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Sample records for assisting gas optimization

  1. Development and Optimization of Gas-Assisted Gravity Drainage (GAGD) Process for Improved Light Oil Recovery

    SciTech Connect

    Dandina N. Rao; Subhash C. Ayirala; Madhav M. Kulkarni; Wagirin Ruiz Paidin; Thaer N. N. Mahmoud; Daryl S. Sequeira; Amit P. Sharma

    2006-09-30

    This is the final report describing the evolution of the project ''Development and Optimization of Gas-Assisted Gravity Drainage (GAGD) Process for Improved Light Oil Recovery'' from its conceptual stage in 2002 to the field implementation of the developed technology in 2006. This comprehensive report includes all the experimental research, models developments, analyses of results, salient conclusions and the technology transfer efforts. As planned in the original proposal, the project has been conducted in three separate and concurrent tasks: Task 1 involved a physical model study of the new GAGD process, Task 2 was aimed at further developing the vanishing interfacial tension (VIT) technique for gas-oil miscibility determination, and Task 3 was directed at determining multiphase gas-oil drainage and displacement characteristics in reservoir rocks at realistic pressures and temperatures. The project started with the task of recruiting well-qualified graduate research assistants. After collecting and reviewing the literature on different aspects of the project such gas injection EOR, gravity drainage, miscibility characterization, and gas-oil displacement characteristics in porous media, research plans were developed for the experimental work to be conducted under each of the three tasks. Based on the literature review and dimensional analysis, preliminary criteria were developed for the design of the partially-scaled physical model. Additionally, the need for a separate transparent model for visual observation and verification of the displacement and drainage behavior under gas-assisted gravity drainage was identified. Various materials and methods (ceramic porous material, Stucco, Portland cement, sintered glass beads) were attempted in order to fabricate a satisfactory visual model. In addition to proving the effectiveness of the GAGD process (through measured oil recoveries in the range of 65 to 87% IOIP), the visual models demonstrated three possible

  2. DEVELOPMENT AND OPTIMIZATION OF GAS-ASSISTED GRAVITY DRAINAGE (GAGD) PROCESS FOR IMPROVED LIGHT OIL RECOVERY

    SciTech Connect

    Dandina N. Rao; Subhash C. Ayirala; Madhav M. Kulkarni; Thaer N.N. Mahmoud; Wagirin Ruiz Paidin

    2006-01-01

    This report describes the progress of the project ''Development And Optimization of Gas-Assisted Gravity Drainage (GAGD) Process for Improved Light Oil Recovery'' for the duration of the thirteenth project quarter (Oct 1, 2005 to Dec 30, 2005). There are three main tasks in this research project. Task 1 is a scaled physical model study of the GAGD process. Task 2 is further development of a vanishing interfacial tension (VIT) technique for miscibility determination. Task 3 is determination of multiphase displacement characteristics in reservoir rocks. Section I reports experimental work designed to investigate wettability effects of porous medium, on secondary and tertiary mode GAGD performance. The experiments showed a significant improvement of oil recovery in the oil-wet experiments versus the water-wet runs, both in secondary as well as tertiary mode. When comparing experiments conducted in secondary mode to those run in tertiary mode an improvement in oil recovery was also evident. Additionally, this section summarizes progress made with regard to the scaled physical model construction and experimentation. The purpose of building a scaled physical model, which attempts to include various multiphase mechanics and fluid dynamic parameters operational in the field scale, was to incorporate visual verification of the gas front for viscous instabilities, capillary fingering, and stable displacement. Preliminary experimentation suggested that construction of the 2-D model from sintered glass beads was a feasible alternative. During this reporting quarter, several sintered glass mini-models were prepared and some preliminary experiments designed to visualize gas bubble development were completed. In Section II, the gas-oil interfacial tensions measured in decane-CO{sub 2} system at 100 F and live decane consisting of 25 mole% methane, 30 mole% n-butane and 45 mole% n-decane against CO{sub 2} gas at 160 F have been modeled using the Parachor and newly proposed

  3. DEVELOPMENT AND OPTIMIZATION OF GAS-ASSISTED GRAVITY DRAINAGE (GAGD) PROCESS FOR IMPROVED LIGHT OIL RECOVERY

    SciTech Connect

    Dandina N. Rao; Subhash C. Ayirala; Madhav M. Kulkarni; Amit P. Sharma

    2004-10-01

    This report describes the progress of the project ''Development and Optimization of Gas-Assisted Gravity Drainage (GAGD) Process for Improved Light Oil Recovery'' for the duration of the second project year (October 1, 2003--September 30, 2004). There are three main tasks in this research project. Task 1 is scaled physical model study of GAGD process. Task 2 is further development of vanishing interfacial tension (VIT) technique for miscibility determination. Task 3 is determination of multiphase displacement characteristics in reservoir rocks. In Section I, preliminary design of the scaled physical model using the dimensional similarity approach has been presented. Scaled experiments on the current physical model have been designed to investigate the effect of Bond and capillary numbers on GAGD oil recovery. Experimental plan to study the effect of spreading coefficient and reservoir heterogeneity has been presented. Results from the GAGD experiments to study the effect of operating mode, Bond number and capillary number on GAGD oil recovery have been reported. These experiments suggest that the type of the gas does not affect the performance of GAGD in immiscible mode. The cumulative oil recovery has been observed to vary exponentially with Bond and capillary numbers, for the experiments presented in this report. A predictive model using the bundle of capillary tube approach has been developed to predict the performance of free gravity drainage process. In Section II, a mechanistic Parachor model has been proposed for improved prediction of IFT as well as to characterize the mass transfer effects for miscibility development in reservoir crude oil-solvent systems. Sensitivity studies on model results indicate that provision of a single IFT measurement in the proposed model is sufficient for reasonable IFT predictions. An attempt has been made to correlate the exponent (n) in the mechanistic model with normalized solute compositions present in both fluid phases

  4. Response surface methodology for the modeling and optimization of oil-in-water emulsion separation using gas sparging assisted microfiltration.

    PubMed

    Fouladitajar, Amir; Zokaee Ashtiani, Farzin; Dabir, Bahram; Rezaei, Hamid; Valizadeh, Bardiya

    2015-02-01

    Response surface methodology (RSM) and central composite design (CCD) were used to develop models for optimization and modeling of a gas sparging assisted microfiltration of oil-in-water (o/w) emulsion. The effect of gas flow rate (Q G ), oil concentration (C oil ), transmembrane pressure (TMP), and liquid flow rate (Q L ) on the permeate flux and oil rejection were studied by RSM. Two sets of experiments were designed to investigate the effects of different gas-liquid two-phase flow regimes; low and high gas flow rates. Two separate RSM models were developed for each experimental set. The oil concentration and TMP were found to be the most significant factors influencing both permeate flux and rejection. Also, the interaction between these parameters was the most significant one. At low Q G , the more the gas flow rate, the higher the permeate flux; however, in the high gas flow rate region, higher Q G did not necessarily improve the permeate flux. In the case of rejection, gas and liquid flow rates were found to be insignificant. The optimum process conditions were found to be the following: Q G  = 1.0 (L/min), C oil  = 1,290 (mg/L), TMP = 1.58 (bar), and Q L  = 3.0 (L/min). Under these optimal conditions, maximum permeate flux and rejection (%) were 115.9 (L/m(2)h) and 81.1 %, respectively.

  5. DEVELOPMENT AND OPTIMIZATION OF GAS-ASSISTED GRAVITY DRAINAGE (GAGD) PROCESS FOR IMPROVED LIGHT OIL RECOVERY

    SciTech Connect

    Dandina N. Rao

    2003-10-01

    This is the first Annual Technical Progress Report being submitted to the U. S. Department of Energy on the work performed under the Cooperative Agreement DE-FC26-02NT15323. This report follows two other progress reports submitted to U.S. DOE during the first year of the project: The first in April 2003 for the project period from October 1, 2002 to March 31, 2003, and the second in July 2003 for the period April 1, 2003 to June 30, 2003. Although the present Annual Report covers the first year of the project from October 1, 2002 to September 30, 2003, its contents reflect mainly the work performed in the last quarter (July-September, 2003) since the work performed during the first three quarters has been reported in detail in the two earlier reports. The main objective of the project is to develop a new gas-injection enhanced oil recovery process to recover the oil trapped in reservoirs subsequent to primary and/or secondary recovery operations. The project is divided into three main tasks. Task 1 involves the design and development of a scaled physical model. Task 2 consists of further development of the vanishing interfacial tension (VIT) technique for miscibility determination. Task 3 involves the determination of multiphase displacement characteristics in reservoir rocks. Each technical progress report, including this one, reports on the progress made in each of these tasks during the reporting period. Section I covers the scaled physical model study. A survey of literature in related areas has been conducted. Test apparatus has been under construction throughout the reporting period. A bead-pack visual model, liquid injection system, and an image analysis system have been completed and used for preliminary experiments. Experimental runs with decane and paraffin oil have been conducted in the bead pack model. The results indicate the need for modifications in the apparatus, which are currently underway. A bundle of capillary tube model has been considered and

  6. The effect of gas assisted length on polymer melt extrusion based on the gas-assisted extrusion technique

    NASA Astrophysics Data System (ADS)

    Wan, B.; Ren, Z.; Liu, G. D.; Huang, X. Y.

    2017-02-01

    In this study, the gas-assisted technique was used into the process of polymer melt extrusion to overcome the extrudate swell problem. The gas length is an important factors in the gas-assisted extrusion technique. To ascertain the mechanism of the gas-assisted extrusion technique, and to determine the optimal gas length, the effect of gas length on the extrudate swell ratio of melt was numerically investigated. In finite element numerical simulation, PTT constitutive model and full slip boundary condition were used to achieve the gas-assisted mode. Compared with the traditional no gas-assisted extrusion, numerical results showed that the extrudate swell problem was well eliminated by the gas-assisted method. Moreover, the extrudate swell of melt decreased with the increasing of the gas length because the pressure and shear stress of melt were greatly decreased. Moreover, the flow velocity of melt is uniform at the die outlet.

  7. Improved conventional and microwave-assisted silylation protocols for simultaneous gas chromatographic determination of tocopherols and sterols: Method development and multi-response optimization.

    PubMed

    Poojary, Mahesha M; Passamonti, Paolo

    2016-12-09

    This paper reports on improved conventional thermal silylation (CTS) and microwave-assisted silylation (MAS) methods for simultaneous determination of tocopherols and sterols by gas chromatography. Reaction parameters in each of the methods developed were systematically optimized using a full factorial design followed by a central composite design. Initially, experimental conditions for CTS were optimized using a block heater. Further, a rapid MAS was developed and optimized. To understand microwave heating mechanisms, MAS was optimized by two distinct modes of microwave heating: temperature-controlled MAS and power-controlled MAS, using dedicated instruments where reaction temperature and microwave power level were controlled and monitored online. Developed methods: were compared with routine overnight derivatization. On a comprehensive level, while both CTS and MAS were found to be efficient derivatization techniques, MAS significantly reduced the reaction time. The optimal derivatization temperature and time for CTS found to be 55°C and 54min, while it was 87°C and 1.2min for temperature-controlled MAS. Further, a microwave power of 300W and a derivatization time 0.5min found to be optimal for power-controlled MAS. The use of an appropriate derivatization solvent, such as pyridine, was found to be critical for the successful determination. Catalysts, like potassium acetate and 4-dimethylaminopyridine, enhanced the efficiency slightly. The developed methods showed excellent analytical performance in terms of linearity, accuracy and precision.

  8. Determination of volatile components of green, black, oolong and white tea by optimized ultrasound-assisted extraction-dispersive liquid-liquid microextraction coupled with gas chromatography.

    PubMed

    Sereshti, Hassan; Samadi, Soheila; Jalali-Heravi, Mehdi

    2013-03-08

    Ultrasound assisted extraction (UAE) followed by dispersive liquid-liquid microextraction (DLLME) was used for extraction and preconcentration of volatile constituents of six tea plants. The preconcentrated compounds were analyzed by gas chromatography-mass spectrometry (GC-MS). Totally, 42 compounds were identified and caffeine was quantitatively determined. The main parameters (factors) of the extraction process were optimized by using a central composite design (CCD). Methanol and chloroform were selected as the extraction solvent and preconcentration solvent, respectively .The optimal conditions were obtained as 21 in for sonication time; 32°C for temperature; 27 L for volume of extraction solvent and 7.4% for salt concentration (NaCl/H(2)O). The determination coefficient (R(2)) was 0.9988. The relative standard deviation (RSD %) was 4.8 (n=5), and the enhancement factors (EFs) were 4.0-42.6.

  9. Optimize acid gas removal

    SciTech Connect

    Nicholas, D.M.; Wilkins, J.T.

    1983-09-01

    Innovative design of physical solvent plants for acid gas removal can materially reduce both installation and operating costs. A review of the design considerations for one physical solvent process (Selexol) points to numerous arrangements for potential improvement. These are evaluated for a specific case in four combinations that identify an optimum for the case in question but, more importantly, illustrate the mechanism for use for such optimization elsewhere.

  10. Determination of gas length for gas-assisted extrusion forming of polymer melt

    NASA Astrophysics Data System (ADS)

    Ren, Z.; Huang, X. Y.

    2017-02-01

    To determine the optimal gas length for the gas-assisted etrusion forming of melt, numerical investigations about the gas length on the extrudate swell of melt were performed by using the finite element method. Meanwhile, the geometric model of gas-assistd extrusion forming was established. The full slip boundary condition was used as the gas-assisted condition. Numerical results show that the gas length should be shortened with increasing of the inlet volumme flow rate of melt. In addition, under the given inlet volume flow rate of melt, the extrudate swell ratio, X velocity and shear stress of melt greatly decreases with increasing the gas length. Accroding to the numerical results and experiences reported past time, under the inlet volume flow rate of 0.5cm3/s, the optimal gas lenth of gas-assisted extrusion forming is about 10mm.

  11. Optimized ultrasonic assisted extraction-dispersive liquid-liquid microextraction coupled with gas chromatography for determination of essential oil of Oliveria decumbens Vent.

    PubMed

    Sereshti, Hassan; Izadmanesh, Yahya; Samadi, Soheila

    2011-07-22

    Ultrasonic assisted extraction-dispersive liquid-liquid microextraction (UAE-DLLME) coupled with gas chromatography (GC) was applied for extraction and determination of essential oil constituents of the plant Oliveria decumbens Vent. Scanning electron microscopy (SEM) was used to see the effect of ultrasonic radiation on the extraction efficiency. By comparison with hydrodistillation, UAE-DLLME is fast, low cost, simple, efficient and consuming small amount of plant materials (∼1.0 g). The effects of various parameters such as temperature, ultrasonication time, volume of disperser and extraction solvents were investigated by a full factorial design to identify significant variables and their interactions. The results demonstrated that temperature and ultrasonication time had no considerable effect on the results. In the next step, a central composite design (CCD) was performed to obtain the optimum levels of significant parameters. The obtained optimal conditions were: 0.45 mL for disperser solvent (acetonitrile) and 94.84 μL for extraction solvent (chlorobenzene). The limits of detection (LODs), linear dynamic range and determination coefficients (R(2)) were 0.2-29 ng mL(-1), 1-2100 ng mL(-1) and 0.995-0.998, respectively. The main components of the essential oil were: thymol (47.06%), carvacrol (23.31%), gamma-terpinene (18.94%), p-cymene (8.71%), limonene (0.76%) and myristicin (0.63%).

  12. Optimized entanglement-assisted quantum error correction

    SciTech Connect

    Taghavi, Soraya; Brun, Todd A.; Lidar, Daniel A.

    2010-10-15

    Using convex optimization, we propose entanglement-assisted quantum error-correction procedures that are optimized for given noise channels. We demonstrate through numerical examples that such an optimized error-correction method achieves higher channel fidelities than existing methods. This improved performance, which leads to perfect error correction for a larger class of error channels, is interpreted in at least some cases by quantum teleportation, but for general channels this interpretation does not hold.

  13. Optimization of ultrasonic-assisted extraction of 3-monochloropropane-1,2-diol (MCPD) and analysis of its esters from edible oils by gas chromatography-mass spectrometry.

    PubMed

    Ma, Fei; Li, Peiwu; Matthäus, Bertrand; Zhang, Wen; Zhang, Qi

    2012-09-01

    In this paper, ultrasonic-assisted extraction of 3-chloropropane-1,2-diol and its esters from edible oils was studied with isotope dilution GC-MS. Effects of several experimental parameters, such as types and concentrations of extracting solvent, ratios of liquid to material, extraction temperature, time of ultrasonic treatment on the extraction efficiency of 3-chloropropane-1,2-diol and its esters from edible oils and sample preparation for calibration were compared and optimized. The optimal extraction conditions were suggested as 66 mg oil sample in mixture of 0.5 mL MTBE/ethyl acetate (20% v/v) and 0.5 mL of sulfuric acid/n-propanol (0.3% v/v), being extracted for 30 min at 45°C under ultrasonic irradiation. Good linearity was gained in the range of 0.020-5.000 μg/g with the limit of detection (LOD) of 0.006 μg/g (S/N = 3) and the limit of quantification (LOQ) of 0.020 μg/g (S/N = 10). The recoveries at five spiked concentrations were ranged from 91.9 to 109.3% with RSD less than 9.4%. The method was successfully applied to the determination of 3-chloropropane-1,2-diol and its esters amounts in rapeseed, sesame, peanut, camellia, and soybean oils.

  14. Natural gas-assisted steam electrolyzer

    DOEpatents

    Pham, Ai-Quoc; Wallman, P. Henrik; Glass, Robert S.

    2000-01-01

    An efficient method of producing hydrogen by high temperature steam electrolysis that will lower the electricity consumption to an estimated 65 percent lower than has been achievable with previous steam electrolyzer systems. This is accomplished with a natural gas-assisted steam electrolyzer, which significantly reduces the electricity consumption. Since this natural gas-assisted steam electrolyzer replaces one unit of electrical energy by one unit of energy content in natural gas at one-quarter the cost, the hydrogen production cost will be significantly reduced. Also, it is possible to vary the ratio between the electricity and the natural gas supplied to the system in response to fluctuations in relative prices for these two energy sources. In one approach an appropriate catalyst on the anode side of the electrolyzer will promote the partial oxidation of natural gas to CO and hydrogen, called Syn-Gas, and the CO can also be shifted to CO.sub.2 to give additional hydrogen. In another approach the natural gas is used in the anode side of the electrolyzer to burn out the oxygen resulting from electrolysis, thus reducing or eliminating the potential difference across the electrolyzer membrane.

  15. Optimization of ultrasonic-assisted extraction for determination of polycyclic aromatic hydrocarbons in biochar-based fertilizer by gas chromatography-mass spectrometry.

    PubMed

    Chen, Ping; Sun, Mingxing; Zhu, Zhixiu; Zhang, Jidong; Shen, Guoqing

    2015-08-01

    Application of biochar-based fertilizers is increasingly being considered for its potential agronomic and environmental benefits. However, biochar may contain residues of polycyclic aromatic hydrocarbons (PAHs) as a result of its production by pyrolysis. The strong adsorption of PAHs to biochar makes extraction and analysis of biochar-based fertilizers difficult. This study optimizes the extraction of PAHs in biochar-based fertilizer samples by using an ultrasonic bath for quantification by gas chromatography-mass spectrometry. Among 12 solvents, acetone-cyclohexane (1:1) mixture was selected as the optimum solvent for extraction. Three variables affecting the extraction were studied by Box-Behnken design. The optimum conditions were 57 °C extraction temperature, 81 min extraction time, and two extraction cycles, which were validated by assessing the linearity of analysis, LOD, LOQ, recovery, and levels of PAHs in real biochar-based fertilizer samples. Results revealed that the 16 U.S. EPA PAHs had good linearity, with squared correlation coefficients greater than 0.99. LODs were low, ranging from 2.2 ng g(-1) (acenaphthene) to 23.55 ng g(-1) (indeno[1,2,3-cd]perylene), and LOQs varied from 7.51 ng g(-1) to 78.49 ng g(-1). The recoveries of 16 individual PAHs from the three biochar-based fertilizer samples were 81.8-109.4 %. Graphical Abstract Use of RSM to optimize UAE for extraction of the PAHs in biochar-based fertilizer.

  16. Offshore oil - growing optimism with gas

    SciTech Connect

    Pagano, S.S.

    1994-01-01

    The gas-rich Gulf of Mexico is on the rebound and there's growing optimism business conditions will continue to improve in 1994. Environmental regulations, such as the Clean Air Act and the Oil Pollution Act of 1990, are having a significant impact on oil an gas drilling and production. The Clean Air Act has increased the use of natural gas, which is helping bolster gas consumption from the Gulf of Mexico's reserves. In late December 1993, the Clinton administration unveiled its long-awaited gas and oil initiative aimed at boosting markets for domestic natural gas and oil while developing a long-term strategy to reduce the nation's dependence on imported energy. This article examines the political and economic issues of concern to the oil and gas industry, and how international competition affects development in the Gulf.

  17. Gentle protein ionization assisted by high-velocity gas flow.

    PubMed

    Yang, Pengxiang; Cooks, R Graham; Ouyang, Zheng; Hawkridge, Adam M; Muddiman, David C

    2005-10-01

    Gentle protein electrospray ionization is achieved using the high-velocity gas flow of an air amplifier to improve desolvation in conventional ESI and generate intact folded protein ions in the gas phase. Comparisons are made between the ESI spectra of a number of model proteins, including ubiquitin, cytochrome c, lysozyme, and myoglobin, over a range of pH values under optimized conditions, with and without using an air amplifier to achieve high-velocity gas flow. Previously reported increased ion signals are confirmed. In addition, the peaks recorded using the air amplifier are shown to be narrower, corresponding to more complete desolvation. Significant changes in the charge-state distribution also are observed, with a shift to lower charge state at high-velocity flow. The relationship between the observed charge-state distribution and protein conformation was explored by comparing the charge-state shifts and the distributions of charge states for proteins that are or are not stable in their native conformations in low pH solutions. The data suggest retention of native or nativelike protein conformations using the air amplifier in all cases examined. This is explained by a mechanism in which the air amplifier rapidly creates small droplets from the original large ESI droplets and these microdroplets then desolvate without a significant decrease in pH, resulting in retention of the folded protein conformations. Furthermore, the holoform of ionized myoglobin is visible at pH 3.5, a much lower value than the minimum needed to see this form in conventional ESI. These results provide evidence for the importance of the conditions used in the desolvation process for the preservation of the protein conformation and suggest that the conditions achieved when using high-velocity gas flows to assist droplet evaporation and ion desolvation are much gentler than those in conventional ESI experiments.

  18. OPTIMIZING SYNTHESIS GAS YIELD FROM THE CROSS ...

    EPA Pesticide Factsheets

    Symposium Paper Biomass can be gasified to yield synthesis gas, tars, and ash. The process is governed by a number of parameters such as the temperature of the gasifying medium (in this case), and the moisture content of the feedstock. Synthesis gas from gasifying wood pellets was collected and analyzed as a function of inlet air temperature and feedstock moisture content. The air was introduced at temperatures ranging from 630 to 730 °C and the moisture content of the feedstock ranged from 8 to 20%. The data collected was used to establish the relationship between the outcome of gasification and these two parameters, and then to determine optimal operating parameters for maximizing the fuel value (maximizing the concentrations of flammable gases in the synthesis gas) while minimizing the production of gasification tars.

  19. [Computer-assisted optimization of dialysis treatment].

    PubMed

    Rieck, B; Reinschke, P

    1988-01-01

    In some dialysis centers of the GDR personal computers are introduced step by step. There are two main areas in the use of computers in dialysis centers: data management systems and computer-assisted individualization of dialysis. Type and size of data processing are the result of the specific information process in a dialysis center and the presence of a long-term constantly group of patients along with a stereotypical amount of data. In the mathematical modelling of dialysis it is possible to adapt the standard dialysis to each patient.

  20. Performance Calculations and Optimization of Gas Guns

    DTIC Science & Technology

    1981-05-01

    Covolume . D Inside diameter. E Internal energy of driver gas in control volume. g Initial (maximum) projectile acceleration. G Mass of driver gas...Degrees of freedom of driver gas. P Gas pressure . R Gas constant. t Time. T Gas temperature. u Gas Velocity. u p Projectile Mach number based on initial...guns operating at low- pressures are used. These guns are located in fixed length rooms. The characteristics of the guns must be known to configure

  1. Optimization and analysis of gas turbine engine blades

    NASA Technical Reports Server (NTRS)

    Vandenbrink, D. J.; Hopkins, D. A.

    1987-01-01

    A gas turbine engine blade design is optimized using STAEBL. To validate the STAEBL analysis, the optimized blade design is analyzed using MARC, MHOST and BEST3D. The results show good agreement between STAEBL, MARC, and MHOST. The conclusion is that STAEBL can be used to optimize an engine blade design.

  2. Panorama parking assistant system with improved particle swarm optimization method

    NASA Astrophysics Data System (ADS)

    Cheng, Ruzhong; Zhao, Yong; Li, Zhichao; Jiang, Weigang; Wang, Xin'an; Xu, Yong

    2013-10-01

    A panorama parking assistant system (PPAS) for the automotive aftermarket together with a practical improved particle swarm optimization method (IPSO) are proposed in this paper. In the PPAS system, four fisheye cameras are installed in the vehicle with different views, and four channels of video frames captured by the cameras are processed as a 360-deg top-view image around the vehicle. Besides the embedded design of PPAS, the key problem for image distortion correction and mosaicking is the efficiency of parameter optimization in the process of camera calibration. In order to address this problem, an IPSO method is proposed. Compared with other parameter optimization methods, the proposed method allows a certain range of dynamic change for the intrinsic and extrinsic parameters, and can exploit only one reference image to complete all of the optimization; therefore, the efficiency of the whole camera calibration is increased. The PPAS is commercially available, and the IPSO method is a highly practical way to increase the efficiency of the installation and the calibration of PPAS in automobile 4S shops.

  3. Assisted closed-loop optimization of SSVEP-BCI efficiency

    PubMed Central

    Fernandez-Vargas, Jacobo; Pfaff, Hanns U.; Rodríguez, Francisco B.; Varona, Pablo

    2012-01-01

    We designed a novel assisted closed-loop optimization protocol to improve the efficiency of brain-computer interfaces (BCI) based on steady state visually evoked potentials (SSVEP). In traditional paradigms, the control over the BCI-performance completely depends on the subjects' ability to learn from the given feedback cues. By contrast, in the proposed protocol both the subject and the machine share information and control over the BCI goal. Generally, the innovative assistance consists in the delivery of online information together with the online adaptation of BCI stimuli properties. In our case, this adaptive optimization process is realized by (1) a closed-loop search for the best set of SSVEP flicker frequencies and (2) feedback of actual SSVEP magnitudes to both the subject and the machine. These closed-loop interactions between subject and machine are evaluated in real-time by continuous measurement of their efficiencies, which are used as online criteria to adapt the BCI control parameters. The proposed protocol aims to compensate for variability in possibly unknown subjects' state and trait dimensions. In a study with N = 18 subjects, we found significant evidence that our protocol outperformed classic SSVEP-BCI control paradigms. Evidence is presented that it takes indeed into account interindividual variabilities: e.g., under the new protocol, baseline resting state EEG measures predict subjects' BCI performances. This paper illustrates the promising potential of assisted closed-loop protocols in BCI systems. Probably their applicability might be expanded to innovative uses, e.g., as possible new diagnostic/therapeutic tools for clinical contexts and as new paradigms for basic research. PMID:23443214

  4. Optimization of buffer gas pressure for Rb atomic magnetometer

    NASA Astrophysics Data System (ADS)

    Chen, Chang; Liu, Xiaohu; Qu, Tianliang; Yang, Kaiyong

    2015-08-01

    The optimization of buffer gas pressure is very important to improve the performance of the rubidium (Rb) atomic magnetometer. In this paper we briefly introduce the basic principle and the experimental method of the rubidium magnetometer based on Faraday rotation effect, and describe the factors affecting the magnetometer sensitivity, then analyze and summarize the mechanism of the influence of spin-exchange, spin-destruction collisions, radiation trapping and the spin diffusion on spin relaxation of Rb atoms. Based on this, the relationship between the rubidium magnetometer sensitivity, the spin relaxation rate and the gas chamber conditions (buffer gas pressure, the bubble radius, measuring temperature) is established. Doing calculations by the simulation software, how the magnetometer sensitivity and the relaxation rate vary with the gas chamber conditions can be seen; finally, the optimal values of the buffer gas pressure under certain gas chamber conditions are obtained. The work is significant for the engineering development of rubidium magnetometer.

  5. Performance optimization of water-jet assisted underwater laser cutting of AISI 304 stainless steel sheet

    NASA Astrophysics Data System (ADS)

    Mullick, Suvradip; Madhukar, Yuvraj K.; Roy, Subhransu; Nath, Ashish K.

    2016-08-01

    Recent development of water-jet assisted underwater laser cutting has shown some advantages over the gas assisted underwater laser cutting, as it produces much less turbulence, gas bubble and aerosols, resulting in a more gentle process. However, this process has relatively low efficiency due to different losses in water. Scattering is reported to be a dominant loss mechanism, which depends on the growth of vapor layer at cut front and its removal by water-jet. Present study reports improvement in process efficiency by reducing the scattering loss using modulated laser power. Judicious control of laser pulse on- and off-time could improve process efficiency through restricting the vapor growth and its effective removal by water-jet within the laser on- and off-time, respectively. Effects of average laser power, duty cycle and modulation frequency on specific energy are studied to get an operating zone for maximum efficiency. Next, the variation in laser cut quality with different process parameters are studied within this operating zone using Design of experiment (DOE). Response surface methodology (RSM) is used by implementing three level Box-Behnken design to optimize the variation in cut quality, and to find out the optimal process parameters for desired quality. Various phenomena and material removal mechanism involved in this process are also discussed.

  6. Optimization of wastewater treatment plant operation for greenhouse gas mitigation.

    PubMed

    Kim, Dongwook; Bowen, James D; Ozelkan, Ertunga C

    2015-11-01

    This study deals with the determination of optimal operation of a wastewater treatment system for minimizing greenhouse gas emissions, operating costs, and pollution loads in the effluent. To do this, an integrated performance index that includes three objectives was established to assess system performance. The ASMN_G model was used to perform system optimization aimed at determining a set of operational parameters that can satisfy three different objectives. The complex nonlinear optimization problem was simulated using the Nelder-Mead Simplex optimization algorithm. A sensitivity analysis was performed to identify influential operational parameters on system performance. The results obtained from the optimization simulations for six scenarios demonstrated that there are apparent trade-offs among the three conflicting objectives. The best optimized system simultaneously reduced greenhouse gas emissions by 31%, reduced operating cost by 11%, and improved effluent quality by 2% compared to the base case operation.

  7. Naturally fractured tight gas reservoir detection optimization

    SciTech Connect

    1998-11-30

    The goal of the work this quarter has been to partition and high-grade the Greater Green River basin for exploration efforts in the Upper Cretaceous tight gas play and to initiate resource assessment of the basin. The work plan for the quarter of July 1-September 30, 1998 comprised three tasks: (1) Refining the exploration process for deep, naturally fractured gas reservoirs; (2) Partitioning of the basin based on structure and areas of overpressure; (3) Examination of the Kinney and Canyon Creek fields with respect to the Cretaceous tight gas play and initiation of the resource assessment of the Vermilion sub-basin partition (which contains these two fields); and (4) Initiation analysis of the Deep Green River Partition with respect to the Stratos well and assessment of the resource in the partition.

  8. Naturally fractured tight gas reservoir detection optimization

    SciTech Connect

    1999-06-01

    Building upon the partitioning of the Greater Green River Basin (GGRB) that was conducted last quarter, the goal of the work this quarter has been to conclude evaluation of the Stratos well and the prototypical Green River Deep partition, and perform the fill resource evaluation of the Upper Cretaceous tight gas play, with the goal of defining target areas of enhanced natural fracturing. The work plan for the quarter of November 1-December 31, 1998 comprised four tasks: (1) Evaluation of the Green River Deep partition and the Stratos well and examination of potential opportunity for expanding the use of E and P technology to low permeability, naturally fractured gas reservoirs, (2) Gas field studies, and (3) Resource analysis of the balance of the partitions.

  9. Topology optimization of a gas-turbine engine part

    NASA Astrophysics Data System (ADS)

    Faskhutdinov, R. N.; Dubrovskaya, A. S.; Dongauzer, K. A.; Maksimov, P. V.; Trufanov, N. A.

    2017-02-01

    One of the key goals of aerospace industry is a reduction of the gas turbine engine weight. The solution of this task consists in the design of gas turbine engine components with reduced weight retaining their functional capabilities. Topology optimization of the part geometry leads to an efficient weight reduction. A complex geometry can be achieved in a single operation with the Selective Laser Melting technology. It should be noted that the complexity of structural features design does not affect the product cost in this case. Let us consider a step-by-step procedure of topology optimization by an example of a gas turbine engine part.

  10. Optimized Assistive Human-Robot Interaction Using Reinforcement Learning.

    PubMed

    Modares, Hamidreza; Ranatunga, Isura; Lewis, Frank L; Popa, Dan O

    2016-03-01

    An intelligent human-robot interaction (HRI) system with adjustable robot behavior is presented. The proposed HRI system assists the human operator to perform a given task with minimum workload demands and optimizes the overall human-robot system performance. Motivated by human factor studies, the presented control structure consists of two control loops. First, a robot-specific neuro-adaptive controller is designed in the inner loop to make the unknown nonlinear robot behave like a prescribed robot impedance model as perceived by a human operator. In contrast to existing neural network and adaptive impedance-based control methods, no information of the task performance or the prescribed robot impedance model parameters is required in the inner loop. Then, a task-specific outer-loop controller is designed to find the optimal parameters of the prescribed robot impedance model to adjust the robot's dynamics to the operator skills and minimize the tracking error. The outer loop includes the human operator, the robot, and the task performance details. The problem of finding the optimal parameters of the prescribed robot impedance model is transformed into a linear quadratic regulator (LQR) problem which minimizes the human effort and optimizes the closed-loop behavior of the HRI system for a given task. To obviate the requirement of the knowledge of the human model, integral reinforcement learning is used to solve the given LQR problem. Simulation results on an x - y table and a robot arm, and experimental implementation results on a PR2 robot confirm the suitability of the proposed method.

  11. Optimizing nanoporous materials for gas storage.

    PubMed

    Simon, Cory M; Kim, Jihan; Lin, Li-Chiang; Martin, Richard L; Haranczyk, Maciej; Smit, Berend

    2014-03-28

    In this work, we address the question of which thermodynamic factors determine the deliverable capacity of methane in nanoporous materials. The deliverable capacity is one of the key factors that determines the performance of a material for methane storage in automotive fuel tanks. To obtain insights into how the molecular characteristics of a material are related to the deliverable capacity, we developed several statistical thermodynamic models. The predictions of these models are compared with the classical thermodynamics approach of Bhatia and Myers [Bhatia and Myers, Langmuir, 2005, 22, 1688] and with the results of molecular simulations in which we screen the International Zeolite Association (IZA) structure database and a hypothetical zeolite database of over 100,000 structures. Both the simulations and our models do not support the rule of thumb that, for methane storage, one should aim for an optimal heat of adsorption of 18.8 kJ mol(-1). Instead, our models show that one can identify an optimal heat of adsorption, but that this optimal heat of adsorption depends on the structure of the material and can range from 8 to 23 kJ mol(-1). The different models we have developed are aimed to determine how this optimal heat of adsorption is related to the molecular structure of the material.

  12. Optimizing the response from a passively controlled biventricular assist device.

    PubMed

    Gaddum, Nicholas Richard; Timms, Daniel L; Pearcy, Mark John

    2010-05-01

    Recent studies into rotary biventricular support have indicated that inadequate left/right flow balancing may lead to vascular congestion and/or ventricular suckdown. The implementation of a passive controller that automatically adjusts left/right flow during total and partial cardiac support would improve physiological interaction. This has encouraged the development of a biventricular assist device (BiVAD) prototype that achieves passive control of the two rotary pumps' hydraulic output by way of a nonrotating double pressure plate configuration, the hub, suspended between the ventricular assist device (VAD) impellers. Fluctuations in either the VAD's inlet or outlet pressure will cause the hub to translate, and in doing so, affect each pump's hydraulic outputs. In order to achieve partial support, the floating assembly needed to respond to pathologic blood pressure signals while being insensitive to residual ventricular function. An incorporated mechanical spring-mass-damper assembly affects the passive response to optimize the dynamic interaction between the prototype and the supported cardiovascular system. It was found that increasing the damping from a medium to a high level was effective in filtering out the higher frequency ventricular pressure signals, reducing a modified amplitude ratio by up to 72%. A spring response was also identified as being inherent in the passive response and was characterized as being highly nonlinear at the extremes of the floating assembly's translation range. The results from this study introduce a new means of BiVAD control as well as the characterization of a fully passive mechanical physiological controller.

  13. Naturally fractured tight gas reservoir detection optimization

    SciTech Connect

    Decker, D.

    1995-05-01

    Exploration strategies are needed to identify subtle basement features critical to locating fractured regions in advance of drilling in tight gas reservoirs. The Piceance Basin served as a demonstration site for an analysis utilizing aeromagnetic surveys, remote sensing, Landsat Thematic Mapper, and Side Looking Airborne Radar imagery for the basin and surrounding areas. Spatially detailed aeromagnetic maps were used to to interpret zones of basement structure.

  14. Naturally fractured tight gas reservoir detection optimization

    SciTech Connect

    1999-04-30

    In March, work continued on characterizing probabilities for determining natural fracturing associated with the GGRB for the Upper Cretaceous tight gas plays. Structural complexity, based on potential field data and remote sensing data was completed. A resource estimate for the Frontier and Mesa Verde play was also completed. Further, work was also conducted to determine threshold economics for the play based on limited current production in the plays in the Wamsutter Ridge area. These analyses culminated in a presentation at FETC on 24 March 1999 where quantified natural fracture domains, mapped on a partition basis, which establish ''sweet spot'' probability for natural fracturing, were reviewed. That presentation is reproduced here as Appendix 1. The work plan for the quarter of January 1, 1999--March 31, 1999 comprised five tasks: (1) Evaluation of the GGRB partitions for structural complexity that can be associated with natural fractures, (2) Continued resource analysis of the balance of the partitions to determine areas with higher relative gas richness, (3) Gas field studies, (4) Threshold resource economics to determine which partitions would be the most prospective, and (5) Examination of the area around the Table Rock 4H well.

  15. Optimization of the assisted bidirectional Glenn for single ventricle palliation

    NASA Astrophysics Data System (ADS)

    Marsden, Alison; Shang, Jessica; Esmaily-Moghadam, Mahdi; Figliola, Richard; Reinhartz, Olaf; Hsia, Tain-Yen

    2015-11-01

    For neonates with single ventricle physiology, a systemic-pulmonary shunt (e.g., a modified Blalock-Taussig shunt (mBTS)) is typically employed as an early-stage procedure in preparation for a later-stage bidirectional Glenn (BDG). Mortality rates with the mBTS are high, yet the BDG has poorer outcomes in neonates. The assisted bidirectional Glenn (ABG) augments the inadequate pulmonary flow associated with early BDG implementation in neonates through an additional shunt between the innominate artery and the superior vena cava (SVC). The shunt uses a nozzle to inject high-velocity flow to the SVC, elevating downstream pulmonary pressure. Previous simulations and animal studies verified feasibility and higher pulmonary flow rates. In numerical simulations, we explore shunt geometries and placements implanted into a 3D model of the aorta and pulmonary arteries, coupled with a lumped parameter network describing the remaining circulatory system. We seek an ABG shunt that optimizes hemodynamic variables such as pulmonary flow rate and oxygenation and constrains SVC pressure. The optimized ABG will be evaluated against the mBTS and the BDG in simulations and experiments. A successful implementation of the ABG would replace the mBTS and BDG procedures and reduce mortality rates. Burroughs Wellcome Fund, Leducq Foundation.

  16. Method for nonlinear optimization for gas tagging and other systems

    DOEpatents

    Chen, T.; Gross, K.C.; Wegerich, S.

    1998-01-06

    A method and system are disclosed for providing nuclear fuel rods with a configuration of isotopic gas tags. The method includes selecting a true location of a first gas tag node, selecting initial locations for the remaining n-1 nodes using target gas tag compositions, generating a set of random gene pools with L nodes, applying a Hopfield network for computing on energy, or cost, for each of the L gene pools and using selected constraints to establish minimum energy states to identify optimal gas tag nodes with each energy compared to a convergence threshold and then upon identifying the gas tag node continuing this procedure until establishing the next gas tag node until all remaining n nodes have been established. 6 figs.

  17. Method for nonlinear optimization for gas tagging and other systems

    DOEpatents

    Chen, Ting; Gross, Kenny C.; Wegerich, Stephan

    1998-01-01

    A method and system for providing nuclear fuel rods with a configuration of isotopic gas tags. The method includes selecting a true location of a first gas tag node, selecting initial locations for the remaining n-1 nodes using target gas tag compositions, generating a set of random gene pools with L nodes, applying a Hopfield network for computing on energy, or cost, for each of the L gene pools and using selected constraints to establish minimum energy states to identify optimal gas tag nodes with each energy compared to a convergence threshold and then upon identifying the gas tag node continuing this procedure until establishing the next gas tag node until all remaining n nodes have been established.

  18. Naturally fractured tight gas reservoir detection optimization

    SciTech Connect

    1998-11-30

    The work plan for October 1, 1997 to September 30, 1998 consisted of investigation of a number of topical areas. These topical areas were reported in four quarterly status reports, which were submitted to DOE earlier. These topical areas are reviewed in this volume. The topical areas covered during the year were: (1) Development of preliminary tests of a production method for determining areas of natural fracturing. Advanced Resources has demonstrated that such a relationship exists in the southern Piceance basin tight gas play. Natural fracture clusters are genetically related to stress concentrations (also called stress perturbations) associated with local deformation such a faulting. The mechanical explanation of this phenomenon is that deformation generally initiates at regions where the local stress field is elevated beyond the regional. (2) Regional structural and geologic analysis of the Greater Green River Basin (GGRB). Application of techniques developed and demonstrated during earlier phases of the project for sweet-spot delineation were demonstrated in a relatively new and underexplored play: tight gas from continuous-typeUpper Cretaceous reservoirs of the Greater Green River Basin (GGRB). The effort included data acquisition/processing, base map generation, geophysical and remote sensing analysis and the integration of these data and analyses. (3) Examination of the Table Rock field area in the northern Washakie Basin of the Greater Green River Basin. This effort was performed in support of Union Pacific Resources- and DOE-planned horizontal drilling efforts. The effort comprised acquisition of necessary seismic data and depth-conversion, mapping of major fault geometry, and analysis of displacement vectors, and the development of the natural fracture prediction. (4) Greater Green River Basin Partitioning. Building on fundamental fracture characterization work and prior work performed under this contract, namely structural analysis using satellite and

  19. Mixed integer simulation optimization for optimal hydraulic fracturing and production of shale gas fields

    NASA Astrophysics Data System (ADS)

    Li, J. C.; Gong, B.; Wang, H. G.

    2016-08-01

    Optimal development of shale gas fields involves designing a most productive fracturing network for hydraulic stimulation processes and operating wells appropriately throughout the production time. A hydraulic fracturing network design-determining well placement, number of fracturing stages, and fracture lengths-is defined by specifying a set of integer ordered blocks to drill wells and create fractures in a discrete shale gas reservoir model. The well control variables such as bottom hole pressures or production rates for well operations are real valued. Shale gas development problems, therefore, can be mathematically formulated with mixed-integer optimization models. A shale gas reservoir simulator is used to evaluate the production performance for a hydraulic fracturing and well control plan. To find the optimal fracturing design and well operation is challenging because the problem is a mixed integer optimization problem and entails computationally expensive reservoir simulation. A dynamic simplex interpolation-based alternate subspace (DSIAS) search method is applied for mixed integer optimization problems associated with shale gas development projects. The optimization performance is demonstrated with the example case of the development of the Barnett Shale field. The optimization results of DSIAS are compared with those of a pattern search algorithm.

  20. West European economic security and international natural gas trade: optimal portfolios of gas imports

    SciTech Connect

    Greer, B.I.

    1985-01-01

    In 1981 the dependence of Western Europe on the Soviet Union for natural gas imports became a major issue in the debate over the European involvement in the Urengoi natural gas project. This analysis addresses the question spawned by this debate: how should West Europe diversify its natural gas imports to achieve the greatest security for its economy. The analysis presents a summary of the policy and institutional background of this Western European gas market, explains the nature of European gas markets, and establishes the relationship, between contract structure and economic vulnerability. By characterizing Western Europe's gas import problem as a portfolio decision, the analysis develops a simple static model that articulates the relationship between the cost of gas imports and commensurate risk. Using the portfolio framework, the analysis develops a dynamic model to characterize the intertemporal tradeoffs that are characteristic of a depletable resource in the optimal portfolio selection. An optimal control formulation provides insights that generalize the static portfolio model. Both the static and dynamic formulations provide the basis of computational models that produce empirical estimates of optimal natural gas import portfolios for Western Europe.

  1. Laser-assisted focused He+ ion beam induced etching with and without XeF2 gas assist

    DOE PAGES

    Stanford, Michael G.; Mahady, Kyle; Lewis, Brett B.; ...

    2016-10-04

    Focused helium ion (He+) milling has been demonstrated as a high-resolution nanopatterning technique; however, it can be limited by its low sputter yield as well as the introduction of undesired subsurface damage. Here, we introduce pulsed laser- and gas-assisted processes to enhance the material removal rate and patterning fidelity. A pulsed laser-assisted He+ milling process is shown to enable high-resolution milling of titanium while reducing subsurface damage in situ. Gas-assisted focused ion beam induced etching (FIBIE) of Ti is also demonstrated in which the XeF2 precursor provides a chemical assist for enhanced material removal rate. In conclusion, a pulsed laser-assistedmore » and gas-assisted FIBIE process is shown to increase the etch yield by ~9× relative to the pure He+ sputtering process. These He+ induced nanopatterning techniques improve material removal rate, in comparison to standard He+ sputtering, while simultaneously decreasing subsurface damage, thus extending the applicability of the He+ probe as a nanopattering tool.« less

  2. Sensitivity and optimization analyses of the ``ACOGAS`` gas conditioning plant

    SciTech Connect

    Ochoa, D.; Cardenas, A.R.

    1995-11-01

    ACOGAS is a gas dew point control plant (water and hydrocarbons), operated by Lagoven S.A., a subsidiary of Petroleos de Venezuela S.A. (PDVSA). The ACOGAS plant located in Jusepin, Eastern Venezuela, produces stabilized condensate from an inlet gas stream which is a mixture of different gravity gases obtained by separation and compression from various oil production fields in the area. Sensitivity and optimization analyses of the plant and the stabilizer tower were carried out to evaluate the effects of: plant capacity reductions during shutdowns of some unspared systems of the plant; composition changes from original design basis; segregation of the lean gas currents from the inlet gas stream, reducing total flow but increasing GPM (C{sub 3}{sup +}) content; and incorporating condensate from the upstream compression processes in the inlet gas stream. It is shown that significant increases of stabilized condensate production could be obtained, while maintaining the quality for the condensate and lean residual gas within specifications, by various low cost modifications to the upstream processes and the stabilizer tower. Additionally, a change of the stabilizer tower valves could lower the minimum acceptable inlet flow, thereby increasing flexibility during shutdowns and low feed gas flows.

  3. Microwave-assisted derivatization: application to steroid profiling by gas chromatography/mass spectrometry.

    PubMed

    Casals, Gregori; Marcos, Josep; Pozo, Oscar J; Alcaraz, José; Martínez de Osaba, María Jesús; Jiménez, Wladimiro

    2014-06-01

    Gas chromatography-mass spectrometry (GC-MS) remains as the gold-standard technique for the study of the steroid metabolome. A main limitation is the need of performing a derivatization step since incubation with strong silylations agents for long periods of time (usually 16 h) is required for the derivatization of hindered hydroxyls present in some steroids of interest. In the present work, a rapid, simple and reproducible microwave-assisted derivatization method was developed. In the method, 36 steroids already treated with methoxyamine (2% in pyridine) were silylated with 50 μl of N-trimethylsilylimidazole by using microwave irradiation, and the formed methyloxime-trimethylsilyl derivatives were analyzed by GC-MS. Microwave power and derivatization time silylation conditions were optimized being the optimum conditions 600 W and 3 min respectively. In order to evaluate the usefulness of this technique, the urine steroid profiles for 20 healthy individuals were analyzed. The results of a comparison of microwave irradiation with the classical heating protocol showed similar derivatization yields, thus suggesting that microwave-assisted silylation is a valid tool for the rapid steroid metabolome study.

  4. Optimized replica gas estimation of absolute integrals and partition functions

    NASA Astrophysics Data System (ADS)

    Minh, David D. L.

    2010-09-01

    In contrast with most Monte Carlo integration algorithms, which are used to estimate ratios, the replica gas identities recently introduced by Adib enable the estimation of absolute integrals and partition functions using multiple copies of a system and normalized transition functions. Here, an optimized form is presented. After generalizing a replica gas identity with an arbitrary weighting function, we obtain a functional form that has the minimal asymptotic variance for samples from two replicas and is provably good for a larger number. This equation is demonstrated to improve the convergence of partition function estimates in a two-dimensional Ising model.

  5. Optimized replica gas estimation of absolute integrals and partition functions.

    SciTech Connect

    Minh, D.

    2010-01-01

    In contrast with most Monte Carlo integration algorithms, which are used to estimate ratios, the replica gas identities recently introduced by Adib enable the estimation of absolute integrals and partition functions using multiple copies of a system and normalized transition functions. Here, an optimized form is presented. After generalizing a replica gas identity with an arbitrary weighting function, we obtain a functional form that has the minimal asymptotic variance for samples from two replicas and is provably good for a larger number. This equation is demonstrated to improve the convergence of partition function estimates in a two-dimensional Ising model.

  6. A Novel Consensus-Based Particle Swarm Optimization-Assisted Trust-Tech Methodology for Large-Scale Global Optimization.

    PubMed

    Zhang, Yong-Feng; Chiang, Hsiao-Dong

    2016-06-20

    A novel three-stage methodology, termed the "consensus-based particle swarm optimization (PSO)-assisted Trust-Tech methodology," to find global optimal solutions for nonlinear optimization problems is presented. It is composed of Trust-Tech methods, consensus-based PSO, and local optimization methods that are integrated to compute a set of high-quality local optimal solutions that can contain the global optimal solution. The proposed methodology compares very favorably with several recently developed PSO algorithms based on a set of small-dimension benchmark optimization problems and 20 large-dimension test functions from the CEC 2010 competition. The analytical basis for the proposed methodology is also provided. Experimental results demonstrate that the proposed methodology can rapidly obtain high-quality optimal solutions that can contain the global optimal solution. The scalability of the proposed methodology is promising.

  7. Optimizing Dense Plasma Focus Neutron Yields with Fast Gas Jets

    NASA Astrophysics Data System (ADS)

    McMahon, Matthew; Kueny, Christopher; Stein, Elizabeth; Link, Anthony; Schmidt, Andrea

    2016-10-01

    We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high density jet models fast gas puffs which allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of the jet compared to the background fill increases we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration is explored. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  8. Optimal Discrete Event Supervisory Control of Aircraft Gas Turbine Engines

    NASA Technical Reports Server (NTRS)

    Litt, Jonathan (Technical Monitor); Ray, Asok

    2004-01-01

    This report presents an application of the recently developed theory of optimal Discrete Event Supervisory (DES) control that is based on a signed real measure of regular languages. The DES control techniques are validated on an aircraft gas turbine engine simulation test bed. The test bed is implemented on a networked computer system in which two computers operate in the client-server mode. Several DES controllers have been tested for engine performance and reliability.

  9. Optimal Energy Consumption Analysis of Natural Gas Pipeline

    PubMed Central

    Liu, Enbin; Li, Changjun; Yang, Yi

    2014-01-01

    There are many compressor stations along long-distance natural gas pipelines. Natural gas can be transported using different boot programs and import pressures, combined with temperature control parameters. Moreover, different transport methods have correspondingly different energy consumptions. At present, the operating parameters of many pipelines are determined empirically by dispatchers, resulting in high energy consumption. This practice does not abide by energy reduction policies. Therefore, based on a full understanding of the actual needs of pipeline companies, we introduce production unit consumption indicators to establish an objective function for achieving the goal of lowering energy consumption. By using a dynamic programming method for solving the model and preparing calculation software, we can ensure that the solution process is quick and efficient. Using established optimization methods, we analyzed the energy savings for the XQ gas pipeline. By optimizing the boot program, the import station pressure, and the temperature parameters, we achieved the optimal energy consumption. By comparison with the measured energy consumption, the pipeline now has the potential to reduce energy consumption by 11 to 16 percent. PMID:24955410

  10. Optimal energy consumption analysis of natural gas pipeline.

    PubMed

    Liu, Enbin; Li, Changjun; Yang, Yi

    2014-01-01

    There are many compressor stations along long-distance natural gas pipelines. Natural gas can be transported using different boot programs and import pressures, combined with temperature control parameters. Moreover, different transport methods have correspondingly different energy consumptions. At present, the operating parameters of many pipelines are determined empirically by dispatchers, resulting in high energy consumption. This practice does not abide by energy reduction policies. Therefore, based on a full understanding of the actual needs of pipeline companies, we introduce production unit consumption indicators to establish an objective function for achieving the goal of lowering energy consumption. By using a dynamic programming method for solving the model and preparing calculation software, we can ensure that the solution process is quick and efficient. Using established optimization methods, we analyzed the energy savings for the XQ gas pipeline. By optimizing the boot program, the import station pressure, and the temperature parameters, we achieved the optimal energy consumption. By comparison with the measured energy consumption, the pipeline now has the potential to reduce energy consumption by 11 to 16 percent.

  11. Performance analysis and optimization of power plants with gas turbines

    NASA Astrophysics Data System (ADS)

    Besharati-Givi, Maryam

    The gas turbine is one of the most important applications for power generation. The purpose of this research is performance analysis and optimization of power plants by using different design systems at different operation conditions. In this research, accurate efficiency calculation and finding optimum values of efficiency for design of chiller inlet cooling and blade cooled gas turbine are investigated. This research shows how it is possible to find the optimum design for different operation conditions, like ambient temperature, relative humidity, turbine inlet temperature, and compressor pressure ratio. The simulated designs include the chiller, with varied COP and fogging cooling for a compressor. In addition, the overall thermal efficiency is improved by adding some design systems like reheat and regenerative heating. The other goal of this research focuses on the blade-cooled gas turbine for higher turbine inlet temperature, and consequently, higher efficiency. New film cooling equations, along with changing film cooling effectiveness for optimum cooling air requirement at the first-stage blades, and an internal and trailing edge cooling for the second stage, are innovated for optimal efficiency calculation. This research sets the groundwork for using the optimum value of efficiency calculation, while using inlet cooling and blade cooling designs. In the final step, the designed systems in the gas cycles are combined with a steam cycle for performance improvement.

  12. Optimization of simultaneous tritium–radiocarbon internal gas proportional counting

    SciTech Connect

    Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.; Hoppe, E. W.; Mace, E. K.; Moran, J. J.; Overman, C. T.; Panisko, M. E.; Seifert, A.

    2016-03-01

    Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium counting efficiency while minimizing radiocarbon beta decay interference.

  13. Optimization of simultaneous tritium-radiocarbon internal gas proportional counting

    NASA Astrophysics Data System (ADS)

    Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.; Hoppe, E. W.; Mace, E. K.; Moran, J. J.; Overman, C. T.; Panisko, M. E.; Seifert, A.

    2016-03-01

    Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a natural methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium-counting efficiency while minimizing radiocarbon beta-decay interference.

  14. Design Optimization of Gas Generator Hybrid Propulsion Boosters

    NASA Technical Reports Server (NTRS)

    Weldon, Vincent; Phillips, Dwight; Fink, Larry

    1990-01-01

    A methodology used in support of a study for NASA/MSFC to optimize the design of gas generator hybrid propulsion booster for uprating the National Space Transportation System (NSTS) is presented. The objective was to compare alternative configurations for this booster approach, optimizing each candidate concept on different bases, in order to develop data for a trade table on which a final decision was based. The methodology is capable of processing a large number of independent and dependent variables, adjusting the overall subsystems characteristics to arrive at a best compromise integrated design to meet various specific optimization criteria subject to selected constraints. For each system considered, a detailed weight statement was generated along with preliminary cost and reliability estimates.

  15. Kinetics in Gas Mixtures for Problem of Plasma Assisted Combustion

    DTIC Science & Technology

    2010-05-01

    exothermal chemical hydrocarbon oxidation process, and (iii) subsequent thermal ignition. The role of gas temperature increase in the experiments on...the nonequilibrium plasma, (ii) chemical reactions of hydrocarbon oxidation with participa- tion of O atoms and gas heating due to net exothermal ...autoignition) the ignition delay de- pends upon the rate of the dissociation reaction which is endothermic . Generally the induction delay time is greatly

  16. Optimization of Gas Metal Arc Welding Process Parameters

    NASA Astrophysics Data System (ADS)

    Kumar, Amit; Khurana, M. K.; Yadav, Pradeep K.

    2016-09-01

    This study presents the application of Taguchi method combined with grey relational analysis to optimize the process parameters of gas metal arc welding (GMAW) of AISI 1020 carbon steels for multiple quality characteristics (bead width, bead height, weld penetration and heat affected zone). An orthogonal array of L9 has been implemented to fabrication of joints. The experiments have been conducted according to the combination of voltage (V), current (A) and welding speed (Ws). The results revealed that the welding speed is most significant process parameter. By analyzing the grey relational grades, optimal parameters are obtained and significant factors are known using ANOVA analysis. The welding parameters such as speed, welding current and voltage have been optimized for material AISI 1020 using GMAW process. To fortify the robustness of experimental design, a confirmation test was performed at selected optimal process parameter setting. Observations from this method may be useful for automotive sub-assemblies, shipbuilding and vessel fabricators and operators to obtain optimal welding conditions.

  17. Optimizing Geothermal Drilling: Oil and Gas Technology Transfer

    SciTech Connect

    Denninger, Kate; Eustes, Alfred; Visser, Charles; Baker, Walt; Bolton, Dan; Bell, Jason; Bell, Sean; Jacobs, Amelia; Nagandran, Uneshddarann; Tilley, Mitch; Quick, Ralph

    2015-09-02

    There is a significant amount of financial risk associated with geothermal drilling. This study of drilling operations seeks opportunities to improve upon current practices and technologies. The scope of this study included analyzing 21 geothermal wells and 21 oil and gas wells. The goal was to determine a 'Perfect Well' using historical data to compare the best oil and gas well to the best geothermal well. Unfortunately, limitations encountered in the study included missing data (bit records, mud information, etc.) and poor data collection practices An online software database was used to format drilling data to IADC coded daily drilling reports and generate figures for analysis. Six major issues have been found in geothermal drilling operations. These problems include lost circulation, rig/ equipment selection, cementing, penetration rate, drilling program, and time management. As a result of these issues, geothermal drilling averaged 56.4 days longer than drilling comparable oil and gas wells in the wells in this study. Roughly $13.9 million was spent on non-productive time in the 21 geothermal wells, compared with only $1.3 million in the oil and gas wells, assuming a cost of $50,000 per day. Comparable events such as drilling the same sized hole, tripping in/out, cementing, and running the same size casing took substantially less time in the oil and gas wells. Geothermal wells were drilled using older and/or less advanced technology to depths less than 10,000 feet, while oil and gas wells reached 12,500 feet faster with purpose built rigs. A new approach is now underway that will optimize drilling programs throughout the drilling industry using Mechanical Specific Energy (MSE) as a tool to realize efficient drilling processes. Potential improvements for current geothermal operations are: the use of electronic records, real time services, and official glossary terms to describe rig operations, and advanced drilling rigs/technology.

  18. Optimizing Computer Assisted Instruction By Applying Principles of Learning Theory.

    ERIC Educational Resources Information Center

    Edwards, Thomas O.

    The development of learning theory and its application to computer-assisted instruction (CAI) are described. Among the early theoretical constructs thought to be important are E. L. Thorndike's concept of learning connectisms, Neal Miller's theory of motivation, and B. F. Skinner's theory of operant conditioning. Early devices incorporating those…

  19. Gas-Assisted Capture of the Irregular Satellites of Jupiter

    NASA Astrophysics Data System (ADS)

    Cuk, M.; Burns, J. A.

    2001-11-01

    Recent discoveries of ``irregular'' satellites about the giant planets have dramatically increased their number such that systematic studies of their origin can begin. Since irregulars move along large, inclined and eccentric orbits, capture from circumsolar orbit is usually suspected (Franklin and Colombo 1971, Heppenheimer and Porco 1977). Because permanent capture is not possible in a strictly gravitational three-body problem, a dissipative mechanism is needed. Many assume that gas drag by protojovian nebula led to their capture (cf. Pollack et al. 1979). We numerically simulate the gas-aided capture of a planetesimal by Jupiter. The distribution and velocity of gas come from hydrocode simulations (Lubow et al. 1999). In our simple replication of their model, gas is assumed to follow gravitational trajectories, except at the shockwave fronts (taken from Lubow et al.) which the gas is forbidden to cross. The planetesimal's motion is integrated using a mixture of modern and traditional techniques. We employ a symplectic integration algorithm (Malhotra 1994) within the circumsolar and circumjovian disks. In the transitional region we used a fourth-order Runge-Kutta integrator expressed in rotating coordinates. The method's timesteps are independent of the presence of the gas. Subsequent orbital evolution is handled in a symplectic way, thus avoiding ``fake captures'' due to energy leakage owing to integration errors. By incorporating more sophisticated models of protoJupiter's environs, we hope to refine the nebular models and/or to elucidate the capture process. Preliminary results indicate that the parent body of the prograde cluster of Jovian irregulars (Himalia's group) may have originated from the Hilda region, at around 4 AU from the Sun. This is consistent with the taxonomical types of the cluster members (Sykes et al. 2000) being similar to those of Hildas that are close in size to Himalia (Dahlgren and Lagerkvist 1995).

  20. Optimizing automated gas turbine fault detection using statistical pattern recognition

    NASA Astrophysics Data System (ADS)

    Loukis, E.; Mathioudakis, K.; Papailiou, K.

    1992-06-01

    A method enabling the automated diagnosis of Gas Turbine Compressor blade faults, based on the principles of statistical pattern recognition is initially presented. The decision making is based on the derivation of spectral patterns from dynamic measurements data and then the calculation of discriminants with respect to reference spectral patterns of the faults while it takes into account their statistical properties. A method of optimizing the selection of discriminants using dynamic measurements data is also presented. A few scalar discriminants are derived, in such a way that the maximum available discrimination potential is exploited. In this way the success rate of automated decision making is further improved, while the need for intuitive discriminant selection is eliminated. The effectiveness of the proposed methods is demonstrated by application to data coming from an Industrial Gas Turbine while extension to other aspects of Fault Diagnosis is discussed.

  1. Optimal design of gas adsorption refrigerators for cryogenic cooling

    NASA Technical Reports Server (NTRS)

    Chan, C. K.

    1983-01-01

    The design of gas adsorption refrigerators used for cryogenic cooling in the temperature range of 4K to 120K was examined. The functional relationships among the power requirement for the refrigerator, the system mass, the cycle time and the operating conditions were derived. It was found that the precool temperature, the temperature dependent heat capacities and thermal conductivities, and pressure and temperature variations in the compressors have important impacts on the cooling performance. Optimal designs based on a minimum power criterion were performed for four different gas adsorption refrigerators and a multistage system. It is concluded that the estimates of the power required and the system mass are within manageable limits in various spacecraft environments.

  2. Improving Gas Storage Development Planning Through Simulation-Optimization

    SciTech Connect

    Johnson, V.M.; Ammer, J.; Trick, M.D.

    2000-07-25

    This is the first of two papers describing the application of simulator-optimization methods to a natural gas storage field development planning problem. The results presented here illustrate the large gains in cost-effectiveness that can be made by employing the reservoir simulator as the foundation for a wide-ranging search for solutions to management problems. The current paper illustrates the application of these techniques given a deterministic view of the reservoir. A companion paper will illustrate adaptations needed to accommodate uncertainties regarding reservoir properties.

  3. Analysis of the dynamic characteristics of gas flow inside a laser cut kerf under high cut-assist gas pressure

    NASA Astrophysics Data System (ADS)

    Man, H. C.; Duan, J.; Yue, T. M.

    1999-07-01

    The behaviour of the cut-assist gas jet inside a simulating laser cut kerf for a supersonic and a conical nozzle tip were studied by a shadowgraphic technique under conditions of inlet stagnation pressure from 3 to 7 bar. The effects of the stand-off distance, kerf width, material thickness and the inlet stagnation pressure upon the dynamic characteristics and momentum thrust of the gas flow inside the cut kerf were investigated. It was found that under a gas pressure of 7 bar, the gas jet from a conical nozzle tip expands radially and the jet momentum deteriorates rapidly inside the kerf. The behaviour of the jet is strongly influenced by the stand-off distance and thickness of the workpiece. On the other hand, the gas jet from a supersonic nozzle inside the cut kerf has tidy boundary and uniform distribution of pressure and thrust. The sensitivity to the stand-off distance and the workpiece thickness of the supersonic nozzle are much less as compared with the conical nozzle. With the supersonic nozzle, a dross free clean cut on 5 mm stainless steel can be achieved at an inert cut-assist gas pressure as low as 5 bar instead of the normal operating range of 10 bar or above for the conical nozzle.

  4. Optimizing quantum gas production by an evolutionary algorithm

    NASA Astrophysics Data System (ADS)

    Lausch, T.; Hohmann, M.; Kindermann, F.; Mayer, D.; Schmidt, F.; Widera, A.

    2016-05-01

    We report on the application of an evolutionary algorithm (EA) to enhance performance of an ultra-cold quantum gas experiment. The production of a ^{87}rubidium Bose-Einstein condensate (BEC) can be divided into fundamental cooling steps, specifically magneto-optical trapping of cold atoms, loading of atoms to a far-detuned crossed dipole trap, and finally the process of evaporative cooling. The EA is applied separately for each of these steps with a particular definition for the feedback, the so-called fitness. We discuss the principles of an EA and implement an enhancement called differential evolution. Analyzing the reasons for the EA to improve, e.g., the atomic loading rates and increase the BEC phase-space density, yields an optimal parameter set for the BEC production and enables us to reduce the BEC production time significantly. Furthermore, we focus on how additional information about the experiment and optimization possibilities can be extracted and how the correlations revealed allow for further improvement. Our results illustrate that EAs are powerful optimization tools for complex experiments and exemplify that the application yields useful information on the dependence of these experiments on the optimized parameters.

  5. Optimization and comparison of ultrasound/microwave assisted extraction (UMAE) and ultrasonic assisted extraction (UAE) of lycopene from tomatoes.

    PubMed

    Lianfu, Zhang; Zelong, Liu

    2008-07-01

    The extracting technology including ultrasonic and microwave assisted extraction (UMAE) and ultrasonic assisted extraction (UAE) of lycopene from tomato paste were optimized and compared. The results showed that the optimal conditions for UMAE were 98 W microwave power together with 40 KHz ultrasonic processing, the ratio of solvents to tomato paste was 10.6:1 (V/W) and the extracting time should be 367 s; as for UAE, the extracting temperature was 86.4 degrees C, the ratio of the solvents to tomato paste was 8.0:1 (V/W) and the extracting time should be 29.1 min, while the percentage of lycopene yield was 97.4% and 89.4% for UMAE and UAE, respectively. These results implied that UMAE was far more efficient extracting method than UAE.

  6. Optimal Use of Wire-Assisted Techniques and Precut Sphincterotomy

    PubMed Central

    Lee, Tae Hoon; Park, Sang-Heum

    2016-01-01

    Various endoscopic techniques have been developed to overcome the difficulties in biliary or pancreatic access during endoscopic retrograde cholangiopancreatography, according to the preference of the endoscopist or the aim of the procedures. In terms of endoscopic methods, guidewire-assisted cannulation is a commonly used and well-known initial cannulation technique, or an alternative in cases of difficult cannulation. In addition, precut sphincterotomy encompasses a range of available rescue techniques, including conventional precut, precut fistulotomy, transpancreatic septotomy, and precut after insertion of pancreatic stent or pancreatic duct guidewire-guided septal precut. We present a literature review of guidewire-assisted cannulation as a primary endoscopic method and the precut technique for the facilitation of selective biliary access. PMID:27642848

  7. A new method for optimization of low-thrust gravity-assist sequences

    NASA Astrophysics Data System (ADS)

    Maiwald, V.

    2017-02-01

    Recently missions like Hayabusa and Dawn have shown the relevance and benefits of low-thrust spacecraft concerning the exploration of our solar system. In general, the efficiency of low-thrust propulsion is one means of improving mission payload mass. At the same time, gravity-assist maneuvers can serve as mission enablers, as they have the capability to provide "free energy." A combination of both, gravity-assist and low-thrust propulsion, has the potential to generally improve mission performance, i.e. planning and optimization of gravity-assist sequences for low-thrust missions is a desirable asset. Currently no established methods exist to include the gravity-assist partners as optimization variable for low-thrust missions. The present paper explains how gravity-assists are planned and optimized, including the gravity-assist partners, for high-thrust missions and discusses the possibility to transfer the established method, based on the Tisserand Criterion, to low-thrust missions. It is shown how the Tisserand Criterion needs to be adapted using a correction term for the low-thrust situation. It is explained why this necessary correction term excludes an a priori evaluation of sequences and therefore their planning and an alternate approach is proposed. Preliminary results of this method, by application of a Differential Evolution optimization algorithm, are presented and discussed, showing that the method is valid but can be improved. Two constraints on the search space are briefly presented for that aim.

  8. Optimizing the separation performance of a gas centrifuge

    NASA Astrophysics Data System (ADS)

    Wood, H. G.

    1997-11-01

    Gas centrifuges were originally developed for the enrichment of U^235 from naturally occurring uranium for the purpose of providing fuel for nuclear power reactors and material for nuclear weapons. This required the separation of a binary mixture composed of U^235 and U^238. Since the end of the cold war, a surplus of enriched uranium exists on the world market, but many centrifuge plants exist in numerous countries. These circumstances together with the growing demand for stable isotopes for chemical and physical research and in medical science has led to the exploration of alternate applications of gas centrifuge technology. In order to acieve these multi-component separations, existing centrifuges must be modified or new centrifuges must be designed. In either case, it is important to have models of the internal flow fields to predict the separation performance and algorithms to seek the optimal operating conditions of the centrifuges. Here, we use the Onsager pancake model of the internal flow field, and we present an optimization strategy which exploits a similarity parameter in the pancake model. Numerical examples will be presented.

  9. Chaos and Gas-Assisted Capture of Kozai Resonators

    NASA Astrophysics Data System (ADS)

    Carruba, V.; Nesvorny, D.; Cuk, M.; Burns, J. A.; Rand, R.

    2003-05-01

    Carruba et al. (2003) previously studied a layer of chaos for satellites in Kozai resonance, i.e., satellites whose argument of pericenter, instead of circulating from 0 to 360 degrees, librates around +/- 90 degrees. By performing numerical simulations with test particles covering the orbital space surrounding S/2000S5, a satellite of Saturn currently in this resonance, and by applying the Frequency Analysis Method of Laskar (Laskar, 1993, 1999), we identified a layer of chaos at the transition between circulation and libration. We now further investigate this chaotic boundary and try to determine its cause(s). Our simulations suggest that, for the case of S5, perturbations from Jupiter are needed to create the chaotic boundary. In order to understand if secular or short-period terms in the disturbing potential of Jupiter are actually responsible for the appearance of the layer of chaos we are performing simulations where test particles are subjected to perturbations from a Jupiter on a fictitious orbit whose parameters are determined using the Bretagnon model (Bretagnon and Francou 1992). By perfoming simulations with Jovian orbits that only include either secular or secular and short-period terms, we are confident we shall be able to identify the source of chaos. Another problem posed by the existence of the chaotic boundary is its possible relevance for capture mechanisms. In this work we have modified the SWIFT-WHM integrator to account for gas-drag, according to the model of Cuk and Burns (2003). Preliminary results of our simulations suggest that, for typical values of gas density at the mid-point of the disk (6*10-9 g/cm3), the chaotic layer does not affect the capture of satellites into Kozai resonance. The chaotic layer might, however, still play a role in the very last phases of capture, when the gas-disk is dissipating. We are currently investigating different sets of gas-densities and disk parameters. As Cuk et al. (2002) found, preliminary results of

  10. Monte Carlo modeling and optimization of buffer gas positron traps

    NASA Astrophysics Data System (ADS)

    Marjanović, Srđan; Petrović, Zoran Lj

    2017-02-01

    Buffer gas positron traps have been used for over two decades as the prime source of slow positrons enabling a wide range of experiments. While their performance has been well understood through empirical studies, no theoretical attempt has been made to quantitatively describe their operation. In this paper we apply standard models as developed for physics of low temperature collision dominated plasmas, or physics of swarms to model basic performance and principles of operation of gas filled positron traps. The Monte Carlo model is equipped with the best available set of cross sections that were mostly derived experimentally by using the same type of traps that are being studied. Our model represents in realistic geometry and fields the development of the positron ensemble from the initial beam provided by the solid neon moderator through voltage drops between the stages of the trap and through different pressures of the buffer gas. The first two stages employ excitation of N2 with acceleration of the order of 10 eV so that the trap operates under conditions when excitation of the nitrogen reduces the energy of the initial beam to trap the positrons without giving them a chance to become annihilated following positronium formation. The energy distribution function develops from the assumed distribution leaving the moderator, it is accelerated by the voltage drops and forms beams at several distinct energies. In final stages the low energy loss collisions (vibrational excitation of CF4 and rotational excitation of N2) control the approach of the distribution function to a Maxwellian at room temperature but multiple non-Maxwellian groups persist throughout most of the thermalization. Optimization of the efficiency of the trap may be achieved by changing the pressure and voltage drops and also by selecting to operate in a two stage mode. The model allows quantitative comparisons and test of optimization as well as development of other properties.

  11. Solar assisted gas-fired absorption heat pump

    NASA Astrophysics Data System (ADS)

    Murphy, K. P.; Burke, J. C.; Phillips, B. A.

    1982-08-01

    An evaluation of the technical and economic feasibility of coupling an absorption heat pump and an active solar system for residential applications is discussed. The absorption heat pump is based on a new absorption working pair developed by Allied. Three basic modes of coupling were considered, a series arrangement, a parallel arrangement, and a solar drive arrangement. Little overall difference in performance was found for these three modes but the solar drive was chosen for detailed study. A preliminary design of a dual mode absorption generator was developed capable of using simultaneously heat from gas and solar. The performance of such a system was examined in three cities.

  12. Study of optimal gas pressure in optically pumped D IIO gas terahertz laser

    NASA Astrophysics Data System (ADS)

    He, Zhihong; Yao, Jianquan; Ren, Xia; Yang, Yang; Luo, Xizhang; Wang, Peng

    2008-03-01

    Heavy water vapor (D IIO gas) which owns special structure properties, can generate terahertz (THz) radiation by optically pumped technology, and its 385 μm wavelength radiation can be widely used. In this research, on the base of semi-classical density matrix theory, we set up a three-level energy system as its theoretical model, a TEA-CO II laser 9R (22) output line (λ=9.26 μm) acted as pumping source, D IIO gas molecules were operating medium, the expressions of pumping absorption coefficient G p and THz signal gain coefficient G s were deduced , It was shown that the gain of THz signal was related with the energy-level parameters of operating molecules and some operating parameters of the THz laser cavity, mainly including gas pressure, temperature etc.; By means of iteration method, the output power density of THz pulse signal was calculated numerically as its initial power density was known; Changing the parameter of gas pressure and keeping others steady, the relationship curve between the output power intensity (Is) of Tera-Hz pulse laser and the operating D IIO gas pressure (P) was obtained. The curve showed that the power intensity (Is) increased with gas pressure (P) in a certain range, but decreased when the pressure (P) exceeded some value because of the bottleneck effect, and there was an optimal gas pressure for the highest output power. We used a grating tuned TEA-CO II laser as pumping power and a sample tube of 97cm length as THz laser operating cavity to experiment. The results of theoretical calculation and experiment matched with each other.

  13. Optimizing Geothermal Drilling: Oil and Gas Technology Transfer

    SciTech Connect

    Tilley, Mitch; Eustes, Alfred; Visser, Charles; Baker, Walt; Bolton, Dan; Bell, Jason; Nagandran, Uneshddarann; Quick, Ralph

    2015-01-26

    There is a significant amount of financial risk associated with geothermal drilling; however, there are opportunities to improve upon current practices and technologies used. The scope of this drilling operational study included 21 geothermal wells and 21 oil and gas wells. The goal was to determine a 'perfect well' using historical data to compare the best oil and gas well to the best geothermal well. Unfortunately, limitations encountered in the study included missing data (bit records, mud information, etc.), poor data collection, and difficult to ascertain handwriting. An online software database was used to format drilling data to IADC coded daily drilling reports and generate analysis figures. Six major issues have been found in geothermal drilling operations. These problems include lost circulation, rig/equipment selection, cementing, penetration rate, drilling program, and time management. As a result of these issues, geothermal drilling averages 56.4 days longer than drilling comparable oil and gas wells in the wells in this study. Roughly $13.9 million would be lost due to non-productive time in the 21 geothermal wells and only $1.3 million in the oil and gas wells, assuming a cost of $50,000 per day. Comparable events such as drilling the same sized hole, tripping in/out, cementing, and running the same size casing took substantially less time in the oil and gas wells. Geothermal wells were drilled using older and/or less advanced technology to depths less than 10,000 feet, while oil and gas wells reached 12,500 feet faster with purpose built rigs. A new approach is now underway that will optimize drilling programs throughout the drilling industry. It is the use of Mechanical Specific Energy (MSE) as a tool to realize efficient drilling processes. However, a work-flow must also be established in order for there to be an efficient drilling program. Potential improvements for current geothermal operations are: the use of electronic records, real time

  14. Designing optimal greenhouse gas monitoring networks for Australia

    NASA Astrophysics Data System (ADS)

    Ziehn, T.; Law, R. M.; Rayner, P. J.; Roff, G.

    2016-01-01

    Atmospheric transport inversion is commonly used to infer greenhouse gas (GHG) flux estimates from concentration measurements. The optimal location of ground-based observing stations that supply these measurements can be determined by network design. Here, we use a Lagrangian particle dispersion model (LPDM) in reverse mode together with a Bayesian inverse modelling framework to derive optimal GHG observing networks for Australia. This extends the network design for carbon dioxide (CO2) performed by Ziehn et al. (2014) to also minimise the uncertainty on the flux estimates for methane (CH4) and nitrous oxide (N2O), both individually and in a combined network using multiple objectives. Optimal networks are generated by adding up to five new stations to the base network, which is defined as two existing stations, Cape Grim and Gunn Point, in southern and northern Australia respectively. The individual networks for CO2, CH4 and N2O and the combined observing network show large similarities because the flux uncertainties for each GHG are dominated by regions of biologically productive land. There is little penalty, in terms of flux uncertainty reduction, for the combined network compared to individually designed networks. The location of the stations in the combined network is sensitive to variations in the assumed data uncertainty across locations. A simple assessment of economic costs has been included in our network design approach, considering both establishment and maintenance costs. Our results suggest that, while site logistics change the optimal network, there is only a small impact on the flux uncertainty reductions achieved with increasing network size.

  15. AF fixer: new incremental OPC method for optimizing assist feature

    NASA Astrophysics Data System (ADS)

    Jung, Sung-Gon; Kim, Sang-Wook; Suh, Sung-Soo; Kim, Young-Chang; Lee, Suk-Joo; Choi, Sung-Woon; Han, Woo-Sung; Moon, Joo-Tae; Barnes, Levi D.; Li, Xiaohai; Lugg, Robert M.; Lee, Sooryong; Koo, Kyoil; Do, Munhoe; Amoroso, Frank P.; Painter, Benjamin

    2008-05-01

    Due to shrinking design nodes and to some limitations of scanners, extreme off-axis illumination (OAI) required and its use and implementation of assist features (AF) to solve depth of focus (DOF) problems for isolated features and specific pitch regions is essential. But unfortunately, the strong periodic character of OAI illumination makes AF's print more easily. Present OPC flows generate AFs before OPC, which is also causes some AF printing problems. At present, mask manufacturers must downsize AF's below 30nm to solve this problem. This is challenging and increases mask cost. We report on an AF-fixer tool which is able to check AF printability and correct weak points with minimal cost in terms of DOF after OPC. We have devised an effective algorithm that removes printing AF's. It can not only search for the best non-printing AF condition to meet the DOF spec, but also reports uncorrectable spots, which could be marked as design errors. To limit correction times and to maximize DOF in full-chip correction, a process window (PW) model and incremental OPC method are applied. This AF fixer, which suggests optimum AF in only weak point region, solves AF printing problems economically and accurately.

  16. Simultaneous analysis of polychlorinated biphenyls and organochlorine pesticides in seawater samples by membrane-assisted solvent extraction combined with gas chromatography-electron capture detector and gas chromatography-tandem mass spectrometry.

    PubMed

    Shi, Xizhi; Tang, Zigang; Sun, Aili; Zhou, Lei; Zhao, Jian; Li, Dexiang; Chen, Jiong; Pan, Daodong

    2014-12-01

    A highly efficient and environment-friendly membrane-assisted solvent extraction system combined with gas chromatography-electron capture detector was applied in the simultaneous determination of 17 polychlorinated biphenyls and organochlorine pesticides in seawater samples. Variables affecting extraction efficiency, including extraction solvent used, stirring rate, extraction time, and temperature, were optimized extensively. Under optimal extraction conditions, recoveries between 76.9% and 104.6% in seawater samples were achieved, and relative standard deviation values below 10% were obtained. The limit of detection (signal-to-noise ratio=3) and limit of quantification (signal-to-noise ratio=10) of 17 polychlorinated biphenyls and organochlorine pesticides in seawater ranged from 0.14ngL(-1) to 0.36ngL(-1) and 0.46ngL(-1) to 1.19ngL(-1), respectively. Matrix effects on extraction efficiency were evaluated by comparing with the results obtained using tap water. The extraction effect of developed membrane-assisted solvent extraction method was further demonstrated by gas chromatography-tandem mass spectrometry which can provide structural information of the analytes for more accurate identification, and results identical to those produced by gas chromatography-electron capture detector were obtained. These findings demonstrate the applicability of the developed membrane-assisted solvent extraction determination method for coupling to gas chromatography-electron capture detector or tandem mass spectrometry for determining polychlorinated biphenyls and organochlorine pesticides in seawater samples.

  17. Effect of impeller design and spacing on gas exchange in a percutaneous respiratory assist catheter.

    PubMed

    Jeffries, R Garrett; Frankowski, Brian J; Burgreen, Greg W; Federspiel, William J

    2014-12-01

    Providing partial respiratory assistance by removing carbon dioxide (CO2 ) can improve clinical outcomes in patients suffering from acute exacerbations of chronic obstructive pulmonary disease and acute respiratory distress syndrome. An intravenous respiratory assist device with a small (25 Fr) insertion diameter eliminates the complexity and potential complications associated with external blood circuitry and can be inserted by nonspecialized surgeons. The impeller percutaneous respiratory assist catheter (IPRAC) is a highly efficient CO2 removal device for percutaneous insertion to the vena cava via the right jugular or right femoral vein that utilizes an array of impellers rotating within a hollow-fiber membrane bundle to enhance gas exchange. The objective of this study was to evaluate the effects of new impeller designs and impeller spacing on gas exchange in the IPRAC using computational fluid dynamics (CFD) and in vitro deionized water gas exchange testing. A CFD gas exchange and flow model was developed to guide a progressive impeller design process. Six impeller blade geometries were designed and tested in vitro in an IPRAC device with 2- or 10-mm axial spacing and varying numbers of blades (2-5). The maximum CO2 removal efficiency (exchange per unit surface area) achieved was 573 ± 8 mL/min/m(2) (40.1 mL/min absolute). The gas exchange rate was found to be largely independent of blade design and number of blades for the impellers tested but increased significantly (5-10%) with reduced axial spacing allowing for additional shaft impellers (23 vs. 14). CFD gas exchange predictions were within 2-13% of experimental values and accurately predicted the relative improvement with impellers at 2- versus 10-mm axial spacing. The ability of CFD simulation to accurately forecast the effects of influential design parameters suggests it can be used to identify impeller traits that profoundly affect facilitated gas exchange.

  18. Gas assisted thin-film evaporation from confined spaces

    NASA Astrophysics Data System (ADS)

    Narayanan, Shankar

    A novel cooling mechanism based on evaporation of thin liquid films is presented for thermal management of confined heat sources, such as microprocessor hotspots, high power light emitting diodes and RF packages with a high operational frequency. A thin nanoporous membrane (˜1--5microm) is utilized to maintain microscopically thin liquid films (˜1--5microm) by capillary action, while providing a pathway for the vapor generated due to evaporation at the liquid-vapor interface. The vapor generated by evaporation is continuously removed by using a dry sweeping gas, keeping the membrane outlet dry. This thesis presents a detailed theoretical, computational and experimental investigation of the heat and mass transfer mechanisms that result in cooling the confined heat sources. Performance analysis of this cooling mechanism demonstrates heat fluxes over 600W/cm2 for sufficiently thin membrane and film thicknesses (˜1--5microm) and by using air jet impingement for advection of vapor from the membrane surface. Based on the results from this performance analysis, a monolithic micro-fluidic device is designed and fabricated incorporating micro and nanoscale features. This MEMS/NEMS device serves multiple functionalities of hotspot simulation, temperature sensing, and evaporative cooling. Subsequent experimental investigations using this microfluidic device demonstrate heat fluxes in excess of 600W/cm2 at 90 °C using water as the evaporating coolant. In order to further enhance the device performance, a comprehensive theoretical and computational analysis of heat and mass transfer at micro and nanoscales is carried out. Since the coolant is confined using a nanoporous membrane, a detailed study of evaporation inside a nanoscale cylindrical pore is performed. The continuum analysis of water confined within a cylindrical nanopore determines the effect of electrostatic interaction and Van der Waals forces in addition to capillarity on the interfacial transport

  19. Stepwise approaches to optimize strategy for holding thoracoscope during single port video-assisted thoracoscopic surgery

    PubMed Central

    Liu, Chengwu; Deng, Senyi; Liao, Hu; Ma, Lin; Pu, Qiang; Mei, Jiandong

    2016-01-01

    Coordination between the thoracoscope assistant and the surgeon was difficult during single port video-assisted thoracoscopic surgery (SP-VATS). What’s more, holding the thoracoscope was an exhausting work for the assistant and optimized strategies were intensely needed. This paper aims to share our experience in making the thoracoscope assistant feel comfortable by illustrating the stepwise approaches in optimizing the strategies for holding the thoracoscope during our practice of SP-VATS. The evolution of techniques were divided into four stages: stage I, traditional 10-mm 30° thoracoscope placed at the posterior part of the incision; stage II, 5-mm thoracoscope towed and fixed via a silk suture; stage III, 5-mm thoracoscope placed outside of a plastic wound protector; stage IV, 5-mm thoracoscope introduced into the thoracic cavity through a 5-mm laparoscopic trocar outside of a plastic wound protector and the assistant stood at a foot-stool. After stepwise improvement, the thoracoscope assistant felt more labor saving and comfortable, and coordination with the surgeon has become smoother. PMID:27867575

  20. Direct droplet production from a liquid film: a new gas-assisted atomization mechanism

    NASA Astrophysics Data System (ADS)

    Snyder, Herman E.; Reitz, Rolf D.

    1998-11-01

    X-ray lithography and micro-machining have been used to study gas-assisted liquid atomization in which a liquid film was impinged by a large number of sonic micro-gas jets. Three distinct breakup regimes were demonstrated. Two of these regimes share characteristics with previously observed atomization processes: a bubble bursting at a free surface (Newitt et al. 1954; Boulton-Stone & Blake 1993) and liquid sheet disintegration in a high gas/liquid relative velocity environment (Dombrowski & Johns 1963). The present work shows that suitable control of the gas/liquid interface creates a third regime, a new primary atomization mechanism, in which single liquid droplets are ejected directly from the liquid film without experiencing an intermediate ligament formation stage. The interaction produces a stretched liquid sheet directly above each gas orifice. This effectively pre-films the liquid prior to its breakup. Following this, surface tension contracts the stretched film of liquid into a sphere which subsequently detaches from the liquid sheet and is entrained by the gas jet that momentarily pierces the film. After droplet ejection, the stretched liquid film collapses, covering the gas orifice, and the process repeats. This new mechanism is capable of the efficient creation of finely atomized sprays at low droplet ejection velocities (e.g. 20 [mu]m Sauter mean diameter methanol sprays using air at 239 kPa, with air-to-liquid mass ratios below 1.0, and droplet velocities lower than 2.0 m s[minus sign]1). Independent control of the gas and the liquid flows allows the droplet creation process to be effectively de-coupled from the initial droplet momentum, a characteristic not observed with standard gas-assisted atomization mechanisms.

  1. Gas-assisted annular microsprayer for sample preparation for time-resolved cryo-electron microscopy

    NASA Astrophysics Data System (ADS)

    Lu, Zonghuan; Barnard, David; Shaikh, Tanvir R.; Meng, Xing; Mannella, Carmen A.; Yassin, Aymen S.; Agrawal, Rajendra K.; Wagenknecht, Terence; Lu, Toh-Ming

    2014-11-01

    Time-resolved cryo-electron microscopy (TRCEM) has emerged as a powerful technique for transient structural characterization of isolated biomacromolecular complexes in their native state within the time scale of seconds to milliseconds. For TRCEM sample preparation, a microfluidic device has been demonstrated to be a promising approach to facilitate TRCEM biological sample preparation. It is capable of achieving rapidly aqueous sample mixing, controlled reaction incubation, and sample deposition on electron microscopy (EM) grids for rapid freezing. One of the critical challenges is to transfer samples to cryo-EM grids from the microfluidic device. By using a microspraying method, the generated droplet size needs to be controlled to facilitate thin ice film formation on the grid surface for efficient data collection, whilst not being so thin that it dries out before freezing, i.e. an optimized mean droplet size needs to be achieved. In this work, we developed a novel monolithic three dimensional (3D) annular gas-assisted microfluidic sprayer using 3D MEMS (MicroElectroMechanical System) fabrication techniques. The microsprayer demonstrated dense and consistent microsprays with average droplet size between 6 and 9 μm, which fulfilled the droplet size requirement for TRCEM sample preparation. With droplet density of around 12-18 per grid window (window size 58  ×  58 μm), and a data collectible thin ice region of >50% total wetted area, we collected ~800-1000 high quality CCD micrographs in a 6-8 h period of continuous effort. This level of output is comparable to what were routinely achieving using cryo-grids prepared by conventional blotting and manual data collection. In this case, weeks of data collection with the previous device has been shortened to a day or two. And hundreds of microliters of valuable sample consumption can be reduced to only a small fraction.

  2. Gas-Assisted Annular Microsprayer for Sample Preparation for Time-Resolved Cryo-Electron Microscopy

    PubMed Central

    Lu, Zonghuan; Barnard, David; Shaikh, Tanvir R.; Meng, Xing; Mannella, Carmen A.; Yassin, Aymen; Agrawal, Rajendra; Wagenknecht, Terence; Lu, Toh-Ming

    2014-01-01

    Time-resolved cryo electron microscopy (TRCEM) has emerged as a powerful technique for transient structural characterization of isolated biomacromolecular complexes in their native state within the time scale of seconds to milliseconds. For TRCEM sample preparation, microfluidic device [9] has been demonstrated to be a promising approach to facilitate TRCEM biological sample preparation. It is capable of achieving rapidly aqueous sample mixing, controlled reaction incubation, and sample deposition on electron microscopy (EM) grids for rapid freezing. One of the critical challenges is to transfer samples to cryo-EM grids from the microfluidic device. By using microspraying method, the generated droplet size needs to be controlled to facilitate the thin ice film formation on the grid surface for efficient data collection, while not too thin to be dried out before freezing, i.e., optimized mean droplet size needs to be achieved. In this work, we developed a novel monolithic three dimensional (3D) annular gas-assisted microfluidic sprayer using 3D MEMS (MicroElectroMechanical System) fabrication techniques. The microsprayer demonstrated dense and consistent microsprays with average droplet size between 6-9 μm, which fulfilled the above droplet size requirement for TRCEM sample preparation. With droplet density of around 12-18 per grid window (window size is 58×58 μm), and the data collectible thin ice region of >50% total wetted area, we collected ~800-1000 high quality CCD micrographs in a 6-8 hour period of continuous effort. This level of output is comparable to what were routinely achieved using cryo-grids prepared by conventional blotting and manual data collection. In this case, weeks of data collection process with the previous device [9] has shortened to a day or two. And hundreds of microliter of valuable sample consumption can be reduced to only a small fraction. PMID:25530679

  3. Optimization of microwave-assisted extraction with saponification (MAES) for the determination of polybrominated flame retardants in aquaculture samples.

    PubMed

    Fajar, N M; Carro, A M; Lorenzo, R A; Fernandez, F; Cela, R

    2008-08-01

    The efficiency of microwave-assisted extraction with saponification (MAES) for the determination of seven polybrominated flame retardants (polybrominated biphenyls, PBBs; and polybrominated diphenyl ethers, PBDEs) in aquaculture samples is described and compared with microwave-assisted extraction (MAE). Chemometric techniques based on experimental designs and desirability functions were used for simultaneous optimization of the operational parameters used in both MAES and MAE processes. Application of MAES to this group of contaminants in aquaculture samples, which had not been previously applied to this type of analytes, was shown to be superior to MAE in terms of extraction efficiency, extraction time and lipid content extracted from complex matrices (0.7% as against 18.0% for MAE extracts). PBBs and PBDEs were determined by gas chromatography with micro-electron capture detection (GC-muECD). The quantification limits for the analytes were 40-750 pg g(-1) (except for BB-15, which was 1.43 ng g(-1)). Precision for MAES-GC-muECD (%RSD < 11%) was significantly better than for MAE-GC-muECD (%RSD < 20%). The accuracy of both optimized methods was satisfactorily demonstrated by analysis of appropriate certified reference material (CRM), WMF-01.

  4. 3D Numerical study on the hollow profile polymer extrusion forming based on the gas-assisted technique

    NASA Astrophysics Data System (ADS)

    Ren, Z.; Huang, X. Y.; Liu, H. S.

    2016-07-01

    In this study, gas-assisted extrusion method was introduced into the extrusion of the hollow profiles. To validate the feasibility of the new extrusion method, 3D numerical simulation of the hollow profiles based on gas-assisted technique was carried out by using the finite element method. The Phan-Thien-Tanner (PTT) mode was selected as the construction equation. In the simulations, the physical field distributions of four different extrusion modes were obtained and analyzed. Results showed that the extrudate effect of traditional no gas- assisted mode was poor because the extrudate swell phenomenon is obvious and the physical field values are larger. For the gas-assisted of the inner wall, the extrudate swell of the melt was more obvious than that of the traditional no gas-assisted mode on account of the no-slip boundary condition on the outer wall. For the gas-assisted of the outer wall, the dimple effect of the inner wall is more obvious owing to the no-slip boundary condition on the inner wall. However, the extrusion effect of the double walls gas-assisted mode is very good because of the full-slip effect on the both walls.

  5. Fully automated system for the gas chromatographic characterization of polar biopolymers based on thermally assisted hydrolysis and methylation.

    PubMed

    Kaal, Erwin; de Koning, Sjaak; Brudin, Stella; Janssen, Hans-Gerd

    2008-08-08

    Pyrolysis-gas chromatography (Py-GC) is a powerful tool for the detailed compositional analysis of polymers. A major problem of Py-GC is that polar (bio)polymers yield polar pyrolyzates which are not easily accessible to further GC characterization. In the present work, a newly developed fully automated procedure for thermally assisted hydrolysis and methylation (THM) of biopolymers is described. Drying of the sample, addition of the reagent, incubation and pyrolysis are performed inside the liner of a programmable temperature vaporizer injector. The new system not only allows efficient analysis of large series of samples, but also allows automated optimization of the experimental parameters based on an experimental design approach. The performance of the automated THM-procedure was evaluated by performing THM-GC of a poly(acrylic acid)-poly(maleic anhydride) copolymer (PAA/PMAH) and several polysaccharides. The optimized THM-procedure was applied for the structural characterization and differentiation of several lignins and hydroxypropylmethyl-celluloses. It was also applied to proteins. Here myoglobin and cytochrome c were used as the model compounds. Both conventional GC-mass spectrometry (MS) and comprehensive two-dimensional gas chromatography (GCxGC)-time-of-flight (TOF) MS were used for separation and identification of the species formed. The information obtained can aid in structure elucidation of polar biopolymers as well as in providing detailed compositional information which can be used to differentiate structurally similar biopolymers.

  6. Microengineered cold gas thruster system for a co-orbiting satellite assistant (COSA)

    NASA Astrophysics Data System (ADS)

    Huang, Adam; Hansen, William W.; Janson, Siegfried W.; Helvajian, Henry

    2001-10-01

    Miniaturization technologies such as Micro-Electro-Mechanical Systems (MEMS) have been used to fabricate a prototype 100-gm class cold gas propulsion system suitable for use on a Co-Orbiting Satellite Assistant (COSA). The propulsion system is fabricated from bonded layers of photostructurable glass (Foturan glass; the design is based on fabricating integrated modular parts. Thus, the propulsion system is mass producible, expandable, expendable (low unit cost), and highly integrated.

  7. Optimization of a radiative membrane for gas sensing applications

    NASA Astrophysics Data System (ADS)

    Lefebvre, Anthony; Boutami, Salim; Greffet, Jean-Jacques; Benisty, Henri

    2014-05-01

    To engineer a cheap, portable and low-power optical gas sensor, incandescent sources are more suitable than expensive quantum cascade lasers and low-efficiency light-emitting diodes. Such sources of radiation have already been realized, using standard MEMS technology, consisting in free standing circular micro-hotplates. This paper deals with the design of such membranes in order to maximize their wall-plug efficiency. Specification constraints are taken into account, including available energy per measurement and maximum power delivered by the electrical supply source. The main drawback of these membranes is known to be the power lost through conduction to the substrate, thus not converted in (useful) radiated power. If the membrane temperature is capped by technological requirements, radiative flux can be favored by increasing the membrane radius. However, given a finite amount of energy, the larger the membrane and its heat capacity, the shorter the time it can be turned on. This clearly suggests that an efficiency optimum has to be found. Using simulations based on a spatio-temporal radial profile, we demonstrate how to optimally design such membrane systems, and provide an insight into the thermo-optical mechanisms governing this kind of devices, resulting in a nontrivial design with a substantial benefit over existing systems. To further improve the source, we also consider tailoring the membrane stack spectral emissivity to promote the infrared signal to be sensed as well as to maximize energy efficiency.

  8. METHANE EMISSIONS FROM THE NATURAL GAS INDUSTRY VOLUME 15: GAS-ASSISTED GLYCOL PUMPS

    EPA Science Inventory

    The 15-volume report summarizes the results of a comprehensive program to quantify methane (CH4) emissions from the U.S. natural gas industry for the base year. The objective was to determine CH4 emissions from the wellhead and ending downstream at the customer's meter. The accur...

  9. APPLICATION OF OPTIMAL CONTROL THEORY TO CARDIO-CIRCULATORY ASSIST DEVICES.

    DTIC Science & Technology

    The objective of the investigation is the application of, and where necessary, extension of optimal control theory to the synthesis of controllers for such cardio-circulatory assist devices. In particular, the concept of set of attainability is extended to include linear, periodic, bounded control systems and the maximum principle applied to obtain necessary and sufficient conditions for various problems. In addition to several numerical examples, the results of a large-scale hybrid simulation for a cardiovascular model and particular assist device are presented.

  10. Gas-assisted gravity drainage (GAGD) process for improved oil recovery

    SciTech Connect

    Rao, Dandina N

    2012-07-10

    A rapid and inexpensive process for increasing the amount of hydrocarbons (e.g., oil) produced and the rate of production from subterranean hydrocarbon-bearing reservoirs by displacing oil downwards within the oil reservoir and into an oil recovery apparatus is disclosed. The process is referred to as "gas-assisted gravity drainage" and comprises the steps of placing one or more horizontal producer wells near the bottom of a payzone (i.e., rock in which oil and gas are found in exploitable quantities) of a subterranean hydrocarbon-bearing reservoir and injecting a fluid displacer (e.g., CO.sub.2) through one or more vertical wells or horizontal wells. Pre-existing vertical wells may be used to inject the fluid displacer into the reservoir. As the fluid displacer is injected into the top portion of the reservoir, it forms a gas zone, which displaces oil and water downward towards the horizontal producer well(s).

  11. EMG assisted optimization: a hybrid approach for estimating muscle forces in an indeterminate biomechanical model.

    PubMed

    Cholewicki, J; McGill, S M

    1994-10-01

    There are two basic approaches to estimate individual muscle forces acting on a joint, given the indeterminacy of moment balance equations: optimization and electromyography (EMG) assisted. Each approach is characterized by unique advantages and liabilities. With this in mind, a new hybrid method which combines the advantages of both of these traditional approaches, termed 'EMG assisted optimization' (EMGAO), was described. In this method, minimal adjustments are applied to the individual muscle forces estimated from EMG, so that all moment equilibrium equations are satisfied in three dimensions. The result is the best possible match between physiologically observed muscle activation patterns and the predicted forces, while satisfying the moment constraints about all three joint axes. Several forms of the objective function are discussed and their effect on individual muscle adjustments is illustrated in a simple two-dimensional example.

  12. The problem of optimal placement of sub-resolution assist features (SRAF)

    NASA Astrophysics Data System (ADS)

    Mukherjee, Maharaj; Mansfield, Scott; Liebmann, Lars; Lvov, Alexey; Papadapoulou, Evanthia; Lavin, Mark; Zhao, Zengqin

    2005-05-01

    In this paper, we present a formulation of the Sub-Resolution Assist Feature (SRAF) placement problem as a geometric optimization problem. We present three independent geometric methodologies that use the above formulation to optimize SRAF placements under mask and lithographic process constraints. Traditional rules-based methodology, are mainly one dimensional in nature. These methods, though apparently very simple, has proven to be inadequate for complex two-dimensional layouts. The methodologies presented in this paper, on the other hand, are inherently two-dimensional and attempt to maximize SRAF coverage on real and complex designs, and minimizes mask rule and lithographic violations.

  13. Fast low-pressure microwave assisted extraction and gas chromatographic determination of polychlorinated biphenyls in soil samples.

    PubMed

    Bruzzoniti, M C; Maina, R; Tumiatti, V; Sarzanini, C; Rivoira, L; De Carlo, R M

    2012-11-23

    A new technology equipment for low-pressure microwave assisted extraction (usually employed for organic chemistry reactions), recently launched in the market, is used for the first time in environmental analysis for the extraction of commercial technical Aroclor mixtures from soil. Certified reference materials of Aroclor 1260, Aroclor 1254 and Aroclor 1242 in transformer oils were used to contaminate the soil samples and to optimize the extraction method as well as the subsequent gas chromatographic electron capture detection (GC-ECD) analytical method. The study was performed optimizing the extraction, the purification and the gas chromatographic separation conditions to enhance the resolution of difficult pairs of congeners (C28/31 and C141/179). After optimization, the recovery yields were included within the range 79-84%. The detection limits, evaluated for two different commercial polychlorinated biphenyl (PCB) mixtures (Aroclor 1260 and Aroclor 1242) were 0.056 ± 0.001 mg/kg and 0.290 ± 0.006 mg/kg, respectively. The method, validated with certified soil samples, was used to analyze a soil sample after an event of failure of a pole-mounted transformer which caused the dumping of PCB contaminated oil in soil. Moreover, the method provides simple sample handling, fast extraction with reduced amount of sample and solvents than usually required, and simple purification step involving the use of solvent (cyclohexane) volumes as low as 5 mL. Reliability and reproducibility of extraction conditions are ensured by direct and continuous monitoring of temperature and pressure conditions.

  14. Laser-assisted focused He+ ion beam induced etching with and without XeF2 gas assist

    SciTech Connect

    Stanford, Michael G.; Mahady, Kyle; Lewis, Brett B.; Fowlkes, Jason D.; Tan, Shida; Livengood, Richard; Magel, Gregory A.; Moore, Thomas M.; Rack, Philip D.

    2016-10-04

    Focused helium ion (He+) milling has been demonstrated as a high-resolution nanopatterning technique; however, it can be limited by its low sputter yield as well as the introduction of undesired subsurface damage. Here, we introduce pulsed laser- and gas-assisted processes to enhance the material removal rate and patterning fidelity. A pulsed laser-assisted He+ milling process is shown to enable high-resolution milling of titanium while reducing subsurface damage in situ. Gas-assisted focused ion beam induced etching (FIBIE) of Ti is also demonstrated in which the XeF2 precursor provides a chemical assist for enhanced material removal rate. In conclusion, a pulsed laser-assisted and gas-assisted FIBIE process is shown to increase the etch yield by ~9× relative to the pure He+ sputtering process. These He+ induced nanopatterning techniques improve material removal rate, in comparison to standard He+ sputtering, while simultaneously decreasing subsurface damage, thus extending the applicability of the He+ probe as a nanopattering tool.

  15. Shape optimization of pulsatile ventricular assist devices using FSI to minimize thrombotic risk

    NASA Astrophysics Data System (ADS)

    Long, C. C.; Marsden, A. L.; Bazilevs, Y.

    2014-10-01

    In this paper we perform shape optimization of a pediatric pulsatile ventricular assist device (PVAD). The device simulation is carried out using fluid-structure interaction (FSI) modeling techniques within a computational framework that combines FEM for fluid mechanics and isogeometric analysis for structural mechanics modeling. The PVAD FSI simulations are performed under realistic conditions (i.e., flow speeds, pressure levels, boundary conditions, etc.), and account for the interaction of air, blood, and a thin structural membrane separating the two fluid subdomains. The shape optimization study is designed to reduce thrombotic risk, a major clinical problem in PVADs. Thrombotic risk is quantified in terms of particle residence time in the device blood chamber. Methods to compute particle residence time in the context of moving spatial domains are presented in a companion paper published in the same issue (Comput Mech, doi: 10.1007/s00466-013-0931-y, 2013). The surrogate management framework, a derivative-free pattern search optimization method that relies on surrogates for increased efficiency, is employed in this work. For the optimization study shown here, particle residence time is used to define a suitable cost or objective function, while four adjustable design optimization parameters are used to define the device geometry. The FSI-based optimization framework is implemented in a parallel computing environment, and deployed with minimal user intervention. Using five SEARCH/ POLL steps the optimization scheme identifies a PVAD design with significantly better throughput efficiency than the original device.

  16. Gas cluster ion beam assisted NiPt germano-silicide formation on SiGe

    NASA Astrophysics Data System (ADS)

    Ozcan, Ahmet S.; Lavoie, Christian; Alptekin, Emre; Jordan-Sweet, Jean; Zhu, Frank; Leith, Allen; Pfeifer, Brian D.; LaRose, J. D.; Russell, N. M.

    2016-04-01

    We report the formation of very uniform and smooth Ni(Pt)Si on epitaxially grown SiGe using Si gas cluster ion beam treatment after metal-rich silicide formation. The gas cluster ion implantation process was optimized to infuse Si into the metal-rich silicide layer and lowered the NiSi nucleation temperature significantly according to in situ X-ray diffraction measurements. This novel method which leads to more uniform films can also be used to control silicide depth in ultra-shallow junctions, especially for high Ge containing devices, where silicidation is problematic as it leads to much rougher interfaces.

  17. Spectrum of temperature pulsations of the melt in gas-assisted cutting with fiber laser

    NASA Astrophysics Data System (ADS)

    Dubrov, Alexander V.; Zavalov, Yury N.; Dubrov, Vladimir D.; Grezev, Anatoly N.; Grezev, Nikolay V.; Makarova, Elena S.; Dubrovin, Nickolay G.

    2012-09-01

    Measurements of the temperature behavior in the zone of action of the laser-radiation on the molten metal have been performed using multichannel pyrometer. Measurements were carried out for test cutting of a 3-mm mild-steel plate with several values of cutting speed and pressure of assist gas (oxygen), using an 1800-watt Ytterbium fiber laser. It is shown that fluctuations of temperature are related to local melt's surface deformations due to unequal radiation absorption; thus the noise spectrum of temperature fluctuations reflects turbulent surface deformation caused by gas jet and capillary waves. The maximum density of turbulent energy dissipation ε depends on cutting conditions: its value rises with increasing cutting velocity and oxygen pressure in a described range of parameters. The maximum of ε is localized near depth of (1.2…1.5) mm along the cutting front. We can distinguish the specific radiation pulsation spectrum of laser cutting from other processes of radiation affection to the sample, including unwanted degrading of the quality of technological operations. The spectrum of capillary waves on the melt's surface is formed under the effect of assisted gas jet and has a function of ω-3, ω is cycle frequency. The results of this investigation can be useful for the development of monitoring and quality-control systems for the laser-cutting process.

  18. Solar-assisted gas-energy water-heating feasibility for apartments

    NASA Technical Reports Server (NTRS)

    Davis, E. S.

    1975-01-01

    Studies of residential energy use, solar-energy technology for buildings, and the requirements for implementing technology in the housing industry led to a project to develop a solar water heater for apartments. A design study for a specific apartment was used to establish a solar water-heater cost model which is based on plumbing contractor bids and manufacturer estimates. The cost model was used to size the system to minimize the annualized cost of hot water. The annualized cost of solar-assisted gas-energy water heating is found to be less expensive than electric water heating but more expensive than gas water heating. The feasibility of a natural gas utility supplying the auxiliary fuel is evaluated. It is estimated that gas-utilizing companies will find it profitable to offer solar water heating as part of a total energy service option or on a lease basis when the price of new base-load supplies of natural gas reaches $2.50-$3.00 per million Btu.

  19. Optimization of ultrasound-assisted extraction of bioactive compounds from wild garlic (Allium ursinum L.).

    PubMed

    Tomšik, Alena; Pavlić, Branimir; Vladić, Jelena; Ramić, Milica; Brindza, Ján; Vidović, Senka

    2016-03-01

    Ultrasound-assisted extraction was used for extraction of bioactive compounds and for production of Allium ursinum liquid extract. The experiments were carried out according to tree level, four variables, face-centered cubic experimental design (FDC) combined with response surface methodology (RSM). Temperature (from 40 to 80 °C), ethanol concentration (from 30% to 70%), extraction time (from 40 to 80 min) and ultrasonic power (from 19.2 to 38.4 W/L) were investigated as independent variables in order to obtain the optimal conditions for extraction and to maximize the yield of total phenols (TP), flavonoids (TF) and antioxidant activity of obtained extracts. Experimental results were fitted to the second order polynomial model where multiple regression and analysis of variance were used to determine the fitness of the model and optimal condition for investigated responses. The predicted values of the TP (1.60 g GAE/100 g DW), TF (0.35 g CE/100 g DW), antioxidant activity, IC50 (0.71 mg/ml) and EY (38.1%) were determined at the optimal conditions for ultrasound assisted extraction: 80 °C temperature, 70% ethanol, 79.8 min and 20.06 W/L ultrasonic power. The predicted results matched well with the experimental results obtained using optimal extraction conditions which validated the RSM model with a good correlation.

  20. Total dissolved gas prediction and optimization in RiverWare

    SciTech Connect

    Stewart, Kevin M.; Witt, Adam M.; Hadjerioua, Boualem

    2015-09-01

    Management and operation of dams within the Columbia River Basin (CRB) provides the region with irrigation, hydropower production, flood control, navigation, and fish passage. These various system-wide demands can require unique dam operations that may result in both voluntary and involuntary spill, thereby increasing tailrace levels of total dissolved gas (TDG) which can be fatal to fish. Appropriately managing TDG levels within the context of the systematic demands requires a predictive framework robust enough to capture the operationally related effects on TDG levels. Development of the TDG predictive methodology herein attempts to capture the different modes of hydro operation, thereby making it a viable tool to be used in conjunction with a real-time scheduling model such as RiverWare. The end result of the effort will allow hydro operators to minimize system-wide TDG while meeting hydropower operational targets and constraints. The physical parameters such as spill and hydropower flow proportions, accompanied by the characteristics of the dam such as plant head levels and tailrace depths, are used to develop the empirically-based prediction model. In the broader study, two different models are developed a simplified and comprehensive model. The latter model incorporates more specific bubble physics parameters for the prediction of tailrace TDG levels. The former model is presented herein and utilizes an empirically based approach to predict downstream TDG levels based on local saturation depth, spillway and powerhouse flow proportions, and entrainment effects. Representative data collected from each of the hydro projects is used to calibrate and validate model performance and the accuracy of predicted TDG uptake. ORNL, in conjunction with IIHR - Hydroscience & Engineering, The University of Iowa, carried out model adjustments to adequately capture TDG levels with respect to each plant while maintaining a generalized model configuration. Validation results

  1. DUV ArF light source automated gas optimization for enhanced repeatability and availability

    NASA Astrophysics Data System (ADS)

    Aggarwal, Tanuj; O'Brien, Kevin

    2015-03-01

    The need for repeatable, reliable, and faster DUV ArF light source gas optimizations drove the development of Automated Gas Optimization (AGO). These automate the manual gas optimization procedure previously used to select the laser chamber gas pressures and in addition, bandwidth actuation settings, to deliver consistent performance and long gas lives, while maintaining stability and bounds on laser inputs. Manual gas optimization procedure requires at least two refills and an on-site visit by service personnel that can take over an hour to complete. This results in inconsistent light source performance, and sometimes unscheduled downtime. The key to AGO technology is the real-time estimation and monitoring of the laser's gas and bandwidth states, and automatic adjustment of gas pressure and bandwidth actuators until the states reach their specified targets, thus creating a closed loop. AGO executes on every refill, typically complete in less than 5 minutes, and collect performance data to allow long-term trending. They include built-in safety features and flexibility to allow future upgrades of light source features or performance tuning. Deployed in many lasers in the field, AGO has proved to be a dependable automation, yielding repeatable, fast, and reliable optimizations and valuable long-term trending data used to assess chamber performance

  2. Assessment of solar-assisted gas-fired heat pump systems

    NASA Technical Reports Server (NTRS)

    Lansing, F. L.

    1981-01-01

    As a possible application for the Goldstone Energy Project, the performance of a 10 ton heat pump unit using a hybrid solar gas energy source was evaluated in an effort to optimize the solar collector size. The heat pump system is designed to provide all the cooling and/or heating requirements of a selected office building. The system performance is to be augmented in the heating mode by utilizing the waste heat from the power cycle. A simplified system analysis is described to assess and compute interrrelationships of the engine, heat pump, and solar and building performance parameters, and to optimize the solar concentrator/building area ratio for a minimum total system cost. In addition, four alternative heating cooling systems, commonly used for building comfort, are described; their costs are compared, and are found to be less competitive with the gas solar heat pump system at the projected solar equipment costs.

  3. Assessment of solar-assisted gas-fired heat pump systems

    NASA Astrophysics Data System (ADS)

    Lansing, F. L.

    1981-06-01

    As a possible application for the Goldstone Energy Project, the performance of a 10 ton heat pump unit using a hybrid solar gas energy source was evaluated in an effort to optimize the solar collector size. The heat pump system is designed to provide all the cooling and/or heating requirements of a selected office building. The system performance is to be augmented in the heating mode by utilizing the waste heat from the power cycle. A simplified system analysis is described to assess and compute interrrelationships of the engine, heat pump, and solar and building performance parameters, and to optimize the solar concentrator/building area ratio for a minimum total system cost. In addition, four alternative heating cooling systems, commonly used for building comfort, are described; their costs are compared, and are found to be less competitive with the gas solar heat pump system at the projected solar equipment costs.

  4. Optimal design of perforating completion for gas well

    SciTech Connect

    Tang, Y.; Pan, Y.; Wang, Y.

    1995-10-01

    The productivity characteristics of perforated gas well are investigated for the first time under real conditions considering drilling damage, perforation compacted zone and anisotropy in this paper. A non-linear finite element model for non-Darcy flow in perforated gas reservoir is built to consider the effects of twelve factors on productivity ratio (PR) of perforated gas well. The nomographs for two cases are presented in this paper. Compared with previous works, the following results are found: (1) the effects of drilling damage and perforation diameter on PR of gas well are more remarkable than that in oil well; (2) any perforation phase may be the best or the worst as to perforating gas well, which depends on anisotropy, drawdown and that whether or not perforations are beyond drilling damage zone; (3) the increase in perforation length hardly improve PR of gas well when perforations have been beyond drilling damage zone. The new method is suggested to predict or determine the turbulent flow co-efficient D{prime}, total skin S, pseudo skin St{prime}, and individual skin factors (Sp, Sd, Sdp) in perforated gas well. The minimum underbalance required to obtain a zero perforating skin is discussed as well. Some drawbacks of the equation proposed by Tariq (SPE 20636) are analyzed and a new Reynold`s number criterion is established. The critical Reynold`s number for clean perforation is dependent on formation permeability. Based on this research, the principle and the program for optional design of perforating completion in gas well are highlighted. These new concepts, results and conclusions would be of importance to both gas well perforating and gas reservoir engineering.

  5. Microwave-assisted synthesis of SnO₂ nanorods for oxygen gas sensing at room temperature.

    PubMed

    Azam, Ameer; Habib, Sami S; Salah, Numan A; Ahmed, Faheem

    2013-01-01

    High-quality single-crystalline SnO₂ nanorods were synthesized using a microwave-assisted solution method. The nanorods were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), ultraviolet-visible and Raman spectroscopy, Brunauer-Emmett-Teller (BET), and electrical resistance measurements. The XRD pattern indicated the formation of single-phase SnO₂ nanorods with rutile structure. FE-SEM and TEM images revealed tetragonal nanorods of about 450-500 nm in length and 60-80 nm in diameter. The nanorods showed a higher BET surface area of 288 m²/g, much higher than that of previously reported work. The Raman scattering spectra indicated a typical rutile phase of the SnO₂. The absorption spectrum showed an absorption peak centered at 340 nm, and the band-gap value was found to be 3.64 eV. The gas-sensing properties of the SnO₂ nanorods for oxygen gas with different concentrations were measured at room temperature. It was found that the value of resistance increased with the increase in oxygen gas concentration in the test chamber. The SnO₂ nanorods exhibited high sensitivity and rapid response-recovery characteristics to oxygen gas, and could detect oxygen concentration as low as 1, 3, 5, and 10 ppm.

  6. Thermal Battery Operating Gas Atmosphere Control and Heat Transfer Optimization

    DTIC Science & Technology

    2012-09-01

    Approved for public release; distribution unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT The effects of gases and gas mixtures on global...highly effective in atmospheres of pure hydrogen and are potentially useful in mixtures of hydrogen and air. Barium chromate (BaCrO4) placed in contact...15 Figure 9. Gas gettering from a 79.6/20.4 volume percent hydrogen/air mixture

  7. Optimization of microwave-assisted extraction of polysaccharide from Psidium guajava L. fruits.

    PubMed

    Amutha Gnana Arasi, Michael Antony Samy; Gopal Rao, Manchineela; Bagyalakshmi, Janardanan

    2016-10-01

    This study deals with the optimization of microwave assisted extraction of polysaccharide from Psidium guajava L. fruit using Response surface methodology. To evaluate the effect of three independent variables, Water to plant material ratio, microwave power used for extraction and Irradiation time, central composite design has been employed. The yield is considered as dependent variable. The design model estimated the optimum yield of 6.81677% at 200W microwave power level, 3:1 water to plant material ratio and 20min of irradiation time. Three factors three levels Central composite design coupled with RSM was used to model the extraction process. ANOVA was performed to find the significance of the model. The polysaccharide extracted using microwave assisted extraction process was analyzed using FTIR Spectroscopy.

  8. Numerical simulations of CO2 -assisted gas production from hydrate reservoirs

    NASA Astrophysics Data System (ADS)

    Sridhara, P.; Anderson, B. J.; Myshakin, E. M.

    2015-12-01

    A series of experimental studies over the last decade have reviewed the feasibility of using CO2 or CO2+N2 gas mixtures to recover CH4 gas from hydrates deposits. That technique would serve the dual purpose of CO2 sequestration and production of CH4 while maintaining the geo-mechanical stability of the reservoir. In order to analyze CH4 production process by means of CO2 or CO2+N2 injection into gas hydrate reservoirs, a new simulation tool, Mix3HydrateResSim (Mix3HRS)[1], was previously developed to account for the complex thermodynamics of multi-component hydrate phase and to predict the process of CH4 substitution by CO2 (and N2) in the hydrate lattice. In this work, Mix3HRS is used to simulate the CO2 injection into a Class 2 hydrate accumulation characterized by a mobile aqueous phase underneath a hydrate bearing sediment. That type of hydrate reservoir is broadly confirmed in permafrost and along seashore. The production technique implies a two-stage approach using a two-well design, one for an injector and one for a producer. First, the CO2 is injected into the mobile aqueous phase to convert it into immobile CO2 hydrate and to initiate CH4 release from gas hydrate across the hydrate-water boundary (generally designating the onset of a hydrate stability zone). Second, CH4 hydrate decomposition is induced by the depressurization method at a producer to estimate gas production potential over 30 years. The conversion of the free water phase into the CO2 hydrate significantly reduces competitive water production in the second stage, thereby improving the methane gas production. A base case using only the depressurization stage is conducted to compare with enhanced gas production predicted by the CO2-assisted technique. The approach also offers a possibility to permanently store carbon dioxide in the underground formation to greater extent comparing to a direct injection of CO2 into gas hydrate sediment. Numerical models are based on the hydrate formations at the

  9. Study on Process Optimization of Cold Gas Spraying

    NASA Astrophysics Data System (ADS)

    Tabbara, H.; Gu, S.; McCartney, D. G.; Price, T. S.; Shipway, P. H.

    2011-03-01

    Cold gas dynamic spraying is a relatively new spray coating technique capable of depositing a variety of materials without extensive heating. As a result the inherent degradation of the powder particles found during traditional thermal spraying can be avoided. The simplicity of this technique is its most salient feature. High pressure gas is accelerated through a convergent-divergent nozzle up to supersonic velocity. The powder particles are carried to the substrate by the gas and on impact the particles deform at temperatures below their melting point. Computational modeling of thermal spray systems can provide thorough descriptions of the complex, compressible, particle-laden flow, and therefore can be utilized to strengthen understanding and allow technological progress to be made in a more systematic fashion. The computational fluid dynamic approach is adopted in this study to examine the effects of changing the nozzle cross-section shape, particle size and process gas type on the gas flow characteristics through a cold spray nozzle, as well as the spray distribution and particle velocity variation at the exit.

  10. Analysis and Methane Gas Separations Studies for City of Marsing, Idaho An Idaho National Laboratory Technical Assistance Program Study

    SciTech Connect

    Christopher Orme

    2012-08-01

    Introduction and Background Large amounts of methane in well water is a wide spread problem in North America. Methane gas from decaying biomass and oil and gas deposits escape into water wells typically through cracks or faults in otherwise non-porous rock strata producing saturated water systems. This methane saturated water can pose several problems in the delivery of drinking water. The problems range from pumps vapor locking (cavitating), to pump houses exploding. The City of Marsing requested Idaho National Laboratory (INL) to assist with some water analyses as well as to provide some engineering approaches to methane capture through the INL Technical Assistance Program (TAP). There are several engineering approaches to the removal of methane and natural gas from water sources that include gas stripping followed by compression and/or dehydration; membrane gas separators coupled with dehydration processes, membrane water contactors with dehydration processes.

  11. Label-Assisted Mass Spectrometry for the Acceleration of Reaction Discovery and Optimization

    PubMed Central

    Cabrera-Pardo, Jaime R.; Chai, David I.; Liu, Song; Mrksich, Milan; Kozmin, Sergey A.

    2014-01-01

    Identification of new reactions expands our knowledge of chemical reactivity and enables new synthetic applications. Accelerating the pace of this discovery process remains challenging. We describe a highly effective and simple platform for screening a large number of potential chemical reactions in order to discover and optimize previously unknown catalytic transformations thereby revealing new chemical reactivity. Our strategy is based on labeling one of the reactants with a polyaromatic chemical tag, which selectively undergoes photoionization-desorption process upon laser irradiation without the assistance of an external matrix and enables rapid mass spectrometric detection of any products originating from such labeled reactants in complex reaction mixtures without any chromatographic separation. This method was successfully employed for high-throughput discovery and subsequent optimization of two previously unknown benzannulation reactions. PMID:23609094

  12. Optimal Number of Thermoelectric Couples in a Heat Pipe Assisted Thermoelectric Generator for Waste Heat Recovery

    NASA Astrophysics Data System (ADS)

    Liu, Tongjun; Wang, Tongcai; Luan, Weiling; Cao, Qimin

    2017-01-01

    Waste heat recovery through thermoelectric generators is a promising way to improve energy conversion efficiency. This paper proposes a type of heat pipe assisted thermoelectric generator (HP-TEG) system. The expandable evaporator and condenser surface of the heat pipe facilitates the intensive assembly of thermoelectric (TE) modules to compose a compact device. Compared with a conventional layer structure thermoelectric generator, this system is feasible for the installment of more TE couples, thus increasing power output. To investigate the performance of the HP-TEG and the optimal number of TE couples, a theoretical model was presented and verified by experiment results. Further theoretical analysis results showed the performance of the HP-TEG could be further improved by optimizing the parameters, including the inlet air temperature, the thermal resistance of the heating section, and thermal resistance of the cooling structure. Moreover, applying a proper number of TE couples is important to acquire the best power output performance.

  13. Performance Evaluation and Optimal Detection of Relay-Assisted Diffusion-Based Molecular Communication with Drift.

    PubMed

    Tavakkoli, Nooshin; Azmi, Paeiz; Mokari, Nader

    2016-11-16

    In this paper, we consider a decode-and-forward (DF) relay-assisted diffusion-based molecular communication system inside one of the blood vessels of a human body with positive drift from transmitter to receiver. We use the normal approximation to the distribution of the number of received molecules and derive a closed-form expression for the end-toend bit error probability of the system. We then propose an optimization problem that aims at minimizing the bit error probability of the system and solve it at the receiver nanomachine by an algorithm based on the bisection method to determine the optimal detection threshold. Furthermore, we study the impact of the system parameters, such as drift velocity, position of the relay node and number of allocated molecules on the performance of the system. The numerical results show that with a constant molecular budget, DF relying strategy can considerably improve the system performance.

  14. Optimization of ultrasound assisted dispersive liquid-liquid microextraction of six antidepressants in human plasma using experimental design.

    PubMed

    Fernández, P; Taboada, V; Regenjo, M; Morales, L; Alvarez, I; Carro, A M; Lorenzo, R A

    2016-05-30

    A simple Ultrasounds Assisted-Dispersive Liquid Liquid Microextraction (UA-DLLME) method is presented for the simultaneous determination of six second-generation antidepressants in plasma by Ultra Performance Liquid Chromatography with Photodiode Array Detector (UPLC-PDA). The main factors that potentially affect to DLLME were optimized by a screening design followed by a response surface design and desirability functions. The optimal conditions were 2.5 mL of acetonitrile as dispersant solvent, 0.2 mL of chloroform as extractant solvent, 3 min of ultrasounds stirring and extraction pH 9.8.Under optimized conditions, the UPLC-PDA method showed good separation of antidepressants in 2.5 min and good linearity in the range of 0.02-4 μg mL(-1), with determination coefficients higher than 0.998. The limits of detection were in the range 4-5 ng mL(-1). The method precision (n=5) was evaluated showing relative standard deviations (RSD) lower than 8.1% for all compounds. The average recoveries ranged from 92.5% for fluoxetine to 110% for mirtazapine. The applicability of DLLME/UPLC-PDA was successfully tested in twenty nine plasma samples from antidepressant consumers. Real samples were analyzed by the proposed method and the results were successfully submitted to comparison with those obtained by a Liquid Liquid Extraction-Gas Chromatography - Mass Spectrometry (LLE-GC-MS) method. The results confirmed the presence of venlafaxine in most cases (19 cases), followed by sertraline (3 cases) and fluoxetine (3 cases) at concentrations below toxic levels.

  15. Environmentally Assisted Cracking of Drill Pipes in Deep Drilling Oil and Natural Gas Wells

    NASA Astrophysics Data System (ADS)

    Ziomek-Moroz, M.

    2012-06-01

    Corrosion fatigue (CF), hydrogen induced cracking (HIC) and sulfide stress cracking (SSC), or environmentally assisted cracking (EAC) have been identified as the most challenging causes of catastrophic brittle fracture of drill pipes during drilling operations of deep oil and natural gas wells. Although corrosion rates can be low and tensile stresses during service can be below the material yield stress, a simultaneous action between the stress and corrosive environment can cause a sudden brittle failure of a drill component. Overall, EAC failure consists of two stages: incubation and propagation. Defects, such as pits, second-phase inclusions, etc., serve as preferential sites for the EAC failure during the incubation stage. Deep oil and gas well environments are rich in chlorides and dissolved hydrogen sulfide, which are extremely detrimental to steels used in drilling operations. This article discusses catastrophic brittle fracture mechanisms due to EAC of drill pipe materials, and the corrosion challenges that need to be overcome for drilling ultra-deep oil and natural gas wells.

  16. Inert Gas Enhanced Laser-Assisted Purification of Platinum Electron-Beam-Induced Deposits.

    PubMed

    Stanford, Michael G; Lewis, Brett B; Noh, Joo Hyon; Fowlkes, Jason D; Rack, Philip D

    2015-09-09

    Electron-beam-induced deposition patterns, with composition of PtC5, were purified using a pulsed laser-induced purification reaction to erode the amorphous carbon matrix and form pure platinum deposits. Enhanced mobility of residual H2O molecules via a localized injection of inert Ar-H2 (4%) is attributed to be the reactive gas species for purification of the deposits. Surface purification of deposits was realized at laser exposure times as low as 0.1 s. The ex situ purification reaction in the deposit interior was shown to be rate-limited by reactive gas diffusion into the deposit, and deposit contraction associated with the purification process caused some loss of shape retention. To circumvent the intrinsic flaws of the ex situ anneal process, in situ deposition and purification techniques were explored that resemble a direct write atomic layer deposition (ALD) process. First, we explored a laser-assisted electron-beam-induced deposition (LAEBID) process augmented with reactive gas that resulted in a 75% carbon reduction compared to standard EBID. A sequential deposition plus purification process was also developed and resulted in deposition of pure platinum deposits with high fidelity and shape retention.

  17. Inert gas enhanced laser-assisted purification of platinum electron-beam-induced deposits

    SciTech Connect

    Stanford, Michael G.; Lewis, Brett B.; Noh, Joo Hyon; Fowlkes, Jason Davidson; Rack, Philip D.

    2015-06-30

    Electron-beam-induced deposition patterns, with composition of PtC5, were purified using a pulsed laser-induced purification reaction to erode the amorphous carbon matrix and form pure platinum deposits. Enhanced mobility of residual H2O molecules via a localized injection of inert Ar–H2 (4%) is attributed to be the reactive gas species for purification of the deposits. Surface purification of deposits was realized at laser exposure times as low as 0.1 s. The ex situ purification reaction in the deposit interior was shown to be rate-limited by reactive gas diffusion into the deposit, and deposit contraction associated with the purification process caused some loss of shape retention. To circumvent the intrinsic flaws of the ex situ anneal process, in situ deposition and purification techniques were explored that resemble a direct write atomic layer deposition (ALD) process. First, we explored a laser-assisted electron-beam-induced deposition (LAEBID) process augmented with reactive gas that resulted in a 75% carbon reduction compared to standard EBID. Lastly, a sequential deposition plus purification process was also developed and resulted in deposition of pure platinum deposits with high fidelity and shape retention.

  18. Inert gas enhanced laser-assisted purification of platinum electron-beam-induced deposits

    DOE PAGES

    Stanford, Michael G.; Lewis, Brett B.; Noh, Joo Hyon; ...

    2015-06-30

    Electron-beam-induced deposition patterns, with composition of PtC5, were purified using a pulsed laser-induced purification reaction to erode the amorphous carbon matrix and form pure platinum deposits. Enhanced mobility of residual H2O molecules via a localized injection of inert Ar–H2 (4%) is attributed to be the reactive gas species for purification of the deposits. Surface purification of deposits was realized at laser exposure times as low as 0.1 s. The ex situ purification reaction in the deposit interior was shown to be rate-limited by reactive gas diffusion into the deposit, and deposit contraction associated with the purification process caused some lossmore » of shape retention. To circumvent the intrinsic flaws of the ex situ anneal process, in situ deposition and purification techniques were explored that resemble a direct write atomic layer deposition (ALD) process. First, we explored a laser-assisted electron-beam-induced deposition (LAEBID) process augmented with reactive gas that resulted in a 75% carbon reduction compared to standard EBID. Lastly, a sequential deposition plus purification process was also developed and resulted in deposition of pure platinum deposits with high fidelity and shape retention.« less

  19. Optimize Flue Gas Settings to Promote Microalgae Growth in Photobioreactors via Computer Simulations

    PubMed Central

    He, Lian; Chen, Amelia B; Yu, Yi; Kucera, Leah; Tang, Yinjie

    2013-01-01

    Flue gas from power plants can promote algal cultivation and reduce greenhouse gas emissions1. Microalgae not only capture solar energy more efficiently than plants3, but also synthesize advanced biofuels2-4. Generally, atmospheric CO2 is not a sufficient source for supporting maximal algal growth5. On the other hand, the high concentrations of CO2 in industrial exhaust gases have adverse effects on algal physiology. Consequently, both cultivation conditions (such as nutrients and light) and the control of the flue gas flow into the photo-bioreactors are important to develop an efficient “flue gas to algae” system. Researchers have proposed different photobioreactor configurations4,6 and cultivation strategies7,8 with flue gas. Here, we present a protocol that demonstrates how to use models to predict the microalgal growth in response to flue gas settings. We perform both experimental illustration and model simulations to determine the favorable conditions for algal growth with flue gas. We develop a Monod-based model coupled with mass transfer and light intensity equations to simulate the microalgal growth in a homogenous photo-bioreactor. The model simulation compares algal growth and flue gas consumptions under different flue-gas settings. The model illustrates: 1) how algal growth is influenced by different volumetric mass transfer coefficients of CO2; 2) how we can find optimal CO2 concentration for algal growth via the dynamic optimization approach (DOA); 3) how we can design a rectangular on-off flue gas pulse to promote algal biomass growth and to reduce the usage of flue gas. On the experimental side, we present a protocol for growing Chlorella under the flue gas (generated by natural gas combustion). The experimental results qualitatively validate the model predictions that the high frequency flue gas pulses can significantly improve algal cultivation. PMID:24121788

  20. Optimization of a large integrated area development of gas fields offshore Sarawak, Malaysia

    SciTech Connect

    Inyang, S.E.; Tak, A.N.H.; Costello, G.

    1995-10-01

    Optimizations of field development plans are routine in the industry. The size, schedule and nature of the upstream gas supply project to the second Malaysia LNG (MLNG Dua) plant in Bintulu, Sarawak made the need for extensive optimizations critical to realizing a robust and cost effective development scheme, and makes the work of more general interest. The project comprises the upstream development of 11 offshore fields for gas supply to MLNG Dua plant at an initial plateau production of 7.8 million tons per year of LNG. The gas fields span a large geographical area in medium water depths (up to 440 ft), and contain gas reserves of a distinctly variable gas quality. This paper describes the project optimization efforts aimed to ensure an upstream gas supply system effectiveness of over 99% throughout the project life while maintaining high safety and environmental standards and also achieving an economic development in an era of low hydrocarbon prices. Fifty percent of the first of the three phases of this gas supply project has already been completed and the first gas from these fields is scheduled to be available by the end of 1995.

  1. Optimization of microwave-assisted enzymatic extraction of polysaccharides from the fruit of Schisandra chinensis Baill.

    PubMed

    Cheng, Zhenyu; Song, Haiyan; Yang, Yingjie; Liu, Yan; Liu, Zhigang; Hu, Haobin; Zhang, Yang

    2015-05-01

    A microwave-assisted enzymatic extraction (MAEE) method had been developed, which was optimized by response surface methodology (RSM) and orthogonal test design, to enhance the extraction of crude polysaccharides (CPS) from the fruit of Schisandra chinensis Baill. The optimum conditions were as follows: microwave irradiation time of 10 min, extraction pH of 4.21, extraction temperature of 47.58°C, extraction time of 3h and enzyme concentration of 1.5% (wt% of S. chinensis powder) for cellulase, papain and pectinase, respectively. Under these conditions, the extraction yield of CPS was 7.38 ± 0.21%, which was well in close agreement with the value predicted by the model. The three methods including heat-refluxing extraction (HRE), ultrasonic-assisted extraction (UAE) and enzyme-assisted extraction (EAE) for extracting CPS by RSM were further compared. Results indicated MAEE method had the highest extraction yields of CPS at lower temperature. It was indicated that the proposed approach in this study was a simple and efficient technique for extraction of CPS in S. chinensis Baill.

  2. Optimization of microwave assisted extraction (MAE) and soxhlet extraction of phenolic compound from licorice root.

    PubMed

    Karami, Zohreh; Emam-Djomeh, Zahra; Mirzaee, Habib Allah; Khomeiri, Morteza; Mahoonak, Alireza Sadeghi; Aydani, Emad

    2015-06-01

    In present study, response surface methodology was used to optimize extraction condition of phenolic compounds from licorice root by microwave application. Investigated factors were solvent (ethanol 80 %, methanol 80 % and water), liquid/solid ratio (10:1-25:1) and time (2-6 min). Experiments were designed according to the central composite rotatable design. The results showed that extraction conditions had significant effect on the extraction yield of phenolic compounds and antioxidant capacities. Optimal condition in microwave assisted method were ethanol 80 % as solvent, extraction time of 5-6 min and liquid/solid ratio of 12.7/1. Results were compared with those obtained by soxhlet extraction. In soxhlet extraction, Optimum conditions were extraction time of 6 h for ethanol 80 % as solvent. Value of phenolic compounds and extraction yield of licorice root in microwave assisted (MAE), and soxhlet were 47.47 mg/g and 16.38 %, 41.709 mg/g and 14.49 %, respectively. These results implied that MAE was more efficient extracting method than soxhlet.

  3. Shape Optimization of the Assisted Bi-directional Glenn surgery for stage-1 single ventricle palliation

    NASA Astrophysics Data System (ADS)

    Verma, Aekaansh; Shang, Jessica; Esmaily-Moghadam, Mahdi; Wong, Kwai; Marsden, Alison

    2016-11-01

    Babies born with a single functional ventricle typically undergo three open-heart surgeries starting as neonates. The first of these stages (BT shunt or Norwood) has the highest mortality rates of the three, approaching 30%. Proceeding directly to a stage-2 Glenn surgery has historically demonstrated inadequate pulmonary flow (PF) & high mortality. Recently, the Assisted Bi-directional Glenn (ABG) was proposed as a promising means to achieve a stable physiology by assisting the PF via an 'ejector pump' from the systemic circulation. We present preliminary parametrization and optimization results for the ABG geometry, with the goal of increasing PF. To limit excessive pressure increases in the Superior Vena Cava (SVC), the SVC pressure is included as a constraint. We use 3-D finite element flow simulations coupled with a single ventricle lumped parameter network to evaluate PF & the pressure constraint. We employ a derivative free optimization method- the Surrogate Management Framework, in conjunction with the OpenDIEL framework to simulate multiple simultaneous evaluations. Results show that nozzle diameter is the most important design parameter affecting ABG performance. The application of these results to patient specific situations will be discussed. This work was supported by an NSF CAREER award (OCI1150184) and by the XSEDE National Computing Resource.

  4. Optimal design of a gas transmission network: A case study of the Turkish natural gas pipeline network system

    NASA Astrophysics Data System (ADS)

    Gunes, Ersin Fatih

    Turkey is located between Europe, which has increasing demand for natural gas and the geographies of Middle East, Asia and Russia, which have rich and strong natural gas supply. Because of the geographical location, Turkey has strategic importance according to energy sources. To supply this demand, a pipeline network configuration with the optimal and efficient lengths, pressures, diameters and number of compressor stations is extremely needed. Because, Turkey has a currently working and constructed network topology, obtaining an optimal configuration of the pipelines, including an optimal number of compressor stations with optimal locations, is the focus of this study. Identifying a network design with lowest costs is important because of the high maintenance and set-up costs. The quantity of compressor stations, the pipeline segments' lengths, the diameter sizes and pressures at compressor stations, are considered to be decision variables in this study. Two existing optimization models were selected and applied to the case study of Turkey. Because of the fixed cost of investment, both models are formulated as mixed integer nonlinear programs, which require branch and bound combined with the nonlinear programming solution methods. The differences between these two models are related to some factors that can affect the network system of natural gas such as wall thickness, material balance compressor isentropic head and amount of gas to be delivered. The results obtained by these two techniques are compared with each other and with the current system. Major differences between results are costs, pressures and flow rates. These solution techniques are able to find a solution with minimum cost for each model both of which are less than the current cost of the system while satisfying all the constraints on diameter, length, flow rate and pressure. These results give the big picture of an ideal configuration for the future state network for the country of Turkey.

  5. Optimizing Natural Gas Networks through Dynamic Manifold Theory and a Decentralized Algorithm: Belgium Case Study

    NASA Astrophysics Data System (ADS)

    Koch, Caleb; Winfrey, Leigh

    2014-10-01

    Natural Gas is a major energy source in Europe, yet political instabilities have the potential to disrupt access and supply. Energy resilience is an increasingly essential construct and begins with transmission network design. This study proposes a new way of thinking about modelling natural gas flow. Rather than relying on classical economic models, this problem is cast into a time-dependent Hamiltonian dynamics discussion. Traditional Natural Gas constraints, including inelastic demand and maximum/minimum pipe flows, are portrayed as energy functions and built into the dynamics of each pipe flow. Doing so allows the constraints to be built into the dynamics of each pipeline. As time progresses in the model, natural gas flow rates find the minimum energy, thus the optimal gas flow rates. The most important result of this study is using dynamical principles to ensure the output of natural gas at demand nodes remains constant, which is important for country to country natural gas transmission. Another important step in this study is building the dynamics of each flow in a decentralized algorithm format. Decentralized regulation has solved congestion problems for internet data flow, traffic flow, epidemiology, and as demonstrated in this study can solve the problem of Natural Gas congestion. A mathematical description is provided for how decentralized regulation leads to globally optimized network flow. Furthermore, the dynamical principles and decentralized algorithm are applied to a case study of the Fluxys Belgium Natural Gas Network.

  6. Surface Defects Control for ZnO Nanorods Synthesized Through a Gas-Assisted Hydrothermal Process

    NASA Astrophysics Data System (ADS)

    Zhao, Limin; Shu, Changhua; Jia, Zhengfeng; Wang, Changzheng

    2017-01-01

    Oxygen vacancies in crystal have an important impact on the electronic properties of zinc oxide (ZnO). In this paper, ZnO nanorods with rich oxygen vacancies were prepared through a novel gas-assisted hydrothermal growth process. X-ray diffraction data showed that single-phase ZnO with the wurtzite crystal structure was obtained and the crystallite size decreased as the reaction atmosphere pressure increased. The oxygen vacancies of ZnO were confirmed using x-ray photoelectron spectroscopy and photoluminescence spectroscopy. The results showed that the concentration of oxygen vacancies could be regulated by both the atmosphere pressure and the atmosphere properties. The oxygen vacancies in ZnO samples were reduced when the pressure increase in the hydrogen reaction environment (reducing atmosphere) and the oxygen vacancies in ZnO samples were increased when the pressure increased in the oxygen reaction environment (oxidizing atmosphere).

  7. Optimization problems in natural gas transportation systems. A state-of-the-art review

    SciTech Connect

    Ríos-Mercado, Roger Z.; Borraz-Sánchez, Conrado

    2015-03-24

    Our paper provides a review on the most relevant research works conducted to solve natural gas transportation problems via pipeline systems. The literature reveals three major groups of gas pipeline systems, namely gathering, transmission, and distribution systems. In this work, we aim at presenting a detailed discussion of the efforts made in optimizing natural gas transmission lines.There is certainly a vast amount of research done over the past few years on many decision-making problems in the natural gas industry and, specifically, in pipeline network optimization. In this work, we present a state-of-the-art survey focusing on specific categories that include short-term basis storage (line-packing problems), gas quality satisfaction (pooling problems), and compressor station modeling (fuel cost minimization problems). We also discuss both steady-state and transient optimization models highlighting the modeling aspects and the most relevant solution approaches known to date. Although the literature on natural gas transmission system problems is quite extensive, this is, to the best of our knowledge, the first comprehensive review or survey covering this specific research area on natural gas transmission from an operations research perspective. Furthermore, this paper includes a discussion of the most important and promising research areas in this field. Hence, our paper can serve as a useful tool to gain insight into the evolution of the many real-life applications and most recent advances in solution methodologies arising from this exciting and challenging research area of decision-making problems.

  8. Naturally fractured tight gas reservoir detection optimization. Final report

    SciTech Connect

    1997-11-19

    This DOE-funded research into seismic detection of natural fractures is one of six projects within the DOE`s Detection and Analysis of Naturally Fractured Gas Reservoirs Program, a multidisciplinary research initiative to develop technology for prediction, detection, and mapping of naturally fractured gas reservoirs. The demonstration of successful seismic techniques to locate subsurface zones of high fracture density and to guide drilling orientation for enhanced fracture permeability will enable better returns on investments in the development of the vast gas reserves held in tight formations beneath the Rocky Mountains. The seismic techniques used in this project were designed to capture the azimuthal anisotropy within the seismic response. This seismic anisotropy is the result of the symmetry in the rock fabric created by aligned fractures and/or unequal horizontal stresses. These results may be compared and related to other lines of evidence to provide cross-validation. The authors undertook investigations along the following lines: Characterization of the seismic anisotropy in three-dimensional, P-wave seismic data; Characterization of the seismic anisotropy in a nine-component (P- and S-sources, three-component receivers) vertical seismic profile; Characterization of the seismic anisotropy in three-dimensional, P-to-S converted wave seismic data (P-wave source, three-component receivers); and Description of geological and reservoir-engineering data that corroborate the anisotropy: natural fractures observed at the target level and at the surface, estimation of the maximum horizontal stress in situ, and examination of the flow characteristics of the reservoir.

  9. Buffer gas-assisted four-wave mixing resonances in alkali vapor excited by a single cw laser

    NASA Astrophysics Data System (ADS)

    Shmavonyan, Svetlana; Khanbekyan, Aleksandr; Khanbekyan, Alen; Mariotti, Emilio; Papoyan, Aram V.

    2016-12-01

    We report the observation of a fluorescence peak appearing in dilute alkali (Rb, Cs) vapor in the presence of a buffer gas when the cw laser radiation frequency is tuned between the Doppler-broadened hyperfine transition groups of an atomic D2 line. Based on steep laser radiation intensity dependence above the threshold and spectral composition of the observed features corresponding to atomic resonance transitions, we have attributed these features to the buffer gas-assisted four-wave mixing process.

  10. Response surface methodology to optimize enzyme-assisted aqueous extraction of maize germ oil.

    PubMed

    Shende, Deepika; Sidhu, Gagandeep Kaur

    2016-08-01

    The present study was aimed at optimizing the enzyme assisted aqueous extraction (EAAE) process for extraction of maize germ oil. The different EAAE process parameter viz., pH of the slurry, seed to water ratio, the temperature of incubation and time of hydrolysis were optimized for improving oil recovery and oil quality. The combined effect of independent variables on recovery of oil, time taken for oil extraction and various quality parameters were studied using response surface methodology. The designed experimental runs were conducted to obtain the optimal conditions as 5.85 pH of slurry, 1:6.92 seed to water ratio, 45.12 °C temperature of incubation and 1 h time of hydrolysis. Oil extracted under these conditions was light yellowish in color and had a pleasant nutty taste, with maximum oil recovery of 70 %. The extraction variables viz., pH of slurry, seed to water ratio, the temperature of incubation had a significant effect on recovery of oil and various quality characteristics, however the time of hydrolysis had a non significant effect.

  11. Fusion of optimized indicators from Advanced Driver Assistance Systems (ADAS) for driver drowsiness detection.

    PubMed

    Daza, Iván García; Bergasa, Luis Miguel; Bronte, Sebastián; Yebes, Jose Javier; Almazán, Javier; Arroyo, Roberto

    2014-01-09

    This paper presents a non-intrusive approach for monitoring driver drowsiness using the fusion of several optimized indicators based on driver physical and driving performance measures, obtained from ADAS (Advanced Driver Assistant Systems) in simulated conditions. The paper is focused on real-time drowsiness detection technology rather than on long-term sleep/awake regulation prediction technology. We have developed our own vision system in order to obtain robust and optimized driver indicators able to be used in simulators and future real environments. These indicators are principally based on driver physical and driving performance skills. The fusion of several indicators, proposed in the literature, is evaluated using a neural network and a stochastic optimization method to obtain the best combination. We propose a new method for ground-truth generation based on a supervised Karolinska Sleepiness Scale (KSS). An extensive evaluation of indicators, derived from trials over a third generation simulator with several test subjects during different driving sessions, was performed. The main conclusions about the performance of single indicators and the best combinations of them are included, as well as the future works derived from this study.

  12. Optimization of ultrasound-assisted extraction of charantin from Momordica charantia fruits using response surface methodology

    PubMed Central

    Ahamad, Javed; Amin, Saima; Mir, Showkat R.

    2015-01-01

    Background: Momordica charantia Linn. (Cucurbitaceae) fruits are well known for their beneficial effects in diabetes that are often attributed to its bioactive component charantin. Objective: The aim of the present study is to develop and optimize an efficient protocol for the extraction of charantin from M. charantia fruits. Materials and Methods: Response surface methodology (RSM) was used for the optimization of ultrasound-assisted extraction (UAE) conditions. RSM was based on a three-level, three-variable Box-Behnken design (BBD), and the studied variables included solid to solvent ratio, extraction temperature, and extraction time. Results: The optimal conditions predicted by the BBD were: UAE with methanol: Water (80:20, v/v) at 46°C for 120 min with solid to solvent ratio of 1:26 w/v, under which the yield of charantin was 3.18 mg/g. Confirmation trials under slightly adjusted conditions yielded 3.12 ± 0.14 mg/g of charantin on dry weight basis of fruits. The result of UAE was also compared with Soxhlet extraction method and UAE was found 2.74-fold more efficient than the Soxhlet extraction for extracting charantin. Conclusions: A facile UAE protocol for a high extraction yield of charantin was developed and validated. PMID:26681889

  13. Stacking optimization of compressor blades of gas turbine engines

    NASA Technical Reports Server (NTRS)

    Cheu, Tsu-Chien

    1990-01-01

    A procedure is presented to obtain optimal designs of axial compressor blades with structural design constraints. Coefficients of the polynomials defining the circumferential tilting angles and the axial leaning distances of the airfoil cross sections from the initial design geometry are used as design variables. The compressor blades are modeled by 20-node solid elements. An efficient finite element method is developed for modal analysis and sensitivity analysis with respect to the design variables. Based on this information, a sequential linear programming method is applied to calculate the required change of geometry for the desired structural design constraints.

  14. Naturally fractured tight gas reservoir detection optimization. Quarterly report, January 1, 1997--March 31, 1997

    SciTech Connect

    1998-04-01

    This document contains the quarterly report dated January 1-March 31, 1997 for the Naturally Fractured Tight Gas Reservoir Detection Optimization project. Topics covered in this report include AVOA modeling using paraxial ray tracing, AVOA modeling for gas- and water-filled fractures, 3-D and 3-C processing, and technology transfer material. Several presentations from a Geophysical Applications Workshop workbook, workshop schedule, and list of workshop attendees are also included.

  15. Preconcentration modeling for the optimization of a micro gas preconcentrator applied to environmental monitoring.

    PubMed

    Camara, Malick; Breuil, Philippe; Briand, Danick; Viricelle, Jean-Paul; Pijolat, Christophe; de Rooij, Nico F

    2015-04-21

    This paper presents the optimization of a micro gas preconcentrator (μ-GP) system applied to atmospheric pollution monitoring, with the help of a complete modeling of the preconcentration cycle. Two different approaches based on kinetic equations are used to illustrate the behavior of the micro gas preconcentrator for given experimental conditions. The need for high adsorption flow and heating rate and for low desorption flow and detection volume is demonstrated in this paper. Preliminary to this optimization, the preconcentration factor is discussed and a definition is proposed.

  16. MW-assisted synthesis of carboxymethyl tamarind kernel polysaccharide-g-polyacrylonitrile: optimization and characterization.

    PubMed

    Meenkashi; Ahuja, Munish; Verma, Purnima

    2014-11-26

    Microwave-assisted synthesis of graft copolymer of carboxymethyl tamarind seed polysaccharide and polyacrylonitrile was carried out. The effect of formulation and process variables on grafting efficiency of carboxymethyl tamarind kernel polysaccharide-g-poly(acrylonitrile) was studied using response surface methodology. The results revealed that the significant factors affecting grafting efficiency were concentrations of ammonium persulphate, acrylonitrile and interaction effects of ammonium persulphate and acrylonitrile concentrations. The optimal calculated parameters were found to be microwave exposure time-99.48 s, microwave exposure power-160 W, concentration of acrylonitrile-0.10% (w/v), concentration of ammonium persulphate--40 mmol/l, which provided graft copolymer with grafting efficiency of 96%. The formation of graft copolymer was confirmed by FT-IR studies and validated by scanning electron micrographs. Thermogravimetric analysis indicated higher thermal stability of graft copolymer and X-ray diffraction study revealed increase in crystallinity on graft polymerization. Further, the graft copolymer showed pH dependant swelling.

  17. Optimization of ion-assisted ITO films by design of experiment

    NASA Astrophysics Data System (ADS)

    Schwyn Thöny, Silvia; Buchholz, Jürgen; Waldner, Stephan

    2011-09-01

    In this work we want to demonstrate how the methodology of Design of Experiment (DOE) can be used for the development of ion-assisted ITO films deposited at low temperatures. The optimization method allows us to identify the process parameters, which yield films with high transmittance and low resistivity. The article will show the results obtained for transmittance and resistivity. Furthermore, the dispersion of the refractive index and the extinction coefficient will be determined as well as the surface roughness. In ITO there is a trade-off between transmittance / absorbance and sheet resistance. Virtually absorption free films could be obtained with a resistivity of 3.2 μΩm, whereas the lowest resistivity (2.7 μΩm) yielded a transmittance, which was reduced by a few percent.

  18. Diagonal slice spectrum assisted optimal scale morphological filter for rolling element bearing fault diagnosis

    NASA Astrophysics Data System (ADS)

    Li, Yifan; Liang, Xihui; Zuo, Ming J.

    2017-02-01

    This paper presents a novel signal processing scheme, diagonal slice spectrum assisted optimal scale morphological filter (DSS-OSMF), for rolling element fault diagnosis. In this scheme, the concept of quadratic frequency coupling (QFC) is firstly defined and the ability of diagonal slice spectrum (DSS) in detection QFC is derived. The DSS-OSMF possesses the merits of depressing noise and detecting QFC. It can remove fault independent frequency components and give a clear representation of fault symptoms. A simulated vibration signal and experimental vibration signals collected from a bearing test rig are employed to evaluate the effectiveness of the proposed method. Results show that the proposed method has a superior performance in extracting fault features of defective rolling element bearing. In addition, comparisons are performed between a multi-scale morphological filter (MMF) and a DSS-OSMF. DSS-OSMF outperforms MMF in detection of an outer race fault and a rolling element fault of a rolling element bearing.

  19. Multiparticle quantum Szilard engine with optimal cycles assisted by a Maxwell's demon

    NASA Astrophysics Data System (ADS)

    Cai, C. Y.; Dong, H.; Sun, C. P.

    2012-03-01

    We present a complete-quantum description of a multiparticle Szilard engine that consists of a working substance and a Maxwell's demon. The demon is modeled as a multilevel quantum system with specific quantum control, and the working substance consists of identical particles obeying Bose-Einstein or Fermi-Dirac statistics. In this description, a reversible scheme to erase the demon's memory by a lower-temperature heat bath is used. We demonstrate that (1) the quantum control of the demon can be optimized for a single-particle Szilard engine so that the efficiency of the demon-assisted thermodynamic cycle could reach the Carnot cycle's efficiency and (2) the low-temperature behavior of the working substance is very sensitive to the quantum statistics of the particles and the insertion position of the partition.

  20. Optimal heat pumps for solar-assisted heat-pump systems

    NASA Astrophysics Data System (ADS)

    Catan, M. A.

    Work at Brookhaven National Laboratory (BNL) investigates the design of optimal heat pumps for solar assisted heat pump (SAPH) systems. Heat pump designs suitable for two generic systems, identified in the course of recent analytical work, are being studied. These are series SAHP systems operating at evaporator temperatures in the -5 to 10 C range and those operating at evaporator temperatures in the 10 to 35 C range. A heat pump simulator has been constructed with liquid based source subsystem and two load subsystems, one for testing air cooled condensers and one for testing water cooled condensers. Heat pumps tested were composed of various components including several types of variable and fixed capacity compressors, two types of expansion devices, and heat exchangers varying in size and type.

  1. Process optimization and analysis of microwave assisted extraction of pectin from dragon fruit peel.

    PubMed

    Thirugnanasambandham, K; Sivakumar, V; Prakash Maran, J

    2014-11-04

    Microwave assisted extraction (MAE) technique was employed for the extraction of pectin from dragon fruit peel. The extracting parameters were optimized by using four-variable-three-level Box-Behnken design (BBD) coupled with response surface methodology (RSM). RSM analysis indicated good correspondence between experimental and predicted values. 3D response surface plots were used to study the interactive effects of process variables on extraction of pectin. The optimum extraction conditions for the maximum yield of pectin were power of 400 W, temperature of 45 °C, extracting time of 20 min and solid-liquid ratio of 24 g/mL. Under these conditions, 7.5% of pectin was extracted.

  2. Process optimization of ultrasound-assisted curcumin nanoemulsions stabilized by OSA-modified starch.

    PubMed

    Abbas, Shabbar; Bashari, Mohanad; Akhtar, Waseem; Li, Wei Wei; Zhang, Xiaoming

    2014-07-01

    This study reports on the process optimization of ultrasound-assisted, food-grade oil-water nanoemulsions stabilized by modified starches. In this work, effects of major emulsification process variables including applied power in terms of power density and sonication time, and formulation parameters, that is, surfactant type and concentration, bioactive concentration and dispersed-phase volume fraction were investigated on the mean droplet diameter, polydispersity index and charge on the emulsion droplets. Emulsifying properties of octenyl succinic anhydride modified starches, that is, Purity Gum 2000, Hi-Cap 100 and Purity Gum Ultra, and the size stability of corresponding emulsion droplets during the 1 month storage period were also investigated. Results revealed that the smallest and more stable nanoemulsion droplets were obtained when coarse emulsions treated at 40% of applied power (power density: 1.36 W/mL) for 7 min, stabilized by 1.5% (w/v) Purity Gum Ultra. Optimum volume fraction of oil (medium chain triglycerides) and the concentration of bioactive compound (curcumin) dispersed were 0.05 and 6 mg/mL oil, respectively. These results indicated that the ultrasound-assisted emulsification could be successfully used for the preparation of starch-stabilized nanoemulsions at lower temperatures (40-45 °C) and reduced energy consumption.

  3. Numerical simulation of an industrial microwave assisted filter dryer: criticality assessment and optimization.

    PubMed

    Leonelli, Cristina; Veronesi, Paolo; Grisoni, Fabio

    2007-01-01

    Industrial-scale filter dryers, equipped with one or more microwave input ports, have been modelled with the aim of detecting existing criticalities, proposing possible solutions and optimizing the overall system efficiency and treatment homogeneity. Three different loading conditions have been simulated, namely the empty applicator, the applicator partially loaded by both a high-loss and low loss load whose dielectric properties correspond to the one measured on real products. Modeling results allowed for the implementation of improvements to the original design such as the insertion of a wave guide transition and a properly designed pressure window, modification of the microwave inlet's position and orientation, alteration of the nozzles' geometry and distribution, and changing of the cleaning metallic torus dimensions and position. Experimental testing on representative loads, as well as in production sites, allowed for the confirmation of the validity of the implemented improvements, thus showing how numerical simulation can assist the designer in removing critical features and improving equipment performances when moving from conventional heating to hybrid microwave-assisted processing.

  4. Are there optimal numbers of oocytes, spermatozoa and embryos in assisted reproduction?

    PubMed Central

    Milachich, Tanya; Shterev, Atanas

    2016-01-01

    The aim of this overview is to discuss the current information about the search for the optimum yield of gametes in assisted reproduction, as one of the major pillars of IVF success. The first topic is focused on the number of male gametes and the possible impact of some genetic traits on these parameters. The number of spermatozoa did not seem to be crucial when there is no severe male factor of infertility. Genetic testing prior to using those sperm cells is very important. Different methods were applied in order to elect the "best" spermatozoa according to specific indications. The next problem discussed is the importance of the number of oocytes collected. Several studies have agreed that "15 oocytes is the perfect number," as the number of mature oocytes is more important. However, if elective single embryo transfer is performed, the optimal number of oocytes will enable a proper embryo selection. The third problem discussed concerns fertility preservation. Many educational programs promote and encourage procreation at maternal ages between 20-35 years, since assisted reproduction is unable to fully overcome the effects of female aging and fertility loss after that age. It is also strongly recommended to ensure a reasonable number of cryopreserved mature oocytes, preferably in younger ages (<35), for which an average of two stimulation cycles are likely required. For embryo cryopreservation, the "freeze all" strategy suggests the vitrification of good embryos, therefore quality is prior to number and patient recruitment for this strategy should be performed cautiously. PMID:27584608

  5. Gas pressure sintering of silicon nitride to optimize fracture toughness

    SciTech Connect

    Tiegs, T.N.; Nunn, S.D.; Beavers, T.M.; Menchhofer, P.A.; Barker, D.L.; Coffey, D.W.

    1995-06-01

    Gas-pressure sintering (GPS) can be used to densify silicon nitride containing a wide variety of sintering additives. Parameters affecting the sintering behavior include densification temperature, densification time, grain growth temperature, grain growth time and heating rates. The Si{sub 3}N{sub 4}-6% Y{sub 2}O{sub 3}-2% A1{sub 2}O{sub 3} samples sintered to high densities at all conditions used in the present study, whereas the Si{sub 3}N{sub 4}-Sr{sub 2}La{sub 4}Yb{sub 4}(SiO{sub 4}){sub 6}O{sub 2} samples required the highest temperatures and longest times to achieve densities {ge}98 % T. D. The main effect on the fracture toughness for Si{sub 3}N{sub 4}-6% Y{sub 2}O{sub 3}-2% A1{sub 2}O{sub 3} samples was the use of a lower densification temperature, which was 1900C in the present study. For the Si{sub 3}N{sub 4}-Sr{sub 2}La{sub 4}Yb{sub 4}SiO4{sub 4}){sub 6}O{sub 2} composition, fracture toughness was sensitive to and improved by a slower heating rate (10c/min), a lower densification temperature (1900`), a higher grain growth temperature (2000C), and a longer grain growth time (2 h).

  6. Flow and heat transfer characteristics of assisting gas impingining onto an alumina coated hole in relation to laser drilling

    NASA Astrophysics Data System (ADS)

    Shuja, S. Z.; Yilbas, B. S.

    2014-07-01

    Flow and heat transfer characteristics of the assisting gas impinging onto the coated holes are investigated in relation to the laser drilling process. The alumina coating with thickness of 250 μm is considered at the surface of the carbon steel substrate. Three cases are considered by incorporating different locations of the coating on the carbon steel. These cases include coating at the top of the workpiece, coating at the bottom of the workpiece, and coating both at the top and at the bottom of the workpiece. A no-coating situation of the hole is also presented for the comparison reason. To resemble the laser drilling process, the wall temperature of the coating and the carbon steel substrate is kept at the melting temperatures during the simulations. A numerical scheme incorporating the control volume approach is introduced and the Reynolds stress turbulence model is used to account for the turbulence effect of the impinging assisting gas. An experiment is carried out in line with the simulation conditions to examine the morphological changes at the coating-carbon steel interface. It is found that the assisting gas temperature exceeds the melting temperature of the steel substrate along the coating thickness and as the assisting gas progresses further into the hole, heat transfer from the assisting gas to the hole wall takes place. This, in turn, increases thermal erosion at the hole wall in the vicinity of the coating-steel substrate interface. The Nusselt number and the skin friction attain large values along the coating thickness in the hole.

  7. Process optimization for ultrasonic vibration assisted polishing of micro-structured surfaces on super hard material

    NASA Astrophysics Data System (ADS)

    Sun, Zhiyuan; Guo, Bing; Rao, Zhimin; Zhao, Qingliang

    2014-08-01

    In consideration of the excellent property of SiC, the ground micro-structured surface quality is hard to meet the requirement - consequently the ultrasonic vibration assisted polishing (UVAP) of micro-structures of molds is proposed in this paper. Through the orthogonal experiment, the parameters of UVAP of micro-structures were optimized. The experimental results show that, abrasive polishing process, the effect of the workpiece feed rate on the surface roughness (Ra), groove tip radius (R) and material removal rate (MRR) of micro-structures is significant. While, the UVAP, the most significant effect factor for Ra, R and MRR is the ultrasonic amplitude of the ultrasonic vibration. In addition, within the scope of the polishing process parameters selected by preliminary experiments, ultrasonic amplitude of 2.5μm, polishing force of 0.5N, workpiece feed rate of 5 mm·min-1, polishing wheel rotational speed of 50rpm, polishing time of 35min, abrasive size of 100nm and the polishing liquid concentration of 15% is the best technology of UVAP of micro-structures. Under the optimal parameters, the ground traces on the micro-structured surface were removed efficiently and the integrity of the edges of the micro-structure after grinding was maintained efficiently.

  8. Optimal control of FES-assisted standing up in paraplegia using genetic algorithms.

    PubMed

    Davoodi, R; Andrews, B J

    1999-11-01

    A practical system for Functional Electrical Stimulation (FES) assisted standing up in paraplegia should involve only a minimum of manual set up and tuning. An improved tuning method, using a genetic algorithm (GA) is proposed and demonstrated using computer simulation. Specifically, the GA adjusts the parameters of fuzzy logic (FL) and gain-scheduling proportional integral derivative (GS-PID) controllers that electrically stimulate the hip and knee musculature during the sit-stand maneuver. These new GA designed controllers were found to be effective in coordinating volitional and FES control according to formulated criteria. The latter was based on the deviations from a desired trajectory of the knee and hip joints and the magnitude of the voluntary upper body forces. The magnitude of the average arm forces were slightly higher when compared with the open-loop maximal stimulation of the hip and knee musculature; however, the terminal knee velocities were significantly reduced to less than 10 degrees /s. For practical implementation, the number of trials required to optimize the FL and GS-PID controllers can be reduced by a proposed pre-training procedure using a computer model scaled to the individual. The GA designed controllers remain near optimal provided the model-subject mismatch is small.

  9. Optimal dye concentration and power density for laser-assisted vascular anatomosis (LAVA)

    NASA Astrophysics Data System (ADS)

    Ren, Zhen; Furnary, Anthony; Xie, Hua; Lagerquist, Kathryn A.; Burke, Allen; Prahl, Scott A.; Gregory, Kenton W.

    2003-06-01

    Laser tissue welding with albumin solder/indocyanine green (ICG) dye is an effective technique in surgical reconstruction. This study was carried out in vitro to find optimal ICG concentration and power density (PD) in laser assisted vascular anastomosis (LAVA). Fresh porcine carotid arteries incised into vascular strips (n = 120) were welded by diode laser in end-to-end with 50% albumin solder of 0.01, 0.1, and 1.0 mM ICG and at power density of 27.7, 56.7, and 76.9 W/cm2. Direct temperature was measured by inserting thermocouples outside and inside vessel. Tensile strength was tested immediately and histological study was performed. Temperature (both outside and inside vessel) significantly gradually decreasd (p < 0.01) with the increasing of ICG concentration at PD 56.7 W/cm2. Tensile strength significantly gradually decreased (p < 0.01) with increasing of ICG concentration at PD 56.7 W/cm2. Histological study showed minimal thermal injury limited to adventitia of vessels and no appreciable difference in all groups. We find that ICG concentration within solder is most important factor affecting both tissue temperature and tensile strength during laser vessel welding. The optimal balance between stronger strength and minimal thermal injury of vessel may be achieved primarily by using PD 56.7 W/cm2 at 0.01 mM ICG within solder during LAVA.

  10. Magnetically assisted chemical separation (MACS) process: Preparation and optimization of particles for removal of transuranic elements

    SciTech Connect

    Nunez, L.; Kaminski, M.; Bradley, C.; Buchholz, B.A.; Aase, S.B.; Tuazon, H.E.; Vandegrift, G.F.; Landsberger, S.

    1995-05-01

    The Magnetically Assisted Chemical Separation (MACS) process combines the selectivity afforded by solvent extractants with magnetic separation by using specially coated magnetic particles to provide a more efficient chemical separation of transuranic (TRU) elements, other radionuclides, and heavy metals from waste streams. Development of the MACS process uses chemical and physical techniques to elucidate the properties of particle coatings and the extent of radiolytic and chemical damage to the particles, and to optimize the stages of loading, extraction, and particle regeneration. This report describes the development of a separation process for TRU elements from various high-level waste streams. Polymer-coated ferromagnetic particles with an adsorbed layer of octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) diluted with tributyl phosphate (TBP) were evaluated for use in the separation and recovery of americium and plutonium from nuclear waste solutions. Due to their chemical nature, these extractants selectively complex americium and plutonium contaminants onto the particles, which can then be recovered from the solution by using a magnet. The partition coefficients were larger than those expected based on liquid[liquid extractions, and the extraction proceeded with rapid kinetics. Extractants were stripped from the particles with alcohols and 400-fold volume reductions were achieved. Particles were more sensitive to acid hydrolysis than to radiolysis. Overall, the optimization of a suitable NMCS particle for TRU separation was achieved under simulant conditions, and a MACS unit is currently being designed for an in-lab demonstration.

  11. Optimized Triton X-114 assisted lipopolysaccharide (LPS) removal method reveals the immunomodulatory effect of food proteins

    PubMed Central

    Perdijk, Olaf; Verhoek, Iris; Govers, Coen; Savelkoul, Huub F. J.; Tang, Yongfu; Wichers, Harry; Broersen, Kerensa

    2017-01-01

    Scope Investigations into the immunological response of proteins is often masked by lipopolysaccharide (LPS) contamination. We report an optimized Triton X-114 (TX-114) based LPS extraction method for β-lactoglobulin (BLG) and soy protein extract suitable for cell-based immunological assays. Methods and results Optimization of an existing TX-114 based phase LPS extraction method resulted in >99% reduction of LPS levels. However, remaining TX-114 was found to interfere with LPS and protein concentration assays and decreased viability of THP-1 macrophages and HEK-Blue 293 cells. Upon screening a range of TX-114 extraction procedures, TX-114-binding beads were found to most effectively lower TX-114 levels without affecting protein structural properties. LPS-purified proteins showed reduced capacity to activate TLR4 compared to non-treated proteins. LPS-purified BLG did not induce secretion of pro-inflammatory cytokines from THP-1 macrophages, as non-treated protein did, showing that LPS contamination masks the immunomodulatory effect of BLG. Both HEK293 cells expressing TLR4 and differentiated THP-1 macrophages were shown as a relevant model to screen the protein preparations for biological effects of LPS contamination. Conclusion The reported TX-114 assisted LPS-removal from protein preparations followed by bead based removal of TX-114 allows evaluation of natively folded protein preparations for their immunological potential in cell-based studies. PMID:28355240

  12. Simulation based flow distribution network optimization for vacuum assisted resin transfer moulding process

    NASA Astrophysics Data System (ADS)

    Hsiao, Kuang-Ting; Devillard, Mathieu; Advani, Suresh G.

    2004-05-01

    In the vacuum assisted resin transfer moulding (VARTM) process, using a flow distribution network such as flow channels and high permeability fabrics can accelerate the resin infiltration of the fibre reinforcement during the manufacture of composite parts. The flow distribution network significantly influences the fill time and fill pattern and is essential for the process design. The current practice has been to cover the top surface of the fibre preform with the distribution media with the hope that the resin will flood the top surface immediately and penetrate through the thickness. However, this approach has some drawbacks. One is when the resin finds its way to the vent before it has penetrated the preform entirely, which results in a defective part or resin wastage. Also, if the composite structure contains ribs or inserts, this approach invariably results in dry spots. Instead of this intuitive approach, we propose a science-based approach to design the layout of the distribution network. Our approach uses flow simulation of the resin into the network and the preform and a genetic algorithm to optimize the flow distribution network. An experimental case study of a co-cured rib structure is conducted to demonstrate the design procedure and validate the optimized flow distribution network design. Good agreement between the flow simulations and the experimental results was observed. It was found that the proposed design algorithm effectively optimized the flow distribution network of the part considered in our case study and hence should prove to be a useful tool to extend the VARTM process to manufacture of complex structures with effective use of the distribution network layup.

  13. Accretion and Orbital Inspiral in Gas-assisted Supermassive Black Hole Binary Mergers

    NASA Astrophysics Data System (ADS)

    Rafikov, Roman R.

    2016-08-01

    Many galaxies are expected to harbor binary supermassive black holes (SMBHs) in their centers. Their interaction with the surrounding gas results in the accretion and exchange of angular momentum via tidal torques, facilitating binary inspiral. Here, we explore the non-trivial coupling between these two processes and analyze how the global properties of externally supplied circumbinary disks depend on the binary accretion rate. By formulating our results in terms of the angular momentum flux driven by internal stresses, we come up with a very simple classification of the possible global disk structures, which differ from the standard constant \\dot{M} accretion disk solution. The suppression of accretion by the binary tides, leading to a significant mass accumulation in the inner disk, accelerates binary inspiral. We show that once the disk region strongly perturbed by the viscously transmitted tidal torque exceeds the binary semimajor axis, the binary can merge in less than its mass-doubling time due to accretion. Thus, unlike the inspirals driven by stellar scattering, the gas-assisted merger can occur even if the binary is embedded in a relatively low-mass disk (lower than its own mass). This is important for resolving the “last parsec” problem for SMBH binaries and understanding powerful gravitational wave sources in the universe. We argue that the enhancement of accretion by the binary found in some recent simulations cannot persist for a long time and should not affect the long-term orbital inspiral. We also review existing simulations of SMBH binary-disk coupling and propose a numerical setup which is particularly well suited to verifying our theoretical predictions.

  14. Resolution improvement of isolated line pattern in quarter-micrometer level by layout-optimized assistant pattern method

    NASA Astrophysics Data System (ADS)

    Tounai, Keiichiro; Aizaki, Naoaki

    1996-06-01

    In the previous report, we showed the optimized results of off-axis illumination (OAI) for 0.25 micrometers resist patterning. Wide DOF was obtained for dense patterns like 1:1 L and S pattern, however, DOF was small for the sparse patterns. In order to widen the DOF for isolated line patterns under the OAI, we have examined the assistant pattern method, which needs the only unresolved additional patterns beside the isolated pattern. Optimization has been carried out by light intensity simulation under the following criteria; CD variation within plus or minus 10 percent, resist thickness loss of 10 percent and unresolved assistant patterns. CD value has been defined by the threshold method of aerial images. The evaluation method by aerial image is useful for rough estimate because the calculation is very rapid. However, the difference from the experimental results cannot be ignored in some cases, especially, in important CD- focus characteristics. For more accurate evaluation, we also investigated the result difference using a simplified resist development model. This model is useful for rapid calculation as light intensity calculation. From the evaluation of the exposure dose and focus latitude (EFL), the optimal layout must be decided considering exposure dose latitude decrease by resist development process. We have additionally investigated the combination effect of assistant pattern and halftone phase-shifting under OAI. EFL was improved a little by halftone phase- shifting mask without assistant patterns, on the other hand, EFL was improved by combination of HPSM and assistant patterns.

  15. Coordinated optimization of the parameters of the cooled gas-turbine flow path and the parameters of gas-turbine cycles and combined-cycle power plants

    NASA Astrophysics Data System (ADS)

    Kler, A. M.; Zakharov, Yu. B.; Potanina, Yu. M.

    2014-06-01

    In the present paper, we evaluate the effectiveness of the coordinated solution to the optimization problem for the parameters of cycles in gas turbine and combined cycle power plants and to the optimization problem for the gas-turbine flow path parameters within an integral complex problem. We report comparative data for optimizations of the combined cycle power plant at coordinated and separate optimizations, when, first, the gas turbine and, then, the steam part of a combined cycle plant is optimized. The comparative data are presented in terms of economic indicators, energy-effectiveness characteristics, and specific costs. Models that were used in the present study for calculating the flow path enable taking into account, as a factor influencing the economic and energy effectiveness of the power plant, the heat stability of alloys from which the nozzle and rotor blades of gas-turbine stages are made.

  16. Determination of mercury species in fish reference materials by gas chromatography-atomic fluorescence detection after closed-vessel microwave-assisted extraction.

    PubMed

    Nevado, Juan José Berzas; Martín-Doimeadios, Rosa Carmen Rodríguez; Bernardo, Francisco Javier Guzmán; Moreno, María Jiménez

    2005-11-04

    A simple and rapid method has been developed for speciation analysis of inorganic mercury and monomethylmercury (MMHg) in biological tissues. The procedure is based on the quantitative closed-vessel microwave-assisted leaching of mercury from biological samples with an alkaline extractant. The extracted mercury species are ethylated and analysed by capillary gas chromatography coupled to an atomic fluorescence detector via pyrolysis (CGC-pyro-AFS). The coupling between capillary gas chromatography and atomic fluorescence detector was optimized with the aim of minimizing the detection limits and time necessary for the species-selective determination of mercury compounds. The use of closed-vessel microwave-assisted extraction along with no clean-up steps before the ethylation leads to a significant total analysis time decrease with respect to similar procedures. The detection limit was 2 pg for MMHg (as Hg) and 1 pg for inorganic mercury. The method was validated by the analysis of DORM-2 (dogfish muscle) and DOLT-3 (dogfish liver) certified reference materials. The inorganic mercury and methylmercury concentrations found were in good agreement with the certified values. Recovery studies of fish muscle tissue spiked with inorganic mercury and MMHg were done to check the reliability of the method. In all cases satisfactory recoveries (92-105%) were obtained.

  17. OPTIMIZATION OF INFILL DRILLING IN NATURALLY-FRACTURED TIGHT-GAS RESERVOIRS

    SciTech Connect

    Lawrence W. Teufel; Her-Yuan Chen; Thomas W. Engler; Bruce Hart

    2004-05-01

    A major goal of industry and the U.S. Department of Energy (DOE) fossil energy program is to increase gas reserves in tight-gas reservoirs. Infill drilling and hydraulic fracture stimulation in these reservoirs are important reservoir management strategies to increase production and reserves. Phase II of this DOE/cooperative industry project focused on optimization of infill drilling and evaluation of hydraulic fracturing in naturally-fractured tight-gas reservoirs. The cooperative project involved multidisciplinary reservoir characterization and simulation studies to determine infill well potential in the Mesaverde and Dakota sandstone formations at selected areas in the San Juan Basin of northwestern New Mexico. This work used the methodology and approach developed in Phase I. Integrated reservoir description and hydraulic fracture treatment analyses were also conducted in the Pecos Slope Abo tight-gas reservoir in southeastern New Mexico and the Lewis Shale in the San Juan Basin. This study has demonstrated a methodology to (1) describe reservoir heterogeneities and natural fracture systems, (2) determine reservoir permeability and permeability anisotropy, (3) define the elliptical drainage area and recoverable gas for existing wells, (4) determine the optimal location and number of new in-fill wells to maximize economic recovery, (5) forecast the increase in total cumulative gas production from infill drilling, and (6) evaluate hydraulic fracture simulation treatments and their impact on well drainage area and infill well potential. Industry partners during the course of this five-year project included BP, Burlington Resources, ConocoPhillips, and Williams.

  18. Multivariate analysis of the volatile components in tobacco based on infrared-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Yang, Yanqin; Pan, Yuanjiang; Zhou, Guojun; Chu, Guohai; Jiang, Jian; Yuan, Kailong; Xia, Qian; Cheng, Changhe

    2016-11-01

    A novel infrared-assisted extraction coupled to headspace solid-phase microextraction followed by gas chromatography with mass spectrometry method has been developed for the rapid determination of the volatile components in tobacco. The optimal extraction conditions for maximizing the extraction efficiency were as follows: 65 μm polydimethylsiloxane-divinylbenzene fiber, extraction time of 20 min, infrared power of 175 W, and distance between the infrared lamp and the headspace vial of 2 cm. Under the optimum conditions, 50 components were found to exist in all ten tobacco samples from different geographical origins. Compared with conventional water-bath heating and nonheating extraction methods, the extraction efficiency of infrared-assisted extraction was greatly improved. Furthermore, multivariate analysis including principal component analysis, hierarchical cluster analysis, and similarity analysis were performed to evaluate the chemical information of these samples and divided them into three classifications, including rich, moderate, and fresh flavors. The above-mentioned classification results were consistent with the sensory evaluation, which was pivotal and meaningful for tobacco discrimination. As a simple, fast, cost-effective, and highly efficient method, the infrared-assisted extraction coupled to headspace solid-phase microextraction technique is powerful and promising for distinguishing the geographical origins of the tobacco samples coupled to suitable chemometrics.

  19. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane

    PubMed Central

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M. Nazmul; Tan, Tianwei

    2015-01-01

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient ‘green technique’, gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kgm−2h−1) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry. PMID:25819091

  20. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane.

    PubMed

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M Nazmul; Tan, Tianwei

    2015-03-30

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient 'green technique', gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kg m(-2) h(-1)) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry.

  1. A novel method for furfural recovery via gas stripping assisted vapor permeation by a polydimethylsiloxane membrane

    NASA Astrophysics Data System (ADS)

    Hu, Song; Guan, Yu; Cai, Di; Li, Shufeng; Qin, Peiyong; Karim, M. Nazmul; Tan, Tianwei

    2015-03-01

    Furfural is an important platform chemical with a wide range of applications. However, due to the low concentration of furfural in the hydrolysate, the conventional methods for furfural recovery are energy-intensive and environmentally unfriendly. Considering the disadvantages of pervaporation (PV) and distillation in furfural separation, a novel energy-efficient `green technique', gas stripping assisted vapor permeation (GSVP), was introduced in this work. In this process, the polydimethylsiloxane (PDMS) membrane was prepared by employing water as solvent. Coking in pipe and membrane fouling was virtually non-existent in this new process. In addition, GSVP was found to achieve the highest pervaporation separation index of 216200 (permeate concentration of 71.1 wt% and furfural flux of 4.09 kgm-2h-1) so far, which was approximately 2.5 times higher than that found in pervaporation at 95°C for recovering 6.0 wt% furfural from water. Moreover, the evaporation energy required for GSVP decreased by 35% to 44% relative to that of PV process. Finally, GSVP also displayed more promising potential in industrial application than PV, especially when coupled with the hydrolysis process or fermentation in biorefinery industry.

  2. Gas assisted method synthesis nitrogen-doped carbon quantum dots and Hg (II) sensing.

    PubMed

    Li, Yamei; Wang, Nan; He, Zhanhang

    2016-11-29

    Nitrogen-doped fluorescent carbon quantum dots (CQDs) was prepared by gas-assisted method using cellulose as precursors under ammonia atmosphere, which not only exhibited excellent photoluminescent properties, but also showed highly selective and sensitive detection of mercury ion. The nitrogen-doped CQDs displayed excitation wavelength dependent fluorescent behavior with outstanding dispersibility. Moreover, they exhibited high tolerance to various external conditions, such as storage time, pH value, and ionic strength. The rapid detection of Hg (II) by one-step operation within 1 min and the good linear correlation between I0/I and Hg (II) concentration in the range of 10-100 nM made the nitrogen-doped CQDs a promising nanoprobe for Hg (II) detection. The detection limit of the nitrogen-doped CQDs is about 7.7 nM. Such a nanoprobe has been successfully applied for the analysis of Hg (II) in natural water samples, demonstrating excellent practical feasibility.

  3. Optimization problems in natural gas transportation systems. A state-of-the-art review

    DOE PAGES

    Ríos-Mercado, Roger Z.; Borraz-Sánchez, Conrado

    2015-03-24

    Our paper provides a review on the most relevant research works conducted to solve natural gas transportation problems via pipeline systems. The literature reveals three major groups of gas pipeline systems, namely gathering, transmission, and distribution systems. In this work, we aim at presenting a detailed discussion of the efforts made in optimizing natural gas transmission lines.There is certainly a vast amount of research done over the past few years on many decision-making problems in the natural gas industry and, specifically, in pipeline network optimization. In this work, we present a state-of-the-art survey focusing on specific categories that include short-termmore » basis storage (line-packing problems), gas quality satisfaction (pooling problems), and compressor station modeling (fuel cost minimization problems). We also discuss both steady-state and transient optimization models highlighting the modeling aspects and the most relevant solution approaches known to date. Although the literature on natural gas transmission system problems is quite extensive, this is, to the best of our knowledge, the first comprehensive review or survey covering this specific research area on natural gas transmission from an operations research perspective. Furthermore, this paper includes a discussion of the most important and promising research areas in this field. Hence, our paper can serve as a useful tool to gain insight into the evolution of the many real-life applications and most recent advances in solution methodologies arising from this exciting and challenging research area of decision-making problems.« less

  4. Microwave-assisted extraction and large-volume injection gas chromatography tandem mass spectrometry determination of multiresidue pesticides in edible seaweed.

    PubMed

    García-Rodríguez, D; Carro, A M; Cela, R; Lorenzo, R A

    2010-09-01

    A microwave-assisted extraction method followed by clean-up with solid-phase extraction (SPE) combined with large-volume injection gas chromatography-tandem mass spectrometry (LVI-GC-MS/MS) for the analysis of 17 pesticides in wild and aquaculture edible seaweeds has been developed. An experimental central composite design was employed to evaluate the effects of the main variables potentially affecting the extraction (temperature, time, and solvent volume) and to optimize the process. The most effective microwave extraction conditions were achieved at 125 °C and 12 min with 24 mL of hexane/ethyl acetate (80:20). SPE clean-up of the extracts with graphitized carbon and Florisil, optimized by means of the experimental design, proved to be efficient in the removal of matrix interferences. The analytical recoveries were close to 100% for all the analytes, with relative standard deviations lower than 13%. The limits of detection ranged from 0.3 to 23.1 pg g(-1) and the limits of quantification were between 2.3 and 76.9 pg g(-1), far below the maximum residue levels established by the European Union for pesticides in seaweed. The results obtained prove the suitability of the microwave-assisted extraction for the routine analysis of pesticides in aquaculture and wild seaweed samples.

  5. Optimization of microwave-assisted extraction of polyphenols from Myrtus communis L. leaves.

    PubMed

    Dahmoune, Farid; Nayak, Balunkeswar; Moussi, Kamal; Remini, Hocine; Madani, Khodir

    2015-01-01

    Phytochemicals, such as phenolic compounds, are of great interest due to their health-benefitting antioxidant properties and possible protection against inflammation, cardiovascular diseases and certain types of cancer. Maximum retention of these phytochemicals during extraction requires optimised process parameter conditions. A microwave-assisted extraction (MAE) method was investigated for extraction of total phenolics from Myrtus communis leaves. The total phenolic capacity (TPC) of leaf extracts at optimised MAE conditions was compared with ultrasound-assisted extraction (UAE) and conventional solvent extraction (CSE). The influence of extraction parameters including ethanol concentration, microwave power, irradiation time and solvent-to-solid ratio on the extraction of TPC was modeled by using a second-order regression equation. The optimal MAE conditions were 42% ethanol concentration, 500 W microwave power, 62 s irradiation time and 32 mL/g solvent to material ratio. Ethanol concentration and liquid-to-solid ratio were the significant parameters for the extraction process (p<0.01). Under the MAE optimised conditions, the recovery of TPC was 162.49 ± 16.95 mg gallic acidequivalent/gdry weight(DW), approximating the predicted content (166.13 mg GAE/g DW). When bioactive phytochemicals extracted from Myrtus leaves using MAE compared with UAE and CSE, it was also observed that tannins (32.65 ± 0.01 mg/g), total flavonoids (5.02 ± 0.05 mg QE/g) and antioxidant activities (38.20 ± 1.08 μg GAE/mL) in MAE extracts were higher than the other two extracts. These findings further illustrate that extraction of bioactive phytochemicals from plant materials using MAE method consumes less extraction solvent and saves time.

  6. Optimization of Ultrasound-assisted Extraction of Phenolic Compounds from Myrcia amazonica DC. (Myrtaceae) Leaves

    PubMed Central

    de Morais Rodrigues, Mariana Cristina; Borges, Leonardo Luiz; Martins, Frederico Severino; Mourão, Rosa Helena V.; da Conceição, Edemilson Cardoso

    2016-01-01

    Background: Myrcia amazonica. DC is a species predominantly found in northern Brazil, and belongs to the Myrtaceae family, which possess various species used in folk medicine to treat gastrointestinal disorders, infectious diseases, and hemorrhagic conditions and are known for their essential oil contents. Materials and Methods: This study aimed applied the Box–Behnken design combined with response surface methodology to optimize ultrasound-assisted extraction of total polyphenols, total tannins (TT), and total flavonoids (TF) from M. amazonica DC. Results: The results indicated that the best conditions to obtain highest yields of TT were in lower levels of alcohol degree (65%), time (15 min), and also solid: Liquid ratio (solid to liquid ratio; 20 mg: 5 mL). The TF could be extracted with high amounts with higher extraction times (45 min), lower values of solid: Liquid ratio (20 mg: mL), and intermediate alcohol degree level. Conclusion: The exploitation of the natural plant resources present very important impact for the economic development, and also the valorization of great Brazilian biodiversity. The knowledge obtained from this work should be useful to further exploit and apply this raw material. SUMMARY Myrcia amazonica leaves possess phenolic compounds with biological applications;Lower levels of ethanolic strength are more suitable to obtain a igher levels of phenolic compouds such as tannins;Box-Behnken design indicates to be useful to explore the best conditions of ultrasound assisted extraction. Abbreviation used: Nomenclature ES: Ethanolic strength, ET: Extraction time, SLR: Solid to liquid ratio, TFc: Total flavonoid contents, TPc: Total polyphenol contents, TTc: Total tannin contents PMID:27019555

  7. Optimal waste-to-energy strategy assisted by GIS For sustainable solid waste management

    NASA Astrophysics Data System (ADS)

    Tan, S. T.; Hashim, H.

    2014-02-01

    Municipal solid waste (MSW) management has become more complex and costly with the rapid socio-economic development and increased volume of waste. Planning a sustainable regional waste management strategy is a critical step for the decision maker. There is a great potential for MSW to be used for the generation of renewable energy through waste incineration or landfilling with gas capture system. However, due to high processing cost and cost of resource transportation and distribution throughout the waste collection station and power plant, MSW is mostly disposed in the landfill. This paper presents an optimization model incorporated with GIS data inputs for MSW management. The model can design the multi-period waste-to-energy (WTE) strategy to illustrate the economic potential and tradeoffs for MSW management under different scenarios. The model is capable of predicting the optimal generation, capacity, type of WTE conversion technology and location for the operation and construction of new WTE power plants to satisfy the increased energy demand by 2025 in the most profitable way. Iskandar Malaysia region was chosen as the model city for this study.

  8. Methodology for optimizing the development and operation of gas storage fields

    SciTech Connect

    Mercer, J.C.; Ammer, J.R.; Mroz, T.H.

    1995-04-01

    The Morgantown Energy Technology Center is pursuing the development of a methodology that uses geologic modeling and reservoir simulation for optimizing the development and operation of gas storage fields. Several Cooperative Research and Development Agreements (CRADAs) will serve as the vehicle to implement this product. CRADAs have been signed with National Fuel Gas and Equitrans, Inc. A geologic model is currently being developed for the Equitrans CRADA. Results from the CRADA with National Fuel Gas are discussed here. The first phase of the CRADA, based on original well data, was completed last year and reported at the 1993 Natural Gas RD&D Contractors Review Meeting. Phase 2 analysis was completed based on additional core and geophysical well log data obtained during a deepening/relogging program conducted by the storage operator. Good matches, within 10 percent, of wellhead pressure were obtained using a numerical simulator to history match 2 1/2 injection withdrawal cycles.

  9. Adsorbed Natural Gas Storage in Optimized High Surface Area Microporous Carbon

    NASA Astrophysics Data System (ADS)

    Romanos, Jimmy; Rash, Tyler; Nordwald, Erik; Shocklee, Joshua Shawn; Wexler, Carlos; Pfeifer, Peter

    2011-03-01

    Adsorbed natural gas (ANG) is an attractive alternative technology to compressed natural gas (CNG) or liquefied natural gas (LNG) for the efficient storage of natural gas, in particular for vehicular applications. In adsorbants engineered to have pores of a few molecular diameters, a strong van der Walls force allows reversible physisorption of methane at low pressures and room temperature. Activated carbons were optimized for storage by varying KOH:C ratio and activation temperature. We also consider the effect of mechanical compression of powders to further enhance the volumetric storage capacity. We will present standard porous material characterization (BET surface area and pore-size distribution from subcritical N2 adsorption) and methane isotherms up to 250 bar at 293K. At sufficiently high pressure, specific surface area, methane binding energy and film density can be extracted from supercritical methane adsorption isotherms. Research supported by the California Energy Commission (500-08-022).

  10. Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997

    SciTech Connect

    1997-12-31

    Economically viable natural gas production from the low permeability Mesaverde Formation in the Piceance Basin, Colorado requires the presence of an intense set of open natural fractures. Establishing the regional presence and specific location of such natural fractures is the highest priority exploration goal in the Piceance and other western US tight, gas-centered basins. Recently, Advanced Resources International, Inc. (ARI) completed a field program at Rulison Field, Piceance Basin, to test and demonstrate the use of advanced seismic methods to locate and characterize natural fractures. This project began with a comprehensive review of the tectonic history, state of stress and fracture genesis of the basin. A high resolution aeromagnetic survey, interpreted satellite and SLAR imagery, and 400 line miles of 2-D seismic provided the foundation for the structural interpretation. The central feature of the program was the 4.5 square mile multi-azimuth 3-D seismic P-wave survey to locate natural fracture anomalies. The interpreted seismic attributes are being tested against a control data set of 27 wells. Additional wells are currently being drilled at Rulison, on close 40 acre spacings, to establish the productivity from the seismically observed fracture anomalies. A similar regional prospecting and seismic program is being considered for another part of the basin. The preliminary results indicate that detailed mapping of fault geometries and use of azimuthally defined seismic attributes exhibit close correlation with high productivity gas wells. The performance of the ten new wells, being drilled in the seismic grid in late 1996 and early 1997, will help demonstrate the reliability of this natural fracture detection and mapping technology.

  11. Surfactant assisted solid-state synthesis and gas sensor application of a SWCNT/SnO2 nanocomposite material.

    PubMed

    Lu, Jun; Ma, Anson; Yang, Shihe; Ng, Ka Ming

    2007-01-01

    Although tin oxide has been the most widely investigated metal oxide material for gas detection, it suffers from the large resistance and high operating temperature. This could be overcome by hybridization with nanostructured carbon. In this work, tin oxide nanoparticles with ultrasmall sizes of 1-3 nm have been uniformly coated onto bundles of single-walled carbon nanotubes by a surfactant assisted solid state synthesis approach for the first time. Gas sensor properties of the as-synthesized nanocomposite material toward NO2 (from 5 to 60 ppm) are measured at 150 degrees C. Compared to the pure carbon tubes gas sensors, the nanocomposite gas sensor responds to NO2 in low concentrations with good linearity, high sensitivity, and fast recovery, while working at a relatively low temperature.

  12. Metal-Assisted Laser-Induced Gas Plasma for the Direct Analysis of Powder Using Pulse CO2 Laser

    NASA Astrophysics Data System (ADS)

    Khumaeni, A.; Lie, Z. S.; Kurniawan, K. H.; Kagawa, K.

    2017-01-01

    Analysis of powder samples available in small quantities has been carried out using metal-assisted gas plasma by utilizing a transversely excited atmospheric (TEA) CO2 laser. The powder was homogeneously mixed with Si grease, and the mixed powder was painted on a metal subtarget. When a TEA CO2 laser was directly focused on the metal subtarget at atmospheric pressure of He gas, a high-temperature He gas plasma was induced. It is assumed that the powder particles were vaporized to be effectively atomized and excited in the gas plasma region. This method has been employed in the rapid analyses of elements in organic and inorganic powder samples present in small quantities. Detection of trace elements of Cr and Pb has been successfully made by using the supplement powder and loam soil, respectively. The detection limits of Pb in loam soil were approximately 20 mg/kg.

  13. SDS-assisted hydrothermal synthesis of NiO flake-flower architectures with enhanced gas-sensing properties

    NASA Astrophysics Data System (ADS)

    Miao, Ruiyang; Zeng, Wen; Gao, Qi

    2016-10-01

    A facile hydrothermal route was developed for the preparation of well-aligned hierarchical flower-like NiO nanostructure with the assistance of SDS that served as a structure-directing agent as well as a capping agent in the process of aggregation and assembly. Notably, the NiO sensors exhibit enhanced gas-sensing performance towards ethanol, which could be explained in association with the ultrathin nanosheets that are close to Debye length (LD) scale and thus get the majority carriers fully depleted due to the ionization of adsorbed oxygen, abundant effective gas diffusion paths as well as high surface-to-volume ratio to promote sufficient contact and reaction between the NiO sample and ethanol molecules, and numerous miniature reaction rooms assembled with nanosheets to make the test gas molecules stay long enough for completed gas-sensing reactions. Besides, a novel growth mechanism with the passage of reaction time was also proposed in detail.

  14. Optimization of deep eutectic solvent-based ultrasound-assisted extraction of polysaccharides from Dioscorea opposita Thunb.

    PubMed

    Zhang, Lijin; Wang, Maoshan

    2017-02-01

    In this study, deep eutectic solvents were proposed for the ultrasound-assisted extraction of polysaccharides from Dioscorea opposita Thunb. Several deep eutectic solvents were prepared for the extraction of polysaccharides, among which the deep eutectic solvent composed of choline chloride and 1,4-butanediol was proved to be suitable for the extraction. Based on the screening of single-factor experiment design and orthogonal experiment design, three experimental factors were optimized for the Box-Behnken experimental design combined with response surface methodology, which gave the optimal extraction conditions: water content of 32.89%(v/v), extraction temperature of 94.00°C, and the extraction time of 44.74min. The optimal extraction conditions could supply higher extraction yield than those of hot water extraction and water-based ultrasound-assisted extraction. Therefore, deep eutectic solvents were an excellent extraction solvent alternative to the extraction of polysaccharides from sample matrices.

  15. Contact-assisted protein structure modeling by global optimization in CASP11.

    PubMed

    Joo, Keehyoung; Joung, InSuk; Cheng, Qianyi; Lee, Sung Jong; Lee, Jooyoung

    2016-09-01

    We have applied the conformational space annealing method to the contact-assisted protein structure modeling in CASP11. For Tp targets, where predicted residue-residue contact information was provided, the contact energy term in the form of the Lorentzian function was implemented together with the physical energy terms used in our template-free modeling of proteins. Although we observed some structural improvement of Tp models over the models predicted without the Tp information, the improvement was not substantial on average. This is partly due to the inaccuracy of the provided contact information, where only about 18% of it was correct. For Ts targets, where the information of ambiguous NOE (Nuclear Overhauser Effect) restraints was provided, we formulated the modeling in terms of the two-tier optimization problem, which covers: (1) the assignment of NOE peaks and (2) the three-dimensional (3D) model generation based on the assigned NOEs. Although solving the problem in a direct manner appears to be intractable at first glance, we demonstrate through CASP11 that remarkably accurate protein 3D modeling is possible by brute force optimization of a relevant energy function. For 19 Ts targets of the average size of 224 residues, generated protein models were of about 3.6 Å Cα atom accuracy. Even greater structural improvement was observed when additional Tc contact information was provided. For 20 out of the total 24 Tc targets, we were able to generate protein structures which were better than the best model from the rest of the CASP11 groups in terms of GDT-TS. Proteins 2016; 84(Suppl 1):189-199. © 2015 Wiley Periodicals, Inc.

  16. Ultrasonic nebulization extraction assisted dispersive liquid-liquid microextraction followed by gas chromatography for the simultaneous determination of six parabens in cosmetic products.

    PubMed

    Wei, Hongmin; Yang, Jinjuan; Zhang, Hanqi; Shi, Yuhua

    2014-09-01

    A simple, rapid, and efficient method of ultrasonic nebulization extraction assisted dispersive liquid-liquid microextraction was developed for the simultaneous determination of six parabens in cosmetic products. The analysis was carried out by gas chromatography. Water was used as the dispersive solvent instead of traditional organic disperser. The experimental factors affecting the extraction yield, such as the extraction solvent and volume, extraction time, dispersive solvent and volume, ionic strength, and centrifuging condition were studied and optimized in detail. The limit of detections for the target analytes were in the range of 2.0-9.5 μg/g. Good linear ranges were obtained with the coefficients ranging from 0.9934 to 0.9969. The proposed method was successfully applied to the analysis of six parabens in 16 cosmetic products. The recoveries of the target analytes in real samples ranged from 81.9 to 108.7%, and the relative standard deviations were <5.3%.

  17. Integration and optimization of the gas removal system for hybrid-cycle OTEC power plants

    SciTech Connect

    Rabas, T.J.; Panchal, C.B.; Stevens, H.C. )

    1990-02-01

    A preliminary design of the noncondensible gas removal system for a 10 mWe, land-based hybrid-cycle OTEC power plant has been developed and is presented herein. This gas removal system is very different from that used for conventional power plants because of the substantially larger and continuous noncondensible gas flow rates and lower condenser pressure levels which predicate the need for higher-efficiency components. Previous OTEC studies discussed the need for multiple high-efficiency compressors with intercoolers; however, no previous design effort was devoted to the details of the intercoolers, integration and optimization of the intercoolers with the compressors, and the practical design constraints and feasibility issues of these components. The resulting gas removal system design uses centrifugal (radial) compressors with matrix-type crossflow aluminum heat exchangers as intercoolers. Once-through boiling of ammonia is used as the heat sink for the cooling and condensing of the steam-gas mixture. A computerized calculation method was developed for the performance analysis and subsystem optimization. For a specific number of compressor units and the stream arrangement, the method is used to calculate the dimensions, speeds, power requirements, and costs of all the components.

  18. Nonlinear Resonant Oscillations of Gas in Optimized Acoustical Resonators and the Effect of Central Blockage

    NASA Technical Reports Server (NTRS)

    Li, Xiaofan; Finkbeiner, Joshua; Raman, Ganesh; Daniels, Christopher; Steinetz, Bruce M.

    2003-01-01

    Optimizing resonator shapes for maximizing the ratio of maximum to minimum gas pressure at an end of the resonator is investigated numerically. It is well known that the resonant frequencies and the nonlinear standing waveform in an acoustical resonator strongly depend on the resonator geometry. A quasi-Newton type scheme was used to find optimized axisymmetric resonator shapes achieving the maximum pressure compression ratio with an acceleration of constant amplitude. The acoustical field was solved using a one-dimensional model, and the resonance frequency shift and hysteresis effects were obtained through an automation scheme based on continuation method. Results are presented for optimizing three types of geometry: a cone, a horn-cone and a half cosine-shape. For each type, different optimized shapes were found when starting with different initial guesses. Further, the one-dimensional model was modified to study the effect of an axisymmetric central blockage on the nonlinear standing wave.

  19. Microwave-assisted extraction of lignin from triticale straw: optimization and microwave effects.

    PubMed

    Monteil-Rivera, Fanny; Huang, Guang Hai; Paquet, Louise; Deschamps, Stéphane; Beaulieu, Chantale; Hawari, Jalal

    2012-01-01

    Presently lignin is used as fuel but recent interests in biomaterials encourage the use of this polymer as a renewable feedstock in manufacturing. The present study was undertaken to explore the potential applicability of microwaves to isolate lignin from agricultural residues. A central composite design (CCD) was used to optimize the processing conditions for the microwave (MW)-assisted extraction of lignin from triticale straw. Maximal lignin yield (91%) was found when using 92% EtOH, 0.64 N H(2)SO(4), and 148 °C. The yield and chemical structure of MW-extracted lignin were compared to those of lignin extracted with conventional heating. Under similar conditions, MW irradiation led to higher lignin yields, lignins of lower sugar content, and lignins of smaller molecular weights. Except for these differences the lignins resulting from both types of heating exhibited comparable chemical structures. The present findings should provide a clean source of lignin for potential testing in manufacturing of biomaterials.

  20. [Response surface method optimize of nano-silica solid dispersion technology assistant enzymatic hydrolysis preparation genistein].

    PubMed

    Jin, Xin; Zhang, Zhen-Hai; Zhu, Jing; Sun, E; Yu, Dan-Hong; Chen, Xiao-Yun; Liu, Qi-Yuan; Ning, Qing; Jia, Xiao-Bin

    2012-04-01

    This article reports that nano-silica solid dispersion technology was used to raise genistein efficiency through increasing the enzymatic hydrolysis rate. Firstly, genistin-nano-silica solid dispersion was prepared by solvent method. And differential scanning calorimetry (DSC) and transmission electron microscopy (TEM) were used to verify the formation of solid dispersion, then enzymatic hydrolysis of solid dispersion was done by snailase to get genistein. With the conversion of genistein as criteria, single factor experiments were used to study the different factors affecting enzymatic hydrolysis of genistin and its solid dispersion. And then, response surface method was used to optimize of nano-silica solid dispersion technology assistant enzymatic hydrolysis. The optimum condition to get genistein through enzymatic hydrolysis of genistin-nano-silica solid dispersion was pH 7.1, temperature 52.2 degrees C, enzyme concentration 5.0 mg x mL(-1) and reaction time 7 h. Under this condition, the conversion of genistein was (93.47 +/- 2.40)%. Comparing with that without forming the genistin-nano-silica solid dispersion, the conversion increased 2.62 fold. At the same time, the product of hydrolysis was purified to get pure genistein. The method of enzymatic hydrolysis of genistin-nano-silica solid dispersion by snailase to obtain genistein is simple, efficiency and suitable for the modern scale production.

  1. Optimization of microwave assisted extraction of pectin from sour orange peel and its physicochemical properties.

    PubMed

    Hosseini, Seyed Saeid; Khodaiyan, Faramarz; Yarmand, Mohammad Saeid

    2016-04-20

    Microwave assisted extraction technique was used to extract pectin from sour orange peel. Box-Behnken design was used to study the effect of irradiation time, microwave power and pH on the yield and degree of esterification (DE) of pectin. The results showed that the optimum conditions for the highest yield of pectin (29.1%) were obtained at pH of 1.50, microwave power of 700W, and irradiation time of 3min. DE values of pectin ranged from 1.7% to 37.5%, indicating that the obtained pectin was low in methoxyl. Under optimal conditions, the galacturonic acid content and emulsifying activity were 71.0±0.8% and 40.7%, respectively. In addition, the emulsion stability value ranged from 72.1% to 83.4%. Viscosity measurement revealed that the solutions of pectin at low concentrations showed nearly Newtonian flow behavior, and as the concentration increased, pseudoplastic flow became dominant.

  2. Erbium-Doped Hole-Assisted Optical Fiber Amplifier: Design and Optimization

    NASA Astrophysics Data System (ADS)

    Prudenzano, Francesco

    2005-01-01

    An erbium-doped hole-assisted optical fiber amplifier, to be employed in the third band of the optical communications, is designed and optimized via a tailor made computer code. The finite element method is used for the electromagnetic investigation of the microstructured fiber section. The simulation model takes into account all the rare earth physical phenomena, i.e., the pump and signal propagation, the amplified spontaneous emission,the secondary transitions pertaining to the ion-ion interactions, and so on. The device feasibility is tested via a number of simulations, realistically performed by taking into account the actual parameters pertaining to the dispersion of the germania/silica glass, the erbium emission and absorption cross sections,the propagation losses. By simulation, in the small signal operation, a gain close to 42.8 dB is demonstrated for a fiber 13-m long, using a pump power of 50 mW at the signal wavelength lambdas =1536 nm, the pump and the signal being copropagating.

  3. Pectin from Opuntia ficus indica: Optimization of microwave-assisted extraction and preliminary characterization.

    PubMed

    Lefsih, Khalef; Giacomazza, Daniela; Dahmoune, Farid; Mangione, Maria Rosalia; Bulone, Donatella; San Biagio, Pier Luigi; Passantino, Rosa; Costa, Maria Assunta; Guarrasi, Valeria; Madani, Khodir

    2017-04-15

    Optimization of microwave-assisted extraction (MAE) of water-soluble pectin (WSP) from Opuntia ficus indica cladodes was performed using Response Surface Methodology. The effect of extraction time (X1), microwave power (X2), pH (X3) and solid-to-liquid ratio (X4) on the extraction yield was examined. The optimum conditions of MAE were as follows: X1=2.15min; X2=517W; X3=2.26 and X4=2g/30.6mL. The maximum obtained yield of pectin extraction was 12.57%. Total carbohydrate content of WSP is about 95.5% including 34.4% of Galacturonic acid. Pectin-related proteins represent only the 0.66% of WSP mass. HPSEC and light scattering analyses reveal that WSP is mostly constituted of high molecular pectin and FTIR measurements show that the microwave treatment does not alter the chemical structure of WSP, in which Galacturonic acid content and yield are 34.4% and 4.33%, respectively. Overall, application of MAE can give rise to high quality pectin.

  4. Microwave assisted synthesis and optimization of Aegle marmelos-g-poly(acrylamide): release kinetics studies.

    PubMed

    Setia, A; Kumar, R

    2014-04-01

    Microwave assisted grafting of poly(acrylamide) on to Aegle marmelos gum was carried out employing 3-factor 3-level full factorial design. Microwave power, microwave exposure time and concentration of gum were selected as independent variable and grafting efficiency was taken as dependent variable. A. marmelos-g-poly(acrylamide) was characterized by FTIR, DSC, X-ray diffraction and scanning electron microscopy. Microwave power, microwave exposure time had synergistic effect on grafting efficiency where as concentration of the gum did not contributed much to grafting efficiency. Batch having microwave power - 80%, microwave exposure time -120 s and concentration of A. marmelos gum - 2% was selected as the optimized formulation. Comparative release behaviour of diclofenac sodium from the matrix tablets of A. marmelos gum and A. marmelos-g-polyacrylamide was evaluated. The results of kinetic studies revealed that the graft copolymer matrix, marketed tablets and polymer matrix tablets of A. marmelos gum released the drug by zero order kinetics and with n value greater than 1, indicating that the mechanism for release as super case II transport i.e. dominated by the erosion and swelling of the polymer.

  5. Cellulase-assisted extraction of polysaccharides from Malva sylvestris: Process optimization and potential functionalities.

    PubMed

    Rostami, Hosein; Gharibzahedi, Seyed Mohammad Taghi

    2017-03-19

    Enzyme-assisted extraction process of the water-soluble Malva sylvestris polysaccharides (MSPs) was optimized using response surface methodology (RSM). The highest yield (10.40%) of MSPs was achieved at 5.64% cellulase, 55.65°C temperature, 3.4h time, and 5.22 pH. Three homogeneous polysaccharide fractions (MSP-1, MSP-2, MSP-3) were purified by DEAE-cellulose and Sephadex G-100 chromatography, which were composed of galactose, glucuronic acid, arabinose, rhamnose and mannose in different molar ratios with molecular weight range of 2.6×10(5)-8.8×10(5)Da. The fractions could significantly increase antioxidant, antitumor and antimicrobial activities in a dose-dependent pattern. MSP-2 revealed stronger antioxidant activities than MSP-1 and MSP-3, including reducing power and scavenging activity of DPPH and OH radicals. The antiproliferative activity of MSP-2 (1.0mg/mL) on the growth of A549 and HepG2 cells was 45.1% and 53.2%, respectively. The Gram-positive bacteria (Bacillus cereus PTCC 1015 and Staphylococcus aureus PTCC 1112) compared with Gram-negative ones (Escherichia coli PTCC 1763 and Salmonella typhimurium PTCC 1709) showed less sensitivity against the various MSPs (3-15mg/mL).

  6. Areal density optimizations for heat-assisted magnetic recording of high-density media

    NASA Astrophysics Data System (ADS)

    Vogler, Christoph; Abert, Claas; Bruckner, Florian; Suess, Dieter; Praetorius, Dirk

    2016-06-01

    Heat-assisted magnetic recording (HAMR) is hoped to be the future recording technique for high-density storage devices. Nevertheless, there exist several realization strategies. With a coarse-grained Landau-Lifshitz-Bloch model, we investigate in detail the benefits and disadvantages of a continuous and pulsed laser spot recording of shingled and conventional bit-patterned media. Additionally, we compare single-phase grains and bits having a bilayer structure with graded Curie temperature, consisting of a hard magnetic layer with high TC and a soft magnetic one with low TC, respectively. To describe the whole write process as realistically as possible, a distribution of the grain sizes and Curie temperatures, a displacement jitter of the head, and the bit positions are considered. For all these cases, we calculate bit error rates of various grain patterns, temperatures, and write head positions to optimize the achievable areal storage density. Within our analysis, shingled HAMR with a continuous laser pulse moving over the medium reaches the best results and thus has the highest potential to become the next-generation storage device.

  7. Optimal distribution of medical backpacks and health surveillance assistants in Malawi.

    PubMed

    Kunkel, Amber G; Van Itallie, Elizabeth S; Wu, Duo

    2014-09-01

    Despite recent progress, Malawi continues to perform poorly on key health indicators such as child mortality and life expectancy. These problems are exacerbated by a severe lack of access to health care. Health Surveillance Assistants (HSAs) help bridge this gap by providing community-level access to basic health care services. However, the success of these HSAs is limited by a lack of supplies and long distances between HSAs and patients. To address this issue, we used large-scale weighted p-median and capacitated facility location problems to create a scalable, three-tiered plan for optimal allocation of HSAs, HSA designated medical backpacks, and backpack resupply centers. Our analysis uses real data on the location and characteristics of hospitals, health centers, and the general population. In addition to offering specific recommendations for HSA, backpack, and resupply center locations, it provides general insights into the scope of the proposed HSA backpack program scale-up. In particular, it demonstrates the importance of local health centers to the resupply network. The proposed assignments are robust to changes in the underlying population structure, and could significantly improve access to medical supplies for both HSAs and patients.

  8. Optimization of wave rotors for use as gas turbine engine topping cycles

    NASA Technical Reports Server (NTRS)

    Wilson, Jack; Paxson, Daniel E.

    1995-01-01

    Use of a wave rotor as a topping cycle for a gas turbine engine can improve specific power and reduce specific fuel consumption. Maximum improvement requires the wave rotor to be optimized for best performance at the mass flow of the engine. The optimization is a trade-off between losses due to friction and passage opening time, and rotational effects. An experimentally validated, one-dimensional CFD code, which includes these effects, has been used to calculate wave rotor performance, and find the optimum configuration. The technique is described, and results given for wave rotors sized for engines with sea level mass flows of 4, 26, and 400 lb/sec.

  9. Application of Hydrogen Assisted Lean Operation to Natural Gas-Fueled Reciprocating Engines (HALO)

    SciTech Connect

    Chad Smutzer

    2006-01-01

    Two key challenges facing Natural Gas Engines used for cogeneration purposes are spark plug life and high NOx emissions. Using Hydrogen Assisted Lean Operation (HALO), these two keys issues are simultaneously addressed. HALO operation, as demonstrated in this project, allows stable engine operation to be achieved at ultra-lean (relative air/fuel ratios of 2) conditions, which virtually eliminates NOx production. NOx values of 10 ppm (0.07 g/bhp-hr NO) for 8% (LHV H2/LHV CH4) supplementation at an exhaust O2 level of 10% were demonstrated, which is a 98% NOx emissions reduction compared to the leanest unsupplemented operating condition. Spark ignition energy reduction (which will increase ignition system life) was carried out at an oxygen level of 9%, leading to a NOx emission level of 28 ppm (0.13 g/bhp-hr NO). The spark ignition energy reduction testing found that spark energy could be reduced 22% (from 151 mJ supplied to the coil) with 13% (LHV H2/LHV CH4) hydrogen supplementation, and even further reduced 27% with 17% hydrogen supplementation, with no reportable effect on NOx emissions for these conditions and with stable engine torque output. Another important result is that the combustion duration was shown to be only a function of hydrogen supplementation, not a function of ignition energy (until the ignitability limit was reached). The next logical step leading from these promising results is to see how much the spark energy reduction translates into increase in spark plug life, which may be accomplished by durability testing.

  10. Dynamic and quasi-static lung mechanics system for gas-assisted and liquid-assisted ventilation.

    PubMed

    Alvarez, Francisco J; Gastiasoro, Elena; Rey-Santano, M Carmen; Gomez-Solaetxe, Miguel A; Publicover, Nelson G; Larrabe, Juan L

    2009-07-01

    Our aim was to develop a computerized system for real-time monitoring of lung mechanics measurements during both gas and liquid ventilation. System accuracy was demonstrated by calculating regression and percent error of the following parameters compared to standard device: airway pressure difference (Delta P(aw)), respiratory frequency (f(R) ), tidal volume (V(T)), minute ventilation (V'(E)), inspiratory and expiratory maximum flows (V'(ins,max), V'(exp,max)), dynamic lung compliance (C(L,dyn) ), resistance of the respiratory system calculated by method of Mead-Whittenberger (R(rs,MW)) and by equivalence to electrical circuits (R(rs,ele)), work of breathing (W(OB)), and overdistension. Outcome measures were evaluated as function of gas exchange, cardiovascular parameters, and lung mechanics including mean airway pressure (mP(aw)). Delata P(aw), V(T), V'(ins,max), V'(exp,max), and V'(E) measurements had correlation coefficients r = 1.00, and %error < 0.5%. f(R), C(L,dyn), R(rs,MW), R(rs,ele), and W(OB) showed r > or = 0.98 and %error < 5%. Overdistension had r = 0.87 and %error < 15%. Also, resistance was accurately calculated by a new algorithm. The system was tested in rats in which lung lavage was used to induce acute respiratory failure. After lavage, both gas- and liquid-ventilated groups had increased mP(aw) and W(OB), with decreased V(T), V'(E), C(L,dyn), R(rs,MW), and R(rs,ele) compared to controls. After 1-h ventilation, both injured group had decreased V(T), V'(E) , and C(L,dyn), with increased mP(aw), R(rs,MW), R(rs,ele), and W(OB) . In lung-injured animals, liquid ventilation restored gas exchange, and cardiovascular and lung functions. Our lung mechanics system was able to closely monitor pulmonary function, including during transitions between gas and liquid phases.

  11. Rapid analysis of Fructus forsythiae essential oil by ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction followed by gas chromatography-mass spectrometry.

    PubMed

    Jiao, Jiao; Ma, Dan-Hui; Gai, Qing-Yan; Wang, Wei; Luo, Meng; Fu, Yu-Jie; Ma, Wei

    2013-12-04

    A rapid, green and effective miniaturized sample preparation and analytical technique, i.e. ionic liquids-assisted microwave distillation coupled with headspace single-drop microextraction (ILAMD-HS-SDME) followed by gas chromatography-mass spectrometry (GC-MS) was developed for the analysis of essential oil (EO) in Fructus forsythiae. In this work, ionic liquids (ILs) were not only used as the absorption medium of microwave irradiation but also as the destruction agent of plant cell walls. 1-Ethyl-3-methylimidazolium acetate ([C2mim]OAc) was chosen as the optimal ILs. Moreover, n-heptadecane (2.0 μL) was selected as the appropriate suspended solvent for the extraction and concentration of EO. Extraction conditions of the proposed method were optimized using the relative peak area of EO constituents as the index, and the optimal operational parameters were obtained as follows: irradiation power (300 W), sample mass (0.7 g), mass ratio of ILs to sample (2.4), temperature (78°C) and time (3.4 min). In comparison to previous reports, the proposed method was faster and required smaller sample amount but could equally monitor all EO constituents with no significant differences.

  12. Determination of cyclic and linear siloxanes in wastewater samples by ultrasound-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

    PubMed

    Cortada, Carol; dos Reis, Luciana Costa; Vidal, Lorena; Llorca, Julio; Canals, Antonio

    2014-03-01

    A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid-liquid microextraction (USA-DLLME) procedure has been developed to preconcentrate eight cyclic and linear siloxanes from wastewater samples prior to quantification by gas chromatography-mass spectrometry (GC-MS). A two-stage multivariate optimization approach has been developed employing a Plackett-Burman design for screening and selecting the significant factors involved in the USA-DLLME procedure, which was later optimized by means of a circumscribed central composite design. The optimum conditions were: extractant solvent volume, 13 µL; solvent type, chlorobenzene; sample volume, 13 mL; centrifugation speed, 2300 rpm; centrifugation time, 5 min; and sonication time, 2 min. Under the optimized experimental conditions the method gave levels of repeatability with coefficients of variation between 10 and 24% (n=7). Limits of detection were between 0.002 and 1.4 µg L(-1). Calculated calibration curves gave high levels of linearity with correlation coefficient values between 0.991 and 0.9997. Finally, the proposed method was applied for the analysis of wastewater samples. Relative recovery values ranged between 71 and 116% showing that the matrix had a negligible effect upon extraction. To our knowledge, this is the first time that combines LLME and GC-MS for the analysis of methylsiloxanes in wastewater samples.

  13. Development and optimization of porous carbon papers suitable for gas diffusion electrodes. Final report, December 2000

    SciTech Connect

    Fleming, Gerald J.; Fleming, Patrick J.

    2001-01-16

    This final report details results from the program to optimize porous carbon gas diffusion electrodes for use in fuel cells. Efforts focused on isolating discrete paper properties through a custom-made matrix, then fuel cell testing each variant to correlate properties to performance. Resulting reduced cost material was manufactured on production equipment and made available to DOE industry partners. The resulting product is suitable for continuous production, which will be evaluated in future work.

  14. Hydrogen gas filling into an actual tank at high pressure and optimization of its thermal characteristics

    NASA Astrophysics Data System (ADS)

    Khan, Md. Tawhidul Islam; Monde, Masanori; Setoguchi, Toshiaki

    2009-09-01

    Gas with high pressure is widely used at present as fuel storage mode for different hydrogen vehicles. Different types of materials are used for constructing these hydrogen pressure vessels. An aluminum lined vessel and typically carbon fiber reinforced plastic (CFRP) materials are commercially used in hydrogen vessels. An aluminum lined vessel is easy to construct and posses high thermal conductivity compared to other commercially available vessels. However, compared to CFRP lined vessel, it has low strength capacity and safety factors. Therefore, nowadays, CFRP lined vessels are becoming more popular in hydrogen vehicles. Moreover, CFRP lined vessel has an advantage of light weight. CFRP, although, has many desirable properties in reducing the weight and in increasing the strength, it is also necessary to keep the material temperature below 85 °C for maintaining stringent safety requirements. While filling process occurs, the temperature can be exceeded due to the compression works of the gas flow. Therefore, it is very important to optimize the hydrogen filling system to avoid the crossing of the critical limit of the temperature rise. Computer-aided simulation has been conducted to characterize the hydrogen filling to optimize the technique. Three types of hydrogen vessels with different volumes have been analyzed for optimizing the charging characteristics of hydrogen to test vessels. Gas temperatures are measured inside representative vessels in the supply reservoirs (H2 storages) and at the inlet to the test tank during filling.

  15. Optimal q-homotopy analysis method for time-space fractional gas dynamics equation

    NASA Astrophysics Data System (ADS)

    Saad, K. M.; AL-Shareef, E. H.; Mohamed, Mohamed S.; Yang, Xiao-Jun

    2017-01-01

    It is well known that the homotopy analysis method is one of the most efficient methods for obtaining analytical or approximate semi-analytical solutions of both linear and non-linear partial differential equations. A more general form of HAM is introduced in this paper, which is called Optimal q-Homotopy Analysis Method (Oq-HAM). It has better convergence properties as compared with the usual HAM, due to the presence of fraction factor associated with the solution. The convergence of q-HAM is studied in details elsewhere (M.A. El-Tawil, Int. J. Contemp. Math. Sci. 8, 481 (2013)). Oq-HAM is applied to the non-linear homogeneous and non-homogeneous time and space fractional gas dynamics equations with initial condition. An optimal convergence region is determined through the residual error. By minimizing the square residual error, the optimal convergence control parameters can be obtained. The accuracy and efficiency of the proposed method are verified by comparison with the exact solution of the fractional gas dynamics equation. Also, it is shown that the Oq-HAM for the fractional gas dynamics equation is equivalent to the exact solution. We obtain graphical representations of the solutions using MATHEMATICA.

  16. Variable-geometry turbocharger with asymmetric divided volute for engine exhaust gas pulse optimization

    SciTech Connect

    Serres, Nicolas

    2010-11-09

    A turbine assembly for a variable-geometry turbocharger includes a turbine housing defining a divided volute having first and second scrolls, wherein the first scroll has a substantially smaller volume than the second scroll. The first scroll feeds exhaust gas to a first portion of a turbine wheel upstream of the throat of the wheel, while the second scroll feeds gas to a second portion of the wheel at least part of which is downstream of the throat. Flow from the second scroll is regulated by a sliding piston. The first scroll can be optimized for low-flow conditions such that the turbocharger can operate effectively like a small fixed-geometry turbocharger when the piston is closed. The turbine housing defines an inlet that is divided by a dividing wall into two portions respectively feeding gas to the two scrolls, a leading edge of the dividing wall being downstream of the inlet mouth.

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

    SciTech Connect

    Dr. Chenn Zhou

    2012-08-15

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

  18. Identifying Optimal Zeolitic Sorbents for Sweetening of Highly Sour Natural Gas.

    PubMed

    Shah, Mansi S; Tsapatsis, Michael; Siepmann, J Ilja

    2016-05-10

    Raw natural gas is a complex mixture comprising methane, ethane, other hydrocarbons, hydrogen sulfide, carbon dioxide, nitrogen, and water. For sour gas fields, selective and energy-efficient removal of H2 S is one of the crucial challenges facing the natural-gas industry. Separation using nanoporous materials, such as zeolites, can be an alternative to energy-intensive amine-based absorption processes. Herein, the adsorption of binary H2 S/CH4 and H2 S/C2 H6 mixtures in the all-silica forms of 386 zeolitic frameworks is investigated using Monte Carlo simulations. Adsorption of a five-component mixture is utilized to evaluate the performance of the 16 most promising materials under close-to-real conditions. It is found that depending on the fractions of CH4 , C2 H6 , and CO2 , different sorbents allow for optimal H2 S removal and hydrocarbon recovery.

  19. An effective vacuum assisted extraction method for the optimization of labdane diterpenoids from Andrographis paniculata by response surface methodology.

    PubMed

    Wang, Ya-Qi; Wu, Zhen-Feng; Ke, Gang; Yang, Ming

    2014-12-31

    An effective vacuum assisted extraction (VAE) technique was proposed for the first time and applied to extract bioactive components from Andrographis paniculata. The process was carefully optimized by response surface methodology (RSM). Under the optimized experimental conditions, the best results were obtained using a boiling temperature of 65 °C, 50% ethanol concentration, 16 min of extraction time, one extraction cycles and a 12:1 liquid-solid ratio. Compared with conventional ultrasonic assisted extraction and heat reflux extraction, the VAE technique gave shorter extraction times and remarkable higher extraction efficiency, which indicated that a certain degree of vacuum gave the solvent a better penetration of the solvent into the pores and between the matrix particles, and enhanced the process of mass transfer. The present results demonstrated that VAE is an efficient, simple and fast method for extracting bioactive components from A. paniculata, which shows great potential for becoming an alternative technique for industrial scale-up applications.

  20. All-oxide broadband antireflection coatings by plasma ion assisted deposition: design, simulation, manufacturing and re-optimization.

    PubMed

    Wilbrandt, Steffen; Stenzel, Olaf; Kaiser, Norbert

    2010-09-13

    A new all-oxide design for broadband antireflection coatings with significantly reduced impact of deposition errors to the final reflectance is presented. Computational manufacturing including re-optimization during deposition has been used in the design work to account for maximum insensibility of the design with respect to deposition errors typical for plasma ion assisted deposition PIAD. Repeated deposition runs with the deducted monitoring and re-optimization strategy verify the validity of the simulations and the stability of the derived design solution.

  1. Optimizing Vacuum Assisted Resin Transfer Moulding (VARTM) Processing Parameters to Improve Part Quality

    NASA Astrophysics Data System (ADS)

    Polowick, Christopher

    The Low Cost Composites (LCC) group at Carleton University is studying out-of-autoclave composite manufacturing processes such as Vacuum Assisted Resin Transfer Moulding (VARTM) and Closed Cavity Bag Moulding (CCBM). These processes are used to produce inexpensive and high performance components for the GeoSurv II, an Unmanned Aerial Vehicle (UAV) being developed at Carleton University. This research has focused on optimizing VARTM processing parameters to reduce the weight and improve the strength and surface finish of GeoSurv II composite components. A simulation was developed to model resin flow through in VARTM infusions and was used to simulate mould filling and resin emptying of the GeoSurv II inverted V-empennage and mission avionics hatch. The resin infusion schemes of these parts were designed to ensure full preform resin saturation, and minimize thickness variations. An experimental study of the effects of the presence of a corner on composite thickness, void content, and strength was conducted. It was found that inside corners result in local increases in thickness and void content due to poor preform compaction. A novel bagging technique was developed to improve corner compaction, and this technique was shown to reduce thickness variability and void content. The strength, void content, and thickness variation were found to be heavily dependent on corner radius, with corner radii greater than 6.4 mm displaying the greatest improvement in performance for the layups considered. The design of the empennage and hatch mould incorporated the results of this study to improve the quality of these components.

  2. Parametric modeling and optimization of laser scanning parameters during laser assisted machining of Inconel 718

    NASA Astrophysics Data System (ADS)

    Venkatesan, K.; Ramanujam, R.; Kuppan, P.

    2016-04-01

    This paper presents a parametric effect, microstructure, micro-hardness and optimization of laser scanning parameters (LSP) on heating experiments during laser assisted machining of Inconel 718 alloy. The laser source used for experiments is a continuous wave Nd:YAG laser with maximum power of 2 kW. The experimental parameters in the present study are cutting speed in the range of 50-100 m/min, feed rate of 0.05-0.1 mm/rev, laser power of 1.25-1.75 kW and approach angle of 60-90°of laser beam axis to tool. The plan of experiments are based on central composite rotatable design L31 (43) orthogonal array. The surface temperature is measured via on-line measurement using infrared pyrometer. Parametric significance on surface temperature is analysed using response surface methodology (RSM), analysis of variance (ANOVA) and 3D surface graphs. The structural change of the material surface is observed using optical microscope and quantitative measurement of heat affected depth that are analysed by Vicker's hardness test. The results indicate that the laser power and approach angle are the most significant parameters to affect the surface temperature. The optimum ranges of laser power and approach angle was identified as 1.25-1.5 kW and 60-65° using overlaid contour plot. The developed second order regression model is found to be in good agreement with experimental values with R2 values of 0.96 and 0.94 respectively for surface temperature and heat affected depth.

  3. Mass-based design and optimization of wave rotors for gas turbine engine enhancement

    NASA Astrophysics Data System (ADS)

    Chan, S.; Liu, H.

    2017-03-01

    An analytic method aiming at mass properties was developed for the preliminary design and optimization of wave rotors. In the present method, we introduce the mass balance principle into the design and thus can predict and optimize the mass qualities as well as the performance of wave rotors. A dedicated least-square method with artificial weighting coefficients was developed to solve the over-constrained system in the mass-based design. This method and the adoption of the coefficients were validated by numerical simulation. Moreover, the problem of fresh air exhaustion (FAE) was put forward and analyzed, and exhaust gas recirculation (EGR) was investigated. Parameter analyses and optimization elucidated which designs would not only achieve the best performance, but also operate with minimum EGR and no FAE.

  4. Examination of optimal separator shape of polymer electrolyte fuel cell with numerical analysis including the effect of gas flow through gas diffusion layer

    NASA Astrophysics Data System (ADS)

    Inoue, Gen; Matsukuma, Yosuke; Minemoto, Masaki

    This work concentrates on the effects of channel depth and separator shape on cell output performance, current density distribution and gas flow condition in various conditions with PEFC numerical analysis model including gas flow through GDL. When GDL effective porosity was small, the effect of gas flow through GDL which was changed by channel depth on cell output performance became large. However, current density distribution was ununiform. As GDL permeability became larger, cell output density increased, but current density and gas flow rate distribution were ununiform. From the results of changing the gas flow rate, it was found that the ratio of the minimum gas flow rate to the inlet flow rate depended on channel depth. Furthermore, the optimal separator, which increased output density and made the current density distribution and gas flow rate distribution uniform, was examined. It was also found that cell performance had possible to be developed by improving the turning point of the serpentine separator.

  5. Binocular indirect ophthalmo microscope-assistant gas-perfused pars plana vitrectomy

    PubMed Central

    Zhang, Luyi; Yang, Xiaoli; Zheng, Qingqing; Wu, Miaoqin

    2016-01-01

    Abstract The vitreous sample has been used for the diagnosis of uveitis and intraocular malignancy for decades. The sample volume is usually limited to 1 mL with current techniques. In the present study, a novel technique for higher amount of vitreous sample acquisition, that is, Binocular Indirect Ophthalmo Microscope-assistant gas-perfused pars plana vitrectomy (BAG-PPV) was invented. For diagnostic purpose, BAG-PPV with 23-ga vitrectomy system was performed on a 54-year-old Chinese male with the symptom of bilateral atypical uveitis. More than 3 mL of vitreous sample per eye was collected without any significant complications. Cytopathology was confirmed on the basis of cell surface markers and released cytokines by flow cytometry analysis and cytokine assays respectively. A monoclonal B-cell population with the pattern of CD5−, CD10−, cyKi67+, CD71+, FMC7+, CD23−, and kappa light chain single expression for the right eye and a monoclonal B-cell pattern with CD5−, CD10−, cyKi67+, and kappa light chain restriction for the left eye were identified. The cytokine assay revealed high levels of interleukin (IL)-10 (90,838.30 and 41,098.0 pg/mL for the right and left eyes, respectively) and IL10/IL6 ratios for both eyes (with 90.78 and 63.26 for the IL10/IL6 ratios of the right and left eyes, respectively), while those for the cerebrospinal fluid were low (4.77 pg/mL for the IL10 level and 0.65 for the IL10/IL6 ratio). Based on the results, the patient was diagnosed with primary intraocular lymphoma for bilateral eyes. Our results demonstrated that diagnostic vitrectomy with BAG-PPV using the 23-ga vitrectomy system was safe, efficient, and able to provide useful diagnostic information for suspicious intraocular malignancy and other atypical uveitis. PMID:27930538

  6. Optimizing power cylinder lubrication on a large bore natural gas engine

    NASA Astrophysics Data System (ADS)

    Luedeman, Matthew R.

    More than 6000 integral compressors, located along America's natural gas pipelines, pump natural gas across the United States. These compressors are powered by 2-stroke, large bore natural gas burning engines. Lowering the operating costs, reducing the emissions, and ensuring that these engines remain compliant with future emission regulations are the drivers for this study. Substantial research has focused on optimizing efficiency and reducing the fuel derived emissions on this class of engine. However, significantly less research has focused on the effect and reduction of lubricating oil derived emissions. This study evaluates the impact of power cylinder lubricating oil on overall engine emissions with an emphasis on reducing oxidation catalyst poisoning. A traditional power cylinder lubricator was analyzed; power cylinder lubricating oil was found to significantly impact exhaust emissions. Lubricating oil was identified as the primary contributor of particulate matter production in a large bore natural gas engine. The particulate matter was determined to be primarily organic carbon, and most likely direct oil carryover of small oil droplets. The particulate matter production equated to 25% of the injected oil at a nominal power cylinder lubrication rate. In addition, power cylinder friction is considered the primary contributor to friction loss in the internal combustion engine. This study investigates the potential for optimizing power cylinder lubrication by controlling power cylinder injection to occur at the optimal time in the piston cycle. By injecting oil directly into the ring pack, it is believed that emissions, catalyst poisoning, friction, and wear can all be reduced. This report outlines the design and theory of two electronically controlled lubrication systems. Experimental results and evaluation of one of the systems is included.

  7. Microwave-assisted one-step extraction-derivatization for rapid analysis of fatty acids profile in herbal medicine by gas chromatography-mass spectrometry.

    PubMed

    Liu, Rui-Lin; Zhang, Jing; Mou, Zhao-Li; Hao, Shuang-Li; Zhang, Zhi-Qi

    2012-11-07

    A rapid and practical microwave-assisted one-step extraction-derivatization (MAED) method was developed for gas chromatography-mass spectrometry analysis of fatty acids profile in herbal medicine. Several critical experimental parameters for MAED, including reaction temperature, microwave power and the amount of derivatization reagent (methanol), were optimized with response surface methodology. The results showed that the chromatographic peak areas of total fatty acids and total unsaturated fatty acids content obtained with MAED were markedly higher than those obtained by the conventional Soxhlet or microwave extraction and then derivatization method. The investigation of kinetics and thermodynamics of the derivatization reaction revealed that microwave assistance could reduce activation energy and increase the Arrhenius pre-exponential factor. The MAED method simplified the sample preparation procedure, shortened the reaction time, but improved the extraction and derivatization efficiency of lipids and reduced ingredient losses, especially for the oxidization and isomerization of unsaturated fatty acids. The simplicity, speed and practicality of this method indicates great potential for high throughput analysis of fatty acids in natural medicinal samples.

  8. Incidence and Outcomes of Anterior Chamber Gas Bubble during Femtosecond Flap Creation for Laser-Assisted In Situ Keratomileusis.

    PubMed

    Rush, Sloan W; Cofoid, Philip; Rush, Ryan B

    2015-01-01

    Purpose. To report the incidence and outcomes of anterior chamber gas bubble formation during femtosecond laser flap creation for laser-assisted in situ keratomileusis (LASIK). Methods. The charts of 2,886 consecutive eyes that underwent femtosecond LASIK from May 2011 through August 2014 were retrospectively reviewed. The incidence, preoperative characteristics, intraoperative details, and postoperative outcomes were analyzed in subjects developing anterior chamber gas bubble formation during the procedure. Results. A total of 4 cases (0.14%) developed anterior chamber gas bubble formation during femtosecond laser flap creation. In all four cases, the excimer laser was unable to successfully track the pupil immediately following the anterior chamber bubble formation, temporarily postponing the completion of the procedure. There was an ethnicity predilection of anterior chamber gas formation toward Asians (p = 0.0055). An uncorrected visual acuity of 20/20 was ultimately achieved in all four cases without further complications. Conclusions. Anterior chamber gas bubble formation during femtosecond laser flap creation for LASIK is an uncommon event that typically results in a delay in treatment completion; nevertheless, it does influence final positive visual outcome.

  9. Low-thrust trajectory optimization of asteroid sample return mission with multiple revolutions and moon gravity assists

    NASA Astrophysics Data System (ADS)

    Tang, Gao; Jiang, FanHuag; Li, JunFeng

    2015-11-01

    Near-Earth asteroids have gained a lot of interest and the development in low-thrust propulsion technology makes complex deep space exploration missions possible. A mission from low-Earth orbit using low-thrust electric propulsion system to rendezvous with near-Earth asteroid and bring sample back is investigated. By dividing the mission into five segments, the complex mission is solved separately. Then different methods are used to find optimal trajectories for every segment. Multiple revolutions around the Earth and multiple Moon gravity assists are used to decrease the fuel consumption to escape from the Earth. To avoid possible numerical difficulty of indirect methods, a direct method to parameterize the switching moment and direction of thrust vector is proposed. To maximize the mass of sample, optimal control theory and homotopic approach are applied to find the optimal trajectory. Direct methods of finding proper time to brake the spacecraft using Moon gravity assist are also proposed. Practical techniques including both direct and indirect methods are investigated to optimize trajectories for different segments and they can be easily extended to other missions and more precise dynamic model.

  10. COMETBOARDS Can Optimize the Performance of a Wave-Rotor-Topped Gas Turbine Engine

    NASA Technical Reports Server (NTRS)

    Patnaik, Surya N.

    1997-01-01

    A wave rotor, which acts as a high-technology topping spool in gas turbine engines, can increase the effective pressure ratio as well as the turbine inlet temperature in such engines. The wave rotor topping, in other words, may significantly enhance engine performance by increasing shaft horse power while reducing specific fuel consumption. This performance enhancement requires optimum selection of the wave rotor's adjustable parameters for speed, surge margin, and temperature constraints specified on different engine components. To examine the benefit of the wave rotor concept in engine design, researchers soft coupled NASA Lewis Research Center's multidisciplinary optimization tool COMETBOARDS and the NASA Engine Performance Program (NEPP) analyzer. The COMETBOARDS-NEPP combined design tool has been successfully used to optimize wave-rotor-topped engines. For illustration, the design of a subsonic gas turbine wave-rotor-enhanced engine with four ports for 47 mission points (which are specified by Mach number, altitude, and power-setting combinations) is considered. The engine performance analysis, constraints, and objective formulations were carried out through NEPP, and COMETBOARDS was used for the design optimization. So that the benefits that accrue from wave rotor enhancement could be examined, most baseline variables and constraints were declared to be passive, whereas important parameters directly associated with the wave rotor were considered to be active for the design optimization. The engine thrust was considered as the merit function. The wave rotor engine design, which became a sequence of 47 optimization subproblems, was solved successfully by using a cascade strategy available in COMETBOARDS. The graph depicts the optimum COMETBOARDS solutions for the 47 mission points, which were normalized with respect to standard results. As shown, the combined tool produced higher thrust for all mission points than did the other solution, with maximum benefits

  11. Optimal placement of piezoelectric plates for active vibration control of gas turbine blades: experimental results

    NASA Astrophysics Data System (ADS)

    Botta, F.; Marx, N.; Gentili, S.; Schwingshackl, C. W.; Di Mare, L.; Cerri, G.; Dini, D.

    2012-04-01

    It is well known that the gas turbine blade vibrations can give rise to catastrophic failures and a reduction of the blades life because of fatigue related phenomena[1]-[3] . In last two decades, the adoption of piezoelectric elements, has received considerable attention by many researcher for its potential applicability to different areas of mechanical, aerospace, aeronautical and civil engineering. Recently, a number of studies of blades vibration control via piezoelectric plates and patches have been reported[4]-[6] . It was reported that the use of piezoelectric elements can be very effective in actively controlling vibrations. In one of their previous contributions[7] , the authors of the present manuscript studied a model to control the blade vibrations by piezoelectric elements and validated their results using a multi-physics finite elements package (COMSOL) and results from the literature. An optimal placement method of piezoelectric plate has been developed and applied to different loading scenarios for realistic configurations encountered in gas turbine blades. It has been demonstrated that the optimal placement depends on the spectrum of the load, so that segmented piezoelectric patches have been considered and, for different loads, an optimal combination of sequential and/or parallel actuation and control of the segments has been studied. In this paper, an experimental investigation carried out by the authors using a simplified beam configuration is reported and discussed. The test results obtained by the investigators are then compared with the numerical predictions [7] .

  12. Optimal integration strategies for a syngas fuelled SOFC and gas turbine hybrid

    NASA Astrophysics Data System (ADS)

    Zhao, Yingru; Sadhukhan, Jhuma; Lanzini, Andrea; Brandon, Nigel; Shah, Nilay

    This article aims to develop a thermodynamic modelling and optimization framework for a thorough understanding of the optimal integration of fuel cell, gas turbine and other components in an ambient pressure SOFC-GT hybrid power plant. This method is based on the coupling of a syngas-fed SOFC model and an associated irreversible GT model, with an optimization algorithm developed using MATLAB to efficiently explore the range of possible operating conditions. Energy and entropy balance analysis has been carried out for the entire system to observe the irreversibility distribution within the plant and the contribution of different components. Based on the methodology developed, a comprehensive parametric analysis has been performed to explore the optimum system behavior, and predict the sensitivity of system performance to the variations in major design and operating parameters. The current density, operating temperature, fuel utilization and temperature gradient of the fuel cell, as well as the isentropic efficiencies and temperature ratio of the gas turbine cycle, together with three parameters related to the heat transfer between subsystems are all set to be controllable variables. Other factors affecting the hybrid efficiency have been further simulated and analysed. The model developed is able to predict the performance characteristics of a wide range of hybrid systems potentially sizing from 2000 to 2500 W m -2 with efficiencies varying between 50% and 60%. The analysis enables us to identify the system design tradeoffs, and therefore to determine better integration strategies for advanced SOFC-GT systems.

  13. Purge-assisted headspace solid-phase microextraction combined with gas chromatography-mass spectrometry for determination of chlorophenols in aqueous samples.

    PubMed

    Ho, Hsin-Pin; Lee, Ren-Jye; Lee, Maw-Rong

    2008-12-12

    A simple, economical and very effective method is demonstrated for simultaneous determination of 2,4-dichlorophenol, 2,4,6-trichlorophenol, 2,3,4,6-tetrachlorophenol and pentachlorophenol, in aqueous samples, by using purge-assisted headspace solid-phase microextraction (PA/HS-SPME) coupled to gas chromatography-mass spectrometry (GC-MS). In the new method, purging the sample enhances the removal of the trace chlorophenols without derivatization from the matrices to the headspace. Extraction parameters including extraction temperature, purge gas flow rate and extraction time were systematically investigated. Under optimal conditions, the relative standard deviations (RSDs) were 4-11% at 50 pg/mL and 5-14% at 5 pg/mL, respectively. The recoveries were in the range of 83-114%. Detection limits were determined at the fg level. These results indicate that PA/HS-SPME provides a significant contribution to highly efficient extraction of semi-volatile CPs, especially for pentachlorophenol, which has the smallest Henry's constant and large octanol-water partitioning coefficient. In addition, the proposed method was successfully applied to the analysis of chlorophenols in landfill leachate. New perspectives are opened for headspace extraction of relatively low vapor pressure compounds in complex matrices.

  14. Comparison and improvements of optimization methods for gas emission source identification

    NASA Astrophysics Data System (ADS)

    Ma, Denglong; Deng, Jianqiang; Zhang, Zaoxiao

    2013-12-01

    Identification of gas leakage source term is important for atmosphere safety. Optimization is one useful method to determine leakage source parameters. The performances of different optimization methods, including genetic algorithm (GA), simulated annealing (SA), pattern search (PS) method, Nelder-Mead simplex method (N-M simplex) and their hybrid optimization methods, were discussed. It was seen that GA-PS hybrid optimization has the best performance for location and source strength estimation while the hybrid methods with N-M simplex is the best one when time cost and robustness are added into consideration. Moreover, the performances of these optimization methods with different initial values, signal noise ratios (SNR), sensor numbers and sensor distribution forms were discussed. Further, experiment data test showed that the less deviation of forward simulation model from the real condition, the better performance of the source parameters determination method is. When two error correction coefficients were added to the Gaussian dispersion model, the accuracy of source strength and downwind distance estimation is increased. Other different cost functions were also applied to identify the source parameters. Finally, a new forward dispersion model based on radial basis function neural network and Gaussian model (Gaussian-RBF network) was presented and then it was applied to determine the leakage source parameters. The results showed that the performance of optimization method based on Gaussian-RBF network model is significantly improved, especially for location estimation. Therefore, the optimization method with a good selection of forward dispersion model and cost function will obtain a satisfactory estimation result.

  15. Optimization of ultrasonic-assisted extraction of antioxidant compounds from Guava (Psidium guajava L.) leaves using response surface methodology

    PubMed Central

    Kong, Fansheng; Yu, Shujuan; Feng, Zeng; Wu, Xinlan

    2015-01-01

    Objective: To optimization of extraction of antioxidant compounds from guava (Psidium guajava L.) leaves and showed that the guava leaves are the potential source of antioxidant compounds. Materials and Methods: The bioactive polysaccharide compounds of guava leaves (P. guajava L.) were obtained using ultrasonic-assisted extraction. Extraction was carried out according to Box-Behnken central composite design, and independent variables were temperature (20–60°C), time (20–40 min) and power (200–350 W). The extraction process was optimized by using response surface methodology for the highest crude extraction yield of bioactive polysaccharide compounds. Results: The optimal conditions were identified as 55°C, 30 min, and 240 W. 1,1-diphenyl-2-picryl-hydrazyl and hydroxyl free radical scavenging were conducted. Conclusion: The results of quantification showed that the guava leaves are the potential source of antioxidant compounds. PMID:26246720

  16. Real-World Application of Robust Design Optimization Assisted by Response Surface Approximation and Visual Data-Mining

    NASA Astrophysics Data System (ADS)

    Shimoyama, Koji; Jeong, Shinkyu; Obayashi, Shigeru

    A new approach for multi-objective robust design optimization was proposed and applied to a real-world design problem with a large number of objective functions. The present approach is assisted by response surface approximation and visual data-mining, and resulted in two major gains regarding computational time and data interpretation. The Kriging model for response surface approximation can markedly reduce the computational time for predictions of robustness. In addition, the use of self-organizing maps as a data-mining technique allows visualization of complicated design information between optimality and robustness in a comprehensible two-dimensional form. Therefore, the extraction and interpretation of trade-off relations between optimality and robustness of design, and also the location of sweet spots in the design space, can be performed in a comprehensive manner.

  17. A comprehensive method for preliminary design optimization of axial gas turbine stages. II - Code verification

    NASA Technical Reports Server (NTRS)

    Jenkins, R. M.

    1983-01-01

    The present effort represents an extension of previous work wherein a calculation model for performing rapid pitchline optimization of axial gas turbine geometry, including blade profiles, is developed. The model requires no specification of geometric constraints. Output includes aerodynamic performance (adiabatic efficiency), hub-tip flow-path geometry, blade chords, and estimates of blade shape. Presented herein is a verification of the aerodynamic performance portion of the model, whereby detailed turbine test-rig data, including rig geometry, is input to the model to determine whether tested performance can be predicted. An array of seven (7) NASA single-stage axial gas turbine configurations is investigated, ranging in size from 0.6 kg/s to 63.8 kg/s mass flow and in specific work output from 153 J/g to 558 J/g at design (hot) conditions; stage loading factor ranges from 1.15 to 4.66.

  18. Microwave plasma assisted supersonic gas jet deposition of thin film materials

    DOEpatents

    Schmitt, III, Jerome J.; Halpern, Bret L.

    1993-01-01

    An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures.

  19. Optimization and analysis of mixed refrigerant composition for the PRICO natural gas liquefaction process

    NASA Astrophysics Data System (ADS)

    Xu, Xiongwen; Liu, Jinping; Cao, Le

    2014-01-01

    In this paper, the energy optimization of the PRICO natural gas liquefaction (LNG) process was performed with the genetic algorithm (GA) and the process simulation software Aspen Plus. Then the characteristics of the heat transfer composite curves of the cold box were obtained and analyzed. Based on it, the heat exchange process in the cold box was divided into three regions. At last, in order to find the relationship between the energy consumption and the composition of the mixed refrigerant, the effects of the refrigerant flow composition on the temperature difference and the pinch point location were deeply investigated, which would be useful to guide the refrigerant charging.

  20. Optimization of Sampling Positions for Measuring Ventilation Rates in Naturally Ventilated Buildings Using Tracer Gas

    PubMed Central

    Shen, Xiong; Zong, Chao; Zhang, Guoqiang

    2012-01-01

    Finding out the optimal sampling positions for measurement of ventilation rates in a naturally ventilated building using tracer gas is a challenge. Affected by the wind and the opening status, the representative positions inside the building may change dynamically at any time. An optimization procedure using the Response Surface Methodology (RSM) was conducted. In this method, the concentration field inside the building was estimated by a three-order RSM polynomial model. The experimental sampling positions to develop the model were chosen from the cross-section area of a pitched-roof building. The Optimal Design method which can decrease the bias of the model was adopted to select these sampling positions. Experiments with a scale model building were conducted in a wind tunnel to achieve observed values of those positions. Finally, the models in different cases of opening states and wind conditions were established and the optimum sampling position was obtained with a desirability level up to 92% inside the model building. The optimization was further confirmed by another round of experiments.

  1. Ultrasound-assisted extraction of natural antioxidants from the flower of Limonium sinuatum: Optimization and comparison with conventional methods.

    PubMed

    Xu, Dong-Ping; Zheng, Jie; Zhou, Yue; Li, Ya; Li, Sha; Li, Hua-Bin

    2017-02-15

    Natural antioxidants are widely used as dietary supplements or food additives. An optimized method of ultrasound-assisted extraction (UAE) was proposed for the effective extraction of antioxidants from the flowers of Limonium sinuatum and evaluated by response surface methodology. In this study, ethanol concentration, ratio of solvent to solid, ultrasonication time and temperature were investigated and optimized using a central composite rotatable design. The optimum extraction conditions were as follows: ethanol concentration, 60%; ratio of solvent to solid, 56.9:1mL/g; ultrasonication time, 9.8min; and temperature, 40°C. Under the optimal UAE conditions, the experimental values (483.01±15.39μmolTrolox/gDW) matched with those predicted (494.13μmolTrolox/gDW) within a 95% confidence level. In addition, the antioxidant activities of UAE were compared with those of conventional maceration and Soxhlet extraction methods, and the ultrasound-assisted extraction could give higher yield of antioxidants and markedly reduce the extraction time.

  2. Optimization of microwave-assisted extraction of polyphenols from apple pomace using response surface methodology and HPLC analysis.

    PubMed

    Bai, Xue-Lian; Yue, Tian-Li; Yuan, Ya-Hong; Zhang, Hua-Wei

    2010-12-01

    A simple and efficient microwave-assisted extraction of polyphenols from industrial apple pomace was developed and optimized by the maximization of the yield using response surface methodology. A Box-Behnken design was used to monitor the effect of microwave power, extraction time, ethanol concentration and ratio of solvent to raw material (g/mL) on the polyphenols yield. The results showed that the optimal conditions were as follows: microwave power 650.4 W, extraction time 53.7 s, ethanol concentration 62.1% and ratio of solvent to raw material 22.9:1. Validation tests indicated that the actual yield of polyphenols was 62.68±0.35 mg gallic acid equivalents per 100 g dry apple pomace with RSD=0.86% (n=5) under the optimal conditions, which was in good agreement with the predicted yield and higher than those of reflux and ultrasonic-assisted extraction methods. HPLC analysis indicated that the major polyphenols of apple pomace consisted of chlorogenic acid, caffeic acid, syrigin, procyanidin B2, (-)-epicatechin, cinnamic acid, coumaric acid, phlorizin and quercetin, of which procyanidin B2 had the highest content of 219.4 mg/kg.

  3. Multivariate optimization of an ultrasound-assisted extraction procedure for Cu, Mn, Ni and Zn determination in ration to chickens.

    PubMed

    Barros, Joélia M; Bezerra, Marcos A; Valasques, Gisseli S; Do Nascimento Jr, Baraquízio B; Souza, Anderson S; De Aragão, Nádia M

    2013-09-01

    In this work, multivariate optimization techniques were used to develop a method based on the ultrasound-assisted extraction for copper, manganese, nickel and zinc determination from rations for chicken nutrition using flame atomic absorption spectrometry. The proportions of extracting components (2.0 mol.L-1 nitric, hydrochloric and acetic acid solutions) were optimized using centroid-simplex mixture design. The optimum proportions of this mixture taken as percentage of each component were respectively 20%, 37% and 43%. Variables of method (sample mass, sonication time and final acid concentration) were optimized using Doehlert design. The optimum values found for these variables were respectively 0.24 g, 18s and 3.6 mol.L-1. The developed method allows copper, manganese, nickel and zinc determination with quantification limits of 2.82; 4.52; 10.7; e 9.69 µg.g-1, and precision expressed as relative standard deviation (%RSD, 25 µg.g-1, N = 5) of 5.30; 2.13; 0.88; and 0.83%, respectively. This method was applied in the analytes determination from chicken rations collected from specialized commerce in Jequié city (Bahia State/Brazil). Application of paired t-test at the obtained results, in a confidence level of 95%, does not show significant difference between the proposed method and the microwave-assisted digestion.

  4. Multi-response optimization of factors affecting ultrasonic assisted extraction from Iranian basil using central composite design.

    PubMed

    Izadiyan, Parisa; Hemmateenejad, Bahram

    2016-01-01

    The present study reports on the extraction of antioxidant compounds from Iranian Ocimum basilicum. Central composite design (CCD) was used to investigate the effect of extraction variables on the ultrasound-assisted extraction (UAE). Three independent variables including temperature, methanol to water ratio percent, and sonication time were studied for simultaneous optimization of antioxidant capacity, total phenolic content and extraction yield. Both quantitative modeling and response surface methodology suggested that methanol to water ratio percent and extraction temperature were the most effective parameters of UAE process. However, sonication time was found out to be an insignificant factor in ultrasound-assisted extraction of antioxidant and total phenolic compounds of O. basilicum. The optimum conditions were determined as temperature of 59 °C, methanol to water ratio of 65.2% (v/v), and extraction time of 20 min.

  5. Ultrasound-assisted extraction of phenolics from wine lees: modeling, optimization and stability of extracts during storage.

    PubMed

    Tao, Yang; Wu, Di; Zhang, Qing-An; Sun, Da-Wen

    2014-03-01

    The ultrasound-assisted extraction process of phenolics including anthocyanins from wine lees was modeled and optimized in this research. An ultrasound bath system with the frequency of 40 kHz was used and the acoustic energy density during extraction was identified to 48 W/L. The effects of extraction time, extraction temperature, solvent-to-solid ratio and the solvent composition on the extraction yields of total phenolics and total anthocyanins were taken into account. The extraction process was simulated and optimized by means of artificial neural network (ANN) and genetic algorithm (GA). The constructed ANN models were accurate to predict the extraction yields of both total phenolics and total anthocyanins according to the statistical analysis. Meanwhile, the input space of the ANN models was optimized by GA, so as to maximize the extraction yields. Under the optimal conditions, the experimental yields of total phenolics and total anthocyanins were 58.76 and 6.69 mg/g, respectively, which agreed with the predicted values. Furthermore, more amounts of total phenolics and total anthocyanins were extracted by ultrasound at the optimal conditions than by conventional maceration. On the other hand, the stability of phenolics in the liquid extracts obtained from ultrasound-assisted extraction during storage was evaluated. After 30-day storage, the total phenolic contents in extracts stored at 4 °C and 20 °C decreased by 12.5% and 12.1%, respectively. Moreover, anthocyanins were more stable at 4 °C while tartaric esters and flavonols exhibited a better stability at 20 °C. Overall, the loss of phenolics during storage found in this study could be acceptable.

  6. Microwave plasma assisted supersonic gas jet deposition of thin film materials

    DOEpatents

    Schmitt, J.J. III; Halpern, B.L.

    1993-10-26

    An apparatus for fabricating thin film materials utilizing high speed gas dynamics relies on supersonic free jets of carrier gas to transport depositing vapor species generated in a microwave discharge to the surface of a prepared substrate where the vapor deposits to form a thin film. The present invention generates high rates of deposition and thin films of unforeseen high quality at low temperatures. 5 figures.

  7. Optimized design of substrate-integrated hollow waveguides for mid-infrared gas analyzers

    NASA Astrophysics Data System (ADS)

    Fortes, Paula Regina; Flávio da Silveira Petruci, João; Wilk, Andreas; Alves Cardoso, Arnaldo; Milton Raimundo, Ivo, Jr.; Mizaikoff, Boris

    2014-09-01

    Design and analytical performance studies are presented for optimizing a new generation of hollow waveguides suitable for quantitative gas sensing—the so-called substrate-integrated hollow waveguide (iHWG). Taking advantage of a particularly compact Fourier transform infrared spectrometer optimized iHWG geometries are investigated toward the development of a multi-constituent breath analysis tool compatible for usage, e.g., in exhaled mouse breath analysis. Three different iHWG geometries were compared, i.e., straight, meandering one-turn and meandering two-turn waveguide channels aiming at maximizing the related analytical figures-of-merit including the achievable limits of detection for selected exemplary analytes. In addition, efficient coupling of infrared (IR) radiation into straight iHWGs was investigated using integrated optical funnel structures. Calibration functions of butane in nitrogen serving as IR-transparent matrix gas were established and compared for the various iHWG geometries. Given the tidal volume of exhaled breath (EB) samples ranging from a few hundreds of milliliters (human, swine) to a few hundreds of microliters (mouse), it is essential for any given analysis to select an appropriate waveguide geometry and volume yet maintaining (i) a compact footprint ensuring hand-held instrumentation, (ii) modular exchange of the iHWG according to the analysis requirement yet with constant device format, and (iii) enabling inline/online measurement capabilities toward continuous EB diagnostics.

  8. Optimization of microporous palm shell activated carbon production for flue gas desulphurization: experimental and statistical studies.

    PubMed

    Sumathi, S; Bhatia, S; Lee, K T; Mohamed, A R

    2009-02-01

    Optimizing the production of microporous activated carbon from waste palm shell was done by applying experimental design methodology. The product, palm shell activated carbon was tested for removal of SO2 gas from flue gas. The activated carbon production was mathematically described as a function of parameters such as flow rate, activation time and activation temperature of carbonization. These parameters were modeled using response surface methodology. The experiments were carried out as a central composite design consisting of 32 experiments. Quadratic models were developed for surface area, total pore volume, and microporosity in term of micropore fraction. The models were used to obtain the optimum process condition for the production of microporous palm shell activated carbon useful for SO2 removal. The optimized palm shell activated carbon with surface area of 973 m(2)/g, total pore volume of 0.78 cc/g and micropore fraction of 70.5% showed an excellent agreement with the amount predicted by the statistical analysis. Palm shell activated carbon with higher surface area and microporosity fraction showed good adsorption affinity for SO2 removal.

  9. Method for microwave plasma assisted supersonic gas jet deposition of thin films

    DOEpatents

    Schmitt, J.J. III; Halpern, B.L.

    1994-10-18

    A thin film is formed on a substrate positioned in a vacuum chamber by use of a gas jet apparatus affixed to a vacuum chamber port and having an outer nozzle with an interior cavity into which carrier gas is fed, an inner nozzle located within the outer nozzle interior cavity into which reactant gas is introduced, a tip of the inner nozzle being recessed from the vacuum chamber port within the outer nozzle interior cavity, and a microwave discharge device configured about the apparatus for generating a discharge in the carrier gas and reactant gas only in a portion of the outer nozzle interior cavity extending from approximately the inner nozzle tip towards the vacuum chamber. A supersonic free jet of carrier gas transports vapor species generated in the microwave discharge to the surface of the substrate to form a thin film on the substrate. The substrate can be translated from the supersonic jet to a second supersonic jet in less time than needed to complete film formation so that the film is chemically composed of chemical reaction products of vapor species in the jets. 5 figs.

  10. Method for microwave plasma assisted supersonic gas jet deposition of thin films

    DOEpatents

    Schmitt, III, Jerome J.; Halpern, Bret L.

    1994-01-01

    A thin film is formed on a substrate positioned in a vacuum chamber by use of a gas jet apparatus affixed to a vacuum chamber port and having an outer nozzle with an interior cavity into which carrier gas is fed, an inner nozzle located within the outer nozzle interior cavity into which reactant gas is introduced, a tip of the inner nozzle being recessed from the vacuum chamber port within the outer nozzle interior cavity, and a microwave discharge device configured about the apparatus for generating a discharge in the carrier gas and reactant gas only in a portion of the outer nozzle interior cavity extending from approximately the inner nozzle tip towards the vacuum chamber. A supersonic free jet of carrier gas transports vapor species generated in the microwave discharge to the surface of the substrate to form a thin film on the substrate. The substrate can be translated from the supersonic jet to a second supersonic jet in less time than needed to complete film formation so that the film is chemically composed of chemical reaction products of vapor species in the jets.

  11. Optimization and Prediction of Ultimate Tensile Strength in Metal Active Gas Welding

    PubMed Central

    Ampaiboon, Anusit; Lasunon, On-Uma; Bubphachot, Bopit

    2015-01-01

    We investigated the effect of welding parameters on ultimate tensile strength of structural steel, ST37-2, welded by Metal Active Gas welding. A fractional factorial design was used for determining the significance of six parameters: wire feed rate, welding voltage, welding speed, travel angle, tip-to-work distance, and shielded gas flow rate. A regression model to predict ultimate tensile strength was developed. Finally, we verified optimization of the process parameters experimentally. We achieved an optimum tensile strength (558 MPa) and wire feed rate, 19 m/min, had the greatest effect, followed by tip-to-work distance, 7 mm, welding speed, 200 mm/min, welding voltage, 30 V, and travel angle, 60°. Shield gas flow rate, 10 L/min, was slightly better but had little effect in the 10–20 L/min range. Tests showed that our regression model was able to predict the ultimate tensile strength within 4%. PMID:26491719

  12. Determination of nitroaromatic explosives in water samples by direct ultrasound-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

    PubMed

    Cortada, Carol; Vidal, Lorena; Canals, Antonio

    2011-10-15

    A fast, simple, inexpensive, sensitive, efficient and environmental friendly direct ultrasound-assisted dispersive liquid-liquid microextraction (DUSA-DLLME) procedure has been developed to concentrate five nitroaromatic explosives from water samples prior to quantification by gas chromatography-mass spectrometry (GC-MS). An efficient ultrasonic probe has been used to radiate directly the samples producing very fine emulsions from immiscible liquids. A D-optimal design was used for optimizing the factors and to evaluate their influential upon extraction. The optimum experimental conditions were: sample volume, 10 mL; extraction time, 60s; cycles, 0.6s(s(-1)); power of ultrasound energy, 40% (70 W); and, extractant solvent (chlorobenzene) volume, 20 μL. Under the optimized experimental conditions the method presents good level of repeatability with coefficients of variation under 6% (n=8; spiking level 10 μg L(-1)). Calculated calibration curves gave high level of linearity with correlation coefficient values between 0.9949 and 0.9992. Limits of detection were ranged between 0.03 and 0.91 μg L(-1). Finally, the proposed method was applied to the analysis of two types of water samples, reservoir and effluent wastewater. The samples were previously analysed and confirmed free of target analytes. At 5 μg L(-1) spiking level recovery values ranged between 75 and 96% for reservoir water sample showing that the matrix had a negligible effect upon extraction. However, a noticeable matrix effect (around 50% recovery) was observed for effluent wastewater sample. In order to alleviate this matrix effect, the standard addition calibration method was used for quantitative determination. This calibration method supplied recovery values ranged between 71 and 79%. The same conclusions have been obtained from an uncertainty budget evaluation study.

  13. Determination of geosmin and 2-methylisoborneol in water and wine samples by ultrasound-assisted dispersive liquid-liquid microextraction coupled to gas chromatography-mass spectrometry.

    PubMed

    Cortada, Carol; Vidal, Lorena; Canals, Antonio

    2011-01-07

    A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid-liquid microextraction (USADLLME) procedure has been developed to preconcentrate geosmin and 2-methylisoborneol (MIB) from water and wine samples prior to quantification by gas chromatography-mass spectrometry (GC-MS). A two-stage multivariate optimization approach was developed by means of a Plackett-Burman design for screening and selecting the significant variables involved in the USADLLME procedure, which was later optimized by means of a circumscribed central composite design. The optimum conditions were: solvent volume, 8μL; solvent type: tetrachloroethylene; sample volume, 12 mL; centrifugation speed, 2300 rpm; extraction temperature 20 °C; extraction time, 3 min; and centrifugation time, 3 min. Under the optimized experimental conditions the method gave good levels of repeatability with coefficient of variation under 11% (n=10). Limits of detection were 2 and 9 ng L⁻¹ for geosmin and MIB, respectively. Calculated calibration curves gave high levels of linearity with correlation coefficient values of 0.9988 and 0.9994 for geosmin and MIB, respectively. Finally, the proposed method was applied to the analysis of two water (reservoir and tap) samples and three wine (red, rose and white) samples. The samples were previously analyzed and confirmed free of target analytes. Recovery values ranged between 70 and 113% at two spiking levels (0.25 μg L⁻¹ and 30 ng L⁻¹) showing that the matrix had a negligible effect upon extraction. Only red wine showed a noticeable matrix effect (70-72% recovery). Similar conclusions have been obtained from an uncertainty budget evaluation study.

  14. Response surface modeling and optimization of ultrasound-assisted extraction of three flavonoids from tartary buckwheat (Fagopyrum tataricum)

    PubMed Central

    Peng, Lian-Xin; Zou, Liang; Zhao, Jiang-Lin; Xiang, Da-Bing; Zhu, Peng; Zhao, Gang

    2013-01-01

    Background: Buckwheat (Fagopyrum spp., Polygonaceae) is a widely planted food crop. Flavonoids, including quercetin, rutin, and kaempferol, are the main bioactive components in tartary buckwheat (Fagopyrum tataricum (L.) Gaertn). From the nutriological and pharmacological perspectives, flavonoids have great value in controlling blood glucose and blood pressure levels, and they also have antioxidant properties. Objective: To optimize the conditions for extraction of quercetin, rutin, and kaempferol from F. tataricum. Materials and Methods: A combination of ultrasound-assisted extraction (UAE) and response surface methodology (RSM) was used for flavonoid extraction and yield assessment. The RSM was based on a three-level, three-variable Box-Behnken design. Results: Flavonoids were optimally extracted from F. tataricum by using 72% methanol, at 60°C, for 21 minutes. Under these conditions, the obtained extraction yield of the total flavonoids was 3.94%. Conclusion: The results indicated that the UAE method was effective for extraction of flavonoids from tartary buckwheat. PMID:23930003

  15. Optimization for ultrasound-assisted extraction of polysaccharides with antioxidant activity in vitro from the aerial root of Ficus microcarpa.

    PubMed

    Jiang, Changxing; Li, Xia; Jiao, Yunpeng; Jiang, Dingyun; Zhang, Ling; Fan, Benxia; Zhang, Qianghua

    2014-09-22

    In this study, optimization of ultrasound-assisted extraction and antioxidant activity of polysaccharides from the aerial root of Ficus microcarpa (FMPS) were investigated. The optimal conditions for extraction of FMPS were determined as followings: ultrasound power 200 W, ultrasound temperature 70°C, extraction temperature 74°C, liquid-solid ratio 35, extraction time 238 min, ultrasound time 49 min. The experimental yield of FMPS (3.44%) obtained under these conditions was well agreement with the value predicted by the model. In addition, Fourier transform-infrared spectroscopy and antioxidant activity assays revealed that FMPS were acidic polysaccharides and had strong Fe2+ chelating activity and moderate hydrogen peroxide scavenging effect. Further work on the purification, structure characterization and antioxidant activity in vivo of FMPS is in progress.

  16. Teaching Assistant Training and Supervision: An Examination of Optimal Delivery Modes and Skill Emphases

    ERIC Educational Resources Information Center

    Prieto, Loreto R.; Yamokoski, Cynthia A.; Meyers, Steven A.

    2007-01-01

    We collected data from 149 graduate teaching assistants at a Midwestern university concerning their classroom duties, experiences with TA training and supervision, sense of self-efficacy toward teaching, preference for supervisory style, and feedback on those modes and skill domains in TA training they felt were most effective and best prepared…

  17. Single-step syngas-to-dimethyl ether processes for optimal productivity, minimal emissions, and natural gas-derived syngas

    SciTech Connect

    Peng, X.D.; Wang, A.W.; Toseland, B.A.; Tijm, P.J.A.

    1999-11-01

    Process schemes for single-step syngas-to-dimethyl ether (DME) were developed in two stages: (1) the performance of the syngas-to-DME reactor was optimized with respect to the feed gas composition and (2) the optimal reactor feed gas system was integrated with synthesis gas generators. It was shown that the reactor performance is very sensitive to the H{sub 2}:CO ratio in the feed gas. The optimal DME productivity and best material utilization were obtained with a feed gas containing 50% hydrogen and 50% carbon monoxide. In the second phase the syngas generation units considered were CO{sub 2}-methane reformer, steam-methane reformer, methane partial oxidation, and coal gasifier. The integration adjusts the H{sub 2}:CO ratio in natural gas-derived syngas to fit the optimal DME reactor operation and minimizes CO{sub 2} emissions and material loss. The technical feasibility of these schemes was demonstrated by simulations using realistic reactor models, kinetics, and thermodynamics under commercially relevant conditions.

  18. Optimal Integrated Design of Air Separation Unit and Gas Turbine Block for IGCC Systems

    SciTech Connect

    Ravindra S. Kamath; Ignacio E. Grossmann; Lorenz T. Biegler; Stephen E. Zitney

    2009-01-01

    The Integrated Gasification Combined Cycle (IGCC) systems are considered as a promising technology for power generation. However, they are not yet in widespread commercial use and opportunities remain to improve system feasibility and profitability via improved process integration. This work focuses on the integrated design of gasification system, air separation unit (ASU) and the gas turbine (GT) block. The ASU supplies oxygen to the gasification system and it can also supply nitrogen (if required as a diluent) to the gas turbine block with minimal incremental cost. Since both GT and the ASU require a source of compressed air, integrating the air requirement of these units is a logical starting point for facility optimization (Smith et al., 1997). Air extraction from the GT can reduce or avoid the compression cost in the ASU and the nitrogen injection can reduce NOx emissions and promote trouble-free operation of the GT block (Wimer et al., 2006). There are several possible degrees of integration between the ASU and the GT (Smith and Klosek, 2001). In the case of 'total' integration, where all the air required for the ASU is supplied by the GT compressor and the ASU is expected to be an elevated-pressure (EP) type. Alternatively, the ASU can be 'stand alone' without any integration with the GT. In this case, the ASU operates at low pressure (LP), with its own air compressor delivering air to the cryogenic process at the minimum energy cost. Here, nitrogen may or may not be injected because of the energy penalty issue and instead, syngas humidification may be preferred. A design, which is intermediate between these two cases, involves partial supply of air by the gas turbine and the remainder by a separate air compressor. These integration schemes have been utilized in some IGCC projects. Examples include Nuon Power Plant at Buggenum, Netherlands (both air and nitrogen integration), Polk Power Station at Tampa, US (nitrogen-only integration) and LGTI at Plaquemine

  19. Optimization of Ultrasound-Assisted Extraction of phenolic compounds and anthocyanins from blueberry (Vaccinium ashei) wine pomace.

    PubMed

    He, Bo; Zhang, Ling-Li; Yue, Xue-Yang; Liang, Jin; Jiang, Jun; Gao, Xue-Ling; Yue, Peng-Xiang

    2016-08-01

    Ultrasound-Assisted Extraction (UAE) of total anthocyanins (TA) and phenolics (TP) from Blueberry Wine Pomace (BWP) was optimized using Response Surface Methodology (RSM). A Box-Behnken design was used to predict that the optimized conditions were an extraction temperature of 61.03°C, a liquid-solid ratio of 21.70mL/g and a sonication time of 23.67min. Using the modeled optimized conditions, the predicted and experimental yields of TA and TP were within a 2% difference. The yields of TA and TP obtained through the optimized UAE method were higher than those using a Conventional Solvent Extraction (CSE) method. Seven anthocyanins, namely delphinidin-3-O-glucoside, delphindin-3-O-arabinoside, petunidin-3-O-glucoside, cyanidin-3-O-arabinoside, cyanidin-3-O-glucoside, malvidin-3-O-glucoside and malvidin-3-O-arabinoside, were found in the BWP extract from both the UAE and CSE methods.

  20. Optimized production of vanillin from green vanilla pods by enzyme-assisted extraction combined with pre-freezing and thawing.

    PubMed

    Zhang, Yanjun; Mo, Limei; Chen, Feng; Lu, Minquan; Dong, Wenjiang; Wang, Qinghuang; Xu, Fei; Gu, Fenglin

    2014-02-19

    Production of vanillin from natural green vanilla pods was carried out by enzyme-assisted extraction combined with pre-freezing and thawing. In the first step the green vanilla pods were pre-frozen and then thawed to destroy cellular compartmentation. In the second step pectinase from Aspergillus niger was used to hydrolyze the pectin between the glucovanillin substrate and β-glucosidase. Four main variables, including enzyme amount, reaction temperature, time and pH, which were of significance for the vanillin content were studied and a central composite design (CCD) based on the results of a single-factor tests was used. Response surface methodology based on CCD was employed to optimize the combination of enzyme amount, reaction temperature, time, and pH for maximum vanillin production. This resulted in the optimal condition in regards of the enzyme amount, reaction temperature, time, and pH at 84.2 mg, 49.5 °C, 7.1 h, and 4.2, respectively. Under the optimal condition, the experimental yield of vanillin was 4.63% ± 0.11% (dwb), which was in good agreement with the value predicted by the model. Compared to the traditional curing process (1.98%) and viscozyme extract (2.36%), the optimized method for the vanillin production significantly increased the yield by 133.85% and 96%, respectively.

  1. Optimization of enzyme-assisted extraction and characterization of collagen from Chinese sturgeon (Acipenser sturio Linnaeus) skin

    PubMed Central

    Feng, Weiwei; Zhao, Ting; Zhou, Ye; Li, Fang; Zou, Ye; Bai, Shiqi; Wang, Wei; Yang, Liuqing; Wu, Xiangyang

    2013-01-01

    Background: Sturgeon (Acipenser sturio Linnaeus) skin contains high amount of nutrients including unsaturated fatty acids and collagen. A pepsin-assisted extraction procedure was developed and optimized for the extraction of collagen from Chinese sturgeon (Acipenser sturio Linnaeus) skins. Objective: To determine the optimum conditions with the maximum yield of the pepsin-soluble collagen (PSC) extraction. Materials and Methods: The conditions of the extraction were optimized using response surface methodology. The Box–Behnken design was used to evaluate the effects of the three independent variables (extraction time, enzyme concentration, and solid–liquid ratio) on the PSC yield of the sturgeon skin. Results: The optimal conditions were: solid–liquid ratio of 1:11.88, enzyme concentration of 2.42%, and extraction time of 6.45 h. The maximum yield of 86.69% of PSC was obtained under the optimal conditions. This value was not significantly different from the predicted value (87.4%) of the RSM (P < 0.05). Conclusion: The results of this study indicated that the production of PSC from sturgeon skin is feasible and beneficial. The patterns of sodium dodecyl sulfate-polyacrylamide gel electrophoretic patterns (SDS-PAGE) indicated that the sturgeon skin contains type I collagen, which is made of α-chain and β-chain. The infrared spectra of the collagens also indicated that pepsin hydrolysis does not affect the secondary structure of collagen, especially triple-helical structure. PMID:24143042

  2. A near optimal guidance algorithm for aero-assisted orbit transfer

    NASA Astrophysics Data System (ADS)

    Calise, Anthony J.; Bae, Gyoung H.

    The paper presents a near optimal guidance algorithm for aero-assited orbit plane change, based on minimizing the energy loss during the atmospheric portion of the maneuver. The guidance algorithm makes use of recent results obtained from energy state approximations and singular perturbation analysis of optimal heading change for a hypersonic gliding vehicle. This earlier work ignored the terminal constraint on altitude needed to insure that the vehicle exits that atmosphere. Thus, the resulting guidance algorithm was only appropriate for maneuvering reentry vehicle guidance. In the context of singular perturbation theory, a constraint on final altitude gives rise to a difficult terminal boundary layer problem, which cannot be solved in closed form. This paper will demonstrate the near optimality of a predictive/corrective guidance algorithm for the terminal maneuver. Comparisons are made to numerically optimized trajectories for a range or orbit plane angles.

  3. A near optimal guidance algorithm for aero-assisted orbit transfer

    NASA Technical Reports Server (NTRS)

    Calise, Anthony J.; Bae, Gyoung H.

    1988-01-01

    The paper presents a near optimal guidance algorithm for aero-assited orbit plane change, based on minimizing the energy loss during the atmospheric portion of the maneuver. The guidance algorithm makes use of recent results obtained from energy state approximations and singular perturbation analysis of optimal heading change for a hypersonic gliding vehicle. This earlier work ignored the terminal constraint on altitude needed to insure that the vehicle exits that atmosphere. Thus, the resulting guidance algorithm was only appropriate for maneuvering reentry vehicle guidance. In the context of singular perturbation theory, a constraint on final altitude gives rise to a difficult terminal boundary layer problem, which cannot be solved in closed form. This paper will demonstrate the near optimality of a predictive/corrective guidance algorithm for the terminal maneuver. Comparisons are made to numerically optimized trajectories for a range or orbit plane angles.

  4. Optimization of Ultrasound-Assisted Extraction of Natural Antioxidants from the Flower of Jatropha integerrima by Response Surface Methodology.

    PubMed

    Xu, Dong-Ping; Zhou, Yue; Zheng, Jie; Li, Sha; Li, An-Na; Li, Hua-Bin

    2015-12-24

    An ultrasound-assisted extraction (UAE) method was developed for the efficient extraction of natural antioxidants from the flowers of Jatropha integerrima. Four independent variables, including ethanol concentration, solvent/material ratio, ultrasound irradiation time and temperature were studied by single factor experiments. Then, the central composite rotatable design and response surface methodology were employed to investigate the effect of three key parameters (ethanol concentration, solvent/material ratio, and ultrasound irradiation time) on the antioxidant activities of the flower extracts. The optimal extraction conditions were an ethanol concentration of 59.6%, solvent/material ratio of 50:1, ultrasound irradiation time of 7 min, and ultrasound irradiation temperature of 40 °C. Under these conditions, the optimized experimental value was 1103.38 ± 16.11 µmol Trolox/g dry weight (DW), which was in accordance with the predicted value (1105.49 µmol Trolox/g DW). Furthermore, the antioxidant activities of flower extracts obtained by UAE were compared with those produced by the traditional maceration and Soxhlet extraction methods, and UAE resulted in higher antioxidant activities after a shorter time at a lower temperature. The results obtained are helpful for the full utilization of Jatropha integerrima, and also indicate that ultrasound-assisted extraction is an efficient method for the extraction of natural antioxidants from plant materials.

  5. Optimization of the idler wavelength tunable cascaded optical parametric oscillator based on chirp-assisted aperiodically poled lithium niobate crystal

    NASA Astrophysics Data System (ADS)

    Tao, Chen; Rong, Shu; Ye, Ge; Zhuo, Chen

    2016-01-01

    We present the numerical results for the optimization of the pump-to-idler conversion efficiencies of nanosecond idler wavelength tunable cascaded optical parametric oscillators (OPO) in different wavelength tuning ranges, where the primary signals from the OPO process are recycled to enhance the pump-to-idler conversion efficiencies via the simultaneous difference frequency generation (DFG) process by monolithic aperiodically poled, magnesium oxide doped lithium niobate (APMgLN) crystals. The APMgLN crystals are designed with different chirp parameters for the DFG process to broaden their thermal acceptance bandwidths to different extents. The idler wavelength tuning of the cascaded OPO is realized by changing the temperature of the designed APMgLN crystal and the cascaded oscillation is achieved in a single pump pass singly resonant linear cavity. The pump-to-idler conversion efficiencies with respect to the pump pulse duration and ratio of OPO coefficient to DFG coefficient are calculated by numerically solving the coupled wave equations. The optimal working conditions of the tunable cascaded OPOs pumped by pulses with energies of 350 μJ and 700 μJ are compared to obtain the general rules of optimization. It is concluded that the optimization becomes the interplay between the ratio of OPO coefficient to DFG coefficient and the pump pulse duration when the idler wavelength tuning range and the pump pulse energy are fixed. Besides, higher pump pulse energy is beneficial for reaching higher optimal pump-to-idler conversion efficiency as long as the APMgLN crystal is optimized according to this pump condition. To the best of our knowledge, this is the first numerical analysis of idler wavelength tunable cascaded OPOs based on chirp-assisted APMgLN crystals. Project supported by the National Natural Science Foundation of China (Grant No. 61505236), the Innovation Program of Shanghai Institute of Technical Physics, China (Grant No. CX-2), and the Program of Shanghai

  6. GIS based location optimization for mobile produced water treatment facilities in shale gas operations

    NASA Astrophysics Data System (ADS)

    Kitwadkar, Amol Hanmant

    Over 60% of the nation's total energy is supplied by oil and natural gas together and this demand for energy will continue to grow in the future (Radler et al. 2012). The growing demand is pushing the exploration and exploitation of onshore oil and natural gas reservoirs. Hydraulic fracturing has proven to not only create jobs and achieve economic growth, but also has proven to exert a lot of stress on natural resources---such as water. As water is one of the most important factors in the world of hydraulic fracturing, proper fluids management during the development of a field of operation is perhaps the key element to address a lot of these issues. Almost 30% of the water used during hydraulic fracturing comes out of the well in the form of flowback water during the first month after the well is fractured (Bai et. al. 2012). Handling this large amount of water coming out of the newly fractured wells is one of the major issues as the volume of the water after this period drops off and remains constant for a long time (Bai et. al. 2012) and permanent facilities can be constructed to take care of the water over a longer period. This paper illustrates development of a GIS based tool for optimizing the location of a mobile produced water treatment facility while development is still occurring. A methodology was developed based on a multi criteria decision analysis (MCDA) to optimize the location of the mobile treatment facilities. The criteria for MCDA include well density, ease of access (from roads considering truck hauls) and piping minimization if piping is used and water volume produced. The area of study is 72 square miles east of Greeley, CO in the Wattenberg Field in northeastern Colorado that will be developed for oil and gas production starting in the year 2014. A quarterly analysis is done so that we can observe the effect of future development plans and current circumstances on the location as we move from quarter to quarter. This will help the operators to

  7. A microfluidic respiratory assist device with high gas permeance for artificial lung applications.

    PubMed

    Kniazeva, Tatiana; Hsiao, James C; Charest, Joseph L; Borenstein, Jeffrey T

    2011-04-01

    One of the principal challenges in artificial lung technology has been the ability to provide levels of oxygen and carbon dioxide exchange that rival those of the natural human lung, while mitigating the deleterious interaction between blood and the surface of the synthetic gas exchange membrane. This interaction is exacerbated by the large oxygenator surface area required to achieve sufficient levels of gas transfer. In an effort to address this challenge, microfluidics-based artificial lung technologies comprising stacked microchannel networks have been explored by several groups. Here we report the design, fabrication and initial testing of a parallel plate multilayered silicone-based microfluidic construct containing ultrathin gas exchange membranes, aimed at maximizing gas transfer efficiency while minimizing membrane-blood contact area. The device comprises a branched microvascular network that provides controlled wall shear stress and uniform blood flow, and is designed to minimize blood damage, thrombosis and inflammatory responses seen in current oxygenators. Initial testing indicates that flow distribution through the multilayer structure is uniform and that the thin membrane can withstand pressures equivalent to those expected during operation. Oxygen transfer using phosphate buffered saline as the carrier fluid has also been assessed, demonstrating a sharp increase in oxygen transfer as membrane thickness is reduced, consistent with the expected values of oxygen permeance for thin silicone membranes.

  8. Optimal transseptal puncture location for robot-assisted left atrial catheter ablation.

    PubMed

    Jayender, Jagadeesan; Patel, Rajni V; Michaud, Gregory F; Hatal, Nobuhiko

    2009-01-01

    The preferred method of treatment for Atrial Fibrillation (AF) is by catheter ablation wherein a catheter is guided into the left atrium through a transseptal puncture. However, the transseptal puncture constrains the catheter, thereby limiting its maneuverability and increasing the difficulty in reaching various locations in the left atrium. In this paper, we address the problem of choosing the optimal transseptal puncture location for performing cardiac ablation to obtain maximum maneuverability of the catheter. We have employed an optimization algorithm to maximize the Global Isotropy Index (GII) to evaluate the optimal transseptal puncture location. As part of this algorithm, a novel kinematic model for the catheter has been developed based on a continuum robot model. Preoperative MR/CT images of the heart are segmented using the open source image-guided therapy software, Slicer 3, to obtain models of the left atrium and septal wall. These models are input to the optimization algorithm to evaluate the optimal transseptal puncture location. Simulation results for the optimization algorithm are presented in this paper.

  9. Improving development planning in a natural gas storage field through simulation-optimization uncertainty analyses

    SciTech Connect

    Johnson, V M

    2001-01-22

    This is the second of two papers describing the application of simulation-optimization methods to a gas storage field development planning problem. The first paper began by giving a detailed description of the field and earlier efforts to model the effects of selected field development options on the field's productivity. It then outlined the basic steps required to apply a combination of artificial neural networks (ANNs) and the genetic algorithm (GA) to explore a much larger universe of field development planning options. Familiarity with the contents of the first paper is a prerequisite for understanding the material presented in this second paper. The optimized solutions to the planning problem presented in the first paper were based on a deterministic, ''best guess'' view of the field's reservoir properties. However, practical field development planning dictates that at least some of the uncertainties associated with these properties be taken into account. This second paper describes procedures and presents results showing how the ANN-GA approach to optimization can be extended to accommodate three sources of uncertainty pertinent to the field being studied: (1) Alternative hypotheses regarding the permeabilities in a key region of the field; (2) Uncertainty regarding the likely success of remediating existing wells; (3) Risks associated with siting new wells in relatively unknown regions of the field. The first two sources involve physical properties (permeabilities and skin factors, respectively) that are embedded in the simulation of the reservoir response and, therefore, require substantial changes to the knowledge base of simulations. The third source of uncertainty is examined simply by making changes to the objective functions driving the optimization. To streamline the presentation of results, only one of the two injection/withdrawal scenarios described in the first paper is included here, namely the 30-day peak service at the 2.5 Bcf baseload.

  10. Optimization of ultrasound-assisted extraction of polyphenols from spruce wood bark.

    PubMed

    Ghitescu, Roxana-Elena; Volf, Irina; Carausu, Constantin; Bühlmann, Ana-Maria; Gilca, Iulian Andrei; Popa, Valentin I

    2015-01-01

    Here we describe the ultrasound-assisted extraction of the phenolic compounds from spruce wood bark and present a straight-forward experimental planning method, allowing the optimisation of the process. The effect of ethanol concentration, temperature and extraction time were evaluated through a 3(2)·2 experimental planning. The efficiency of the extraction process was appreciated based on factorial ANOVA results. The maximum extraction yield of total polyphenols (13.232mg gallic acid equivalents (GAE)/g of spruce bark tested) was obtained using a process time of 60min, an extraction temperature of 54°C and a concentration of ethanol of 70% respectively. These results indicate that an important quantity of bioactive compounds can be extracted from spruce wood bark by ultrasound assisted extraction technology.

  11. [Simultaneous determination of six organophosphorous flame retardants in textiles by gas chromatography-tandem mass spectrometry combined with microwave assisted extraction].

    PubMed

    Wang, Chengyun; Li, Lixia; Xie, Tangtang; Zhang, Weiya; Liu, Caiming; Zhu, Naiqing

    2011-08-01

    An effective method was established for the simultaneous determination of six banned organophosphorous flame retardants in textiles by gas chromatography-tandem mass spectrometry (GC-MS/MS) combined with microwave assisted extraction (MAE). By investigating the extraction efficiency of 12 different extraction solvents for the target analytes, the optimal conditions were that the sample was extracted by microwave assisted extraction using acetone as the solvent at 76 degrees C for 30 min. Then the extract was analyzed by GC-MS/MS in multiple reaction monitoring (MRM) mode, and the concentration of each analyte was calibrated by external standard method. The linear ranges of tris-(1-aziridinyl) phosphine oxide (TEPA), tris-(2-chloroethyl) phosphate (TCEP), tris-(1,3-dichloropropyl) phosphate (TDCP), bis-(2,3-dibromopropyl) phosphate (DDBPP), tri-o-cresyl phosphate (TOCP) and tris-(2,3-dibromopropyl) phosphate (TRIS) were 9.17 - 366.80, 0.95 - 75.98, 1.04 - 83.20, 41.60 - 832.00, 3.80 - 75.90, and 40.48 - 809.60 microg/L, respectively, the correlation coefficients were not less than 0.997 5, while the limits of quantification (LOQ) (S/N = 10) were 3.0, 0.2, 0.3, 25.0, 2.5 and 29.0 microg/kg, respectively. The spiked recoveries varied from 82.62% to 96.88% with the relative standard deviations of 3.80% to 8.79%. The proposed method was successfully applied to the determination of organophosphorous flame retardants in eight commercial textiles. The experimental results demonstrated that the method developed is simple, rapid, sensitive and accurate, which could satisfy the demand of the analysis of banned organophosphorous flame retardants in textiles.

  12. Optimization of microwave-assisted extraction of flavonoids from young barley leaves

    NASA Astrophysics Data System (ADS)

    Gao, Tian; Zhang, Min; Fang, Zhongxiang; Zhong, Qifeng

    2017-01-01

    A central composite design combined with response surface methodology was utilized to optimise microwave-assisted extraction of flavonoids from young barley leaves. The results showed that using water as solvent, the optimum conditions of microwave-assisted extraction were extracted twice at 1.27 W g-1 microwave power and liquid-solid ratio 34.02 ml g-1 for 11.12 min. The maximum extraction yield of flavonoids (rutin equivalents) was 80.78±0.52%. Compared with conventional extraction method, the microwave-assisted extraction was more efficient as the extraction time was only 6.18% of conventional extraction, but the extraction yield of flavonoids was increased by 5.47%. The main flavonoid components from the young barley leaf extract were probably 33.36% of isoorientin-7-O-glueoside and 54.17% of isovitexin-7-O-glucoside, based on the HPLC-MS analysis. The barley leaf extract exhibited strong reducing power as well as the DPPH radical scavenging capacity.

  13. A Test of the Optimality Approach to Modelling Canopy gas Exchange by Natural Vegetation

    NASA Astrophysics Data System (ADS)

    Schymanski, S. J.; Sivapalan, M.; Roderick, M. L.; Beringer, J.; Hutley, L. B.

    2005-12-01

    Natural vegetation has co-evolved with its environment over a long period of time and natural selection has led to a species composition that is most suited for the given conditions. Part of this adaptation is the vegetation's water use strategy, which determines the amount and timing of water extraction from the soil. Knowing that water extraction by vegetation often accounts for over 90% of the annual water balance in some places, we need to understand its controls if we want to properly model the hydrologic cycle. Water extraction by roots is driven by transpiration from the canopy, which in turn is an inevitable consequence of CO2 uptake for photosynthesis. Photosynthesis provides plants with their main building material, carbohydrates, and with the energy necessary to thrive and prosper in their environment. Therefore we expect that natural vegetation would have evolved an optimal water use strategy to maximise its `net carbon profit' (the difference between carbon acquired by photosynthesis and carbon spent on maintenance of the organs involved in its uptake). Based on this hypothesis and on an ecophysiological gas exchange and photosynthesis model (Cowan and Farquhar 1977; von Caemmerer 2000), we model the optimal vegetation for a site in Howard Springs (N.T., Australia) and compare the modelled fluxes with measurements by Beringer, Hutley et al. (2003). The comparison gives insights into theoretical and real controls on transpiration and photosynthesis and tests the optimality approach to modelling gas exchange of natural vegetation with unknown properties. The main advantage of the optimality approach is that no assumptions about the particular vegetation on a site are needed, which makes it very powerful for predicting vegetation response to long-term climate- or land use change. Literature: Beringer, J., L. B. Hutley, et al. (2003). "Fire impacts on surface heat, moisture and carbon fluxes from a tropical savanna in northern Australia." International

  14. Reducing California's Greenhouse Gas Emissions through ProductLife-Cycle Optimization

    SciTech Connect

    Masanet, Eric; Price, Lynn; de la Rue du Can, Stephane; Worrell,Ernst

    2005-12-30

    Product life-cycle optimization addresses the reduction ofenvironmental burdens associated with the production, use, andend-of-life stages of a product s life cycle. In this paper, we offer anevaluation of the opportunities related to product life-cycleoptimization in California for two key products: personal computers (PCs)and concrete. For each product, we present the results of an explorativecase study to identify specific opportunities for greenhouse gas (GHG)emissions reductions at each stage of the product life cycle. We thenoffer a discussion of the practical policy options that may exist forrealizing the identified GHG reduction opportunities. The case studiesdemonstrate that there may be significant GHG mitigation options as wellas a number of policy options that could lead to life-cycle GHG emissionsreductions for PCs and concrete in California.

  15. Optimization in multidimensional gas chromatography applying quantitative analysis via a stable isotope dilution assay.

    PubMed

    Schmarr, Hans-Georg; Slabizki, Petra; Legrum, Charlotte

    2013-08-01

    Trace level analyses in complex matrices benefit from heart-cut multidimensional gas chromatographic (MDGC) separations and quantification via a stable isotope dilution assay. Minimization of the potential transfer of co-eluting matrix compounds from the first dimension ((1)D) separation into the second dimension separation requests narrow cut-windows. Knowledge about the nature of the isotope effect in the separation of labeled and unlabeled compounds allows choosing conditions resulting in at best a co-elution situation in the (1)D separation. Since the isotope effect strongly depends on the interactions of the analytes with the stationary phase, an appropriate separation column polarity is mandatory for an isotopic co-elution. With 3-alkyl-2-methoxypyrazines and an ionic liquid stationary phase as an example, optimization of the MDGC method is demonstrated and critical aspects of narrow cut-window definition are discussed.

  16. Rapid method for the determination of 16 organochlorine pesticides in sesame seeds by microwave-assisted extraction and analysis of extracts by gas chromatography-mass spectrometry.

    PubMed

    Papadakis, Emmanouil N; Vryzas, Zisis; Papadopoulou-Mourkidou, Euphemia

    2006-09-15

    A method for the multiresidue analysis of 16 organochlorine insecticides in sesame seeds has been developed. The method is based on the microwave-assisted extraction (MAE) of the sesame seeds by the use of a water-acetonitrile mixture followed by Florisil clean-up of the extracts and subsequent analysis by gas chromatography-mass spectrometry (GC/MS) in the selected ion monitoring (SIM) mode. MAE operational parameters (extraction solvent, temperature and time, extractant volume) were optimized with respect to extraction efficiency of the target compounds from sesame seeds with 46% oil content. Recoveries >80% with relative standard deviations (RSD) <12% were obtained for all compounds under the selected parameters. The Florisil clean-up step proved sufficient for the removal of co-extracted substances so that no adverse effect on the chromatographic system was observed. Limit of quantification (LOQ) values were in the range of 5-10 microg/kg. The proposed method was applied in the analysis of sesame seed samples imported to Greece.

  17. Rapid determination of polycyclic aromatic hydrocarbons in grilled meat using microwave-assisted extraction and dispersive liquid-liquid microextraction coupled to gas chromatography-mass spectrometry.

    PubMed

    Kamankesh, Marzieh; Mohammadi, Abdorreza; Hosseini, Hedayat; Modarres Tehrani, Zohreh

    2015-05-01

    A simple and rapid analytical tech nique for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in grilled meat was developed using microwave-assisted extraction and dispersive liquid-liquid microextraction (MAE-DLLME) followed by gas chromatography-mass spectrometry (GC-MS). The effective parameters in DLLME process were optimized. Good linear relationships were obtained for 16 PAHs in a range of 1-200 ng g(-1), with a correlation coefficient (R(2)) higher than 0.98. Limits of detection and limits of quantification were 0.15-0.3 ng g(-1) and 0.47-1 ng g(-1), respectively. The relative standard deviations (RSD%) for seven analyses were less than 9%. The recoveries of those compounds in grilled meat were obtained from 85% to 104%. Low consumption of the solvent, high recovery, short extraction time, no matrix interference and good merit figures compared to other methods are advantages of the proposed method. The performance of the present method was evaluated for the determination of PAHs in various types of real grilled meat samples, and satisfactory results were obtained.

  18. Rapid screening of haloacetamides in water using salt-assisted liquid-liquid extraction coupled injection-port silylation gas chromatography-mass spectrometry.

    PubMed

    Chen, Tzu-Ling; Tzing, Shin-Hwa; Ding, Wang-Hsien

    2015-11-27

    The rapid screening of trace amounts of the nitrogenous disinfection by-products, haloacetamides (HAcAms), in drinking and swimming pool water was performed by a simple and reliable procedure based on salt-assisted liquid-liquid extraction (SALLE) combined with injection-port silylation gas chromatography-mass spectrometry (IPS-GC-MS) method. The optimal SALLE conditions involved the injection of 4-mL of ethyl acetate into a 10-mL water sample (pH 7) containing 3-g of sodium sulfate. After vortex extraction for 1min and centrifugation, 10μL of the extract (mixed with 1μL of MTBSTFA) was directly determined by IPS-GC-MS. The limits of quantitation (LOQs) were determined to be 0.03-0.3μg/L. Precision, as indicated by relative standard deviations (RSDs), was less than 10% for both intra- and inter-day analysis. Accuracy, expressed as the mean extraction recovery, was between 76% and 94%. The SALLE plus IPS-GC-MS was successfully applied to quantitatively determine HAcAms from drinking and swimming pool water samples, and the total concentrations of the compounds ranged from 0.43 to 4.03μg/L.

  19. Rapid analysis of pyrethroid insecticides in aquaculture seawater samples via membrane-assisted solvent extraction coupled with gas chromatography-electron capture detection.

    PubMed

    Shi, X Z; Song, S Q; Sun, A L; Liu, J H; Li, D X; Chen, J

    2012-01-21

    A simple, efficient, and environmentally friendly membrane-assisted solvent extraction (MASE) method for the extraction and preconcentration of six pyrethroid insecticides from aquaculture seawater samples followed by gas chromatography-electron capture detection (GC-ECD) was successfully proposed. The operating conditions for MASE, such as the extraction solvent, solvent volume, NaCl concentration, stirring rate, extraction time, and temperature, were optimized. Compared to conventional Florisil-solid phase extraction (SPE), higher extraction recoveries (85.9% to 105.9%) of three spiked levels of the six pyrethroid pesticides in aquaculture seawater were obtained using MASE, and the RSD values were lower than 7.9%. The limits of detection (LOD, signal-to-noise ratio (S/N)=3) and quantification (LOQ, S/N = 10) were in the range of 0.037-0.166 and 0.12-0.55 μg L(-1), respectively. The results demonstrate the excellent applicability of the MASE method in analyzing the six pyrethroid pesticides in aqueous samples. The proposed method exhibited a high potential for routine monitoring analysis of pyrethroid insecticides in seawater samples.

  20. Determination of volatile components of saffron by optimised ultrasound-assisted extraction in tandem with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

    PubMed

    Sereshti, Hassan; Heidari, Reza; Samadi, Soheila

    2014-01-15

    In the present research, a combined extraction method of ultrasound-assisted extraction (UAE) in conjunction with dispersive liquid-liquid microextraction (DLLME) was applied to isolation and enrichment of saffron volatiles. The extracted components of the saffron were separated and determined by gas chromatography-mass spectrometry (GC-MS) technique. The mixture of methanol/acetonitrile was chosen for the extraction of the compounds and chloroform was used at the preconcentration stage. The important parameters, such as composition of extraction solvent, volume of preconcentration solvent, ultrasonic applying time, and salt concentration were optimised by using a half-fraction factorial central composite design (CCD). Under the optimal conditions, the linear dynamic ranges (LDRs) were 10-10,000mgL(-)(1). The determination coefficients (R(2)) were from 0.9990 to 0.9997. The limits of detection (LODs) and limits of quantification (LOQs) for the extracted compounds were 6-123mgL(-)(1) and 20-406mgL(-)(1), respectively. The relative standard deviations (RSDs) were 2.48-9.82% (n=3). The enhancement factors (EFs) were 3.6-41.3.

  1. Structural and composition investigations at delayered locations of low k integrated circuit device by gas-assisted focused ion beam

    SciTech Connect

    Wang, Dandan Kee Tan, Pik; Yamin Huang, Maggie; Lam, Jeffrey; Mai, Zhihong

    2014-05-15

    The authors report a new delayering technique – gas-assisted focused ion beam (FIB) method and its effects on the top layer materials of integrated circuit (IC) device. It demonstrates a highly efficient failure analysis with investigations on the precise location. After removing the dielectric layers under the bombardment of an ion beam, the chemical composition of the top layer was altered with the reduced oxygen content. Further energy-dispersive x-ray spectroscopy and Fourier transform infrared analysis revealed that the oxygen reduction lead to appreciable silicon suboxide formation. Our findings with structural and composition alteration of dielectric layer after FIB delayering open up a new insight avenue for the failure analysis in IC devices.

  2. Conformation of Macromolecules in the Gas Phase: Use of Matrix-Assisted Laser Desorption Methods in Ion Chromatography

    NASA Astrophysics Data System (ADS)

    von Helden, Gert; Wyttenbach, Thomas; Bowers, Michael T.

    1995-03-01

    Conformational data for macromolecules in the gas phase have been obtained by the coupling of a matrix-assisted laser desorption ion source to an ion chromatograph. A series of polyethylene glycol (PEG) polymers "cationized" (converted to a cation) by sodium ions (Na^+PEG9 to Na^+PEG19) and a protonated neurotransmitter protein, bradykinin, were studied. Mobilities of Na^+PEG9 to Na^+PEG19 are reported. Detailed modeling of Na^+PEG9 with molecular mechanics methods indicates that the lowest energy structure has the Na^+ ion "solvated" by the polymer chain with seven oxygen atoms as nearest neighbors. The agreement between the model and experiment is within 1 percent for Na^+PEG9, Na^+PEG13, and Na^+PEG17, giving strong support to both the method and the deduced structures. Similar agreement was obtained in initial studies that modeled experimental data for arginine-protonated bradykinin.

  3. Optimized Design and Use of Induced Complex Fractures in Horizontal Wellbores of Tight Gas Reservoirs

    NASA Astrophysics Data System (ADS)

    Zeng, F. H.; Guo, J. C.

    2016-04-01

    Multistage hydraulic fracturing is being increasing use in the establishment of horizontal wells in tight gas reservoirs. Connecting hydraulic fractures to natural and stress-induced fractures can further improve well productivity. This paper investigates the fracture treatment design issues involved in the establishment of horizontal wellbores, including the effects of geologic heterogeneity, perforation parameters, fracturing patterns, and construction parameters on stress anisotropy during hydraulic fracturing and on natural fractures during hydraulic fracture propagation. The extent of stress reversal and reorientation was calculated for fractures induced by the creation of one or more propped fractures. The effects of stress on alternate and sequential fracturing horizontal well and on the reservoir's mechanical properties, including the spatial extent of stress reorientation caused by the opening of fractures, were assessed and quantified. Alternate sequencing of transverse fractures was found to be an effective means of enhancing natural fracture stimulation by allowing fractures to undergo less stress contrast during propagation. The goal of this paper was to present a new approach to design that optimizes fracturing in a horizontal wellbore from the perspectives of both rock mechanics and fluid production. The new design is a modified version of alternate fracturing, where the fracture-initiation sequence was controlled by perforation parameters with a staggered pattern within a horizontal wellbore. Results demonstrated that the modified alternate fracturing performed better than original sequence fracturing and that this was because it increased the contact area and promoted more gas production in completed wells.

  4. Strategies and methodologies to develop techniques for computer-assisted analysis of gas phase formation during altitude decompression

    NASA Technical Reports Server (NTRS)

    Powell, Michael R.; Hall, W. A.

    1993-01-01

    It would be of operational significance if one possessed a device that would indicate the presence of gas phase formation in the body during hypobaric decompression. Automated analysis of Doppler gas bubble signals has been attempted for 2 decades but with generally unfavorable results, except with surgically implanted transducers. Recently, efforts have intensified with the introduction of low-cost computer programs. Current NASA work is directed towards the development of a computer-assisted method specifically targeted to EVA, and we are most interested in Spencer Grade 4. We note that Spencer Doppler Grades 1 to 3 have increased in the FFT sonogram and spectrogram in the amplitude domain, and the frequency domain is sometimes increased over that created by the normal blood flow envelope. The amplitude perturbations are of very short duration, in both systole and diastole and at random temporal positions. Grade 4 is characteristic in the amplitude domain but with modest increases in the FFT sonogram and spectral frequency power from 2K to 4K over all of the cardiac cycle. Heart valve motion appears to characteristic display signals: (1) the demodulated Doppler signal amplitude is considerably above the Doppler-shifted blow flow signal (even Grade 4); and (2) demodulated Doppler frequency shifts are considerably greater (often several kHz) than the upper edge of the blood flow envelope. Knowledge of these facts will aid in the construction of a real-time, computer-assisted discriminator to eliminate cardiac motion artifacts. There could also exist perturbations in the following: (1) modifications of the pattern of blood flow in accordance with Poiseuille's Law, (2) flow changes with a change in the Reynolds number, (3) an increase in the pulsatility index, and/or (4) diminished diastolic flow or 'runoff.' Doppler ultrasound devices have been constructed with a three-transducer array and a pulsed frequency generator.

  5. Redeposition in plasma-assisted atomic layer deposition: Silicon nitride film quality ruled by the gas residence time

    SciTech Connect

    Knoops, Harm C. M. E-mail: w.m.m.kessels@tue.nl; Peuter, K. de; Kessels, W. M. M. E-mail: w.m.m.kessels@tue.nl

    2015-07-06

    The requirements on the material properties and growth control of silicon nitride (SiN{sub x}) spacer films in transistors are becoming ever more stringent as scaling of transistor structures continues. One method to deposit high-quality films with excellent control is atomic layer deposition (ALD). However, depositing SiN{sub x} by ALD has turned out to be very challenging. In this work, it is shown that the plasma gas residence time τ is a key parameter for the deposition of SiN{sub x} by plasma-assisted ALD and that this parameter can be linked to a so-called “redeposition effect”. This previously ignored effect, which takes place during the plasma step, is the dissociation of reaction products in the plasma and the subsequent redeposition of reaction-product fragments on the surface. For SiN{sub x} ALD using SiH{sub 2}(NH{sup t}Bu){sub 2} as precursor and N{sub 2} plasma as reactant, the gas residence time τ was found to determine both SiN{sub x} film quality and the resulting growth per cycle. It is shown that redeposition can be minimized by using a short residence time resulting in high-quality films with a high wet-etch resistance (i.e., a wet-etch rate of 0.5 nm/min in buffered HF solution). Due to the fundamental nature of the redeposition effect, it is expected to play a role in many more plasma-assisted ALD processes.

  6. Determination of ultraviolet filters in water samples by vortex-assisted dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

    PubMed

    Zhang, Yufeng; Lee, Hian Kee

    2012-08-03

    For the first time, a simple solvent microextraction method termed vortex-assisted liquid-liquid microextraction (VADLLME) coupled with gas chromatography-mass spectrometry (GC-MS) has been developed and used for the analysis of six benzophenone ultraviolet (UV) filters (i.e. benzhydrol, 2,4-dihydroxybenzophenone, benzophenone, 2-hydroxy-4-methoxybenzophenone, ethylhexyl salicylate and homosalate) in water samples. The most favorable extraction variables in the VADLLME process were determined. In the extraction procedure, 40 μL of tetrachloroethene as extraction solvent were directly injected into a 15-mL centrifuge tube containing 10 mL of aqueous sample, adjusted to pH 4 for VADLLME. After VADLLME, the extract was evaporated under a gentle nitrogen gas stream and then reconstituted with N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA), thus allowing the target analytes to be converted into their trimethylsilyl derivatives to optimize the GC-MS analysis. No centrifugation and disperser solvent were required in this microextraction procedure. Significantly, short extraction time and high extraction efficiency were achieved. This method opens up a potentially new horizon for on-site dispersive liquid-liquid microextraction. Under the optimum conditions, the proposed method provided good enrichment factors up to 310, with relative standard deviations ranging from 6.1 to 12.9%. The limits of quantification were in the range of 20-100 ng/L, depending on the analytes. The linearities were between 0.05 and 10 μg/L and 0.1 and 10 μg/L for different UV filters. Finally, the proposed method was successfully applied to the determination of UV filters from spiked genuine water samples and acceptable recoveries over the range of 71.0-120.0% were obtained.

  7. Derivatization of small biomolecules for optimized matrix-assisted laser desorption/ionization mass spectrometry.

    PubMed

    Tholey, Andreas; Wittmann, Christoph; Kang, Min-Jung; Bungert, Ditte; Hollemeyer, Klaus; Heinzle, Elmar

    2002-09-01

    Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) is a powerful tool for the measurement of low molecular mass compounds of biological interest. The limitations for this method are the volatility of many analytes, possible interference with matrix signals or bad ionization or desorption behavior of the compounds. We investigated the application of well-known and straightforward one-pot derivatization procedures to circumvent these problems. The derivatizations tested allow the measurement and the labeling of alcohols, aldehydes and ketones, carboxylic acids, alpha-ketocarboxylic acids and amines.

  8. Optimization of In-Situ Shot-Peening-Assisted Cold Spraying Parameters for Full Corrosion Protection of Mg Alloy by Fully Dense Al-Based Alloy Coating

    NASA Astrophysics Data System (ADS)

    Wei, Ying-Kang; Luo, Xiao-Tao; Li, Cheng-Xin; Li, Chang-Jiu

    2017-01-01

    Magnesium-based alloys have excellent physical and mechanical properties for a lot of applications. However, due to high chemical reactivity, magnesium and its alloys are highly susceptible to corrosion. In this study, Al6061 coating was deposited on AZ31B magnesium by cold spray with a commercial Al6061 powder blended with large-sized stainless steel particles (in-situ shot-peening particles) using nitrogen gas. Microstructure and corrosion behavior of the sprayed coating was investigated as a function of shot-peening particle content in the feedstock. It is found that by introducing the in-situ tamping effect using shot-peening (SP) particles, the plastic deformation of deposited particles is significantly enhanced, thereby resulting in a fully dense Al6061 coating. SEM observations reveal that no SP particle is deposited into Al6061 coating at the optimization spraying parameters. Porosity of the coating significantly decreases from 10.7 to 0.4% as the SP particle content increases from 20 to 60 vol.%. The electrochemical corrosion experiments reveal that this novel in-situ SP-assisted cold spraying is effective to deposit fully dense Al6061 coating through which aqueous solution is not permeable and thus can provide exceptional protection of the magnesium-based materials from corrosion.

  9. RSM and ANN modeling-based optimization approach for the development of ultrasound-assisted liposome encapsulation of piceid.

    PubMed

    Huang, Shang-Ming; Kuo, Chia-Hung; Chen, Chun-An; Liu, Yung-Chuan; Shieh, Chwen-Jen

    2017-05-01

    Piceid, a naturally occurring derivative of resveratrol found in many plants, has recently been considered as a potential nutraceutical. However, its poorly water-soluble property could cause a coupled problem of biological activities concerning drug dispersion and absorption in human body, which is still unsolved now. Liposome, a well-known aqueous carrier for water-insoluble ingredients, is commonly applied in drug delivery systems. In this study, a feasible approach for solving the problem is that the targeted piceid was encapsulated into a liposomal formula as aqueous substrate to overcome its poor water-solubility. The encapsulation process was assisted by ultrasound, with investigation of lipid content, ultrasound power and ultrasound time, for controlling encapsulation efficiency (E.E%), absolute loading (A.L%) and particle size (PS). Moreover, both RSM and ANN methodologies were further applied to optimize the ultrasound-assisted encapsulation process. The data indicated that the most important effects on the encapsulation performance were found to be of lipid content followed by ultrasound time and ultrasound power. The maximum E.E% (75.82%) and A.L% (2.37%) were exhibited by ultrasound assistance with the parameters of 160mg lipid content, ultrasound time for 24min and ultrasound power of 90W. By methodological aspects of processing, the predicted E.E% and A.L% were respectively in good agreement with the experimental results for both RSM and ANN. Moreover, RMSE, R(2) and AAD statistics were further used to compare the prediction abilities of RSM and ANN based on the validation data set. The results indicated that the prediction accuracy of ANN was better than that of RSM. In conclusion, ultrasound-assisted liposome encapsulation can be an efficient strategy for producing well-soluble/dispersed piceid, which could be further applied to promote human health by increased efficiency of biological absorption, and the process of ultrasound-mediated liposome

  10. A comparative study of expected improvement-assisted global optimization with different surrogates

    NASA Astrophysics Data System (ADS)

    Wang, Hu; Ye, Fan; Li, Enying; Li, Guangyao

    2016-08-01

    Efficient global optimization (EGO) uses the surrogate uncertainty estimator called expected improvement (EI) to guide the selection of the next sampling candidates. Theoretically, any modelling methods can be integrated with the EI criterion. To improve the convergence ratio, a multi-surrogate efficient global optimization (MSEGO) was suggested. In practice, the EI-based optimization methods with different surrogates show widely divergent characteristics. Therefore, it is important to choose the most suitable algorithm for a certain problem. For this purpose, four single-surrogate efficient global optimizations (SSEGOs) and an MSEGO involving four surrogates are investigated. According to numerical tests, both the SSEGOs and the MSEGO are feasible for weak nonlinear problems. However, they are not robust for strong nonlinear problems, especially for multimodal and high-dimensional problems. Moreover, to investigate the feasibility of EGO in practice, a material identification benchmark is designed to demonstrate the performance of EGO methods. According to the tests in this study, the kriging EGO is generally the most robust method.

  11. Optimization of Ultrasound-Assisted Extraction of Natural Antioxidants from Sugar Apple (Annona squamosa L.) Peel Using Response Surface Methodology.

    PubMed

    Deng, Gui-Fang; Xu, Dong-Ping; Li, Sha; Li, Hua-Bin

    2015-11-17

    Sugar apple (Annona squamosa L.) is a popular tropical fruit and its peel is a municipal waste. An ultrasound-assisted extraction method was developed for the recovery of natural antioxidants from sugar apple peel. Central composite design was used to optimize solvent concentration (13.2%-46.8%), ultrasonic time (33.2-66.8 min), and temperature (43.2-76.8 °C) for the recovery of natural antioxidants from sugar apple peel. The second-order polynomial models demonstrated a good fit of the quadratic models with the experimental results in respect to total phenolic content (TPC, R²=0.9524, p<0.0001), FRAP (R²=0.9743, p<0.0001), and TEAC (R²=0.9610, p<0.0001) values. The optimal extraction conditions were 20:1 (mL/g) of solvent-to-solid ratio, 32.68% acetone, and 67.23 °C for 42.54 min under ultrasonic irradiation. Under these conditions, the maximal yield of total phenolic content was 26.81 (mg GA/g FW). The experimental results obtained under optimal conditions agreed well with the predicted results. The application of ultrasound markedly decreased extraction time and improved the extraction efficiency, compared with the conventional methods.

  12. Optimization of preparation of activated carbon from cotton stalk by microwave assisted phosphoric acid-chemical activation.

    PubMed

    Deng, Hui; Zhang, Genlin; Xu, Xiaolin; Tao, Guanghui; Dai, Jiulei

    2010-10-15

    The preparation of activated carbon (AC) from cotton stalk was investigated in this paper. Orthogonal array experimental design method was used to optimize the preparation of AC using microwave assisted phosphoric acid. Optimized parameters were radiation power of 400 W, radiation time of 8 min, concentration of phosphoric acid of 50% by volume and impregnation time of 20 h, respectively. The surface characteristics of the AC prepared under optimized condition were examined by pore structure analysis, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Pore structure analysis shows that mecropores constitute more of the porosity of the prepared AC. Compared to cotton stalk, different functionalities and morphology on the carbon surfaces were formed in the prepared process. The adsorption capacity of the AC was also investigated by removing methylene blue (MB) in aqueous solution. The equilibrium data of the adsorption was well fitted to the Langmuir isotherm. The maximum adsorption capacity of MB on the prepared AC is 245.70 mg/g. The adsorption process follows the pseudo-second-order kinetic model.

  13. Optimization of Ultrasonic-Assisted Extraction and Radical-Scavenging Capacity of Phenols and Flavonoids from Clerodendrum cyrtophyllum Turcz Leaves

    PubMed Central

    Zhou, Jing; Zheng, Xiaoxue; Yang, Qi; Liang, Zhenyi; Li, Donghai; Yang, Xiaobo; Xu, Jing

    2013-01-01

    Ultrasonic-assisted extraction (UAE) was developed to extract phenolic and flavonoid antioxidants from Clerodendrum cyrtophyllum Turcz leaves. The optimal experimental parameters for antioxidant extraction from C. cyrtophyllum leaves were measured using single-factor experimentation combined with response surface methodology (RSM). Total phenolic content (TPC) and total flavonoid content (TFC) assays were used to quantify antioxidant compounds. Next, antioxidant radical scavenging capacity was measured using 2,2′-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′ -azino-bis(3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) radicals. Optimized extraction conditions for UAE from C. cyrtophyllum leaves were as follows: 60.9% ethanol, 85.4 min, and 63.3°C for maximal TPC extraction (16.8±0.2 mg GAE/g DW); 67.7% ethanol, 82.9 min, and 63.0°C for maximal TFC extraction (49.3±0.4 mg RT/g DW); 48.8% ethanol, 85.1 min, and 63.9°C for maximal DPPH radical-scavenging capacity (86.8±0.2%); and 50.6% ethanol, 81.3 min, and 63.4°C for maximal ABTS radical-scavenging capacity (92.9±0.5%). Ethanol concentration was the most important factor in the extraction process. Our work offers optimal extraction conditions for C. cyrtophyllum as a potential source of natural antioxidants. PMID:23874607

  14. Optimization of ultrasonic-assisted extraction of antioxidant polysaccharides from the stem of Trapa quadrispinosa using response surface methodology.

    PubMed

    Raza, Aun; Li, Feng; Xu, Xiuquan; Tang, Jian

    2017-01-01

    Response surface methodology (RSM) was used to optimize experimental conditions for ultrasonic-assisted extraction (UAE) of antioxidant crude polysaccharides (CPS) from Trapa quadrispinosa stems. Antioxidant capacity of polysaccharides was determined by Ferric-Reducing Antioxidant Capacity (FRAC) assay with the method of 1, 10-phenanthroline. The maximum yield of polysaccharides (2.78±0.16%) was obtained under optimal extraction conditions of extraction time, 41min; ratio of water to material, 31.5mL/g; and extraction temperature, 58°C. The maximum antioxidant capacity (19.02±0.24μmol Fe(2+)/g) was obtained under the optimal extraction conditions of extraction time, 38min; ratio of water to material, 32mL/g; and extraction temperature, 56°C. These two values were agreed well with predicted yield (2.75%) and antioxidant capacity (18.77μmol Fe(2+)/g). Antioxidant activities of CPS were investigated by various assays. The results showed that CPSUAE obtained by UAE showed higher 1,1-Diphenyl-2-picrylhydrazxyl (DPPH), 2,2-azinobis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging activities and stronger reducing power, total antioxidant capacity compared with CPSHWE obtained by hot water extraction (HWE).The results indicated that UAE is an advisable method for extraction of antioxidant polysaccharides from the stem of T. quadrispinosa and polysaccharides could be explored as potential antioxidant to use in medicine or functional food.

  15. Scalability of surrogate-assisted multi-objective optimization of antenna structures exploiting variable-fidelity electromagnetic simulation models

    NASA Astrophysics Data System (ADS)

    Koziel, Slawomir; Bekasiewicz, Adrian

    2016-10-01

    Multi-objective optimization of antenna structures is a challenging task owing to the high computational cost of evaluating the design objectives as well as the large number of adjustable parameters. Design speed-up can be achieved by means of surrogate-based optimization techniques. In particular, a combination of variable-fidelity electromagnetic (EM) simulations, design space reduction techniques, response surface approximation models and design refinement methods permits identification of the Pareto-optimal set of designs within a reasonable timeframe. Here, a study concerning the scalability of surrogate-assisted multi-objective antenna design is carried out based on a set of benchmark problems, with the dimensionality of the design space ranging from six to 24 and a CPU cost of the EM antenna model from 10 to 20 min per simulation. Numerical results indicate that the computational overhead of the design process increases more or less quadratically with the number of adjustable geometric parameters of the antenna structure at hand, which is a promising result from the point of view of handling even more complex problems.

  16. Analyses of polychlorinated biphenyls in waters and wastewaters using vortex-assisted liquid-liquid microextraction and gas chromatography-mass spectrometry.

    PubMed

    Ozcan, Senar

    2011-03-01

    A method was developed for viable and rapid determination of seven polychlorinated biphenyls (PCBs) in water samples with vortex-assisted liquid-liquid microextraction (VALLME) using gas chromatography-mass spectrometry (GC-MS). At first, the most suitable extraction solvent and extraction solvent volume were determined. Later, the parameters affecting the extraction efficiency such as vortex extraction time, rotational speed of the vortex, and ionic strength of the sample were optimized by using a 2(3) factorial experimental design. The optimized extraction conditions for 5 mL water sample were as follows: extractant solvent 200 μL of chloroform; vortex extraction time of 2 min at 3000 rpm; centrifugation 5 min at 4000 rpm, and no ionic strength. Under the optimum condition, limits of detection (LOD) ranged from 0.36 to 0.73 ng/L. Mean recoveries of PCBs from fortified water samples are 96% for three different fortification levels and RSDs of the recoveries are below 5%. The developed procedure was successfully applied to the determination of PCBs in real water and wastewater samples such as tap, well, surface, bottled waters, and municipal, treated municipal, and industrial wastewaters. The performance of the proposed method was compared with traditional liquid-liquid extraction (LLE) of real water samples and the results show that efficiency of proposed method is comparable to the LLE. However, the proposed method offers several advantages, i.e. reducing sample requirement for measurement of target compounds, less solvent consumption, and reducing the costs associated with solvent purchase and waste disposal. It is also viable, rapid, and easy to use for the analyses of PCBs in water samples by using GC-MS.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  18. Fire assisted pastoralism vs. sustainable forestry--the implications of missing markets for carbon in determining optimal land use in the wet-dry tropics of Australia.

    PubMed

    Ockwell, David; Lovett, Jon C

    2005-04-01

    Using Cape York Peninsula, Queensland, Australia as a case study, this paper combines field sampling of woody vegetation with cost-benefit analysis to compare the social optimality of fire-assisted pastoralism with sustainable forestry. Carbon sequestration is estimated to be significantly higher in the absence of fire. Integration of carbon sequestration benefits for mitigating future costs of climate change into cost-benefit analysis demonstrates that sustainable forestry is a more socially optimal land use than fire-assisted pastoralism. Missing markets for carbon, however, imply that fire-assisted pastoralism will continue to be pursued in the absence of policy intervention. Creation of markets for carbon represents a policy solution that has the potential to drive land use away from fire-assisted pastoralism towards sustainable forestry and environmental conservation.

  19. CO2 Binding Organic Liquids Gas Capture with Polarity Swing Assisted Regeneration

    SciTech Connect

    Heldebrant, David

    2014-05-31

    This report outlines the comprehensive bench-scale testing of the CO2-binding organic liquids (CO2BOLs) solvent platform and its unique Polarity Swing Assisted Regeneration (PSAR). This study outlines all efforts on a candidate CO2BOL solvent molecule, including solvent synthesis, material characterization, preliminary toxicology studies, and measurement of all physical, thermodynamic and kinetic data, including bench-scale testing. Equilibrium and kinetic models and analysis were made using Aspen Plus™. Preliminary process configurations, a technoeconomic assessment and solvent performance projections for separating CO2 from a subcritical coal-fired power plant are compared to the U.S. Department of Energy's Case 10 monoethanolamine baseline.

  20. Photon-Assisted Tunneling in a Biased Strongly Correlated Bose Gas

    SciTech Connect

    Ma Ruichao; Tai, M. Eric; Preiss, Philipp M.; Bakr, Waseem S.; Simon, Jonathan; Greiner, Markus

    2011-08-26

    We study the impact of coherently generated lattice photons on an atomic Mott insulator subjected to a uniform force. Analogous to an array of tunnel-coupled and biased quantum dots, we observe sharp, interaction-shifted photon-assisted tunneling resonances corresponding to tunneling one and two lattice sites either with or against the force and resolve multiorbital shifts of these resonances. By driving a Landau-Zener sweep across such a resonance, we realize a quantum phase transition between a paramagnet and an antiferromagnet and observe quench dynamics when the system is tuned to the critical point. Direct extensions will produce gauge fields and site-resolved spin flips, for topological physics and quantum computing.

  1. Optimization of Ultrasound Assisted Extraction of Functional Ingredients from Stevia Rebaudiana Bertoni Leaves

    NASA Astrophysics Data System (ADS)

    Šic Žlabur, Jana; Voća, Sandra; Dobričević, Nadica; Brnčić, Mladen; Dujmić, Filip; Rimac Brnčić, Suzana

    2015-04-01

    The aim of the present study was to reveal an effective extraction procedure for maximization of the yield of steviol glycosides and total phenolic compounds as well as antioxidant activity in stevia extracts. Ultrasound assisted extraction was compared with conventional solvent extraction. The examined solvents were water (100°C/24 h) and 70% ethanol (at 70°C for 30 min). Qualitative and quantitative analyses of steviol glycosides in the extracts obtained were performed using high performance liquid chromatography. Total phenolic compounds, flavonoids, and radical scavenging capacity by 2, 2-azino-di-3-ethylbenzothialozine- sulphonic acid) assay were also determined. The highest content of steviol glycosides, total phenolic compounds, and flavonoids in stevia extracts were obtained when ultrasound assisted extraction was used. The antioxidant activity of the extracts was correlated with the total amount of phenolic compounds. The results indicated that the examined sonication parameters represented as the probe diameter (7 and 22 mm) and treatment time (2, 4, 6, 8, and 10 min) significantly contributed to the yield of steviol glycosides, total phenolic compounds, and flavonoids. The optimum conditions for the maximum yield of steviol glycosides, total phenolic compounds, and flavonoids were as follows: extraction time 10 min, probe diameter 22 mm, and temperature 81.2°C.

  2. Read buffer optimizations to support compiler-assisted multiple instruction retry

    NASA Technical Reports Server (NTRS)

    Alewine, N. J.; Fuchs, W. K.; Hwu, W. M.

    1993-01-01

    Multiple instruction retry is a recovery mechanism for transient processor faults. We previously developed a compiler-assisted approach to multiple instruction ferry in which a read buffer of size 2N (where N represents the maximum instruction rollback distance) was used to resolve some data hazards while the compiler resolved the remaining hazards. The compiler-assisted scheme was shown to reduce the performance overhead and/or hardware complexity normally associated with hardware-only retry schemes. This paper examines the size and design of the read buffer. We establish a practical lower bound and average size requirement for the read buffer by modifying the scheme to save only the data required for rollback. The study measures the effect on the performance of a DECstation 3100 running ten application programs using six read buffer configurations with varying read buffer sizes. Two alternative configurations are shown to be the most efficient and differed depending on whether split-cycle-saves are assumed. Up to a 55 percent read buffer size reduction is achievable with an average reduction of 39 percent given the most efficient read buffer configuration and a variety of applications.

  3. Plasma-assisted cleanup of flue gas. Technical report, March 1, 1994--May 31, 1994

    SciTech Connect

    Dhali, S.K.

    1994-09-01

    The experimental data reported in the last quarterly report were verified by repeating the experiments. It was consistently determined that there is nearly 80% removal of SO{sub 2} in a flue gas containing 775 ppm (parts per million) of SO{sub 2} and 99% for SO{sub 2} in concentrations of 300 ppm. The reduction increases with increasing electrode length. Also during this period, the removal studies for higher concentrations of SO{sub 2} (1400 ppm) were studied. For this a variable frequency power supply was used. It was found that the removal efficiency increased with frequency (in the range 60-400 Hz).

  4. Highly selective NH3 gas sensor based on Au loaded ZnO nanostructures prepared using microwave-assisted method.

    PubMed

    Shingange, K; Tshabalala, Z P; Ntwaeaborwa, O M; Motaung, D E; Mhlongo, G H

    2016-10-01

    ZnO nanorods synthesized using microwave-assisted approach were functionalized with gold (Au) nanoparticles. The Au coverage on the surface of the functionalized ZnO was controlled by adjusting the concentration of the Au precursor. According to X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) results, it was confirmed that Au form nanoparticles loaded on the surface of ZnO. The small Au loading level of 0.5wt% showed the highest response of 1600-100ppm of NH3 gas at room temperature (RT) whereas further increase of Au loading level resulted in poor detection of NH3. All Au loaded ZnO (Au/ZnO) based sensors exhibited very short recovery and response times compared to unloaded ZnO sensing materials. The responses of ZnO and Au/ZnO based sensors (0.5-2.5wt%) to other flammable gases, including H2, CO and CH4, were considerably less, demonstrating that Au/ZnO based sensors were highly selective to NH3 gas at room temperature. Spill over mechanism which is the main reason for the observed enhanced NH3 response with 0.5 Au loading level is explained in detail.

  5. Effect of Gas Tungsten Arc Welding Parameters on Hydrogen-Assisted Cracking of Type 321 Stainless Steel

    NASA Astrophysics Data System (ADS)

    Rozenak, Paul; Unigovski, Yaakov; Shneck, Roni

    2016-05-01

    The susceptibility of AISI type 321 stainless steel welded by the gas tungsten arc welding (GTAW) process to hydrogen-assisted cracking (HAC) was studied in a tensile test combined with in situ cathodic charging. Specimen charging causes a decrease in ductility of both the as-received and welded specimens. The mechanical properties of welds depend on welding parameters. For example, the ultimate tensile strength and ductility increase with growing shielding gas (argon) rate. More severe decrease in the ductility was obtained after post-weld heat treatment (PWHT). In welded steels, in addition to discontinuous grain boundary carbides (M23C6) and dense distribution of metal carbides MC ((Ti, Nb)C) precipitated in the matrix, the appearance of delta-ferrite phase was observed. The fracture of sensitized specimens was predominantly intergranular, whereas the as-welded specimens exhibited mainly transgranular regions. High-dislocation density regions and stacking faults were found in delta-ferrite formed after welding. Besides, thin stacking fault plates and epsilon-martensite were found in the austenitic matrix after the cathodic charging.

  6. UV-assisted room temperature gas sensing of GaN-core/ZnO-shell nanowires

    NASA Astrophysics Data System (ADS)

    Park, Sunghoon; Ko, Hyunsung; Kim, Soohyun; Lee, Chongmu

    2014-11-01

    GaN is highly sensitive to low concentrations of H2 in ambient air and is almost insensitive to most other common gases. However, enhancing the sensing performance and the detection limit of GaN is a challenge. This study examined the H2-gas-sensing properties of GaN nanowires encapsulated with ZnO. GaN-core/ZnO-shell nanowires were fabricated by using a two-step process comprising the thermal evaporation of GaN powders and the atomic layer deposition of ZnO. The core-shell nanowires ranged from 80 to 120 nm in diameter and from a few tens to a few hundreds of micrometers in length, with a mean shell layer thickness of ~8 nm. Multiple-networked pristine GaN nanowire and ZnO-encapsulated GaN (or GaN-core/ZnO-shell) nanowire sensors showed responses of 120-147% and 179-389%, respectively, to 500-2,500 ppm of H2 at room temperature under UV (254 nm) illumination. The underlying mechanism of the enhanced response of the GaN nanowire to H2 gas when using ZnO encapsulation and UV irradiation is discussed.

  7. Acoustically assisted removal of nitrogen oxide from high temperature flue gas.

    PubMed

    Komarov, Sergey V; Nemeth, Szabolcs; Hirasawa, Masahiro

    2005-02-01

    The present study focuses on a possibility for improving NO removal efficiency from flue gas by application of powerful sound waves. The sound waves (frequency 6.9-17.2kHz, intensity 144-160dB) are propagated from Hartmann sound generators to a preheated graphite disk inside a vertical reaction tube (height 1.8m, I.D. 105mm). An Ar-NO synthetic mixture (NO 911-934ppm) is blown onto the disk surface to perform reactions in the system C-NO. It is found that the NO reduction rate can be significantly enhanced by the sound waves but the enhancement effect is dependent on the sound frequency, intensity and temperature of disk surface. The better effects are obtained at a temperature of 973K and sound frequencies between 9.6 and 12.4kHz. Under these conditions, the sound application results in 3-5-fold enhancement of NO reduction rate. The obtained effects are explained in terms of gas-phase mass transfer controlling mechanism and of near surface turbulent diffusivity.

  8. Optimization and Technological Development Strategies of an Antimicrobial Extract from Achyrocline alata Assisted by Statistical Design

    PubMed Central

    Demarque, Daniel P.; Fitts, Sonia Maria F.; Boaretto, Amanda G.; da Silva, Júlio César Leite; Vieira, Maria C.; Franco, Vanessa N. P.; Teixeira, Caroline B.; Toffoli-Kadri, Mônica C.; Carollo, Carlos A.

    2015-01-01

    Achyrocline alata, known as Jateí-ka-há, is traditionally used to treat several health problems, including inflammations and infections. This study aimed to optimize an active extract against Streptococcus mutans, the main bacteria that causes caries. The extract was developed using an accelerated solvent extraction and chemometric calculations. Factorial design and response surface methodologies were used to determine the most important variables, such as active compound selectivity. The standardized extraction recovered 99% of the four main compounds, gnaphaliin, helipyrone, obtusifolin and lepidissipyrone, which represent 44% of the extract. The optimized extract of A. alata has a MIC of 62.5 μg/mL against S. mutans and could be used in mouth care products. PMID:25710523

  9. Fast surrogate-assisted simulation-driven optimization of compact microwave hybrid couplers

    NASA Astrophysics Data System (ADS)

    Kurgan, Piotr; Koziel, Slawomir

    2016-07-01

    This work presents a robust methodology for expedited simulation-driven design optimization of compact microwave hybrid couplers. The technique relies on problem decomposition, and a bottom-up design strategy, starting from the level of basic building blocks of the coupler, and finishing with a tuning procedure that exploits a fast surrogate model of the entire structure. The latter is constructed by cascading local response surface approximations of coupler elementary elements. The cross-coupling effects within the structure are neglected in the first stage of the design process; however, they are accounted for in the tuning phase by means of space-mapping correction of the surrogate. The proposed approach is demonstrated through the design of a compact rat-race and two branch-line couplers. In all cases, the computational cost of the optimization process is very low and corresponds to just a few high-fidelity electromagnetic simulations of respective structures. Experimental validation is also provided.

  10. Optimizing Ship-to-Shore Movement for Hospital Ship Humanitarian Assistance Operations

    DTIC Science & Technology

    2008-03-01

    Programming – The Global Search.” (2007). ———. Xpress -MP Release 2007 www.dashoptimization.com (accessed March 21, 2008). Department of the Navy...of personnel between T-AH and watercraft. The T-AH HAT model is implemented in Xpress -MP, with a supporting MS- Access database. Our optimized...Governmental Organization (NGO) partners. It has been noted hospital ships may be viewed as offensive participants in the so-called Global War on

  11. MULTI-SCALE MODELING AND APPROXIMATION ASSISTED OPTIMIZATION OF BARE TUBE HEAT EXCHANGERS

    SciTech Connect

    Bacellar, Daniel; Ling, Jiazhen; Aute, Vikrant; Radermacher, Reinhard; Abdelaziz, Omar

    2014-01-01

    Air-to-refrigerant heat exchangers are very common in air-conditioning, heat pump and refrigeration applications. In these heat exchangers, there is a great benefit in terms of size, weight, refrigerant charge and heat transfer coefficient, by moving from conventional channel sizes (~ 9mm) to smaller channel sizes (< 5mm). This work investigates new designs for air-to-refrigerant heat exchangers with tube outer diameter ranging from 0.5 to 2.0mm. The goal of this research is to develop and optimize the design of these heat exchangers and compare their performance with existing state of the art designs. The air-side performance of various tube bundle configurations are analyzed using a Parallel Parameterized CFD (PPCFD) technique. PPCFD allows for fast-parametric CFD analyses of various geometries with topology change. Approximation techniques drastically reduce the number of CFD evaluations required during optimization. Maximum Entropy Design method is used for sampling and Kriging method is used for metamodeling. Metamodels are developed for the air-side heat transfer coefficients and pressure drop as a function of tube-bundle dimensions and air velocity. The metamodels are then integrated with an air-to-refrigerant heat exchanger design code. This integration allows a multi-scale analysis of air-side performance heat exchangers including air-to-refrigerant heat transfer and phase change. Overall optimization is carried out using a multi-objective genetic algorithm. The optimal designs found can exhibit 50 percent size reduction, 75 percent decrease in air side pressure drop and doubled air heat transfer coefficients compared to a high performance compact micro channel heat exchanger with same capacity and flow rates.

  12. Optimization of ultrasound-assisted extraction of flavonoids compounds from Chenopodium hybridum L. stem with response surface methodology

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Hu, H. B.; Wang, C. L.; Ma, S. R.; Zhang, L. L.

    2016-08-01

    Ultrasound-assisted extraction (UAE) of flavonoids compounds (FC) from the stem of Chenopodium hybridum L.(C.hybridum L.) was investigated in this paper. Significant technological parameters were screened and optimized by using Plackett-Burman (PB) design, Steepest ascent method and Box-Behnken (BB) design, respectively. A mathematical model with high correlation coefficient (R2=0.9896) was developed and showed good consistency between the experimental and predicted values. The optimum conditions for UAE were obtained by res- ponse surface methodology (RSM) as follows: volumn fraction of ethanol 76.62 %, extractive temperature 78.69°C, and liquid to solid ratio 58.43 for 30 min. Under these conditions, total flavo- noid content (TFC) of 9.4701 mg RE/100g were gained and it was closely related with predi- cted value (9.4640 mg RE/100g) and indicated the suitability of the developed model.

  13. Laparoscopic-assisted catheter insertion for continuous ambulatory peritoneal dialysis: A case report of simple technique for optimal placement

    PubMed Central

    Hori, Tomohide; Nakauchi, Masaya; Nagao, Kazuhiro; Oike, Fumitaka; Tanaka, Takahiro; Gunji, Daigo; Okada, Noriyuki

    2013-01-01

    A 40-year-old male underwent tube placement surgery for continuous ambulatory peritoneal dialysis (CAPD). A 2-cm skin incision was made, and the peritoneum was reflected enough to perform secure fixation. A swan-necked, double-felted silicone CAPD catheter was inserted, and the felt cuff was sutured to the peritoneum to avoid postoperative leakage. An adequate gradient for tube fixation to the abdominal wall was confirmed. The CAPD tube was passed through a subcutaneous tunnel. Aeroperitoneum was induced to confirm that there was no air leakage from the sites of CAPD insertion. Two trocars were placed, and we confirmed that the CAPD tube led to the rectovesical pouch. Tip position was reliably observed laparoscopically. Optimal patency of the CAPD tube was confirmed during surgery. Placement of CAPD catheters by laparoscopic-assisted surgery has clear advantages in simplicity, safety, flexibility, and certainty. Laparoscopic technique should be considered the first choice for CAPD tube insertion. PMID:24179625

  14. Ultrasonic assisted removal of sunset yellow from aqueous solution by zinc hydroxide nanoparticle loaded activated carbon: Optimized experimental design.

    PubMed

    Roosta, M; Ghaedi, M; Sahraei, R; Purkait, M K

    2015-01-01

    The efficiency of zinc hydroxide nanoparticle loaded on activated carbon (Zn(OH)2-NP-AC) in the removal of sunset yellow from aqueous solutions using ultrasonic-assisted adsorption method was investigated. This nanomaterial was characterized using different techniques such as SEM, XRD and UV-vis spectrophotometer. A central composite design (CCD) was used for the optimization of significant factors using response surface methodology (RSM). Under the best conditions (5.2 min of sonication time, pH3, 0.023 g of adsorbent and 30 mg L(-1) of SY), Langmuir model was fitting the experimental equilibrium data well. The small amount of proposed adsorbent (0.023 g) is applicable for the successful removal of SY (>97%) in short time (5 min) with high adsorption capacity (83-114 mg g(-1)).

  15. Parameter estimation with a novel gradient-based optimization method for biological lattice-gas cellular automaton models.

    PubMed

    Mente, Carsten; Prade, Ina; Brusch, Lutz; Breier, Georg; Deutsch, Andreas

    2011-07-01

    Lattice-gas cellular automata (LGCAs) can serve as stochastic mathematical models for collective behavior (e.g. pattern formation) emerging in populations of interacting cells. In this paper, a two-phase optimization algorithm for global parameter estimation in LGCA models is presented. In the first phase, local minima are identified through gradient-based optimization. Algorithmic differentiation is adopted to calculate the necessary gradient information. In the second phase, for global optimization of the parameter set, a multi-level single-linkage method is used. As an example, the parameter estimation algorithm is applied to a LGCA model for early in vitro angiogenic pattern formation.

  16. Optimization of Ultrasonic-Assisted Extraction of Flavonoid Compounds and Antioxidants from Alfalfa Using Response Surface Method.

    PubMed

    Jing, Chang-Liang; Dong, Xiao-Fang; Tong, Jian-Ming

    2015-08-26

    Ultrasonic-assisted extraction (UAE) was used to extract flavonoid-enriched antioxidants from alfalfa aerial part. Response surface methodology (RSM), based on a four-factor, five-level central composite design (CCD), was employed to obtain the optimal extraction parameters, in which the flavonoid content was maximum and the antioxidant activity of the extracts was strongest. Radical scavenging capacity of the extracts, which represents the amounts of antioxidants in alfalfa, was determined by using 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonicacid) (ABTS) and 2,2'-diphenyl-1-picrylhydrazyl (DPPH) methods. The results showed good fit with the proposed models for the total flavonoid extraction (R² = 0.9849), for the antioxidant extraction assayed by ABTS method (R² = 0.9764), and by DPPH method (R² = 0.9806). Optimized extraction conditions for total flavonoids was a ratio of liquid to solid of 57.16 mL/g, 62.33 °C, 57.08 min, and 52.14% ethanol. The optimal extraction parameters of extracts for the highest antioxidant activity by DPPH method was a ratio of liquid to solid 60.3 mL/g, 54.56 °C, 45.59 min, and 46.67% ethanol, and by ABTS assay was a ratio of liquid to solid 47.29 mL/g, 63.73 °C, 51.62 min, and 60% ethanol concentration. Our work offers optimal extraction conditions for total flavonoids and antioxidants from alfalfa.

  17. Optimization of microwave-assisted extraction for six inorganic and organic arsenic species in chicken tissues using response surface methodology.

    PubMed

    Zhang, Wenfeng; Hu, Yuanan; Cheng, Hefa

    2015-09-01

    Response surface methodology was applied to optimize the parameters for microwave-assisted extraction of six major inorganic and organic arsenic species (As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p-arsanilic acid, and roxarsone) from chicken tissues, followed by detection using a high-performance liquid chromatography with inductively coupled mass spectrometry detection method, which allows the simultaneous analysis of both inorganic and organic arsenic species in the extract in a single run. Effects of extraction medium, solution pH, liquid-to-solid ratio, and the temperature and time of microwave-assisted extraction on the extraction of the targeted arsenic species were studied. The optimum microwave-assisted extraction conditions were: 100 mg of chicken tissue, extracted by 5 mL of 22% v/v methanol, 90 mmol/L (NH4 )2 HPO4 , and 0.07% v/v trifluoroacetic acid (with pH adjusted to 10.0 by ammonium hydroxide solution), ramping for 10 min to 71°C, and holding for 11 min. The method has good extraction performance for total arsenic in the spiked and nonspiked chicken tissues (104.0 ± 13.8% and 91.6 ± 7.8%, respectively), except for the ones with arsenic contents close to the quantitation limits. Limits of quantitation (S/N = 10) for As(III), As(V), dimethyl arsenic acid, monomethyl arsenic acid, p-arsanilic acid, and roxarsone in chicken tissues using this method were 0.012, 0.058, 0.039, 0.061, 0.102, and 0.240 mg/kg (dry weight), respectively.

  18. Extraction of bioactives from Orthosiphon stamineus using microwave and ultrasound-assisted techniques: Process optimization and scale up.

    PubMed

    Chan, Chung-Hung; See, Tiam-You; Yusoff, Rozita; Ngoh, Gek-Cheng; Kow, Kien-Woh

    2017-04-15

    This work demonstrated the optimization and scale up of microwave-assisted extraction (MAE) and ultrasonic-assisted extraction (UAE) of bioactive compounds from Orthosiphon stamineus using energy-based parameters such as absorbed power density and absorbed energy density (APD-AED) and response surface methodology (RSM). The intensive optimum conditions of MAE obtained at 80% EtOH, 50mL/g, APD of 0.35W/mL, AED of 250J/mL can be used to determine the optimum conditions of the scale-dependent parameters i.e. microwave power and treatment time at various extraction scales (100-300mL solvent loading). The yields of the up scaled conditions were consistent with less than 8% discrepancy and they were about 91-98% of the Soxhlet extraction yield. By adapting APD-AED method in the case of UAE, the intensive optimum conditions of the extraction, i.e. 70% EtOH, 30mL/g, APD of 0.22W/mL, AED of 450J/mL are able to achieve similar scale up results.

  19. Research on optimal process parameters in thermally oxidation-assisted polishing of reaction-sintered silicon carbide

    NASA Astrophysics Data System (ADS)

    Shen, Xinmin; Yamamura, Kazuya; Zhang, Xiaonan; Zhang, Xiangpo; Wang, Dong; Peng, Kang

    2016-10-01

    Reaction-sintered silicon carbide (RS-SiC) has been widely used in space telescope systems for its excellent physical and mechanical properties. Thermally oxidation-assisted polishing is a practical machining method to obtain RS-SiC parts with high precision, and the research focus is optimization of process parameters, because there are bumpy structures on the oxidized RS-SiC. By atomic force microscopy (AFM) detection, the distributions of oxides on the oxidized RS-SiC sample are quantitative analyzed when the thermal oxidation time is 5min, 30min, and 60min, and the calculated average differences of oxide heights between the initial Si grains and SiC grains are 10.7nm, 25.1nm, and 35.2nm, respectively. Meanwhile, the volume expansion coefficient in oxidation of Si/SiC to SiO2 is 2.257 and 2.194, respectively. Through theoretical derivation based on the Deal-Grove model, the numerical relationship between differences of oxide heights and thermal oxidation time is obtained. Combining with the material removal rate of oxide by ceria slurry in the abrasive polishing, the obtained surface quality can be precisely forecasted and controlled. The oxidized RS-SiC sample, when the oxidation time is 30min, is polished with different times to verify the theoretical analysis results. When the polishing times are 20min, 30min, and 40min, the obtained differences of oxide heights by the AFM detection are consistent with theoretical calculated results. Research on the optimal process parameters in thermally oxidation-assisted polishing of RS-SiC can improve the process level of RS-SiC sample and promote the application of SiC parts.

  20. Optimization of Ultrasound-Assisted Extraction, Preliminary Characterization and In Vitro Antioxidant Activity of Polysaccharides from Green Pea Pods

    PubMed Central

    Jalili Safaryan, Maryam; Ganjloo, Ali; Bimakr, Mandana; Zarringhalami, Soheila

    2016-01-01

    In this study, ultrasound-assisted extraction of green pea pod polysaccharide (GPPP) was investigated and optimized using a central composite response surface design coupled with a numerical optimization technique. The effects of ultrasonic power (50–150 W), sonication time (20–80 min), ratio of water to raw material (20:1–40:1 mL/g) and extraction temperature (40–80 °C) on polysaccharide extraction yield were studied. The maximum extraction yield was obtained with a sonication power of 135.34 W, extraction time of 48.61 min, ratio of water to raw material of 33.6:1 mL/g and extraction temperature of 68.25 °C. Under these conditions, the experimental yield was 7.37% ± 0.13%, which was in close agreement with the predicted value (7.20%). The GPPP has been analyzed in order to identify a variety of chemical properties. The FT-IR spectrum demonstrated obvious characteristic peaks of polysaccharides. Furthermore, antioxidant activity of GPPP was evaluated by various antioxidant assays in vitro. The results revealed that GPPP possessed considerable DPPH free radical scavenging activity (91.03%), reducing power (0.63) and ferric reducing antioxidant power (0.34 mmol/L) at a total amount of 0.9 mg/mL. These findings indicated that GPPP extracted using an ultrasound-assisted extraction technique has potential as a novel source of natural antioxidant agent for future applications. PMID:28231174

  1. Optimization of Ultrasound-Assisted Extraction of Morphine from Capsules of Papaver somniferum by Response Surface Methodology

    PubMed Central

    Bulduk, Ibrahim; Gezer, Bahdışen; Cengiz, Mustafa

    2015-01-01

    In this study, amount of morphine from poppy capsules (Papaver somniferum) was investigated using ultrasonic assisted extraction (UAE). Response surface methodology was used to estimate effective experimental conditions on the content extraction of poppy capsules. For this purpose, solvent/solid ratio (10–20 mL/500 mg sample), pH (1–13), time (30–60 min), and temperature (30–50°C) were chosen as experimental variables. The affected response is extraction recovery values for morphine from poppy straw. For interpreting the relationship between experimental factors and response, a design table was established with combinations of three different concentrations levels of this compound in 29 trials. The second order quadratic model gave a satisfactory description of the experimental data. In our study, R-Squared (0.96), Adj-R-Squared (0.92), and Pred R-Squared (0.78) values for extraction yield display good accuracy of the derived model. The predicted optimal conditions for the highest morphine level (3.38 mg morphine/500 mg-sample) were found at 19.99 mL solvent/500 mg solid ratio, 59.94 min extraction time, 1.10 pH, and 42.36°C temperature. In the optimal extraction conditions, the experimental values are very close to the predicted values. Consequently, the response surface modeling can be achieved sufficiently to predict extraction yield from poppy straw by ultrasound assisted extraction. PMID:25861273

  2. Employing response surface methodology for the optimization of ultrasound assisted extraction of lutein and β-carotene from spinach.

    PubMed

    Altemimi, Ammar; Lightfoot, David A; Kinsel, Mary; Watson, Dennis G

    2015-04-14

    The extraction of lutein and β-carotene from spinach (Spinacia oleracea L.) leaves is important to the dietary supplement industry. A Box-Behnken design and response surface methodology (RSM) were used to investigate the effect of process variables on the ultrasound-assisted extraction (UAE) of lutein and β-carotene from spinach. Three independent variables, extraction temperature (°C), extraction power (%) and extraction time (min) were studied. Thin-layer chromatography (TLC) followed by UV visualization and densitometry was used as a simple and rapid method for both identification and quantification of lutein and β-carotene during UAE. Methanol extracts of leaves from spinach and authentic standards of lutein and β-carotene were separated by normal-phase TLC with ethyl acetate-acetone (5:4 (v/v)) as the mobile phase. In this study, the combination of TLC, densitometry, and Box-Behnken with RSM methods were effective for the quantitative analysis of lutein and β-carotene from spinach extracts. The resulting quadratic polynomial models for optimizing lutein and β-carotene from spinach had high coefficients of determination of 0.96 and 0.94, respectively. The optimal UAE settings for output of lutein and β-carotene simultaneously from spinach extracts were an extraction temperature of 40 °C, extraction power of 40% (28 W/cm3) and extraction time of 16 min. The identity and purity of each TLC spot was measured using time-of-flight mass spectrometry. Therefore, UAE assisted extraction of carotenes from spinach can provide a source of lutein and β-carotene for the dietary supplement industry.

  3. Effect of laser parameters and assist gas on spectral response of silicon fibrous nanostructure

    SciTech Connect

    Mahmood, Abdul Salam; Venkatakrishnan, Krishnan; Alubiady, M.; Tan, Bo

    2010-11-15

    This article report, for the first time, the influence of laser parameters on the spectral response of weblike silicon fibrous nanostructures. These nanostructures are formed by femtosecond laser irradiation at megahertz pulse frequency under atmosphere and nitrogen ambient. The observed decreasing in reflectance is correlated with the density of fibrous nanostructures and the size of the agglomerated nanoparticles. Compared to bulk silicon, Raman spectra of fibrous nanostructures shows a downward shift and asymmetric broadening at the first order phonon peak. The shift and broadening are attributed to phonon confinement of fibrous nanostructure. Polarization and nitrogen gas modify the morphology of generated nanomaterials but does not have effect on light absorptance. Pulsewidth and pulse frequency do not have significant effect on light absorptance.

  4. Matrix-assisted laser desorption mass spectrometry of gas-phase peptide-metal complexes

    NASA Astrophysics Data System (ADS)

    Hortal, Ana R.; Hurtado, Paola; Martínez-Haya, Bruno

    2008-12-01

    Cation attachment to a model peptide has been investigated in matrix-assisted laser desorption experiments. Angiotensin I (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe-His-Leu) is chosen as a system for study, and Cu2+ and K+ salts are used as cationizing agents. Three fundamentally different types of samples are investigated: (1) a crystalline sample of Ang I, metal salt and MALDI matrix, prepared with the conventional dried droplet method; (2) a solvent-free fine powder mixture of the same three compounds, and (3) a solution of the angiotensin and the metal salt in an ionic liquid matrix (a molten organic salt that acts as a MALDI active solvent). Effective protonation and cationization of the peptide are achieved with the three methods. The transition metal systematically provides more efficient cationization than the alkali metal. At sufficiently high concentration of the salt, the attachment of up to four copper cations to the angiotensin is observed in the MALDI spectrum. In contrast, only one K+ cation is efficiently bound to the peptide. For a given salt concentration, the highest degree of cationization is obtained in the laser desorption from the ionic liquid matrix. This is attributed to the efficient transfer of free metal cations to the desorption plume, where the complexation takes place.

  5. Design Optimization And Thermal Analysis Of Multipurpose Refrigerant Gas Recovery Machine: An Innovative Approach

    NASA Astrophysics Data System (ADS)

    Jirapure, Sagar C.

    2010-10-01

    Today on the global scene, world will see a definite impact of global temperatures, coupled with burgeoning population, will make society more vulnerable to climatic disorder, drought, famines, and flood longer heat waves spreading to newer areas. Tropical islands and low-lying coastal areas will face the treat of being submerged. Hence, it is important to reduce refrigerant emission and the approaching and with approaching phase out date for CFC elimination. It is important to recover as much of refrigerant as possible. Likewise, HFCs should also be recovered as they have high GWP. For such recovery of refrigerant, a recovery & recycling machine is required. The machine is usually comprising a hermetic compressor, air-cooled condenser, distilator, Oil separator, filters and Electric motor. The refrigerant from the appliances is drown through the filters by compressor and then discharged into recovery cylinder. The recovery cylinder should just be used for recovered refrigerant. This is because oil will usually be covered with refrigerant and this will contaminate the cylinder. It is therefore very important to treat the recovery of refrigerant at most accuracy, which require close optimization of design and further analysis of gas behavior in the system. This project aims to provide optimum solution as regards to thermal analysis of gas recovery machine. For getting insight the parameters like Specific heat of vapor at constant pressure, Density of saturated vapor, Latent heat of vaporization at boiling point, Thermal conductivity of vapor, Surface tension, etc. will require critical approach. To impart the thermal analysis, ANSYS software is proposed. It in turn provides the details of temperatures through out the piping of machine, pressure and velocity of at various locations of different components as well as the thermal zones near to high pressure and temperatures in the machine, which gives better approach for design of future gas recovery machines. It is

  6. Fuel-Optimal Trajectories in a Planet-Moon Environment Using Multiple Gravity Assists

    NASA Technical Reports Server (NTRS)

    Ross, Shane D.; Grover, Piyush

    2007-01-01

    For low energy spacecraft trajectories such as multi-moon orbiters for the Jupiter system, multiple gravity assists by moons could be used in conjunction with ballistic capture to drastically decrease fuel usage. In this paper, we outline a procedure to obtain a family of zero-fuel multi-moon orbiter trajectories, using a family of Keplerian maps derived by the first author previously. The maps capture well the dynamics of the full equations of motion; the phase space contains a connected chaotic zone where intersections between unstable resonant orbit manifolds provide the template for lanes of fast migration between orbits of different semimajor axes. Patched three body approach is used and the four body problem is broken down into two three-body problems, and the search space is considerably reduced by the use of properties of the Keplerian maps. We also introduce the notion of Switching Region where the perturbations due to the two perturbing moons are of comparable strength, and which separates the domains of applicability of the corresponding two Keplerian maps.

  7. Optimization of the Outflow Graft Position and Angle in a Left Ventricular Assist Device

    NASA Astrophysics Data System (ADS)

    McGah, Patrick; Prisco, Anthony; Beckman, Jennifer; Mokadam, Nahush; Mahr, Claudius; Aliseda, Alberto

    2015-11-01

    The placement of the outflow graft in the aorta plays a key role in the hemodynamics of Left Ventricle Assist Devices (LVAD), a medical device with a growing importance in the treatment of end-stage heart failure. We use a patient-specific computational model of the VAD and the ascending aorta to investigate the impact of VAD outflow graft configuration on the residence time and wall shear stresses along the ascending aorta and the ostia of the upper branches. The flow induced by the combination of VAD output through the graft anastomosed to the aorta and the limited cardiac output through intermittent opening of the aortic valve is studied to determine the nature of thrombogenic flow patterns. Outflow grafts are virtually anastomosed along the ascending aorta or subclavian artery of the patient-specific model at different positions and angles that are surgically-informed. Detailed markers of thrombosis, such as cell residence time, wall shear stress, and shear stress gradients are analyzed and compared for the different configurations. The angle of incidence of the outflow graft critically influences the volume of recirculating flow between aortic valve and anastomosis, and the aortic pressure acting against aortic valve opening.

  8. Optimization of the ultrasound-assisted synthesis of lutein disuccinate using uniform design.

    PubMed

    Li, Da-Jing; Song, Jiang-Feng; Xu, Ai-Qin; Liu, Chun-Quan

    2014-01-01

    The ultrasound-assisted synthesis of lutein disuccinate from all-trans lutein (AL) and succinic anhydride (SA) was investigated in this study. Triethylamine was used as the catalyst. Based on the single-factor experiments, a 7-level-3-factor uniform design and response surface analysis were further employed to evaluate the effects of the selected variables including molar ratio of SA/AL, reaction time and ultrasonic power on the yield of lutein disuccinate. The results indicated that the data were adequately fitted into a second-order polynomial model; the molar ratio of SA/AL significantly affected the synthesis of lutein disuccinate, whereas reaction time and ultrasonic power did not. Based on ridge max analysis, the optimum condition for lutein disuccinate synthesis was predicted to be the molar ratio of SA/AL 265.3:1, ultrasonic power 300 W and reaction time 131.6 min with the lutein disuccinate yield of 80.53±0.18%, which give a 43.8% increase compared with the traditional method, and also significantly shorten the reaction time.

  9. Optimization of olive leaf extract obtained by ultrasound-assisted extraction with response surface methodology.

    PubMed

    Şahin, Selin; Samlı, Rüya

    2013-01-01

    In the present article, ultrasound-assisted extraction (UAE) of polyphenols from agricultural and industrial waste of olive oil and table oil productions, olive tree (Olea europaea) leaves were investigated. The aim of the study is to examine the extraction parameters such as solvent concentration (0-100% ethanol (EtOH), v/v), the ratio of solid to solvent (25-50mg/mL) and extraction time (20-60 min), and to obtain the best possible combinations of these parameters through response surface methodology (RSM). The extract yield was stated as mg extract per g of dried leaf (DL). Total phenolic content was expressed in gallic acid equivalent (GAE) per g of dried leaf. Free radical scavenging activity for the antioxidant capacity was tested by 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical. The second order polynomial model gave a satisfactory description of the experimental data. 201.2158 mg extract/g DL, 25.0626 mg GAE/g DL, and 95.5610% in respect to inhibition of DPPH radical were predicted at the optimum operating conditions (500 mg solid to 10 mL solvent ratio, 60 min of extraction time and 50% EtOH composition), respectively.

  10. Optimization of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Analysis for Bacterial Identification

    PubMed Central

    Khot, Prasanna D.; Couturier, Marc R.; Wilson, Andrew; Croft, Ann

    2012-01-01

    Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a relatively new addition to the clinical microbiology laboratory. The performance of the MALDI Biotyper system (Bruker Daltonics) was compared to those of phenotypic and genotypic identification methods for 690 routine and referred clinical isolates representing 102 genera and 225 unique species. We systematically compared direct-smear and extraction methods on a taxonomically diverse collection of isolates. The optimal score thresholds for bacterial identification were determined, and an approach to address multiple divergent results above these thresholds was evaluated. Analysis of identification scores revealed optimal species- and genus-level identification thresholds of 1.9 and 1.7, with 91.9% and 97.0% of isolates correctly identified to species and genus levels, respectively. Not surprisingly, routinely encountered isolates showed higher concordance than did uncommon isolates. The extraction method yielded higher scores than the direct-smear method for 78.3% of isolates. Incorrect species were reported in the top 10 results for 19.4% of isolates, and although there was no obvious cutoff to eliminate all of these ambiguities, a 10% score differential between the top match and additional species may be useful to limit the need for additional testing to reach single-species-level identifications. PMID:22993178

  11. Inorganic selenium speciation analysis in Allium and Brassica vegetables by ionic liquid assisted liquid-liquid microextraction with multivariate optimization.

    PubMed

    Castro Grijalba, Alexander; Martinis, Estefanía M; Wuilloud, Rodolfo G

    2017-03-15

    A highly sensitive vortex assisted liquid-liquid microextraction (VA-LLME) method was developed for inorganic Se [Se(IV) and Se(VI)] speciation analysis in Allium and Brassica vegetables. Trihexyl(tetradecyl)phosphonium decanoate phosphonium ionic liquid (IL) was applied for the extraction of Se(IV)-ammonium pyrrolidine dithiocarbamate (APDC) complex followed by Se determination with electrothermal atomic absorption spectrometry. A complete optimization of the graphite furnace temperature program was developed for accurate determination of Se in the IL-enriched extracts and multivariate statistical optimization was performed to define the conditions for the highest extraction efficiency. Significant factors of IL-VA-LLME method were sample volume, extraction pH, extraction time and APDC concentration. High extraction efficiency (90%), a 100-fold preconcentration factor and a detection limit of 5.0ng/L were achieved. The high sensitivity obtained with preconcentration and the non-chromatographic separation of inorganic Se species in complex matrix samples such as garlic, onion, leek, broccoli and cauliflower, are the main advantages of IL-VA-LLME.

  12. Optimization of the ultrasound-assisted extraction of anthocyanins and total phenolic compounds in mulberry (Morus nigra) pulp.

    PubMed

    Espada-Bellido, Estrella; Ferreiro-González, Marta; Carrera, Ceferino; Palma, Miguel; Barroso, Carmelo G; Barbero, Gerardo F

    2017-03-15

    New ultrasound-assisted extraction methods for the determination of anthocyanins and total phenolic compounds present in mulberries have been developed. Several extraction variables, including methanol composition (50-100%), temperature (10-70°C), ultrasound amplitude (30-70%), cycle (0.2-0.7s), solvent pH (3-7) and solvent-solid ratio (10:1.5-20:1.5) were optimized. A Box-Behnken design in conjunction with a response surface methodology was employed to optimize the conditions for the maximum response based on 54 different experiments. Two response variables were considered: total anthocyanins and total phenolic compounds. Extraction temperature and solvent composition were found to be the most influential parameters for anthocyanins (48°C and 76%) and phenolic compounds (64°C and 61%). The developed methods showed high reproducibility and repeatability (RSD<5%). Finally, the new methods were successfully applied to real samples in order to investigate the presence of anthocyanins and total phenolic compounds in several mulberry jams.

  13. Optimization for ultrasound-assisted extraction of polysaccharides with chemical composition and antioxidant activity from the Artemisia sphaerocephala Krasch seeds.

    PubMed

    Zheng, Quan; Ren, Daoyuan; Yang, Nana; Yang, Xingbin

    2016-10-01

    Artemisia sphaerocephala Krasch seeds polysaccharides have been reported to have a variety of important biological activities. However, effective extraction of Artemisia sphaerocephala Krasch seeds polysaccharides is still an unsolved issue. In this study, the orthogonal rotatable central composite design was employed to optimize ultrasound-assisted extraction conditions of Artemisia sphaerocephala Krasch seeds polysaccharides. Based on a single-factor analysis method, ultrasonic power, extraction time, solid-liquid ratio and extraction temperature were shown to significantly affect the yield of polysaccharides extracted from the A. sphaerocephala Krasch seeds. The optimal conditions for extraction of Artemisia sphaerocephala Krasch seeds polysaccharides were determined as following: ultrasonic power 243W, extraction time 125min, solid-liquid ratio 64:1 and extraction temperature 64°C, where the experimental yield was 14.78%, which was well matched with the predicted value of 14.81%. Furthermore, ASKP was identified as a typical heteropolysaccharide with d-galacturonic acid (38.8%) d-galactose (20.2%) and d-xylose (15.5%) being the main constitutive monosaccharides. Moreover, Artemisia sphaerocephala Krasch seeds polysaccharides exhibited high total reducing power and considerable scavenging activities on DPPH, hydroxyl and superoxide radicals, in a concentration-dependent manner in vitro.

  14. Response Surface Optimization of a Rapid Ultrasound-Assisted Extraction Method for Simultaneous Determination of Tetracycline Antibiotics in Manure

    PubMed Central

    Li, Lanqing; Sun, Mingxing; Zhou, Hui; Zhou, Yun; Chen, Ping; Min, Hong; Shen, Guoqing

    2015-01-01

    A rapid and cleanup-free ultrasound-assisted extraction method is proposed for the simultaneous extraction of oxytetracycline, tetracycline, chlortetracycline, and doxycycline in manure. The analytes were determined using high-performance liquid chromatography with ultraviolet detector. The influence of several variables on the efficiency of the extraction procedure was investigated by single-factor experiments. The temperature, pH, and amount of extraction solution were selected for optimization experiment using response surface methodology. The calibration curves showed good linearity (R2 > 0.99) for all analytes in the range of 0.1–20 μg/mL. The four antibiotics were successfully extracted from manure with recoveries ranging from 81.89 to 92.42% and good reproducibility (RSD, <4.06%) under optimal conditions, which include 50 mL of McIlvaine buffer extraction solution (pH 7.15) mixed with 1 g of manure sample, extraction temperature of 40°C, extraction time of 10 min, and three extraction cycles. Method quantification limits of 1.75–2.32 mg/kg were obtained for the studied compounds. The proposed procedure demonstrated clear reductions in extraction time and elimination of cleanup steps. Finally, the applicability to tetracyclines antibiotics determination in real samples was evaluated through the successful determination of four target analytes in swine, cow manure, and mixture of animal manure with inorganic fertilizer. PMID:25922787

  15. Optimization of ultrasound assisted extraction of bioactive components from brown seaweed Ascophyllum nodosum using response surface methodology.

    PubMed

    Kadam, Shekhar U; Tiwari, Brijesh K; Smyth, Thomas J; O'Donnell, Colm P

    2015-03-01

    The objective of this study was to investigate the effect of key extraction parameters of extraction time (5-25 min), acid concentration (0-0.06 M HCl) and ultrasound amplitude (22.8-114 μm) on yields of bioactive compounds (total phenolics, fucose and uronic acid) from Ascophyllumnodosum. Response surface methodology was employed to optimize the extraction variables for bioactive compounds' yield. A second order polynomial model was fitted well to the extraction experimental data with (R(2)>0.79). Extraction yields of 143.12 mgGAE/gdb, 87.06 mg/gdb and 128.54 mg/gdb were obtained for total phenolics, fucose and uronic acid respectively at optimized extraction conditions of extraction time (25 min), acid concentration (0.03 M HCl) and ultrasonic amplitude (114 μm). Mass spectroscopy analysis of extracts show that ultrasound enhances the extraction of high molecular weight phenolic compounds from A. nodosum. This study demonstrates that ultrasound assisted extraction (UAE) can be employed to enhance extraction of bioactive compounds from seaweed.

  16. Optimization of ultrasound-assisted extraction of anthocyanins from haskap berries (Lonicera caerulea L.) using Response Surface Methodology.

    PubMed

    Celli, Giovana Bonat; Ghanem, Amyl; Brooks, Marianne Su-Ling

    2015-11-01

    Haskap berries (Lonicera caerulea L.) are a rich source of bioactive molecules. As such, the extraction of anthocyanins is important for the development of many value-added products and functional food ingredients. In this paper, the ultrasound-assisted extraction (UAE) of anthocyanins from haskap berries was investigated. Significant independent variables were screened and optimized using Plackett-Burman (PB) and Box-Behnken (BB) designs, respectively. The mathematical model showed a high coefficient of determination (R(2)=0.9396) and the optimum conditions for the extraction were as follows: liquid/solid ratio 25:1 (mL/g), solvent composition of 80% ethanol, addition of 0.5% formic acid, ultrasound bath temperature of 35°C for 20 min. Under these conditions, the total anthocyanin content of 22.73 mg cyaniding 3-glucoside equivalents (C3G)/g dry weight (DW) was consistent with the predicted response of 22.45 mg C3G/g DW from the model (mean error of 1.28%). Five anthocyanins were identified in the optimized extract, namely cyanidin 3,5-diglucoside, cyanidin 3-glucoside, cyanidin 3-rutinoside, pelargonidin 3-glucoside, and peonidin 3-glucoside. Thus, UAE is a suitable technique for the extraction of anthocyanins from haskap berries.

  17. Plasma-assisted cleanup of flue gas. Technical report, 1 December 1993--28 February 1994

    SciTech Connect

    Dhali, S.K.

    1994-06-01

    The authors have conclusively demonstrated that plasma chemistry alone is sufficient to convert SO{sub 2} to H{sub 2}SO{sub 4}, the plasma being produced by a dielectric-barrier discharge. They get nearly 80% removal of SO{sub 2} in a flue gas containing 775 ppm (parts per million) of SO{sub 2} and 99% for SO{sub 2} in concentrations of 300 ppm. A significant achievement during this period is the progress the authors have made with the wetting of the glass by the acid. They are using a simple and cheap method of coating the glass with Teflon (PTFE 30) to provide a hydrophobic surface. These films show chemical inertness to nearly all chemical and solvents and have low friction and antistick surfaces. The following important conclusions can be drawn from the results: (1) The percentage removal does not show saturation with the applied voltage. (2) The removal efficiency at an inlet temperature of 300 C is almost similar to 25 C at high voltages. (3) With longer electrodes the efficiency of removal increases. These results suggest that removal efficiency can be improved further by increasing the voltage and electrode length. The authors are yet to exploit the full range of parameters available. Therefore, it is likely that they will get much improved performance from the system.

  18. Surfactant assisted growth of nanostructured tin oxide films for gas sensing applications

    NASA Astrophysics Data System (ADS)

    Khun, Kamalpreet Khun; Mahajan, Aman; Bedi, R. K.

    2011-12-01

    Porous nanostructured SnO2 films have been prepared using an ultrasonic spray pyrolysis technique in conjunction with cationic, anionic and non ionic surfactants namely CTAB (Cetyl trimethyl ammonium bromide), SDS (sodium dodecyl sulphate) and PEG (polyethylene glycol) respectively. The effect of surfactants on the structural, electrical, optical and gas sensing properties of SnO2 films were investigated by using different techniques such as X-ray diffraction (XRD), Field emission scanning electroscope microscopy (FESEM), two probe technique and Photoluminiscence (PL) studies. The results reveal that the addition of surfactants in the precursor solutions leads to reduction in crystallite size with significant changes in porosity of SnO2 films. PL studies of the films show emissions in the visible region which exhibit changes in the intensities upon variation of surfactants in the precursor solutions. The prepared films were tested for their sensing behaviour towards chlorine and the results reveal that the films prepared in conjunction with cationic surfactant CTAB exhibits a sensing response of 53.5% towards 20 ppm chlorine at a low operating temperature of 150°C.

  19. Controls and measurements of KU engine test cells for biodiesel, SynGas, and assisted biodiesel combustion

    NASA Astrophysics Data System (ADS)

    Cecrle, Eric Daniel

    This thesis is comprised of three unique data acquisition and controls (CDAQ) projects. Each of these projects differs from each other; however, they all include the concept of testing renewable or future fuel sources. The projects were the following: University of Kansas's Feedstock-to-Tailpipe Initiative's Synthesis Gas Reforming rig, Feedstock-to-Tailpipe Initiative's Biodiesel Single Cylinder Test Stand, and a unique Reformate Assisted Biodiesel Combustion architecture. The main responsibility of the author was to implement, develop and test CDAQ systems for the projects. For the Synthesis Gas Reforming rig, this thesis includes a report that summarizes the analysis and solution of building a controls and data acquisition system for this setup. It describes the purpose of the sensors selected along with their placement throughout the system. Moreover, it includes an explanation of the planned data collection system, along with two models describing the reforming process useful for system control. For the Biodiesel Single Cylinder Test Stand, the responsibility was to implement the CDAQ system for data collection. This project comprised a variety of different sensors that are being used collect the combustion characteristics of different biodiesel formulations. This project is currently being used by other graduates in order to complete their projects for subsequent publication. For the Reformate Assisted Biodiesel Combustion architecture, the author developed a reformate injection system to test different hydrogen and carbon monoxide mixtures as combustion augmentation. Hydrogen combustion has certain limiting factors, such as pre-ignition in spark ignition engines and inability to work as a singular fuel in compression ignition engines. To offset these issues, a dual-fuel methodology is utilized by injecting a hydrogen/carbon monoxide mixture into the intake stream of a diesel engine operating on biodiesel. While carbon monoxide does degrade some of the

  20. Optimization-based decision support to assist in logistics planning for hospital evacuations.

    PubMed

    Glick, Roger; Bish, Douglas R; Agca, Esra

    2013-01-01

    The evacuation of the hospital is a very complex process and evacuation planning is an important part of a hospital's emergency management plan. There are numerous factors that affect the evacuation plan including the nature of threat, availability of resources and staff the characteristics of the evacuee population, and risk to patients and staff. The safety and health of patients is of fundamental importance, but safely moving patients to alternative care facilities while under threat is a very challenging task. This article describes the logistical issues and complexities involved in planning and execution of hospital evacuations. Furthermore, this article provides examples of how optimization-based decision support tools can help evacuation planners to better plan for complex evacuations by providing real-world solutions to various evacuation scenarios.

  1. Evaluation of an optimal guidance algorithm for aero-assisted orbit transfer

    NASA Technical Reports Server (NTRS)

    Melamed, N.; Calise, A. J.

    1992-01-01

    A detailed evaluation is performed of a guidance algorithm for aeroassisted orbit transfer that was developed earlier based on the method of matched asymptotic expansions. It is shown that, by exploiting the structure of the matched asymptotic expansion solution procedure, the original problem which requires the solution of a set of 20 implicit algebraic equations can be reduced to a problem of six implicit equations in six unknowns. The main contribution here is that it was possible to obtain a solution that is near optimal, requires a minimum of computation, and thus can be implemented in real time and on-board the vehicle. Guidance law implementation entails treating the current state as a new initial state and repetitively solving the matched asymptotic expansion problem to obtain the feedback controls.

  2. Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column

    NASA Technical Reports Server (NTRS)

    Huz, Kateryna

    2014-01-01

    RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better

  3. Flame-in-gas-shield and miniature diffusion flame hydride atomizers for atomic fluorescence spectrometry: optimization and comparison

    NASA Astrophysics Data System (ADS)

    Marschner, Karel; Musil, Stanislav; Dědina, Jiří

    2015-07-01

    A detailed optimization of relevant experimental parameters of two hydride atomizers for atomic fluorescence spectrometry: flame-in-gas-shield atomizer with a two-channel shielding unit and a standard atomizer for atomic fluorescence spectrometry, miniature diffusion flame, was performed. Arsine, generated by the reaction with NaBH4 in a flow injection arrangement, was chosen as the model hydride. Analytical characteristics of both the atomizers (sensitivity, noise, limits of detection) were compared. Under optimum conditions sensitivity obtained with flame-in-gas-shield atomizer was approximately twice higher than with miniature diffusion flame. The additional advantage of flame-in-gas-shield atomizer is significantly lower flame emission resulting in a better signal to noise ratio. The resulting arsenic limits of detection for miniature diffusion flame and flame-in-gas-shield atomizer were 3.8 ng l- 1 and 1.0 ng l- 1, respectively.

  4. Design Of A Sorbent/desorbent Unit For Sample Pre-treatment Optimized For QMB Gas Sensors

    SciTech Connect

    Pennazza, G.; Cristina, S.; Santonico, M.; Martinelli, E.; Di Natale, C.; D'Amico, A.; Paolesse, R.

    2009-05-23

    Sample pre-treatment is a typical procedure in analytical chemistry aimed at improving the performance of analytical systems. In case of gas sensors sample pre-treatment systems are devised to overcome sensors limitations in terms of selectivity and sensitivity. For this purpose, systems based on adsorption and desorption processes driven by temperature conditioning have been illustrated. The involvement of large temperature ranges may pose problems when QMB gas sensors are used. In this work a study of such influences on the overall sensing properties of QMB sensors are illustrated. The results allowed the design of a pre-treatment unit coupled with a QMB gas sensors array optimized to operate in a suitable temperatures range. The performance of the system are illustrated by the partially separation of water vapor in a gas mixture, and by substantial improvement of the signal to noise ratio.

  5. Optimization of ultrasound-assisted hydroalcoholic extraction of phenolic compounds from walnut leaves using response surface methodology.

    PubMed

    Nour, Violeta; Trandafir, Ion; Cosmulescu, Sina

    2016-10-01

    Context Walnut leaves are highly appreciated for their pharmacological effects and therapeutic properties which are mainly attributed to their high content of phenolic compounds. Objective This study optimizes ultrasound assisted hydroalcoholic extraction (UAE) of phenolic compounds from dried walnut leaves by the maximization of total phenolics content (TPC) and total flavanoids content (TFC) of the extracts. Materials and methods Optimal conditions with regard to ethanol concentration (X1: 12.17-95.83% v/v), extraction time (X2: 8.17-91.83 min) and liquid-to-solid ratio (X3: 4.96-25.04 v/w) were identified using central composite design combined with response surface methodology. A high-performance liquid chromatography method with diode-array detection was used to quantify phenolic acids (gallic, vanillic, chlorogenic, caffeic, syringic, p-coumaric, ferulic, sinapic, salicylic, ellagic and trans-cinnamic), flavonoids (catechin, epicatechin, rutin, myricetin and quercetin) and juglone in the extracts. Results Liquid-to-solid ratio and ethanol concentration proved to be the primary factors affecting the extraction efficiency. The maximum predicted TPC, under the optimized conditions (61% ethanol concentration, 51.28 min extraction time and 4.96 v/w liquid-to-solid ratio) was 10125.4 mg gallic acid equivalents per liter while maximum TFC (2925 mg quercetin equivalents per liter) occurred at 67.83% ethanol concentration, 4.96 v/w liquid-to-solid ratio and 49.37 min extraction time. High significant correlations were found between antioxidant activity and both TPC (R(2 )=( )0.81) and TFC (R(2 )=( )0.78). Discussion and conclusion Extracts very rich in polyphenols could be obtained from walnut leaves by using UAE, aimed at preparing dietary supplements, nutraceuticals or functional food ingredients.

  6. Naturally fractured tight gas reservoir detection optimization. Annual report, September 1993--September 1994

    SciTech Connect

    1994-10-01

    This report is an annual summarization of an ongoing research in the field of modeling and detecting naturally fractured gas reservoirs. The current research is in the Piceance basin of Western Colorado. The aim is to use existing information to determine the most optimal zone or area of fracturing using a unique reaction-transport-mechanical (RTM) numerical basin model. The RTM model will then subsequently help map subsurface lateral and vertical fracture geometries. The base collection techniques include in-situ fracture data, remote sensing, aeromagnetics, 2-D seismic, and regional geologic interpretations. Once identified, high resolution airborne and spaceborne imagery will be used to verify the RTM model by comparing surficial fractures. If this imagery agrees with the model data, then a further investigation using a three-dimensional seismic survey component will be added. This report presents an overview of the Piceance Creek basin and then reviews work in the Parachute and Rulison fields and the results of the RTM models in these fields.

  7. Exchange Bias Optimization by Controlled Oxidation of Cobalt Nanoparticle Films Prepared by Sputter Gas Aggregation.

    PubMed

    Antón, Ricardo López; González, Juan A; Andrés, Juan P; Normile, Peter S; Canales-Vázquez, Jesús; Muñiz, Pablo; Riveiro, José M; De Toro, José A

    2017-03-11

    Porous films of cobalt nanoparticles have been obtained by sputter gas aggregation and controllably oxidized by air annealing at 100 °C for progressively longer times (up to more than 1400 h). The magnetic properties of the samples were monitored during the process, with a focus on the exchange bias field. Air annealing proves to be a convenient way to control the Co/CoO ratio in the samples, allowing the optimization of the exchange bias field to a value above 6 kOe at 5 K. The occurrence of the maximum in the exchange bias field is understood in terms of the density of CoO uncompensated spins and their degree of pinning, with the former reducing and the latter increasing upon the growth of a progressively thicker CoO shell. Vertical shifts exhibited in the magnetization loops are found to correlate qualitatively with the peak in the exchange bias field, while an increase in vertical shift observed for longer oxidation times may be explained by a growing fraction of almost completely oxidized particles. The presence of a hummingbird-like form in magnetization loops can be understood in terms of a combination of hard (biased) and soft (unbiased) components; however, the precise origin of the soft phase is as yet unresolved.

  8. Exchange Bias Optimization by Controlled Oxidation of Cobalt Nanoparticle Films Prepared by Sputter Gas Aggregation

    PubMed Central

    Antón, Ricardo López; González, Juan A.; Andrés, Juan P.; Normile, Peter S.; Canales-Vázquez, Jesús; Muñiz, Pablo; Riveiro, José M.; De Toro, José A.

    2017-01-01

    Porous films of cobalt nanoparticles have been obtained by sputter gas aggregation and controllably oxidized by air annealing at 100 °C for progressively longer times (up to more than 1400 h). The magnetic properties of the samples were monitored during the process, with a focus on the exchange bias field. Air annealing proves to be a convenient way to control the Co/CoO ratio in the samples, allowing the optimization of the exchange bias field to a value above 6 kOe at 5 K. The occurrence of the maximum in the exchange bias field is understood in terms of the density of CoO uncompensated spins and their degree of pinning, with the former reducing and the latter increasing upon the growth of a progressively thicker CoO shell. Vertical shifts exhibited in the magnetization loops are found to correlate qualitatively with the peak in the exchange bias field, while an increase in vertical shift observed for longer oxidation times may be explained by a growing fraction of almost completely oxidized particles. The presence of a hummingbird-like form in magnetization loops can be understood in terms of a combination of hard (biased) and soft (unbiased) components; however, the precise origin of the soft phase is as yet unresolved. PMID:28336895

  9. Modeling the Optimal Heat Transfer Fluidization Velocity in Gas-Fluidized Beds

    NASA Astrophysics Data System (ADS)

    Predey, Thomas; Bougie, Jon; Goltsiker, Aleksandr

    2014-11-01

    Fluidized beds are vital to a wide range of industrial applications and are useful for studying two-phase flow. However, modeling the optimal heat transfer fluidization velocity (OHTFV) in such beds has remained difficult. Previous investigations have commonly taken one of two approaches. One such approach attempts to find a general scaling formula for homogeneous fluidized beds by taking a harmonic average between the terminal and minimum fluidization velocities. Modern approaches using computer simulations and a wide range of parameters are more commonly used in industry today, but are generally concerned with specific applications. We propose a third approach, taking into account the inhomogeneity of the fluidized bed system while limiting the input parameters to gas velocity and particle size. We use this approach to find a general formula for OHTFV that accounts for the collective behavior of the particles rather than focusing on each individual particle in the bed. We then compare this model to previous experimental results. This research is supported by the Loyola Undergraduate Research Opportunities Program.

  10. 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.

  11. Using infrastructure optimization to reduce greenhouse gas emissions from oil sands extraction and processing.

    PubMed

    Middleton, Richard S; Brandt, Adam R

    2013-02-05

    The Alberta oil sands are a significant source of oil production and greenhouse gas emissions, and their importance will grow as the region is poised for decades of growth. We present an integrated framework that simultaneously considers economic and engineering decisions for the capture, transport, and storage of oil sands CO(2) emissions. The model optimizes CO(2) management infrastructure at a variety of carbon prices for the oil sands industry. Our study reveals several key findings. We find that the oil sands industry lends itself well to development of CO(2) trunk lines due to geographic coincidence of sources and sinks. This reduces the relative importance of transport costs compared to nonintegrated transport systems. Also, the amount of managed oil sands CO(2) emissions, and therefore the CCS infrastructure, is very sensitive to the carbon price; significant capture and storage occurs only above 110$/tonne CO(2) in our simulations. Deployment of infrastructure is also sensitive to CO(2) capture decisions and technology, particularly the fraction of capturable CO(2) from oil sands upgrading and steam generation facilities. The framework will help stakeholders and policy makers understand how CCS infrastructure, including an extensive pipeline system, can be safely and cost-effectively deployed.

  12. Optimization and evaluation of fluorescent tracers for flare removal in gas-phase particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Chennaoui, M.; Angarita-Jaimes, D.; Ormsby, M. P.; Angarita-Jaimes, N.; McGhee, E.; Towers, C. E.; Jones, A. C.; Towers, D. P.

    2008-11-01

    We report the development of optimized fluorescent dye-doped tracer particles for gas-phase particle image velocimetry (PIV) and their use to eliminate 'flare' from the images obtained. In such applications, micron-sized tracer particles are normally required to accurately follow the flow. However, as the tracer size is reduced the amount of light incident on the particle diminishes and consequently the intensity of emitted light (fluorescence). Hence, there is a requirement to identify dyes with high quantum yield that can be dissolved in conventional tracer media at high concentrations. We describe the selection and characterization of a highly fluorescent blue-emitting dye, Bis-MSB, using a novel method, employing stabilized micro-emulsions, to emulate the fluorescence properties of tracer particles. We present the results of PIV experiments, using 1 µm tracer particles of o-xylene doped with Bis-MSB, in which elastically scattered 'flare' has been successfully removed from the images using an appropriate optical filter.

  13. Strategies to Optimize Microbially-Mediated Mitigation of Greenhouse Gas Emissions from Landfill Cover Soils

    SciTech Connect

    Jeremy Semrau; Sung-Woo Lee; Jeongdae Im; Sukhwan Yoon; Michael Barcelona

    2010-09-30

    The overall objective of this project, 'Strategies to Optimize Microbially-Mediated Mitigation of Greenhouse Gas Emissions from Landfill Cover Soils' was to develop effective, efficient, and economic methodologies by which microbial production of nitrous oxide can be minimized while also maximizing microbial consumption of methane in landfill cover soils. A combination of laboratory and field site experiments found that the addition of nitrogen and phenylacetylene stimulated in situ methane oxidation while minimizing nitrous oxide production. Molecular analyses also indicated that methane-oxidizing bacteria may play a significant role in not only removing methane, but in nitrous oxide production as well, although the contribution of ammonia-oxidizing archaea to nitrous oxide production can not be excluded at this time. Future efforts to control both methane and nitrous oxide emissions from landfills as well as from other environments (e.g., agricultural soils) should consider these issues. Finally, a methanotrophic biofiltration system was designed and modeled for the promotion of methanotrophic activity in local methane 'hotspots' such as landfills. Model results as well as economic analyses of these biofilters indicate that the use of methanotrophic biofilters for controlling methane emissions is technically feasible, and provided either the costs of biofilter construction and operation are reduced or the value of CO{sub 2} credits is increased, can also be economically attractive.

  14. Optimal timing of same-admission orthotopic heart transplantation after left ventricular assist device implantation

    PubMed Central

    Gulati, Gunsagar; Ouyang, David; Ha, Richard; Banerjee, Dipanjan

    2017-01-01

    AIM To investigate the impact of timing of same-admission orthotopic heart transplant (OHT) after left ventricular assist device (LVAD) implantation on in-hospital mortality and post-transplant length of stay. METHODS Using data from the Nationwide Inpatient Sample from 1998 to 2011, we identified patients 18 years of age or older who underwent implantation of a LVAD and for whom the procedure date was available. We calculated in-hospital mortality for those patients who underwent OHT during the same admission as a function of time from LVAD to OHT, adjusting for age, sex, race, household income, and number of comorbid diagnoses. Finally, we analyzed the effect of time to OHT after LVAD implantation on the length of hospital stay post-transplant. RESULTS Two thousand and two hundred patients underwent implantation of a LVAD in this cohort. One hundred and sixty-four (7.5%) patients also underwent OHT during the same admission, which occurred on average 32 d (IQR 7.75-66 d) after LVAD implantation. Of patients who underwent OHT, patients who underwent transplantation within 7 d of LVAD implantation (“early”) experienced increased in-hospital mortality (26.8% vs 12.2%, P = 0.0483) compared to patients who underwent transplant after 8 d (“late”). There was no statistically significant difference in age, sex, race, household income, or number of comorbid diagnoses between the early and late groups. Post-transplant length of stay after LVAD implantation was also not significantly different between patients who underwent early vs late OHT. CONCLUSION In this cohort of patients who received LVADs, the rate of in-hospital mortality after OHT was lower for patients who underwent late OHT (at least 8 d after LVAD implantation) compared to patients who underwent early OHT. Delayed timing of OHT after LVAD implantation did not correlate with longer hospital stays post-transplant. PMID:28289529

  15. Modeling and optimal design of an optical MEMS tactile sensor for use in robotically assisted surgery

    NASA Astrophysics Data System (ADS)

    Ahmadi, Roozbeh; Kalantari, Masoud; Packirisamy, Muthukumaran; Dargahi, Javad

    2010-06-01

    Currently, Minimally Invasive Surgery (MIS) performs through keyhole incisions using commercially available robotic surgery systems. One of the most famous examples of these robotic surgery systems is the da Vinci surgical system. In the current robotic surgery systems like the da Vinci, surgeons are faced with problems such as lack of tactile feedback during the surgery. Therefore, providing a real-time tactile feedback from interaction between surgical instruments and tissue can help the surgeons to perform MIS more reliably. The present paper proposes an optical tactile sensor to measure the contact force between the bio-tissue and the surgical instrument. A model is proposed for simulating the interaction between a flexible membrane and bio-tissue based on the finite element methods. The tissue is considered as a hyperelastic material with the material properties similar to the heart tissue. The flexible membrane is assumed as a thin layer of silicon which can be microfabricated using the technology of Micro Electro Mechanical Systems (MEMS). The simulation results are used to optimize the geometric design parameters of a proposed MEMS tactile sensor for use in robotic surgical systems to perform MIS.

  16. Tuning to optimize SVM approach for assisting ovarian cancer diagnosis with photoacoustic imaging.

    PubMed

    Wang, Rui; Li, Rui; Lei, Yanyan; Zhu, Quing

    2015-01-01

    Support vector machine (SVM) is one of the most effective classification methods for cancer detection. The efficiency and quality of a SVM classifier depends strongly on several important features and a set of proper parameters. Here, a series of classification analyses, with one set of photoacoustic data from ovarian tissues ex vivo and a widely used breast cancer dataset- the Wisconsin Diagnostic Breast Cancer (WDBC), revealed the different accuracy of a SVM classification in terms of the number of features used and the parameters selected. A pattern recognition system is proposed by means of SVM-Recursive Feature Elimination (RFE) with the Radial Basis Function (RBF) kernel. To improve the effectiveness and robustness of the system, an optimized tuning ensemble algorithm called as SVM-RFE(C) with correlation filter was implemented to quantify feature and parameter information based on cross validation. The proposed algorithm is first demonstrated outperforming SVM-RFE on WDBC. Then the best accuracy of 94.643% and sensitivity of 94.595% were achieved when using SVM-RFE(C) to test 57 new PAT data from 19 patients. The experiment results show that the classifier constructed with SVM-RFE(C) algorithm is able to learn additional information from new data and has significant potential in ovarian cancer diagnosis.

  17. Multi-parameter vital sign database to assist in alarm optimization for general care units.

    PubMed

    Welch, James; Kanter, Benjamin; Skora, Brooke; McCombie, Scott; Henry, Isaac; McCombie, Devin; Kennedy, Rosemary; Soller, Babs

    2016-12-01

    Continual vital sign assessment on the general care, medical-surgical floor is expected to provide early indication of patient deterioration and increase the effectiveness of rapid response teams. However, there is concern that continual, multi-parameter vital sign monitoring will produce alarm fatigue. The objective of this study was the development of a methodology to help care teams optimize alarm settings. An on-body wireless monitoring system was used to continually assess heart rate, respiratory rate, SpO2 and noninvasive blood pressure in the general ward of ten hospitals between April 1, 2014 and January 19, 2015. These data, 94,575 h for 3430 patients are contained in a large database, accessible with cloud computing tools. Simulation scenarios assessed the total alarm rate as a function of threshold and annunciation delay (s). The total alarm rate of ten alarms/patient/day predicted from the cloud-hosted database was the same as the total alarm rate for a 10 day evaluation (1550 h for 36 patients) in an independent hospital. Plots of vital sign distributions in the cloud-hosted database were similar to other large databases published by different authors. The cloud-hosted database can be used to run simulations for various alarm thresholds and annunciation delays to predict the total alarm burden experienced by nursing staff. This methodology might, in the future, be used to help reduce alarm fatigue without sacrificing the ability to continually monitor all vital signs.

  18. Optimization of microwave-assisted transesterification of dry algal biomass using response surface methodology.

    PubMed

    Patil, Prafulla D; Gude, Veera Gnaneswar; Mannarswamy, Aravind; Cooke, Peter; Munson-McGee, Stuart; Nirmalakhandan, Nagamany; Lammers, Peter; Deng, Shuguang

    2011-01-01

    The effect of microwave irradiation on the simultaneous extraction and transesterification (in situ transesterification) of dry algal biomass to biodiesel was investigated. A high degree of oil/lipid extraction from dry algal biomass and an efficient conversion of the oils/lipids to biodiesel were demonstrated in a set of well-designed experimental runs. A response surface methodology (RSM) was used to analyze the influence of the process variables (dry algae to methanol (wt/vol) ratio, catalyst concentration, and reaction time) on the fatty acid methyl ester conversion. Based on the experimental results and RSM analysis, the optimal conditions for this process were determined as: dry algae to methanol (wt/vol) ratio of around 1:12, catalyst concentration about 2 wt.%, and reaction time of 4 min. The algal biodiesel samples were analyzed with GC-MS and thin layer chromatography (TLC) methods. Transmission electron microscopy (TEM) images of the algal biomass samples before and after the extraction/transesterification reaction are also presented.

  19. Scaling of stomatal size and density optimizes allocation of leaf epidermal space for gas exchange in angiosperms

    NASA Astrophysics Data System (ADS)

    de Boer, Hugo Jan; Price, Charles A.; Wagner-Cremer, Friederike; Dekker, Stefan C.; Franks, Peter J.; Veneklaas, Erik J.

    2015-04-01

    Stomata on plant leaves are key traits in the regulation of terrestrial fluxes of water and carbon. The basic morphology of stomata consists of a diffusion pore and two guard cells that regulate the exchange of CO2 and water vapour between the leaf interior and the atmosphere. This morphology is common to nearly all land plants, yet stomatal size (defined as the area of the guard cell pair) and stomatal density (the number of stomata per unit area) range over three orders of magnitude across species. Evolution of stomatal sizes and densities is driven by selection pressure on the anatomical maximum stomatal conductance (gsmax), which determines the operational range of leaf gas exchange. Despite the importance of stomata traits for regulating leaf gas exchange, a quantitative understanding of the relation between adaptation of gsmax and the underlying co-evolution of stomatal sizes and densities is still lacking. Here we develop a theoretical framework for a scaling relationship between stomatal sizes and densities within the constraints set by the allocation of epidermal space and stomatal gas exchange. Our theory predicts an optimal scaling relationship that maximizes gsmax and minimizes epidermal space allocation to stomata. We test whether stomatal sizes and densities reflect this optimal scaling with a global compilation of stomatal trait data on 923 species reflecting most major clades. Our results show optimal scaling between stomatal sizes and densities across all species in the compiled data set. Our results also show optimal stomatal scaling across angiosperm species, but not across gymnosperm and fern species. We propose that the evolutionary flexibility of angiosperms to adjust stomatal sizes underlies their optimal allocation of leaf epidermal space to gas exchange.

  20. Optimization of carbon dioxide supply in raceway reactors: Influence of carbon dioxide molar fraction and gas flow rate.

    PubMed

    Duarte-Santos, T; Mendoza-Martín, J L; Acién Fernández, F G; Molina, E; Vieira-Costa, J A; Heaven, S

    2016-07-01

    Influence of CO2 composition and gas flow rate to control pH in a pilot-scale raceway producing Scenedesmus sp. was studied. Light and temperature determined the biomass productivity whereas neither the CO2 molar fraction nor the gas flow rate used influenced it; because pH was always controlled and carbon limitation did not take place. The CO2 molar fraction and the gas flow rate influenced carbon loss in the system. At low CO2 molar fraction (2-6%) or gas flow rate (75-100l·min(-1)) the carbon efficiency in the sump was higher than 95%, 85% of the injected carbon being transformed into biomass. Conversely, at high CO2 molar fraction (14%) or gas flow rate (150l·min(-1)) the carbon efficiency in the sump was lower than 67%, 32% of the carbon being fixed as biomass. Analysis here reported allows the pH control to be optimized and production costs to be reduced by optimizing CO2 efficiency.

  1. Application of microwave-assisted desorption/headspace solid-phase microextraction as pretreatment step in the gas chromatographic determination of 1-naphthylamine in silica gel adsorbent.

    PubMed

    Yan, Cheing-Tong; Jen, Jen-Fon; Shih, Tung-Sheng

    2007-03-30

    Pretreatment of silica gel sample containing 1-naphthylamine by microwave-assisted desorption (MAD) coupled to in situ headspace solid phase microextraction (HS-SPME) has been investigated as a possible alternative to conventional methods prior to gas chromatographic (GC) analysis. The 1-naphthylamine desorbs from silica gel to headspace under microwave irradiation, and directly absorbs onto a SPME fiber located in a controlled-temperature headspace area. After being collected on the SPME fiber, and desorbed in the GC injection port, 1-naphthylamine is analyzed by GC-FID. Parameters that influence the extraction efficiency of the MAD/HS-SPME, such as the extraction media and its pH, the microwave irradiation power and irradiation time as well as desorption conditions of the GC injector, have been investigated. Experimental results indicate that the extraction of a 150mg silica gel sample by using 0.8ml of 1.0M NaOH solution and a PDMS/DVB fiber under high-powered irradiation (477W) for 5min maximizes the extraction efficiency. Desorption of 1-naphthylamine from the SPME fiber in GC injector is optimal at 250 degrees C held for 3min. The detection limit of method is 8.30ng. The detected quantity of 1-naphthylamine obtained by the proposed method is 33.3 times of that obtained by the conventional solvent extraction method for the silica gel sample containing 100ng of 1-naphthylamine. It provides a simple, fast, sensitive and organic-solvent-free pretreatment procedure prior to the analysis of 1-naphthylamine collected on a silica gel adsorbent.

  2. Hybrid field-assisted solid-liquid-solid dispersive extraction for the determination of organochlorine pesticides in tobacco with gas chromatography.

    PubMed

    Zhou, Ting; Xiao, Xiaohua; Li, Gongke

    2012-01-03

    A novel one-step sample preparation technique termed hybrid field-assisted solid-liquid-solid dispersive extraction (HF-SLSDE) was developed in this study. A simple glass system equipped with a condenser was designed as an extraction vessel. The HF-SLSDE technique was a three-phase dispersive extraction approach. Target analytes were extracted from the sample into the extraction solvent enhanced by the hybrid field. Meanwhile, the interfering components were adsorbed by dispersing sorbent. No cleanup step preceded chromatographic analysis. The efficiency of the HF-SLSDE approach was demonstrated in the determination of organochlorine pesticide (OCP) residues in tobacco with a gas chromatography-electron capture detector (GC-ECD). Various operation conditions were studied systematically. Low detection limits (0.3-1.6 μg/kg) and low quantification limits (1.0-4.5 μg/kg) were achieved under the optimized conditions. The recoveries of OCPs ranged from 70.2% to 118.2%, with relative standard deviations of <9.6%, except for the lowest fortification level. Because of the effect of the hybrid field, HF-SLSDE showed significant predominance compared with other extraction techniques. The dispersing sorbent with good cleanup ability used in this study was also found to be a microwave absorption medium, which could heat the nonpolar extraction solvent under microwave irradiation. Different microstructures of tobacco samples before and after extractions demonstrated the mechanism of HF-SLSDE was based on an explosion at the cell level. According to the results, HF-SLSDE was proved to be a simple and effective sample preparation method for the analysis of pesticide residues in solid samples and could potentially be extended to other nonpolar target analytes in a complex matrix.

  3. Chemometric-based determination of polycyclic aromatic hydrocarbons in aqueous samples using ultrasound-assisted emulsification microextraction combined to gas chromatography-mass spectrometry.

    PubMed

    Ahmadvand, Mohammad; Sereshti, Hassan; Parastar, Hadi

    2015-09-25

    In the present research, ultrasonic-assisted emulsification-microextraction (USAEME) coupled with gas chromatography-mass spectrometry (GC-MS) has been proposed for analysis of thirteen environmental protection agency (EPA) polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. Tetrachloroethylene was selected as extraction solvent. The main parameters of USAEME affecting the efficiency of the method were modeled and optimized using a central composite design (CCD). Under the optimum conditions (9μL for extraction solvent, 1.15% (w/v) NaCl (salt concentration) and 10min for ultrasonication time), preconcentration factor (PF) of the PAHs was in the range of 500-950. In order to have a comprehensive analysis, multivariate curve resolution-alternating least squares (MCR-ALS) as a second-order calibration algorithm was used for resolution, identification and quantification of the target PAHs in the presence of uncalibrated interferences. The regression coefficients and relative errors (REs, %) of calibration curves of the PAHs were in the satisfactory range of 0.9971-0.9999 and 1.17-6.59%, respectively. Furthermore, analytical figures of merit (AFOM) for univariate and second-order calibrations were obtained and compared. As an instance, the limit of detections (LODs) of target PAHs were in the range of 1.87-18.9 and 0.89-6.49ngmL(-1) for univariate and second-order calibration, respectively. Finally, the proposed strategy was used for determination of target PAHs in real water samples (tap and hookah waters). The relative recoveries (RR) and the relative standard deviations (RSDs) were 68.4-109.80% and 2.15-6.93%, respectively. It was concluded that combination of multivariate chemometric methods with USAEME-GC-MS can be considered as a new insight for the analysis of target analytes in complex sample matrices.

  4. Emergency ambulance assistance in The Netherlands: is the Dutch situation optimal?

    PubMed

    van Vugt, A B; van Olden, G D; Edwards, M J

    1995-12-01

    The system of prehospital trauma care in the Netherlands is the subject of great concern. Although many improvements have been achieved in the last decade, there are still some deficits. Legislation concerning the minimal level of education for ambulance attendants was recently upgraded to 'registered nurse', a standard which must be achieved by 1997. Standardization with regard to extrication techniques, equipment and methods of treatment in prehospital trauma care does not yet exist. Although aware of the fact that large regional differences exist throughout the USA, a system of care in accordance with the advanced trauma life support (ATLS) standard of the American College of Surgeons (ACS) and by means of prehospital and advanced trauma life support (PHTLS) given according to the standards of the National Association of Emergency Medical Technicians (NAEMS) was considered to be the 'golden standard'. Nineteen ground ambulance and two helicopter services in different states of the USA, working according to ACS/NAEMS standard, were visited to analyse the system of care, with special reference to (para)medical education, communication, logistics, and immobilization materials and techniques. In the Netherlands all 41 central post ambulance services (CPAs) were asked to return a questionnaire. This resulted in a 90% (37 out of 41) response. The deficits of the Dutch system of care related to the PHTLS/ATLS standard are pointed out, resulting in recommendations to improve the Dutch system. The requirements of the dispatcher are far inferior to the optimal situation, which, together with the lack of technical equipment, results in serious communication problems. The Dutch ambulance attendant education, in which in the present system the education level reaches 'registered nurse' in only 91% and specialized courses are not mandatory, should be upgraded to the PHTLS level of care.

  5. Bell-shaped extraction device assisted liquid-liquid microextraction technique and its optimization using response-surface methodology.

    PubMed

    Čabala, Radomír; Bursová, Miroslava

    2012-03-23

    We have developed a new microextraction technique for equilibrium, non-exhaustive analyte preconcentration from aqueous solutions into organic solvents lighter than water. The key point of the method is application of specially designed and optimized bell-shaped extraction device, BSED. The technique has been tested and applied to the preconcentration of selected volatile and semi volatile compounds which were determined by gas chromatography/mass spectrometry in spiked water samples. The significant parameters of the extraction have been found using chemometric procedures and these parameters were optimized using the central composite design (CCD) for two solvents. The analyte preconcentration factors were in a range from 8.3 to 161.8 (repeatability from 7 to 14%) for heptane, and 50.0-105.0 (repeatability from 0 to 5%) for tert-butyl acetate. The reproducibility of the technique was within 1-8%. The values of limits of detection and determination were 0.1-3.3 ng mL(-1) for heptane and 0.3-10.7 ng mL(-1) for tert-butyl acetate. The new microextraction technique has been found to be a cheap, simple and flexible alternative to the common procedures, such as SPME or LLME. This BSED-LLME technique can also be combined with other separation methods, e.g., HPLC or CE.

  6. Virtual Pipeline System Testbed to Optimize the U.S. Natural Gas Transmission Pipeline System

    SciTech Connect

    Kirby S. Chapman; Prakash Krishniswami; Virg Wallentine; Mohammed Abbaspour; Revathi Ranganathan; Ravi Addanki; Jeet Sengupta; Liubo Chen

    2005-06-01

    The goal of this project is to develop a Virtual Pipeline System Testbed (VPST) for natural gas transmission. This study uses a fully implicit finite difference method to analyze transient, nonisothermal compressible gas flow through a gas pipeline system. The inertia term of the momentum equation is included in the analysis. The testbed simulate compressor stations, the pipe that connects these compressor stations, the supply sources, and the end-user demand markets. The compressor station is described by identifying the make, model, and number of engines, gas turbines, and compressors. System operators and engineers can analyze the impact of system changes on the dynamic deliverability of gas and on the environment.

  7. The performance optimization of a gas turbine cogeneration/heat pump facility with thermal storage

    SciTech Connect

    Spakovsky, M.R. von; Curti, V.; Batato, M.

    1995-01-01

    With the push for greater energy conservation, the need for heating and/or power production is being filled by cogeneration facilities. Thus, the search for the best performance at the least cost for such multipurpose plants is made much more difficult by the fact that such facilities must meet differing goals or demands. Such a facility exists at the Ecole Polytechnique Federale de Lausanne (EPFL) and has been studied in order to find the optimum modes of operation as a function of time for variations in both the heating and electrical demands this facility must meet. The results of this study are presented here. The plant itself provides heat and electricity for both the EPFL and the University of Lausanne and is projected to supply electricity to the exterior utility grid provided it can be shown to be economically viable. The plant`s primary components include two gas turbines, a heat recovery system, two heat pumps, a set of heat storage tanks, and both medium and low-temperature district heating networks. In order to find the optimum mode of operation, a mixed-integer linear programming approach was used, which balances the competing costs of operation and minimizes these costs subject to the operational constraints placed on the system. The effects of both the cost of the fuel and the costs of electricity sold and bought on the best performance of the system are evaluated. In addition, the important features of the modeling process are discussed, in particular the heat storage tanks, which complicate the optimization of the series of steady-state models used to model the overall quasi-steady-state behavior of the system.

  8. Reaction chemistry and optimization of plasma remediation of NxOy from gas streams

    NASA Astrophysics Data System (ADS)

    Gentile, Ann C.; Kushner, Mark J.

    1995-08-01

    Increasing environmental awareness and regulatory pressure have motivated investigations into energy efficient methods to remove oxides of nitrogen (NxOy) from gas streams resulting from the combustion of fossil fuels. Plasma remediation of NxOy is potentially an efficient removal technique due to the relative ease of generating reactants by electron-impact processes. Previous works have investigated the use of electron-beam, corona, and dielectric barrier discharge (DBD) generated plasmas for this purpose. In those works, reduction (N+NO→N2+O) and oxidation (NO2+OH→HNO3) reactions were identified as major removal channels. A computational study of the plasma remediation of NxOy from humid air using repetitively pulsed DBDs is reported. The dominant reaction pathways are discussed and scaling laws are proposed to optimize the energy efficiency of removal. Three reaction periods are identified: the current pulse (during which electron-impact processes generate radicals), the postpulse remediative period (during which NxOy is removed), and the interpulse period (during which the densities of various nitrogen oxides are reapportioned with little net removal). The lifetimes of reactants (OH and O3 in particular) determine the length of these periods and hence the optimum repetition frequency. Optimum repetition rates are typically less than hundreds of Hz. It is also found that a larger number of current pulses producing less energy deposition per pulse results in a higher removal efficiency due to reduced competition from radical-radical reactions which deplete the reactants. The production of unwanted species (e.g., O3 and N2O) can be minimized by reducing or terminating power deposition when the densities NO and NO2 have been reduced to ppm levels. The energy efficiency of remediation generally increases with increasing water content by removing NOx through the oxidation channel, although at the price of producing an acidic end product.

  9. Microwave-assisted extraction followed by headspace solid-phase microextraction and gas chromatography with mass spectrometry detection (MAE-HSSPME-GC-MS/MS) for determination of polybrominated compounds in aquaculture samples.

    PubMed

    Carro, A M; Lorenzo, R A; Fernández, F; Phan-Tan-Luu, R; Cela, R

    2007-07-01

    This paper describes the first validated method for the extraction, purification and determination of trace levels of a number of pollutants of growing concern, including polybrominated biphenyls (PBBs) and polybrominated diphenyl ethers (PBDEs), in aquaculture feeds and products. The new procedure comprises microwave-assisted extraction (MAE; optimized, using a central composite experimental design, to 15 min at 85 degrees C in 14 mL of 1:1 hexane/dichloromethane), and concentration by headspace solid-phase microextraction (HSSPME), and separation/quantification by gas chromatography with mass spectrometry detection (GC-MS/MS). The method was validated on the reference materials IAEA-406 and WMF-01. Limits of detection for fourteen of the fifteen analytes considered range from 10 to 600 pg g(-1), and limits of quantification from 50 pg g(-1) to 1.9 ng g(-1). Linear ranges, accuracies and precisions are reported.

  10. Ultrasound-assisted dispersive liquid-liquid microextraction based on the solidification of a floating organic droplet followed by gas chromatography for the determination of eight pyrethroid pesticides in tea samples.

    PubMed

    Hou, Xiaohong; Zheng, Xin; Zhang, Conglu; Ma, Xiaowei; Ling, Qiyuan; Zhao, Longshan

    2014-10-15

    A novel ultrasound-assisted dispersive liquid-liquid microextraction based on solidification of floating organic droplet method (UA-DLLME-SFO) combined with gas chromatography (GC) was developed for the determination of eight pyrethroid pesticides in tea for the first time. After ultrasound and centrifugation, 1-dodecanol and ethanol was used as the extraction and dispersive solvent, respectively. A series of parameters, including extraction solvent and volume, dispersive solvent and volume, extraction time, pH, and ultrasonic time influencing the microextraction efficiency were systematically investigated. Under the optimal conditions, the enrichment factors (EFs) were from 292 to 883 for the eight analytes. The linear ranges for the analytes were from 5 to 100μg/kg. The method recoveries ranged from 92.1% to 99.6%, with the corresponding RSDs less than 6.0%. The developed method was considered to be simple, fast, and precise to satisfy the requirements of the residual analysis of pyrethroid pesticides.

  11. Simultaneous derivatization and ultrasound-assisted dispersive liquid-liquid microextraction of chloropropanols in soy milk and other aqueous matrices combined with gas-chromatography-mass spectrometry.

    PubMed

    Carro, A M; González, P; Lorenzo, R A

    2013-12-06

    A novel approach involving ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) and derivatization combined with gas chromatography-mass spectrometry was developed for the determination of chloropropanols in water and beverages. UA-DLLME was optimized as less solvent-consuming and cost-effective extraction method for water, fruit juice, milk and soy milk samples. The effect of parameters such as the type and volume of extraction solvent, the type and volume of dispersive solvent, amount of derivatization agent, temperature, pH of sample and ionic strength was investigated and optimized for each specimen, using experimental designs. By adding acetonitrile as dispersive solvent, N-heptafluorobutyrylimizadole (HFBI) as derivatization agent and chloroform as extraction solvent, the extraction-derivatization and preconcentration were simultaneously performed. The analytical concentration range was investigated in detail for each analyte in the different samples, obtaining linearity with R(2) ranging between 0.9990 and 0.9999. The method detection limits were in the range of 0.2-1.8μgL(-1) (water), 0.5-15μgL(-1) (fruit juices) and 0.9-3.6μgkg(-1) (milk) and 0.1-1.0μgkg(-1) (soy milk). The method was applied to the analysis of a variety of specimens, with recoveries of 98-101% from water, 97-102% from juices, 99-103% from milk and 97-105% from soy beverage. The relative standard deviation (precision, n=6) varied between 1.3 and 4.9%RSD in water, 2.3 and 5.8%RSD in juices, 1.0 and 5.7%RSD in milk and 3.9 and 9.3%RSD in soy milk. The proposed method was applied to analysis of twenty-eight samples. 1,3-Dichloro-2-propanol was found in an influent water sample from urban wastewater treatment plant (WWTP) (2.1±0.04mgL(-1)) but no chloropropanols were found in the corresponding effluent water sample. This result suggests that the purification system used in the WWTP has been effective for this compound. Moreover, the results revealed the presence of 3

  12. A Time-Regularized Multiple Gravity-Assist Low-Thrust Bounded-Impulse Model for Trajectory Optimization

    NASA Technical Reports Server (NTRS)

    Ellison, Donald H.; Englander, Jacob A.; Conway, Bruce A.

    2017-01-01

    The multiple gravity assist low-thrust (MGALT) trajectory model combines the medium-fidelity Sims-Flanagan bounded-impulse transcription with a patched-conics flyby model and is an important tool for preliminary trajectory design. While this model features fast state propagation via Kepler's equation and provides a pleasingly accurate estimation of the total mass budget for the eventual flight-suitable integrated trajectory it does suffer from one major drawback, namely its temporal spacing of the control nodes. We introduce a variant of the MGALT transcription that utilizes the generalized anomaly from the universal formulation of Kepler's equation as a decision variable in addition to the trajectory phase propagation time. This results in two improvements over the traditional model. The first is that the maneuver locations are equally spaced in generalized anomaly about the orbit rather than time. The second is that the Kepler propagator now has the generalized anomaly as its independent variable instead of time and thus becomes an iteration-free propagation method. The new algorithm is outlined, including the impact that this has on the computation of Jacobian entries for numerical optimization, and a motivating application problem is presented that illustrates the improvements that this model has over the traditional MGALT transcription.

  13. A Time-Regularized, Multiple Gravity-Assist Low-Thrust, Bounded-Impulse Model for Trajectory Optimization

    NASA Technical Reports Server (NTRS)

    Ellison, Donald H.; Englander, Jacob A.; Conway, Bruce A.

    2017-01-01

    The multiple gravity assist low-thrust (MGALT) trajectory model combines the medium-fidelity Sims-Flanagan bounded-impulse transcription with a patched-conics flyby model and is an important tool for preliminary trajectory design. While this model features fast state propagation via Keplers equation and provides a pleasingly accurate estimation of the total mass budget for the eventual flight suitable integrated trajectory it does suffer from one major drawback, namely its temporal spacing of the control nodes. We introduce a variant of the MGALT transcription that utilizes the generalized anomaly from the universal formulation of Keplers equation as a decision variable in addition to the trajectory phase propagation time. This results in two improvements over the traditional model. The first is that the maneuver locations are equally spaced in generalized anomaly about the orbit rather than time. The second is that the Kepler propagator now has the generalized anomaly as its independent variable instead of time and thus becomes an iteration-free propagation method. The new algorithm is outlined, including the impact that this has on the computation of Jacobian entries for numerical optimization, and a motivating application problem is presented that illustrates the improvements that this model has over the traditional MGALT transcription.

  14. Sequential microwave-assisted ultra-fast ZnO nanorod growth on optimized sol-gel seedlayers

    NASA Astrophysics Data System (ADS)

    Soleimanzadeh, Reza; Mousavi, Matin Sadat Saneei; Mehrfar, Amin; Esfahani, Zahra Kolahdouz; Kolahdouz, Mohammadreza; Zhang, Kouchi

    2015-09-01

    Recently, the studies on ZnO nanostructure characteristics and their fabrication methods have been increased significantly in order to be able to use its magnificent properties by reaching the desired optimum features. Very high growth rate and high quality growth have always been the center of attention. In this study, a sequential microwave-assisted ZnO nanorod (NR) growth as an ultra-fast, highly efficient method for vertical growth of high quality ZnO NRs on different substrates is proposed. A NRs' growth rate of 4.2 μm/h was obtained which led to uniformly distributed, high aspect ratio and vertically-aligned NRs. Furthermore, the influences of spinner's speed as an important parameter on the quality of ZnO seed and annealing treatment have been studied. The sol-gel casting approach is optimized for the layer. Different seed layers were used to grow the nanostructures and the optimum spinner speed is found to be 2000 rpm. In order to diminish the dependency of the uniformity of ZnO NRs on the quality of seed layers, a remedy is suggested.

  15. Optimization of ultrasonic-assisted acid extraction of mercury in muscle tissues of fishes using multivariate strategy.

    PubMed

    Shah, Abdul Q; Kazii, Tasneem G; Arain, Mohammad B; Baig, Jameel A; Afridi, Hassan I; Jamali, Mohammad K; Jalbani, Nusrat; Kandhro, Ghulam A

    2009-01-01

    A simple and rapid ultrasound-assisted extraction procedure was developed for the determination of total mercury (Hg) in muscle tissues of freshwater fish species. A Plackett-Burman experimental design was used as a multivariate strategy for the evaluation of the effects of variables, such as presonication time (without ultrasonic stirring), sonication time, ultrasonic bath temperature, nitric acid concentration, hydrochloric acid concentration, and sample mass of muscle tissues. Some variables showed a significant effect on recovery, and they were further optimized by a 2(3) + star central composite design that involved 16 experiments. The validation was carried out by analysis of certified reference material DORM-2 (dog fish muscles); for comparative purposes, an acid digestion induced by microwave energy was used. Cold vapor atomic absorption spectrometry was used for the determination of total Hg. No significant differences were established between the analytical results and the certified values (paired t-test at P > 0.05). The LOD and LOQ of Hg were 0.133 and 0.445 microg/kg, respectively, which demonstrated the high sensitivity of the proposed procedure for the determination of Hg at trace levels. The Hg concentrations in the muscle tissues of 10 freshwater fish species were found in the range of 35.3-67.8 microg/kg on a dried basis, which were within the permissible limit of the World Health Organization.

  16. Entransy analysis and optimization of performance of nano-scale irreversible Otto cycle operating with Maxwell-Boltzmann ideal gas

    NASA Astrophysics Data System (ADS)

    Ahmadi, Mohammad H.; Ahmadi, Mohammad Ali; Pourfayaz, Fathollah; Bidi, Mokhtar

    2016-08-01

    This paper made attempt to investigate thermodynamically a nano scale irreversible Otto cycle for optimizing its performance. This system employed an ideal Maxwell-Boltzmann gas as a working fluid. Two different scenarios were proposed in the multi-objective optimization process and the results of each of the scenarios were examined separately. The first scenario made attempt to maximize the dimensionless ecological function and minimize the dimensionless entransy dissipation of the system. Furthermore, the second scenario tried to maximize the ecological coefficient of performance and minimize the dimensionless entransy dissipation of the system. The multi objective evolutionary method integrated with non-dominated sorting genetic algorithm was used to optimize the proposed objective functions. To determine the final output of each scenario, three efficient decision makers were employed. Finally, error analysis was employed to determine the deviation of solutions chosen by decision makers.

  17. Gas Turbine Heavy Hybrid Powertrain Variants. Opportunities and Potential for Systems Optimization

    SciTech Connect

    Smith, David; Chambon, Paul H.

    2015-07-01

    Widespread use of alternative hybrid powertrains is currently inevitable, and many opportunities for substantial progress remain. Hybrid electric vehicles (HEVs) have attracted considerable attention due to their potential to reduce petroleum consumption and greenhouse gas emissions in the transportation sector. This capability is mainly attributed to (a) the potential for downsizing the engine, (b) the potential for recovering energy during braking and thus recharging the energy storage unit, and (c) the ability to minimize the operation of the engine outside of its most efficient brake specific fuel consumption (BSFC) regime. Hybridization of the Class 8, heavy-duty (HD) powertrain is inherently challenging due to the expected long-haul driving requirements and limited opportunities for regenerative braking. The objective of this project is to develop control strategies aiming at optimizing the operation of a Class 8 HEV that features a micro-turbine as the heat engine. The micro-turbine application shows promise in fuel efficiency, even when compared to current diesel engines, and can meet regulated exhaust emissions levels with no exhaust after-treatment system. Both parallel and series HEV variants will be examined to understand the merits of each approach of the micro-turbine to MD advanced powertrain applications. These powertrain configurations enable new paradigms in operational efficiency, particularly in the Class 8 truck fleet. The successful development of these HEV variants will require a thorough technical understanding of the complex interactions between various energy sources and energy consumption components, for various operating modes. PACCAR will be integrating the first generation of their series HEV powertrain with a Brayton Energy micro-turbine into a Class 8 HD truck tractor that has both regional haul and local pick-up and delivery (P&D) components to its drive cycle. The vehicle will be deployed into fleet operation for a demonstration

  18. Optimal water resources management and system benefit for the Marcellus shale-gas reservoir in Pennsylvania and West Virginia

    NASA Astrophysics Data System (ADS)

    Cheng, Xi; He, Li; Lu, Hongwei; Chen, Yizhong; Ren, Lixia

    2016-09-01

    A major concern associated with current shale-gas extraction is high consumption of water resources. However, decision-making problems regarding water consumption and shale-gas extraction have not yet been solved through systematic approaches. This study develops a new bilevel optimization problem based on goals at two different levels: minimization of water demands at the lower level and maximization of system benefit at the upper level. The model is used to solve a real-world case across Pennsylvania and West Virginia. Results show that surface water would be the largest contributor to gas production (with over 80.00% from 2015 to 2030) and groundwater occupies for the least proportion (with less than 2.00% from 2015 to 2030) in both districts over the planning span. Comparative analysis between the proposed model and conventional single-level models indicates that the bilevel model could provide coordinated schemes to comprehensively attain the goals from both water resources authorities and energy sectors. Sensitivity analysis shows that the change of water use of per unit gas production (WU) has significant effects upon system benefit, gas production and pollutants (i.e., barium, chloride and bromide) discharge, but not significantly changes water demands.

  19. OPTIMIZING SYNTHESIS GAS YIELD FROM THE CROSS DRAFT GASIFICATION OF WOODY BIOMASS

    EPA Science Inventory

    Biomass can be gasified to yield synthesis gas, tars, and ash. The process is governed by a number of parameters such as the temperature of the gasifying medium (in this case air), and the moisture content of the feedstock. Synthesis gas from gasifying wood pellets was collected ...

  20. Optimal sensor locations for the backward Lagrangian stochastic technique in measuring lagoon gas emission

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the impact of gas concentration and wind sensor locations on the accuracy of the backward Lagrangian stochastic inverse-dispersion technique (bLS) for measuring gas emission rates from a typical lagoon environment. Path-integrated concentrations (PICs) and 3-dimensional (3D) wi...

  1. Ultrasonic assisted formation and stability of mustard oil in water nanoemulsion: Effect of process parameters and their optimization.

    PubMed

    Carpenter, Jitendra; Saharan, Virendra Kumar

    2017-03-01

    The present work reports the ultrasound assisted preparation of mustard oil in water nanoemulsion stabilized by Span 80 and Tween 80 at different operating conditions. Effects of various operating parameters such as HLB (Hydrophilic Lipophilic Balance) value, surfactant volume fraction (φS), oil volume fraction (φO) and power amplitude were investigated and optimized on the basis of droplet size and stability of nanoemulsions. It was observed that minimum droplet size of about 87.38nm was obtained within 30min of ultrasonication at an optimum HLB value of 10, φS of 0.08 (8%, v/v), φO of 0.1 (10%, v/v) and ultrasonic power amplitude of 40%. The stability of the nanoemulsion was measured through visual observation and it was found that the unstable emulsions got separated within 24h whereas, stable emulsions never showed any separation until 90days. In addition to that, the kinetic stability of the prepared nanoemulsions was also assessed under centrifuge and thermal stress conditions. The emulsion stability was found to be unaffected by these forces as the droplet size remained unchanged. The ultrasound prepared emulsion was found to be long term stable even after 3months of storage at ambient conditions without any visual evidence of creaming and phase separation and also remained kinetically stable. FTIR analysis of the emulsions at different sonication conditions was carried out to examine the possible impact of ultrasonically induced chemical effects on oil structure during emulsification and it was found that the oil molecular structure was unaffected by ultrasonication process. The present work illustrates the formation and stability of mustard oil in water nanoemulsion using ultrasound cavitation which may be useful in food and cosmetic based applications.

  2. Assessment and optimization of an ultrasound-assisted washing process using organic solvents for polychlorinated biphenyl-contaminated soil.

    PubMed

    Bezama, Alberto; Flores, Alejandra; Araneda, Alberto; Barra, Ricardo; Pereira, Eduardo; Hernández, Víctor; Moya, Heriberto; Konrad, Odorico; Quiroz, Roberto

    2013-10-01

    The goal of this work was to evaluate a washing process that uses organic solutions for polychlorinated biphenyl (PCB)-contaminated soil, and includes an ultrasound pre-treatment step to reduce operational times and organic solvent losses. In a preliminary trial, the suitability of 10 washing solutions of different polarities were tested, from which three n-hexane-based solutions were selected for further evaluation. A second set of experiments was designed using a three-level Taguchi L27 orthogonal array to model the desorption processes of seven different PCB congeners in terms of the variability of their PCB concentration levels, polarity of the washing solution, sonication time, the ratio washing solution/soil, number of extraction steps and total washing time. Linear models were developed for the desorption processes of all congeners. These models provide a good fit with the results obtained. Moreover, statistically significant outcomes were achieved from the analysis of variance tests carried out. It was determined that sonication time and ratio of washing solution/soil were the most influential process parameters. For this reason they were studied in a third set of experiments, constructed as a full factorial design. The process was eventually optimized, achieving desorption rates of more than 90% for all congeners, thus obtaining concentrations lower than 5 ppb in all cases. The use of an ultrasound-assisted soil washing process for PCB-contaminated soils that uses organic solvents seems therefore to be a viable option, especially with the incorporation of an extra step in the sonication process relating to temperature control, which is intended to prevent the loss of the lighter congeners.

  3. Development of micro-heaters with optimized temperature compensation design for gas sensors.

    PubMed

    Hwang, Woo-Jin; Shin, Kyu-Sik; Roh, Ji-Hyoung; Lee, Dae-Sung; Choa, Sung-Hoon

    2011-01-01

    One of the key components of a chemical gas sensor is a MEMS micro-heater. Micro-heaters are used in both semiconductor gas sensors and NDIR gas sensors; however they each require different heat dissipation characteristics. For the semiconductor gas sensors, a uniform temperature is required over a wide area of the heater. On the other hand, for the NDIR gas sensor, the micro-heater needs high levels of infrared radiation in order to increase sensitivity. In this study, a novel design of a poly-Si micro-heater is proposed to improve the uniformity of heat dissipation on the heating plate. Temperature uniformity of the micro-heater is achieved by compensating for the variation in power consumption around the perimeter of the heater. With the power compensated design, the uniform heating area is increased by 2.5 times and the average temperature goes up by 40 °C. Therefore, this power compensated micro-heater design is suitable for a semiconductor gas sensor. Meanwhile, the poly-Si micro-heater without compensation shows a higher level of infrared radiation under equal power consumption conditions. This indicates that the micro-heater without compensation is more suitable for a NDIR gas sensor. Furthermore, the micro-heater shows a short response time of less than 20 ms, indicating a very high efficiency of pulse driving.

  4. Naturally fractured tight gas reservoir detection optimization. Quarterly report, January--March 1995

    SciTech Connect

    1995-05-01

    This report describes progress in the following five projects: (1) Geologic assessment of the Piceance Basin; (2) Regional stratigraphic studies, Upper Cretaceous Mesaverde Group, southern Piceance Basin, Colorado; (3) Structurally controlled and aligned tight gas reservoir compartmentalization in the San Juan and Piceance Basins--Foundation for a new approach to exploration and resource assessments of continuous type deposits; (4) Delineation of Piceance Basin basement structures using multiple source data--Implications for fractured reservoir exploration; and (5) Gas and water-saturated conditions in the Piceance Basin, western Colorado--Implications for fractured reservoir detection in a gas-centered coal basin.

  5. Optimization of a PGSS (particles from gas saturated solutions) process for a fenofibrate lipid-based solid dispersion formulation.

    PubMed

    Pestieau, Aude; Krier, Fabrice; Lebrun, Pierre; Brouwers, Adeline; Streel, Bruno; Evrard, Brigitte

    2015-05-15

    The aim of this study was to develop a formulation containing fenofibrate and Gelucire(®) 50/13 (Gattefossé, France) in order to improve the oral bioavailability of the drug. Particles from gas saturated solutions (PGSS) process was chosen for investigation as a manufacturing process for producing a solid dispersion. The PGSS process was optimized according to the in vitro drug dissolution profile obtained using a biphasic dissolution test. Using a design of experiments approach, the effects of nine experimental parameters were investigated using a PGSS apparatus provided by Separex(®) (Champigneulles, France). Within the chosen experimental conditions, the screening results showed that the drug loading level, the autoclave temperature and pressure, the connection temperature and the nozzle diameter had a significant influence on the dissolution profile of fenofibrate. During the optimization step, the three most relevant parameters were optimized using a central composite design, while other factors remained fixed. In this way, we were able to identify the optimal production conditions that would deliver the highest level of fenofibrate in the organic phase at the end of the dissolution test. The closeness between the measured and the predicted optimal dissolution profiles in the organic phase demonstrated the validity of the statistical analyses.

  6. Design and optimization of a gas-puff nozzle for staged Z-pinch experiments using computational fluid dynamics simulations

    NASA Astrophysics Data System (ADS)

    Valenzuela, J. C.; Krasheninnikov, I.; Beg, F. N.; Wessel, F.; Rahman, H.; Ney, P.; Presura, R.; McKee, E.; Darling, T.; Covington, A.

    2015-11-01

    Previous experimental work on staged Z-pinches demonstrated that gas liners can efficiently couple energy and implode uniformly a target-plasma. A 1.5 MA, 1 μs current driver was used to implode a magnetized, Kr liner onto a D + target, producing 1010 neutrons per shot and providing clear evidence of enhanced pinch stability. Time-of-flight data suggest that primary and secondary neutrons were produced. MHD simulations show that in Zebra, a 1.5MA and 100ns rise-time current driver, high fusion gain can be attained when the optimum liner and plasma target conditions are used. In this work we present the design and optimization of a liner-on-target nozzle to be fielded in Zebra and demonstrate high fusion gain at 1 MA current level. The nozzle is composed of an annular high atomic number gas-puff and an on-axis plasma gun that will deliver the ionized deuterium target. The nozzle optimization was carried out using the computational fluid dynamics (CFD) code fluent and the MHD code Mach2. The CFD simulation produces density and temperature profiles, as a function of the nozzle shapes and gas conditions, which are then used in Mach2 to find the optimum plasma liner implosion-pinch conditions. Funded by the US Department of Energy, ARPA-E, Control Number 1184-1527.

  7. An experimental design approach for optimizing polycyclic aromatic hydrocarbon analysis in contaminated soil by pyrolyser-gas chromatography-mass spectrometry.

    PubMed

    Buco, S; Moragues, M; Sergent, M; Doumenq, P; Mille, G

    2007-06-01

    Pyrolyser-gas chromatography-mass spectrometry was used to analyze polycyclic aromatic hydrocarbons in contaminated soil without preliminary extraction. Experimental research methodology was used to obtain optimal performance of the system. After determination of the main factors (desorption time, Curie point temperature, carrier gas flow), modeling was done using a Box-Behnken matrix. Study of the response surface led to factor values that optimize the experimental response and achieve better chromatographic results.

  8. Optimization of ultrasound-assisted extraction of pectinase enzyme from guava (Psidium guajava) peel: Enzyme recovery, specific activity, temperature, and storage stability.

    PubMed

    Amid, Mehrnoush; Murshid, Fara Syazana; Manap, Mohd Yazid; Islam Sarker, Zaidul

    2016-01-01

    This study aimed to investigate the effects of the ultrasound-assisted extraction conditions on the yield, specific activity, temperature, and storage stability of the pectinase enzyme from guava peel. The ultrasound variables studied were sonication time (10-30 min), ultrasound temperature (30-50 °C), pH (2.0-8.0), and solvent-to-sample ratio (2:1 mL/g to 6:1 mL/g). The main goal was to optimize the ultrasound-assisted extraction conditions to maximize the recovery of pectinase from guava peel with the most desirable enzyme-specific activity and stability. Under the optimum conditions, a high yield (96.2%), good specific activity (18.2 U/mg), temperature stability (88.3%), and storage stability (90.3%) of the extracted enzyme were achieved. The optimal conditions were 20 min sonication time, 40 °C temperature, at pH 5.0, using a 4:1 mL/g solvent-to-sample ratio. The study demonstrated that optimization of ultrasound-assisted process conditions for the enzyme extraction could improve the enzymatic characteristics and yield of the enzyme.

  9. Metallographic structure, mechanical properties, and process parameter optimization of 5A06 joints formed by ultrasonic-assisted refill friction stir spot welding

    NASA Astrophysics Data System (ADS)

    Liu, Xin-bo; Qiao, Feng-bin; Guo, Li-jie; Qiu, Xiong-er

    2017-02-01

    Novel hybrid refill friction stir spot welding (RFSSW) assisted with ultrasonic oscillation was introduced to 5A06 aluminum alloy joints. The metallographic structure and mechanical properties of 5A06 aluminum alloy RFSSW joints formed without ultrasonic assistance and with lateral and longitudinal ultrasonic assistance were compared, and the ultrasonic-assisted RFSSW process parameters were optimized. The results show that compared with lateral ultrasonic oscillation, longitudinal ultrasonic oscillation strengthens the horizontal bonding ligament in the joint and has a stronger effect on the joint's shear strength. By contrast, lateral ultrasonic oscillation strengthens the vertical bonding ligament and is more effective in increasing the joint's tensile strength. The maximum shear strength of ultrasonic-assisted RFSSW 5A06 aluminum alloy joints is as high as 8761 N, and the maximum tensile strength is 3679 N when the joints are formed at a tool rotating speed of 2000 r/min, a welding time of 3.5 s, a penetration depth of 0.2 mm, and an axial pressure of 11 kN.

  10. A Randomized Rounding Approach for Optimization of Test Sheet Composing and Exposure Rate Control in Computer-Assisted Testing

    ERIC Educational Resources Information Center

    Wang, Chu-Fu; Lin, Chih-Lung; Deng, Jien-Han

    2012-01-01

    Testing is an important stage of teaching as it can assist teachers in auditing students' learning results. A good test is able to accurately reflect the capability of a learner. Nowadays, Computer-Assisted Testing (CAT) is greatly improving traditional testing, since computers can automatically and quickly compose a proper test sheet to meet user…

  11. Start-up, performance and optimization of a compost biofilter treating gas-phase mixture of benzene and toluene.

    PubMed

    Rene, Eldon R; Kar, Saurajyoti; Krishnan, Jagannathan; Pakshirajan, K; López, M Estefanía; Murthy, D V S; Swaminathan, T

    2015-08-01

    The performance of a compost biofilter inoculated with mixed microbial consortium was optimized for treating a gas-phase mixture of benzene and toluene. The biofilter was acclimated to these VOCs for a period of ∼18d. The effects of concentration and flow rate on the removal efficiency (RE) and elimination capacity (EC) were investigated by varying the inlet concentration of benzene (0.12-0.95g/m(3)), toluene (0.14-1.48g/m(3)) and gas-flow rate (0.024-0.072m(3)/h). At comparable loading rates, benzene removal in the mixture was reduced in the range of 6.6-41% in comparison with the individual benzene degradation. Toluene removal in mixture was even more affected as observed from the reductions in REs, ranging from 18.4% to 76%. The results were statistically interpreted by performing an analysis of variance (ANOVA) to elucidate the main and interaction effects.

  12. Limit of detection of 15{sub N} by gas-chromatography atomic emission detection: Optimization using an experimental design

    SciTech Connect

    Deruaz, D.; Bannier, A.; Pionchon, C.

    1995-08-01

    This paper deals with the optimal conditions for the detection of {sup 15}N determined using a four-factor experimental design from [2{sup 13}C,-1,3 {sup 15}N] caffeine measured with an atomic emission detector (AED) coupled to gas chromatography (GC). Owing to the capability of a photodiodes array, AED can simultaneously detect several elements using their specific emission lines within a wavelength range of 50 nm. So, the emissions of {sup 15}N and {sup 14}N are simultaneously detected at 420.17 nm and 421.46 nm respectively. Four independent experimental factors were tested (1) helium flow rate (plasma gas); (2) methane pressure (reactant gas); (3) oxygen pressure; (4) hydrogen pressure. It has been shown that these four gases had a significant influence on the analytical response of {sup 15}N. The linearity of the detection was determined using {sup 15}N amounts ranging from 1.52 pg to 19 ng under the optimal conditions obtained from the experimental design. The limit of detection was studied using different methods. The limits of detection of {sup 15}N was 1.9 pg/s according to the IUPAC method (International-Union of Pure and Applied Chemistry). The method proposed by Quimby and Sullivan gave a value of 2.3 pg/s and that of Oppenheimer gave a limit of 29 pg/s. For each determination, and internal standard: 1-isobutyl-3.7 dimethylxanthine was used. The results clearly demonstrate that GC AED is sensitive and selective enough to detect and measure {sup 15}N-labelled molecules after gas chromatographic separation.

  13. Microwave-assisted solvent extraction and gas chromatography ion trap mass spectrometry procedure for the determination of persistent organochlorine pesticides (POPs) in marine sediment.

    PubMed

    Carro, Nieves; García, Isabel; Ignacio, María; Mouteira, Ana

    2006-07-01

    Microwave-assisted solvent extraction of persistent organochlorine pesticides (POPs) in marine sediment was developed and optimized by means of two-level factorial designs. Six variables (microwave power, extraction time and temperature, amount of sample, solvent volume, and sample moisture) were considered as factors in the optimization process. The results show that the amount of sample to be extracted and solvent volume are statistically significant for the overall recovery of the studied pesticides, although compromise conditions have to be established with the object of avoiding overpressure in closed vessels. After extraction, a clean up step including the use of a silica cartridge was performed prior to chromatographic determination in order to remove interferences. The optimized procedure was compared to conventional Soxhlet extraction. The MS-MS ion preparation mode was applied to improve the sensitivity and selectivity of the chromatographic technique.

  14. A study of the optimization method used in the NAVY/NASA gas turbine engine computer code

    NASA Technical Reports Server (NTRS)

    Horsewood, J. L.; Pines, S.

    1977-01-01

    Sources of numerical noise affecting the convergence properties of the Powell's Principal Axis Method of Optimization in the NAVY/NASA gas turbine engine computer code were investigated. The principal noise source discovered resulted from loose input tolerances used in terminating iterations performed in subroutine CALCFX to satisfy specified control functions. A minor source of noise was found to be introduced by an insufficient number of digits in stored coefficients used by subroutine THERM in polynomial expressions of thermodynamic properties. Tabular results of several computer runs are presented to show the effects on program performance of selective corrective actions taken to reduce noise.

  15. Arapahoe low-sulfur-coal fabric filter pilot plant: Volume 3, Characterization of sonic-assisted reverse-gas cleaning, May 1982--May 1984: Final report

    SciTech Connect

    Cushing, K.M.; Bustard, C.J.; Pontius, D.H.; Pyle, B.E.; Smith, W.B.

    1989-02-01

    During 1981 intense interest developed in the utility industry regarding the use of horns as a supplement to reverse-gas bag cleaning. To characterize and assess sonic-enhanced, reverse-gas cleaning, horns were installed at EPRI's 10-MW Fabric Filter Pilot Plant (FFPP) at its Arapahoe Test Facility located at Public Service Company of Colorado's Arapahoe Steam Plant in Denver, Colorado. In addition to the FFPP tests, laboratory studies of sonic cleaning were conducted to supplement the pilot plant data. To verify the applicability of the pilot plant and laboratory work to full-scale baghouses, field data from utility baghouses in which horns had been installed were collected. The purpose of the testing was to determine the range of horn frequencies and total output power most effective in removing residual dustcakes from bags in reverse-gas-cleaned baghouses and, hence, most effective in reducing baghouse pressure drop. No attempt was made to identify a specific horn or horns most appropriate for baghouse application. The report presents the results of this testing from May 1982 through May 1984. Results showed that horns can dislodge a significant fraction of residual dustcake, thereby reducing pressure drop by as much as 60% without any noticeable reduction in bag life. Although outlet particulate emissions are higher with sonic assistance, they are generally <0.01 lb/10/sup 6/ Btu---below the 1979 New Source Performance Standards of 0.03 lb/MBtu. The overall results of this sonic horn investigation indicate that reverse-gas cleaning with sonic assistance definitely promotes more effective bag filter cleaning and lower pressure drop, and it should be considered as a supplement for most reverse-gas cleaned baghouse applications. 10 refs., 37 figs., 7 tabs.

  16. Optimal integration condition between the gas turbine air compressor and the air separation unit of IGCC power plant

    SciTech Connect

    Lee, C.; Kim, H.T.; Yun, Y.

    1997-12-31

    Parametric studies are conducted for optimizing the integration design between gas turbine compressor and air separation unit (ASU) of integrated gasification combined cycle (IGCC) power plant. The ASU is assumed as low pressure double-distillation column process which is integrated at the interstage location of the compressor, and integration design criteria of air extraction and reversing heat exchanger are defined and mathematically formulated. With the performance prediction of compressor by through-flow analysis, the effects of pinch-point temperature difference (PTD) in the reversing heat exchanger, the amount and the pressure of extracted air are quantitatively examined. As the extraction air amount or the PTD is increased, the power consumption is increased. The compressor efficiency deteriorates as the increase of the flow rate of air extracted at higher pressure while improving at lower pressure air extraction. Furthermore, optimal integration condition for compressor efficiency maximization is found by generating the compressor characteristic curve.

  17. Efficiency enhancement for natural gas liquefaction with CO2 capture and sequestration through cycles innovation and process optimization

    NASA Astrophysics Data System (ADS)

    Alabdulkarem, Abdullah

    Liquefied natural gas (LNG) plants are energy intensive. As a result, the power plants operating these LNG plants emit high amounts of CO2 . To mitigate global warming that is caused by the increase in atmospheric CO2, CO2 capture and sequestration (CCS) using amine absorption is proposed. However, the major challenge of implementing this CCS system is the associated power requirement, increasing power consumption by about 15--25%. Therefore, the main scope of this work is to tackle this challenge by minimizing CCS power consumption as well as that of the entire LNG plant though system integration and rigorous optimization. The power consumption of the LNG plant was reduced through improving the process of liquefaction itself. In this work, a genetic algorithm (GA) was used to optimize a propane pre-cooled mixed-refrigerant (C3-MR) LNG plant modeled using HYSYS software. An optimization platform coupling Matlab with HYSYS was developed. New refrigerant mixtures were found, with savings in power consumption as high as 13%. LNG plants optimization with variable natural gas feed compositions was addressed and the solution was proposed through applying robust optimization techniques, resulting in a robust refrigerant which can liquefy a range of natural gas feeds. The second approach for reducing the power consumption is through process integration and waste heat utilization in the integrated CCS system. Four waste heat sources and six potential uses were uncovered and evaluated using HYSYS software. The developed models were verified against experimental data from the literature with good agreement. Net available power enhancement in one of the proposed CCS configuration is 16% more than the conventional CCS configuration. To reduce the CO2 pressurization power into a well for enhanced oil recovery (EOR) applications, five CO2 pressurization methods were explored. New CO2 liquefaction cycles were developed and modeled using HYSYS software. One of the developed

  18. A Novel Optimization Technique to Improve Gas Recognition by Electronic Noses Based on the Enhanced Krill Herd Algorithm

    PubMed Central

    Wang, Li; Jia, Pengfei; Huang, Tailai; Duan, Shukai; Yan, Jia; Wang, Lidan

    2016-01-01

    An electronic nose (E-nose) is an intelligent system that we will use in this paper to distinguish three indoor pollutant gases (benzene (C6H6), toluene (C7H8), formaldehyde (CH2O)) and carbon monoxide (CO). The algorithm is a key part of an E-nose system mainly composed of data processing and pattern recognition. In this paper, we employ support vector machine (SVM) to distinguish indoor pollutant gases and two of its parameters need to be optimized, so in order to improve the performance of SVM, in other words, to get a higher gas recognition rate, an effective enhanced krill herd algorithm (EKH) based on a novel decision weighting factor computing method is proposed to optimize the two SVM parameters. Krill herd (KH) is an effective method in practice, however, on occasion, it cannot avoid the influence of some local best solutions so it cannot always find the global optimization value. In addition its search ability relies fully on randomness, so it cannot always converge rapidly. To address these issues we propose an enhanced KH (EKH) to improve the global searching and convergence speed performance of KH. To obtain a more accurate model of the krill behavior, an updated crossover operator is added to the approach. We can guarantee the krill group are diversiform at the early stage of iterations, and have a good performance in local searching ability at the later stage of iterations. The recognition results of EKH are compared with those of other optimization algorithms (including KH, chaotic KH (CKH), quantum-behaved particle swarm optimization (QPSO), particle swarm optimization (PSO) and genetic algorithm (GA)), and we can find that EKH is better than the other considered methods. The research results verify that EKH not only significantly improves the performance of our E-nose system, but also provides a good beginning and theoretical basis for further study about other improved krill algorithms’ applications in all E-nose application areas. PMID

  19. Optimism

    PubMed Central

    Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.

    2010-01-01

    Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998

  20. Optimization of ultrasound-assisted extraction of total monomeric anthocyanin (TMA) and total phenolic content (TPC) from eggplant (Solanum melongena L.) peel.

    PubMed

    Dranca, Florina; Oroian, Mircea

    2016-07-01

    The present study describes the extraction of total monomeric anthocyanin (TMA) and total phenolic content (TPC) from eggplant peel using ultrasonic treatments and methanol and 2-propanol as extraction solvents. The extraction yields were optimized by varying the solvent concentration, ultrasonic frequency, temperature and time of ultrasonic treatment. Box-Behnken design was used to investigate the effect of process variables on the ultrasound-assisted extraction. The results showed that for TPC extraction the optimal condition were obtained with a methanol concentration of 76.6%, 33.88 kHz ultrasonic frequency, a temperature of 69.4 °C and 57.5 min extraction time. For TMA the optimal condition were the following: 54.4% methanol concentration, 37 kHz, 55.1 °C and process time of 44.85 min.

  1. Orthogonal array optimization of ultrasound-assisted emulsification-microextraction for the determination of chlorinated phenoxyacetic acids in river water.

    PubMed

    Lin, Shu-Ling; Fuh, Ming-Ren

    2010-05-21

    Orthogonal array design (OAD) was utilized for the first time to optimize the experimental conditions of ultrasound-assisted emulsification-microextraction (USAEME) for determining chlorinated phenoxyacetic acids (CPAs) in river water samples. The use of ultrasound facilitates the mass transfer of CPAs from an aqueous phase into a water-immiscible organic extraction solvent (dichloromethane, DCM) without adding dispersive solvent to form numerous microdroplets. The water-immiscible extractant was collected by centrifugation, dried under low pressure, reconstituted in methanol-water mixture (1:1), and injected into a HPLC system for the determination of CPAs. The linear range was 2-1000 ng mL(-1) (2, 5, 10, 50, 200, 500 and 1000 ng mL(-1)) for each analyte and the relative standard deviations of CPAs among the seven different concentrations were in the range of 1.5-17.0% (n=3). The detection limits (signal-to-noise ratio of 3) of CPAs ranged from 0.67 to 1.50 ng mL(-1). The ranges of intra-day precision (n=3) for CPAs at the levels of 5 and 200 ng mL(-1) were 3.6-11.9% and 5.3-9.5%, respectively. The range of inter-day precision (n=3) at 5 and 200 ng mL(-1) were 1.4-7.7% and 8.5-12.2%, respectively. The applicability of USAEME for environmental analysis was demonstrated by determining CPAs in river water. The recoveries of CPAs from five-spiked river water samples at 10 and 200 ng mL(-1) were 96.3-112.5% and 94.8-109.4%, respectively. The maximum contaminant level (MCL) of 2,4-D in drinking water and the tolerance of residues in food for p-CPA are 70 and 200 microg L(-1), respectively, according to the US EPA regulations. These contaminant levels fall in the linear range investigated in this study. In addition, this USAEME method provided detection limits lower than their contaminant levels, which made USAEME an effective sample preparation method for determining organic environmental contaminants, such as CPAs, in river water samples with little consumption of

  2. Optimization of a two stage light gas gun. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Rynearson, R. J.; Rand, J. L.

    1972-01-01

    Performance characteristics of the Texas A&M University light gas gun are presented along with a review of basic gun theory and popular prediction methods. A computer routine based on the simple isentropic compression method is discussed. Results from over 60 test shots are given which demonstrate an increase in gun muzzle velocity from 9.100 ft/sec. to 19,000 ft/sec. The data gathered indicated the Texas A&M light gas gun more closely resembles an isentropic compression gun rather than a shock compression gun.

  3. Naturally fractured tight gas reservoir detection optimization. Quarterly technical progress report, April 1995--June 1995

    SciTech Connect

    1995-08-01

    Research continued on methods to detect naturally fractured tight gas reservoirs. This report contains a seismic survey map, and reports on efforts towards a source test to select the source parameters for a 37 square mile compressional wave 3-D seismic survey. Considerations of the source tests are discussed.

  4. Optimized Breech Location in the Harry Diamond Laboratories 4-Inch Gas Gun

    DTIC Science & Technology

    1982-04-01

    Zop,)] 1𔃼 . (2) (3) (4) ’Arnold E. Seigel. Performance Calculations and Op- timization of Gas Guns, Chevy Chase, MD, HDL- CR-81-723-1 (May 1981...189 ATTN S. SUGARMAN GREEN ACRES ROAD WEST VALLEY STREAM, NY 11582 BOEING COMPANY AEROSPACE COMPANY PO BOX 3707 ATTN 8K-38, RUTH E. PERRENBOOM

  5. Determination of chlorobenzenes in textiles by pressurized hot water extraction followed by vortex-assisted liquid-liquid microextraction and gas chromatography-mass spectrometry.

    PubMed

    Lu, Yang; Zhu, Yan

    2013-12-06

    A method for quantitative determination of chlorobenzenes in textiles is developed, using pressurized hot water extraction (PHWE), vortex-assisted liquid-liquid microextraction (VALLME) and gas chromatography-mass spectrometry (GC-MS). VALLME serves as a trapping step after PHWE. The extraction conditions are investigated, as well as the quantitative features such as linearity, limits of detection (LODs), limits of quantification (LOQs), repeatabilities and reproducibilities between days. LOQs of 0.018-0.032mg/kg were achieved. The present method provides good repeatabilities (RSD<6.9%) and demonstrates that PHWE-VALLME-GC-MS is a simple, rapid and environmentally friendly method for determination of chlorobenzenes in textiles.

  6. The application of an assisting gas plasma generator for low- temperature magnetron sputtering of Ti-C-Mo-S antifriction coatings on titanium alloys

    NASA Astrophysics Data System (ADS)

    Potekaev, A. I.; Savostikov, V. M.; Tabachenko, A. N.; Dudarev, E. F.; Melnikova, E. A.; Shulepov, I. A.

    2015-11-01

    The positive effect of assisting influence of high-density gas plasma formed by an independent plasma generator PINK on mechanical and tribological characteristics of Ti-C- Mo-S magnetron coating on titanium alloys at lowered to 350°C temperature of coating regardless of alloy structural condition was revealed by methods of calotest, nanorecognition, scratch testing and frictional material tests. The coating formed by means of a combined magnetron plasma method reduces titanium alloys friction coefficient in multiple times and increases wear resistance by two orders of magnitude. At the same time the mechanical properties of ultra-fine-grained titanium alloys obtained by nanostructuring do not deteriorate.

  7. Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry.

    PubMed

    Merritt, D A; Freeman, K H; Ricci, M P; Studley, S A; Hayes, J M

    1995-07-15

    Conditions and systems for on-line combustion of effluents from capillary gas chromatographic columns and for removal of water vapor from product streams were tested. Organic carbon in gas chromatographic peaks 15 s wide and containing up to 30 nanomoles of carbon was quantitatively converted to CO2 by tubular combustion reactors, 200 x 0.5 mm, packed with CuO or NiO. No auxiliary source of O2 was required because oxygen was supplied by metal oxides. Spontaneous degradation of CuO limited the life of CuO reactors at T > 850 degrees C. Since NiO does not spontaneously degrade, its use might be favored, but Ni-bound carbon phases form and lead to inaccurate isotopic results at T < 1050 degrees C if gas-phase O2 is not added. For all compounds tested except CH4, equivalent isotopic results are provided by CuO at 850 degrees C, NiO + O2 (gas-phase mole fraction, 10(-3)) at 1050 degrees C and NiO at 1150 degrees C. The combustion interface did not contribute additional analytical uncertainty, thus observed standard deviations of 13C/12C ratios were within a factor of 2 of shot-noise limits. For combustion and isotopic analyses of CH4, in which quantitative combustion required T approximately 950 degrees C, NiO-based systems are preferred, and precision is approximately 2 times lower than that observed for other analytes. Water must be removed from the gas stream transmitted to the mass spectrometer or else protonation of CO2 will lead to inaccuracy in isotopic analyses. Although thresholds for this effect vary between mass spectrometers, differential permeation of H2O through Nafion tubing was effective in both cases tested, but the required length of the Nafion membrane was 4 times greater for the more sensitive mass spectrometer.

  8. Performance and optimization of a combustion interface for isotope ratio monitoring gas chromatography/mass spectrometry

    NASA Technical Reports Server (NTRS)

    Merritt, D. A.; Freeman, K. H.; Ricci, M. P.; Studley, S. A.; Hayes, J. M.

    1995-01-01

    Conditions and systems for on-line combustion of effluents from capillary gas chromatographic columns and for removal of water vapor from product streams were tested. Organic carbon in gas chromatographic peaks 15 s wide and containing up to 30 nanomoles of carbon was quantitatively converted to CO2 by tubular combustion reactors, 200 x 0.5 mm, packed with CuO or NiO. No auxiliary source of O2 was required because oxygen was supplied by metal oxides. Spontaneous degradation of CuO limited the life of CuO reactors at T > 850 degrees C. Since NiO does not spontaneously degrade, its use might be favored, but Ni-bound carbon phases form and lead to inaccurate isotopic results at T < 1050 degrees C if gas-phase O2 is not added. For all compounds tested except CH4, equivalent isotopic results are provided by CuO at 850 degrees C, NiO + O2 (gas-phase mole fraction, 10(-3)) at 1050 degrees C and NiO at 1150 degrees C. The combustion interface did not contribute additional analytical uncertainty, thus observed standard deviations of 13C/12C ratios were within a factor of 2 of shot-noise limits. For combustion and isotopic analyses of CH4, in which quantitative combustion required T approximately 950 degrees C, NiO-based systems are preferred, and precision is approximately 2 times lower than that observed for other analytes. Water must be removed from the gas stream transmitted to the mass spectrometer or else protonation of CO2 will lead to inaccuracy in isotopic analyses. Although thresholds for this effect vary between mass spectrometers, differential permeation of H2O through Nafion tubing was effective in both cases tested, but the required length of the Nafion membrane was 4 times greater for the more sensitive mass spectrometer.

  9. Gas ultrasonic flow rate measurement through genetic-ant colony optimization based on the ultrasonic pulse received signal model

    NASA Astrophysics Data System (ADS)

    Hou, Huirang; Zheng, Dandan; Nie, Laixiao

    2015-04-01

    For gas ultrasonic flowmeters, the signals received by ultrasonic sensors are susceptible to noise interference. If signals are mingled with noise, a large error in flow measurement can be caused by triggering mistakenly using the traditional double-threshold method. To solve this problem, genetic-ant colony optimization (GACO) based on the ultrasonic pulse received signal model is proposed. Furthermore, in consideration of the real-time performance of the flow measurement system, the improvement of processing only the first three cycles of the received signals rather than the whole signal is proposed. Simulation results show that the GACO algorithm has the best estimation accuracy and ant-noise ability compared with the genetic algorithm, ant colony optimization, double-threshold and enveloped zero-crossing. Local convergence doesn’t appear with the GACO algorithm until -10 dB. For the GACO algorithm, the converging accuracy and converging speed and the amount of computation are further improved when using the first three cycles (called GACO-3cycles). Experimental results involving actual received signals show that the accuracy of single-gas ultrasonic flow rate measurement can reach 0.5% with GACO-3 cycles, which is better than with the double-threshold method.

  10. Experimental studies and statistical analysis of membrane fouling behavior and performance in microfiltration of microalgae by a gas sparging assisted process.

    PubMed

    Javadi, Najvan; Ashtiani, Farzin Zokaee; Fouladitajar, Amir; Zenooz, Alireza Moosavi

    2014-06-01

    Response surface methodology (RSM) and central composite design (CCD) were applied for modeling and optimization of cross-flow microfiltration of Chlorella sp. suspension. The effects of operating conditions, namely transmembrane pressure (TMP), feed flow rate (Qf) and optical density of feed suspension (ODf), on the permeate flux and their interactions were determined. Analysis of variance (ANOVA) was performed to test the significance of response surface model. The effect of gas sparging technique and different gas-liquid two phase flow regimes on the permeate flux was also investigated. Maximum flux enhancement was 61% and 15% for Chlorella sp. with optical densities of 1.0 and 3.0, respectively. These results indicated that gas sparging technique was more efficient in low concentration microalgae microfiltration in which up to 60% enhancement was achieved in slug flow pattern. Additionally, variations in the transmission of exopolysaccharides (EPS) and its effects on the fouling phenomenon were evaluated.

  11. Evaluation of Thermoelectric Properties of Bite Alloys for the Optimization of Gas-Cooled Peltier Current Lead

    NASA Astrophysics Data System (ADS)

    Fujii, T.; Fukuda, S.; Kawahara, T.; Emoto, M.; Sugino, M.; Sun, J.; Hamabe, M.; Watanabe, H.; Yamaguchi, S.

    2010-04-01

    A direct current superconducting power transmission (DC-SCPT) test facility with 20-meter power cable has been developed in Chubu University. Heat leakage through current leads dominates in case of short-distance DC-SCPT. To solve this problem, we have developed special Peltier current lead (PCL) with bismuth telluride (BiTe) alloy is used as a Peltier material, and have studied a gas-cooled PCL as a novel type current lead for higher reduction of the heat leakage. In order to achieve high efficiency, highest thermoelectric figure of merit material is important to be used especially at low temperature conditions. In our work we measured the thermoelectric properties of BiTe samples, and optimized geometry of PCL by the numerical calculations. It was fount that the heat leakages through PCL and gas-cooled PCL are reduced to 55% and to 36% of the conventional copper current lead (CCL) at the self-cooling condition, correspondingly. PCL can reduce the total electric power consumption of the whole system. We also discuss the heat exchange ratio for the gas-cooled PCL, and extend this approach for further reduction of the heat leakage.

  12. Dopant-assisted negative photoionization Ion mobility spectrometry coupled with on-line cooling inlet for real-time monitoring H2S concentration in sewer gas.

    PubMed

    Peng, Liying; Jiang, Dandan; Wang, Zhenxin; Hua, Lei; Li, Haiyang

    2016-06-01

    Malodorous hydrogen sulfide (H2S) gas often exists in the sewer system and associates with the problems of releasing the dangerous odor to the atmosphere and causing sewer pipe to be corroded. A simple method is in demand for real-time measuring H2S level in the sewer gas. In this paper, an innovated method based on dopant-assisted negative photoionization ion mobility spectrometry (DANP-IMS) with on-line semiconductor cooling inlet was put forward and successfully applied for the real-time measurement of H2S in sewer gas. The influence of moisture was effectively reduced via an on-line cooling method and a non-equilibrium dilution with drift gas. The limits of quantitation for the H2S in ≥60% relative humidity air could be obtained at ≤79.0ng L(-1) with linear ranges of 129-2064ng L(-1). The H2S concentration in a sewer manhole was successfully determined while its product ions were identified by an ion-mobility time-of-fight mass spectrometry. Finally, the correlation between sewer H2S concentration and the daily routines and habits of residents was investigated through hourly or real-time monitoring the variation of sewer H2S in manholes, indicating the power of this DANP-IMS method in assessing the H2S concentration in sewer system.

  13. MOVPE GaN gas phase chemistry for reactor design and optimization

    SciTech Connect

    Safvi, S.A.; Thon, A.; Kuech, T.F.; Redwing, J.M.; Flynn, J.S.; Tischler, M.A.

    1997-12-31

    The results of gas phase decomposition studies are used to construct a chemistry model which is compared to data obtained from an experimental MOVPE reactor. A flow tube reactor is used to study gas phase reactions between trimethylgallium (TMG) and ammonia at high temperatures, characteristic to the metalorganic vapor phase epitaxy (MOVPE) of GaN. Experiments were performed to determine the effect of the mixing of the Group III precursors and Group V precursors on the growth rate, growth uniformity and film properties. Growth rates are predicted for simple reaction mechanisms and compared to those obtained experimentally. Quantification of the loss of reacting species due to oligomerization is made based on experimentally observed growth rates. The model is used to obtain trends in growth rate and uniformity with the purpose of moving towards better operating conditions.

  14. Optimization of ultrasound-assisted extraction to obtain mycosterols from Agaricus bisporus L. by response surface methodology and comparison with conventional Soxhlet extraction.

    PubMed

    Heleno, Sandrina A; Diz, Patrícia; Prieto, M A; Barros, Lillian; Rodrigues, Alírio; Barreiro, Maria Filomena; Ferreira, Isabel C F R

    2016-04-15

    Ergosterol, a molecule with high commercial value, is the most abundant mycosterol in Agaricus bisporus L. To replace common conventional extraction techniques (e.g. Soxhlet), the present study reports the optimal ultrasound-assisted extraction conditions for ergosterol. After preliminary tests, the results showed that solvents, time and ultrasound power altered the extraction efficiency. Using response surface methodology, models were developed to investigate the favourable experimental conditions that maximize the extraction efficiency. All statistical criteria demonstrated the validity of the proposed models. Overall, ultrasound-assisted extraction with ethanol at 375 W during 15 min proved to be as efficient as the Soxhlet extraction, yielding 671.5 ± 0.5mg ergosterol/100 g dw. However, with n-hexane extracts with higher purity (mg ergosterol/g extract) were obtained. Finally, it was proposed for the removal of the saponification step, which simplifies the extraction process and makes it more feasible for its industrial transference.

  15. Optimization of the interface between radiology, surgery, radiotherapy, and pathology in head and neck tumor surgery: a navigation-assisted multidisciplinary network.

    PubMed

    Guijarro-Martínez, R; Gellrich, N-C; Witte, J; Tapioles, D; von Briel, C; Kolotas, C; Achinger, J; Hailemariam, S; Schulte, H; Rohner, D; Hammer, B

    2014-02-01

    A navigation-assisted multidisciplinary network to improve the interface between radiology, surgery, radiotherapy, and pathology in the field of head and neck cancer is described. All implicated fields are integrated by a common server platform and have remote data access in a ready-to-use format. The margins of resection and exact locations of biopsies are mapped intraoperatively. The pathologist uses the numerical coordinates of these samples to precisely trace each specimen in the anatomical field. Subsequently, map-guided radiotherapy is planned. In addition to the benefits of image-guided resection, this model enables radiotherapy planning according to the specific coordinates of the resection defect plus any residually affected sites identified by the pathologist. Irradiation of adjacent healthy structures is thereby minimized. In summary, the navigation-assisted network described grants timely multidisciplinary feedback between all fields involved, attains meticulous pathological definition, and permits optimized coordinate-directed radiotherapy.

  16. Optimizing the hohlraum gas density for better symmetry control of indirect drive implosion experiments

    NASA Astrophysics Data System (ADS)

    Izumi, Nobuhiko; Hall, G. N.; Nagel, S. R.; Khan, S.; Rygg, R. R.; MacKinnon, A. J.; Ho, D. D.; Berzak Hopkins, L.; Jones, O. S.; Town, R. P. J.; Bradley, D. K.

    2014-10-01

    To achieve a spherically symmetric implosion, control of drive uniformity is essential. Both the ablation pressure and the mass ablation rate on the capsule surface should be made as uniform as possible for the duration of the drive. For an indirect drive implosion, the drive uniformity changes during the pulse because of: (1) the dynamic movement of the laser spots due to blow-off of the hohlraum wall, and (2) cross-beam energy transfer caused by laser-plasma interaction in the hohlraum. To tamp the wall blow-off, we use gas filled hohlraums. The cross-beam energy transfer can be controlled by applying a wave length separation between the cones of the laser beams. However, both of those dynamic effects are sensitive to the initial density of the hohlraum gas fill. To assess this, we performed implosion experiments with different hohlraum gas densities and tested the effect on drive asymmetry. The uniformity of the acceleration was measured by in-flight x-ray backlit imaging of the capsule. The uniformity of the core assembly was observed by imaging the self emission x-ray from the core. We will report on the experimental results and compare them to hydrodynamic simulations. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-626372.

  17. Optimal control system design of an acid gas removal unit for an IGCC power plants with CO2 capture

    SciTech Connect

    Jones, D.; Bhattacharyya, D.; Turton, R.; Zitney, S.

    2012-01-01

    Future IGCC plants with CO{sub 2} capture should be operated optimally in the face of disturbances without violating operational and environmental constraints. To achieve this goal, a systematic approach is taken in this work to design the control system of a selective, dual-stage Selexol-based acid gas removal (AGR) unit for a commercial-scale integrated gasification combined cycle (IGCC) power plant with pre-combustion CO{sub 2} capture. The control system design is performed in two stages with the objective of minimizing the auxiliary power while satisfying operational and environmental constraints in the presence of measured and unmeasured disturbances. In the first stage of the control system design, a top-down analysis is used to analyze degrees of freedom, define an operational objective, identify important disturbances and operational/environmental constraints, and select the control variables. With the degrees of freedom, the process is optimized with relation to the operational objective at nominal operation as well as under the disturbances identified. Operational and environmental constraints active at all operations are chosen as control variables. From the results of the optimization studies, self-optimizing control variables are identified for further examination. Several methods are explored in this work for the selection of these self-optimizing control variables. Modifications made to the existing methods will be discussed in this presentation. Due to the very large number of candidate sets available for control variables and due to the complexity of the underlying optimization problem, solution of this problem is computationally expensive. For reducing the computation time, parallel computing is performed using the Distributed Computing Server (DCS®) and the Parallel Computing® toolbox from Mathworks®. The second stage is a bottom-up design of the control layers used for the operation of the process. First, the regulatory control layer is

  18. Optimization of an electromagnetic generator for strong shocks in low pressure gas

    NASA Astrophysics Data System (ADS)

    Larour, Jean; Singh, Raj Laxmi; Stehlé, Chantal; Ciardi, Andrea; Chaulagain, Uddhab; Suzuki-Vidal, Francisco

    2015-12-01

    In this paper, we present the design and optimization of an electromagnetic generator, able to produce strong shocks in noble gases, relevant to astrophysical conditions. It is a powerful accelerating device which ejects a quasi-planar plasma sheath out of a set of coaxial conical electrodes where a pulsed 100-kA current is passing. A simple model is used to optimize the operation parameters. Preliminary experiments show that the generator is capable of launching supersonic shocks in Argon, in the form of a thin plasma layer with the speed of ∼1-30 km/s. A three-dimension MHD simulation gives a description consistent with the model and with the observations.

  19. Naturally fractured tight gas reservoir detection optimization. Quarterly report, October 1--December 31, 1994

    SciTech Connect

    1995-01-30

    This progress report covers the following tasks: Computational geochemistry (Indiana University Laboratory); and geologic assessment of the Piceance Basin. Computational geochemistry covers; three- dimensional basin simulator; stress solver; two-dimensional basin simulator; organic reactions and multi-phase flow; grid optimization; database calibration and data input; and Piceance Basin initial simulation. Sub-tasks under geologic assessment of the Piceance Basin include: structural analysis; reservoir characterization; stratigraphic interpretation; seismic interpretation; and remote sensing interpretation.

  20. Theoretical optimization by genetic algorithm of delayed extraction parameters for a matrix-assisted laser desorption/ionization time-of-flight mass spectrometer.

    PubMed

    Tauro, S; Razvi, M A N

    2005-01-01

    This paper presents the application of a genetic algorithm (GA) to optimize the operating parameters, namely pulse voltage and extraction delay time, when using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS). Simulations predict the presence of several combinations of these parameters that give a local maximum. The aim is to locate the optimal combination (a global maximum) of pulse voltage and extraction time delay in order to focus the ions of a particular m/z value to achieve the best resolution in a given instrumental geometry. The GA locates the global maximum quickly. The results indicate that it may be possible to achieve very high resolving power by using delayed extraction (DE)-MALDI-TOFMS with parameters obtained from the GA.

  1. An optimized concept for flue gas cleaning downstream of MWCs using sodium tetrasulfide for mercury removal

    SciTech Connect

    Schuettenhelm, W.; Hartenstein, H.U.; Licata, A.

    1998-07-01

    In Germany and other central European countries, new emission standards for refuse incineration plants became effective in 1989/90. In recent years the operators of incinerating plants in Germany demanded higher removal emission efficiency than required by law in order to obtain local permits. In the course of the procurement process, complex flue gas cleaning systems were approved and built. As a result, the costs for air pollution control systems exceeded the costs of the refuse combustion system (stoker plus boiler) which has been reflected in the constantly climbing disposal costs. Not all of the increased disposal costs have been able to be passed along to the market. Economic pressure has led to a search for simple solutions and low-cost flue gas cleaning systems which correspond to the legal and contractual limits. A new processes was developed by L. and C. Steinmueller GmbH (Steinmueller) using sodium tetrasulfide (Na{sub 2}S{sub 4}) as a additive for the emission control of mercury. This paper will present an overview of the general application of this new technology in the waste-to-energy field. The efficiency of the reduction of mercury, and serviceability and the simple handling of this new technology will be shown by results of plants which are in operating. For a conclusion, an outlook is provided into future applications of this technology over the waste-to-energy field.

  2. Turbine cooling configuration selection and design optimization for the high-reliability gas turbine. Final report

    SciTech Connect

    Smith, M J; Suo, M

    1981-04-01

    The potential of advanced turbine convectively air-cooled concepts for application to the Department of Energy/Electric Power Research Institute (EPRI) Advanced Liquid/Gas-Fueled Engine Program was investigated. Cooling of turbine airfoils is critical technology and significant advances in cooling technology will permit higher efficiency coal-base-fuel gas turbine energy systems. Two new airfoil construction techniques, bonded and wafer, were the principal designs considered. In the bonded construction, two airfoil sections having intricate internal cooling configurations are bonded together to form a complete blade or vane. In the wafer construction, a larger number (50 or more) of wafers having intricate cooling flow passages are bonded together to form a complete blade or vane. Of these two construction techniques, the bonded airfoil is considered to be lower in risk and closer to production readiness. Bonded airfoils are being used in aircraft engines. A variety of industrial materials were evaluated for the turbine airfoils. A columnar grain nickel alloy was selected on the basis of strength and corrosion resistance. Also, cost of electricity and reliability were considered in the final concept evaluation. The bonded airfoil design yielded a 3.5% reduction in cost-of-electricity relative to a baseline Reliable Engine design. A significant conclusion of this study was that the bonded airfoil convectively air-cooled design offers potential for growth to turbine inlet temperatures above 2600/sup 0/F with reasonable development risk.

  3. Application of response surface methodology to optimize microwave-assisted extraction of silymarin from milk thistle seeds

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several parameters of Microwave-assisted extraction (MAE) including extraction time, extraction temperature, ethanol concentration and solid-liquid ratio were selected to describe the MAE processing. The silybin content, measured by an UV-Vis spectrophotometry, was considered as the silymarin yield....

  4. Designing optimal greenhouse gas observing networks that consider performance and cost

    DOE PAGES

    Lucas, D. D.; Yver Kwok, C.; Cameron-Smith, P.; ...

    2015-06-16

    Emission rates of greenhouse gases (GHGs) entering into the atmosphere can be inferred using mathematical inverse approaches that combine observations from a network of stations with forward atmospheric transport models. Some locations for collecting observations are better than others for constraining GHG emissions through the inversion, but the best locations for the inversion may be inaccessible or limited by economic and other non-scientific factors. We present a method to design an optimal GHG observing network in the presence of multiple objectives that may be in conflict with each other. As a demonstration, we use our method to design a prototypemore » network of six stations to monitor summertime emissions in California of the potent GHG 1,1,1,2-tetrafluoroethane (CH2FCF3, HFC-134a). We use a multiobjective genetic algorithm to evolve network configurations that seek to jointly maximize the scientific accuracy of the inferred HFC-134a emissions and minimize the associated costs of making the measurements. The genetic algorithm effectively determines a set of "optimal" observing networks for HFC-134a that satisfy both objectives (i.e., the Pareto frontier). The Pareto frontier is convex, and clearly shows the tradeoffs between performance and cost, and the diminishing returns in trading one for the other. Without difficulty, our method can be extended to design optimal networks to monitor two or more GHGs with different emissions patterns, or to incorporate other objectives and constraints that are important in the practical design of atmospheric monitoring networks.« less

  5. Distortion Control of Transmission Components by Optimized High Pressure Gas Quenching

    NASA Astrophysics Data System (ADS)

    Heuer, Volker; Faron, Donald R.; Bolton, David; Lifshits, Mike; Loeser, K.

    2013-07-01

    The paper presents how the "Dynamic Quenching" and "Reversing gas flow" processes are successfully applied on internal ring gears and planetary gears for a 6-speed automatic transmission. The specific challenge was to reduce distortion in such a way that subsequent machining operations are entirely eliminated. As a result of extensive development in the quenching process, it was possible to meet the design metrological requirements. The internal ring gears have been in continuous production since 2006. By utilizing the special CFC fixtures and quench methodology of "Dynamic Quenching," the customer was able to achieve the design intent, while eliminating all machining operations of the ring gears following LPC/HPGQ. Subsequent testing and monitoring over a 2-year period progressively demonstrated that conformance. Therefore, quality inspection was reduced accordingly.

  6. Parametric Study On The CW Nd: YAG Laser Cutting Quality Of 1.25 mm Ultra Low Carbon Steel Sheets Using O2 Assist Gas

    NASA Astrophysics Data System (ADS)

    Salem, Hanadi G.; Abbas, Wafaa A.; Mansour, Mohy S.; Badr, Yehia A.

    2007-02-01

    There are many non-linear interaction factors responsible for the performance of the laser cutting process. Identification of the dominant factors that significantly affect the cut quality is important. In the current research, the gas pressure, laser power and scanning speed were selected as the cutting parameters. Effect of the cutting parameters on the cut quality was investigated, by monitoring the variation in hardness, oxide layer width and microstructural changes within the heat affected zone (HAZ). Results revealed that good quality cuts can be produced in ultra low carbon steel thin sheets, using CW Nd:YAG laser at a window of scanning speed ranging from 1100-1500 mm/min at a minimum heat input of 337watts under an assisting O2 gas pressure of 5 bar. Higher laser power resulted in either strengthening or softening in the HAZ surrounding the cut kerf. The oxide layer width is not affected by the energy density input but rather affected by the O2 gas pressure due to exothermal reaction.

  7. Effort Optimization in Minimizing Food Related Greenhouse Gas Emissions, a look at "Organic" and "Local"

    NASA Astrophysics Data System (ADS)

    Bowen, E.; Martin, P. A.; Eshel, G.

    2008-12-01

    The adverse environmental effects, especially energy use and resultant GHG emissions, of food production and consumption are becoming more widely appreciated and increasingly well documented. Our insights into the thorny problem of how to mitigate some of those effects, however, are far less evolved. Two of the most commonly advocated strategies are "organic" and "local", referring, respectively, to growing food without major inputs of fossil fuel based synthetic fertilizers and pesticides and to food consumption near its agricultural origin. Indeed, both agrochemical manufacture and transportation of produce to market make up a significant percentage of energy use in agriculture. While there can be unique environmental benefits to each strategy, "organic" and "local" each may potentially result in energy and emissions savings relative to conventionally grown produce. Here, we quantify the potential energy and greenhouse gas emissions savings associated with "organic" and "local". We take note of energy use and actual GHG costs of the major synthetic fertilizers and transportation by various modes routinely employed in agricultural distribution chains, and compare them for ~35 frequently consumed nutritional mainstays. We present new, current, lower-bound energy and greenhouse gas efficiency estimates for these items and compare energy consumption and GHG emissions incurred during producing those food items to consumption and emissions resulting from transporting them, considering travel distances ranging from local to continental and transportation modes ranging from (most efficient) rail to (least efficient) air. In performing those calculations, we demonstrate the environmental superiority of either local or organic over conventional foods, and illuminate the complexities involved in entertaining the timely yet currently unanswered, and previously unanswerable, question of "Which is Environmentally Superior, Organic or Local?". More broadly, we put forth a

  8. Optimal sensor locations for the backward lagrangian stochastic technique in measuring lagoon gas emission.

    PubMed

    Ro, Kyoung S; Stone, Kenneth C; Johnson, Melvin H; Hunt, Patrick G; Flesch, Thomas K; Todd, Richard W

    2014-07-01

    This study evaluated the impact of gas concentration and wind sensor locations on the accuracy of measuring gas emission rates from a lagoon environment using the backward Lagrangian stochastic (bLS) inverse-dispersion technique. Path-integrated concentrations (PICs) and three-dimensional (3D) wind vector data were collected at different locations within the lagoon landscape. A floating 45 m × 45 m perforated pipe network on an irrigation pond was used as a synthetic distributed emission source for the controlled release of methane. A total of 961 15-min datasets were collected under different atmospheric stability conditions over a 2-yr period. The PIC location had a significant impact on the accuracy of the bLS technique. The location of the 3D sonic anemometer was generally not a factor for the measured accuracies with the PIC positioned on the downwind berm. The PICs across the middle of the pond consistently produced the lowest accuracy with any of the 3D anemometer locations (<69% accuracy). The PICs located on the downwind berm consistently yielded the best bLS accuracy regardless of whether the 3D sonic anemometer was located on the upwind, side, or downwind berm (accuracies ranged from 79 to 108%). The accuracies of the emission measurements with the berm PIC-berm 3D setting were statistically similar to that found in a more ideal homogeneous grass field. Considering the practical difficulties of setting up equipment and the accuracies associated with various sensor locations, we recommend that wind and concentration sensors be located on the downwind berm.

  9. Tribological composition optimization of chromium-carbide-based solid lubricant coatings for foil gas bearings at temperatures to 650 C

    NASA Technical Reports Server (NTRS)

    Dellacorte, Christopher

    1988-01-01

    The determination of the tribilogically optimum composition of chromium-carbide-based solid lubricant coatings using a foil gas bearing test apparatus is described. The coatings contain a wear resistant chromium carbide `base stock' with the lubricant additives silver and BaF2-CaF2 eutectic. The coating composition is optimized for air-lubricated foil gas bearings at temperatures ranging from 25 to 650 C. The various compositions were prepared by powder blending, then plasma sprayed onto Inconel 718 test journals and diamond ground to the desired coating thickness and surface finish. The journals were operated against preoxidized Ni-Cr alloy foils, and the test bearings were subjected to repeated start-stop cycles under a bearing unit of 14 kPa. Sliding contact between the coated journal and the smooth foil occurs during bearing start-up before lift-off or hydrodynamic lubrication by the air film and during bearing coast-down. The bearings were tested for 9000 start-stop cycles or until specimen reached a predetermined failure level.

  10. Optimization of microwave-assisted FeCl3 pretreatment conditions of rice straw and utilization of Trichoderma viride and Bacillus pumilus for production of reducing sugars.

    PubMed

    Lü, Jiliang; Zhou, Peijiang

    2011-07-01

    In this study, Box-Behnken design (BBD) and response surface methodology (RSM) were used to optimize microwave-assisted FeCl(3) pretreatment conditions of rice straw with respect to FeCl(3) concentration, microwave intensity, irradiation time and substrate concentration. When rice straw was pretreated at the optimal conditions of FeCl(3) concentration, 0.14 mol/L; microwave intensity, 160°C; irradiation time, 19 min; substrate concentration, 109 g/L; and inoculated with Trichoderma viride and Bacillus pumilus, the production of reducing sugars was 6.62 g/L. This yield was 2.9 times higher than that obtained with untreated rice straw. The microorganisms degraded 37.8% of pretreated rice straw after 72 h. The structural characteristic analyses suggest that microwave-assisted FeCl(3) pretreatment damaged the silicified waxy surface of rice straw, disrupted almost all the ether linkages between lignin and carbohydrates, and removed lignin.

  11. Trajectory design to L4 and L5 libiration point in the Earth-Moon system using lunar gravity assistance and orbit optimization

    NASA Astrophysics Data System (ADS)

    Zhang, ZhengTao; Tang, Jingshi; Liu, Lin

    There has some application prospects of the stable libration point L4 and L5 of the Earth-Moon system in deep space exploration,such as VLBI.The transfer strategy is from LEO to L4 or L5 libration point with the lunar gravity assistance,which saves energy compared to the traditional Hohmann transfer strategy.The high-order analysis solution of period orbit around L4 libration point is applied to express the target orbit.Then by changing the velocity of a given point on the target orbit and doing reverse integration the probe reaches the perilune patched by a Hohmann transfer orbit from LEO with different velocity.By utilizing the global optimization method PSO and local SQP method,we optimize the transfer orbit. This powered lunar gravity assistance method is applied in the transfer from L2 to L4 and L5 libration point with invariant manifolds,which sloves the problem that the unstable manifold of L2 cannot reach L4 and L5.

  12. Performance assessment and optimization of an irreversible nano-scale Stirling engine cycle operating with Maxwell-Boltzmann gas

    NASA Astrophysics Data System (ADS)

    Ahmadi, Mohammad H.; Ahmadi, Mohammad-Ali; Pourfayaz, Fathollah

    2015-09-01

    Developing new technologies like nano-technology improves the performance of the energy industries. Consequently, emerging new groups of thermal cycles in nano-scale can revolutionize the energy systems' future. This paper presents a thermo-dynamical study of a nano-scale irreversible Stirling engine cycle with the aim of optimizing the performance of the Stirling engine cycle. In the Stirling engine cycle the working fluid is an Ideal Maxwell-Boltzmann gas. Moreover, two different strategies are proposed for a multi-objective optimization issue, and the outcomes of each strategy are evaluated separately. The first strategy is proposed to maximize the ecological coefficient of performance (ECOP), the dimensionless ecological function (ecf) and the dimensionless thermo-economic objective function ( F . Furthermore, the second strategy is suggested to maximize the thermal efficiency ( η), the dimensionless ecological function (ecf) and the dimensionless thermo-economic objective function ( F). All the strategies in the present work are executed via a multi-objective evolutionary algorithms based on NSGA∥ method. Finally, to achieve the final answer in each strategy, three well-known decision makers are executed. Lastly, deviations of the outcomes gained in each strategy and each decision maker are evaluated separately.

  13. An inexact dynamic optimization model for municipal solid waste management in association with greenhouse gas emission control.

    PubMed

    Lu, H W; Huang, G H; He, L; Zeng, G M

    2009-01-01

    Municipal solid waste (MSW) should be properly disposed in order to help protect environmental quality and human health, as well as to preserve natural resources. During MSW disposal processes, a large amount of greenhouse gas (GHG) is emitted, leading to a significant impact on climate change. In this study, an inexact dynamic optimization model (IDOM) is developed for MSW-management systems under uncertainty. It grounds upon conventional mixed-integer linear programming (MILP) approaches, and integrates GHG components into the modeling framework. Compared with the existing models, IDOM can not only deal with the complex tradeoff between system cost minimization and GHG-emission mitigation, but also provide optimal allocation strategies under various emission-control standards. A case study is then provided for demonstrating applicability of the developed model. The results indicate that desired waste-flow patterns with a minimized system cost and GHG-emission amount can be obtained. Of more importance, the IDOM solution is associated with over 5.5 million tonnes of TEC reduction, which is of significant economic implication for real implementations. Therefore, the proposed model could be regarded as a useful tool for realizing comprehensive MSW management with regard to mitigating climate-change impacts.

  14. Drought limitations to leaf-level gas exchange: results from a model linking stomatal optimization and cohesion-tension theory.

    PubMed

    Novick, Kimberly A; Miniat, Chelcy F; Vose, James M

    2016-03-01

    We merge concepts from stomatal optimization theory and cohesion-tension theory to examine the dynamics of three mechanisms that are potentially limiting to leaf-level gas exchange in trees during drought: (1) a 'demand limitation' driven by an assumption of optimal stomatal functioning; (2) 'hydraulic limitation' of water movement from the roots to the leaves; and (3) 'non-stomatal' limitations imposed by declining leaf water status within the leaf. Model results suggest that species-specific 'economics' of stomatal behaviour may play an important role in differentiating species along the continuum of isohydric to anisohydric behaviour; specifically, we show that non-stomatal and demand limitations may reduce stomatal conductance and increase leaf water potential, promoting wide safety margins characteristic of isohydric species. We used model results to develop a diagnostic framework to identify the most likely limiting mechanism to stomatal functioning during drought and showed that many of those features were commonly observed in field observations of tree water use dynamics. Direct comparisons of modelled and measured stomatal conductance further indicated that non-stomatal and demand limitations reproduced observed patterns of tree water use well for an isohydric species but that a hydraulic limitation likely applies in the case of an anisohydric species.

  15. Optimization of operating parameters for gas-phase photocatalytic splitting of H2S by novel vermiculate packed tubular reactor.

    PubMed

    Preethi, V; Kanmani, S

    2016-10-01

    Hydrogen production by gas-phase photocatalytic splitting of Hydrogen Sulphide (H2S) was investigated on four semiconductor photocatalysts including CuGa1.6Fe0.4O2, ZnFe2O3, (CdS + ZnS)/Fe2O3 and Ce/TiO2. The CdS and ZnS coated core shell particles (CdS + ZnS)/Fe2O3 shows the highest rate of hydrogen (H2) production under optimized conditions. Packed bed tubular reactor was used to study the performance of prepared photocatalysts. Selection of the best packing material is a key for maximum removal efficiency. Cheap, lightweight and easily adsorbing vermiculate materials were used as a novel packing material and were found to be effective in splitting H2S. Effect of various operating parameters like flow rate, sulphide concentration, catalyst dosage, light irradiation were tested and optimized for maximum H2 conversion of 92% from industrial waste H2S.

  16. Ultrasound-assisted alkaline pretreatment of sugarcane bagasse for fermentable sugar production: optimization through response surface methodology.

    PubMed

    Velmurugan, Rajendran; Muthukumar, Karuppan

    2012-05-01

    Ultrasound-assisted alkaline pretreatment of sugarcane bagasse (SCB) for fermentable sugar production was carried out and the influence of particle size, liquid to solid ratio (LSR), NaOH concentration, temperature and sonication time on delignification and reducing sugar production was ascertained with Placket-Burman design. The best combination of each significant factor was determined by a central composite design (CCD) and optimum pretreatment conditions for maximum reducing sugar yield (96.27%) were particle size of 0.27 mm, LSR of 25 ml/g, NaOH concentration of 2.89% (w/v), temperature of 70.15°C and pretreatment time of 47.42 min. Under these conditions, 92.11% of theoretical reducing sugar yield was observed experimentally. The substantial reduction in pretreatment time and temperature with improved efficiency is the most attractive features of the ultrasound-assisted alkaline pretreatment.

  17. OPTIMIZING TECHNOLOGY TO REDUCE MERCURY AND ACID GAS EMISSIONS FROM ELECTRIC POWER PLANTS

    SciTech Connect

    Jeffrey C. Quick; David E. Tabet; Sharon Wakefield; Roger L. Bon

    2005-10-01

    Maps showing potential mercury, sulfur, chlorine, and moisture emissions for U.S. coal by county of origin were made from publicly available data (plates 1, 2, 3, and 4). Published equations that predict mercury capture by emission control technologies used at U.S. coal-fired utilities were applied to average coal quality values for 169 U.S. counties. The results were used to create five maps that show the influence of coal origin on mercury emissions from utility units with: (1) hot-side electrostatic precipitator (hESP), (2) cold-side electrostatic precipitator (cESP), (3) hot-side electrostatic precipitator with wet flue gas desulfurization (hESP/FGD), (4) cold-side electrostatic precipitator with wet flue gas desulfurization (cESP/FGD), and (5) spray-dry adsorption with fabric filter (SDA/FF) emission controls (plates 5, 6, 7, 8, and 9). Net (lower) coal heating values were calculated from measured coal Btu values, and estimated coal moisture and hydrogen values; the net heating values were used to derive mercury emission rates on an electric output basis (plate 10). Results indicate that selection of low-mercury coal is a good mercury control option for plants having hESP, cESP, or hESP/FGD emission controls. Chlorine content is more important for plants having cESP/FGD or SDA/FF controls; optimum mercury capture is indicated where chlorine is between 500 and 1000 ppm. Selection of low-sulfur coal should improve mercury capture where carbon in fly ash is used to reduce mercury emissions. Comparison of in-ground coal quality with the quality of commercially mined coal indicates that existing coal mining and coal washing practice results in a 25% reduction of mercury in U.S. coal before it is delivered to the power plant. Further pre-combustion mercury reductions may be possible, especially for coal from Texas, Ohio, parts of Pennsylvania and much of the western U.S.

  18. Optimal use of buffer volumes for the measurement of atmospheric gas concentration in multi-point systems

    NASA Astrophysics Data System (ADS)

    Cescatti, Alessandro; Marcolla, Barbara; Goded, Ignacio; Gruening, Carsten

    2016-09-01

    Accurate multi-point monitoring systems are required to derive atmospheric measurements of greenhouse gas concentrations both for the calculation of surface fluxes with inversion transport models and for the estimation of non-turbulent components of the mass balance equation (i.e. advection and storage fluxes) at eddy covariance sites. When a single analyser is used to monitor multiple sampling points, the deployment of buffer volumes (BVs) along sampling lines can reduce the uncertainty due to the discrete temporal sampling of the signal. In order to optimize the use of buffer volumes we explored various set-ups by simulating their effect on time series of high-frequency CO2 concentration collected at three Fluxnet sites. Besides, we proposed a novel scheme to calculate half-hourly weighted arithmetic means from discrete point samples, accounting for the probabilistic fraction of the signal generated in the averaging period. Results show that the use of BVs with the new averaging scheme reduces the mean absolute error (MAE) up to 80 % compared to a set-up without BVs and up to 60 % compared to the case with BVs and a standard, non-weighted averaging scheme. The MAE of CO2 concentration measurements was observed to depend on the variability of the concentration field and on the size of BVs, which therefore have to be carefully dimensioned. The optimal volume size depends on two main features of the instrumental set-up: the number of measurement points and the time needed to sample at one point (i.e. line purging plus sampling time). A linear and consistent relationship was observed at all sites between the sampling frequency, which summarizes the two features mentioned above, and the renewal frequency associated with the volume. Ultimately, this empirical relationship can be applied to estimate the optimal volume size according to the technical specifications of the sampling system.

  19. Quantification of fatty acids in the muscle of Antarctic fish Trematomus bernacchii by gas chromatography-mass spectrometry: Optimization of the analytical methodology.

    PubMed

    Truzzi, C; Illuminati, S; Annibaldi, A; Antonucci, M; Scarponi, G

    2017-04-01

    This work presents data on the quantification of fatty acids (FAs, in terms of mass unit per tissue weight) in the muscle of Trematomus bernacchii, a key species in Antarctica, often used as bioindicator for contamination studies. Modifications in fatty acids content should be considered a useful biomarker to study how contaminants affect Antarctic biota. Until now, very few studies quantified fatty acids of muscle of T. bernacchii, and only as percentage of a single fatty acid on total lipids. To perform the quantification of fatty acids, we used an analytical method based on a fast microwave-assisted extraction of lipids from a lyophilized sample, a base-catalyzed trans-esterification of lipid extract to obtain Fatty Acids Methyl Esters (FAMEs), and a separation and identification of FAMEs by gas chromatography-mass spectrometry. With the optimized and validated method, a fast and accurate separation of Fatty Acids Methyl Esters was performed in 43 min. The linearity was checked up to about 320 μg mL(-1); limit of detection and limit of quantification are in the range 4-22 μg mL(-1) and 13-66 μg mL(-1), respectively. The optimized method showed a good accuracy and precision. Major fatty acids were 14:0, 16:0, 16:1n7, 18:1n9, 18:1n7, 20:1n9, 20:5n3 and 22:6n3. Quantified FAs compute for about 47 mg g(-1) tissue dry weight (dw), with 9.1 ± 0.1 mg g(-1) dw of saturated FAs, 25.5 ± 0.1 mg g(-1) dw of mono-unsaturated FAs, and 12.2 ± 0.1 mg g(-1) dw of poly-unsaturated FAs.

  20. Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment.

    PubMed

    Balakrishnan, Madhesan; Sacia, Eric R; Sreekumar, Sanil; Gunbas, Gorkem; Gokhale, Amit A; Scown, Corinne D; Toste, F Dean; Bell, Alexis T

    2015-06-23

    Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a method for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We also demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%.

  1. Naturally fractured tight gas reservoir detection optimization. Annual report, August 1994--July 1995

    SciTech Connect

    1995-09-01

    This report details the field work undertaken Blackhawk Geosciences and Lynn, Inc. during August 1994 to July 1995 at a gas field in the Wind River Basin in central Wyoming. The work described herein consisted of four parts: 9C VSP in a well at the site; additional processing of the previously recorded 3D P-wave survey on the site and Minivibrator testing; and planning and acquisition of a 3-D, 3-C seismic survey. The objectives of all four parts were to characterize the nature of anisotropy in the reservoir. With the 9C VSP, established practices were used to achieve this objective in the immediate vicinity of the well. The additional processing of the 3-D uses developmental techniques to determine areas of fractures in 3-D surveys. With the multicomponent studies, tests were conducted to establish the feasibility of surface recording of the anisotropic reservoir rocks. The 3-D, 3-C survey will provide both compressional and shear wave data sets over areas of known fracturing to verify the research.

  2. Gas chromatographic quantitative analysis of methanol in wine: operative conditions, optimization and calibration model choice.

    PubMed

    Caruso, Rosario; Gambino, Grazia Laura; Scordino, Monica; Sabatino, Leonardo; Traulo, Pasqualino; Gagliano, Giacomo

    2011-12-01

    The influence of the wine distillation process on methanol content has been determined by quantitative analysis using gas chromatographic flame ionization (GC-FID) detection. A comparative study between direct injection of diluted wine and injection of distilled wine was performed. The distillation process does not affect methanol quantification in wines in proportions higher than 10%. While quantification performed on distilled samples gives more reliable results, a screening method for wine injection after a 1:5 water dilution could be employed. The proposed technique was found to be a compromise between the time consuming distillation process and direct wine injection. In the studied calibration range, the stability of the volatile compounds in the reference solution is concentration-dependent. The stability is higher in the less concentrated reference solution. To shorten the operation time, a stronger temperature ramp and carrier flow rate was employed. With these conditions, helium consumption and column thermal stress were increased. However, detection limits, calibration limits, and analytical method performances are not affected substantially by changing from normal to forced GC conditions. Statistical data evaluation were made using both ordinary (OLS) and bivariate least squares (BLS) calibration models. Further confirmation was obtained that limit of detection (LOD) values, calculated according to the 3sigma approach, are lower than the respective Hubaux-Vos (H-V) calculation method. H-V LOD depends upon background noise, calibration parameters and the number of reference standard solutions employed in producing the calibration curve. These remarks are confirmed by both calibration models used.

  3. Optimizing detection of noble gas emission at a former UNE site: sample strategy, collection, and analysis

    NASA Astrophysics Data System (ADS)

    Kirkham, R.; Olsen, K.; Hayes, J. C.; Emer, D. F.

    2013-12-01

    Underground nuclear tests may be first detected by seismic or air samplers operated by the CTBTO (Comprehensive Nuclear-Test-Ban Treaty Organization). After initial detection of a suspicious event, member nations may call for an On-Site Inspection (OSI) that in part, will sample for localized releases of radioactive noble gases and particles. Although much of the commercially available equipment and methods used for surface and subsurface environmental sampling of gases can be used for an OSI scenario, on-site sampling conditions, required sampling volumes and establishment of background concentrations of noble gases require development of specialized methodologies. To facilitate development of sampling equipment and methodologies that address OSI sampling volume and detection objectives, and to collect information required for model development, a field test site was created at a former underground nuclear explosion site located in welded volcanic tuff. A mixture of SF-6, Xe127 and Ar37 was metered into 4400 m3 of air as it was injected into the top region of the UNE cavity. These tracers were expected to move towards the surface primarily in response to barometric pumping or through delayed cavity pressurization (accelerated transport to minimize source decay time). Sampling approaches compared during the field exercise included sampling at the soil surface, inside surface fractures, and at soil vapor extraction points at depths down to 2 m. Effectiveness of various sampling approaches and the results of tracer gas measurements will be presented.

  4. Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment

    DOE PAGES

    Balakrishnan, Madhesan; Sacia, Eric R.; Sreekumar, Sanil; ...

    2015-06-08

    Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a methodmore » for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%.« less

  5. Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment

    SciTech Connect

    Balakrishnan, Madhesan; Sacia, Eric R.; Sreekumar, Sanil; Gunbas, Gorkem; Gokhale, Amit A.; Scown, Corinne D.; Toste, F. Dean; Bell, Alexis T.

    2015-06-08

    Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a method for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%.

  6. Optimized working conditions for a thermoelectric generator as a topping cycle for gas turbines

    NASA Astrophysics Data System (ADS)

    Brady Knowles, C.; Lee, Hohyun

    2012-10-01

    This paper presents a model for a theoretical maximum efficiency of a thermoelectric generator integrated with a Brayton-cycle engine. The thermoelectric cycle is presented in two configurations as a topping cycle and a preheating topping cycle. For the topping cycle configuration, the thermoelectric generator receives heat from a high-temperature heat source and produces electrical work before rejecting heat to a Brayton cycle. For the preheating topping cycle, the rejected heat from the thermoelectric generator partially heats the compressed working fluid of the Brayton cycle before a secondary heater delivers heat to the working fluid directly from the heat source. The thermoelectric topping cycle efficiency increases as the temperature difference between the hot- and cold-side increases; however, this limits the heat transfer possible to the Brayton cycle, which in turn reduces power generation from the Brayton cycle. This model identifies the optimum operating parameters of the thermoelectric and Brayton cycles to obtain the maximum thermal efficiency of the combined cycle. In both configurations, efficiency gains are larger at low-temperature Brayton cycles. Although a thermoelectric generator (TEG) topping cycle enhances efficiency for a low temperature turbine, efficiency cannot exceed a high temperature gas turbine. Using a TEG topping cycle is limited to cases when space or price for a high temperature turbine cannot be justified. A design to achieve the preheating thermoelectric topping cycle is also presented.

  7. Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment

    PubMed Central

    Balakrishnan, Madhesan; Sacia, Eric R.; Sreekumar, Sanil; Gunbas, Gorkem; Gokhale, Amit A.; Scown, Corinne D.; Toste, F. Dean; Bell, Alexis T.

    2015-01-01

    Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a method for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We also demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%. PMID:26056307

  8. Optimization of an oxide dispersion strengthened Ni-Cr-Al alloy for gas turbine engine vanes

    NASA Technical Reports Server (NTRS)

    Klarstrom, D. L.; Grierson, R.

    1975-01-01

    The investigation was carried out to determine the optimum alloy within the Ni-16Cr-Al-Y2O3 system for use as a vane material in advanced aircraft gas turbine engines. Six alloys containing nominally 4%, 5% and 6% Al with Y2O3 levels of 0.8% and 1.2% were prepared by mechanical attrition. Six small-scale, rectangular extrusions were produced from each powder lot for property evaluation. The approximate temperatures for incipient melting were found to be 1658 K (2525 F), 1644 K (2500 F) and 1630 K (2475 F) for the 4%, 5% and 6% aluminum levels, respectively. With the exception of longitudinal crystallographic texture, the eight extrusions selected for extensive evaluation either exceeded or were close to mechanical property goals. Major differences between the alloys became apparent during dynamic oxidation testing, and in particular during the 1366 K (2000 F)/500 hour Mach 1 tests carried out by NASA-Lewis. An aluminum level of 4.75% was subsequently judged to be optimum based on considerations of dynamic oxidation resistance, susceptibility to thermal fatigue cracking and melting point.

  9. Optimizing Techology to Reduce Mercury and Acid Gas Emissions from Electric Power Plants

    SciTech Connect

    Jeffrey C. Quick; David E. Tabet; Sharon Wakefield; Roger L. Bon

    2004-01-31

    More than 56,000 coal quality data records from five public data sets have been selected for use in this project. These data will be used to create maps showing where coals with low mercury and acid-gas emissions might be found for power plants classified by air-pollution controls. Average coal quality values, calculated for 51,156 commercial coals by U.S. county-of-origin, are listed in the appendix. Coal moisture values are calculated for commercially shipped coal from 163 U.S. counties, where the raw assay data (including mercury and chlorine values) are reported on a dry basis. The calculated moisture values are verified by comparison with observed moisture values in commercial coal. Moisture in commercial U.S. coal shows provincial variation. For example, high volatile C bituminous rank coal from the Interior province has 3% to 4% more moisture than equivalent Rocky Mountain province coal. Mott-Spooner difference values are calculated for 4,957 data records for coals collected from coal mines and exploration drill holes. About 90% of the records have Mott-Spooner difference values within {+-}250 Btu/lb.

  10. Optimization studies on TFC membrane for Membrane Gas Absorption (MGA) application

    NASA Astrophysics Data System (ADS)

    Sunarti, A. R.; Ahmad, A. L.

    2013-06-01

    A thin film composite (TFC) membrane has been developed by coating polydimethylsiloxane (PDMS) and glutaraldehyde (GH) on a surface porous polyvinylideneflouride (PVDF) membrane for membrane gas absorption (MGA) application. The optimum conditions for dip coating method were determined using response surface methodology (RSM). A central composite design (CCD) was used to investigate the effects of two independent factors, which PDMS concentrations (wt%) and dipping time (s) of GH on the four specific responses which are CO2 and N2 permeances, selectivity and contact angle (CA) value. The optimum conditions for PDMS concentration and GH dipping time are 10 wt% and 19 s, respectively where 354 GPU for CO2 permeance, 66 GPU for N2 permeance, 5.4 of selectivity and 132° of CA value were obtained. Through atomic force microscopy (AFM) analysis, the result shown the root mean square roughness (Rms) of the TFC membrane was 381 nm and it was double from untreated membrane Rms value. Therefore, the roughness of the surface membrane contributed to the performance of the separation in the process flow such as in MGA application. By coating PDMS, hydrophobicity of the surface membrane was improved as well

  11. Optimization of ultrasonic-assisted extraction (UAE) of betulin from white birch bark using response surface methodology.

    PubMed

    Chen, Qi-he; Fu, Ming-liang; Liu, Jin; Zhang, Hai-feng; He, Guo-qing; Ruan, Hui

    2009-06-01

    Betulin is an abundant naturally occurring triterpene, which makes it a potentially important raw material for a precursor of biologically active compounds. The objective of the current study was to determine the optimum UAE conditions for betulin from B. papyfera bark. The optimum conditions were evaluated with fractional factorial design and optimized using response surface methodology. High yields of betulin were observed from white birch bark by UAE technology. The solvent concentration and the ratio of material to solvent were the most significant parameters on betulin extraction as evaluated through FFD. The extraction conditions were further investigated with central composite design. The fitted second-order model revealed that the optimal conditions consisted of 98% ethonal concentration, 1:42 the ratio of white birch bark to solvent, extraction temperature 50 degrees C, ultrasonic frequency 5kHz and extraction time 3h. Under the optimized condition, the maximum productivity of betulin predicted is 23.17%. The extraction productivity and purity of betulin under the optimized extraction conditions were great higher than that of the non-optimized condition. The present study demonstrates that ultrasound is a great efficiency tool for the fast extraction of betulin from white birch bark.

  12. Assistance in Determining BACT for Simple-Cycle Natural Gas Turbine Peaker Project Proposed by Standard Energy Ventures

    EPA Pesticide Factsheets

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  13. Bio-guided optimization of the ultrasound-assisted extraction of compounds from Annona glabra L. leaves using the etiolated wheat coleoptile bioassay.

    PubMed

    Matsumoto, Sadao; Varela, Rosa M; Palma, Miguel; Molinillo, José M G; Lima, Inês S; Barroso, Carmelo G; Macías, Francisco A

    2014-07-01

    A bio-guided optimization of the extraction of bioactive components from Annona glabra leaves has been developed using the etiolated wheat coleoptile bioassay as the control method. The optimization of an ultrasound-assisted extraction of bioactive compounds using allelopathy results as target values has been carried out for the first time. A two-level fractional factorial experimental design was applied to optimize the ultrasound-assisted extraction. The solvent was the extraction variable that had the most marked effect on the resulting bioactivity of the extracts in the etiolated wheat coleoptile bioassay. Extraction time, extraction temperature and the size of the ultrasonic probe also influenced the bioactivity of the extracts. A larger scale extraction was carried out in the next step in the allelopathic study, i.e., the isolation of compounds from the bioactive extract and chemical characterization by spectroscopic techniques, including NMR. Eight compounds were isolated and identified from the active extracts, namely two steroids (β-sistosterol and stigmasterol), five diterpenes with the kaurane skeleton (ent-kaur-16-en-19-oic acid, ent-19-methoxy-19-oxokauran-17-oic acid, annoglabasin B, ent-17-hydroxykaur-15-en-19-oic acid and ent-15β,16β-epoxy-17-hydroxy-kauran-19-oic acid) and the acetogenin asimicin. The most active compound was annoglabasin B, which showed inhibition with values of -95% at 10(-3) M, -87% at 5×10(-4) M and greater than -70% at 10(-4) M in the etiolated wheat coleoptile bioassay.

  14. Combination of accelerated solvent extraction and vortex-assisted liquid-liquid microextraction for the determination of dimethyl fumarate in textiles and leathers by gas chromatography-mass spectrometry.

    PubMed

    Lu, Yang; Zhu, Yan

    2014-02-01

    A simple and environmentally friendly sample preparation procedure coupled with gas chromatography-mass spectrometry was developed to assay dimethyl fumarate in textiles and leathers. The sample preparation procedure involved an accelerated solvent extraction (ASE) using water as the extract solvent, followed by the extraction and concentration of dimethyl fumarate from the aqueous solution using vortex-assisted liquid-liquid microextraction (VALLME). The parameters affecting the ASE and VALLME were optimized to achieve the maximum extraction efficiency, and the performance of the developed method was evaluated. Good linearity was observed over the range assayed (0.01-1mg/kg) with a regression coefficient of 0.998. The limit of detection and enrichment factor for the VALLME step were 0.001 mg/kg and 53, respectively. The intra- and inter-day precision were below 8.9%, and the recovery was approximately 84-103%. The as-developed method was successfully applied to textiles and leather samples.

  15. [Ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction for the determination of eight drugs in biological samples by gas chromatography-triple quadrupole mass spectrometry].

    PubMed

    Meng, Liang; Zhu, Binling; Zheng, Kefang; Zhang, Wenwen; Meng, Pinjia

    2015-03-01

    A novel microextraction technique based on ultrasound-assisted low-density solvent dispersive liquid-liquid microextraction (UA-LDS-DLLME) has been developed for the determination of multiple drugs of abuse in biological samples by gas chromatography-triple quadrupole mass spectrometry (GC-QQQ-MS). A total of 100 µL of toluene as extraction solvent was dropped into the sample solution. Then the mixture was sonicated drastically in an ultrasonic bath for 3 min with occasional manual shaking to form a cloudy suspension. After centrifugation at 10,000 r/min for 3 min, the upper layer of low-density extractant was withdrawn and injected into the GC-QQQ-MS for analysis. The parameters affecting extraction efficiency have been investigated and optimized. Under the optimum conditions, good linearities were observed for all analytes with the correlation coefficients ranging from 0. 998 4 to 0. 999 4. The recoveries of 79.3%-100.3% with RSDs < 5.7% were obtained. The LODs (S/N = 3) were in the range from 0.05 to 0.40 µg/L. UA-LDS-DLLME technique has the advantages of less extraction time, suitable for batches of sample pretreatment simultaneously, and higher extraction efficiency. It was successfully applied to the analysis of amphetamines in real human urine samples.

  16. Comparative study of matrix-assisted laser desorption/ionization and gas chromatography for quantitative determination of cocoa butter and cocoa butter equivalent triacylglycerol composition.

    PubMed

    Guyon, F; Absalon, Ch; Eloy, A; Salagoity, M H; Esclapez, M; Medina, B

    2003-01-01

    The triacylglycerol (TAG) composition study of cocoa butter (CB) and cocoa butter equivalents (CBEs) has been performed by gas chromatography (GC) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). These two techniques provided comparable results. The advantage of the MALDI technique was the detection of each compound comprising the triacylglycerol classes (Cn). Moreover, comparison of the data obtained by these two techniques indicated that TAG relative percentages could be obtained quantitatively with the MALDI technique. These techniques have been applied for the composition determination of CB + CBE mixtures. Encouraging results showed that it is possible to quantify an admixture containing as little as 4% of CBE.

  17. Automated fast extraction of nitrated polycyclic aromatic hydrocarbons from soil by focused microwave-assisted Soxhlet extraction prior to gas chromatography--electron-capture detection.

    PubMed

    Priego-Capote, F; Luque-García, J L; Luque de Castro, M D

    2003-04-25

    An approach for the automated fast extraction of nitrated polycyclic aromatic hydrocarbons (nitroPAHs) from soil, using a focused microwave-assisted Soxhlet extractor, is proposed. The main factors affecting the extraction efficiency (namely: irradiation power, irradiation time, number of cycles and extractant volume) were optimised by using experimental design methodology. The reduction of the nitro-PAHs to amino-PAHs and the derivatisation of the reduced analytes with heptafluorobutyric anhydride was mandatory prior to the separation-determination step by gas chromatography--electron-capture detection. The proposed approach has allowed the extraction of these pollutants from spiked and "real" contaminated soils with extraction efficiencies similar to those provided by the US Environmental Protection Agency methods 3540-8091, but with a drastic reduction in both the extraction time and sample handling, and using less organic solvent, as 75-85% of it was recycled.

  18. Biosynthesis of Gold Nanoparticles and Identification of Capping Agent Using Gas Chromatography-Mass Spectrometry and Matrix Assisted Laser Desorption Ionization-Mass Spectrometry.

    PubMed

    Karthick, V; Kumar, V Ganesh; Dhas, T Stalin; Govindaraju, K; Sinha, Sweta; Singaravelu, G

    2015-06-01

    In the present study, gold nanoparticles (AuNPs) were synthesized using leaf extract of Syzygium jambolanum and capping agent has been explored. The synthesized AuNPs have been characterized using UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HRTEM) and atomic force microscopic (AFM) analysis. The AuNPs show intense surface plasmon resonance (SPR) band at 528 nm and were found to be spherical and hexagonal in shape with particle size ranging from 20-30 nm. Transmission electron microscopy and atomic force microscopy were used to analyze the surface morphology of synthesized AuNPs. The capping ligand has been evaluated using matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) and gas chromatography-mass spectrometry (GC-MS) analysis.

  19. Determination of nonylphenol and octylphenol in paper by microwave-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    PubMed

    Latorre, A; Lacorte, S; Barceló, D; Montury, M

    2005-02-18

    A novel and simple method for the determination of active endocrine disrupter compounds (octylphenol OP, and nonylphenol NP) in paper using microwave-assisted extraction (MAE) and headspace solid-phase microextraction, coupled with gas chromatography-mass spectrometry has been developed. Parameters affecting the efficiency in the MAE process such as exposure time and extraction solvent were studied in order to determine operating conditions. The optimised method was linear over the range studied (1.25-125 microg kg(-1) for OP and 9.50-950 microg kg(-1) for NP) and showed good level of precision, with a RSD lower than 10% and detection limits at 0.10 and 4.56 microg kg(-1) for OP and NP, respectively. The results obtained from six different types of paper revealed the presence of the target compounds in all samples analysed, at levels ranging between 3 and 211 microg kg(-1).

  20. LABORATORY OPTIMIZATION TESTS OF TECHNETIUM DECONTAMINATION OF HANFORD WASTE TREATMENT PLANT LOW ACTIVITY WASTE OFF-GAS CONDENSATE SIMULANT

    SciTech Connect

    Taylor-Pashow, K.; Nash, C.; McCabe, D.

    2014-09-29

    compatible with longterm tank storage and immobilization methods. For this new application, testing is needed to demonstrate acceptable treatment sorbents and precipitating agents and measure decontamination factors for additional radionuclides in this unique waste stream. The origin of this LAW Off-Gas Condensate stream will be the liquids from the Submerged Bed Scrubber (SBS) and the Wet Electrostatic Precipitator (WESP) from the LAW melter off-gas system. The stream is expected to be a dilute salt solution with near neutral pH, and will likely contain some insoluble solids from melter carryover. The soluble components are expected to be mostly sodium and ammonium salts of nitrate, chloride, and fluoride. This stream has not been generated yet and will not be available until the WTP begins operation, but a simulant has been produced based on models, calculations, and comparison with pilot-scale tests. One of the radionuclides that is volatile and expected to be in greatest abundance in this LAW Off-Gas Condensate stream is Technetium-99 ({sup 99}Tc). Technetium will not be removed from the aqueous waste in the Hanford WTP, and will primarily end up immobilized in the LAW glass by repeated recycle of the off-gas condensate into the LAW melter. Other radionuclides that are low but are also expected to be in measurable concentration in the LAW Off-Gas Condensate are {sup 129}I, {sup 90}Sr, {sup 137}Cs, {sup 241}Pu, and {sup 241}Am. These are present due to their partial volatility and some entrainment in the off-gas system. This report discusses results of optimized {sup 99}Tc decontamination testing of the simulant. Testing examined use of inorganic reducing agents for {sup 99}Tc. Testing focused on minimizing the quantity of sorbents/reactants added, and minimizing mixing time to reach the decontamination targets in this simulant formulation. Stannous chloride and ferrous sulfate were tested as reducing agents to determine the minimum needed to convert soluble pertechnetate

  1. Microwave-assisted extraction: a simpler and faster method for the determination of ethyl glucuronide in hair by gas chromatography-mass spectrometry.

    PubMed

    Alvarez, Iván; Bermejo, Ana María; Tabernero, María Jesús; Fernández, Purificación; Cabarcos, Pamela; López, Patricia

    2009-02-01

    Alcohol is the most frequently abused "addictive substance" that causes serious social problems throughout the world; thus, alcoholism is of particular interest in clinical and forensic medicine. Alcohol biomarkers are physiological indicators of alcohol exposure or ingestion and may reflect the presence of an alcohol use disorder. The glucuronide conjugation is a minor pathway of ethanol metabolism. Ethyl glucuronide (EtG) is a marker of recent alcohol consumption that detects alcohol use reliably over a definite time period. The present paper describes a new method for the determination of EtG in hair. It is based both in the microwave-assisted extraction (MAE), to extract the analyte from hair samples, and gas chromatography-mass spectrometry (GC-MS), to identify and quantify the EtG in selected ion monitoring (SIM) mode. The method was applied to 15 hair samples from occasional alcohol users, obtaining positive results in all cases. It was fully validated, including a linear range (0.3-10 ng/mg) and the main precision parameters. In summary, the use of microwave-assisted extraction turned out to be a substantially simpler, faster, and a more sensitive procedure than any other conventional sample preparations.

  2. Polytetrafluoroethylene physisorption-assisted emulsification microextraction as a cleanup and preconcentration step in the gas chromatography determination of aliphatic hydrocarbons in marine sediment samples.

    PubMed

    Molaei, Saeideh; Saleh, Abolfazl; Ghoulipour, Vanik; Seidi, Shahram

    2017-02-01

    For the first time, the application of polytetrafluoroethylene powder as an extractant phase collector or holder in liquid-phase microextraction has been developed. For this purpose, the analytical performances of two different ways of applying polytetrafluoroethylene powder in microextraction methods including polytetrafluoroethylene physisorption-assisted emulsification microextraction and dispersive liquid-phase microextraction via polytetrafluoroethylene extractant phase holders have been compared for analysis of aliphatic hydrocarbons in aqueous phases. Under the same conditions, the former showed better extraction efficiencies over the latter and as a result, it was applied as preconcentration and cleanup step in the analysis of aliphatic hydrocarbons in sediment samples followed by gas chromatography analysis. The linearity of the polytetrafluoroethylene physisorption-assisted emulsification microextraction method was obtained over a range of 3.7 and 2000 ng/g (R(2) > 0.993). The relative standard deviations were less than 6.5% (n = 3). The limits of detection and quantification obtained by this method were 1.1-9.0 and 3.7-30 ng/g, respectively, indicating that satisfactory results were achieved by the procedure.

  3. Developments of global greenhouse gas retrieval algorithm based on Optimal Estimation Method

    NASA Astrophysics Data System (ADS)

    Kim, W. V.; Kim, J.; Lee, H.; Jung, Y.; Boesch, H.

    2013-12-01

    After the industrial revolution, atmospheric carbon dioxide concentration increased drastically over the last 250 years. It is still increasing and over than 400ppm of carbon dioxide was measured at Mauna Loa observatory for the first time which value was considered as important milestone. Therefore, understanding the source, emission, transport and sink of global carbon dioxide is unprecedentedly important. Currently, Total Carbon Column Observing Network (TCCON) is operated to observe CO2 concentration by ground base instruments. However, the number of site is very few and concentrated to Europe and North America. Remote sensing of CO2 could supplement those limitations. Greenhouse Gases Observing SATellite (GOSAT) which was launched 2009 is measuring column density of CO2 and other satellites are planned to launch in a few years. GOSAT provide valuable measurement data but its low spatial resolution and poor success rate of retrieval due to aerosol and cloud, forced the results to cover less than half of the whole globe. To improve data availability, accurate aerosol information is necessary, especially for East Asia region where the aerosol concentration is higher than other region. For the first step, we are developing CO2 retrieval algorithm based on optimal estimation method with VLIDORT the vector discrete ordinate radiative transfer model. Proto type algorithm, developed from various combinations of state vectors to find best combination of state vectors, shows appropriate result and good agreement with TCCON measurements. To reduce calculation cost low-stream interpolation is applied for model simulation and the simulation time is drastically reduced. For the further study, GOSAT CO2 retrieval algorithm will be combined with accurate GOSAT-CAI aerosol retrieval algorithm to obtain more accurate result especially for East Asia.

  4. Nitrogen dioxide observations from the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument: Retrieval algorithm and measurements during DISCOVER-AQ Texas 2013

    EPA Science Inventory

    The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument is a test bed for upcoming air quality satellite instruments that will measure backscattered ultraviolet, visible and near-infrared light from geostationary orbit. GeoTASO flew on the NASA F...

  5. A microporous Cu-MOF with optimized open metal sites and pore spaces for high gas storage and active chemical fixation of CO2.

    PubMed

    Gao, Chao-Ying; Tian, Hong-Rui; Ai, Jing; Li, Lei-Jiao; Dang, Song; Lan, Ya-Qian; Sun, Zhong-Ming

    2016-09-25

    A microporous Cu-MOF with optimized open metal sites and pore space was constructed based on a designed bent ligand; it exhibits high-capacity multiple gas storage under atmospheric pressure and efficient catalytic activity for chemical fixation of CO2 under mild conditions.

  6. Optimization of Resin Infusion Processing for Composite Pipe Key-Part and K/T Type Joints Using Vacuum-Assisted Resin Transfer Molding

    NASA Astrophysics Data System (ADS)

    Wang, Changchun; Bai, Guanghui; Yue, Guangquan; Wang, Zhuxi; Li, Jin; Zhang, Boming

    2016-10-01

    In present study, the optimization injection processes for manufacturing the composite pipe key-part and K/T type joints in vacuum-assisted resin transfer molding (VARTM) were determined by estimating the filling time and flow front shape of four kinds of injection methods. Validity of the determined process was proved with the results of a scaling-down composite pipe key-part containing of the carbon fiber four axial fabrics and a steel core with a complex surface. In addition, an expanded-size composite pipe part was also produced to further estimate the effective of the determined injection process. Moreover, the resin injection method for producing the K/T type joints via VARTM was also optimized with the simulation method, and then manufactured on a special integrated mould by the determined injection process. The flow front pattern and filling time of the experiments show good agreement with that from simulation. Cross-section images of the cured composite pipe and K/T type joints parts prove the validity of the optimized injection process, which verify the efficiency of simulation method in obtaining a suitable injection process of VARTM.

  7. Removal of cobalt ions from aqueous solutions by polymer assisted ultrafiltration using experimental design approach. part 1: optimization of complexation conditions.

    PubMed

    Cojocaru, Corneliu; Zakrzewska-Trznadel, Grazyna; Jaworska, Agnieszka

    2009-09-30

    The polymer assisted ultrafiltration process combines the selectivity of the chelating agent with the filtration ability of the membrane acting in synergy. Such hybrid process (complexation-ultrafiltration) is influenced by several factors and therefore the application of experimental design for process optimization using a reduced number of experiments is of great importance. The present work deals with the investigation and optimization of cobalt ions removal from aqueous solutions by polymer enhanced ultrafiltration using experimental design and response surface methodological approach. Polyethyleneimine has been used as chelating agent for cobalt complexation and the ultrafiltration experiments were carried out in dead-end operating mode using a flat-sheet membrane made from regenerated cellulose. The aim of this part of experiments was to find optimal conditions for cobalt complexation, i.e. the influence of initial concentration of cobalt in feed solution, polymer/metal ratio and pH of feed solution, on the rejection efficiency and binding capacity of the polymer. In this respect, the central compositional design has been used for planning the experiments and for construction of second-order response surface models applicable for predictions. The analysis of variance has been employed for statistical validation of regression models. The optimum conditions for maximum rejection efficiency of 96.65% has been figured out experimentally by gradient method and was found to be as follows: [Co(2+)](0)=65 mg/L, polymer/metal ratio=5.88 and pH 6.84.

  8. Optimization of microwave-assisted extraction for anthocyanins, polyphenols, and antioxidants from raspberry (Rubus Coreanus Miq.) using response surface methodology.

    PubMed

    Teng, Hui; Lee, Won Young; Choi, Yong Hee

    2013-09-01

    Anthocyanins (Acys), polyphenols, and antioxidants were extracted from raspberry (Rubus Coreanus Miq.) using a highly efficient microwave-assisted extraction technique. Different solvents, including methanol, ethanol, and acetone, were tested. The colors of the extracts varied from light yellow to purple red or dark red. SEM and other nutrient analyses verified that ethanol was the most favorable medium for the microwave-assisted extraction of raspberry due to its high output and low toxicity. Effects of process parameters, including microwave power, irradiation time, and solvent concentration, were investigated through response surface methodology. Canonical analysis estimated that the highest total Acys content, total polyphenols content, and antioxidant activity of raspberry were 17.93 mg cyanidin-3-O-glucoside equivalents per gram dry weight, 38.57 mg gallic acid equivalents per gram dry weight, and 81.24%, respectively. The polyphenol compositions of raspberry extract were identified by HPLC with diode array detection, and nine kinds of polyphenols were identified and quantified, revealing that chlorogenic acid, syringic acid, and rutin are the major polyphenols contained in raspberry fruits. Compared with other fruits and vegetables, raspberry contains higher Acy and polyphenol contents with stronger antioxidant activity, suggesting that raspberry fruits are a good source of natural food colorants and antioxidants.

  9. Pressure-assisted synthesis of HKUST-1 thin film on polymer hollow fiber at room temperature toward gas separation.

    PubMed

    Mao, Yiyin; Li, Junwei; Cao, Wei; Ying, Yulong; Sun, Luwei; Peng, Xinsheng

    2014-03-26

    The scalable fabrication of continuous and defect-free metal-organic framework (MOF) films on the surface of polymeric hollow fibers, departing from ceramic supported or dense composite membranes, is a huge challenge. The critical way is to reduce the growth temperature of MOFs in aqueous or ethanol solvents. In the present work, a pressure-assisted room temperature growth strategy was carried out to fabricate continuous and well-intergrown HKUST-1 films on a polymer hollow fiber by using solid copper hydroxide nanostrands as the copper source within 40 min. These HKUST-1 films/polyvinylidenefluoride (PVDF) hollow fiber composite membranes exhibit good separation performance for binary gases with selectivity 116% higher than Knudsen values via both inside-out and outside-in modes. This provides a new way to enable for scale-up preparation of HKUST-1/polymer hollow fiber membranes, due to its superior economic and ecological advantages.

  10. INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Experimental optimisation of the gas-assisted laser cutting of thick steel sheets

    NASA Astrophysics Data System (ADS)

    Malikov, A. G.; Orishich, Anatolii M.; Shulyat'ev, Viktor B.

    2009-06-01

    We report on the experimental optimisation of the oxygen-assisted CO2 laser cutting of low-carbon sheet steel 5 to 25 mm in thickness. It is shown that the cut edge roughness is minimal when the energy input per unit volume of the material removed and the incident beam power per unit sheet thickness remain constant at ~20 J mm-3 and ~200 W mm-1, respectively, over the entire range of sheet thicknesses examined. The corresponding Péclet number is Pe = 0.5. These results can be used to determine the optimal beam power and cutting speed for a particular sheet thickness. At sufficiently large thicknesses, the conditions that ensure the minimum roughness can be written in the form of relations between nondimensional parameters.

  11. Preliminary Analysis of Low-Thrust Gravity Assist Trajectories by An Inverse Method and a Global Optimization Technique.

    NASA Astrophysics Data System (ADS)

    de Pascale, P.; Vasile, M.; Casotto, S.

    The design of interplanetary trajectories requires the solution of an optimization problem, which has been traditionally solved by resorting to various local optimization techniques. All such approaches, apart from the specific method employed (direct or indirect), require an initial guess, which deeply influences the convergence to the optimal solution. The recent developments in low-thrust propulsion have widened the perspectives of exploration of the Solar System, while they have at the same time increased the difficulty related to the trajectory design process. Continuous thrust transfers, typically characterized by multiple spiraling arcs, have a broad number of design parameters and thanks to the flexibility offered by such engines, they typically turn out to be characterized by a multi-modal domain, with a consequent larger number of optimal solutions. Thus the definition of the first guesses is even more challenging, particularly for a broad search over the design parameters, and it requires an extensive investigation of the domain in order to locate the largest number of optimal candidate solutions and possibly the global optimal one. In this paper a tool for the preliminary definition of interplanetary transfers with coast-thrust arcs and multiple swing-bys is presented. Such goal is achieved combining a novel methodology for the description of low-thrust arcs, with a global optimization algorithm based on a hybridization of an evolutionary step and a deterministic step. Low thrust arcs are described in a 3D model in order to account the beneficial effects of low-thrust propulsion for a change of inclination, resorting to a new methodology based on an inverse method. The two-point boundary values problem (TPBVP) associated with a thrust arc is solved by imposing a proper parameterized evolution of the orbital parameters, by which, the acceleration required to follow the given trajectory with respect to the constraints set is obtained simply through

  12. Optimization of a corn steep medium for production of ethanol from synthesis gas fermentation by Clostridium ragsdalei.

    PubMed

    Saxena, Jyotisna; Tanner, Ralph S

    2012-04-01

    Fermentation of biomass derived synthesis gas to ethanol is a sustainable approach that can provide more usable energy and environmental benefits than food-based biofuels. The effects of various medium components on ethanol production by Clostridium ragsdalei utilizing syngas components (CO:CO(2)) were investigated, and corn steep liquor (CSL) was used as an inexpensive nutrient source for ethanol production by C. ragsdalei. Elimination of Mg(2+), NH(4) (+) and PO(4) (3-) decreased ethanol production from 38 to 3.7, 23 and 5.93 mM, respectively. Eliminating Na(+), Ca(2+), and K(+) or increasing Ca(2+), Mg(2+), K(+), NH(4) (+) and PO(4) (3-) concentrations had no effect on ethanol production. However, increased Na(+) concentration (171 mM) inhibited growth and ethanol production. Yeast extract (0.5 g l(-1)) and trace metals were necessary for growth of C. ragsdalei. CSL alone did not support growth and ethanol production. Nutrients limiting in CSL were trace metals, NH(4) (+) and reducing agent (Cys: cysteine sulfide). Supplementation of trace metals, NH(4) (+) and CyS to CSL (20 g l(-1), wet weight basis) yielded better growth and similar ethanol production as compared to control medium. Using 10 g l(-1), the nutritional limitation led to reduced ethanol production. Higher concentrations of CSL (50 and 100 g l(-1)) were inhibitory for cell growth and ethanol production. The CSL could replace yeast extract, vitamins and minerals (excluding NH(4) (+)). The optimized CSL medium produced 120 and 50 mM of ethanol and acetate, respectively. The CSL could provide as an inexpensive source of most of the nutrients required for the syngas fermentation, and thus could improve the economics of ethanol production from biomass derived synthesis gas by C. ragsdalei.

  13. Determination of triazine and chloroacetanilide herbicides in soils by microwave-assisted extraction (MAE) coupled to gas chromatographic analysis with either GC-NPD or GC-MS.

    PubMed

    Vryzas, Zisis; Papadopoulou-Mourkidou, Euphemia

    2002-08-28

    A simple and rapid method based on microwave-assisted extraction (MAE) coupled to gas chromatographic analysis was developed for the analysis of triazine (atrazine, cyanazine, metribuzine, simazine and deethylatrazine, and deisopropylatrazine) and chloroacetanilide (acetochlor, alachlor, and metolachlor) herbicide residues in soils. Soil samples are processed by MAE for 5 min at 80 degrees C in the presence of acetonitrile (20 mL/sample). Mean recovery values of most solutes are >80% in the 10 to 500 microg/kg fortification range with respective RSDs (relative standard deviations) < 20%. The limits of quantification (LOQ) and limits of detection (LOD) are 10 and 1 to 5 microg/kg, respectively. The method was validated with two types of soils containing 1.5 and 3.0% organic matter content, respectively; no statistically significant differences were found between solute recovery values from the two types of soils. The solute mean recovery values from freshly spiked (24 h aging) and spiked samples stored refrigerated for one week before processed were also not statistically different. Residue levels determined in field weathered soils were higher when soils were processed by MAE than with a comparison method based on flask-shaking of soil suspensions overnight. Extracts were analyzed by a gas chromatographic system equipped either with a thermionic (GC-NPD) or a mass spectrometric detector (GC-MS).

  14. Drill Cuttings-based Methodology to Optimize Multi-stage Hydraulic Fracturing in Horizontal Wells and Unconventional Gas Reservoirs

    NASA Astrophysics Data System (ADS)

    Ortega Mercado, Camilo Ernesto

    Horizontal drilling and hydraulic fracturing techniques have become almost mandatory technologies for economic exploitation of unconventional gas reservoirs. Key to commercial success is minimizing the risk while drilling and hydraulic fracturing these wells. Data collection is expensive and as a result this is one of the first casualties during budget cuts. As a result complete data sets in horizontal wells are nearly always scarce. In order to minimize the data scarcity problem, the research addressed throughout this thesis concentrates on using drill cuttings, an inexpensive direct source of information, for developing: 1) A new methodology for multi-stage hydraulic fracturing optimization of horizontal wells without any significant increases in operational costs. 2) A new method for petrophysical evaluation in those wells with limited amount of log information. The methods are explained using drill cuttings from the Nikanassin Group collected in the Deep Basin of the Western Canada Sedimentary Basin (WCSB). Drill cuttings are the main source of information for the proposed methodology in Item 1, which involves the creation of three 'log tracks' containing the following parameters for improving design of hydraulic fracturing jobs: (a) Brittleness Index, (b) Measured Permeability and (c) An Indicator of Natural Fractures. The brittleness index is primarily a function of Poisson's ratio and Young Modulus, parameters that are obtained from drill cuttings and sonic logs formulations. Permeability is measured on drill cuttings in the laboratory. The indication of natural fractures is obtained from direct observations on drill cuttings under the microscope. Drill cuttings are also the main source of information for the new petrophysical evaluation method mentioned above in Item 2 when well logs are not available. This is important particularly in horizontal wells where the amount of log data is almost non-existent in the vast majority of the wells. By combining data

  15. Optimization of matrix assisted desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) for the characterization of Bacillus and Brevibacillus species

    PubMed Central

    AlMasoud, Najla; Xu, Yun; Nicolaou, Nicoletta; Goodacre, Royston

    2014-01-01

    Over the past few decades there has been an increased interest in using various analytical techniques for detecting and identifying microorganisms. More recently there has been an explosion in the application of matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) for bacterial characterization, and here we optimize this approach in order to generate reproducible MS data from bacteria belonging to the genera Bacillus and Brevibacillus. Unfortunately MALDI-TOF-MS generates large amounts of data and is prone to instrumental drift. To overcome these challenges we have developed a preprocessing pipeline that includes baseline correction, peak alignment followed by peak picking that in combination significantly reduces the dimensionality of the MS spectra and corrects for instrument drift. Following this two different prediction models were used which are based on support vector machines and these generated satisfactory prediction accuracies of approximately 90%. PMID:25086893

  16. Optimization of microwave assisted digestion procedure for the determination of zinc, copper and nickel in tea samples employing flame atomic absorption spectrometry.

    PubMed

    Soylak, Mustafa; Tuzen, Mustafa; Souza, Anderson Santos; das Graças Andrade Korn, Maria; Ferreira, Sérgio Luis Costa

    2007-10-22

    The present paper describes the development of a microwave assisted digestion procedure for the determination of zinc, copper and nickel in tea samples employing flame atomic absorption spectrometry (FAAS). The optimization step was performed using a full factorial design (2(3)) involving the factors: composition of the acid mixture (CMA), microwave power (MP) and radiation time (RT). The experiments of this factorial were carried out using a certified reference material of tea GBW 07605 furnished by National Research Centre for Certified Reference Materials, China, being the metal recoveries considered as response. The relative standard deviations of the method were found below 8% for the three elements. The procedure proposed was used for the determination of copper, zinc and nickel in several samples of tea from Turkey. For 10 tea samples analyzed, the concentration achieved for copper, zinc and nickel varied at 6.4-13.1, 7.0-16.5 and 3.1-5.7 (microg g(-1)), respectively.

  17. Evaluation, prediction and optimization the ultrasound-assisted extraction method using response surface methodology: antioxidant and biological properties of Stachys parviflora L.

    PubMed Central

    Bashi, Davoud Salar; Dowom, Samaneh Attaran; Bazzaz, Bibi Sedigheh Fazly; Khanzadeh, Farhad; Soheili, Vahid; Mohammadpour, Ali

    2016-01-01

    Objective(s): To optimize the extraction method using response surface methodology, extract the phenolic compounds, and identify the antioxidant and biological properties of Stachys parviflora L. extracts. Materials and Methods: Maceration and ultrasound-assisted extraction (UAE) (4, 7, 10 min treatment time, 40, 70, 100 % high-intensity and 60, 80, 100 % (v v-1) methanol purity) were applied to obtain the extracts. SEM was conducted to provide the microstructure of the extracted plant. MICs (colorimetric assay), MFCs (colony diameter), total phenolic content, total flavonoid content, radical scavenging capacity and extraction efficiency were determined. HPLC analysis was applied to measure the existent phenolic compounds. Results: A quadratic model (4 min treatment time, 74.5 % high-intensity and 74.2 % solvent purity) was suggested as the best (TPC: 20.89 mg GAE g-1 d.m., TFC: 6.22 mg QEs g-1 d.m., DPPH IC50: 21.86 µg ml-1 and EE: 113.65 mg g-1 d.m.) UAE extraction model. The optimized UAE extract was generally more effective against Gram-positive microorganisms (MIC: 10-20; MBC: 10-40 (mg ml-1)) than Gram-negative ones (MIC: 40; MBC: >40 (mg ml-1)). Moreover, it (MGI: 2.32-100 %) revealed more anti-mold activity than maceration (MGI: <28.77 %). Explosive disruption of the cell walls, therefore, enhanced extraction yield by acoustic cavitation, was elucidated using SEM. Caffeic acid, tannic acid, quercetin, trans ferulic acid and rosmarinic acid were determined as the phenolic compounds in the optimized extract. Conclusion: RSM optimization was successfully applied for UAE from S. parviflora. The considerable antioxidant and biological properties were attributed to the phenolic compounds. PMID:27403260

  18. Performance Optimization of Priority Assisted CSMA/CA Mechanism of 802.15.6 under Saturation Regime

    PubMed Central

    Shakir, Mustafa; Rehman, Obaid Ur; Rahim, Mudassir; Alrajeh, Nabil; Khan, Zahoor Ali; Khan, Mahmood Ashraf; Niaz, Iftikhar Azim; Javaid, Nadeem

    2016-01-01

    Due to the recent development in the field of Wireless Sensor Networks (WSNs), the Wireless Body Area Networks (WBANs) have become a major area of interest for the developers and researchers. Human body exhibits postural mobility due to which distance variation occurs and the status of connections amongst sensors change time to time. One of the major requirements of WBAN is to prolong the network lifetime without compromising on other performance measures, i.e., delay, throughput and bandwidth efficiency. Node prioritization is one of the possible solutions to obtain optimum performance in WBAN. IEEE 802.15.6 CSMA/CA standard splits the nodes with different user priorities based on Contention Window (CW) size. Smaller CW size is assigned to higher priority nodes. This standard helps to reduce delay, however, it is not energy efficient. In this paper, we propose a hybrid node prioritization scheme based on IEEE 802.15.6 CSMA/CA to reduce energy consumption and maximize network lifetime. In this scheme, optimum performance is achieved by node prioritization based on CW size as well as power in respective user priority. Our proposed scheme reduces the average back off time for channel access due to CW based prioritization. Additionally, power based prioritization for a respective user priority helps to minimize required number of retransmissions. Furthermore, we also compare our scheme with IEEE 802.15.6 CSMA/CA standard (CW assisted node prioritization) and power assisted node prioritization under postural mobility in WBAN. Mathematical expressions are derived to determine the accurate analytical model for throughput, delay, bandwidth efficiency, energy consumption and life time for each node prioritization scheme. With the intention of analytical model validation, we have performed the simulations in OMNET++/MIXIM framework. Analytical and simulation results show that our proposed hybrid node prioritization scheme outperforms other node prioritization schemes in

  19. Performance Optimization of Priority Assisted CSMA/CA Mechanism of 802.15.6 under Saturation Regime.

    PubMed

    Shakir, Mustafa; Rehman, Obaid Ur; Rahim, Mudassir; Alrajeh, Nabil; Khan, Zahoor Ali; Khan, Mahmood Ashraf; Niaz, Iftikhar Azim; Javaid, Nadeem

    2016-09-02

    Due to the recent development in the field of Wireless Sensor Networks (WSNs), the Wireless Body Area Networks (WBANs) have become a major area of interest for the developers and researchers. Human body exhibits postural mobility due to which distance variation occurs and the status of connections amongst sensors change time to time. One of the major requirements of WBAN is to prolong the network lifetime without compromising on other performance measures, i.e., delay, throughput and bandwidth efficiency. Node prioritization is one of the possible solutions to obtain optimum performance in WBAN. IEEE 802.15.6 CSMA/CA standard splits the nodes with different user priorities based on Contention Window (CW) size. Smaller CW size is assigned to higher priority nodes. This standard helps to reduce delay, however, it is not energy efficient. In this paper, we propose a hybrid node prioritization scheme based on IEEE 802.15.6 CSMA/CA to reduce energy consumption and maximize network lifetime. In this scheme, optimum performance is achieved by node prioritization based on CW size as well as power in respective user priority. Our proposed scheme reduces the average back off time for channel access due to CW based prioritization. Additionally, power based prioritization for a respective user priority helps to minimize required number of retransmissions. Furthermore, we also compare our scheme with IEEE 802.15.6 CSMA/CA standard (CW assisted node prioritization) and power assisted node prioritization under postural mobility in WBAN. Mathematical expressions are derived to determine the accurate analytical model for throughput, delay, bandwidth efficiency, energy consumption and life time for each node prioritization scheme. With the intention of analytical model validation, we have performed the simulations in OMNET++/MIXIM framework. Analytical and simulation results show that our proposed hybrid node prioritization scheme outperforms other node prioritization schemes in

  20. Impact of surfactant assisted acid and alkali pretreatment on lignocellulosic structure of pine foliage and optimization of its saccharification parameters using response surface methodology.

    PubMed

    Pandey, Ajay Kumar; Negi, Sangeeta

    2015-09-01

    In present study, two hybrid methods such as surfactant assisted acid pretreatment (SAAP) and surfactant assisted base pretreatment (SABP) of pine foliage (PF) were found efficient for removal of 59.53 ± 0.76% and 73.47 ± 1.03% lignin, respectively. Assessment of the impact of pretreatment over the structure of PF were studied by scanning electron microscopy, Fourier transform infrared and X-ray diffraction analysis. Parameters for saccharification of SAAP and SABP biomass were optimized by Box-Behnken design method and 0.588 g/g and 0.477 g/g of reducing sugars were obtained, respectively. The ethanol fermentation efficiency of Saccharomyces cerevisiae (NCIM 3288) of hydrolysates was increased by 16.1% and 6.01% in SAAP-PFF and SABP-PFF after detoxification with XAD-4 resin. The mass balance analysis of the process showed that 67.7% and 70.12% cellulose were utilized during SAAP and SABP, respectively. These results indicated that SAAP would be more economic for bioethanol production.

  1. Optimization of ultrasound-assisted aqueous two-phase system extraction of polyphenolic compounds from Aronia melanocarpa pomace by response surface methodology.

    PubMed

    Xu, Yan-Yang; Qiu, Yang; Ren, Hui; Ju, Dong-Hu; Jia, Hong-Lei

    2017-03-16

    Aronia melanocarpa berries are abundant in polyphenolic compounds. After juice production, the pomace of pressed berries still contains a substantial amount of polyphenolic compounds. For efficient utilization of A. melanocarpa berries and the enhancement of polyphenolic compound yields in Aronia melanocarpa pomace (AMP), total phenolics (TP) and total flavonoids (TF) from AMP were extracted, using ultrasound-assisted aqueous two-phase system (UAE-ATPS) extraction method. First, the influences of ammonium sulfate concentration, ethanol-water ratio, ultrasonic time, and ultrasonic power on TP and TF yields were investigated. On this basis, process variables such as ammonium sulfate concentration (0.30-0.35 g mL(-1)), ethanol-water ratio (0.6-0.8), ultrasonic time (40-60 min), and ultrasonic power (175-225 W) were further optimized by implementing Box-Benhnken design with response surface methodology. The experimental results showed that optimal extraction conditions of TP from AMP were as follows: ammonium sulfate concentration of 0.324 g mL(-1), ethanol-water ratio of 0.69, ultrasonic time of 52 min, and ultrasonic power of 200 W. Meanwhile, ammonium sulfate concentration of 0.320 g mL(-1), ethanol-water ratio of 0.71, ultrasonic time of 50 min, and ultrasonic power of 200 W were determined as optimum extraction conditions of TF in AMP. Experimental validation was performed, where TP and TF yields reached 68.15 ± 1.04 and 11.67 ± 0.63 mg g(-1), respectively. Close agreement was found between experimental and predicted values. Overall, the present results demonstrated that ultrasound-assisted aqueous two-phase system extraction method was successfully used to extract total phenolics and flavonoids in A. melanocarpa pomace.

  2. An Approach to the Prototyping of an Optimized Limited Stroke Actuator to Drive a Low Pressure Exhaust Gas Recirculation Valve

    PubMed Central

    Gutfrind, Christophe; Dufour, Laurent; Liebart, Vincent; Vannier, Jean-Claude; Vidal, Pierre

    2016-01-01

    The purpose of this article is to describe the design of a limited stroke actuator and the corresponding prototype to drive a Low Pressure (LP) Exhaust Gas Recirculation (EGR) valve for use in Internal Combustion Engines (ICEs). The direct drive actuator topology is an axial flux machine with two air gaps in order to minimize the rotor inertia and a bipolar surface-mounted permanent magnet in order to respect an 80° angular stroke. Firstly, the actuator will be described and optimized under constraints of a 150 ms time response, a 0.363 N·m minimal torque on an angular range from 0° to 80° and prototyping constraints. Secondly, the finite element method (FEM) using the FLUX-3D® software (CEDRAT, Meylan, France) will be used to check the actuator performances with consideration of the nonlinear effect of the iron material. Thirdly, a prototype will be made and characterized to compare its measurement results with the analytical model and the FEM model results. With these electromechanical behavior measurements, a numerical model is created with Simulink® in order to simulate an EGR system with this direct drive actuator under all operating conditions. Last but not least, the energy consumption of this machine will be estimated to evaluate the efficiency of the proposed EGR electromechanical system. PMID:27213398

  3. An Approach to the Prototyping of an Optimized Limited Stroke Actuator to Drive a Low Pressure Exhaust Gas Recirculation Valve.

    PubMed

    Gutfrind, Christophe; Dufour, Laurent; Liebart, Vincent; Vannier, Jean-Claude; Vidal, Pierre

    2016-05-20

    The purpose of this article is to describe the design of a limited stroke actuator and the corresponding prototype to drive a Low Pressure (LP) Exhaust Gas Recirculation (EGR) valve for use in Internal Combustion Engines (ICEs). The direct drive actuator topology is an axial flux machine with two air gaps in order to minimize the rotor inertia and a bipolar surface-mounted permanent magnet in order to respect an 80° angular stroke. Firstly, the actuator will be described and optimized under constraints of a 150 ms time response, a 0.363 N·m minimal torque on an angular range from 0° to 80° and prototyping constraints. Secondly, the finite element method (FEM) using the FLUX-3D(®) software (CEDRAT, Meylan, France) will be used to check the actuator performances with consideration of the nonlinear effect of the iron material. Thirdly, a prototype will be made and characterized to compare its measurement results with the analytical model and the FEM model results. With these electromechanical behavior measurements, a numerical model is created with Simulink(®) in order to simulate an EGR system with this direct drive actuator under all operating conditions. Last but not least, the energy consumption of this machine will be estimated to evaluate the efficiency of the proposed EGR electromechanical system.

  4. Gas Chromatography- Mass Spectrometry Based Metabolomic Approach for Optimization and Toxicity Evaluation of Earthworm Sub-Lethal Responses to Carbofuran

    PubMed Central

    Saxena, Prem Narain

    2013-01-01

    Despite recent advances in understanding mechanism of toxicity, the development of biomarkers (biochemicals that vary significantly with exposure to chemicals) for pesticides and environmental contaminants exposure is still a challenging task. Carbofuran is one of the most commonly used pesticides in agriculture and said to be most toxic carbamate pesticide. It is necessary to identify the biochemicals that can vary significantly after carbofuran exposure on earthworms which will help to assess the soil ecotoxicity. Initially, we have optimized the extraction conditions which are suitable for high-throughput gas chromatography mass spectrometry (GC-MS) based metabolomics for the tissue of earthworm, Metaphire posthuma. Upon evaluation of five different extraction solvent systems, 80% methanol was found to have good extraction efficiency based on the yields of metabolites, multivariate analysis, total number of peaks and reproducibility of metabolites. Later the toxicity evaluation was performed to characterize the tissue specific metabolomic perturbation of earthworm, Metaphire posthuma after exposure to carbofuran at three different concentration levels (0.15, 0.3 and 0.6 mg/kg of soil). Seventeen metabolites, contributing to the best classification performance of highest dose dependent carbofuran exposed earthworms from healthy controls were identified. This study suggests that GC-MS based metabolomic approach was precise and sensitive to measure the earthworm responses to carbofuran exposure in soil, and can be used as a promising tool for environmental eco-toxicological studies. PMID:24324663

  5. Gas chromatographic-mass spectrometric study of the oil fractions produced by microwave-assisted pyrolysis of different sewage sludges.

    PubMed

    Domínguez, A; Menéndez, J A; Inguanzo, M; Bernad, P L; Pis, J J

    2003-09-19

    The pyrolysis of sewage sludge was studied in a microwave oven using graphite as microwave absorber. The pyrolysis temperature ranged from 800 to 1000 degrees C depending on the type of sewage sludge. A conventional electrical furnace was also employed in order to compare the results obtained with both methods. The pyrolysis oils were trapped in a series of condensers and their characteristics such as elemental analysis and calorific value were determined and compared with those of the initial sludge. The oil composition was analyzed by GC-MS. The oils from the microwave oven had n-alkanes and 1-alkenes, aromatic compounds, ranging from benzene derivatives to polycyclic aromatic hydrocarbons (PAHs), nitrogenated compounds, long chain aliphatic carboxylic acids, ketones and esters and also monoterpenes and steroids. The oil from the electric oven was composed basically of PAHs such as naphthalene, acenapthylene, phenanthrene, fluoranthene, benzo[a]anthracene, benzofluoranthenes, benzopyrenes, indenepyrene, benzo[ghi]perylene, and anthanthrene. In contrast, these compounds were not produced in the case of microwave-assisted pyrolysis.

  6. The Use of Exhaust Gas Recirculation to Optimize Fuel Economy and Minimize Emission in Engines Operating on E85 Fuel

    SciTech Connect

    Wu, Ko-Jen

    2011-12-31

    This report summarizes activities conducted for the project “The Use of Exhaust Gas Recirculation to Optimized Fuel Economy and Minimize Emissions in Engines Operating on E85 Fuel” under COOPERATIVE AGREEMENT NUMBER DE-FC26-07NT43271, which are as outlined in the STATEMENT OF PROJECT OBJECTIVES (SOPO) dated March 2007 and in the supplemental SOPO dated October 2010. The project objective was to develop and demonstrate an internal combustion engine that is optimized for E85 (85% ethanol and 15% gasoline) fuel operation to achieve substantially improved fuel economy while operating with E85 fuel and that is also production viable in the near- to medium-term. The key engine technology selected for research and development was turbocharging, which is known to improve fuel economy thru downsizing and is in particular capable of exploiting ethanol fuel’s characteristics of high octane number and high latent heat of vaporization. The engine further integrated synergistic efficiency improving technologies of cooled exhaust gas recirculation (EGR), direct fuel injection and dual continuously variable intake and exhaust cam phasers. On the vehicle level, fuel economy was furthered thru powertrain system optimization by mating a state-of-the-art six-speed automatic transmission to the engine. In order to achieve the project’s objective of near- to medium-term production viability, it was essential to develop the engine to be flex-fuel capable of operating with fuels ranging from E0 (0% ethanol and 100% gasoline) to E85 and to use three-way type of catalyst technology for exhaust aftertreatment. Within these scopes, various technologies were developed through systems approach to focus on ways to help accelerate catalyst light-off. Significant amount of development took place during the course of the project within General Motors, LLC. Many prototype flex-fuel engines were designed, built and developed with various hardware configurations selected to achieve the project

  7. Matrix-assisted laser desorption/ionization sample preparation optimization for structural characterization of poly(styrene-co-pentafluorostyrene) copolymers.

    PubMed

    Tisdale, Evgenia; Kennedy, Devin; Xu, Xiaodong; Wilkins, Charles

    2014-01-15

    The influence of the sample preparation parameters (the choice of the matrix, matrix:analyte ratio, salt:analyte ratio) was investigated and optimal conditions were established for the MALDI time-of-flight mass spectrometry analysis of the poly(styrene-co-pentafluorostyrene) copolymers. These were synthesized by atom transfer radical polymerization. Use of 2,5-dihydroxybenzoic acid as matrix resulted in spectra with consistently high ion yields for all matrix:analyte:salt ratios tested. The optimized MALDI procedure was successfully applied to the characterization of three copolymers obtained by varying the conditions of polymerization reaction. It was possible to establish the nature of the end groups, calculate molecular weight distributions, and determine the individual length distributions for styrene and pentafluorostyrene monomers, contained in the resulting copolymers. Based on the data obtained, it was concluded that individual styrene chain length distributions are more sensitive to the change in the composition of the catalyst (the addition of small amount of CuBr2) than is the pentafluorostyrene component distribution.

  8. Finding the Right Candidate for the Right Position: A Fast NMR-Assisted Combinatorial Method for Optimizing Nucleic Acids Binders.

    PubMed

    Jiménez-Moreno, Ester; Montalvillo-Jiménez, Laura; Santana, Andrés G; Gómez, Ana M; Jiménez-Osés, Gonzalo; Corzana, Francisco; Bastida, Agatha; Jiménez-Barbero, Jesús; Cañada, Francisco Javier; Gómez-Pinto, Irene; González, Carlos; Asensio, Juan Luis

    2016-05-25

    Development of strong and selective binders from promiscuous lead compounds represents one of the most expensive and time-consuming tasks in drug discovery. We herein present a novel fragment-based combinatorial strategy for the optimization of multivalent polyamine scaffolds as DNA/RNA ligands. Our protocol provides a quick access to a large variety of regioisomer libraries that can be tested for selective recognition by combining microdialysis assays with simple isotope labeling and NMR experiments. To illustrate our approach, 20 small libraries comprising 100 novel kanamycin-B derivatives have been prepared and evaluated for selective binding to the ribosomal decoding A-Site sequence. Contrary to the common view of NMR as a low-throughput technique, we demonstrate that our NMR methodology represents a valuable alternative for the detection and quantification of complex mixtures, even integrated by highly similar or structurally related derivatives, a common situation in the context of a lead optimization process. Furthermore, this study provides valuable clues about the structural requirements for selective A-site recognition.

  9. Optimization of the ultrasonic assisted removal of methylene blue by gold nanoparticles loaded on activated carbon using experimental design methodology.

    PubMed

    Roosta, M; Ghaedi, M; Daneshfar, A; Sahraei, R; Asghari, A

    2014-01-01

    The present study was focused on the removal of methylene blue (MB) from aqueous solution by ultrasound-assisted adsorption onto the gold nanoparticles loaded on activated carbon (Au-NP-AC). This nanomaterial was characterized using different techniques such as SEM, XRD, and BET. The effects of variables such as pH, initial dye concentration, adsorbent dosage (g), temperature and sonication time (min) on MB removal were studied and using central composite design (CCD) and the optimum experimental conditions were found with desirability function (DF) combined response surface methodology (RSM). Fitting the experimental equilibrium data to various isotherm models such as Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models show the suitability and applicability of the Langmuir model. Analysis of experimental adsorption data to various kinetic models such as pseudo-first and second order, Elovich and intraparticle diffusion models show the applicability of the second-order equation model. The small amount of proposed adsorbent (0.01 g) is applicable for successful removal of MB (RE>95%) in short time (1.6 min) with high adsorption capacity (104-185 mg g(-1)).

  10. Optimization of Suture-Free Laser-Assisted Vessel Repair by Solder-Doped Electrospun Poly(ε-caprolactone) Scaffold

    PubMed Central

    Pabittei, Dara R.; Heger, Michal; Beek, Johan F.; van Tuijl, Sjoerd; Simonet, Marc; van der Wal, Allard C.; de Mol, Bas A.

    2010-01-01

    Poor welding strength constitutes an obstacle in the clinical employment of laser-assisted vascular repair (LAVR) and anastomosis. We therefore investigated the feasibility of using electrospun poly(ε-caprolactone) (PCL) scaffold as reinforcement material in LAVR of medium-sized vessels. In vitro solder-doped scaffold LAVR (ssLAVR) was performed on porcine carotid arteries or abdominal aortas using a 670-nm diode laser, a solder composed of 50% bovine serum albumin and 0.5% methylene blue, and electrospun PCL scaffolds. The correlation between leaking point pressures (LPPs) and arterial diameter, the extent of thermal damage, structural and mechanical alterations of the scaffold following ssLAVR, and the weak point were investigated. A strong negative correlation existed between LPP and vessel diameter, albeit LPP (484 ± 111 mmHg) remained well above pathophysiological pressures. Histological analysis revealed that thermal damage extended into the medial layer with a well-preserved internal elastic lamina and endothelial cells. Laser irradiation of PCL fibers and coagulation of solder material resulted in a strong and stiff scaffold. The weak point of the ssLAVR modality was predominantly characterized by cohesive failure. In conclusion, ssLAVR produced supraphysiological LPPs and limited tissue damage. Despite heat-induced structural/mechanical alterations of the scaffold, PCL is a suitable polymer for weld reinforcement in medium-sized vessel ssLAVR. PMID:20835847

  11. Tri-leaflet valve design with a purge flow for heart-assist devices: an in vitro optimization study.

    PubMed

    Timmel, Tobias; Seshadri, Santhosh; Goubergrits, Leonid; Affeld, Klaus; Kertzscher, Ulrich

    2012-01-01

    The objective of this study is to assess the effect of a purge flow on valves of pulsatile heart-assist devices. Clinical applications of these devices are still limited because of frequent thromboembolic complications. These complications often originate at the valves and the unavoidable flow separation regions that are found behind the leaflets. The flow separations cause a long residence time of blood that is considered particularly detrimental. To solve this problem, a valve with a purge flow is proposed. A purge flow is a jet, which is separated from the main blood flow and directed behind the leaflets into the sinus to flush it. Even though the purge flow does not prevent a flow separation, it shortens the residence time of the blood in the sinus. Thus, the purge flow improves the periodic washout of the blood in the region of flow separation. The complex purge flow was investigated in a tri-leaflet valve. The geometrical parameters of the valve were varied systematically. A statistical technique--the Taguchi method--was used to reduce the number of investigated models to 12. The flows through the resulting valve models were numerically simulated and analyzed. The evaluated models with the best results were subsequently investigated experimentally using different methods: hemodynamic tests in a valve tester and flow visualization using the dye washout method. It was shown that the purge flow can effectively wash out the sinus. Therefore, the purge flow valve reduces the potential of a thrombus formation normally associated with the valve.

  12. Optimization of microwave-assisted extraction for the characterization of olive leaf phenolic compounds by using HPLC-ESI-TOF-MS/IT-MS(2).

    PubMed

    Taamalli, Amani; Arráez-Román, David; Ibañez, Elena; Zarrouk, Mokhtar; Segura-Carretero, Antonio; Fernández-Gutiérrez, Alberto

    2012-01-25

    In the present work, a simple and rapid method for the extraction of phenolic compounds from olive leaves, using microwave-assisted extraction (MAE) technique, has been developed. The experimental variables that affect the MAE process, such as the solvent type and composition, microwave temperature, and extraction time, were optimized using a univariate method. The obtained extracts were analyzed by using high-performance liquid chromatography (HPLC) coupled to electrospray time-of-flight mass spectrometry (ESI-TOF-MS) and electrospray ion trap tandem mass spectrometry (ESI-IT-MS(2)) to prove the MAE extraction efficiency. The optimal MAE conditions were methanol:water (80:20, v/v) as extracting solvent, at a temperature equal to 80 °C for 6 min. Under these conditions, several phenolic compounds could be characterized by HPLC-ESI-MS/MS(2). As compared to the conventional method, MAE can be used as an alternative extraction method for the characterization of phenolic compounds from olive leaves due to its efficiency and speed.

  13. Optimization of extraction efficiency by shear emulsifying assisted enzymatic hydrolysis and functional properties of dietary fiber from deoiled cumin (Cuminum cyminum L.).

    PubMed

    Ma, Mengmei; Mu, Taihua; Sun, Hongnan; Zhang, Miao; Chen, Jingwang; Yan, Zhibin

    2015-07-15

    This study evaluated the optimal conditions for extracting dietary fiber (DF) from deoiled cumin by shear emulsifying assisted enzymatic hydrolysis (SEAEH) using the response surface methodology. Fat adsorption capacity (FAC), glucose adsorption capacity (GAC), and bile acid retardation index (BRI) were measured to evaluate the functional properties of the extracted DF. The results revealed that the optimal extraction conditions included an enzyme to substrate ratio of 4.5%, a reaction temperature of 57 °C, a pH value of 7.7, and a reaction time of 155 min. Under these conditions, DF extraction efficiency and total dietary fiber content were 95.12% and 84.18%, respectively. The major components of deoiled cumin DF were hemicellulose (37.25%) and cellulose (33.40%). FAC and GAC increased with decreasing DF particle size (51-100 μm), but decreased with DF particle sizes <26 μm; BRI increased with decreasing DF particle size. The results revealed that SEAEH is an effective method for extracting DF. DF with particle size 26-51 μm had improved functional properties.

  14. The optimization process of biodiesel production using multiple feedstock (CPO and Jatropha) with assistance of ultrasound at 40 kHz

    NASA Astrophysics Data System (ADS)

    Fajar, Berkah; Wilis, Widayat

    2016-06-01

    CPO prices are unstable, therefore affecting the supply of feedstock to produce biodiesel [2]. To overcome the shortage of feedstock, it is necessary to use multiple feedstock, in this case is CPO and Jatropha [1]. This objective of this work to optimizate biodiesel production using multifeedstock (CPO and Jatropha) with assistance of ultrasound. The optimization was to find the highest yield and the least production time. Experiments was carried out using an ultrasonic bath at a frequency of 40 kHz. The ratio of CPO and Jatropha was 1: 1, 3: 1, 4: 1 while the ratio of methanol and oil was 5: 1, 6: 1, 7: 1 and the reaction time was 50, 60, and 70 minutes. KOH was used as a catalyst. The experiment data was optimized using a Response Surface Methodology [3,4]. The optimum point was at a frequency of 40 kHz obtained at a 2.8: 1 mixture of CPO - Jatropha, 6.4: 1 molar ratio of methanol-oil and 61.5 minutes of reaction time. The results of quality testing shows that the biodiesel produced meets the ASTM standard D6751 and SNI 04-7182-2006[5].

  15. Optimality in Microwave-Assisted Drying of Aloe Vera ( Aloe barbadensis Miller) Gel using Response Surface Methodology and Artificial Neural Network Modeling

    NASA Astrophysics Data System (ADS)

    Das, Chandan; Das, Arijit; Kumar Golder, Animes

    2016-10-01

    The present work illustrates the Microwave-Assisted Drying (MWAD) characteristic of aloe vera gel combined with process optimization and artificial neural network modeling. The influence of microwave power (160-480 W), gel quantity (4-8 g) and drying time (1-9 min) on the moisture ratio was investigated. The drying of aloe gel exhibited typical diffusion-controlled characteristics with a predominant interaction between input power and drying time. Falling rate period was observed for the entire MWAD of aloe gel. Face-centered Central Composite Design (FCCD) developed a regression model to evaluate their effects on moisture ratio. The optimal MWAD conditions were established as microwave power of 227.9 W, sample amount of 4.47 g and 5.78 min drying time corresponding to the moisture ratio of 0.15. A computer-stimulated Artificial Neural Network (ANN) model was generated for mapping between process variables and the desired response. `Levenberg-Marquardt Back Propagation' algorithm with 3-5-1 architect gave the best prediction, and it showed a clear superiority over FCCD.

  16. Optimization of Ionic Liquid Based Simultaneous Ultrasonic- and Microwave-Assisted Extraction of Rutin and Quercetin from Leaves of Velvetleaf (Abutilon theophrasti) by Response Surface Methodology

    PubMed Central

    Zhao, Chunjian; Lu, Zhicheng; He, Xin; Li, Zhao; Shi, Kunming; Yang, Lei; Fu, Yujie; Zu, Yuangang

    2014-01-01

    An ionic liquids based simultaneous ultrasonic and microwave assisted extraction (ILs-UMAE) method has been proposed for the extraction of rutin (RU), quercetin (QU), from velvetleaf leaves. The influential parameters of the ILs-UMAE were optimized by the single factor and the central composite design (CCD) experiments. A 2.00 M 1-butyl-3-methylimidazolium bromide ([C4mim]Br) was used as the experimental ionic liquid, extraction temperature 60°C, extraction time 12 min, liquid-solid ratio 32 mL/g, microwave power of 534 W, and a fixed ultrasonic power of 50 W. Compared to conventional heating reflux extraction (HRE), the RU and QU extraction yields obtained by ILs-UMAE were, respectively, 5.49 mg/g and 0.27 mg/g, which increased, respectively, 2.01-fold and 2.34-fold with the recoveries that were in the range of 97.62–102.36% for RU and 97.33–102.21% for QU with RSDs lower than 3.2% under the optimized UMAE conditions. In addition, the shorter extraction time was used in ILs-UMAE, compared with HRE. Therefore, ILs-UMAE was a rapid and an efficient method for the extraction of RU and QU from the leaves of velvetleaf. PMID:25243207

  17. Soil radium, soil gas radon and indoor radon empirical relationships to assist in post-closure impact assessment related to near-surface radioactive waste disposal.

    PubMed

    Appleton, J D; Cave, M R; Miles, J C H; Sumerling, T J

    2011-03-01

    Least squares (LS), Theil's (TS) and weighted total least squares (WTLS) regression analysis methods are used to develop empirical relationships between radium in the ground, radon in soil and radon in dwellings to assist in the post-closure assessment of indoor radon related to near-surface radioactive waste disposal at the Low Level Waste Repository in England. The data sets used are (i) estimated ²²⁶Ra in the < 2 mm fraction of topsoils (eRa226) derived from equivalent uranium (eU) from airborne gamma spectrometry data, (ii) eRa226 derived from measurements of uranium in soil geochemical samples, (iii) soil gas radon and (iv) indoor radon data. For models comparing indoor radon and (i) eRa226 derived from airborne eU data and (ii) soil gas radon data, some of the geological groupings have significant slopes. For these groupings there is reasonable agreement in slope and intercept between the three regression analysis methods (LS, TS and WTLS). Relationships between radon in dwellings and radium in the ground or radon in soil differ depending on the characteristics of the underlying geological units, with more permeable units having steeper slopes and higher indoor radon concentrations for a given radium or soil gas radon concentration in the ground. The regression models comparing indoor radon with soil gas radon have intercepts close to 5 Bq m⁻³ whilst the intercepts for those comparing indoor radon with eRa226 from airborne eU vary from about 20 Bq m⁻³ for a moderately permeable geological unit to about 40 Bq m⁻³ for highly permeable limestone, implying unrealistically high contributions to indoor radon from sources other than the ground. An intercept value of 5 Bq m⁻³ is assumed as an appropriate mean value for the UK for sources of indoor radon other than radon from the ground, based on examination of UK data. Comparison with published data used to derive an average indoor radon: soil ²²⁶Ra ratio shows that whereas the published data are

  18. Optimization and economic evaluation of industrial gas production and combined heat and power generation from gasification of corn stover and distillers grains.

    PubMed

    Kumar, Ajay; Demirel, Yasar; Jones, David D; Hanna, Milford A

    2010-05-01

    Thermochemical gasification is one of the most promising technologies for converting biomass into power, fuels and chemicals. The objectives of this study were to maximize the net energy efficiency for biomass gasification, and to estimate the cost of producing industrial gas and combined heat and power (CHP) at a feedrate of 2000kg/h. Aspen Plus-based model for gasification was combined with a CHP generation model, and optimized using corn stover and dried distillers grains with solubles (DDGS) as the biomass feedstocks. The cold gas efficiencies for gas production were 57% and 52%, respectively, for corn stover and DDGS. The selling price of gas was estimated to be $11.49 and $13.08/GJ, respectively, for corn stover and DDGS. For CHP generation, the electrical and net efficiencies were as high as 37% and 88%, respectively, for corn stover and 34% and 78%, respectively, for DDGS. The selling price of electricity was estimated to be $0.1351 and $0.1287/kWh for corn stover and DDGS, respectively. Overall, high net energy efficiencies for gas and CHP production from biomass gasification can be achieved with optimized processing conditions. However, the economical feasibility of these conversion processes will depend on the relative local prices of fossil fuels.

  19. Determination of the solubility of low volatility liquid organic compounds in water using volatile-tracer assisted headspace gas chromatography.

    PubMed

    Zhang, Shu-Xin; Chai, Xin-Sheng; Barnes, Donald G

    2016-02-26

    This study reports a new headspace gas chromatographic method (HS-GC) for the determination of water solubility of low volatility liquid organic compounds (LVLOs). The HS-GC analysis was performed on a set of aqueous solutions containing a range of concentrations of toluene-spiked (as a tracer) LVLOs, from under-saturation to over-saturation. A plot of the toluene tracer GC signal vs. the concentration of the LVLO results in two lines of different slopes that intersect at the concentration corresponding to the compound's solubility in water. The results showed that the HS-GC method has good precision (RSD <6.3%) and good accuracy, in which the relative deference between the data measured by the HS-GC method and the reference method were within 6.0%. The HS-GC method is simple and particularly suitable for measuring the solubility of LVLOs at elevated temperatures. This approach should be of special interest to those concerned about the impact of the presence of low-volatility organic liquids in waters of environmental and biological systems.

  20. Plasma-assisted cleanup of flue gas. Final technical report, 1 September, 1992--31 August, 1993

    SciTech Connect

    Dhali, S.K.

    1993-12-31

    The objective of the proposed research is to design and implement a novel scheme for the combined removal of SO{sub 2} and NO{sub x} using a dielectric-barrier discharge in conjunction with UV irradiation. This investigation requires the design of a dielectric-barrier reactor and testing the proposed scheme under different conditions that exist in a flue gas. A reactor has been designed and electrical tests have been performed. The voltage characteristics of the plasma reactor has been studied. The authors have found that a discharge can be sustained at atmospheric pressures with a large inner electrode in the coaxial configuration. The testing of the uniformity of the discharge with UV irradiation has been very successful. The details are provided in this report and have been submitted to the Applied Physics Letter. Also both experimental and simulation work were carried out on the removal of SO{sub 2} and NO{sub x}. With the improved reactor, they have achieved a conversions of SO{sub 2} up to 85%. The simulation studies indicate that complete removal of NO{sub x} is possible at reduced electric fields (E/N) of above 100 Td.

  1. Microwave-assisted on-spot derivatization for gas chromatography-mass spectrometry based determination of polar low molecular weight compounds in dried blood spots.

    PubMed

    Sadones, Nele; Van Bever, Elien; Archer, John R H; Wood, David M; Dargan, Paul I; Van Bortel, Luc; Lambert, Willy E; Stove, Christophe P

    2016-09-23

    Dried blood spot (DBS) sampling and analysis is increasingly being applied in bioanalysis. Although the use of DBS has many advantages, it is also associated with some challenges. E.g. given the limited amount of available material, highly sensitive detection techniques are often required to attain sufficient sensitivity. In gas chromatography coupled to mass spectrometry (GC-MS), derivatization can be helpful to achieve adequate sensitivity. Because this additional sample preparation step is considered as time-consuming, we introduce a new derivatization procedure, i.e. "microwave-assisted on-spot derivatization", to minimize sample preparation of DBS. In this approach the derivatization reagents are directly applied onto the DBS and derivatization takes place in a microwave instead of via conventional heating. In this manuscript we evaluated the applicability of this new concept of derivatization for the determination of two polar low molecular weight molecules, gamma-hydroxybutyric acid (GHB) and gabapentin, in DBS using a standard GC-MS configuration. The method was successfully validated for both compounds, with imprecision and bias values within acceptance criteria (<20% at LLOQ, <15% at 3 other QC levels). Calibration lines were linear over the 10-100μg/mL and 1-30μg/mL range for GHB and gabapentin, respectively. Stability studies revealed no significant decrease of gabapentin and GHB in DBS upon storage at room temperature for at least 84 days. Furthermore, DBS-specific parameters, including hematocrit and volume spotted, were evaluated. As demonstrated by the analysis of GHB and gabapentin positive samples, "microwave-assisted on-spot derivatization" proved to be reliable, fast and applicable in routine toxicology. Moreover, other polar low molecular weight compounds of interest in clinical and/or forensic toxicology, including vigabatrin, beta-hydroxybutyric acid, propylene glycol, diethylene glycol, 1,4-butanediol and 1,2-butanediol, can also be

  2. Ultrasound-assisted extraction and derivatization of sterols and fatty alcohols from olive leaves and drupes prior to determination by gas chromatography-tandem mass spectrometry.

    PubMed

    Orozco-Solano, M; Ruiz-Jiménez, J; Luque de Castro, M D

    2010-02-19

    A method for simultaneous determination of sterols and fatty alcohols in olive leaves and drupes based on ultrasound-assisted extraction and derivatization prior to individual identification-quantitation by chromatographic separation and mass spectrometry detection (single ion monitoring mode) is reported here. The sample preparation procedure involves the following steps: (i) leaching of the raw material accelerated by ultrasound; (ii) saponification of the leachate, also accelerated by ultrasound, and separation of the unsaponifiable matter; (iii) cleaning of the extract by solid-phase extraction; (iv) silylation of the target analytes-also assisted by ultrasound; (v) injection into the gas chromatograph for identification-simultaneous quantitation of the two families of compounds. Individual separation-determination of the fatty alcohols and sterols provide limits of detection (LOD) in the range 9.8 x 10(-2) to 2 microg/l and 5.0-6.0 microg/l, respectively. The LOQs range from 0.3 to 0.9 microg/l and 17.0 to 21.0 microg/l, and the linear dynamic ranges are between LOQ and 25.0 microg/ml. The between-day precision, expressed as relative standard deviation (RSD), ranges between 3.6 and 6.1% and the within-laboratory reproducibility, also expressed as RSD, between 6.4 and 9.2%. Within the study of the metabolomic profile of the unsaponifiable fraction in olive tree, the method has been applied to the determination of the target analytes in different varieties of olive trees cultivated in the same zone, so that differences in this unsaponifiable fraction can be attributed to characteristics of the target varieties. As compared with its European Union counterpart, the method is endowed with similar analytical characteristics and drastic shortening of the operational time.

  3. Optimized microwave-assisted decomposition method for multi-element analysis of glass standard reference material and ancient glass specimens by inductively coupled plasma atomic emission spectrometry.

    PubMed

    Zachariadis, G; Dimitrakoudi, E; Anthemidis, A; Stratis, J

    2006-02-28

    A novel microwave-assisted wet-acid decomposition method for the multi-element analysis of glass samples using inductively coupled plasma atomic emission spectrometry (ICP-AES) was developed and optimized. The SRM 621 standard reference glass material was used for this purpose, because it has similar composition with either archaeological glass specimens or common modern glasses. For the main constituents of SRM 621 (Ca, Na, Al, Fe, Mg, Ba and Ti), quality control data are given for all the examined procedures. The chemical and instrumental parameters of the method were thoroughly optimized. Thirteen acid mixtures of hydrochloric, nitric, and hydrofluoric acids in relation to two different microwave programs were examined in order to establish the most efficient protocol for the determination of metals in glass matrix. For both microwave programs, an intermediate step was employed with addition of H(3)BO(3) in order to compensate the effect of HF, which was used in all protocols. The suitability of the investigated protocols was evaluated for major (Ca, Na, Al), and minor (Fe, Mg, Ba, Ti, Mn, Cu, Sb, Co, Pb) glass constituents. The analytes were determined using multi-element matrix matched standard solutions. The analytical data matrix was processed chemometrically in order to evaluate the examined protocols in terms of their accuracy, precision and sensitivity, and eventually select the most efficient method for ancient glass. ICP-AES parameters such as spectral line, RF power and sample flow rate were optimized using the proposed protocol. Finally, the optimum method was successfully applied to the analysis of a number of ancient glass fragments.

  4. Global Optimization of the IR Matrix-Assisted Laser Desorption Ionization (IR MALDESI) Source for Mass Spectrometry Using Statistical Design of Experiments

    PubMed Central

    Barry, Jeremy A.; Muddiman, David C.

    2013-01-01

    Design of experiments (DOE) is a systematic and cost-effective approach to system optimization by which the effects of multiple parameters and parameter interactions on a given response can be measured in few experiments. Herein, we describe the use of statistical DOE to improve a few of the analytical figures of merit of the infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) source for mass spectrometry. In a typical experiment, bovine cytochrome c (~12 kDa) was ionized via electrospray, and equine cytochrome c (~12 kDa) was desorbed and ionized by IR-MALDESI such that the ratio of equine:bovine was used as a measure of the ionization efficiency of IR-MALDESI. This response was used to rank the importance of seven source parameters including flow rate, laser fluence, laser repetition rate, ESI emitter to mass spectrometer inlet distance, sample stage height, sample plate voltage, and the sample to mass spectrometer inlet distance. A screening fractional factorial DOE was conducted to designate which of the seven parameters induced the greatest amount of change in the response. These important parameters (flow rate, stage height, sample to mass spectrometer inlet distance, and laser fluence) were then studied at higher resolution using a full factorial DOE to obtain the globally optimized combination of parameter settings. The optimum combination of settings was then compared with our previously determined settings to quantify the degree of improvement in detection limit. The limit of detection for the optimized conditions was approximately 10 attomoles compared with 100 femtomoles for the previous settings, which corresponds to a four order of magnitude improvement in the detection limit of equine cytochrome c. PMID:22095501

  5. Modeling and optimization of ultrasound-assisted extraction of polyphenolic compounds from Aronia melanocarpa by-products from filter-tea factory.

    PubMed

    Ramić, Milica; Vidović, Senka; Zeković, Zoran; Vladić, Jelena; Cvejin, Aleksandra; Pavlić, Branimir

    2015-03-01

    Aronia melanocarpa by-product from filter-tea factory was used for the preparation of extracts with high content of bioactive compounds. Extraction process was accelerated using sonication. Three level, three variable face-centered cubic experimental design (FCD) with response surface methodology (RSM) was used for optimization of extraction in terms of maximized yields for total phenolics (TP), flavonoids (TF), anthocyanins (MA) and proanthocyanidins (TPA) contents. Ultrasonic power (X₁: 72-216 W), temperature (X₂: 30-70 °C) and extraction time (X₃: 30-90 min) were investigated as independent variables. Experimental results were fitted to a second-order polynomial model where multiple regression analysis and analysis of variance were used to determine fitness of the model and optimal conditions for investigated responses. Three-dimensional surface plots were generated from the mathematical models. The optimal conditions for ultrasound-assisted extraction of TP, TF, MA and TPA were: X₁=206.64 W, X₂=70 °C, X₃=80.1 min; X₁=210.24 W, X₂=70 °C, X₃=75 min; X₁=216 W, X₂=70 °C, X₃=45.6 min and X₁=199.44 W, X₂=70 °C, X₃=89.7 min, respectively. Generated model predicted values of the TP, TF, MA and TPA to be 15.41 mg GAE/ml, 9.86 mg CE/ml, 2.26 mg C3G/ml and 20.67 mg CE/ml, respectively. Experimental validation was performed and close agreement between experimental and predicted values was found (within 95% confidence interval).

  6. Optimization of two different dispersive liquid-liquid microextraction methods followed by gas chromatography-mass spectrometry determination for polycyclic aromatic hydrocarbons (PAHs) analysis in water.

    PubMed

    Tseng, Wan-Chi; Chen, Pai-Shan; Huang, Shang-Da

    2014-03-01

    Novel sample preparation methods termed "up-and-down shaker-assisted dispersive liquid-liquid microextraction (UDSA-DLLME)" and "water with low concentration of surfactant in dispersed solvent-assisted emulsion dispersive liquid-liquid microextraction (WLSEME)" coupled with gas chromatography-mass spectrometry (GC-MS) have been developed for the analysis of 11 polycyclic aromatic hydrocarbons (PAHs) in aqueous samples. For UDSA-DLLME, an up-and-down shaker-assisted emulsification was employed. Extraction was complete in 3min. Only 14 μL of 1-heptanol was required, without a dispersive solvent. Under the optimum conditions, the linear range was 0.08-100 µg L(-1), and the LODs were in the range 0.022-0.060 µg L(-1). The enrichment factors (EFs) ranged from 392 to 766. Relative recoveries were between 84% and 113% for river, lake, and field water. In WLSEME, 9 μL of 1-nonanol as extraction solvent and 240 μL of 1 mg L(-1) Triton X-100 as surfactant were mixed in a microsyringe to form a cloudy emulsified solution, which was then injected into the samples. Compared with other surfactant-assisted emulsion methods, WLSEME uses much less surfactant. The linear range was 0.08-100 µg L(-1), and the LODs were 0.022-0.13 µg L(-1). The EFs ranged from 388 to 649. The relative recoveries were 86-114% for all three water specimens.

  7. Conventional gas ventilation, liquid-assisted high-frequency oscillatory ventilation, and tidal liquid ventilation in surfactant-treated preterm lambs.

    PubMed

    Degraeuwe, P L; Thunnissen, F B; Jansen, N J; Dormaar, J T; Dohmen, L R; Blanco, C E

    2000-11-01

    This study was designed to compare the efficacy and potential protective or injurious effects of tidal liquid ventilation (TLV), liquid-assisted high-frequency oscillatory ventilation (LA-HFOV), and high PEEP conventional mechanical ventilation (CMV) in neonatal respiratory distress syndrome. Preterm lambs (124-126 days gestation), prophylactically treated with natural surfactant, were allocated to one of the treatment modalities or to an untreated fetal control group (F), euthanised after tracheal ligation. LA-HFOV animals received an intratracheal loading dose of 5 mL x kg(-1) followed by a continuous intrapulmonary instillation of 12 mL x kg(-1);h(-1) FC-75 perfluorocarbon liquid. The ventilation strategies aimed at keeping clinically appropriate arterial blood gases for a study period of 5 hours. A histological lung injury score was calculated and semiquantitative morphometry was performed on lung tissue fixed by vascular perfusion. The alveolar-arterial pressure difference for O2 was significantly lower throughout the study in TLV compared to CMV lambs; at 1, 2, and 5 hours, oxygenation was better in TLV when compared to LA-HFOV. Total lung injury scores in TLV lambs were significantly lower than in either CMV or LA-HFOV animals, but higher when compared to F. CMV and LA-HFOV induced an excess of collapsed and overdistended alveoli, whereas in TLV alveolar expansion was normally distributed around predominantly normal alveoli. CMV and LA-HFOV, but not TLV, were associated with an excess of dilated airways. Thus, in the ovine neonatal RDS model, TLV compared favourably to either gas ventilation strategy by its more uniform ventilation, reduced lung injury, and improved gas exchange.

  8. Using the Eclipse Parallel Tools Platform to Assist Earth Science Model Development and Optimization on High Performance Computers

    NASA Astrophysics Data System (ADS)

    Alameda, J. C.

    2011-12-01

    Development and optimization of computational science models, particularly on high performance computers, and with the advent of ubiquitous multicore processor systems, practically on every system, has be