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Sample records for advanced two-stage pressurized

  1. Advanced two-stage compressor program design of inlet stage

    NASA Technical Reports Server (NTRS)

    Bryce, C. A.; Paine, C. J.; Mccutcheon, A. R. S.; Tu, R. K.; Perrone, G. L.

    1973-01-01

    The aerodynamic design of an inlet stage for a two-stage, 10/1 pressure ratio, 2 lb/sec flow rate compressor is discussed. Initially a performance comparison was conducted for an axial, mixed flow and centrifugal second stage. A modified mixed flow configuration with tandem rotors and tandem stators was selected for the inlet stage. The term conical flow compressor was coined to describe a particular type of mixed flow compressor configuration which utilizes axial flow type blading and an increase in radius to increase the work input potential. Design details of the conical flow compressor are described.

  2. Two-stage, low noise advanced technology fan. 5: Acoustic final report

    NASA Technical Reports Server (NTRS)

    Sofrin, T. G.; Riloff, N., Jr.

    1975-01-01

    The NASA Q2S(quiet two-stage) fan is a 0.836m (32.9 in.) diameter model of the STF 433 engine fan, selected in a 1972 study for an Advanced Technology Transport (ATT) airplane. Noise-control features include: low tip speed, moderate stage pressure rise, large blade-vane spacings, no inlet guide vanes, and optimum blade and vane numbers. Tests were run on the baseline Q2S fan with standard inlet and discharge ducts. Further tests were made of a translating centerbody sonic inlet device and treated discharge ducts. Results were scaled to JT8D and JT3D engine fan size for comparison with current two-stage fans, and were also scaled to STF 433 fan size to compare calculated ATT flyover noise with FAR 36 limits. Baseline Q2S results scaled to JT8D and JT3D engine fan sizes showed substantial noise reductions. Calculated unsuppressed baseline ATT flyovers averaged about 2.5 EPNdB below FAR 36 limits. Using measured sonic inlet results, scaled baseline Q2S fan results, and calculated attenuations for a 1975 technology duct liner, projected flyover noise calculations for the ATT averaged about FAR 36 limits minus 10 EPNdB. Advances in suppression technology required to meet the 1985 goal of FAR 36 limits minus 20 EPNdB are discussed.

  3. High pressure studies using two-stage diamond micro-anvils grown by chemical vapor deposition

    DOE PAGES

    Vohra, Yogesh K.; Samudrala, Gopi K.; Moore, Samuel L.; ...

    2015-06-10

    Ultra-high static pressures have been achieved in the laboratory using a two-stage micro-ball nanodiamond anvils as well as a two-stage micro-paired diamond anvils machined using a focused ion-beam system. The two-stage diamond anvils’ designs implemented thus far suffer from a limitation of one diamond anvil sliding past another anvil at extreme conditions. We describe a new method of fabricating two-stage diamond micro-anvils using a tungsten mask on a standard diamond anvil followed by microwave plasma chemical vapor deposition (CVD) homoepitaxial diamond growth. A prototype two stage diamond anvil with 300 μm culet and with a CVD diamond second stage ofmore » 50 μm in diameter was fabricated. We have carried out preliminary high pressure X-ray diffraction studies on a sample of rare-earth metal lutetium sample with a copper pressure standard to 86 GPa. Furthermore, the micro-anvil grown by CVD remained intact during indentation of gasket as well as on decompression from the highest pressure of 86 GPa.« less

  4. High pressure studies using two-stage diamond micro-anvils grown by chemical vapor deposition

    SciTech Connect

    Vohra, Yogesh K.; Samudrala, Gopi K.; Moore, Samuel L.; Montgomery, Jeffrey M.; Tsoi, Georgiy M.; Velisavljevic, Nenad

    2015-06-10

    Ultra-high static pressures have been achieved in the laboratory using a two-stage micro-ball nanodiamond anvils as well as a two-stage micro-paired diamond anvils machined using a focused ion-beam system. The two-stage diamond anvils’ designs implemented thus far suffer from a limitation of one diamond anvil sliding past another anvil at extreme conditions. We describe a new method of fabricating two-stage diamond micro-anvils using a tungsten mask on a standard diamond anvil followed by microwave plasma chemical vapor deposition (CVD) homoepitaxial diamond growth. A prototype two stage diamond anvil with 300 μm culet and with a CVD diamond second stage of 50 μm in diameter was fabricated. We have carried out preliminary high pressure X-ray diffraction studies on a sample of rare-earth metal lutetium sample with a copper pressure standard to 86 GPa. Furthermore, the micro-anvil grown by CVD remained intact during indentation of gasket as well as on decompression from the highest pressure of 86 GPa.

  5. Two-stage, low noise advanced technology fan. Volume 2: Aerodynamic data

    NASA Technical Reports Server (NTRS)

    Harley, K. G.; Odegard, P. A.

    1975-01-01

    Aerodynamic data from static tests of a two-stage advanced technology fan designed to minimize noise are presented. Fan design conditions include delivery of 209.1kg/sec/sq m (42.85 lbm/sec/sq ft) specific corrected flow at an overall pressure ratio of 1.9 and an adiabatic efficiency of 85.3 percent. The 0.836m (2.74ft) diameter first stage rotor has a hub/tip ratio of 0.4 and 365.8m/sec (1200ft/sec) design tip speed. In addition to the moderate tip speed and pressure rise per stage, other noise control design features involve widely spaced blade rows and proper selection of blade-vane ratios. Aerodynamic data are presented for tests with unifrom and with hub and tip radially distorted inlet flow. Aerodynamic data are also presented for tests of this fan with acoustic treatments, including acoustically treated casing walls, a flowpath exit acoustic ring, and a translating centerbody sonic inlet device. A complete tabulation of the overall performance data, the blade element data, and the power spectral density information relating to turbulence levels generated by the sonic inlet obtained during these tests is included. For vol. 1, see N74-33789.

  6. Two-stage, low noise advanced technology fan. 4: Aerodynamic final report

    NASA Technical Reports Server (NTRS)

    Harley, K. G.; Keenan, M. J.

    1975-01-01

    A two-stage research fan was tested to provide technology for designing a turbofan engine for an advanced, long range commercial transport having a cruise Mach number of 0.85 -0.9 and a noise level 20 EPNdB below current requirements. The fan design tip speed was 365.8m/sec (1200ft/sec);the hub/tip ratio was 0.4; the design pressure ratio was 1.9; and the design specific flow was 209.2 kg/sec/sq m(42.85lbm/sec/sq ft). Two fan-versions were tested: a baseline configuration, and an acoustically treated configuration with a sonic inlet device. The baseline version was tested with uniform inlet flow and with tip-radial and hub-radial inlet flow distortions. The baseline fan with uniform inlet flow attained an efficiency of 86.4% at design speed, but the stall margin was low. Tip-radial distortion increased stall margin 4 percentage points at design speed and reduced peak efficiency one percentage point. Hub-radial distortion decreased stall margin 4 percentage points at all speeds and reduced peak efficiency at design speed 8 percentage points. At design speed, the sonic inlet in the cruise position reduced stall margin one percentage point and efficiency 1.5 to 4.5 percentage points. The sonic inlet in the approach position reduced stall margin 2 percentage points.

  7. Effect of casing treatment on performance of a two-stage high-pressure-ratio fan

    NASA Technical Reports Server (NTRS)

    Urasek, D. C.

    1979-01-01

    A two-stage fan, previously tested with a solid casing, was tested with a casing with circumferential grooves over the tips of both rotors (casing treatment). Tests were conducted at 80 and 100 percent of design speed with uniform flow. The casing treatment improved the flow range and stall margin significantly without changing the characteristics overall performance curves of total-pressure and efficiency as functions of weight flow, other than extending them to lower weight flows.

  8. Influence of pressures up to 50bar on two-stage anaerobic digestion.

    PubMed

    Merkle, Wolfgang; Baer, Katharina; Lindner, Jonas; Zielonka, Simon; Ortloff, Felix; Graf, Frank; Kolb, Thomas; Jungbluth, Thomas; Lemmer, Andreas

    2017-05-01

    The concept of pressurized two-stage anaerobic digestion integrates biogas production, purification and pressure boosting within one process. The produced methane-rich biogas can be fed into gas grids with considerably less purification effort. To investigate biogas production under high pressures up to 50bar, a lab scale two-stage anaerobic digestion system was constructed including one continuously operated pressurized methane reactor. This investigation examined the effects of different operating pressures in methane reactor (10, 25, 50bar) on biogas quantity and quality, pH value and process stability. By increasing operating pressures in methane reactor, the pH value decreased from 6.65 at 10bar to 6.55 at 50bar. Simultaneously, methane content increased from 79.08% at 10bar to 90.45% at 50bar. The results show that methane reactors can be operated up to 50bar pressure continuously representing a viable alternative to commonly used gas upgrading methods because of reduced purification effort.

  9. A Two Stage Solution Procedure for Production Planning System with Advance Demand Information

    NASA Astrophysics Data System (ADS)

    Ueno, Nobuyuki; Kadomoto, Kiyotaka; Hasuike, Takashi; Okuhara, Koji

    We model for ‘Naiji System’ which is a unique corporation technique between a manufacturer and suppliers in Japan. We propose a two stage solution procedure for a production planning problem with advance demand information, which is called ‘Naiji’. Under demand uncertainty, this model is formulated as a nonlinear stochastic programming problem which minimizes the sum of production cost and inventory holding cost subject to a probabilistic constraint and some linear production constraints. By the convexity and the special structure of correlation matrix in the problem where inventory for different periods is not independent, we propose a solution procedure with two stages which are named Mass Customization Production Planning & Management System (MCPS) and Variable Mesh Neighborhood Search (VMNS) based on meta-heuristics. It is shown that the proposed solution procedure is available to get a near optimal solution efficiently and practical for making a good master production schedule in the suppliers.

  10. Pressurization System Modeling for a Generic Bimese Two- Stage-to-Orbit Reusable Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Mazurkivich, Pete; Chandler, Frank; Nguyen, Han

    2005-01-01

    A pressurization system model was developed for a generic bimese Two-Stage-to-orbit Reusable Launch Vehicle using a cross-feed system and operating with densified propellants. The model was based on the pressurization system model for a crossfeed subscale water test article and was validated with test data obtained from the test article. The model consists of the liquid oxygen and liquid hydrogen pressurization models, each made up of two submodels, Booster and Orbiter tank pressurization models. The tanks are controlled within a 0.2-psi band and pressurized on the ground with ambient helium and autogenously in flight with gaseous oxygen and gaseous hydrogen. A 15-psi pressure difference is maintained between the Booster and Orbiter tanks to ensure crossfeed check valve closure before Booster separation. The analysis uses an ascent trajectory generated for a generic bimese vehicle and a tank configuration based on the Space Shuttle External Tank. It determines the flow rates required to pressurize the tanks on the ground and in flight, and demonstrates the model's capability to analyze the pressurization system performance of a full-scale bimese vehicle with densified propellants.

  11. Exprimental Results of the First Two Stages of an Advanced Transonic Core Compressor Under Isolated and Multi-Stage Conditions.

    NASA Technical Reports Server (NTRS)

    Prahst, Patricia S.; Kulkarni, Sameer; Sohn, Ki H.

    2015-01-01

    NASA's Environmentally Responsible Aviation (ERA) Program calls for investigation of the technology barriers associated with improved fuel efficiency for large gas turbine engines. Under ERA, the highly loaded core compressor technology program attempts to realize the fuel burn reduction goal by increasing overall pressure ratio of the compressor to increase thermal efficiency of the engine. Study engines with overall pressure ratio of 60 to 70 are now being investigated. This means that the high pressure compressor would have to almost double in pressure ratio while keeping a high level of efficiency. NASA and GE teamed to address this challenge by testing the first two stages of an advanced GE compressor designed to meet the requirements of a very high pressure ratio core compressor. Previous test experience of a compressor which included these front two stages indicated a performance deficit relative to design intent. Therefore, the current rig was designed to run in 1-stage and 2-stage configurations in two separate tests to assess whether the bow shock of the second rotor interacting with the upstream stage contributed to the unpredicted performance deficit, or if the culprit was due to interaction of rotor 1 and stator 1. Thus, the goal was to fully understand the stage 1 performance under isolated and multi-stage conditions, and additionally to provide a detailed aerodynamic data set for CFD validation. Full use was made of steady and unsteady measurement methods to understand fluid dynamics loss source mechanisms due to rotor shock interaction and endwall losses. This paper will present the description of the compressor test article and its measured performance and operability, for both the single stage and two stage configurations. We focus the paper on measurements at 97% corrected speed with design intent vane setting angles.

  12. Study of Boundary Layer Development in a Two-Stage Low-Pressure Turbine

    NASA Technical Reports Server (NTRS)

    Dorney, Daniel J.; Ashpis, David E.; Halstead, David E.; Wisler, David C.

    1999-01-01

    Experimental data from jet-engine tests have indicated that unsteady blade row interactions and separation can have a significant impact on the efficiency of low-pressure turbine stages. Measured turbine efficiencies at takeoff can be as much as two points higher than those at cruise conditions. Several recent studies have revealed that Reynolds number effects may contribute to the lower efficiencies at cruise conditions. In the current study numerical simulations have been performed to study the boundary layer development in a two-stage low-pressure turbine, and to evaluate the transition models available for low Reynolds number flows in turbomachinery. The results of the simulations have been compared with experimental data, including airfoil loadings and integral boundary layer quantities. The predicted unsteady results display similar trends to the experimental data, but significantly overestimate the amplitude of the unsteadiness. The time-averaged results show close agreement with the experimental data.

  13. Two stage low noise advanced technology fan. 1: Aerodynamic, structural, and acoustic design

    NASA Technical Reports Server (NTRS)

    Messenger, H. E.; Ruschak, J. T.; Sofrin, T. G.

    1974-01-01

    A two-stage fan was designed to reduce noise 20 db below current requirements. The first-stage rotor has a design tip speed of 365.8 m/sec and a hub/tip ratio of 0.4. The fan was designed to deliver a pressure ratio of 1.9 with an adiabatic efficiency of 85.3 percent at a specific inlet corrected flow of 209.2kg/sec/sq m. Noise reduction devices include acoustically treated casing walls, a flowpath exit acoustic splitter, a translating centerbody sonic inlet device, widely spaced blade rows, and the proper ratio of blades and vanes. Multiple-circular-arc rotor airfoils, resettable stators, split outer casings, and capability to go to close blade-row spacing are also included.

  14. Study of Boundary Layer Development in a Two-Stage Low-Pressure Turbine

    NASA Technical Reports Server (NTRS)

    Dorney, Daniel J.; Ashpis, David E.; Halstead, David E.; Wisler, David C.

    1998-01-01

    Experimental data from jet-engine tests have indicated that unsteady blade row (wake) interactions and separation can have a significant impact on the efficiency of turbine stages. The effects of these interactions can be intensified in low-pressure turbine stages because of the low Reynolds number operating environment. Measured turbine efficiencies at takeoff can be as much as two points higher than those at cruise conditions. Thus, during the last decade a significant amount of effort has been put into determining the effects of transition and turbulence on the performance of low pressure turbine stages. Experimental investigations have been performed, for example, by Hodson et al. and Halstead et al. These investigations have helped identify/clarify the roles that factors such as the Reynolds number, free stream turbulence intensity, pressure gradient and curvature have in the generation of losses. In parallel to the experimental investigations, there have been significant analytical efforts to improve the modeling of transition. Examples of such efforts include the works of Mayle and Gostelow et al. These newer models show promise of providing accurate transition predictions over a wide range of flow conditions, although they have yet to be implemented into the numerical flow analyses used by the turbine design community. Some recent computational investigations of interest include the works of Chernobrovkin and Lakshminarayana and Eulitz and Engel. The focus of the current effort has been to -use a viscous, unsteady quasi-three-dimensional Navier-Stokes analysis to study boundary layer development in a two-stage low-pressure turbine. A two-layer algebraic turbulence model, along with a natural transition model and a bubble transition model, have been used, The geometry used in the simulations has been the subject of extensive experiments. The predicted results have been compared with experimental data, including airfoil loadings and time

  15. Phase-resolved surface pressure and heat-transfer measurements on the blade of a two-stage turbine

    SciTech Connect

    Dunn, M.G.; Haldeman, C.W. Jr.

    1995-12-01

    Phase-resolved surface pressure, and unsteady pressure measurements are reported for the first-stage blade row of the Space Shuttle Main Engine two-stage fuel-side turbine. Measurements were made at 10, 50, and 90 percent span on both the pressure and suction surfaces of the blade. Phase-resolved and unsteady heat-flux measurements are also reported.

  16. Development of advanced heat pump. Part 2: Preliminary test of two-stage compression heat pump

    NASA Astrophysics Data System (ADS)

    Iwatsubo, Tetsushiro; Saikawa, Michinori; Hamamatsu, Teruhide

    1988-03-01

    A heat pump driven by electricity is one of the excellent electricity utilization systems and is promoted to be widely used. An advanced heat pump has been investigated to enlarge its applications in the field of hot water supply for domestic use which will be competitive with city gas and air conditioning in large scale buildings. An experimental unit with two-stage compression system was designed, which has the multi-function of air conditioning and hot water supply, and the trial system was fabricated. In the design, followings were considered; cooperative operations of two compressors by inverter driving, the temperature conditions of both the air for the air conditioning and the heat source, additional setting of the intermediate heat exchanger. The test operation was carried out with checking the start up procedure, the control sequence and so on. The probability of five operation modes: cooling, heating, hot water supply, cooling/hot water supply, and heating/hot water supply, were confirmed. In the mode of heating/hot water supply the hot water temperature was increased to 65 C, the excellent performance in hot water supply was demonstrated.

  17. Experimental Results of the First Two Stages of an Advanced Transonic Core Compressor Under Isolated and Multi-Stage Conditions

    NASA Technical Reports Server (NTRS)

    Prahst, Patricia S.; Kulkarni, Sameer; Sohn, Ki H.

    2015-01-01

    NASA's Environmentally Responsible Aviation (ERA) Program calls for investigation of the technology barriers associated with improved fuel efficiency of large gas turbine engines. Under ERA the task for a High Pressure Ratio Core Technology program calls for a higher overall pressure ratio of 60 to 70. This mean that the HPC would have to almost double in pressure ratio and keep its high level of efficiency. The challenge is how to match the corrected mass flow rate of the front two supersonic high reaction and high corrected tip speed stages with a total pressure ratio of 3.5. NASA and GE teamed to address this challenge by using the initial geometry of an advanced GE compressor design to meet the requirements of the first 2 stages of the very high pressure ratio core compressor. The rig was configured to run as a 2 stage machine, with Strut and IGV, Rotor 1 and Stator 1 run as independent tests which were then followed by adding the second stage. The goal is to fully understand the stage performances under isolated and multi-stage conditions and fully understand any differences and provide a detailed aerodynamic data set for CFD validation. Full use was made of steady and unsteady measurement methods to isolate fluid dynamics loss source mechanisms due to interaction and endwalls. The paper will present the description of the compressor test article, its predicted performance and operability, and the experimental results for both the single stage and two stage configurations. We focus the detailed measurements on 97 and 100 of design speed at 3 vane setting angles.

  18. Influence of different substrates on the performance of a two-stage high pressure anaerobic digestion system.

    PubMed

    Lemmer, A; Chen, Y; Lindner, J; Wonneberger, A M; Zielonka, S; Oechsner, H; Jungbluth, T

    2015-02-01

    The two-stage autogenerative high-pressure digestion technique is a novel and promising approach for the production of gaseous fuels or upgraded biogas. This new technique is described in the patent DE 10 2011 015415 A1 and integrates biogas production, its upgrading and pressure boosting in one process. Anaerobic digestion under elevated pressure conditions leads to decreasing pH-values in the digestate due to the augmented formation of carboxylic acid. Model calculations carried out to evaluate the two-stage design showed that the pH-value in the pressurized anaerobic filter has a major influence on the methane content of the biogas produced. Within this study, the influence of the nitrogen content as one of the most important buffering substances on the performance of the system has been tested. The results show that higher NH4 contents lead to higher pH-values in the digester and as a consequence to higher methane contents.

  19. Advancing Early Detection of Autism Spectrum Disorder by Applying an Integrated Two-Stage Screening Approach

    ERIC Educational Resources Information Center

    Oosterling, Iris J.; Wensing, Michel; Swinkels, Sophie H.; van der Gaag, Rutger Jan; Visser, Janne C.; Woudenberg, Tim; Minderaa, Ruud; Steenhuis, Mark-Peter; Buitelaar, Jan K.

    2010-01-01

    Background: Few field trials exist on the impact of implementing guidelines for the early detection of autism spectrum disorders (ASD). The aims of the present study were to develop and evaluate a clinically relevant integrated early detection programme based on the two-stage screening approach of Filipek et al. (1999), and to expand the evidence…

  20. Time-averaged heat transfer and pressure measurements and comparison with prediction for a two-stage turbine

    NASA Astrophysics Data System (ADS)

    Dunn, M. G.; Kim, J.; Civinskas, K. C.; Boyle, R. J.

    1992-06-01

    Time-averaged Stanton number and surface-pressure distributions are reported for the first-stage vane row and the first-stage blade row of the Rocketdyne Space Shuttle Main Engine two-stage fuel-side turbine. These measurements were made at 10 percent, 50 percent, and 90 percent span on both the pressure and suction surfaces of the component. Stanton-number distributions are also reported for the second-stage vane at 50 percent span. A shock tube is used as a short-duration source of heated and pressurized air to which the turbine is subjected. Platinum thin-film gages are used to obtain the heat-flux measurements and miniature silicone-diaphragm pressure transducers are used to obtain the surface pressure measurements. The first-stage vane Stanton number distributions are compared with predictions obtained using a quasi-3D Navier-Stokes solution and a version of STAN5. This same N-S technique was also used to obtain predictions for the first blade and the second vane.

  1. Optimization of two-stage production/inventory systems under order base stock policy with advance demand information

    NASA Astrophysics Data System (ADS)

    Nakade, Koichi; Yokozawa, Shiori

    2016-08-01

    It is important to share demand information among the members in supply chains. In recent years, production and inventory systems with advance demand information (ADI) have been discussed, where advance demand information means the information of demand which the decision maker obtains before the corresponding actual demand arrives. Appropriate production and inventory control using demand information leads to the decrease of inventory and backlog costs. For a single stage system, the optimal base stock and release lead time have been discussed in the literature. In practical production systems the manufacturing system has multiple processes. The multiple stage production and inventory system with ADI, however, has been analyzed by simulation or assuming exponential processing time. That is, their theoretical analysis and optimization of release lead time and base stock level have little been obtained because of its difficulty. In this paper, theoretical analysis of a two-stage production inventory system with advance demand information is developed, where the processing time is assumed deterministic and identical; demand arrival process is Poisson, and an order base stock policy is adopted. Using the analytical results, optimal release lead time and optimal base stock levels for minimizing the average cost on the holding and backlog costs are explicitly derived.

  2. Results of Two-Stage Light-Gas Gun Development Efforts and Hypervelocity Impact Tests of Advanced Thermal Protection Materials

    NASA Technical Reports Server (NTRS)

    Cornelison, C. J.; Watts, Eric T.

    1998-01-01

    Gun development efforts to increase the launching capabilities of the NASA Ames 0.5-inch two-stage light-gas gun have been investigated. A gun performance simulation code was used to guide initial parametric variations and hardware modifications, in order to increase the projectile impact velocity capability to 8 km/s, while maintaining acceptable levels of gun barrel erosion and gun component stresses. Concurrent with this facility development effort, a hypervelocity impact testing series in support of the X-33/RLV program was performed in collaboration with Rockwell International. Specifically, advanced thermal protection system materials were impacted with aluminum spheres to simulate impacts with on-orbit space debris. Materials tested included AETB-8, AETB-12, AETB-20, and SIRCA-25 tiles, tailorable advanced blanket insulation (TABI), and high temperature AFRSI (HTA). The ballistic limit for several Thermal Protection System (TPS) configurations was investigated to determine particle sizes which cause threshold TPS/structure penetration. Crater depth in tiles was measured as a function of impact particle size. The relationship between coating type and crater morphology was also explored. Data obtained during this test series was used to perform a preliminary analysis of the risks to a typical orbital vehicle from the meteoroid and space debris environment.

  3. Advances of two-stage riser catalytic cracking of heavy oil for maximizing propylene yield (TMP) process.

    PubMed

    Chaohe, Yang; Xiaobo, Chen; Jinhong, Zhang; Chunyi, Li; Honghong, Shan

    Two-stage riser catalytic cracking of heavy oil for maximizing propylene yield (TMP) process proposed by State Key Laboratory of Heavy oil Processing, China University of Petroleum, can remarkably enhance the propylene yield and minimize the dry gas and coke yields, and obtain high-quality light oils (gasoline and diesel). It has been commercialized since 2006. Up to now, three TMP commercial units have been put into production and other four commercial units are under design and construction. The commercial data showed that taking paraffinic based Daqing (China) atmospheric residue as the feedstock, the propylene yield reached 20.31 wt%, the liquid products yield (the total yield of liquefied petroleum gas, gasoline, and diesel) was 82.66 wt%, and the total yield of dry gas and coke was 14.28 wt%. Moreover, the research octane number of gasoline could be up to 96.

  4. Design and performance of a 427-meter-per-second-tip-speed two-stage fan having a 2.40 pressure ratio

    NASA Technical Reports Server (NTRS)

    Cunnan, W. S.; Stevans, W.; Urasek, D. C.

    1978-01-01

    The aerodynamic design and the overall and blade-element performances are presented of a 427-meter-per-second-tip-speed two-stage fan designed with axially spaced blade rows to reduce noise transmitted upstream of the fan. At design speed the highest recorded adiabatic efficiency was 0.796 at a pressure of 2.30. Peak efficiency was not established at design speed because of a damper failure which terminated testing prematurely. The overall efficiencies, at 60 and 80 percent of design speed, peaked at approximately 0.83.

  5. A two stage launch vehicle for use as an advanced space transportation system for logistics support of the space station

    NASA Technical Reports Server (NTRS)

    1987-01-01

    This report describes the preliminary design specifications for an Advanced Space Transportation System consisting of a fully reusable flyback booster, an intermediate-orbit cargo vehicle, and a shuttle-type orbiter with an enlarged cargo bay. It provides a comprehensive overview of mission profile, aerodynamics, structural design, and cost analyses. These areas are related to the overall feasibility and usefullness of the proposed system.

  6. Combined processes of two-stage Fenton-biological anaerobic filter-biological aerated filter for advanced treatment of landfill leachate.

    PubMed

    Wang, Xiaojun; Han, Jijun; Chen, Zhiwei; Jian, Lei; Gu, Xiaoyang; Lin, Che-Jen

    2012-12-01

    There are numerous non-biodegradable organic materials in the mature landfill leachate. To meet the new discharge standard of China, additional advanced treatment is needed for the effluent from the biological treatment processes of leachate. In this study, a combined process including two stages of "Fenton-biological anaerobic filter (BANF)-biological aerated filter (BAF)" was evaluated to address the advanced treatment need. The Fenton oxidation was applied to reduce chemical oxygen demand (COD) and enhance biodegradability of refractory organics, and the BANF-BAF process was then applied to remove the total nitrogen (TN). The treatment achieved effluent concentrations of COD<70 mg/L, TN<40 mg/L and NH(3)-N<10 mg/L. The removal efficiency of COD and TN were 96.1% and 95.9%, respectively. The effluent quality met the new discharge standard for Pollution Control on the Landfill Site of Municipal Solid of PR China (GB16889-2008). The operation cost of these processes was about 36.1CHY/t (5.70USD/t).

  7. Two stage liquefaction of coal

    DOEpatents

    Neuworth, Martin B.

    1981-01-01

    A two stage coal liquefaction process and apparatus comprising hydrogen donor solvent extracting, solvent deashing, and catalytic hydrocracking. Preferrably, the catalytic hydrocracking is performed in an ebullating bed hydrocracker.

  8. Two stage turbine for rockets

    NASA Technical Reports Server (NTRS)

    Veres, Joseph P.

    1993-01-01

    The aerodynamic design and rig test evaluation of a small counter-rotating turbine system is described. The advanced turbine airfoils were designed and tested by Pratt & Whitney. The technology represented by this turbine is being developed for a turbopump to be used in an advanced upper stage rocket engine. The advanced engine will use a hydrogen expander cycle and achieve high performance through efficient combustion of hydrogen/oxygen propellants, high combustion pressure, and high area ratio exhaust nozzle expansion. Engine performance goals require that the turbopump drive turbines achieve high efficiency at low gas flow rates. The low mass flow rates and high operating pressures result in very small airfoil heights and diameters. The high efficiency and small size requirements present a challenging turbine design problem. The shrouded axial turbine blades are 50 percent reaction with a maximum thickness to chord ratio near 1. At 6 deg from the tangential direction, the nozzle and blade exit flow angles are well below the traditional design minimum limits. The blade turning angle of 160 deg also exceeds the maximum limits used in traditional turbine designs.

  9. Advanced research for the characterization of hydrogen donor solvents in two-stage liquefaction. Quarterly report, April 1, 1984-June 30, 1984

    SciTech Connect

    Hamshar, J. A.; Potts, J. D.

    1984-01-01

    Solvent-only reactions at SCT conditions in hydrogen were explored for each of the four blended solvents, ranging from 6.1 to 8.6 wt. % hydrogen content (nominally 6.1, 7.7, 7.4, 8.6). Generally, no loss of solvent to gas was measured, but small amounts of retrograde reactions (oil to preasphaltenes, asphaltenes, insolubles) were observed at both low and high severity. Insolubles were produced in solvent A (6.1% H) and consumed in solvent D (8.6% H). Ten hydrotreating and hydrocracking catalysts have been selected and obtained from a variety of catalyst manufacturers. A matrix of eleven runs was made using the base catalyst and solvent B (7.7% H) to determine ranges of operating conditions appropriate for further catalyst testing. A series of 72 run conditions were completed at SCT conditions for coal extraction in the microautoclave, studying the effects of temperature, residence time, pressure, solvent makeup, and atmosphere. At hydrogen-deficient conditions, coal conversions were observed to decline at the highest reaction severities (i.e. 850 to 900/sup 0/F), apparently due to condensation (coking) reactions. Preasphaltene and asphaltene yields are maximized at intermediate severities, and oil yields increase with severity over the range of conditions tested. Coal conversions in a nitrogen atmosphere were generally slightly less than in hydrogen, for all solvents, and at both mild and severe conditions. Coal conversions maximize at a solvent hydrogen content of approximately 7.5%. At this level of hydrogen content, solvent B (7.7% H), made by mild hydrogenation of KC-oil, out-performs solvent C (7.4% H), made by blending hydrogen-rich and hydrogen-deficient components. The performance of solvent C was, however, significantly better than that of either component by itself. 21 figures, 18 tables.

  10. Two stage coal gasification plant

    SciTech Connect

    Shoebotham, N.M.

    1984-06-26

    This invention relates to a two stage coal gasification plant which comprises a gasifier 1 and a predistillation retort 2. The gasifier has a plurality of gas extraction outlets 4 located in the periphery thereof which feed into a manifold 5 from where a percentage of the gas from the gasifier is extracted. Gas from the predistillation retort is extracted through an outlet near the top of the retort. An agitator 8 is provided for agitation of the coal in the agglomeration zone. The agitator is preferably automatically controlled by means of a temperature sensing device 10 located on an arm thereof.

  11. Pressure Safety: Advanced Live 11459

    SciTech Connect

    Glass, George

    2016-03-02

    Many Los Alamos National Laboratory (LANL) operations use pressure equipment and systems. Failure to follow proper procedures when designing or operating pressure systems can result in injuries to personnel and damage to equipment and/or the environment. This manual presents an overview of the requirements and recommendations that address the safe design and operation of pressure systems at LANL.

  12. Two stage indirect evaporative cooling system

    SciTech Connect

    Bourne, Richard C.; Lee, Brian E.; Callaway, Duncan

    2005-08-23

    A two stage indirect evaporative cooler that moves air from a blower mounted above the unit, vertically downward into dry air passages in an indirect stage and turns the air flow horizontally before leaving the indirect stage. After leaving the dry passages, a major air portion travels into the direct stage and the remainder of the air is induced by a pressure drop in the direct stage to turn 180.degree. and returns horizontally through wet passages in the indirect stage and out of the unit as exhaust air.

  13. Two stage to orbit design

    NASA Technical Reports Server (NTRS)

    1991-01-01

    A preliminary design of a two-stage to orbit vehicle was conducted with the requirements to carry a 10,000 pound payload into a 300 mile low-earth orbit using an airbreathing first stage, and to take off and land unassisted on a 15,000 foot runway. The goal of the design analysis was to produce the most efficient vehicle in size and weight which could accomplish the mission requirements. Initial parametric analysis indicated that the weight of the orbiter and the transonic performance of the system were the two parameters that had the largest impact on the design. The resulting system uses a turbofan ramjet powered first stage to propel a scramjet and rocket powered orbiter to the stage point of Mach 6 to 6.5 at an altitude of 90,000 ft.

  14. Two-Stage Centrifugal Fan

    NASA Technical Reports Server (NTRS)

    Converse, David

    2011-01-01

    Fan designs are often constrained by envelope, rotational speed, weight, and power. Aerodynamic performance and motor electrical performance are heavily influenced by rotational speed. The fan used in this work is at a practical limit for rotational speed due to motor performance characteristics, and there is no more space available in the packaging for a larger fan. The pressure rise requirements keep growing. The way to ordinarily accommodate a higher DP is to spin faster or grow the fan rotor diameter. The invention is to put two radially oriented stages on a single disk. Flow enters the first stage from the center; energy is imparted to the flow in the first stage blades, the flow is redirected some amount opposite to the direction of rotation in the fixed stators, and more energy is imparted to the flow in the second- stage blades. Without increasing either rotational speed or disk diameter, it is believed that as much as 50 percent more DP can be achieved with this design than with an ordinary, single-stage centrifugal design. This invention is useful primarily for fans having relatively low flow rates with relatively high pressure rise requirements.

  15. Impact of osmotic pressure and gelling in the generation of highly stable single core water-in-oil-in-water (W/O/W) nano multiple emulsions of aspirin assisted by two-stage ultrasonic cavitational emulsification.

    PubMed

    Tang, Siah Ying; Sivakumar, Manickam; Nashiru, Billa

    2013-02-01

    The present investigation focuses in investigating the effect of osmotic pressure, gelling on the mean droplet diameter, polydispersity index, droplet size stability of the developed novel Aspirin containing water-in-oil-in-water (W/O/W) nano multiple emulsion. The aspirin-loaded nano multiple emulsion formulation was successfully generated using two-stage ultrasonic cavitational emulsification which had been reported in author's previous study. The osmotic behavior of ultrasonically prepared nano multiple emulsions were also examined with different glucose concentrations both in the inner and outer aqueous phases. In addition, introducing gelatin into the formulation also observed to play an important role in preventing the interdroplet coalescence via the formation of interfacial rigid film. Detailed studies were also made on the possible mechanisms of water migration under osmotic gradient which primarily caused by the permeation of glucose. Besides, the experimental results have shown that the interfacial tension between the two immiscible phases decreases with varying the composition of organic phase. Although the W/O/W emulsion prepared with the inner/outer glucose weight ratio of 1-0.5% (w/w) showed an excellent droplet stability, the formulation containing 0.5% (w/w) glucose in the inner aqueous phase appeared to be the most stable with minimum change in the mean droplet size upon one-week storage period. Based on the optimization, nano multiple emulsion droplets with the mean droplet diameter of around 400 nm were produced using 1.25% (w/w) Span 80 and 0.5% Cremophore EL. Overall, our investigation makes a pathway in proving that the use of ultrasound cavitation is an efficient yet promising approach in the generation of stable and uniform nano multiple emulsions and could be used in the encapsulation of various active pharmaceutical ingredients in the near future.

  16. Pressure Safety: Advanced Self-Study 30120

    SciTech Connect

    Glass, George

    2016-02-29

    Pressure Safety Advance Self-Study (Course 30120) consists of an introduction, five modules, and a quiz. To receive credit in UTrain for completing this course, you must score 80% or better on the 15-question quiz (check UTrain). Directions for initiating the quiz are appended to the end of this training manual. This course contains several links to LANL websites. UTrain might not support active links, so please copy links into the address line in your browser.

  17. Advanced Extravehicular Activity Pressure Garment Requirements Development

    NASA Technical Reports Server (NTRS)

    Ross, Amy

    2014-01-01

    The NASA Johnson Space Center advanced pressure garment technology development team is addressing requirements development for exploration missions. Lessons learned from the Z-2 high fidelity prototype development have reiterated that clear low-level requirements and verification methods reduce risk to the government, improve efficiency in pressure garment design efforts, and enable the government to be a smart buyer. The expectation is to provide requirements at the specification level that are validated so that their impact on pressure garment design is understood. Additionally, the team will provide defined verification protocols for the requirements. However, in reviewing exploration space suit high level requirements there are several gaps in the team's ability to define and verify related lower level requirements. This paper addresses the efforts in requirement areas such as mobility/fit/comfort and environmental protection (dust, radiation, plasma, secondary impacts) to determine the by what method the requirements can be defined and use of those methods for verification. Gaps exist at various stages. In some cases component level work is underway, but no system level effort has begun, in other cases no effort has been initiated to close the gap. Status of ongoing efforts and potential approaches to open gaps are discussed.

  18. Two-stage coal liquefaction process

    DOEpatents

    Skinner, Ronald W.; Tao, John C.; Znaimer, Samuel

    1985-01-01

    An improved SRC-I two-stage coal liquefaction process which improves the product slate is provided. Substantially all of the net yield of 650.degree.-850.degree. F. heavy distillate from the LC-Finer is combined with the SRC process solvent, substantially all of the net 400.degree.-650.degree. F. middle distillate from the SRC section is combined with the hydrocracker solvent in the LC-Finer, and the initial boiling point of the SRC process solvent is increased sufficiently high to produce a net yield of 650.degree.-850.degree. F. heavy distillate of zero for the two-stage liquefaction process.

  19. Two stage sorption of sulfur compounds

    DOEpatents

    Moore, William E.

    1992-01-01

    A two stage method for reducing the sulfur content of exhaust gases is disclosed. Alkali- or alkaline-earth-based sorbent is totally or partially vaporized and introduced into a sulfur-containing gas stream. The activated sorbent can be introduced in the reaction zone or the exhaust gases of a combustor or a gasifier. High efficiencies of sulfur removal can be achieved.

  20. Two-Stage Series-Resonant Inverter

    NASA Technical Reports Server (NTRS)

    Stuart, Thomas A.

    1994-01-01

    Two-stage inverter includes variable-frequency, voltage-regulating first stage and fixed-frequency second stage. Lightweight circuit provides regulated power and is invulnerable to output short circuits. Does not require large capacitor across ac bus, like parallel resonant designs. Particularly suitable for use in ac-power-distribution system of aircraft.

  1. Two stage surgical procedure for root coverage.

    PubMed

    George, Anjana Mary; Rajesh, K S; Hegde, Shashikanth; Kumar, Arun

    2012-07-01

    Gingival recession may present problems that include root sensitivity, esthetic concern, and predilection to root caries, cervical abrasion and compromising of a restorative effort. When marginal tissue health cannot be maintained and recession is deep, the need for treatment arises. This literature has documented that recession can be successfully treated by means of a two stage surgical approach, the first stage consisting of creation of attached gingiva by means of free gingival graft, and in the second stage, a lateral sliding flap of grafted tissue to cover the recession. This indirect technique ensures development of an adequate width of attached gingiva. The outcome of this technique suggests that two stage surgical procedures are highly predictable for root coverage in case of isolated deep recession and lack of attached gingiva.

  2. Two-Stage Free Electron Laser Research.

    DTIC Science & Technology

    1984-10-24

    Ctmetenar an reverse ode It ne*eey aud identify fo black nmber) Free electron laser, two-stage free electron laser, quasioptical cavity, helical ...of very high intensity (_10 W/cm ). A quasioptical cavity concept has been developed to produce such a field. A helical wiggler is needed to excite...the TE waveguide mode in this cavity. Work is described on the development of a pfmanent magnet helical wiggler for this system. Off-axis electron

  3. Two Stage Gear Tooth Dynamics Program

    DTIC Science & Technology

    1989-08-01

    cordi - tions and associated iteration prooedure become more complex. This is due to both the increased number of components and to the time for a...solved for each stage in the two stage solution . There are (3 + ntrrber of planets) degrees of freedom fcr eacb stage plus two degrees of freedom...should be devised. It should be noted that this is not minor task. In general, each stage plus an input or output shaft will have 2 times (4 + number

  4. Stepwise two-stage sample size adaptation.

    PubMed

    Wan, Hong; Ellenberg, Susan S; Anderson, Keaven M

    2015-01-15

    Several adaptive design methods have been proposed to reestimate sample size using the observed treatment effect after an initial stage of a clinical trial while preserving the overall type I error at the time of the final analysis. One unfortunate property of the algorithms used in some methods is that they can be inverted to reveal the exact treatment effect at the interim analysis. We propose using a step function with an inverted U-shape of observed treatment difference for sample size reestimation to lessen the information on treatment effect revealed. This will be referred to as stepwise two-stage sample size adaptation. This method applies calculation methods used for group sequential designs. We minimize expected sample size among a class of these designs and compare efficiency with the fully optimized two-stage design, optimal two-stage group sequential design, and designs based on promising conditional power. The trade-off between efficiency versus the improved blinding of the interim treatment effect will be discussed.

  5. Two-stage microbial community experimental design.

    PubMed

    Tickle, Timothy L; Segata, Nicola; Waldron, Levi; Weingart, Uri; Huttenhower, Curtis

    2013-12-01

    Microbial community samples can be efficiently surveyed in high throughput by sequencing markers such as the 16S ribosomal RNA gene. Often, a collection of samples is then selected for subsequent metagenomic, metabolomic or other follow-up. Two-stage study design has long been used in ecology but has not yet been studied in-depth for high-throughput microbial community investigations. To avoid ad hoc sample selection, we developed and validated several purposive sample selection methods for two-stage studies (that is, biological criteria) targeting differing types of microbial communities. These methods select follow-up samples from large community surveys, with criteria including samples typical of the initially surveyed population, targeting specific microbial clades or rare species, maximizing diversity, representing extreme or deviant communities, or identifying communities distinct or discriminating among environment or host phenotypes. The accuracies of each sampling technique and their influences on the characteristics of the resulting selected microbial community were evaluated using both simulated and experimental data. Specifically, all criteria were able to identify samples whose properties were accurately retained in 318 paired 16S amplicon and whole-community metagenomic (follow-up) samples from the Human Microbiome Project. Some selection criteria resulted in follow-up samples that were strongly non-representative of the original survey population; diversity maximization particularly undersampled community configurations. Only selection of intentionally representative samples minimized differences in the selected sample set from the original microbial survey. An implementation is provided as the microPITA (Microbiomes: Picking Interesting Taxa for Analysis) software for two-stage study design of microbial communities.

  6. Two-Stage Reduction Of Dynamical Models

    NASA Technical Reports Server (NTRS)

    Lee, Allan Y.; Tsuha, Walter S.

    1993-01-01

    No longer necessary to solve eigenvalue problems of high order. Component-mode projection-and-assembly model-reduction (COMPARE) method provides approximation of dynamics of vibrations of complicated, multiple flexible bodies by use of mathematical models of reduced order. Incorporates component-mode synthesis (CMS) method and enhanced projection-and-assembly (EP&A) method, described in "Enhanced Method of Reduction of Dynamical Models" (NPO-18402), providing for somewhat simplified two-stage process in which order of applicable mathematical models reduced. Reduced-order models used to design algorithms of control systems to suppress vibrations or otherwise control structure.

  7. Two-Stage Passive Vibration Isolator

    NASA Technical Reports Server (NTRS)

    Goullioud, Renaud; Gursel, Yekta; Neville, Timothy; Bronowicki, Allen J.; Platus, David; MacDonald, Rhonda

    2008-01-01

    The design and testing of a structural system were implemented to hold the optics of the planned Space Interferometry Mission (SIM) at positions and orientations characterized by vibrational translation and rotation errors of no more than a few nanometers or a few milliarcseconds, respectively. Much of the effort was devoted to a test bed for verifying the predicted behavior of a vibration- isolation structural subsystem working together with an active control system for positioning and orienting the SIM optics. There was considerable emphasis on the vibration-isolation subsystem, which was passive and comprised two stages. The main sources of vibration were six reaction wheels in an assembly denoted the "backpack." The first vibration-isolation stage consisted of hexapod isolator mounts - one for each reaction wheel - characterized by a natural vibration frequency of 10 Hz. The second stage was a set of three beams, disposed between the backpack and the structure that held the SIM optics, that were flexured such that they transmitted only bending loads, with a natural vibrational frequency and damping of about 5 Hz and 4 percent, respectively. Preliminary test results were presented and characterized as demonstrating the effectiveness of the two-stage vibration-isolation design.

  8. Conceptual design of a two stage to orbit spacecraft

    NASA Technical Reports Server (NTRS)

    Armiger, Scott C.; Kwarta, Jennifer S.; Horsley, Kevin B.; Snow, Glenn A.; Koe, Eric C.; Single, Thomas G.

    1993-01-01

    This project, undertaken through the Advanced Space Design Program, developed a 'Conceptual Design of a Two Stage To Orbit Spacecraft (TSTO).' The design developed utilizes a combination of air breathing and rocket propulsion systems and is fully reusable, with horizontal takeoff and landing capability. The orbiter is carried in an aerodynamically designed bay in the aft section of the booster vehicle to the staging altitude. This TSTO Spacecraft design meets the requirements of replacing the aging Space Shuttle system with a more easily maintained vehicle with more flexible mission capability.

  9. Two-Stage Fan I: Aerodynamic and Mechanical Design

    NASA Technical Reports Server (NTRS)

    Messenger, H. E.; Kennedy, E. E.

    1972-01-01

    A two-stage, highly-loaded fan was designed to deliver an overall pressure ratio of 2.8 with an adiabatic efficiency of 83.9 percent. At the first rotor inlet, design flow per unit annulus area is 42 lbm/sec/sq ft (205 kg/sec/sq m), hub/tip ratio is 0.4 with a tip diameter of 31 inches (0.787 m), and design tip speed is 1450 ft/sec (441.96 m/sec). Other features include use of multiple-circular-arc airfoils, resettable stators, and split casings over the rotor tip sections for casing treatment tests.

  10. Two stage gear tooth dynamics program

    NASA Technical Reports Server (NTRS)

    Boyd, Linda S.

    1989-01-01

    The epicyclic gear dynamics program was expanded to add the option of evaluating the tooth pair dynamics for two epicyclic gear stages with peripheral components. This was a practical extension to the program as multiple gear stages are often used for speed reduction, space, weight, and/or auxiliary units. The option was developed for either stage to be a basic planetary, star, single external-external mesh, or single external-internal mesh. The two stage system allows for modeling of the peripherals with an input mass and shaft, an output mass and shaft, and a connecting shaft. Execution of the initial test case indicated an instability in the solution with the tooth paid loads growing to excessive magnitudes. A procedure to trace the instability is recommended as well as a method of reducing the program's computation time by reducing the number of boundary condition iterations.

  11. Two-stage eutectic metal brushes

    DOEpatents

    Hsu, John S [Oak Ridge, TN

    2009-07-14

    A two-stage eutectic metal brush assembly having a slip ring rigidly coupled to a shaft, the slip ring being electrically coupled to first voltage polarity. At least one brush is rigidly coupled to a second ring and slidingly engaged to the slip ring. Eutectic metal at least partially fills an annulus between the second ring and a stationary ring. At least one conductor is rigidly coupled to the stationary ring and electrically coupled to a second voltage polarity. Electrical continuity is maintained between the first voltage polarity and the second voltage polarity. Periodic rotational motion is present between the stationary ring and the second ring. Periodic rotational motion is also present between the brush and the slip ring.

  12. Modeling of a Sequential Two-Stage Combustor

    NASA Technical Reports Server (NTRS)

    Hendricks, R. C.; Liu, N.-S.; Gallagher, J. R.; Ryder, R. C.; Brankovic, A.; Hendricks, J. A.

    2005-01-01

    A sequential two-stage, natural gas fueled power generation combustion system is modeled to examine the fundamental aerodynamic and combustion characteristics of the system. The modeling methodology includes CAD-based geometry definition, and combustion computational fluid dynamics analysis. Graphical analysis is used to examine the complex vortical patterns in each component, identifying sources of pressure loss. The simulations demonstrate the importance of including the rotating high-pressure turbine blades in the computation, as this results in direct computation of combustion within the first turbine stage, and accurate simulation of the flow in the second combustion stage. The direct computation of hot-streaks through the rotating high-pressure turbine stage leads to improved understanding of the aerodynamic relationships between the primary and secondary combustors and the turbomachinery.

  13. Two-Stage Modelling Of Random Phenomena

    NASA Astrophysics Data System (ADS)

    Barańska, Anna

    2015-12-01

    The main objective of this publication was to present a two-stage algorithm of modelling random phenomena, based on multidimensional function modelling, on the example of modelling the real estate market for the purpose of real estate valuation and estimation of model parameters of foundations vertical displacements. The first stage of the presented algorithm includes a selection of a suitable form of the function model. In the classical algorithms, based on function modelling, prediction of the dependent variable is its value obtained directly from the model. The better the model reflects a relationship between the independent variables and their effect on the dependent variable, the more reliable is the model value. In this paper, an algorithm has been proposed which comprises adjustment of the value obtained from the model with a random correction determined from the residuals of the model for these cases which, in a separate analysis, were considered to be the most similar to the object for which we want to model the dependent variable. The effect of applying the developed quantitative procedures for calculating the corrections and qualitative methods to assess the similarity on the final outcome of the prediction and its accuracy, was examined by statistical methods, mainly using appropriate parametric tests of significance. The idea of the presented algorithm has been designed so as to approximate the value of the dependent variable of the studied phenomenon to its value in reality and, at the same time, to have it "smoothed out" by a well fitted modelling function.

  14. Advanced Diagnostics for High Pressure Spray Combustion.

    SciTech Connect

    Skeen, Scott A.; Manin, Julien Luc; Pickett, Lyle M.

    2014-06-01

    The development of accurate predictive engine simulations requires experimental data to both inform and validate the models, but very limited information is presently available about the chemical structure of high pressure spray flames under engine- relevant conditions. Probing such flames for chemical information using non- intrusive optical methods or intrusive sampling techniques, however, is challenging because of the physical and optical harshness of the environment. This work details two new diagnostics that have been developed and deployed to obtain quantitative species concentrations and soot volume fractions from a high-pressure combusting spray. A high-speed, high-pressure sampling system was developed to extract gaseous species (including soot precursor species) from within the flame for offline analysis by time-of-flight mass spectrometry. A high-speed multi-wavelength optical extinction diagnostic was also developed to quantify transient and quasi-steady soot processes. High-pressure sampling and offline characterization of gas-phase species formed following the pre-burn event was accomplished as well as characterization of gas-phase species present in the lift-off region of a high-pressure n-dodecane spray flame. For the initial samples discussed in this work several species were identified, including polycyclic aromatic hydrocarbons (PAH); however, quantitative mole fractions were not determined. Nevertheless, the diagnostic developed here does have this capability. Quantitative, time-resolved measurements of soot extinction were also accomplished and the novel use of multiple incident wavelengths proved valuable toward characterizing changes in soot optical properties within different regions of the spray flame.

  15. Gas loading system for LANL two-stage gas guns

    NASA Astrophysics Data System (ADS)

    Gibson, Lee; Bartram, Brian; Dattelbaum, Dana; Lang, John; Morris, John

    2015-06-01

    A novel gas loading system was designed for the specific application of remotely loading high purity gases into targets for gas-gun driven plate impact experiments. The high purity gases are loaded into well-defined target configurations to obtain Hugoniot states in the gas phase at greater than ambient pressures. The small volume of the gas samples is challenging, as slight changing in the ambient temperature result in measurable pressure changes. Therefore, the ability to load a gas gun target and continually monitor the sample pressure prior to firing provides the most stable and reliable target fielding approach. We present the design and evaluation of a gas loading system built for the LANL 50 mm bore two-stage light gas gun. Targets for the gun are made of 6061 Al or OFHC Cu, and assembled to form a gas containment cell with a volume of approximately 1.38 cc. The compatibility of materials was a major consideration in the design of the system, particularly for its use with corrosive gases. Piping and valves are stainless steel with wetted seals made from Kalrez and Teflon. Preliminary testing was completed to ensure proper flow rate and that the proper safety controls were in place. The system has been used to successfully load Ar, Kr, Xe, and anhydrous ammonia with purities of up to 99.999 percent. The design of the system, and example data from the plate impact experiments will be shown. LA-UR-15-20521

  16. Residential oil burners with low input and two stages firing

    SciTech Connect

    Butcher, T.; Krajewski, R.; Leigh, R.

    1997-12-31

    The residential oil burner market is currently dominated by the pressure-atomized, retention head burner. At low firing rates pressure atomizing nozzles suffer rapid fouling of the small internal passages, leading to bad spray patterns and poor combustion performance. To overcome the low input limitations of conventional burners, a low pressure air-atomized burner has been developed watch can operate at fining rates as low as 0.25 gallons of oil per hour (10 kW). In addition, the burner can be operated in a high/low fining rate mode. Field tests with this burner have been conducted at a fixed input rate of 0.35 gph (14 kW) with a side-wall vented boiler/water storage tank combination. At the test home, instrumentation was installed to measure fuel and energy flows and record trends in system temperatures. Laboratory efficiency testing with water heaters and boilers has been completed using standard single purpose and combined appliance test procedures. The tests quantify benefits due to low firing rates and other burner features. A two stage oil burner gains a strong advantage in rated efficiency while maintaining capacity for high domestic hot water and space heating loads.

  17. Advanced High Pressure O2/H2 Technology

    NASA Technical Reports Server (NTRS)

    Morea, S. F. (Editor); Wu, S. T. (Editor)

    1985-01-01

    Activities in the development of advanced high pressure oxygen-hydrogen stage combustion rocket engines are reported. Particular emphasis is given to the Space Shuttle main engine. The areas of engine technology discussed include fracture and fatigue in engine components, manufacturing and producibility engineering, materials, bearing technology, structure dynamics, fluid dynamics, and instrumentation technology.

  18. New LANL gas driven two-stage gun

    SciTech Connect

    Martinez, A.R.; Sheffied, S.A.; Whitehead, M.C.; Olivas, H.D.; Dick, J.J. )

    1994-07-10

    A new compressed-helium driven two-stage light gas gun has been installed at LANL to study shock initiated reaction in insensitive high explosives. The gun (based on a design at Ernst Mach Institute) has a 100-mm diameter by 7.6 long pump tube and a 50-mm diameter by 7.6-m long launch tube. The gas breech, capable of pressures up to 15,000 psi, has a volume of 42.5 liters and can be used in either a wrap-around or double-diaphragm mode. This breech was designed so we could use helium rather than powder combustion gases to drive the pump piston, eliminating the safety and cleanup problems assoicated with gun powder. Large hydraulic clamps (pressurized to 10,000 psi) are used to clamp the breech to the pump tube, the pump tube to the transition section, and the transition section to the launch tube. The target chamber was designed to allow the necessary room to do multiple magnetic gauging experiments. Gun control is accomplished using a MAC computer and LabVIEW control software. [copyright]American Institute of Physics

  19. New LANL gas driven two-stage gun

    NASA Astrophysics Data System (ADS)

    Martinez, A. R.; Sheffied, S. A.; Whitehead, M. C.; Olivas, H. D.; Dick, J. J.

    1994-07-01

    A new compressed-helium driven two-stage light gas gun has been installed at LANL to study shock initiated reaction in insensitive high explosives. The gun (based on a design at Ernst Mach Institute) has a 100-mm diameter by 7.6 long pump tube and a 50-mm diameter by 7.6-m long launch tube. The gas breech, capable of pressures up to 15,000 psi, has a volume of 42.5 liters and can be used in either a wrap-around or double-diaphragm mode. This breech was designed so we could use helium rather than powder combustion gases to drive the pump piston, eliminating the safety and cleanup problems assoicated with gun powder. Large hydraulic clamps (pressurized to 10,000 psi) are used to clamp the breech to the pump tube, the pump tube to the transition section, and the transition section to the launch tube. The target chamber was designed to allow the necessary room to do multiple magnetic gauging experiments. Gun control is accomplished using a MAC computer and LabVIEW control software.

  20. New LANL gas-driven two-stage gun

    SciTech Connect

    Martinez, A.R.; Sheffield, S.A.; Whitehead, M.C.; Olivas, H.D.; Dick, J.J.

    1993-08-01

    A new compressed-helium driven two-stage light gas gun has been installed at LANL to study shock initiated reaction in insensitive high explosives. The gun (based on a design at Ernst Mach Institute) has a 100-mm diameter by 7.6 long pump tube and a 50-mm diameter by 7.6-m long launch tube. The gas breech, capable of pressures up to 15.000 psi, has a volume of 42.5 liters and can be used in either a wrap-around or double-diaphragm mode. This breech was designed so we could use helium rather than powder combustion gases to drive the pump piston, eliminating the safety and cleanup problems associated with gun powder. Large hydraulic clamps (pressurized to 10,000 psi) are used to clamp the breech to the pump tube, the pump tube to the transition section, and the transition section to the launch tube. The target chamber was designed to allow the necessary room to do multiple magnetic gauging experiments. Gun control is accomplished using a MAC computer and LabVIEW control software.

  1. Advances and synergy of high pressure sciences at synchrotron sources

    SciTech Connect

    Liu, H.; Ehm, L.; Duffy, T.; Crichton, W.; Aoki, K.

    2009-01-01

    Introductory overview to the special issue papers on high-pressure sciences and synchrotron radiation. High-pressure research in geosciences, materials science and condensed matter physics at synchrotron sources is experiencing growth and development through synergistic efforts around the world. A series of high-pressure science workshops were organized in 2008 to highlight these developments. One of these workshops, on 'Advances in high-pressure science using synchrotron X-rays', was held at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, USA, on 4 October 2008. This workshop was organized in honour of Drs Jingzhu Hu and Quanzhong Guo in celebration of their retirement after up to 18 years of dedicated service to the high-pressure community as beamline scientists at X17 of NSLS. Following this celebration of the often unheralded role of the beamline scientist, a special issue of the Journal of Synchrotron Radiation on Advances and Synergy of High-Pressure Sciences at Synchrotron Sources was proposed, and we were pleased to invite contributions from colleagues who participated in the workshop as well as others who are making similar efforts at synchrotron sources worldwide.

  2. High-Pressure Design of Advanced BN-Based Materials.

    PubMed

    Kurakevych, Oleksandr O; Solozhenko, Vladimir L

    2016-10-20

    The aim of the present review is to highlight the state of the art in high-pressure design of new advanced materials based on boron nitride. Recent experimental achievements on the governing phase transformation, nanostructuring and chemical synthesis in the systems containing boron nitride at high pressures and high temperatures are presented. All these developments allowed discovering new materials, e.g., ultrahard nanocrystalline cubic boron nitride (nano-cBN) with hardness comparable to diamond, and superhard boron subnitride B13N₂. Thermodynamic and kinetic aspects of high-pressure synthesis are described based on the data obtained by in situ and ex situ methods. Mechanical and thermal properties (hardness, thermoelastic equations of state, etc.) are discussed. New synthetic perspectives, combining both soft chemistry and extreme pressure-temperature conditions are considered.

  3. Catalytic two-stage coal hydrogenation and hydroconversion process

    DOEpatents

    MacArthur, James B.; McLean, Joseph B.; Comolli, Alfred G.

    1989-01-01

    A process for two-stage catalytic hydrogenation and liquefaction of coal to produce increased yields of low-boiling hydrocarbon liquid and gas products. In the process, the particulate coal is slurried with a process-derived liquid solvent and fed at temperature below about 650.degree. F. into a first stage catalytic reaction zone operated at conditions which promote controlled rate liquefaction of the coal, while simultaneously hydrogenating the hydrocarbon recycle oils at conditions favoring hydrogenation reactions. The first stage reactor is maintained at 650.degree.-800.degree. F. temperature, 1000-4000 psig hydrogen partial pressure, and 10-60 lb coal/hr/ft.sup.3 reactor space velocity. The partially hydrogenated material from the first stage reaction zone is passed directly to the close-coupled second stage catalytic reaction zone maintained at a temperature at least about 25.degree. F. higher than for the first stage reactor and within a range of 750.degree.-875.degree. F. temperature for further hydrogenation and thermal hydroconversion reactions. By this process, the coal feed is successively catalytically hydrogenated and hydroconverted at selected conditions, which results in significantly increased yields of desirable low-boiling hydrocarbon liquid products and minimal production of undesirable residuum and unconverted coal and hydrocarbon gases, with use of less energy to obtain the low molecular weight products, while catalyst life is substantially increased.

  4. Mandibular Advancing Positive Pressure Apnea Remediation Device (MAPPARD)

    DTIC Science & Technology

    2014-06-01

    wiki/Starling_resistor Lankford, D. A., Proctor, C. D., & Richard, R. (2005). Continuous positive airway pressure (CPAP) changes in bariatric surgery ...Mandibular Advancing Device (after Schlaflabor-Saletu, n.d.). ............ 8  Figure 4.  Uvulopalatopharyngoplasty (before and after surgery ) (from...Lastly, when behavioral and medical techniques have been exhausted the last OSA reduction technique is surgery . Within the last 25 years, the

  5. Technology and staging effects on two-stage-to-orbit systems

    NASA Technical Reports Server (NTRS)

    Wilhite, Alan W.

    1991-01-01

    Horizontal takeoff and landing two-stage systems with an airbreathing first stage and rocket second stage are evaluated for staging Mach numbers that range from 5 to 14. All systems are evaluated with advanced technologies being developed in the NASP Program and sized to the same mission requirements. With these advanced technologies, the two-stage systems are heavier than the single stage. The weights of the two-stage systems are closely related to staging. Using a rocket on the first stage to accelerate from the turboramjet limit of Mach 6 to Mach 10 signiificantly decreases dry weight as compared to the Mach 6-staged system. The optimum dry weight staging Mach number for the scramjet two-stage system is Mach 12. At a 40 percent weight growth (current technology level), the scramjet two-stage systems are half the weight and less sensitive to weight changes than the single stage, but still require substantial technology development in the areas of inlets, nozzles, ramjet propulsion, active cooling, and high-temperature structures.

  6. Effect of Silica Fume on two-stage Concrete Strength

    NASA Astrophysics Data System (ADS)

    Abdelgader, H. S.; El-Baden, A. S.

    2015-11-01

    Two-stage concrete (TSC) is an innovative concrete that does not require vibration for placing and compaction. TSC is a simple concept; it is made using the same basic constituents as traditional concrete: cement, coarse aggregate, sand and water as well as mineral and chemical admixtures. As its name suggests, it is produced through a two-stage process. Firstly washed coarse aggregate is placed into the formwork in-situ. Later a specifically designed self compacting grout is introduced into the form from the lowest point under gravity pressure to fill the voids, cementing the aggregate into a monolith. The hardened concrete is dense, homogeneous and has in general improved engineering properties and durability. This paper presents the results from a research work attempt to study the effect of silica fume (SF) and superplasticizers admixtures (SP) on compressive and tensile strength of TSC using various combinations of water to cement ratio (w/c) and cement to sand ratio (c/s). Thirty six concrete mixes with different grout constituents were tested. From each mix twenty four standard cylinder samples of size (150mm×300mm) of concrete containing crushed aggregate were produced. The tested samples were made from combinations of w/c equal to: 0.45, 0.55 and 0.85, and three c/s of values: 0.5, 1 and 1.5. Silica fume was added at a dosage of 6% of weight of cement, while superplasticizer was added at a dosage of 2% of cement weight. Results indicated that both tensile and compressive strength of TSC can be statistically derived as a function of w/c and c/s with good correlation coefficients. The basic principle of traditional concrete, which says that an increase in water/cement ratio will lead to a reduction in compressive strength, was shown to hold true for TSC specimens tested. Using a combination of both silica fume and superplasticisers caused a significant increase in strength relative to control mixes.

  7. Advanced Synchrotron Techniques at High Pressure Collaborative Access Team (HPCAT)

    NASA Astrophysics Data System (ADS)

    Shen, G.; Sinogeikin, S. V.; Chow, P.; Kono, Y.; Meng, Y.; Park, C.; Popov, D.; Rod, E.; Smith, J.; Xiao, Y.; Mao, H.

    2012-12-01

    High Pressure Collaborative Access Team (HPCAT) is dedicated to advancing cutting-edge, multidisciplinary, high-pressure science and technology using synchrotron radiation at Sector 16 of the Advanced Photon Source (APS) of Argonne National Laboratory. At HPCAT an array of novel x-ray diffraction and spectroscopic techniques has been integrated with high pressure and extreme temperature instrumentation for studies of structure and materials properties at extreme conditions.. HPCAT consists of four active independent beamlines performing a large range of various experiments at extreme conditions. 16BM-B beamline is dedicated to energy dispersive and white Laue X-ray diffraction. The majority of experiments are performed with a Paris-Edinburgh large volume press (to 7GPa and 2500K) and include amorphous and liquid structure measurement, white beam radiography, elastic sound wave velocity measurement of amorphous solid materials, with viscosity and density measurement of liquid being under development. 16BM-D is a monochromatic diffraction beamline for powder and single crystal diffraction at high pressure and high (resistive heating) / low (cryostats) temperature. The additional capabilities include high-resolution powder diffraction and x-ray absorption near edge structure (XANES) spectroscopy. The insertion device beamline of HPCAT has two undulators in canted mode (operating independently) and LN cooled Si monochromators capable of providing a large range of energies. 16IDB is a microdiffraction beamline mainly focusing on high-pressure powder and single crystal diffraction in DAC at high temperatures (double-sided laser heating and resistive heating) and low temperature (various cryostats). The modern instrumentation allows high-quality diffraction at megabar pressures from light element, fast experiments with pulsed laser heating, fast dynamic experiments with Pilatus detector, and so on. 16ID-D beamline is dedicated to x-ray scattering and spectroscopy research

  8. Residential Two-Stage Gas Furnaces - Do They Save Energy?

    SciTech Connect

    Lekov, Alex; Franco, Victor; Lutz, James

    2006-05-12

    Residential two-stage gas furnaces account for almost a quarter of the total number of models listed in the March 2005 GAMA directory of equipment certified for sale in the United States. Two-stage furnaces are expanding their presence in the market mostly because they meet consumer expectations for improved comfort. Currently, the U.S. Department of Energy (DOE) test procedure serves as the method for reporting furnace total fuel and electricity consumption under laboratory conditions. In 2006, American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE) proposed an update to its test procedure which corrects some of the discrepancies found in the DOE test procedure and provides an improved methodology for calculating the energy consumption of two-stage furnaces. The objectives of this paper are to explore the differences in the methods for calculating two-stage residential gas furnace energy consumption in the DOE test procedure and in the 2006 ASHRAE test procedure and to compare test results to research results from field tests. Overall, the DOE test procedure shows a reduction in the total site energy consumption of about 3 percent for two-stage compared to single-stage furnaces at the same efficiency level. In contrast, the 2006 ASHRAE test procedure shows almost no difference in the total site energy consumption. The 2006 ASHRAE test procedure appears to provide a better methodology for calculating the energy consumption of two-stage furnaces. The results indicate that, although two-stage technology by itself does not save site energy, the combination of two-stage furnaces with BPM motors provides electricity savings, which are confirmed by field studies.

  9. Using Advanced Tensiometers to Monitor Temporal Variations in Pore Pressure

    NASA Astrophysics Data System (ADS)

    Nichols, R. L.; Young, M. H.; Dixon, K. L.; Rossabi, J.; Hyde, W. K.; Holmes-Burns, H.

    2002-12-01

    The Savannah River Site has installed a comprehensive vadose zone monitoring system (VZMS) at it's low level radioactive waste disposal facility to collect the necessary information to calculate contaminant flux. The VZMS includes water content reflectometers, suction lysimeters, advanced tensiometers (ATs), water flux meters, access ports for neutron probes, and a tipping bucket rain gauge. Forty one ATs were installed from 1999 to 2001 at depths ranging from 2 to 60 feet and have been operated continuously. The installation depths were based on a hydrostatigraphic model developed from core logs, cone penetrometer logs, moisture content profiles, water retention curves model that were obtained during the phased installation of the VZMS. An AT consists of a porous cup installed at a prescribed depth with casing back to the surface and a pressure transducer that is lowered into the casing and connects with the porous cup. The pressure transducer transmits it's signal to a datalogger where the data is stored for future retrieval using a cellular phone communications package. Results from the 2 year operating period show that the AT calibrations are stable and t ATs are capable of extended monitoring of pore pressures in the 0 to 300 cm H2 O range. The ATs had sufficient resolution to detect the naturally occurring fluctuations in pore pressure (1 to 100 cm H2 O over 1 to 72 hours) that resulted from infiltration events at the site. The stable performance of the ATs combined with their ability to detect naturally occurring fluctuations in pore pressure make the ATs a useful tool in measuring temporal pore pressure variations for use in calibrating numerical models of fluid flow in variably saturated porous media.

  10. Advanced fuels for plutonium management in pressurized water reactors

    NASA Astrophysics Data System (ADS)

    Vasile, A.; Dufour, Ph; Golfier, H.; Grouiller, J. P.; Guillet, J. L.; Poinot, Ch; Youinou, G.; Zaetta, A.

    2003-06-01

    Several fuel concepts are under investigation at CEA with the aim of manage plutonium inventories in pressurized water reactors. This options range from the use of mature technologies like MOX adapted in the case of MOX-EUS (enriched uranium support) and COmbustible Recyclage A ILot (CORAIL) assemblies to more innovative technologies using IMF like DUPLEX and advanced plutonium assembly (APA). The plutonium burning performances reported to the electrical production go from 7 to 60 kg (TW h) -1. More detailed analysis covering economic, sustainability, reliability and safety aspects and their integration in the whole fuel cycle would allow identifying the best candidate.

  11. Hydrodynamic model of advanced pressurized fluidized bed combustion

    SciTech Connect

    Horio, Masayuki; Lei, H.W.

    1997-12-31

    A hydrodynamic model was developed for the advanced pressurized fluidized bed combustion (A-PFBC) process. The particular system investigated here is composed of a pressurized circulating fluidized bed (PCFB) for coal gasification/desulfurization and a PCFB for combustion with the gas-solid counter-current flow through the two PCFBs. One of the most important parameters may be the material seal height (MSH) in the downcomer connecting the gasifier/desulfurizer and the combustor, which is thought to strongly influence the safe and stable operation of the process. In this mode, MSH was determined according to the pressure balance between the gasifier/desulfurizer and the combustor. The solid flux in the lower dense region of the two PCFBs was estimated by considering the clustering suspension and core-annulus flow. The mean cluster size and voidage in the cluster phase were predicted by the cluster size model of Horio-Ito (1996). Solid flux of the gasifier and combustor was calculated based on mass balances of limestone, char and ash in the system. Based on this model, the whole pressure profile loop in the system was predicted, and the effects of operating conditions on MSH between the gasifier and the combustor were investigated. The feasibility of the A-PCFB system with PCFBs both for the gasifier/desulfurizer and for the combustor was successfully confirmed.

  12. COMPARISON OF THEORY AND MEASUREMENTS OF A TWO-STAGE LIGHT-GAS GUN

    SciTech Connect

    Levinson, S.; Berry, D.; Pedersen, B.; Bless, S.

    2009-12-28

    A comparison of techniques for obtaining projectile velocity history on a two-stage launcher and discuss gun code accuracy vis-a-vis pressure gauges and the new photonic Doppler velocimetry (PDV) technique is presented. The PDV technique itself is described in a companion paper. The PDV records were differentiated to compute acceleration and, hence, base pressure. Two acceleration episodes are revealed in the data. Base pressure values were compared with measurements from stationary pressure gauges and with predictions of a standard two-stage gun code. The agreement with the pressure gages was satisfactory. Code predictions did not account for the two acceleration stages. However, for the main acceleration episode, the predicted base pressure is in good agreement with the smoothed pressure computed from the PDV record. Both the gauge records and PDV contain short-time pressure spikes which are apparently real. Therefore, use of computed base pressure for projectile design may lead to failures if the projectile is vulnerable to pressure spikes.

  13. Pressure-Sensitive Paints Advance Rotorcraft Design Testing

    NASA Technical Reports Server (NTRS)

    2013-01-01

    The rotors of certain helicopters can spin at speeds as high as 500 revolutions per minute. As the blades slice through the air, they flex, moving into the wind and back out, experiencing pressure changes on the order of thousands of times a second and even higher. All of this makes acquiring a true understanding of rotorcraft aerodynamics a difficult task. A traditional means of acquiring aerodynamic data is to conduct wind tunnel tests using a vehicle model outfitted with pressure taps and other sensors. These sensors add significant costs to wind tunnel testing while only providing measurements at discrete locations on the model's surface. In addition, standard sensor solutions do not work for pulling data from a rotor in motion. "Typical static pressure instrumentation can't handle that," explains Neal Watkins, electronics engineer in Langley Research Center s Advanced Sensing and Optical Measurement Branch. "There are dynamic pressure taps, but your costs go up by a factor of five to ten if you use those. In addition, recovery of the pressure tap readings is accomplished through slip rings, which allow only a limited amount of sensors and can require significant maintenance throughout a typical rotor test." One alternative to sensor-based wind tunnel testing is pressure sensitive paint (PSP). A coating of a specialized paint containing luminescent material is applied to the model. When exposed to an LED or laser light source, the material glows. The glowing material tends to be reactive to oxygen, explains Watkins, which causes the glow to diminish. The more oxygen that is present (or the more air present, since oxygen exists in a fixed proportion in air), the less the painted surface glows. Imaged with a camera, the areas experiencing greater air pressure show up darker than areas of less pressure. "The paint allows for a global pressure map as opposed to specific points," says Watkins. With PSP, each pixel recorded by the camera becomes an optical pressure

  14. Structure design of and experimental research on a two-stage laval foam breaker for foam fluid recycling.

    PubMed

    Wang, Jin-song; Cao, Pin-lu; Yin, Kun

    2015-07-01

    Environmental, economical and efficient antifoaming technology is the basis for achievement of foam drilling fluid recycling. The present study designed a novel two-stage laval mechanical foam breaker that primarily uses vacuum generated by Coanda effect and Laval principle to break foam. Numerical simulation results showed that the value and distribution of negative pressure of two-stage laval foam breaker were larger than that of the normal foam breaker. Experimental results showed that foam-breaking efficiency of two-stage laval foam breaker was higher than that of normal foam breaker, when gas-to-liquid ratio and liquid flow rate changed. The foam-breaking efficiency of normal foam breaker decreased rapidly with increasing foam stability, whereas the two-stage laval foam breaker remained unchanged. Foam base fluid would be recycled using two-stage laval foam breaker, which would reduce the foam drilling cost sharply and waste disposals that adverse by affect the environment.

  15. Advanced Extra-Vehicular Activity Pressure Garment Requirements Development

    NASA Technical Reports Server (NTRS)

    Ross, Amy; Aitchison, Lindsay; Rhodes, Richard

    2015-01-01

    The NASA Johnson Space Center advanced pressure garment technology development team is addressing requirements development for exploration missions. Lessons learned from the Z-2 high fidelity prototype development have reiterated that clear low-level requirements and verification methods reduce risk to the government, improve efficiency in pressure garment design efforts, and enable the government to be a smart buyer. The expectation is to provide requirements at the specification level that are validated so that their impact on pressure garment design is understood. Additionally, the team will provide defined verification protocols for the requirements. However, in reviewing exploration space suit high level requirements there are several gaps in the team's ability to define and verify related lower level requirements. This paper addresses the efforts in requirement areas such as mobility/fit/comfort and environmental protection (dust, radiation, plasma, secondary impacts) to determine the method by which the requirements can be defined and use of those methods for verification. Gaps exist at various stages. In some cases component level work is underway, but no system level effort has begun; in other cases no effort has been initiated to close the gap. Status of on-going efforts and potential approaches to open gaps are discussed.

  16. STARS A Two Stage High Gain Harmonic Generation FEL Demonstrator

    SciTech Connect

    M. Abo-Bakr; W. Anders; J. Bahrdt; P. Budz; K.B. Buerkmann-Gehrlein; O. Dressler; H.A. Duerr; V. Duerr; W. Eberhardt; S. Eisebitt; J. Feikes; R. Follath; A. Gaupp; R. Goergen; K. Goldammer; S.C. Hessler; K. Holldack; E. Jaeschke; Thorsten Kamps; S. Klauke; J. Knobloch; O. Kugeler; B.C. Kuske; P. Kuske; A. Meseck; R. Mitzner; R. Mueller; M. Neeb; A. Neumann; K. Ott; D. Pfluckhahn; T. Quast; M. Scheer; Th. Schroeter; M. Schuster; F. Senf; G. Wuestefeld; D. Kramer; Frank Marhauser

    2007-08-01

    BESSY is proposing a demonstration facility, called STARS, for a two-stage high-gain harmonic generation free electron laser (HGHG FEL). STARS is planned for lasing in the wavelength range 40 to 70 nm, requiring a beam energy of 325 MeV. The facility consists of a normal conducting gun, three superconducting TESLA-type acceleration modules modified for CW operation, a single stage bunch compressor and finally a two-stage HGHG cascaded FEL. This paper describes the faciliy layout and the rationale behind the operation parameters.

  17. Premixing and flash vaporization in a two-stage combustor

    SciTech Connect

    Sjoblom, B.G.A.

    1982-01-01

    A double recirculation zone two-stage combustor fitted with airblast atomizers has been investigated in a previous work. This paper describes further tests with premixing tubes in the secondary combustion zone. Flash vaporization was employed to ensure complete vaporization of the secondary fuel, which was heated to 600K by the combustor inlet air. 9 refs.

  18. Analysis of two-stage Joule-Thomson expansion

    NASA Astrophysics Data System (ADS)

    Narasaki, Katsuhiro

    2016-03-01

    To cool far infrared detectors for infrared observation or superconductor-insulator-superconductor (SIS) mixers for atmospheric observation, 1 K-class and 4 K-class coolers have been developed. These coolers consist of a two-stage Stirling cooler for pre-cooling and a Joule-Thomson (JT) cooler with a single JT valve. This paper presents descriptions of theoretical analyses based on enthalpy balance to elucidate the benefits of a two-stage JT valve type compared with those of a single JT valve type in a JT cooler. First, relational expressions for heat balance analysis of enthalpy for single-stage JT expansion are introduced. Then similar relational expressions for two-stage JT expansion are introduced under some assumptions. Results of heat balance analyses using several parameters demonstrated that, using two-stage JT expansion, the cooling capacity for a 1 K-class cooler is improved by 100%; that of a 4 K-class cooler is improved by about 30%.

  19. A two-stage dynamic model for visual tracking.

    PubMed

    Kristan, Matej; Kovacic, Stanislav; Leonardis, Aleš; Pers, Janez

    2010-12-01

    We propose a new dynamic model which can be used within blob trackers to track the target's center of gravity. A strong point of the model is that it is designed to track a variety of motions which are usually encountered in applications such as pedestrian tracking, hand tracking, and sports. We call the dynamic model a two-stage dynamic model due to its particular structure, which is a composition of two models: a liberal model and a conservative model. The liberal model allows larger perturbations in the target's dynamics and is able to account for motions in between the random-walk dynamics and the nearly constant-velocity dynamics. On the other hand, the conservative model assumes smaller perturbations and is used to further constrain the liberal model to the target's current dynamics. We implement the two-stage dynamic model in a two-stage probabilistic tracker based on the particle filter and apply it to two separate examples of blob tracking: 1) tracking entire persons and 2) tracking of a person's hands. Experiments show that, in comparison to the widely used models, the proposed two-stage dynamic model allows tracking with smaller number of particles in the particle filter (e.g., 25 particles), while achieving smaller errors in the state estimation and a smaller failure rate. The results suggest that the improved performance comes from the model's ability to actively adapt to the target's motion during tracking.

  20. Impressions in cleft lip and palate--a novel two stage technique.

    PubMed

    Pani, Sharat Chandra; Hedge, Amitha M

    2008-01-01

    Though the field of presurgical orthopedics for the management of children with cleft Lip and Palate (CLAP) has made great advances over the past few decades, little is found in literature regarding the imressions required to fabricate these appliances. The purpose of this paper is to describe a novel two stage technique utilizing greenstick compound and addition silicone impression material to provide a safe, economical and accurate method for recording impressions in children with cleft lip and palate.

  1. Advances in Positive Airway Pressure Treatment Modalities for Hypoventilation Syndromes

    PubMed Central

    Combs, Dan; Shetty, Safal; Parthasarathy, Sairam

    2014-01-01

    SYNOPSIS Rationale Positive airway pressure therapy for hypoventilation syndromes can significantly improve health-related quality of life (HR-QOL), healthcare costs, and even mortality. The sleep-disordered breathing in such individuals are quite complex and require sophisticated devices with algorithms that are designed to accurately detect and effectively treat respiratory events that includes hypoventilation, upper airway obstruction, lower airway obstruction, central apneas and central hypopneas and reduce the work of breathing while maintaining breathing comfort. Objectives The therapeutic physiological rationale for the various advanced PAP modalities and the details about the principles of operation and technology implementation are provided here. Conclusions The physiological rationale for advanced PAP modalities is sound considering the complexity of sleep-disordered breathing in patients with hypoventilation syndromes. Although such devices are increasingly used in clinical practice, the supporting clinical evidence – specifically comparative-effectiveness studies in real-life conditions -- needs to be performed. Moreover, there is much opportunity for further refining these devices that include the ability of the device to reliably monitor gas-exchange, sleep-wakefulness state, and for reducing variability in device efficacy due to provider-selected device-settings. PMID:25346650

  2. Ambulatory pulmonary artery pressure monitoring in advanced heart failure patients

    PubMed Central

    Yandrapalli, Srikanth; Raza, Anoshia; Tariq, Sohaib; Aronow, Wilbert S

    2017-01-01

    Heart failure (HF) is an emerging epidemic associate with significant morbidity, mortality, and health care expenditure. Although there were major advances in pharmacologic and device based therapies for the management of HF, mortality of this condition remains high. Accurate monitoring of HF patients for exacerbations is very important to reduce recurrent hospitalizations and its associated complications. With the failure of clinical signs, tele-monitoring, and laboratory bio-markers to function as early markers of HF exacerbations, more sophisticated techniques were sought to accurately predict the circulatory status in HF patients in order to execute timely pharmacological intervention to reduce frequent hospitalizations. CardioMEMSTM (St. Jude Medical, Inc., Saint Paul, Minnesota) is an implantable, wireless pulmonary arterial pressure (PAP) monitoring system which transmits the patient’s continuous PAPs to the treating health care provider in the ambulatory setting. PAP-guided medical therapy modification has been shown to significantly reduce HF-related hospitalization and overall mortality. In advanced stages of HF, wireless access to hemodynamic information correlated with earlier left ventricular assist device implantation and shorter time to heart transplantation. PMID:28163833

  3. Changes to the LANL gas-driven two-stage gun: Magnetic gauge instrumentation, etc.

    SciTech Connect

    Sheffield, S.A.; Gustavsen, R.L.; Martinez, A.R.; Alcon, R.R.

    1996-12-31

    Our gas-driven two-stage gun was designed and built to do initiation studies on insensitive high explosives as well as other equation of state experiments on inert materials. Our preferred method of measuring initiation phenomena involves the use of magnetic particle velocity gauges. In order to accommodate this type of gauging in our two-stage gun, projectile velocity was sacrificed in favor of a larger experimental target area (obtained by using a 50 mm diameter launch tube). We have used magnetic gauging on our 72-mm bore diameter single-stage gun for over 15 years and it has proven a very effective technique to monitor reactive shock wave evolution. This technique has now been adapted to our gas-driven two-stage gun. We describe the method used, as well as some of the difficulties that arose while installing this technique. Several magnetic gauge experiments have been completed on plastic materials. Waveforms obtained in one experiment are given, along with the Hugoniot information that was obtained. This new technique is now working quite well, as is evidenced by the data. To our knowledge, this is the first time magnetic gauging has been used on a two-stage gun. We have also made changes to the burst diaphragm package in the transition section to ensure that the petals do not break off during the opening process and to increase the burst pressure. This will also be discussed briefly.

  4. High-pressure propulsion - advanced concepts for cooling

    NASA Astrophysics Data System (ADS)

    Schoerman, Leonard

    The state-of-the-art liquid propellant cooled combustion chambers utilized in the space shuttle are third-generation designs which have evolved from a continuing demand for higher operating pressure and aircraft-type reusability. History has shown that major advances in cooling occur in approximately ten-year cycles, with each cycle providing a nominal 400% increase in operating pressure and/or a higher degree of reusability. The previous technologies include the first-generation double-wall steel jackets used in the 220 psi V-2 and Aerobee, and the second generation wire-wrapped double tapered tubular assemblies typical of the 800 psi Titan I, II, and III, and 1000 psi F-1 engines. The third-generation designs utilize milled slot, high thermal conductivity liners and electrodeposited nickel closures. The space shuttle main engine operating at 3200 psia is adequate for individual flights; however, the desired goal of 55 service-free missions has yet to be realized. Future single-stage-to-orbit propulsion concepts can benefit from a further increase in operating pressures to 6000 to 10,000 psi combined with engine reuse capabilities in excess of the 55 flight goals of the space shuttle. A fourth-generation approach will be required to attain these more ambitious goals. These new designs will require a combination of cooling processes, including regenerative and transpiration, combined with improved high-temperature materials and new fabrication techniques. The limitations of the third-generation designs, the impact of propellant/coolant selection, and the approaches for the coming fourth-generation cooling technologies are discussed.

  5. Two-Stage Variable Sample-Rate Conversion System

    NASA Technical Reports Server (NTRS)

    Tkacenko, Andre

    2009-01-01

    A two-stage variable sample-rate conversion (SRC) system has been pro posed as part of a digital signal-processing system in a digital com munication radio receiver that utilizes a variety of data rates. The proposed system would be used as an interface between (1) an analog- todigital converter used in the front end of the receiver to sample an intermediatefrequency signal at a fixed input rate and (2) digita lly implemented tracking loops in subsequent stages that operate at v arious sample rates that are generally lower than the input sample r ate. This Two-Stage System would be capable of converting from an input sample rate to a desired lower output sample rate that could be var iable and not necessarily a rational fraction of the input rate.

  6. Multifunctional two-stage riser fluid catalytic cracking process.

    PubMed

    Zhang, Jinhong; Shan, Honghong; Chen, Xiaobo; Li, Chunyi; Yang, Chaohe

    This paper described the discovering process of some shortcomings of the conventional fluid catalytic cracking (FCC) process and the proposed two-stage riser (TSR) FCC process for decreasing dry gas and coke yields and increasing light oil yield, which has been successfully applied in 12 industrial units. Furthermore, the multifunctional two-stage riser (MFT) FCC process proposed on the basis of the TSR FCC process was described, which were carried out by the optimization of reaction conditions for fresh feedstock and cycle oil catalytic cracking, respectively, by the coupling of cycle oil cracking and light FCC naphtha upgrading processes in the second-stage riser, and the specially designed reactor for further reducing the olefin content of gasoline. The pilot test showed that it can further improve the product quality, increase the diesel yield, and enhance the conversion of heavy oil.

  7. The design of two-stage-to-orbit vehicles

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Two separate student design groups developed conceptual designs for a two-stage-to-orbit vehicle, with each design group consisting of a carrier team and an orbiter team. A two-stage-to-orbit system is considered in the event that single-stage-to-orbit is deemed not feasible in the foreseeable future; the two-stage system would also be used as a complement to an already existing heavy lift vehicle. The design specifications given are to lift a 10,000-lb payload 27 ft long by 10 ft diameter, to low Earth orbit (300 n.m.) using an air breathing carrier configuration that will take off horizontally within 15,000 ft. The staging Mach number and altitude were to be determined by the design groups. One group designed a delta wing/body carrier with the orbiter nested within the fuselage of the carrier, and the other group produced a blended cranked-delta wing/body carrier with the orbiter in the more conventional piggyback configuration. Each carrier used liquid hydrogen-fueled turbofanramjet engines, with data provided by General Electric Aircraft Engine Group. While one orbiter used a full-scale Space Shuttle Main Engine (SSME), the other orbiter employed a half-scale SSME coupled with scramjet engines, with data again provided by General Electric. The two groups conceptual designs, along with the technical trade-offs, difficulties, and details that surfaced during the design process are presented.

  8. Two-Stage Machine Learning model for guideline development.

    PubMed

    Mani, S; Shankle, W R; Dick, M B; Pazzani, M J

    1999-05-01

    We present a Two-Stage Machine Learning (ML) model as a data mining method to develop practice guidelines and apply it to the problem of dementia staging. Dementia staging in clinical settings is at present complex and highly subjective because of the ambiguities and the complicated nature of existing guidelines. Our model abstracts the two-stage process used by physicians to arrive at the global Clinical Dementia Rating Scale (CDRS) score. The model incorporates learning intermediate concepts (CDRS category scores) in the first stage that then become the feature space for the second stage (global CDRS score). The sample consisted of 678 patients evaluated in the Alzheimer's Disease Research Center at the University of California, Irvine. The demographic variables, functional and cognitive test results used by physicians for the task of dementia severity staging were used as input to the machine learning algorithms. Decision tree learners and rule inducers (C4.5, Cart, C4.5 rules) were selected for our study as they give expressive models, and Naive Bayes was used as a baseline algorithm for comparison purposes. We first learned the six CDRS category scores (memory, orientation, judgement and problem solving, personal care, home and hobbies, and community affairs). These learned CDRS category scores were then used to learn the global CDRS scores. The Two-Stage ML model classified as well as or better than the published inter-rater agreements for both the category and global CDRS scoring by dementia experts. Furthermore, for the most critical distinction, normal versus very mildly impaired, the Two-Stage ML model was 28.1 and 6.6% more accurate than published performances by domain experts. Our study of the CDRS examined one of the largest, most diverse samples in the literature, suggesting that our findings are robust. The Two-Stage ML model also identified a CDRS category, Judgment and Problem Solving, which has low classification accuracy similar to published

  9. Advanced research and technology programs for advanced high-pressure oxygen-hydrogen rocket propulsion

    NASA Astrophysics Data System (ADS)

    Marsik, S. J.; Morea, S. F.

    1985-03-01

    A research and technology program for advanced high pressure, oxygen-hydrogen rocket propulsion technology is presently being pursued by the National Aeronautics and Space Administration (NASA) to establish the basic discipline technologies, develop the analytical tools, and establish the data base necessary for an orderly evolution of the staged combustion reusable rocket engine. The need for the program is based on the premise that the USA will depend on the Shuttle and its derivative versions as its principal Earth-to-orbit transportation system for the next 20 to 30 yr. The program is focused in three principal areas of enhancement: (1) life extension, (2) performance, and (3) operations and diagnosis. Within the technological disciplines the efforts include: rotordynamics, structural dynamics, fluid and gas dynamics, materials fatigue/fracture/life, turbomachinery fluid mechanics, ignition/combustion processes, manufacturing/producibility/nondestructive evaluation methods and materials development/evaluation. An overview of the Advanced High Pressure Oxygen-Hydrogen Rocket Propulsion Technology Program Structure and Working Groups objectives are presented with highlights of several significant achievements.

  10. Advanced research and technology program for advanced high pressure oxygen-hydrogen rocket propulsion

    NASA Technical Reports Server (NTRS)

    Marsik, S. J.; Morea, S. F.

    1985-01-01

    A research and technology program for advanced high pressure, oxygen-hydrogen rocket propulsion technology is presently being pursued by the National Aeronautics and Space Administration (NASA) to establish the basic discipline technologies, develop the analytical tools, and establish the data base necessary for an orderly evolution of the staged combustion reusable rocket engine. The need for the program is based on the premise that the USA will depend on the Shuttle and its derivative versions as its principal Earth-to-orbit transportation system for the next 20 to 30 yr. The program is focused in three principal areas of enhancement: (1) life extension, (2) performance, and (3) operations and diagnosis. Within the technological disciplines the efforts include: rotordynamics, structural dynamics, fluid and gas dynamics, materials fatigue/fracture/life, turbomachinery fluid mechanics, ignition/combustion processes, manufacturing/producibility/nondestructive evaluation methods and materials development/evaluation. An overview of the Advanced High Pressure Oxygen-Hydrogen Rocket Propulsion Technology Program Structure and Working Groups objectives are presented with highlights of several significant achievements.

  11. Advanced research and technology programs for advanced high-pressure oxygen-hydrogen rocket propulsion

    NASA Technical Reports Server (NTRS)

    Marsik, S. J.; Morea, S. F.

    1985-01-01

    A research and technology program for advanced high pressure, oxygen-hydrogen rocket propulsion technology is presently being pursued by the National Aeronautics and Space Administration (NASA) to establish the basic discipline technologies, develop the analytical tools, and establish the data base necessary for an orderly evolution of the staged combustion reusable rocket engine. The need for the program is based on the premise that the USA will depend on the Shuttle and its derivative versions as its principal Earth-to-orbit transportation system for the next 20 to 30 yr. The program is focused in three principal areas of enhancement: (1) life extension, (2) performance, and (3) operations and diagnosis. Within the technological disciplines the efforts include: rotordynamics, structural dynamics, fluid and gas dynamics, materials fatigue/fracture/life, turbomachinery fluid mechanics, ignition/combustion processes, manufacturing/producibility/nondestructive evaluation methods and materials development/evaluation. An overview of the Advanced High Pressure Oxygen-Hydrogen Rocket Propulsion Technology Program Structure and Working Groups objectives are presented with highlights of several significant achievements.

  12. Isokinetic evaluation after two-stage bicruciate reconstruction

    PubMed Central

    GiglioTakaes, Igor; Inada, Mauro Mituso; de Miranda, João Batista; Cunha, Sérgio Augusto; Piedade, Sérgio Rocha

    2014-01-01

    Objective: To assess the functional balance of the knee after bicruciate reconstruction and its correlation with clinical score. Methods: 14 patients (11 men and three women), mean age 29.9±7.65 years, mean BMI 26.2±2.51 kg/m2 underwent surgical reconstruction of the Posterior Cruciate Ligament (PCL) and Anterior Cruciate Ligament (ACL) in two stages, with a mean interval of 3 months between procedures. With a mean follow-up period of 27.33 months, the isokinetic knee analysis was performed at 60°/s and 180°/s and the Lysholm and Tegner scores were applied. Results: The Lysholm score was 86.8±11.1 points and the Tegner score showed a deficit of 30% compared to pre-injury level. In isokinetic evaluation, the deficit of the operated quadriceps average torque was 17.05% at 60°/s and 12.16% at 180°/s, while the average flexor torque deficit was 3.43% at 60°/s and 5.82% at 180°/s. Although it was observed torque deficit between members, there were no statistical differences regarding the functional balance between hamstrings and quadriceps. Conclusion: Although the results of isokinetic evaluation has shown a functional balance of the knee (flexor-extensor), which may have contributed to the good subjective Lysholm score in the bicruciate two-stage reconstruction, two-stage reconstruction did not restore the pre-injury functional level. Level of Evidence IV, Case Series. PMID:24644415

  13. Two stage treatment of dairy effluent using immobilized Chlorella pyrenoidosa

    PubMed Central

    2013-01-01

    Background Dairy effluents contains high organic load and unscrupulous discharge of these effluents into aquatic bodies is a matter of serious concern besides deteriorating their water quality. Whilst physico-chemical treatment is the common mode of treatment, immobilized microalgae can be potentially employed to treat high organic content which offer numerous benefits along with waste water treatment. Methods A novel low cost two stage treatment was employed for the complete treatment of dairy effluent. The first stage consists of treating the diary effluent in a photobioreactor (1 L) using immobilized Chlorella pyrenoidosa while the second stage involves a two column sand bed filtration technique. Results Whilst NH4+-N was completely removed, a 98% removal of PO43--P was achieved within 96 h of two stage purification processes. The filtrate was tested for toxicity and no mortality was observed in the zebra fish which was used as a model at the end of 96 h bioassay. Moreover, a significant decrease in biological oxygen demand and chemical oxygen demand was achieved by this novel method. Also the biomass separated was tested as a biofertilizer to the rice seeds and a 30% increase in terms of length of root and shoot was observed after the addition of biomass to the rice plants. Conclusions We conclude that the two stage treatment of dairy effluent is highly effective in removal of BOD and COD besides nutrients like nitrates and phosphates. The treatment also helps in discharging treated waste water safely into the receiving water bodies since it is non toxic for aquatic life. Further, the algal biomass separated after first stage of treatment was highly capable of increasing the growth of rice plants because of nitrogen fixation ability of the green alga and offers a great potential as a biofertilizer. PMID:24355316

  14. Two-stage band selection algorithm for hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Velez-Reyes, Miguel; Linares, Daphnia M.; Jimenez-Rodriguez, Luis O.

    2002-08-01

    This paper presents a two-stage band optimal band selection algorithm for hyperspectral imagery. The algorithm tries to compute the closest subset of bands to the principal components in the sense of having the smallest canonical correlation. The first stage of the algorithm computes and initial guess for the closest bands using matrix-factorization-based band subset selection. The second stage refines the subset of bands using a steepest ascent algorithm. Experimental results using AVIRIS imagery from the Cuprite Mining District are presented.

  15. Two-stage dilute acid prehydrolysis of biomass

    DOEpatents

    Grohmann, Karel; Torget, Robert W.

    1992-01-01

    A two-stage dilute acid prehydrolysis process on xylan containing hemicellulose in biomass is effected by: treating feedstock of hemicellulosic material comprising xylan that is slow hydrolyzable and xylan that is fast hydrolyzable under predetermined low temperature conditions with a dilute acid for a residence time sufficient to hydrolyze the fast hydrolyzable xylan to xylose; removing said xylose from said fast hydrolyzable xylan and leaving a residue; and treating said residue having a slow hydrolyzable xylan with a dilute acid under predetermined high temperature conditions for a residence time required to hydrolyze said slow hydrolyzable xylan to xylose.

  16. Two-stage biohumus production from inedible potato biomass.

    PubMed

    Manukovsky, N S; Kovalev, V S; Gribovskaya, I V

    2001-07-01

    The feasibility of a two-stage bioconversion of inedible potato biomass into biohumus by oyster mushroom followed by worms was tested. As a raw material for biohumus production the inedible potato biomass in certain properties ranked below wheat straw. The most feasible method to convert the potato wastes into biohumus was to mix them with wheat straw at the mass ratio of 1:3 and then treat with mushrooms followed by worms. This gave a good yield of mushrooms. The biohumus produced from the mixture was suitable for use as a plant growth medium.

  17. Two-Stage FEL (Free Electron Laser) Program.

    DTIC Science & Technology

    1983-08-25

    Sargent and Spitzer editors, Addison-Wesley (1982). 3. S. B . Segall, H. R. Hiddleston, H. Takeda, S. Von Laven, R. Holsinger, J. Ward , J. Richardson, and W...1983). 4. S. Von Laven, S. B . Segall, J. F. Ward , "A Low Loss Quasioptical Cavity for a Two-Stage Free Electron Laser", in the proceedings of this...CLASSIFICATION OF THIS PAGE Mhen Data Entered) _ _"_ _ _A READ IMMUCTIONS REPORT DOCUMENTATION PAGE B n oR ORM I. REPORT NUMER 2. GOVT ACCESSION NO

  18. Two-stage series array SQUID amplifier for space applications

    NASA Astrophysics Data System (ADS)

    Tuttle, J. G.; DiPirro, M. J.; Shirron, P. J.; Welty, R. P.; Radparvar, M.

    We present test results for a two-stage integrated SQUID amplifier which uses a series array of d.c. SQUIDS to amplify the signal from a single input SQUID. The device was developed by Welty and Martinis at NIST and recent versions have been manufactured by HYPRES, Inc. Shielding and filtering techniques were employed during the testing to minimize the external noise. Energy resolution of 300 h was demonstrated using a d.c. excitation at frequencies above 1 kHz, and better than 500 h resolution was typical down to 300 Hz.

  19. Method of operating a two-stage coal gasifier

    DOEpatents

    Tanca, Michael C.

    1982-01-01

    A method of operating an entrained flow coal gasifier (10) via a two-stage gasification process. A portion of the coal (18) to be gasified is combusted in a combustion zone (30) with near stoichiometric air to generate combustion products. The combustion products are conveyed from the combustion zone into a reduction zone (32) wherein additional coal is injected into the combustion products to react with the combustion products to form a combustible gas. The additional coal is injected into the reduction zone as a mixture (60) consisting of coal and steam, preferably with a coal-to-steam weight ratio of approximately ten to one.

  20. Design of a Two-Stage Light Gas Gun for Muzzle Velocities of 10 - 11 kms

    NASA Technical Reports Server (NTRS)

    Bogdanoff, David W.

    2016-01-01

    Space debris poses a major risk to spacecraft. In low earth orbit, impact velocities can be 10 11 kms and as high as 15 kms. For debris shield design, it would be desirable to be able to launch controlled shape projectiles to these velocities. The design of the proposed 10 11 kmsec gun uses, as a starting point, the Ames 1.280.22 two stage gun, which has achieved muzzle velocities of 10 11.3 kmsec. That gun is scaled up to a 0.3125 launch tube diameter. The gun is then optimized with respect to maximum pressures by varying the pump tube length to diameter ratio (LD), the piston mass and the hydrogen pressure. A pump tube LD of 36.4 is selected giving the best overall performance. Piezometric ratios for the optimized guns are found to be 2.3, much more favorable than for more traditional two stage light gas guns, which range from 4 to 6. The maximum powder chamber pressures are 20 to 30 ksi. To reduce maximum pressures, the desirable range of the included angle of the cone of the high pressure coupling is found to be 7.3 to 14.6 degrees. Lowering the break valve rupture pressure is found to lower the maximum projectile base pressure, but to raise the maximum gun pressure. For the optimized gun with a pump tube LD of 36.4, increasing the muzzle velocity by decreasing the projectile mass and increasing the powder loads is studied. It appears that saboted spheres could be launched to 10.25 and possibly as high as 10.7 10.8 kmsec, and that disc-like plastic models could be launched to 11.05 kms. The use of a tantalum liner to greatly reduce bore erosion and increase muzzle velocity is discussed. With a tantalum liner, CFD code calculations predict muzzle velocities as high as 12 to 13 kms.

  1. Performance and stability of two-stage anaerobic digestion.

    PubMed

    Zahller, J D; Bucher, R H; Ferguson, J F; Stensel, H D

    2007-05-01

    The stability, capacity, and solids destruction efficiency of single versus two-stage anaerobic digestion was studied in bench-scale reactors using combined waste activated and primary sludge. Laboratory staged mesophilic digesters showed an improved volatile solids and volatile suspended solids destruction efficiency over a single-stage system (at the same total solids retention time [SRT]) of approximately 3.2 and 5.8 percentage points, respectively. To quantify stability and capacity, a new digester monitoring method was introduced that measured the digester maximum acetate utilization capacity, V(max,ac), and was used to investigate the potential for digester instability at different transient loadings. The ratio of the V(max,ac) value to the estimated acetate production rate for a given digester loading was termed the acetate capacity number (ACN). Values greater than 1.0 indicate excess acetate utilization capacity. The first stage of the laboratory two-stage mesophilic system (10-day SRT for each stage) had an ACN number of 1.3 compared with a value of 1.8 for the single-stage 20-day SRT digester. Thus, while a staged mesophilic system can improve solids destruction efficiency, it demonstrates a lower capacity for metabolizing highly variable loads.

  2. Two-stage anaerobic digestion enables heavy metal removal.

    PubMed

    Selling, Robert; Håkansson, Torbjörn; Björnsson, Lovisa

    2008-01-01

    To fully exploit the environmental benefits of the biogas process, the digestate should be recycled as biofertiliser to agriculture. This practice can however be jeopardized by the presence of unwanted compounds such as heavy metals in the digestate. By using two-stage digestion, where the first stage includes hydrolysis/acidification and liquefaction of the substrate, heavy metals can be transferred to the leachate. From the leachate, metals can then be removed by adsorption. In this study, up to 70% of the Ni, 40% of the Zn and 25% of the Cd present in maize was removed when the leachate from hydrolysis was circulated over a macroporous polyacrylamide column for 6 days. For Cu and Pb, the mobilization in the hydrolytic stage was lower which resulted in a low removal. A more efficient two-stage process with improved substrate hydrolysis would give lower pH and/or longer periods with low pH in the hydrolytic stage. This is likely to increase metal mobilisation, and would open up for an excellent opportunity of heavy metal removal.

  3. Two-stage mineralization of phenanthrene by estuarine enrichment cultures

    SciTech Connect

    Guerin, W.F.; Jones, G.E.

    1988-04-01

    The polycyclic aromatic hydrocarbon phenanthrene was mineralized in two stages by soil, estuarine water, and sediment microbial populations. At high concentrations, phenanthrene was degraded, with the concomitant production of biomass and accumulation of Folin-Ciocalteau-reactive aromatic intermediates. Subsequent consumption of these intermediates resulted in a secondary increase in biomass. Analysis of intermediates by high-performance liquid chromatography, thin-layer chromatography, and UV absorption spectrometry showed 1-hydroxy-2-naphthoic acid (1H2NA) to be the predominant product. A less pronounced two-stage mineralization pattern was also observed by monitoring /sup 14/CO/sub 2/ production from low concentrations (0.5 mg liter/sup -1/) of radiolabeled phenanthrene. Here, mineralization of /sup 14/C-labeled 1H2NA could explain the incremental /sup 14/CO/sub 2/ produced during the later part of the incubations. Accumulation of 1H2NA by isolates obtained from enrichments was dependent on the initial phenanthrene concentration. The production of metabolites during polycyclic aromatic hydrocarbon biodegradation is discussed with regard to its possible adaptive significance and its methodological implications.

  4. An optimal stratified Simon two-stage design.

    PubMed

    Parashar, Deepak; Bowden, Jack; Starr, Colin; Wernisch, Lorenz; Mander, Adrian

    2016-07-01

    In Phase II oncology trials, therapies are increasingly being evaluated for their effectiveness in specific populations of interest. Such targeted trials require designs that allow for stratification based on the participants' molecular characterisation. A targeted design proposed by Jones and Holmgren (JH) Jones CL, Holmgren E: 'An adaptive Simon two-stage design for phase 2 studies of targeted therapies', Contemporary Clinical Trials 28 (2007) 654-661.determines whether a drug only has activity in a disease sub-population or in the wider disease population. Their adaptive design uses results from a single interim analysis to decide whether to enrich the study population with a subgroup or not; it is based on two parallel Simon two-stage designs. We study the JH design in detail and extend it by providing a few alternative ways to control the familywise error rate, in the weak sense as well as the strong sense. We also introduce a novel optimal design by minimising the expected sample size. Our extended design contributes to the much needed framework for conducting Phase II trials in stratified medicine. © 2016 The Authors Pharmaceutical Statistics Published by John Wiley & Sons Ltd.

  5. Two-stage coal gasification and desulfurization apparatus

    DOEpatents

    Bissett, Larry A.; Strickland, Larry D.

    1991-01-01

    The present invention is directed to a system which effectively integrates a two-stage, fixed-bed coal gasification arrangement with hot fuel gas desulfurization of a first stream of fuel gas from a lower stage of the two-stage gasifier and the removal of sulfur from the sulfur sorbent regeneration gas utilized in the fuel-gas desulfurization process by burning a second stream of fuel gas from the upper stage of the gasifier in a combustion device in the presence of calcium-containing material. The second stream of fuel gas is taken from above the fixed bed in the coal gasifier and is laden with ammonia, tar and sulfur values. This second stream of fuel gas is burned in the presence of excess air to provide heat energy sufficient to effect a calcium-sulfur compound forming reaction between the calcium-containing material and sulfur values carried by the regeneration gas and the second stream of fuel gas. Any ammonia values present in the fuel gas are decomposed during the combustion of the fuel gas in the combustion chamber. The substantially sulfur-free products of combustion may then be combined with the desulfurized fuel gas for providing a combustible fluid utilized for driving a prime mover.

  6. Runway Operations Planning: A Two-Stage Heuristic Algorithm

    NASA Technical Reports Server (NTRS)

    Anagnostakis, Ioannis; Clarke, John-Paul

    2003-01-01

    The airport runway is a scarce resource that must be shared by different runway operations (arrivals, departures and runway crossings). Given the possible sequences of runway events, careful Runway Operations Planning (ROP) is required if runway utilization is to be maximized. From the perspective of departures, ROP solutions are aircraft departure schedules developed by optimally allocating runway time for departures given the time required for arrivals and crossings. In addition to the obvious objective of maximizing throughput, other objectives, such as guaranteeing fairness and minimizing environmental impact, can also be incorporated into the ROP solution subject to constraints introduced by Air Traffic Control (ATC) procedures. This paper introduces a two stage heuristic algorithm for solving the Runway Operations Planning (ROP) problem. In the first stage, sequences of departure class slots and runway crossings slots are generated and ranked based on departure runway throughput under stochastic conditions. In the second stage, the departure class slots are populated with specific flights from the pool of available aircraft, by solving an integer program with a Branch & Bound algorithm implementation. Preliminary results from this implementation of the two-stage algorithm on real-world traffic data are presented.

  7. Neuronal substrates characterizing two stages in visual object recognition.

    PubMed

    Taminato, Tomoya; Miura, Naoki; Sugiura, Motoaki; Kawashima, Ryuta

    2014-12-01

    Visual object recognition is classically believed to involve two stages: a perception stage in which perceptual information is integrated, and a memory stage in which perceptual information is matched with an object's representation. The transition from the perception to the memory stage can be slowed to allow for neuroanatomical segregation using a degraded visual stimuli (DVS) task in which images are first presented at low spatial resolution and then gradually sharpened. In this functional magnetic resonance imaging study, we characterized these two stages using a DVS task based on the classic model. To separate periods that are assumed to dominate the perception, memory, and post-recognition stages, subjects responded once when they could guess the identity of the object in the image and a second time when they were certain of the identity. Activation of the right medial occipitotemporal region and the posterior part of the rostral medial frontal cortex was found to be characteristic of the perception and memory stages, respectively. Although the known role of the former region in perceptual integration was consistent with the classic model, a likely role of the latter region in monitoring for confirmation of recognition suggests the advantage of recently proposed interactive models.

  8. A two-stage Stirling-type pulse tube cryocooler with a cold inertance tube

    NASA Astrophysics Data System (ADS)

    Gan, Z. H.; Fan, B. Y.; Wu, Y. Z.; Qiu, L. M.; Zhang, X. J.; Chen, G. B.

    2010-06-01

    A thermally coupled two-stage Stirling-type pulse tube cryocooler (PTC) with inertance tubes as phase shifters has been designed, manufactured and tested. In order to obtain a larger phase shift at the low acoustic power of about 2.0 W, a cold inertance tube as well as a cold reservoir for the second stage, precooled by the cold end of the first stage, was introduced into the system. The transmission line model was used to calculate the phase shift produced by the cold inertance tube. Effect of regenerator material, geometry and charging pressure on the performance of the second stage of the two-stage PTC was investigated based on the well known regenerator model REGEN. Experimental results of the two-stage PTC were carried out with an emphasis on the performance of the second stage. A lowest cooling temperature of 23.7 K and 0.50 W at 33.9 K were obtained with an input electric power of 150.0 W and an operating frequency of 40 Hz.

  9. Study on a high capacity two-stage free piston Stirling cryocooler working around 30 K

    NASA Astrophysics Data System (ADS)

    Wang, Xiaotao; Zhu, Jian; Chen, Shuai; Dai, Wei; Li, Ke; Pang, Xiaomin; Yu, Guoyao; Luo, Ercang

    2016-12-01

    This paper presents a two-stage high-capacity free-piston Stirling cryocooler driven by a linear compressor to meet the requirement of the high temperature superconductor (HTS) motor applications. The cryocooler system comprises a single piston linear compressor, a two-stage free piston Stirling cryocooler and a passive oscillator. A single stepped displacer configuration was adopted. A numerical model based on the thermoacoustic theory was used to optimize the system operating and structure parameters. Distributions of pressure wave, phase differences between the pressure wave and the volume flow rate and different energy flows are presented for a better understanding of the system. Some characterizing experimental results are presented. Thus far, the cryocooler has reached a lowest cold-head temperature of 27.6 K and achieved a cooling power of 78 W at 40 K with an input electric power of 3.2 kW, which indicates a relative Carnot efficiency of 14.8%. When the cold-head temperature increased to 77 K, the cooling power reached 284 W with a relative Carnot efficiency of 25.9%. The influences of different parameters such as mean pressure, input electric power and cold-head temperature are also investigated.

  10. Two-stage polling system with multiple servers

    NASA Astrophysics Data System (ADS)

    Lai, Wai Sum; Houck, David J.; Fuhrmann, Steven W.

    1997-10-01

    We investigate the impact of scheduling policies on the tail distribution of sojourn times experienced by various unevenly-loaded queues in a two-stage polling system served by a symmetric multiprocessor system running under a Unix- like operating system. The queues are statically divided into groups, with each group being managed by a process. A process can run on any of the available processors. Service to a customer is thus scheduled first at the process level and then at the queue level. Assuming that all customers have the same service requirement, and for Poisson arrivals and exponentially distributed service times and setup times, it is shown by simulation that the earliest-customer policy outperforms both 1-limited and exhaustive policies in the sense of providing equitable service to the queues.

  11. Investigation on Two-Stage 300 HZ Pulse Tube Cryocooler

    NASA Astrophysics Data System (ADS)

    Cai, H. K.; Yang, L. W.; Hong, G. T.; Luo, E. C.; Zhou, Y.

    2010-04-01

    In the past few years, ultra-high frequency pulse tube cryocoolers are becoming a research hotspot for their portability and compactness in aerospace and aviation applications. For preliminary research, a two-stage pulse tube cryocooler working at 300 Hz driven by a thermoacoustic engine is established to investigate the problems due to ultra high frequency, and several results have been derived in our early reports. In order to study the effect of thermal penetration depth, this paper presents the cooler adopting copper mesh as the regenerator, and comparison with stainless steel mesh is given. In addition, the influence of inertance tube on the lowest possible cooler temperature is also tested. Finally, we discuss the improvement for getting a lower temperature.

  12. Nonlinear two-stage model for color discrimination.

    PubMed

    Inamura, Taisuke; Shioiri, Satoshi; Tsujimura, Sei-ichi; Yaguchi, Hirohisa

    2011-04-01

    We modified a two-stage model for color discrimination proposed in a previous study [Color Res. Appl.25, 105 (2000)]; in order to extend the model to wider conditions, we considered the conditions with luminance modulations in addition to color modulations. Using the modified model, we successfully predicted color discrimination data with test color changes along both the chromatic and luminance axes under a variety of background colors. Both qualitative and quantitative assessments in modeling showed that nonlinearity is required in both the cone and the cone-opponent stages to interpret adaptation effects of both color and luminance on color discrimination. This fact suggests that the nonlinear properties at each stage have different roles in color perception.

  13. Two-stage designs for cross-over bioequivalence trials.

    PubMed

    Kieser, Meinhard; Rauch, Geraldine

    2015-07-20

    The topic of applying two-stage designs in the field of bioequivalence studies has recently gained attention in the literature and in regulatory guidelines. While there exists some methodological research on the application of group sequential designs in bioequivalence studies, implementation of adaptive approaches has focused up to now on superiority and non-inferiority trials. Especially, no comparison of the features and performance characteristics of these designs has been performed, and therefore, the question of which design to employ in this setting remains open. In this paper, we discuss and compare 'classical' group sequential designs and three types of adaptive designs that offer the option of mid-course sample size recalculation. A comprehensive simulation study demonstrates that group sequential designs can be identified, which show power characteristics that are similar to those of the adaptive designs but require a lower average sample size. The methods are illustrated with a real bioequivalence study example.

  14. Two-stage radio-frequency interferometer sensors

    PubMed Central

    Osterberg, Jeffrey; Wang, Pingshan

    2015-01-01

    We show that simple radio-frequency (RF) interferometers can have slow-wave positive group delay (PGD) or negative group delay (NGD), as well as superluminal propagation (SP) regions, due to a destructive interference process. These properties are easily tunable, which makes RF interferometers unique among systems that have NGD and SP regimes. A two-stage interferometer arrangement, which includes a first stage interferometer in the material-under-test path of a second stage, has significantly improved sensitivity in comparison with a one-stage reference interferometer. With a power divider based first stage and at its maximum NGD frequency, the frequency sensitivity improvement is as high as 7 times. With a quadrature based first stage, the sensitivity is increased by as much as 20 times. Sensitivity improvements are also observed at PGD and SP frequency regions. PMID:26576062

  15. The role of two-stage repair in modern hypospadiology

    PubMed Central

    Bracka, Aivar

    2008-01-01

    Hypospadias surgery continues to evolve. The enthusiasm for flap-based urethroplasty is waning and instead there is an increasing preference for urethroplasty that uses either the urethral plate alone or in combination with grafts. From the vast armamentarium of hypospadias repairs that are still in use, the author suggests a simple protocol of just three closely related procedures with which we can now repair almost all hypospadias. The tubularised incised plate (TIP) repair and the ‘Snodgraft’ modification of the TIP principle are simple and effective one-stage solutions when partial circumference urethroplasty is required. Conversely, the Bracka two-stage graft repair remains an ideal and versatile solution when a full circumference urethroplasty is required. It is particularly appropriate for severe primary hypospadias associated with a poor plate and marked chordee and also to replace a scarred, hairy or balanitis xerotica obliterans diseased urethra in re-operative salvage hypospadias. PMID:19468400

  16. Two-stage observer based offset-free MPC.

    PubMed

    Mohammadkhani, MohammadAli; Bayat, Farhad; Jalali, Ali Akbar

    2015-07-01

    This paper addresses design of model predictive control (MPC) for dynamic systems in the presence of disturbances. For the systems with disturbances, it is common to use observers to estimate states and disturbances, allowing control algorithm to reject disturbances. In this paper, we demonstrate how one can extend model predictive control for systems with disturbances by applying full state and disturbance observer. To this aim, a two-stage approach is proposed where the observer design procedure is completely decoupled from the MPC problem, known as the separation principle. We focus on the decoupling principal and it is shown that the observer can be designed independently via a norm minimization problem to reduce effects of disturbances and model mismatch. On the other hand, the MPC law is obtained using the multi-parametric quadratic programming approach where the parameters are the components of the state vector.

  17. Two-stage decision approach to material accounting

    SciTech Connect

    Opelka, J.H.; Sutton, W.B.

    1982-01-01

    The validity of the alarm threshold 4sigma has been checked for hypothetical large and small facilities using a two-stage decision model in which the diverter's strategic variable is the quantity diverted, and the defender's strategic variables are the alarm threshold and the effectiveness of the physical security and material control systems in the possible presence of a diverter. For large facilities, the material accounting system inherently appears not to be a particularly useful system for the deterrence of diversions, and essentially no improvement can be made by lowering the alarm threshold below 4sigma. For small facilities, reduction of the threshold to 2sigma or 3sigma is a cost effective change for the accounting system, but is probably less cost effective than making improvements in the material control and physical security systems.

  18. Two-stage radio-frequency interferometer sensors.

    PubMed

    Osterberg, Jeffrey; Wang, Pingshan

    2015-10-26

    We show that simple radio-frequency (RF) interferometers can have slow-wave positive group delay (PGD) or negative group delay (NGD), as well as superluminal propagation (SP) regions, due to a destructive interference process. These properties are easily tunable, which makes RF interferometers unique among systems that have NGD and SP regimes. A two-stage interferometer arrangement, which includes a first stage interferometer in the material-under-test path of a second stage, has significantly improved sensitivity in comparison with a one-stage reference interferometer. With a power divider based first stage and at its maximum NGD frequency, the frequency sensitivity improvement is as high as 7 times. With a quadrature based first stage, the sensitivity is increased by as much as 20 times. Sensitivity improvements are also observed at PGD and SP frequency regions.

  19. Performance of a highly loaded two stage axial-flow fan

    NASA Technical Reports Server (NTRS)

    Ruggeri, R. S.; Benser, W. A.

    1974-01-01

    A two-stage axial-flow fan with a tip speed of 1450 ft/sec (442 m/sec) and an overall pressure ratio of 2.8 was designed, built, and tested. At design speed and pressure ratio, the measured flow matched the design value of 184.2 lbm/sec (83.55kg/sec). The adiabatic efficiency at the design operating point was 85.7 percent. The stall margin at design speed was 10 percent. A first-bending-mode flutter of the second-stage rotor blades was encountered near stall at speeds between 77 and 93 percent of design, and also at high pressure ratios at speeds above 105 percent of design. A 5 deg closed reset of the first-stage stator eliminated second-stage flutter for all but a narrow speed range near 90 percent of design.

  20. Two Stage Assessment of Thermal Hazard in An Underground Mine

    NASA Astrophysics Data System (ADS)

    Drenda, Jan; Sułkowski, Józef; Pach, Grzegorz; Różański, Zenon; Wrona, Paweł

    2016-06-01

    The results of research into the application of selected thermal indices of men's work and climate indices in a two stage assessment of climatic work conditions in underground mines have been presented in this article. The difference between these two kinds of indices was pointed out during the project entitled "The recruiting requirements for miners working in hot underground mine environments". The project was coordinated by The Institute of Mining Technologies at Silesian University of Technology. It was a part of a Polish strategic project: "Improvement of safety in mines" being financed by the National Centre of Research and Development. Climate indices are based only on physical parameters of air and their measurements. Thermal indices include additional factors which are strictly connected with work, e.g. thermal resistance of clothing, kind of work etc. Special emphasis has been put on the following indices - substitute Silesian temperature (TS) which is considered as the climatic index, and the thermal discomfort index (δ) which belongs to the thermal indices group. The possibility of the two stage application of these indices has been taken into consideration (preliminary and detailed estimation). Based on the examples it was proved that by the application of thermal hazard (detailed estimation) it is possible to avoid the use of additional technical solutions which would be necessary to reduce thermal hazard in particular work places according to the climate index. The threshold limit value for TS has been set, based on these results. It was shown that below TS = 24°C it is not necessary to perform detailed estimation.

  1. Runway Operations Planning: A Two-Stage Solution Methodology

    NASA Technical Reports Server (NTRS)

    Anagnostakis, Ioannis; Clarke, John-Paul

    2003-01-01

    The airport runway is a scarce resource that must be shared by different runway operations (arrivals, departures and runway crossings). Given the possible sequences of runway events, careful Runway Operations Planning (ROP) is required if runway utilization is to be maximized. Thus, Runway Operations Planning (ROP) is a critical component of airport operations planning in general and surface operations planning in particular. From the perspective of departures, ROP solutions are aircraft departure schedules developed by optimally allocating runway time for departures given the time required for arrivals and crossings. In addition to the obvious objective of maximizing throughput, other objectives, such as guaranteeing fairness and minimizing environmental impact, may be incorporated into the ROP solution subject to constraints introduced by Air Traffic Control (ATC) procedures. Generating optimal runway operations plans was approached in with a 'one-stage' optimization routine that considered all the desired objectives and constraints, and the characteristics of each aircraft (weight class, destination, Air Traffic Control (ATC) constraints) at the same time. Since, however, at any given point in time, there is less uncertainty in the predicted demand for departure resources in terms of weight class than in terms of specific aircraft, the ROP problem can be parsed into two stages. In the context of the Departure Planner (OP) research project, this paper introduces Runway Operations Planning (ROP) as part of the wider Surface Operations Optimization (SOO) and describes a proposed 'two stage' heuristic algorithm for solving the Runway Operations Planning (ROP) problem. Focus is specifically given on including runway crossings in the planning process of runway operations. In the first stage, sequences of departure class slots and runwy crossings slots are generated and ranked based on departure runway throughput under stochastic conditions. In the second stage, the

  2. Advanced technology for minimum weight pressure vessel system

    NASA Technical Reports Server (NTRS)

    Hamstad, M. A.; Jessop, E. S.; Toland, R. H.

    1977-01-01

    Bosses were made of fiber/resin composite materials to evaluate their potential in lightweight pressure vessels. An approximate 25% weight savings over the standard aluminum boss was achieved without boss failures during burst tests. Polymer liners and metal liners are used in fiber composite pressure vessels for containment of gases. The internal support of these liners required during the filament winding process has previously been provided by dissolvable salt mandrels. An internal pressurization technique has been developed which allows overwinding the liner without other means of support and without collapse. Study was made of several additional concepts including styrene/Saran, styrene/flexible epoxy.

  3. Two-Stage, 90-GHz, Low-Noise Amplifier

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene A.; Gaier, Todd C.; Xenos, Stephanie; Soria, Mary M.; Kangaslahti, Pekka P.; Cleary, Kieran A.; Ferreira, Linda; Lai, Richard; Mei, Xiaobing

    2010-01-01

    A device has been developed for coherent detection of the polarization of the cosmic microwave background (CMB). A two-stage amplifier has been designed that covers 75-110 GHz. The device uses the emerging 35-nm InP HEMT technology recently developed at Northrop Grumman Corporation primarily for use at higher frequencies. The amplifier has more than 18 dB gain and less than 35 K noise figure across the band. These devices have noise less than 30 K at 100 GHz. The development started with design activities at JPL, as well as characterization of multichip modules using existing InP. Following processing, a test campaign was carried out using single-chip modules at 100 GHz. Successful development of the chips will lead to development of multichip modules, with simultaneous Q and U Stokes parameter detection. This MMIC (monolithic microwave integrated circuit) amplifier takes advantage of performance improvements intended for higher frequencies, but in this innovation are applied at 90 GHz. The large amount of available gain ultimately leads to lower possible noise performance at 90 GHz.

  4. Object Proposal Generation Using Two-Stage Cascade SVMs.

    PubMed

    Zhang, Ziming; Torr, Philip H S

    2016-01-01

    Object proposal algorithms have shown great promise as a first step for object recognition and detection. Good object proposal generation algorithms require high object detection recall rate as well as low computational cost, because generating object proposals is usually utilized as a preprocessing step. The problem of how to accelerate the object proposal generation and evaluation process without decreasing recall is thus of great interest. In this paper, we propose a new object proposal generation method using two-stage cascade support vector machines (SVMs), where in the first stage linear filters are learned for predefined quantized scales/aspect-ratios independently, and in the second stage a global linear classifier is learned across all the quantized scales/aspect-ratios for calibration, so that all the windows from the first stage can be compared properly. The windows with highest scores from the second stage are kept as inputs to our new efficient proposal calibration algorithm to improve their localization quality significantly, resulting in our final object proposals. We explain our scale/aspect-ratio quantization scheme, and investigate the effects of combinations of l1 and l2 regularizers in cascade SVMs with/without ranking constraints in learning. Comprehensive experiments on VOC2007 dataset are conducted, and our method is comparable with the current state-of-the-art methods with much better computational efficiency.

  5. Baseplate for two-stage cranial mounting of BMI connectors

    NASA Astrophysics Data System (ADS)

    McMorland, Angus J. C.; Velliste, Meel

    2013-06-01

    Objective. Intracortical electrode arrays provide the best spatial and temporal resolution signals for brain-machine interfaces. Wireless technologies are being developed to handle this information capacity, but currently the only means to deliver neural information from the implant to a signal processing unit is by a physical connection starting at a skull-mounted connector. The failure rate of the attachment of these connectors is significant. In this study we report an improvement to the traditional connectors. Approach. We have designed and applied an intermediary mounting plate that incorporates several features that provide better, more stable fixation to the skull: (1) wide legs allowing distribution of loading forces and distancing the intracranial screws from the skin interface, (2) a thin shelf to allow early osseointegration, (3) a concave interior to accommodate the curvature of the cranium, and (4) two-stage fixation process providing time for osseointegration prior to the application of loading forces from the connector. Main results. Six baseplates, over four design iterations, have now been tested in three non-human primates. The baseplates are associated with a substantially lower attachment failure rate. Significance. Our baseplate design improves on the current skull-mounted connectors, leading to better outcomes for subjects and fewer catastrophic failure events that can terminate resource intensive intracortical recording experiments.

  6. A two-stage approach to automatic face alignment

    NASA Astrophysics Data System (ADS)

    Wang, Tong; Ai, Haizhou; Huang, Gaofeng

    2003-09-01

    Face alignment is very important in face recognition, modeling and synthesis. Many approaches have been developed for this purpose, such as ASM, AAM, DAM and TC-ASM. After a brief review of all those methods, it is pointed out that these approaches all require a manual initialization to the positions of the landmarks and are very sensitive to it, and despite of all those devoted works the outline of a human face remains a difficult task to be localized precisely. In this paper, a two-stage method to achieve frontal face alignment fully automatically is introduced. The first stage is landmarks' initialization called coarse face alignment. In this stage, after a face is detected by an Adaboost cascade face detector, we use Simple Direct Appearance Model (SDAM) to locate a few key points of human face from the texture according which all the initial landmarks are setup as the coarse alignment. The second stage is fine face alignment that uses a variant of AAM method in which shape variation is predicted from texture reconstruction error together with an embedded ASM refinement for the outline landmarks of the face to achieve the fine alignment. Experiments on a face database of 500 people show that this method is very effective for practical applications.

  7. Laparoscopic management of a two staged gall bladder torsion

    PubMed Central

    Sunder, Yadav Kamal; Akhilesh, Sali Priyanka; Raman, Garg; Deborshi, Sharma; Shantilal, Mehta Hitesh

    2015-01-01

    Gall bladder torsion (GBT) is a relatively uncommon entity and rarely diagnosed preoperatively. A constant factor in all occurrences of GBT is a freely mobile gall bladder due to congenital or acquired anomalies. GBT is commonly observed in elderly white females. We report a 77-year-old, Caucasian lady who was originally diagnosed as gall bladder perforation but was eventually found with a two staged torsion of the gall bladder with twisting of the Riedel’s lobe (part of tongue like projection of liver segment 4A). This together, has not been reported in literature, to the best of our knowledge. We performed laparoscopic cholecystectomy and she had an uneventful post-operative period. GBT may create a diagnostic dilemma in the context of acute cholecystitis. Timely diagnosis and intervention is necessary, with extra care while operating as the anatomy is generally distorted. The fundus first approach can be useful due to altered anatomy in the region of Calot’s triangle. Laparoscopic cholecystectomy has the benefit of early recovery. PMID:26730287

  8. A two-stage model of fracture of rocks

    USGS Publications Warehouse

    Kuksenko, V.; Tomilin, N.; Damaskinskaya, E.; Lockner, D.

    1996-01-01

    In this paper we propose a two-stage model of rock fracture. In the first stage, cracks or local regions of failure are uncorrelated occur randomly throughout the rock in response to loading of pre-existing flaws. As damage accumulates in the rock, there is a gradual increase in the probability that large clusters of closely spaced cracks or local failure sites will develop. Based on statistical arguments, a critical density of damage will occur where clusters of flaws become large enough to lead to larger-scale failure of the rock (stage two). While crack interaction and cooperative failure is expected to occur within clusters of closely spaced cracks, the initial development of clusters is predicted based on the random variation in pre-existing Saw populations. Thus the onset of the unstable second stage in the model can be computed from the generation of random, uncorrelated damage. The proposed model incorporates notions of the kinetic (and therefore time-dependent) nature of the strength of solids as well as the discrete hierarchic structure of rocks and the flaw populations that lead to damage accumulation. The advantage offered by this model is that its salient features are valid for fracture processes occurring over a wide range of scales including earthquake processes. A notion of the rank of fracture (fracture size) is introduced, and criteria are presented for both fracture nucleation and the transition of the failure process from one scale to another.

  9. Optimal two-stage enrichment design correcting for biomarker misclassification.

    PubMed

    Zang, Yong; Guo, Beibei

    2015-11-26

    The enrichment design is an important clinical trial design to detect the treatment effect of the molecularly targeted agent (MTA) in personalized medicine. Under this design, patients are stratified into marker-positive and marker-negative subgroups based on their biomarker statuses and only the marker-positive patients are enrolled into the trial and randomized to receive either the MTA or a standard treatment. As the biomarker plays a key role in determining the enrollment of the trial, a misclassification of the biomarker can induce substantial bias, undermine the integrity of the trial, and seriously affect the treatment evaluation. In this paper, we propose a two-stage optimal enrichment design that utilizes the surrogate marker to correct for the biomarker misclassification. The proposed design is optimal in the sense that it maximizes the probability of correctly classifying each patient's biomarker status based on the surrogate marker information. In addition, after analytically deriving the bias caused by the biomarker misclassification, we develop a likelihood ratio test based on the EM algorithm to correct for such bias. We conduct comprehensive simulation studies to investigate the operating characteristics of the optimal design and the results confirm the desirable performance of the proposed design.

  10. Apparatus and method for two-stage oxidation of wastes

    DOEpatents

    Fleischman, Scott D.

    1995-01-01

    An apparatus and method for oxidizing wastes in a two-stage process. The apparatus includes an oxidation device, a gas-liquid contacting column and an electrocell. In the first stage of the process, wastes are heated in the presence of air to partially oxidize the wastes. The heated wastes produce an off-gas stream containing oxidizable materials. In the second stage, the off-gas stream is cooled and flowed through the contacting column, where the off-gas stream is contacted with an aqueous acid stream containing an oxidizing agent having at least two positive valence states. At least a portion of the oxidizable materials are transferred to the acid stream and destroyed by the oxidizing agent. During oxidation, the valence of the oxidizing agent is decreased from its higher state to its lower state. The acid stream is flowed to the electrocell, where an electric current is applied to the stream to restore the oxidizing agent to its higher valence state. The regenerated acid stream is recycled to the contacting column.

  11. A two-stage DEA approach for environmental efficiency measurement.

    PubMed

    Song, Malin; Wang, Shuhong; Liu, Wei

    2014-05-01

    The slacks-based measure (SBM) model based on the constant returns to scale has achieved some good results in addressing the undesirable outputs, such as waste water and water gas, in measuring environmental efficiency. However, the traditional SBM model cannot deal with the scenario in which desirable outputs are constant. Based on the axiomatic theory of productivity, this paper carries out a systematic research on the SBM model considering undesirable outputs, and further expands the SBM model from the perspective of network analysis. The new model can not only perform efficiency evaluation considering undesirable outputs, but also calculate desirable and undesirable outputs separately. The latter advantage successfully solves the "dependence" problem of outputs, that is, we can not increase the desirable outputs without producing any undesirable outputs. The following illustration shows that the efficiency values obtained by two-stage approach are smaller than those obtained by the traditional SBM model. Our approach provides a more profound analysis on how to improve environmental efficiency of the decision making units.

  12. A continuous two stage solar coal gasification system

    NASA Astrophysics Data System (ADS)

    Mathur, V. K.; Breault, R. W.; Lakshmanan, S.; Manasse, F. K.; Venkataramanan, V.

    The characteristics of a two-stage fluidized-bed hybrid coal gasification system to produce syngas from coal, lignite, and peat are described. Devolatilization heat of 823 K is supplied by recirculating gas heated by a solar receiver/coal heater. A second-stage gasifier maintained at 1227 K serves to crack remaining tar and light oil to yield a product free from tar and other condensables, and sulfur can be removed by hot clean-up processes. CO is minimized because the coal is not burned with oxygen, and the product gas contains 50% H2. Bench scale reactors consist of a stage I unit 0.1 m in diam which is fed coal 200 microns in size. A stage II reactor has an inner diam of 0.36 m and serves to gasify the char from stage I. A solar power source of 10 kWt is required for the bench model, and will be obtained from a central receiver with quartz or heat pipe configurations for heat transfer.

  13. Contactless two-stage solar concentrators for tubular absorber

    NASA Astrophysics Data System (ADS)

    Benitez, Pablo; Minano, Juan C.; Garcia, Raphael; Mohedano Arroyo, Ruben

    1997-10-01

    Two new types of two-mirror solar concentrator for tubular receiver, the snail concentrator and the helmet concentrator , are presented. The main feature of these concentrators is that they have a sizable gap between the secondary mirror and the absorber, and they still achieve concentrations close to the thermodynamic limit with high collection efficiencies. This characteristic makes them unique and, on the contrary to the present two-stage designs, allows for the location of the secondary outside the evacuated tube. One of the differences between the snail and the helmet concentrators is that the last is symmetric (as the conventional parabolic trough) but the first is not. For an acceptance angle of (alpha) equals +/- 0.73 degs and a collection efficiency of 96.8% (i.e. 3.2% of the rays incident on the primary mirror within the acceptance angle are rejected), the snail concentrator and the helmet concentrator achieve an average flux concentration of 91.1% and 72.8% of the thermodynamic limit, respectively. The gap between the absorber and the secondary mirror is 6.8 and 12.1 times the absorber radius for each concentrator. Moreover, both concentrators have also high rim angles of the primary mirror: +/- 86.2 degs (helmet) and 3.1 - 98.8 degs (snail). This is of interest for a good mechanical stability of the collector.

  14. Effect of two-stage coagulant addition on coagulation-ultrafiltration process for treatment of humic-rich water.

    PubMed

    Liu, Ting; Chen, Zhong-lin; Yu, Wen-zheng; Shen, Ji-min; Gregory, John

    2011-08-01

    A novel two-stage coagulant addition strategy applied in a coagulation-ultrafiltration (UF) process for treatment of humic-rich water at neutral pH was investigated in this study. When aluminum sulfate (alum) doses were set at a ratio of 3:1 added during rapid mix stage and half way through flocculation stage, the integrated process of two-stage alum addition achieved almost the same organic matter removal as that of conventional one-stage alum addition at the same overall dose. Whereas membrane fouling could be effectively mitigated by the two-stage addition exhibited by trans-membrane pressure (TMP) developments. The TMP developments were found to be primarily attributed to external fouling on membrane surface, which was closely associated with floc characteristics. The results of jar tests indicated that the average size of flocs formed in two-stage addition mode roughly reached one half larger than that in one-stage addition mode, which implied a beneficial effect on membrane fouling reduction. Moreover, the flocs with more irregular structure and lower effective density resulted from the two-stage alum addition, which caused higher porosity of cake layer formed by such flocs on membrane surface. Microscopic observations of membrane surface demonstrated that internal fouling in membrane pores could be also remarkably limited by two-stage alum addition. It is likely that the freshly formed hydroxide precipitates were distinct in surface characteristics from the aged precipitates due to formation of more active groups or adsorption of more labile aluminum species. Consequently, the flocs could further connect and aggregate to contribute to preferable properties for filtration performance of the coagulation-UF process. As a simple and efficient approach, two-stage coagulant addition strategy could have great practical significance in coagulation-membrane processes.

  15. Short-interval two-stage approach to primary total knee arthroplasty for acutely septic osteoarthritic knees.

    PubMed

    Hochreiter, Bettina; Strahm, Carol; Behrend, Henrik

    2016-10-01

    Treatment strategies for advanced knee osteoarthritis with coexistent joint infection are not well established. While in periprosthetic joint infection the two-stage approach has been studied extensively, only few case reports on two-stage total knee arthroplasty (TKA) for knee osteoarthritis with coexistent joint infection have been published. The purpose of this paper was to report on our method of implementing a two-stage TKA with intervening antibiotic-loaded articulating cement spacers and a short interval between first- and second-stage procedures to treat two patients with Staphylococcus aureus-infected end-stage knee osteoarthritis. Consistent infection eradication was found at a 1-year follow-up with postoperative range of motion and knee scores comparing favourably with those of other case series. Level of evidence V.

  16. Advanced composite fiber/metal pressure vessels for aircraft applications

    NASA Astrophysics Data System (ADS)

    Papanicolopoulos, Aleck

    1993-06-01

    Structural Composites Industries has developed, qualified, and delivered a number of high performance carbon epoxy overwrapped/seamless aluminum liner pressure vessels for use in military aircraft where low weight, low cost, high operating pressure and short lead time are the primary considerations. This paper describes product design, development, and qualification for a typical program. The vessel requirements included a munitions insensitivity criterion as evidenced by no fragmentation following impact by a .50 cal tumbling bullet. This was met by the development of a carbon-Spectra hybrid composite overwrap on a thin-walled seamless aluminum liner. The same manufacturing, inspection, and test processes that are used to produce lightweight, thin walled seamless aluminum lined carbon/epoxy overwrapped pressure vessels for satellite and other space applications were used to fabricate this vessel. This report focuses on the results of performance in the qualification testing.

  17. Two-stage Catalytic Reduction of NOx with Hydrocarbons

    SciTech Connect

    Umit S. Ozkan; Erik M. Holmgreen; Matthew M. Yung; Jonathan Halter; Joel Hiltner

    2005-12-21

    A two-stage system for the catalytic reduction of NO from lean-burn natural gas reciprocating engine exhaust is investigated. Each of the two stages uses a distinct catalyst. The first stage is oxidation of NO to NO{sub 2} and the second stage is reduction of NO{sub 2} to N{sub 2} with a hydrocarbon. The central idea is that since NO{sub 2} is a more easily reduced species than NO, it should be better able to compete with oxygen for the combustion reaction of hydrocarbon, which is a challenge in lean conditions. Early work focused on demonstrating that the N{sub 2} yield obtained when NO{sub 2} was reduced was greater than when NO was reduced. NO{sub 2} reduction catalysts were designed and silver supported on alumina (Ag/Al{sub 2}O{sub 3}) was found to be quite active, able to achieve 95% N{sub 2} yield in 10% O{sub 2} using propane as the reducing agent. The design of a catalyst for NO oxidation was also investigated, and a Co/TiO{sub 2} catalyst prepared by sol-gel was shown to have high activity for the reaction, able to reach equilibrium conversion of 80% at 300 C at GHSV of 50,000h{sup -1}. After it was shown that NO{sub 2} could be more easily reduced to N{sub 2} than NO, the focus shifted on developing a catalyst that could use methane as the reducing agent. The Ag/Al{sub 2}O{sub 3} catalyst was tested and found to be inactive for NOx reduction with methane. Through iterative catalyst design, a palladium-based catalyst on a sulfated-zirconia support (Pd/SZ) was synthesized and shown to be able to selectively reduce NO{sub 2} in lean conditions using methane. Development of catalysts for the oxidation reaction also continued and higher activity, as well as stability in 10% water, was observed on a Co/ZrO{sub 2} catalyst, which reached equilibrium conversion of 94% at 250 C at the same GHSV. The Co/ZrO{sub 2} catalyst was also found to be extremely active for oxidation of CO, ethane, and propane, which could potential eliminate the need for any separate

  18. Recent Advances in Food Processing Using High Hydrostatic Pressure Technology.

    PubMed

    Wang, Chung-Yi; Huang, Hsiao-Wen; Hsu, Chiao-Ping; Yang, Binghuei Barry

    2016-01-01

    High hydrostatic pressure is an emerging non-thermal technology that can achieve the same standards of food safety as those of heat pasteurization and meet consumer requirements for fresher tasting, minimally processed foods. Applying high-pressure processing can inactivate pathogenic and spoilage microorganisms and enzymes, as well as modify structures with little or no effects on the nutritional and sensory quality of foods. The U.S. Food and Drug Administration (FDA) and the U.S. Department of Agriculture (USDA) have approved the use of high-pressure processing (HPP), which is a reliable technological alternative to conventional heat pasteurization in food-processing procedures. This paper presents the current applications of HPP in processing fruits, vegetables, meats, seafood, dairy, and egg products; such applications include the combination of pressure and biopreservation to generate specific characteristics in certain products. In addition, this paper describes recent findings on the microbiological, chemical, and molecular aspects of HPP technology used in commercial and research applications.

  19. Time Pressure and Phonological Advance Planning in Spoken Production

    ERIC Educational Resources Information Center

    Damian, Markus F.; Dumay, Nicolas

    2007-01-01

    Current accounts of spoken production debate the extent to which speakers plan ahead. Here, we investigated whether the scope of phonological planning is influenced by changes in time pressure constraints. The first experiment used a picture-word interference task and showed that picture naming latencies were shorter when word distractors shared…

  20. MEMS pressure sensor fabricated by advanced bulk micromachining techniques

    NASA Astrophysics Data System (ADS)

    Vanko, Gabriel; Hudek, Peter; Zehetner, Johann; Dzuba, Jaroslav; Choleva, Pavlina; Vallo, Martin; Rýger, Ivan; Lalinský, Tibor

    2013-05-01

    We present the design and implementation of a MEMS pressure sensor with an operation potential under harsh conditions at high temperatures (T = 300 - 800°C). The sensor consists of a circular HEMT (C-HEMT) integrated on a circular AlGaN/GaN membrane. In order to realize MEMS for extreme conditions using AlGaN/GaN material system, two key issues should be solved: (a) realization of MEMS structures by etching of the substrate material and (b) formation of metallic contacts (both ohmic and Schottky) to be able to withstand high thermal loads. In this design concept the piezoresistive and piezoelectric effect of AlGaN/GaN heterostructure is used to sense the pressure under static and/or dynamic conditions. The backside bulk micromachining of our SiC wafer in the first experiment started with FS-laser ablation down to ~200 -270μm deep holes of 500μm in diameter. Because no additional intermediate layer can stop the ablation process, the number of laser pulses has to be optimized in order to reach the required ablation depth. 2D structural-mechanical and piezoelectric analyses were performed to verify the mechanical and piezoelectric response of the circular membrane pressure sensor to static pressure load (in the range between 20 and 100kPa). We suggested that suppressing the residual stress in the membrane can improve the sensor response. The parameters of the same devices previously fabricated on bulk substrates and/or membranes were compared. The maxima of drain currents of our C-HEMT devices on SiC exhibit more than four times higher values compared to those measured on silicon substrates.

  1. Metamodeling and Optimization of a Blister Copper Two-Stage Production Process

    NASA Astrophysics Data System (ADS)

    Jarosz, Piotr; Kusiak, Jan; Małecki, Stanisław; Morkisz, Paweł; Oprocha, Piotr; Pietrucha, Wojciech; Sztangret, Łukasz

    2016-06-01

    It is often difficult to estimate parameters for a two-stage production process of blister copper (containing 99.4 wt.% of Cu metal) as well as those for most industrial processes with high accuracy, which leads to problems related to process modeling and control. The first objective of this study was to model flash smelting and converting of Cu matte stages using three different techniques: artificial neural networks, support vector machines, and random forests, which utilized noisy technological data. Subsequently, more advanced models were applied to optimize the entire process (which was the second goal of this research). The obtained optimal solution was a Pareto-optimal one because the process consisted of two stages, making the optimization problem a multi-criteria one. A sequential optimization strategy was employed, which aimed for optimal control parameters consecutively for both stages. The obtained optimal output parameters for the first smelting stage were used as input parameters for the second converting stage. Finally, a search for another optimal set of control parameters for the second stage of a Kennecott-Outokumpu process was performed. The optimization process was modeled using a Monte-Carlo method, and both modeling parameters and computed optimal solutions are discussed.

  2. Investigation of gas stripping and pervaporation for improved feasibility of two-stage butanol production process.

    PubMed

    Setlhaku, Mpho; Heitmann, Sebastian; Górak, Andrzej; Wichmann, Rolf

    2013-05-01

    Gas stripping and pervaporation are investigated for butanol recovery in a two-stage acetone-butanol-ethanol (ABE) fermentation process. The first stage is operated in a continuous mode and the second stage as a fed-batch. Gas stripping coupled to the second stage and operated intermittently enabled additional glucose feeding in the second stage and up to 59 g/L butanol and 73 g/L total ABE solvents in the condensate. Concentration of 167 g/L butanol and 269 g/L ABE in the permeate was measured in ex situ pervaporation experiments using a PDMS membrane at temperature of 37 °C and pressure of 10mbars. The "operating window" tool is introduced to evaluate the feasibility of the existing ABE fermentations operated as continuous with cell recycle, as two-stages, with biomass immobilization or with integrated product removal. This tool enables the identification of the most favorable process configuration, which is the combination of cell immobilization and integrated product removal.

  3. Two-stage coal liquefaction without gas-phase hydrogen

    DOEpatents

    Stephens, H.P.

    1986-06-05

    A process is provided for the production of a hydrogen-donor solvent useful in the liquefaction of coal, wherein the water-gas shift reaction is used to produce hydrogen while simultaneously hydrogenating a donor solvent. A process for the liquefaction of coal using said solvent is also provided. The process enables avoiding the use of a separate water-gas shift reactor as well as high pressure equipment for liquefaction. 3 tabs.

  4. High-Energy Two-Stage Pulsed Plasma Thruster

    NASA Technical Reports Server (NTRS)

    Markusic, Tom

    2003-01-01

    A high-energy (28 kJ per pulse) two-stage pulsed plasma thruster (MSFC PPT-1) has been constructed and tested. The motivation of this project is to develop a high power (approximately 500 kW), high specific impulse (approximately 10000 s), highly efficient (greater than 50%) thruster for use as primary propulsion in a high power nuclear electric propulsion system. PPT-1 was designed to overcome four negative characteristics which have detracted from the utility of pulsed plasma thrusters: poor electrical efficiency, poor propellant utilization efficiency, electrode erosion, and reliability issues associated with the use of high speed gas valves and high current switches. Traditional PPTs have been plagued with poor efficiency because they have not been operated in a plasma regime that fully exploits the potential benefits of pulsed plasma acceleration by electromagnetic forces. PPTs have generally been used to accelerate low-density plasmas with long current pulses. Operation of thrusters in this plasma regime allows for the development of certain undesirable particle-kinetic effects, such as Hall effect-induced current sheet canting. PPT-1 was designed to propel a highly collisional, dense plasma that has more fluid-like properties and, hence, is more effectively pushed by a magnetic field. The high-density plasma loading into the second stage of the accelerator is achieved through the use of a dense plasma injector (first stage). The injector produces a thermal plasma, derived from a molten lithium propellant feed system, which is subsequently accelerated by the second stage using mega-amp level currents, which eject the plasma at a speed on the order of 100 kilometers per second. Traditional PPTs also suffer from dynamic efficiency losses associated with snowplow loading of distributed neutral propellant. The twostage scheme used in PPT-I allows the propellant to be loaded in a manner which more closely approximates the optimal slug loading. Lithium propellant

  5. Two-Stage Exams Improve Student Learning in an Introductory Geology Course: Logistics, Attendance, and Grades

    ERIC Educational Resources Information Center

    Knierim, Katherine; Turner, Henry; Davis, Ralph K.

    2015-01-01

    Two-stage exams--where students complete part one of an exam closed book and independently and part two is completed open book and independently (two-stage independent, or TS-I) or collaboratively (two-stage collaborative, or TS-C)--provide a means to include collaborative learning in summative assessments. Collaborative learning has been shown to…

  6. Hydrogen/Oxygen Propellant Densifier Using a Two-Stage Pulse Tube Cryocooler

    NASA Astrophysics Data System (ADS)

    Nguyen, C.; Yeckley, A.; Culler, A.; Haberbusch, M.; Radebaugh, R.

    2004-06-01

    A unique, patent pending, thermoacoustic propellant densifier, that simultaneously densifies liquid hydrogen and liquid oxygen propellants for aerospace vehicles is introduced. The thermoacoustic densifier consists of a two-stage pulse tube cryocooler that operates at 30 Hz using helium as the working fluid. The extremely reliable pulse tube has no moving parts, is water cooled, and is acoustically driven. The pulse tube has been driven by a Thermoacoustic Stirling Heat Engine (TASHE) and a linear flexure bearing compressor. A laboratory prototype was designed, fabricated, and tested at the Sierra Lobo, Inc. facility in Milan, Ohio. Unique design features include a removable 2nd stage for easy testing of low temperature regenerator materials and an advanced aftercooler design geometry. A system description will be presented and experimental data of the pulse tube performance will be compared with REGEN 3.2 and other analytical predictions.

  7. Advanced High-Temperature, High-Pressure Transport Reactor Gasification

    SciTech Connect

    Michael Swanson; Daniel Laudal

    2008-03-31

    The U.S. Department of Energy (DOE) National Energy Technology Laboratory Office of Coal and Environmental Systems has as its mission to develop advanced gasification-based technologies for affordable, efficient, zero-emission power generation. These advanced power systems, which are expected to produce near-zero pollutants, are an integral part of DOE's Vision 21 Program. DOE has also been developing advanced gasification systems that lower the capital and operating costs of producing syngas for chemical production. A transport reactor has shown potential to be a low-cost syngas producer compared to other gasification systems since its high-throughput-per-unit cross-sectional area reduces capital costs. This work directly supports the Power Systems Development Facility utilizing the KBR transport reactor located at the Southern Company Services Wilsonville, Alabama, site. Over 2800 hours of operation on 11 different coals ranging from bituminous to lignite along with a petroleum coke has been completed to date in the pilot-scale transport reactor development unit (TRDU) at the Energy & Environmental Research Center (EERC). The EERC has established an extensive database on the operation of these various fuels in both air-blown and oxygen-blown modes utilizing a pilot-scale transport reactor gasifier. This database has been useful in determining the effectiveness of design changes on an advanced transport reactor gasifier and for determining the performance of various feedstocks in a transport reactor. The effects of different fuel types on both gasifier performance and the operation of the hot-gas filter system have been determined. It has been demonstrated that corrected fuel gas heating values ranging from 90 to 130 Btu/scf have been achieved in air-blown mode, while heating values up to 230 Btu/scf on a dry basis have been achieved in oxygen-blown mode. Carbon conversions up to 95% have also been obtained and are highly dependent on the oxygen-coal ratio. Higher

  8. Performance of two-stage fan with larger dampers on first-stage rotor

    NASA Technical Reports Server (NTRS)

    Urasek, D. C.; Cunnan, W. S.; Stevans, W.

    1979-01-01

    The performance of a two stage, high pressure-ratio fan, having large, part-span vibration dampers on the first stage rotor is presented and compared with an identical aerodynamically designed fan having smaller dampers. Comparisons of the data for the two damper configurations show that with increased damper size: (1) very high losses in the damper region reduced overall efficiency of first stage rotor by approximately 3 points, (2) the overall performance of each blade row, downstream of the damper was not significantly altered, although appreciable differences in the radial distributions of various performance parameters were noted, and (3) the lower performance of the first stage rotor decreased the overall fan efficiency more than 1 percentage point.

  9. Performances of single and two-stage pulse tube cryocoolers under different vacuum levels with and without thermal radiation shields

    NASA Astrophysics Data System (ADS)

    Kasthurirengan, Srinivasan; Behera, Upendra; Nadig, D. S.; Krishnamoorthy, V.

    2012-06-01

    Single and two-stage Pulse Tube Cryocoolers (PTC) have been designed, fabricated and experimentally studied. The single stage PTC reaches a no-load temperature of ~ 29 K at its cold end, the two-stage PTC reaches ~ 2.9 K in its second stage cold end and ~ 60 K in its first stage cold end. The two-stage Pulse Tube Cryocooler provides a cooling power of ~ 250 mW at 4.2 K. The single stage system uses stainless steel meshes along with Pb granules as its regenerator materials, while the two-stage PTC uses combinations of Pb along with Er3Ni / HoCu2 as the second stage regenerator materials. Normally, the above systems are insulated by thermal radiation shields and mounted inside a vacuum chamber which is maintained at high vacuum. To evaluate the performance of these systems in the possible conditions of loss of vacuum with and without radiation shields, experimental studies have been performed. The heat-in-leak under such severe conditions has been estimated from the heat load characteristics of the respective stages. The experimental results are analyzed to obtain surface emissivities and effective thermal conductivities as a function of interspace pressure.

  10. A gas-loading system for LANL two-stage gas guns

    SciTech Connect

    Gibson, Lloyd Lee; Bartram, Brian Douglas; Dattelbaum, Dana Mcgraw; Lang, John Michael; Morris, John Scott

    2015-09-01

    A novel gas loading system was designed for the specific application of remotely loading high purity gases into targets for gas-gun driven plate impact experiments. The high purity gases are loaded into well-defined target configurations to obtain Hugoniot states in the gas phase at greater than ambient pressures.The small volume of the gas samples is challenging, as slight changing in the ambient temperature result in measurable pressure changes. Therefore, the ability to load a gas gun target and continually monitor the sample pressure prior to firing provides the most stable and reliable target fielding approach. We present the design and evaluation of a gas loading system built for the LANL 50 mm bore two-stage light gas gun. Targets for the gun are made of 6061 Al or OFHC Cu, and assembled to form a gas containment cell with a volume of approximately 1.38 cc. The compatibility of materials was a major consideration in the design of the system, particularly for its use with corrosive gases. Piping and valves are stainless steel with wetted seals made from Kalrez® and Teflon®. Preliminary testing was completed to ensure proper flow rate and that the proper safety controls were in place. The system has been used to successfully load Ar, Kr, Xe, and anhydrous ammonia with purities of up to 99.999 percent. The design of the system and example data from the plate impact experiments will be shown.

  11. A gas-loading system for LANL two-stage gas guns

    NASA Astrophysics Data System (ADS)

    Gibson, L. L.; Bartram, B. D.; Dattelbaum, D. M.; Lang, J. M.; Morris, J. S.

    2017-01-01

    A novel gas loading system was designed for the specific application of remotely loading high purity gases into targets for gas-gun driven plate impact experiments. The high purity gases are loaded into well-defined target configurations to obtain Hugoniot states in the gas phase at greater than ambient pressures. The small volume of the gas samples is challenging, as slight changing in the ambient temperature result in measurable pressure changes. Therefore, the ability to load a gas gun target and continually monitor the sample pressure prior to firing provides the most stable and reliable target fielding approach. We present the design and evaluation of a gas loading system built for the LANL 50 mm bore two-stage light gas gun. Targets for the gun are made of 6061 Al or OFHC Cu, and assembled to form a gas containment cell with a volume of approximately 1.38 cc. The compatibility of materials was a major consideration in the design of the system, particularly for its use with corrosive gases. Piping and valves are stainless steel with wetted seals made from Kalrez® and Teflon®. Preliminary testing was completed to ensure proper flow rate and that the proper safety controls were in place. The system has been used to successfully load Ar, Kr, Xe, and anhydrous ammonia with purities of up to 99.999 percent. The design of the system and example data from the plate impact experiments will be shown.

  12. Advanced developments in NiH{sub 2} dependent pressure vessel (DPV) cell and battery technology

    SciTech Connect

    Caldwell, D.B.; Fox, C.L.

    1997-12-01

    The Dependent Pressure Vessel (DPV) Nickel-Hydrogen (NiH{sub 2}) design is being developed by Eagle-Picher Industries, Inc. (EPI) as an advanced battery for military and commercial, aerospace and terrestrial applications. The DPV cell design offers high specific energy and energy density as well as reduced cost, while retaining the established Individual Pressure Vessel (IPV) technology flight heritage and database. This advanced DPV design also offers a more efficient mechanical, electrical and thermal cell and battery configuration and a reduced parts count. The DPV battery design promotes compact, minimum volume packaging and weight efficiency, and delivers cost and weight savings with minimal design risks.

  13. The Mechanism of Phagocytosis: Two Stages of Engulfment

    NASA Astrophysics Data System (ADS)

    Richards, David M.; Endres, Robert G.

    2014-10-01

    Despite being of vital importance to the immune system, the mechanism by which cells engulf relatively large solid particles during phagocytosis is still poorly understood. From movies of neutrophil phagocytosis of polystyrene beads, we measure the fractional engulfment as a function of time and demonstrate that phagocytosis occurs in two distinct stages. During the first stage, engulfment is relatively slow and progressively slows down as phagocytosis proceeds. However, at approximately half-engulfment, the rate of engulfment increases dramatically, with complete engulfment attained soon afterwards. By studying simple mathematical models of phagocytosis, we suggest that the first stage is due to a passive mechanism, determined by receptor diffusion and capture, whereas the second stage is more actively controlled, perhaps with receptors being driven towards the site of engulfment. We then consider a more advanced model that includes signaling and captures both stages of engulfment. This model predicts that there is an optimum ligand density for quick engulfment. Further, we show how this model explains why non-spherical particles engulf quickest when presented tip-first. Our findings suggest that active regulation may be a later evolutionary innovation, allowing fast and robust engulfment even for large particles.

  14. Two stages of dust delivery from satellites to planetary rings

    NASA Astrophysics Data System (ADS)

    Dikarev, Valeri V.; Krivov, Alexander V.; Grün, Eberhard

    2006-08-01

    Faint rings of micrometre-sized dust particles embrace many planets in the Solar system. As a rule, they are replenished by ejecta from embedded atmosphereless moons. On a number of occasions, the ejecta are generated by hypervelocity meteoroid impacts into the moons. Small ejecta fragments are then swiftly shifted into rings by an array of non-gravitational forces, e.g. radiation pressure or plasma drag. A significant fraction of ejecta mass, however, is contained in relatively big, multi-micrometre fragments which are subject to gravity only. Having escaped from the satellite, they stay close to its orbit and form a belt around planet. This belt is itself a source of ring dust through collisional disruption of its particles. Here the contributions of belts to the respective rings are estimated for selected satellites of Jupiter and Saturn. The belts under review could supply substantially more dust to rings than the direct ejecta from satellites and should be taken into account when estimating ring dust budgets. The belts are very difficult to observe, however, and some of them remain a theoretical proposition. We find an appealing evidence for the belts due to Amalthea and Thebe around Jupiter, and for the belt due to Enceladus around Saturn.

  15. Advanced High-Temperature, High-Pressure Transport Reactor Gasification

    SciTech Connect

    Michael L. Swanson

    2005-08-30

    50 hours of gasification on a petroleum coke from the Hunt Oil Refinery and an additional 73 hours of operation on a high-ash coal from India. Data from these tests indicate that while acceptable fuel gas heating value was achieved with these fuels, the transport gasifier performs better on the lower-rank feedstocks because of their higher char reactivity. Comparable carbon conversions have been achieved at similar oxygen/coal ratios for both air-blown and oxygen-blown operation for each fuel; however, carbon conversion was lower for the less reactive feedstocks. While separation of fines from the feed coals is not needed with this technology, some testing has suggested that feedstocks with higher levels of fines have resulted in reduced carbon conversion, presumably due to the inability of the finer carbon particles to be captured by the cyclones. These data show that these low-rank feedstocks provided similar fuel gas heating values; however, even among the high-reactivity low-rank coals, the carbon conversion did appear to be lower for the fuels (brown coal in particular) that contained a significant amount of fines. The fuel gas under oxygen-blown operation has been higher in hydrogen and carbon dioxide concentration since the higher steam injection rate promotes the water-gas shift reaction to produce more CO{sub 2} and H{sub 2} at the expense of the CO and water vapor. However, the high water and CO{sub 2} partial pressures have also significantly reduced the reaction of (Abstract truncated)

  16. Recent advances in lightweight, filament-wound composite pressure vessel technology

    NASA Technical Reports Server (NTRS)

    Lark, R. F.

    1977-01-01

    A review of recent advances is presented for lightweight, high performance composite pressure vessel technology that covers the areas of design concepts, fabrication procedures, applications, and performance of vessels subjected to single cycle burst and cyclic fatigue loading. Filament wound fiber/epoxy composite vessels were made from S glass, graphite, and Kevlar 49 fibers and were equipped with both structural and nonstructural liners. Pressure vessels structural efficiencies were attained which represented weight savings, using different liners, of 40 to 60 percent over all titanium pressure vessels. Significant findings in each area are summarized.

  17. Advanced Computational Thermal Studies and their Assessment for Supercritical-Pressure Reactors (SCRs)

    SciTech Connect

    D. M. McEligot; J. Y. Yoo; J. S. Lee; S. T. Ro; E. Lurien; S. O. Park; R. H. Pletcher; B. L. Smith; P. Vukoslavcevic; J. M. Wallace

    2009-04-01

    The goal of this laboratory / university collaboration of coupled computational and experimental studies is the improvement of predictive methods for supercritical-pressure reactors. The general objective is to develop supporting knowledge needed of advanced computational techniques for the technology development of the concepts and their safety systems.

  18. Two-stage light-gas magnetoplasma accelerator for hypervelocity impact simulation

    NASA Astrophysics Data System (ADS)

    Khramtsov, P. P.; Vasetskij, V. A.; Makhnach, A. I.; Grishenko, V. M.; Chernik, M. Yu; Shikh, I. A.; Doroshko, M. V.

    2016-11-01

    The development of macroparticles acceleration methods for high-speed impact simulation in a laboratory is an actual problem due to increasing of space flights duration and necessity of providing adequate spacecraft protection against micrometeoroid and space debris impacts. This paper presents results of experimental study of a two-stage light- gas magnetoplasma launcher for acceleration of a macroparticle, in which a coaxial plasma accelerator creates a shock wave in a high-pressure channel filled with light gas. Graphite and steel spheres with diameter of 2.5-4 mm were used as a projectile and were accelerated to the speed of 0.8-4.8 km/s. A launching of particle occurred in vacuum. For projectile velocity control the speed measuring method was developed. The error of this metod does not exceed 5%. The process of projectile flight from the barrel and the process of a particle collision with a target were registered by use of high-speed camera. The results of projectile collision with elements of meteoroid shielding are presented. In order to increase the projectile velocity, the high-pressure channel should be filled with hydrogen. However, we used helium in our experiments for safety reasons. Therefore, we can expect that the range of mass and velocity of the accelerated particles can be extended by use of hydrogen as an accelerating gas.

  19. Optimization Study of the Ames 0.5 Two-Stage Light Gas Gun

    NASA Technical Reports Server (NTRS)

    Bogdanoff, D. W.

    1996-01-01

    There is a need for more faithful simulation of space debris impacts on various space vehicles. Space debris impact velocities can range up to 14 km/sec and conventional two-stage light gas guns with moderately heavy saboted projectiles are limited to launch velocities of 7-8 km/sec. Any increases obtained in the launch velocities will result in more faithful simulations of debris impacts. It would also be valuable to reduce the maximum gun and projectile base pressures and the gun barrel erosion rate. In this paper, the results of a computational fluid dynamics (CFD) study designed to optimize the performance of the NASA Ames 0.5' gun by systematically varying seven gun operating parameters are reported. Particularly beneficial effects were predicted to occur if (1) the piston mass was decreased together with the powder mass and the hydrogen fill pressure and (2) the pump tube length was decreased. The optimum set of changes in gun operating conditions were predicted to produce an increase in muzzle velocity of 0.7-1.0 km/sec, simultaneously with a substantial decrease in gun erosion. Preliminary experimental data have validated the code predictions. Velocities of up to 8.2 km/sec with a 0.475 cm diameter saboted aluminum sphere have been obtained, along with large reductions in gun erosion rates.

  20. CFD Modelling of Bore Erosion in Two-Stage Light Gas Guns

    NASA Technical Reports Server (NTRS)

    Bogdanoff, D. W.

    1998-01-01

    A well-validated quasi-one-dimensional computational fluid dynamics (CFD) code for the analysis of the internal ballistics of two-stage light gas guns is modified to explicitly calculate the ablation of steel from the gun bore and the incorporation of the ablated wall material into the hydrogen working cas. The modified code is used to model 45 shots made with the NASA Ames 0.5 inch light gas gun over an extremely wide variety of gun operating conditions. Good agreement is found between the experimental and theoretical piston velocities (maximum errors of +/-2% to +/-6%) and maximum powder pressures (maximum errors of +/-10% with good igniters). Overall, the agreement between the experimental and numerically calculated gun erosion values (within a factor of 2) was judged to be reasonably good, considering the complexity of the processes modelled. Experimental muzzle velocities agree very well (maximum errors of 0.5-0.7 km/sec) with theoretical muzzle velocities calculated with loading of the hydrogen gas with the ablated barrel wall material. Comparison of results for pump tube volumes of 100%, 60% and 40% of an initial benchmark value show that, at the higher muzzle velocities, operation at 40% pump tube volume produces much lower hydrogen loading and gun erosion and substantially lower maximum pressures in the gun. Large muzzle velocity gains (2.4-5.4 km/sec) are predicted upon driving the gun harder (that is, upon using, higher powder loads and/or lower hydrogen fill pressures) when hydrogen loading is neglected; much smaller muzzle velocity gains (1.1-2.2 km/sec) are predicted when hydrogen loading is taken into account. These smaller predicted velocity gains agree well with those achieved in practice. CFD snapshots of the hydrogen mass fraction, density and pressure of the in-bore medium are presented for a very erosive shot.

  1. Experimental Investigation of a Model of a Two-Stage Turboblower

    NASA Technical Reports Server (NTRS)

    Dovjik, s.; Polikovsky, W.

    1943-01-01

    In the present paper an investigation is made of two stages of a multistage turboblower having a vaneless diffuser behind the impeller and guide vanes at the inlet to the nest stage. The method employed was that of investigating the performance of the successive elements of the blower (the impeller, vaneless diffuser, ets.) whereby the kinematics of the flow through the blower could be followed and the pressure at the different points computed. The character of the flow and the physical significance of the loss coefficients could thereby be determined so as to secure the best agreement of the computed with the actual performance of the blower. Since the tests were carried out for various delivery volumes, the dependence of the coefficients on a number of factors (angle of attack, velocities, etc.) could be obtained. The distribution of the losses that occur during the transformation of dynamic pressure at the impeller exit into static pressure could be found and likewise the range within which the friction coefficient varies in the vaneless diffuser. With the aid of factors having a certain physical significance, the centrifugal blower could be computed on the basis of a more or less schematical consideration of the phenomena occuring during the air flow through it, and the use of arbitrary factors and recourse to the geometrical similtude law thus avoided. The present investigation largely summarizes all the previous work af the CHI Blower Section on the different elements of a centrifugal blower. Some considerations on the analysis of model test data for application to full-scale are presented in the appendix.

  2. Management of severe obstructive sleep apnea using mandibular advancement devices with auto continuous positive airway pressures

    PubMed Central

    Upadhyay, Rashmi; Dubey, Abhishek; Kant, Surya; Singh, Balendra Pratap

    2015-01-01

    The use of continuous positive airway pressures (CPAP) is considered standard treatment of moderate to severe obstructive sleep apnea (OSA). Treatment of the disease poses a great challenge not only for its diagnostic purpose but also for its treatment part. In about 29-83% of the patients, treatment is difficult because of non-compliance resulting due to high pressures, air leaks and other related issues. In such situations, alternative methods of treatment need to be looked for so as to ascertain better management. Mandibular advancement devices along with CPAP may show better treatment outcome in specific situations. PMID:25814802

  3. Development of a Two-Stage Mars Ascent Vehicle Using In-Situ Propellant Production

    NASA Technical Reports Server (NTRS)

    Paxton, Laurel; Vaughan, David

    2014-01-01

    Mars Sample Return (MSR) and Mars In-Situ Resource Utilization (ISRU) present two main challenges for the advancement of Mars science. MSR would demonstrate Mars lift-off capability, while ISRU would test the ability to produce fuel and oxidizer using Martian resources, a crucial step for future human missions. A two-stage Mars Ascent Vehicle (MAV) concept was developed to support sample return as well as in-situ propellant production. The MAV would be powered by a solid rocket first stage and a LOX-propane second stage. A liquid second-stage provides higher orbit insertion reliability than a solid second stage as well as a degree of complexity eventually required for manned missions. Propane in particular offers comparable performance to methane without requiring cryogenic storage. The total MAV mass would be 119.9 kg to carry an 11 kg payload to orbit. The feasibility of in-situ fuel and oxidizer production was also examined. Two potential schemes were evaluated for production capability, size and power requirements. The schemes examined utilize CO2 and water as starting blocks to produce LOX and a propane blend. The infrastructure required to fuel and launch the MAV was also explored.

  4. Two-stage seasonal streamflow forecasts to guide water resources decisions and water rights allocation

    NASA Astrophysics Data System (ADS)

    Block, P. J.; Gonzalez, E.; Bonnafous, L.

    2011-12-01

    Decision-making in water resources is inherently uncertain producing copious risks, ranging from operational (present) to planning (season-ahead) to design/adaptation (decadal) time-scales. These risks include human activity and climate variability/change. As the risks in designing and operating water systems and allocating available supplies vary systematically in time, prospects for predicting and managing such risks become increasingly attractive. Considerable effort has been undertaken to improve seasonal forecast skill and advocate for integration to reduce risk, however only minimal adoption is evident. Impediments are well defined, yet tailoring forecast products and allowing for flexible adoption assist in overcoming some obstacles. The semi-arid Elqui River basin in Chile is contending with increasing levels of water stress and demand coupled with insufficient investment in infrastructure, taxing its ability to meet agriculture, hydropower, and environmental requirements. The basin is fed from a retreating glacier, with allocation principles founded on a system of water rights and markets. A two-stage seasonal streamflow forecast at leads of one and two seasons prescribes the probability of reductions in the value of each water right, allowing water managers to inform their constituents in advance. A tool linking the streamflow forecast to a simple reservoir decision model also allows water managers to select a level of confidence in the forecast information.

  5. Electric and hybrid electric vehicles: A technology assessment based on a two-stage Delphi study

    SciTech Connect

    Vyas, A.D.; Ng, H.K.; Santini, D.J.; Anderson, J.L.

    1997-12-01

    To address the uncertainty regarding future costs and operating attributes of electric and hybrid electric vehicles, a two stage, worldwide Delphi study was conducted. Expert opinions on vehicle attributes, current state of the technology, possible advancements, costs, and market penetration potential were sought for the years 2000, 2010, and 2020. Opinions related to such critical components as batteries, electric drive systems, and hybrid vehicle engines, as well as their respective technical and economic viabilities, were also obtained. This report contains descriptions of the survey methodology, analytical approach, and results of the analysis of survey data, together with a summary of other factors that will influence the degree of market success of electric and hybrid electric vehicle technologies. Responses by industry participants, the largest fraction among all the participating groups, are compared with the overall responses. An evaluation of changes between the two Delphi stages is also summarized. An analysis of battery replacement costs for various types is summarized, and variable operating costs for electric and hybrid vehicles are compared with those of conventional vehicles. A market penetration analysis is summarized, in which projected market shares from the survey are compared with predictions of shares on the basis of two market share projection models that use the cost and physical attributes provided by the survey. Finally, projections of market shares beyond the year 2020 are developed by use of constrained logit models of market shares, statistically fitted to the survey data.

  6. Two-stage fan. 4: Performance data for stator setting angle optimization

    NASA Technical Reports Server (NTRS)

    Burger, G. D.; Keenan, M. J.

    1975-01-01

    Stator setting angle optimization tests were conducted on a two-stage fan to improve efficiency at overspeed, stall margin at design speed, and both efficiency and stall margin at partspeed. The fan has a design pressure ratio of 2.8, a flow rate of 184.2 lb/sec (83.55 kg/sec) and a 1st-stage rotor tip speed of 1450 ft/sec (441.96 in/sec). Performance was obtained at 70,100, and 105 percent of design speed with different combinations of 1st-stage and 2nd-stage stator settings. One combination of settings, other than design, was common to all three speeds. At design speed, a 2.0 percentage point increase in stall margin was obtained at the expense of a 1.3 percentage point efficiency decrease. At 105 percent speed, efficiency was improved by 1.8 percentage points but stall margin decreased 4.7 percentage points. At 70 percent speed, no change in stall margin or operating line efficiency was obtained with stator resets although considerable speed-flow requlation occurred.

  7. New higher-order Godunov code for modelling performance of two-stage light gas guns

    NASA Technical Reports Server (NTRS)

    Bogdanoff, D. W.; Miller, R. J.

    1995-01-01

    A new quasi-one-dimensional Godunov code for modeling two-stage light gas guns is described. The code is third-order accurate in space and second-order accurate in time. A very accurate Riemann solver is used. Friction and heat transfer to the tube wall for gases and dense media are modeled and a simple nonequilibrium turbulence model is used for gas flows. The code also models gunpowder burn in the first-stage breech. Realistic equations of state (EOS) are used for all media. The code was validated against exact solutions of Riemann's shock-tube problem, impact of dense media slabs at velocities up to 20 km/sec, flow through a supersonic convergent-divergent nozzle and burning of gunpowder in a closed bomb. Excellent validation results were obtained. The code was then used to predict the performance of two light gas guns (1.5 in. and 0.28 in.) in service at the Ames Research Center. The code predictions were compared with measured pressure histories in the powder chamber and pump tube and with measured piston and projectile velocities. Very good agreement between computational fluid dynamics (CFD) predictions and measurements was obtained. Actual powder-burn rates in the gun were found to be considerably higher (60-90 percent) than predicted by the manufacturer and the behavior of the piston upon yielding appears to differ greatly from that suggested by low-strain rate tests.

  8. Two-stage gas amplifier for ultrahigh resolution low vacuum scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Thiel, B. L.; Toth, M.; Schroemges, R. P. M.; Scholtz, J. J.; van Veen, G.; Knowles, W. R.

    2006-03-01

    We describe a magnetic field assisted, two-stage secondary electron gas amplification process for low vacuum scanning electron microscopy. The field of an ultrahigh resolution magnetic immersion objective lens and the electric field of an annular electrode configuration partition the amplification volume into two regions in which the electric and magnetic fields are parallel and crossed, respectively. The fields confine secondary electrons to axial and radial oscillations within the detector volume, until all of the kinetic energy imparted by an anode is dissipated through inelastic collisions with gas molecules. The electron confinement yields high gas amplification efficiency at short working distances and low gas pressures, facilitating high resolution imaging at low electron beam energies. Charging of insulating specimens is stabilized by positive ions produced in the gas ionization cascade. Furthermore, the signal to background level and bandwidth of this detector are superior to those of earlier generations of environmental secondary electron detectors. The combination of low vacuum, short working distance, and low beam energy is attractive to the semiconductor metrology industry, in particular, for critical dimension measurements on photolithographic masks.

  9. Two-stage gas amplifier for ultrahigh resolution low vacuum scanning electron microscopy

    SciTech Connect

    Thiel, B.L.; Toth, M.; Schroemges, R.P.M.; Scholtz, J.J.; Veen, G. van; Knowles, W.R.

    2006-03-15

    We describe a magnetic field assisted, two-stage secondary electron gas amplification process for low vacuum scanning electron microscopy. The field of an ultrahigh resolution magnetic immersion objective lens and the electric field of an annular electrode configuration partition the amplification volume into two regions in which the electric and magnetic fields are parallel and crossed, respectively. The fields confine secondary electrons to axial and radial oscillations within the detector volume, until all of the kinetic energy imparted by an anode is dissipated through inelastic collisions with gas molecules. The electron confinement yields high gas amplification efficiency at short working distances and low gas pressures, facilitating high resolution imaging at low electron beam energies. Charging of insulating specimens is stabilized by positive ions produced in the gas ionization cascade. Furthermore, the signal to background level and bandwidth of this detector are superior to those of earlier generations of environmental secondary electron detectors. The combination of low vacuum, short working distance, and low beam energy is attractive to the semiconductor metrology industry, in particular, for critical dimension measurements on photolithographic masks.

  10. Catalytic two-stage coal hydrogenation process using extinction recycle of heavy liquid fraction

    DOEpatents

    MacArthur, J.B.; Comolli, A.G.; McLean, J.B.

    1989-10-17

    A process is described for catalytic two-stage hydrogenation and liquefaction of coal with selective extinction recycle of all heavy liquid fractions boiling above a distillation cut point of about 600--750 F to produce increased yields of low-boiling hydrocarbon liquid and gas products. In the process, the particulate coal feed is slurried with a process-derived liquid solvent normally boiling above about 650 F and fed into a first stage catalytic reaction zone operated at conditions which promote controlled rate liquefaction of the coal, while simultaneously hydrogenating the hydrocarbon recycle oils. The first stage reactor is maintained at 710--800 F temperature, 1,000--4,000 psig hydrogen partial pressure, and 10-90 lb/hr per ft[sup 3] catalyst space velocity. Partially hydrogenated material withdrawn from the first stage reaction zone is passed directly to the second stage catalytic reaction zone maintained at 760--860 F temperature for further hydrogenation and hydroconversion reactions. A 600--750 F[sup +] fraction containing 0--20 W % unreacted coal and ash solids is recycled to the coal slurrying step. If desired, the cut point lower boiling fraction can be further catalytically hydrotreated. By this process, the coal feed is successively catalytically hydrogenated and hydroconverted at selected conditions, to provide significantly increased yields of desirable low-boiling hydrocarbon liquid products and minimal production of hydrocarbon gases, and no net production of undesirable heavy oils and residuum materials. 2 figs.

  11. Catalytic two-stage coal hydrogenation process using extinction recycle of heavy liquid fraction

    DOEpatents

    MacArthur, James B.; Comolli, Alfred G.; McLean, Joseph B.

    1989-01-01

    A process for catalytic two-stage hydrogenation and liquefaction of coal with selective extinction recycle of all heavy liquid fractions boiling above a distillation cut point of about 600.degree.-750.degree. F. to produce increased yields of low-boiling hydrocarbon liquid and gas products. In the process, the particulate coal feed is slurried with a process-derived liquid solvent normally boiling above about 650.degree. F. and fed into a first stage catalytic reaction zone operated at conditions which promote controlled rate liquefaction of the coal, while simultaneously hydrogenating the hydrocarbon recycle oils. The first stage reactor is maintained at 710.degree.-800.degree. F. temperature, 1000-4000 psig hydrogen partial pressure, and 10-90 lb/hr per ft.sup.3 catalyst space velocity. Partially hydrogenated material withdrawn from the first stage reaction zone is passed directly to the second stage catalytic reaction zone maintained at 760.degree.-860.degree. F. temperature for further hydrogenation and hydroconversion reactions. A 600.degree.-750.degree. F..sup.+ fraction containing 0-20 W % unreacted coal and ash solids is recycled to the coal slurrying step. If desired, the cut point lower boiling fraction can be further catalytically hydrotreated. By this process, the coal feed is successively catalytically hydrogenated and hydroconverted at selected conditions, to provide significantly increased yields of desirable low-boiling hydrocarbon liquid products and minimal production of hydrocarbon gases, and no net production of undesirable heavy oils and residuum materials.

  12. Removal of cesium from simulated liquid waste with countercurrent two-stage adsorption followed by microfiltration.

    PubMed

    Han, Fei; Zhang, Guang-Hui; Gu, Ping

    2012-07-30

    Copper ferrocyanide (CuFC) was used as an adsorbent to remove cesium. Jar test results showed that the adsorption capacity of CuFC was better than that of potassium zinc hexacyanoferrate. Lab-scale tests were performed by an adsorption-microfiltration process, and the mean decontamination factor (DF) was 463 when the initial cesium concentration was 101.3μg/L, the dosage of CuFC was 40mg/L and the adsorption time was 20min. The cesium concentration in the effluent continuously decreased with the operation time, which indicated that the used adsorbent retained its adsorption capacity. To use this capacity, experiments on a countercurrent two-stage adsorption (CTA)-microfiltration (MF) process were carried out with CuFC adsorption combined with membrane separation. A calculation method for determining the cesium concentration in the effluent was given, and batch tests in a pressure cup were performed to verify the calculated method. The results showed that the experimental values fitted well with the calculated values in the CTA-MF process. The mean DF was 1123 when the dilution factor was 0.4, the initial cesium concentration was 98.75μg/L and the dosage of CuFC and adsorption time were the same as those used in the lab-scale test. The DF obtained by CTA-MF process was more than three times higher than the single-stage adsorption in the jar test.

  13. Advanced Damage Tolerance Analysis of International Space Station Pressure Wall Welds

    NASA Technical Reports Server (NTRS)

    Allen, Phillip A.

    2006-01-01

    EM20/MSFC has sponsored technology in the area of advanced damage tolerance analysis tools used to analyze the International Space Station (ISS) pressure wall welds. The ISS European modules did not receive non-destructive evaluation (NDE) inspection after proof test. In final assembly configuration, most welds could only be inspected from one side, and some welds were uninspectible. Therefore, advanced damage tolerance analysis was required to determine the critical initial flaw sizes and predicted safe life for the pressure wall welds. EM20 sponsored the development of a new finite element tools using FEA-Crack and WARP3D to solve the problem. This presentation gives a brief overview of the new analytical tools and the analysis results.

  14. Adaptive Urban Stormwater Management Using a Two-stage Stochastic Optimization Model

    NASA Astrophysics Data System (ADS)

    Hung, F.; Hobbs, B. F.; McGarity, A. E.

    2014-12-01

    In many older cities, stormwater results in combined sewer overflows (CSOs) and consequent water quality impairments. Because of the expense of traditional approaches for controlling CSOs, cities are considering the use of green infrastructure (GI) to reduce runoff and pollutants. Examples of GI include tree trenches, rain gardens, green roofs, and rain barrels. However, the cost and effectiveness of GI are uncertain, especially at the watershed scale. We present a two-stage stochastic extension of the Stormwater Investment Strategy Evaluation (StormWISE) model (A. McGarity, JWRPM, 2012, 111-24) to explicitly model and optimize these uncertainties in an adaptive management framework. A two-stage model represents the immediate commitment of resources ("here & now") followed by later investment and adaptation decisions ("wait & see"). A case study is presented for Philadelphia, which intends to extensively deploy GI over the next two decades (PWD, "Green City, Clean Water - Implementation and Adaptive Management Plan," 2011). After first-stage decisions are made, the model updates the stochastic objective and constraints (learning). We model two types of "learning" about GI cost and performance. One assumes that learning occurs over time, is automatic, and does not depend on what has been done in stage one (basic model). The other considers learning resulting from active experimentation and learning-by-doing (advanced model). Both require expert probability elicitations, and learning from research and monitoring is modelled by Bayesian updating (as in S. Jacobi et al., JWRPM, 2013, 534-43). The model allocates limited financial resources to GI investments over time to achieve multiple objectives with a given reliability. Objectives include minimizing construction and O&M costs; achieving nutrient, sediment, and runoff volume targets; and community concerns, such as aesthetics, CO2 emissions, heat islands, and recreational values. CVaR (Conditional Value at Risk) and

  15. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

    PubMed

    Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

    2010-02-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness.

  16. Supersonic Test of the 10-Inch Bifurcated Two-Stage Supersonic Inlet (BTSSI)

    NASA Technical Reports Server (NTRS)

    Carlin, C. M.; Frisch, I.; Kolden, J. J.; Koncsek, J. L.; Marrs, K. J.; Mayer, D. W.; McMahon, S. L.; Milligan, K. H.; Sommerfield, D. M.

    2003-01-01

    Experimental results from testing of a novel supersonic inlet model in NASA Glenn Research Center's 10- by 10-foot supersonic wind tunnel are presented. The patented inlet concept, called Two-Stage Supersonic Inlet (TSSI), incorporates a large cavity, or throat slot, in the supersonic diffuser intended to enhance the stability of the normal shock. The present embodiment of the concept is a bifurcated twin-duct) design. During the course of testing an unusual 'semi-started' mode of operation was encountered. The inlet was able to spill up to 30 percent of the captured airstream without fully expelling the normal shock. In this mode, the total pressure recovery dropped approximately 6 percent without increasing steady-state distortion. Dynamic instrumentation at the cowl lip station indicates the semi-start mode may be a series of unstart/restart cycles with frequency ranging from 0.2 to 20 Hz. Engine face total pressure measurements indicate a modest impact due to this event. However, since the current test article does not have a representative subsonic diffuser (and is in fact separated), it is unclear how this mode of operation would effect an engine. Further investigation of this phenomenon is required before it is fully understood. Prior testing of the TSSI concept allowed extension of fully started inlet operation to regions of significantly reduced supply flow without reducing recovery. The test article was a smaller scale than the present test and was a single duct design. In the present test, the expanded range of stable operation with high recovery was not realized.

  17. Partial fuel stratification to control HCCI heat release rates : fuel composition and other factors affecting pre-ignition reactions of two-stage ignition fuels.

    SciTech Connect

    Dec, John E.; Sjoberg, Carl-Magnus G.; Cannella, William; Yang, Yi; Dronniou, Nicolas

    2010-11-01

    Homogeneous charge compression ignition (HCCI) combustion with fully premixed charge is severely limited at high-load operation due to the rapid pressure-rise rates (PRR) which can lead to engine knock and potential engine damage. Recent studies have shown that two-stage ignition fuels possess a significant potential to reduce the combustion heat release rate, thus enabling higher load without knock.

  18. Unsteady blade-surface pressures on a large-scale advanced propeller: Prediction and data

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Groeneweg, J. F.

    1990-01-01

    An unsteady 3-D Euler analysis technique is employed to compute the flow field of an advanced propeller operating at an angle of attack. The predicted blade pressure waveforms are compared with wind tunnel data at two Mach numbers, 0.5 and 0.2. The inflow angle is three degrees. For an inflow Mach number of 0.5, the predicted pressure response is in fair agreement with data: the predicted phases of the waveforms are in close agreement with data while the magnitudes are underpredicted. At the low Mach number of 0.2 (takeoff), the numerical solution shows the formation of a leading edge vortex which is in qualitative agreement with measurements. However, the highly nonlinear pressure response measured on the blade suction surface is not captured in the present inviscid analysis.

  19. Unsteady blade surface pressures on a large-scale advanced propeller - Prediction and data

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Groeneweg, J. F.

    1990-01-01

    An unsteady three dimensional Euler analysis technique is employed to compute the flowfield of an advanced propeller operating at an angle of attack. The predicted blade pressure waveforms are compared with wind tunnel data at two Mach numbers, 0.5 and 0.2. The inflow angle is three degrees. For an inflow Mach number of 0.5, the predicted pressure response is in fair agreement with data: the predicted phases of the waveforms are in close agreement with data while the magnitudes are underpredicted. At the low Mach number of 0.2 (take-off) the numerical solution shows the formation of a leading edge vortex which is in qualitative agreement with measurements. However, the highly nonlinear pressure response measured on the blade suction surface is not captured in the present inviscid analysis.

  20. Recent advances in lightweight, filament-wound composite pressure vessel technology

    NASA Technical Reports Server (NTRS)

    Lark, R. F.

    1977-01-01

    A review of recent advances is presented for lightweight, high-performance composite pressure vessel technology that covers the areas of design concepts, fabrication procedures, applications, and performance of vessels subjected to single-cycle burst and cyclic fatigue loading. Filament-wound fiber/epoxy composite vessels were made from S-glass, graphite, and Kevlar 49 fibers and were equipped with both structural and nonstructural liners. Pressure vessel structural efficiencies were attained which represented weight savings, using different liners, of 40 to 60 percent over all-titanium pressure vessels. Significant findings in each area are summarized including data from current NASA-Lewis Research Center contractual and in-house programs.

  1. Advanced Computational Modeling of Vapor Deposition in a High-pressure Reactor

    NASA Technical Reports Server (NTRS)

    Cardelino, Beatriz H.; Moore, Craig E.; McCall, Sonya D.; Cardelino, Carlos A.; Dietz, Nikolaus; Bachmann, Klaus

    2004-01-01

    In search of novel approaches to produce new materials for electro-optic technologies, advances have been achieved in the development of computer models for vapor deposition reactors in space. Numerical simulations are invaluable tools for costly and difficult processes, such as those experiments designed for high pressures and microgravity conditions. Indium nitride is a candidate compound for high-speed laser and photo diodes for optical communication system, as well as for semiconductor lasers operating into the blue and ultraviolet regions. But InN and other nitride compounds exhibit large thermal decomposition at its optimum growth temperature. In addition, epitaxy at lower temperatures and subatmospheric pressures incorporates indium droplets into the InN films. However, surface stabilization data indicate that InN could be grown at 900 K in high nitrogen pressures, and microgravity could provide laminar flow conditions. Numerical models for chemical vapor deposition have been developed, coupling complex chemical kinetics with fluid dynamic properties.

  2. Advanced Computational Modeling of Vapor Deposition in a High-Pressure Reactor

    NASA Technical Reports Server (NTRS)

    Cardelino, Beatriz H.; Moore, Craig E.; McCall, Sonya D.; Cardelino, Carlos A.; Dietz, Nikolaus; Bachmann, Klaus

    2004-01-01

    In search of novel approaches to produce new materials for electro-optic technologies, advances have been achieved in the development of computer models for vapor deposition reactors in space. Numerical simulations are invaluable tools for costly and difficult processes, such as those experiments designed for high pressures and microgravity conditions. Indium nitride is a candidate compound for high-speed laser and photo diodes for optical communication system, as well as for semiconductor lasers operating into the blue and ultraviolet regions. But InN and other nitride compounds exhibit large thermal decomposition at its optimum growth temperature. In addition, epitaxy at lower temperatures and subatmospheric pressures incorporates indium droplets into the InN films. However, surface stabilization data indicate that InN could be grown at 900 K in high nitrogen pressures, and microgravity could provide laminar flow conditions. Numerical models for chemical vapor deposition have been developed, coupling complex chemical kinetics with fluid dynamic properties.

  3. Numerical analysis of flow interaction of turbine system in two-stage turbocharger of internal combustion engine

    NASA Astrophysics Data System (ADS)

    Liu, Y. B.; Zhuge, W. L.; Zhang, Y. J.; Zhang, S. Y.

    2016-05-01

    To reach the goal of energy conservation and emission reduction, high intake pressure is needed to meet the demand of high power density and high EGR rate for internal combustion engine. Present power density of diesel engine has reached 90KW/L and intake pressure ratio needed is over 5. Two-stage turbocharging system is an effective way to realize high compression ratio. Because turbocharging system compression work derives from exhaust gas energy. Efficiency of exhaust gas energy influenced by design and matching of turbine system is important to performance of high supercharging engine. Conventional turbine system is assembled by single-stage turbocharger turbines and turbine matching is based on turbine MAP measured on test rig. Flow between turbine system is assumed uniform and value of outlet physical quantities of turbine are regarded as the same as ambient value. However, there are three-dimension flow field distortion and outlet physical quantities value change which will influence performance of turbine system as were demonstrated by some studies. For engine equipped with two-stage turbocharging system, optimization of turbine system design will increase efficiency of exhaust gas energy and thereby increase engine power density. However flow interaction of turbine system will change flow in turbine and influence turbine performance. To recognize the interaction characteristics between high pressure turbine and low pressure turbine, flow in turbine system is modeled and simulated numerically. The calculation results suggested that static pressure field at inlet to low pressure turbine increases back pressure of high pressure turbine, however efficiency of high pressure turbine changes little; distorted velocity field at outlet to high pressure turbine results in swirl at inlet to low pressure turbine. Clockwise swirl results in large negative angle of attack at inlet to rotor which causes flow loss in turbine impeller passages and decreases turbine

  4. DEVELOPMENT OF COLD CLIMATE HEAT PUMP USING TWO-STAGE COMPRESSION

    SciTech Connect

    Shen, Bo; Rice, C Keith; Abdelaziz, Omar; Shrestha, Som S

    2015-01-01

    This paper uses a well-regarded, hardware based heat pump system model to investigate a two-stage economizing cycle for cold climate heat pump applications. The two-stage compression cycle has two variable-speed compressors. The high stage compressor was modelled using a compressor map, and the low stage compressor was experimentally studied using calorimeter testing. A single-stage heat pump system was modelled as the baseline. The system performance predictions are compared between the two-stage and single-stage systems. Special considerations for designing a cold climate heat pump are addressed at both the system and component levels.

  5. Design considerations for single-stage and two-stage pneumatic pellet injectors

    SciTech Connect

    Gouge, M.J.; Combs, S.K.; Fisher, P.W.; Milora, S.L.

    1988-09-01

    Performance of single-stage pneumatic pellet injectors is compared with several models for one-dimensional, compressible fluid flow. Agreement is quite good for models that reflect actual breech chamber geometry and incorporate nonideal effects such as gas friction. Several methods of improving the performance of single-stage pneumatic pellet injectors in the near term are outlined. The design and performance of two-stage pneumatic pellet injectors are discussed, and initial data from the two-stage pneumatic pellet injector test facility at Oak Ridge National Laboratory are presented. Finally, a concept for a repeating two-stage pneumatic pellet injector is described. 27 refs., 8 figs., 3 tabs.

  6. Comparison of classical and two-stage methods of Barkhausen noise measurement

    NASA Astrophysics Data System (ADS)

    Pal'a, Jozef; Bydžovský, Jan

    2014-07-01

    The purpose of the article was to investigate properties of the two-stage methods of the Barkhausen noise (BN) measurement used in non-destructive testing. The principle of the two-stage method is based on subtraction of two successive instances of the electromotive force (EMF) signal with the same non-stochastic (continuous) component. The subtraction can be accomplished in a hardware (hardware two-stage method) or in a software (software two-stage method). The experiments proved that, with these methods, we are able to significantly suppress the dominant continuous component from the induced EMF signal without using filters and thus simplify the measurement. On the other hand, with the classical one-stage method, to achieve similar suppression of the continuous component and, simultaneously, to not suppress the BN, it was necessary to adjust the cut-off frequency of the high-pass filter.

  7. An adaptive two-stage sequential design for sampling rare and clustered populations

    USGS Publications Warehouse

    Brown, J.A.; Salehi, M.M.; Moradi, M.; Bell, G.; Smith, D.R.

    2008-01-01

    How to design an efficient large-area survey continues to be an interesting question for ecologists. In sampling large areas, as is common in environmental studies, adaptive sampling can be efficient because it ensures survey effort is targeted to subareas of high interest. In two-stage sampling, higher density primary sample units are usually of more interest than lower density primary units when populations are rare and clustered. Two-stage sequential sampling has been suggested as a method for allocating second stage sample effort among primary units. Here, we suggest a modification: adaptive two-stage sequential sampling. In this method, the adaptive part of the allocation process means the design is more flexible in how much extra effort can be directed to higher-abundance primary units. We discuss how best to design an adaptive two-stage sequential sample. ?? 2008 The Society of Population Ecology and Springer.

  8. Thermodynamic Analysis and Optimization Based on Exergy Flow for a Two-Staged Pulse Tube Refrigerator

    DTIC Science & Technology

    2010-01-01

    model is convenient for thermodynamic analysis and optimization and shows the important characteristics of two-stage PTRs. Exergy comes into the system ...THERMODYNAMIC ANALYSIS AND OPTIMIZATION BASED ON EXERGY FLOW FOR A TWOSTAGED PULSE TUBE REFRIGERATOR A. Razani, T. Fraser, C. Dodson, and T. Roberts...Prescribed by ANSI Std Z39-18 THERMODYNAMIC ANALYSIS AND OPTIMIZATION BASED ON EXERGY FLOW FOR A TWO-STAGED PULSE TUBE REFRIGERATOR A. Razani 1,3

  9. Two-stage Revision for Periprosthetic Hip and Knee Joint Infections

    PubMed Central

    Kini, Sunil Gurpur; Gabr, Ayman; Das, Rishi; Sukeik, Mohamed; Haddad, Fares Sami

    2016-01-01

    Background: Periprosthetic joint infection (PJI) continues to be one of the leading causes of failure following hip and knee surgery. The diagnostic workflow of PJI includes detailed clinical examination, serum markers, imaging and aspiration/biopsy of the affected joint. The goals of treatment are eradication of the infection, alleviation of pain, and restoration of joint function. Surgical management of PJI consists of debridement, antibiotics and implant retention (DAIR) and single or two-stage revision procedures. Two-stage revision remains the gold standard for treatment of PJIs. We aim to discuss the two stage procedure in this article and report the outcomes. Methods: The first stage of the two stages consists of removal of all components and associated cement with aggressive debridement and placement of an antibiotic-loaded cement spacer. Patients are then treated with variable periods of parenteral antibiotics, followed by an antibiotic free period to help ensure the infection has been eradicated. If the clinical evaluation and serum inflammatory markers suggest infection control, then the second stage can be undertaken and this involves removal of the cement spacer, repeat debridement, and placement of a new prosthesis. Results: Common themes around the two-stage revision procedure include timing of the second stage, antibiotics used in the interim period, length of the interim period before consideration of reimplantation and close liaising with microbiologists. Conclusion: Successful eradication of infection and good functional outcome using the two stage procedure is dependent on a multidisciplinary approach and having a standard reproducible startegy. PMID:28144371

  10. Including sampling and phenotyping costs into the optimization of two stage designs for genomewide association studies.

    PubMed

    Müller, Hans-Helge; Pahl, Roman; Schäfer, Helmut

    2007-12-01

    We propose optimized two-stage designs for genome-wide case-control association studies, using a hypothesis testing paradigm. To save genotyping costs, the complete marker set is genotyped in a sub-sample only (stage I). On stage II, the most promising markers are then genotyped in the remaining sub-sample. In recent publications, two-stage designs were proposed which minimize the overall genotyping costs. To achieve full design optimization, we additionally include sampling costs into both the cost function and the design optimization. The resulting optimal designs differ markedly from those optimized for genotyping costs only (partially optimized designs), and achieve considerable further cost reductions. Compared with partially optimized designs, fully optimized two-stage designs have higher first-stage sample proportion. Furthermore, the increment of the sample size over the one-stage design, which is necessary in two-stage designs in order to compensate for the loss of power due to partial genotyping, is less pronounced for fully optimized two-stage designs. In addition, we address the scenario where the investigator is interested to gain as much information as possible, however is restricted in terms of a budget. In that we develop two-stage designs that maximize the power under a certain cost constraint.

  11. Neuroscience and approach/avoidance personality traits: a two stage (valuation-motivation) approach.

    PubMed

    Corr, Philip J; McNaughton, Neil

    2012-11-01

    Many personality theories link specific traits to the sensitivities of the neural systems that control approach and avoidance. But there is no consensus on the nature of these systems. Here we combine recent advances in economics and neuroscience to provide a more solid foundation for a neuroscience of approach/avoidance personality. We propose a two-stage integration of valuation (loss/gain) sensitivities with motivational (approach/avoidance/conflict) sensitivities. Our key conclusions are: (1) that valuation of appetitive and aversive events (e.g. gain and loss as studied by behavioural economists) is an independent perceptual input stage--with the economic phenomenon of loss aversion resulting from greater negative valuation sensitivity compared to positive valuation sensitivity; (2) that valuation of an appetitive stimulus then interacts with a contingency of presentation or omission to generate a motivational 'attractor' or 'repulsor', respectively (vice versa for an aversive stimulus); (3) the resultant behavioural tendencies to approach or avoid have distinct sensitivities to those of the valuation systems; (4) while attractors and repulsors can reinforce new responses they also, more usually, elicit innate or previously conditioned responses and so the perception/valuation-motivation/action complex is best characterised as acting as a 'reinforcer' not a 'reinforcement'; and (5) approach-avoidance conflict must be viewed as activating a third motivation system that is distinct from the basic approach and avoidance systems. We provide examples of methods of assessing each of the constructs within approach-avoidance theories and of linking these constructs to personality measures. We sketch a preliminary five-element reinforcer sensitivity theory (RST-5) as a first step in the integration of existing specific approach-avoidance theories into a coherent neuroscience of personality.

  12. Investigation on the two-stage active magnetic regenerative refrigerator for liquefaction of hydrogen

    SciTech Connect

    Park, Inmyong; Park, Jiho; Jeong, Sangkwon; Kim, Youngkwon

    2014-01-29

    An active magnetic regenerative refrigerator (AMRR) is expected to be useful for hydrogen liquefaction due to its inherent high thermodynamic efficiency. Because the temperature of the cold end of the refrigerator has to be approximately liquid temperature, a large temperature span of the active magnetic regenerator (AMR) is indispensable when the heat sink temperature is liquid nitrogen temperature or higher. Since magnetic refrigerants are only effective in the vicinity of their own transition temperatures, which limit the temperature span of the AMR, an innovative structure is needed to increase the temperature span. The AMR must be a layered structure and the thermophysical matching of magnetic field and flow convection effects is very important. In order to design an AMR for liquefaction of hydrogen, the implementation of multi-layered AMR with different magnetic refrigerants is explored with multi-staging. In this paper, the performance of the multi-layered AMR using four rare-earth compounds (GdNi{sub 2}, Gd{sub 0.1}Dy{sub 0.9}Ni{sub 2}, Dy{sub 0.85}Er{sub 0.15}Al{sub 2}, Dy{sub 0.5}Er{sub 0.5}Al{sub 2}) is investigated. The experimental apparatus includes two-stage active magnetic regenerator containing two different magnetic refrigerants each. A liquid nitrogen reservoir connected to the warm end of the AMR maintains the temperature of the warm end around 77 K. High-pressure helium gas is employed as a heat transfer fluid in the AMR and the maximum magnetic field of 4 T is supplied by the low temperature superconducting (LTS) magnet. The temperature span with the variation of parameters such as phase difference between magnetic field and mass flow rate of magnetic refrigerants in AMR is investigated. The maximum temperature span in the experiment is recorded as 50 K and several performance issues have been discussed in this paper.

  13. End-wall boundary layer measurements in a two-stage fan

    NASA Technical Reports Server (NTRS)

    Ball, C. L.; Reid, L.; Schmidt, J. F.

    1983-01-01

    Detailed flow measurements made in the casing boundary layer of a two-stage transonic fan are summarized. These measurements were taken at stations upstream of the fan, between all blade rows, and downstream of the last blade row. At the design tip speed of 429 m/sec the fan achieved a peak efficiency of 0.846 at a pressure ratio of 2.471. The boundary layer data were obtained at three weight flows at the design speed: one near choke flow, one near peak efficiency, and one near stall. Conventional boundary layer parameters were calculated from the data measured at each measuring station for each of the three flows. A classical two dimensional casing boundary layer was measured at the fan inlet and extended inward to approximately 15 percent of span. A highly three dimensional boundary layer was measured at the exit of each blade row and extended inward to approximately 10 percent of span. The steep radial gradient of axial velocity noted at the exit of the rotors was reduced substantially as the flow passed through the stators. This reduced gradient is attributed to flow mixing. The amount of flow mixing was reflected in the radial redistribution of total temperature as the flow passed through the stators. The data also show overturning of the tip flow at the stator exits that is consistent with the expected effect of the secondary flow field. The blockage factors calculated from the measured data show an increase in blockage across the rotors and a decrease across the stators.

  14. A two-stage adaptive stochastic collocation method on nested sparse grids for multiphase flow in randomly heterogeneous porous media

    NASA Astrophysics Data System (ADS)

    Liao, Qinzhuo; Zhang, Dongxiao; Tchelepi, Hamdi

    2017-02-01

    A new computational method is proposed for efficient uncertainty quantification of multiphase flow in porous media with stochastic permeability. For pressure estimation, it combines the dimension-adaptive stochastic collocation method on Smolyak sparse grids and the Kronrod-Patterson-Hermite nested quadrature formulas. For saturation estimation, an additional stage is developed, in which the pressure and velocity samples are first generated by the sparse grid interpolation and then substituted into the transport equation to solve for the saturation samples, to address the low regularity problem of the saturation. Numerical examples are presented for multiphase flow with stochastic permeability fields to demonstrate accuracy and efficiency of the proposed two-stage adaptive stochastic collocation method on nested sparse grids.

  15. A CFD Analysis of Steam Flow in the Two-Stage Experimental Impulse Turbine with the Drum Rotor Arrangement

    NASA Astrophysics Data System (ADS)

    Yun, Kukchol; Tajč, L.; Kolovratník, M.

    2016-03-01

    The aim of the paper is to present the CFD analysis of the steam flow in the two-stage turbine with a drum rotor and balancing slots. The balancing slot is a part of every rotor blade and it can be used in the same way as balancing holes on the classical rotor disc. The main attention is focused on the explanation of the experimental knowledge about the impact of the slot covering and uncovering on the efficiency of the individual stages and the entire turbine. The pressure and temperature fields and the mass steam flows through the shaft seals, slots and blade cascades are calculated. The impact of the balancing slots covering or uncovering on the reaction and velocity conditions in the stages is evaluated according to the pressure and temperature fields. We have also concentrated on the analysis of the seal steam flow through the balancing slots. The optimized design of the balancing slots has been suggested.

  16. TRAC-PF1: an advanced best-estimate computer program for pressurized water reactor analysis

    SciTech Connect

    Liles, D.R.; Mahaffy, J.H.

    1984-02-01

    The Transient Reactor Analysis Code (TRAC) is being developed at the Los Alamos National Laboratory to provide advanced best-estimate predictions of postulated accidents in light water reactors. The TRAC-PF1 program provides this capability for pressurized water reactors and for many thermal-hydraulic experimental facilities. The code features either a one-dimensional or a three-dimensional treatment of the pressure vessel and its associated internals; a two-phase, two-fluid nonequilibrium hydrodynamics model with a noncondensable gas field; flow-regime-dependent constitutive equation treatment; optional reflood tracking capability for both bottom flood and falling-film quench fronts; and consistent treatment of entire accident sequences including the generation of consistent initial conditions. This report describes the thermal-hydraulic models and the numerical solution methods used in the code. Detailed programming and user information also are provided.

  17. High Pressure Research in the Large-Volume Press at the Advanced Photon Source

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Shen, G.

    2013-05-01

    We present an overview of current status of high-pressure research using large-volume presses (LVP) at both GSECARS (Sector 13) and HPCAT (Sector 16) at the third-generation synchrotron facility of the Advanced Photon Source (APS), Argonne National Laboratory. These combined facilities provide a wide range of research capabilities for the high pressure community. The 230 ton Paris-Edinburgh device (jointly developed by HPCAT and GSECARS, with partial support from COMPRES) at the bending magnet (BM) beamline 16-BM-B has been used primarily for studies on liquids and glasses. We use the multi-angle energy-dispersive diffraction technique to probe structures of non-crystalline materials, and ultrasonic and falling sphere techniques to measure elasticity and viscosity of these materials. These capabilities allow us to examine the close link between structure and physical properties of non-crystalline metarials. The 1000 ton system at the insertion device (ID) beamline 13-ID-D is used extensively for acoustic velocity measurement for solids and melts. The newly developed DDIA-30 module, when used in a double-stage apparatus with sintered diamond anvils, can generate pressures in excess of 40 GPa routinely. DDIA-30 can also be used as a deformation device for larger samples or higher pressure experiments. The 250 ton system at beamline 13-BM-D as just been upgraded and can accommodate a variety of LVP techniques. Among them the D-DIA and the high-pressure x-ray tomography microscope (HPXTM) are at high demand. The D-DIA has been used for deformation at mantle conditions in both ductile and brittle regime, with acoustic emission detection. The HPXTM has been used to study volumetric properties of glasses and melts as well as 3D microstructure imaging under pressure. Latest scientific results will be highlighted.

  18. High-pressure hydrogen testing of single crystal superalloys for advanced rocket engine turbopump turbine blades

    NASA Technical Reports Server (NTRS)

    Parr, R. A.; Alter, W. S.; Johnston, M. H.; Strizak, J. P.

    1985-01-01

    A screening program to determine the effects of high pressure hydrogen on selected candidate materials for advanced single crystal turbine blade applications is examined. The alloys chosen for the investigation are CM SX-2, CM SX-4C, Rene N-4, and PWA1480. Testing is carried out in hydrogen and helium at 34 MPa and room temperature, with both notched and unnotched single crystal specimens. Results show a significant variation in susceptibility to Hydrogen Environment Embrittlement (HEE) among the four alloys and a marked difference in fracture topography between hydrogen and helium environment specimens.

  19. High-pressure hydrogen testing of single crystal superalloys for advanced rocket engine turbopump turbine blades

    NASA Technical Reports Server (NTRS)

    Alter, W. S.; Parr, R. A.; Johnston, M. H.; Strizak, J. P.

    1984-01-01

    A screening program to determine the effects of high pressure hydrogen on selected candidate materials for advanced single crystal turbine blade applications is examined. The alloys chosen for the investigation are CM SX-2, CM SX-4C, Rene N-4, and PWA1480. Testing is carried out in hydrogen and helium at 34 MPa and room temperature, with both notched and unnotched single crystal specimens. Results show a significant variation in susceptibility to Hydrogen Environment Embrittlement (HEE) among the four alloys and a marked difference in fracture topography between hydrogen and helium environment specimens.

  20. Advanced turboprop wing installation effects measured by unsteady blade pressure and noise

    NASA Technical Reports Server (NTRS)

    Heidelberg, Laurence J.; Woodward, Richard P.

    1987-01-01

    A single rotation model propeller (SR-7A) was tested at simulated takeoff/approach conditions (Mach 0.2), in the NASA Lewis 9- by 15-Ft Anechoic Wind Tunnel. Both unsteady blade surface pressures and noise measurements were made for a tractor configuration with propeller/straight wing and propeller alone configurations. The angle between the wing chord and propeller axis (droop angle) was varied along with the wing angle of attack to determine the effects on noise and unsteady loading. A method was developed that uses unsteady blade pressure measurements to provide a quantitative indication of propeller inflow conditions, at least for a uniform (across the propeller disk) inflow angle. The wing installation caused a nearly uniform upwash at the propeller inlet as evidenced by the domination of the pressure spectra by the first shaft order. This inflow angle increased at a rate of almost 150 percent of that of the wing angle-of-attack for a propeller-wing spacing of 0.54 wing chords at a constant droop angle. The flyover noise, as measured by the maximum blade passing frequency level, correlates closely with the propeller inflow angle (approx. 0.6 dB per degree of inflow angle) for all droop angles and wing angles of attack tested, including the propeller alone data. Large changes in the unsteady pressure responses on the suction surface of the blade were observed as the advance ratio was varied. The presence of a leading edge vortex may explain this behavior since changes in the location of this vortex would change with loading (advance ratio).

  1. New LANL Group M-7 two-stage gun: Double-diaphragm and wrap-around gas breech

    SciTech Connect

    Sheffield, S.A.; Martinez, A.R.

    1992-01-01

    A new two-stage gun is being installed in a high explosive testing facility at Los Alamos National Laboratory for the purpose of subjecting insensitive high explosives to controlled projectile impacts so that shock-to-detonation transition can be studied in detail. This gun has been patterned after guns designed by Alois Stilp at Ernst Mach Institut (EMI) in Freiburg and Wintersweiler, Germany. Several changes were made to adapt the design to our needs. The gun has a 100-mm diameter pump tube and 33-mm and 50-mm diameter launch tubes; both pump and launch tubes are 7.6 m long. We plan to use only helium as the reservoir gas. Large hydraulic clamps hold the gun together in three places during a shot; these are located on both sides of the transition section and at the breech. These clamps make gun conversions to different setups relatively simple, i.e., the two-stage gun can be converted into a single-stage gun. A gas breech has been designed which can be operated in either wrap-around or double-diaphragm mode with a maximum operating pressure of 15,000 psi. Two-stage gun calculations indicate that in the gas breech configuration, projectile velocities up to 4 km/s can be obtained using helium in both the breech and the reservoir. The gun has been fabricated and is being installed at the present time. Testing is expected to begin in early 1993 if the startup difficulties do not become excessive.

  2. New LANL Group M-7 two-stage gun: Double-diaphragm and wrap-around gas breech

    SciTech Connect

    Sheffield, S.A.; Martinez, A.R.

    1992-10-01

    A new two-stage gun is being installed in a high explosive testing facility at Los Alamos National Laboratory for the purpose of subjecting insensitive high explosives to controlled projectile impacts so that shock-to-detonation transition can be studied in detail. This gun has been patterned after guns designed by Alois Stilp at Ernst Mach Institut (EMI) in Freiburg and Wintersweiler, Germany. Several changes were made to adapt the design to our needs. The gun has a 100-mm diameter pump tube and 33-mm and 50-mm diameter launch tubes; both pump and launch tubes are 7.6 m long. We plan to use only helium as the reservoir gas. Large hydraulic clamps hold the gun together in three places during a shot; these are located on both sides of the transition section and at the breech. These clamps make gun conversions to different setups relatively simple, i.e., the two-stage gun can be converted into a single-stage gun. A gas breech has been designed which can be operated in either wrap-around or double-diaphragm mode with a maximum operating pressure of 15,000 psi. Two-stage gun calculations indicate that in the gas breech configuration, projectile velocities up to 4 km/s can be obtained using helium in both the breech and the reservoir. The gun has been fabricated and is being installed at the present time. Testing is expected to begin in early 1993 if the startup difficulties do not become excessive.

  3. Development of a replacement for trichloroethylene in the two-stage cleaning process

    SciTech Connect

    Harding, W.B.

    1992-12-01

    A solvent was sought to replace trichloroethylene in the two-stage cleaning process that is used in the Allied-Signal Inc., Kansas City Division (KCD) Miniature Electro-Mechanical Assembly Department. The process is an ultrasonic cleaning process in which product is first cleaned in trichloroethylene and then in isopropyl alcohol. After a general review of the properties of available solvents, isopropyl alcohol, d-limonene, and a synthetic mineral spirits, were chosen to be evaluated as trichloroethylene replacements. Stainless steel test panels were cleaned and then soiled with several different organic materials. Certain of the panels were cleaned by the two-stage process. The others were cleaned by the two-stage process using one or another of the solvents under evaluation in the place of the trichloroethylene. The cleanliness of the panels was determined by Auger and photoelectron spectroscopy. The panels cleaned with any of the three solvents under evaluation were found to be as clean as those cleaned by the standard two-stage process. Because of simplicity and minimization of inventory, it is recommended that the two-stage process be changed to use isopropyl alcohol in both stages.

  4. Application of acidic thermal treatment for one- and two-stage anaerobic digestion of sewage sludge.

    PubMed

    Takashima, M; Tanaka, Y

    2010-01-01

    The effectiveness of acidic thermal treatment (ATT) was examined in a 106-day continuous experiment, when applied to one- or two-stage anaerobic digestion of sewage sludge (4.3% TS). The ATT was performed at 170 °C and pH 5 for 1 hour (sulfuric acid for lowering pH). The one-stage process was mesophilic at 20 days hydraulic retention time (HRT), and incorporated the ATT as pre-treatment. The two-stage process consisted of a thermophilic digester at 5 days HRT and a mesophilic digester at 15 days HRT, and incorporated the ATT as interstage-treatment. On average, VSS reduction was 48.7% for the one-stage control, 65.8% for the one-stage ATT, 52.7% for the two-stage control and 67.6% for the two-stage ATT. Therefore, VSS reduction was increased by 15-17%, when the ATT was combined in both one- and two-stage processes. In addition, the dewaterability of digested sludge was remarkably improved, and phosphate release was enhanced. On the other hand, total methane production did not differ significantly, and color generation was noted in the digested sludge solutions with the ATT. In conclusion, the anaerobic digestion with ATT can be an attractive alternative for sludge reduction, handling, and phosphorus recovery.

  5. Accuracy of the One-Stage and Two-Stage Impression Techniques: A Comparative Analysis.

    PubMed

    Jamshidy, Ladan; Mozaffari, Hamid Reza; Faraji, Payam; Sharifi, Roohollah

    2016-01-01

    Introduction. One of the main steps of impression is the selection and preparation of an appropriate tray. Hence, the present study aimed to analyze and compare the accuracy of one- and two-stage impression techniques. Materials and Methods. A resin laboratory-made model, as the first molar, was prepared by standard method for full crowns with processed preparation finish line of 1 mm depth and convergence angle of 3-4°. Impression was made 20 times with one-stage technique and 20 times with two-stage technique using an appropriate tray. To measure the marginal gap, the distance between the restoration margin and preparation finish line of plaster dies was vertically determined in mid mesial, distal, buccal, and lingual (MDBL) regions by a stereomicroscope using a standard method. Results. The results of independent test showed that the mean value of the marginal gap obtained by one-stage impression technique was higher than that of two-stage impression technique. Further, there was no significant difference between one- and two-stage impression techniques in mid buccal region, but a significant difference was reported between the two impression techniques in MDL regions and in general. Conclusion. The findings of the present study indicated higher accuracy for two-stage impression technique than for the one-stage impression technique.

  6. Accuracy of the One-Stage and Two-Stage Impression Techniques: A Comparative Analysis

    PubMed Central

    Jamshidy, Ladan; Faraji, Payam; Sharifi, Roohollah

    2016-01-01

    Introduction. One of the main steps of impression is the selection and preparation of an appropriate tray. Hence, the present study aimed to analyze and compare the accuracy of one- and two-stage impression techniques. Materials and Methods. A resin laboratory-made model, as the first molar, was prepared by standard method for full crowns with processed preparation finish line of 1 mm depth and convergence angle of 3-4°. Impression was made 20 times with one-stage technique and 20 times with two-stage technique using an appropriate tray. To measure the marginal gap, the distance between the restoration margin and preparation finish line of plaster dies was vertically determined in mid mesial, distal, buccal, and lingual (MDBL) regions by a stereomicroscope using a standard method. Results. The results of independent test showed that the mean value of the marginal gap obtained by one-stage impression technique was higher than that of two-stage impression technique. Further, there was no significant difference between one- and two-stage impression techniques in mid buccal region, but a significant difference was reported between the two impression techniques in MDL regions and in general. Conclusion. The findings of the present study indicated higher accuracy for two-stage impression technique than for the one-stage impression technique. PMID:28003824

  7. Drinking water treatment of priority pesticides using low pressure UV photolysis and advanced oxidation processes.

    PubMed

    Sanches, Sandra; Barreto Crespo, Maria T; Pereira, Vanessa J

    2010-03-01

    This study reports the efficiency of low pressure UV photolysis for the degradation of pesticides identified as priority pollutants by the European Water Framework Directive 2000/60/EC. Direct low pressure UV photolysis and advanced oxidation processes (using hydrogen peroxide and titanium dioxide) experiments were conducted in laboratory grade water, surface water, and groundwater. LP direct photolysis using a high UV fluence (1500 mJ/cm(2)) was found to be extremely efficient to accomplish the degradation of all pesticides except isoproturon, whereas photolysis using hydrogen peroxide and titanium dioxide did not significantly enhance their removal. In all matrices tested the experimental photolysis of the pesticides followed the same trend: isoproturon degradation was negligible, alachlor, pentachlorophenol, and atrazine showed similar degradation rate constants, whereas diuron and chlorfenvinphos were highly removed. The degradation trend observed for the selected compounds followed the decadic molar absorption coefficients order with exception of isoproturon probably due to its extremely low quantum yield. Similar direct photolysis rate constants were obtained for each pesticide in the different matrices tested, showing that the water components did not significantly impact degradation. Extremely similar photolysis rate constants were also obtained in surface water for individual compounds when compared to mixtures. The model fluence and time-based rate constants reported were very similar to the direct photolysis experimental results obtained, while overestimating the advanced oxidation results. This model was used to predict how degradation of isoproturon, the most resilient compound, could be improved.

  8. Effects of earthworm casts and zeolite on the two-stage composting of green waste.

    PubMed

    Zhang, Lu; Sun, Xiangyang

    2015-05-01

    Because it helps protect the environment and encourages economic development, composting has become a viable method for organic waste disposal. The objective of this study was to investigate the effects of earthworm casts (EWCs) (at 0.0%, 0.30%, and 0.60%) and zeolite (clinoptilolite, CL) (at 0%, 15%, and 25%) on the two-stage composting of green waste. The combination of EWCs and CL improved the conditions of the composting process and the quality of the compost products in terms of the thermophilic phase, humification, nitrification, microbial numbers and enzyme activities, the degradation of cellulose and hemicellulose, and physico-chemical characteristics and nutrient contents of final composts. The compost matured in only 21days with the optimized two-stage composting method rather than in the 90-270days required for traditional composting. The optimal two-stage composting and the best quality compost were obtained with 0.30% EWCs and 25% CL.

  9. Design and construction of the X-2 two-stage free piston driven expansion tube

    NASA Technical Reports Server (NTRS)

    Doolan, Con

    1995-01-01

    This report outlines the design and construction of the X-2 two-stage free piston driven expansion tube. The project has completed its construction phase and the facility has been installed in the new impulsive research laboratory where commissioning is about to take place. The X-2 uses a unique, two-stage driver design which allows a more compact and lower overall cost free piston compressor. The new facility has been constructed in order to examine the performance envelope of the two-stage driver and how well it couple to sub-orbital and super-orbital expansion tubes. Data obtained from these experiments will be used for the design of a much larger facility, X-3, utilizing the same free piston driver concept.

  10. Mining Gold Dust under the Genome Wide Significance Level: A Two-Stage Approach to Analysis of GWAS

    PubMed Central

    Shi, Gang; Boerwinkle, Eric; Morrison, Alanna C.; Gu, C. Charles; Chakravarti, Aravinda; Rao, DC

    2013-01-01

    We propose a two-stage approach to analyze genome-wide association (GWA) data in order to identify a set of promising single-nucleotide polymorphisms (SNPs). In stage one, we select a list of top signals from single SNP analyses by controlling false discovery rate (FDR). In stage two, we use the least absolute shrinkage and selection operator (LASSO) regression to reduce false positives. The proposed approach was evaluated using simulated quantitative traits based on genome-wide SNP data on 8,861 Caucasian individuals from the Atherosclerosis Risk in Communities (ARIC) Study. Our first stage, targeted at controlling false negatives, yields better power than using Bonferroni corrected significance level. The LASSO regression reduces the number of significant SNPs in stage two: it reduces false positive SNPs and it reduces true positive SNPs also at simulated causal loci due to linkage disequilibrium. Interestingly, the LASSO regression preserves the power from stage one, i.e., the number of causal loci detected from the LASSO regression in stage two is almost the same as in stage one, while reducing false positives further. Real data on systolic blood pressure in the ARIC study was analyzed using our two-stage approach which identified two significant SNPs, one of which was reported to be genome-significant in a meta-analysis containing a much larger sample size. On the other hand, a single SNP association scan did not yield any significant results. PMID:21254218

  11. Two-stage high-rate biogas (H2 and CH4) production from food waste using anaerobic mixed microflora

    NASA Astrophysics Data System (ADS)

    Xu, K.; Lee, D.; Kobayashi, T.; Ebie, Y.; Li, Y.; Inamori, Y.

    2010-12-01

    To achieve the high-rate H2 and CH4 production from food waste using fermentative anaerobic microflora, the effects of carbonate-alkalinity in the recirculated digestion sludge on continuous two-stage fermentation were investigated. Higher H2 production rate of 2.9 L-H2/L/day was achieved at the recycle ratio of 1.0 in an alkalinity range of 9000 to 10000 mg-CaCO3/L. The maximum CH4 production rate was stably maintained at the range of 1.85 to 1.88 L-CH4/L/day without alkalinity change. Carbonate alkalinity in digestion sludge could reduce the H2 partial pressure in the headspace of the fermentation reactors, and improve a biogas production capacity in the two-stage fermentation process. The average volatile solids degradation rate in the overall process increased as the digestion sludge recycle increased from 0.5 to 1.0. These results show that the alkalinity in recycle of the digestion sludge is crucial factor in determining biogas (H2 and CH4) production capacity and reducing the total solids.

  12. Characterisation of two-stage ignition in diesel engine-relevant thermochemical conditions using direct numerical simulation

    DOE PAGES

    Krisman, Alex; Hawkes, Evatt R.; Talei, Mohsen; ...

    2016-08-30

    With the goal of providing a more detailed fundamental understanding of ignition processes in diesel engines, this study reports analysis of a direct numerical simulation (DNS) database. In the DNS, a pseudo turbulent mixing layer of dimethyl ether (DME) at 400 K and air at 900 K is simulated at a pressure of 40 atmospheres. At these conditions, DME exhibits a two-stage ignition and resides within the negative temperature coefficient (NTC) regime of ignition delay times, similar to diesel fuel. The analysis reveals a complex ignition process with several novel features. Autoignition occurs as a distributed, two-stage event. The high-temperaturemore » stage of ignition establishes edge flames that have a hybrid premixed/autoignition flame structure similar to that previously observed for lifted laminar flames at similar thermochemical conditions. In conclusion, a combustion mode analysis based on key radical species illustrates the multi-stage and multi-mode nature of the ignition process and highlights the substantial modelling challenge presented by diesel combustion.« less

  13. Mining gold dust under the genome wide significance level: a two-stage approach to analysis of GWAS.

    PubMed

    Shi, Gang; Boerwinkle, Eric; Morrison, Alanna C; Gu, C Charles; Chakravarti, Aravinda; Rao, D C

    2011-02-01

    We propose a two-stage approach to analyze genome-wide association data in order to identify a set of promising single-nucleotide polymorphisms (SNPs). In stage one, we select a list of top signals from single SNP analyses by controlling false discovery rate. In stage two, we use the least absolute shrinkage and selection operator (LASSO) regression to reduce false positives. The proposed approach was evaluated using simulated quantitative traits based on genome-wide SNP data on 8,861 Caucasian individuals from the Atherosclerosis Risk in Communities (ARIC) Study. Our first stage, targeted at controlling false negatives, yields better power than using Bonferroni-corrected significance level. The LASSO regression reduces the number of significant SNPs in stage two: it reduces false-positive SNPs and it reduces true-positive SNPs also at simulated causal loci due to linkage disequilibrium. Interestingly, the LASSO regression preserves the power from stage one, i.e., the number of causal loci detected from the LASSO regression in stage two is almost the same as in stage one, while reducing false positives further. Real data on systolic blood pressure in the ARIC study was analyzed using our two-stage approach which identified two significant SNPs, one of which was reported to be genome-significant in a meta-analysis containing a much larger sample size. On the other hand, a single SNP association scan did not yield any significant results.

  14. Characterisation of two-stage ignition in diesel engine-relevant thermochemical conditions using direct numerical simulation

    SciTech Connect

    Krisman, Alex; Hawkes, Evatt R.; Talei, Mohsen; Bhagatwala, Ankit; Chen, Jacqueline H.

    2016-08-30

    With the goal of providing a more detailed fundamental understanding of ignition processes in diesel engines, this study reports analysis of a direct numerical simulation (DNS) database. In the DNS, a pseudo turbulent mixing layer of dimethyl ether (DME) at 400 K and air at 900 K is simulated at a pressure of 40 atmospheres. At these conditions, DME exhibits a two-stage ignition and resides within the negative temperature coefficient (NTC) regime of ignition delay times, similar to diesel fuel. The analysis reveals a complex ignition process with several novel features. Autoignition occurs as a distributed, two-stage event. The high-temperature stage of ignition establishes edge flames that have a hybrid premixed/autoignition flame structure similar to that previously observed for lifted laminar flames at similar thermochemical conditions. In conclusion, a combustion mode analysis based on key radical species illustrates the multi-stage and multi-mode nature of the ignition process and highlights the substantial modelling challenge presented by diesel combustion.

  15. Rapid two-stage Starnes procedure for a symptomatic neonate with Ebstein anomaly.

    PubMed

    Kajihara, Noriyoshi; Asou, Toshihide; Takeda, Yuko; Kosaka, Yoshimichi; Onakatomi, Yasuko; Miyata, Daiki; Yasui, Seiyo

    2010-12-01

    We present a rapid two-stage Starnes procedure for a seriously symptomatic neonate with the prenatal diagnosis of Ebstein anomaly. At 16 hours after birth, we performed an emergency operation consisting of main pulmonary artery ligation, plication of the right atrial and right ventricular wall, modified Blalock-Taussig shunt, and patent ductus arteriosus ligation, without cardiopulmonary bypass. At age 12 days, we then performed the Starnes procedure using a glutaraldehyde-treated autologous pericardial patch with a 4-mm fenestration to close the tricuspid valve orifice. The infant's postoperative course was excellent. A rapid two-stage Starnes procedure is useful for treating a seriously symptomatic neonate with Ebstein anomaly.

  16. Mechanisms to deploy the two-stage IUS from the shuttle cargo bay

    NASA Technical Reports Server (NTRS)

    Haynie, H. T.

    1980-01-01

    The Inertial Upper Stage (IUS) is a two-stage or three-stage booster used to transport spacecraft from the space shuttle orbit to synchronous orbit or on an interplanetary trajectory. The mechanisms which were designed specifically to perform the two-stage IUS required functions while contained within the cargo bay of the space shuttle during the boost phase and while in a low Earth orbit are discussed. The requirements, configuration, and operation of the mechanisms are described, with particular emphasis on the tilt actuator and the mechanism for decoupling the actuators during boost to eliminate redundant load paths.

  17. Randomized two-stage Phase II clinical trial designs based on Barnard's exact test.

    PubMed

    Shan, Guogen; Ma, Changxing; Hutson, Alan D; Wilding, Gregory E

    2013-01-01

    In areas such as oncology, two-stage designs are often preferred as compared to one-stage designs due to the ability to stop the trial early when faced with evidence of lack of sufficient efficacy and the associated sample size savings. We present exact two-stage designs based on Barnard's exact test for differences in proportions and compare the designs to those proposed by Kepner ( 2010 ) and Jung ( 2010 ). In addition, we present tables of decision rules under a variety of assumed realities for use in trial planning. The procedure is recommended for use due to the substantial sample size savings experienced.

  18. Two-Stage Sampling Procedures for Comparing Means When Population Distributions Are Non-Normal.

    ERIC Educational Resources Information Center

    Luh, Wei-Ming; Olejnik, Stephen

    Two-stage sampling procedures for comparing two population means when variances are heterogeneous have been developed by D. G. Chapman (1950) and B. K. Ghosh (1975). Both procedures assume sampling from populations that are normally distributed. The present study reports on the effect that sampling from non-normal distributions has on Type I error…

  19. Assessing Compliance-Effect Bias in the Two Stage Least Squares Estimator

    ERIC Educational Resources Information Center

    Reardon, Sean; Unlu, Fatih; Zhu, Pei; Bloom, Howard

    2011-01-01

    The proposed paper studies the bias in the two-stage least squares, or 2SLS, estimator that is caused by the compliance-effect covariance (hereafter, the compliance-effect bias). It starts by deriving the formula for the bias in an infinite sample (i.e., in the absence of finite sample bias) under different circumstances. Specifically, it…

  20. Treatment of corn ethanol distillery wastewater using two-stage anaerobic digestion.

    PubMed

    Ráduly, B; Gyenge, L; Szilveszter, Sz; Kedves, A; Crognale, S

    In this study the mesophilic two-stage anaerobic digestion (AD) of corn bioethanol distillery wastewater is investigated in laboratory-scale reactors. Two-stage AD technology separates the different sub-processes of the AD in two distinct reactors, enabling the use of optimal conditions for the different microbial consortia involved in the different process phases, and thus allowing for higher applicable organic loading rates (OLRs), shorter hydraulic retention times (HRTs) and better conversion rates of the organic matter, as well as higher methane content of the produced biogas. In our experiments the reactors have been operated in semi-continuous phase-separated mode. A specific methane production of 1,092 mL/(L·d) has been reached at an OLR of 6.5 g TCOD/(L·d) (TCOD: total chemical oxygen demand) and a total HRT of 21 days (5.7 days in the first-stage, and 15.3 days in the second-stage reactor). Nonetheless the methane concentration in the second-stage reactor was very high (78.9%); the two-stage AD outperformed the reference single-stage AD (conducted at the same reactor loading rate and retention time) by only a small margin in terms of volumetric methane production rate. This makes questionable whether the higher methane content of the biogas counterbalances the added complexity of the two-stage digestion.

  1. Overcoming the bottlenecks of anaerobic digestion of olive mill solid waste by two-stage fermentation.

    PubMed

    Stoyanova, Elitza; Lundaa, Tserennyam; Bochmann, Günther; Fuchs, Werner

    2017-02-01

    Two-stage anaerobic digestion (AD) of two-phase olive mill solid waste (OMSW) was applied for reducing the inhibiting factors by optimizing the acidification stage. Single-stage AD and co-fermentation with chicken manure were conducted coinstantaneous for direct comparison. Degradation of the polyphenols up to 61% was observed during the methanogenic stage. Nevertheless the concentration of phenolic substances was still high; the two-stage fermentation remained stable at OLR 1.5 kgVS/m³day. The buffer capacity of the system was twice as high, compared to the one-stage fermentation, without additives. The two-stage AD was a combined process - thermophilic first stage and mesophilic second stage, which pointed out to be the most profitable for AD of OMSW for the reduced hydraulic retention time (HRT) from 230 to 150 days, and three times faster than the single-stage and the co-fermentation start-up of the fermentation. The optimal HRT and incubation temperature for the first stage were determined to four days and 55°C. The performance of the two-stage AD concerning the stability of the process was followed by the co-digestion of OMSW with chicken manure as a nitrogen-rich co-substrate, which makes them viable options for waste disposal with concomitant energy recovery.

  2. Innovative two-stage anaerobic process for effective codigestion of cheese whey and cattle manure.

    PubMed

    Bertin, Lorenzo; Grilli, Selene; Spagni, Alessandro; Fava, Fabio

    2013-01-01

    The valorisation of agroindustrial waste through anaerobic digestion represents a significant opportunity for refuse treatment and renewable energy production. This study aimed to improve the codigestion of cheese whey (CW) and cattle manure (CM) by an innovative two-stage process, based on concentric acidogenic and methanogenic phases, designed for enhancing performance and reducing footprint. The optimum CW to CM ratio was evaluated under batch conditions. Thereafter, codigestion was implemented under continuous-flow conditions comparing one- and two-stage processes. The results demonstrated that the addition of CM in codigestion with CW greatly improved the anaerobic process. The highest methane yield was obtained co-treating the two substrates at equal ratio by using the innovative two-stage process. The proposed system reached the maximum value of 258 mL(CH4) g(gv(-1), which was more than twice the value obtained by the one-stage process and 10% higher than the value obtained by the two-stage one.

  3. Identifying combined design and analysis procedures in two-stage trials with a binary end point.

    PubMed

    Bowden, Jack; Wason, James

    2012-12-20

    Two-stage trial designs provide the flexibility to stop early for efficacy or futility and are popular because they have a smaller sample size on average than a traditional trial has with the same type I and II error rates. This makes them financially attractive but also has the ethical benefit of reducing, in the long run, the number of patients who are given ineffective treatments. Designs that minimise the expected sample size are often referred to as 'optimal'. However, two-stage designs can impart a substantial bias into the parameter estimate at the end of the trial. In this paper, we argue that the expected performance of one's chosen estimation method should also be considered when deciding on a two-stage trial design. We review the properties of standard and bias-adjusted maximum likelihood estimators as well as mean and median unbiased estimators. We then identify optimal two-stage design and analysis procedures that balance projected sample size considerations with those of estimator performance. We make available software to implement this new methodology.

  4. A Two-Stage Exercise on the Binomial Distribution Using Minitab.

    ERIC Educational Resources Information Center

    Shibli, M. Abdullah

    1990-01-01

    Describes a two-stage experiment that was designed to explain binomial distribution to undergraduate statistics students. A manual coin flipping exercise is explained as the first stage; a computerized simulation using MINITAB software is presented as stage two; and output from the MINITAB exercises is included. (two references) (LRW)

  5. Response Bias Using Two-Stage Data Collection: A Study of Elderly Participants in a Program.

    ERIC Educational Resources Information Center

    Goodfellow, Marianne; And Others

    1988-01-01

    This study assessed the nature of response bias in a two-stage data-collection design (telephone interviews followed by a questionnaire mailing), which was used to examine the effectiveness of a state-level pharmaceutical assistance program for the elderly. Demographic and health factors affecting response (N=1,705 elderly persons) are discussed.…

  6. Extraoral implants for orbit rehabilitation: a comparison between one-stage and two-stage surgeries.

    PubMed

    de Mello, M C L M P; Guedes, R; de Oliveira, J A P; Pecorari, V A; Abrahão, M; Dib, L L

    2014-03-01

    The aim of the study was to compare the osseointegration success rate and time for delivery of the prosthesis among cases treated by two-stage or one-stage surgery for orbit rehabilitation between 2003 and 2011. Forty-five patients were included, 31 males and 14 females; 22 patients had two-stage surgery and 23 patients had one-stage surgery. A total 138 implants were installed, 42 (30.4%) on previously irradiated bone. The implant survival rate was 96.4%, with a success rate of 99.0% among non-irradiated patients and 90.5% among irradiated patients. Two-stage patients received 74 implants with a survival rate of 94.6% (four implants lost); one-stage surgery patients received 64 implants with a survival rate of 98.4% (one implant lost). The median time interval between implant fixation and delivery of the prosthesis for the two-stage group was 9.6 months and for the one-stage group was 4.0 months (P < 0.001). The one-stage technique proved to be reliable and was associated with few risks and complications; the rate of successful osseointegration was similar to those reported in the literature. The one-stage technique should be considered a viable procedure that shortens the time to final rehabilitation and facilitates appropriate patient follow-up treatment.

  7. Use a Log Splitter to Demonstrate Two-Stage Hydraulic Pump

    ERIC Educational Resources Information Center

    Dell, Timothy W.

    2012-01-01

    The two-stage hydraulic pump is commonly used in many high school and college courses to demonstrate hydraulic systems. Unfortunately, many textbooks do not provide a good explanation of how the technology works. Another challenge that instructors run into with teaching hydraulic systems is the cost of procuring an expensive real-world machine…

  8. EVALUATION OF A TWO-STAGE PASSIVE TREATMENT APPROACH FOR MINING INFLUENCE WATERS

    EPA Science Inventory

    A two-stage passive treatment approach was assessed at bench-scale using two Colorado Mining Influenced Waters (MIWs). The first-stage was a limestone drain with the purpose of removing iron and aluminum and mitigating the potential effects of mineral acidity. The second stage w...

  9. A two-stage spectrum sensing scheme based on energy detection and a novel multitaper method

    NASA Astrophysics Data System (ADS)

    Qi, Pei-Han; Li, Zan; Si, Jiang-Bo; Xiong, Tian-Yi

    2015-04-01

    Wideband spectrum sensing has drawn much attention in recent years since it provides more opportunities to the secondary users. However, wideband spectrum sensing requires a long time and a complex mechanism at the sensing terminal. A two-stage wideband spectrum sensing scheme is considered to proceed spectrum sensing with low time consumption and high performance to tackle this predicament. In this scheme, a novel multitaper spectrum sensing (MSS) method is proposed to mitigate the poor performance of energy detection (ED) in the low signal-to-noise ratio (SNR) region. The closed-form expression of the decision threshold is derived based on the Neyman-Pearson criterion and the probability of detection in the Rayleigh fading channel is analyzed. An optimization problem is formulated to maximize the probability of detection of the proposed two-stage scheme and the average sensing time of the two-stage scheme is analyzed. Numerical results validate the efficiency of MSS and show that the two-stage spectrum sensing scheme enjoys higher performance in the low SNR region and lower time cost in the high SNR region than the single-stage scheme. Project supported by the National Natural Science Foundation of China (Grant No. 61301179), the China Postdoctoral Science Foundation (Grant No. 2014M550479), and the Doctorial Programs Foundation of the Ministry of Education, China (Grant No. 20110203110011).

  10. Thermal design of two-stage evaporative cooler based on thermal comfort criterion

    NASA Astrophysics Data System (ADS)

    Gilani, Neda; Poshtiri, Amin Haghighi

    2016-09-01

    Performance of two-stage evaporative coolers at various outdoor air conditions was numerically studied, and its geometric and physical characteristics were obtained based on thermal comfort criteria. For this purpose, a mathematical model was developed based on conservation equations of mass, momentum and energy to determine heat and mass transfer characteristics of the system. The results showed that two-stage indirect/direct cooler can provide the thermal comfort condition when outdoor air temperature and relative humidity are located in the range of 34-54 °C and 10-60 %, respectively. Moreover, as relative humidity of the ambient air rises, two-stage evaporative cooler with the smaller direct and larger indirect cooler will be needed. In building with high cooling demand, thermal comfort may be achieved at a greater air change per hour number, and thus an expensive two-stage evaporative cooler with a higher electricity consumption would be required. Finally, a design guideline was proposed to determine the size of required plate heat exchangers at various operating conditions.

  11. Magnetic induction system for two-stage gun projectile velocity measurements

    SciTech Connect

    Moody, R L; Konrad, C H

    1984-05-01

    A magnetic induction technique for measuring projectile velocities has been implemented on Sandia's two-stage light gas gun. The system has been designed to allow for projectile velocity measurements to an accuracy of approx. 0.2 percent. The velocity system has been successfully tested in a velocity range of 3.5 km/s to 6.5 km/s.

  12. Magnetic gauge instrumentation on the LANL gas-driven two-stage gun

    SciTech Connect

    Alcon, R.R.; Sheffield, S.A.; Martinez, A.R.; Gustavsen, R.L.

    1997-11-01

    The LANL gas-driven two-stage gun was designed and built to do initiation studies on insensitive high explosives as well as equation of state and reaction experiments on other materials. The preferred method of measuring reaction phenomena involves the use of in-situ magnetic particle velocity gauges. In order to accommodate this type of gauging in the two-stage gun, it has a 50-mm-diameter launch tube. The authors have sued magnetic gauging on the 72-mm bore diameter single-stage gun for over 15 years and it has proven a very effective technique for all types of shock wave experiments, including those on high explosives. This technique has now been installed on the gas-driven two-stage gun. They describe the method used, as well as some of the difficulties that arose during the installation. Several magnetic gauge experiments have been completed on plastic materials. Waveforms obtained in some of the experiments will be discussed. Up to 10 in-situ particle velocity measurements can be made in a single experiment. This new technique is now working quite well, as is evidenced by the data. To their knowledge, this is the first time magnetic gauging has been used on a two-stage gun.

  13. High concentration two-stage optics for parabolic trough solar collectors with tubular absorber and large rim angle

    SciTech Connect

    Collares-Pereira, M. ); Gordon, J.M. ); Rabl, A. ); Winston, R. )

    1991-01-01

    A new two-stage optical design is proposed for parabolic trough solar collectors with tubular absorbers. It can boost the concentration ratio by a factor of 2.5 relative to the conventional design, while maintaining the large rim angles (i.e., low nominal f-numbers) that are desirable for practical and economical reasons. The second state involves asymmetric nonimaging concentrators of the CPC type, facing segments of the parabolic first stage. The second stage can be accommodated inside an evacuated receiver, allowing the use of first-surface silvered reflectors. The low heat loss of this design opens the possibility of producing steam at temperatures and pressures of conventional power plants, using only one-axis tracking. The improvement in conversion efficiency would be substantial.

  14. Mach 6.5 air induction system design for the Beta 2 two-stage-to-orbit booster vehicle

    NASA Technical Reports Server (NTRS)

    Midea, Anthony C.

    1991-01-01

    A preliminary, two-dimensional, mixed compression air induction system is designed for the Beta II Two Stage to Orbit booster vehicle to minimize installation losses and efficiently deliver the required airflow. Design concepts, such as an external isentropic compression ramp and a bypass system were developed and evaluated for performance benefits. The design was optimized by maximizing installed propulsion/vehicle system performance. The resulting system design operating characteristics and performance are presented. The air induction system design has significantly lower transonic drag than similar designs and only requires about 1/3 of the bleed extraction. In addition, the design efficiently provides the integrated system required airflow, while maintaining adequate levels of total pressure recovery. The excellent performance of this highly integrated air induction system is essential for the successful completion of the Beta II booster vehicle mission.

  15. Two-stage fan. 3: Data and performance with rotor tip casing treatment, uniform and distorted inlet flows

    NASA Technical Reports Server (NTRS)

    Burger, G. D.; Hodges, T. R.; Keenan, M. J.

    1975-01-01

    A two stage fan with a 1st-stage rotor design tip speed of 1450 ft/sec, a design pressure ratio of 2.8, and corrected flow of 184.2 lbm/sec was tested with axial skewed slots in the casings over the tips of both rotors. The variable stagger stators were set in the nominal positions. Casing treatment improved stall margin by nine percentage points at 70 percent speed but decreased stall margin, efficiency, and flow by small amounts at design speed. Treatment improved first stage performance at low speed only and decreased second stage performance at all operating conditions. Casing treatment did not affect the stall line with tip radially distorted flow but improved stall margin with circumferentially distorted flow. Casing treatment increased the attenuation for both types of inlet flow distortion.

  16. High-pressure Experimental Studies on Geo-liquids Using Synchrotron Radiation at the Advanced Photon Source

    SciTech Connect

    Wang, Yanbin; Shen, Guoyin

    2014-12-23

    Here, we review recent progress in studying silicate, carbonate, and metallic liquids of geological and geophysical importance at high pressure and temperature, using the large-volume high-pressure devices at the third-generation synchrotron facility of the Advanced Photon Source, Argonne National Laboratory. These integrated high-pressure facilities now offer a unique combination of experimental techniques that allow researchers to investigate structure, density, elasticity, viscosity, and interfacial tension of geo-liquids under high pressure, in a coordinated and systematic fashion. Moreover, we describe experimental techniques, along with scientific highlights. Future developments are also discussed.

  17. Biomass waste gasification - Can be the two stage process suitable for tar reduction and power generation?

    SciTech Connect

    Sulc, Jindrich; Stojdl, Jiri; Richter, Miroslav; Popelka, Jan; Svoboda, Karel; Smetana, Jiri; Vacek, Jiri; Skoblja, Siarhei; Buryan, Petr

    2012-04-15

    Highlights: Black-Right-Pointing-Pointer Comparison of one stage (co-current) and two stage gasification of wood pellets. Black-Right-Pointing-Pointer Original arrangement with grate-less reactor and upward moving bed of the pellets. Black-Right-Pointing-Pointer Two stage gasification leads to drastic reduction of tar content in gas. Black-Right-Pointing-Pointer One stage gasification produces gas with higher LHV at lower overall ER. Black-Right-Pointing-Pointer Content of ammonia in gas is lower in two stage moving bed gasification. - Abstract: A pilot scale gasification unit with novel co-current, updraft arrangement in the first stage and counter-current downdraft in the second stage was developed and exploited for studying effects of two stage gasification in comparison with one stage gasification of biomass (wood pellets) on fuel gas composition and attainable gas purity. Significant producer gas parameters (gas composition, heating value, content of tar compounds, content of inorganic gas impurities) were compared for the two stage and the one stage method of the gasification arrangement with only the upward moving bed (co-current updraft). The main novel features of the gasifier conception include grate-less reactor, upward moving bed of biomass particles (e.g. pellets) by means of a screw elevator with changeable rotational speed and gradual expanding diameter of the cylindrical reactor in the part above the upper end of the screw. The gasifier concept and arrangement are considered convenient for thermal power range 100-350 kW{sub th}. The second stage of the gasifier served mainly for tar compounds destruction/reforming by increased temperature (around 950 Degree-Sign C) and for gasification reaction of the fuel gas with char. The second stage used additional combustion of the fuel gas by preheated secondary air for attaining higher temperature and faster gasification of the remaining char from the first stage. The measurements of gas composition and tar

  18. Prediction of Unsteady Blade Surface Pressures on an Advanced Propeller at an Angle of Attack

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Groeneweg, J. F.

    1989-01-01

    The numerical solution of the unsteady, three-dimensional, Euler equations is considered in order to obtain the blade surface pressures of an advanced propeller at an angle of attack. The specific configuration considered is the SR7L propeller at cruise conditions with a 4.6 deg inflow angle corresponding to the plus 2 deg nacelle tilt of the Propeller Test Assessment (PTA) flight test condition. The results indicate nearly sinusoidal response of the blade loading, with angle of attack. For the first time, detailed variations of the chordwise loading as a function of azimuthal angle are presented. It is observed that the blade is lightly loaded for part of the revolution and shocks appear from hub to about 80 percent radial station for the highly loaded portion of the revolution.

  19. Prediction of unsteady blade surface pressures on an advanced propeller at an angle of attack

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Groeneweg, J. F.

    1989-01-01

    The paper considers the numerical solution of the unsteady, three-dimensional, Euler equations to obtain the blade surface pressures of an advanced propeller at an angle of attack. The specific configuration considered is the SR7L propeller at cruise conditions with a 4.6 deg inflow angle corresponding to the +2 deg nacelle tilt of the Propeller Test Assessment (PTA) flight test condition. The results indicate nearly sinusoidal response of the blade loading, with angle of attack. For the first time, detailed variations of the chordwise loading as a function of azimuthal angle are presented. It is observed that the blade is lightly loaded for part of the revolution and shocks appear from hub to about 80 percent radial station for the highly loaded portion of the revolution.

  20. Prestressed-concrete pressure vessels and their applicability to advanced-energy-system concepts

    SciTech Connect

    Naus, D.J

    1983-01-01

    Prestressed concrete pressure vessels (PCPVs) are, in essence, spaced steel structures since their strength is derived from a multitude of steel elements made up of deformed reinforcing bars and prestressing tendons which are present in sufficient quantities to carry tension loads imposed on the vessel. Other major components of a PCPV include the concrete, liner and cooling system, and insulation. PCPVs exhibit a number of advantages which make them ideally suited for application to advanced energy concepts: fabricability in virtually any size and shape using available technology, improved safety, reduced capital costs, and a history of proven performance. PCPVs have many applications to both nuclear- and non-nuclear-based energy systems concepts. Several of these concepts will be discussed as well as the research and development activities conducted at ORNL in support of PCPV development.

  1. Prestressed concrete pressure vessels and their applicability to advanced energy system concepts

    SciTech Connect

    Naus, D.J.

    1983-01-01

    Prestressed concrete pressure vessels (PCPVs) are, in essence, spaced steel structures since their strength is derived from a multitude of steel elements made up of deformed reinforcing bars and prestressing tendons which are present in sufficient quantities to carry tension loads imposed on the vessel. Other major components of a PCPV include the concrete, liner and cooling system, and insulation. PCPVs exhibit a number of advantages which make them ideally suited for application to advanced energy concepts: fabricability in virtually any size and shape using available technology, improved safety, reduced capital costs, and a history of proven performance. PCPVs have many applications to both nuclear- and non-nuclear-based energy systems concepts. Several of these concepts are discussed as well as the research and development activities conducted at ORNL in support of PCPV development.

  2. Optical Fuel Injector Patternation Measurements in Advanced Liquid-Fueled, High Pressure, Gas Turbine Combustors

    NASA Technical Reports Server (NTRS)

    Locke, R. J.; Hicks, Y. R.; Anderson, R. C.; Zaller, M. M.

    1998-01-01

    Planar laser-induced fluorescence (PLIF) imaging and planar Mie scattering are used to examine the fuel distribution pattern (patternation) for advanced fuel injector concepts in kerosene burning, high pressure gas turbine combustors. Three fuel injector concepts for aerospace applications were investigated under a broad range of operating conditions. Fuel PLIF patternation results are contrasted with those obtained by planar Mie scattering. For one injector, further comparison is also made with data obtained through phase Doppler measurements. Differences in spray patterns for diverse conditions and fuel injector configurations are readily discernible. An examination of the data has shown that a direct determination of the fuel spray angle at realistic conditions is also possible. The results obtained in this study demonstrate the applicability and usefulness of these nonintrusive optical techniques for investigating fuel spray patternation under actual combustor conditions.

  3. Extension of the operating parameters of the two stage light gas gun to velocities below 2 km/sec.

    SciTech Connect

    Thoe, R S

    2007-08-28

    The Joint Actinide Shock Physics Experimental Facility (JASPER) located in area 27 at the Nevada Test Site Has been tasked with providing high accuracy information on the Equation Of State (EOS) and other dynamic properties of weapons grade plutonium and other actinides important to the stockpile stewardship program. In the past 5 years this facility has provided dozens of experimental data points for the accurate determination of pressure density relationship for these materials over a broad pressure range. In order to complete this survey it is necessary to extend the low pressure region to include projectile velocities below 2 km/s. For most gas gun facilities this would present not too great a difficulty, one could simply decrease the amount of propellant along with a decrease in the strength of the petal valve, However JASPER requires that the piston be securely embedded in the Acceleration Reservoir (AR) as part of the containment system. The projectile must remain flat and undistorted. This requirement makes the attainment of slow velocities problematic. This talk will discuss the JASPER Facility, A finite difference code developed to give predictive capability for two stage gas guns, and a set of experiments performed to demonstrate this capability.

  4. Two-stage spin transition of iron in FeAl-bearing phase D at lower mantle

    NASA Astrophysics Data System (ADS)

    Wu, Xiang; Wu, Ye; Lin, Jung-Fu; Liu, Jin; Mao, Zhu; Guo, Xinzhuan; Yoshino, Takashi; McCammon, Catherine; Prakapenka, Vitali B.; Xiao, Yuming

    2016-09-01

    Hydrous magnesium silicate phase D plays a key role in the transport of water from the upper to the lower mantle via subducted slabs. Here we report pressure dependence hyperfine and lattice parameters of FeAl-bearing phase D up to megabar pressures using synchrotron nuclear forward scattering and X-ray diffraction in a diamond anvil cell at room temperature. FeAl-bearing phase D undergoes a two-stage high-spin to low-spin transition of iron for Fe2+ at 37-41 GPa and for Fe3+ at 64-68 GPa. These transitions are accompanied by an increase in density and a significant softening in the bulk modulus and bulk velocity at their respective pressure range. The occurrence of the dense low-spin FeAl-bearing phase D with relatively high velocity anisotropies in deep-subducted slabs can potentially contribute to small-scale seismic heterogeneities in the middle-lower mantle beneath the circum-Pacific area.

  5. Evaluation of the two-stage ditch as a best management practice

    NASA Astrophysics Data System (ADS)

    Hodaj, A.; Bowling, L. C.; Cibin, R.; Chaubey, I.

    2015-12-01

    Artificial drainage has long been an important component of agriculture in the poorly-drained regions of the US Corn Belt. Continued increases in drainage intensity funnel more water into existing drainage ditches, resulting in higher flood stages, more erosive water velocities and decreased time for in-channel nutrient processing. The two-stage ditch is a type of in-stream restoration that involves modification of a trapezoidal drainage ditch to resemble more the features of a natural stream. The idea is to create or simulate extended benches on both sides of the ditch that would develop naturally over a period of time in a stream because of geomorphological processes. These in-channel flood plains provide a greater flow area during high flow events and offer the potential to reduce sediment load and extend the interaction time between water and vegetation on the benches, allowing larger uptake of nutrients and increasing the denitrification rates in the bench soil. The Soil and Water Assessment Tool (SWAT) hydrologic model has recently been modified to represent the two-stage ditch as a conservation practice. Processes that are represented in the model include: velocity reductions due to the change in channel geometry, particle settling, plant nutrient uptake and denitrification on the benches of the two-stage ditch. The model is evaluated using data collected from a two-stage ditch constructed at the Throckmorton Purdue Agricultural Center (TPAC) near Lafayette, Indiana in September 2012. It drains an area of approximately 2.7 km2 of farmland used for corn and soybean production. Simulation results for 30 years of weather data indicated the impact of the two-stage ditch on reducing peak flow rates, flood stage and nutrient loads. For this 30 year period, 1985 - 2014, the results showed reductions of up to 40% of peak flow velocities, 35% reduction per km of two-stage ditch, of sediment basin output, 10 - 80% reduction in total phosphorus output and 0 - 15

  6. A two-stage ultrafiltration and nanofiltration process for recycling dairy wastewater.

    PubMed

    Luo, Jianquan; Ding, Luhui; Qi, Benkun; Jaffrin, Michel Y; Wan, Yinhua

    2011-08-01

    A two-stage ultrafiltration and nanofiltration (UF/NF) process for the treatment of model dairy wastewater was investigated to recycle nutrients and water from the wastewater. Ultracel PLGC and NF270 membranes were found to be the most suitable for this purpose. In the first stage, protein and lipid were concentrated by the Ultracel PLGC UF membrane and could be used for algae cultivation to produce biodiesel and biofuel, and the permeate from UF was concentrated by the NF270 membrane in the second stage to obtain lactose in retentate and reusable water in permeate, while the NF retentate could be recycled for anaerobic digestion to produce biogas. With this approach, most of dairy wastewater could be recycled to produce reusable water and substrates for bioenergy production. Compared with the single NF process, this two-stage UF/NF process had a higher efficiency and less membrane fouling.

  7. Two-Stage Cementless Revision Total Hip Arthroplasty for Infected Primary Hip Arthroplasties.

    PubMed

    Camurcu, Yalkin; Sofu, Hakan; Buyuk, Abdul Fettah; Gursu, Sarper; Kaygusuz, Mehmet Akif; Sahin, Vedat

    2015-09-01

    The main purpose of the present study was to analyze the clinical features, the most common infective agents, and the results of two-stage total hip revision using a teicoplanin-impregnated spacer. Between January 2005 and July 2011, 41 patients were included. At the clinical status analysis, physical examination was performed, Harris hip score was noted, isolated microorganisms were recorded, and the radiographic evaluation was performed. The mean Harris hip score was improved from 38.9 ± 9.6 points to 81.8 ± 5.8 points (P<0.05). Infection was eradicated in 39 hips. Radiographic evidence of stability was noted in 37 acetabular revision components, and all femoral stems. Two-stage revision of the infected primary hip arthroplasty is a time-consuming but a reliable procedure with high rates of success.

  8. Interval estimation of binomial proportion in clinical trials with a two-stage design.

    PubMed

    Tsai, Wei-Yann; Chi, Yunchan; Chen, Chia-Min

    2008-01-15

    Generally, a two-stage design is employed in Phase II clinical trials to avoid giving patients an ineffective drug. If the number of patients with significant improvement, which is a binomial response, is greater than a pre-specified value at the first stage, then another binomial response at the second stage is also observed. This paper considers interval estimation of the response probability when the second stage is allowed to continue. Two asymptotic interval estimators, Wald and score, as well as two exact interval estimators, Clopper-Pearson and Sterne, are constructed according to the two binomial responses from this two-stage design, where the binomial response at the first stage follows a truncated binomial distribution. The mean actual coverage probability and expected interval width are employed to evaluate the performance of these interval estimators. According to the comparison results, the score interval is recommended for both Simon's optimal and minimax designs.

  9. Toward Improving Electrocardiogram (ECG) Biometric Verification using Mobile Sensors: A Two-Stage Classifier Approach.

    PubMed

    Tan, Robin; Perkowski, Marek

    2017-02-20

    Electrocardiogram (ECG) signals sensed from mobile devices pertain the potential for biometric identity recognition applicable in remote access control systems where enhanced data security is demanding. In this study, we propose a new algorithm that consists of a two-stage classifier combining random forest and wavelet distance measure through a probabilistic threshold schema, to improve the effectiveness and robustness of a biometric recognition system using ECG data acquired from a biosensor integrated into mobile devices. The proposed algorithm is evaluated using a mixed dataset from 184 subjects under different health conditions. The proposed two-stage classifier achieves a total of 99.52% subject verification accuracy, better than the 98.33% accuracy from random forest alone and 96.31% accuracy from wavelet distance measure algorithm alone. These results demonstrate the superiority of the proposed algorithm for biometric identification, hence supporting its practicality in areas such as cloud data security, cyber-security or remote healthcare systems.

  10. Gas pollutants removal in a single- and two-stage ejector-venturi scrubber.

    PubMed

    Gamisans, Xavier; Sarrà, Montserrrat; Lafuente, F Javier

    2002-03-29

    The absorption of SO(2) and NH(3) from the flue gas into NaOH and H(2)SO(4) solutions, respectively has been studied using an industrial scale ejector-venturi scrubber. A statistical methodology is presented to characterise the performance of the scrubber by varying several factors such as gas pollutant concentration, air flowrate and absorbing solution flowrate. Some types of venturi tube constructions were assessed, including the use of a two-stage venturi tube. The results showed a strong influence of the liquid scrubbing flowrate on pollutant removal efficiency. The initial pollutant concentration and the gas flowrate had a slight influence. The use of a two-stage venturi tube considerably improved the absorption efficiency, although it increased energy consumption. The results of this study will be applicable to the optimal design of venturi-based absorbers for gaseous pollution control or chemical reactors.

  11. An adaptive two-stage dose-response design method for establishing Proof of Concept

    PubMed Central

    Franchetti, Yoko; Anderson, Stewart J.; Sampson, Allan R.

    2013-01-01

    We propose an adaptive two-stage dose-response design where a pre-specified adaptation rule is used to add and/or drop treatment arms between the stages. We extend the multiple comparison procedures-modeling (MCP-Mod) approach into a two-stage design. In each stage, we use the same set of candidate dose-response models and test for a dose-response relationship or proof of concept (PoC) via model-associated statistics. The stage-wise test results are then combined to establish ‘global’ PoC using a conditional error function. Our simulation studies showed good and more robust power in our design method compared to conventional and fixed designs. PMID:23957520

  12. Toward Improving Electrocardiogram (ECG) Biometric Verification using Mobile Sensors: A Two-Stage Classifier Approach

    PubMed Central

    Tan, Robin; Perkowski, Marek

    2017-01-01

    Electrocardiogram (ECG) signals sensed from mobile devices pertain the potential for biometric identity recognition applicable in remote access control systems where enhanced data security is demanding. In this study, we propose a new algorithm that consists of a two-stage classifier combining random forest and wavelet distance measure through a probabilistic threshold schema, to improve the effectiveness and robustness of a biometric recognition system using ECG data acquired from a biosensor integrated into mobile devices. The proposed algorithm is evaluated using a mixed dataset from 184 subjects under different health conditions. The proposed two-stage classifier achieves a total of 99.52% subject verification accuracy, better than the 98.33% accuracy from random forest alone and 96.31% accuracy from wavelet distance measure algorithm alone. These results demonstrate the superiority of the proposed algorithm for biometric identification, hence supporting its practicality in areas such as cloud data security, cyber-security or remote healthcare systems. PMID:28230745

  13. Two-stage combustion for reducing pollutant emissions from gas turbine combustors

    NASA Technical Reports Server (NTRS)

    Clayton, R. M.; Lewis, D. H.

    1981-01-01

    Combustion and emission results are presented for a premix combustor fueled with admixtures of JP5 with neat H2 and of JP5 with simulated partial-oxidation product gas. The combustor was operated with inlet-air state conditions typical of cruise power for high performance aviation engines. Ultralow NOx, CO and HC emissions and extended lean burning limits were achieved simultaneously. Laboratory scale studies of the non-catalyzed rich-burning characteristics of several paraffin-series hydrocarbon fuels and of JP5 showed sooting limits at equivalence ratios of about 2.0 and that in order to achieve very rich sootless burning it is necessary to premix the reactants thoroughly and to use high levels of air preheat. The application of two-stage combustion for the reduction of fuel NOx was reviewed. An experimental combustor designed and constructed for two-stage combustion experiments is described.

  14. Non-parametric Estimation of a Survival Function with Two-stage Design Studies.

    PubMed

    Li, Gang; Tseng, Chi-Hong

    2008-06-01

    The two-stage design is popular in epidemiology studies and clinical trials due to its cost effectiveness. Typically, the first stage sample contains cheaper and possibly biased information, while the second stage validation sample consists of a subset of subjects with accurate and complete information. In this paper, we study estimation of a survival function with right-censored survival data from a two-stage design. A non-parametric estimator is derived by combining data from both stages. We also study its large sample properties and derive pointwise and simultaneous confidence intervals for the survival function. The proposed estimator effectively reduces the variance and finite-sample bias of the Kaplan-Meier estimator solely based on the second stage validation sample. Finally, we apply our method to a real data set from a medical device post-marketing surveillance study.

  15. Sample size reassessment for a two-stage design controlling the false discovery rate

    PubMed Central

    Zehetmayer, Sonja; Graf, Alexandra C.; Posch, Martin

    2016-01-01

    Sample size calculations for gene expression microarray and NGS-RNA-Seq experiments are challenging because the overall power depends on unknown quantities as the proportion of true null hypotheses and the distribution of the effect sizes under the alternative. We propose a two-stage design with an adaptive interim analysis where these quantities are estimated from the interim data. The second stage sample size is chosen based on these estimates to achieve a specific overall power. The proposed procedure controls the power in all considered scenarios except for very low first stage sample sizes. The false discovery rate (FDR) is controlled despite of the data dependent choice of sample size. The two-stage design can be a useful tool to determine the sample size of high-dimensional studies if in the planning phase there is high uncertainty regarding the expected effect sizes and variability. PMID:26461844

  16. Two stage bioethanol refining with multi litre stacked microbial fuel cell and microbial electrolysis cell.

    PubMed

    Sugnaux, Marc; Happe, Manuel; Cachelin, Christian Pierre; Gloriod, Olivier; Huguenin, Gérald; Blatter, Maxime; Fischer, Fabian

    2016-12-01

    Ethanol, electricity, hydrogen and methane were produced in a two stage bioethanol refinery setup based on a 10L microbial fuel cell (MFC) and a 33L microbial electrolysis cell (MEC). The MFC was a triple stack for ethanol and electricity co-generation. The stack configuration produced more ethanol with faster glucose consumption the higher the stack potential. Under electrolytic conditions ethanol productivity outperformed standard conditions and reached 96.3% of the theoretically best case. At lower external loads currents and working potentials oscillated in a self-synchronized manner over all three MFC units in the stack. In the second refining stage, fermentation waste was converted into methane, using the scale up MEC stack. The bioelectric methanisation reached 91% efficiency at room temperature with an applied voltage of 1.5V using nickel cathodes. The two stage bioethanol refining process employing bioelectrochemical reactors produces more energy vectors than is possible with today's ethanol distilleries.

  17. Matching Characteristics of J35-A-23 Compressor and Two-stage Turbine

    NASA Technical Reports Server (NTRS)

    Dugan, James F., Jr.; Rebeske, John J., Jr.; Finger, Harold B.

    1951-01-01

    Component data on the J35-A-23 compressor and two-stage turbine were used to determine the problems in matching the two units for operatio n in a turbojet engine. Possible operating regions were determined an d an equilibrium operating line was also determined for the assumed c onditions of zero flight speed and a jet nozzle area approximately 5. 5 percent greater than the wide-open nozzle area.

  18. Latent Inhibition as a Function of US Intensity in a Two-Stage CER Procedure

    ERIC Educational Resources Information Center

    Rodriguez, Gabriel; Alonso, Gumersinda

    2004-01-01

    An experiment is reported in which the effect of unconditioned stimulus (US) intensity on latent inhibition (LI) was examined, using a two-stage conditioned emotional response (CER) procedure in rats. A tone was used as the pre-exposed and conditioned stimulus (CS), and a foot-shock of either a low (0.3 mA) or high (0.7 mA) intensity was used as…

  19. Effect of Two-Stage Aging on Microstructure of 7075 Aluminum Alloys

    DTIC Science & Technology

    1981-04-01

    which particular microstructural characteristic is of greatest significance in the stress corrosion behavior of 7075 in a high strength condition. 2...is expected that RRA may provide less improvement in the stress corrosion behavior of 7050 than of I I 7075 . Data from these tests would allow...I v h EFFECT OF TWO-STAGE AGING ON MICROSTRUCTURE OF 7075 ALUMINUM ALLOYS RE- 627 "Final Report E April 1981 "by 7! Jonn M. Papazian OT i. Prepared

  20. A two-stage monolithic buffer amplifier for 20 GHz satellite communication

    NASA Technical Reports Server (NTRS)

    Petersen, W. C.; Gupta, A. K.

    1983-01-01

    Design, fabrication, and test results of a two-stage GaAs monolithic buffer amplifier for 20 GHz satellite communication are described in this paper. A gain of 13 + or - 0.75 dB from 17.7 to 20.2 GHz was obtained from the 1.5 x 1.5 millimeter chip, which includes all necessary bias and dc blocking circuitry.

  1. [Two-stage hepatectomy for hepatic metastasis and supra renal vena cava reconstruction].

    PubMed

    Nicoluzzi, João Eduardo

    2012-12-01

    Two-stage hepatectomy uses compensatory liver regeneration after a first noncurative hepatectomy to enable a second curative resection. Herein we report the tecnical aspects of the management of a thirty-seven years-old woman with colorectal metastasis to the liver eligible because single resection could not achieve complete treatment, even in combination with chemotherapy, portal embolization, or radiofrequency, but tumors could be totally removed by two sequential resections.

  2. Effects of Endwall Geometry and Stacking on Two-Stage Supersonic Turbine Performance

    NASA Technical Reports Server (NTRS)

    Dorney, Daniel J.; Griffin, Lisa W.; Huber, Frank W.; Sondak, Douglas L.; Turner, Jim (Technical Monitor)

    2002-01-01

    Two methods are commonly used to control the secondary/separated flows (and associated losses) in supersonic turbines: endwall contouring and airfoil stacking. In the current investigation the flow path between the first-stage vanes and rotors, and the stacking of the first-stage vanes were varied in an effort to improve turbine performance. The geometric variations have been studied by performing a series of unsteady three-dimensional numerical simulations for the two-stage turbine.

  3. Two stage dual gate MESFET monolithic gain control amplifier for Ka-band

    NASA Astrophysics Data System (ADS)

    Sokolov, V.; Geddes, J.; Contolatis, A.

    A monolithic two stage gain control amplifier has been developed using submicron gate length dual gate MESFETs fabricated on ion implanted material. The amplifier has a gain of 12 dB at 30 GHz with a gain control range of over 30 dB. This ion implanted monolithic IC is readily integrable with other phased array receiver functions such as low noise amplifiers and phase shifters.

  4. Two-stage/single-stage reversible pump-turbine with supplying pump

    SciTech Connect

    Brcar, A.

    1980-08-12

    In a hydroelectric facility, a vertically mounted rotatable shaft is connected to a motor-generator and carries a pumpturbine with a supplying pump disposed below and immersed in water, the supplying pump disengaging from the shaft when the pump-turbine is driving the motor-generator and engaging the shaft when the motor-generator is driving the pump-turbine and supplying pump, thereby providing a two-stage pumping mode and a single-stage generating mode.

  5. Development of a two-stage membrane-based wash-water reclamation subsystem

    NASA Technical Reports Server (NTRS)

    Mccray, S. B.

    1988-01-01

    A two-stage membrane-based subsystem was designed and constructed to enable the recycle of wash waters generated in space. The first stage is a fouling-resistant tube-side-feed hollow-fiber ultrafiltration module, and the second stage is a spiral-wound reverse-osmosis module. Throughout long-term tests, the subsystem consistently produced high-quality permeate, processing actual wash water to 95 percent recovery.

  6. Effects of earthworm casts and zeolite on the two-stage composting of green waste

    SciTech Connect

    Zhang, Lu Sun, Xiangyang

    2015-05-15

    Highlights: • Earthworm casts (EWCs) and clinoptilolite (CL) were used in green waste composting. • Addition of EWCs + CL improved physico-chemical and microbiological properties. • Addition of EWCs + CL extended the duration of thermophilic periods during composting. • Addition of EWCs + CL enhanced humification, cellulose degradation, and nutrients. • Combined addition of 0.30% EWCs + 25% CL reduced composting time to 21 days. - Abstract: Because it helps protect the environment and encourages economic development, composting has become a viable method for organic waste disposal. The objective of this study was to investigate the effects of earthworm casts (EWCs) (at 0.0%, 0.30%, and 0.60%) and zeolite (clinoptilolite, CL) (at 0%, 15%, and 25%) on the two-stage composting of green waste. The combination of EWCs and CL improved the conditions of the composting process and the quality of the compost products in terms of the thermophilic phase, humification, nitrification, microbial numbers and enzyme activities, the degradation of cellulose and hemicellulose, and physico-chemical characteristics and nutrient contents of final composts. The compost matured in only 21 days with the optimized two-stage composting method rather than in the 90–270 days required for traditional composting. The optimal two-stage composting and the best quality compost were obtained with 0.30% EWCs and 25% CL.

  7. Technology of streptomycin sulfate separation by two-stage foam separation.

    PubMed

    Li, Juan; Wu, Zhaoliang; Li, Rui

    2012-01-01

    Industrial discharges from manufacturing streptomycin sulfate (SS) are inhibitory to biological wastewater treatment and need to be stripped of residual SS. For effective SS recovery from the wastewater, a two-stage foam separation technology was investigated using a column with a vertical ellipsoid-shaped channel (VEC) and a conventional one, and sodium dodecyl sulfate (SDS) served as the collector. The mechanism of enhancing foam drainage by VEC was theoretically analyzed. In the first stage, the column with VEC was used and under the optimal conditions of the liquid-loading volume 300 mL, volumetric airflow rate 100 mL/min, the initial pH 7.0 and the molar ratio of SDS to SS 8.0, an improved SS enrichment ratio of 16.7 was obtained. In the second stage, a conventional column was used and with a volumetric airflow rate of 450 mL/min, the foamate had a SS concentration of about 0.5 g/L, so it was used as the feed solution of the first stage. By the two-stage technology, the total SS recovery percentage reached as high as 99.7%. Thus, it was significantly effective for the two-stage foam separation technology to recover SS from the simulative wastewater.

  8. Economics of spray-dryer FGD system: the two-stage open-loop processes

    SciTech Connect

    Burnett, T.A.; O'Brien, W.E.

    1981-06-01

    Preliminary economics of the Rockwell International Corporation - Wheelabrator Frye, Inc., (RI/WF) two-stage open-loop flue gas desulfurization (FGD) process were determined for both lime and soda ash absorbents. This two-stage open-loop process is a throwaway system in which the alkali raw material (as a solution or slurry) is sprayed into the flue gas stream, dried by the latent heat in the hot flue gas, and collected as dry particulate matter in a baghouse. The fly ash is also collected in the baghouse as an inherent part of the process. An economic evaluation of a limestone slurry FGD process with an electrostatic precipitator (ESP) for particulate matter removal was included for comparison. The basis was a 500-MW power plant burning 3.5% sulfur, 16% ash coal with 90% SO/sub 2/ removal and 0.1 lb/MBtu particulate matter emission. The economic evaluations were made using both TVA and Electric Power Research Institute (EPRI) economic premises. Cost differences between the two-stage open-loop lime and soda ash versions are largely the result of different waste disposal and raw material costs. Both RI/WF versions are more economical than limestone in most process elements except raw material costs. Cost differences between the TVA- and EPRI-based estimates are the result of different methods of estimating indirect costs, levelizing operating costs, and different raw material costs.

  9. Industrial demonstration plant for the gasification of herb residue by fluidized bed two-stage process.

    PubMed

    Zeng, Xi; Shao, Ruyi; Wang, Fang; Dong, Pengwei; Yu, Jian; Xu, Guangwen

    2016-04-01

    A fluidized bed two-stage gasification process, consisting of a fluidized-bed (FB) pyrolyzer and a transport fluidized bed (TFB) gasifier, has been proposed to gasify biomass for fuel gas production with low tar content. On the basis of our previous fundamental study, an autothermal two-stage gasifier has been designed and built for gasify a kind of Chinese herb residue with a treating capacity of 600 kg/h. The testing data in the operational stable stage of the industrial demonstration plant showed that when keeping the reaction temperatures of pyrolyzer and gasifier respectively at about 700 °C and 850 °C, the heating value of fuel gas can reach 1200 kcal/Nm(3), and the tar content in the produced fuel gas was about 0.4 g/Nm(3). The results from this pilot industrial demonstration plant fully verified the feasibility and technical features of the proposed FB two-stage gasification process.

  10. Performance analysis of RDF gasification in a two stage fluidized bed-plasma process.

    PubMed

    Materazzi, M; Lettieri, P; Taylor, R; Chapman, C

    2016-01-01

    The major technical problems faced by stand-alone fluidized bed gasifiers (FBG) for waste-to gas applications are intrinsically related to the composition and physical properties of waste materials, such as RDF. The high quantity of ash and volatile material in RDF can provide a decrease in thermal output, create high ash clinkering, and increase emission of tars and CO2, thus affecting the operability for clean syngas generation at industrial scale. By contrast, a two-stage process which separates primary gasification and selective tar and ash conversion would be inherently more forgiving and stable. This can be achieved with the use of a separate plasma converter, which has been successfully used in conjunction with conventional thermal treatment units, for the ability to 'polish' the producer gas by organic contaminants and collect the inorganic fraction in a molten (and inert) state. This research focused on the performance analysis of a two-stage fluid bed gasification-plasma process to transform solid waste into clean syngas. Thermodynamic assessment using the two-stage equilibrium method was carried out to determine optimum conditions for the gasification of RDF and to understand the limitations and influence of the second stage on the process performance (gas heating value, cold gas efficiency, carbon conversion efficiency), along with other parameters. Comparison with a different thermal refining stage, i.e. thermal cracking (via partial oxidation) was also performed. The analysis is supported by experimental data from a pilot plant.

  11. Rehabilitation outcomes in patients with early and two-stage reconstruction of flexor tendon injuries

    PubMed Central

    Sade, Ilgin; İnanir, Murat; Şen, Suzan; Çakmak, Esra; Kablanoğlu, Serkan; Selçuk, Barin; Dursun, Nigar

    2016-01-01

    [Purpose] The primary aim of this study was to assess rehabilitation outcomes for early and two-stage repair of hand flexor tendon injuries. The secondary purpose of this study was to compare the findings between treatment groups. [Subjects and Methods] Twenty-three patients were included in this study. Early repair (n=14) and two-stage repair (n=9) groups were included in a rehabilitation program that used hand splints. This retrospective evaluated patients according to their demographic characteristics, including age, gender, injured hand, dominant hand, cause of injury, zone of injury, number of affected fingers, and accompanying injuries. Pain, range of motion, and grip strength were evaluated using a visual analog scale, goniometer, and dynamometer, respectively. [Results] Both groups showed significant improvements in pain and finger flexion after treatment compared with baseline measurements. However, no significant differences were observed between the two treatment groups. Similar results were obtained for grip strength and pinch grip, whereas gross grip was better in the early tendon repair group. [Conclusion] Early and two-stage reconstruction of patients with flexor tendon injuries can be performed with similarly favorable responses and effective rehabilitation programs. PMID:27630400

  12. Bias in estimating the causal hazard ratio when using two-stage instrumental variable methods.

    PubMed

    Wan, Fei; Small, Dylan; Bekelman, Justin E; Mitra, Nandita

    2015-06-30

    Two-stage instrumental variable methods are commonly used to estimate the causal effects of treatments on survival in the presence of measured and unmeasured confounding. Two-stage residual inclusion (2SRI) has been the method of choice over two-stage predictor substitution (2SPS) in clinical studies. We directly compare the bias in the causal hazard ratio estimated by these two methods. Under a principal stratification framework, we derive a closed-form solution for asymptotic bias of the causal hazard ratio among compliers for both the 2SPS and 2SRI methods when survival time follows the Weibull distribution with random censoring. When there is no unmeasured confounding and no always takers, our analytic results show that 2SRI is generally asymptotically unbiased, but 2SPS is not. However, when there is substantial unmeasured confounding, 2SPS performs better than 2SRI with respect to bias under certain scenarios. We use extensive simulation studies to confirm the analytic results from our closed-form solutions. We apply these two methods to prostate cancer treatment data from Surveillance, Epidemiology and End Results-Medicare and compare these 2SRI and 2SPS estimates with results from two published randomized trials.

  13. Is the continuous two-stage anaerobic digestion process well suited for all substrates?

    PubMed

    Lindner, Jonas; Zielonka, Simon; Oechsner, Hans; Lemmer, Andreas

    2016-01-01

    Two-stage anaerobic digestion systems are often considered to be advantageous compared to one-stage processes. Although process conditions and fermenter setups are well examined, overall substrate degradation in these systems is controversially discussed. Therefore, the aim of this study was to investigate how substrates with different fibre and sugar contents (hay/straw, maize silage, sugar beet) influence the degradation rate and methane production. Intermediates and gas compositions, as well as methane yields and VS-degradation degrees were recorded. The sugar beet substrate lead to a higher pH-value drop 5.67 in the acidification reactor, which resulted in a six time higher hydrogen production in comparison to the hay/straw substrate (pH-value drop 5.34). As the achieved yields in the two-stage system showed a difference of 70.6% for the hay/straw substrate, and only 7.8% for the sugar beet substrate. Therefore two-stage systems seem to be only recommendable for digesting sugar rich substrates.

  14. Two-stage residual inclusion estimation: addressing endogeneity in health econometric modeling.

    PubMed

    Terza, Joseph V; Basu, Anirban; Rathouz, Paul J

    2008-05-01

    The paper focuses on two estimation methods that have been widely used to address endogeneity in empirical research in health economics and health services research-two-stage predictor substitution (2SPS) and two-stage residual inclusion (2SRI). 2SPS is the rote extension (to nonlinear models) of the popular linear two-stage least squares estimator. The 2SRI estimator is similar except that in the second-stage regression, the endogenous variables are not replaced by first-stage predictors. Instead, first-stage residuals are included as additional regressors. In a generic parametric framework, we show that 2SRI is consistent and 2SPS is not. Results from a simulation study and an illustrative example also recommend against 2SPS and favor 2SRI. Our findings are important given that there are many prominent examples of the application of inconsistent 2SPS in the recent literature. This study can be used as a guide by future researchers in health economics who are confronted with endogeneity in their empirical work.

  15. Research on a novel two-stage direct current hybrid circuit breaker.

    PubMed

    Wu, Yifei; Wu, Yi; Rong, Mingzhe; Yang, Fei; Niu, Chunping; Li, Mei; Hu, Yang

    2014-08-01

    The DC hybrid circuit breaker based on high-speed switch (HSS) and parallel connected capacitor has been widely applied in the fault current breaking of DC system. However, when the current is commutated from HSS to the capacitor according to single-stage operation, the capacitor has to absorb a large amount of energy stored in the system inductance within very short time. Meanwhile, a high over-voltage rate of rise is especially prone to be produced between the contacts of HSS, which will lead to a failed breaking. As a result, a novel DC hybrid circuit breaker based on the two-stage operation is proposed and analyzed in this paper. By controlling the thyristors in the commutation branches, the fault current is fast commutated into the capacitor, which can not only realize the arcless open of HSS, but also decrease the over-voltage rate of rise significantly in comparison to the traditional single-stage operation. The simulation model of fault current breaking under different conditions in 10 kV medium voltage DC system is constructed. The simulated over-voltages of single-stage and two-stage operations in the case of fault current breaking are compared and analyzed. Finally, the fault current breaking test in the two-stage operation is investigated experimentally, which validates the feasibility and effectiveness of the simulation model well.

  16. Empirical study of classification process for two-stage turbo air classifier in series

    NASA Astrophysics Data System (ADS)

    Yu, Yuan; Liu, Jiaxiang; Li, Gang

    2013-05-01

    The suitable process parameters for a two-stage turbo air classifier are important for obtaining the ultrafine powder that has a narrow particle-size distribution, however little has been published internationally on the classification process for the two-stage turbo air classifier in series. The influence of the process parameters of a two-stage turbo air classifier in series on classification performance is empirically studied by using aluminum oxide powders as the experimental material. The experimental results show the following: 1) When the rotor cage rotary speed of the first-stage classifier is increased from 2 300 r/min to 2 500 r/min with a constant rotor cage rotary speed of the second-stage classifier, classification precision is increased from 0.64 to 0.67. However, in this case, the final ultrafine powder yield is decreased from 79% to 74%, which means the classification precision and the final ultrafine powder yield can be regulated through adjusting the rotor cage rotary speed of the first-stage classifier. 2) When the rotor cage rotary speed of the second-stage classifier is increased from 2 500 r/min to 3 100 r/min with a constant rotor cage rotary speed of the first-stage classifier, the cut size is decreased from 13.16 μm to 8.76 μm, which means the cut size of the ultrafine powder can be regulated through adjusting the rotor cage rotary speed of the second-stage classifier. 3) When the feeding speed is increased from 35 kg/h to 50 kg/h, the "fish-hook" effect is strengthened, which makes the ultrafine powder yield decrease. 4) To weaken the "fish-hook" effect, the equalization of the two-stage wind speeds or the combination of a high first-stage wind speed with a low second-stage wind speed should be selected. This empirical study provides a criterion of process parameter configurations for a two-stage or multi-stage classifier in series, which offers a theoretical basis for practical production.

  17. Advanced Models of LWR Pressure Vessel Embrittlement for Low Flux-HighFluence Conditions

    SciTech Connect

    Odette, G. Robert; Yamamoto, Takuya

    2013-06-17

    Neutron embrittlement of reactor pressure vessels (RPVs) is an unresolved issue for light water reactor life extension, especially since transition temperature shifts (TTS) must be predicted for high 80-year fluence levels up to approximately 1,020 n/cm{sup 2}, far beyond the current surveillance database. Unfortunately, TTS may accelerate at high fluence, and may be further amplified by the formation of late blooming phases that result in severe embrittlement even in low-copper (Cu) steels. Embrittlement by this mechanism is a potentially significant degradation phenomenon that is not predicted by current regulatory models. This project will focus on accurately predicting transition temperature shifts at high fluence using advanced physically based, empirically validated and calibrated models. A major challenge is to develop models that can adjust test reactor data to account for flux effects. Since transition temperature shifts depend on synergistic combinations of many variables, flux-effects cannot be treated in isolation. The best current models systematically and significantly under-predict transition temperature at high fluence, although predominantly for irradiations at much higher flux than actual RPV service. This project will integrate surveillance, test reactor and mechanism data with advanced models to address a number of outstanding RPV embrittlement issues. The effort will include developing new databases and preliminary models of flux effects for irradiation conditions ranging from very low (e.g., boiling water reactor) to high (e.g., accelerated test reactor). The team will also develop a database and physical models to help predict the conditions for the formation of Mn-Ni-Si late blooming phases and to guide future efforts to fully resolve this issue. Researchers will carry out other tasks on a best-effort basis, including prediction of transition temperature shift attenuation through the vessel wall, remediation of embrittlement by annealing

  18. High Pressure Burner Rig Testing of Advanced Environmental Barrier Coatings for Si3N4 Turbine Components

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Fox, Dennis S.; Pastel, Robert T.

    2007-01-01

    Advanced thermal and environmental barrier coatings are being developed for Si3N4 components for turbine engine propulsion applications. High pressure burner rig testing was used to evaluate the coating system performance and durability. Test results demonstrated the feasibility and durability of the coating component systems under the simulated engine environments.

  19. Super blue box recycling (SUBBOR) enhanced two-stage anaerobic digestion process for recycling municipal solid waste: laboratory pilot studies.

    PubMed

    Vogt, G M; Liu, H W; Kennedy, K J; Vogt, H S; Holbein, B E

    2002-12-01

    The super blue box recycling (SUBBOR) process is an enhanced, multi-stage anaerobic digestion process for mixed municipal solid waste (MSW) and other biomass feedstock materials. The technology centers on enhanced high solids, thermophilic digestion after steam-pressure disruption of the ligno-cellulosic fiber components that are recalcitrant to conventional anaerobic digestion. Mixed MSW, rich in organic components but also containing inorganic materials, such as glass, aluminum and steel, as well as non-digestible plastic materials, has been laboratory pilot tested with a fully integrated process train designed to treat and recycle all of the MSW components. Methane yields from the MSW were 0.36 m3 CH4/kg volatile solids (VS) representing a 40% increase over the yield obtained from conventional single stage digestion. The secondary digestion step after steam pressure disruption also provided a 40% improvement in total solids and VS reduction. The residual organic fraction following two-stage digestion was fine in texture and was recovered as a clean peat fraction with reduced contents of heavy metal and other fugitive non-digested contaminants. Mass and energy balance determinations indicated a high degree of MSW diversion from landfill disposal (>80%) was achievable by the SUBBOR process as well as substantial net electrical and thermal energy production. Continuous long-term trials of the SUBBOR process at 25,000 tonnes/year are underway.

  20. Two-stage fan. 2: Data and performance with redesigned second stage rotor uniform and distorted inlet flows

    NASA Technical Reports Server (NTRS)

    Messenger, H. E.; Keenan, M. J.

    1974-01-01

    A two-stage fan with a first rotor tip speed of 1450 ft/sec (441.96 m/sec) and no inlet guide vanes was tested with uniform and distorted inlet flows, with a redesigned second rotor having a part span shroud to prevent flutter, with variable-stagger stators set in nominal positions, and without rotor casing treatment. The fan achieved a pressure ratio 2.8 at a corrected flow of 185.4 lbm/sec (84.0 kg/sec), an adiabatic efficiency of 85.0 percent, and a stall margin of 12 percent. The redesigned second rotor did not flutter. Tip radial distortion reduced the stall margin at intermediate speed, but had little effect on stall margin at high or low speeds. Hub radial distortion reduced the stall margin at design speed but increased stall margin at low speed. Circumferential distortion reduced stall pressure ratio and flow to give approximately the same stall lines with uniform inlet flow. Distortions were attenuated by the fan. For Vol. 1, see N74-11421.

  1. Advanced Dependent Pressure Vessel (DPV) nickel-hydrogen spacecraft cell and battery design

    NASA Technical Reports Server (NTRS)

    Coates, Dwaine; Wright, Doug; Repplinger, Ron

    1995-01-01

    The dependent pressure vessel (DPV) nickel-hydrogen (NiH2) battery is being developed as a potential spacecraft battery design for both military and commercial satellites. Individual pressure vessel (IPV) NiH2 batteries are currently flying on more than 70 Earth orbital satellites and have accumulated more than 140,000,000 cell-hours in actual spacecraft operation. The limitations of standard NiH2 IPV flight battery technology are primarily related to the internal cell design and the battery packaging issues associated with grouping multiple cylindrical cells. The DPV cell design offers higher specific energy and reduced cost, while retaining the established IPV NiH2 technology flight heritage and database. The advanced cell design offers a more efficient mechanical, electrical and thermal cell configuration and a reduced parts count. The internal electrode stack is a prismatic flat-plate arrangement. The flat individual cell pressure vessel provides a maximum direct thermal path for removing heat from the electrode stack. The cell geometry also minimizes multiple-cell battery packaging constraints by using an established end-plateltie-rod battery design. A major design advantage is that the battery support structure is efficiently required to restrain only the force applied to a portion of the end cell. As the cells are stacked in series to achieve the desired system voltage, this increment of the total battery weight becomes small. The geometry of the DPV cell promotes compact, minimum volume packaging and places all cell terminals along the length of the battery. The resulting ability to minimize intercell wiring offers additional design simplicity and significant weight savings. The DPV battery design offers significant cost and weight savings advantages while providing minimal design risks. Cell and battery level design issues will be addressed including mechanical, electrical and thermal design aspects. A design performance analysis will be presented at both

  2. The Association for the Advancement of Wound Care (AAWC) venous and pressure ulcer guidelines.

    PubMed

    Bolton, Laura L; Girolami, Sue; Corbett, Lisa; van Rijswijk, Lia

    2014-11-01

    Guidelines based on best available evidence to support pressure ulcer (PU) or venous ulcer (VU) management decisions can improve outcomes. Historically, such guidelines were consensus-based and differed in content and development methods used. Since 2002, the Association for the Advancement of Wound Care (AAWC) Guideline Task Force has used a systematic approach for developing "guidelines of guidelines" that unify and blend recommendations from relevant published guidelines while meeting Institute of Medicine and Agency for Healthcare Research and Quality standards. In addition to establishing the literature-based strength of each recommendation, guideline clinical relevance is examined using standard content validation procedures. All final recommendations included are clinically relevant and/or supported by the highest level of available evidence, cited with every recommendation. In addition, guideline implementation resources are provided. The most recent AAWC VU and PU guidelines and ongoing efforts for improving their clinical relevance are presented. The guideline development process must be transparent and guidelines must be updated regularly to maintain their relevance. In addition, end-user results and research studies to examine their construct and predictive validity are needed.

  3. A two-stage extraction procedure for insensitive munition (IM) explosive compounds in soils.

    PubMed

    Felt, Deborah; Gurtowski, Luke; Nestler, Catherine C; Johnson, Jared; Larson, Steven

    2016-12-01

    The Department of Defense (DoD) is developing a new category of insensitive munitions (IMs) that are more resistant to detonation or promulgation from external stimuli than traditional munition formulations. The new explosive constituent compounds are 2,4-dinitroanisole (DNAN), nitroguanidine (NQ), and nitrotriazolone (NTO). The production and use of IM formulations may result in interaction of IM component compounds with soil. The chemical properties of these IM compounds present unique challenges for extraction from environmental matrices such as soil. A two-stage extraction procedure was developed and tested using several soil types amended with known concentrations of IM compounds. This procedure incorporates both an acidified phase and an organic phase to account for the chemical properties of the IM compounds. The method detection limits (MDLs) for all IM compounds in all soil types were <5 mg/kg and met non-regulatory risk-based Regional Screening Level (RSL) criteria for soil proposed by the U.S. Army Public Health Center. At defined environmentally relevant concentrations, the average recovery of each IM compound in each soil type was consistent and greater than 85%. The two-stage extraction method decreased the influence of soil composition on IM compound recovery. UV analysis of NTO established an isosbestic point based on varied pH at a detection wavelength of 341 nm. The two-stage soil extraction method is equally effective for traditional munition compounds, a potentially important point when examining soils exposed to both traditional and insensitive munitions.

  4. Two-stage hybrid feature selection algorithms for diagnosing erythemato-squamous diseases.

    PubMed

    Xie, Juanying; Lei, Jinhu; Xie, Weixin; Shi, Yong; Liu, Xiaohui

    2013-01-01

    This paper proposes two-stage hybrid feature selection algorithms to build the stable and efficient diagnostic models where a new accuracy measure is introduced to assess the models. The two-stage hybrid algorithms adopt Support Vector Machines (SVM) as a classification tool, and the extended Sequential Forward Search (SFS), Sequential Forward Floating Search (SFFS), and Sequential Backward Floating Search (SBFS), respectively, as search strategies, and the generalized F-score (GF) to evaluate the importance of each feature. The new accuracy measure is used as the criterion to evaluated the performance of a temporary SVM to direct the feature selection algorithms. These hybrid methods combine the advantages of filters and wrappers to select the optimal feature subset from the original feature set to build the stable and efficient classifiers. To get the stable, statistical and optimal classifiers, we conduct 10-fold cross validation experiments in the first stage; then we merge the 10 selected feature subsets of the 10-cross validation experiments, respectively, as the new full feature set to do feature selection in the second stage for each algorithm. We repeat the each hybrid feature selection algorithm in the second stage on the one fold that has got the best result in the first stage. Experimental results show that our proposed two-stage hybrid feature selection algorithms can construct efficient diagnostic models which have got better accuracy than that built by the corresponding hybrid feature selection algorithms without the second stage feature selection procedures. Furthermore our methods have got better classification accuracy when compared with the available algorithms for diagnosing erythemato-squamous diseases.

  5. Murine susceptibility to two-stage skin carcinogenesis is influenced by the agent used for promotion

    SciTech Connect

    Reiners, J.J. Jr.; Nesnow, S.; Slaga, T.J.

    1984-01-01

    Several approaches were employed to investigate whether murine stock and strain differences in susceptibility to two-stage skin carcinogenesis are due to differences in the metabolism of the initiating aromatic hydrocarbons, or the consequences of the agents used for promotion. A cell-mediated mutagenesis assay was used to quantitatively compare the abilities of cultured newborn SENCAR, DBA/2, C57BL/6 and BALB/c keratinocytes to metabolize dimethylbenz(a)anthracene (DMBA) to mutagenic and cytotoxic metabolites. At equivalent concentrations of DMBA, throughout a 25-fold range in promutagen concentration, C57BL/6, BALB/c and SENCAR keratinocyte-dependent mutant frequencies were very similar and approximately twice DBA/2 keratinocyte-dependent mutant frequencies. In in vivo tumor studies, C57BL/6 mice were more sensitive than SENCAR mice to complete skin carcinogenesis protocols employing repetitive weekly treatments with DMBA and benzo(a)pyrene (BP). At equivalent concentrations of either DMBA or BP, C57BL/6 mice developed carcinomas sooner, and had a greater number of carcinomas per animal. SENCAR mice were very sensitive to two-stage skin carcinogenesis protocols employing BP and DMBA as initiators and benzoyl peroxide and 12-O-tetradecanoylphorbol-13-acetate (TPA) as promoters. C57BL/6 mice were relatively refractory to TPA promotion but sensitive to promotion with benzoyl peroxide. These findings suggest that murine stock and strain-dependent differences in sensitivity to two-stage skin carcinogenesis may not be due to major differences in the metabolism of the initiating hydrocarbons, but are partially the consequences of the agents for promotion. 24 references, 5 figures, 1 table.

  6. An adaptive Simon Two-Stage Design for Phase 2 studies of targeted therapies.

    PubMed

    Jones, Cheryl L; Holmgren, Eric

    2007-09-01

    The field of specialized medicine and clinical development programs for targeted cancer therapies are rapidly expanding. The proposed Phase 2 design allows for preliminary determination of efficacy that may be restricted to a particular sub-population defined by biomarker status (presence/absence). The design is an adaptation of the Simon Two-Stage Design. We provide examples where the adaptation can result in substantial savings in sample size and thus potentially lead to greater efficiency in decision making during the drug development process.

  7. Space Station Freedom carbon dioxide removal assembly two-stage rotary sliding vane pump

    NASA Astrophysics Data System (ADS)

    Matteau, Dennis

    1992-07-01

    The design and development of a positive displacement pump selected to operate as an essential part of the carbon dioxide removal assembly (CDRA) are described. An oilless two-stage rotary sliding vane pump was selected as the optimum concept to meet the CDRA application requirements. This positive displacement pump is characterized by low weight and small envelope per unit flow, ability to pump saturated gases and moderate amount of liquid, small clearance volumes, and low vibration. It is easily modified to accommodate several stages on a single shaft optimizing space and weight, which makes the concept ideal for a range of demanding space applications.

  8. CHaracteristics of Two-Stage Absorption Heat Pump Cycler Driven by Waste Heat From Gas Engine

    NASA Astrophysics Data System (ADS)

    Kojima, Hiroshi; Akisawa, Atsushi; Kashiwagi, Takao

    Recently the energy conservation is expected from the global environment protection view point. In this study, a new concept of a compound gas cooling system using treated sewage water combining a gas engine heat pump and an absorption heat pump is proposed. In this system, the absorption heat pump is driven by the waste heat from the gas engine. In this paper, first, the best absorption cycle for this absorption heat pump is selected for the cooling and heating mode. And finally the simulation model of the two-stage absorption heat pumps for heating mode is demonstrated and the static characteristics are clarified.

  9. Titanium-copper-nitride coated spacers for two-stage revision of infected total hip endoprostheses

    PubMed Central

    Ellenrieder, Martin; Haenle, Maximilian; Lenz, Robert; Bader, Rainer; Mittelmeier, Wolfram

    2011-01-01

    Within the first two years after total hip arthroplasty implant-associated infection has become the second most common reason for a revision surgery. Two-stage implant exchange is frequently conducted using temporary spacers made of antibiotic-loaded cement in order to prevent a bacterial colonization on the spacer. Avoiding several disadvantages of cement spacers, a conventional hemi-endoprosthesis was equipped with a copper-containing implant coating for inhibition of bacterial biofilms. In the present paper details of this novel treatment concept are presented including a case report. PMID:22242097

  10. Use of two-stage membrane countercurrent cascade for natural gas purification from carbon dioxide

    NASA Astrophysics Data System (ADS)

    Kurchatov, I. M.; Laguntsov, N. I.; Karaseva, M. D.

    2016-09-01

    Membrane technology scheme is offered and presented as a two-stage countercurrent recirculating cascade, in order to solve the problem of natural gas dehydration and purification from CO2. The first stage is a single divider, and the second stage is a recirculating two-module divider. This scheme allows natural gas to be cleaned from impurities, with any desired degree of methane extraction. In this paper, the optimal values of the basic parameters of the selected technological scheme are determined. An estimation of energy efficiency was carried out, taking into account the energy consumption of interstage compressor and methane losses in energy units.

  11. Biomass waste gasification - can be the two stage process suitable for tar reduction and power generation?

    PubMed

    Sulc, Jindřich; Stojdl, Jiří; Richter, Miroslav; Popelka, Jan; Svoboda, Karel; Smetana, Jiří; Vacek, Jiří; Skoblja, Siarhei; Buryan, Petr

    2012-04-01

    A pilot scale gasification unit with novel co-current, updraft arrangement in the first stage and counter-current downdraft in the second stage was developed and exploited for studying effects of two stage gasification in comparison with one stage gasification of biomass (wood pellets) on fuel gas composition and attainable gas purity. Significant producer gas parameters (gas composition, heating value, content of tar compounds, content of inorganic gas impurities) were compared for the two stage and the one stage method of the gasification arrangement with only the upward moving bed (co-current updraft). The main novel features of the gasifier conception include grate-less reactor, upward moving bed of biomass particles (e.g. pellets) by means of a screw elevator with changeable rotational speed and gradual expanding diameter of the cylindrical reactor in the part above the upper end of the screw. The gasifier concept and arrangement are considered convenient for thermal power range 100-350 kW(th). The second stage of the gasifier served mainly for tar compounds destruction/reforming by increased temperature (around 950°C) and for gasification reaction of the fuel gas with char. The second stage used additional combustion of the fuel gas by preheated secondary air for attaining higher temperature and faster gasification of the remaining char from the first stage. The measurements of gas composition and tar compound contents confirmed superiority of the two stage gasification system, drastic decrease of aromatic compounds with two and higher number of benzene rings by 1-2 orders. On the other hand the two stage gasification (with overall ER=0.71) led to substantial reduction of gas heating value (LHV=3.15 MJ/Nm(3)), elevation of gas volume and increase of nitrogen content in fuel gas. The increased temperature (>950°C) at the entrance to the char bed caused also substantial decrease of ammonia content in fuel gas. The char with higher content of ash leaving the

  12. Two-stage fixed-bed gasifier with selectable middle gas off-take point

    DOEpatents

    Strickland, Larry D.; Bissett, Larry A.

    1992-01-01

    A two-stage fixed bed coal gasifier wherein an annular region is in registry with a gasification zone underlying a devolatilization zone for extracting a side stream of high temperature substantially tar-free gas from the gasifier. A vertically displaceable skirt means is positioned within the gasifier to define the lower portion of the annular region so that vertical displacement of the skirt means positions the inlet into the annular region in a selected location within or in close proximity to the gasification zone for providing a positive control over the composition of the side stream gas.

  13. Titanium-copper-nitride coated spacers for two-stage revision of infected total hip endoprostheses.

    PubMed

    Ellenrieder, Martin; Haenle, Maximilian; Lenz, Robert; Bader, Rainer; Mittelmeier, Wolfram

    2011-01-01

    Within the first two years after total hip arthroplasty implant-associated infection has become the second most common reason for a revision surgery. Two-stage implant exchange is frequently conducted using temporary spacers made of antibiotic-loaded cement in order to prevent a bacterial colonization on the spacer. Avoiding several disadvantages of cement spacers, a conventional hemi-endoprosthesis was equipped with a copper-containing implant coating for inhibition of bacterial biofilms. In the present paper details of this novel treatment concept are presented including a case report.

  14. Performance of two-stage fan having low-aspect-ratio first-stage rotor blading

    NASA Technical Reports Server (NTRS)

    Urasek, D. C.; Gorrell, W. T.; Cunnan, W. S.

    1979-01-01

    The NASA two stage fan was tested with a low aspect ratio first stage rotor having no midspan dampers. At design speed the fan achieved an adiabatic design efficiency of 0.846, and peak efficiencies for the first stage and rotor of 0.870 and 0.906, respectively. Peak efficiency occurred very close to the stall line. In an attempt to improve stall margin, the fan was retested with circumferentially grooved casing treatment and with a series of stator blade resets. Results showed no improvement in stall margin with casing treatment but increased to 8 percent with stator blade reset.

  15. Two-stage fluidized-bed/cyclonic agglomerating incinerator. Technology spotlight report

    SciTech Connect

    1995-08-01

    The two-stage fluidized-bed/cyclonic agglomerating incinerator combines and improves upon the fluidized-bed, agglomeration/ incineration-technology and the cyclonic-combustion technology developed at Institute of Gas Technolgy (IGT) over many years. The result is a unique and extremely flexible incinerator for solid, liquid, and gaseous wastes. The system can operate over a wide range of conditions and has a destruction and removal efficiency (DRE) greater than 99.99%. Solid inorganic contaminants are contained within aglassy matrix, rendering them benign and suitable for disposal in an ordinary landfill.

  16. Two-stage underwater image restoration based on a physical model

    NASA Astrophysics Data System (ADS)

    Wang, Nan; Qi, Lin; Dong, Junyu; Fan, Hao; Chen, Xingnan; Yu, Hui

    2017-02-01

    Underwater images are blurred due to light scattering and absorption. Image restoration is therefore important in many underwater research and practical tasks. In this paper, we propose an effective two-stage method to restore underwater scene images. Based on an underwater light propagation model, we first remove backscatter by fitting a binary quadratic function. Then we eliminate the forward scattering and non-uniform lighting attenuation using blue-green dark channel prior. The proposed method requires no additional calibration and we show its effectiveness and robustness by restoring images captured under various underwater scenes.

  17. Studies on the development and efficiency improvement of a 1.5 W at 25 K two stage pulse tube cooler

    NASA Astrophysics Data System (ADS)

    Kranthi Kumar, J.; Jacob, S.; Karunanithi, R.; Narasimham, GSVL

    2017-02-01

    A high frequency two stage pulse tube cooler (PTC) has been designed using Sage software for a JT-PTC hybrid helium recondensation system. The cold end of the first stage regenerator is anchored at 80 K using a liquid nitrogen supply. Such a thermally coupled design simplifies the design without the need for considering flow distribution between the stages and ensures that entire flow is available to produce cooling power at 25 K. The pulse tube cooler is designed for maximal utilization of the 900 W PV power provided by the Pressure Wave Generator (PWG). With the first prototype, a no load temperature of 40.4 K was achieved at a filling pressure of 24.1 bar. The effect of filling pressure on the acoustic matching of the PTC and PWG was investigated. It is observed that filling pressure has a significant effect on the PWG piston stroke amplitude. Using phasor analysis, it is shown that the phase relationship at different sections of the two stage PTC is detrimentally affected by the pulse tube volume. A scheme for achieving advantageous phasing by reducing the pulse tube volume is proposed. This involves maintaining the hot heat exchanger, inertance tube and buffer volume at 80 K. With the modification it is shown that a beneficial phase reversal across second stage Regenerator is achieved. The method is currently under experimental investigation.

  18. An operational rate control scheme for H.264 with two-stage encoding

    NASA Astrophysics Data System (ADS)

    Kwon, Do-Kyoung; Shen, Mei-Yin; Kuo, C.-C. Jay

    2005-08-01

    An operational rate control (RC) scheme based on two-stage encoding is studied in this research, where frame-layer rate control with a constant bit rate to achieve constant video quality is examined. In the first encoding stage, the R-D optimized mode decision and its associated motion estimation (RDO) as well as DCT/Q, IQ/IDCT and entropy coding are performed for all macroblocks (MBs) for a target frame using an initial quantization parameter (QP), which is the QP of its previous frame. In the second encoding stage, the residual signal from the first stage is encoded using several QP values around the initial QP. Given the target bits and distortion for the current frame, the residual signal is finally encoded using the QP determined by comparing target bits and distortion with actual bits and distortion. To reduce the additional coding complexity of the two-stage encoding, upper and lower bounds around target bits and distortion are employed to reduce the number of encoding required in the second stage. Experimental results are given to show the superior performance of two proposed rate control algorithms, where one targets at the constant bit rate while the other at constant quality.

  19. XPG Gene Polymorphisms Contribute to Colorectal Cancer Susceptibility: A Two-Stage Case-Control Study

    PubMed Central

    Hua, Rui-Xi; Zhuo, Zhen-Jian; Zhu, Jinhong; Zhang, Shao-Dan; Xue, Wen-Qiong; Zhang, Jiang-Bo; Xu, Hong-Mei; Li, Xi-Zhao; Zhang, Pei-Fen; He, Jing; Jia, Wei-Hua

    2016-01-01

    Previous studies have reported that xeroderma pigmentosum group G (XPG) gene polymorphisms may modulate colorectal cancer (CRC) susceptibility. In this study, we performed a two-stage case-control study to comprehensively investigate the associations of five polymorphisms in the XPG gene with CRC risk in 1,901 cases and 1,976 controls from Southern China, including rs2094258 C>T, rs751402 C>T, rs2296147 T>C, rs1047768 T>C and rs873601 G>A. After combining data from two stages, we found that three of the studied polymorphisms (rs2094258 C>T, rs751402 C>T, and rs873601 G>A) were significantly associated with CRC susceptibility. After adjustment for age and gender, multivariate logistic regression analysis indicated that carriers of the rs2094258 T alleles had an increased CRC risk [CT vs. CC: adjusted odds ratio (OR)=1.17, 95% confidence interval (CI)=1.01-1.36; TT vs. CC: adjusted OR=1.49, 95% CI=1.18-1.89; TT vs. CT/CC: adjusted OR=1.38, 95% CI=1.10-1.72]. Likely, rs873601 A allele also conferred increased CRC susceptibility. In contrast, a protective association was identified between rs751402 C>T polymorphism and the risk of CRC. In summary, our results indicated that these three polymorphisms were found to associate with CRC susceptibility in a Southern Chinese population. PMID:27698911

  20. A two-stage linear discriminant analysis via QR-decomposition.

    PubMed

    Ye, Jieping; Li, Qi

    2005-06-01

    Linear Discriminant Analysis (LDA) is a well-known method for feature extraction and dimension reduction. It has been used widely in many applications involving high-dimensional data, such as image and text classification. An intrinsic limitation of classical LDA is the so-called singularity problems; that is, it fails when all scatter matrices are singular. Many LDA extensions were proposed in the past to overcome the singularity problems. Among these extensions, PCA+LDA, a two-stage method, received relatively more attention. In PCA+LDA, the LDA stage is preceded by an intermediate dimension reduction stage using Principal Component Analysis (PCA). Most previous LDA extensions are computationally expensive, and not scalable, due to the use of Singular Value Decomposition or Generalized Singular Value Decomposition. In this paper, we propose a two-stage LDA method, namely LDA/QR, which aims to overcome the singularity problems of classical LDA, while achieving efficiency and scalability simultaneously. The key difference between LDA/QR and PCA+LDA lies in the first stage, where LDA/QR applies QR decomposition to a small matrix involving the class centroids, while PCA+LDA applies PCA to the total scatter matrix involving all training data points. We further justify the proposed algorithm by showing the relationship among LDA/QR and previous LDA methods. Extensive experiments on face images and text documents are presented to show the effectiveness of the proposed algorithm.

  1. Suppression of sludge formation by two-stage hydrocracking of vacuum residue at high conversion

    SciTech Connect

    Mochida, I.; Zhao, X.; Sakanishi, K. )

    1990-12-01

    This paper reports on hydrocracked products from Arabian light vacuum residue at high conversion into distillate ({gt}50%) that were analyzed in order to reveal how sludge formation was suppressed in the two-stage reaction. Although the asphaltene in the starting residue was highly soluble in the starting maltene in spite of is largest molecular weight, single-stage hydrocracking at a higher temperature of 420{degrees}C increased the aromaticity of the asphaltene through extensive deaklylation and dehydrogenation, leading to sludge formation. In contrast, two-stage hydrocracking at 390{degrees}C--3 h/420{degrees}C--1/h accomplished effective depolymerization of the asphaltene, high conversion being achieved without sludge. The carbon aromaticity (f{sub a}) of the produced asphaltene was maintained rather low, although its amount in the product was much the same regardless of the reaction conditions. The heptane-soluble maltenes in the hydrocracked oils exhibited variable dissolving abilities against the asphaltene according to the content and aromaticity of its aromatic fraction, also influencing sludge formation. Hydrocracking produced paraffins through the hydrogenative deaklylation of long-chain alkylbenzenes, decreasing f{sub a} and the dissolving ability of the hydrocracked maltene.

  2. Batch (one- and two-stage) production of biodiesel fuel from rapeseed oil.

    PubMed

    Jeong, Gwi-Taek; Park, Don-Hee

    2006-01-01

    Biodiesel fuel is an alternative and renewable energy source, which may help to reduce air pollution, as well as our dependence on petroleum for energy. Several processes have already been developed for the production of biodiesel. Alkali-catalyzed transesterification with short-chain alcohols, for example, generates high yields of methyl esters in short reaction times. In this study, we have evaluated the efficacy of batch (one- and two-stage) transesterification of rapeseed oil in the production of rapeseed methyl ester. The conversion of rapeseed oil exhibited similar reaction patterns and yields in 30- and 1-L reaction systems. Approximately 98% of the rapeseed oil was converted at 400 rpm within 20 min, under the following conditions: 1% (w/w) KOH, 1:10 methanol molar ratio, and at 60 degrees C. In the 30-L, two-stage transesterification process, approx 98.5% of the rapeseed oil was converted at a 1:4.5 molar ratio and 1% (w/w) KOH at 60 degrees C for 30 min (first reaction condition), and at a 1:1 molar ratio and 0.2% (w/w) KOH at 60 degrees C for 30 min (second reaction condition).

  3. Batch (one- and two-stage) production of biodiesel fuel from rapeseed oil.

    PubMed

    Jeong, Gwi-Taek; Park, Don-Hee

    2006-03-01

    Biodiesel fuel is an alternative and renewable energy source, which may help to reduce air pollution, as well as our dependence on petroleum for energy. Several processes have already been developed for the production of biodiesel. Alkali-catalyzed transesterification with short-chain alcohols, for example, generates high yields of methyl esters in short reaction times. In this study, we have evaluated the efficacy of batch (one- and two-stage) transesterification of rapeseed oil in the production of rapeseed methyl ester. The conversion of rapeseed oil exhibited similar reaction patterns and yields in 30- and 1-L reaction systems. Approximately 98% of the rapeseed oil was converted at 400 rpm within 20 min, under the following conditions: 1% (w/w) KOH, 1ratio10 methanol molar ratio, and at 60 degrees C. In the 30-L, two-stage transesterification process, approx 98.5% of the rapeseed oil was converted at a 1ratio4.5 molar ratio and 1% (w/w) KOH at 60 degrees C for 30 min (first reaction condition), and at a 1ratio1 molar ratio and 0.2% (w/w) KOH at 60 degrees C for 30 min (second reaction condition).

  4. Two stage, low temperature, catalyzed fluidized bed incineration with in situ neutralization for radioactive mixed wastes

    SciTech Connect

    Wade, J.F.; Williams, P.M.

    1995-05-17

    A two stage, low temperature, catalyzed fluidized bed incineration process is proving successful at incinerating hazardous wastes containing nuclear material. The process operates at 550{degrees}C and 650{degrees}C in its two stages. Acid gas neutralization takes place in situ using sodium carbonate as a sorbent in the first stage bed. The feed material to the incinerator is hazardous waste-as defined by the Resource Conservation and Recovery Act-mixed with radioactive materials. The radioactive materials are plutonium, uranium, and americium that are byproducts of nuclear weapons production. Despite its low temperature operation, this system successfully destroyed poly-chlorinated biphenyls at a 99.99992% destruction and removal efficiency. Radionuclides and volatile heavy metals leave the fluidized beds and enter the air pollution control system in minimal amounts. Recently collected modeling and experimental data show the process minimizes dioxin and furan production. The report also discusses air pollution, ash solidification, and other data collected from pilot- and demonstration-scale testing. The testing took place at Rocky Flats Environmental Technology Site, a US Department of Energy facility, in the 1970s, 1980s, and 1990s.

  5. On-line monitoring of a two-stage anaerobic digestion process using a BOD analyzer.

    PubMed

    Liu, Jing; Olsson, Gustaf; Mattiasson, Bo

    2004-04-29

    A computer-controlled biochemical oxygen demand (BOD) analyzer has been developed for fast estimation of biochemical oxygen demand (BODst) automatically with the purpose of on-line monitoring of a process for conversion of biomass under field conditions. The instrument was tested by on-line monitoring of the connecting stream between two stages of a two-stage anaerobic process in laboratory scale. In the first stage, hydrolysis of sugar beet leaves and its conversion into volatile fatty acids and other low molecular weight substrates took place. The effluent from the first reactor was used as a feed stream to the second stage, i.e. an anaerobic contact reactor. The feed stream was sampled intermittently, diluted and analyzed by the BOD analyzer automatically in order to estimate the organic loading rate to the reactor. The results from this study demonstrated that the BOD analyzer could be a stand-alone and promising sensor device for rapid on-line monitoring of easily biodegradable organic substances in biological treatment processes.

  6. Aerobic and two-stage anaerobic-aerobic sludge digestion with pure oxygen and air aeration.

    PubMed

    Zupancic, Gregor D; Ros, Milenko

    2008-01-01

    The degradability of excess activated sludge from a wastewater treatment plant was studied. The objective was establishing the degree of degradation using either air or pure oxygen at different temperatures. Sludge treated with pure oxygen was degraded at temperatures from 22 degrees C to 50 degrees C while samples treated with air were degraded between 32 degrees C and 65 degrees C. Using air, sludge is efficiently degraded at 37 degrees C and at 50-55 degrees C. With oxygen, sludge was most effectively degraded at 38 degrees C or at 25-30 degrees C. Two-stage anaerobic-aerobic processes were studied. The first anaerobic stage was always operated for 5 days HRT, and the second stage involved aeration with pure oxygen and an HRT between 5 and 10 days. Under these conditions, there is 53.5% VSS removal and 55.4% COD degradation at 15 days HRT - 5 days anaerobic, 10 days aerobic. Sludge digested with pure oxygen at 25 degrees C in a batch reactor converted 48% of sludge total Kjeldahl nitrogen to nitrate. Addition of an aerobic stage with pure oxygen aeration to the anaerobic digestion enhances ammonium nitrogen removal. In a two-stage anaerobic-aerobic sludge digestion process within 8 days HRT of the aerobic stage, the removal of ammonium nitrogen was 85%.

  7. Two-stage fermentation process for enhanced mannitol production using Candida magnoliae mutant R9.

    PubMed

    Savergave, Laxman S; Gadre, Ramchandra V; Vaidya, Bhalchandra K; Jogdand, Vitthal V

    2013-02-01

    Mutants of Candida magnoliae NCIM 3470 were generated by treatment of ultra-violet radiations, ethyl methyl sulphonate and N-methyl-N'-nitro-N-nitrosoguanidine. Mutants with higher reductase activity were screened by means of 2,3,5-triphenyl tetrazolium chloride agar plate assay. Among the screened mutants, the mutant R9 produced maximum mannitol (i.e. 46 g l(-1)) in liquid fermentation medium containing 250 g l(-1) glucose and hence was selected for further experiments. Preliminary optimization studies were carried out on shake-flask level which increased the mannitol production to 60 g l(-1) in liquid fermentation medium containing 300 g l(-1) glucose. A two-stage fermentation process comprising of growth phase and production phase was employed. During the growth phase, glucose was supplemented and aerobic conditions were maintained. Thereafter, the production phase was initiated by supplementing fructose and switching to anaerobic conditions by discontinuing aeration and decreasing the speed of agitation. The strategy of two-stage fermentation significantly enhanced the production of mannitol up to 240 g l(-1), which is the highest among all fermentative production processes and corresponds to 81 % yield and 4 g l(-1 )h(-1) productivity without formation of any by-product.

  8. Prediction of bio-methane potential and two-stage anaerobic digestion of starfish.

    PubMed

    Kim, Dong-Hoon; Cha, Jaehwan; Lee, Mo-Kwon; Kim, Hyun-Woo; Kim, Mi-Sun

    2013-08-01

    The present work reports the first ever evaluation of the biological CH₄ potential (BMP) of starfish, classified as invasive species. Since starfish contain a large amount of inorganic matter, only the supernatant obtained through grinding and centrifugation was used for BMP test. By applying response surface methodology, the individual and interactive effects of three parameters, inoculum/substrate ratios, substrate concentrations, and buffer capacities on CH₄ production were investigated, and the maximum CH₄ yield of 334 mL CH₄/g COD was estimated. In addition, continuous CH₄ production was attempted using a two-stage (acidogenic sequencing batch reactor+methanogenic up-flow anaerobic sludge blanket reactor (UASBr)) fermentation process. Acidification efficiency was maximized at 2 days of hydraulic retention time with valerate, butyrate, and acetate as main acids, and these were converted to CH₄ with showing 296 mL CH₄/g COD added. Overall, the two-stage fermentation process could convert 44% of organic content in whole starfish to CH₄.

  9. The feasibility of using a two-stage autotrophic nitrogen removal process to treat sewage.

    PubMed

    Ma, Bin; Zhang, Shujun; Zhang, Liang; Yi, Peng; Wang, Junmin; Wang, Shuying; Peng, Yongzhen

    2011-09-01

    The feasibility of using a two-stage autotrophic nitrogen removal process to treat sewage was examined in this study. The obtained results showed that total nitrogen (TN) could be efficiently removed by 88.38% when influent TN and chemical oxygen demand (COD) were 45.87 and 44.40 mg/L, respectively. In the first stage, nitritation was instantly achieved by the bioaugmentation strategy, and can be maintained under limited oxygen condition (below 0.2mg/L). The ratio of nitrite to ammonium in the effluent of the nitritation reactor can be controlled at approximate 1.0 by adjusting aeration rate. In the second stage, anammox was realized in the upflow anaerobic sludge blanket (UASB) reactor, where the total nitrogen removal rate was 0.40 kg Nm(-3)d(-1) under limited-substrate condition. Therefore, the organic matter in sewage can be firstly concentrated in biomass which could generate biogas (energy). Then, nitrogen in sewage could be removed in a two-stage autotrophic nitrogen removal process.

  10. Performance of two-stage vegetable waste anaerobic digestion depending on varying recirculation rates.

    PubMed

    Zuo, Zhuang; Wu, Shubiao; Zhang, Wanqin; Dong, Renjie

    2014-06-01

    Vegetable waste, which characterized by high moisture content, was evaluated as a substrate for biogas production. The effects of recirculation rate (RR) on the performance of two-stage anaerobic digestion were investigated. The system was operated at an organic loading rate of 1.7 g VS/L/d with varying RRs (0, 0.6, 1, and 1.4). Results demonstrated that volumetric biogas production rates in acidogenic reactor increased from approximately 0.2 7 L/L/d to 0.97 L/L/d, when pH is increased from approximately 5.1 to 6.7. These indicate that recirculation of alkaline effluent from the methanogenic reactor helps create a favorable condition for biogas production in the acidogenic reactor. The decrease in chemical oxygen demand (COD) concentrations from approximately 21,000 mg/L to 6800 mg/L was also observed in the acidogenic reactor. This condition may be attributed to dilution under recirculation. The dynamics between hydrolysis and methanogenesis under recirculation indicated that mass transfer capacity between two-stage reactors improved.

  11. Two-Stage Orthogonal Least Squares Methods for Neural Network Construction.

    PubMed

    Zhang, Long; Li, Kang; Bai, Er-Wei; Irwin, George W

    2015-08-01

    A number of neural networks can be formulated as the linear-in-the-parameters models. Training such networks can be transformed to a model selection problem where a compact model is selected from all the candidates using subset selection algorithms. Forward selection methods are popular fast subset selection approaches. However, they may only produce suboptimal models and can be trapped into a local minimum. More recently, a two-stage fast recursive algorithm (TSFRA) combining forward selection and backward model refinement has been proposed to improve the compactness and generalization performance of the model. This paper proposes unified two-stage orthogonal least squares methods instead of the fast recursive-based methods. In contrast to the TSFRA, this paper derives a new simplified relationship between the forward and the backward stages to avoid repetitive computations using the inherent orthogonal properties of the least squares methods. Furthermore, a new term exchanging scheme for backward model refinement is introduced to reduce computational demand. Finally, given the error reduction ratio criterion, effective and efficient forward and backward subset selection procedures are proposed. Extensive examples are presented to demonstrate the improved model compactness constructed by the proposed technique in comparison with some popular methods.

  12. Pilot-scale two-stage process: a combination of acidogenic hydrogenesis and methanogenesis.

    PubMed

    Han, S K; Kim, S H; Kim, H W; Shin, H S

    2005-01-01

    This study was performed to optimize both acidogenic hydrogenesis and methanogenesis, and then to develop a pilot-scale two-stage process producing not only CH4 but also H2. Firstly, acidogenic hydrogenesis of food waste was examined in pilot-scale leaching-bed reactors using dilution rate (D) as a tool to improve the environmental conditions. The maximum efficiency of 71.4% was obtained by adjusting D from 4.5 to 2.5 d(-1) depending on the state of degradation. Secondly, the wastewater from acidogenic hydrogenesis was converted to CH4 in a pilot-scale UASB reactor. The COD removal efficiency exceeded 95% up to the loading rates of 13.1 g COD/Ld, which corresponded to HRT of 0.25 d (6 h). Lastly, a pilot-scale two-stage process was devised based on a combination of acidogenic hydrogenesis and methanogenesis. Over 120 days, the pilot-scale process resulted in large VS reduction of 70.9% at the high loading rate of 12.5 kg VS/m3/d in a short SRT of 8 days.

  13. Evaluation of a two-stage biofilter for treatment of POTW waste air

    SciTech Connect

    Chitwood, D.E.; Devinny, J.S.; Reynolds, F.E. Jr.

    1999-09-30

    Recent efforts have been made to reduce releases of air toxics and smog precursors from wastewater treatment plants. Hydrogen sulfide is commonly the primary odor and is an important target for removal. Its oxidation, however, generates sulfuric acid and sometimes elemental sulfur, which can create substantial operational problems for biofilters. Declining pH may inhibit the organisms that degrade compounds other than hydrogen sulfide and may hasten aging of organic biofilter media. A two-stage biofilter has been designed and installed at the Ohio Valley Sanitary District wastewater treatment plant. The first stage is an enclosed system with a medium of small, inert, porous stones. It is called an acid gas biofilter. The second stage is a section of a traditional open biofilter filled with wood chips. The acid gas biofilter effectively removed H{sub 2}S and volatile organic compounds while causing much lower headloss than traditional biofilters. However, considerable flow heterogeneity in both the acid gas biofilter and the wood chip biofilter was observed. The two-stage system presumably will have a longer bed life because the first stage bed is inert and because the second stage is protected from acidification by removal of H{sub 2}S in the first stage.

  14. A two-stage series diode for intense large-area moderate pulsed X rays production.

    PubMed

    Lai, Dingguo; Qiu, Mengtong; Xu, Qifu; Su, Zhaofeng; Li, Mo; Ren, Shuqing; Huang, Zhongliang

    2017-01-01

    This paper presents a method for moderate pulsed X rays produced by a series diode, which can be driven by high voltage pulse to generate intense large-area uniform sub-100-keV X rays. A two stage series diode was designed for Flash-II accelerator and experimentally investigated. A compact support system of floating converter/cathode was invented, the extra cathode is floating electrically and mechanically, by withdrawing three support pins several milliseconds before a diode electrical pulse. A double ring cathode was developed to improve the surface electric field and emission stability. The cathode radii and diode separation gap were optimized to enhance the uniformity of X rays and coincidence of the two diode voltages based on the simulation and theoretical calculation. The experimental results show that the two stage series diode can work stably under 700 kV and 300 kA, the average energy of X rays is 86 keV, and the dose is about 296 rad(Si) over 615 cm(2) area with uniformity 2:1 at 5 cm from the last converter. Compared with the single diode, the average X rays' energy reduces from 132 keV to 88 keV, and the proportion of sub-100-keV photons increases from 39% to 69%.

  15. A two-stage series diode for intense large-area moderate pulsed X rays production

    NASA Astrophysics Data System (ADS)

    Lai, Dingguo; Qiu, Mengtong; Xu, Qifu; Su, Zhaofeng; Li, Mo; Ren, Shuqing; Huang, Zhongliang

    2017-01-01

    This paper presents a method for moderate pulsed X rays produced by a series diode, which can be driven by high voltage pulse to generate intense large-area uniform sub-100-keV X rays. A two stage series diode was designed for Flash-II accelerator and experimentally investigated. A compact support system of floating converter/cathode was invented, the extra cathode is floating electrically and mechanically, by withdrawing three support pins several milliseconds before a diode electrical pulse. A double ring cathode was developed to improve the surface electric field and emission stability. The cathode radii and diode separation gap were optimized to enhance the uniformity of X rays and coincidence of the two diode voltages based on the simulation and theoretical calculation. The experimental results show that the two stage series diode can work stably under 700 kV and 300 kA, the average energy of X rays is 86 keV, and the dose is about 296 rad(Si) over 615 cm2 area with uniformity 2:1 at 5 cm from the last converter. Compared with the single diode, the average X rays' energy reduces from 132 keV to 88 keV, and the proportion of sub-100-keV photons increases from 39% to 69%.

  16. Numerical simulation and analysis of the flow in a two-staged axial fan

    NASA Astrophysics Data System (ADS)

    Xu, J. Q.; Dou, H. S.; Jia, H. X.; Chen, X. P.; Wei, Y. K.; Dong, M. W.

    2016-05-01

    In this paper, numerical simulation was performed for the internal three-dimensional turbulent flow field in the two-stage axial fan using steady three-dimensional in-compressible Navier-Stokes equations coupled with the Realizable turbulent model. The numerical simulation results of the steady analysis were combined with the flow characteristics of two- staged axial fan, the influence of the mutual effect between the blade and the vane on the flow of the two inter-stages was analyzed emphatically. This paper studied how the flow field distribution in inter-stage is influenced by the wake interaction and potential flow interaction of mutual effect in the impeller-vane inter-stage and the vane-impeller inter-stage. The results showed that: Relatively, wake interaction has an advantage over potential flow interaction in the impeller-vane inter-stage; potential flow interaction has an advantage over wake interaction in the vane-impeller inter-stage. In other words, distribution of flow field in the two interstages is determined by the rotating component.

  17. An integrated two-stage support vector machine approach to forecast inundation maps during typhoons

    NASA Astrophysics Data System (ADS)

    Jhong, Bing-Chen; Wang, Jhih-Huang; Lin, Gwo-Fong

    2017-04-01

    During typhoons, accurate forecasts of hourly inundation depths are essential for inundation warning and mitigation. Due to the lack of observed data of inundation maps, sufficient observed data are not available for developing inundation forecasting models. In this paper, the inundation depths, which are simulated and validated by a physically based two-dimensional model (FLO-2D), are used as a database for inundation forecasting. A two-stage inundation forecasting approach based on Support Vector Machine (SVM) is proposed to yield 1- to 6-h lead-time inundation maps during typhoons. In the first stage (point forecasting), the proposed approach not only considers the rainfall intensity and inundation depth as model input but also simultaneously considers cumulative rainfall and forecasted inundation depths. In the second stage (spatial expansion), the geographic information of inundation grids and the inundation forecasts of reference points are used to yield inundation maps. The results clearly indicate that the proposed approach effectively improves the forecasting performance and decreases the negative impact of increasing forecast lead time. Moreover, the proposed approach is capable of providing accurate inundation maps for 1- to 6-h lead times. In conclusion, the proposed two-stage forecasting approach is suitable and useful for improving the inundation forecasting during typhoons, especially for long lead times.

  18. Two-stage high temperature sludge gasification using the waste heat from hot blast furnace slags.

    PubMed

    Sun, Yongqi; Zhang, Zuotai; Liu, Lili; Wang, Xidong

    2015-12-01

    Nowadays, disposal of sewage sludge from wastewater treatment plants and recovery of waste heat from steel industry, become two important environmental issues and to integrate these two problems, a two-stage high temperature sludge gasification approach was investigated using the waste heat in hot slags herein. The whole process was divided into two stages, i.e., the low temperature sludge pyrolysis at ⩽ 900°C in argon agent and the high temperature char gasification at ⩾ 900°C in CO2 agent, during which the heat required was supplied by hot slags in different temperature ranges. Both the thermodynamic and kinetic mechanisms were identified and it was indicated that an Avrami-Erofeev model could best interpret the stage of char gasification. Furthermore, a schematic concept of this strategy was portrayed, based on which the potential CO yield and CO2 emission reduction achieved in China could be ∼1.92∗10(9)m(3) and 1.93∗10(6)t, respectively.

  19. Biological hydrogen and methane production from bagasse bioethanol fermentation residues using a two-stage bioprocess.

    PubMed

    Cheng, Hai-Hsuan; Whang, Liang-Ming; Chung, Man-Chien; Chan, Kun-Chi

    2016-06-01

    This study investigated the recovery of H2 and CH4 from bagasse bioethanol fermentation residues (bagasse BEFR) using a two-stage bioprocess. In the hydrogen fermentation bioreactor (HFB), carbohydrate removal efficiency was maintained at 82-93% and the highest hydrogen yield was 8.24mL/gCOD at volumetric loading rate (VLR) of 80kgCOD/m(3)/day. The results indicated a positive correlation between hydrogen yield and butyrate-to-acetate ratio, which might be due to the mechanisms of lactate/acetate utilization for hydrogen production and acetogenesis occurring in the HFB. Remaining volatile fatty acids and alcohols in the HFB effluent were further utilized for methane production in methane fermentation bioreactor (MFB), in which the highest methane yield of 345.2mL/gCOD was attained at VLR of 2.5kgCOD/m(3)/day. Overall, the two-stage bioprocess achieved a maximum COD removal of 81% from bagasse BEFR, and converted 0.3% and 72.8% of COD in the forms of H2 and CH4, respectively.

  20. Estimating accuracy of land-cover composition from two-stage cluster sampling

    USGS Publications Warehouse

    Stehman, S.V.; Wickham, J.D.; Fattorini, L.; Wade, T.D.; Baffetta, F.; Smith, J.H.

    2009-01-01

    Land-cover maps are often used to compute land-cover composition (i.e., the proportion or percent of area covered by each class), for each unit in a spatial partition of the region mapped. We derive design-based estimators of mean deviation (MD), mean absolute deviation (MAD), root mean square error (RMSE), and correlation (CORR) to quantify accuracy of land-cover composition for a general two-stage cluster sampling design, and for the special case of simple random sampling without replacement (SRSWOR) at each stage. The bias of the estimators for the two-stage SRSWOR design is evaluated via a simulation study. The estimators of RMSE and CORR have small bias except when sample size is small and the land-cover class is rare. The estimator of MAD is biased for both rare and common land-cover classes except when sample size is large. A general recommendation is that rare land-cover classes require large sample sizes to ensure that the accuracy estimators have small bias. ?? 2009 Elsevier Inc.

  1. Optimal adaptive two-stage designs for early phase II clinical trials.

    PubMed

    Shan, Guogen; Wilding, Gregory E; Hutson, Alan D; Gerstenberger, Shawn

    2016-04-15

    Simon's optimal two-stage design has been widely used in early phase clinical trials for Oncology and AIDS studies with binary endpoints. With this approach, the second-stage sample size is fixed when the trial passes the first stage with sufficient activity. Adaptive designs, such as those due to Banerjee and Tsiatis (2006) and Englert and Kieser (2013), are flexible in the sense that the second-stage sample size depends on the response from the first stage, and these designs are often seen to reduce the expected sample size under the null hypothesis as compared with Simon's approach. An unappealing trait of the existing designs is that they are not associated with a second-stage sample size, which is a non-increasing function of the first-stage response rate. In this paper, an efficient intelligent process, the branch-and-bound algorithm, is used in extensively searching for the optimal adaptive design with the smallest expected sample size under the null, while the type I and II error rates are maintained and the aforementioned monotonicity characteristic is respected. The proposed optimal design is observed to have smaller expected sample sizes compared to Simon's optimal design, and the maximum total sample size of the proposed adaptive design is very close to that from Simon's method. The proposed optimal adaptive two-stage design is recommended for use in practice to improve the flexibility and efficiency of early phase therapeutic development.

  2. Development of a Two-Stage Microalgae Dewatering Process – A Life Cycle Assessment Approach

    PubMed Central

    Soomro, Rizwan R.; Zeng, Xianhai; Lu, Yinghua; Lin, Lu; Danquah, Michael K.

    2016-01-01

    Even though microalgal biomass is leading the third generation biofuel research, significant effort is required to establish an economically viable commercial-scale microalgal biofuel production system. Whilst a significant amount of work has been reported on large-scale cultivation of microalgae using photo-bioreactors and pond systems, research focus on establishing high performance downstream dewatering operations for large-scale processing under optimal economy is limited. The enormous amount of energy and associated cost required for dewatering large-volume microalgal cultures has been the primary hindrance to the development of the needed biomass quantity for industrial-scale microalgal biofuels production. The extremely dilute nature of large-volume microalgal suspension and the small size of microalgae cells in suspension create a significant processing cost during dewatering and this has raised major concerns towards the economic success of commercial-scale microalgal biofuel production as an alternative to conventional petroleum fuels. This article reports an effective framework to assess the performance of different dewatering technologies as the basis to establish an effective two-stage dewatering system. Bioflocculation coupled with tangential flow filtration (TFF) emerged a promising technique with total energy input of 0.041 kWh, 0.05 kg CO2 emissions and a cost of $ 0.0043 for producing 1 kg of microalgae biomass. A streamlined process for operational analysis of two-stage microalgae dewatering technique, encompassing energy input, carbon dioxide emission, and process cost, is presented. PMID:26904075

  3. Development and optimization of a two-stage gasifier for heat and power production

    NASA Astrophysics Data System (ADS)

    Kosov, V. V.; Zaichenko, V. M.

    2016-11-01

    The major methods of biomass thermal conversion are combustion in excess oxygen, gasification in reduced oxygen, and pyrolysis in the absence of oxygen. The end products of these methods are heat, gas, liquid and solid fuels. From the point of view of energy production, none of these methods can be considered optimal. A two-stage thermal conversion of biomass based on pyrolysis as the first stage and pyrolysis products cracking as the second stage can be considered the optimal method for energy production that allows obtaining synthesis gas consisting of hydrogen and carbon monoxide and not containing liquid or solid particles. On the base of the two stage cracking technology, there was designed an experimental power plant of electric power up to 50 kW. The power plant consists of a thermal conversion module and a gas engine power generator adapted for operation on syngas. Purposes of the work were determination of an optimal operation temperature of the thermal conversion module and an optimal mass ratio of processed biomass and charcoal in cracking chamber of the thermal conversion module. Experiments on the pyrolysis products cracking at various temperatures show that the optimum cracking temperature is equal to 1000 °C. From the results of measuring the volume of gas produced in different mass ratios of charcoal and wood biomass processed, it follows that the maximum volume of the gas in the range of the mass ratio equal to 0.5-0.6.

  4. Two-stage estimation for multivariate recurrent event data with a dependent terminal event.

    PubMed

    Chen, Chyong-Mei; Chuang, Ya-Wen; Shen, Pao-Sheng

    2015-03-01

    Recurrent event data arise in longitudinal follow-up studies, where each subject may experience the same type of events repeatedly. The work in this article is motivated by the data from a study of repeated peritonitis for patients on peritoneal dialysis. Due to the aspects of medicine and cost, the peritonitis cases were classified into two types: Gram-positive and non-Gram-positive peritonitis. Further, since the death and hemodialysis therapy preclude the occurrence of recurrent events, we face multivariate recurrent event data with a dependent terminal event. We propose a flexible marginal model, which has three characteristics: first, we assume marginal proportional hazard and proportional rates models for terminal event time and recurrent event processes, respectively; second, the inter-recurrences dependence and the correlation between the multivariate recurrent event processes and terminal event time are modeled through three multiplicative frailties corresponding to the specified marginal models; third, the rate model with frailties for recurrent events is specified only on the time before the terminal event. We propose a two-stage estimation procedure for estimating unknown parameters. We also establish the consistency of the two-stage estimator. Simulation studies show that the proposed approach is appropriate for practical use. The methodology is applied to the peritonitis cohort data that motivated this study.

  5. Two-stage path planning approach for solving multiple spacecraft reconfiguration maneuvers

    NASA Astrophysics Data System (ADS)

    Aoude, Georges S.; How, Jonathan P.; Garcia, Ian M.

    2008-12-01

    The paper presents a two-stage approach for designing optimal reconfiguration maneuvers for multiple spacecraft in close proximity. These maneuvers involve well-coordinated and highly-coupled motions of the entire fleet of spacecraft while satisfying an arbitrary number of constraints. This problem is complicated by the nonlinearity of the attitude dynamics, the non-convexity of some of the constraints, and the coupling that exists in some of the constraints between the positions and attitudes of all spacecraft. While there has been significant research to solve for the translation and/or rotation trajectories for the multiple spacecraft reconfiguration problem, the approach presented in this paper is more general and on a larger scale than the problems considered previously. The essential feature of the solution approach is the separation into two stages, the first using a simplified planning approach to obtain a feasible solution, which is then significantly improved using a smoothing stage. The first stage is solved using a bidirectional Rapidly-exploring Random Tree (RRT) planner. Then the second step optimizes the trajectories by solving an optimal control problem using the Gauss pseudospectral method (GPM). Several examples are presented to demonstrate the effectiveness of the approach for designing spacecraft reconfiguration maneuvers.

  6. Two-stage k-sample designs for the ordered alternative problem.

    PubMed

    Shan, Guogen; Hutson, Alan D; Wilding, Gregory E

    2012-01-01

    In preclinical studies and clinical dose-ranging trials, the Jonckheere-Terpstra test is widely used in the assessment of dose-response relationships. Hewett and Spurrier (1979) presented a two-stage analog of the test in the context of large sample sizes. In this paper, we propose an exact test based on Simon's minimax and optimal design criteria originally used in one-arm phase II designs based on binary endpoints. The convergence rate of the joint distribution of the first and second stage test statistics to the limiting distribution is studied, and design parameters are provided for a variety of assumed alternatives. The behavior of the test is also examined in the presence of ties, and the proposed designs are illustrated through application in the planning of a hypercholesterolemia clinical trial. The minimax and optimal two-stage procedures are shown to be preferable as compared with the one-stage procedure because of the associated reduction in expected sample size for given error constraints.

  7. Design of adaptive two-stage double-arm clinical trials for dichotomous variables.

    PubMed

    Jiang, Zhiwei; Xue, Fubo; Li, Chanjuan; Wang, Ling; Cai, Hongwei; Zhang, Chunmao; Xia, Jielai

    2010-05-01

    It is well known that flexibility is one of the major advantages of an adaptive two-stage design, and the intended adaptation should be as preplanned as possible to maintain the integrity of the clinical trial. The design of adaptive two-stage double-arm clinical trials for dichotomous variables was proposed by simulation and forecasting procedure at the planning stage. To further ensure the integrity of the clinical trial, the sample size scheme for each scenario, which was supposed to be based on the first stage, was provided in the protocol by Monte Carlo simulation. In addition, the study parameters were determined by comparing the assessment indexes such as total sample size, expected sample size and the test power at the first stage. Furthermore, Fisher's combination test and pooled data analysis were considered and compared through the simulation. The latter, which has the larger overall power and the better overall type I error control, with the same sample size was adopted for further simulation and statistical analysis in the clinical trial.

  8. One-stage and two-stage designs for phase II clinical trials with survival endpoints.

    PubMed

    Whitehead, John

    2014-09-28

    This work is motivated by trials in rapidly lethal cancers or cancers for which measuring shrinkage of tumours is infeasible. In either case, traditional phase II designs focussing on tumour response are unsuitable. Usually, tumour response is considered as a substitute for the more relevant but longer-term endpoint of death. In rapidly lethal cancers such as pancreatic cancer, there is no need to use a surrogate, as the definitive endpoint is (sadly) available so soon. In uveal cancer, there is no counterpart to tumour response, and so, mortality is the only realistic response available. Cytostatic cancer treatments do not seek to kill tumours, but to mitigate their effects. Trials of such therapy might also be based on survival times to death or progression, rather than on tumour shrinkage. Phase II oncology trials are often conducted with all study patients receiving the experimental therapy, and this approach is considered here. Simple extensions of one-stage and two-stage designs based on binary responses are presented. Outcomes based on survival past a small number of landmark times are considered: here, the case of three such times is explored in examples. This approach allows exact calculations to be made for both design and analysis purposes. Simulations presented here show that calculations based on normal approximations can lead to loss of power when sample sizes are small. Two-stage versions of the procedure are also suggested.

  9. Rules and mechanisms for efficient two-stage learning in neural circuits.

    PubMed

    Teşileanu, Tiberiu; Ölveczky, Bence; Balasubramanian, Vijay

    2017-04-04

    Trial-and-error learning requires evaluating variable actions and reinforcing successful variants. In songbirds, vocal exploration is induced by LMAN, the output of a basal ganglia-related circuit that also contributes a corrective bias to the vocal output. This bias is gradually consolidated in RA, a motor cortex analogue downstream of LMAN. We develop a new model of such two-stage learning. Using stochastic gradient descent, we derive how the activity in 'tutor' circuits (e.g., LMAN) should match plasticity mechanisms in 'student' circuits (e.g., RA) to achieve efficient learning. We further describe a reinforcement learning framework through which the tutor can build its teaching signal. We show that mismatches between the tutor signal and the plasticity mechanism can impair learning. Applied to birdsong, our results predict the temporal structure of the corrective bias from LMAN given a plasticity rule in RA. Our framework can be applied predictively to other paired brain areas showing two-stage learning.

  10. Occurrence of two-stage hardening in C-Mn steel wire rods containing pearlitic microstructure

    NASA Astrophysics Data System (ADS)

    Singh, Balbir; Sahoo, Gadadhar; Saxena, Atul

    2016-09-01

    The 8 and 10 mm diameter wire rods intended for use as concrete reinforcement were produced/ hot rolled from C-Mn steel chemistry containing various elements within the range of C:0.55-0.65, Mn:0.85-1.50, Si:0.05-0.09, S:0.04 max, P:0.04 max and N:0.006 max wt%. Depending upon the C and Mn contents the product attained pearlitic microstructure in the range of 85-93% with balance amount of polygonal ferrite transformed at prior austenite grain boundaries. The pearlitic microstructure in the wire rods helped in achieving yield strength, tensile strength, total elongation and reduction in area values within the range of 422-515 MPa, 790-950 MPa, 22-15% and 45-35%, respectively. On analyzing the tensile results it was revealed that the material experienced hardening in two stages separable by a knee strain value of about 0.05. The occurrence of two stage hardening thus in the steel with hardening coefficients of 0.26 and 0.09 could be demonstrated with the help of derived relationships existed between flow stress and the strain.

  11. A two-stage broadcast message propagation model in social networks

    NASA Astrophysics Data System (ADS)

    Wang, Dan; Cheng, Shun-Jun

    2016-11-01

    Message propagation in social networks is becoming a popular topic in complex networks. One of the message types in social networks is called broadcast message. It refers to a type of message which has a unique and unknown destination for the publisher, such as 'lost and found'. Its propagation always has two stages. Due to this feature, rumor propagation model and epidemic propagation model have difficulty in describing this message's propagation accurately. In this paper, an improved two-stage susceptible-infected-removed model is proposed. We come up with the concept of the first forwarding probability and the second forwarding probability. Another part of our work is figuring out the influence to the successful message transmission chance in each level resulting from multiple reasons, including the topology of the network, the receiving probability, the first stage forwarding probability, the second stage forwarding probability as well as the length of the shortest path between the publisher and the relevant destination. The proposed model has been simulated on real networks and the results proved the model's effectiveness.

  12. Two-Stage Single-Compartment Models to Evaluate Dissolution in the Lower Intestine.

    PubMed

    Markopoulos, Constantinos; Vertzoni, Maria; Symillides, Mira; Kesisoglou, Filippos; Reppas, Christos

    2015-09-01

    The purpose was to propose two-stage single-compartment models for evaluating dissolution characteristics in distal ileum and ascending colon, under conditions simulating the bioavailability and bioequivalence studies in fasted and fed state by using the mini-paddle and the compendial flow-through apparatus (closed-loop mode). Immediate release products of two highly dosed active pharmaceutical ingredients (APIs), sulfasalazine and L-870,810, and one mesalamine colon targeting product were used for evaluating their usefulness. Change of medium composition simulating the conditions in distal ileum (SIFileum ) to a medium simulating the conditions in ascending colon in fasted state and in fed state was achieved by adding an appropriate solution in SIFileum . Data with immediate release products suggest that dissolution in lower intestine is substantially different than in upper intestine and is affected by regional pH differences > type/intensity of fluid convection > differences in concentration of other luminal components. Asacol® (400 mg/tab) was more sensitive to type/intensity of fluid convection. In all the cases, data were in line with available human data. Two-stage single-compartment models may be useful for the evaluation of dissolution in lower intestine. The impact of type/intensity of fluid convection and viscosity of media on luminal performance of other APIs and drug products requires further exploration.

  13. Development of a Two-Stage Microalgae Dewatering Process - A Life Cycle Assessment Approach.

    PubMed

    Soomro, Rizwan R; Ndikubwimana, Theoneste; Zeng, Xianhai; Lu, Yinghua; Lin, Lu; Danquah, Michael K

    2016-01-01

    Even though microalgal biomass is leading the third generation biofuel research, significant effort is required to establish an economically viable commercial-scale microalgal biofuel production system. Whilst a significant amount of work has been reported on large-scale cultivation of microalgae using photo-bioreactors and pond systems, research focus on establishing high performance downstream dewatering operations for large-scale processing under optimal economy is limited. The enormous amount of energy and associated cost required for dewatering large-volume microalgal cultures has been the primary hindrance to the development of the needed biomass quantity for industrial-scale microalgal biofuels production. The extremely dilute nature of large-volume microalgal suspension and the small size of microalgae cells in suspension create a significant processing cost during dewatering and this has raised major concerns towards the economic success of commercial-scale microalgal biofuel production as an alternative to conventional petroleum fuels. This article reports an effective framework to assess the performance of different dewatering technologies as the basis to establish an effective two-stage dewatering system. Bioflocculation coupled with tangential flow filtration (TFF) emerged a promising technique with total energy input of 0.041 kWh, 0.05 kg CO2 emissions and a cost of $ 0.0043 for producing 1 kg of microalgae biomass. A streamlined process for operational analysis of two-stage microalgae dewatering technique, encompassing energy input, carbon dioxide emission, and process cost, is presented.

  14. Two-stage effects of awareness cascade on epidemic spreading in multiplex networks

    NASA Astrophysics Data System (ADS)

    Guo, Quantong; Jiang, Xin; Lei, Yanjun; Li, Meng; Ma, Yifang; Zheng, Zhiming

    2015-01-01

    Human awareness plays an important role in the spread of infectious diseases and the control of propagation patterns. The dynamic process with human awareness is called awareness cascade, during which individuals exhibit herd-like behavior because they are making decisions based on the actions of other individuals [Borge-Holthoefer et al., J. Complex Networks 1, 3 (2013), 10.1093/comnet/cnt006]. In this paper, to investigate the epidemic spreading with awareness cascade, we propose a local awareness controlled contagion spreading model on multiplex networks. By theoretical analysis using a microscopic Markov chain approach and numerical simulations, we find the emergence of an abrupt transition of epidemic threshold βc with the local awareness ratio α approximating 0.5 , which induces two-stage effects on epidemic threshold and the final epidemic size. These findings indicate that the increase of α can accelerate the outbreak of epidemics. Furthermore, a simple 1D lattice model is investigated to illustrate the two-stage-like sharp transition at αc≈0.5 . The results can give us a better understanding of why some epidemics cannot break out in reality and also provide a potential access to suppressing and controlling the awareness cascading systems.

  15. Two-stage method of estimation for general linear growth curve models.

    PubMed

    Stukel, T A; Demidenko, E

    1997-06-01

    We extend the linear random-effects growth curve model (REGCM) (Laird and Ware, 1982, Biometrics 38, 963-974) to study the effects of population covariates on one or more characteristics of the growth curve when the characteristics are expressed as linear combinations of the growth curve parameters. This definition includes the actual growth curve parameters (the usual model) or any subset of these parameters. Such an analysis would be cumbersome using standard growth curve methods because it would require reparameterization of the original growth curve. We implement a two-stage method of estimation based on the two-stage growth curve model used to describe the response. The resulting generalized least squares (GLS) estimator for the population parameters is consistent, asymptotically efficient, and multivariate normal when the number of individuals is large. It is also robust to model misspecification in terms of bias and efficiency of the parameter estimates compared to maximum likelihood with the usual REGCM. We apply the method to a study of factors affecting the growth rate of salmonellae in a cubic growth model, a characteristic that cannot be analyzed easily using standard techniques.

  16. Final Report on Two-Stage Fast Spectrum Fuel Cycle Options

    SciTech Connect

    Yang, Won Sik; Lin, C. S.; Hader, J. S.; Park, T. K.; Deng, P.; Yang, G.; Jung, Y. S.; Kim, T. K.; Stauff, N. E.

    2016-01-30

    This report presents the performance characteristics of two “two-stage” fast spectrum fuel cycle options proposed to enhance uranium resource utilization and to reduce nuclear waste generation. One is a two-stage fast spectrum fuel cycle option of continuous recycle of plutonium (Pu) in a fast reactor (FR) and subsequent burning of minor actinides (MAs) in an accelerator-driven system (ADS). The first stage is a sodium-cooled FR fuel cycle starting with low-enriched uranium (LEU) fuel; at the equilibrium cycle, the FR is operated using the recovered Pu and natural uranium without supporting LEU. Pu and uranium (U) are co-extracted from the discharged fuel and recycled in the first stage, and the recovered MAs are sent to the second stage. The second stage is a sodium-cooled ADS in which MAs are burned in an inert matrix fuel form. The discharged fuel of ADS is reprocessed, and all the recovered heavy metals (HMs) are recycled into the ADS. The other is a two-stage FR/ADS fuel cycle option with MA targets loaded in the FR. The recovered MAs are not directly sent to ADS, but partially incinerated in the FR in order to reduce the amount of MAs to be sent to the ADS. This is a heterogeneous recycling option of transuranic (TRU) elements

  17. Two-stage double-level rotational osteotomy in the treatment of congenital radioulnar synostosis.

    PubMed

    El-Adl, Wael

    2007-12-01

    Congenital proximal radioulnar synostosis is a rare congenital anomaly that can be extremely disabling, especially when it occurs bilaterally or if there is severe hyperpronation. Currently, osteotomy to achieve a neutral or slightly pronated position is widely accepted for the management of patients who have severe pronation. The present study evaluates the result of two-stage double-level rotational osteotomy of both the radius and ulna in the treatment of severe congenital radioulnar synostosis. Nine children with severe congenital radioulnar synostosis underwent two-stage double-level rotational osteotomy of both the radius and ulna at Mansoura University Hospital. There were seven boys and two girls with a mean age of 5.6 years who were followed up for a mean of 26 months. The position of the forearm was improved from a mean pronation deformity of 76 degrees (60 degrees to 85 degrees) to 30 degrees of pronation in the affected dominant extremities and 20 degrees of supination in non-dominant extremities in all cases. Bony union was achieved by 5.9 weeks with no loss of correction. The advantages of this technique are that it is easy, safe, with absence of severe postoperative complications and requires a small surgical scar. A drawback of the technique is that the rotation correction depends only on a cast, so that a correction loss might occur if the plaster cast loosens.

  18. Rules and mechanisms for efficient two-stage learning in neural circuits

    PubMed Central

    Teşileanu, Tiberiu; Ölveczky, Bence; Balasubramanian, Vijay

    2017-01-01

    Trial-and-error learning requires evaluating variable actions and reinforcing successful variants. In songbirds, vocal exploration is induced by LMAN, the output of a basal ganglia-related circuit that also contributes a corrective bias to the vocal output. This bias is gradually consolidated in RA, a motor cortex analogue downstream of LMAN. We develop a new model of such two-stage learning. Using stochastic gradient descent, we derive how the activity in ‘tutor’ circuits (e.g., LMAN) should match plasticity mechanisms in ‘student’ circuits (e.g., RA) to achieve efficient learning. We further describe a reinforcement learning framework through which the tutor can build its teaching signal. We show that mismatches between the tutor signal and the plasticity mechanism can impair learning. Applied to birdsong, our results predict the temporal structure of the corrective bias from LMAN given a plasticity rule in RA. Our framework can be applied predictively to other paired brain areas showing two-stage learning. DOI: http://dx.doi.org/10.7554/eLife.20944.001 PMID:28374674

  19. Utilising biohydrogen to increase methane production, energy yields and process efficiency via two stage anaerobic digestion of grass.

    PubMed

    Massanet-Nicolau, Jaime; Dinsdale, Richard; Guwy, Alan; Shipley, Gary

    2015-01-01

    Real time measurement of gas production and composition were used to examine the benefits of two stage anaerobic digestion (AD) over a single stage AD, using pelletized grass as a feedstock. Controlled, parallel digestion experiments were performed in order to directly compare a two stage digestion system producing hydrogen and methane, with a single stage system producing just methane. The results indicated that as well as producing additional energy in the form of hydrogen, two stage digestion also resulted in significant increases to methane production, overall energy yields, and digester stability (as indicated by bicarbonate alkalinity and volatile fatty acid removal). Two stage AD resulted in an increase in energy yields from 10.36 MJ kg(-1) VS to 11.74 MJ kg(-1) VS, an increase of 13.4%. Using a two stage system also permitted a much shorter hydraulic retention time of 12 days whilst maintaining process stability.

  20. A two-stage optimization model for emergency material reserve layout planning under uncertainty in response to environmental accidents.

    PubMed

    Liu, Jie; Guo, Liang; Jiang, Jiping; Jiang, Dexun; Liu, Rentao; Wang, Peng

    2016-06-05

    In the emergency management relevant to pollution accidents, efficiency emergency rescues can be deeply influenced by a reasonable assignment of the available emergency materials to the related risk sources. In this study, a two-stage optimization framework is developed for emergency material reserve layout planning under uncertainty to identify material warehouse locations and emergency material reserve schemes in pre-accident phase coping with potential environmental accidents. This framework is based on an integration of Hierarchical clustering analysis - improved center of gravity (HCA-ICG) model and material warehouse location - emergency material allocation (MWL-EMA) model. First, decision alternatives are generated using HCA-ICG to identify newly-built emergency material warehouses for risk sources which cannot be satisfied by existing ones with a time-effective manner. Second, emergency material reserve planning is obtained using MWL-EMA to make emergency materials be prepared in advance with a cost-effective manner. The optimization framework is then applied to emergency management system planning in Jiangsu province, China. The results demonstrate that the developed framework not only could facilitate material warehouse selection but also effectively provide emergency material for emergency operations in a quick response.

  1. Two-stage sample-to-answer system based on nucleic acid amplification approach for detection of malaria parasites.

    PubMed

    Liu, Qing; Nam, Jeonghun; Kim, Sangho; Lim, Chwee Teck; Park, Mi Kyoung; Shin, Yong

    2016-08-15

    Rapid, early, and accurate diagnosis of malaria is essential for effective disease management and surveillance, and can reduce morbidity and mortality associated with the disease. Although significant advances have been achieved for the diagnosis of malaria, these technologies are still far from ideal, being time consuming, complex and poorly sensitive as well as requiring separate assays for sample processing and detection. Therefore, the development of a fast and sensitive method that can integrate sample processing with detection of malarial infection is desirable. Here, we report a two-stage sample-to-answer system based on nucleic acid amplification approach for detection of malaria parasites. It combines the Dimethyl adipimidate (DMA)/Thin film Sample processing (DTS) technique as a first stage and the Mach-Zehnder Interferometer-Isothermal solid-phase DNA Amplification (MZI-IDA) sensing technique as a second stage. The system can extract DNA from malarial parasites using DTS technique in a closed system, not only reducing sample loss and contamination, but also facilitating the multiplexed malarial DNA detection using the fast and accurate MZI-IDA technique. Here, we demonstrated that this system can deliver results within 60min (including sample processing, amplification and detection) with high sensitivity (<1 parasite μL(-1)) in a label-free and real-time manner. The developed system would be of great potential for better diagnosis of malaria in low-resource settings.

  2. A robust two-stage design identifying the optimal biological dose for phase I/II clinical trials.

    PubMed

    Zang, Yong; Lee, J Jack

    2017-01-15

    We propose a robust two-stage design to identify the optimal biological dose for phase I/II clinical trials evaluating both toxicity and efficacy outcomes. In the first stage of dose finding, we use the Bayesian model averaging continual reassessment method to monitor the toxicity outcomes and adopt an isotonic regression method based on the efficacy outcomes to guide dose escalation. When the first stage ends, we use the Dirichlet-multinomial distribution to jointly model the toxicity and efficacy outcomes and pick the candidate doses based on a three-dimensional volume ratio. The selected candidate doses are then seamlessly advanced to the second stage for dose validation. Both toxicity and efficacy outcomes are continuously monitored so that any overly toxic and/or less efficacious dose can be dropped from the study as the trial continues. When the phase I/II trial ends, we select the optimal biological dose as the dose obtaining the minimal value of the volume ratio within the candidate set. An advantage of the proposed design is that it does not impose a monotonically increasing assumption on the shape of the dose-efficacy curve. We conduct extensive simulation studies to examine the operating characteristics of the proposed design. The simulation results show that the proposed design has desirable operating characteristics across different shapes of the underlying true dose-toxicity and dose-efficacy curves. The software to implement the proposed design is available upon request. Copyright © 2016 John Wiley & Sons, Ltd.

  3. Experimental research on a 12.1 K gas-coupled two-stage high frequency pulse tube cryocooler

    NASA Astrophysics Data System (ADS)

    Xiaoshuang, Zhu; Yuan, Zhou; Wenxiu, Zhu; Wei, Dai; Junjie, Wang

    2017-02-01

    High frequency pulse tube cryocoolers (HFPTC) have been widely used in many fields like physics experimental research and aerospace, for no moving part in cold region, low vibration and long life. A gas-coupled two-stage high frequency pulse tube cryocooler with single compressor is introduced in this paper. In the first stage of the cryocooler, double-inlet and multi-bypass has been adopted as phase shifters. To get a better performance in phase shifting the reservoir and the inertance tube of the second stage has been located on the cold head of the first stage. With SS mesh screen as the regenerator of both stage, no-load temperature of 13.5K has been achieved. To improve the heat capacity of the regenerator of the second stage magnetic material Er3Ni has been employed in the second stage as regenerator matrix. With the charge pressure of 1.8MPa, input power of 260W and operating frequency of 23.5 Hz, the no-load temperature of 12.1K has been achieved.

  4. The Importance of Detailed Component Simulations in the Feedsystem Development for a Two-Stage-to Orbit Reusable Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Mazurkivich, Pete; Chandler, Frank; Grayson, Gary

    2005-01-01

    To meet the requirements for the 2nd Generation Reusable Launch Vehicle (RLV), a unique propulsion feed system concept was identified using crossfeed between the booster and orbiter stages that could reduce the Two-Stage-to-Orbit (TSTO) vehicle weight and development cost by approximately 25%. A Main Propulsion System (MPS) crossfeed water demonstration test program was configured to address all the activities required to reduce the risks for the MPS crossfeed system. A transient, one-dimensional system simulation was developed for the subscale crossfeed water flow tests. To ensure accurate representation of the crossfeed valve's dynamics in the system model, a high-fidelity, three-dimensional, computational fluid-dynamics (CFD) model was employed. The results from the CFD model were used to specify the valve's flow characteristics in the system simulation. This yielded a crossfeed system model that was anchored to the specific valve hardware and achieved good agreement with the measured test data. These results allowed the transient models to be correlated and validated and used for full scale mission predictions. The full scale model simulations indicate crossfeed is ' viable with the system pressure disturbances at the crossfeed transition being less than experienced by the propulsion system during engine start and shutdown transients.

  5. Two-stage atlas subset selection in multi-atlas based image segmentation

    SciTech Connect

    Zhao, Tingting Ruan, Dan

    2015-06-15

    Purpose: Fast growing access to large databases and cloud stored data presents a unique opportunity for multi-atlas based image segmentation and also presents challenges in heterogeneous atlas quality and computation burden. This work aims to develop a novel two-stage method tailored to the special needs in the face of large atlas collection with varied quality, so that high-accuracy segmentation can be achieved with low computational cost. Methods: An atlas subset selection scheme is proposed to substitute a significant portion of the computationally expensive full-fledged registration in the conventional scheme with a low-cost alternative. More specifically, the authors introduce a two-stage atlas subset selection method. In the first stage, an augmented subset is obtained based on a low-cost registration configuration and a preliminary relevance metric; in the second stage, the subset is further narrowed down to a fusion set of desired size, based on full-fledged registration and a refined relevance metric. An inference model is developed to characterize the relationship between the preliminary and refined relevance metrics, and a proper augmented subset size is derived to ensure that the desired atlases survive the preliminary selection with high probability. Results: The performance of the proposed scheme has been assessed with cross validation based on two clinical datasets consisting of manually segmented prostate and brain magnetic resonance images, respectively. The proposed scheme demonstrates comparable end-to-end segmentation performance as the conventional single-stage selection method, but with significant computation reduction. Compared with the alternative computation reduction method, their scheme improves the mean and medium Dice similarity coefficient value from (0.74, 0.78) to (0.83, 0.85) and from (0.82, 0.84) to (0.95, 0.95) for prostate and corpus callosum segmentation, respectively, with statistical significance. Conclusions: The authors

  6. Pressurized Testing of Solid Oxide Electrolysis Stacks with Advanced Electrode-Supported Cells

    SciTech Connect

    J. E. O'Brien; X. Zhang; G. K. Housley; K. DeWall; L. Moore-McAteer; G. Tao

    2012-06-01

    A new facility has been developed at the Idaho National Laboratory for pressurized testing of solid oxide electrolysis stacks. Pressurized operation is envisioned for large-scale hydrogen production plants, yielding higher overall efficiencies when the hydrogen product is to be delivered at elevated pressure for tank storage or pipelines. Pressurized operation also supports higher mass flow rates of the process gases with smaller components. The test stand can accommodate cell dimensions up to 8.5 cm x 8.5 cm and stacks of up to 25 cells. The pressure boundary for these tests is a water-cooled spool-piece pressure vessel designed for operation up to 5 MPa. The stack is internally manifolded and operates in cross-flow with an inverted-U flow pattern. Feed-throughs for gas inlets/outlets, power, and instrumentation are all located in the bottom flange. The entire spool piece, with the exception of the bottom flange, can be lifted to allow access to the internal furnace and test fixture. Lifting is accomplished with a motorized threaded drive mechanism attached to a rigid structural frame. Stack mechanical compression is accomplished using springs that are located inside of the pressure boundary, but outside of the hot zone. Initial stack heatup and performance characterization occurs at ambient pressure followed by lowering and sealing of the pressure vessel and subsequent pressurization. Pressure equalization between the anode and cathode sides of the cells and the stack surroundings is ensured by combining all of the process gases downstream of the stack. Steady pressure is maintained by means of a backpressure regulator and a digital pressure controller. A full description of the pressurized test apparatus is provided in this paper.

  7. Advanced Production Surface Preparation Technology Development for Ultra-High Pressure Diesel Injection

    SciTech Connect

    Grant, Marion B.

    2012-04-30

    In 2007, An Ultra High Injection Pressure (UHIP) fueling method has been demonstrated by Caterpillar Fuel Systems - Product Development, demonstrating ability to deliver U.S. Environment Protection Agency (EPA) Tier 4 Final diesel engine emission performance with greatly reduced emissions handling components on the engine, such as without NOx reduction after-treatment and with only a through-flow 50% effective diesel particulate trap (DPT). They have shown this capability using multiple multi-cylinder engine tests of an Ultra High Pressure Common Rail (UHPCR) fuel system with higher than traditional levels of CEGR and an advanced injector nozzle design. The system delivered better atomization of the fuel, for more complete burn, to greatly reduce diesel particulates, while CEGR or high efficiency NOx reduction after-treatment handles the NOx. With the reduced back pressure of a traditional DPT, and with the more complete fuel burn, the system reduced levels of fuel consumption by 2.4% for similar delivery of torque and horsepower over the best Tier 4 Interim levels of fuel consumption in the diesel power industry. The challenge is to manufacture the components in high-volume production that can withstand the required higher pressure injection. Production processes must be developed to increase the toughness of the injector steel to withstand the UHIP pulsations and generate near perfect form and finish in the sub-millimeter size geometries within the injector. This project resulted in two developments in 2011. The first development was a process and a machine specification by which a high target of compressive residual stress (CRS) can be consistently imparted to key surfaces of the fuel system to increase the toughness of the steel, and a demonstration of the feasibility of further refinement of the process for use in volume production. The second development was the demonstration of the feasibility of a process for imparting near perfect, durable geometry to

  8. Two-stage Surgery for an Aortoesophageal Fistula Caused by Tuberculous Esophagitis

    PubMed Central

    Choi, Chang Woo; Lim, Jae Woong; Her, Keun

    2015-01-01

    An aortoesophageal fistula (AEF) is an extremely rare, potentially fatal condition, and aortic surgery is usually performed together with extracorporeal circulation. However, this surgical method has a high rate of surgical complications and mortality. This report describes an AEF caused by tuberculous esophagitis that was treated successfully using a two-stage operation. A 52-yr-old man was admitted to the hospital with severe hematemesis and syncope. Based on the computed tomography and diagnostic endoscopic findings, he was diagnosed with an AEF and initially underwent thoracic endovascular aortic repair. Esophageal reconstruction was performed after controlling the mediastinal inflammation. The patient suffered postoperative anastomotic leakage, which was treated by an endoscopic procedure, and the patient was discharged without any further problems. The patient received 9 months of anti-tuberculosis treatment after he was diagnosed with histologically confirmed tuberculous esophagitis; subsequently, he was followed as an outpatient and has had no recurrence of the tuberculosis or any further issues. PMID:26539019

  9. Two-stage electron acceleration by simultaneous stimulated Raman backward and forward scattering

    SciTech Connect

    Bertrand, P.; Ghizzo, A.; Karttunen, S.J.; Paettikangas, T.J.H.; Salomaa, R.R.E.; Shoucri, M.

    1995-08-01

    The coexistence of stimulated Raman forward and backward scattering of intense electromagnetic radiation, which can occur, for instance, in laser fusion plasmas, is investigated. The simultaneous Raman forward and backward scattering is shown to create an electrostatic field structure which is exceptionally efficient in producing highly relativistic electrons. The mechanism of the electron acceleration is analyzed both by Vlasov--Maxwell simulations with self-consistent fields and by test particle calculations with prescribed electrostatic fields. The Vlasov--Maxwell simulations reveal that the two plasma waves generated by the backward and forward scattering are spatially separated, and thus form a two-stage electron ``accelerator.`` {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  10. Recurring two-stage evolutionary programming: a novel approach for numeric optimization.

    PubMed

    Alam, Mohammad Shafiul; Islam, Md Monirul; Yao, Xin; Murase, Kazuyuki

    2011-10-01

    In the application of evolutionary algorithms (EAs) to complex problem solving, it is essential to maintain proper balance between global exploration and local exploitation to achieve a good near-optimum solution to the problem. This paper presents a recurring two-stage evolutionary programming (RTEP) to balance the explorative and exploitative features of the conventional EAs. Unlike most previous works, RTEP is based on repeated and alternated execution of two different stages, namely, the exploration and exploitation stages, each with its own mutation operator, selection strategy, and explorative/exploitative objective. Both analytical and empirical studies have been carried out to understand the necessity of repeated and alternated exploration and exploitation operations in EAs. A suite of 48 benchmark numerical optimization problems has been used in the empirical studies. The experimental results show the remarkable effectiveness of the repeated exploration and exploitation operations employed by RTEP.

  11. Two-stage Raman compression of laser pulses with controllable phase fronts

    SciTech Connect

    Balakin, A. A.; Fraiman, G. M.; Dodin, I. Y.

    2015-05-15

    The phase front of an ultrashort laser pulse undergoing Raman amplification and compression in inhomogeneous plasma can be controlled such that it is unaffected by density gradients and thus remains focusable. This is achieved by performing the Raman backscattering in two stages. At the first stage, the standard nonlinear Raman compression of a seed wave takes place and produces a short ultraintense pulse, which yet may be poorly focusable. At the second stage, this amplified pulse is scattered again, now serving as a pump, off a second copy of the initial seed. This stage, which utilizes a denser and shorter plasma, is intended not for compression but rather for passing a significant fraction of the energy to the second seed quickly. Then, the output pulse that is produced is not just short and ultraintense, but also has the smooth phase front of the original seed.

  12. Synchronous rapid start-up of the methanation and anammox processes in two-stage ASBRs

    NASA Astrophysics Data System (ADS)

    Duan, Y.; Li, W. R.; Zhao, Y.

    2017-01-01

    The “methanation + anaerobic ammonia oxidation autotrophic denitrification” method was adopted by using anaerobic sequencing batch reactors (ASBRs) and realized a satisfactory synchronous removal of chemical oxygen demand (COD) and ammonia-nitrogen (NH4 +-N) in wastewater after 75 days operation. 90% of COD was removed at a COD load of 1.2 kg/(m3•d) and 90% of TN was removed at a TN load of 0.14 kg/(m3•d). The anammox reaction ratio was estimated to be 1: 1.32: 0.26. The results showed that synchronous rapid start-up of the methanation and anaerobic ammonia oxidation processes in two-stage ASBRs was feasible.

  13. Final two-stage MOAO on-sky demonstration with CANARY

    NASA Astrophysics Data System (ADS)

    Gendron, E.; Morris, T.; Basden, A.; Vidal, F.; Atkinson, D.; Bitenc, U.; Buey, T.; Chemla, F.; Cohen, M.; Dickson, C.; Dipper, N.; Feautrier, P.; Gach, J.-L.; Gratadour, D.; Henry, D.; Huet, J.-M.; Morel, C.; Morris, S.; Myers, R.; Osborn, J.; Perret, D.; Reeves, A.; Rousset, G.; Sevin, A.; Stadler, E.; Talbot, G.; Todd, S.; Younger, E.

    2016-07-01

    CANARY is an on-sky Laser Guide Star (LGS) tomographic AO demonstrator in operation at the 4.2m William Herschel Telescope (WHT) in La Palma. From the early demonstration of open-loop tomography on a single deformable mirror using natural guide stars in 2010, CANARY has been progressively upgraded each year to reach its final goal in July 2015. It is now a two-stage system that mimics the future E-ELT: a GLAO-driven woofer based on 4 laser guide stars delivers a ground-layer compensated field to a figure sensor locked tweeter DM, that achieves the final on-axis tomographic compensation. We present the overall system, the control strategy and an overview of its on-sky performance.

  14. Two-stage production of olefins utilizing a faujasite structure zeolite in hydrogenation stage

    SciTech Connect

    Kreuter, W.; Mansmann, M.; Watson, A.; Weber, H.; Wernicke, H.J.

    1980-02-12

    A process is disclosed for the production of olefins in two stages. In the first stage, heavy petroleum fractions are hydrogenated in the presence of hydrogen and a hydrogenation catalyst and, in the second stage, the thus-hydrogenated fractions are subjected to thermal cracking the presence of steam. The improvement comprises employing as the hydrogenation catalyst a zeolite of the faujasite structure combined with elements from groups VIB, VIIB and VIII of the periodic table of the elements, wherein the alkali component of the zeolite is exchanged at least partially for ammonium, hydronium, alkaline earth and/or rare earth ions, and the elements are present in a metallic, ionic, oxidic and/or sulfidic form.

  15. Enhanced acarbose production by Streptomyces M37 using a two-stage fermentation strategy

    PubMed Central

    Ren, Fei; Chen, Long; Xiong, Shuangli; Tong, Qunyi

    2017-01-01

    In this work, we investigated the effect of pH on Streptomyces M37 growth and its acarbose biosynthesis ability. We observed that low pH was beneficial for cell growth, whereas high pH favored acarbose synthesis. Moreover, addition of glucose and maltose to the fermentation medium after 72 h of cultivation promoted acarbose production. Based on these results, a two-stage fermentation strategy was developed to improve acarbose production. Accordingly, pH was kept at 7.0 during the first 72 h and switched to 8.0 after that. At the same time, glucose and maltose were fed to increase acarbose accumulation. With this strategy, we achieved an acarbose titer of 6210 mg/L, representing an 85.7% increase over traditional batch fermentation without pH control. Finally, we determined that the increased acarbose production was related to the high activity of glutamate dehydrogenase and glucose 6-phosphate dehydrogenase. PMID:28234967

  16. Bayesian inference using two-stage Laplace approximation for differential equation models

    NASA Astrophysics Data System (ADS)

    Dass, Sarat C.; Lee, Jaeyong; Lee, Kyoungjae

    2016-11-01

    We consider the problem of Bayesian inference for parameters in non-linear regression models whereby the underlying unknown response functions are formed by a set of differential equations. Bayesian methods of inference for unknown parameters rely primarily on the posterior obtained by Bayes rule. For differential equation models, analytic and closed forms for the posterior are not available and one has to resort to approximations. We propose a two-stage Laplace expansion to approximate the marginal likelihood, and hence, the posterior, to obtain an approximate closed form solution. For large sample sizes, the method of inference borrows from non-linear regression theory for maximum likelihood estimates, and is therefore, consistent. Our approach is exact in the limit and does not need the specification of an additional penalty parameter. Examples in this paper include the exponential model and SIR (Susceptible-Infected-Recovered) disease spread model.

  17. Denitrification of drinking water in a two-stage membrane bioreactor by using immobilized biomass.

    PubMed

    Ravnjak, Matjaž; Vrtovšek, Janez; Pintar, Albin

    2013-01-01

    Nitrate removal from polluted groundwater was investigated in a two-stage anoxic/oxic biofilm membrane bioreactor. The process was carried out with ethanol as a carbon source (corresponding C/N ratio of 1.4-2.5) and commercially available Biocontact-N biocarriers (Nisshinbo, Japan) to enable immobilization of highly efficient and long-lasting microbiota. At a residence time of the liquid phase equal to 2.5h, nitrate conversions higher than 99% were obtained without the formation of nitrite and ammonium ions. The concentration of total organic carbon in the reactor discharge was very similar to the content of organic matter in tap water. The biocarriers minimized the occurrence of suspended filamentous bacteria, and the utilization of increased shear force facilitated collisions of floating biocarrier particles with the outer membrane surface, preventing membrane fouling and resulting in stable operation of the system for 40 days.

  18. Two-stage reflective optical system for achromatic 10 nm x-ray focusing

    NASA Astrophysics Data System (ADS)

    Motoyama, Hiroto; Mimura, Hidekazu

    2015-12-01

    Recently, coherent x-ray sources have promoted developments of optical systems for focusing, imaging, and interferometers. In this paper, we propose a two-stage focusing optical system with the goal of achromatically focusing pulses from an x-ray free-electron laser (XFEL), with a focal width of 10 nm. In this optical system, the x-ray beam is expanded by a grazing-incidence aspheric mirror, and it is focused by a mirror that is shaped as a solid of revolution. We describe the design procedure and discuss the theoretical focusing performance. In theory, soft-XFEL lights can be focused to a 10 nm area without chromatic aberration and with high reflectivity; this creates an unprecedented power density of 1020 W cm-2 in the soft-x-ray range.

  19. Heuristic for Critical Machine Based a Lot Streaming for Two-Stage Hybrid Production Environment

    NASA Astrophysics Data System (ADS)

    Vivek, P.; Saravanan, R.; Chandrasekaran, M.; Pugazhenthi, R.

    2017-03-01

    Lot streaming in Hybrid flowshop [HFS] is encountered in many real world problems. This paper deals with a heuristic approach for Lot streaming based on critical machine consideration for a two stage Hybrid Flowshop. The first stage has two identical parallel machines and the second stage has only one machine. In the second stage machine is considered as a critical by valid reasons these kind of problems is known as NP hard. A mathematical model developed for the selected problem. The simulation modelling and analysis were carried out in Extend V6 software. The heuristic developed for obtaining optimal lot streaming schedule. The eleven cases of lot streaming were considered. The proposed heuristic was verified and validated by real time simulation experiments. All possible lot streaming strategies and possible sequence under each lot streaming strategy were simulated and examined. The heuristic consistently yielded optimal schedule consistently in all eleven cases. The identification procedure for select best lot streaming strategy was suggested.

  20. [Study of color blood image segmentation based on two-stage-improved FCM algorithm].

    PubMed

    Wang, Bin; Chen, Huaiqing; Huang, Hua; Rao, Jie

    2006-04-01

    This paper introduces a new method for color blood cell image segmentation based on FCM algorithm. By transforming the original blood microscopic image to indexed image, and by doing the colormap, a fuzzy apparoach to obviating the direct clustering of image pixel values, the quantity of data processing and analysis is enormously compressed. In accordance to the inherent features of color blood cell image, the segmentation process is divided into two stages. (1)confirming the number of clusters and initial cluster centers; (2) altering the distance measuring method by the distance weighting matrix in order to improve the clustering veracity. In this way, the problem of difficult convergence of FCM algorithm is solved, the iteration time of iterative convergence is reduced, the execution time of algarithm is decreased, and the correct segmentation of the components of color blood cell image is implemented.

  1. A two-stage exon recognition model based on synergetic neural network.

    PubMed

    Huang, Zhehuang; Chen, Yidong

    2014-01-01

    Exon recognition is a fundamental task in bioinformatics to identify the exons of DNA sequence. Currently, exon recognition algorithms based on digital signal processing techniques have been widely used. Unfortunately, these methods require many calculations, resulting in low recognition efficiency. In order to overcome this limitation, a two-stage exon recognition model is proposed and implemented in this paper. There are three main works. Firstly, we use synergetic neural network to rapidly determine initial exon intervals. Secondly, adaptive sliding window is used to accurately discriminate the final exon intervals. Finally, parameter optimization based on artificial fish swarm algorithm is used to determine different species thresholds and corresponding adjustment parameters of adaptive windows. Experimental results show that the proposed model has better performance for exon recognition and provides a practical solution and a promising future for other recognition tasks.

  2. Histories obtained by two-stage questionnaire with automated transcript in specialist gynaecological practice.

    PubMed

    Robinson, D W; Walmsley, G L; Horrocks, J C; Milson, P; Jenkins, D M; De Dombal, F T; Scott, J S

    1975-11-29

    A two-stage questionnaire which the patient completes at home has been developed for use by gynaecological outpatients. The first stage (root) identifies the patient's problem and obtains general background information. The second stage (branch) deals with the presenting problem in depth. The system has proved highly acceptable to patients. At the clinic a non-medical assistant uses a programmed typewriter to transcribe the data into a typewritten history which is handed to the doctor before he examines the patient. The transcript compares favourably with the conventional hand-written history in content, ease of assimilation, and cost. While the questionnaire itself is an excellent means of collecting information it becomes an efficient means of transmitting information to the clinician only when combined with the transcript facility. There is no storage of confidential information and no scope for unethical disclosure.

  3. Design and Experimental Performance of a Two Stage Partial Admission Turbine, Task B.1/B.4

    NASA Technical Reports Server (NTRS)

    Sutton, R. F.; Boynton, J. L.; Akian, R. A.; Shea, Dan; Roschak, Edmund; Rojas, Lou; Orr, Linsey; Davis, Linda; King, Brad; Bubel, Bill

    1992-01-01

    A three-inch mean diameter, two-stage turbine with partial admission in each stage was experimentally investigated over a range of admissions and angular orientations of admission arcs. Three configurations were tested in which first stage admission varied from 37.4 percent (10 of 29 passages open, 5 per side) to 6.9 percent (2 open, 1 per side). Corresponding second stage admissions were 45.2 percent (14 of 31 passages open, 7 per side) and 12.9 percent (4 open, 2 per side). Angular positions of the second stage admission arcs with respect to the first stage varied over a range of 70 degrees. Design and off-design efficiency and flow characteristics for the three configurations are presented. The results indicated that peak efficiency and the corresponding isentropic velocity ratio decreased as the arcs of admission were decreased. Both efficiency and flow characteristics were sensitive to the second stage nozzle orientation angles.

  4. A Two-Stage Approach for Medical Supplies Intermodal Transportation in Large-Scale Disaster Responses

    PubMed Central

    Ruan, Junhu; Wang, Xuping; Shi, Yan

    2014-01-01

    We present a two-stage approach for the “helicopters and vehicles” intermodal transportation of medical supplies in large-scale disaster responses. In the first stage, a fuzzy-based method and its heuristic algorithm are developed to select the locations of temporary distribution centers (TDCs) and assign medial aid points (MAPs) to each TDC. In the second stage, an integer-programming model is developed to determine the delivery routes. Numerical experiments verified the effectiveness of the approach, and observed several findings: (i) More TDCs often increase the efficiency and utility of medical supplies; (ii) It is not definitely true that vehicles should load more and more medical supplies in emergency responses; (iii) The more contrasting the traveling speeds of helicopters and vehicles are, the more advantageous the intermodal transportation is. PMID:25350005

  5. Nitrification and microalgae cultivation for two-stage biological nutrient valorization from source separated urine.

    PubMed

    Coppens, Joeri; Lindeboom, Ralph; Muys, Maarten; Coessens, Wout; Alloul, Abbas; Meerbergen, Ken; Lievens, Bart; Clauwaert, Peter; Boon, Nico; Vlaeminck, Siegfried E

    2016-07-01

    Urine contains the majority of nutrients in urban wastewaters and is an ideal nutrient recovery target. In this study, stabilization of real undiluted urine through nitrification and subsequent microalgae cultivation were explored as strategy for biological nutrient recovery. A nitrifying inoculum screening revealed a commercial aquaculture inoculum to have the highest halotolerance. This inoculum was compared with municipal activated sludge for the start-up of two nitrification membrane bioreactors. Complete nitrification of undiluted urine was achieved in both systems at a conductivity of 75mScm(-1) and loading rate above 450mgNL(-1)d(-1). The halotolerant inoculum shortened the start-up time with 54%. Nitrite oxidizers showed faster salt adaptation and Nitrobacter spp. became the dominant nitrite oxidizers. Nitrified urine as growth medium for Arthrospira platensis demonstrated superior growth compared to untreated urine and resulted in a high protein content of 62%. This two-stage strategy is therefore a promising approach for biological nutrient recovery.

  6. Two-stage feedforward tracking control system with error-based disturbance observer for optical discs

    NASA Astrophysics Data System (ADS)

    Sakimura, Naohide; Ohashi, Takahiro; Ohishi, Kiyoshi; Miyazaki, Toshimasa

    2014-09-01

    Recently, the scaling up of the storage capacity and data transfer rate of digital storage media has been required. However, increasing in the storage capacity and transfer rate makes optical head control more difficult. Thus, a tracking control system for optical discs must exhibit a high degree of precision control. Consequently, a new two-stage feedforward control (TSFFC) system for high-precision control is proposed in this paper. The proposed system is constructed using two zero phase error tracking (ZPET) control systems based on error prediction and an error-based disturbance observer (EDOB) that uses a notch filter to suppress non periodic disturbances. The proposed control system is designed for DDU-1000 for digital versatile discs (DVDs). The experimental results demonstrate that the proposed system effectively suppresses tracking errors.

  7. Enhanced biodiesel production in Neochloris oleoabundans by a semi-continuous process in two stage photobioreactors.

    PubMed

    Yoon, Se Young; Hong, Min Eui; Chang, Won Seok; Sim, Sang Jun

    2015-07-01

    Under autotrophic conditions, highly productive biodiesel production was achieved using a semi-continuous culture system in Neochloris oleoabundans. In particular, the flue gas generated by combustion of liquefied natural gas and natural solar radiation were used for cost-effective microalgal culture system. In semi-continuous culture, the greater part (~80%) of the culture volume containing vegetative cells grown under nitrogen-replete conditions in a first photobioreactor (PBR) was directly transferred to a second PBR and cultured sequentially under nitrogen-deplete conditions for accelerating oil accumulation. As a result, in semi-continuous culture, the productivities of biomass and biodiesel in the cells were increased by 58% (growth phase) and 51% (induction phase) compared to the cells in batch culture, respectively. The semi-continuous culture system using two stage photobioreactors is a very efficient strategy to further improve biodiesel production from microalgae under photoautotrophic conditions.

  8. Treatment of Ammonia Nitrogen Wastewater in Low Concentration by Two-Stage Ozonization.

    PubMed

    Luo, Xianping; Yan, Qun; Wang, Chunying; Luo, Caigui; Zhou, Nana; Jian, Chensheng

    2015-09-23

    Ammonia nitrogen wastewater (about 100 mg/L) was treated by two-stage ozone oxidation method. The effects of ozone flow rate and initial pH on ammonia removal were studied, and the mechanism of ammonia nitrogen removal by ozone oxidation was discussed. After the primary stage of ozone oxidation, the ammonia removal efficiency reached 59.32% and pH decreased to 6.63 under conditions of 1 L/min ozone flow rate and initial pH 11. Then, the removal efficiency could be over 85% (the left ammonia concentration was lower than 15 mg/L) after the second stage, which means the wastewater could have met the national discharge standards of China. Besides, the mechanism of ammonia removal by ozone oxidation was proposed by detecting the products of the oxidation: ozone oxidation directly and ·OH oxidation; ammonia was mainly transformed into NO₃(-)-N, less into NO₂(-)-N, not into N₂.

  9. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing

    DOE PAGES

    Brodeur, G.; Telotte, J.; Stickel, J. J.; ...

    2016-08-26

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide -- NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48 h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass -- DA treatment removesmore » the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Lastly, future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.« less

  10. Design of a Two-stage High-capacity Stirling Cryocooler Operating below 30K

    NASA Astrophysics Data System (ADS)

    Wang, Xiaotao; Dai, Wei; Zhu, Jian; Chen, Shuai; Li, Haibing; Luo, Ercang

    The high capacity cryocooler working below 30K can find many applications such as superconducting motors, superconducting cables and cryopump. Compared to the GM cryocooler, the Stirling cryocooler can achieve higher efficiency and more compact structure. Because of these obvious advantages, we have designed a two stage free piston Stirling cryocooler system, which is driven by a moving magnet linear compressor with an operating frequency of 40 Hz and a maximum 5 kW input electric power. The first stage of the cryocooler is designed to operate in the liquid nitrogen temperature and output a cooling power of 100 W. And the second stage is expected to simultaneously provide a cooling power of 50 W below the temperature of 30 K. In order to achieve the best system efficiency, a numerical model based on the thermoacoustic model was developed to optimize the system operating and structure parameters.

  11. Two-stage acceleration of interstellar ions driven by high-energy lepton plasma flows

    NASA Astrophysics Data System (ADS)

    Cui, YunQian; Sheng, ZhengMing; Lu, QuanMing; Li, YuTong; Zhang, Jie

    2015-10-01

    We present the particle-in-cell (PIC) simulation results of the interaction of a high-energy lepton plasma flow with background electron-proton plasma and focus on the acceleration processes of the protons. It is found that the acceleration follows a two-stage process. In the first stage, protons are significantly accelerated transversely (perpendicular to the lepton flow) by the turbulent magnetic field "islands" generated via the strong Weibel-type instabilities. The accelerated protons shows a perfect inverse-power energy spectrum. As the interaction continues, a shockwave structure forms and the protons in front of the shockwave are reflected at twice of the shock speed, resulting in a quasi-monoenergetic peak located near 200 MeV under the simulation parameters. The presented scenario of ion acceleration may be relevant to cosmic-ray generation in some astrophysical environments.

  12. Two stages of parafoveal processing during reading: Evidence from a display change detection task.

    PubMed

    Angele, Bernhard; Slattery, Timothy J; Rayner, Keith

    2016-08-01

    We used a display change detection paradigm (Slattery, Angele, & Rayner Human Perception and Performance, 37, 1924-1938 2011) to investigate whether display change detection uses orthographic regularity and whether detection is affected by the processing difficulty of the word preceding the boundary that triggers the display change. Subjects were significantly more sensitive to display changes when the change was from a nonwordlike preview than when the change was from a wordlike preview, but the preview benefit effect on the target word was not affected by whether the preview was wordlike or nonwordlike. Additionally, we did not find any influence of preboundary word frequency on display change detection performance. Our results suggest that display change detection and lexical processing do not use the same cognitive mechanisms. We propose that parafoveal processing takes place in two stages: an early, orthography-based, preattentional stage, and a late, attention-dependent lexical access stage.

  13. Two-stage neural algorithm for defect detection and characterization uses an active thermography

    NASA Astrophysics Data System (ADS)

    Dudzik, Sebastian

    2015-07-01

    In the paper a two-stage neural algorithm for defect detection and characterization is presented. In order to estimate the defect depth two neural networks trained on data obtained using an active thermography were employed. The first stage of the algorithm is developed to detect the defect by a classification neural network. Then the defects depth is estimated using a regressive neural network. In this work the results of experimental investigations and simulations are shown. Further, the sensitivity analysis of the presented algorithm was conducted and the impacts of emissivity error and the ambient temperature error on the depth estimation errors were studied. The results were obtained using a test sample made of material with a low thermal diffusivity.

  14. Bioconversion to chitosan: a two stage process employing chitin deacetylase from Penicillium oxalicum SAEM-51.

    PubMed

    Pareek, Nidhi; Vivekanand, V; Agarwal, Pragati; Saroj, Samta; Singh, Rajesh P

    2013-07-25

    Chitin deacetylase from Penicillium oxalicum SAEM-51 was evaluated for bioconversion of chitin to chitosan in a two stage chemical and enzymatic process. Variations in morphology, crystallinity and thermal properties following chemical treatment were evaluated by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis. Degree of deacetylation of the substrates was determined using FT-IR and elemental analysis. The pretreatment of substrate led to the decrease in crystallinity and formation of amorphous chitinous substrates to facilitate enzyme reaction. The treated chitin was further subjected to enzymatic deacetylation employing chitin deacetylase from P. oxalicum SAEM-51 to produce chitosan with considerably higher degree of deacetylation. Maximum deacetylation (79.52%) was achieved using superfine chitin, owing to its porous structure and low crystallinity. Further, derivation of reaction variables, i.e. substrate amount and enzyme dose through full-factorial central composite design led to enhanced degree of deacetylation with formation of 90% deacetylated chitosan.

  15. Study of a two-stage photobase generator for photolithography in microelectronics.

    PubMed

    Turro, Nicholas J; Li, Yongjun; Jockusch, Steffen; Hagiwara, Yuji; Okazaki, Masahiro; Mesch, Ryan A; Schuster, David I; Willson, C Grant

    2013-03-01

    The investigation of the photochemistry of a two-stage photobase generator (PBG) is described. Absorption of a photon by a latent PBG (1) (first step) produces a PBG (2). Irradiation of 2 in the presence of water produces a base (second step). This two-photon sequence (1 + hν → 2 + hν → base) is an important component in the design of photoresists for pitch division technology, a method that doubles the resolution of projection photolithography for the production of microelectronic chips. In the present system, the excitation of 1 results in a Norrish type II intramolecular hydrogen abstraction to generate a 1,4-biradiacal that undergoes cleavage to form 2 and acetophenone (Φ ∼ 0.04). In the second step, excitation of 2 causes cleavage of the oxime ester (Φ = 0.56) followed by base generation after reaction with water.

  16. A two-stage approach for medical supplies intermodal transportation in large-scale disaster responses.

    PubMed

    Ruan, Junhu; Wang, Xuping; Shi, Yan

    2014-10-27

    We present a two-stage approach for the "helicopters and vehicles" intermodal transportation of medical supplies in large-scale disaster responses. In the first stage, a fuzzy-based method and its heuristic algorithm are developed to select the locations of temporary distribution centers (TDCs) and assign medial aid points (MAPs) to each TDC. In the second stage, an integer-programming model is developed to determine the delivery routes. Numerical experiments verified the effectiveness of the approach, and observed several findings: (i) More TDCs often increase the efficiency and utility of medical supplies; (ii) It is not definitely true that vehicles should load more and more medical supplies in emergency responses; (iii) The more contrasting the traveling speeds of helicopters and vehicles are, the more advantageous the intermodal transportation is.

  17. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing

    SciTech Connect

    Brodeur, G.; Telotte, J.; Stickel, J. J.; Ramakrishnan, S.

    2016-08-26

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide -- NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48 h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass -- DA treatment removes the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Lastly, future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.

  18. Two-stage dilute-acid and organic-solvent lignocellulosic pretreatment for enhanced bioprocessing.

    PubMed

    Brodeur, G; Telotte, J; Stickel, J J; Ramakrishnan, S

    2016-11-01

    A two stage pretreatment approach for biomass is developed in the current work in which dilute acid (DA) pretreatment is followed by a solvent based pretreatment (N-methyl morpholine N oxide - NMMO). When the combined pretreatment (DAWNT) is applied to sugarcane bagasse and corn stover, the rates of hydrolysis and overall yields (>90%) are seen to dramatically improve and under certain conditions 48h can be taken off the time of hydrolysis with the additional NMMO step to reach similar conversions. DAWNT shows a 2-fold increase in characteristic rates and also fractionates different components of biomass - DA treatment removes the hemicellulose while the remaining cellulose is broken down by enzymatic hydrolysis after NMMO treatment to simple sugars. The remaining residual solid is high purity lignin. Future work will focus on developing a full scale economic analysis of DAWNT for use in biomass fractionation.

  19. Two-stage microfluidic chip for selective isolation of circulating tumor cells (CTCs).

    PubMed

    Hyun, Kyung-A; Lee, Tae Yoon; Lee, Su Hyun; Jung, Hyo-Il

    2015-05-15

    Over the past few decades, circulating tumor cells (CTCs) have been studied as a means of overcoming cancer. However, the rarity and heterogeneity of CTCs have been the most significant hurdles in CTC research. Many techniques for CTC isolation have been developed and can be classified into positive enrichment (i.e., specifically isolating target cells using cell size, surface protein expression, and so on) and negative enrichment (i.e., specifically eluting non-target cells). Positive enrichment methods lead to high purity, but could be biased by their selection criteria, while the negative enrichment methods have relatively low purity, but can isolate heterogeneous CTCs. To compensate for the known disadvantages of the positive and negative enrichments, in this study we introduced a two-stage microfluidic chip. The first stage involves a microfluidic magnetic activated cell sorting (μ-MACS) chip to elute white blood cells (WBCs). The second stage involves a geometrically activated surface interaction (GASI) chip for the selective isolation of CTCs. We observed up to 763-fold enrichment in cancer cells spiked into 5 mL of blood sample using the μ-MACS chip at 400 μL/min flow rate. Cancer cells were successfully separated with separation efficiencies ranging from 10.19% to 22.91% based on their EpCAM or HER2 surface protein expression using the GASI chip at a 100 μL/min flow rate. Our two-stage microfluidic chips not only isolated CTCs from blood cells, but also classified heterogeneous CTCs based on their characteristics. Therefore, our chips can contribute to research on CTC heterogeneity of CTCs, and, by extension, personalized cancer treatment.

  20. Novel two-stage piezoelectric-based ocean wave energy harvesters for moored or unmoored buoys

    NASA Astrophysics Data System (ADS)

    Murray, R.; Rastegar, J.

    2009-03-01

    Harvesting mechanical energy from ocean wave oscillations for conversion to electrical energy has long been pursued as an alternative or self-contained power source. The attraction to harvesting energy from ocean waves stems from the sheer power of the wave motion, which can easily exceed 50 kW per meter of wave front. The principal barrier to harvesting this power is the very low and varying frequency of ocean waves, which generally vary from 0.1Hz to 0.5Hz. In this paper the application of a novel class of two-stage electrical energy generators to buoyant structures is presented. The generators use the buoy's interaction with the ocean waves as a low-speed input to a primary system, which, in turn, successively excites an array of vibratory elements (secondary system) into resonance - like a musician strumming a guitar. The key advantage of the present system is that by having two decoupled systems, the low frequency and highly varying buoy motion is converted into constant and much higher frequency mechanical vibrations. Electrical energy may then be harvested from the vibrating elements of the secondary system with high efficiency using piezoelectric elements. The operating principles of the novel two-stage technique are presented, including analytical formulations describing the transfer of energy between the two systems. Also, prototypical design examples are offered, as well as an in-depth computer simulation of a prototypical heaving-based wave energy harvester which generates electrical energy from the up-and-down motion of a buoy riding on the ocean's surface.

  1. Condition monitoring of distributed systems using two-stage Bayesian inference data fusion

    NASA Astrophysics Data System (ADS)

    Jaramillo, Víctor H.; Ottewill, James R.; Dudek, Rafał; Lepiarczyk, Dariusz; Pawlik, Paweł

    2017-03-01

    In industrial practice, condition monitoring is typically applied to critical machinery. A particular piece of machinery may have its own condition monitoring system that allows the health condition of said piece of equipment to be assessed independently of any connected assets. However, industrial machines are typically complex sets of components that continuously interact with one another. In some cases, dynamics resulting from the inception and development of a fault can propagate between individual components. For example, a fault in one component may lead to an increased vibration level in both the faulty component, as well as in connected healthy components. In such cases, a condition monitoring system focusing on a specific element in a connected set of components may either incorrectly indicate a fault, or conversely, a fault might be missed or masked due to the interaction of a piece of equipment with neighboring machines. In such cases, a more holistic condition monitoring approach that can not only account for such interactions, but utilize them to provide a more complete and definitive diagnostic picture of the health of the machinery is highly desirable. In this paper, a Two-Stage Bayesian Inference approach allowing data from separate condition monitoring systems to be combined is presented. Data from distributed condition monitoring systems are combined in two stages, the first data fusion occurring at a local, or component, level, and the second fusion combining data at a global level. Data obtained from an experimental rig consisting of an electric motor, two gearboxes, and a load, operating under a range of different fault conditions is used to illustrate the efficacy of the method at pinpointing the root cause of a problem. The obtained results suggest that the approach is adept at refining the diagnostic information obtained from each of the different machine components monitored, therefore improving the reliability of the health assessment of

  2. Anti-kindling Induced by Two-Stage Coordinated Reset Stimulation with Weak Onset Intensity

    PubMed Central

    Zeitler, Magteld; Tass, Peter A.

    2016-01-01

    Abnormal neuronal synchrony plays an important role in a number of brain diseases. To specifically counteract abnormal neuronal synchrony by desynchronization, Coordinated Reset (CR) stimulation, a spatiotemporally patterned stimulation technique, was designed with computational means. In neuronal networks with spike timing–dependent plasticity CR stimulation causes a decrease of synaptic weights and finally anti-kindling, i.e., unlearning of abnormally strong synaptic connectivity and abnormal neuronal synchrony. Long-lasting desynchronizing aftereffects of CR stimulation have been verified in pre-clinical and clinical proof of concept studies. In general, for different neuromodulation approaches, both invasive and non-invasive, it is desirable to enable effective stimulation at reduced stimulation intensities, thereby avoiding side effects. For the first time, we here present a two-stage CR stimulation protocol, where two qualitatively different types of CR stimulation are delivered one after another, and the first stage comes at a particularly weak stimulation intensity. Numerical simulations show that a two-stage CR stimulation can induce the same degree of anti-kindling as a single-stage CR stimulation with intermediate stimulation intensity. This stimulation approach might be clinically beneficial in patients suffering from brain diseases characterized by abnormal neuronal synchrony where a first treatment stage should be performed at particularly weak stimulation intensities in order to avoid side effects. This might, e.g., be relevant in the context of acoustic CR stimulation in tinnitus patients with hyperacusis or in the case of electrical deep brain CR stimulation with sub-optimally positioned leads or side effects caused by stimulation of the target itself. We discuss how to apply our method in first in man and proof of concept studies. PMID:27242500

  3. Hydrogen and methane production through two-stage mesophilic anaerobic digestion of olive pulp.

    PubMed

    Koutrouli, Eleni C; Kalfas, Haralabos; Gavala, Hariklia N; Skiadas, Ioannis V; Stamatelatou, Katerina; Lyberatos, Gerasimos

    2009-08-01

    The present study focused on the anaerobic biohydrogen production from olive pulp (two phase olive mill wastes, TPOMW) and the subsequent anaerobic treatment of the effluent for methane production under mesophilic conditions in a two-stage process. Biohydrogen production from water-diluted (1:4) olive pulp was investigated at hydraulic retention times (HRT) of 30 h, 14.5 h and 7.5 h while methane production from the effluent of hydrogenogenic reactor was studied at 20 d, 15 d, 10d and 5d HRT. In comparison with previous studies, it has been shown that the thermophilic hydrogen production process was more efficient than the mesophilic one in both hydrogen production rate and yield. The methanogenic reactor was successfully operated at 20, 15 and 10 days HRT while it failed when an HRT of 5 days was applied. Methane productivity reached the maximum value of 1.13+/-0.08 L/L/d at 10 days HRT whereas the methane yield increased with the HRT. The Anaerobic Digestion Model no. 1 (ADM1) was applied to the obtained experimental data from the methanogenic reactor to simulate the digester response at all HRT tested. The ability of the model to predict the experimental results was evident even in the case of the process failure, thus implying that the ADM1 could be a valuable tool for process design even in the case of a complex feedstock. In general, the two-stage anaerobic digestion proved to be a stable, reliable and effective process for energy recovery and stabilization treatment of olive pulp.

  4. Enhanced bio-energy recovery in a two-stage hydrogen/methane fermentation process.

    PubMed

    Lee, M J; Song, J H; Hwang, S J

    2009-01-01

    A two-stage hydrogen/methane fermentation process has emerged as a feasible engineering system to recover bio-energy from wastewater. Hydrogen-producing bacteria (HPB) generate hydrogen from readily available carbohydrates, and organic acids produced during the hydrogen fermentation step can be degraded to generate methane in the following step. Three strong acids, HCl, H(2)SO(4), and HNO(3), were tested to determine the appropriate pre-treatment method for enhanced hydrogen production. The hydrogen production rates of 230, 290, and 20 L/kg(-glucose)/day was observed for the sludge treated with HCl, H(2)SO(4), and HNO(3), respectively, indicating that the acid pre-treatment using either HCl or H(2)SO(4) resulted in a significant increase in hydrogen production. The fluorescent in situ hybridization method indicated that the acid pre-treatment selectively enriched HPB including Clostridium sp. of cluster I from inoculum sludge. After hydrogen fermentation was terminated, the sludge was introduced to a methane fermentation reactor. This experiment showed methane production rates of 100, 30, and 13 L/kg(-glucose)/day for the sludge pre-treated with HCl, H(2)SO(4), and HNO(3), respectively, implying that both sulfate and nitrate inhibited the activity of methane-producing bacteria. Consequently, the acid pre-treatment might be a feasible option to enhance biogas recovery in the two-stage fermentation process, and HCl was selected as the optimal strong acid for the enrichment of HPB and the continuous production of methane.

  5. Antibiotic-Loaded Spacer for Two-Stage Revision of Infected Total Knee Arthroplasty.

    PubMed

    Vecchini, Eugenio; Micheloni, Gian Mario; Perusi, Francesco; Scaglia, Marco; Maluta, Tommaso; Lavini, Franco; Bondi, Manuel; Dall'Oca, Carlo; Magnan, Bruno

    2017-03-01

    Infection of total knee arthroplasty (TKA) is a challenge in orthopedic surgery. In literature TKA infection is classified according to the time after surgery: acute postoperative; late chronic; acute hematogenous; positive intraoperative microbiological growth. The purpose of this study is to present the results of the use of a preformed antibiotic-loaded spacer in TKA infections, treated by a two-stage revision procedure. A series of 19 consecutive patients (20 knees) with a diagnosis of infected TKA were treated from January 2003 to February 2012. Two-stage reimplantation protocols were completed only in 16 patients and these data were included in the study. We lost three patients at follow-up. An antibiotic-loaded preformed articulating polymethylmethacrylate spacer was applied. Patients were observed 1, 3, and 6 months postoperatively and then yearly for clinical and radiographic examination. The mean American Knee Society Score improved from 68.4 preoperatively (range, from 34 to 108) to 112.7 at final follow-up (range, from 49 to 180). The pain was evaluated as part of clinical score. It improved from an average of 19.3 preoperatively (range, from 10 to 30) to 34.3 at final follow-up (range, from 10 to 50). The average range of motion improved from 40.1 degrees (range, from 6 to 90 degrees) to 79.3 degrees (range, from 45 to 125 degrees). The use of the spacer allows obtaining a reduction of pain, an improvement of quality of life in the period of time between the two surgical stages and an easier reimplantation of TKA.

  6. Mineral chemistry of the Tissint meteorite: Indications of two-stage crystallization in a closed system

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Baziotis, Ioannis P.; Asimow, Paul D.; Bodnar, Robert J.; Taylor, Lawrence A.

    2016-12-01

    The Tissint meteorite is a geochemically depleted, olivine-phyric shergottite. Olivine megacrysts contain 300-600 μm cores with uniform Mg# ( 80 ± 1) followed by concentric zones of Fe-enrichment toward the rims. We applied a number of tests to distinguish the relationship of these megacrysts to the host rock. Major and trace element compositions of the Mg-rich core in olivine are in equilibrium with the bulk rock, within uncertainty, and rare earth element abundances of melt inclusions in Mg-rich olivines reported in the literature are similar to those of the bulk rock. Moreover, the P Kα intensity maps of two large olivine grains show no resorption between the uniform core and the rim. Taken together, these lines of evidence suggest the olivine megacrysts are phenocrysts. Among depleted olivine-phyric shergottites, Tissint is the first one that acts mostly as a closed system with olivine megacrysts being the phenocrysts. The texture and mineral chemistry of Tissint indicate a crystallization sequence of: olivine (Mg# 80 ± 1) → olivine (Mg# 76) + chromite → olivine (Mg# 74) + Ti-chromite → olivine (Mg# 74-63) + pyroxene (Mg# 76-65) + Cr-ulvöspinel → olivine (Mg# 63-35) + pyroxene (Mg# 65-60) + plagioclase, followed by late-stage ilmenite and phosphate. The crystallization of the Tissint meteorite likely occurred in two stages: uniform olivine cores likely crystallized under equilibrium conditions; and a fractional crystallization sequence that formed the rest of the rock. The two-stage crystallization without crystal settling is simulated using MELTS and the Tissint bulk composition, and can broadly reproduce the crystallization sequence and mineral chemistry measured in the Tissint samples. The transition between equilibrium and fractional crystallization is associated with a dramatic increase in cooling rate and might have been driven by an acceleration in the ascent rate or by encounter with a steep thermal gradient in the Martian crust.

  7. Performance evaluation of two-stage fuel cycle from SFR to PWR

    SciTech Connect

    Fei, T.; Hoffman, E.A.; Kim, T.K.; Taiwo, T.A.

    2013-07-01

    One potential fuel cycle option being considered is a two-stage fuel cycle system involving the continuous recycle of transuranics in a fast reactor and the use of bred plutonium in a thermal reactor. The first stage is a Sodium-cooled Fast Reactor (SFR) fuel cycle with metallic U-TRU-Zr fuel. The SFRs need to have a breeding ratio greater than 1.0 in order to produce fissile material for use in the second stage. The second stage is a PWR fuel cycle with uranium and plutonium mixed oxide fuel based on the design and performance of the current state-of-the-art commercial PWRs with an average discharge burnup of 50 MWd/kgHM. This paper evaluates the possibility of this fuel cycle option and discusses its fuel cycle performance characteristics. The study focuses on an equilibrium stage of the fuel cycle. Results indicate that, in order to avoid a positive coolant void reactivity feedback in the stage-2 PWR, the reactor requires high quality of plutonium from the first stage and minor actinides in the discharge fuel of the PWR needs to be separated and sent back to the stage-1 SFR. The electricity-sharing ratio between the 2 stages is 87.0% (SFR) to 13.0% (PWR) for a TRU inventory ratio (the mass of TRU in the discharge fuel divided by the mass of TRU in the fresh fuel) of 1.06. A sensitivity study indicated that by increasing the TRU inventory ratio to 1.13, The electricity generation fraction of stage-2 PWR is increased to 28.9%. The two-stage fuel cycle system considered in this study was found to provide a high uranium utilization (>80%). (authors)

  8. Cost-utility analysis of an advanced pressure ulcer management protocol followed by trained wound, ostomy, and continence nurses.

    PubMed

    Kaitani, Toshiko; Nakagami, Gojiro; Iizaka, Shinji; Fukuda, Takashi; Oe, Makoto; Igarashi, Ataru; Mori, Taketoshi; Takemura, Yukie; Mizokami, Yuko; Sugama, Junko; Sanada, Hiromi

    2015-01-01

    The high prevalence of severe pressure ulcers (PUs) is an important issue that requires to be highlighted in Japan. In a previous study, we devised an advanced PU management protocol to enable early detection of and intervention for deep tissue injury and critical colonization. This protocol was effective for preventing more severe PUs. The present study aimed to compare the cost-effectiveness of the care provided using an advanced PU management protocol, from a medical provider's perspective, implemented by trained wound, ostomy, and continence nurses (WOCNs), with that of conventional care provided by a control group of WOCNs. A Markov model was constructed for a 1-year time horizon to determine the incremental cost-effectiveness ratio of advanced PU management compared with conventional care. The number of quality-adjusted life-years gained, and the cost in Japanese yen (¥) ($US1 = ¥120; 2015) was used as the outcome. Model inputs for clinical probabilities and related costs were based on our previous clinical trial results. Univariate sensitivity analyses were performed. Furthermore, a Bayesian multivariate probability sensitivity analysis was performed using Monte Carlo simulations with advanced PU management. Two different models were created for initial cohort distribution. For both models, the expected effectiveness for the intervention group using advanced PU management techniques was high, with a low expected cost value. The sensitivity analyses suggested that the results were robust. Intervention by WOCNs using advanced PU management techniques was more effective and cost-effective than conventional care.

  9. An Experimental Study of Dynamic Stall on Advanced Airfoil Sections. Volume 2. Pressure and Force Data.

    DTIC Science & Technology

    1982-09-01

    pressure or to the tunnel total-pressure. By using positive gage pressures for cali- bration references, the transducer diaphragms were deformed in the...L aU CD 9; -~C C) -4. r 0~ ~ C _ __ z ~ - ~IE- - £ 1 0 i rN 0 o C0 NP 491) II oo 0x 0+ IIn C .:) U I-\\ 𔃺o Lil 0_ LPC ’ 0 cx N - Li C)-92 o o3 C, C

  10. Effects of combined lipoic acid and pyridoxine on albuminuria, advanced glycation end-products, and blood pressure in diabetic nephropathy.

    PubMed

    Noori, Nazanin; Tabibi, Hadi; Hosseinpanah, Farhad; Hedayati, Mehdi; Nafar, Mohsen

    2013-01-01

    This study was designed to investigate the effects of combined administration of lipoic acid and pyridoxine on albuminuria, oxidative stress, blood pressure, serum advanced glycation end-products, nitric oxide (NO), and endothelin-1 in patients with diabetic nephropathy. Thirty-four patients were randomly assigned to either a supplement group or a placebo group. The patients in the supplement group received 800 mg lipoic acid and 80 mg pyridoxine daily for 12 weeks, whereas the placebo group received corresponding placebos. Urinary albumin, serum malondialdehyde (MDA), and systolic blood pressure decreased significantly in the supplement group compared to the placebo group (p < 0.05). Serum NO increased in the supplement group compared to the placebo group (p < 0.05). Serum pentosidine and carboxymethyl lysine decreased significantly in the supplement group at the end of week 12 compared to baseline (p < 0.05). No statistically significant differences were observed between the two groups in mean changes of serum endothelin-1, glucose, and diastolic blood pressure. The present study indicates that combined administration of lipoic acid and pyridoxine improves albuminuria in patients with diabetic nephropathy by reducing oxidative stress, advanced glycation end-products, and systolic blood pressure. The reduction in microalbuminuria may be of benefit in retarding the progression of diabetic nephropathy.

  11. A PRIOR EVALUATION OF TWO-STAGE CLUSTER SAMPLING FOR ACCURACY ASSESSMENT OF LARGE-AREA LAND-COVER MAPS

    EPA Science Inventory

    Two-stage cluster sampling reduces the cost of collecting accuracy assessment reference data by constraining sample elements to fall within a limited number of geographic domains (clusters). However, because classification error is typically positively spatially correlated, withi...

  12. AREA DETERMINATION OF DIABETIC FOOT ULCER IMAGES USING A CASCADED TWO-STAGE SVM BASED CLASSIFICATION.

    PubMed

    Wang, Lei; Pedersen, Peder; Agu, Emmanuel; Strong, Diane; Tulu, Bengisu

    2016-11-23

    It is standard practice for clinicians and nurses to primarily assess patients' wounds via visual examination. This subjective method can be inaccurate in wound assessment and also represents a significant clinical workload. Hence, computer-based systems, especially implemented on mobile devices, can provide automatic, quantitative wound assessment and can thus be valuable for accurately monitoring wound healing status. Out of all wound assessment parameters, the measurement of the wound area is the most suitable for automated analysis. Most of the current wound boundary determination methods only process the image of the wound area along with a small amount of surrounding healthy skin. In this paper, we present a novel approach that uses Support Vector Machine (SVM) to determine the wound boundary on a foot ulcer image captured with an image capture box, which provides controlled lighting, angle and range conditions. The Simple Linear Iterative Clustering (SLIC) method is applied for effective super-pixel segmentation. A cascaded two-stage classifier is trained as follows: in the first stage a set of k binary SVM classifiers are trained and applied to different subsets of the entire training images dataset, and a set of incorrectly classified instances are collected. In the second stage, another binary SVM classifier is trained on the incorrectly classified set. We extracted various color and texture descriptors from super-pixels that are used as input for each stage in the classifier training. Specifically, we apply the color and Bag-of-Word (BoW) representation of local Dense SIFT features (DSIFT) as the descriptor for ruling out irrelevant regions (first stage), and apply color and wavelet based features as descriptors for distinguishing healthy tissue from wound regions (second stage). Finally, the detected wound boundary is refined by applying a Conditional Random Field (CRF) image processing technique. We have implemented the wound classification on a Nexus

  13. Two-stage induced differentiation of OCT4+/Nanog+ stem-like cells in lung adenocarcinoma

    PubMed Central

    Ma, Meili; Lou, Yuqing; Zhang, Yanwei; Wu, Lixia; Chang, David W.; Zhao, Picheng; Dong, Qianggang; Wu, Xifeng; Han, Baohui

    2016-01-01

    Stem-like cells in solid tumors are purported to contribute to cancer development and poor treatment outcome. The abilities to self-renew, differentiate, and resist anticancer therapies are hallmarks of these rare cells, and steering them into lineage commitment may be one strategy to curb cancer development or progression. Vitamin D is a prohormone that can alter cell growth and differentiation and may induce the differentiation cancer stem-like cells. In this study, octamer-binding transcription factor 4 (OCT4)-positive/Nanog homeobox (Nanog)- positive lung adenocarcinoma stem-like cells (LACSCs) were enriched from spheroid cultured SPC-A1 cells and differentiated by a two-stage induction (TSI) method, which involved knockdown of hypoxia-inducible factor 1-alpha (HIF1α) expression (first stage) followed by sequential induction with 1alpha,25-dihydroxyvitamin D3 (1,25(OH)2D3, VD3) and suberoylanilide hydroxamic acid (SAHA) treatment (second stage). The results showed the HIF1α-knockdowned cells displayed diminished cell invasion and clonogenic activities. Moreover, the TSI cells highly expressed tumor suppressor protein p63 (P63) and forkhead box J1 (FOXJ1) and lost stem cell characteristics, including absent expression of OCT4 and Nanog. These cells regained sensitivity to cisplatin in vitro while losing tumorigenic capacity and decreased tumor cell proliferation in vivo. Our results suggest that induced transdifferentiation of LACSCs by vitamin D and SAHA may become novel therapeutic avenue to alter tumor cell phenotypes and improve patient outcome. SIGNIFICANCE STATEMENT The development and progression of lung cancer may involve rare population of stem-like cells that have the ability to grow, differentiate, and resist drug treatment. However, current therapeutic strategies have mostly focused on tumor characteristics and neglected the potential source of cells that may contribute to poor clinical outcome. We generated lung adenocarcinoma stem-like cells from

  14. Comparative Analysis of Direct Hospital Care Costs between Aseptic and Two-Stage Septic Knee Revision

    PubMed Central

    Kasch, Richard; Merk, Sebastian; Assmann, Grit; Lahm, Andreas; Napp, Matthias; Merk, Harry; Flessa, Steffen

    2017-01-01

    Background The most common intermediate and long-term complications of total knee arthroplasty (TKA) include aseptic and septic failure of prosthetic joints. These complications cause suffering, and their management is expensive. In the future the number of revision TKA will increase, which involves a greater financial burden. Little concrete data about direct costs for aseptic and two-stage septic knee revisions with an in depth-analysis of septic explantation and implantation is available. Questions/Purposes A retrospective consecutive analysis of the major partial costs involved in revision TKA for aseptic and septic failure was undertaken to compare 1) demographic and clinical characteristics, and 2) variable direct costs (from a hospital department’s perspective) between patients who underwent single-stage aseptic and two-stage septic revision of TKA in a hospital providing maximum care. We separately analyze the explantation and implantation procedures in septic revision cases and identify the major cost drivers of knee revision operations. Methods A total of 106 consecutive patients (71 aseptic and 35 septic) was included. All direct costs of diagnosis, surgery, and treatment from the hospital department’s perspective were calculated as real purchase prices. Personnel involvement was calculated in units of minutes. Results Aseptic versus septic revisions differed significantly in terms of length of hospital stay (15.2 vs. 39.9 days), number of reported secondary diagnoses (6.3 vs. 9.8) and incision-suture time (108.3 min vs. 193.2 min). The management of septic revision TKA was significantly more expensive than that of aseptic failure ($12,223.79 vs. $6,749.43) (p <.001). On the level of the separate hospitalizations the mean direct costs of explantation stage ($4,540.46) were lower than aseptic revision TKA ($6,749.43) which were again lower than those of the septic implantation stage ($7,683.33). All mean costs of stays were not comparable as they

  15. Test and Evaluation of a Pilot Two-Stage Precipitator for Jet Engine Test Cell Exhaust Gas Cleaning

    DTIC Science & Technology

    1976-04-01

    then available for emission control . A two- stage electrostatic precipitator was recommended as .j he most viable alternative to a concept then being...TEST AND EVALUATION OF A "PILOT TWO* STAGE PRECIPITATOR FOR JET ENGINE TEST CELL 0 EXHAUST GA, S CLEANING C44 NAVAL AIR REWORK FACILITY NAVAL AIR...is the release you requested in your telephone conversation of 20 July 1976 with the undersigned. Yourn very tru~ly, Head Specifications Branch a 21

  16. Advanced Packaging Technology Used in Fabricating a High-Temperature Silicon Carbide Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Beheim, Glenn M.

    2003-01-01

    The development of new aircraft engines requires the measurement of pressures in hot areas such as the combustor and the final stages of the compressor. The needs of the aircraft engine industry are not fully met by commercially available high-temperature pressure sensors, which are fabricated using silicon. Kulite Semiconductor Products and the NASA Glenn Research Center have been working together to develop silicon carbide (SiC) pressure sensors for use at high temperatures. At temperatures above 850 F, silicon begins to lose its nearly ideal elastic properties, so the output of a silicon pressure sensor will drift. SiC, however, maintains its nearly ideal mechanical properties to extremely high temperatures. Given a suitable sensor material, a key to the development of a practical high-temperature pressure sensor is the package. A SiC pressure sensor capable of operating at 930 F was fabricated using a newly developed package. The durability of this sensor was demonstrated in an on-engine test. The SiC pressure sensor uses a SiC diaphragm, which is fabricated using deep reactive ion etching. SiC strain gauges on the surface of the diaphragm sense the pressure difference across the diaphragm. Conventionally, the SiC chip is mounted to the package with the strain gauges outward, which exposes the sensitive metal contacts on the chip to the hostile measurement environment. In the new Kulite leadless package, the SiC chip is flipped over so that the metal contacts are protected from oxidation by a hermetic seal around the perimeter of the chip. In the leadless package, a conductive glass provides the electrical connection between the pins of the package and the chip, which eliminates the fragile gold wires used previously. The durability of the leadless SiC pressure sensor was demonstrated when two 930 F sensors were tested in the combustor of a Pratt & Whitney PW4000 series engine. Since the gas temperatures in these locations reach 1200 to 1300 F, the sensors were

  17. Design and Characterization of Thin Stainless Steel Burst Disks for Increasing Two-Stage Light Gas Launcher Efficiency

    NASA Technical Reports Server (NTRS)

    Tylka, Jonathan M.; Johnson, Kenneth L.; Henderson, Donald; Rodriguez, Karen

    2012-01-01

    Laser etched 300 series Stainless Steel Burst Disks (SSBD) ranging between 0.178 mm (0.007-in.) and 0.508mm (0.020-in.) thick were designed for use in a 17-caliber two-stage light gas launcher. First, a disk manufacturing method was selected using a combination of wire electrical discharge machining (EDM) to form the blank disks and laser etching to define the pedaling fracture pattern. Second, a replaceable insert was designed to go between the SSDB and the barrel. This insert reduced the stress concentration between the SSBD and the barrel, providing a place for the petals of the SSDB to open, and protecting the rifling on the inside of the barrel. Thereafter, a design of experiments was implemented to test and characterize the burst characteristics of SSBDs. Extensive hydrostatic burst testing of the SSBDs was performed to complete the design of experiments study with one-hundred and seven burst tests. The experiment simultaneously tested the effects of the following: two SSBD material states (full hard, annealed); five SSBD thicknesses 0.178, 0.254, 0.305, 0.381 mm (0.007, 0.010, 0.012, 0.015, 0.020-in.); two grain directions relative); number of times the laser etch pattern was repeated (varies between 5-200 times); two heat sink configurations (with and without heat sink); and, two barrel configurations (with and without insert). These tests resulted in the quantification of the relationship between SSBD thickness, laser etch parameters, and desired burst pressure. Of the factors investigated only thickness and number of laser etches were needed to develop a mathematical relationship predicting hydrostatic burst pressure of disks using the same barrel configuration. The fracture surfaces of two representative SSBD bursts were then investigated with a scanning electron microscope, one burst hydrostatically in a fixture and another dynamically in the launcher. The fracture analysis verified that both burst conditions resulted in a ductile overload failure

  18. Reducing the risk of foaming and decreasing viscosity by two-stage anaerobic digestion of sugar beet pressed pulp.

    PubMed

    Stoyanova, Elitza; Forsthuber, Boris; Pohn, Stefan; Schwarz, Christian; Fuchs, Werner; Bochmann, Günther

    2014-04-01

    Anaerobic digestion (AD) of sugar beet pressed pulp (SBPP) is a promising treatment concept. It produces biogas as a renewable energy source making sugar production more energy efficient and it turns SBPP from a residue into a valuable resource. In this study one- and two-stage mono fermentation at mesophilic conditions in a continuous stirred tank reactor were compared. Also the optimal incubation temperature for the pre-acidification stage was studied. The fastest pre-acidification, with a hydraulic retention time (HRT) of 4 days, occurred at a temperature of 55 °C. In the methanogenic reactor of the two-stage system stable fermentation at loading rate of 7 kg VS/m³ d was demonstrated. No artificial pH adjustment was necessary to maintain optimum levels in both the pre-acidification and the methanogenic reactor. The total HRT of the two-stage AD was 36 days which is considerably lower compared to the one-stage AD (50 days). The frequently observed problem of foaming at high loading rates was less severe in the two-stage reactor. Moreover the viscosity of digestate in the methanogenic stage of the two-stage fermentation was in average tenfold lower than in the one-stage fermentation. This decreases the energy input for the reactor stirring about 80 %. The observed advantages make the two-stage process economically attractive, despite higher investments for a two reactor system.

  19. Opposed piston linear compressor driven two-stage Stirling Cryocooler for cooling of IR sensors in space application

    NASA Astrophysics Data System (ADS)

    Bhojwani, Virendra; Inamdar, Asif; Lele, Mandar; Tendolkar, Mandar; Atrey, Milind; Bapat, Shridhar; Narayankhedkar, Kisan

    2017-04-01

    A two-stage Stirling Cryocooler has been developed and tested for cooling IR sensors in space application. The concept uses an opposed piston linear compressor to drive the two-stage Stirling expander. The configuration used a moving coil linear motor for the compressor as well as for the expander unit. Electrical phase difference of 80 degrees was maintained between the voltage waveforms supplied to the compressor motor and expander motor. The piston and displacer surface were coated with Rulon an anti-friction material to ensure oil less operation of the unit. The present article discusses analysis results, features of the cryocooler and experimental tests conducted on the developed unit. The two-stages of Cryo-cylinder and the expander units were manufactured from a single piece to ensure precise alignment between the two-stages. Flexure bearings were used to suspend the piston and displacer about its mean position. The objective of the work was to develop a two-stage Stirling cryocooler with 2 W at 120 K and 0.5 W at 60 K cooling capacity for the two-stages and input power of less than 120 W. The Cryocooler achieved a minimum temperature of 40.7 K at stage 2.

  20. Experimental and numerical evaluation of the performance of supersonic two-stage high-velocity oxy-fuel thermal spray (Warm Spray) gun

    NASA Astrophysics Data System (ADS)

    Katanoda, H.; Morita, H.; Komatsu, M.; Kuroda, S.

    2011-03-01

    The water-cooled supersonic two-stage high-velocity oxy-fuel (HVOF) thermal spray gun was developed to make a coating of temperature-sensitive material, such as titanium, on a substrate. The gun has a combustion chamber (CC) followed by a mixing chamber (MC), in which the combustion gas is mixed with the nitrogen gas at room temperature. The mixed gas is accelerated to supersonic speed through a converging-diverging (C-D) nozzle followed by a straight passage called the barrel. This paper proposes an experimental procedure to estimate the cooling rate of CC, MC and barrel separately. Then, the mathematical model is presented to predict the pressure and temperature in the MC for the specific mass flow rates of fuel, oxygen and nitrogen by assuming chemical equilibrium with water-cooling in the CC and MC, and frozen flow with constant specific heat from stagnant condition to the throat in the CC and MC. Finally, the present mathematical model was validated by comparing the calculated and measured stagnant pressures of the CC of the two-stage HVOF gun.

  1. Beyond two-stage models for lung carcinogenesis in the Mayak workers: implications for plutonium risk.

    PubMed

    Zöllner, Sascha; Sokolnikov, Mikhail E; Eidemüller, Markus

    2015-01-01

    Mechanistic multi-stage models are used to analyze lung-cancer mortality after Plutonium exposure in the Mayak-workers cohort, with follow-up until 2008. Besides the established two-stage model with clonal expansion, models with three mutation stages as well as a model with two distinct pathways to cancer are studied. The results suggest that three-stage models offer an improved description of the data. The best-fitting models point to a mechanism where radiation increases the rate of clonal expansion. This is interpreted in terms of changes in cell-cycle control mediated by bystander signaling or repopulation following cell killing. No statistical evidence for a two-pathway model is found. To elucidate the implications of the different models for radiation risk, several exposure scenarios are studied. Models with a radiation effect at an early stage show a delayed response and a pronounced drop-off with older ages at exposure. Moreover, the dose-response relationship is strongly nonlinear for all three-stage models, revealing a marked increase above a critical dose.

  2. Beyond Two-Stage Models for Lung Carcinogenesis in the Mayak Workers: Implications for Plutonium Risk

    PubMed Central

    Zöllner, Sascha; Sokolnikov, Mikhail E.; Eidemüller, Markus

    2015-01-01

    Mechanistic multi-stage models are used to analyze lung-cancer mortality after Plutonium exposure in the Mayak-workers cohort, with follow-up until 2008. Besides the established two-stage model with clonal expansion, models with three mutation stages as well as a model with two distinct pathways to cancer are studied. The results suggest that three-stage models offer an improved description of the data. The best-fitting models point to a mechanism where radiation increases the rate of clonal expansion. This is interpreted in terms of changes in cell-cycle control mediated by bystander signaling or repopulation following cell killing. No statistical evidence for a two-pathway model is found. To elucidate the implications of the different models for radiation risk, several exposure scenarios are studied. Models with a radiation effect at an early stage show a delayed response and a pronounced drop-off with older ages at exposure. Moreover, the dose-response relationship is strongly nonlinear for all three-stage models, revealing a marked increase above a critical dose. PMID:26000637

  3. Chemistry of the extractive phase of two stage liquefaction. [9-10-dihydroanthracene and octahydrophenanthrene

    SciTech Connect

    Neuworth, M.B.; Heredy, L.A.; McCoy, L.R.; Skowronski, R.P.; Ratto, J.J.

    1985-04-19

    An experimental program has been conducted to investigate the chemistry of the extractive phase of the Integrated Two-Stage Liquefaction process. The long-term objective of the program is a study of the structural correlations between the starting coal, the coal-derived process solvent, and the primary liquefaction products. The two specific objectives chosen for study under this contract were (1) an investigation of experimental techniques for determining the proportion of cyclic and acyclic alkyl bridges as key weak linkages in coal and coal extract and (2) the generation of experimental information on hydroaromatic structures in coal and their probable role in liquefaction. The experimental technique which was devised for this investigation involved acid-catalyzed depolymerization to cleave methylene and other alkyl bridges in the coal and catalytic dehydrogenation to obtain information on hydroaromatic structures. The results of these experiments were supplemented by structural characterization of the process solvent and the coal extract, experiments using model compounds, and the application of results obtained by others. The experimental work was carried out using Illinois No. 6 coal, coal extract, and process solvent obtained from the PDU coal liquefaction plant operated by C.E. Lummus Crest, Inc. Coal depolymerization was carried out by using phenol-BF/sub 3/ and 3-fluorophenol-BF/sub 3/. Dehydrogenation of coal process solvent fraction and model compounds was carried out using a solvent and a palladium catalyst. The results and conclusions are discussed. 16 refs., 41 figs., 26 tabs.

  4. Orbiter Trajectory Analysis for a Two-Stage Reusable Launch Vehicle

    NASA Technical Reports Server (NTRS)

    Cowling, Adam L.

    2011-01-01

    Trajectory analysis performed on NASA's reference two-stage-to-orbit launch vehicle upper stage will be presented. The work was completed in support of the Hypersonics Multidisciplinary Analysis and Optimization effort for the NASA-Air Force Joint System Study. Three degree-of-freedom (3-DOF) untrimmed trajectory analysis was performed for the orbiter ascent, closure and re-entry. An iterative closure process resulted in a 333,000 lb initial mass for the orbiter. The re-entry trajectory satisfied heating constraints for all payload out cases and met the constraints with reduced margins for payload in cases. Abort trajectories for engine out at staging, engine out during ascent, and failure to circularize in orbit, gave insight to the robustness of the orbiter. A trimmed ascent trajectory defined an engine gimbal location and the body flap angle best suited for maximizing injected mass. A trimmed re-entry trajectory revealed a need to update the trim routine to accommodate full flap aerodynamic data.

  5. Hydrogen and methane production from household solid waste in the two-stage fermentation process.

    PubMed

    Liu, Dawei; Liu, Dapeng; Zeng, Raymond J; Angelidaki, Irini

    2006-06-01

    A two-stage process combined hydrogen and methane production from household solid waste was demonstrated working successfully. The yield of 43 mL H(2)/g volatile solid (VS) added was generated in the first hydrogen production stage and the methane production in the second stage was 500 mL CH(4)/g VS added. This figure was 21% higher than the methane yield from the one-stage process, which was run as control. Sparging of the hydrogen reactor with methane gas resulted in doubling of the hydrogen production. pH was observed as a key factor affecting fermentation pathway in hydrogen production stage. The optimum pH range for hydrogen production in this system was in the range from 5 to 5.5. The short hydraulic retention time (2 days) applied in the first stage was enough to separate acidogenesis from methanogenesis. No additional control for preventing methanogenesis in the first stage was necessary. Furthermore, this study also provided direct evidence in the dynamic fermentation process that, hydrogen production increase was reflected by acetate to butyrate ratio increase in liquid phase.

  6. Treatment of Ammonia Nitrogen Wastewater in Low Concentration by Two-Stage Ozonization

    PubMed Central

    Luo, Xianping; Yan, Qun; Wang, Chunying; Luo, Caigui; Zhou, Nana; Jian, Chensheng

    2015-01-01

    Ammonia nitrogen wastewater (about 100 mg/L) was treated by two-stage ozone oxidation method. The effects of ozone flow rate and initial pH on ammonia removal were studied, and the mechanism of ammonia nitrogen removal by ozone oxidation was discussed. After the primary stage of ozone oxidation, the ammonia removal efficiency reached 59.32% and pH decreased to 6.63 under conditions of 1 L/min ozone flow rate and initial pH 11. Then, the removal efficiency could be over 85% (the left ammonia concentration was lower than 15 mg/L) after the second stage, which means the wastewater could have met the national discharge standards of China. Besides, the mechanism of ammonia removal by ozone oxidation was proposed by detecting the products of the oxidation: ozone oxidation directly and ·OH oxidation; ammonia was mainly transformed into NO3−-N, less into NO2−-N, not into N2. PMID:26404353

  7. A two-stage Bayesian design for co-development of new drugs and companion diagnostics.

    PubMed

    Karuri, Stella Wanjugu; Simon, Richard

    2012-05-10

    Most new drug development in oncology is based on targeting specific molecules. Genomic profiles and deregulated drug targets vary from patient to patient making new treatments likely to benefit only a subset of patients traditionally grouped in the same clinical trials. Predictive biomarkers are being developed to identify patients who are most likely to benefit from a particular treatment; however, their biological basis is not always conclusive. The inclusion of marker-negative patients in a trial is therefore sometimes necessary for a more informative evaluation of the therapy. In this paper, we present a two-stage Bayesian design that includes both marker-positive and marker-negative patients in a clinical trial. We formulate a family of prior distributions that represent the degree of a priori confidence in the predictive biomarker. To avoid exposing patients to a treatment to which they may not be expected to benefit, we perform an interim analysis that may stop accrual of marker-negative patients or accrual of all patients. We demonstrate with simulations that the design and priors used control type I errors, give adequate power, and enable the early futility analysis of test-negative patients to be based on prior specification on the strength of evidence in the biomarker.

  8. A two-stage storage routing model for green roof runoff detention.

    PubMed

    Vesuviano, Gianni; Sonnenwald, Fred; Stovin, Virginia

    2014-01-01

    Green roofs have been adopted in urban drainage systems to control the total quantity and volumetric flow rate of runoff. Modern green roof designs are multi-layered, their main components being vegetation, substrate and, in almost all cases, a separate drainage layer. Most current hydrological models of green roofs combine the modelling of the separate layers into a single process; these models have limited predictive capability for roofs not sharing the same design. An adaptable, generic, two-stage model for a system consisting of a granular substrate over a hard plastic 'egg box'-style drainage layer and fibrous protection mat is presented. The substrate and drainage layer/protection mat are modelled separately by previously verified sub-models. Controlled storm events are applied to a green roof system in a rainfall simulator. The time-series modelled runoff is compared to the monitored runoff for each storm event. The modelled runoff profiles are accurate (mean Rt(2) = 0.971), but further characterization of the substrate component is required for the model to be generically applicable to other roof configurations with different substrate.

  9. TRM: a powerful two-stage machine learning approach for identifying SNP-SNP interactions.

    PubMed

    Lin, Hui-Yi; Chen, Y Ann; Tsai, Ya-Yu; Qu, Xiaotao; Tseng, Tung-Sung; Park, Jong Y

    2012-01-01

    Studies have shown that interactions of single nucleotide polymorphisms (SNPs) may play an important role in understanding the causes of complex disease. We have proposed an integrated machine learning method that combines two machine-learning methods-Random Forests (RF) and Multivariate Adaptive Regression Splines (MARS)-to identify a subset of important SNPs and detect interaction patterns more effectively and efficiently. In this two-stage RF-MARS (TRM) approach, RF is first applied to detect a predictive subset of SNPs, and then MARS is used to identify the interaction patterns. We evaluated the TRM performances in four models. RF variable selection was based on out-of-bag classification error rate (OOB) and variable important spectrum (IS). Our results support that RF(OOB) had better performance than MARS and RF(IS) in detecting important variables. This study demonstrates that TRM(OOB) , which is RF(OOB) plus MARS, has combined the strengths of RF and MARS in identifying SNP-SNP interactions in a scenario of 100 candidate SNPs. TRM(OOB) had greater true positive rate and lower false positive rate compared with MARS, particularly for searching interactions with a strong association with the outcome. Therefore, the use of TRM(OOB) is favored for exploring SNP-SNP interactions in a large-scale genetic variation study.

  10. Characterisation of the current switch mechanism in two-stage wire array Z-pinches

    SciTech Connect

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Hall, G. N.; Swadling, G. F.; Suzuki-Vidal, F.; Khoory, E.; Bland, S. N.; Pickworth, L.; Grouchy, P. de; Skidmore, J.; Suttle, L.; Waisman, E. M.

    2015-11-15

    In this paper, we describe the operation of a two-stage wire array z-pinch driven by the 1.4 MA, 240 ns rise-time Magpie pulsed-power device at Imperial College London. In this setup, an inverse wire array acts as a fast current switch, delivering a current pre-pulse into a cylindrical load wire array, before rapidly switching the majority of the generator current into the load after a 100–150 ns dwell time. A detailed analysis of the evolution of the load array during the pre-pulse is presented. Measurements of the load resistivity and energy deposition suggest significant bulk heating of the array mass occurs. The ∼5 kA pre-pulse delivers ∼0.8 J of energy to the load, leaving it in a mixed, predominantly liquid-vapour state. The main current switch occurs as the inverse array begins to explode and plasma expands into the load region. Electrical and imaging diagnostics indicate that the main current switch may evolve in part as a plasma flow switch, driven by the expansion of a magnetic cavity and plasma bubble along the length of the load array. Analysis of implosion trajectories suggests that approximately 1 MA switches into the load in 100 ns, corresponding to a doubling of the generator dI/dt. Potential scaling of the device to higher current machines is discussed.

  11. Regional frequency analysis at ungauged sites using a two-stage resampling generalized ensemble framework

    NASA Astrophysics Data System (ADS)

    Alobaidi, Mohammad H.; Marpu, Prashanth R.; Ouarda, Taha B. M. J.; Chebana, Fateh

    2015-10-01

    Regional frequency analysis (RFA) deals with the estimation of hydrological characteristics at sites where little or no data is available. Recently, machine learning applications to RFA have received considerable attention in terms of their flexibility in modeling as well as superior generalization ability compared to conventional approaches. The proper application of machine learning techniques, however, requires good understanding of the available information about system's dynamics, i.e. system variables. This paper presents two contributions to the literature. First, novel ensemble architecture, using a unique two-stage resampling approach, is proposed. The objective of the proposed ensemble model is to promote diversity within the individual learners and reduce over fitting. Second, the application of the proposed model is demonstrated in RFA case study to obtain improved regional flood quantile estimates at ungauged sites. A jackknife validation procedure is used for the evaluation of the model's performance. The method is applied to data from the province of Quebec, Canada. The model showed similar performance and generalization compared to major ensemble models in the literature, which were investigated in previous studies using the same data set. The proposed model confirmed the diversity requirement in ensemble modeling and, in the same time, validated the proposed model adherence to ensemble learning theory.

  12. Manufacture of gradient micro-structures of magnesium alloys using two stage extrusion dies

    SciTech Connect

    Hwang, Yeong-Maw; Huang, Tze-Hui; Alexandrov, Sergei; Naimark, Oleg Borisovich; Jeng, Yeau-Ren

    2013-12-16

    This paper aims to manufacture magnesium alloy metals with gradient micro-structures using hot extrusion process. The extrusion die was designed to have a straight channel part combined with a conical part. Materials pushed through this specially-designed die generate a non-uniform velocity distribution at cross sections inside the die and result in different strain and strain rate distributions. Accordingly, a gradient microstructure product can be obtained. Using the finite element analysis, the forming temperature, effective strain, and effective strain rate distributions at the die exit were firstly discussed for various inclination angles in the conical die. Then, hot extrusion experiments with a two stage die were conducted to obtain magnesium alloy products with gradient micro-structures. The effects of the inclination angle on the grain size distribution at cross sections of the products were also discussed. Using a die of an inclination angle of 15°, gradient micro-structures of the grain size decreasing gradually from 17 μm at the center to 4 μm at the edge of product were achieved.

  13. Parameter estimation for metabolic networks with two stage Bregman regularization homotopy inversion algorithm.

    PubMed

    Wang, Hong; Wang, Xi-cheng

    2014-02-21

    Metabolism is a very important cellular process and its malfunction contributes to human disease. Therefore, building dynamic models for metabolic networks with experimental data in order to analyze biological process rationally has attracted a lot of attention. Owing to the technical limitations, some unknown parameters contained in models need to be estimated effectively by means of the computational method. Generally, problems of parameter estimation of nonlinear biological network are known to be ill condition and multimodal. In particular, with the increasing amount and enlarging the scope of parameters, many optimization algorithms often fail to find a global solution. In this paper, two-stage variable factor Bregman regularization homotopy method is proposed. Discrete homotopy is used to identify the possible extreme region and continuous homotopy is executed for the purpose of stability of path tracing in the special region. Meanwhile, Latin hypercube sampling is introduced to get the good initial guess value and a perturbation strategy is developed to jump out of the local optimum. Three metabolic network inverse problems are investigated to demonstrate the effectiveness of the proposed method.

  14. Two-stage combined treatment of acid mine drainage and municipal wastewater.

    PubMed

    Deng, Dongyang; Lin, Lian-Shin

    2013-01-01

    This study examined the feasibility of the combined treatment of field-collected acid mine drainages (AMD, pH = 4.2 ± 0.9, iron = 112 ± 118 mg/L, sulfate = 1,846 ± 594 mg/L) and municipal wastewater (MWW, avg. chemical oxygen demand (COD) = 234-333 mg/L) using a two-stage process. The process consisted of batch mixing of the two wastes to condition the mixture solutions, followed by anaerobic biological treatment. The mixings performed under a range of AMD/MWW ratios resulted in phosphate removal of 9 to ∼100%, the mixture pH of 6.2-7.9, and COD/sulfate concentration ratio of 0.05-5.4. The biological treatment consistently removed COD and sulfate by >80% from the mixture solutions for COD/sulfate ratios of 0.6-5.4. Alkalinity was produced in the biological treatment causing increased pH and further removal of metals from the solutions. Scanning electron microscopy of produced sludge with energy dispersion analysis suggested chemical precipitation and associated adsorption and co-precipitation as the mechanisms for metal removal (Fe: >99%, Al: ∼100%, Mn: 75 to ∼100%, Ca: 52-81%, Mg: 13-76%, and Na: 56-76%). The study showed promising results for the treatment method and denoted the potential of developing innovative technologies for combined management of the two wastes in mining regions.

  15. Optimization of Boiling Water Reactor Loading Pattern Using Two-Stage Genetic Algorithm

    SciTech Connect

    Kobayashi, Yoko; Aiyoshi, Eitaro

    2002-10-15

    A new two-stage optimization method based on genetic algorithms (GAs) using an if-then heuristic rule was developed to generate optimized boiling water reactor (BWR) loading patterns (LPs). In the first stage, the LP is optimized using an improved GA operator. In the second stage, an exposure-dependent control rod pattern (CRP) is sought using GA with an if-then heuristic rule. The procedure of the improved GA is based on deterministic operators that consist of crossover, mutation, and selection. The handling of the encoding technique and constraint conditions by that GA reflects the peculiar characteristics of the BWR. In addition, strategies such as elitism and self-reproduction are effectively used in order to improve the search speed. The LP evaluations were performed with a three-dimensional diffusion code that coupled neutronic and thermal-hydraulic models. Strong axial heterogeneities and constraints dependent on three dimensions have always necessitated the use of three-dimensional core simulators for BWRs, so that optimization of computational efficiency is required. The proposed algorithm is demonstrated by successfully generating LPs for an actual BWR plant in two phases. One phase is only LP optimization applying the Haling technique. The other phase is an LP optimization that considers the CRP during reactor operation. In test calculations, candidates that shuffled fresh and burned fuel assemblies within a reasonable computation time were obtained.

  16. [Comparison research on two-stage sequencing batch MBR and one-stage MBR].

    PubMed

    Yuan, Xin-Yan; Shen, Heng-Gen; Sun, Lei; Wang, Lin; Li, Shi-Feng

    2011-01-01

    Aiming at resolving problems in MBR operation, like low nitrogen and phosphorous removal efficiency, severe membrane fouling and etc, comparison research on two-stage sequencing batch MBR (TSBMBR) and one-stage aerobic MBR has been done in this paper. The results indicated that TSBMBR owned advantages of SBR in removing nitrogen and phosphorous, which could make up the deficiency of traditional one-stage aerobic MBR in nitrogen and phosphorous removal. During steady operation period, effluent average NH4(+) -N, TN and TP concentration is 2.83, 12.20, 0.42 mg/L, which could reach domestic scenic environment use. From membrane fouling control point of view, TSBMBR has lower SMP in supernatant, specific trans-membrane flux deduction rate, membrane fouling resistant than one-stage aerobic MBR. The sedimentation and gel layer resistant of TSBMBR was only 6.5% and 33.12% of one-stage aerobic MBR. Besides high efficiency in removing nitrogen and phosphorous, TSBMBR could effectively reduce sedimentation and gel layer pollution on membrane surface. Comparing with one-stage MBR, TSBMBR could operate with higher trans-membrane flux, lower membrane fouling rate and better pollutants removal effects.

  17. Study on the Effect of Mutated Bacillus Megaterium in Two-Stage Fermentation of Vitamin C

    NASA Astrophysics Data System (ADS)

    Lü, Shujuan; Wang, Jun; Yao, Jianming; Yu, Zengliang

    2003-10-01

    Bacillus megaterium as a companion strain in two-stage fermentation of vitamin C could secrete some active substances to spur growth of Gluconobacter oxydans to produce 2-KLG. In the fermenting system where Gluconobacter oxydans was combined with GB82-a mutated strain of B. megaterium by ion implantation, the amount of 2-KLG harvested was larger than that produced by the original B. megaterium BP52 [1] being substituted for GB82. In this paper, we studied the effect of the active substances secreted by GB82 to enhance the capability of Gluconobacter oxydans to produce 2-KLG. The supernate of GB82 sampled at different cultivation times all had much more activity to spur Gluconobacter oxydans to yield 2-KLG than that of the original B. megaterium, which might be due to the genetic changes in the active components caused by ion implantation. Furthermore, the active substances of GB82's supernate would lose a part of its activity in extreme environments, which is typical of some proteins.

  18. Two-stage bile preparation with acetone for recovery of fluorescent aromatic compounds (FACs).

    PubMed

    Karami, Ali; Syed, Mohd A; Christianus, Annie; Willett, Kristine L; Mazzeo, Jeffrey R; Courtenay, Simon C

    2012-07-15

    In this study we sought to optimize recovery of fluorescent aromatic compounds (FACs) from the bile of African catfish (Clarias gariepinus) injected with 10mg/kg benzo[a]pyrene (BaP). Fractions of pooled bile were hydrolyzed, combined with ten volumes of methanol, ethanol, acetonitrile, or acetone, centrifuged and supernatants were analyzed by high-performance liquid chromatography with fluorescent detection (HPLC/FL). As well, to test whether FACs were being lost in solids from the centrifugation, pellets were resuspended, hydrolyzed and mixed with six volumes of the organic solvent that produced best FAC recovery from the supernatant, and subjected to HPLC/FL. Highest FAC concentrations were obtained with 2000μl and 1250μl acetone for supernatants and resuspended pellets respectively. FACs concentrations were negatively correlated with biliary protein content but were unaffected by addition of bovine serum albumin (BSA) followed by no incubation indicating that the presence of proteins in the biliary mixture does not simply interfere with detection of FACs. In another experiment, efficiency of acetone addition was compared to two different liquid-liquid extractions (L-LEs). Acetone additions provided significantly higher biliary FACs than the L-LE methods. The new two-stage bile preparation with acetone is an efficient, inexpensive and easily performed method.

  19. Two-Stage Fungal Pre-Treatment for Improved Biogas Production from Sisal Leaf Decortication Residues

    PubMed Central

    Muthangya, Mutemi; Mshandete, Anthony Manoni; Kivaisi, Amelia Kajumulo

    2009-01-01

    Sisal leaf decortications residue (SLDR) is amongst the most abundant agro-industrial residues in Tanzania and is a good feedstock for biogas production. Pre-treatment of the residue prior to its anaerobic digestion (AD) was investigated using a two-stage pre-treatment approach with two fungal strains, CCHT-1 and Trichoderma reesei in succession in anaerobic batch bioreactors. AD of the pre-treated residue with CCTH-1 at 10% (wet weight inoculum/SLDR) inoculum concentration incubated for four days followed by incubation for eight days with 25% (wet weight inoculum/SLDR) of T. reesei gave a methane yield of 0.292 ± 0.04 m3 CH4/kg volatile solids (VS)added. On reversing the pre-treatment succession of the fungal inocula using the same parameters followed by AD, methane yield decreased by about 55%. Generally, an increment in the range of 30–101% in methane yield in comparison to the un-treated SLDR was obtained. The results confirmed the potential of CCHT-1 followed by Trichoderma reesei fungi pre-treatment prior to AD to achieve significant improvement in biogas production from SLDR. PMID:20087466

  20. Performance assessment of two-stage anaerobic digestion of kitchen wastes.

    PubMed

    Bo, Zhang; Pin-Jing, He

    2014-01-01

    This study is aimed at investigating the performance of the two-phase anaerobic digestion of kitchen wastes in a lab-scale setup. The semi-continuous experiment showed that the two-phase anaerobic digestion of kitchen wastes had a bioconversion rate of 83%, biogas yield of 338 mL x (g chemical oxygen demand (COD))(-1) and total solid conversion of 63% when the entire two-phase anaerobic digestion process was subjected to an organic loading rate (OLR) of 10.7 g x (L d)(-1). In the hydrolysis-acidogenesis process, the efficiency of solubilization decreased from 72.6% to 41.1%, and the acidogenesis efficiency decreased from 31.8% to 17.8% with an increase in the COD loading rate. On the other hand, the performance of the subsequent methanogenic process was not susceptible to the increase in the feeding COD loading rate in the hydrolysis-acidogenesis stage. Lactic acid was one of the main fermentation products, accounting for over 40% of the total soluble COD in the fermentation liquid. The batch experiments indicated that the lactic acid was the earliest predominant fermentation product, and distributions of fermentation products were pH dependent. Results showed that increasing the feeding OLR of kitchen wastes made the two-stage anaerobic digestion process more effective. Moreover, there was a potential improvement in the performance of anaerobic digestion of kitchen wastes with a corresponding improvement in the hydrolysis process.

  1. Innovative two-stage mesophilic/thermophilic anaerobic degradation of sonicated sludge: performances and energy balance.

    PubMed

    Gianico, A; Braguglia, C M; Gallipoli, A; Mininni, G

    2015-05-01

    This study investigates for the first time, on laboratory scale, the possible application of an innovative enhanced stabilization process based on sequential mesophilic/thermophilic anaerobic digestion of waste-activated sludge, with low-energy sonication pretreatment. The first mesophilic digestion step was conducted at short hydraulic retention time (3-5 days), in order to favor volatile fatty acid production, followed by a longer thermophilic step of 10 days to enhance the bioconversion kinetics, assuring a complete pathogen removal. The high volatile solid removals, up to 55%, noticeably higher compared to the performances of a single-stage process carried out in same conditions, can guarantee the stability of the final digestate for land application. The ultrasonic pretreatment influenced significantly the fatty acid formation and composition during the first mesophilic step, improving consequently the thermophilic conversion of these compounds into methane. Methane yield from sonicated sludge digestion reached values up to 0.2 Nm(3)/kgVSfed. Positive energy balances highlighted the possible exploitation of this innovative two-stage digestion in place of conventional single-stage processes.

  2. A comprehensive microbial insight into two-stage anaerobic digestion of food waste-recycling wastewater.

    PubMed

    Shin, Seung Gu; Han, Gyuseong; Lim, Juntaek; Lee, Changsoo; Hwang, Seokhwan

    2010-09-01

    Microbial community structures were assessed in a two-stage anaerobic digestion system treating food waste-recycling wastewater. The reactors were operated for 390 d at 10 different hydraulic retention times (HRTs) ranging from 25 to 4 d. Stable operation was achieved with the overall chemical oxygen demand (COD) removal efficiency of 73.0-85.9% at organic loading rate of up to 35.6 g COD/L·d. Performance of the acidogenic reactors, however, changed significantly during operation. This change coincided with transition of the bacterial community from one dominated by Aeriscardovia- and Lactobacillus amylovorus-related species to one dominated by Lactobacillus acetotolerans- and Lactobacillus kefiri-like organisms. In methanogenic reactors, the microbial community structures also changed at this stage along with the shift from Methanoculleus- to Methanosarcina-like organisms. This trend was confirmed by the non-metric multidimensional scaling joint plot of microbial shifts along with performance parameters. These results indicated that the overall process performance was relatively stable compared to the dynamic changes in the microbial structures and the acidogenic performance.

  3. CHRONICLE: A Two-Stage Density-Based Clustering Algorithm for Dynamic Networks

    NASA Astrophysics Data System (ADS)

    Kim, Min-Soo; Han, Jiawei

    Information networks, such as social networks and that extracted from bibliographic data, are changing dynamically over time. It is crucial to discover time-evolving communities in dynamic networks. In this paper, we study the problem of finding time-evolving communities such that each community freely forms, evolves, and dissolves for any time period. Although the previous t-partite graph based methods are quite effective for discovering such communities from large-scale dynamic networks, they have some weak points such as finding only stable clusters of single path type and not being scalable w.r.t. the time period. We propose CHRONICLE, an efficient clustering algorithm that discovers not only clusters of single path type but also clusters of path group type. In order to find clusters of both types and also control the dynamicity of clusters, CHRONICLE performs the two-stage density-based clustering, which performs the 2nd-stage density-based clustering for the t-partite graph constructed from the 1st-stage density-based clustering result for each timestamp network. For a given data set, CHRONICLE finds all clusters in a fixed time by using a fixed amount of memory, regardless of the number of clusters and the length of clusters. Experimental results using real data sets show that CHRONICLE finds a wider range of clusters in a shorter time with a much smaller amount of memory than the previous method.

  4. Two-Stage Categorization in Brand Extension Evaluation: Electrophysiological Time Course Evidence

    PubMed Central

    Wang, Xiaoyi

    2014-01-01

    A brand name can be considered a mental category. Similarity-based categorization theory has been used to explain how consumers judge a new product as a member of a known brand, a process called brand extension evaluation. This study was an event-related potential study conducted in two experiments. The study found a two-stage categorization process reflected by the P2 and N400 components in brand extension evaluation. In experiment 1, a prime–probe paradigm was presented in a pair consisting of a brand name and a product name in three conditions, i.e., in-category extension, similar-category extension, and out-of-category extension. Although the task was unrelated to brand extension evaluation, P2 distinguished out-of-category extensions from similar-category and in-category ones, and N400 distinguished similar-category extensions from in-category ones. In experiment 2, a prime–probe paradigm with a related task was used, in which product names included subcategory and major-category product names. The N400 elicited by subcategory products was more significantly negative than that elicited by major-category products, with no salient difference in P2. We speculated that P2 could reflect the early low-level and similarity-based processing in the first stage, whereas N400 could reflect the late analytic and category-based processing in the second stage. PMID:25438152

  5. Isoglucose production from raw starchy materials based on a two-stage enzymatic system.

    PubMed

    Gromada, Anna; Fiedurek, Jan; Szczodrak, Janusz

    2008-01-01

    A new low-cost glucoamylase preparation for liquefaction and saccharification of starchy raw materials in a one-stage system was developed and characterized. A non-purified biocatalyst with a glucoamylase activity of 3.11 U/mg, an alpha-amylase activity of 0.12 WU/mg and a protein content of 0.04 mg protein/mg was obtained from a shaken-flask culture of the strain Aspergillus niger C-IV-4. Factors influencing the enzymatic hydrolysis of starchy materials such as reaction time, temperature and enzyme and substrate concentration were standardized to maximize the yield of glucose syrup. Thus, a 90% conversion of 5% starch, a 67.5% conversion of 5% potato flour and a 55% conversion of 5% wheat flour to sweet syrups containing up to 87% glucose was reached in 3 h using 1.24 glucoamylase U/mg hydrolyzed substrate. The application of such glucoamylase preparation and a commercially immobilized glucose isomerase for the production of glucose-fructose syrup in a two-stage system resulted in high production of stable glucose/fructose blends with a fructose content of 50%. A high concentration of fructose in obtained sweet syrups was achieved when isomerization was performed both in a batch and repeated batch process.

  6. Thrust augmentation options for the Beta 2 two-stage-to-orbit vehicle

    NASA Technical Reports Server (NTRS)

    Snyder, Christopher A.

    1993-01-01

    NASA LeRC is continuing to study propulsion concepts for a horizontal takeoff and landing, fully reusable, two-stage-to-orbit vehicle. This will be capable of launching and returning a 10,000 pound payload to a 100 nautical mile polar orbit using low-risk technology. The vehicle, Beta 2, is a derivative of the USAF/Boeing Beta vehicle which was designed to deliver a 50,000 pound payload to a similar orbit. Beta 2 stages at Mach 6.5 and about 100,000 ft altitude. The propulsion system for the booster is an over/under turbine bypass engine/ramjet configuration. In this paper, several options for thrust augmentation were studied in order to improve the performance of this engine where there was a critical need. Options studies were turbine engine overspeed in the transonic region, water injection at a various turbine engine locations also during the transonic region, and water injection at the turbine engine face during high speed operation. The methodology, constraints, propulsion performance, and mission study results are presented.

  7. Performance of an innovative two-stage process converting food waste to hydrogen and methane.

    PubMed

    Han, Sun-Kee; Shin, Hang-Sik

    2004-02-01

    This study was conducted to evaluate the performance of an innovative two-stage process, BIOCELL, that was developed to produce hydrogen (H2) and methane (CH4) from food waste on the basis of phase separation, reactor rotation mode, and sequential batch technique. The BIOCELL process consisted of four leaching-bed reactors for H2 recovery and post-treatment and a UASB reactor for CH4 recovery. The leaching-bed reactors were operated in a rotation mode with a 2-day interval between degradation stages. The sequential batch technique was useful to optimize environmental conditions during H2 fermentation. The BIOCELL process demonstrated that, at the high volatile solids (VS) loading rate of 11.9 kg/m3 x day, it could remove 72.5% of VS and convert VS(removed) to H2 (28.2%) and CH4 (69.9%) on a chemical oxygen demand (COD) basis in 8 days. H2 gas production rate was 3.63 m3/m3 x day, while CH4 gas production rate was 1.75 m3/m3 x day. The yield values of H2 and CH4 were 0.31 and 0.21 m3/kg VS(added), respectively. Moreover, the output from the post-treatment could be used as a soil amendment. The BIOCELL process proved to be stable, reliable, and effective in resource recovery as well as waste stabilization.

  8. Design of a High-Energy, Two-Stage Pulsed Plasma Thruster

    NASA Technical Reports Server (NTRS)

    Markusic, T. E.; Thio, Y. C. F.; Cassibry, J. T.; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    Design details of a proposed high-energy (approx. 50 kJ/pulse), two-stage pulsed plasma thruster are presented. The long-term goal of this project is to develop a high-power (approx. 500 kW), high specific impulse (approx. 7500 s), highly efficient (approx. 50%),and mechanically simple thruster for use as primary propulsion in a high-power nuclear electric propulsion system. The proposed thruster (PRC-PPT1) utilizes a valveless, liquid lithium-fed thermal plasma injector (first stage) followed by a high-energy pulsed electromagnetic accelerator (second stage). A numerical circuit model coupled with one-dimensional current sheet dynamics, as well as a numerical MHD simulation, are used to qualitatively predict the thermal plasma injection and current sheet dynamics, as well as to estimate the projected performance of the thruster. A set of further modelling efforts, and the experimental testing of a prototype thruster, is suggested to determine the feasibility of demonstrating a full scale high-power thruster.

  9. A two-stage magnetic refrigerator for astronomical applications with reservoir temperatures above 4 K

    NASA Technical Reports Server (NTRS)

    Hagmann, C.; Richards, P. L.

    1993-01-01

    We propose a novel adiabatic demagnetization refrigerator (ADR) to produce temperatures as low as 100 mK starting from a high temperature reservoir between 4 and 8 K. The high temperature reservoir for the ADR can be provided by a mechanical cooler or an unpumped liquid helium bath. This refrigerator can be used to cool bolometric infrared detectors for low background astronomy from mountain tops, balloons or satellites as well as to cool cryogenic x-ray detectors. The two-stage ADR consists of a single magnet with a paramagnetic chromic-cesium-alum (CCA) salt pill to produce the low temperature and paramagnetic gadolinium-gallium-garnet (GGG) as the first stage to intercept heat from the high temperature reservoir. Thermal contact between the paramagnets and the reservoir during magnetization is made with a mechanical heat switch. The ADR is suspended with Kevlar chords under tension for high mechanical stiffness and low parasitic heat leak. In a single cycle, the ADR maintains a temperature of 100 mK for 10 to 100 hours. This time depends strongly on the magnetic field and reservoir temperature but not on the volume of the paramagnetic material as long as the heat leak is dominated by the suspension.

  10. The modelling of trichloroethene photodegradation in Brij 35 surfactant by two-stage reaction.

    PubMed

    Choy, W K; Chu, W

    2001-07-01

    Various clean-up technologies have been developed for the removal and/or destruction of trichloroethene (TCE) in the subsurface. Surfactant-aided soil washing followed by photodegradation could be a promising approach to such a task. The modelling of TCE photodegradation by UV in Brij 35 surfactant micelles is therefore investigated. Two stages of TCE degradation are observed in surfactant Brij 35 systems. A lag phase is observed at the commencement of the degradation, but the duration of the lag phase is significantly reduced as the initial pH increases. As the overall decay of TCE is also found to be faster at higher pH levels, it is suggested that the free radical reaction is dominant at high pH levels, and the formation of lag phases is mainly due to the deficiency of free radicals at lower pH levels. Since the period of the lag phase gradually decreases with the increase of initial pH level, and the two pseudo first-order reaction constants (one for the lag phase and one for the subsequent fast decay) for TCE decay in both stages are also pH dependent, a non-steady-state mathematical model is developed for the prediction of TCE photodegradation in Brij 35 solutions, in which the remaining fraction of TCE (C/C0) in the system can be determined at any instant by using a simple parameter of the initial system pH.

  11. Two-stage transcriptional reprogramming in Saccharomyces cerevisiae for optimizing ethanol production from xylose.

    PubMed

    Cao, Limin; Tang, Xingliang; Zhang, Xinyuan; Zhang, Jingtao; Tian, Xuelei; Wang, Jingyu; Xiong, Mingyong; Xiao, Wei

    2014-07-01

    Conversion of lignocellulosic material to ethanol is a major challenge in second generation bio-fuel production by yeast Saccharomyces cerevisiae. This report describes a novel strategy named "two-stage transcriptional reprogramming (TSTR)" in which key gene expression at both glucose and xylose fermentation phases is optimized in engineered S. cerevisiae. Through a combined genome-wide screening of stage-specific promoters and the balancing of the metabolic flux, ethanol yields and productivity from mixed sugars were significantly improved. In a medium containing 50g/L glucose and 50g/L xylose, the top-performing strain WXY12 rapidly consumed glucose within 12h and within 84h it consistently achieved an ethanol yield of 0.48g/g total sugar, which was 94% of the theoretical yield. WXY12 utilizes a KGD1 inducible promoter to drive xylose metabolism, resulting in much higher ethanol yield than a reference strain using a strong constitutive PGK1 promoter. These promising results validate the TSTR strategy by synthetically regulating the xylose assimilation pathway towards efficient xylose fermentation.

  12. Classification of brain disease in magnetic resonance images using two-stage local feature fusion

    PubMed Central

    Li, Tao; Li, Wu; Yang, Yehui

    2017-01-01

    Background Many classification methods have been proposed based on magnetic resonance images. Most methods rely on measures such as volume, the cerebral cortical thickness and grey matter density. These measures are susceptible to the performance of registration and limited in representation of anatomical structure. This paper proposes a two-stage local feature fusion method, in which deformable registration is not desired and anatomical information is represented from moderate scale. Methods Keypoints are firstly extracted from scale-space to represent anatomical structure. Then, two kinds of local features are calculated around the keypoints, one for correspondence and the other for representation. Scores are assigned for keypoints to quantify their effect in classification. The sum of scores for all effective keypoints is used to determine which group the test subject belongs to. Results We apply this method to magnetic resonance images of Alzheimer's disease and Parkinson's disease. The advantage of local feature in correspondence and representation contributes to the final classification. With the help of local feature (Scale Invariant Feature Transform, SIFT) in correspondence, the performance becomes better. Local feature (Histogram of Oriented Gradient, HOG) extracted from 16×16 cell block obtains better results compared with 4×4 and 8×8 cell block. Discussion This paper presents a method which combines the effect of SIFT descriptor in correspondence and the representation ability of HOG descriptor in anatomical structure. This method has the potential in distinguishing patients with brain disease from controls. PMID:28207873

  13. Two stages of directed forgetting: Electrophysiological evidence from a short-term memory task.

    PubMed

    Gao, Heming; Cao, Bihua; Qi, Mingming; Wang, Jing; Zhang, Qi; Li, Fuhong

    2016-06-01

    In this study, a short-term memory test was used to investigate the temporal course and neural mechanism of directed forgetting under different memory loads. Within each trial, two memory items with high or low load were presented sequentially, followed by a cue indicating whether the presented items should be remembered. After an interval, subjects were asked to respond to the probe stimuli. The ERPs locked to the cues showed that (a) the effect of cue type was initially observed during the P2 (160-240 ms) time window, with more positive ERPs for remembering relative to forgetting cues; (b) load effects were observed during the N2-P3 (250-500 ms) time window, with more positive ERPs for the high-load than low-load condition; (c) the cue effect was also observed during the N2-P3 time window, with more negative ERPs for forgetting versus remembering cues. These results demonstrated that directed forgetting involves two stages: task-relevance identification and information discarding. The cue effects during the N2 epoch supported the view that directed forgetting is an active process.

  14. Terminal differentiation-resistant epidermal cells in mice undergoing two-stage carcinogenesis.

    PubMed

    Miller, D R; Viaje, A; Aldaz, C M; Conti, C J; Slaga, T J

    1987-04-01

    We have used an in vivo-in vitro approach to investigate the cellular aspects of two-stage skin carcinogenesis. Female SENCAR mice initiated with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) were promoted twice weekly with 12-O-tetradecanoylphorbol-13-acetate (TPA). Epidermal cultures from untreated or TPA-treated mice had few focus-forming cells resistant to calcium-induced terminal differentiation. Cultures from mice treated with MNNG alone formed numerous foci. Brief promotion (four TPA treatments) of MNNG-treated mice produced fewer but statistically larger foci, suggesting that TPA was selecting against more slowly growing cells. MNNG plus TPA-treated mice with very early papillomas produced more and larger foci than those due to MNNG treatment alone, suggesting that the papillomas may have comprised calcium-resistant cells. These cells may indeed be initiated cells since a permanent cell line arising after MNNG plus brief TPA treatment eventually formed histological papillomas in vivo. If calcium-resistant cells are initiated, then there were many more initiated cells in the skin (with or without TPA treatment) than papillomas expected, implying that either some initiated cells never formed papillomas, or that a significant accumulation of initiated cells had already occurred in the skin within 2 weeks of MNNG treatment. Subsequent TPA promotion of these cells apparently produced a toxic response that passively selected for more rapidly growing initiated cells, which eventually accumulated into papillomas.

  15. Two stages in lymphocyte mediator production by differential susceptibility to blockade using niridazole.

    PubMed Central

    Daniels, J C; Fajardo, I; David, J R

    1975-01-01

    Sera from guinea pigs given niridazole, an anti-schistosomal compound, have been shown to reversibly block the production of antigen-induced migration inhibitory factor by sensitized guinea pig lymph node cells. Since niridazole itself has no effect in vitro, the blockade of production of migration inhibitory factor is probably due to drug metabolites in the serum. We report here further studies on the mechanism of this drug-induced suppression of cellular hypersensitivity; the data show that niridazole active serum does not block the production of migration inhibitory factor once it has been initiated. Indeed, if niridazole active serum is added a little as 60 sec after the addition of antigen, the lymphocytes will produce migration inhibitory factor. These results suggest the presence of at least two stages in production of migration inhibitory factor after the addition of antigen to lymphocytes. The first, lasting less than 60 sec, is susceptible to blockade by niridazole active serum; the second is not. The elucidation of the mechanism of this blockade should lead to further understanding of the early events after antigen triggering of sensitized lymphocytes. PMID:1105584

  16. Two-stage fungal pre-treatment for improved biogas production from sisal leaf decortication residues.

    PubMed

    Muthangya, Mutemi; Mshandete, Anthony Manoni; Kivaisi, Amelia Kajumulo

    2009-11-06

    Sisal leaf decortications residue (SLDR) is amongst the most abundant agro-industrial residues in Tanzania and is a good feedstock for biogas production. Pre-treatment of the residue prior to its anaerobic digestion (AD) was investigated using a two-stage pre-treatment approach with two fungal strains, CCHT-1 and Trichoderma reesei in succession in anaerobic batch bioreactors. AD of the pre-treated residue with CCTH-1 at 10% (wet weight inoculum/SLDR) inoculum concentration incubated for four days followed by incubation for eight days with 25% (wet weight inoculum/SLDR) of T. reesei gave a methane yield of 0.292 +/- 0.04 m(3) CH(4)/kg volatile solids (VS)(added). On reversing the pre-treatment succession of the fungal inocula using the same parameters followed by AD, methane yield decreased by about 55%. Generally, an increment in the range of 30-101% in methane yield in comparison to the un-treated SLDR was obtained. The results confirmed the potential of CCHT-1 followed by Trichoderma reesei fungi pre-treatment prior to AD to achieve significant improvement in biogas production from SLDR.

  17. Experimental development of a two-stage fluidized-bed/cyclonic agglomerating incinerator

    SciTech Connect

    Mensinger, M.C.; Rehmat, A.; Bryan, B.G.; Lau, F.S. ); Shearer, T.L. ); Duggan, P.A. )

    1991-01-01

    The Institute of Gas Technology (IGT) is conducting an experimental program to develop and test through pilot-plant scale of operation, IGT's two-stage fluidized-bed/cyclonic agglomerating incinerator (TSI). The TSI is based on combining the fluidized-bed agglomeration/gasification technology and the cyclonic combustion/incineration technology, which have been developed at IGT over many years. The TSI is a unique and extremely flexible combustor that can operate over a wide range of conditions in the fluidized-bed first stage from low temperature (desorption) to high temperature (agglomeration) including gasification of high-Btu wastes. The TSI can easily and efficiently destroy solid, liquid and gaseous organic wastes, while containing solid inorganic contaminants within an essentially non-leachable glassy matrix, suitable for disposal in an ordinary landfill. This paper presents the results of tests conducted in a batch, fluidized-bed bench-scale unit (BSU) with commercially available clean'' top soil and the same soil spiked with lead and chromium compounds. The objectives of these tests were to determine the operating conditions necessary to achieve soil agglomeration and to evaluate the leaching characteristics of the soil agglomerates formed. 7 refs., 7 figs., 6 tabs.

  18. Two-stage sequential sampling: A neighborhood-free adaptive sampling procedure

    USGS Publications Warehouse

    Salehi, M.; Smith, D.R.

    2005-01-01

    Designing an efficient sampling scheme for a rare and clustered population is a challenging area of research. Adaptive cluster sampling, which has been shown to be viable for such a population, is based on sampling a neighborhood of units around a unit that meets a specified condition. However, the edge units produced by sampling neighborhoods have proven to limit the efficiency and applicability of adaptive cluster sampling. We propose a sampling design that is adaptive in the sense that the final sample depends on observed values, but it avoids the use of neighborhoods and the sampling of edge units. Unbiased estimators of population total and its variance are derived using Murthy's estimator. The modified two-stage sampling design is easy to implement and can be applied to a wider range of populations than adaptive cluster sampling. We evaluate the proposed sampling design by simulating sampling of two real biological populations and an artificial population for which the variable of interest took the value either 0 or 1 (e.g., indicating presence and absence of a rare event). We show that the proposed sampling design is more efficient than conventional sampling in nearly all cases. The approach used to derive estimators (Murthy's estimator) opens the door for unbiased estimators to be found for similar sequential sampling designs. ?? 2005 American Statistical Association and the International Biometric Society.

  19. A two-stage morphological classifier of foci occurring in cell transformation assays

    NASA Astrophysics Data System (ADS)

    Crosta, Giovanni F.; Urani, Chiara; Bussinelli, Luca

    2009-02-01

    Cell Transformation Assays (CTA) rely on the detection of phenotypic changes, namely foci, induced by chemicals (e.g., xenobiotics or candidate drugs) in mammalian cells such as C3H10T1/2 mouse fibroblasts. A focus is a cell colony and as such is made visible by standardized techniques of light microscopy. Foci exhibit a variety of morphological features, by which three "Types" have been defined. Types II and III consist of cells having undergone neoplastic transformation. The assignment of a focus to a Type is based on the evaluation of phenotypic features by a trained human expert. An automated, two-stage morphological classifier of foci is described herewith. Morphological descriptors are extracted from light microscope images by the "spectrum enhancement" algorithm, which separates structure from texture. Said descriptors are submitted to a classifier, the first stage of which is trained to discriminate transformed cells from normal ones and the 2nd stage to discriminate Type III from Type II. The classifier operating in recognition mode (on images not used for training) is satisfactory in terms of confusion matrix entries. The whole procedure is aimed at removing subjectivity from the scoring and classification of foci and thus make CTA a more powerful tool in carcinogenesis studies.

  20. Syngas production by two-stage method of biomass catalytic pyrolysis and gasification.

    PubMed

    Xie, Qinglong; Kong, Sifang; Liu, Yangsheng; Zeng, Hui

    2012-04-01

    A two-stage technology integrated with biomass catalytic pyrolysis and gasification processes was utilized to produce syngas (H(2)+CO). In the presence of different nickel based catalysts, effects of pyrolysis temperature and gasification temperature on gas production were investigated. Experimental results showed that more syngas and char of high quality could be obtained at a temperature of 750°C in the stage of pyrolysis, and in the stage of gasification, pyrolysis char (produced at 750°C) reacted with steam and the maximum yield of syngas was obtained at 850°C. Syngas yield in this study was greatly increased compared with previous studies, up to 3.29Nm(3)/kg biomass. The pyrolysis process could be well explained by Arrhenius kinetic first-order rate equation. XRD analyses suggested that formation of Mg(0.4)Ni(0.6)O and increase of Ni(0) crystallite size were two main reasons for the deactivation of nickel based catalysts at higher temperature.

  1. Simulation and Analyses of Stage Separation of Two-Stage Reusable Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Pamadi, Bandu N.; Neirynck, Thomas A.; Hotchko, Nathaniel J.; Tartabini, Paul V.; Scallion, William I.; Murphy, K. J.; Covell, Peter F.

    2007-01-01

    NASA has initiated the development of methodologies, techniques and tools needed for analysis and simulation of stage separation of next generation reusable launch vehicles. As a part of this activity, ConSep simulation tool is being developed which is a MATLAB-based front-and-back-end to the commercially available ADAMS(Registerd TradeMark) solver, an industry standard package for solving multi-body dynamic problems. This paper discusses the application of ConSep to the simulation and analysis of staging maneuvers of two-stage-to-orbit (TSTO) Bimese reusable launch vehicles, one staging at Mach 3 and the other at Mach 6. The proximity and isolated aerodynamic database were assembled using the data from wind tunnel tests conducted at NASA Langley Research Center. The effects of parametric variations in mass, inertia, flight path angle, altitude from their nominal values at staging were evaluated. Monte Carlo runs were performed for Mach 3 staging to evaluate the sensitivity to uncertainties in aerodynamic coefficients.

  2. Simulation and Analyses of Stage Separation Two-Stage Reusable Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Pamadi, Bandu N.; Neirynck, Thomas A.; Hotchko, Nathaniel J.; Tartabini, Paul V.; Scallion, William I.; Murphy, Kelly J.; Covell, Peter F.

    2005-01-01

    NASA has initiated the development of methodologies, techniques and tools needed for analysis and simulation of stage separation of next generation reusable launch vehicles. As a part of this activity, ConSep simulation tool is being developed which is a MATLAB-based front-and-back-end to the commercially available ADAMS(registered Trademark) solver, an industry standard package for solving multi-body dynamic problems. This paper discusses the application of ConSep to the simulation and analysis of staging maneuvers of two-stage-to-orbit (TSTO) Bimese reusable launch vehicles, one staging at Mach 3 and the other at Mach 6. The proximity and isolated aerodynamic database were assembled using the data from wind tunnel tests conducted at NASA Langley Research Center. The effects of parametric variations in mass, inertia, flight path angle, altitude from their nominal values at staging were evaluated. Monte Carlo runs were performed for Mach 3 staging to evaluate the sensitivity to uncertainties in aerodynamic coefficients.

  3. Characterization of a Two-Stage Pulse Tube Cooler for Space Applications

    NASA Astrophysics Data System (ADS)

    Orsini, R.; Nguyen, T.; Colbert, R.; Raab, J.

    2010-04-01

    A two-stage long-life, low mass and efficient pulse tube cooler for space applications has been developed and acceptance tested for flight applications. This paper presents the data collected on four flight coolers during acceptance testing. Flight acceptance test of these cryocoolers includes thermal performance mapping over a range of reject temperatures, launch vibration testing and thermal cycling testing. Designed conservatively for a 10-year life, the coolers are required to provide simultaneous cooling powers at 95 K and 180 K while rejecting to 300 K with less than 187 W input power to the electronics. The total mass of each cooler and electronics system is 8.7 kg. The radiation-hardened and software driven control electronics provides cooler control functions which are fully re-configurable in orbit. These functions include precision temperature control to better than 100 mK p-p. This 2 stage cooler has heritage to the 12 Northrop Grumman Aerospace Systems (NGAS) coolers currently on orbit with 2 operating for more than 11.5 years.

  4. A two-stage magnetic refrigerator for astronomical applications with reservoir temperatures above 4 K

    NASA Astrophysics Data System (ADS)

    Hagmann, C.; Richards, P. L.

    1993-02-01

    We propose a novel adiabatic demagnetization refrigerator (ADR) to produce temperatures as low as 100 mK starting from a high temperature reservoir between 4 and 8 K. The high temperature reservoir for the ADR can be provided by a mechanical cooler or an unpumped liquid helium bath. This refrigerator can be used to cool bolometric infrared detectors for low background astronomy from mountain tops, balloons or satellites as well as to cool cryogenic x-ray detectors. The two-stage ADR consists of a single magnet with a paramagnetic chromic-cesium-alum (CCA) salt pill to produce the low temperature and paramagnetic gadolinium-gallium-garnet (GGG) as the first stage to intercept heat from the high temperature reservoir. Thermal contact between the paramagnets and the reservoir during magnetization is made with a mechanical heat switch. The ADR is suspended with Kevlar chords under tension for high mechanical stiffness and low parasitic heat leak. In a single cycle, the ADR maintains a temperature of 100 mK for 10 to 100 hours. This time depends strongly on the magnetic field and reservoir temperature but not on the volume of the paramagnetic material as long as the heat leak is dominated by the suspension.

  5. Human Cough as a Two-Stage Jet and Its Role in Particle Transport

    PubMed Central

    Li, Yuguo

    2017-01-01

    The human cough is a significant vector in the transmission of respiratory diseases in indoor environments. The cough flow is characterized as a two-stage jet; specifically, the starting jet (when the cough starts and flow is released) and interrupted jet (after the source supply is terminated). During the starting-jet stage, the flow rate is a function of time; three temporal profiles of the exit velocity (pulsation, sinusoidal and real-cough) were investigated in this study, and our results showed that the cough flow’s maximum penetration distance was in the range of a 50.6–85.5 opening diameter (D) under our experimental conditions. The real-cough and sinusoidal cases exhibited greater penetration ability than the pulsation cases under the same characteristic Reynolds number (Rec) and normalized cough expired volume (Q/AD, with Q as the cough expired volume and A as the opening area). However, the effects of Rec and Q/AD on the maximum penetration distances proved to be more significant; larger values of Rec and Q/AD reflected cough flows with greater penetration distances. A protocol was developed to scale the particle experiments between the prototype in air, and the model in water. The water tank experiments revealed that although medium and large particles deposit readily, their maximum spread distance is similar to that of small particles. Moreover, the leading vortex plays an important role in enhancing particle transport. PMID:28046084

  6. An adaptive two-stage energy-efficiency mechanism for the doze mode in EPON

    NASA Astrophysics Data System (ADS)

    Nikoukar, AliAkbar; Hwang, I.-Shyan; Su, Yu-Min; Liem, Andrew Tanny

    2016-07-01

    Sleep and doze power-saving modes are the common ways to reduce power consumption of optical network units (ONUs) in Ethernet passive optical network (EPON). The doze mode turns off the ONU transmitter when there is no traffic in the upstream direction while the sleep mode turns off the ONU transmitter and receiver. As the result, the sleep mode is more efficient compared to the doze mode, but it introduces additional complexity of scheduling and signaling, losses the clock synchronization and requires long clock recovery time; furthermore, it requires the cooperation of the optical line terminal (OLT) in the downstream direction to queue frames. To improve the energy-saving in the doze mode, a new two-stage mechanism is introduced that the doze sleep duration is extended for longer time with acceptable quality-of-services (QoS) metrics when ONU is idle in the current cycle. By this way the ONU enters the doze mode even in the high load traffic; moreover, the green dynamic bandwidth allocation (GBA) is proposed to calculate the doze sleep duration based on the ONU queue state and incoming traffic ratio. Simulation results show that the proposed mechanism significantly improves the energy-saving 74% and 54% when traffic load is from the light load to the high load in different traffic situations, and also promises the QoS performance.

  7. A Two-Stage Procedure Toward the Efficient Implementation of PANS and Other Hybrid Turbulence Models

    NASA Technical Reports Server (NTRS)

    Abdol-Hamid, Khaled S.; Girimaji, Sharath S.

    2004-01-01

    The main objective of this article is to introduce and to show the implementation of a novel two-stage procedure to efficiently estimate the level of scale resolution possible for a given flow on a given grid for Partial Averaged Navier-Stokes (PANS) and other hybrid models. It has been found that the prescribed scale resolution can play a major role in obtaining accurate flow solutions. The first step is to solve the unsteady or steady Reynolds Averaged Navier-Stokes (URANS/RANS) equations. From this preprocessing step, the turbulence length-scale field is obtained. This is then used to compute the characteristic length-scale ratio between the turbulence scale and the grid spacing. Based on this ratio, we can assess the finest scale resolution that a given grid for a given flow can support. Along with other additional criteria, we are able to analytically identify the appropriate hybrid solver resolution for different regions of the flow. This procedure removes the grid dependency issue that affects the results produced by different hybrid procedures in solving unsteady flows. The formulation, implementation methodology, and validation example are presented. We implemented this capability in a production Computational Fluid Dynamics (CFD) code, PAB3D, for the simulation of unsteady flows.

  8. A two-stage cascade model of BOLD responses in human visual cortex.

    PubMed

    Kay, Kendrick N; Winawer, Jonathan; Rokem, Ariel; Mezer, Aviv; Wandell, Brian A

    2013-01-01

    Visual neuroscientists have discovered fundamental properties of neural representation through careful analysis of responses to controlled stimuli. Typically, different properties are studied and modeled separately. To integrate our knowledge, it is necessary to build general models that begin with an input image and predict responses to a wide range of stimuli. In this study, we develop a model that accepts an arbitrary band-pass grayscale image as input and predicts blood oxygenation level dependent (BOLD) responses in early visual cortex as output. The model has a cascade architecture, consisting of two stages of linear and nonlinear operations. The first stage involves well-established computations-local oriented filters and divisive normalization-whereas the second stage involves novel computations-compressive spatial summation (a form of normalization) and a variance-like nonlinearity that generates selectivity for second-order contrast. The parameters of the model, which are estimated from BOLD data, vary systematically across visual field maps: compared to primary visual cortex, extrastriate maps generally have larger receptive field size, stronger levels of normalization, and increased selectivity for second-order contrast. Our results provide insight into how stimuli are encoded and transformed in successive stages of visual processing.

  9. Improved two-stage equalization for coherent Pol-Mux QPSK and 16-QAM systems.

    PubMed

    Zhu, Chen; Tran, An V; Chen, Simin; Du, Liang B; Anderson, Trevor; Lowery, Arthur J; Skafidas, Efstratios

    2012-12-10

    We report a two-stage blind frequency domain equalization method for long-haul coherent polarization-multiplexed (pol-mux) systems using quadrature phase shift keying (QPSK) and 16-quadrature amplitude modulation (16-QAM). In the first stage, blind CD parameter prediction is conducted prior to a CD equalizer. This supports flexible path switching in optical networks. In the second stage, a frequency-domain multi-modulus algorithm (MMA) equalizer is used to cope with the residual fiber impairments and perform polarization de-multiplexing. Compared with the conventional constant modulus algorithm (CMA), MMA shows advantages including better steady state performance and a faster convergence rate. Furthermore, all the estimation and equalization algorithms are implemented in the frequency domain which potentially provides the least complexity for the pol-mux optical coherent systems. The proposed algorithm is experimentally demonstrated with an 800-km 10 Gbaud coherent optical pol-mux system. For QPSK signal, the proposed method achieves error-free transmission and shows superior convergence speed against CMA, and for 16-QAM signals, the proposed MMA outperforms CMA with more than 1-dB improvement in Q-value.

  10. Ecotoxicity of materials from integrated two-stage liquefaction and Exxon Donor Solvent processes

    SciTech Connect

    Dauble, D.D.; Scott, A.J.; Lusty, E.W.; Thomas, B.L.; Hanf, R.W. Jr.

    1983-05-01

    Coal-derived materials from two coal conversion processes were screened for potential ecological toxicity. We examined the toxicity of materials from different engineering or process options to an aquatic invertebrate and also related potential hazard to relative concentration, composition, and stability of water soluble components. For materials tested from the Integrated Two-Stage Liquefaction (ITSL) process, only the LC finer (LCF) 650/sup 0/F distillate was highly soluble in water at 20/sup 0/C. The LCF feed and Total Liquid Product (TLP) were not in liquid state at 20/sup 0/C and were relatively insoluble in water. Relative hazard to daphnids from ITSL materials was as follows: LCF 650/sup 0/F distillate greater than or equal to LCF feed greater than or equal to TLP. For Exxon Donor Solvent (EDS) materials, process solvent produced in the bottoms recycle mode was more soluble in water than once-through process solvent and, hence, slightly more acutely toxic to daphnids. When compared to other coal liquids or petroleum products, the ITSL or EDS liquids were intermediate in toxicity; relative hazard ranged from 1/7 to 1/13 of the Solvent Refined Coal (SRC)-II distillable blend, but was several times greater than the relative hazard for No. 2 diesel fuel oil or Prudhoe Bay crude oil. Although compositonal differences in water-soluble fractions (WSF) were noted among materials, phenolics were the major compound class in all WSFs and probably the primary contributor to acute toxicity.

  11. Two-stage hierarchical group testing for multiple infections with application to the Infertility Prevention Project

    PubMed Central

    Tebbs, Joshua M.; McMahan, Christopher S.; Bilder, Christopher R.

    2015-01-01

    Summary Screening for sexually transmitted diseases has benefited greatly from the use of group testing (pooled testing) to lower costs. With the development of assays that detect multiple infections, screening practices now involve testing pools of individuals for multiple infections simultaneously. Building on the research for single infection group testing procedures, we examine the performance of group testing for multiple infections. Our work is motivated by chlamydia and gonorrhea testing for the Infertility Prevention Project (IPP), a national program in the United States. We consider a two-stage pooling algorithm currently used to perform testing for the IPP. We first derive the operating characteristics of this algorithm for classification purposes (e.g., expected number of tests, misclassification probabilities, etc.) and identify pool sizes that minimize the expected number of tests. We then develop an expectation-maximization algorithm to estimate probabilities of infection using both group and individual retest responses. Our research shows that group testing can offer large cost savings when classifying individuals for multiple infections and can provide prevalence estimates that are actually more efficient than those from individual testing. PMID:24117173

  12. Food Behavior Change in Late-Life Widowhood: A Two-Stage Process

    PubMed Central

    Vesnaver, Elisabeth; Keller, Heather H.; Sutherland, Olga; Maitland, Scott B.; Locher, Julie L.

    2015-01-01

    Widowhood is a common life event for married older women. Prior research has found disruptions in eating behaviors to be common among widows. Little is known about the process underlying these disruptions. The aim of this study was to generate a theoretical understanding of the changing food behaviors of older women during the transition of widowhood. Qualitative methods based on constructivist grounded theory guided by a critical realist worldview were used. Individual active interviews were conducted with 15 community-living women, aged 71 to 86 years, living alone, and widowed six months to 15 years at the time of the interview. Participants described a variety of educational backgrounds and levels of health, were mainly white and of Canadian or European descent, and reported sufficient income to meet their needs. The loss of regular shared meals initiated a two-stage process whereby women first fall into new patterns and then re-establish the personal food system, thus enabling women to redirect their food system from one that satisfied the couple to one that satisfied their personal food needs. Influences on the trajectory of the change process included the couple’s food system, experience with nutritional care, food-related values, and food-related resources. Implications for research and practice are discussed. PMID:26232138

  13. End-wall boundary layer measurements in a two-stage fan

    NASA Technical Reports Server (NTRS)

    Ball, C. L.; Reid, L.; Schmidt, J. F.

    1983-01-01

    Detailed flow measurements made in the casing boundary layer of a two-stage transonic fan are summarized. These measurements were taken at a station upstream of the fan, between all blade rows, and downstream of the last row. Conventional boundary layer parameters were calculated from the measured data. A classical two dimensional casing boundary layer was measured at the fan inlet and extended inward to approximately 15 percent of span. A highly three dimensional boundary layer was measured at the exit of each blade row and extended inward to approximately 10 percent of span. The steep radial gradient of axial velocity noted at the exit of the rotors was reduced substantially as the flow passed through the stators. This reduced gradient is attributed to flow mixing. The amount of flow mixing was reflected in the radial redistribution of total temperature as the flow passed through the stators. The blockage factors calculated from the measured data show an increase in blockage across the rotors and a decrease across the stators. For this fan the calculated blockages for the second stage were essentially the same as those for the first stage.

  14. Characterisation of the current switch mechanism in two-stage wire array Z-pinches

    NASA Astrophysics Data System (ADS)

    Burdiak, G. C.; Lebedev, S. V.; Harvey-Thompson, A. J.; Hall, G. N.; Swadling, G. F.; Suzuki-Vidal, F.; Khoory, E.; Bland, S. N.; Pickworth, L.; de Grouchy, P.; Skidmore, J.; Suttle, L.; Waisman, E. M.

    2015-11-01

    In this paper, we describe the operation of a two-stage wire array z-pinch driven by the 1.4 MA, 240 ns rise-time Magpie pulsed-power device at Imperial College London. In this setup, an inverse wire array acts as a fast current switch, delivering a current pre-pulse into a cylindrical load wire array, before rapidly switching the majority of the generator current into the load after a 100-150 ns dwell time. A detailed analysis of the evolution of the load array during the pre-pulse is presented. Measurements of the load resistivity and energy deposition suggest significant bulk heating of the array mass occurs. The ˜5 kA pre-pulse delivers ˜0.8 J of energy to the load, leaving it in a mixed, predominantly liquid-vapour state. The main current switch occurs as the inverse array begins to explode and plasma expands into the load region. Electrical and imaging diagnostics indicate that the main current switch may evolve in part as a plasma flow switch, driven by the expansion of a magnetic cavity and plasma bubble along the length of the load array. Analysis of implosion trajectories suggests that approximately 1 MA switches into the load in 100 ns, corresponding to a doubling of the generator dI/dt. Potential scaling of the device to higher current machines is discussed.

  15. Detrend-free hemodynamic data assimilation of two-stage Kalman estimator.

    PubMed

    Zhenghui, Hu; Pengcheng, Shi

    2011-01-01

    Spurious temporal drift is abundant in fMRI data, and its removal is a critical preprocessing step in fMRI data assimilation due to the sparse nature and the complexity of the data. Conventional data-driven approaches rest upon specific assumptions of the drift structure and signal statistics, and may lead to inaccurate results. In this paper we present an approach to the assimilation of nonlinear hemodynamic system, with special attention on drift. By treating the drift variation as a random-walk process, the assimilation problem was translated into the identification of a nonlinear system in the presence of time varying bias. We developed two-stage unscented Kalman filter (UKF) to efficiently handle this problem. In this framework the assimilation can implement with original fMRI data without detrending preprocessing. The fMRI responses and drift were estimated simultaneously in an assimilation cycle. The efficacy of this approach is demonstrated in synthetic and real fMRI experiments. Results show that the joint estimation strategy produces more accurate estimation of physiological states, fMRI response and drift than separate processing due to no assumption of structure of the drift that is not available in fMRI data.

  16. Effect of evening primrose and fish oils on two stage skin carcinogenesis in mice.

    PubMed

    Ramesh, G; Das, U N

    1998-09-01

    The effect of fish oil (FO, given in the form of MaxEPA) rich in n-3 fatty acids and evening primrose oil (EPO) rich in n-6 fatty acids on two-stage skin carcinogenesis in mice was studied. Both FO and EPO inhibited the papilloma formation to a significant degree only during the promotion stage which was associated with an increase in lipid peroxidation. Both FO and EPO inhibited the binding of benzo(a)-pyrene to skin cell DNA suggesting that this could be one of the mechanism(s) by which these oils could be preventing papilloma development. Neither EPO nor FO influenced epidermal cell proliferation. In the FO group, LA (linoleic acid), AA (arachidonic acid) and DHA (docosahexaenoic acid) were increased, whereas in the EPO group a significant increase in the AA content was noted. No specific changes in the fatty acid pattern were observed in any of the groups that could be attributed to the papilloma incidence. These results suggest that FO and EPO can influence papilloma formation which can be attributed, at least in part, to their ability to prevent benzo(a)pyrene binding to DNA and to an increase the lipid peroxidation process.

  17. Two-Stage Path Planning Approach for Designing Multiple Spacecraft Reconfiguration Maneuvers

    NASA Technical Reports Server (NTRS)

    Aoude, Georges S.; How, Jonathan P.; Garcia, Ian M.

    2007-01-01

    The paper presents a two-stage approach for designing optimal reconfiguration maneuvers for multiple spacecraft. These maneuvers involve well-coordinated and highly-coupled motions of the entire fleet of spacecraft while satisfying an arbitrary number of constraints. This problem is particularly difficult because of the nonlinearity of the attitude dynamics, the non-convexity of some of the constraints, and the coupling between the positions and attitudes of all spacecraft. As a result, the trajectory design must be solved as a single 6N DOF problem instead of N separate 6 DOF problems. The first stage of the solution approach quickly provides a feasible initial solution by solving a simplified version without differential constraints using a bi-directional Rapidly-exploring Random Tree (RRT) planner. A transition algorithm then augments this guess with feasible dynamics that are propagated from the beginning to the end of the trajectory. The resulting output is a feasible initial guess to the complete optimal control problem that is discretized in the second stage using a Gauss pseudospectral method (GPM) and solved using an off-the-shelf nonlinear solver. This paper also places emphasis on the importance of the initialization step in pseudospectral methods in order to decrease their computation times and enable the solution of a more complex class of problems. Several examples are presented and discussed.

  18. Efficient estimation in two-stage randomized clinical trials using ranked sets.

    PubMed

    Hossain, Syed Shahadat; Awan, Nabil

    2016-12-14

    Clinical trials designed for survival probability estimation of different treatment policies for chronic diseases like cancer, leukemia, and schizophrenia usually need randomization of treatments in two stages. Since complete remission is rare for these diseases, initially an induction therapy is given for patient's remission. Further treatment, which is often an expensive maintenance therapy, is administered only for the patients with remission. If the maintenance therapy is so expensive that the cost of the trial inflates, only a simple random sample of patients will be treated with the expensive maintenance due to budget constraint. In this article, we have implemented a design using ranked sets instead of simple randomization in the second stage and obtained an unbiased estimator of the overall survival distribution for a particular treatment combination. Through simulation studies under different conditions, we have found that the design we developed based on ranked sets gives an unbiased estimate of the population survival probability which is more efficient than the estimate obtained by the usual design.

  19. Retinal orientation and interactions in rhodopsin reveal a two-stage trigger mechanism for activation

    PubMed Central

    Kimata, Naoki; Pope, Andreyah; Eilers, Markus; Opefi, Chikwado A.; Ziliox, Martine; Hirshfeld, Amiram; Zaitseva, Ekaterina; Vogel, Reiner; Sheves, Mordechai; Reeves, Philip J.; Smith, Steven O.

    2016-01-01

    The 11-cis retinal chromophore is tightly packed within the interior of the visual receptor rhodopsin and isomerizes to the all-trans configuration following absorption of light. The mechanism by which this isomerization event drives the outward rotation of transmembrane helix H6, a hallmark of activated G protein-coupled receptors, is not well established. To address this question, we use solid-state NMR and FTIR spectroscopy to define the orientation and interactions of the retinal chromophore in the active metarhodopsin II intermediate. Here we show that isomerization of the 11-cis retinal chromophore generates strong steric interactions between its β-ionone ring and transmembrane helices H5 and H6, while deprotonation of its protonated Schiff's base triggers the rearrangement of the hydrogen-bonding network involving residues on H6 and within the second extracellular loop. We integrate these observations with previous structural and functional studies to propose a two-stage mechanism for rhodopsin activation. PMID:27585742

  20. Prediction of syngas quality for two-stage gasification of selected waste feedstocks.

    PubMed

    De Filippis, Paolo; Borgianni, Carlo; Paolucci, Martino; Pochetti, Fausto

    2004-01-01

    This paper compares the syngas produced from methane with the syngas obtained from the gasification, in a two-stage reactor, of various waste feedstocks. The syngas composition and the gasification conditions were simulated using a simple thermodynamic model. The waste feedstocks considered are: landfill gas, waste oil, municipal solid waste (MSW) typical of a low-income country, the same MSW blended with landfill gas, refuse derived fuel (RDF) made from the same MSW, the same RDF blended with waste oil and a MSW typical of a high-income country. Energy content, the sum of H2 and CO gas percentages, and the ratio of H2 to CO are considered as measures of syngas quality. The simulation shows that landfill gas gives the best results in terms of both H2+CO and H2/CO, and that the MSW of low-income countries can be expected to provide inferior syngas on all three quality measures. Co-gasification of the MSW from low-income countries with landfill gas, and the mixture of waste oil with RDF from low-income MSW are considered as options to improve gas quality.

  1. OBSERVATIONS OF A TWO-STAGE SOLAR ERUPTIVE EVENT (SEE): EVIDENCE FOR SECONDARY HEATING

    SciTech Connect

    Su Yang; Dennis, Brian R.; Holman, Gordon D.; Wang, Tongjiang; Chamberlin, Phillip C.; Savage, Sabrina; Veronig, Astrid

    2012-02-10

    We present RHESSI, SDO/AIA, SOHO/LASCO, STEREO, and GOES observations of a partially occulted solar eruptive event that occurred at the southwest limb on 2011 March 8. The GOES X-ray light curve shows two peaks separated by almost 2 hr that we interpret as two stages of a single event associated with the delayed eruption of a coronal mass ejection (CME). A hot flux rope formed during the first stage and continued expanding and rising throughout the event. The speed of the flux rope decreased from {approx}120 to 14 km s{sup -1} during the decay phase of the first stage and increased again during the second stage to become the CME with a speed of {approx}516 km s{sup -1}. RHESSI and GOES data analyses show that the plasma temperature reached over 20 MK in the first stage, then decreased to {approx}10 MK and increased to 15 MK in the second stage. This event provides clear evidence for a secondary heating phase. The enhanced EUV and X-ray emission came from the high corona ({approx}60 arcsec above the limb) in the second stage, {approx}40 arcsec higher than the site of the initial flare emission. STEREO-A on-disk observations indicate that the post-flare loops during this stage were of larger scale sizes and spatially distinct from those in the first stage.

  2. Observations of a Two-Stage Solar Eruptive Event (SEE): Evidence for Secondary Heating

    NASA Technical Reports Server (NTRS)

    Su, Yang; Dennis, Brian R.; Holman, Gordon D.; Wang, Tongjiang; Chamberlin, Phillip C.; Savage, Sabrina; Veronig, Astrid

    2012-01-01

    We present RHESSI, SDO/AIA, SOHO/LASCO, STEREO, and GOES observations of a partially occulted solar eruptive event (SEE) that occurred at the South-West limb on 8 March, 2011. The GOES X-ray light curve shows two peaks separated by almost two hours that we interpret as two stages of a single event associated with the delayed eruption of a CME. A hot flux rope formed during the first stage and continued expanding and rising throughout the event. The speed of the flux rope decreased from approx.120 to 14 km/s during the decay phase of the first stage and increased again during the second stage to become the CME with a speed of approx.516 km/s. RHESSI and GOES data analyses show that the plasma temperature reached over 20 MK in the first stage, then decreased to approx.10 MK and increased to 15 MK in the second stage. This event provides clear evidence for a secondary heating phase. The enhanced EUV and X-ray emission came from the high corona ( approx.60 arcsec above the limb) in the second stage, approx.40 arcsec higher than the site of the initial flare emission. STEREO-A on-disk observations indicate that the post-flare loops during this stage were of larger scale sizes and spatially distinct from those in the first stage.

  3. Two stages catalytic pyrolysis of refuse derived fuel: production of biofuel via syncrude.

    PubMed

    Miskolczi, N; Buyong, F; Angyal, A; Williams, P T; Bartha, L

    2010-11-01

    Thermo-catalytic pyrolysis of refuse derived fuels with different catalysts had been conducted in a two stages process due to its important potential value as fuel. The first stage was a pure thermal pyrolysis in a horizontal tubular reactor with feed rate of 0.5kg hourly. The second stage was a semi-batch process in the presence of catalysts. Results showed that the tested catalysts significantly have affected the quantity of products. E.g. gas yield could be increased with 350% related to the catalyst free case using ZSM-5, while that of pyrolytic oil was 115% over Y-zeolite. Gases consisted of mainly CO and CO(2) obtained from the tubular reactor, while dominantly hydrocarbons from the second stage. Ni-Mo-catalyst and Co-Mo-catalyst had shown activity in pyrolytic oil upgrading via in-situ hydrogenation-dehydrogenation reactions. Sulphur, nitrogen and chlorine level in pyrolytic oils could be significantly declined by using of catalysts.

  4. Procedure for Optimum Design of a Two-Stage Spur Gear System

    NASA Astrophysics Data System (ADS)

    Abuid, Bader Ahmed; Ameen, Yahya Muhammed

    In this paper, an optimum design of a two-stage spur gear system is performed. The optimization is based on a multicriterion technique consisting of a Min-Max method combined with a direct search technique. The optimum design includes the minimization of seven objective functions. They are the volume of gears, the center distance and five dynamic factors in the input shaft, first-teeth meshing, intermediate shaft, second meshing and the output shaft. The dynamic factors are estimated using a dynamic model of twelve degrees of freedom. The objective functions are governed by eleven design variables, chosen to be the number of teeth and face width of the pinion of each stage, stiffness of the input, intermediate, and output shafts and the inertia of the four gears of the mechanism. The developed optimum design is found to give compact-gear system with quiet running (minimum dynamic factors) compared with the classical design. The angle between the power transmitting directions is found to have an important role on the objective functions and the optimum design. A value of 180° for this angle is found to be the optimal for all functions.

  5. Comparing regression methods for the two-stage clonal expansion model of carcinogenesis.

    PubMed

    Kaiser, J C; Heidenreich, W F

    2004-11-15

    In the statistical analysis of cohort data with risk estimation models, both Poisson and individual likelihood regressions are widely used methods of parameter estimation. In this paper, their performance has been tested with the biologically motivated two-stage clonal expansion (TSCE) model of carcinogenesis. To exclude inevitable uncertainties of existing data, cohorts with simple individual exposure history have been created by Monte Carlo simulation. To generate some similar properties of atomic bomb survivors and radon-exposed mine workers, both acute and protracted exposure patterns have been generated. Then the capacity of the two regression methods has been compared to retrieve a priori known model parameters from the simulated cohort data. For simple models with smooth hazard functions, the parameter estimates from both methods come close to their true values. However, for models with strongly discontinuous functions which are generated by the cell mutation process of transformation, the Poisson regression method fails to produce reliable estimates. This behaviour is explained by the construction of class averages during data stratification. Thereby, some indispensable information on the individual exposure history was destroyed. It could not be repaired by countermeasures such as the refinement of Poisson classes or a more adequate choice of Poisson groups. Although this choice might still exist we were unable to discover it. In contrast to this, the individual likelihood regression technique was found to work reliably for all considered versions of the TSCE model.

  6. A Two-Stage-to-Orbit Spaceplane Concept With Growth Potential

    NASA Technical Reports Server (NTRS)

    Mehta, Unmeel B.; Bowles, Jeffrey V.

    2001-01-01

    A two-stage-to-orbit (TSTO) spaceplane concept developed in 1993 is revisited, and new information is provided to assist in the development of the next-generation space transportation vehicles. The design philosophy, TSTO spaceplane concept, and the design method are briefly described. A trade study between cold and hot structures leads to the choice of cold structures with external thermal protection systems. The optimal Mach number for staging the second stage of the TSTO spaceplane (with air-breathing propulsion on the first stage) is 10, based on life-cycle cost analysis. The performance and specification of a prototype/experimental (P/X) TSTO spaceplane with a turbo/ram/scramjet propulsion system and built-in growth potential are presented and discussed. The internal rate of return on investment is the highest for the proposed TSTO spaceplane, vis-A-vis a single-stage-to-orbit (SSTO) rocket vehicle and a TSTO spaceplane without built-in growth. Additional growth potentials for the proposed spaceplane are suggested. This spaceplane can substantially decrease access-to-space cost and risk, and increase safety and reliability in the near term It can be a serious candidate for the next-generation space transportation system.

  7. Two-Stage Adaptive Cutoff (TACO) Design for Building and Validating a Prognostic Biomarker Signature

    PubMed Central

    Polley, Mei-Yin C.; Polley, Eric C.; Huang, Erich P.; Freidlin, Boris; Simon, Richard

    2014-01-01

    Cancer biomarkers are frequently evaluated using archived specimens collected from previously conducted therapeutic trials. Routine collection and banking of high quality specimens is an expensive and time-consuming process. Therefore, care should be taken to preserve these precious resources. Here we propose a novel two-stage adaptive cutoff (TACO) design that affords the possibility to stop the biomarker study early if an evaluation of the model performance is unsatisfactory at an early stage, thereby allowing one to preserve the remaining specimens for future research. In addition, our design integrates important elements necessary to meet statistical rigor and practical demands for developing and validating a prognostic biomarker signature, including maintaining strict separation between the datasets used to build and evaluate the model and producing a locked-down signature to facilitate future validation. We conduct simulation studies to evaluate the operating characteristics of the proposed design. We show that under the null hypothesis when the model performance is deemed undesirable, the proposed design maintains type I error at the nominal level, has high probabilities of terminating the study early, and results in substantial savings in specimens. Under the alternative hypothesis, power is generally high when the total sample size and the targeted degree of improvement in prediction accuracy are reasonably large. We illustrate the use of the procedure with a dataset in patients with diffuse large-B-cell lymphoma. The practical aspects of the proposed designs are discussed. PMID:25263614

  8. Concentration and purification of chromate from electroplating wastewater by two-stage electrodialysis processes.

    PubMed

    Chen, Shiao-Shing; Li, Chi-Wang; Hsu, Hong-Der; Lee, Po-Ching; Chang, Yu-Min; Yang, Chia-Hao

    2009-01-30

    A designed two-stage electrodialysis system is proposed to concentrate and purify chromate from a low pH electroplating wastewater using monovalent selective electrodialysis membranes. With low pH of the raw water (pH 2.2) in the first stage, chromate was presented as HCrO(4)(-) and monovalent ions (HCrO(4)(-), NH(2)SO(3)(-), Na(+) and Cl(-)) were able to pass through the membrane thus chromate was concentrated up to 191%. Higher current density, flowrate and more membrane area all increased the chromium recovery. When pH was adjusted to 8.5 before entering the second stage, the chromate species was presented as divalent CrO(4)(2-) and retained in the concentrated stream, and the rest monovalent ions (NH(2)SO(3)(-), Na(+) and Cl(-)) were separated by passing through the membrane. For example, 45% of the chlorides were separated in this study. The separation efficiencies in the second stage were also increased when the current density, flowrate and membrane area were increased. Electron Spectroscopy for Chemical Analysis was used to examine the surface chromate species for stage 1, and anion exchange membrane showed more chromate fouling comparing to cation exchange membrane due to more adsorption and concentration polarization effects for the anion exchange membrane.

  9. Treatment of anaerobically digested dairy manure in a two-stage biofiltration system.

    PubMed

    Xia, Mengjing; Tao, Wendong; Wang, Ziyuan; Pei, Yuansheng

    2012-01-01

    High concentrations of ammonium and phosphate present a challenge to cost-effective treatment of anaerobically digested dairy manure. This study investigated the efficacy of a two-stage biofiltration system for passive treatment of digested dairy manure. The first stage pebble filters were batch loaded. When the slurry-like digested dairy manure was retained on pebble beds, soluble contaminants were removed before liquid infiltrated over 8-17 days. The pebble filters removed 70% of soluble chemical oxygen demand, 71% of soluble biochemical oxygen demand, 75% of ammonium, and 68% of orthophosphate. Nitrogen removal was attributed to the conventional nitrification - denitrification process and novel nitritation - anammox process. Aerobic ammonium oxidizing and anammox bacteria accounted for 25 and 23% of all bacteria, respectively, in the filtrate of the pebble filters. The longer it took for filtration, the greater the removal efficiency of soluble contaminants. The second stage sand filters had removal efficiencies of 17% for soluble chemical oxygen demand, 45% for soluble biochemical oxygen demand, 43% for ammonium, and 16% for orthophosphate during batch operations at a hydraulic retention time of 7 days. Aerobic ammonium oxidation and anammox were primarily responsible for nitrogen removal in the sand filters. Vegetation made an insignificant difference in treatment performance of the sand filters.

  10. Antioxidant activity and total phenolic content of Moringa oleifera leaves in two stages of maturity.

    PubMed

    Sreelatha, S; Padma, P R

    2009-12-01

    Antioxidants play an important role in inhibiting and scavenging free radicals, thus providing protection to human against infections and degenerative diseases. Current research is now directed towards natural antioxidants originated from plants due to safe therapeutics. Moringa oleifera is used in Indian traditional medicine for a wide range of various ailments. To understand the mechanism of pharmacological actions, antioxidant properties of the Moringa oleifera leaf extracts were tested in two stages of maturity using standard in vitro models. The successive aqueous extract of Moringa oleifera exhibited strong scavenging effect on 2, 2-diphenyl-2-picryl hydrazyl (DPPH) free radical, superoxide, nitric oxide radical and inhibition of lipid per oxidation. The free radical scavenging effect of Moringa oleifera leaf extract was comparable with that of the reference antioxidants. The data obtained in the present study suggests that the extracts of Moringa oleifera both mature and tender leaves have potent antioxidant activity against free radicals, prevent oxidative damage to major biomolecules and afford significant protection against oxidative damage.

  11. Optimum performance analysis of a two-stage irreversible magnetization Brayton refrigeration system

    NASA Astrophysics Data System (ADS)

    Zhang, Yue; Lin, Bihong; Chen, Jincan

    2006-10-01

    A two-stage magnetization Brayton refrigeration cycle model using a paramagnetic material as the working substance is established, in which the regeneration and the irreversibility in the adiabatic processes are taken into account. On the basis of the thermodynamic properties of a paramagnetic material, the expressions of some important parameters such as the coefficient of performance, refrigeration load and work input are derived and used to analyse the performance characteristics of the refrigeration cycle. The influence of the inter-magnetization process, irreversibility in the adiabatic processes and regeneration on the performance of the cycle is discussed in detail. The advantage of adding the inter-magnetization process is expounded and the magnetic field ratio related to the inter-magnetization process is optimized. Moreover, the optimal values of the temperatures of the working substance at different state points and the optimally operating region of the cycle are determined. The results obtained here are compared with those derived from some relevant magnetic Brayton refrigeration cycles, and consequently, some significant conclusions are obtained.

  12. A cooperation model based on CVaR measure for a two-stage supply chain

    NASA Astrophysics Data System (ADS)

    Xu, Xinsheng; Meng, Zhiqing; Shen, Rui

    2015-07-01

    In this paper, we introduce a cooperation model (CM) for the two-stage supply chain consisting of a manufacturer and a retailer. In this model, it is supposed that the objective of the manufacturer is to maximise his/her profit while the objective of the retailer is to minimise his/her CVaR while controlling the risk originating from fluctuation in market demand. In reality, the manufacturer and the retailer would like to choose their own decisions as to wholesale price and order quantity to optimise their own objectives, resulting the fact that the expected decision of the manufacturer and that of the retailer may conflict with each other. Then, to achieve cooperation, the manufacturer and the retailer both need to give some concessions. The proposed model aims to coordinate the decisions of the manufacturer and the retailer, and balance the concessions of the two in their cooperation. We introduce an s* - optimal equilibrium solution in this model, which can decide the minimum concession that the manufacturer and the retailer need to give for their cooperation, and prove that the s* - optimal equilibrium solution can be obtained by solving a goal programming problem. Further, the case of different concessions made by the manufacturer and the retailer is also discussed. Numerical results show that the CM is efficient in dealing with the cooperations between the supplier and the retailer.

  13. Two-stage acceleration of protons from relativistic laser-solid interaction

    SciTech Connect

    Liu Jinlu; Sheng, Z. M.; Zheng, J.; Wang, W. M.; Yu, M. Y.; Liu, C. S.; Zhang, J.

    2012-12-21

    A two-stage proton acceleration scheme using present-day intense lasers and a unique target design is proposed. The target system consists of a hollow cylinder, inside which is a hollow cone, which is followed by the main target with a flat front and dish-like flared rear surface. At the center of the latter is a tapered proton layer, which is surrounded by outer proton layers at an angle to it. In the first acceleration stage, protons in both layers are accelerated by target normal sheath acceleration. The center-layer protons are accelerated forward along the axis and the side protons are accelerated and focused towards them. As a result, the side-layer protons radially compress as well as axially further accelerate the front part of the accelerating center-layer protons in the second stage, which are also radially confined and guided by the field of the fast electrons surrounding them. Two-dimensional particle-incell simulation shows that a 79fs 8.5 Multiplication-Sign 10{sup 20} W/cm{sup 2} laser pulse can produce a proton bunch with {approx} 267MeV maximum energy and {approx} 9.5% energy spread, which may find many applications, including cancer therapy.

  14. The role of the upper sample size limit in two-stage bioequivalence designs.

    PubMed

    Karalis, Vangelis

    2013-11-01

    Two-stage designs (TSDs) are currently recommended by the regulatory authorities for bioequivalence (BE) assessment. The TSDs presented until now rely on an assumed geometric mean ratio (GMR) value of the BE metric in stage I in order to avoid inflation of type I error. In contrast, this work proposes a more realistic TSD design where sample re-estimation relies not only on the variability of stage I, but also on the observed GMR. In these cases, an upper sample size limit (UL) is introduced in order to prevent inflation of type I error. The aim of this study is to unveil the impact of UL on two TSD bioequivalence approaches which are based entirely on the interim results. Monte Carlo simulations were used to investigate several different scenarios of UL levels, within-subject variability, different starting number of subjects, and GMR. The use of UL leads to no inflation of type I error. As UL values increase, the % probability of declaring BE becomes higher. The starting sample size and the variability of the study affect type I error. Increased UL levels result in higher total sample sizes of the TSD which are more pronounced for highly variable drugs.

  15. Two-stage revision of hip prosthesis infection using a hip spacer with stabilising proximal cementation.

    PubMed

    Gil Gonzalez, Sergi; Marqués López, Fernando; Rigol Ramon, Pau; Mestre Cortadellas, Carlos; Cáceres Palou, Enric; León García, Alfonso

    2010-01-01

    Two-stage revision hip arthroplasty for infection using an antibiotic-loaded cement spacer has been used frequently with good results. However, spacer instability is also frequent. Proximal cementation of the spacer could avoid spacer dislocation. We retrospectively assessed 35 patients in whom a 2-stage revision hip arthroplasty for infection was carried out using an antibiotic-loaded cement spacer with gentamicin (Spacer-G) in which the spacer was proximally cemented in 16 patients. The mean follow-up was 32 months. We assessed spacer stability and infection elimination. There were 8 spacer dislocations (22.9%), 5 in hips without proximal cementation and 2 in hips with proximal cementation (p>0.05). There was no fracture in any hip. Reinfection occurred in 5 hips (14.3%), in 3 with the same microorganism, while 2 had a different microorganism. Our results indicate that the proximal cementation of the spacer prevents its dislocation. Infection was eliminated in 86% of the hips.

  16. A Two-Stage Model for Lipid Modulation of the Activity of Integral Membrane Proteins

    PubMed Central

    Dodes Traian, Martín M.; Cattoni, Diego I.; Levi, Valeria; González Flecha, F. Luis

    2012-01-01

    Lipid-protein interactions play an essential role in the regulation of biological function of integral membrane proteins; however, the underlying molecular mechanisms are not fully understood. Here we explore the modulation by phospholipids of the enzymatic activity of the plasma membrane calcium pump reconstituted in detergent-phospholipid mixed micelles of variable composition. The presence of increasing quantities of phospholipids in the micelles produced a cooperative increase in the ATPase activity of the enzyme. This activation effect was reversible and depended on the phospholipid/detergent ratio and not on the total lipid concentration. Enzyme activation was accompanied by a small structural change at the transmembrane domain reported by 1-aniline-8-naphtalenesulfonate fluorescence. In addition, the composition of the amphipilic environment sensed by the protein was evaluated by measuring the relative affinity of the assayed phospholipid for the transmembrane surface of the protein. The obtained results allow us to postulate a two-stage mechanistic model explaining the modulation of protein activity based on the exchange among non-structural amphiphiles at the hydrophobic transmembrane surface, and a lipid-induced conformational change. The model allowed to obtain a cooperativity coefficient reporting on the efficiency of the transduction step between lipid adsorption and catalytic site activation. This model can be easily applied to other phospholipid/detergent mixtures as well to other membrane proteins. The systematic quantitative evaluation of these systems could contribute to gain insight into the structure-activity relationships between proteins and lipids in biological membranes. PMID:22723977

  17. Payload Performance Analysis for a Reusable Two-Stage-to-Orbit Vehicle

    NASA Technical Reports Server (NTRS)

    Tartabini, Paul V.; Beaty, James R.; Lepsch, Roger A.; Gilbert, Michael G.

    2015-01-01

    This paper investigates a unique approach in the development of a reusable launch vehicle where, instead of designing the vehicle to be reusable from its inception, as was done for the Space Shuttle, an expendable two stage launch vehicle is evolved over time into a reusable launch vehicle. To accomplish this objective, each stage is made reusable by adding the systems necessary to perform functions such as thermal protection and landing, without significantly altering the primary subsystems and outer mold line of the original expendable vehicle. In addition, some of the propellant normally used for ascent is used instead for additional propulsive maneuvers after staging in order to return both stages to the launch site, keep loads within acceptable limits and perform a soft landing. This paper presents a performance analysis that was performed to investigate the feasibility of this approach by quantifying the reduction in payload capability of the original expendable launch vehicle after accounting for the mass additions, trajectory changes and increased propellant requirements necessary for reusability. Results show that it is feasible to return both stages to the launch site with a positive payload capability equal to approximately 50 percent of an equivalent expendable launch vehicle. Further discussion examines the ability to return a crew/cargo capsule to the launch site and presents technical challenges that would have to be overcome.

  18. Two-stage Framework for a Topology-Based Projection and Visualization of Classified Document Collections

    SciTech Connect

    Oesterling, Patrick; Scheuermann, Gerik; Teresniak, Sven; Heyer, Gerhard; Koch, Steffen; Ertl, Thomas; Weber, Gunther H.

    2010-07-19

    During the last decades, electronic textual information has become the world's largest and most important information source available. People have added a variety of daily newspapers, books, scientific and governmental publications, blogs and private messages to this wellspring of endless information and knowledge. Since neither the existing nor the new information can be read in its entirety, computers are used to extract and visualize meaningful or interesting topics and documents from this huge information clutter. In this paper, we extend, improve and combine existing individual approaches into an overall framework that supports topological analysis of high dimensional document point clouds given by the well-known tf-idf document-term weighting method. We show that traditional distance-based approaches fail in very high dimensional spaces, and we describe an improved two-stage method for topology-based projections from the original high dimensional information space to both two dimensional (2-D) and three dimensional (3-D) visualizations. To show the accuracy and usability of this framework, we compare it to methods introduced recently and apply it to complex document and patent collections.

  19. Depth-dependent extension, two-stage breakup and cratonic underplating at rifted margins.

    PubMed

    Huismans, Ritske; Beaumont, Christopher

    2011-05-05

    Uniform lithospheric extension predicts basic properties of non-volcanic rifted margins but fails to explain other important characteristics. Significant discrepancies are observed at 'type I' margins (such as the Iberia-Newfoundland conjugates), where large tracts of continental mantle lithosphere are exposed at the sea floor, and 'type II' margins (such as some ultrawide central South Atlantic margins), where thin continental crust spans wide regions below which continental lower crust and mantle lithosphere have apparently been removed. Neither corresponds to uniform extension. Instead, either crust or mantle lithosphere has been preferentially removed. Using dynamical models, we demonstrate that these margins are opposite end members: in type I, depth-dependent extension results in crustal-necking breakup before mantle-lithosphere breakup and in type II, the converse is true. These two-layer, two-stage breakup behaviours explain the discrepancies and have implications for the styles of the associated sedimentary basins. Laterally flowing lower-mantle cratonic lithosphere may underplate some type II margins, thereby contributing to their anomalous characteristics.

  20. Two-stage sparse coding of region covariance via Log-Euclidean kernels to detect saliency.

    PubMed

    Zhang, Ying-Ying; Yang, Cai; Zhang, Ping

    2017-05-01

    In this paper, we present a novel bottom-up saliency detection algorithm from the perspective of covariance matrices on a Riemannian manifold. Each superpixel is described by a region covariance matrix on Riemannian Manifolds. We carry out a two-stage sparse coding scheme via Log-Euclidean kernels to extract salient objects efficiently. In the first stage, given background dictionary on image borders, sparse coding of each region covariance via Log-Euclidean kernels is performed. The reconstruction error on the background dictionary is regarded as the initial saliency of each superpixel. In the second stage, an improvement of the initial result is achieved by calculating reconstruction errors of the superpixels on foreground dictionary, which is extracted from the first stage saliency map. The sparse coding in the second stage is similar to the first stage, but is able to effectively highlight the salient objects uniformly from the background. Finally, three post-processing methods-highlight-inhibition function, context-based saliency weighting, and the graph cut-are adopted to further refine the saliency map. Experiments on four public benchmark datasets show that the proposed algorithm outperforms the state-of-the-art methods in terms of precision, recall and mean absolute error, and demonstrate the robustness and efficiency of the proposed method.

  1. Developments in laser wakefield accelerators: From single-stage to two-stage

    NASA Astrophysics Data System (ADS)

    Li, Wen-Tao; Wang, Wen-Tao; Liu, Jian-Sheng; Wang, Cheng; Zhang, Zhi-Jun; Qi, Rong; Yu, Chang-Hai; Li, Ru-Xin; Xu, Zhi-Zhan

    2015-01-01

    Laser wakefield accelerators (LWFAs) are compact accelerators which can produce femtosecond high-energy electron beams on a much smaller scale than the conventional radiofrequency accelerators. It is attributed to their high acceleration gradient which is about 3 orders of magnitude larger than the traditional ones. The past decade has witnessed the major breakthroughs and progress in developing the laser wakfield accelerators. To achieve the LWFAs suitable for applications, more and more attention has been paid to optimize the LWFAs for high-quality electron beams. A single-staged LWFA does not favor generating controllable electron beams beyond 1 GeV since electron injection and acceleration are coupled and cannot be independently controlled. Staged LWFAs provide a promising route to overcome this disadvantage by decoupling injection from acceleration and thus the electron-beam quality as well as the stability can be greatly improved. This paper provides an overview of the physical conceptions of the LWFA, as well as the major breakthroughs and progress in developing LWFAs from single-stage to two-stage LWFAs. Project supported by the National Natural Science Foundation of China (Grant Nos. 11127901, 11425418, and 61221064), the National Basic Research Program of China (Grant No. 2011CB808100), and the Science and Technology Talent Project of Shanghai City, China (Grant Nos. 12XD1405200 and 12ZR1451700).

  2. A pilot study of quantitative assessment of mandible advancement using pressure-flow relationship during midazolam sedation.

    PubMed

    Ayuse, T; Hoshino, Y; Inazawa, T; Oi, K; Schneider, H; Schwartz, A R

    2006-11-01

    It has been proposed that a titration of the mandibular positioner would be a promising method for predicting the outcome of nasal continuous positive airway pressure (CPAP) therapy. This study was carried out to test the hypothesis that mandible advancement could be evaluated by analysis of inspiratory flow limitation using a titration procedure. To explore its effect, we examined upper airway pressure-flow relationships using a titrated mandible positioner during midazolam sedation. Non-flow limited inspiration occurred when the mandible was advanced 7.1 +/- 1.2 mm from centric occlusion position. In the centric occlusion position (0 mm advancement), Pcrit was -1.9 +/- 2.9 cmH2O and Rua was 23.3 +/- 4.5 cmH2O L(-1) s(-1). In the eMAP position, Pcrit was -7.3 +/- 1.9 cmH2O and Rua was 27.8 +/- 3.3 cmH2O L(-1) s(-1). Essentially no CPAP was required to overcome flow limitation in eMAP position, whereas 3.7 +/- 2.2 cmH2O CPAP was required in centric occlusion position. We conclude that assessing inspiratory flow limitation using a titrated mandible positioner was effective for estimating individual-matched mandible positions.

  3. Comparison of transient and stationary neutral pressure response in the DIII-D advanced divertor

    SciTech Connect

    Klepper, C.C.; Hogan, J.T.; Owen, L.W.; Mioduszewski, P.K.; Maingi, R.; Hill, D.N.; Buchenauer, D.; Ali Mahdavi, M.; Schaffer, M.J.; Petrie, T.W.; Jackson, G.L.; Evans, T.E.; Haas, G.

    1992-05-01

    The DIII-D divertor baffle system was designed to facilitate density control in long pulse H-mode discharges by removing a particle flux equal to the neutral beam fueling rate ({approximately}20 Torr-1/s) with a {approximately}1mTorr neutral pressure under the baffle (p{sub 0}). Initial measurements of the baffle pressure indicated that p{sub 0}{approximately} 10 mTorr (without pumping or biasing), a value much in excess of that required for long pulse density control. Radial sweeps of the X-point position have been employed to determine the maximum p{sub 0}, as well as to establish the dependence of this pressure on geometry. An estimate of the particle equilibration time for the baffle system has been made by studying the baffle pressure response to ``giant`` ELM effects. ``Steady state`` experiments in which the X-point position was fixed for {approximately}2.5s have also been carried out and steady baffle pressures were observed. The scaling of baffle pressure with plasma parameters has been found to be similar under transient and ``steady state`` conditions. Detailed modeling of these experiments with the B2, DEGAS, and WDIFFUSE (wall model) codes has been made.

  4. Development of Advanced ISS-WPA Catalysts for Organic Oxidation at Reduced Pressure/Temperature

    NASA Technical Reports Server (NTRS)

    Yu, Ping; Nalette, Tim; Kayatin, Matthew

    2016-01-01

    The Water Processor Assembly (WPA) at International Space Station (ISS) processes a waste stream via multi-filtration beds, where inorganic and non-volatile organic contaminants are removed, and a catalytic reactor, where low molecular weight organics not removed by the adsorption process are oxidized at elevated pressure in the presence of oxygen and elevated temperature above the normal water boiling point. Operation at an elevated pressure requires a more complex system design compared to a reactor that could operate at ambient pressure. However, catalysts currently available have insufficient activity to achieve complete oxidation of the organic load at a temperature less than the water boiling point and ambient pressure. Therefore, it is highly desirable to develop a more active and efficient catalyst at ambient pressure and a moderate temperature that is less than water boiling temperature. This paper describes our efforts in developing high efficiency water processing catalysts. Different catalyst support structures and coating metals were investigated in subscale reactors and results were compared against the flight WPA catalyst. Detailed improvements achieved on alternate metal catalysts at ambient pressure and 200 F will also be presented in the paper.

  5. Achieve Continuous Injection of Solid Fuels into Advanced Combustion System Pressures

    SciTech Connect

    Derek L. Aldred; Timothy Saunders

    2007-03-31

    The overall objective of this project is the development of a mechanical rotary-disk feeder, known as the Stamet Posimetric High Pressure Solids Feeder System, to demonstrate feeding of dry granular coal continuously and controllably into pressurized environments of up to 70 kg/cm2 (1,000 psi). This is the Phase III of the ongoing program. Earlier Phases 1 and II successfully demonstrated feeding into pressures up to 35 kg/cm{sup 2} (500 psi). The final report for those phases was submitted in April 2005. Based on the previous work done in Phases I & II using Powder River Basin coal provided by the PSDF facility in Wilsonville, AL, a Phase III feeder system was designed and built to accomplish the target of feeding the coal into a pressure of 70 kg/cm2 (1,000 psi) and to be capable of feed rates of up to 550 kilograms (1,200lbs) per hour. The drive motor system from Phase II was retained for use on Phase III since projected performance calculations indicated it should be capable of driving the Phase III pump to the target levels. The pump & motor system was installed in a custom built test rig comprising an inlet vessel containing an active live-wall hopper mounted on weigh cells in a support frame, transition into the pump inlet, transition from pump outlet and a receiver vessel containing a receiver drum supported on weigh cells. All pressure containment on the rig was rated to105 kg/cm{sup 2} (1,500psi) to accommodate the final pressure requirement of a proposed Phase IV of the program. A screw conveyor and batch hopper were added to transfer coal at atmospheric pressure from the shop floor up into the test rig to enable continuous feeding up to the capacity of the receiving vessel. Control & monitoring systems were up-rated from the Phase II system to cover the additional features incorporated in the Phase III rig, and provide closer control and expanded monitoring of the entire system. A program of testing and modification was carried out in Stamet's facility

  6. Advanced cooling techniques for high-pressure hydrocarbon-fueled engines

    NASA Technical Reports Server (NTRS)

    Cook, R. T.

    1979-01-01

    The regenerative cooling limits (maximum chamber pressure) for 02/hydrocarbon gas generator and staged combustion cycle rocket engines over a thrust range of 89,000 N (20,000lbf) to 2,669,000 N (600,000 lbf) for a reusable life of 250 missions were defined. Maximum chamber pressure limits were first determined for the three propellant combinations (O2/CH4, O2/C3H8, and O2/RP-1 without a carbon layer (unenhanced designs). Chamber pressure cooling enhancement limits were then established for seven thermal barriers. The thermal barriers evaluated for these designs were: carbon layer, ceramic coating, graphite liner, film cooling, transpiration cooling, zoned combustion, and a combination of two of the above. All fluid barriers were assessed a 3 percent performance loss. Sensitivity studies were then conducted to determine the influence of cycle life and RP-1 decomposition temperature on chamber pressure limits. Chamber and nozzle design parameters are presented for the unenahanced and enhanced designs. The maximum regenerative cooled chamber pressure limits were attained with the O2/CH4 propellant combination. The O2/RP-1 designs relied on a carbon layer and liquid gas injection chamber contours, short chamber, to be competitive with the other two propellant combinations. This was attributed to the low decomposition temperature of RP-1.

  7. Two-Stage Acceleration Mechanism for Impulsive Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Wu, S.; Tan, A.

    2006-12-01

    Two distinct classes of impulsive and gradual solar energetic particle events have been recognized (Reames, ApJ, 571, L63, 2002). The impulsive events are characterized by 1) abundance enhancements of 3He/4He by a factor of ~ 104, Fe/O by a factor of ~ 10 in Fe/O, ^{22}Ne/20Ne by a factor of ~ 2-3, and (Z > 50)/O by a factor of ~ 102 -104, 2) high charge states of ions, 3) short durations (a few minutes to several hours), 4) small but frequently occurred events ( ~ 1000 per year), and 5) type-III radio bursts. The gradual events are characterized by 1) coronal mass ejection associations, 2) normal abundances and charge states of ions, 3) long durations (several hours to days), 4) large but rarely occurred events (~ 10 per year), and 5) type-I, IV radio bursts. Some solar gradual events can be superhot with temperature up to ~ 40 MK and contain both impulsive and gradual phases, so that these events have the features of both the impulsive and gradual events such as the RHESSI observed 2002 July 23 event (Lin et al., ApJ, 595, L69, 2003). Based on Cartwright and Mogro-Campero (ApJ, 177, L43, 1972) scenario and Fisk (ApJ, 224, 1048, 1978) efforts, Zhang (ApJ, 449, 916, 1995; ApJ, 518, 954, 1999) developed a complete two-stage acceleration model for solar impulsive or 3He-rich events. Plasma waves with frequency close to the harmonics of the 3He- cyclotron frequency efficiently heat 3He and heavy ions with appropriate charge states through the harmonic resonances and electrons through Landau resonances. The preheating of ions significantly increases the number of them that are injected into the flare-acceleration processes, and therefore lead to the enhancements of the ions in solar energetic particle events. The two-stage acceleration model has self- consistently explained various aspects of accelerations of ions and electrons in solar 3He-rich events (Zhang, JGR, 108A, SSH6Z, 2003; ApJ, 617, L77, 2004; Zhang and Wang, ApJ, 588, L57, 2003; ApJ, 613, L165, 2004; Zhang

  8. Oxygen transport membrane based advanced power cycle with low pressure synthesis gas slip stream

    DOEpatents

    Kromer, Brian R.; Litwin, Michael M.; Kelly, Sean M.

    2016-09-27

    A method and system for generating electrical power in which a high pressure synthesis gas stream generated in a gasifier is partially oxidized in an oxygen transport membrane based reactor, expanded and thereafter, is combusted in an oxygen transport membrane based boiler. A low pressure synthesis gas slip stream is split off downstream of the expanders and used as the source of fuel in the oxygen transport membrane based partial oxidation reactors to allow the oxygen transport membrane to operate at low fuel pressures with high fuel utilization. The combustion within the boiler generates heat to raise steam to in turn generate electricity by a generator coupled to a steam turbine. The resultant flue gas can be purified to produce a carbon dioxide product.

  9. Temperature and pressure measurement techniques for an advanced turbine test facility

    NASA Technical Reports Server (NTRS)

    Pollack, F. G.; Cochran, R. P.

    1980-01-01

    A high pressure, high-temperature turbine test facility constructed for use in turbine cooling research is described. Several recently developed temperature and pressure measuring techniques are used in this facility. The measurement techniques, their status, previous applications and some results are discussed. Noncontact surface temperature measurements are made by optical methods. Radiation pyrometry principles combined with photoelectric scanning are used for rotating components and infrared photography for stationary components. Contact (direct) temperature and pressure measurements on rotating components are expected to be handled with an 80 channel rotary data package which mounts on and rotates with the turbine shaft at speeds up to 17,500 rpm. The data channels are time-division multiplexed and converted to digital words in the data package. A rotary transformer couples power and digital data to and from the shaft.

  10. Protozoan Grazing, Bacterial Activity, and Mineralization in Two-Stage Continuous Cultures

    PubMed Central

    Bloem, Jaap; Starink, Mathieu; Bär-Gilissen, Marie-José B.; Cappenberg, Thomas E.

    1988-01-01

    In two-stage continuous cultures, at bacterial concentrations, biovolumes, and growth rates similar to values found in Lake Vechten, ingestion rates of heterotrophic nanoflagellates (HNAN) increased from 2.3 bacteria HNAN−1 · h−1 at a growth rate of 0.15 day−1 to 9.2 bacteria · HNAN−1 · h−1 at a growth rate of 0.65 day−1. On a yeast extract medium with a C/N/P ratio of 100:15:1.2 (Redfield ratio), a mixed bacterial population showed a yield of 18% (C/C) and a specific carbon content of 211 fg of C · μm−3. The HNAN carbon content and yield were estimated at 127 fg of C · μm−3 and 47% (C/C). Although P was not growth limiting, HNAN accelerated the mineralization of PO4-P from dissolved organic matter by 600%. The major mechanism of P remineralization appeared to be direct consumption of bacteria by HNAN. N mineralization was performed mainly (70%) by bacteria but was increased 30% by HNAN. HNAN did not enhance the decomposition of the relatively mineral-rich dissolved organic matter. An accelerated decomposition of organic carbon by protozoa may be restricted to mineral-poor substrates and may be explained mainly by protozoan nutrient regeneration. Growth and grazing in the cultures were compared with methods for in situ estimates. Thymidine incorporation by actively growing bacteria yielded an empirical conversion factor of 1.1 × 1018 bacteria per mol of thymidine incorporated into DNA. However, nongrowing bacteria also showed considerable incorporation. Protozoan grazing was found to be accurately measured by uptake of fluorescently labeled bacteria, whereas artificial fluorescent microspheres were not ingested, and selective prokaryotic inhibitors blocked not only bacterial growth but also protozoan grazing. PMID:16347801

  11. Two-stage models for lunar and terrestrial anorthosites: Petrogenesis without a magma ocean

    NASA Astrophysics Data System (ADS)

    Longhi, John; Ashwal, Lewis D.

    1985-02-01

    Two-stage diapiric models for lunar ferroan anorthosites and terrestrial massif anorthosites are examined. The lunar model is developed to explain early lunar differentiation in the absence of a magma ocean. If correct, the terrestrial model serves as an analog for the development of lunar anorthositic diapirs. There is field and textural evidence of transport of mostly crystalline anorthositic material within the terrestrial complexes. This evidence, combined with the absence of anorthositic lavas and phase equilibrium constraints inhibiting the production of hyperaluminous magmas, is consistent with the detachment of plagioclase-rich crystalline mushes from large, uppermost mantle plutons and multiple diapiric intrusion of these mushes into the upper sialic crust with attendant anatexis. Rudimentary dynamical calculations suggest that a simple, single-layer source for the diapirs is improbable: either there were several parental magma chambers or there was a single large chamber that was repeatedly replenished. The lunar model is a development of Wetherill's (1975) suggestion that, following accretion, the outer portion of the moon consisted of a stack of overlapping layered intrusions and that reheating of these intrusions mobilized their anorthositic layers, which intruded upwards to produce the anorthositic lunar crust. Dynamical calculations show that gravitational instabilities in anorthositic layers (≤ 1 km thick) could develop into diapirs on a reasonable time scale (50-100 m.y.) only if the outer portion of the moon was partially remelted. We suggest that partial melting of the interior due to the decay of long-lived radionuclides with the subsequent onset of global convection heated the stack of intrusions from below, thus causing melting and allowing the anorthositic diapirs to grow and ascend fairly rapidly. As the convecting zone thickened, a mass expulsion of anorthositic material out of the lunar interior may have occurred.

  12. Chromosome 21 BACE2 haplotype associates with Alzheimer's disease: a two-stage study.

    PubMed

    Myllykangas, Liisa; Wavrant-De Vrièze, Fabienne; Polvikoski, Tuomo; Notkola, Irma-Leena; Sulkava, Raimo; Niinistö, Leena; Edland, Steven D; Arepalli, Sampath; Adighibe, Omanma; Compton, Danielle; Hardy, John; Haltia, Matti; Tienari, Pentti J

    2005-09-15

    Genetic linkage studies have provided evidence for a late-onset Alzheimer's disease (AD) susceptibility locus on chromosome 21q. We have tested, in a two-stage association study, whether allelic or haplotype variation of the beta-amyloid cleaving enzyme-2 (BACE2) locus on chromosome 21q affects the risk of late-onset AD. In stage-1, an unselected population-based sample of Finns aged 85 years or over (n=515) was analysed. Neuropathologic examination including beta-amyloid load quantification was possible in over 50% (n=264) of these subjects. AD patients (n=100) and controls (n=48) were defined by modified neuropathological NIA-RI criteria. Positive associations were taken as a hypothesis, and tested in stage-2 using 483 AD families from the USA. Four single nucleotide polymorphisms (SNPs) of BACE2 gene were tested in stage-1. A SNP close to exon-6 was associated with neuropathologically verified AD (p=0.02) and also with beta-amyloid load in non-selected autopsied subjects after conditioning with APOE genotype (p=0.001). In haplotype analysis a specific, relatively common haplotype (H5) was found to associate with AD (p=0.004) and a second haplotype (H7) showed a weaker association with protection against AD (p=0.04). In stage-2, the SNP association was not replicated, whereas the haplotype H5 association was replicated (p=0.004) and a trend to association was found with the putative protective haplotype H7 (two-sided p=0.08). BACE2 haplotype association with AD in two independent datasets provides further evidence for an AD susceptibility locus on chromosome 21q within or close to BACE2.

  13. Electrolyzed Reduced Water Supplemented with Platinum Nanoparticles Suppresses Promotion of Two-stage Cell Transformation.

    PubMed

    Nishikawa, Ryuhei; Teruya, Kiichiro; Katakura, Yoshinori; Osada, Kazuhiro; Hamasaki, Takeki; Kashiwagi, Taichi; Komatsu, Takaaki; Li, Yuping; Ye, Jun; Ichikawa, Akira; Otsubo, Kazumichi; Morisawa, Shinkatsu; Xu, Qianghua; Shirahata, Sanetaka

    2005-01-01

    In the two-stage cell transformation theory, cancer cells first receive initiation, which is mainly caused by DNA damage, and then promotion, which enhances transformation. Murine Balb/c 3T3 cells are widely used for transformation experiments because they lose contact inhibition ability when transformed. Electrolyzed reduced water (ERW), which is produced near a cathode during electrolysis of water, is an alkaline drinking water that is beneficial to health. ERW contains a high concentration of dissolved hydrogen and scavenge reactive oxygen species (ROS), along with a small amount of platinum (Pt) nanoparticles (Pt nps) derived from Pt-coated titanium electrodes. Pt nps stably disperse in aqueous solution for a long time, and convert hydrogen molecules to active hydrogen (atomic hydrogen) that can scavenge ROS. Therefore, ERW supplemented with synthesized Pt nps is a model strong reduced water. This is the first report that ERW supplemented with synthesized Pt nps strongly prevents transformation of Balb/c 3T3 cells. ERW was prepared by electrolysis of 0.002 M NaOH solution using a batch-type electrolysis device. Balb/c 3T3 cells were treated with 3-methyl cholanthrene (MCA) as an initiation substance, followed by treatment with phorbol-12-myristate-13-acetate (PMA) as a promotion substance. MCA/PMA-induced formation of a transformation focus was strongly suppressed by ERW supplemented with Pt nps but not by ERW or Pt nps individually. ERW supplemented with Pt nps suppressed transformation at the promoter stage, not at initiation, suggesting that ERW supplemented with Pt nps suppressed the PMA-induced augmentation of intracellular ROS. ERW supplemented with Pt nps is a potential new antioxidant against carcinogenesis.

  14. Neural Mechanisms of Human Perceptual Learning: Electrophysiological Evidence for a Two-Stage Process

    PubMed Central

    Hamamé, Carlos M.; Cosmelli, Diego; Henriquez, Rodrigo; Aboitiz, Francisco

    2011-01-01

    Background Humans and other animals change the way they perceive the world due to experience. This process has been labeled as perceptual learning, and implies that adult nervous systems can adaptively modify the way in which they process sensory stimulation. However, the mechanisms by which the brain modifies this capacity have not been sufficiently analyzed. Methodology/Principal Findings We studied the neural mechanisms of human perceptual learning by combining electroencephalographic (EEG) recordings of brain activity and the assessment of psychophysical performance during training in a visual search task. All participants improved their perceptual performance as reflected by an increase in sensitivity (d') and a decrease in reaction time. The EEG signal was acquired throughout the entire experiment revealing amplitude increments, specific and unspecific to the trained stimulus, in event-related potential (ERP) components N2pc and P3 respectively. P3 unspecific modification can be related to context or task-based learning, while N2pc may be reflecting a more specific attentional-related boosting of target detection. Moreover, bell and U-shaped profiles of oscillatory brain activity in gamma (30–60 Hz) and alpha (8–14 Hz) frequency bands may suggest the existence of two phases for learning acquisition, which can be understood as distinctive optimization mechanisms in stimulus processing. Conclusions/Significance We conclude that there are reorganizations in several neural processes that contribute differently to perceptual learning in a visual search task. We propose an integrative model of neural activity reorganization, whereby perceptual learning takes place as a two-stage phenomenon including perceptual, attentional and contextual processes. PMID:21541280

  15. Greater India Basin hypothesis and a two-stage Cenozoic collision between India and Asia

    NASA Astrophysics Data System (ADS)

    Van Hinsbergen, D. J.; Lippert, P. C.; Dupont-Nivet, G.; McQuarrie, N.; Doubrovine, P. V.; Spakman, W.; Torsvik, T. H.

    2012-12-01

    Cenozoic convergence between the Indian and Asian plates pro- duced the archetypical continental collision zone comprising the Himalaya mountain belt and the Tibetan Plateau. How and where India-Asia convergence was accommodated after collision at or before 52 Ma remains a long-standing controversy. Since 52 Ma, the two plates have converged up to 3,600 +/- 35 km, yet the upper crustal shortening documented from the geological record of Asia and the Himalaya is up to approximately 2,350-km less. Here we show that the discrepancy between the convergence and the shortening can be explained by subduction of highly extended continental and oceanic Indian lithosphere within the Himalaya be- tween approximately 50 and 25 Ma. Paleomagnetic data show that this extended continental and oceanic "Greater India" promontory resulted from 2,675 +/- 700 km of North-South extension between 120 and 70 Ma, accommodated between the Tibetan Himalaya and cratonic India. We suggest that the approximately 50 Ma "India"- Asia collision was a collision of a Tibetan-Himalayan microcontinent with Asia, followed by subduction of the largely oceanic Greater India Basin along a subduction zone at the location of the Greater Himalaya. The "hard" India-Asia collision with thicker and contiguous Indian continental lithosphere occurred around 25-20 Ma. This hard collision is coincident with far-field deformation in central Asia and rapid exhumation of Greater Himalaya crystalline rocks, and may be linked to intensification of the Asian monsoon system. This two-stage collision between India and Asia is also reflected in the deep mantle remnants of subduction imaged with seismic tomography.

  16. Two-stage designs to identify the effects of SNP combinations on complex diseases.

    PubMed

    Kang, Guolian; Yue, Weihua; Zhang, Jifeng; Huebner, Marianne; Zhang, Handi; Ruan, Yan; Lu, Tianlan; Ling, Yansu; Zuo, Yijun; Zhang, Dai

    2008-01-01

    The genetic basis of complex diseases is expected to be highly heterogeneous, with many disease genes, where each gene by itself has only a small effect. Based on the nonlinear contributions of disease genes across the genome to complex diseases, we introduce the concept of single nucleotide polymorphism (SNP) synergistic blocks. A two-stage approach is applied to detect the genetic association of synergistic blocks with a disease. In the first stage, synergistic blocks associated with a complex disease are identified by clustering SNP patterns and choosing blocks within a cluster that minimize a diversity criterion. In the second stage, a logistic regression model is given for a synergistic block. Using simulated case-control data, we demonstrate that our method has reasonable power to identify gene-gene interactions. To further evaluate the performance of our method, we apply our method to 17 loci of four candidate genes for paranoid schizophrenia in a Chinese population. Five synergistic blocks are found to be associated with schizophrenia, three of which are negatively associated (odds ratio, OR < 0.3, P < 0.05), while the others are positively associated (OR > 2.0, P < 0.05). The mathematical models of these five synergistic blocks are presented. The results suggest that there may be interactive effects for schizophrenia among variants of the genes neuregulin 1 (NRG1, 8p22-p11), G72 (13q34), the regulator of G-protein signaling-4 (RGS4, 1q21-q22) and frizzled 3 (FZD3, 8p21). Using synergistic blocks, we can reduce the dimensionality in a multi-locus association analysis, and evaluate the sizes of interactive effects among multiple disease genes on complex phenotypes.

  17. Two-stage flux balance analysis of metabolic networks for drug target identification

    PubMed Central

    2011-01-01

    Background Efficient identification of drug targets is one of major challenges for drug discovery and drug development. Traditional approaches to drug target identification include literature search-based target prioritization and in vitro binding assays which are both time-consuming and labor intensive. Computational integration of different knowledge sources is a more effective alternative. Wealth of omics data generated from genomic, proteomic and metabolomic techniques changes the way researchers view drug targets and provides unprecedent opportunities for drug target identification. Results In this paper, we develop a method based on flux balance analysis (FBA) of metabolic networks to identify potential drug targets. This method consists of two linear programming (LP) models, which first finds the steady optimal fluxes of reactions and the mass flows of metabolites in the pathologic state and then determines the fluxes and mass flows in the medication state with the minimal side effect caused by the medication. Drug targets are identified by comparing the fluxes of reactions in both states and examining the change of reaction fluxes. We give an illustrative example to show that the drug target identification problem can be solved effectively by our method, then apply it to a hyperuricemia-related purine metabolic pathway. Known drug targets for hyperuricemia are correctly identified by our two-stage FBA method, and the side effects of these targets are also taken into account. A number of other promising drug targets are found to be both effective and safe. Conclusions Our method is an efficient procedure for drug target identification through flux balance analysis of large-scale metabolic networks. It can generate testable predictions, provide insights into drug action mechanisms and guide experimental design of drug discovery. PMID:21689470

  18. Pilot plant testing of IGT`s two-stage fluidized-bed/cyclonic agglomerating combustor

    SciTech Connect

    Rehmat, A.; Mensinger, M.C.; Richardson, T.L.

    1993-12-31

    The Institute of Gas Technology (IGT) is conducting a multi-year experimental program to develop and test, through pilot-scale operation, IGT`s two-stage fluidized-bed/cyclonic agglomerating combustor (AGGCOM). The AGGCOM process is based on combining the fluidized-bed agglomeration and gasification technology with the cyclonic combustion technology, both of which have been developed at IGT over many years. AGGCOM is a unique and extremely flexible combustor that can operate over a wide range of conditions in the fluidized-bed first stage from low temperature (desorption) to high temperature (agglomeration), including gasification of high-energy-content wastes. The ACCCOM combustor can easily and efficiently destroy solid, liquid, and gaseous organic wastes, while isolating solid inorganic contaminants within an essentially non-leachable glassy matrix, suitable for disposal in ordinary landfills. Fines elutriated from the first stage are captured by a high-efficiency cyclone and returned to the fluidized bed for ultimate incorporation into the agglomerates. Intense mixing in the second-stage cyclonic combustor ensures high destruction and removal efficiencies (DRE) for organic compounds that may be present in the feed material. This paper presents an overview of the experimental development of the AGGCOM process and progress made to date in designing, constructing, and operating the 6-ton/day AGGCOM pilot plant. Results of the bench-scale tests conducted to determine the operating conditions necessary to agglomerate a soil were presented at the 1991 Incineration Conference. On-site construction of the AGGCOM pilot plant was initiated in August 1992 and completed at the end of March 1993, with shakedown testing following immediately thereafter. The initial tests in the AGGCOM pilot plant will focus on the integrated operation of both stages of the combustor and will be conducted with ``clean`` topsoil.

  19. Two-stage muscle activity responses in decisions about leg movement adjustments during trip recovery

    PubMed Central

    Potocanac, Zrinka; Pijnappels, Mirjam; Verschueren, Sabine; van Dieën, Jaap

    2015-01-01

    Studies on neural decision making mostly investigated fast corrective adjustments of arm movements. However, fast leg movement corrections deserve attention as well, since they are often required to avoid falling after balance perturbations. The present study aimed at elucidating the mechanisms behind fast corrections of tripping responses by analyzing the concomitant leg muscle activity changes. This was investigated in seven young adults who were tripped in between normal walking trials and took a recovery step by elevating the tripped leg over the obstacle. In some trials, a forbidden landing zone (FZ) was presented behind the obstacle, at the subjects' preferred foot landing position, forcing a step correction. Muscle activity of the tripped leg gastrocnemius medialis (iGM), tibialis anterior (iTA), rectus femoris (iRF), and biceps femoris (iBF) muscles was compared between normal trips presented before any FZ appearance, trips with a FZ, and normal trips presented in between trips with a FZ (“catch” trials). When faced with a real or expected (catch trials) FZ, subjects shortened their recovery steps. The underlying changes in muscle activity consisted of two stages. The first stage involved reduced iGM activity, occurring at a latency shorter than voluntary reaction, followed by reduced iTA and increased iBF and iGM activities occurring at longer latencies. The fast response was not related to step shortening, but longer latency responses clearly were functional. We suggest that the initial response possibly acts as a “pause,” allowing the nervous system to integrate the necessary information and prepare the subsequent, functional movement adjustment. PMID:26561597

  20. A two-stage cyclone using microcentrifuge tubes for personal bioaerosol sampling.

    PubMed

    Lindsley, William G; Schmechel, Detlef; Chen, Bean T

    2006-11-01

    Personal aerosol samplers are widely used to monitor human exposure to airborne materials. For bioaerosols, interest is growing in analyzing samples using molecular and immunological techniques. This paper presents a personal sampler that uses a two-stage cyclone to collect bioaerosols into disposable 1.5 ml Eppendorf-type microcentrifuge tubes. Samples can be processed in the tubes for polymerase chain reaction (PCR) or immunoassays, and the use of multiple stages fractionates aerosol particles by aerodynamic diameter. The sampler was tested using fluorescent microspheres and aerosolized fungal spores. The sampler had first and second stage cut-off diameters of 2.6 microm and 1.6 microm at 2 l min(-1)(geometric standard deviation, GSD = 1.45 and 1.75), and 1.8 microm and 1 microm at 3.5 l min(-1)(GSD = 1.42 and 1.55). The sampler aspiration efficiency was >or=98% at both flow rates for particles with aerodynamic diameters of 3.1 microm or less. For 6.2 microm particles, the aspiration efficiency was 89% at 2 l min(-1) and 96% at 3.5 l min(-1). At 3.5 l min(-1), the sampler collected 92% of aerosolized Aspergillus versicolor and Penicillium chrysogenum spores inside the two microcentrifuge tubes, with less than 0.4% of the spores collecting on the back-up filter. The design and techniques given here are suitable for personal bioaerosol sampling, and could also be adapted to design larger aerosol samplers for longer-term atmospheric and indoor air quality sampling.