analyzers.

  14. CFD assisted simulation of temperature distribution and laser power in pulsed and CW pumped static gas DPALs

    NASA Astrophysics Data System (ADS)

    Waichman, Karol; Barmashenko, Boris D.; Rosenwaks, Salman

    2015-10-01

    An analysis of radiation, kinetic and fluid dynamic processes in diode pumped alkali lasers (DPALs) is reported. The analysis is based on a three-dimensional, time-dependent computational fluid dynamics (3D CFD) model. The CFD code which solves the gas conservation equations includes effects of natural convection and temperature diffusion of the species in the DPAL mixture. The gas flow conservation equations are coupled to the equations for DPAL kinetics and to the Beer-Lambert equations for pump and laser beams propagation. The DPAL kinetic processes in the Cs/CH4 (K/He) gas mixtures considered involve the three low energy levels, (1) n2S1/2, (2) n2P3/2 and (3) n2P1/2 (where n=4,6 for K and Cs, respectively), three excited alkali states and two alkali ionic states. Using the CFD model, the gas flow pattern and spatial distributions of the pump and laser intensities in the resonator were calculated for end-pumped CW and pulsed Cs and K DPALs. The DPAL power and medium temperature were calculated as a function of pump power and pump pulse duration. The CFD model results were compared to experimental results of Cs and K DPALs.

  15. Gas chromatographic simulated distillation-mass spectrometry for the determination of the boiling point distributions of crude oils

    PubMed

    Roussis; Fitzgerald

    2000-04-01

    The coupling of gas chromatographic simulated distillation with mass spectrometry for the determination of the distillation profiles of crude oils is reported. The method provides the boiling point distributions of both weight and volume percent amounts. The weight percent distribution is obtained from the measured total ion current signal. The total ion current signal is converted to weight percent amount by calibration with a reference crude oil of a known distillation profile. Knowledge of the chemical composition of the crude oil across the boiling range permits the determination of the volume percent distribution. The long-term repeatability is equivalent to or better than the short-term repeatability of the currently available American Society for Testing and Materials (ASTM) gas chromatographic method for simulated distillation. Results obtained by the mass spectrometric method are in very good agreement with results obtained by conventional methods of physical distillation. The compositional information supplied by the method can be used to extensively characterize crude oils. PMID:10763233

  16. Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: constraints from ODP Leg 204

    SciTech Connect

    Trehu, Ann M.; Long, Philip E.; Torres, M E.; Bohrmann, G; Rack, F R.; Collett, T S.; Goldberg, D S.; Milkov, A V.; Riedel, M; Schultheiss, P; Bangs, N L.; Barr, S R.; Borowski, W S.; Claypool, G E.; Delwiche, Mark E.; Dickens, G R.; Gracia, E; Guerin, G; Holland, M; Johnson, Jerry E.; Lee, Y J.; Liu, C S.; Su, X; Teichert, B; Tomaru, H; Vanneste, M; Watanabe, M; Weinberger, Jill L.

    2004-03-01

    Large uncertainties about the energy resource potential and role in global climate change of gas hydrates result from uncertainty about how much hydrate is contained in marine sediments. During Leg 204 of the Ocean Drilling Program (ODP) to the accretionary complex of the Cascadia subduction zone, the entire gas hydrate stability zone was sampled in contrasting geological settings defined by a 3D seismic survey. By integrating results from different methods, including several new techniques developed for Leg 204, we overcome the problem of spatial under-sampling inherent in robust methods traditionally used for estimating the hydrate content of cores and obtain a high-resolution, quantitative estimate of the total amount and spatial variability of gas hydrate in this structural system. We conclude that high gas hydrate content (30-40% of pore space of 20-26% of total volume) is restricted to the upper tens of meters below the seafloor near the summit of the structure, where vigorous fluid venting occurs.

  17. Improvement of oxygen diffusion characteristic in gas diffusion layer with planar-distributed wettability for polymer electrolyte fuel cell

    NASA Astrophysics Data System (ADS)

    Koresawa, Ryo; Utaka, Yoshio

    2014-12-01

    Mass transfer characteristics of gas diffusion layer (GDL) are closely related to performance of polymer electrolyte fuel cells. Therefore, it is necessary to clarify the characteristics of water distribution relating to the microscopic conformation and oxygen diffusivity of GDL. A hybrid type carbon paper GDL with planar-distributed wettability is investigated for control of liquid water movement and distribution due to hydrophobic to hydrophilic areas that provide wettability differences in GDL and to achieve enhancement of both oxygen diffusion and moisture retention. Hybrid GDLs with different PTFE content were fabricated in an attempt to improve the oxygen diffusion characteristics. The effects of different PTFE contents on the oxygen diffusivity and water distribution were simultaneously measured and observed using galvanic cell oxygen absorber and X-ray radiography. The PTFE distribution was observed using scanning electron microscopy. The formation of oxygen diffusion paths was confirmed by X-ray radiography, where voids in the hybrid GDL were first formed in the hydrophobic regions and then spread to the untreated wetting region. Thus, the formation of oxygen diffusion paths enhanced the oxygen diffusion. In addition, the effects of local PTFE content in the hydrophobic region and the optimal amount of PTFE for hybrid GDL were elucidated.

  18. Distribution of Hg, As and Se in material and flue gas streams from preheater-precalciner cement kilns and vertical shaft cement kilns in China.

    PubMed

    Yan, Dahai; Peng, Zheng; Ding, Qiong; Karstensen, Kåre Helge; Engelsen, Christian J; Li, Li; Ren, Yong; Jiang, Chen

    2015-08-01

    The aim of this study was to evaluate the behavior of Hg, As, and Se in cement production. Two types of cement plants were studied, including the vertical shaft kiln (VSK) and preheater-precalciner kiln (PPK) processes. Determination of Hg, As, and Se in the main material and gas streams were performed. It was found that recycling of particulate matter captured by an air pollution control device caused a significant enrichment of Hg and As inside both processes. The total quantity of Hg entering the process and the quantity emitted to the atmosphere were found to be 10-109 and 6.3-38 mg, respectively, per ton of clinker produced. The average Hg emission was calculated to be around 41% of the total mercury input. The emissions found complied with the European Union (EU) limit and exceeded partly the U.S. limit. Furthermore, it was found that oxidized mercury was the dominant species in the PPK process, whereas the reduced form was dominant in the VSK process, due to the oxidizing and reducing gas conditions, respectively. Regarding the distribution of As and Se, the major amounts were bound to the solid materials, that is, cement clinker and particulate matter. Based on cement production data in China in 2013, the annual emissions of Hg and As were estimated to be in the range of 8.6-52 and 4.1-9.5 tons, respectively. PMID:26037967

  19. Simultaneous removal of SO2 and trace As2O3 from flue gas: mechanism, kinetics study, and effect of main gases on arsenic capture.

    PubMed

    Li, Yuzhong; Tong, Huiling; Zhuo, Yuqun; Li, Yan; Xu, Xuchang

    2007-04-15

    Sulfur dioxide (SO2) and trace elements are pollutants derived from coal combustion. This study focuses on the simultaneous removal of S02 and trace arsenic oxide (As2O3) from flue gas by calcium oxide (CaO) adsorption in the moderate temperature range. Experiments have been performed on a thermogravimetric analyzer (TGA). The interaction mechanism between As2O3 and CaO is studied via XRD detection. Calcium arsenate [Ca3(AsO4)2] is found to be the reaction product in the range of 600-1000 degrees C. The ability of CaO to absorb As2O3 increases with the increasing temperature over the range of 400-1000 degrees C. Through kinetics analysis, it has been found that the rate constant of arsenate reaction is much higher than that of sulfate reaction. SO2 presence does not affect the trace arsenic capture either in the initial reaction stage when CaO conversion is relatively low or in the later stage when CaO conversion is very high. The product of sulfate reaction, CaS04, is proven to be able to absorb As2O3. The coexisting CO2 does not weaken the trace arsenic capture either. PMID:17533855

  20. Witnessing Gas Mixing in the Metal Distribution during a Galaxy Merger.

    NASA Astrophysics Data System (ADS)

    Amram, Philippe

    2015-08-01

    I will present direct evidence that in a merger of disk galaxies, the pre-existing central metallicities will mix as a result of gas being transported in the merger interface region along the line that joins the two coalescing nuclei. In focusing on the emission line gas, this is shown using detailed two-dimensional kinematics as well as metallicity measurements for the nearby ongoing merger in the center of the compact group HCG 31. The two coalescing cores display similar oxygen abundances, while in between the two nuclei, the metallicity changes smoothly from one nucleus to the other indicating a mix of metals in this region. This nearby system involves the merging of two fairly low-mass and clumpy galaxies (LMC-like galaxies), making it an important system for comparison with high-redshift galaxies.

  1. Simultaneous determination of traces of pyrethroids, organochlorines and other main plant protection agents in agricultural soils by headspace solid-phase microextraction-gas chromatography.

    PubMed

    Fernandez-Alvarez, Maria; Llompart, Maria; Lamas, J Pablo; Lores, Marta; Garcia-Jares, Carmen; Cela, Rafael; Dagnac, Thierry

    2008-04-25

    A solvent-free and simple method based on headspace solid-phase microextraction (HS-SPME) was developed in order to determine simultaneously 36 common pesticides and breakdown products (mostly pyrethroids and organochlorine compounds) in soil. The analysis was carried out by gas chromatography with micro-electron-capture detection (GC-microECD). As far as we know, this is the first study about the SPME of pyrethroid insecticides from soil. Factors such as extraction temperature, matrix modification by addition of water, salt addition (% NaCl) and fiber coating were considered in the optimization of the HS-SPME. To this end, a 3 x 2(3-1) fractional factorial design was performed. The results showed that temperature and fiber coating were the most significant variables affecting extraction efficiency. A suitable sensitivity for all investigated compounds was achieved at 100 degrees C by extracting soil samples wetted with 0.5 mL of ultrapure water (0% NaCl) employing a polyacrylate (PA) coating fiber. Using the recommended extraction conditions with GC-microECD, a linear calibration could be achieved over a range of two orders of magnitude for both groups of analytes. Limits of detection (LODS) at the sub-ng g(-1) level were attained and relative standard deviations (RSDs) were found to be lower than 14% for both groups of pesticides. Matrix effects were investigated by the analysis of different soil samples fortified with the target compounds. The method accuracy was assessed and good recovery values (>70%, in most cases) were obtained. The method was also validated with a certified reference material (RTC-CRM818-050), which was quantified using a standard addition protocol. Finally, the proposed HS-SPME-GC-microECD methodology was further applied to the screening of environmental soil samples for the presence of the target pesticides. PMID:18346746

  2. Gas-Phase Neutral Binary Oxide Clusters: Distribution, Structure, and Reactivity toward CO.

    PubMed

    Wang, Zhe-Chen; Yin, Shi; Bernstein, Elliot R

    2012-09-01

    Neutral binary (vanadium-cobalt) oxide clusters are generated and detected in the gas phase for the first time. Their reactivities toward carbon monoxide (CO) are studied both experimentally and theoretically. Experimental results suggest that neutral VCoO4 can react with CO to generate VCoO3 and CO2. Density functional theory studies show parallel results as well as provide detailed reaction mechanisms. PMID:26292125

  3. Radiation intensity distribution in a nuclear-pumped gas-flow laser

    SciTech Connect

    Korzenev, A N; Limar', Yu M; Sizov, A N; Sinyanskii, A A

    2005-09-30

    It is shown experimentally that two lasing zones, displaced directly towards the entrance of the laser channel, are formed in gas-flow lasers pumped by the fission fragments of uranium nuclei. As the pump power is increased, these zones merge into a single zone that expands towards the exit section of the channel. The time dependence of the lasing power qualitatively repeats the shape of the exciting neutron pulse. (lasers)

  4. Analysis of the gas-dynamic performance of a vaned diffuser with given velocity distribution along the vane's surfaces

    NASA Astrophysics Data System (ADS)

    Kalinkevych, M.; Obukhov, O.; Obukhova, O.; Miroshnychenko, A.

    2015-08-01

    Extension of the effective range of vaned diffusers is one of the promising ways to improve the centrifugal compressor's stages which are used in numerous fields of industry. The new method of profiling of the diffuser vanes has been developed using Stratford's results and boundary layer theory by Loytsanskiy. The developed method is based on the solution of the inverse task of gas-dynamic using given velocity distribution along the vane's surface. Comparison of the results of numerical simulations for different diffusers has shown that the performance of the diffuser designed with the resulting velocity distribution are better. Influence of the vane profile, number of the vanes, diffuser outlet diameter and the diffuser width on diffuser characteristics has been investigated. The results of the simulations have been used to formulate recommendations on the design of high-effectiveness vaned diffusers for centrifugal stages of different types.

  5. Estimation of placental and lactational transfer and tissue distribution of atrazine and its main metabolites in rodent dams, fetuses, and neonates with physiologically based pharmacokinetic modeling

    SciTech Connect

    Lin, Zhoumeng; Fisher, Jeffrey W.; Wang, Ran; Ross, Matthew K.; Filipov, Nikolay M.

    2013-11-15

    The fetus is exposed to atrazine/its main metabolite at levels similar to the dam. • The nursing neonate is exposed primarily to atrazine's main metabolite DACT.

  6. Gas-phase particle size distributions and lead loss during spray pyrolysis of (Bi,Pb)--Sr--Ca--Cu--O

    SciTech Connect

    Gurav, A.S.; Kodas, T.T.; Joutsensaari, J.; Kauppinen, E.I.; Zilliacus, R.

    1995-07-01

    Gas-phase particle size distributions and lead loss were measured during formation of (Bi,Pb)--Sr--Ca--Cu--O and pure PbO particles by spray pyrolysis at different temperatures. A differential mobility analyzer (DMA) in conjunction with a condensation particle counter (CPC) was used to monitor the gas-phase particle size distributions, and a Berner-type low-pressure impactor was used to obtain mass size distributions and a Berner-type low-pressure impactor was used to obtain mass size distributions and size-classified samples for chemical analysis. For (Bi,Pb)--Sr--Ca--Cu--O, as the processing temperature was raised from 200 to 700 {degree}C, the number average particle size decreased due to metal nitrate decomposition, intraparticle reactions forming mixed-metal oxides and particle densification. The geometric number mean particle diameter was 0.12 {mu}m at 200 {degree}C and reduced to 0.08 and 0.07 {mu}m, respectively, at 700 and 900 {degree}C. When the reactor temperature was raised from 700 and 800 {degree}C to 900 {degree}C, a large number ({similar_to}10{sup 7} no./cm{sup 3}) of new ultrafine particles were formed from PbO vapor released from the particles and the reactor walls. Particles made at temperatures up to 700 {degree}C maintained their initial stoichiometry over the whole range of particle size monitored, however; those made at 800 {degree}C and above were heavily depleted in lead in the size range 0.5--5.0 {mu}m. The evaporative losses of lead oxide from (Bi,Pb)--Sr--Ca--Cu--O particles were compared with the losses from PbO particles to gain insight into the pathways involved in lead loss and the role of intraparticle processes in controlling it.

  7. Spatial distribution of cell–cell and cell–ECM adhesions regulates force balance while main­taining E-cadherin molecular tension in cell pairs

    PubMed Central

    Sim, Joo Yong; Moeller, Jens; Hart, Kevin C.; Ramallo, Diego; Vogel, Viola; Dunn, Alex R.; Nelson, W. James; Pruitt, Beth L.

    2015-01-01

    Mechanical linkage between cell–cell and cell–extracellular matrix (ECM) adhesions regulates cell shape changes during embryonic development and tissue homoeostasis. We examined how the force balance between cell–cell and cell–ECM adhesions changes with cell spread area and aspect ratio in pairs of MDCK cells. We used ECM micropatterning to drive different cytoskeleton strain energy states and cell-generated traction forces and used a Förster resonance energy transfer tension biosensor to ask whether changes in forces across cell–cell junctions correlated with E-cadherin molecular tension. We found that continuous peripheral ECM adhesions resulted in increased cell–cell and cell–ECM forces with increasing spread area. In contrast, confining ECM adhesions to the distal ends of cell–cell pairs resulted in shorter junction lengths and constant cell–cell forces. Of interest, each cell within a cell pair generated higher strain energies than isolated single cells of the same spread area. Surprisingly, E-cadherin molecular tension remained constant regardless of changes in cell–cell forces and was evenly distributed along cell–cell junctions independent of cell spread area and total traction forces. Taken together, our results showed that cell pairs maintained constant E-cadherin molecular tension and regulated total forces relative to cell spread area and shape but independently of total focal adhesion area. PMID:25971797

  8. Evaluation of P{sub 2}O{sub 5} distribution inside the main clinker minerals by the application of EPMA method

    SciTech Connect

    Ifka, Tomáš; Palou, Martin; Baraček, Jan; Šoukal, František; Boháč, Martin

    2014-05-01

    The formation of Portland clinker phases has taken place in thermodynamically non-equilibrium state between macro-oxides CaO, SiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3} and MgO from raw meal and P{sub 2}O{sub 5} from bone meal. The paper deals with the study of clinker minerals as solid solutions with P{sub 2}O{sub 5} during the clinkerization of raw mixture containing bone meal (BM). The ash of BM has contributed as a raw material to the formation of different clinker phases. Electron probe microanalysis (EPMA) method was used to determine the preferential distribution of P{sub 2}O{sub 5} inside calcium silicate phases and its influence upon C{sub 2}S/C{sub 3}S ratio. Basing on these results, composition of solid solution of C{sub 2}S and C{sub 3}S was established.

  9. Noninvasive identification of left main and triple vessel coronary artery disease: improved accuracy using quantitative analysis of regional myocardial stress distribution and washout of thallium-201

    SciTech Connect

    Maddahi, J.; Abdulla, A.; Garcia, E.V.; Swan, H.J.; Berman, D.S.

    1986-01-01

    The capabilities of visual and quantitative analysis of stress redistribution thallium-201 scintigrams, exercise electrocardiography and exercise blood pressure response were compared for correct identification of extensive coronary disease, defined as left main or triple vessel coronary artery disease, or both (50% or more luminal diameter coronary narrowing), in 105 consecutive patients with suspected coronary artery disease. Extensive disease was present in 56 patients and the remaining 49 had either less extensive coronary artery disease (n = 34) or normal coronary arteriograms (n = 15). Although exercise blood pressure response, exercise electrocardiography and visual thallium-201 analysis were highly specific (98, 88 and 96%, respectively), they were insensitive for identification of patients with extensive disease (14, 45 and 16%, respectively). Quantitative thallium-201 analysis significantly improved the sensitivity of visual thallium-201 analysis for identification of patients with extensive disease (from 16 to 63%, p less than 0.001) without a significant loss of specificity (96 versus 86%, p = NS). Eighteen (64%) of the 28 patients who were misclassified by visual analysis as having less extensive disease were correctly classified as having extensive disease by virtue of quantitative analysis of regional myocardial thallium-201 washout. When the results of quantitative thallium-201 analysis were combined with those of blood pressure and electrocardiographic response to exercise, the sensitivity and specificity for identification of patients with extensive disease was 86 and 76%, respectively, and the highest overall accuracy (0.82) was obtained.

  10. Spatial and diurnal distribution of invertebrate and fish fauna of a Zostera marina bed and nearby unvegetated sediments in Damariscotta River, Maine (USA)

    NASA Astrophysics Data System (ADS)

    Mattila, Johanna; Chaplin, Glen; Eilers, Michele R.; Heck, Kenneth L.; O'Neal, Jonathan P.; Valentine, John F.

    1999-06-01

    Fish, epibenthos and macroinfauna were collected in a Zostera marina bed and nearby unvegetated sediments in the estuary of the Damariscotta River, on the mid-coast of Maine. Samples of epibenthic fauna and fish were collected at low tides both during day and night, and samples of infauna at low tides during the day. The mean density of Zostera shoots in the study area was 335 m -2. Abundance and species number of fish were greater at night than during the day and greater in eelgrass beds ( Z. marina) than in unvegetated habitats. Daytime fish collections were dominated by Atlantic silversides ( Medinia medinia), while juvenile winter flounder ( Pseudopleuronectes americanus) dominated night collections. Also Zostera-associated epifaunal abundances and number of species were significantly higher at night than during the day. Mysis stenolepis, Idotea balthica and Littorina obtusata were dominant species in the epifauna samples. Of the total of 37 invertebrate species encountered, only five occurred both in the infaunal and epifaunal samples. Nineteen different taxa were collected from the benthic core samples. The most abundant invertebrate infaunal taxa were sipunculids, the polychaete Nereis virens, and oligochaetes. Infaunal invertebrate abundances and species diversity were significantly higher in eelgrass beds than in unvegetated sediments. The abundance and number of species of benthic invertebrates were also positively correlated to seagrass biomass. Community diversity values ( H') were relatively low but fit well in the general pattern of decreasing diversity towards northern latitudes.

  11. H2 and CO Emission from Disks around T Tauri and Herbig Ae Pre-Main-Sequence Stars and from Debris Disks around Young Stars: Warm and Cold Circumstellar Gas

    NASA Astrophysics Data System (ADS)

    Thi, W. F.; van Dishoeck, E. F.; Blake, G. A.; van Zadelhoff, G. J.; Horn, J.; Becklin, E. E.; Mannings, V.; Sargent, A. I.; van den Ancker, M. E.; Natta, A.; Kessler, J.

    2001-11-01

    We present ISO Short-Wavelength Spectrometer observations of H2 pure-rotational line emission from the disks around low- and intermediate-mass pre-main-sequence stars as well as from young stars thought to be surrounded by debris disks. The pre-main-sequence sources have been selected to be isolated from molecular clouds and to have circumstellar disks revealed by millimeter interferometry. We detect ``warm'' (T~100-200 K) H2 gas around many sources, including tentatively the debris-disk objects. The mass of this warm gas ranges from ~10-4 Msolar up to 8×10-3 Msolar and can constitute a nonnegligible fraction of the total disk mass. Complementary single-dish 12CO 3-2, 13CO 3-2, and 12CO 6-5 observations have been obtained as well. These transitions probe cooler gas at T~20-80 K. Most objects show a double-peaked CO emission profile characteristic of a disk in Keplerian rotation, consistent with interferometer data on the lower J lines. The ratios of the 12CO 3-2/13CO 3-2 integrated fluxes indicate that 12CO 3-2 is optically thick but that 13CO 3-2 is optically thin or at most moderately thick. The 13CO 3-2 lines have been used to estimate the cold gas mass. If a H2/CO conversion factor of 1×104 is adopted, the derived cold gas masses are factors of 10-200 lower than those deduced from 1.3 millimeter dust emission assuming a gas/dust ratio of 100, in accordance with previous studies. These findings confirm that CO is not a good tracer of the total gas content in disks since it can be photodissociated in the outer layers and frozen onto grains in the cold dense part of disks, but that it is a robust tracer of the disk velocity field. In contrast, H2 can shield itself from photodissociation even in low-mass ``optically thin'' debris disks and can therefore survive longer. The warm gas is typically 1%-10% of the total mass deduced from millimeter continuum emission, but it can increase up to 100% or more for the debris-disk objects. Thus, residual molecular gas may

  12. Gas-phase reactions of carbon dioxide with atomic transition-metal and main-group cations: room-temperature kinetics and periodicities in reactivity.

    PubMed

    Koyanagi, Gregory K; Bohme, Diethard K

    2006-02-01

    The chemistry of carbon dioxide has been surveyed systematically with 46 atomic cations at room temperature using an inductively-coupled plasma/selected-ion flow tube (ICP/SIFT) tandem mass spectrometer. The atomic cations were produced at ca. 5500 K in an ICP source and allowed to cool radiatively and to thermalize by collisions with Ar and He atoms prior to reaction downstream in a flow tube in helium buffer gas at 0.35 +/- 0.01 Torr and 295 +/- 2 K. Rate coefficients and products were measured for the reactions of first-row atomic ions from K(+) to Se(+), of second-row atomic ions from Rb(+) to Te(+) (excluding Tc(+)), and of third-row atomic ions from Cs(+) to Bi(+). CO(2) was found to react in a bimolecular fashion by O atom transfer only with 9 early transition-metal cations: the group 3 cations Sc(+), Y(+), and La(+), the group 4 cations Ti(+), Zr(+), and Hf(+), the group 5 cations Nb(+) and Ta(+), and the group 6 cation W(+). Electron spin conservation was observed to control the kinetics of O atom transfer. Addition of CO(2) was observed for the remaining 37 cations. While the rate of addition was not measurable some insight was obtained into the standard free energy change, DeltaG(o), for CO(2) ligation from equilibrium constant measurements. A periodic variation in DeltaG(o) was observed for first row cations that is consistent with previous calculations of bond energies D(0)(M(+)-CO(2)). The observed trends in D(0) and DeltaG(o) are expected from the variation in electrostatic attraction between M(+) and CO(2) which follows the trend in atomic-ion size and the trend in repulsion between the orbitals of the atomic cations and the occupied orbitals of CO(2). Higher-order CO(2) cluster ions with up to four CO(2) ligands also were observed for 24 of the atomic cations while MO(2)(+) dioxide formation by sequential O atom transfer was seen only with Hf(+), Nb(+), Ta(+), and W(+). PMID:16435784

  13. Transition in Gas Turbine Control System Architecture: Modular, Distributed, and Embedded

    NASA Technical Reports Server (NTRS)

    Culley, Dennis

    2010-01-01

    Controls systems are an increasingly important component of turbine-engine system technology. However, as engines become more capable, the control system itself becomes ever more constrained by the inherent environmental conditions of the engine; a relationship forced by the continued reliance on commercial electronics technology. A revolutionary change in the architecture of turbine-engine control systems will change this paradigm and result in fully distributed engine control systems. Initially, the revolution will begin with the physical decoupling of the control law processor from the hostile engine environment using a digital communications network and engine-mounted high temperature electronics requiring little or no thermal control. The vision for the evolution of distributed control capability from this initial implementation to fully distributed and embedded control is described in a roadmap and implementation plan. The development of this plan is the result of discussions with government and industry stakeholders

  14. Do not disturb the animals! or, how Con Edison saved $300,000 using a trenchless technology to renew 3,000 feet of leaking gas main at the Bronx Zoo

    SciTech Connect

    Bufe, M.

    1995-07-01

    Every leaking gas main presents a challenge. But when that leaking main follows a series of sweeping bends on its route through North America`s largest urban wildlife park, it presents a special challenge. That was the situation Consolidated Edison Company of New York Inc. recently faced when numerous leaks were discovered along 3,000 feet of a 95-year-old, 12-inch cast-iron main that winds through New York City`s Bronx Zoo. Con Edison knew it needed a long-term solution to this increasingly common problem. Thanks to the cooperative efforts of the utility`s operations and research departments and the Gas Research Institute (GRI), Con Edison also knew about a trenchless technology that could renew the pipe with minimal impact to the environment--while saving the utility a substantial sum of money in the process. In the Paltem system, a woven polyester hose is injected with an epoxy resin and then inverted (turned inside out) into a pipe at an access pit. The liner then bonds to the inside wall of the pipe, forming a smooth, flexible and pressure-resistant lining. The process is environmentally safe, requires very little excavation and can be installed in days, rather than the weeks or months it can take to dig up and replace existing pipe.

  15. Controlling the electron energy distribution function of electron beam generated plasmas with molecular gas concentration: II. Numerical modeling

    NASA Astrophysics Data System (ADS)

    Petrov, G. M.; Boris, D. R.; Petrova, Tz B.; Lock, E. H.; Fernsler, R. F.; Walton, S. G.

    2013-12-01

    In this work, the second in a series of two, a spatially averaged model of an electron beam generated Ar-N2 plasma is developed to identify the processes behind the measured influence of trace amounts of N2 on the development of the electron energy distribution function. The model is based on the numerical solution of the electron Boltzmann equation self-consistently coupled to a set of rate balance equations for electrons, argon and nitrogen species. Like the experiments, the calculations cover only the low-energy portion (<50 eV) of the electron energy distribution, and therefore a source term is added to the Boltzmann equation to represent ionization by the beam. Similarly, terms representing ambipolar diffusion along and across the magnetic field are added to allow for particle loss and electrostatic cooling from the ambipolar electric field. This work focuses on the changes introduced by adding a small admixture of nitrogen to an argon background. The model predictions for the electron energy distribution function, electron density and temperature are in good agreement with the experimentally measured data reported in part I, where it was found that the electron and ion energy distributions can be controlled by adjusting the fraction of nitrogen in the gas composition.

  16. The spatiotemporal distribution of dissolved carbon in the main stems and their tributaries along the lower reaches of Heilongjiang River Basin, Northeast China.

    PubMed

    Wang, Lili; Song, Changchun; Guo, Yuedong

    2016-01-01

    The Heilongjiang River Basin in the eastern Siberia, one of the largest river basins draining to the North Pacific Ocean, is a border river between China, Mongolia, and Russia. In this study, we examined the spatial and seasonal variability in dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and dissolved total carbon (DTC) concentrations along lower reaches of Heilongjiang River Basin, China. Water samples were collected monthly along the mouths of main rivers (Heilongjiang River, Wusuli River, and Songhua River) and their ten tributary waters for 2 years. The DOC concentrations of waters ranged from 1.74 to 16.64 mg/L, with a mean value of 8.90 ± 0.27 mg/L (n = 165). Notably, mean DIC concentrations were 9.08 ± 0.31 mg/L, accounting for 13.26∼83.27% of DTC. DIC concentrations increased significantly after the Heilongjiang River passed through Northeast China, while DOC concentrations decreased. Over 50% of DIC concentrations were decreased during exports from groundwater to rice fields and from rice fields to ditches. Water dissolved carbon showed large spatial and temporal variations during the 2-year measurement, suggesting that more frequently samplings were required. Carbon (DIC + DOC) loads from the Heilongjiang River to the Sea of Okhotsk were estimated to be 3.26 Tg C/year in this study, accounting for 0.64% of the global water dissolved carbon flux. DIC export contributed an average of 51.84% of the estimated carbon load in the Heilongjiang River, acting as an important carbon component during riverine transport. Our study could provide some guides on agricultural water management and contribute to more accurately estimate global carbon budgets. PMID:26507729

  17. Optimum Operation Condition on Distributed Power Supply System with Micro Gas Turbine/Solid Oxide Fuel Cell

    NASA Astrophysics Data System (ADS)

    Suzuki, Hiroshi; Yamada, Miki; Usui, Hiromoto; Komoda, Yoshiyuki

    In order to find the optimum operation condition of a distributed power supply system of 30kW class micro gas turbine (MGT) and solid oxide fuel cell (SOFC) hybrid system with the combination of line electric power and supplied gas, a system analysis has been performed. In this study, an absorption chiller and a boiler were mounted to utilize the exhausted heat from the MGT/SOFC system. The time variation of energy consumption in 24 hours for house and market models was taken into consideration for the calculation of the energy saving ratio of the present system. The operation ratio defined with the ratio of power supply of MGT/SOFC system to the power required at the peak load was changed as a parameter. From the comparison with the system using line power and gas, it is found that the present system shows high energy saving ratio around 0.4 of the operation ratio, but the energy saving ratio severely decreases in the range of high operation ratio. In this study, it is revealed that the thermal storage system effectively improves the energy saving ratio especially for the house model in winter season.

  18. Costs and benefits of excess-flow valves in gas-distribution services. Final report, March 1984-December 1985

    SciTech Connect

    Atallah, S.; Pape, R.

    1985-12-01

    A comparison was made of the costs and benefits (as measured by risk reduction) associated with the use of excess-flow valves on gas-distribution services operating at > or = 10 psig. For the U.S. as a whole, and with conservative assumptions, the cost of installing and maintaining EFVs was found to be inordinately high when compared to the accrued benefits. The expenditure of a total of $8.82 billion ($451 million in 1985 dollars) over the next 50 years would be projected to prevent the occurrence of 6,250 accidents, save a total of 28 lives and 284 injuries and reduce the anticipated property damage by $6.87 million. A sensitivity analysis showed that the average cost per accident prevented was highly dependent on the age at which EFVs were assumed to be replaced and their installation rate. A computer program was provided to allow the calculation of the various costs, the corresponding benefits, and the cost/benefit ratio for individual gas distribution systems.

  19. Gas hydrate distribution and hydrocarbon maturation north of the Knipovich Ridge, western Svalbard margin

    NASA Astrophysics Data System (ADS)

    Dumke, Ines; Burwicz, Ewa B.; Berndt, Christian; Klaeschen, Dirk; Feseker, Tomas; Geissler, Wolfram H.; Sarkar, Sudipta

    2016-03-01

    A bottom-simulating reflector (BSR) occurs west of Svalbard in water depths exceeding 600 m, indicating that gas hydrate occurrence in marine sediments is more widespread in this region than anywhere else on the eastern North Atlantic margin. Regional BSR mapping shows the presence of hydrate and free gas in several areas, with the largest area located north of the Knipovich Ridge, a slow spreading ridge segment of the Mid Atlantic Ridge system. Here heat flow is high (up to 330 mW m-2), increasing toward the ridge axis. The coinciding maxima in across-margin BSR width and heat flow suggest that the Knipovich Ridge influenced methane generation in this area. This is supported by recent finds of thermogenic methane at cold seeps north of the ridge termination. To evaluate the source rock potential on the western Svalbard margin, we applied 1-D petroleum system modeling at three sites. The modeling shows that temperature and burial conditions near the ridge were sufficient to produce hydrocarbons. The bulk petroleum mass produced since the Eocene is at least 5 kt and could be as high as ~0.2 Mt. Most likely, source rocks are Miocene organic-rich sediments and a potential Eocene source rock that may exist in the area if early rifting created sufficiently deep depocenters. Thermogenic methane production could thus explain the more widespread presence of gas hydrates north of the Knipovich Ridge. The presence of microbial methane on the upper continental slope and shelf indicates that the origin of methane on the Svalbard margin varies spatially.

  20. Distribution and chemical fate of chlorine dioxide gas during sanitation of tomatoes and cantaloupe

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A series of studies was conducted to establish the 1) distribution and chemical fate of 36-ClO2 on tomatoes and cantaloupe; and 2) the magnitude of residues in kilogram quantities of tomatoes and cantaloupe sanitized with a slow-release chlorine dioxide formulation. Tomatoes and cantaloupe were resp...

  1. Imaging the Gas Distribution and Kinematics in the Early Universe with ALMA

    NASA Astrophysics Data System (ADS)

    Brown, Robert L.

    1999-12-01

    A summary is presented of the status of the Atacama Large Millimeter Array (ALMA) project. The scientific goals for the project, in particular the goals for imaging gas in early galaxies, are used to illustrate the specific needs for the development of ALMA technology making it, uniquely, a complete imaging system. The plans to achieve this development by means of common international effort and under a common Memorandum of Understanding are noted. Finally, estimates are given of the construction timescale and the principle issues that remain to be settled are highlighted.

  2. Distribution of gas-oil-bitumen shows in the Yakutian diamond province

    SciTech Connect

    Kravtsov, A.I.; Ivanov, V.A.; Bobrov, V.A.; Kropotova, O.I.

    1981-10-01

    The combination of carbon-bearing compounds in the kimberlite pipes may be divided into distinct geochemical groups, genetically associated with exogenic or endogenic geological processes. In analyzing the isotope composition of diamonds from eclogite and kimberlite, graphite in concentrated form from eclogite and ultrabasic inclusions in kimberlite, and postmagmaic carbonic acid from the matrix of kimberlite, it was established that these compounds have a distinctive endogenic nature. The isotope composition of the limestones of marine origin has been determined by the isotope-exchange reation /sup 13/CO/sub 2/ (gas) + /sup 12/CO/sub 3/ (solution) reverse arrow..-->.. /sup 12/CO/sub 2/ (gas) + /sup 13/CO/sub 3/ (solution), which is rigidly associated with temperature of sedimentation and has controlled the ''heavy'' isotope composition of these rocks. The isotope composition of the bitumens has not yet enabled us to resolve the problem of the origin of the bitumen shows (biogenic or abiogenic). However, the similarity of the isotope composition of bitumens examined from various bitumen shows indicates identical thermodynamic conditions of formation.

  3. WITNESSING GAS MIXING IN THE METAL DISTRIBUTION OF THE HICKSON COMPACT GROUP HCG 31

    SciTech Connect

    Torres-Flores, S.; Alfaro-Cuello, M.; De Oliveira, C. Mendes; Amram, P.; Carrasco, E. R.

    2015-01-01

    We present for the first time direct evidence that in a merger of disk galaxies, the pre-existing central metallicities will mix as a result of gas being transported in the merger interface region along the line that joins the two coalescing nuclei. This is shown using detailed two-dimensional kinematics as well as metallicity measurements for the nearby ongoing merger in the center of the compact group HCG 31. We focus on the emission line gas, which is extensive in the system. The two coalescing cores display similar oxygen abundances. While in between the two nuclei, the metallicity changes smoothly from one nucleus to the other indicating a mix of metals in this region, which is confirmed by the high-resolution Hα kinematics (R = 45,900). This nearby system is especially important because it involves the merging of two fairly low-mass and clumpy galaxies (LMC-like galaxies), making it an important system for comparison with high-redshift galaxies.

  4. Scaling Laws for the Distribution of Gold, Geothermal, and Gas Resources

    NASA Astrophysics Data System (ADS)

    Blenkinsop, Thomas

    2015-07-01

    Mass dimensions of natural resources have important implications for ore-forming processes and resource estimation and exploration. The mass dimension is established from a power law scaling relationship between numbers of resources and distance from an origin. The relation between the total quantity of resource and distance, measured by the mass-radius scaling exponent, may be even more useful. Lode gold deposits, geothermal wells and volcanoes, and conventional and unconventional gas wells are examined in this study. Mass dimensions and scaling exponents generally increase from the lode gold through geothermal wells to gas data sets, reflecting decreasing degrees of clustering. Mass dimensions are similar to or slightly less than the mass-radius scaling exponents, and could be used as estimates of the minimum scaling exponent in the common case that data are not available for the latter. All the resources in this study are formed by fluid fluxes in the crust, and, therefore, percolation theory is an appropriate unifying framework to understand their significance. The mass dimensions indicate that none of the percolation networks that formed the deposits reached the percolation threshold.

  5. Internal energy distribution of carboxylate negative-ions of the herbicide diclofop acid in the gas-phase

    NASA Astrophysics Data System (ADS)

    Headley, J. V.; Peru, K. M.

    1997-11-01

    Unimolecular dissociations of diclofop acid and three of its esters were studied using electron capture negative-ion mass spectrometry, to determine to what extent the gas-phase chemistry correlated with transformation products reported for the herbicide in soils and microbial biofilms. Electron capture of the trimethylsilyl (TMS) and pentafluorobenzyl (PFB) esters along with H+ abstraction of diclofop acid were used to form the carboxylate ion at m / z 325. The degree of dissociation of this ion was strongly dependent on the relative distribution of internal energies, chemical nature and size of the ester group. For carboxylate ions formed with relatively low distribution of internal energies (PFB ester), elimination of HCl only was the preferred pathway. In contrast, m / z 325 from the TMS ester and diclofop acid, underwent loss of Cl, followed by loss of HCl to give m / z 254 with some direct loss of HCl for the TMS ester. For carboxylate ions formed with little or no internal energy under electrospray ionization, no unimolecular dissociations were observed. However, a wide range of product-ions were observed for the latter using collision-induced dissociations. For the methyl ester there was a preponderance for initial formation of a chlorodibenzofuran oxide ion (m / z 217) instead of electron attachment on the carbonyl function. The ion (m / z 217) was also prevalent for fragmentation of m / z 253 produced directly by electron capture of diclofop acid and the TMS ester. In general, the gas-phase ion chemistry correlated well with the distribution of some transformation products reported in the literature for the herbicide in soils and microbial biofilms.

  6. Risk analysis of highly combustible gas storage, supply, and distribution systems in PWR plants

    SciTech Connect

    Simion, G.P.; VanHorn, R.L.; Smith, C.L.; Bickel, J.H.; Sattison, M.B.; Bulmahn, K.D.

    1993-06-01

    This report presents the evaluation of the potential safety concerns for pressurized water reactors (PWRs) identified in Generic Safety Issue 106, Piping and the Use of Highly Combustible Gases in Vital Areas. A Westinghouse four-loop PWR plant was analyzed for the risk due to the use of combustible gases (predominantly hydrogen) within the plant. The analysis evaluated an actual hydrogen distribution configuration and conducted several sensitivity studies to determine the potential variability among PWRs. The sensitivity studies were based on hydrogen and safety-related equipment configurations observed at other PWRs within the United States. Several options for improving the hydrogen distribution system design were identified and evaluated for their effect on risk and core damage frequency. A cost/benefit analysis was performed to determine whether alternatives considered were justifiable based on the safety improvement and economics of each possible improvement.

  7. Effect of ageing of gas diffusion layers on the water distribution in flow field channels of polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Kätzel, Juliane; Markötter, Henning; Arlt, Tobias; Klages, Merle; Haußmann, Jan; Messerschmidt, Matthias; Kardjilov, Nikolay; Scholta, Joachim; Banhart, John; Manke, Ingo

    2016-01-01

    We present a quantitative analysis of the influence of artificial ageing of gas diffusion layers (GDL) on the water distribution and transport in polymer electrolyte membrane fuel cells (PEMFCs) during cell operation. Water droplet size distributions are measured by means of in-operando neutron radiography. We find a strong correlation between droplet size distribution and GDL ageing time: With increasing GDL ageing, water droplet sizes in the flow field channels strongly decrease, indicating an ineffective water transport that leads to a reduced cell performance. This effect can be assigned to water accumulations on the GDL surface that block the gas supply towards the catalyst layer.

  8. Modifying the dissolved-in-water type natural gas field simulation model based on the distribution of estimated Young's modulus for the Kujukuri region, Japan

    NASA Astrophysics Data System (ADS)

    Nakagawa, T.; Matsuyama, R.; Adachi, M.; Kuroshima, S.; Ogatsu, T.; Adachi, R.

    2015-11-01

    A simulation model, which covers the part of Southern-Kanto natural gas field in Chiba prefecture, was developed to perform studies and make predictions of land subsidence. However, because large differences between simulated and measured subsidence occurred in the northern modeled area of the gas field, the model was modified with an estimated Young's modulus distribution. This distribution was estimated by the yield value distribution and the correlation of yield value with Young's modulus. Consequently, the simulated subsidence in the north area was improved to some extent.

  9. On the Distribution of Free Path Lengthsfor the Periodic Lorentz Gas

    NASA Astrophysics Data System (ADS)

    Bourgain, Jean; Golse, François; Wennberg, Bernt

    Consider the domain and let the free path length be defined as The distribution of values of is studied in the limit as for all . It is shown that the value is critical for this problem: in other words, the limiting behavior of depends only on whether γ is larger or smaller than .

  10. Instability in the dense supernova neutrino gas with flavor-dependent angular distributions.

    PubMed

    Mirizzi, Alessandro; Serpico, Pasquale Dario

    2012-06-01

    The usual description of self-induced flavor conversions for neutrinos (ν's) in supernovae is based on the simplified assumption that all the ν's of the different species are emitted "half-isotropically" by a common neutrinosphere, in analogy to a blackbody emission. However, realistic supernova simulations show that ν angular distributions at decoupling are far from being half-isotropic and, above all, are flavor dependent. We show that flavor-dependent angular distributions may lead to crossing points in the angular spectra of different ν species (where F(ν(e))=F(ν(x)) and F(ν(e))=F(ν(x))) around which a new multiangle instability can develop. To characterize this effect, we carry out a linearized flavor stability analysis for different supernova neutrino angular distributions. We find that this instability can shift the onset of the flavor conversions toward low radii and produce a smearing of the splitting features found with trivial ν emission models. As a result the spectral differences among ν's of different flavors could be strongly reduced. PMID:23003940

  11. Occurrence, distribution and expression of gas seeps and gas hydrates on the northeastern continental slope of Sakhalin Island, Sea of Okhotsk

    NASA Astrophysics Data System (ADS)

    Jin, Y.; Hong, J.; Baranov, B.; Shoji, H.; Obzhirov, A.

    2012-12-01

    The northeastern Sakhalin continental slope (NESS), Okhotsk Sea is characterized by an abundant occurrence of gas hydrate and gas seeps. Under the frameworks of Korea-Russia-Japan international projects (CHAOS and SSGH), we have carried out multidisciplinary surveys to investigate gas hydrate accumulation and active gas seepage phenomena on the NESS since 2003. During the surveys, about moe than nine hundred gas seeps were detected in a 2,650 km2 area of the NESS. Active gas seeps on the NESS were evident from features in the water column, on the seafloor, and in the subsurface by geophysical methods: well-defined hydroacoustic anomalies (gas flares), side-scan sonar seafloor structures with high backscatter intensity (seepage structures), bathymetric structures (pockmarks and mounds), and gas- and gas-hydrate-related seismic features (bottom-simulating reflectors, gas chimneys, high-amplitude reflectors, and acoustic blanking). They are also evident from ground-truths; high methane concentrations in seawater, near-bottom gas hydrates and antigenic carbonates. These features are generally related; a gas flare emits at a topographic mound with high backscatter intensity, below which a gas chimney is present. We interpret that gas chimneys producing enhanced reflection on high-resolution seismic profiles are active pathways for upward gas migration to the seafloor.

  12. Do hybrid morphology radio sources form in a lopsided distribution of cold gas?

    NASA Astrophysics Data System (ADS)

    Miller, Brendan

    2010-10-01

    We test the hypothesis that hybrid morphology radio sources (HYMORS; Gopal-Krishna & Wiita 2000) feature one-sided jet disruption caused by propagation into a large-scale overdensity of cold gas, through XMM-Newton observations of B2 1404+25A and B2 1345+28 (33 and 16 ks, respectively). These HYMORS are intrinsic low-inclination RLQs for which the X-ray spectra would ordinarily be unabsorbed. VLBA mapping places the FRI jet on the near side in B2 1404+25A, and so the putative disrupting medium can be directly detected as absorption against the core; in contrast, the FRII lobe is closer in B2 1345+28, and so a simple power-law X-ray spectrum is anticipated. Distinct results are predicted for alternative scenarios of HYMORS formation.

  13. Distribution of gas and galaxies around the distant quasar PKS 1614 + 051

    SciTech Connect

    Hu, E.M.; Cowie, L.L.

    1987-06-01

    The results of narrow-band and broad-band filter observations of the region surrounding the z = 3.21 quasars, PKS 1614 + 051, made under subarcsec seeing conditions with the 3.6 m CFHT telescope at Mauna Kea are reported. The nuclear region of the Lyman-alpha companion to the quasar is resolved with a FWHM of about 0.9 arcsec A magnitude fainter. Limits on detectable continuum flux from this object suggest that it is a gas cloud interacting with the quasar, and its emission is consistent with simple photoionization by the quasar. However, the presence of several galaxies around the periphery of the quasar is noted. A search of 11 additional quasars at z greater than 3 has failed to show any other such systems. It is argued that this is consistent with the statistics of extended emission line systems in low-z quasars. 11 references.

  14. Witnessing Gas Mixing in the Metal Distribution of the Hickson Compact Group HCG 31

    NASA Astrophysics Data System (ADS)

    Torres-Flores, S.; Mendes de Oliveira, C.; Amram, P.; Alfaro-Cuello, M.; Carrasco, E. R.; de Mello, D. F.

    2015-01-01

    We present for the first time direct evidence that in a merger of disk galaxies, the pre-existing central metallicities will mix as a result of gas being transported in the merger interface region along the line that joins the two coalescing nuclei. This is shown using detailed two-dimensional kinematics as well as metallicity measurements for the nearby ongoing merger in the center of the compact group HCG 31. We focus on the emission line gas, which is extensive in the system. The two coalescing cores display similar oxygen abundances. While in between the two nuclei, the metallicity changes smoothly from one nucleus to the other indicating a mix of metals in this region, which is confirmed by the high-resolution Hα kinematics (R = 45,900). This nearby system is especially important because it involves the merging of two fairly low-mass and clumpy galaxies (LMC-like galaxies), making it an important system for comparison with high-redshift galaxies. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina) - Observing run: GS-2012B-Q-60.

  15. Abnormal distribution of microhardness in tungsten inert gas arc butt-welded AZ61 magnesium alloy plates

    SciTech Connect

    Xu Nan; Shen Jun; Xie Weidong; Wang Linzhi; Wang Dan; Min Dong

    2010-07-15

    In this study, the effects of heat input on the distribution of microhardness of tungsten inert gas (TIG) arc welded hot-extruded AZ61 magnesium alloy joints were investigated. The results show that with an increase of heat input, the distributions of microhardness at the top and bottom of the welded joints are different because they are determined by both the effect of grain coarsening and the effect of dispersion strengthening. With an increase of the heat input, the microhardness of the heat-affected zone (HAZ) at the top and bottom of welded joints and the fusion zone (FZ) at the bottom of welded joints decreased gradually, while the microhardness of the FZ at the top of welded joints decreased initially and then increased sharply. The reason for the abnormal distribution of microhardness of the FZ at the top of the welded joints is that this area is close to the heat source during welding and then large numbers of hard {beta}-Mg{sub 17}(Al,Zn){sub 12} particles are precipitated. Hence, in this case, the effect of dispersion strengthening dominated the microhardness.

  16. On the Distribution of Free Path Lengths for the Periodic Lorentz Gas III

    NASA Astrophysics Data System (ADS)

    Caglioti, Emanuele; Golse, François

    For r(0,1), let Zr={xR2|dist(x,Z2)>r/2} and define τr(x,v)=inf{t>0|x+tv∂Zr}. Let Φr(t) be the probability that τr(x,v)>=t for x and v uniformly distributed in Zr and §1 respectively. We prove in this paper that as t-->+∞. This result improves upon the bounds on Φr in Bourgain-Golse-Wennberg [Commun. Math. Phys. 190, 491-508 (1998)]. We also discuss the applications of this result in the context of kinetic theory.

  17. Replacing London's cast iron mains

    SciTech Connect

    Thorne, A. ); Mathews, P. )

    1992-07-01

    This paper discusses the cast iron gas distribution systems that exist in many cities and contains considerable amounts of pipe that vary in age from 20 to 150 years. In many ways, cast iron is an excellent material. It is inherently corrosion resistant, easy to install and cheap. However, it is also brittle and smaller diameter cast iron pipe has a relatively low beam strength. This can lead, under some circumstances, to failure without external warning, with typically a full-circumferential failure. In congested areas this can lead to serious consequences. As a result, cast iron replacement programs are a common feature in such urban gas distribution systems.

  18. Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems

    PubMed Central

    Tassi, Franco; Montegrossi, Giordano; Capecchiacci, Francesco; Vaselli, Orlando

    2010-01-01

    The composition of non-methane organic volatile compounds (VOCs) determined in 139 thermal gas discharges from 18 different geothermal and volcanic systems in Italy and Latin America, consists of C2–C20 species pertaining to the alkanes, alkenes, aromatics and O-, S- and N-bearing classes of compounds. Thiophenes and mono-aromatics, especially the methylated species, are strongly enriched in fluids emissions related to hydrothermal systems. Addition of hydrogen sulphide to dienes and electrophilic methylation involving halogenated radicals may be invoked for the formation of these species. On the contrary, the formation of furans, with the only exception of C4H8O, seems to be favoured at oxidizing conditions and relatively high temperatures, although mechanisms similar to those hypothesized for the production of thiophenes can be suggested. Such thermodynamic features are typical of fluid reservoirs feeding high-temperature thermal discharges of volcanoes characterised by strong degassing activity, which are likely affected by conspicuous contribution from a magmatic source. The composition of heteroaromatics in fluids naturally discharged from active volcanoes and geothermal areas can then be considered largely dependent on the interplay between hydrothermal vs. magmatic contributions. This implies that they can be used as useful geochemical tools to be successfully applied in both volcanic monitoring and geothermal prospection. PMID:20480029

  19. Possible health effects of liquefied petroleum gas on workers at filling and distribution stations of Gaza governorates.

    PubMed

    Sirdah, M M; Al Laham, N A; El Madhoun, R A

    2013-03-01

    Liquefied petroleum gas (LPG) is widely used in the Gaza Strip for domestic purposes, in agriculture and industry and, illegally, in cars. This study aimed to identify possible health effects on workers exposed to LPG in Gaza governorates. Data were collected by a questionnaire interview, and haematological and biochemical analyses of venous blood samples were made from 30 workers at filling and distribution stations and 30 apparently healthy controls. Statistically significant differences were found in all self-reported health-related complaints among LPG workers versus controls. LPG workers had significantly higher values of red blood cell counts, haemoglobin, haematocrit mean corpuscular haemoglobin and platelet counts. They also had significantly higher values of kidney function tests (urea, creatinine and uric acid) and liver function enzyme activities (aspartate aminotransferase and alanine aminotransferase). LPG workers at Gaza Strip petroleum stations are at higher risk for health-related symptoms and clinical abnormalities. PMID:23879082

  20. Yet Another Spectro-Interferometric Study of The Gas Distribution in The Enigmatic Semi-Detached Binary β Lyrae

    NASA Astrophysics Data System (ADS)

    Nemravová, J.; Mourard, D.; Harmanec, P.; Meilland, A.

    2015-12-01

    The majority of close binaries undergo episodes of mass transfer between their components, which completely change their further evolution. Simulations and observations agree that the mass transfer has two phases: i) short and rapid one, and ii) long and slow one. The bulk of the mass is likely exchanged during the rapid phase, but due to its shortness, systems undergoing this phase are rare, but they hold the key to understanding of the process. One system that is either undergoing the rapid mass transfer phase or is in a transient phase between the two phases is β Lyrae. Our goal is to map the distribution of circumstellar gas in the system. To achieve it, a series of spectro-interferometric observations acquired with the optical instrument VEGA/CHARA are investigated. Here we present our tools and preliminary results of our analysis.

  1. Asymptotic Limit of Momentum Distribution Functions in the Sudden Expansion of a Spin-imbalanced Fermi Gas in One Dimension

    NASA Astrophysics Data System (ADS)

    Heidrich-Meisner, Fabian; Bolech, Carlos; Langer, Stephan; McCulloch, Ian; Orso, Giuliano; Rigol, Marcos

    2013-03-01

    We study the sudden expansion of a spin-imbalanced Fermi gas in an optical lattice after quenching the trapping potential to zero, described by the attractive Hubbard model. Using time-dependent density matrix renormalization group simulations we demonstrate that the momentum distribution functions (MDFs) of majority and minority fermions become stationary after surprisingly short expansion times. We explain this via a quantum distillation mechanism that results in a spatial separation of excess fermions and pairs, causing Fulde-Ferrell-Larkin-Ovchinnikov correlations to disappear rapidly. We further argue that the asymptotic form of the MDFs is determined by the integrals of motion of this integrable quantum system, namely the rapidities from the Bethe ansatz solution. We discuss the relevance of our results for the observation of Fulde-Ferrell-Larkin-Ovchinnikov correlations in 1D systems, related to recent experiments from Rice University.

  2. Mapping the Distribution of 10(-6) K Gas Toward the Galactic Poles

    NASA Astrophysics Data System (ADS)

    Juda, M.

    1996-05-01

    The diffuse 1/4 keV background at high galactic latitude is a combination of emission from the local interstellar medium (LISM), the galactic halo, and the extragalactic background. Separation of the LISM contribution from the distant ones can be accomplished via the detection of intensity variations in the 1/4 keV background caused by absorption by intervening neutral material. I have searched the ROSAT archive for PSPC observations with |b|>60deg that are coincident with the IRAS 100 mu m enhancements identified by Desert, Bazell, & Boulanger (1988) as likely molecular cirrus clouds. For each field, I have generated maps of the intensity in the 1/4 keV band following the procedure suggested by Snowden et al. (1994) and fit for an anticorrelation with the 100 mu m intensity. I will present preliminary results for the derived intensity distributions for the LISM and distant components.

  3. Regularities in the distribution of star/gas complexes in the spiral arms of our galaxy and M31

    NASA Astrophysics Data System (ADS)

    Efremov, Yu. N.

    2009-08-01

    The fragmentation of gaseous spiral arms in the outer Galaxy into superclouds has been studied using recently published data on the HI distribution in the Galactic disk. Regular chains of superclouds have been found or confirmed in the Cygnus (Outer) and Carina arms, with the spacings between the superclouds being concentrated near 0.1 and 0.2 of the solar Galactocentric distance. The star complexes in the northwestern arm of the galaxy M31 are spaced, on average, 1.2 kpc apart, with the most distinct chain of complexes being located in the arm region where Beck et al. (1989) detected a strong and wavy (along the arm) magnetic field. Its wavelength turns out to be related to the spacing between the complexes. In this arm, the HII regions lie inside the star complexes, which, in turn, are located inside the gas-dust lane. In contrast, the southwestern arm of M31 is split into a gas-dust lane and a dense stellar arm, which is not fragmented into star complexes. Here, the HII regions are located along the boundary between the gas-dust and stellar components of the arm; other evidence for the presence of a spiral shock wave triggering star formation is also observed, which is probably attributable to the large pitch angle of this segment of the southwestern arm. It may be suggested that the shock wave rapidly leads to star formation everywhere in this arm, while in the northwestern arm, where the shock wave is absent, star formation begins in the superclouds formed along the arm by the magneto-gravitational instability. This is how the chains of star complexes in the northwestern arm of M31 and, obviously, the chains of superclouds in the Carina and Cygnus arms of our Galaxy have been formed. The detection of a regularmagnetic field in the corresponding segments of these arms can be predicted.

  4. Leaf gas exchange and nutrient use efficiency help explain the distribution of two Neotropical mangroves under contrasting flooding and salinity

    USGS Publications Warehouse

    Cardona-Olarte, Pablo; Krauss, Ken W.; Twilley, Robert R.

    2013-01-01

    Rhizophora mangle and Laguncularia racemosa co-occur along many intertidal floodplains in the Neotropics. Their patterns of dominance shift along various gradients, coincident with salinity, soil fertility, and tidal flooding. We used leaf gas exchange metrics to investigate the strategies of these two species in mixed culture to simulate competition under different salinity concentrations and hydroperiods. Semidiurnal tidal and permanent flooding hydroperiods at two constant salinity regimes (10 g L−1 and 40 g L−1) were simulated over 10 months. Assimilation (A), stomatal conductance (gw), intercellular CO2 concentration (Ci), instantaneous photosynthetic water use efficiency (PWUE), and photosynthetic nitrogen use efficiency (PNUE) were determined at the leaf level for both species over two time periods. Rhizophora mangle had significantly higher PWUE than did L. racemosa seedlings at low salinities; however, L. racemosa had higher PNUE and stomatal conductance and gw, accordingly, had greater intercellular CO2 (calculated) during measurements. Both species maintained similar capacities for assimilation at 10 and 40 g L−1 salinity and during both permanent and tidal hydroperiod treatments. Hydroperiod alone had no detectable effect on leaf gas exchange. However, PWUE increased and PNUE decreased for both species at 40 g L−1 salinity compared to 10 g L−1. At 40 g L−1 salinity, PNUE was higher for L. racemosa than R. mangle with tidal flooding. These treatments indicated that salinity influences gas exchange efficiency, might affect how gases are apportioned intercellularly, and accentuates different strategies for distributing leaf nitrogen to photosynthesis for these two species while growing competitively.

  5. ZTEK`s ultra-high efficiency fuel cell/gas turbine system for distributed generation

    SciTech Connect

    Hsu, M.; Nathanson, D.; Bradshaw, D.T.

    1996-12-31

    Ztek`s Planar Solid Oxide Fuel Cell (SOFC) system has exceptional potential for utility electric power generation because of: simplicity of components construction, capability for low cost manufacturing, efficient recovery of very high quality by-product heat (up to 1000{degrees}C), and system integration simplicity. Utility applications of the Solid Oxide Fuel Cell are varied and include distributed generation units (sub-MW to 30MW capacity), repowering existing power plants (i.e. 30MW to 100MW), and multi-megawatt central power plants. A TVA/EPRI collaboration program involved functional testing of the advanced solid oxide fuel cell stacks and design scale-up for distributed power generation applications. The emphasis is on the engineering design of the utility modules which will be the building blocks for up to megawatt scale power plants. The program has two distinctive subprograms: Verification test on a 1 kW stack and 25kW module for utility demonstration. A 1 kW Planar SOFC stack was successfully operated for 15,000 hours as of December, 1995. Ztek began work on a 25kW SOFC Power System for TVA, which plans to install the 25kW SOFC at a host site for demonstration in 1997. The 25kW module is Ztek`s intended building block for the commercial use of the Planar SOFC. Systems of up to megawatt capacity can be obtained by packaging the modules in 2-dimensional or 3-dimensional arrays.

  6. Two and three-dimensional segmentation of hyperpolarized 3He magnetic resonance imaging of pulmonary gas distribution

    NASA Astrophysics Data System (ADS)

    Heydarian, Mohammadreza; Kirby, Miranda; Wheatley, Andrew; Fenster, Aaron; Parraga, Grace

    2012-03-01

    A semi-automated method for generating hyperpolarized helium-3 (3He) measurements of individual slice (2D) or whole lung (3D) gas distribution was developed. 3He MRI functional images were segmented using two-dimensional (2D) and three-dimensional (3D) hierarchical K-means clustering of the 3He MRI signal and in addition a seeded region-growing algorithm was employed for segmentation of the 1H MRI thoracic cavity volume. 3He MRI pulmonary function measurements were generated following two-dimensional landmark-based non-rigid registration of the 3He and 1H pulmonary images. We applied this method to MRI of healthy subjects and subjects with chronic obstructive lung disease (COPD). The results of hierarchical K-means 2D and 3D segmentation were compared to an expert observer's manual segmentation results using linear regression, Pearson correlations and the Dice similarity coefficient. 2D hierarchical K-means segmentation of ventilation volume (VV) and ventilation defect volume (VDV) was strongly and significantly correlated with manual measurements (VV: r=0.98, p<.0001 VDV: r=0.97, p<.0001) and mean Dice coefficients were greater than 92% for all subjects. 3D hierarchical K-means segmentation of VV and VDV was also strongly and significantly correlated with manual measurements (VV: r=0.98, p<.0001 VDV: r=0.64, p<.0001) and the mean Dice coefficients were greater than 91% for all subjects. Both 2D and 3D semi-automated segmentation of 3He MRI gas distribution provides a way to generate novel pulmonary function measurements.

  7. Constraining the sub-au-scale distribution of hydrogen and carbon monoxide gas around young stars with the Keck Interferometer

    NASA Astrophysics Data System (ADS)

    Eisner, J. A.; Hillenbrand, L. A.; Stone, Jordan M.

    2014-09-01

    We present Keck Interferometer (KI) observations of T Tauri and Herbig Ae/Be stars with a spatial resolution of a few milliarcseconds and a spectral resolution of ˜2000. Our observations span the K band, and include the Brγ transition of hydrogen and the v = 2 → 0 and v = 3 → 1 transitions of carbon monoxide. For several targets, we also present data from Keck/NIRSPEC that provide higher spectral resolution, but a seeing-limited spatial resolution, of the same spectral features. We analyse the Brγ emission in the context of both disc and infall/outflow models, and conclude that the Brγ emission traces gas at very small stellocentric radii, consistent with the magnetospheric scale. However, some Brγ-emitting gas also seems to be located at radii of ≳ 0.1 au, perhaps tracing the inner regions of magnetically launched outflows. CO emission is detected from several objects, and we generate disc models that reproduce both the KI and NIRSPEC data well. We infer the CO spatial distribution to be coincident with the distribution of continuum emission in most cases. Furthermore, the Brγ emission in these objects is roughly coincident with both the CO and continuum emission. We present potential explanations for the spatial coincidence of continuum, Brγ, and CO overtone emission, and explore the implications for the low occurrence rate of CO overtone emission in young stars. Finally, we provide additional discussion of V1685 Cyg, which is unusual among our sample in showing large differences in emitting region size and spatial position as a function of wavelength.

  8. Polycyclic aromatic hydrocarbons in air on small spatial and temporal scales - II. Mass size distributions and gas-particle partitioning

    NASA Astrophysics Data System (ADS)

    Lammel, Gerhard; Klánová, Jana; Ilić, Predrag; Kohoutek, Jiří; Gasić, Bojan; Kovacić, Igor; Škrdlíková, Lenka

    2010-12-01

    Polycyclic aromatic hydrocarbons (PAHs) were measured together with inorganic air pollutants at two urban sites and one rural background site in the Banja Luka area, Bosnia and Hercegovina, during 72 h in July 2008 using a high time resolution (5 samples per day) with the aim to study gas-particle partitioning, aerosol mass size distributions and to explore the potential of a higher time resolution (4 h-sampling). In the particulate phase the mass median diameters of the PAHs were found almost exclusively in the accumulation mode (0.1-1.0 μm of size). These were larger for semivolatile PAHs than for non-volatile PAHs. Gas-particle partitioning of semivolatile PAHs was strongly influenced by temperature. The results suggest that the Junge-Pankow model is inadequate to explain the inter-species variation and another process must be significant for phase partitioning which is less temperature sensitive than adsorption. Care should be taken when interpreting slopes m of plots of the type log K p = m log p L0 + b based on 24 h means, as these are found sensitive to the time averaging, i.e. tend to be higher than when based on 12 h-mean samples.

  9. Dual Layer Monolith ATR of Pyrolysis Oil for Distributed Synthesis Gas Production

    SciTech Connect

    Lawal, Adeniyi

    2012-09-29

    We have successfully demonstrated a novel reactor technology, based on BASF dual layer monolith catalyst, for miniaturizing the autothermal reforming of pyrolysis oil to syngas, the second and most critical of the three steps for thermochemically converting biomass waste to liquid transportation fuel. The technology was applied to aged as well as fresh samples of pyrolysis oil derived from five different biomass feedstocks, namely switch-grass, sawdust, hardwood/softwood, golden rod and maple. Optimization of process conditions in conjunction with innovative reactor system design enabled the minimization of carbon deposit and control of the H2/CO ratio of the product gas. A comprehensive techno-economic analysis of the integrated process using in part, experimental data from the project, indicates (1) net energy recovery of 49% accounting for all losses and external energy input, (2) weight of diesel oil produced as a percent of the biomass to be ~14%, and (3) for a demonstration size biomass to Fischer-Tropsch liquid plant of ~ 2000 daily barrels of diesel, the price of the diesel produced is ~$3.30 per gallon, ex. tax. However, the extension of catalyst life is critical to the realization of the projected economics. Catalyst deactivation was observed and the modes of deactivation, both reversible and irreversible were identified. An effective catalyst regeneration strategy was successfully demonstrated for reversible catalyst deactivation while a catalyst preservation strategy was proposed for preventing irreversible catalyst deactivation. Future work should therefore be focused on extending the catalyst life, and a successful demonstration of an extended (> 500 on-stream hours) catalyst life would affirm the commercial viability of the process.

  10. Chemistry, morphology, and distribution of illites from Morecambe gas field, Irish Sea, offshore United Kingdom

    SciTech Connect

    Macchi, L. ); Curtis, C.D.; Hughes, C.R. ); Levison, A.; Woodward, K. )

    1990-03-01

    Morecambe field is centered on Block 110/2, 26 mi (42 km) off the northwestern coast of England. The gas-bearing structure occurs in Triassic sandstones with the top of the reservoir at an average depth of 3,000 ft (915 m), about 6,500 ft (2 km) less than maximum burial. Production is constrained by the presence of coarse-textured (crystals often > 20 {mu}m) platy illite. Thin-section and scanning electron microscopy have shown this phase to have a well developed, pore-bridging boxwork texture and indicates a depth zonation in which platy illite occurs below a productive illite-free interval and above a zone of fibrous illite. The top of the platy illite zone forms a mappable datum but cannot be predicted from present structure. Illite also is present throughout the reservoir as grain-tangential rims and as a replacement of unstable framework grains, matrix clays, and neoformed kaolinite cement. Analytical transmission electron microscopy, used to define the chemistry of the illites, has shown that all morphological types (grain tangential, replacement, platy, and fibrous) have compositions close to phengitic muscovite. A calculated maximum paleotemperature of 270{degree}F (132{degree}C) indicates that phengite can form as a lower temperature mineral than hitherto has been recognized. Excluding replacement illite, which has no specific association with respect to the sandstone pore system, minor increases in Al/Si and K/Mg + Fe ratio (0.69 to 0.72 and 1.86 to 2.26, respectively) correspond to the morphological change from tangential/fibrous to platy. This suggests that platy illite represents the closest approach to ideal muscovite. Geochemistry indicates that either K-feldspar dissolution or brines could have provided K for illitization.

  11. Subarcsecond observations of NGC 7538 IRS 1: Continuum distribution and dynamics of molecular gas

    SciTech Connect

    Zhu, Lei; Shi, Hui; Zhao, Jun-Hui; Wright, M. C. H.; Sandell, Göran; Wu, Yue-Fang; Brogan, Crystal; Corder, Stuartt

    2013-12-10

    We report new results based on the analysis of the Submillimeter Array (SMA) and Combined Array for Research in Millimeter-wave Astronomy (CARMA) observations of NGC 7538 IRS 1 at 1.3 and 3.4 mm with subarcsecond resolutions. With angular resolutions ∼0.''7, the SMA and CARMA observations show that the continuum emission at 1.3 and 3.4 mm from the hyper-compact H II region IRS 1 is dominated by a compact source with a tail-like extended structure to the southwest of IRS 1. With a CARMA B-array image at 1.3 mm convolved to 0.''1, we resolve the hyper-compact H II region into two components: an unresolved hyper-compact core, and a north-south extension with linear sizes of <270 AU and ∼2000 AU, respectively. The fine structure observed with CARMA is in good agreement with the previous Very Large Array results at centimeter wavelengths, suggesting that the hyper-compact H II region at the center of IRS 1 is associated with an ionized bipolar outflow. We image the molecular lines OCS(19-18) and CH{sub 3}CN(12-11) as well as {sup 13}CO(2-1) surrounding IRS 1, showing a velocity gradient along the southwest-northeast direction. The spectral line profiles in {sup 13}CO(2-1), CO(2-1), and HCN(1-0) observed toward IRS 1 show broad redshifted absorption, providing evidence for gas infall with rates in the range of 3-10 × 10{sup –3} M {sub ☉} yr{sup –1} inferred from our observations.

  12. Electrical Resistivity Investigation of Gas Hydrate Distribution in Mississippi Canyon Block 118, Gulf of Mexico

    SciTech Connect

    Dunbar, John

    2012-12-31

    Electrical methods offer a geophysical approach for determining the sub-bottom distribution of hydrate in deep marine environments. Methane hydrate is essentially non-conductive. Hence, sediments containing hydrate are more resistive than sediments without hydrates. To date, the controlled source electromagnetic (CSEM) method has been used in marine hydrates studies. This project evaluated an alternative electrical method, direct current resistivity (DCR), for detecting marine hydrates. DCR involves the injection of direct curren