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Sample records for external pore loop

  1. Anti-Gravity Loop-shaped heat pipe with graded pore-size wick

    International Nuclear Information System (INIS)

    Tang Yong; Zhou Rui; Lu Longsheng; Xie Zichun

    2012-01-01

    An Anti-Gravity Loop-Shaped Heat Pipe (AGLSHP) with a Continuous Graded Pore-Size Wick (CGPSW) was developed for the cooling of electronic devices at the anti-gravity orientation on the ground. At this orientation, heat is transferred toward the direction of the gravitational field. The AGLSHP consists of an evaporator, a condenser, a vapor line and a liquid line. The CGPSW is formed by sintered copper powders and it is filled inside the evaporator and the liquid line. The corresponding test system was developed to investigate the start-up characteristics and heat transfer performance of the AGLSHP at the anti-gravity orientation. The experimental result shows that, the AGLSHP has the capability to start-up reliably without any temperature overshoot or oscillation at the test heat loads. And the AGLSHP is able to keep the temperature of the evaporator below 105 °C and the overall thermal resistance below 0.24 °C/W at the heat load of 100 W. It is also found that the ideal heat load range of the AGLSHP at the anti-gravity orientation is from 30 W to 90 W. In this power range the overall thermal resistance stabilizes at about 0.15 °C/W, and the maximum temperature of the evaporator is lower than 84 °C at the heat load of 90 W. - Highlights: ► We present a loop-shaped heat pipe for the anti-gravity application on the ground. ► We present the continuous graded pore-size wick and its fabrication process. ► We test the start-up and heat transfer performance of this loop-shaped heat pipe. ► This loop-shaped heat pipe starts up reliably and has satisfying heat transfer capability.

  2. Silicon photonic dynamic optical channel leveler with external feedback loop.

    Science.gov (United States)

    Doylend, J K; Jessop, P E; Knights, A P

    2010-06-21

    We demonstrate a dynamic optical channel leveler composed of a variable optical attenuator (VOA) integrated monolithically with a defect-mediated photodiode in a silicon photonic waveguide device. An external feedback loop mimics an analog circuit such that the photodiode directly controls the VOA to provide blind channel leveling within +/-1 dB across a 7-10 dB dynamic range for wavelengths from 1530 nm to 1570 nm. The device consumes approximately 50 mW electrical power and occupies a 6 mm x 0.1 mm footprint per channel. Dynamic leveling is accomplished without tapping optical power from the output path to the photodiode and thus the loss penalty is minimized.

  3. Antibodies to the extracellular pore loop of TRPM8 act as antagonists of channel activation.

    Directory of Open Access Journals (Sweden)

    Silke Miller

    Full Text Available The mammalian transient receptor potential melastatin channel 8 (TRPM8 is highly expressed in trigeminal and dorsal root ganglia. TRPM8 is activated by cold temperature or compounds that cause a cooling sensation, such as menthol or icilin. TRPM8 may play a role in cold hypersensitivity and hyperalgesia in various pain syndromes. Therefore, TRPM8 antagonists are pursued as therapeutics. In this study we explored the feasibility of blocking TRPM8 activation with antibodies. We report the functional characterization of a rabbit polyclonal antibody, ACC-049, directed against the third extracellular loop near the pore region of the human TRPM8 channel. ACC-049 acted as a full antagonist at recombinantly expressed human and rodent TRPM8 channels in cell based agonist-induced 45Ca2+ uptake assays. Further, several poly-and monoclonal antibodies that recognize the same region also blocked icilin activation of not only recombinantly expressed TRPM8, but also endogenous TRPM8 expressed in rat dorsal root ganglion neurons revealing the feasibility of generating monoclonal antibody antagonists. We conclude that antagonist antibodies are valuable tools to investigate TRPM8 function and may ultimately pave the way for development of therapeutic antibodies.

  4. Polyakov loop fluctuations in the presence of external fields

    Science.gov (United States)

    Lo, Pok Man; Szymański, Michał; Redlich, Krzysztof; Sasaki, Chihiro

    2018-06-01

    We study the implications of the spontaneous and explicit Z(3) center symmetry breaking for the Polyakov loop susceptibilities. To this end, ratios of the susceptibilities of the real and imaginary parts, as well as of the modulus of the Polyakov loop are computed within an effective model using a color group integration scheme. We show that the essential features of the lattice QCD results of these ratios can be successfully captured by the effective approach. Furthermore we discuss a novel scaling relation in one of these ratios involving the explicit breaking field, volume, and temperature.

  5. Beyond the rhizosphere: growth and function of arbuscular mycorrhizal external hyphae in sands of varying pore sizes

    DEFF Research Database (Denmark)

    Drew, E.A.; Murray, R.S.; Smith, S.E.

    2003-01-01

    Research on nutrient acquisition by symbiotic arbuscular mycorrhizal (AM) fungi has mainly focused on the root fungus interface and less attention has been given to the growth and functioning of external hyphae in the bulk soil. The growth and function of external hyphae may be affected....... intraradices obtained a greater proportion of P at a distance from the host roots. Differences in P acquisition were not correlated with production of external hyphae in the four media zones and changes in sand pore size did not affect the ability of the fungi studied to acquire P at a distance from the host...... roots. Production of external hyphae in HC2 was influenced by fungal species and media treatment. Both fungi produced maximum amounts of external hyphae in the soil medium. Sand pore size affected growth of G. intraradices (but not G. mosseae) and hyphal diameter distributions of both fungi. The results...

  6. The Life Cycle Evaluation Model of External Diseconomy of Open-loop Supply Chain

    Science.gov (United States)

    Liu, Qian; Hu, Tianjun

    2017-08-01

    In recent years, with the continuous deterioration of pollution, resource space is gradually narrowed, the number of waste items increased, people began to use the method of recycling on waste products to ease the pressure on the environment. This paper adopted the external diseconomy of open-loop supply chain as the research object and constructed the model by the life cycle evaluation method, comparative analysis through the case. This paper also concludes that the key to solving the problem is to realize the closed-loop supply chain and building reverse logistics system is of great significance.

  7. A Digital Phase Lock Loop for an External Cavity Diode Laser

    Science.gov (United States)

    Wang, Xiao-Long; Tao, Tian-Jiong; Cheng, Bing; Wu, Bin; Xu, Yun-Fei; Wang, Zhao-Ying; Lin, Qiang

    2011-08-01

    A digital optical phase lock loop (OPLL) is implemented to synchronize the frequency and phase between two external cavity diode lasers (ECDL), generating Raman pulses for atom interferometry. The setup involves all-digital phase detection and a programmable digital proportional-integral-derivative (PID) loop in locking. The lock generates a narrow beat-note linewidth below 1 Hz and low phase-noise of 0.03rad2 between the master and slave ECDLs. The lock proves to be stable and robust, and all the locking parameters can be set and optimized on a computer interface with convenience, making the lock adaptable to various setups of laser systems.

  8. Rapid Pore Cranial Drilling With External Ventricular Drainage for Treatment of Intraventricular Hemorrhage: A 36-Year Case Series.

    Science.gov (United States)

    Zhang, Wei; Wei, Lin; Li, Gang; Sun, Jinlong; Jin, Peng; Yang, Jun; Wang, Daokui; Bai, Yunan; Li, Xingang; Fei, Chang; Wang, Chengwei; Wang, Baoan; Pan, Shumao; Du, Jihai; Xie, Bo; Xu, Dongfang; Xin, Changming; Wang, Jihua; Zhang, Qinglin

    2015-06-01

    This study aimed to describe the technique details of rapid pore cranial drilling with external ventricular drainage and document its clinical outcomes by highlighting the advantages over the traditional and modified cranial drilling technique. Intraventricular hemorrhage is one of the most severe subtypes of hemorrhagic stroke with high mortality. The amount of blood in the ventricles is associated with severity of outcomes, and fast removal of the blood clot is the key to a good prognosis. Between 1977 and 2013, 3773 patients admitted for intraventricular hemorrhage underwent rapid pore cranial drilling drainage. The therapeutic effects and clinical outcomes were retrospectively analyzed. Of these patients, 1049 (27.8%) experienced complete remission, 1788 (47.4%) had improved condition, and 936 (24.8%) died. A total of 3229 (85.6%) patients gained immediate remission. One typical case was illustrated to demonstrate the efficacy of the rapid pore drilling technique. Rapid pore cranial drilling drainage in patients with intraventricular hemorrhage is fast, effective, and provides immediate relief in patients with severe conditions. It could be a better alternative to the conventional drilling approach for treatment of intraventricular hemorrhage. A randomized controlled trial for direct comparison between the rapid pore cranial drilling drainage and conventional drilling technique is in urgent need.

  9. Use of implantable and external loop recorders in syncope with unknown causes

    Directory of Open Access Journals (Sweden)

    Kaoru Tanno

    2017-12-01

    Full Text Available The gold standard for diagnosing syncope is to elucidate the symptom-electrocardiogram (ECG correlation. The ECG recordings during syncope allow physicians to either confirm or exclude an arrhythmia as the mechanism of syncope. Many studies have investigated the use of internal loop recorder (ILR, while few studies have used external loop recorder (ELR for patients with unexplained syncope. The aim of this review is to clarify the clinical usefulness of ILR and ELR in the diagnosis and management of patients with unexplained syncope. Many observational and four randomized control studies have shown that ILR for patients with unknown syncope is a useful tool for early diagnosis and improving diagnosis rate. ILR also provides important information on the mechanism of syncope and treatment strategy. However, there is no evidence of total mortality or quality of life improvements with ILR. The diagnostic yield of ELR in patients with syncope was similar to that with ILR within the same timeframe. Therefore, ELR could be considered for long-term ECG monitoring before a patient switches to using ILR. A systematic approach and selection of ECG monitoring tools reduces health care costs and improves the selection of patients for optimal treatment possibilities. Keywords: Internal loop recorder, External loop recorder, Unknown Syncope

  10. Co-Aromatization of Methane with Olefins: The Role of Inner Pore and External Surface Catalytic Sites

    Energy Technology Data Exchange (ETDEWEB)

    Yung, Matthew M [National Renewable Energy Laboratory (NREL), Golden, CO (United States); He, Peng [University of Calgary; Jarvis, Jack [University of Calgary; Meng, Shijun [University of Calgary; Wang, Aiguo [University of Calgary; Kou, Shiyu [University of Calgary; Gatip, Richard [University of Calgary; Liu, Lijia [Soochow University; Song, Hua [University of Calgary

    2018-04-22

    The co-aromatization of methane with olefins is investigated using Ag-Ga/HZSM-5 as the catalyst at 400 degrees C. The presence of methane has a pronounced effect on the product distribution in terms of increased average carbon number and substitution index and decreased aromatic carbon fraction compared with its N2 environment counterpart. The participation of methane during the co-aromatization over the Ag-Ga/HZSM-5 catalyst diminishes as the co-fed olefin feedstock molecule becomes larger, from 1-hexene to 1-octene and 1-decene, in diameter. The effect of suppressed methane participation with larger olefinic molecules is not as significant when Ag-Ga/HY is employed as the catalyst, which might be attributed to the larger pore size of HY that gives more room to hold olefin and methane molecules within the inner pores and reduces the diffusion limitation of olefin molecules. The effect of olefin feedstock on the methane participation during the co-aromatization over Ag-Ga/HZSM-5 is experimentally evidenced by 13C and 2D NMR. The incorporation of the methane carbon atoms into the phenyl ring of product molecules is reduced significantly with larger co-fed olefins, whereas its incorporation into the substitution groups of the formed aromatic molecules is not notably affected, suggesting that the methane participation in the phenyl ring formation might preferably occur within inner pores, while its incorporation into substitution groups may mainly take place on external catalytic sites. This hypothesis is well supported by the product selectivity obtained over Ag-Ga/HZSM-5 catalysts prepared using conventional ZSM-5, ZSM-5 with the external catalytic sites deactivated, nanosize ZSM-5, ZSM-5 with a micro/meso pore structure and ZSM-5 with the inner pores blocked, and further confirmed by the isotopic labeling studies.

  11. CALCULATION OF DESORPTION BRANCH OF HYSTERESIS LOOP TOR THE ADSORBENTS OF CORPUSCULAR STRUCTURE ON THE BASIS OF MODEL OF CYLINDRICAL PORES

    Directory of Open Access Journals (Sweden)

    V. V. Kutarov

    2015-02-01

    Full Text Available The method of calculation of desorption branch of hysteresis loop for the adsorbents of corpus­cular structure is offered. The method is based on the model of cylindrical pores. Applicability of equation is tested by a way comparing of calculation results to information, certain on experimental isotherms, on the example of two adsorption systems with different adsorbents and adsorbats

  12. External K+ dependence of strong inward rectifier K+ channel conductance is caused not by K+ but by competitive pore blockade by external Na.

    Science.gov (United States)

    Ishihara, Keiko

    2018-06-15

    Strong inward rectifier K + (sKir) channels determine the membrane potentials of many types of excitable and nonexcitable cells, most notably the resting potentials of cardiac myocytes. They show little outward current during membrane depolarization (i.e., strong inward rectification) because of the channel blockade by cytoplasmic polyamines, which depends on the deviation of the membrane potential from the K + equilibrium potential ( V - E K ) when the extracellular K + concentration ([K + ] out ) is changed. Because their open - channel conductance is apparently proportional to the "square root" of [K + ] out , increases/decreases in [K + ] out enhance/diminish outward currents through sKir channels at membrane potentials near their reversal potential, which also affects, for example, the repolarization and action-potential duration of cardiac myocytes. Despite its importance, however, the mechanism underlying the [K + ] out dependence of the open sKir channel conductance has remained elusive. By studying Kir2.1, the canonical member of the sKir channel family, we first show that the outward currents of Kir2.1 are observed under the external K + -free condition when its inward rectification is reduced and that the complete inhibition of the currents at 0 [K + ] out results solely from pore blockade caused by the polyamines. Moreover, the noted square-root proportionality of the open sKir channel conductance to [K + ] out is mediated by the pore blockade by the external Na + , which is competitive with the external K + Our results show that external K + itself does not activate or facilitate K + permeation through the open sKir channel to mediate the apparent external K + dependence of its open channel conductance. The paradoxical increase/decrease in outward sKir channel currents during alternations in [K + ] out , which is physiologically relevant, is caused by competition from impermeant extracellular Na . © 2018 Ishihara.

  13. FROZEN ASH BERRIES PROCESSING IN THE DEVICE WITH A NOZZLE CONTINUOUS VIBRATION, EQUIPPED WITH AN EXTERNAL RECIRCULATION LOOP

    Directory of Open Access Journals (Sweden)

    P. P. Ivanov

    2015-01-01

    Full Text Available An external recirculation loop was used as the method of increasing the concentration of dry soluble substances in the obtained extract. The objective of the research is to determine the value of the external recirculation index (KR, which provides the optimal conditions for the process carrying out. The results of the conducted research show the increase in the concentration of dry soluble substances in the extract if the external recirculation index increases. It is conditioned by the extension of the interaction between the processed raw mate-rial and the extract, as well as by the decrease in the surface tension of the extracting agent, which results in improving the conditions of its penetration into the pores of particles. Such an opposite property of recirculation as the decrease in mass transfer rate was also ob-served. It causes the significant rise of dry soluble substances losses while discharging extraction cake, which leads to the performance degradation. According to the analytical evaluation of the obtained results, the maximum process results are observed if KR = 1 (without recirculation and KR = 2, the values of the optimality criterion are 5.02∙10-3 and 4.92∙10-3 % mass/W respectively. At the same time the operation of the apparatus with the recirculation loop at KR = 2 is characterized by 62%-increase in dry soluble substances concentration in the extract as compared to a pure extracting agent. The efficiency of recirculation at KR = 2 is proved by the saving of energy con-sumed on the evaporation of the extract obtained. The energy costs calculation for the production of 60l of 12 % mass dry soluble sub-stances concentration extract showed that if the initial dry soluble substances concentration is raised to 6 % mass (KR = 2, the amount of consumed saturated vapor is 104.1 kg less, which is 281685 kJ if the vapor specific enthalpy is 2706.29 kJ/kg.

  14. A Digital Phase Lock Loop for an External Cavity Diode Laser

    International Nuclear Information System (INIS)

    Wang Xiao-Long; Tao Tian-Jiong; Cheng Bing; Wu Bin; Xu Yun-Fei; Wang Zhao-Ying; Lin Qiang

    2011-01-01

    A digital optical phase lock loop (OPLL) is implemented to synchronize the frequency and phase between two external cavity diode lasers (ECDL), generating Raman pulses for atom interferometry. The setup involves all-digital phase detection and a programmable digital proportional-integral-derivative (PID) loop in locking. The lock generates a narrow beat-note linewidth below 1 Hz and low phase-noise of 0.03rad 2 between the master and slave ECDLs. The lock proves to be stable and robust, and all the locking parameters can be set and optimized on a computer interface with convenience, making the lock adaptable to various setups of laser systems. (fundamental areas of phenomenology(including applications))

  15. Reovirus FAST Proteins Drive Pore Formation and Syncytiogenesis Using a Novel Helix-Loop-Helix Fusion-Inducing Lipid Packing Sensor.

    Directory of Open Access Journals (Sweden)

    Jolene Read

    2015-06-01

    Full Text Available Pore formation is the most energy-demanding step during virus-induced membrane fusion, where high curvature of the fusion pore rim increases the spacing between lipid headgroups, exposing the hydrophobic interior of the membrane to water. How protein fusogens breach this thermodynamic barrier to pore formation is unclear. We identified a novel fusion-inducing lipid packing sensor (FLiPS in the cytosolic endodomain of the baboon reovirus p15 fusion-associated small transmembrane (FAST protein that is essential for pore formation during cell-cell fusion and syncytiogenesis. NMR spectroscopy and mutational studies indicate the dependence of this FLiPS on a hydrophobic helix-loop-helix structure. Biochemical and biophysical assays reveal the p15 FLiPS preferentially partitions into membranes with high positive curvature, and this partitioning is impeded by bis-ANS, a small molecule that inserts into hydrophobic defects in membranes. Most notably, the p15 FLiPS can be functionally replaced by heterologous amphipathic lipid packing sensors (ALPS but not by other membrane-interactive amphipathic helices. Furthermore, a previously unrecognized amphipathic helix in the cytosolic domain of the reptilian reovirus p14 FAST protein can functionally replace the p15 FLiPS, and is itself replaceable by a heterologous ALPS motif. Anchored near the cytoplasmic leaflet by the FAST protein transmembrane domain, the FLiPS is perfectly positioned to insert into hydrophobic defects that begin to appear in the highly curved rim of nascent fusion pores, thereby lowering the energy barrier to stable pore formation.

  16. Modeling of the Near Field Coupling Between an External Loop and an Implantable Spiral Chip Antennas in Biosensor Systems

    Science.gov (United States)

    Simons, Rainee N.; Miranda, Felix A.

    2006-01-01

    In this paper, the near field coupling between an external hand-held loop antenna and an implantable miniature (1x1 mm) printed square spiral chip antenna used in bio-MEMS sensors for contact-less powering and RF telemetry is investigated. The loop and the spiral are inductively coupled and effectively form a transformer. The numerical results include the quasi-stationary magnetic field pattern of the implanted antenna, near zone wave impedance as a function of the radial distance and the values of the lumped elements in the equivalent circuit model for the transformer.

  17. Electrocoagulation/electroflotation of reactive, disperse and mixture dyes in an external-loop airlift reactor

    International Nuclear Information System (INIS)

    Balla, Wafaa; Essadki, A.H.; Gourich, B.; Dassaa, A.; Chenik, H.; Azzi, M.

    2010-01-01

    This paper studied the efficiency of electrocoagulation/electroflotation in removing colour from synthetic and real textile wastewater by using aluminium and iron electrodes in an external-loop airlift reactor of 20 L. The disperse dye is a mixture of Yellow terasil 4G, Red terasil 343 150% and Blue terasil 3R02, the reactive dye is a mixture of Red S3B 195, Yellow SPD, Blue BRFS. For disperse dye, the removal efficiency was better using aluminium electrodes, whereas, the iron electrodes showed more efficiency for removing colour for reactive dye and mixed synthetic dye. Both for disperse, reactive and mixed dye, 40 mA cm -2 and 20 min were respectively the optimal current density and electrolysis time. 7.5 was an optimal initial pH for both reactive and mixed synthetic dye and 6.2 was an optimal initial pH for disperse dye. The colour efficiency reached in general 90%. The results showed also that Red and Blue disappeared quickly comparatively to the Yellow component both for reactive and disperse dyes. The real textile wastewater was then used. Three effluents were also used: disperse, reactive and the mixture. The colour efficiency is between 70 and 90% and COD efficiency reached 78%. The specific electrical energy consumption per kg dye removed (E dye ) in optimal conditions for real effluent was calculated. 170 kWh/kg dye was required for a reactive dye, 120 kWh/kg dye for disperse and 50 kWh/kg dye for the mixture.

  18. Electrocoagulation/electroflotation of reactive, disperse and mixture dyes in an external-loop airlift reactor

    Energy Technology Data Exchange (ETDEWEB)

    Balla, Wafaa [Ecole Superieure de Technologie, Laboratoire Genie des Procedes et Environnement, B.P. 8012, Oasis, Casablanca (Morocco); Faculte des sciences Ain Chock, Laboratoire d' Electrochimie et chimie de l' environnement, B.P. 5366, Maarif, Casablanca (Morocco); Essadki, A.H., E-mail: essadki@est-uh2c.ac.ma [Ecole Superieure de Technologie, Laboratoire Genie des Procedes et Environnement, B.P. 8012, Oasis, Casablanca (Morocco); Gourich, B. [Ecole Superieure de Technologie, Laboratoire Genie des Procedes et Environnement, B.P. 8012, Oasis, Casablanca (Morocco); Dassaa, A. [Faculte des sciences Ain Chock, Laboratoire d' Electrochimie et chimie de l' environnement, B.P. 5366, Maarif, Casablanca (Morocco); Chenik, H. [Ecole Superieure de Technologie, Laboratoire Genie des Procedes et Environnement, B.P. 8012, Oasis, Casablanca (Morocco); Faculte des sciences Ain Chock, Laboratoire d' Electrochimie et chimie de l' environnement, B.P. 5366, Maarif, Casablanca (Morocco); Azzi, M. [Faculte des sciences Ain Chock, Laboratoire d' Electrochimie et chimie de l' environnement, B.P. 5366, Maarif, Casablanca (Morocco)

    2010-12-15

    This paper studied the efficiency of electrocoagulation/electroflotation in removing colour from synthetic and real textile wastewater by using aluminium and iron electrodes in an external-loop airlift reactor of 20 L. The disperse dye is a mixture of Yellow terasil 4G, Red terasil 343 150% and Blue terasil 3R02, the reactive dye is a mixture of Red S3B 195, Yellow SPD, Blue BRFS. For disperse dye, the removal efficiency was better using aluminium electrodes, whereas, the iron electrodes showed more efficiency for removing colour for reactive dye and mixed synthetic dye. Both for disperse, reactive and mixed dye, 40 mA cm{sup -2} and 20 min were respectively the optimal current density and electrolysis time. 7.5 was an optimal initial pH for both reactive and mixed synthetic dye and 6.2 was an optimal initial pH for disperse dye. The colour efficiency reached in general 90%. The results showed also that Red and Blue disappeared quickly comparatively to the Yellow component both for reactive and disperse dyes. The real textile wastewater was then used. Three effluents were also used: disperse, reactive and the mixture. The colour efficiency is between 70 and 90% and COD efficiency reached 78%. The specific electrical energy consumption per kg dye removed (E{sub dye}) in optimal conditions for real effluent was calculated. 170 kWh/kg{sub dye} was required for a reactive dye, 120 kWh/kg{sub dye} for disperse and 50 kWh/kg{sub dye} for the mixture.

  19. MRI-guided percutaneous cryoablation of renal tumors: Use of external manual displacement of adjacent bowel loops

    International Nuclear Information System (INIS)

    Tuncali, Kemal; Morrison, Paul R.; Tatli, Servet; Silverman, Stuart G.

    2006-01-01

    Purpose: We sought to investigate retrospectively the safety and effectiveness of using external hand compression to displace adjacent bowel loops during MRI-guided percutaneous cryoablation of renal tumors. Materials and methods: Fourteen patients (six women, eight men; mean age: 72 years) with 15 renal tumors (mean diameter: 2.4 cm; range: 1.4-4.6 cm) adjacent to bowel were treated with MRI-guided percutaneous cryoablation during which bowel was displaced manually. Bowel loop of concern was ascending colon (n 5), descending colon (n = 8), descending colon and small bowel (n = 1), ascending colon and small bowel (n = 1). To analyze effectiveness of the maneuver, mean distance between tumor margin and bowel before and after the maneuver were compared and analyzed using paired Student's t-test. Minimum distance between iceball edge and adjacent bowel with external manual displacement during freezing was also measured. Safety was assessed by analyzing post-procedural MR imaging for adjacent bowel wall thickening and focal fluid collections as well as patients' clinical and imaging follow-up. Results: Mean distance between tumor margin and closest adjacent bowel increased from 0.8 cm (range: 0-2 cm) before external manual compression to 2.6 cm (range: 1.6-4.1 cm) with manual displacement (p < 0.01). Mean minimum distance between iceball edge and closest adjacent bowel during the procedures was 1.6 cm (range: 0.5-3.5 cm). No evidence of bowel injury was encountered. Twelve of 15 tumors had follow-up (mean: 10 months) that showed no tumor recurrence. Conclusion: MRI-guided percutaneous cryoablation of renal tumors adjacent to bowel can be done safely and effectively using external hand compression to displace bowel loops

  20. Production of polygalacturonases by Aspergillus oryzae in stirred tank and internal- and external-loop airlift reactors.

    Science.gov (United States)

    Fontana, Roselei Claudete; da Silveira, Maurício Moura

    2012-11-01

    The production of endo- and exo-polygalacturonase (PG) by Aspergillus oryzae was assessed in stirred tank reactors (STRs), internal-loop airlift reactors (ILARs) and external-loop airlift reactors (ELARs). For STR production, we compared culture media formulated with either pectin (WBE) or partially hydrolyzed pectin. The highest enzyme activities were obtained in medium that contained 50% pectin in hydrolyzed form (WBE5). PG production in the three reactor types was compared for WBE5 and low salt WBE medium, with additional salts added at 48, 60 and 72h (WBES). The ELARs performed better than the ILARs in WBES medium where the exo-PG was the same concentration as for STRs and the endo-PG was 20% lower. These results indicate that PG production is higher under experimental conditions that result in higher cell growth with minimum pH values less than 3.0. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Effect of External Pressure Drop on Loop Heat Pipe Operating Temperature

    Science.gov (United States)

    Jentung, Ku; Ottenstein, Laura; Rogers, Paul; Cheung, Kwok; Obenschain, Arthur F. (Technical Monitor)

    2002-01-01

    This paper discusses the effect of the pressure drop on the operating temperature in a loop heat pipe (LHP). Because the evaporator and the compensation chamber (CC) both contain two-phase fluid, a thermodynamic constraint exists between the temperature difference and the pressure drop for these two components. As the pressure drop increases, so will the temperature difference. The temperature difference in turn causes an increase of the heat leak from the evaporator to the CC, resulting in a higher CC temperature. Furthermore, the heat leak strongly depends on the vapor void fraction inside the evaporator core. Tests were conducted by installing a valve on the vapor line so as to vary the pressure drop, and by charging the LHP with various amounts of fluid. Test results verify that the LHP operating temperature increases with an increasing differential pressure, and the temperature increase is a strong function of the fluid inventory in the loop.

  2. Biodegradation of high strength phenolic wastewater in a modified external loop inversed fluidized bed airlift bioreactor (EIFBAB)

    Energy Technology Data Exchange (ETDEWEB)

    Aye, T. T.; Loh, K-C. [National University of Singapore, Dept. of Chemical and Environmental Engineering, (Singapore)

    2003-12-01

    Phenol degradation at high concentrations was investigated in both batch and continuous mode, using a modified external loop inversed fluidized bed airlift bioreactor (EIFBAB). It was found that the modified EIFBAB, when operated at five litres/hour was capable of degrading 3,000 mg/L phenol. Under continuous operation the bioreactor was capable of degrading up to 5,000 mg/L phenol, with gradual acclimatization of the biofilm on the expanded polystyrene beads. Response of the system under shock loading was also evaluated. Results showed that the system was able to absorb the shock well up to 5,000 mg/L phenol. Although phenol breakthrough was evident in the effluent beyond 4,500 mg/L., the increase in effluent phenol concentration was gradual, and the effluent concentration did not increase beyond 1,000 mg/L phenol. 6 refs., 3 tabs., 3 figs.

  3. Glu-311 in External Loop 4 of the Sodium/Proline Transporter PutP Is Crucial for External Gate Closure*

    Science.gov (United States)

    Bracher, Susanne; Guérin, Kamila; Polyhach, Yevhen; Jeschke, Gunnar; Dittmer, Sophie; Frey, Sabine; Böhm, Maret; Jung, Heinrich

    2016-01-01

    The available structural information on LeuT and structurally related transporters suggests that external loop 4 (eL4) and the outer end of transmembrane domain (TM) 10′ participate in the reversible occlusion of the outer pathway to the solute binding sites. Here, the functional significance of eL4 and the outer region of TM10′ are explored using the sodium/proline symporter PutP as a model. Glu-311 at the tip of eL4, and various amino acids around the outer end of TM10′ are identified as particularly crucial for function. Substitutions at these sites inhibit the transport cycle, and affect in part ligand binding. In addition, changes at selected sites induce a global structural alteration in the direction of an outward-open conformation. It is suggested that interactions between the tip of eL4 and the peptide backbone at the end of TM10′ participate in coordinating conformational alterations underlying the alternating access mechanism of transport. Together with the structural information on LeuT-like transporters, the results further specify the idea that common design and functional principles are maintained across different transport families. PMID:26728461

  4. Glu-311 in External Loop 4 of the Sodium/Proline Transporter PutP Is Crucial for External Gate Closure.

    Science.gov (United States)

    Bracher, Susanne; Guérin, Kamila; Polyhach, Yevhen; Jeschke, Gunnar; Dittmer, Sophie; Frey, Sabine; Böhm, Maret; Jung, Heinrich

    2016-03-04

    The available structural information on LeuT and structurally related transporters suggests that external loop 4 (eL4) and the outer end of transmembrane domain (TM) 10' participate in the reversible occlusion of the outer pathway to the solute binding sites. Here, the functional significance of eL4 and the outer region of TM10' are explored using the sodium/proline symporter PutP as a model. Glu-311 at the tip of eL4, and various amino acids around the outer end of TM10' are identified as particularly crucial for function. Substitutions at these sites inhibit the transport cycle, and affect in part ligand binding. In addition, changes at selected sites induce a global structural alteration in the direction of an outward-open conformation. It is suggested that interactions between the tip of eL4 and the peptide backbone at the end of TM10' participate in coordinating conformational alterations underlying the alternating access mechanism of transport. Together with the structural information on LeuT-like transporters, the results further specify the idea that common design and functional principles are maintained across different transport families. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. International Space Station (ISS) External Thermal Control System (ETCS) Loop A Pump Module (PM) Jettison Options Assessment

    Science.gov (United States)

    Murri, Daniel G.; Dwyer Cianciolo, Alicia; Shidner, Jeremy D.; Powell, Richard W.

    2014-01-01

    On December 11, 2013, the International Space Station (ISS) experienced a failure of the External Thermal Control System (ETCS) Loop A Pump Module (PM). To minimize the number of extravehicular activities (EVA) required to replace the PM, jettisoning the faulty pump was evaluated. The objective of this study was to independently evaluate the jettison options considered by the ISS Trajectory Operations Officer (TOPO) and to provide recommendations for safe jettison of the ETCS Loop A PM. The simulation selected to evaluate the TOPO options was the NASA Engineering and Safety Center's (NESC) version of Program to Optimize Simulated Trajectories II (POST2) developed to support another NESC assessment. The objective of the jettison analysis was twofold: (1) to independently verify TOPO posigrade and retrograde jettison results, and (2) to determine jettison guidelines based on additional sensitivity, trade study, and Monte Carlo (MC) analysis that would prevent PM recontact. Recontact in this study designates a propagated PM trajectory that comes within 500 m of the ISS propagated trajectory. An additional simulation using Systems Tool Kit (STK) was run for independent verification of the POST2 simulation results. Ultimately, the ISS Program removed the PM jettison option from consideration. However, prior to the Program decision, the retrograde jettison option remained part of the EVA contingency plan. The jettison analysis presented showed that, in addition to separation velocity/direction and the atmosphere conditions, the key variables in determining the time to recontact the ISS is highly dependent on the ballistic number (BN) difference between the object being jettisoned and the ISS.

  6. Evolution of magnetic and transport properties in pore-modified CoAlO antidot arrays

    International Nuclear Information System (INIS)

    Ma, Y G; Lim, S L; Ong, C K

    2007-01-01

    CoAlO composite antidot arrays were fabricated on self-organized porous anodic aluminium oxide (AAO) membranes. The effects of pore size and film thickness on the magnetism and magnetotransport properties of the CoAlO films were investigated. On increasing the pore dimensions in the arrays, an anisotropic to isotropic magnetism transition was observed. The result is discussed based on the competitive contributions from the external field induced uniaxial anisotropy and the topology-induced shape anisotropy superimposed by the stray fields from the pore channels. Magnetoresistance showed corresponding variations with increasing pore sizes, as evidenced by a magnetoresistance variation from typically anisotropic to nearly isotropic behaviour. When deposited on large-pored AAO membranes, the antidot arrays showed no obvious anisotropy at different film thicknesses. It led to negligible magnetoresistive loops in the thick films of high structural continuity. The possible reasons for spin-independent electron scatterings are discussed

  7. The external-internal loop of interference: two types of attention and their influence on the learning abilities of mice.

    Science.gov (United States)

    Sauce, Bruno; Wass, Christopher; Smith, Andrew; Kwan, Stephanie; Matzel, Louis D

    2014-12-01

    Attention is a component of the working memory system, and is responsible for protecting task-relevant information from interference. Cognitive performance (particularly outside of the laboratory) is often plagued by interference, and the source of this interference, either external or internal, might influence the expression of individual differences in attentional ability. By definition, external attention (also described as "selective attention") protects working memory against sensorial distractors of all kinds, while internal attention (also called "inhibition") protects working memory against emotional impulses, irrelevant information from memory, and automatically-generated responses. At present, it is unclear if these two types of attention are expressed independently in non-human animals, and how they might differentially impact performance on other cognitive processes, such as learning. By using a diverse battery of four attention tests (with varying levels of internal and external sources of interference), here we aimed both to explore this issue, and to obtain a robust and general (less task-specific) measure of attention in mice. Exploratory factor analyses revealed two factors (external and internal attention) that in total, accounted for 73% of the variance in attentional performance. Confirmatory factor analyses found an excellent fit with the data of the model of attention that assumed an external and internal distinction (with a resulting correlation of 0.43). In contrast, a model of attention that assumed one source of variance (i.e., "general attention") exhibited a poor fit with the data. Regarding the relationship between attention and learning, higher resistance against external sources of interference promoted better new learning, but tended to impair performance when cognitive flexibility was required, such as during the reversal of a previously instantiated response. The present results suggest that there can be (at least) two types of

  8. Numerical study on the influence of entrapped air bubbles on the time-dependent pore pressure distribution in soils due to external changes in water level

    Directory of Open Access Journals (Sweden)

    Ausweger Georg M.

    2016-01-01

    Full Text Available In practical geotechnical engineering soils below the groundwater table are usually regarded as a two-phase medium, consisting of solids and water. The pore water is assumed to be incompressible. However, under certain conditions soils below the groundwater table may exhibit a liquid phase consisting of water and air. The air occurs in form of entrapped air bubbles and dissolved air. Such conditions are named quasi-saturated and the assumption of incompressibility is no longer justified. In addition the entrapped air bubbles influence the hydraulic conductivity of soils. These effects are usually neglected in standard problems of geotechnical engineering. However, sometimes it is required to include the pore fluid compressibility when modelling the hydraulic behaviour of soils in order to be able to explain certain phenomena observed in the field. This is for example true for fast fluctuating water levels in reservoirs. In order to study these phenomena, numerical investigations on the influence of the pore fluid compressibility on the pore water pressure changes in a soil layer beneath a reservoir with fast fluctuating water levels were performed. Preliminary results of this study are presented and it could be shown that numerical analysis and field data are in good agreement.

  9. Closed-Loop Supply Chain Planning Model for a Photovoltaic System Manufacturer with Internal and External Recycling

    Directory of Open Access Journals (Sweden)

    Songi Kim

    2016-06-01

    Full Text Available The photovoltaic (PV generation system has been widely used since the late 1990s. Considering its lifespan of 20 to 30 years, many end-of-life systems will emerge in the near future. This is why recycling PV systems will be beneficial (and may even be detrimental to both the environment and the economy. Through the recycling process, hazardous by-product substances such as cadmium and lead can be treated properly. Moreover, valuable materials including indium, gallium, and tellurium can be extracted and reused for manufacturing purposes. Even though many studies have dealt with issues related to the PV system and its recycling policy, they lack significant factors regarding the recycling policy. This study analyzes and compares three real cases of manufacturer’s recycling policy, including Deutsche Solar, First Solar, and PV Cycle, from the perspective of a closed-loop supply chain. Two mathematical models are developed to help PV system manufacturers establish supply chain planning and choose suitable recycling policies in consideration of different circumstances. Furthermore, an experimental example of these models will be used to validate and conclude the significance of the models. The results from this study will show that recycling CdTe PV systems is much more efficient than recycling c-Si PV systems and that, in the case of c-Si, it is better to outsource recycling end-of-life systems and dispose of all manufacturing scrap.

  10. Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor

    International Nuclear Information System (INIS)

    Essadki, A.H.; Gourich, B.; Vial, Ch.; Delmas, H.; Bennajah, M.

    2009-01-01

    Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency was higher in the STR at the beginning of the electrolysis, whereas similar values were usually achieved after 15 min operation. The influence of the initial pH was explained using the analyses of sludge composition and residual soluble aluminum species in the effluents, and it was related to the prevailing mechanisms of defluoridation. Fluoride removal and sludge reduction were both favored by an initial pH around 4, but this value required an additional pre-treatment for pH adjustment. Finally, electric energy consumption was similar in both reactors when current density was lower than 12 mA/cm 2 , but mixing and complete flotation of the pollutants were achieved without additional mechanical power in the ELAR, using only the overall liquid recirculation induced by H 2 microbubbles generated by water electrolysis, which makes subsequent treatments easier to carry out.

  11. Defluoridation of drinking water by electrocoagulation/electroflotation in a stirred tank reactor with a comparative performance to an external-loop airlift reactor

    Energy Technology Data Exchange (ETDEWEB)

    Essadki, A.H., E-mail: essadki@hotmail.com [Ecole Superieure de Technologie de Casablanca, BP 8012, Oasis, Casablanca (Morocco); Gourich, B. [Ecole Superieure de Technologie de Casablanca, BP 8012, Oasis, Casablanca (Morocco); Vial, Ch. [Laboratoire de Genie Chimique et Biochimique, LGCB-UBP/ENSCCF, 24 avenue des Landais, BP 206, 63174 Aubiere Cedex (France); Delmas, H. [Laboratoire de Genie Chimique, ENSIACET-INPT, 5 rue Paulin Talabot, 31106 Toulouse (France); Bennajah, M. [Ecole Superieure de Technologie de Casablanca, BP 8012, Oasis, Casablanca (Morocco); Laboratoire de Genie Chimique, ENSIACET-INPT, 5 rue Paulin Talabot, 31106 Toulouse (France)

    2009-09-15

    Defluoridation using batch electrocoagulation/electroflotation (EC/EF) was carried out in two reactors for comparison purpose: a stirred tank reactor (STR) close to a conventional EC cell and an external-loop airlift reactor (ELAR) that was recently described as an innovative reactor for EC. The respective influences of current density, initial concentration and initial pH on the efficiency of defluoridation were investigated. The same trends were observed in both reactors, but the efficiency was higher in the STR at the beginning of the electrolysis, whereas similar values were usually achieved after 15 min operation. The influence of the initial pH was explained using the analyses of sludge composition and residual soluble aluminum species in the effluents, and it was related to the prevailing mechanisms of defluoridation. Fluoride removal and sludge reduction were both favored by an initial pH around 4, but this value required an additional pre-treatment for pH adjustment. Finally, electric energy consumption was similar in both reactors when current density was lower than 12 mA/cm{sup 2}, but mixing and complete flotation of the pollutants were achieved without additional mechanical power in the ELAR, using only the overall liquid recirculation induced by H{sub 2} microbubbles generated by water electrolysis, which makes subsequent treatments easier to carry out.

  12. Atrial fibrillation detected by external loop recording for seven days or two-day simultaneous Holter recording: A comparison in patients with ischemic stroke or transient ischemic attack.

    Science.gov (United States)

    Sejr, Michala Herskind; Nielsen, Jens Cosedis; Damgaard, Dorte; Sandal, Birgitte Forsom; May, Ole

    Atrial fibrillation (AF) is the most common cardiac cause of ischemic stroke and transient ischemic attack (IS/TIA). To compare the diagnostic value of seven-day external loop recording (ELR) and two-day Holter recording for detecting AF after IS/TIA. 191 IS/TIA patients without AF history. Endpoint was AF >30s. We started two-day Holter recording and seven-day ELR simultaneously. Seven-day ELR and two-day Holter recording detected the same three AF patients. ELR detected another six patients with AF adjudicated by cardiologists, four detections after Holter (3 vs. 7, p=0.125) and two false-positive detections during Holter. Seven-day ELR automatically classified 50/191 patients (26%) with AF, but only 7/50 (14%) were confirmed as AF by cardiologists. Seven-day ELR did not detect significantly more patients with AF than two-day Holter recording. 86% of patients with ELR-classified AF were false positives, indicating a poor performance of the automatic AF detection algorithm used. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Loop kinematics

    International Nuclear Information System (INIS)

    Migdal, A.A.

    1982-01-01

    Basic operators acting in the loop space are introduced. The topology of this space and properties of the Stokes type loop functionals are discussed. The parametrically invariant loop calculus developed here is used in the loop dynamics

  14. Mesoscale Simulations of Pore Migration in a Nuclear Fuel

    International Nuclear Information System (INIS)

    Radhakrishnan, Balasubramaniam; Gorti, Sarma B.

    2010-01-01

    The evolution of pore and grain structure in a nuclear fuel environment is strongly influenced by the local temperature, and the temperature gradient. The evolution of pore and grain structure in an externally imposed temperature gradient is simulated for a hypothetical material using a Potts model approach that allows for porosity migration by mechanisms similar to surface, grain boundary and volume diffusion, as well as the interaction of migrating pores with stationary grain boundaries. First, the migration of a single pore in a single crystal in the presence of the temperature gradient is simulated. Next, the interaction of a pore moving in a temperature gradient with a grain boundary that is perpendicular to the pore migration direction is simulated in order to capture the force exerted by the pore on the grain boundary. The simulations reproduce the expected variation of pore velocity with pore size as well as the variation of the grain boundary force with pore size.

  15. A single amino acid of human immunodeficiency virus type 2 capsid protein affects conformation of two external loops and viral sensitivity to TRIM5α.

    Directory of Open Access Journals (Sweden)

    Tadashi Miyamoto

    Full Text Available We previously reported that human immunodeficiency virus type 2 (HIV-2 carrying alanine or glutamine but not proline at position 120 of the capsid protein (CA could grow in the presence of anti-viral factor TRIM5α of cynomolgus monkey (CM. To elucidate details of the interaction between the CA and TRIM5α, we generated mutant HIV-2 viruses, each carrying one of the remaining 17 possible amino acid residues, and examined their sensitivity to CM TRIM5α-mediated restriction. Results showed that hydrophobic residues or those with ring structures were associated with sensitivity, while those with small side chains or amide groups conferred resistance. Molecular dynamics simulation study revealed a structural basis for the differential TRIM5α sensitivities. The mutations at position 120 in the loop between helices 6 and 7 (L6/7 affected conformation of the neighboring loop between helices 4 and 5 (L4/5, and sensitive viruses had a common L4/5 conformation. In addition, the common L4/5 structures of the sensitive viruses were associated with a decreased probability of hydrogen bond formation between the 97th aspartic acid in L4/5 and the 119th arginine in L6/7. When we introduced aspartic acid-to-alanine substitution at position 97 (D97A of the resistant virus carrying glutamine at position 120 to disrupt hydrogen bond formation, the resultant virus became moderately sensitive. Interestingly, the virus carrying glutamic acid at position 120 showed resistance, while its predicted L4/5 conformation was similar to those of sensitive viruses. The D97A substitution failed to alter the resistance of this particular virus, indicating that the 120th amino acid residue itself is also involved in sensitivity regardless of the L4/5 conformation. These results suggested that a hydrogen bond between the L4/5 and L6/7 modulates the overall structure of the exposed surface of the CA, but the amino acid residue at position 120 is also directly involved in CM TRIM5

  16. Predictor-based multivariable closed-loop system identification of the EXTRAP T2R reversed field pinch external plasma response

    Energy Technology Data Exchange (ETDEWEB)

    Olofsson, K Erik J; Brunsell, Per R; Drake, James R [Fusion Plasma Physics, School of Electrical Engineering, Royal Institute of Technology (KTH Stockholm), Sweden (Association EURATOM-VR) (Sweden); Rojas, Cristian R; Hjalmarsson, Haakan, E-mail: erik.olofsson@ee.kth.se [Automatic Control, School of Electrical Engineering, KTH Stockholm (Sweden)

    2011-08-15

    The usage of computationally feasible overparametrized and nonregularized system identification signal processing methods is assessed for automated determination of the full reversed-field pinch external plasma response spectrum for the experiment EXTRAP T2R. No assumptions on the geometry of eigenmodes are imposed. The attempted approach consists of high-order autoregressive exogenous estimation followed by Markov block coefficient construction and Hankel matrix singular value decomposition. It is seen that the obtained 'black-box' state-space models indeed can be compared with the commonplace ideal magnetohydrodynamics (MHD) resistive thin-shell model in cylindrical geometry. It is possible to directly map the most unstable autodetected empirical system pole to the corresponding theoretical resistive shell MHD eigenmode.

  17. Predictor-based multivariable closed-loop system identification of the EXTRAP T2R reversed field pinch external plasma response

    Science.gov (United States)

    Olofsson, K. Erik J.; Brunsell, Per R.; Rojas, Cristian R.; Drake, James R.; Hjalmarsson, Håkan

    2011-08-01

    The usage of computationally feasible overparametrized and nonregularized system identification signal processing methods is assessed for automated determination of the full reversed-field pinch external plasma response spectrum for the experiment EXTRAP T2R. No assumptions on the geometry of eigenmodes are imposed. The attempted approach consists of high-order autoregressive exogenous estimation followed by Markov block coefficient construction and Hankel matrix singular value decomposition. It is seen that the obtained 'black-box' state-space models indeed can be compared with the commonplace ideal magnetohydrodynamics (MHD) resistive thin-shell model in cylindrical geometry. It is possible to directly map the most unstable autodetected empirical system pole to the corresponding theoretical resistive shell MHD eigenmode.

  18. Treatment of low-strength wastewater using immobilized biomass in a sequencing batch external loop reactor: influence of the medium superficial velocity on the stability and performance

    Directory of Open Access Journals (Sweden)

    Camargo E.F.M.

    2002-01-01

    Full Text Available An anaerobic sequencing batch bioreactor with external circulation of the liquid phase wherein the biomass was immobilized on a polyurethane foam matrix was analyzed, focussing on the influence of the liquid superficial velocity on the reactor's stability and efficiency. Eight-hour cycles were carried out at 30ºC treating glucose-based synthetic wastewater around 500 mgDQO/L. The performance of the reactor was assessed without circulation and with circulating liquid superficial velocity between 0.034 and 0.188 cm/s. The reactor attained operating stability and a high organic matter removal was achieved when liquid was circulated. A first order model was used to evaluate the influence of the liquid superficial velocity (vS, resulting in an increase in the apparent first order parameter when vS increased from 0.034 to 0.094 cm/s. The parameter value remained unchangeable when 0.188 cm/s was applied, indicating that beyond this value no improvement on liquid mass transfer was observed. Moreover, the necessary time to reach the final removal efficiency decreased when liquid circulation was applied, indicating that a 3-hour cycle could be enough.

  19. Fouling layer characterization and pore-blocking mechanisms in an ...

    African Journals Online (AJOL)

    Fouling layer characterization and pore-blocking mechanisms in an UF membrane externally coupled to a UASB reactor. ... Regarding pore-blocking mechanisms, standard blocking was the predominant mechanism at the beginning of filtration, coexisting at the end of it with cake filtration. In the first filtration cycle (1 h), after ...

  20. Immobilized glucose oxidase--catalase and their deactivation in a differential-bed loop reactor.

    Science.gov (United States)

    Prenosil, J E

    1979-01-01

    Glucose oxidase containing catalase was immobilized with a copolymer of phenylenediamine and glutaraldehyde on pumice and titania carrier to study the enzymatic oxidation of glucose in a differential-bed loop reactor. The reaction rate was found to be first order with respect to the concentration of limiting oxygen substrate, suggesting a strong external mass-transfer resistance for all the flow rates used. The partial pressure of oxygen was varied from 21.3 up to 202.6 kPa. The use of a differential-bed loop reactor for the determination of the active enzyme concentration in the catalyst with negligible internal pore diffusion resistance is shown. Catalyst deactivation was studied, especially with respect to the presence of catalase. It is believed that the hydrogen peroxide formed in the oxidation reaction deactivates catalase first; if an excess of catalase is present, the deactivation of glucose oxidase remains small. The mathematical model subsequently developed adequately describes the experimental results.

  1. Robust fault detection in open loop vs. closed loop

    DEFF Research Database (Denmark)

    Niemann, Hans Henrik; Stoustrup, J.

    1997-01-01

    The robustness aspects of fault detection and isolation (FDI) for uncertain systems are considered. The FDI problem is considered in a standard problem formulation. The FDI design problem is analyzed both in the case where the control input signal is considered as a known external input signal (o...... (open loop) and when the input signal is generated by a feedback controller...

  2. Regional Externalities

    NARCIS (Netherlands)

    Heijman, W.J.M.

    2007-01-01

    The book offers practical and theoretical insights in regional externalities. Regional externalities are a specific subset of externalities that can be defined as externalities where space plays a dominant role. This class of externalities can be divided into three categories: (1) externalities

  3. The pore space scramble

    Science.gov (United States)

    Gormally, Alexandra; Bentham, Michelle; Vermeylen, Saskia; Markusson, Nils

    2015-04-01

    Climate change and energy security continue to be the context of the transition to a secure, affordable and low carbon energy future, both in the UK and beyond. This is reflected in for example, binding climate policy targets at the EU level, the introduction of renewable energy targets, and has also led to an increasing interest in Carbon Capture and Storage (CCS) technology with its potential to help mitigate against the effects of CO2 emissions from fossil fuel burning. The UK has proposed a three phase strategy to integrate CCS into its energy system in the long term focussing on off-shore subsurface storage (DECC, 2014). The potential of CCS therefore, raises a number of challenging questions and issues surrounding the long-term storage of CO2 captured and injected into underground spaces and, alongside other novel uses of the subsurface, contributes to opening a new field for discussion on the governance of the subsurface. Such 'novel' uses of the subsurface have lead to it becoming an increasingly contested space in terms of its governance, with issues emerging around the role of ownership, liability and property rights of subsurface pore space. For instance, questions over the legal ownership of pore space have arisen with ambiguity over the legal standpoint of the surface owner and those wanting to utilise the pore space for gas storage, and suggestions of whether there are depths at which legal 'ownership' becomes obsolete (Barton, 2014). Here we propose to discuss this 'pore space scramble' and provide examples of the competing trajectories of different stakeholders, particularly in the off-shore context given its priority in the UK. We also propose to highlight the current ambiguity around property law of pore space in the UK with reference to approaches currently taken in different national contexts. Ultimately we delineate contrasting models of governance to illustrate the choices we face and consider the ethics of these models for the common good

  4. Automated computation of one-loop integrals in massless theories

    International Nuclear Information System (INIS)

    Hameren, A. van; Vollinga, J.; Weinzierl, S.

    2005-01-01

    We consider one-loop tensor and scalar integrals, which occur in a massless quantum field theory, and we report on the implementation into a numerical program of an algorithm for the automated computation of these one-loop integrals. The number of external legs of the loop integrals is not restricted. All calculations are done within dimensional regularization. (orig.)

  5. Two-Loop Splitting Amplitudes

    International Nuclear Information System (INIS)

    Bern, Z.

    2004-01-01

    Splitting amplitudes govern the behavior of scattering amplitudes at the momenta of external legs become collinear. In this talk we outline the calculation of two-loop splitting amplitudes via the unitarity sewing method. This method retains the simple factorization properties of light-cone gauge, but avoids the need for prescriptions such as the principal value or Mandelstam-Leibbrandt ones. The encountered loop momentum integrals are then evaluated using integration-by-parts and Lorentz invariance identities. We outline a variety of applications for these splitting amplitudes

  6. Two-loop splitting amplitudes

    International Nuclear Information System (INIS)

    Bern, Z.; Dixon, L.J.; Kosower, D.A.

    2004-01-01

    Splitting amplitudes govern the behavior of scattering amplitudes at the momenta of external legs become collinear. In this talk we outline the calculation of two-loop splitting amplitudes via the unitarity sewing method. This method retains the simple factorization properties of light-cone gauge, but avoids the need for prescriptions such as the principal value or Mandelstam-Leibbrandt ones. The encountered loop momentum integrals are then evaluated using integration-by-parts and Lorentz invariance identities. We outline a variety of applications for these splitting amplitudes

  7. Capillary condensation in porous materials. Hysteresis and interaction mechanism without pore blocking/percolation process.

    Science.gov (United States)

    Grosman, Annie; Ortega, Camille

    2008-04-15

    We have performed measurements of boundary hysteresis loops, reversal curves, and subloops in p+-type porous silicon, a porous material composed of straight non-interconnected pores. These data show that a strong interaction mechanism exists between the pores. The pores of porous silicon are non-independent, whereas they are not interconnected. This hysteretic behavior is very similar to that observed in porous glass, which consists of cavities connected to each other by constrictions. This questions the so-called pore blocking/percolation model developed to explain the behavior of fluid in porous glass. More generally, if we disregard the shape of the boundary hysteresis loops which depends on the porous material (H1 for MCM-41 and SBA-15, H2 for porous glass and p+-type porous silicon), the hysteretic features inside the main loop are qualitatively the same for all these porous systems. This shows that none of these systems are composed of independent pores. A coupling between the pores is always present whether they are interconnected or not and whatever the shape of the main loop is.

  8. Magnetic properties of Fe20 Ni80 antidots: Pore size and array disorder

    International Nuclear Information System (INIS)

    Palma, J.L.; Gallardo, C.; Spinu, L.; Vargas, J.M.; Dorneles, L.S.; Denardin, J.C.; Escrig, J.

    2013-01-01

    Magnetic properties of nanoscale Fe 20 Ni 80 antidot arrays with different hole sizes prepared on top of nanoporous alumina membranes have been studied by means of magnetometry and micromagnetic simulations. The results show a significant increase of the coercivity as well as a reduction of the remanence of the antidot arrays, as compared with their parent continuous film, which depends on the hole size introduced in the Fe 20 Ni 80 thin film. When the external field is applied parallel to the antidots, the reversal of magnetization is achieved by free-core vortex propagation, whereas when the external field is applied perpendicular to the antidots, the reversal occurs through a process other than the coherent rotation (a maze-like pattern). Besides, in-plane hysteresis loops varying the angle show that the degree of disorder in the sample breaks the expected hexagonal symmetry. - Highlights: • Magnetic properties are strongly influenced by the pore diameter of the samples. • Coercive fields for antidots are higher than the values for the continuous film. • Disorder breaks the hexagonal symmetry of the sample. • Each hole acts as a vortex nucleation point. • Antidots have unique properties that allow them to be used in applications

  9. A pore water conductivity sensor

    NARCIS (Netherlands)

    Hilhorst, M.A.

    2001-01-01

    The electrical permittivity and conductivity of the bulk soil are a function of the permittivity and conductivity of the pore water. For soil water contents higher than 0.10 both functions are equal, facilitating in situ conductivity measurements of the pore water. A novel method is described, based

  10. Alternative loop rings

    CERN Document Server

    Goodaire, EG; Polcino Milies, C

    1996-01-01

    For the past ten years, alternative loop rings have intrigued mathematicians from a wide cross-section of modern algebra. As a consequence, the theory of alternative loop rings has grown tremendously. One of the main developments is the complete characterization of loops which have an alternative but not associative, loop ring. Furthermore, there is a very close relationship between the algebraic structures of loop rings and of group rings over 2-groups. Another major topic of research is the study of the unit loop of the integral loop ring. Here the interaction between loop rings and group ri

  11. Laboratory characterization of shale pores

    Science.gov (United States)

    Nur Listiyowati, Lina

    2018-02-01

    To estimate the potential of shale gas reservoir, one needs to understand the characteristics of pore structures. Characterization of shale gas reservoir microstructure is still a challenge due to ultra-fine grained micro-fabric and micro level heterogeneity of these sedimentary rocks. The sample used in the analysis is a small portion of any reservoir. Thus, each measurement technique has a different result. It raises the question which methods are suitable for characterizing pore shale. The goal of this paper is to summarize some of the microstructure analysis tools of shale rock to get near-real results. The two analyzing pore structure methods are indirect measurement (MIP, He, NMR, LTNA) and direct observation (SEM, TEM, Xray CT). Shale rocks have a high heterogeneity; thus, it needs multiscale quantification techniques to understand their pore structures. To describe the complex pore system of shale, several measurement techniques are needed to characterize the surface area and pore size distribution (LTNA, MIP), shapes, size and distribution of pore (FIB-SEM, TEM, Xray CT), and total porosity (He pycnometer, NMR). The choice of techniques and methods should take into account the purpose of the analysis and also the time and budget.

  12. Extended Cognition: Feedback Loops and Coupled Systems

    Directory of Open Access Journals (Sweden)

    Olga Markic

    2017-12-01

    Full Text Available The article explores two waves of active externalism. I first introduce the distinction between passive and active externalism and analyse a proposal of active externalism based on the principle of parity proposed by Clark and Chalmers. There are two main obstacles, causal-constitution fallacy and cognitive bloat, that threaten the extended cognition hypothesis. The second wave of discussions based on the complementarity principle deals with cognitive systems with feedback loops between internal and external elements and is a more radical departure from functionalism and traditional thinking about cognition. I conclude with some remarks on potential ethical considerations of extended cognition.

  13. MD simulation of organics adsorption from aqueous solution in carbon slit-like pores. Foundations of the pore blocking effect

    International Nuclear Information System (INIS)

    Gauden, Piotr A; Terzyk, Artur P; Furmaniak, Sylwester; Zieliński, Wojciech; Włoch, Jerzy; Kowalczyk, Piotr

    2014-01-01

    The results of systematic studies of organics adsorption from aqueous solutions (at the neutral pH level) in a system of slit-like carbon pores having different sizes and oxygen groups located at the pore mouth are reported. Using molecular dynamics simulations (GROMACS package) the properties of adsorbent–adsorbate (benzene, phenol or paracetamol) as well as adsorbent–water systems are discussed. After the introduction of surface oxygen functionalities, adsorption of organic compounds decreases (in accordance with experimental data) and this is caused by the accumulation of water molecules at pore entrances. The pore blocking effect decreases with the diameter of slits and practically vanishes for widths larger than approx. 0.68 nm. We observed the increase in phenol adsorption with the rise in temperature. Moreover, adsorbed molecules occupy the external surface of the slit pores (the entrances) in the case of oxidized adsorbents. Among the studied molecules benzene, phenol and paracetamol prefer an almost flat orientation and with the rise in the pore width the number of molecules oriented in parallel decreases. The decrease or increase in temperature (with respect to 298 K) leads to insignificant changes of angular orientation of adsorbed molecules. (paper)

  14. Loop Transfer Matrix and Loop Quantum Mechanics

    International Nuclear Information System (INIS)

    Savvidy, George K.

    2000-01-01

    The gonihedric model of random surfaces on a 3d Euclidean lattice has equivalent representation in terms of transfer matrix K(Q i ,Q f ), which describes the propagation of loops Q. We extend the previous construction of the loop transfer matrix to the case of nonzero self-intersection coupling constant κ. We introduce the loop generalization of Fourier transformation which allows to diagonalize transfer matrices, that depend on symmetric difference of loops only and express all eigenvalues of 3d loop transfer matrix through the correlation functions of the corresponding 2d statistical system. The loop Fourier transformation allows to carry out the analogy with quantum mechanics of point particles, to introduce conjugate loop momentum P and to define loop quantum mechanics. We also consider transfer matrix on 4d lattice which describes propagation of memebranes. This transfer matrix can also be diagonalized by using the generalized Fourier transformation, and all its eigenvalues are equal to the correlation functions of the corresponding 3d statistical system. In particular the free energy of the 4d membrane system is equal to the free energy of 3d gonihedric system of loops and is equal to the free energy of 2d Ising model. (author)

  15. Pore size matters for potassium channel conductance

    Science.gov (United States)

    Moldenhauer, Hans; Pincuntureo, Matías

    2016-01-01

    Ion channels are membrane proteins that mediate efficient ion transport across the hydrophobic core of cell membranes, an unlikely process in their absence. K+ channels discriminate K+ over cations with similar radii with extraordinary selectivity and display a wide diversity of ion transport rates, covering differences of two orders of magnitude in unitary conductance. The pore domains of large- and small-conductance K+ channels share a general architectural design comprising a conserved narrow selectivity filter, which forms intimate interactions with permeant ions, flanked by two wider vestibules toward the internal and external openings. In large-conductance K+ channels, the inner vestibule is wide, whereas in small-conductance channels it is narrow. Here we raise the idea that the physical dimensions of the hydrophobic internal vestibule limit ion transport in K+ channels, accounting for their diversity in unitary conductance. PMID:27619418

  16. Can ash clog soil pores?

    Science.gov (United States)

    Stoof, Cathelijne; Stoof, Cathelijne; Gevaert, Anouk; Gevaert, Anouk; Baver, Christine; Baver, Christine; Hassanpour, Bahareh; Hassanpour, Bahareh; Morales, Veronica; Morales, Veronica; Zhang, Wei; Zhang, Wei; Martin, Deborah; Martin, Deborah; Steenhuis, Tammo; Steenhuis, Tammo

    2015-04-01

    Wildfire can greatly increase a landscape's vulnerability to flooding and erosion events, and ash is thought to play a large role in controlling runoff and erosion processes after wildfire. Although ash can store rainfall and thereby reduce runoff and erosion for a limited period after wildfires, it has also been hypothesized to clog soil pores and reduce infiltration. Several researchers have attributed the commonly observed increase in runoff and erosion after fire to the potential pore-clogging effect of ash. Evidence is however incomplete, as to date, research has solely focused on identifying the presence of ash in the soil, with the actual flow processes associated with the infiltration and pore-clogging of ash remaining a major unknown. In several laboratory experiments, we tested the hypothesis that ash causes pore clogging to the point that infiltration is hampered and ponding occurs. We first visualized and quantified pore-scale infiltration of water and ash in sand of a range of textures and at various infiltration rates, using a digital bright field microscope capturing both photo and video. While these visualization experiments confirm field and lab observation of ash washing into soil pores, we did not observe any clogging of pores, and have not been able to create conditions for which this does occur. Additional electrochemical analysis and measurement of saturated hydraulic conductivity indicate that pore clogging by ash is not plausible. Electrochemical analysis showed that ash and sand are both negatively charged, showing that attachment of ash to sand and any resulting clogging is unlikely. Ash also had quite high saturated conductivity, and systems where ash was mixed in or lying on top of sand had similarly high hydraulic conductivity. Based on these various experiments, we cannot confirm the hypothesis that pore clogging by ash contributes to the frequently observed increase in post-fire runoff, at least for the medium to coarse sands

  17. Effect of Pore Geometry on Gas Adsorption: Grand Canonical Monte Carlo Simulation Studies

    International Nuclear Information System (INIS)

    Lee, Eon Ji; Chang, Rak Woo; Han, Ji Hyung; Chung, Taek Dong

    2012-01-01

    In this study, we investigated the pure geometrical effect of porous materials in gas adsorption using the grand canonical Monte Carlo simulations of primitive gas-pore models with various pore geometries such as planar, cylindrical, and random pore geometries. Although the model does not possess atomistic level details of porous materials, our simulation results provided many insightful information in the effect of pore geometry on the adsorption behavior of gas molecules. First, the surface curvature of porous materials plays a significant role in the amount of adsorbed gas molecules: the concave surface such as in cylindrical pores induces more attraction between gas molecules and pore, which results in the enhanced gas adsorption. On the contrary, the convex surface of random pores gives the opposite effect. Second, this geometrical effect shows a nonmonotonic dependence on the gas-pore interaction strength and length. Third, as the external gas pressure is increased, the change in the gas adsorption due to pore geometry is reduced. Finally, the pore geometry also affects the collision dynamics of gas molecules. Since our model is based on primitive description of fluid molecules, our conclusion can be applied to any fluidic systems including reactant-electrode systems

  18. The Brownian loop soup

    OpenAIRE

    Lawler, Gregory F.; Werner, Wendelin

    2003-01-01

    We define a natural conformally invariant measure on unrooted Brownian loops in the plane and study some of its properties. We relate this measure to a measure on loops rooted at a boundary point of a domain and show how this relation gives a way to ``chronologically add Brownian loops'' to simple curves in the plane.

  19. CHY loop integrands from holomorphic forms

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, Humberto [Facultad de Ciencias Basicas, Universidad Santiago de Cali,Calle 5 62-00 Barrio Pampalinda, Cali, Valle (Colombia); Perimeter Institute for Theoretical Physics,31 Caroline Street N, Waterloo, ON N2L 2Y5 (Canada); Mizera, Sebastian; Zhang, Guojun [Perimeter Institute for Theoretical Physics,31 Caroline Street N, Waterloo, ON N2L 2Y5 (Canada); Department of Physics & Astronomy, University of Waterloo,Waterloo, ON N2L 3G1 (Canada)

    2017-03-16

    Recently, the Cachazo-He-Yuan (CHY) approach for calculating scattering amplitudes has been extended beyond tree level. In this paper, we introduce a way of constructing CHY integrands for Φ{sup 3} theory up to two loops from holomorphic forms on Riemann surfaces. We give simple rules for translating Feynman diagrams into the corresponding CHY integrands. As a complementary result, we extend the L-algorithm, originally introduced in https://arxiv.org/abs/1604.05373, to two loops. Using this approach, we are able to analytically verify our prescription for the CHY integrands up to seven external particles at two loops. In addition, it gives a natural way of extending to higher-loop orders.

  20. Antera 3D capabilities for pore measurements.

    Science.gov (United States)

    Messaraa, C; Metois, A; Walsh, M; Flynn, J; Doyle, L; Robertson, N; Mansfield, A; O'Connor, C; Mavon, A

    2018-04-29

    The cause of enlarged pores remains obscure but still remains of concern for women. To complement subjective methods, bioengineered methods are needed for quantification of pores visibility following treatments. The study objective was to demonstrate the suitability of pore measurements from the Antera 3D. Pore measurements were collected on 22 female volunteers aged 18-65 years with the Antera 3D, the DermaTOP and image analysis on photographs. Additionally, 4 raters graded pore size on photographs on a scale 0-5. Repeatability of Antera 3D parameters was ascertained and the benefit of a pore minimizer product on the cheek was assessed on a sub panel of seven female volunteers. Pore parameters using the Antera were shown to depict pore severity similar to raters on photographs, except for Max Depth. Mean pore volume, mean pore area and count were moderately correlated with DermaTOP parameters (up to r = .50). No relationship was seen between the Antera 3D and pore visibility analysis on photographs. The most repeatable parameters were found to be mean pore volume, mean pore area and max depth, especially for the small and medium filters. The benefits of a pore minimizer product were the most striking for mean pore volume and mean pore area when using the small filter for analysis, rather than the medium/large ones. Pore measurements with the Antera 3D represent a reliable tool for efficacy and field studies, with an emphasis of the small filter for analysis for the mean pore volume/mean pore area parameters. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  1. Influence of the Location of Attractive Polymer-Pore Interactions on Translocation Dynamics.

    Science.gov (United States)

    Ghosh, Bappa; Chaudhury, Srabanti

    2018-01-11

    We probe the influence of polymer-pore interactions on the translocation dynamics using Langevin dynamics simulations. We investigate the effect of the strength and location of the polymer-pore interaction using nanopores that are partially charged either at the entry or the exit or on both sides of the pore. We study the change in the translocation time as a function of the strength of the polymer-pore interaction for a given chain length and under the effect of an externally applied field. Under a moderate driving force and a chain length longer than the length of the pore, the translocation time shows a nonmonotonic increase with an increase in the attractive interaction. Also, an interaction on the cis side of the pore can increase the translocation probability. In the presence of an external field and a strong attractive force, the translocation time for shorter chains is independent of the polymer-pore interaction at the entry side of the pore, whereas an interaction on the trans side dominates the translocation process. Our simulation results are rationalized by a qualitative analysis of the free energy landscape for polymer translocation.

  2. Magnetic properties of Fe{sub 20} Ni{sub 80} antidots: Pore size and array disorder

    Energy Technology Data Exchange (ETDEWEB)

    Palma, J.L., E-mail: juan.palma.s@usach.cl [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Gallardo, C. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Spinu, L.; Vargas, J.M. [Advanced Material Research Institute (AMRI) and Department of Physics, University of New Orleans, New Orleans, LA 70148 (United States); Dorneles, L.S. [Departamento de Fisica, Universidade Federal de Santa Maria UFSM, Av. Roraima 1000, Camobi, Santa Maria, RS 97105-900 (Brazil); Denardin, J.C.; Escrig, J. [Departamento de Física, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile)

    2013-10-15

    Magnetic properties of nanoscale Fe{sub 20}Ni{sub 80} antidot arrays with different hole sizes prepared on top of nanoporous alumina membranes have been studied by means of magnetometry and micromagnetic simulations. The results show a significant increase of the coercivity as well as a reduction of the remanence of the antidot arrays, as compared with their parent continuous film, which depends on the hole size introduced in the Fe{sub 20}Ni{sub 80} thin film. When the external field is applied parallel to the antidots, the reversal of magnetization is achieved by free-core vortex propagation, whereas when the external field is applied perpendicular to the antidots, the reversal occurs through a process other than the coherent rotation (a maze-like pattern). Besides, in-plane hysteresis loops varying the angle show that the degree of disorder in the sample breaks the expected hexagonal symmetry. - Highlights: • Magnetic properties are strongly influenced by the pore diameter of the samples. • Coercive fields for antidots are higher than the values for the continuous film. • Disorder breaks the hexagonal symmetry of the sample. • Each hole acts as a vortex nucleation point. • Antidots have unique properties that allow them to be used in applications.

  3. Numerical implementation of the loop-tree duality method

    Energy Technology Data Exchange (ETDEWEB)

    Buchta, Sebastian; Rodrigo, German [Universitat de Valencia-Consejo Superior de Investigaciones Cientificas, Parc Cientific, Instituto de Fisica Corpuscular, Valencia (Spain); Chachamis, Grigorios [Universidad Autonoma de Madrid, Instituto de Fisica Teorica UAM/CSIC, Madrid (Spain); Draggiotis, Petros [Institute of Nuclear and Particle Physics, NCSR ' ' Demokritos' ' , Agia Paraskevi (Greece)

    2017-05-15

    We present a first numerical implementation of the loop-tree duality (LTD) method for the direct numerical computation of multi-leg one-loop Feynman integrals. We discuss in detail the singular structure of the dual integrands and define a suitable contour deformation in the loop three-momentum space to carry out the numerical integration. Then we apply the LTD method to the computation of ultraviolet and infrared finite integrals, and we present explicit results for scalar and tensor integrals with up to eight external legs (octagons). The LTD method features an excellent performance independently of the number of external legs. (orig.)

  4. Point-defect migration into an infinitesimal dislocation loop

    International Nuclear Information System (INIS)

    Woo, C.H.

    1981-11-01

    Point-defect migration into an infinitesimal dislocation loop in an isotropic linear elastic medium is described. Particular care has been taken to include the effects of the saddle-point shape anisotropy of the point defect. Expressions for the reaction radii and the bias are derived, both in the presence and absence of an external applied stress. These are found to depend on intrinsic parameters, such as the loop strength, the loop nature (vacancy or interstitial), the relaxation volume, the saddle-point shape, and extrinsic parameters, such as the magnitude and direction of the external stress, and the temperature. The implications of the results are discussed

  5. Renormalization of loop functions for all loops

    International Nuclear Information System (INIS)

    Brandt, R.A.; Neri, F.; Sato, M.

    1981-01-01

    It is shown that the vacuum expectation values W(C 1 ,xxx, C/sub n/) of products of the traces of the path-ordered phase factors P exp[igcontour-integral/sub C/iA/sub μ/(x)dx/sup μ/] are multiplicatively renormalizable in all orders of perturbation theory. Here A/sub μ/(x) are the vector gauge field matrices in the non-Abelian gauge theory with gauge group U(N) or SU(N), and C/sub i/ are loops (closed paths). When the loops are smooth (i.e., differentiable) and simple (i.e., non-self-intersecting), it has been shown that the generally divergent loop functions W become finite functions W when expressed in terms of the renormalized coupling constant and multiplied by the factors e/sup -K/L(C/sub i/), where K is linearly divergent and L(C/sub i/) is the length of C/sub i/. It is proved here that the loop functions remain multiplicatively renormalizable even if the curves have any finite number of cusps (points of nondifferentiability) or cross points (points of self-intersection). If C/sub γ/ is a loop which is smooth and simple except for a single cusp of angle γ, then W/sub R/(C/sub γ/) = Z(γ)W(C/sub γ/) is finite for a suitable renormalization factor Z(γ) which depends on γ but on no other characteristic of C/sub γ/. This statement is made precise by introducing a regularization, or via a loop-integrand subtraction scheme specified by a normalization condition W/sub R/(C-bar/sub γ/) = 1 for an arbitrary but fixed loop C-bar/sub γ/. Next, if C/sub β/ is a loop which is smooth and simple except for a cross point of angles β, then W(C/sub β/) must be renormalized together with the loop functions of associated sets S/sup i//sub β/ = ]C/sup i/ 1 ,xxx, C/sup i//sub p/i] (i = 2,xxx,I) of loops C/sup i//sub q/ which coincide with certain parts of C/sub β/equivalentC 1 1 . Then W/sub R/(S/sup i//sub β/) = Z/sup i/j(β)W(S/sup j//sub β/) is finite for a suitable matrix Z/sup i/j

  6. Capillary-Condenser-Pumped Heat-Transfer Loop

    Science.gov (United States)

    Silverstein, Calvin C.

    1989-01-01

    Heat being transferred supplies operating power. Capillary-condenser-pumped heat-transfer loop similar to heat pipe and to capillary-evaporator-pumped heat-transfer loop in that heat-transfer fluid pumped by evaporation and condensation of fluid at heat source and sink, respectively. Capillary condenser pump combined with capillary evaporator pump to form heat exchanger circulating heat-transfer fluids in both loops. Transport of heat more nearly isothermal. Thermal stress in loop reduced, and less external surface area needed in condenser section for rejection of heat to heat sink.

  7. Coating of silicon pore optics

    DEFF Research Database (Denmark)

    Cooper-Jensen, Carsten P.; Ackermann, M.; Christensen, Finn Erland

    2009-01-01

    For the International X-ray observatory (IXO), a mirror module with an effective area of 3 m2 at 1.25 keV and at least 0.65 m2 at 6 keV has to be realized. To achieve this goal, coated silicon pore optics has been developed over the last years. One of the challenges is to coat the Si plates...

  8. Perception as a closed-loop convergence process.

    Science.gov (United States)

    Ahissar, Ehud; Assa, Eldad

    2016-05-09

    Perception of external objects involves sensory acquisition via the relevant sensory organs. A widely-accepted assumption is that the sensory organ is the first station in a serial chain of processing circuits leading to an internal circuit in which a percept emerges. This open-loop scheme, in which the interaction between the sensory organ and the environment is not affected by its concurrent downstream neuronal processing, is strongly challenged by behavioral and anatomical data. We present here a hypothesis in which the perception of external objects is a closed-loop dynamical process encompassing loops that integrate the organism and its environment and converging towards organism-environment steady-states. We discuss the consistency of closed-loop perception (CLP) with empirical data and show that it can be synthesized in a robotic setup. Testable predictions are proposed for empirical distinction between open and closed loop schemes of perception.

  9. Pore volume is most highly correlated with the visual assessment of skin pores.

    Science.gov (United States)

    Kim, S J; Shin, M K; Back, J H; Koh, J S

    2014-11-01

    Many studies have been focused on evaluating assessment techniques for facial pores amid growing attention on skin care. Ubiquitous techniques used to assess the size of facial pores include visual assessment, cross-section images of the skin surface, and profilometric analysis of silicone replica of the facial skin. In addition, there are indirect assessment methods, including observation of pores based on confocal laser scanning microscopy and the analysis of sebum secretion and skin elasticity. The aim of this study was to identify parameters useful in estimating pore of surface in normal skin. The severity of pores on the cheek area by frontal optical images was divided on a 0-6 scale with '0' being faint and small pore and '6' being obvious and large pore. After the photos of the frontal cheek of 32 women aged between 35 and 49 were taken, the size of their pores was measured on a 0-6 scale; and the correlation between visual grading of pore and various evaluations (pore volume by 3-D image, pore area and number by Optical Image Analyzer) contributing to pore severity investigated using direct, objective, and noninvasive evaluations. The visual score revealed that the size of pores was graded on a 1-6 scale. Visual grading of pore was highly correlated with pore volume measured from 3-D images and pore area measured from 2-D optical images in the order (P pore was also slightly correlated with the number of pores in size of over 0.04 mm(2) (P pore score and pore volume can be explained by 3-D structural characteristics of pores. It is concluded that pore volume and area serve as useful parameters in estimating pore of skin surface. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  10. Protein crystal nucleation in pores.

    Science.gov (United States)

    Nanev, Christo N; Saridakis, Emmanuel; Chayen, Naomi E

    2017-01-16

    The most powerful method for protein structure determination is X-ray crystallography which relies on the availability of high quality crystals. Obtaining protein crystals is a major bottleneck, and inducing their nucleation is of crucial importance in this field. An effective method to form crystals is to introduce nucleation-inducing heterologous materials into the crystallization solution. Porous materials are exceptionally effective at inducing nucleation. It is shown here that a combined diffusion-adsorption effect can increase protein concentration inside pores, which enables crystal nucleation even under conditions where heterogeneous nucleation on flat surfaces is absent. Provided the pore is sufficiently narrow, protein molecules approach its walls and adsorb more frequently than they can escape. The decrease in the nucleation energy barrier is calculated, exhibiting its quantitative dependence on the confinement space and the energy of interaction with the pore walls. These results provide a detailed explanation of the effectiveness of porous materials for nucleation of protein crystals, and will be useful for optimal design of such materials.

  11. Constant external fields in gauge theory and the spin 0, 1/2, 1 path integrals

    International Nuclear Information System (INIS)

    Reuter, M.; Schmidt, M.G.

    1996-10-01

    We investigate the usefulness of the ''string-inspired technique'' for gauge theory calculations in a constant external field background. Our approach is based on Strassler's worldline path integral approach to the Bern-Kosower formalism, and on the construction of worldline (super-) Green's functions incorporating external fields as well as internal propagators. The worldline path integral representation of the gluon loop is reexamined in detail. We calculate the two-loop effective actions induced for a constant external field by a scalar and spinor loop, and the corresponding one-loop effective action in the gluon loop case. (orig.)

  12. Lattice density functional theory investigation of pore shape effects. I. Adsorption in single nonperiodic pores.

    Science.gov (United States)

    Malanoski, A P; van Swol, Frank

    2002-10-01

    A fully explicit in three dimensions lattice density functional theory is used to investigate adsorption in single nonperiodic pores. The effect of varying pore shape from the slits and cylinders that are normally simulated was our primary interest. A secondary concern was the results for pores with very large diameters. The shapes investigated were square pores with or without surface roughness, cylinders, right triangle pores, and trapezoidal pores. It was found that pores with very similar shape factors gave similar results but that the introduction of acute angled corners or very large side ratio lengths in rectangular pores gave results that were significantly different. Further, a rectangular pore going towards the limit of infinite side ratio does not approach the results of a slit pore. In all of these cases, the importance of features that are present for only a small portion of the pore is demonstrated.

  13. The Arabidopsis Nuclear Pore and Nuclear Envelope

    OpenAIRE

    Meier, Iris; Brkljacic, Jelena

    2010-01-01

    The nuclear envelope is a double membrane structure that separates the eukaryotic cytoplasm from the nucleoplasm. The nuclear pores embedded in the nuclear envelope are the sole gateways for macromolecular trafficking in and out of the nucleus. The nuclear pore complexes assembled at the nuclear pores are large protein conglomerates composed of multiple units of about 30 different nucleoporins. Proteins and RNAs traffic through the nuclear pore complexes, enabled by the interacting activities...

  14. Rock Physics of Reservoir Rocks with Varying Pore Water Saturation and Pore Water Salinity

    DEFF Research Database (Denmark)

    Katika, Konstantina

    experiments, the rock is subjected to high external stresses that resemble the reservoir stresses; 2) the fluid distribution within the pore space changes during the flow through experiments and wettability alterations may occur; 3) different ions, present in the salt water injected in the core, interact......Advanced waterflooding (injection of water with selective ions in reservoirs) is a method of enhanced oil recovery (EOR) that has attracted the interest of oil and gas companies that exploit the Danish oil and gas reservoirs. This method has been applied successfully in oil reservoirs...... and in the Smart Water project performed in a laboratory scale in order to evaluate the EOR processes in selected core plugs. A major step towards this evaluation is to identify the composition of the injected water that leads to increased oil recovery in reservoirs and to define changes in the petrophysical...

  15. Relationship between pore structure and compressive strength

    Indian Academy of Sciences (India)

    Properties of concrete are strongly dependent on its pore structure features, porosity being an important one among them. This study deals with developing an understanding of the pore structure-compressive strength relationship in concrete. Several concrete mixtures with different pore structures are proportioned and ...

  16. Facial Pores: Definition, Causes, and Treatment Options.

    Science.gov (United States)

    Lee, Sang Ju; Seok, Joon; Jeong, Se Yeong; Park, Kui Young; Li, Kapsok; Seo, Seong Jun

    2016-03-01

    Enlarged skin pores refer to conditions that present with visible topographic changes of skin surfaces. Although not a medical concern, enlarged pores are a cosmetic concern for a large number of individuals. Moreover, clear definition and possible causes of enlarged pores have not been elucidated. To review the possible causes and treatment options for skin pores. This article is based on a review of the medical literature and the authors' clinical experience in investigating and treating skin pores. There are 3 major clinical causes of enlarged facial pores, namely high sebum excretion, decreased elasticity around pores, and increased hair follicle volume. In addition, chronic recurrent acne, sex hormones, and skin care regimen can affect pore size. Given the different possible causes for enlarged pores, therapeutic modalities must be individualized for each patient. Potential factors that contribute to enlarged skin pores include excessive sebum, decreased elasticity around pores, and increased hair follicle volume. Because various factors cause enlarged facial pores, it might be useful to identify the underlying causes to be able to select the appropriate treatment.

  17. Random walk loop soup

    OpenAIRE

    Lawler, Gregory F.; Ferreras, José A. Trujillo

    2004-01-01

    The Brownian loop soup introduced in Lawler and Werner (2004) is a Poissonian realization from a sigma-finite measure on unrooted loops. This measure satisfies both conformal invariance and a restriction property. In this paper, we define a random walk loop soup and show that it converges to the Brownian loop soup. In fact, we give a strong approximation result making use of the strong approximation result of Koml\\'os, Major, and Tusn\\'ady. To make the paper self-contained, we include a proof...

  18. On loop extensions and cohomology of loops

    OpenAIRE

    Benítez, Rolando Jiménez; Meléndez, Quitzeh Morales

    2015-01-01

    In this paper are defined cohomology-like groups that classify loop extensions satisfying a given identity in three variables for association identities, and in two variables for the case of commutativity. It is considered a large amount of identities. This groups generalize those defined in works of Nishigori [2] and of Jhonson and Leedham-Green [4]. It is computed the number of metacyclic extensions for trivial action of the quotient on the kernel in one particular case for left Bol loops a...

  19. Neutron transport in irradiation loops (IRENE loop)

    International Nuclear Information System (INIS)

    Sarsam, Maher.

    1980-09-01

    This thesis is composed of two parts with different aspects. Part one is a technical description of the loop and its main ancillary facilities as well as of the safety and operational regulations. The measurement methods on the model of the ISIS reactor and on the loop in the OSIRIS reactor are described. Part two deals with the possibility of calculating the powers dissipated by each rod of the fuel cluster, using appropriate computer codes, not only in the reflector but also in the core and to suggest a method of calculation [fr

  20. Radial symmetry in a chimeric glutamate receptor pore

    Science.gov (United States)

    Wilding, Timothy J.; Lopez, Melany N.; Huettner, James E.

    2014-02-01

    Ionotropic glutamate receptors comprise two conformationally different A/C and B/D subunit pairs. Closed channels exhibit fourfold radial symmetry in the transmembrane domain (TMD) but transition to twofold dimer-of-dimers symmetry for extracellular ligand binding and N-terminal domains. Here, to evaluate symmetry in open pores we analysed interaction between the Q/R editing site near the pore loop apex and the transmembrane M3 helix of kainate receptor subunit GluK2. Chimeric subunits that combined the GluK2 TMD with extracellular segments from NMDA receptors, which are obligate heteromers, yielded channels made up of A/C and B/D subunit pairs with distinct substitutions along M3 and/or Q/R site editing status, in an otherwise identical homotetrameric TMD. Our results indicate that Q/R site interaction with M3 occurs within individual subunits and is essentially the same for both A/C and B/D subunit conformations, suggesting that fourfold pore symmetry persists in the open state.

  1. Measuring kinetic drivers of pneumolysin pore structure.

    Science.gov (United States)

    Gilbert, Robert J C; Sonnen, Andreas F-P

    2016-05-01

    Most membrane attack complex-perforin/cholesterol-dependent cytolysin (MACPF/CDC) proteins are thought to form pores in target membranes by assembling into pre-pore oligomers before undergoing a pre-pore to pore transition. Assembly during pore formation is into both full rings of subunits and incomplete rings (arcs). The balance between arcs and full rings is determined by a mechanism dependent on protein concentration in which arc pores arise due to kinetic trapping of the pre-pore forms by the depletion of free protein subunits during oligomerization. Here we describe the use of a kinetic assay to study pore formation in red blood cells by the MACPF/CDC pneumolysin from Streptococcus pneumoniae. We show that cell lysis displays two kinds of dependence on protein concentration. At lower concentrations, it is dependent on the pre-pore to pore transition of arc oligomers, which we show to be a cooperative process. At higher concentrations, it is dependent on the amount of pneumolysin bound to the membrane and reflects the affinity of the protein for its receptor, cholesterol. A lag occurs before cell lysis begins; this is dependent on oligomerization of pneumolysin. Kinetic dissection of cell lysis by pneumolysin demonstrates the capacity of MACPF/CDCs to generate pore-forming oligomeric structures of variable size with, most likely, different functional roles in biology.

  2. Water loop for training

    International Nuclear Information System (INIS)

    Moeller, S.V.

    1983-02-01

    The procedures used to operate the water loop of the Institute of Nuclear Enginering (IEN) in Brazil are presented. The aim is to help future operators of the training water loop in the operation technique and in a better comprehension of the phenomena occured during the execution of an experience. (E.G.) [pt

  3. Automated one-loop calculations with GOSAM

    International Nuclear Information System (INIS)

    Cullen, Gavin; Greiner, Nicolas; Heinrich, Gudrun; Reiter, Thomas; Luisoni, Gionata

    2011-11-01

    We present the program package GoSam which is designed for the automated calculation of one-loop amplitudes for multi-particle processes in renormalisable quantum field theories. The amplitudes, which are generated in terms of Feynman diagrams, can be reduced using either D-dimensional integrand-level decomposition or tensor reduction. GoSam can be used to calculate one-loop QCD and/or electroweak corrections to Standard Model processes and offers the flexibility to link model files for theories Beyond the Standard Model. A standard interface to programs calculating real radiation is also implemented. We demonstrate the flexibility of the program by presenting examples of processes with up to six external legs attached to the loop. (orig.)

  4. Automated one-loop calculations with GOSAM

    Energy Technology Data Exchange (ETDEWEB)

    Cullen, Gavin [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Deutsches Elektronen-Synchrotron, Zeuthen [DESY; Germany; Greiner, Nicolas [Illinois Univ., Urbana-Champaign, IL (United States). Dept. of Physics; Max-Planck-Institut fuer Physik, Muenchen (Germany); Heinrich, Gudrun; Reiter, Thomas [Max-Planck-Institut fuer Physik, Muenchen (Germany); Luisoni, Gionata [Durham Univ. (United Kingdom). Inst. for Particle Physics Phenomenology; Mastrolia, Pierpaolo [Max-Planck-Institut fuer Physik, Muenchen (Germany); Padua Univ. (Italy). Dipt. di Fisica; Ossola, Giovanni [New York City Univ., NY (United States). New York City College of Technology; New York City Univ., NY (United States). The Graduate School and University Center; Tramontano, Francesco [European Organization for Nuclear Research (CERN), Geneva (Switzerland)

    2011-11-15

    We present the program package GoSam which is designed for the automated calculation of one-loop amplitudes for multi-particle processes in renormalisable quantum field theories. The amplitudes, which are generated in terms of Feynman diagrams, can be reduced using either D-dimensional integrand-level decomposition or tensor reduction. GoSam can be used to calculate one-loop QCD and/or electroweak corrections to Standard Model processes and offers the flexibility to link model files for theories Beyond the Standard Model. A standard interface to programs calculating real radiation is also implemented. We demonstrate the flexibility of the program by presenting examples of processes with up to six external legs attached to the loop. (orig.)

  5. Nanoscale dislocation shear loops at static equilibrium and finite temperature

    Science.gov (United States)

    Dang, Khanh; Capolungo, Laurent; Spearot, Douglas E.

    2017-12-01

    Atomistic simulations are used to determine the resolved shear stress necessary for equilibrium and the resulting geometry of nanoscale dislocation shear loops in Al. Dislocation loops with different sizes and shapes are created via superposition of elemental triangular dislocation displacement fields in the presence of an externally imposed shear stress. First, a bisection algorithm is developed to determine systematically the resolved shear stress necessary for equilibrium at 0 K. This approach allows for the identification of dislocation core structure and a correlation between dislocation loop size, shape and the computed shear stress for equilibrium. It is found, in agreement with predictions made by Scattergood and Bacon, that the equilibrium shape of a dislocation loop becomes more circular with increasing loop size. Second, the bisection algorithm is extended to study the influence of temperature on the resolved shear stress necessary for stability. An approach is presented to compute the effective lattice friction stress, including temperature dependence, for dislocation loops in Al. The temperature dependence of the effective lattice friction stress can be reliably computed for dislocation loops larger than 16.2 nm. However, for dislocation loops smaller than this threshold, the effective lattice friction stress shows a dislocation loop size dependence caused by significant overlap of the stress fields on the interior of the dislocation loops. Combined, static and finite temperature atomistic simulations provide essential data to parameterize discrete dislocation dynamics simulations.

  6. Large lithium loop experience

    International Nuclear Information System (INIS)

    Kolowith, R.; Owen, T.J.; Berg, J.D.; Atwood, J.M.

    1981-10-01

    An engineering design and operating experience of a large, isothermal, lithium-coolant test loop are presented. This liquid metal coolant loop is called the Experimental Lithium System (ELS) and has operated safely and reliably for over 6500 hours through September 1981. The loop is used for full-scale testing of components for the Fusion Materials Irradiation Test (FMIT) Facility. Main system parameters include coolant temperatures to 430 0 C and flow to 0.038 m 3 /s (600 gal/min). Performance of the main pump, vacuum system, and control system is discussed. Unique test capabilities of the ELS are also discussed

  7. Understanding the microscopic moisture migration in pore space using DEM simulation

    Directory of Open Access Journals (Sweden)

    Yuan Guo

    2015-04-01

    Full Text Available The deformation of soil skeleton and migration of pore fluid are the major factors relevant to the triggering of and damages by liquefaction. The influence of pore fluid migration during earthquake has been demonstrated from recent model experiments and field case studies. Most of the current liquefaction assessment models are based on testing of isotropic liquefiable materials. However the recent New Zealand earthquake shows much severer damages than those predicted by existing models. A fundamental cause has been contributed to the embedded layers of low permeability silts. The existence of these silt layers inhibits water migration under seismic loads, which accelerated liquefaction and caused a much larger settlement than that predicted by existing theories. This study intends to understand the process of moisture migration in the pore space of sand using discrete element method (DEM simulation. Simulations were conducted on consolidated undrained triaxial testing of sand where a cylinder sample of sand was built and subjected to a constant confining pressure and axial loading. The porosity distribution was monitored during the axial loading process. The spatial distribution of porosity change was determined, which had a direct relationship with the distribution of excess pore water pressure. The non-uniform distribution of excess pore water pressure causes moisture migration. From this, the migration of pore water during the loading process can be estimated. The results of DEM simulation show a few important observations: (1 External forces are mainly carried and transmitted by the particle chains of the soil sample; (2 Porosity distribution during loading is not uniform due to non-homogeneous soil fabric (i.e. the initial particle arrangement and existence of particle chains; (3 Excess pore water pressure develops differently at different loading stages. At the early stage of loading, zones with a high initial porosity feature higher

  8. Natively unstructured loops differ from other loops.

    Directory of Open Access Journals (Sweden)

    Avner Schlessinger

    2007-07-01

    Full Text Available Natively unstructured or disordered protein regions may increase the functional complexity of an organism; they are particularly abundant in eukaryotes and often evade structure determination. Many computational methods predict unstructured regions by training on outliers in otherwise well-ordered structures. Here, we introduce an approach that uses a neural network in a very different and novel way. We hypothesize that very long contiguous segments with nonregular secondary structure (NORS regions differ significantly from regular, well-structured loops, and that a method detecting such features could predict natively unstructured regions. Training our new method, NORSnet, on predicted information rather than on experimental data yielded three major advantages: it removed the overlap between testing and training, it systematically covered entire proteomes, and it explicitly focused on one particular aspect of unstructured regions with a simple structural interpretation, namely that they are loops. Our hypothesis was correct: well-structured and unstructured loops differ so substantially that NORSnet succeeded in their distinction. Benchmarks on previously used and new experimental data of unstructured regions revealed that NORSnet performed very well. Although it was not the best single prediction method, NORSnet was sufficiently accurate to flag unstructured regions in proteins that were previously not annotated. In one application, NORSnet revealed previously undetected unstructured regions in putative targets for structural genomics and may thereby contribute to increasing structural coverage of large eukaryotic families. NORSnet found unstructured regions more often in domain boundaries than expected at random. In another application, we estimated that 50%-70% of all worm proteins observed to have more than seven protein-protein interaction partners have unstructured regions. The comparative analysis between NORSnet and DISOPRED2 suggested

  9. Introduction to Loop Heat Pipes

    Science.gov (United States)

    Ku, Jentung

    2015-01-01

    This is the presentation file for the short course Introduction to Loop Heat Pipes, to be conducted at the 2015 Thermal Fluids and Analysis Workshop, August 3-7, 2015, Silver Spring, Maryland. This course will discuss operating principles and performance characteristics of a loop heat pipe. Topics include: 1) pressure profiles in the loop; 2) loop operating temperature; 3) operating temperature control; 4) loop startup; 4) loop shutdown; 5) loop transient behaviors; 6) sizing of loop components and determination of fluid inventory; 7) analytical modeling; 8) examples of flight applications; and 9) recent LHP developments.

  10. Pore surface engineering in covalent organic frameworks.

    Science.gov (United States)

    Nagai, Atsushi; Guo, Zhaoqi; Feng, Xiao; Jin, Shangbin; Chen, Xiong; Ding, Xuesong; Jiang, Donglin

    2011-11-15

    Covalent organic frameworks (COFs) are a class of important porous materials that allow atomically precise integration of building blocks to achieve pre-designable pore size and geometry; however, pore surface engineering in COFs remains challenging. Here we introduce pore surface engineering to COF chemistry, which allows the controlled functionalization of COF pore walls with organic groups. This functionalization is made possible by the use of azide-appended building blocks for the synthesis of COFs with walls to which a designable content of azide units is anchored. The azide units can then undergo a quantitative click reaction with alkynes to produce pore surfaces with desired groups and preferred densities. The diversity of click reactions performed shows that the protocol is compatible with the development of various specific surfaces in COFs. Therefore, this methodology constitutes a step in the pore surface engineering of COFs to realize pre-designed compositions, components and functions.

  11. Effects of fractal pore on coal devolatilization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yongli; He, Rong [Tsinghua Univ., Beijing (China). Dept. of Thermal Engineering; Wang, Xiaoliang; Cao, Liyong [Dongfang Electric Corporation, Chengdu (China). Centre New Energy Inst.

    2013-07-01

    Coal devolatilization is numerically investigated by drop tube furnace and a coal pyrolysis model (Fragmentation and Diffusion Model). The fractal characteristics of coal and char pores are investigated. Gas diffusion and secondary reactions in fractal pores are considered in the numerical simulations of coal devolatilization, and the results show that the fractal dimension is increased firstly and then decreased later with increased coal conversions during devolatilization. The mechanisms of effects of fractal pores on coal devolatilization are analyzed.

  12. Diffusion of Wilson loops

    International Nuclear Information System (INIS)

    Brzoska, A.M.; Lenz, F.; Thies, M.; Negele, J.W.

    2005-01-01

    A phenomenological analysis of the distribution of Wilson loops in SU(2) Yang-Mills theory is presented in which Wilson loop distributions are described as the result of a diffusion process on the group manifold. It is shown that, in the absence of forces, diffusion implies Casimir scaling and, conversely, exact Casimir scaling implies free diffusion. Screening processes occur if diffusion takes place in a potential. The crucial distinction between screening of fundamental and adjoint loops is formulated as a symmetry property related to the center symmetry of the underlying gauge theory. The results are expressed in terms of an effective Wilson loop action and compared with various limits of SU(2) Yang-Mills theory

  13. Blind loop syndrome

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/001146.htm Blind loop syndrome To use the sharing features on ... Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David ...

  14. Mashup the OODA Loop

    National Research Council Canada - National Science Library

    Heier, Jeffrey E

    2008-01-01

    ...) processes via the Observe, Orient, Decide, and Act (OODA) Loop concept. As defined by Wikipedia, a mashup is a Website or application that combines the content from more than one source into an integrated presentation...

  15. Electroosmotic pore transport in human skin.

    Science.gov (United States)

    Uitto, Olivia D; White, Henry S

    2003-04-01

    To determine the pathways and origin of electroosmotic flow in human skin. Iontophoretic transport of acetaminophen in full thickness human cadaver skin was visualized and quantified by scanning electrochemical microscopy. Electroosmotic flow in the shunt pathways of full thickness skin was compared to flow in the pores of excised stratum corneum and a synthetic membrane pore. The penetration of rhodamine 6G into pore structures was investigated by laser scanning confocal microscopy. Electroosmotic transport is observed in shunt pathways in full thickness human skin (e.g., hair follicles and sweat glands), but not in pore openings of freestanding stratum corneum. Absolute values of the diffusive and iontophoretic pore fluxes of acetaminophen in full thickness human skin are also reported. Rhodamine 6G is observed to penetrate to significant depths (approximately 200 microm) along pore pathways. Iontophoresis in human cadaver skin induces localized electroosmotic flow along pore shunt paths. Electroosmotic forces arise from the passage of current through negatively charged mesoor nanoscale pores (e.g., gap functions) within cellular regions that define the pore structure beneath the stratum corneum.

  16. Reactor loops at Chalk River

    International Nuclear Information System (INIS)

    Sochaski, R.O.

    1962-07-01

    This report describes broadly the nine in-reactor loops, and their components, located in and around the NRX and NRU reactors at Chalk River. First an introduction and general description is given of the loops and their function, supplemented with a table outlining some loop specifications and nine simplified flow sheets, one for each individual loop. The report then proceeds to classify each loop into two categories, the 'main loop circuit' and the 'auxiliary circuit', and descriptions are given of each circuit's components in turn. These components, in part, are comprised of the main loop pumps, the test section, loop heaters, loop coolers, delayed-neutron monitors, surge tank, Dowtherm coolers, loop piping. Here again photographs, drawings and tables are included to provide a clearer understanding of the descriptive literature and to include, in tables, some specifications of the more important components in each loop. (author)

  17. Dechanneling by dislocation loops

    International Nuclear Information System (INIS)

    Chalant, Gerard.

    1976-09-01

    Ion implantation always induces the creation of dislocation loops. When the damage profile is determined by a backscattering technique, the dechanneling by these loops is implicitely at the origin of these measurements. The dechanneling of alpha particles by dislocation loops produced by the coalescence of quenched-in vacancies in aluminium is studied. The dechanneling and the concentration of loops were determined simultaneously. The dechanneling width around dislocation was found equal to lambda=6A, both for perfect and imperfect loops having a mean diameter d=250A. In the latter case, a dechanneling probability chi=0.34 was determined for the stacking fault, in good agreement with previous determination in gold. A general formula is proposed which takes into account the variation of lambda with the curvature (or the diameter d) of the loops. Finally, by a series of isothermal anneals, the self-diffusion energy ΔH of aluminium was measured. The value obtained ΔH=1.32+-0.10eV is in good agreement with the values obtained by other methods [fr

  18. An alternative explanation for evidence that xenon depletion, pore formation, and grain subdivision begin at different local burnups

    International Nuclear Information System (INIS)

    Rest, J.; Hofman, G.L.

    2000-01-01

    In order to interpret the recent observation that xenon depletion, pore formation, and grain subdivision occur successively at increasing local burnups, a rate-theory-based model is used to investigate the nucleation and growth of cavities during low-temperature irradiation of UO 2 in the presence of irradiation-induced interstitial-loop formation and growth. Consolidation of the dislocation structure takes into account the generation of forest dislocations and capture of interstitial dislocation loops. The loops accumulate and ultimately evolve into a low-energy cellular dislocation structure. The cell walls have been previously identified as recrystallization nuclei. The calculations indicate that nanometer-size bubbles are associated with this cellular dislocation structure while the observed micron-size bubbles are presumed to be either preexisting pores deformed by adjacent grains and/or new pores formed in the new recrystallized grain-boundary junctions. Subsequent to recrystallization, gas released from the recrystallized grains feeds the preexisting pores and the recrystallized grains may appear to form a preferential concentration of subdivided grains around the growing pores. This picture is illustrated in a sequence of photomicrographs of irradiated U 3 O 8

  19. Molecular basis of usher pore gating in Escherichia coli pilus biogenesis.

    Science.gov (United States)

    Volkan, Ender; Kalas, Vasilios; Pinkner, Jerome S; Dodson, Karen W; Henderson, Nadine S; Pham, Thieng; Waksman, Gabriel; Delcour, Anne H; Thanassi, David G; Hultgren, Scott J

    2013-12-17

    Extracellular fibers called chaperone-usher pathway pili are critical virulence factors in a wide range of Gram-negative pathogenic bacteria that facilitate binding and invasion into host tissues and mediate biofilm formation. Chaperone-usher pathway ushers, which catalyze pilus assembly, contain five functional domains: a 24-stranded transmembrane β-barrel translocation domain (TD), a β-sandwich plug domain (PLUG), an N-terminal periplasmic domain, and two C-terminal periplasmic domains (CTD1 and 2). Pore gating occurs by a mechanism whereby the PLUG resides stably within the TD pore when the usher is inactive and then upon activation is translocated into the periplasmic space, where it functions in pilus assembly. Using antibiotic sensitivity and electrophysiology experiments, a single salt bridge was shown to function in maintaining the PLUG in the TD channel of the P pilus usher PapC, and a loop between the 12th and 13th beta strands of the TD (β12-13 loop) was found to facilitate pore opening. Mutation of the β12-13 loop resulted in a closed PapC pore, which was unable to efficiently mediate pilus assembly. Deletion of the PapH terminator/anchor resulted in increased OM permeability, suggesting a role for the proper anchoring of pili in retaining OM integrity. Further, we introduced cysteine residues in the PLUG and N-terminal periplasmic domains that resulted in a FimD usher with a greater propensity to exist in an open conformation, resulting in increased OM permeability but no loss in type 1 pilus assembly. These studies provide insights into the molecular basis of usher pore gating and its roles in pilus biogenesis and OM permeability.

  20. An exact method for solving logical loops in reliability analysis

    International Nuclear Information System (INIS)

    Matsuoka, Takeshi

    2009-01-01

    This paper presents an exact method for solving logical loops in reliability analysis. The systems that include logical loops are usually described by simultaneous Boolean equations. First, present a basic rule of solving simultaneous Boolean equations. Next, show the analysis procedures for three-component system with external supports. Third, more detailed discussions are given for the establishment of logical loop relation. Finally, take up two typical structures which include more than one logical loop. Their analysis results and corresponding GO-FLOW charts are given. The proposed analytical method is applicable to loop structures that can be described by simultaneous Boolean equations, and it is very useful in evaluating the reliability of complex engineering systems.

  1. Analysis of severe accidents on fast reactor test loop

    International Nuclear Information System (INIS)

    Cenerini, R.; Verzelletti, G.; Curioni, S.

    1975-01-01

    The Pec reactor is a sodium cooled fast reactor which is being designed for the primary purpose of accomodating closed sodium cooled test loops for the developmental and proof testing of fast reactor fuel assemblies. The test loops are located in the central test region of reactor. The basic function for which the loop is designed is burn-up to failure testing of fuel under advanced performance conditions. It is therefore necessary to design the loop for failure conditions. Basically two types of accidents can occur within the loops: rupture of gas plenum in the fuel pins and coolant starvation. Explosive tests on Pec loop, whose first set is described in this report, are devoted to investigate the effects of an accidental energy release on loop containment. The loop model reproduces in the test section the prototype dimensions in radial scale 1:1. Using a wire explosive charge of 300mm, the height of test section is sufficient for determining the containment capability of the loop that has a nearly constant deformation in a length of. 3-4 time the diameter. The inertial effects of the coolant column are reproduced by two tubes at the extremities of test section, closed with top plugs. Some tests has been performed by wrapping around the test section four layers of steel wire in order to evaluate the influence on the containment of tungsten wire that is foreseen in prototype loop. The influence of the coolant around the loop was evaluated by inserting the model in water. Dummy sub-assemblies was used and explosive substitutes the central rods. Piezoelectric pressure transducers were mounted on the three plugs and radial deformation was measured directly at different height. From experiments performed it resulted the importance of harmonic wires and inertial reaction of external water on loop containment; maximum containable energy is about 50 Cal with E.1 explosive

  2. The Effect of the Pore Entrance on Particle Motion in Slit Pores: Implications for Ultrathin Membranes.

    Science.gov (United States)

    Delavari, Armin; Baltus, Ruth

    2017-08-10

    Membrane rejection models generally neglect the effect of the pore entrance on intrapore particle transport. However, entrance effects are expected to be particularly important with ultrathin membranes, where membrane thickness is typically comparable to pore size. In this work, a 2D model was developed to simulate particle motion for spherical particles moving at small Re and infinite Pe from the reservoir outside the pore into a slit pore. Using a finite element method, particles were tracked as they accelerated across the pore entrance until they reached a steady velocity in the pore. The axial position in the pore where particle motion becomes steady is defined as the particle entrance length (PEL). PELs were found to be comparable to the fluid entrance length, larger than the pore size and larger than the thickness typical of many ultrathin membranes. Results also show that, in the absence of particle diffusion, hydrodynamic particle-membrane interactions at the pore mouth result in particle "funneling" in the pore, yielding cross-pore particle concentration profiles focused at the pore centerline. The implications of these phenomena on rejection from ultrathin membranes are examined.

  3. Automatic facial pore analysis system using multi-scale pore detection.

    Science.gov (United States)

    Sun, J Y; Kim, S W; Lee, S H; Choi, J E; Ko, S J

    2017-08-01

    As facial pore widening and its treatments have become common concerns in the beauty care field, the necessity for an objective pore-analyzing system has been increased. Conventional apparatuses lack in usability requiring strong light sources and a cumbersome photographing process, and they often yield unsatisfactory analysis results. This study was conducted to develop an image processing technique for automatic facial pore analysis. The proposed method detects facial pores using multi-scale detection and optimal scale selection scheme and then extracts pore-related features such as total area, average size, depth, and the number of pores. Facial photographs of 50 subjects were graded by two expert dermatologists, and correlation analyses between the features and clinical grading were conducted. We also compared our analysis result with those of conventional pore-analyzing devices. The number of large pores and the average pore size were highly correlated with the severity of pore enlargement. In comparison with the conventional devices, the proposed analysis system achieved better performance showing stronger correlation with the clinical grading. The proposed system is highly accurate and reliable for measuring the severity of skin pore enlargement. It can be suitably used for objective assessment of the pore tightening treatments. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Radiative magnetohydrodynamic simulations of solar pores

    NARCIS (Netherlands)

    Cameron, R.; Schuessler, M.; Vögler, A.; Zakharov, V.

    2007-01-01

    Context. Solar pores represent a class of magnetic structures intermediate between small-scale magnetic flux concentrations in intergranular lanes and fully developed sunspots with penumbrae. Aims. We study the structure, energetics, and internal dynamics of pore-like magnetic structures by means of

  5. Cavitation and pore blocking in nanoporous glasses.

    Science.gov (United States)

    Reichenbach, C; Kalies, G; Enke, D; Klank, D

    2011-09-06

    In gas adsorption studies, porous glasses are frequently referred to as model materials for highly disordered mesopore systems. Numerous works suggest that an accurate interpretation of physisorption isotherms requires a complete understanding of network effects upon adsorption and desorption, respectively. The present article deals with nitrogen and argon adsorption at different temperatures (77 and 87 K) performed on a series of novel nanoporous glasses (NPG) with different mean pore widths. NPG samples contain smaller mesopores and significantly higher microporosity than porous Vycor glass or controlled pore glass. Since the mean pore width of NPG can be tuned sensitively, the evolution of adsorption characteristics with respect to a broadening pore network can be investigated starting from the narrowest nanopore width. With an increasing mean pore width, a H2-type hysteresis develops gradually which finally transforms into a H1-type. In this connection, a transition from a cavitation-induced desorption toward desorption controlled by pore blocking can be observed. Furthermore, we find concrete hints for a pore size dependence of the relative pressure of cavitation in highly disordered pore systems. By comparing nitrogen and argon adsorption, a comprehensive insight into adsorption mechanisms in novel disordered materials is provided. © 2011 American Chemical Society

  6. FINGERPRINT MATCHING BASED ON PORE CENTROIDS

    Directory of Open Access Journals (Sweden)

    S. Malathi

    2011-05-01

    Full Text Available In recent years there has been exponential growth in the use of bio- metrics for user authentication applications. Automated Fingerprint Identification systems have become popular tool in many security and law enforcement applications. Most of these systems rely on minutiae (ridge ending and bifurcation features. With the advancement in sensor technology, high resolution fingerprint images (1000 dpi pro- vide micro level of features (pores that have proven to be useful fea- tures for identification. In this paper, we propose a new strategy for fingerprint matching based on pores by reliably extracting the pore features The extraction of pores is done by Marker Controlled Wa- tershed segmentation method and the centroids of each pore are con- sidered as feature vectors for matching of two fingerprint images. Experimental results shows that the proposed method has better per- formance with lower false rates and higher accuracy.

  7. Concepts of self-acting circulation loops for downward heat transfer (reverse thermosiphons)

    International Nuclear Information System (INIS)

    Dobriansky, Y.

    2011-01-01

    This paper reviews the scientific and technical knowledge related to general self-acting flow loops (thermosiphons and heat pipes) that transmit heat upwards and self-acting reverse flow loops that transmit heat downwards. This paper classifies the heat and mass transfer processes that take place in general flow loops and analyses the nomenclature applied in the literature. It also presents the principles of operation of sixteen reverse flow loops; four of the loops are powered by an external source of energy, while the remaining loops are self-acting. Of the self-acting loops, vapor was used for heat transfer in seven of them and liquid was used in the remaining ones. Based on the available research results, a list of the advantages and disadvantages of both types of loops is presented.

  8. Conformal boundary loop models

    International Nuclear Information System (INIS)

    Jacobsen, Jesper Lykke; Saleur, Hubert

    2008-01-01

    We study a model of densely packed self-avoiding loops on the annulus, related to the Temperley-Lieb algebra with an extra idempotent boundary generator. Four different weights are given to the loops, depending on their homotopy class and whether they touch the outer rim of the annulus. When the weight of a contractible bulk loop x≡q+q -1 element of (-2,2], this model is conformally invariant for any real weight of the remaining three parameters. We classify the conformal boundary conditions and give exact expressions for the corresponding boundary scaling dimensions. The amplitudes with which the sectors with any prescribed number and types of non-contractible loops appear in the full partition function Z are computed rigorously. Based on this, we write a number of identities involving Z which hold true for any finite size. When the weight of a contractible boundary loop y takes certain discrete values, y r ≡([r+1] q )/([r] q ) with r integer, other identities involving the standard characters K r,s of the Virasoro algebra are established. The connection with Dirichlet and Neumann boundary conditions in the O(n) model is discussed in detail, and new scaling dimensions are derived. When q is a root of unity and y=y r , exact connections with the A m type RSOS model are made. These involve precise relations between the spectra of the loop and RSOS model transfer matrices, valid in finite size. Finally, the results where y=y r are related to the theory of Temperley-Lieb cabling

  9. Excess pore water pressure induced in the foundation of a tailings dyke at Muskeg River Mine, Fort McMurray

    Energy Technology Data Exchange (ETDEWEB)

    Eshraghian, A.; Martens, S. [Klohn Crippen Berger Ltd., Calgary, AB (Canada)

    2010-07-01

    This paper discussed the effect of staged construction on the generation and dissipation of excess pore water pressure within the foundation clayey units of the External Tailings Facility dyke. Data were compiled from piezometers installed within the dyke foundation and used to estimate the dissipation parameters for the clayey units for a selected area of the foundation. Spatial and temporal variations in the pore water pressure generation parameters were explained. Understanding the process by which excess pore water pressure is generated and dissipates is critical to optimizing dyke design and performance. Piezometric data was shown to be useful in improving estimates of the construction-induced pore water pressure and dissipation rates within the clay layers in the foundation during dyke construction. In staged construction, a controlled rate of load application is used to increase foundation stability. Excess pore water pressure dissipates after each application, so the most critical stability condition happens after each load. Slow loading allows dissipation, whereas previous load pressure remains during fast loading. The dyke design must account for the rate of loading and the rate of pore pressure dissipation. Controlling the rate of loading and the rate of stress-induced excess pore water pressure generation is important to dyke stability during construction. Effective stress-strength parameters for the foundation require predictions of the pore water pressure induced during staged construction. It was found that both direct and indirect loading generates excess pore water pressure in the foundation clays. 2 refs., 2 tabs., 11 figs.

  10. Enlarged facial pores: an update on treatments.

    Science.gov (United States)

    Dong, Joanna; Lanoue, Julien; Goldenberg, Gary

    2016-07-01

    Enlarged facial pores remain a common dermatologic and cosmetic concern from acne and rosacea, among other conditions, that is difficult to treat due to the multifactorial nature of their pathogenesis and negative impact on patients' quality of life. Enlarged facial pores are primarily treated through addressing associative factors, such as increased sebum production and cutaneous aging. We review the current treatment modalities for enlarged or dense facial pores, including topical retinoids, chemical peels, oral antiandrogens, and lasers and devices, with a focus on newer therapies.

  11. Control of pore size in epoxy systems.

    Energy Technology Data Exchange (ETDEWEB)

    Sawyer, Patricia Sue; Lenhart, Joseph Ludlow (North Dakota State University, Fargo, ND); Lee, Elizabeth (North Dakota State University, Fargo, ND); Kallam, Alekhya (North Dakota State University, Fargo, ND); Majumdar, Partha (North Dakota State University, Fargo, ND); Dirk, Shawn M.; Gubbins, Nathan; Chisholm, Bret J. (North Dakota State University, Fargo, ND); Celina, Mathias C.; Bahr, James (North Dakota State University, Fargo, ND); Klein, Robert J.

    2009-01-01

    Both conventional and combinatorial approaches were used to study the pore formation process in epoxy based polymer systems. Sandia National Laboratories conducted the initial work and collaborated with North Dakota State University (NDSU) using a combinatorial research approach to produce a library of novel monomers and crosslinkers capable of forming porous polymers. The library was screened to determine the physical factors that control porosity, such as porogen loading, polymer-porogen interactions, and polymer crosslink density. We have identified the physical and chemical factors that control the average porosity, pore size, and pore size distribution within epoxy based systems.

  12. Loop quantum gravity

    International Nuclear Information System (INIS)

    Pullin, J.

    2015-01-01

    Loop quantum gravity is one of the approaches that are being studied to apply the rules of quantum mechanics to the gravitational field described by the theory of General Relativity . We present an introductory summary of the main ideas and recent results. (Author)

  13. Blind Loop Syndrome

    Science.gov (United States)

    ... or scleroderma involving the small intestine History of radiation therapy to the abdomen Diabetes Diverticulosis of the small intestine Complications A blind loop can cause escalating problems, including: Poor absorption of fats. Bacteria in your small intestine break down the bile ...

  14. Improving Loop Dependence Analysis

    DEFF Research Database (Denmark)

    Jensen, Nicklas Bo; Karlsson, Sven

    2017-01-01

    Programmers can no longer depend on new processors to have significantly improved single-thread performance. Instead, gains have to come from other sources such as the compiler and its optimization passes. Advanced passes make use of information on the dependencies related to loops. We improve th...

  15. Cytokine loops driving senescence

    Czech Academy of Sciences Publication Activity Database

    Bartek, Jiří; Hodný, Zdeněk; Lukáš, Jan

    2008-01-01

    Roč. 10, č. 8 (2008), s. 887-889 ISSN 1465-7392 Institutional research plan: CEZ:AV0Z50520514 Keywords : cellular senescence * cytokines * autocrine feedback loop Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 17.774, year: 2008

  16. Loop Quantum Gravity

    Directory of Open Access Journals (Sweden)

    Rovelli Carlo

    1998-01-01

    Full Text Available The problem of finding the quantum theory of the gravitational field, and thus understanding what is quantum spacetime, is still open. One of the most active of the current approaches is loop quantum gravity. Loop quantum gravity is a mathematically well-defined, non-perturbative and background independent quantization of general relativity, with its conventional matter couplings. Research in loop quantum gravity today forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained are: (i The computation of the physical spectra of geometrical quantities such as area and volume, which yields quantitative predictions on Planck-scale physics. (ii A derivation of the Bekenstein-Hawking black hole entropy formula. (iii An intriguing physical picture of the microstructure of quantum physical space, characterized by a polymer-like Planck scale discreteness. This discreteness emerges naturally from the quantum theory and provides a mathematically well-defined realization of Wheeler's intuition of a spacetime ``foam''. Long standing open problems within the approach (lack of a scalar product, over-completeness of the loop basis, implementation of reality conditions have been fully solved. The weak part of the approach is the treatment of the dynamics: at present there exist several proposals, which are intensely debated. Here, I provide a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  17. Functions of phenylalanine residues within the beta-barrel stem of the anthrax toxin pore.

    Directory of Open Access Journals (Sweden)

    Jie Wang

    2009-07-01

    Full Text Available A key step of anthrax toxin action involves the formation of a protein-translocating pore within the endosomal membrane by the Protective Antigen (PA moiety. Formation of this transmembrane pore by PA involves interaction of the seven 2beta2-2beta3 loops of the heptameric precursor to generate a 14-strand transmembrane beta barrel.We examined the effects on pore formation, protein translocation, and cytotoxicity, of mutating two phenylalanines, F313 and F314, that lie at the tip the beta barrel, and a third one, F324, that lies part way up the barrel.Our results show that the function of these phenylalanine residues is to mediate membrane insertion and formation of stable transmembrane channels. Unlike F427, a key luminal residue in the cap of the pore, F313, F314, and F324 do not directly affect protein translocation through the pore. Our findings add to our knowledge of structure-function relationships of a key virulence factor of the anthrax bacillus.

  18. Three- and two-point one-loop integrals in heavy particle effective theories

    International Nuclear Information System (INIS)

    Bouzas, A.O.

    2000-01-01

    We give a complete analytical computation of three- and two-point loop integrals occurring in heavy particle theories, involving a velocity change, for arbitrary real values of the external masses and residual momenta. (orig.)

  19. Valve seat pores sealed with thermosetting monomer

    Science.gov (United States)

    Olmore, A. B.

    1966-01-01

    Hard anodic coating provides a smooth wear resistant value seating surface on a cast aluminum alloy valve body. Vacuum impregnation with a thermosetting monomer, diallyl phthalate, seals the pores on the coating to prevent galvanic corrosion.

  20. Estimation of pore pressure from seismic velocities

    International Nuclear Information System (INIS)

    Perez, Zayra; Ojeda, German Y; Mateus, Darwin

    2009-01-01

    On pore pressure calculations it is common to obtain a profile in a well bore, which is then extrapolated toward offset wells. This practice might generate mistakes on pore pressure measurements, since geological conditions may change from a well bore to another, even into the same basin. Therefore, it is important to use other tools which allow engineers not only to detect and estimate in an indirect way overpressure zones, but also to keep a lateral tracking of possible changes that may affect those values in the different formations. Taking into account this situation, we applied a methodology that estimates formation pressure from 3D seismic velocities by using the Eaton method. First, we estimated formation pore pressure; then, we identified possible overpressure zones. Finally, those results obtained from seismic information were analyzed involving well logs and pore pressure tests, in order to compare real data with prediction based on seismic information from the Colombian foothill.

  1. OBSERVATIONS OF SAUSAGE MODES IN MAGNETIC PORES

    International Nuclear Information System (INIS)

    Morton, R. J.; Erdelyi, R.; Jess, D. B.; Mathioudakis, M.

    2011-01-01

    We present here evidence for the observation of the magnetohydrodynamic (MHD) sausage modes in magnetic pores in the solar photosphere. Further evidence for the omnipresent nature of acoustic global modes is also found. The empirical decomposition method of wave analysis is used to identify the oscillations detected through a 4170 A 'blue continuum' filter observed with the Rapid Oscillations in the Solar Atmosphere (ROSA) instrument. Out of phase, periodic behavior in pore size and intensity is used as an indicator of the presence of magnetoacoustic sausage oscillations. Multiple signatures of the magnetoacoustic sausage mode are found in a number of pores. The periods range from as short as 30 s up to 450 s. A number of the magnetoacoustic sausage mode oscillations found have periods of 3 and 5 minutes, similar to the acoustic global modes of the solar interior. It is proposed that these global oscillations could be the driver of the sausage-type magnetoacoustic MHD wave modes in pores.

  2. Random walk loop soups and conformal loop ensembles

    NARCIS (Netherlands)

    van de Brug, T.; Camia, F.; Lis, M.

    2016-01-01

    The random walk loop soup is a Poissonian ensemble of lattice loops; it has been extensively studied because of its connections to the discrete Gaussian free field, but was originally introduced by Lawler and Trujillo Ferreras as a discrete version of the Brownian loop soup of Lawler and Werner, a

  3. Effects of carbon coating and pore corrugation on capillary condensation of nitrogen in SBA-15 mesoporous silica.

    Science.gov (United States)

    Morishige, Kunimitsu

    2013-09-24

    To examine the origin of an ink-bottle-like structure in SBA-15 formed by carbon coating and the effects of pore corrugation on capillary condensation and evaporation of a vapor in the cylindrical pores, we measured the adsorption isotherms of nitrogen at 77 K on 10 kinds of SBA-15 samples before and after a carbon coating process by the exposure to acetylene at 1073 K, as well as desorption scanning curves and subloops on the untreated samples. These SBA-15 samples were synthesized under the different conditions of initial SiO2/P123 ratio and hydrothermal treatment. SBA-15 with relatively large microporosity tends to form easily constrictions inside the main channels by the carbon coating. This strongly suggests that the rough pore walls of SBA-15 may induce the incomplete wetting of carbon layers on the pore walls to form the constrictions inside the cylindrical pores. A comparison of two subloops implies that the pores of SBA-15 synthesized with a SiO2/P123 ratio of 75 consist of an assembly of connecting domains of different diameters; that is, the pores are highly corrugated. For SBA-15 synthesized with a SiO2/P123 ratio of 60, the amplitude of the pore corrugation is significantly decreased by the prolonged hydrothermal treatment at 373 K. On the other hand, for SBA-15 synthesized with a SiO2/P123 ratio of 45, the amplitude of the corrugation is negligibly small, although the cylindrical pores are interconnected through narrow necks with each other. It is found that the smaller the amplitude of the pore corrugation, the smaller the width of the hysteresis loop.

  4. Error analysis of acceleration control loops of a synchrotron

    International Nuclear Information System (INIS)

    Zhang, S.Y.; Weng, W.T.

    1991-01-01

    For beam control during acceleration, it is conventional to derive the frequency from an external reference, be it a field marker or an external oscillator, to provide phase and radius feedback loops to ensure the phase stability, radial position and emittance integrity of the beam. The open and closed loop behaviors of both feedback control and their response under the possible frequency, phase and radius errors are derived from fundamental principles and equations. The stability of the loops is investigated under a wide range of variations of the gain and time delays. Actual system performance of the AGS Booster is analyzed and compared to commissioning experiences. Such analysis is useful for setting design criteria and tolerances for new proton synchrotrons. 4 refs., 13 figs

  5. Visualization of enzyme activities inside earthworm pores

    Science.gov (United States)

    Hoang, Duyen; Razavi, Bahar S.

    2015-04-01

    In extremely dynamic microhabitats as bio-pores made by earthworm, the in situ enzyme activities are assumed as a footprint of complex biotic interactions. Our study focused on the effect of earthworm on the enzyme activities inside bio-pores and visualizing the differences between bio-pores and earthworm-free soil by zymography technique (Spohn and Kuzyakov, 2013). For the first time, we aimed at quantitative imaging of enzyme activities in bio-pores. Lumbricus terrestris L. was placed into transparent box (15×20×15cm). After two weeks when bio-pore systems were formed by earthworms, we visualized in situ enzyme activities of five hydrolytic enzymes (β-glucosidase, cellobiohydrolase, chitinase, xylanase, leucine-aminopeptidase, and phosphatase. Zymography showed higher activity of β-glucosidase, chitinase, xylanase and phosphatase in biopores comparing to bulk soil. However, the differences in activity of cellobiohydrolase and leucine aminopeptidase between bio-pore and bulk soil were less pronounced. This demonstrated an applicability of zymography approach to monitor and to distinguish the in situ activity of hydrolytic enzymes in soil biopores.

  6. One loop integrals reduction

    International Nuclear Information System (INIS)

    Sun Yi; Chang Haoran

    2012-01-01

    By further examining the symmetry of external momenta and masses in Feynman integrals, we fulfilled the method proposed by Battistel and Dallabona, and showed that recursion relations in this method can be applied to simplify Feynman integrals directly. (authors)

  7. Pore REconstruction and Segmentation (PORES) method for improved porosity quantification of nanoporous materials

    Energy Technology Data Exchange (ETDEWEB)

    Van Eyndhoven, G., E-mail: geert.vaneyndhoven@uantwerpen.be [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Kurttepeli, M. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Van Oers, C.J.; Cool, P. [Laboratory of Adsorption and Catalysis, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Bals, S. [EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Batenburg, K.J. [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium); Centrum Wiskunde and Informatica, Science Park 123, NL-1090 GB Amsterdam (Netherlands); Mathematical Institute, Universiteit Leiden, Niels Bohrweg 1, NL-2333 CA Leiden (Netherlands); Sijbers, J. [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk (Belgium)

    2015-01-15

    Electron tomography is currently a versatile tool to investigate the connection between the structure and properties of nanomaterials. However, a quantitative interpretation of electron tomography results is still far from straightforward. Especially accurate quantification of pore-space is hampered by artifacts introduced in all steps of the processing chain, i.e., acquisition, reconstruction, segmentation and quantification. Furthermore, most common approaches require subjective manual user input. In this paper, the PORES algorithm “POre REconstruction and Segmentation” is introduced; it is a tailor-made, integral approach, for the reconstruction, segmentation, and quantification of porous nanomaterials. The PORES processing chain starts by calculating a reconstruction with a nanoporous-specific reconstruction algorithm: the Simultaneous Update of Pore Pixels by iterative REconstruction and Simple Segmentation algorithm (SUPPRESS). It classifies the interior region to the pores during reconstruction, while reconstructing the remaining region by reducing the error with respect to the acquired electron microscopy data. The SUPPRESS reconstruction can be directly plugged into the remaining processing chain of the PORES algorithm, resulting in accurate individual pore quantification and full sample pore statistics. The proposed approach was extensively validated on both simulated and experimental data, indicating its ability to generate accurate statistics of nanoporous materials. - Highlights: • An electron tomography reconstruction/segmentation method for nanoporous materials. • The method exploits the porous nature of the scanned material. • Validated extensively on both simulation and real data experiments. • Results in increased image resolution and improved porosity quantification.

  8. Active pore space utilization in nanoporous carbon-based supercapacitors: Effects of conductivity and pore accessibility

    Science.gov (United States)

    Seredych, Mykola; Koscinski, Mikolaj; Sliwinska-Bartkowiak, Malgorzata; Bandosz, Teresa J.

    2012-12-01

    Composites of commercial graphene and nanoporous sodium-salt-polymer-derived carbons were prepared with 5 or 20 weight% graphene. The materials were characterized using the adsorption of nitrogen, SEM/EDX, thermal analysis, Raman spectroscopy and potentiometric titration. The samples' conductivity was also measured. The performance of the carbon composites in energy storage was linked to their porosity and electronic conductivity. The small pores (<0.7) were found as very active for double layer capacitance. It was demonstrated that when double layer capacitance is a predominant mechanism of charge storage, the degree of the pore space utilization for that storage can be increased by increasing the conductivity of the carbons. That active pore space utilization is defined as gravimetric capacitance per unit pore volume in pores smaller than 0.7 nm. Its magnitude is affected by conductivity of the carbon materials. The functional groups, besides pseudocapacitive contribution, increased the wettability and thus the degree of the pore space utilization. Graphene phase, owing to its conductivity, also took part in an insitu increase of the small pore accessibility and thus the capacitance of the composites via enhancing an electron transfer to small pores and thus imposing the reduction of groups blocking the pores for electrolyte ions.

  9. Closing the loop.

    Science.gov (United States)

    Dassau, E; Atlas, E; Phillip, M

    2010-02-01

    The dream of closing the loop is actually the dream of creating an artificial pancreas and freeing the patients from being involved with the care of their own diabetes. Insulin-dependent diabetes (type 1) is a chronic incurable disease which requires constant therapy without the possibility of any 'holidays' or insulin-free days. It means that patients have to inject insulin every day of their life, several times per day, and in order to do it safely they also have to measure their blood glucose levels several times per day. Patients need to plan their meals, their physical activities and their insulin regime - there is only very small room for spontaneous activities. This is why the desire for an artificial pancreas is so strong despite the fact that it will not cure the diabetic patients. Attempts to develop a closed-loop system started in the 1960s but never got to a clinical practical stage of development. In recent years the availability of continuous glucose sensors revived those efforts and stimulated the clinician and researchers to believe that closing the loop might be possible nowadays. Many papers have been published over the years describing several different ideas on how to close the loop. Most of the suggested systems have a sensing arm that measures the blood glucose repeatedly or continuously, an insulin delivery arm that injects insulin upon command and a computer that makes the decisions of when and how much insulin to deliver. The differences between the various published systems in the literature are mainly in their control algorithms. However, there are also differences related to the method and site of glucose measurement and insulin delivery. SC glucose measurements and insulin delivery are the most studied option but other combinations of insulin measurements and glucose delivery including intravascular and intraperitoneal (IP) are explored. We tried to select recent publications that we believe had influenced and inspired people interested

  10. Loop Quantum Cosmology.

    Science.gov (United States)

    Bojowald, Martin

    2008-01-01

    Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time. Supplementary material is available for this article at 10.12942/lrr-2008-4.

  11. Loop Quantum Cosmology

    Directory of Open Access Journals (Sweden)

    Bojowald Martin

    2008-07-01

    Full Text Available Quantum gravity is expected to be necessary in order to understand situations in which classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical spacetime inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding spacetime is then modified. One particular theory is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. The main effects are introduced into effective classical equations, which allow one to avoid the interpretational problems of quantum theory. They give rise to new kinds of early-universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function, which allows an extension of quantum spacetime beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of spacetime arising in loop quantum gravity and its application to cosmology sheds light on more general issues, such as the nature of time.

  12. Loop Quantum Cosmology

    Directory of Open Access Journals (Sweden)

    Bojowald Martin

    2005-12-01

    Full Text Available Quantum gravity is expected to be necessary in order to understand situations where classical general relativity breaks down. In particular in cosmology one has to deal with initial singularities, i.e., the fact that the backward evolution of a classical space-time inevitably comes to an end after a finite amount of proper time. This presents a breakdown of the classical picture and requires an extended theory for a meaningful description. Since small length scales and high curvatures are involved, quantum effects must play a role. Not only the singularity itself but also the surrounding space-time is then modified. One particular realization is loop quantum cosmology, an application of loop quantum gravity to homogeneous systems, which removes classical singularities. Its implications can be studied at different levels. Main effects are introduced into effective classical equations which allow to avoid interpretational problems of quantum theory. They give rise to new kinds of early universe phenomenology with applications to inflation and cyclic models. To resolve classical singularities and to understand the structure of geometry around them, the quantum description is necessary. Classical evolution is then replaced by a difference equation for a wave function which allows to extend space-time beyond classical singularities. One main question is how these homogeneous scenarios are related to full loop quantum gravity, which can be dealt with at the level of distributional symmetric states. Finally, the new structure of space-time arising in loop quantum gravity and its application to cosmology sheds new light on more general issues such as time.

  13. Facial skin pores: a multiethnic study.

    Science.gov (United States)

    Flament, Frederic; Francois, Ghislain; Qiu, Huixia; Ye, Chengda; Hanaya, Tomoo; Batisse, Dominique; Cointereau-Chardon, Suzy; Seixas, Mirela Donato Gianeti; Dal Belo, Susi Elaine; Bazin, Roland

    2015-01-01

    Skin pores (SP), as they are called by laymen, are common and benign features mostly located on the face (nose, cheeks, etc) that generate many aesthetic concerns or complaints. Despite the prevalence of skin pores, related literature is scarce. With the aim of describing the prevalence of skin pores and anatomic features among ethnic groups, a dermatoscopic instrument, using polarized lighting, coupled to a digital camera recorded the major features of skin pores (size, density, coverage) on the cheeks of 2,585 women in different countries and continents. A detection threshold of 250 μm, correlated to clinical scorings by experts, was input into a specific software to further allow for automatic counting of the SP density (N/cm(2)) and determination of their respective sizes in mm(2). Integrating both criteria also led to establishing the relative part of the skin surface (as a percentage) that is actually covered by SP on cheeks. The results showed that the values of respective sizes, densities, and skin coverage: 1) were recorded in all studied subjects; 2) varied greatly with ethnicity; 3) plateaued with age in most cases; and 4) globally refected self-assessment by subjects, in particular those who self-declare having "enlarged pores" like Brazilian women. Inversely, Chinese women were clearly distinct from other ethnicities in having very low density and sizes. Analyzing the present results suggests that facial skin pore's morphology as perceived by human eye less result from functional criteria of associated appendages such as sebaceous glands. To what extent skin pores may be viewed as additional criteria of a photo-altered skin is an issue to be further addressed.

  14. LoopIng: a template-based tool for predicting the structure of protein loops.

    KAUST Repository

    Messih, Mario Abdel

    2015-08-06

    Predicting the structure of protein loops is very challenging, mainly because they are not necessarily subject to strong evolutionary pressure. This implies that, unlike the rest of the protein, standard homology modeling techniques are not very effective in modeling their structure. However, loops are often involved in protein function, hence inferring their structure is important for predicting protein structure as well as function.We describe a method, LoopIng, based on the Random Forest automated learning technique, which, given a target loop, selects a structural template for it from a database of loop candidates. Compared to the most recently available methods, LoopIng is able to achieve similar accuracy for short loops (4-10 residues) and significant enhancements for long loops (11-20 residues). The quality of the predictions is robust to errors that unavoidably affect the stem regions when these are modeled. The method returns a confidence score for the predicted template loops and has the advantage of being very fast (on average: 1 min/loop).www.biocomputing.it/loopinganna.tramontano@uniroma1.itSupplementary data are available at Bioinformatics online.

  15. Wilson loops in minimal surfaces

    International Nuclear Information System (INIS)

    Drukker, Nadav; Gross, David J.; Ooguri, Hirosi

    1999-01-01

    The AdS/CFT correspondence suggests that the Wilson loop of the large N gauge theory with N = 4 supersymmetry in 4 dimensions is described by a minimal surface in AdS 5 x S 5 . The authors examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which the authors call BPS loops, whose expectation values are free from ultra-violet divergence. They formulate the loop equation for such loops. To the extent that they have checked, the minimal surface in AdS 5 x S 5 gives a solution of the equation. The authors also discuss the zig-zag symmetry of the loop operator. In the N = 4 gauge theory, they expect the zig-zag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. They will show how this is realized for the minimal surface

  16. Wilson loops and minimal surfaces

    International Nuclear Information System (INIS)

    Drukker, Nadav; Gross, David J.; Ooguri, Hirosi

    1999-01-01

    The AdS-CFT correspondence suggests that the Wilson loop of the large N gauge theory with N=4 supersymmetry in four dimensions is described by a minimal surface in AdS 5 xS 5 . We examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which we call BPS loops, whose expectation values are free from ultraviolet divergence. We formulate the loop equation for such loops. To the extent that we have checked, the minimal surface in AdS 5 xS 5 gives a solution of the equation. We also discuss the zigzag symmetry of the loop operator. In the N=4 gauge theory, we expect the zigzag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. We will show how this is realized for the minimal surface. (c) 1999 The American Physical Society

  17. On the amplitude/Wilson loop duality in N=2 SCQCD

    Directory of Open Access Journals (Sweden)

    Marta Leoni

    2015-07-01

    Full Text Available We compute the four-point amplitude with external adjoint particles in N=2 SCQCD at two loops using N=1 superspace Feynman diagrams, extending the results of arXiv:1406.7283. We consider the diagrammatic difference with the corresponding process of N=4 SYM finding a non-vanishing result, which is a non-trivial function of the kinematic variables. This demonstrates that in N=2 SCQCD, even in the sector with external particles in the vector multiplet, the amplitude/Wilson loop duality is inevitably broken at two loops.

  18. Using BIB-SEM to determine pore morphology and pore size distributions in coal macerals

    Energy Technology Data Exchange (ETDEWEB)

    Giffin, S.; Littke, R. [RWTH Aachen Univ. (Germany). Inst. of Geology and Geochemistry of Petroleum and Coal; Klaver, J.; Urai, J.L. [RWTH Aachen Univ. (Germany). Structural Geology, Tectonics and Geomechanics

    2013-08-01

    The composition of coalbeds is considerably heterogeneous, affecting the transport pathways for fluids within the coal. Transport pathways include cleats and larger pores. However, only a few clues exist as the nature of these pores. This study examines the morphology and distribution of macro- and mesopores in coal samples, using broad ion beam (BIB) milling to prepare relief- and damage-free polished surfaces of coal samples for high-resolution SEM imaging. Broad ion beam milling is advantageous to focused ion beam milling in that a larger surface area can be milled. Combining that with SEM imaging results in a useful tool to study pore morphology and distributions in the size range between 10 nm and 10 {mu}m. Since BIB-sections of a few square millimeters are not large enough to be statistically representative, results cannot be easily interpreted from a coal seam standpoint. Therefore, porosity was investigated as a function of maceral type to characterize pore morphologies. Macerals from the vitrinite and inertinite groups were selected with a known relationship to bedding. BIB-sections were milled parallel to bedding and perpendicular to bedding, and the pores were evaluated in each section. The goal of this study is to (1) qualitatively describe pore morphology with respect to maceral type and (2) quantitatively characterize pore size distributions with respect to maceral and in relationship to bedding. Our results lead to a better understanding of bulk coal porosity due to the visual, spatial representation and quantification of pores in individual macerals. (orig.)

  19. TIG Dressing Effects on Weld Pores and Pore Cracking of Titanium Weldments

    Directory of Open Access Journals (Sweden)

    Hui-Jun Yi

    2016-10-01

    Full Text Available Weld pores redistribution, the effectiveness of using tungsten inert gas (TIG dressing to remove weld pores, and changes in the mechanical properties due to the TIG dressing of Ti-3Al-2.5V weldments were studied. Moreover, weld cracks due to pores were investigated. The results show that weld pores less than 300 μm in size are redistributed or removed via remelting due to TIG dressing. Regardless of the temperature condition, TIG dressing welding showed ductility, and there was a loss of 7% tensile strength of the weldments. Additionally, it was considered that porosity redistribution by TIG dressing was due to fluid flow during the remelting of the weld pool. Weld cracks in titanium weldment create branch cracks around pores that propagate via the intragranular fracture, and oxygen is dispersed around the pores. It is suggested that the pore locations around the LBZ (local brittle zone and stress concentration due to the pores have significant effects on crack initiation and propagation.

  20. Stretchable Random Lasers with Tunable Coherent Loops.

    Science.gov (United States)

    Sun, Tzu-Min; Wang, Cih-Su; Liao, Chi-Shiun; Lin, Shih-Yao; Perumal, Packiyaraj; Chiang, Chia-Wei; Chen, Yang-Fang

    2015-12-22

    Stretchability represents a key feature for the emerging world of realistic applications in areas, including wearable gadgets, health monitors, and robotic skins. Many optical and electronic technologies that can respond to large strain deformations have been developed. Laser plays a very important role in our daily life since it was discovered, which is highly desirable for the development of stretchable devices. Herein, stretchable random lasers with tunable coherent loops are designed, fabricated, and demonstrated. To illustrate our working principle, the stretchable random laser is made possible by transferring unique ZnO nanobrushes on top of polydimethylsiloxane (PDMS) elastomer substrate. Apart from the traditional gain material of ZnO nanorods, ZnO nanobrushes were used as optical gain materials so they can serve as scattering centers and provide the Fabry-Perot cavity to enhance laser action. The stretchable PDMS substrate gives the degree of freedom to mechanically tune the coherent loops of the random laser action by changing the density of ZnO nanobrushes. It is found that the number of laser modes increases with increasing external strain applied on the PDMS substrate due to the enhanced possibility for the formation of coherent loops. The device can be stretched by up to 30% strain and subjected to more than 100 cycles without loss in laser action. The result shows a major advance for the further development of man-made smart stretchable devices.

  1. On some properties of conjugacy closed loops

    International Nuclear Information System (INIS)

    Adeniran, John Olusola

    2002-07-01

    It is shown that central loops are not conjugacy closed loops but instead are loops of units in their loop algebras that are conjugacy closed. It is also shown that certain inner mappings of a conjugacy closed loop are nuclear. Some invariants of left conjugacy closed loops are obtained. (author)

  2. Moving Magnetic Features Around a Pore

    Energy Technology Data Exchange (ETDEWEB)

    Kaithakkal, A. J.; Riethmüller, T. L.; Solanki, S. K.; Lagg, A.; Barthol, P.; Gandorfer, A.; Gizon, L.; Hirzberger, J.; VanNoort, M. [Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, Göttingen D-37077 (Germany); Rodríguez, J. Blanco [Grupo de Astronomía y Ciencias del Espacio, Universidad de Valencia, E-46980 Paterna, Valencia (Spain); Iniesta, J. C. Del Toro; Suárez, D. Orozco [Instituto de Astrofísica de Andalucía (CSIC), Apartado de Correos 3004, E-18080 Granada (Spain); Schmidt, W. [Kiepenheuer-Institut für Sonnenphysik, Schöneckstr. 6, D-79104 Freiburg (Germany); Pillet, V. Martínez [National Solar Observatory, 3665 Discovery Drive, Boulder, CO 80303 (United States); Knölker, M., E-mail: anjali@mps.mpg.de [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States)

    2017-03-01

    Spectropolarimetric observations from Sunrise/IMaX, obtained in 2013 June, are used for a statistical analysis to determine the physical properties of moving magnetic features (MMFs) observed near a pore. MMFs of the same and opposite polarity, with respect to the pore, are found to stream from its border at an average speed of 1.3 km s{sup −1} and 1.2 km s{sup −1}, respectively, with mainly same-polarity MMFs found further away from the pore. MMFs of both polarities are found to harbor rather weak, inclined magnetic fields. Opposite-polarity MMFs are blueshifted, whereas same-polarity MMFs do not show any preference for up- or downflows. Most of the MMFs are found to be of sub-arcsecond size and carry a mean flux of ∼1.2 × 10{sup 17} Mx.

  3. Gas transport and subsoil pore characteristics

    DEFF Research Database (Denmark)

    Berisso, Feto Esimo; Schjønning, Per; Keller, Thomas

    2013-01-01

    Arrangements of elementary soil particles during soil deposition and subsequent biological and physical processes in long-term pedogenesis are expected to lead to anisotropy of the non-tilled subsoil pore system. Soil compaction by agricultural machinery is known to affect soil pore characteristics...... were sampled in vertical and horizontal directions from 0.3, 0.5, 0.7 and 0.9 m depth (the two lower depths only in Sweden). In the laboratory, water retention, air permeability (ka) and gas diffusivity (Ds/D0) were determined. For the sandy clay loam, morphological characteristics of pores (effective......). In the sandy clay loam soil, dB and nB displayed significant anisotropy (FAcharacteristics because of its origin...

  4. Gluons and gravitons at one loop from ambitwistor strings

    Science.gov (United States)

    Geyer, Yvonne; Monteiro, Ricardo

    2018-03-01

    We present new and explicit formulae for the one-loop integrands of scattering amplitudes in non-supersymmetric gauge theory and gravity, valid for any number of particles. The results exhibit the colour-kinematics duality in gauge theory and the double-copy relation to gravity, in a form that was recently observed in supersymmetric theories. The new formulae are expressed in a particular representation of the loop integrand, with only one quadratic propagator, which arises naturally from the framework of the loop-level scattering equations. The starting point in our work are the expressions based on the scattering equations that were recently derived from ambitwistor string theory. We turn these expressions into explicit formulae depending only on the loop momentum, the external momenta and the external polarisations. These formulae are valid in any number of spacetime dimensions for pure Yang-Mills theory (gluon) and its natural double copy, NS-NS gravity (graviton, dilaton, B-field), and we also present formulae in four spacetime dimensions for pure gravity (graviton). We perform several tests of our results, such as checking gauge invariance and directly matching our four-particle formulae to previously known expressions. While these tests would be elaborate in a Feynman-type representation of the loop integrand, they become straightforward in the representation we use.

  5. Long n-alkanes isomerization by medium pore zeolites with pore mouth and key lock mechanisms; Isomerisation des paraffines longues par des zeolithes a pores moyens selon les mecanismes ouverture de pore et cle serrure

    Energy Technology Data Exchange (ETDEWEB)

    Claude, M.

    1999-10-01

    Skeletal isomerization of long n-alkanes is practiced to improve cold flow properties of diesel and lubricant fractions. In this work, model long n-alkanes (n-C{sub 10} - n-C{sub 24}) were hydro-isomerized in a fixed bed down flow vapour phase reactor loaded with bifunctional Pt/H-ZSM-22 zeolite catalyst. The skeletal isomers were analysed and identified with GC/MS. High isomer yields were obtained. The distribution of positional mono-methyl-branched isomers obtained from n-C{sub 12} to n-C{sub 24} are typically bimodal. This is explained by adsorption and reaction of the alkanes in pore mouths and locks on the external surface of the zeolite crystals. The pore mouth mode favours branching at C{sub 2} and C{sub 3}. The 'key lock' type proceeds by penetration of the two ends of the hydrocarbon chain into a different pore opening and favours more central mono-branching of the chain. The contribution of the key lock mode increases with increasing chain length and with the reaction temperature. The preferentially formed dimethyl-branched isomers have a separation between branchings of three up to fourteen carbon atoms. The formation of the second methyl-branching occurs preferentially from a centrally branched mono-methyl-branched isomer, so that the second branching is generated always more toward the end of the chain. Owing to the differences in adsorption entropy among the locks, at higher temperatures the largest lock is preferred and the distance between the two branching along the carbon chain in the preferred isomers is biggest. Thus the work resulted in the formulation of structure-selectivity relationships. n-C{sub 18} was hydro-isomerized on other zeolites. The nature and distribution of the isomers obtained suggest that the tubular 10-ring zeolites ZSM-23, ZSM-35 and SAPO-11 also operate according to pore mouth and key lock concepts. Zeolites with 12-rings show typical product patterns for catalysis in absence of steric hindrance. (author)

  6. Porous media fluid transport and pore structure

    CERN Document Server

    Dullien, F A L

    1992-01-01

    This book examines the relationship between transport properties and pore structure of porous material. Models of pore structure are presented with a discussion of how such models can be used to predict the transport properties of porous media. Portions of the book are devoted to interpretations of experimental results in this area and directions for future research. Practical applications are given where applicable, and are expected to be useful for a large number of different fields, including reservoir engineering, geology, hydrogeology, soil science, chemical process engineering, biomedica

  7. Nuclear pore complex tethers to the cytoskeleton.

    Science.gov (United States)

    Goldberg, Martin W

    2017-08-01

    The nuclear envelope is tethered to the cytoskeleton. The best known attachments of all elements of the cytoskeleton are via the so-called LINC complex. However, the nuclear pore complexes, which mediate the transport of soluble and membrane bound molecules, are also linked to the microtubule network, primarily via motor proteins (dynein and kinesins) which are linked, most importantly, to the cytoplasmic filament protein of the nuclear pore complex, Nup358, by the adaptor BicD2. The evidence for such linkages and possible roles in nuclear migration, cell cycle control, nuclear transport and cell architecture are discussed. Copyright © 2017. Published by Elsevier Ltd.

  8. Dissolution at porous interfaces VI: Multiple pore systems.

    Science.gov (United States)

    Grijseels, H; Crommelin, D J; De Blaey, C J

    1984-12-01

    With the aid of rapidly dissolving sodium chloride particles, cubic pores were made in the surface of a theophylline tablet. The influence of the pores on the dissolution rate of the surface was investigated in a rotating disk apparatus. Like the drilled pores used in earlier studies, downstream on the surface they caused a turbulent flow regimen with the development of a trough due to enhanced erosion. The phenomenon of a critical pore diameter, discovered with single, drilled pores, seems to be applicable to the cubic pores investigated in this study, although a higher degree of surface coverage with pores caused complications, probably due to particles bordering one another and forming larger pores. The behavior of the porous surfaces at different rotation speeds was studied. Due to the presence of pores the laminar character of the boundary layer flow changes to turbulent, which induces locally an increased dissolution flux in the wake of a pore.

  9. Step-wise potential development across the lipid bilayer under external electric fields

    Science.gov (United States)

    Majhi, Amit Kumar

    2018-04-01

    Pore formation across the bilayers under external electric field is an important phenomenon, which has numerous applications in biology and bio-engineering fields. However, it is not a ubiquitous event under all field applications. To initiate a pore in the bilayer a particular threshold electric field is required. The electric field alters the intrinsic potential distribution across the bilayer as we as it enhances total potential drop across the bilayer, which causes the pore formation. The intrinsic potential profile has a maximum peak value, which is 0.8 V and it gets enhanced under application of external field, 0.43 V/nm. The peak value becomes 1.4 V when a pore appears in the bilayer and it continues to evolve as along as the external electric field remains switched on.

  10. Electrochemical growth of nanowires in anodic alumina templates: the role of pore branching

    International Nuclear Information System (INIS)

    Noyan, Alexey A.; Leontiev, Alexey P.; Yakovlev, Maxim V.; Roslyakov, Ilya V.; Tsirlina, Galina A.; Napolskii, Kirill S.

    2017-01-01

    Highlights: • The model of metal growth inside the anodic alumina with branched pores is developed. • Model predicts the dependence of anodic alumina filling on deposition regime. • Branched pores affect the uniformity of anodic alumina filling with electrodeposits. • Branched pores make growth front of metal nanowires inside template multimodal. - Abstract: A comparative study of electrochemical growth of nanowires in the anodic alumina templates with various degree of porous structure ordering is performed. Scanning electron microscopy and coulometric analysis are used for experimental evaluation of the average filling of pores with metal. The theoretical model of metal growth inside anodic alumina templates is proposed. The model takes into account the presence of branched channels in the real structure of anodic alumina and operates with completeness of template filling achieved at the moment when metal reaches the external surface of the oxide film. In case of the diffusion-controlled regime the strong dependence of the pore filling factor on the thickness of porous film and the degree of its structure ordering is predicted theoretically and observed experimentally. The influence of the nature of limiting current on the homogeneity and completeness of template filling is discussed.

  11. Behaviors and kinetics of toluene adsorption-desorption on activated carbons with varying pore structure.

    Science.gov (United States)

    Yang, Xi; Yi, Honghong; Tang, Xiaolong; Zhao, Shunzheng; Yang, Zhongyu; Ma, Yueqiang; Feng, Tiecheng; Cui, Xiaoxu

    2018-05-01

    This work was undertaken to investigate the behaviors and kinetics of toluene adsorption and desorption on activated carbons with varying pore structure. Five kinds of activated carbon from different raw materials were selected. Adsorption isotherms and breakthrough curves for toluene were measured. Langmuir and Freundlich equations were fitted to the equilibrium data, and the Freundlich equation was more suitable for simulating toluene adsorption. The process consisted of monolayer, multilayer and partial active site adsorption types. The effect of the pore structure of the activated carbons on toluene adsorption capacity was investigated. The quasi-first-order model was more suitable for describing the process than the quasi-second-order model. The adsorption data was also modeled by the internal particle diffusion model and it was found that the adsorption process could be divided into three stages. In the external surface adsorption process, the rate depended on the specific surface area. During the particle diffusion stage, pore structure and volume were the main factors affecting adsorption rate. In the final equilibrium stage, the rate was determined by the ratio of meso- and macro-pores to total pore volume. The rate over the whole adsorption process was dominated by the toluene concentration. The desorption behavior of toluene on activated carbons was investigated, and the process was divided into heat and mass transfer parts corresponding to emission and diffusion mechanisms, respectively. Physical adsorption played the main role during the adsorption process. Copyright © 2017. Published by Elsevier B.V.

  12. Two-loop polygon Wilson loops in N = 4 SYM

    International Nuclear Information System (INIS)

    Anastasiou, C.; Brandhuber, A.; Heslop, P.; Spence, B.; Travaglini, G.; Khoze, V.V.

    2009-01-01

    We compute for the first time the two-loop corrections to arbitrary n-gon lightlike Wilson loops in N = 4 supersymmetric Yang-Mills theory, using efficient numerical methods. The calculation is motivated by the remarkable agreement between the finite part of planar six-point MHV amplitudes and hexagon Wilson loops which has been observed at two loops. At n = 6 we confirm that the ABDK/BDS ansatz must be corrected by adding a remainder function, which depends only on conformally invariant ratios of kinematic variables. We numerically compute remainder functions for n = 7,8 and verify dual conformal invariance. Furthermore, we study simple and multiple collinear limits of the Wilson loop remainder functions and demonstrate that they have precisely the form required by the collinear factorisation of the corresponding two-loop n-point amplitudes. The number of distinct diagram topologies contributing to the n-gon Wilson loops does not increase with n, and there is a fixed number of 'master integrals', which we have computed. Thus we have essentially computed general polygon Wilson loops, and if the correspondence with amplitudes continues to hold, all planar n-point two-loop MHV amplitudes in the N = 4 theory.

  13. Multi-parton loop amplitudes and next-to-leading order jet cross-sections

    International Nuclear Information System (INIS)

    Bern, Z.; Dixon, L.; Kosower, D.A.; Signer, A.

    1998-02-01

    The authors review recent developments in the calculation of QCD loop amplitudes with several external legs, and their application to next-to-leading order jet production cross-sections. When a number of calculational tools are combined together--helicity, color and supersymmetry decompositions, plus unitarity and factorization properties--it becomes possible to compute multi-parton one-loop QCD amplitudes without ever evaluating analytically standard one-loop Feynman diagrams. One-loop helicity amplitudes are now available for processes with five external partons (ggggg, q anti qggg and q anti qq anti q' g), and for an intermediate vector boson V ≡ γ * , Z, W plus four external partons (V q anti q and V q anti qq'anti q'). Using these amplitudes, numerical programs have been constructed for the next-to-leading order corrections to the processes p anti p → 3 jets (ignoring quark contributions so far) and e + e - → 4 jets

  14. High temperature storage loop :

    Energy Technology Data Exchange (ETDEWEB)

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  15. Accelerating the loop expansion

    International Nuclear Information System (INIS)

    Ingermanson, R.

    1986-01-01

    This thesis introduces a new non-perturbative technique into quantum field theory. To illustrate the method, I analyze the much-studied phi 4 theory in two dimensions. As a prelude, I first show that the Hartree approximation is easy to obtain from the calculation of the one-loop effective potential by a simple modification of the propagator that does not affect the perturbative renormalization procedure. A further modification then susggests itself, which has the same nice property, and which automatically yields a convex effective potential. I then show that both of these modifications extend naturally to higher orders in the derivative expansion of the effective action and to higher orders in the loop-expansion. The net effect is to re-sum the perturbation series for the effective action as a systematic ''accelerated'' non-perturbative expansion. Each term in the accelerated expansion corresponds to an infinite number of terms in the original series. Each term can be computed explicitly, albeit numerically. Many numerical graphs of the various approximations to the first two terms in the derivative expansion are given. I discuss the reliability of the results and the problem of spontaneous symmetry-breaking, as well as some potential applications to more interesting field theories. 40 refs

  16. Mirror symmetry and loop operators

    Energy Technology Data Exchange (ETDEWEB)

    Assel, Benjamin [Department of Mathematics, King’s College London,The Strand, London WC2R 2LS (United Kingdom); Gomis, Jaume [Perimeter Institute for Theoretical Physics,Waterloo, Ontario, N2L 2Y5 (Canada)

    2015-11-09

    Wilson loops in gauge theories pose a fundamental challenge for dualities. Wilson loops are labeled by a representation of the gauge group and should map under duality to loop operators labeled by the same data, yet generically, dual theories have completely different gauge groups. In this paper we resolve this conundrum for three dimensional mirror symmetry. We show that Wilson loops are exchanged under mirror symmetry with Vortex loop operators, whose microscopic definition in terms of a supersymmetric quantum mechanics coupled to the theory encode in a non-trivial way a representation of the original gauge group, despite that the gauge groups of mirror theories can be radically different. Our predictions for the mirror map, which we derive guided by branes in string theory, are confirmed by the computation of the exact expectation value of Wilson and Vortex loop operators on the three-sphere.

  17. Reactor recirculation pump test loop

    International Nuclear Information System (INIS)

    Taka, Shusei; Kato, Hiroyuki

    1979-01-01

    A test loop for a reactor primary loop recirculation pumps (PLR pumps) has been constructed at Ebara's Haneda Plant in preparation for production of PLR pumps under license from Byron Jackson Pump Division of Borg-Warner Corporation. This loop can simulate operating conditions for test PLR pumps with 130 per cent of the capacity of pumps for a 1100 MWe BWR plant. A main loop, primary cooling system, water demineralizer, secondary cooling system, instrumentation and control equipment and an electric power supply system make up the test loop. This article describes the test loop itself and test results of two PLR pumps for Fukushima No. 2 N.P.S. Unit 1 and one main circulation pump for HAZ Demonstration Test Facility. (author)

  18. Capillary Condensation in Pores with Rough Walls:

    Czech Academy of Sciences Publication Activity Database

    Bryk, P.; Rżysko, W.; Malijevský, Alexandr; Sokołowski, S.

    2007-01-01

    Roč. 313, č. 1 (2007), s. 41-52 ISSN 0021-9797 Grant - others:TOK(XE) 509249 Institutional research plan: CEZ:AV0Z40720504 Source of funding: R - rámcový projekt EK Keywords : adsorption * pore * capillary condensation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.309, year: 2007

  19. Mimicking the nuclear pore complex using nanopores

    NARCIS (Netherlands)

    Ananth, A.N.

    2018-01-01

    Nuclear pore complexes acts as a gatekeeper for molecular transport between the nucleus and the cytoplasm in eukaryotic cells. The central NPC channel is filled with intrinsically disordered FG domains (phenylalanine (F), glycine (G)) that are responsible for the fascinating selectivity of NPCs, for

  20. Induction of nano pore in Agrobacterial hemoglobin

    Directory of Open Access Journals (Sweden)

    Mojtaba Tousheh

    2014-01-01

    Full Text Available Introduction: A variety of oxygen-transport and -binding proteins exist in organisms including bacteria, protozoans, and fungi all have hemoglobin-like proteins. In addition to dealing with transport and sensing of oxygen, they may also deal with NO2, CO2, sulfide compounds, and even O2 scavenging in environments. Also they detoxified chlorinated materials like P450 enzymes and peroxidases and use as a detector of nitrate and hydrogen peroxide. Pore-forming bacterial globins are interested for filtration. Materials and methods: Although there are data for bacterial toxin as a filter, here we used Agrobacterial hem to induce nano pore in the heme structure using point mutation. Results: Investigations showed that three amino acids leucine 76, alanine 83 and histidine 80 are important for pore formation in Agrobacterium hemoglobin. A point mutation on leucine 76 to glycine, histidine 80 to asparagine and alanine 83 to lysine step by step led to create the nano pore 0.7- 0.8 nm in the globin. Discussion and conclusion: These mutations in bacterial hemoglobin increase the stability when mutation is with it’s at pH7. This mutation decreases the aliphatic index however increase the stability index.

  1. Regulating multiple externalities

    DEFF Research Database (Denmark)

    Waldo, Staffan; Jensen, Frank; Nielsen, Max

    2016-01-01

    Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory instrume......Open access is a well-known externality problem in fisheries causing excess capacity and overfishing. Due to global warming, externality problems from CO2 emissions have gained increased interest. With two externality problems, a first-best optimum can be achieved by using two regulatory...

  2. Loop Heat Pipe Startup Behaviors

    Science.gov (United States)

    Ku, Jentung

    2016-01-01

    A loop heat pipe must start successfully before it can commence its service. The startup transient represents one of the most complex phenomena in the loop heat pipe operation. This paper discusses various aspects of loop heat pipe startup behaviors. Topics include the four startup scenarios, the initial fluid distribution between the evaporator and reservoir that determines the startup scenario, factors that affect the fluid distribution between the evaporator and reservoir, difficulties encountered during the low power startup, and methods to enhance the startup success. Also addressed are the pressure spike and pressure surge during the startup transient, and repeated cycles of loop startup and shutdown under certain conditions.

  3. Modeling of compact loop antennas

    International Nuclear Information System (INIS)

    Baity, F.W.

    1987-01-01

    A general compact loop antenna model which treats all elements of the antenna as lossy transmission lines has been developed. In addition to capacitively-tuned resonant double loop (RDL) antennas the model treats stub-tuned resonant double loop antennas. Calculations using the model have been compared with measurements on full-scale mockups of resonant double loop antennas for ATF and TFTR in order to refine the transmission line parameters. Results from the model are presented for RDL antenna designs for ATF, TFTR, Tore Supra, and for the Compact Ignition Tokamak

  4. ExternE National Implementation Finland

    Energy Technology Data Exchange (ETDEWEB)

    Pingoud, K; Maelkki, H; Wihersaari, M; Pirilae, P [VTT Energy, Espoo (Finland); Hongisto, M [Imatran Voima Oy, Vantaa (Finland); Siitonen, S [Ekono Energy Ltd, Espoo (Finland); Johansson, M [Finnish Environment Institute, Helsinki (Finland)

    1999-07-01

    ExternE National Implementation is a continuation of the ExternE Project, funded in part by the European Commission's Joule III Programme. This study is the result of the ExternE National Implementation Project for Finland. Three fuel cycles were selected for the Finnish study: coal, peat and wood-derived biomass, which together are responsible for about 40% of total electricity generation in Finland and about 75% of the non-nuclear fuel based generation. The estimated external costs or damages were dominated by the global warming (GW) impacts in the coal and peat fuel cycles, but knowledge of the true GW impacts is still uncertain. From among other impacts that were valued in monetary terms the human health damages due to airborne emissions dominated in all the three fuel cycles. Monetary valuation for ecosystem impacts is not possible using the ExternE methodology at present. The Meri-Pori power station representing the coal fuel cycle is one of the world's cleanest and most efficient coal-fired power plants with a condensing turbine. The coal is imported mainly from Poland. The estimated health damages were about 4 mECU/kWh, crop damages an order of magnitude lower and damages caused to building materials two orders of magnitude lower. The power stations of the peat and biomass fuel cycles are of CHP type, generating electricity and heat for the district heating systems of two cities. Their fuels are of domestic origin. The estimated health damages allocated to electricity generation were about 5 and 6 mECU/kWh, respectively. The estimates were case-specific and thus an generalisation of the results to the whole electricity generation in Finland is unrealistic. Despite the uncertainties and limitations of the methodology, it is a promising tool in the comparison of similar kinds of fuel cycles, new power plants and pollution abatement technologies and different plant locations with each other. (orig.)

  5. ExternE National Implementation Finland

    International Nuclear Information System (INIS)

    Pingoud, K.; Maelkki, H.; Wihersaari, M.; Pirilae, P.; Hongisto, M.; Siitonen, S.; Johansson, M.

    1999-01-01

    ExternE National Implementation is a continuation of the ExternE Project, funded in part by the European Commission's Joule III Programme. This study is the result of the ExternE National Implementation Project for Finland. Three fuel cycles were selected for the Finnish study: coal, peat and wood-derived biomass, which together are responsible for about 40% of total electricity generation in Finland and about 75% of the non-nuclear fuel based generation. The estimated external costs or damages were dominated by the global warming (GW) impacts in the coal and peat fuel cycles, but knowledge of the true GW impacts is still uncertain. From among other impacts that were valued in monetary terms the human health damages due to airborne emissions dominated in all the three fuel cycles. Monetary valuation for ecosystem impacts is not possible using the ExternE methodology at present. The Meri-Pori power station representing the coal fuel cycle is one of the world's cleanest and most efficient coal-fired power plants with a condensing turbine. The coal is imported mainly from Poland. The estimated health damages were about 4 mECU/kWh, crop damages an order of magnitude lower and damages caused to building materials two orders of magnitude lower. The power stations of the peat and biomass fuel cycles are of CHP type, generating electricity and heat for the district heating systems of two cities. Their fuels are of domestic origin. The estimated health damages allocated to electricity generation were about 5 and 6 mECU/kWh, respectively. The estimates were case-specific and thus an generalisation of the results to the whole electricity generation in Finland is unrealistic. Despite the uncertainties and limitations of the methodology, it is a promising tool in the comparison of similar kinds of fuel cycles, new power plants and pollution abatement technologies and different plant locations with each other. (orig.)

  6. ExternE National Implementation Finland

    Energy Technology Data Exchange (ETDEWEB)

    Pingoud, K.; Maelkki, H.; Wihersaari, M.; Pirilae, P. [VTT Energy, Espoo (Finland); Hongisto, M. [Imatran Voima Oy, Vantaa (Finland); Siitonen, S. [Ekono Energy Ltd, Espoo (Finland); Johansson, M. [Finnish Environment Institute, Helsinki (Finland)

    1999-07-01

    ExternE National Implementation is a continuation of the ExternE Project, funded in part by the European Commission's Joule III Programme. This study is the result of the ExternE National Implementation Project for Finland. Three fuel cycles were selected for the Finnish study: coal, peat and wood-derived biomass, which together are responsible for about 40% of total electricity generation in Finland and about 75% of the non-nuclear fuel based generation. The estimated external costs or damages were dominated by the global warming (GW) impacts in the coal and peat fuel cycles, but knowledge of the true GW impacts is still uncertain. From among other impacts that were valued in monetary terms the human health damages due to airborne emissions dominated in all the three fuel cycles. Monetary valuation for ecosystem impacts is not possible using the ExternE methodology at present. The Meri-Pori power station representing the coal fuel cycle is one of the world's cleanest and most efficient coal-fired power plants with a condensing turbine. The coal is imported mainly from Poland. The estimated health damages were about 4 mECU/kWh, crop damages an order of magnitude lower and damages caused to building materials two orders of magnitude lower. The power stations of the peat and biomass fuel cycles are of CHP type, generating electricity and heat for the district heating systems of two cities. Their fuels are of domestic origin. The estimated health damages allocated to electricity generation were about 5 and 6 mECU/kWh, respectively. The estimates were case-specific and thus an generalisation of the results to the whole electricity generation in Finland is unrealistic. Despite the uncertainties and limitations of the methodology, it is a promising tool in the comparison of similar kinds of fuel cycles, new power plants and pollution abatement technologies and different plant locations with each other. (orig.)

  7. X-ray pore optic developments

    Science.gov (United States)

    Wallace, Kotska; Bavdaz, Marcos; Collon, Maximilien; Beijersbergen, Marco; Kraft, Stefan; Fairbend, Ray; Séguy, Julien; Blanquer, Pascal; Graue, Roland; Kampf, Dirk

    2017-11-01

    In support of future x-ray telescopes ESA is developing new optics for the x-ray regime. To date, mass and volume have made x-ray imaging technology prohibitive to planetary remote sensing imaging missions. And although highly successful, the mirror technology used on ESA's XMM-Newton is not sufficient for future, large, x-ray observatories, since physical limits on the mirror packing density mean that aperture size becomes prohibitive. To reduce telescope mass and volume the packing density of mirror shells must be reduced, whilst maintaining alignment and rigidity. Structures can also benefit from a modular optic arrangement. Pore optics are shown to meet these requirements. This paper will discuss two pore optic technologies under development, with examples of results from measurement campaigns on samples. One activity has centred on the use of coated, silicon wafers, patterned with ribs, that are integrated onto a mandrel whose form has been polished to the required shape. The wafers follow the shape precisely, forming pore sizes in the sub-mm region. Individual stacks of mirrors can be manufactured without risk to, or dependency on, each other and aligned in a structure from which they can also be removed without hazard. A breadboard is currently being built to demonstrate this technology. A second activity centres on glass pore optics. However an adaptation of micro channel plate technology to form square pores has resulted in a monolithic material that can be slumped into an optic form. Alignment and coating of two such plates produces an x-ray focusing optic. A breadboard 20cm aperture optic is currently being built.

  8. Vortex loops and Majoranas

    International Nuclear Information System (INIS)

    Chesi, Stefano; Jaffe, Arthur; Loss, Daniel; Pedrocchi, Fabio L.

    2013-01-01

    We investigate the role that vortex loops play in characterizing eigenstates of interacting Majoranas. We give some general results and then focus on ladder Hamiltonian examples as a test of further ideas. Two methods yield exact results: (i) A mapping of certain spin Hamiltonians to quartic interactions of Majoranas shows that the spectra of these two examples coincide. (ii) In cases with reflection-symmetric Hamiltonians, we use reflection positivity for Majoranas to characterize vortices in the ground states. Two additional methods suggest wider applicability of these results: (iii) Numerical evidence suggests similar behavior for certain systems without reflection symmetry. (iv) A perturbative analysis also suggests similar behavior without the assumption of reflection symmetry

  9. Inductance loop and partial

    CERN Document Server

    Paul, Clayton R

    2010-01-01

    "Inductance is an unprecedented text, thoroughly discussing "loop" inductance as well as the increasingly important "partial" inductance. These concepts and their proper calculation are crucial in designing modern high-speed digital systems. World-renowned leader in electromagnetics Clayton Paul provides the knowledge and tools necessary to understand and calculate inductance." "With the present and increasing emphasis on high-speed digital systems and high-frequency analog systems, it is imperative that system designers develop an intimate understanding of the concepts and methods in this book. Inductance is a much-needed textbook designed for senior and graduate-level engineering students, as well as a hands-on guide for working engineers and professionals engaged in the design of high-speed digital and high-frequency analog systems."--Jacket.

  10. Dynamic PID loop control

    International Nuclear Information System (INIS)

    Pei, L.; Klebaner, A.; Theilacker, J.; Soyars, W.; Martinez, A.; Bossert, R.; DeGraff, B.; Darve, C.

    2011-01-01

    The Horizontal Test Stand (HTS) SRF Cavity and Cryomodule 1 (CM1) of eight 9-cell, 1.3GHz SRF cavities are operating at Fermilab. For the cryogenic control system, how to hold liquid level constant in the cryostat by regulation of its Joule-Thompson JT-valve is very important after cryostat cool down to 2.0 K. The 72-cell cryostat liquid level response generally takes a long time delay after regulating its JT-valve; therefore, typical PID control loop should result in some cryostat parameter oscillations. This paper presents a type of PID parameter self-optimal and Time-Delay control method used to reduce cryogenic system parameters oscillation.

  11. Uranyl Nitrate Flow Loop

    International Nuclear Information System (INIS)

    Ladd-Lively, Jennifer L

    2008-01-01

    The objectives of the work discussed in this report were to: (1) develop a flow loop that would simulate the purified uranium-bearing aqueous stream exiting the solvent extraction process in a natural uranium conversion plant (NUCP); (2) develop a test plan that would simulate normal operation and disturbances that could be anticipated in an NUCP; (3) use the flow loop to test commercially available flowmeters for use as safeguards monitors; and (4) recommend a flowmeter for production-scale testing at an NUCP. There has been interest in safeguarding conversion plants because the intermediate products [uranium dioxide (UO 2 ), uranium tetrafluoride (UF 4 ), and uranium hexafluoride (UF 6 )] are all suitable uranium feedstocks for producing special nuclear materials. Furthermore, if safeguards are not applied virtually any nuclear weapons program can obtain these feedstocks without detection by the International Atomic Energy Agency (IAEA). Historically, IAEA had not implemented safeguards until the purified UF 6 product was declared as feedstock for enrichment plants. H. A. Elayat et al. provide a basic definition of a safeguards system: 'The function of a safeguards system on a chemical conversion plant is in general terms to verify that no useful nuclear material is being diverted to use in a nuclear weapons program'. The IAEA now considers all highly purified uranium compounds as candidates for safeguarding. DOE is currently interested in 'developing instruments, tools, strategies, and methods that could be of use to the IAEA in the application of safeguards' for materials found in the front end of the nuclear fuel cycle-prior to the production of the uranium hexafluoride or oxides that have been the traditional starting point for IAEA safeguards. Several national laboratories, including Oak Ridge, Los Alamos, Lawrence Livermore, and Brookhaven, have been involved in developing tools or techniques for safeguarding conversion plants. This study was sponsored by

  12. Loop Quantum Gravity.

    Science.gov (United States)

    Rovelli, Carlo

    2008-01-01

    The problem of describing the quantum behavior of gravity, and thus understanding quantum spacetime , is still open. Loop quantum gravity is a well-developed approach to this problem. It is a mathematically well-defined background-independent quantization of general relativity, with its conventional matter couplings. Today research in loop quantum gravity forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained so far are: (i) The computation of the spectra of geometrical quantities such as area and volume, which yield tentative quantitative predictions for Planck-scale physics. (ii) A physical picture of the microstructure of quantum spacetime, characterized by Planck-scale discreteness. Discreteness emerges as a standard quantum effect from the discrete spectra, and provides a mathematical realization of Wheeler's "spacetime foam" intuition. (iii) Control of spacetime singularities, such as those in the interior of black holes and the cosmological one. This, in particular, has opened up the possibility of a theoretical investigation into the very early universe and the spacetime regions beyond the Big Bang. (iv) A derivation of the Bekenstein-Hawking black-hole entropy. (v) Low-energy calculations, yielding n -point functions well defined in a background-independent context. The theory is at the roots of, or strictly related to, a number of formalisms that have been developed for describing background-independent quantum field theory, such as spin foams, group field theory, causal spin networks, and others. I give here a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  13. Loop Quantum Gravity

    Directory of Open Access Journals (Sweden)

    Rovelli Carlo

    2008-07-01

    Full Text Available The problem of describing the quantum behavior of gravity, and thus understanding quantum spacetime, is still open. Loop quantum gravity is a well-developed approach to this problem. It is a mathematically well-defined background-independent quantization of general relativity, with its conventional matter couplings. Today research in loop quantum gravity forms a vast area, ranging from mathematical foundations to physical applications. Among the most significant results obtained so far are: (i The computation of the spectra of geometrical quantities such as area and volume, which yield tentative quantitative predictions for Planck-scale physics. (ii A physical picture of the microstructure of quantum spacetime, characterized by Planck-scale discreteness. Discreteness emerges as a standard quantum effect from the discrete spectra, and provides a mathematical realization of Wheeler’s “spacetime foam” intuition. (iii Control of spacetime singularities, such as those in the interior of black holes and the cosmological one. This, in particular, has opened up the possibility of a theoretical investigation into the very early universe and the spacetime regions beyond the Big Bang. (iv A derivation of the Bekenstein–Hawking black-hole entropy. (v Low-energy calculations, yielding n-point functions well defined in a background-independent context. The theory is at the roots of, or strictly related to, a number of formalisms that have been developed for describing background-independent quantum field theory, such as spin foams, group field theory, causal spin networks, and others. I give here a general overview of ideas, techniques, results and open problems of this candidate theory of quantum gravity, and a guide to the relevant literature.

  14. External Otitis (Swimmer's Ear)

    Science.gov (United States)

    ... otitis. Fungal external otitis (otomycosis), typically caused by Aspergillus niger or Candida albicans, is less common. Boils are ... in the ear. Fungal external otitis caused by Aspergillus niger usually causes grayish black or yellow dots (called ...

  15. ExternE: Externalities of energy Vol. 2. Methodology

    International Nuclear Information System (INIS)

    Berry, J.; Holland, M.; Watkiss, P.

    1995-01-01

    This report describes the methodology used by the ExternE Project of the European Commission (DGXII) JOULE Programme for assessment of the external costs of energy. It is one of a series of reports describing analysis of nuclear, fossil and renewable fuel cycles for assessment of the externalities associated with electricity generation. Part I of the report deals with analysis of impacts, and Part II with the economic valuation of those impacts. Analysis is conducted on a marginal basis, to allow the effect of an incremental investment in a given technology to be quantified. Attention has been paid to the specificity of results with respect to the location of fuel cycle activities, the precise technologies used, and the type and source of fuel. The main advantages of this detailed approach are as follows: It takes full and proper account of the variability of impacts that might result from different power projects; It is more transparent than analysis based on hypothetically 'representative' cases for each of the different fuel cycles; It provides a framework for consistent comparison between fuel cycles. A wide variety of impacts have been considered. These include the effects of air pollution on the natural and human environment, consequences of accidents in the workplace, impacts of noise and visual intrusion on amenity, and the effects of climate change arising from the release of greenhouse gases. Wherever possible we have used the 'impact pathway' or 'damage function' approach to follow the analysis from identification of burdens (e.g. emissions) through to impact assessment and then valuation in monetary terms. This has required a detailed knowledge of the technologies involved, pollutant dispersion, analysis of effects on human and environmental health, and economics. In view of this the project brought together a multi-disciplinary team with experts from many European countries and the USA. The spatial and temporal ranges considered in the analysis are

  16. ASH External Web Portal (External Portal) -

    Data.gov (United States)

    Department of Transportation — The ASH External Web Portal is a web-based portal that provides single sign-on functionality, making the web portal a single location from which to be authenticated...

  17. 3-D numerical simulations of coronal loops oscillations

    Directory of Open Access Journals (Sweden)

    M. Selwa

    2009-10-01

    Full Text Available We present numerical results of 3-D MHD model of a dipole active region field containing a loop with a higher density than its surroundings. We study different ways of excitation of vertical kink oscillations by velocity perturbation: as an initial condition, and as an impulsive excitation with a pulse of a given position, duration, and amplitude. These properties are varied in the parametric studies. We find that the amplitude of vertical kink oscillations is significantly amplified in comparison to horizontal kink oscillations for exciters located centrally (symmetrically below the loop, but not if the exciter is located a significant distance to the side of the loop. This explains why the pure vertical kink mode is so rarely observed in comparison to the horizontally polarized one. We discuss the role of curved magnetic field lines and the pulse overlapping at one of the loop's footpoints in 3-D active regions (AR's on the excitation and the damping of slow standing waves. We find that footpoint excitation becomes more efficient in 3-D curved loops than in 2-D curved arcades and that slow waves can be excited within an interval of time that is comparable to the observed one wave-period due to the combined effect of the pulse inside and outside the loop. Additionally, we study the effect of AR topology on the excitation and trapping of loop oscillations. We find that a perturbation acting directly on a single loop excites oscillations, but results in an increased leakage compared to excitation of oscillations in an AR field by an external source.

  18. 3-D numerical simulations of coronal loops oscillations

    Directory of Open Access Journals (Sweden)

    M. Selwa

    2009-10-01

    Full Text Available We present numerical results of 3-D MHD model of a dipole active region field containing a loop with a higher density than its surroundings. We study different ways of excitation of vertical kink oscillations by velocity perturbation: as an initial condition, and as an impulsive excitation with a pulse of a given position, duration, and amplitude. These properties are varied in the parametric studies. We find that the amplitude of vertical kink oscillations is significantly amplified in comparison to horizontal kink oscillations for exciters located centrally (symmetrically below the loop, but not if the exciter is located a significant distance to the side of the loop. This explains why the pure vertical kink mode is so rarely observed in comparison to the horizontally polarized one. We discuss the role of curved magnetic field lines and the pulse overlapping at one of the loop's footpoints in 3-D active regions (AR's on the excitation and the damping of slow standing waves. We find that footpoint excitation becomes more efficient in 3-D curved loops than in 2-D curved arcades and that slow waves can be excited within an interval of time that is comparable to the observed one wave-period due to the combined effect of the pulse inside and outside the loop. Additionally, we study the effect of AR topology on the excitation and trapping of loop oscillations. We find that a perturbation acting directly on a single loop excites oscillations, but results in an increased leakage compared to excitation of oscillations in an AR field by an external source.

  19. The equivalent pore aspect ratio as a tool for pore type prediction in carbonate reservoirs

    OpenAIRE

    FOURNIER , François; Pellerin , Matthieu; Villeneuve , Quentin; Teillet , Thomas; Hong , Fei; Poli , Emmanuelle; Borgomano , Jean; Léonide , Philippe; Hairabian , Alex

    2018-01-01

    International audience; The equivalent pore aspect ratios (EPAR) provide a tool to detect pore types by combining P-and S-wave velocities, porosity, bulk density and mineralogical composition of carbonate rocks. The integration of laboratory measurements, well log data and petrographic analysis of 468 carbonate samples from various depositional and diagenetic settings (Lower Cretaceous pre-salt non-marine carbonates from offshore Brazil, Lower Cretaceous shallow-water platform carbonates from...

  20. A totally diverting loop colostomy.

    Science.gov (United States)

    Merrett, N. D.; Gartell, P. C.

    1993-01-01

    A technique is described where the distal limb of a loop colostomy is tied with nylon or polydioxanone. This ensures total faecal diversion and dispenses with the supporting rod, enabling early application of stoma appliances. The technique does not interfere with the traditional transverse closure of a loop colostomy. PMID:8379632

  1. Higher dimensional loop quantum cosmology

    International Nuclear Information System (INIS)

    Zhang, Xiangdong

    2016-01-01

    Loop quantum cosmology (LQC) is the symmetric sector of loop quantum gravity. In this paper, we generalize the structure of loop quantum cosmology to the theories with arbitrary spacetime dimensions. The isotropic and homogeneous cosmological model in n + 1 dimensions is quantized by the loop quantization method. Interestingly, we find that the underlying quantum theories are divided into two qualitatively different sectors according to spacetime dimensions. The effective Hamiltonian and modified dynamical equations of n + 1 dimensional LQC are obtained. Moreover, our results indicate that the classical big bang singularity is resolved in arbitrary spacetime dimensions by a quantum bounce. We also briefly discuss the similarities and differences between the n + 1 dimensional model and the 3 + 1 dimensional one. Our model serves as a first example of higher dimensional loop quantum cosmology and offers the possibility to investigate quantum gravity effects in higher dimensional cosmology. (orig.)

  2. Automated one-loop calculations with GoSam

    International Nuclear Information System (INIS)

    Cullen, Gavin; Greiner, Nicolas; Heinrich, Gudrun; Reiter, Thomas; Luisoni, Gionata; Mastrolia, Pierpaolo; Ossola, Giovanni; Tramontano, Francesco

    2012-01-01

    We present the program package GoSam which is designed for the automated calculation of one-loop amplitudes for multi-particle processes in renormalisable quantum field theories. The amplitudes, which are generated in terms of Feynman diagrams, can be reduced using either D-dimensional integrand-level decomposition or tensor reduction. GoSam can be used to calculate one-loop QCD and/or electroweak corrections to Standard Model processes and offers the flexibility to link model files for theories Beyond the Standard Model. A standard interface to programs calculating real radiation is also implemented. We demonstrate the flexibility of the program by presenting examples of processes with up to six external legs attached to the loop. (orig.)

  3. Automated One-Loop Calculations with GoSam

    CERN Document Server

    Cullen, Gavin; Heinrich, Gudrun; Luisoni, Gionata; Mastrolia, Pierpaolo; Ossola, Giovanni; Reiter, Thomas; Tramontano, Francesco

    2012-01-01

    We present the program package GoSam which is designed for the automated calculation of one-loop amplitudes for multi-particle processes in renormalisable quantum field theories. The amplitudes, which are generated in terms of Feynman diagrams, can be reduced using either D-dimensional integrand-level decomposition or tensor reduction. GoSam can be used to calculate one-loop QCD and/or electroweak corrections to Standard Model processes and offers the flexibility to link model files for theories Beyond the Standard Model. A standard interface to programs calculating real radiation is also implemented. We demonstrate the flexibility of the program by presenting examples of processes with up to six external legs attached to the loop.

  4. Closing global material loops

    DEFF Research Database (Denmark)

    Prosman, Ernst-Jan; Wæhrens, Brian Vejrum; Liotta, Giacomo

    2017-01-01

    where both enablers are absent, this study seeks to explore firm-level challenges of IS. We adopt an exploratory case study approach at a cement manufacturer who engages in cross-border IS without the support of external coordinators. Our research presents insights into two key areas of IS: 1) setting......-up the initial IS exchange and 2) improving the performance of existing IS exchanges. Moreover, our research provides initial insights into the underlying nature of the related firm-level challenges and explores how internal coordination between manufacturing and purchasing may or may not act as a substitute...

  5. Overview of Loop Heat Pipe Operation

    Science.gov (United States)

    Ku, Jentung

    1999-01-01

    Loop heat pipes (LHP's) are two-phase heat transfer devices that utilize the evaporation and condensation of a working fluid to transfer heat, and the capillary forces developed in the porous wicks to circulate the fluid. The LHP was first developed in the former Soviet Union in the early 1980s, about the same time that the capillary pumped loop (CPL) was developed in the United States. The LHP is known for its high pumping capability and robust operation mainly due to the use of fine-pored metal wicks and an integral evaporator/hydro-accumulator design. The LHP technology is rapidly gaining acceptance in aerospace community. It is the baseline design for thermal control of several spacecraft, including NASA's GLAS and Chemistry, ESA's ATLID, CNES' STENTOR, RKA's OBZOR, and several commercial satellites. Numerous LHP papers have been published since the mid-1980's. Most papers presented test results and discussions on certain specific aspects of the LHP operation. LHP's and CPL's show many similarities in their operating principles and performance characteristics. However, they also display significant differences in many aspects of their operation. Some of the LHP behaviors may seem strange or mysterious, even to experienced CPL practitioners. The main purpose of this paper is to present a systematic description of the operating principles and thermal-hydraulic behaviors of LHP'S. LHP operating principles will be given first, followed by a description of the thermal-hydraulics involved in LHP operation. Operating characteristics and important parameters affecting the LHP operation will then be described in detail. Peculiar behaviors of the LHP, including temperature hysteresis and temperature overshoot during start-up, will be explained. For simplicity, most discussions will focus upon LHP's with a single evaporator and a single condenser, but devices with multiple evaporators and condensers will also be discussed. Similarities and differences between LHP's and

  6. Enhancement of plasma generation in catalyst pores with different shapes

    Science.gov (United States)

    Zhang, Yu-Ru; Neyts, Erik C.; Bogaerts, Annemie

    2018-05-01

    Plasma generation inside catalyst pores is of utmost importance for plasma catalysis, as the existence of plasma species inside the pores affects the active surface area of the catalyst available to the plasma species for catalytic reactions. In this paper, the electric field enhancement, and thus the plasma production inside catalyst pores with different pore shapes is studied with a two-dimensional fluid model. The results indicate that the electric field will be significantly enhanced near tip-like structures. In a conical pore with small opening, the strongest electric field appears at the opening and bottom corners of the pore, giving rise to a prominent ionization rate throughout the pore. For a cylindrical pore, the electric field is only enhanced at the bottom corners of the pore, with lower absolute value, and thus the ionization rate inside the pore is only slightly enhanced. Finally, in a conical pore with large opening, the electric field is characterized by a maximum at the bottom of the pore, yielding a similar behavior for the ionization rate. These results demonstrate that the shape of the pore has a significantly influence on the electric field enhancement, and thus modifies the plasma properties.

  7. Pores and Void in Asclepiades’ Physical Theory

    Science.gov (United States)

    Leith, David

    2012-01-01

    This paper examines a fundamental, though relatively understudied, aspect of the physical theory of the physician Asclepiades of Bithynia, namely his doctrine of pores. My principal thesis is that this doctrine is dependent on a conception of void taken directly from Epicurean physics. The paper falls into two parts: the first half addresses the evidence for the presence of void in Asclepiades’ theory, and concludes that his conception of void was basically that of Epicurus; the second half focuses on the precise nature of Asclepiadean pores, and seeks to show that they represent void interstices between the primary particles of matter which are the constituents of the human body, and are thus exactly analogous to the void interstices between atoms within solid objects in Epicurus’ theory. PMID:22984299

  8. Active Pore Volume in Danish Peat Soils

    DEFF Research Database (Denmark)

    Forsmann, Ditte M.; Kjærgaard, Charlotte

    2012-01-01

    Phosphorus release within the soil matrix caused by the changed redox conditions due to re-establishment of a riparian wetland can be critical for the aquatic environment. However, phosphorous released in the soil will not always result in an immediate contribution to this loss to the aquatic...... environment. Lowland soils are primarily peat soils, and only a minor part of the total soil volume of peat soils is occupied by macropores (>30 µm). Since water primarily flows in these macropores, the majority of the soil matrix is bypassed (the immobile domain). Phosphorus released in the immobile domain...... is not actively transported out of the system, but is only transported via diffusion, which is a very slow process. Thus it is interesting to investigate the size of the active pore volume in peat soils. The hypothesis of this study is that the active pores volume of a peat soil can be expressed using bulk...

  9. One-loop tensor Feynman integral reduction with signed minors

    DEFF Research Database (Denmark)

    Fleischer, Jochem; Riemann, Tord; Yundin, Valery

    2012-01-01

    of the formalism is the immediate evaluation of complete contractions of the tensor integrals with external momenta. This leads to the problem of evaluating sums over products of signed minors with scalar products of chords. Chords are differences of external momenta. These sums may be evaluated analytically......We present an algebraic approach to one-loop tensor integral reduction. The integrals are presented in terms of scalar one- to four-point functions. The reduction is worked out explicitly until five-point functions of rank five. The numerical C++ package PJFry evaluates tensor coefficients in terms...

  10. LoopIng: a template-based tool for predicting the structure of protein loops.

    KAUST Repository

    Messih, Mario Abdel; Lepore, Rosalba; Tramontano, Anna

    2015-01-01

    ) and significant enhancements for long loops (11-20 residues). The quality of the predictions is robust to errors that unavoidably affect the stem regions when these are modeled. The method returns a confidence score for the predicted template loops and has

  11. Higgs bosons and QCD jets at two loops

    International Nuclear Information System (INIS)

    Koukoutsakis, Athanasios

    2003-04-01

    In this thesis we present techniques for the calculation of two-loop integrals contributing to the virtual corrections to physical processes with three on-shell and one off-shell external particles. First, we describe a set of basic tools that simplify the manipulation of complicated two-loop integrals. A technique for deriving helicity amplitudes with use of a set of projectors is demonstrated. Then we present an algorithm, introduced by Laporta, that helps reduce all possible two-loop integrals to a basic set of 'master integrals'. Subsequently, these master integrals are analytically evaluated by deriving and solving differential equations on the external scales of the process. Two-loop matrix elements and helicity amplitudes are calculated for the physical processes γ* → qq-barg and H → ggg respectively. Conventional Dimensional Regularization is used in the evaluation of Feynman diagrams. For both processes the infrared singular behavior is shown to agree with the one predicted by Catani. (author)

  12. Limiting Factors for External Reactor Vessel Cooling

    International Nuclear Information System (INIS)

    Cheung, F.B.

    2005-01-01

    The method of external reactor vessel cooling (ERVC) that involves flooding of the reactor cavity during a severe accident has been considered a viable means for in-vessel retention (IVR). For high-power reactors, however, there are some limiting factors that might adversely affect the feasibility of using ERVC as a means for IVR. In this paper, the key limiting factors for ERVC have been identified and critically discussed. These factors include the choking limit for steam venting (CLSV) through the bottleneck of the vessel/insulation structure, the critical heat flux (CHF) for downward-facing boiling on the vessel outer surface, and the two-phase flow instabilities in the natural circulation loop within the flooded cavity. To enhance ERVC, it is necessary to eliminate or relax these limiting factors. Accordingly, methods to enhance ERVC and thus improve margins for IVR have been proposed and demonstrated, using the APR1400 as an example. The strategy is based on using two distinctly different methods to enhance ERVC. One involves the use of an enhanced vessel/insulation design to facilitate steam venting through the bottleneck of the annular channel. The other involves the use of an appropriate vessel coating to promote downward-facing boiling. It is found that the use of an enhanced vessel/insulation design with bottleneck enlargement could greatly facilitate the process of steam venting through the bottleneck region as well as streamline the resulting two-phase motions in the annular channel. By selecting a suitable enhanced vessel/insulation design, not only the CLSV but also the CHF limits could be significantly increased. In addition, the problem associated with two-phase flow instabilities and flow-induced mechanical vibration could be minimized. It is also found that the use of vessel coatings made of microporous metallic layers could greatly facilitate downward-facing boiling on the vessel outer surface. With vessel coatings, the local CHF limits at

  13. Electron contribution to the muon anomalous magnetic moment at four loops

    International Nuclear Information System (INIS)

    Kurz, Alexander; Liu, Tao; Smirnov, Alexander V.; Smirnov, Vladimir A.; Humboldt-Universitaet, Berlin; Humboldt-Universitaet, Berlin; Steinhauser, Matthias

    2016-02-01

    We present results for the QED contributions to the anomalous magnetic moment of the muon containing closed electron loops. The main focus is on perturbative corrections at four-loop order where the external photon couples to the external muon. Furthermore, all four-loop contributions involving simultaneously a closed electron and tau loop are computed. In combination with our recent results on the light-by-light-type corrections the complete four-loop electron-loop contribution to the anomalous magnetic moment of the muon has been obtained with an independent calculation. Our calculation is based on an asymptotic expansion in the ratio of the electron and the muon mass and shows the importance of higher order terms in this ratio. We perform a detailed comparison with results available in the literature and find good numerical agreement. As a by-product we present analytic results for the on-shell muon mass and wave function renormalization constants at three-loop order including massive closed electron and tau loops, which we also calculated using the method of asymptotic expansion.

  14. A pore structure model for the gas transport property changes, initial oxidation rates and cumulative weight loss of AGR moderator graphite

    International Nuclear Information System (INIS)

    Johnson, P.A.V.

    1985-09-01

    A quantitative model has been developed for the gas transport property variation, cumulative weight loss and initial oxidation rates of AGR moderator graphite. The model utilises the theory of dynamic moments of the pore structure to calculate the changes in physical properties brought about by radiolytic corrosion taking place within the graphite porosity. In order to account for the behaviour of the initial rate curves, and the weight loss data obtained it is necessary to invoke the presence of a group of cylindrical pore and a group of small slab-shaped pores. The latter are methane depleted. This is in addition to the pore group involved in gas transport which is best represented by cylinders of mean radius 2.13 μm. The model satisfactorily predicts the experimental weight loss data obtained from experiments in the DIDO 6V3 and BFB loops. (author)

  15. Facial skin pores: a multiethnic study

    Directory of Open Access Journals (Sweden)

    Flament F

    2015-02-01

    Full Text Available Frederic Flament,1 Ghislain Francois,1 Huixia Qiu,2 Chengda Ye,2 Tomoo Hanaya,3 Dominique Batisse,3 Suzy Cointereau-Chardon,1 Mirela Donato Gianeti Seixas,4 Susi Elaine Dal Belo,4 Roland Bazin5 1Department of Applied Research and Development, L’Oreal Research and Innovation, Paris, France; 2Department of Applied Research and Development, L’Oreal Research and Innovation, Shanghai, People’s Republic of China; 3Department of Applied Research and Development, L’Oreal Research and Innovation, Tokyo, Japan; 4Department of Applied Research and Development, L’Oreal Research and Innovation, Rio de Janeiro, Brazil; 5RB Consult, Bievres, France Abstract: Skin pores (SP, as they are called by laymen, are common and benign features mostly located on the face (nose, cheeks, etc that generate many aesthetic concerns or complaints. Despite the prevalence of skin pores, related literature is scarce. With the aim of describing the prevalence of skin pores and anatomic features among ethnic groups, a dermatoscopic instrument, using polarized lighting, coupled to a digital camera recorded the major features of skin pores (size, density, coverage on the cheeks of 2,585 women in different countries and continents. A detection threshold of 250 µm, correlated to clinical scorings by experts, was input into a specific software to further allow for automatic counting of the SP density (N/cm2 and determination of their respective sizes in mm2. Integrating both criteria also led to establishing the relative part of the skin surface (as a percentage that is actually covered by SP on cheeks. The results showed that the values of respective sizes, densities, and skin coverage: 1 were recorded in all studied subjects; 2 varied greatly with ethnicity; 3 plateaued with age in most cases; and 4 globally reflected self-assessment by subjects, in particular those who self-declare having “enlarged pores” like Brazilian women. Inversely, Chinese women were clearly

  16. A Three-Dimensional Pore-Scale Model for Non-Wetting Phase Mobilization with Ferrofluid

    Science.gov (United States)

    Wang, N.; Prodanovic, M.

    2017-12-01

    Ferrofluid, a stable dispersion of paramagnetic nanoparticles in water, can generate a distributed pressure difference across the phase interface in an immiscible two-phase flow under an external magnetic field. In water-wet porous media, this non-uniform pressure difference may be used to mobilize the non-wetting phase, e.g. oil, trapped in the pores. Previous numerical work by Soares et al. of two-dimensional single-pore model showed enhanced non-wetting phase recovery with water-based ferrofluid under certain magnetic field directions and decreased recovery under other directions. However, the magnetic field selectively concentrates in the high magnetic permeability ferrofluid which fills the small corners between the non-wetting phase and the solid wall. The magnetic field induced pressure is proportional to the square of local magnetic field strength and its normal component, and makes a significant impact on the non-wetting phase deformation. The two-dimensional model omitted the effect of most of these corners and is not sufficient to compute the magnetic-field-induced pressure difference or to predict the non-wetting blob deformation. Further, it is not clear that 3D effects on magnetic field in an irregular geometry can be approximated in 2D. We present a three-dimensional immiscible two-phase flow model to simulate the deformation of a non-wetting liquid blob in a single pore filled with a ferrofluid under a uniform external magnetic field. The ferrofluid is modeled as a uniform single phase because the nanoparticles are 104 times smaller than the pore. The open source CFD solver library OpenFOAM is used for the simulations based on the volume of fluid method. Simulations are performed in a converging-diverging channel model on different magnetic field direction, different initial oil saturations, and different pore shapes. Results indicate that the external magnetic field always stretches the non-wetting blob away from the solid channel wall. A magnetic

  17. Mass upflows in 'post'-flare loops

    International Nuclear Information System (INIS)

    Forbes, T.G.; Priest, E.R.

    1983-01-01

    A self-consistent numerical model of a reconnecting magnetic field configuration similar to that occurring during the main-phase of two-ribbon flares is used to estimate the upflow caused by the fast-mode expansion of the magnetic field moving into the reconnection region. Such an expansion creates a field-aligned pressure gradient which accelerates plasma upward from the chromospheric base of magnetic field lines in the region external to the loops. The numerical results imply that the amount of mass sucked up in this way is even smaller than was previously estimated by Kopp and Pneuman who used a kinematic model. Therefore, some indirect mechanism (such as evaporation), which would probably derive its motive power from the thermal energy generated by the reconnection, is required to explain the large mass upflows inferred from observations. (orig.)

  18. Rogowski Loop design for NSTX

    International Nuclear Information System (INIS)

    McCormack, B.; Kaita, R.; Kugel, H.; Hatcher, R.

    2000-01-01

    The Rogowski Loop is one of the most basic diagnostics for tokamak operations. On the National Spherical Torus Experiment (NSTX), the plasma current Rogowski Loop had the constraints of the very limited space available on the center stack, 5,000 volt isolation, flexibility requirements as it remained a part of the Center Stack assembly after the first phase of operation, and a +120 C temperature requirement. For the second phase of operation, four Halo Current Rogowski Loops under the Center Stack tiles will be installed having +600 C and limited space requirements. Also as part of the second operational phase, up to ten Rogowski Loops will installed to measure eddy currents in the Passive Plate support structures with +350 C, restricted space, and flexibility requirements. This presentation will provide the details of the material selection, fabrication techniques, testing, and installation results of the Rogowski Loops that were fabricated for the high temperature operational and bakeout requirements, high voltage isolation requirements, and the space and flexibility requirements imposed upon the Rogowski Loops. In the future operational phases of NSTX, additional Rogowski Loops could be anticipated that will measure toroidal plasma currents in the vacuum vessel and in the Passive Plate assemblies

  19. Polyacrylamide sorption opportunity on interlayer and external pore surfaces of contaminant barrier clays.

    Science.gov (United States)

    Inyang, Hilary I; Bae, Sunyoung

    2005-01-01

    Physico-chemical interactions among polymer molecules in aqueous solution and clay mineralogical/textural characteristics influence the sorption of polymer molecules on clay barrier minerals. Amendment of potentially unstable barrier clays with aqueous polymers can improve barrier material resistance to environmental stresses during service. In this research, the ability of molecular coils of polyacrylamide (PAM) to overlap in solution and to enter interlayer space in Na-montmorillonite (specific surface=31.82+/-0.22 m2 g(-1)) and kaolinite (specific surface=18+/-2 m2 g(-1)) were analyzed theoretically and experimentally, using solution viscosity measurements, and X-ray diffractometry. Experimental data on two theoretical indices: relative size ratio (RSR); and molecular availability (Ma) that are formulated to scale polymer molecular sorption on clay interlayer, indicate that the sorption of PAM A (Mw=4000000) and PAM B (Mw=7000000) does not produce any significant change in the d-spacing of both clay minerals. Although the negative Ma values of -3.51 g l(-1) for PAM A and -3.88 g l(-1) for PAM B indicate high levels of entanglement of polymer molecular coils in solution, sorption data confirm that the entangled coils are still able to sorb onto Na-montmorillonite highly and kaolinite to a lesser extent.

  20. Two-loop hard-thermal-loop thermodynamics with quarks

    International Nuclear Information System (INIS)

    Andersen, Jens O.; Petitgirard, Emmanuel; Strickland, Michael

    2004-01-01

    We calculate the quark contribution to the free energy of a hot quark-gluon plasma to two-loop order using hard-thermal-loop (HTL) perturbation theory. All ultraviolet divergences can be absorbed into renormalizations of the vacuum energy and the HTL quark and gluon mass parameters. The quark and gluon HTL mass parameters are determined self-consistently by a variational prescription. Combining the quark contribution with the two-loop HTL perturbation theory free energy for pure glue we obtain the total two-loop QCD free energy. Comparisons are made with lattice estimates of the free energy for N f =2 and with exact numerical results obtained in the large-N f limit

  1. Radial distribution of ions in pores with a surface charge

    NARCIS (Netherlands)

    Stegen, J.H.G. van der; Görtzen, J.; Kuipers, J.A.M.; Hogendoorn, J.A.; Versteeg, G.F.

    2001-01-01

    A sorption model applicable to calculate the radial equilibrium concentrations of ions in the pores of ion-selective membranes with a pore structure is developed. The model is called the radial uptake model. Because the model is applied to a Nafion sulfonic layer with very small pores and the radial

  2. String breaking with Wilson loops?

    CERN Document Server

    Kratochvila, S; Kratochvila, Slavo; Forcrand, Philippe de

    2003-01-01

    A convincing, uncontroversial observation of string breaking, when the static potential is extracted from Wilson loops only, is still missing. This failure can be understood if the overlap of the Wilson loop with the broken string is exponentially small. In that case, the broken string ground state will only be seen if the Wilson loop is long enough. Our preliminary results show string breaking in the context of the 3d SU(2) adjoint static potential, using the L\\"uscher-Weisz exponential variance reduction approach. As a by-product, we measure the fundamental SU(2) static potential with improved accuracy and see clear deviations from Casimir scaling.

  3. BMN correlators by loop equations

    International Nuclear Information System (INIS)

    Eynard, Bertrand; Kristjansen, Charlotte

    2002-01-01

    In the BMN approach to N=4 SYM a large class of correlators of interest are expressible in terms of expectation values of traces of words in a zero-dimensional gaussian complex matrix model. We develop a loop-equation based, analytic strategy for evaluating such expectation values to any order in the genus expansion. We reproduce the expectation values which were needed for the calculation of the one-loop, genus one correction to the anomalous dimension of BMN-operators and which were earlier obtained by combinatorial means. Furthermore, we present the expectation values needed for the calculation of the one-loop, genus two correction. (author)

  4. ExternE: Externalities of energy Vol. 1. Summary

    International Nuclear Information System (INIS)

    Holland, M.; Berry, J.

    1995-01-01

    There is a growing requirement for policy analysts to take account of the environment in their decision making and to undertake the specified cost-benefit analysis. Within the European Union this is reflected in the 5th Environmental Action Programme, and the Commission's White Paper entitled 'Growth, competitiveness, employment and the ways forward to the 21st century'. This has led to a need for evaluation of environmental externalities. The ExternE Project commenced in 1991 as the European part of a collaborative study between the European Commission and the US Department of Energy. It aims to be the first systematic approach to the evaluation of external costs of a wide range of different fuel cycles. The project will result in an operational accounting framework for the quantification and monetarisation of priority environmental and other externalities. This framework will allow the calculation of the marginal external costs and benefits for specific power plants, at specific sites using specified technologies. There are three major phases in the project. Phase 1 was undertaken in collaboration with the US Department of Energy. In this phase the teams jointly developed the conceptual approach and methodology and shared scientific information for application to a number of fuel cycles. On the European side work concentrated on the nuclear and coal fuel cycles which together were expected to raise many of the fundamental issues in fuel cycle analysis. The project is currently nearing completion of Phase 2. During this phase the methodology has been applied to a wide range of different fossil, nuclear and renewable fuel cycles for power generation and energy conservation options. Also a series of National Implementation Programmes is underway in which the methodology and accounting framework are being applied to reference sites throughout Europe. In addition the general methodology is being extended to address the evaluation of externalities associated with

  5. Externalities of fuel cycles 'ExternE' project. Summary report

    International Nuclear Information System (INIS)

    Holland, M.; Berry, J.

    1994-01-01

    There is a growing requirement for policy analysts to take account of the environment in their decision making and to undertake the specified cost-benefit analysis. Within the European Union this is reflected in the 5th Environmental Action Programme, and the Commission's White Paper entitled 'Growth, competitiveness, employment and the ways forward to the 21st century'. This has led to a need for evaluation of environmental externalities. The ExternE Project commenced in 1991 as the European part of a collaborative study between the European Commission and the US Department of Energy. It aims to be the first systematic approach to the evaluation of external costs of a wide range of different fuel cycles. The project will result in an operational accounting framework for the quantification and monetarisation of priority environmental and other externalities. This framework will allow the calculation of the marginal external costs and benefits for specific power plants, at specific sites using specified technologies. There are three major phases in the project. Phase I was undertaken in collaboration with the US Department of Energy. In this phase the teams jointly developed the conceptual approach and methodology and shared scientific information for application to a number of fuel cycles. On the European side work concentrated on the nuclear and coal fuel cycles which together were expected to raise many of the fundamental issues in fuel cycle analysis. The project is currently nearing completion of Phase 2. During this phase the methodology has been applied to a wide range of different fossil, nuclear and renewable fuel cycles for power generation and energy conservation options. Also a series of National Implementation Programmes are underway in which the methodology and accounting framework are being applied to reference sites throughout Europe. In addition the general methodology is being extended to address the evaluation of externalities associated with

  6. A novel bio-safe phase separation process for preparing open-pore biodegradable polycaprolactone microparticles.

    Science.gov (United States)

    Salerno, Aurelio; Domingo, Concepción

    2014-09-01

    Open-pore biodegradable microparticles are object of considerable interest for biomedical applications, particularly as cell and drug delivery carriers in tissue engineering and health care treatments. Furthermore, the engineering of microparticles with well definite size distribution and pore architecture by bio-safe fabrication routes is crucial to avoid the use of toxic compounds potentially harmful to cells and biological tissues. To achieve this important issue, in the present study a straightforward and bio-safe approach for fabricating porous biodegradable microparticles with controlled morphological and structural features down to the nanometer scale is developed. In particular, ethyl lactate is used as a non-toxic solvent for polycaprolactone particles fabrication via a thermal induced phase separation technique. The used approach allows achieving open-pore particles with mean particle size in the 150-250 μm range and a 3.5-7.9 m(2)/g specific surface area. Finally, the combination of thermal induced phase separation and porogen leaching techniques is employed for the first time to obtain multi-scaled porous microparticles with large external and internal pore sizes and potential improved characteristics for cell culture and tissue engineering. Samples were characterized to assess their thermal properties, morphology and crystalline structure features and textural properties. Copyright © 2014 Elsevier B.V. All rights reserved.

  7. Mathematical modeling of deformation of a porous medium, considering its strengthening due to pore collapse

    Energy Technology Data Exchange (ETDEWEB)

    Sadovskii, V. M., E-mail: sadov@icm.krasn.ru; Sadovskaya, O. V., E-mail: o-sadov@icm.krasn.ru [Institute of Computational Modeling, SB RAS, Akademgorodok 50/44, 660036 Krasnoyarsk (Russian Federation)

    2015-10-28

    Based on the generalized rheological method, the mathematical model describing small deformations of a single-phase porous medium without regard to the effects of a fluid or gas in pores is constructed. The change in resistance of a material to the external mechanical impacts at the moment of pore collapse is taken into account by means of the von Mises–Schleicher strength condition. In order to consider irreversible deformations, alongside with the classical yield conditions by von Mises and Tresca– Saint-Venant, the special condition modeling the plastic loss of stability of a porous skeleton is used. The random nature of the pore size distribution is taken into account. It is shown that the proposed mathematical model satisfies the principles of thermodynamics of irreversible processes. Phenomenological parameters of the model are determined on the basis of the approximate calculation of the problem on quasi-static loading of a cubic periodicity cell with spherical voids. In the framework of the obtained model, the process of propagation of plane longitudinal waves of the compression in a homogenous porous medium, accompanied by the plastic deformation of a skeleton and the collapse of pores, is analyzed.

  8. Estimation of adsorption-induced pore pressure and confinement in a nanoscopic slit pore by a density functional theory

    Science.gov (United States)

    Grégoire, David; Malheiro, Carine; Miqueu, Christelle

    2018-03-01

    This study aims at characterising the adsorption-induced pore pressure and confinement in nanoscopic pores by molecular non-local density functional theory (DFT). Considering its important potential industrial applications, the adsorption of methane in graphitic slit pores has been selected as the test case. While retaining the accuracy of molecular simulations at pore scale, DFT has a very low computational cost that allows obtaining highly resolved pore pressure maps as a function of both pore width and thermodynamic conditions. The dependency of pore pressure on these parameters (pore width, pressure and temperature) is carefully analysed in order to highlight the effect of each parameter on the confined fluid properties that impact the solid matrix.

  9. Optical loop framing

    International Nuclear Information System (INIS)

    Kalibjian, R.; Chong, Y.P.; Prono, D.S.; Cavagnolo, H.R.

    1984-06-01

    The ATA provides an electron beam pulse of 70-ns duration at a 1-Hz rate. Our present optical diagnostics technique involve the imaging of the visible light generated by the beam incident onto the plant of a thin sheet of material. It has already been demonstrated that the light generated has a sufficiently fast temporal reponse in performing beam diagnostics. Notwithstanding possible beam emittance degradation due to scattering in the thin sheet, the observation of beam spatial profiles with relatively high efficiencies has provided data complementary to that obtained from beam wall current monitors and from various x-ray probes and other electrical probes. The optical image sensor consists of a gated, intensified television system. The gate pulse of the image intensifier can be appropriately delayed to give frames that are time-positioned from the head to the tail of the beam with a minimum gate time of 5-ns. The spatial correlation of the time frames from pulse to pulse is very good for a stable electron beam; however, when instabilities do occur, it is difficult to properly assess the spatial composition of the head and the tail of the beam on a pulse-to-pulse basis. Multiple gating within a pulse duration becomes desirable but cannot be performed because the recycle time (20-ms) of the TV system is much longer than the beam pulse. For this reason we have developed an optical-loop framing technique that will allow the recording of two frames within one pulse duration with our present gated/intensified TV system

  10. The effects of pressure, temperature, and pore water on velocities in Westerly granite. [for seismic wave propagation

    Science.gov (United States)

    Spencer, J. W., Jr.; Nur, A. M.

    1976-01-01

    A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining pressures and with independent control of the pore pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal pore water on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.

  11. External radiation surveillance

    International Nuclear Information System (INIS)

    Antonio, E.J.

    1995-01-01

    This section of the 1994 Hanford Site Environmental Report describes how external radiation was measured, how surveys were performed, and the results of these measurements and surveys. External radiation exposure rates were measured at locations on and off the Hanford Site using thermoluminescent dosimeters (TLD). External radiation and contamination surveys were also performed with portable radiation survey instruments at locations on and around the Hanford Site

  12. External radiation surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Antonio, E.J.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report describes how external radiation was measured, how surveys were performed, and the results of these measurements and surveys. External radiation exposure rates were measured at locations on and off the Hanford Site using thermoluminescent dosimeters (TLD). External radiation and contamination surveys were also performed with portable radiation survey instruments at locations on and around the Hanford Site.

  13. Dendritic silica nanomaterials (KCC-1) with fibrous pore structure possess high DNA adsorption capacity and effectively deliver genes in vitro.

    Science.gov (United States)

    Huang, Xiaoxi; Tao, Zhimin; Praskavich, John C; Goswami, Anandarup; Al-Sharab, Jafar F; Minko, Tamara; Polshettiwar, Vivek; Asefa, Tewodros

    2014-09-16

    The pore size and pore structure of nanoporous materials can affect the materials' physical properties, as well as potential applications in different areas, including catalysis, drug delivery, and biomolecular therapeutics. KCC-1, one of the newest members of silica nanomaterials, possesses fibrous, large pore, dendritic pore networks with wide pore entrances, large pore size distribution, spacious pore volume and large surface area--structural features that are conducive for adsorption and release of large guest molecules and biomacromolecules (e.g., proteins and DNAs). Here, we report the results of our comparative studies of adsorption of salmon DNA in a series of KCC-1-based nanomaterials that are functionalized with different organoamine groups on different parts of their surfaces (channel walls, external surfaces or both). For comparison the results of our studies of adsorption of salmon DNA in similarly functionalized, MCM-41 mesoporous silica nanomaterials with cylindrical pores, some of the most studied silica nanomaterials for drug/gene delivery, are also included. Our results indicate that, despite their relatively lower specific surface area, the KCC-1-based nanomaterials show high adsorption capacity for DNA than the corresponding MCM-41-based nanomaterials, most likely because of KCC-1's large pores, wide pore mouths, fibrous pore network, and thereby more accessible and amenable structure for DNA molecules to diffuse through. Conversely, the MCM-41-based nanomaterials adsorb much less DNA, presumably because their outer surfaces/cylindrical channel pore entrances can get blocked by the DNA molecules, making the inner parts of the materials inaccessible. Moreover, experiments involving fluorescent dye-tagged DNAs suggest that the amine-grafted KCC-1 materials are better suited for delivering the DNAs adsorbed on their surfaces into cellular environments than their MCM-41 counterparts. Finally, cellular toxicity tests show that the KCC-1-based

  14. LOW-FREQUENCY MAGNETIC FIELD SHIELDING BY A CIRCULAR PASSIVE LOOP AND CLOSED SHELLS

    Directory of Open Access Journals (Sweden)

    V.S. Grinchenko

    2016-05-01

    Full Text Available Purpose. To analyze the shielding factors for a circular passive loop and conductive closed shells placed in a homogeneous low-frequency magnetic field. Methodology. We have obtained simplified expressions for the shielding factors for a circular passive loop and a thin spherical shell. In addition, we have developed the numerical model of a thin cubical shell in a magnetic field, which allows exploring its shielding characteristics. Results. We have obtained dependences of the shielding factors for passive loops and shells on the frequency of the external field. Analytically determined frequency of the external magnetic field, below which field shielding of a passive loop is expedient to use, above which it is advisable to use a shielding shell.

  15. Energy conversion device with support member having pore channels

    Science.gov (United States)

    Routkevitch, Dmitri [Longmont, CO; Wind, Rikard A [Johnstown, CO

    2014-01-07

    Energy devices such as energy conversion devices and energy storage devices and methods for the manufacture of such devices. The devices include a support member having an array of pore channels having a small average pore channel diameter and having a pore channel length. Material layers that may include energy conversion materials and conductive materials are coaxially disposed within the pore channels to form material rods having a relatively small cross-section and a relatively long length. By varying the structure of the materials in the pore channels, various energy devices can be fabricated, such as photovoltaic (PV) devices, radiation detectors, capacitors, batteries and the like.

  16. Explicit evaluation of covariant one-loop four-point amplitude for open fermionic string

    International Nuclear Information System (INIS)

    Yamamoto, Hisashi; Nakazawa, Naohito.

    1986-11-01

    We carry out the explicit evaluation of the covariant one-loop amplitude with four massless external bosons for open fermionic string by the operator formalism. The resulting expression of the amplitude completely coincides with that of the light-cone new formalism for type-I superstring theory, providing the explicit demonstration for the one-loop equivalence of the old and new formalisms for the open superstring theory at the four-point interacting level. (author)

  17. Large momentum expansion of two-loop self-energy diagrams with arbitrary masses

    International Nuclear Information System (INIS)

    Davydychev, A.I.; Smirnov, V.A.; Tausk, J.B.

    1993-01-01

    For two-loop two-point diagrams with arbitrary masses, an algorithm to derive the asymptotic expansion at large external momentum squared is constructed. By using a general theorem on asymptotic expansions of Feynman diagrams, the coefficients of the expansion are calculated analytically. For some two-loop diagrams occurring in the Standard Model, comparison with results of numerical integration shows that our expansion works well in the region above the highest physical threshold. (orig.)

  18. Improved hard-thermal-loop effective action for hot QED and QCD

    International Nuclear Information System (INIS)

    Flechsig, F.; Rebhan, A.K.

    1995-01-01

    The conventional results for hard thermal loops, which are the building blocks of resummed perturbation theory in thermal field theories, have collinear singularities when external momenta are light-like. It is shown that by taking into account asymptotic thermal masses these singularities are removed. The thus improved hard thermal loops can be summarized by compact gauge-invariant effective actions, generalizing the ones found by Taylor and Wong, and by Braaten and Pisarski. (orig.)

  19. Silicon pore optics developments and status

    DEFF Research Database (Denmark)

    Bavdaz, Marcos; Wille, Eric; Wallace, Kotska

    2012-01-01

    Silicon Pore Optics (SPO) is a lightweight high performance X-ray optics technology being developed in Europe, driven by applications in observatory class high energy astrophysics missions. An example of such application is the former ESA science mission candidate ATHENA (Advanced Telescope...... for High Energy Astrophysics), which uses the SPO technology for its two telescopes, in order to provide an effective area exceeding 1 m2 at 1 keV, and 0.5 m2 at 6 keV, featuring an angular resolution of 10" or better [1 to 24]. This paper reports on the development activities led by ESA, and the status...

  20. ExternE: Externalities of energy Vol. 5. Nuclear

    International Nuclear Information System (INIS)

    Dreicer, M.; Tort, V.; Manen, P.

    1995-01-01

    Since the early 1970s, there has been increased interest in the environmental impacts that are caused by the generation of electricity. The comparative risk assessment studies at that time used mainly deaths and injuries as impact indicators. By the end of the 1980s studies changed to the assessment of the costs imposed on society and the environment that were not included in the market price of the energy produced, the so-called external costs. The preliminary studies that were published set the conceptual basis, grounded in neo-classical economics, for the valuation of the health and environmental impacts that could be assessed. As a consequence of the many questions raised by the methodologies employed by these early studies, Directorate General XII (DG XII) of the Commission of the European Communities established a collaborative research programme with the United States Department of Energy to identify an appropriate methodology for this type of work. Following the completion of this collaboration, the DG XII programme has continued as the ExternE project. The main objective of the work carried out at CEPN was to develop an impact pathway methodology for the nuclear fuel cycle that would be consistent with the methodologies developed for other fuel cycles, without loosing the nuclear-specific techniques required for a proper evaluation. In this way, comparisons between the different fuel cycles would be possible. This report presents the methodology and demonstration of the results in the context of the French nuclear fuel cycle. The United States team at Oak Ridge National Laboratory has previously issued a draft report on the results of their assessment. The French fuel cycle was broken down into 8 separate stages. Reference sites and 1990s technology were chosen to represent the total nuclear fuel cycle, as it exists today. In addition, the transportation of material between the sites was considered. The facilities are assessed for routine operation, except

  1. An Evaluation of Models of Bentonite Pore Water Evolution

    Energy Technology Data Exchange (ETDEWEB)

    Savage, David; Watson, Claire; Wilson, James (Quintessa Ltd, Henley-on-Thames (United Kingdom)); Arthur, Randy (Monitor Scientific LLC, Denver, CO (United States))

    2010-01-15

    set of calculations investigated disequilibrium between clay and pore fluid in laboratory squeezing cell tests involving pure water (pH = 9.0) or a 1M NaOH solution (pH = 12.1). Simulations carried out for 100 days (the same timescale as the experiments) showed that smectite remained far from equilibrium throughout, and that pH decreases due to smectite hydrolysis were trivial. However, extending the duration of the simulations to that required for clay-fluid equilibrium, necessitated timescales of 7 and 65 years for pure water and 1M NaOH, respectively, but again produced relatively minor pH decreases in the order of 0.1-0.2 pH units. If the (equilibrium) precipitation of secondary minerals was included in the simulations, then not only was the clay-fluid equilibration period extended dramatically (from 7 to 360 years for pure water, and from 65 to 2600 years for 1 M NaOH), but concomitant changes in pH were significant, decreasing from 9.0 to 8.6 (pure water) and from 12.1 to 9.0 (1 M NaOH). Repetition of these latter calculations using an alternative method of estimating the DELTAG{sub f}0 of smectite produced an increase in equilibration time for reaction with 1M NaOH from 2600 to 5000 years, highlighting the potential effects of the uncertainty in thermodynamic data for smectite. A final set of calculations was carried out to investigate both the time- and space-dependent variations in pore fluid composition in laboratory in diffusion experiments conducted for over 1200 days, initially with pure water and 'spiked' after 271 days with a Na-Ca-OH-Cl solution (pH = 11.7). Here, the sensitivity of the results to both variations in a number of parameters/ conditions (porosity, reaction rate of secondary minerals, the degree of mixing of the external fluid reservoirs in the experiments, the effective diffusion coefficient) and the inclusion/exclusion of key processes (clay hydrolysis, secondary mineral precipitation, ion exchange, clay edge protonation

  2. A comprehensive coordinate space renormalization of quantum electrodynamics to two-loop order

    International Nuclear Information System (INIS)

    Haagensen, P.E.; Latorre, J.I.

    1993-01-01

    We develop a coordinate space renormalization of massless quantum electrodynamics using the powerful method of differential renormalization. Bare one-loop amplitudes are finite at non-coincident external points, but do not accept a Fourier transform into momentum space. The method provides a systematic procedure to obtain one-loop renormalized amplitudes with finite Fourier transforms in strictly four dimensions without the appearance of integrals or the use of a regulator. Higher loops are solved similarly by renormalizing from the inner singularities outwards to the global one. We compute all one- and two-loop 1PI diagrams, run renormalization group equations on them. and check Ward identities. The method furthermore allows us to discern a particular pattern of renormalization under which certain amplitudes are seen not to contain higher-loop leading logarithms. We finally present the computation of the chiral triangle showing that differential renormalization emerges as a natural scheme to tackle γ 5 problems

  3. Performance characterization of silicon pore optics

    Science.gov (United States)

    Collon, M. J.; Kraft, S.; Günther, R.; Maddox, E.; Beijersbergen, M.; Bavdaz, M.; Lumb, D.; Wallace, K.; Krumrey, M.; Cibik, L.; Freyberg, M.

    2006-06-01

    The characteristics of the latest generation of assembled silicon pore X-ray optics are discussed in this paper. These very light, stiff and modular high performance pore optics (HPO) have been developed [1] for the next generation of astronomical X-ray telescopes, which require large collecting areas whilst achieving angular resolutions better than 5 arcseconds. The suitability of 12 inch silicon wafers as high quality optical mirrors and the automated assembly process are discussed elsewhere in this conference. HPOs with several tens of ribbed silicon plates are assembled by bending the plates into an accurate cylindrical shape and directly bonding them on top of each other. The achievable figure accuracy is measured during assembly and in test campaigns at X-ray testing facilities like BESSY-II and PANTER. Pencil beam measurements allow gaining information on the quality achieved by the production process with high spatial resolution. In combination with full beam illumination a complete picture of the excellent performance of these optics can be derived. Experimental results are presented and discussed in detail. The results of such campaigns are used to further improve the production process in order to match the challenging XEUS requirements [2] for imaging resolution and mass.

  4. Four-loop beta function in the Wess-Zumino model

    International Nuclear Information System (INIS)

    Avdeev, L.V.; Gorishny, S.G.

    1982-01-01

    A method for calculating momentum integrals, proposed by Chetyrkin and Tkachov, is applied to the foUr-loop calculations of the ν-function in the Wess-Zumino model. The main advantage of the used method is the existence of a relatively simple calculational algorithm that allows one to write an effective computer program on the system of analytical evaluations SCHOONSCHIP. Any three-loop integral with one external momentum can be computed by this program. The four-loop calculation in the WZ model is one of the first and simplest applications of the program

  5. The Asymptotic Expansion of Lattice Loop Integrals Around the Continuum Limit

    International Nuclear Information System (INIS)

    Becher, Thomas G

    2002-01-01

    We present a method of computing any one-loop integral in lattice perturbation theory by systematically expanding around its continuum limit. At any order in the expansion in the lattice spacing, the result can be written as a sum of continuum loop integrals in analytic regularization and a few genuine lattice integrals (''master integrals''). These lattice master integrals are independent of external momenta and masses and can be computed numerically. At the one-loop level, there are four master integrals in a theory with only bosonic fields, seven in HQET and sixteen in QED or QCD with Wilson fermions

  6. Exact two-loop vacuum polarization correction to the Lamb shift in hydrogenlike ions

    International Nuclear Information System (INIS)

    Plunien, G.; Beier, T.; Soff, G.

    1998-01-01

    We present a calculation scheme for the two-loop vacuum polarization correction of order α 2 to the Lamb shift of hydrogenlike high-Z atoms. The interaction with the external Coulomb field is taken into account to all orders in (Zα). By means of a modified potential approach the problem is reduced to the evaluation of effective one-loop vacuumpolarization potentials. An expression for the energy shift is deduced within the framework of partial wave decomposition performing appropriate subtractions. Exact results for the two-loop vacuum polarization contribution to the Lamb shift of K- and L-shell electron states in hydrogenlike lead and uranium are presented. (orig.)

  7. Remeasurement of thorium-230 in the pore water of Lacnor tailings

    International Nuclear Information System (INIS)

    Snodgrass, W.J.; Hart, D.R.

    1990-02-01

    A resampling of the Lacnor tailings management area was undertaken under a comprehensive quality assurance programme to establish levels of thorium 230 in pore water. A quality assurance programme was established for field sampling, sample handling and transport, and laboratory procedures and reporting. The external audit was used to evaluate analytical bias (on synthetic and field samples) and precision (by comparison of duplicate-duplicate results). Accuracy was assessed using synthetic samples. The external audit indicates that thorium 230 measurements by the main laboratory are not significantly different from the interlaboratory average within standard statistical limits. The results of the audit are based on measurement of environmental samples and known synthetic samples. This shows that present and previous measurements of thorium 230 varying from 0,1 to 150 Bq/L are valid data. A qualitative interpretation of the controls on thorium 230 geochemistry is provided in terms of control by thorium 232 and thorium dioxide(c) solid phase. Generic dose estimates for consumption of water containing thorium 230 are made but require refinement ot account for the actual pH of the drinking water and the degree of dilution of the pore water. The results of this project indicate that the performance of the laboratory that will conduct future thorium 230 measurements can be assessed satisfactorily with a smaller scale external laboratory assurance programme. The programme should include replicate samples sent to each laboratory and interlaboratory comparison on samples having high and low values of thorium 230

  8. [A photographic scale for evaluating facial pores and analysis of factors associated with pore widening in Chengdu].

    Science.gov (United States)

    Wang, Qing; Zhou, Cheng-xia; Meng, Hui-min; Wang, Xi; Li, Li

    2010-09-01

    To develop a photographic scale for grading widening of pores, and to identify the factors associated with pore widening. People with widened pores were recruited, with photographs taken on their nasal tips, nasal alas and cheeks. A questionnaire survey was undertaken by dermatologists to assess the severity of pore widening. A Cumulative Logit Model was established to identify factors that were associated with pore widening. A total of 115 people participated in the study and 562 photographs were taken. The photographic scale was highly consistent with the clinical judgment. Another 1011 residents aged from 18 to 70 years old in Chengdu were surveyed. The logit model revealed that facial pore widening were associated with gender, age, oily skin, sun protection and anti-aging cosmetic. The photographic scale is reliable and easy to use. Gender, age and oily skin are risk factors, and sun protection and anti-aging cosmetic are protective factors with related to pore widening.

  9. Loop equations in the theory of gravitation

    International Nuclear Information System (INIS)

    Makeenko, Yu.M.; Voronov, N.A.

    1981-01-01

    Loop-space variables (matrices of parallel transport) for the theory of gravitation are described. Loop equations, which are equivalent to the Einstein equations, are derived in the classical case. Loop equations are derived for gravity with cosmological constant as well. An analogy with the loop-space approach in Yang-Mills theory is discussed [ru

  10. Kalman Orbit Optimized Loop Tracking

    Science.gov (United States)

    Young, Lawrence E.; Meehan, Thomas K.

    2011-01-01

    Under certain conditions of low signal power and/or high noise, there is insufficient signal to noise ratio (SNR) to close tracking loops with individual signals on orbiting Global Navigation Satellite System (GNSS) receivers. In addition, the processing power available from flight computers is not great enough to implement a conventional ultra-tight coupling tracking loop. This work provides a method to track GNSS signals at very low SNR without the penalty of requiring very high processor throughput to calculate the loop parameters. The Kalman Orbit-Optimized Loop (KOOL) tracking approach constitutes a filter with a dynamic model and using the aggregate of information from all tracked GNSS signals to close the tracking loop for each signal. For applications where there is not a good dynamic model, such as very low orbits where atmospheric drag models may not be adequate to achieve the required accuracy, aiding from an IMU (inertial measurement unit) or other sensor will be added. The KOOL approach is based on research JPL has done to allow signal recovery from weak and scintillating signals observed during the use of GPS signals for limb sounding of the Earth s atmosphere. That approach uses the onboard PVT (position, velocity, time) solution to generate predictions for the range, range rate, and acceleration of the low-SNR signal. The low- SNR signal data are captured by a directed open loop. KOOL builds on the previous open loop tracking by including feedback and observable generation from the weak-signal channels so that the MSR receiver will continue to track and provide PVT, range, and Doppler data, even when all channels have low SNR.

  11. Analytic continuation of massless two-loop four-point functions

    International Nuclear Information System (INIS)

    Gehrmann, T.; Remiddi, E.

    2002-01-01

    We describe the analytic continuation of two-loop four-point functions with one off-shell external leg and internal massless propagators from the Euclidean region of space-like 1→3 decay to Minkowskian regions relevant to all 1→3 and 2→2 reactions with one space-like or time-like off-shell external leg. Our results can be used to derive two-loop master integrals and unrenormalized matrix elements for hadronic vector-boson-plus-jet production and deep inelastic two-plus-one-jet production, from results previously obtained for three-jet production in electron-positron annihilation. (author)

  12. A type of loop algebra and the associated loop algebras

    International Nuclear Information System (INIS)

    Tam Honwah; Zhang Yufeng

    2008-01-01

    A higher-dimensional twisted loop algebra is constructed. As its application, a new Lax pair is presented, whose compatibility gives rise to a Liouville integrable hierarchy of evolution equations by making use of Tu scheme. One of the reduction cases of the hierarchy is an analogous of the well-known AKNS system. Next, the twisted loop algebra, furthermore, is extended to another higher dimensional loop algebra, from which a hierarchy of evolution equations with 11-potential component functions is obtained, whose reduction is just standard AKNS system. Especially, we prove that an arbitrary linear combination of the four Hamiltonian operators directly obtained from the recurrence relations is still a Hamiltonian operator. Therefore, the hierarchy with 11-potential functions possesses 4-Hamiltonian structures. Finally, an integrable coupling of the hierarchy is worked out

  13. [External cephalic version].

    Science.gov (United States)

    Navarro-Santana, B; Duarez-Coronado, M; Plaza-Arranz, J

    2016-08-01

    To analyze the rate of successful external cephalic versions in our center and caesarean sections that would be avoided with the use of external cephalic versions. From January 2012 to March 2016 external cephalic versions carried out at our center, which were a total of 52. We collected data about female age, gestational age at the time of the external cephalic version, maternal body mass index (BMI), fetal variety and situation, fetal weight, parity, location of the placenta, amniotic fluid index (ILA), tocolysis, analgesia, and newborn weight at birth, minor adverse effects (dizziness, hypotension and maternal pain) and major adverse effects (tachycardia, bradycardia, decelerations and emergency cesarean section). 45% of the versions were unsuccessful and 55% were successful. The percentage of successful vaginal delivery in versions was 84% (4% were instrumental) and 15% of caesarean sections. With respect to the variables studied, only significant differences in birth weight were found; suggesting that birth weight it is related to the outcome of external cephalic version. Probably we did not find significant differences due to the number of patients studied. For women with breech presentation, we recommend external cephalic version before the expectant management or performing a cesarean section. The external cephalic version increases the proportion of fetuses in cephalic presentation and also decreases the rate of caesarean sections.

  14. Piezosurgery in External Dacryocystorhinostomy.

    Science.gov (United States)

    Czyz, Craig N; Fowler, Amy M; Dutton, Jonathan J; Cahill, Kenneth V; Foster, Jill A; Hill, Robert H; Everman, Kelly R; Nabavi, Cameron B

    Dacryocystorhinostomy (DCR) can be performed via an external or endoscopic approach. The use of ultrasonic or piezosurgery has been well described for endoscopic DCRs but is lacking for external DCRs. This study presents a case series of external DCRs performed using piezosurgery evaluating results and complications. Prospective, consecutive case series of patients undergoing primary external DCR for lacrimal drainage insufficiency. A standard external DCR technique was used using 1 of 2 piezosurgery systems for all bone incision. All patients received silicone intubation to the lacrimal system. Surgical outcome was measured in terms of patient-reported epiphora as follows: 1) complete resolution, 2) improvement >50%, 3) improvement 50% improvement. There were 4 patients (7%) who had <50% improvement. There was 1 (2%) intraoperative complication and 2 (4%) postoperative complications recorded. Piezourgery is a viable modality for performing external DCRs. The lack of surgical complications shows a potential for decreased soft tissues damage. The surgical success rate based on patient-reported epiphora is similar to those published for mechanical external DCRs. This modality may benefit the novice surgeon in the reduction of soft and mucosal tissue damage.

  15. Multiple Approaches to Characterizing Pore Structure in Natural Rock

    Science.gov (United States)

    Hu, Q.; Dultz, S.; Hamamoto, S.; Ewing, R. P.

    2012-12-01

    Microscopic characteristics of porous media - pore shape, pore-size distribution, and pore connectivity - control fluid flow and chemical transport, and are important in hydrogeological studies of rock formations in the context of energy, environmental, and water resources management. This presentation discusses various approaches to investigating pore structure of rock, with a particular focus on the Barnett Shale in north Texas used for natural gas production. Approaches include imbibition, tracer diffusion, porosimetry (MIP, vapor adsorption/desorption isotherms, NMR cyroporometry), and imaging (μ-tomography, Wood's metal impregnation, FIB/SEM). Results show that the Barnett Shale pores are predominantly in the nm size range, with a measured median pore-throat diameter of 6.5 nm. But small pore size is not the major contributor to low gas recovery; rather, the low gas diffusivity appears to be caused by low pore connectivity. Chemical diffusion in sparsely-connected pore spaces is not well described by classical Fickian behavior; anomalous behavior is suggested by percolation theory, and confirmed by results of imbibition tests. Our evolving complementary approaches, with their several advantages and disadvantages, provide a rich toolbox for tackling the pore structure characteristics in the Barnett Shale and other natural rocks.

  16. Tritium Management Loop Design Status

    Energy Technology Data Exchange (ETDEWEB)

    Rader, Jordan D. [ORNL; Felde, David K. [ORNL; McFarlane, Joanna [ORNL; Greenwood, Michael Scott [ORNL; Qualls, A L. [ORNL; Calderoni, Pattrick [Idaho National Laboratory (INL)

    2017-12-01

    This report summarizes physical, chemical, and engineering analyses that have been done to support the development of a test loop to study tritium migration in 2LiF-BeF2 salts. The loop will operate under turbulent flow and a schematic of the apparatus has been used to develop a model in Mathcad to suggest flow parameters that should be targeted in loop operation. The introduction of tritium into the loop has been discussed as well as various means to capture or divert the tritium from egress through a test assembly. Permeation was calculated starting with a Modelica model for a transport through a nickel window into a vacuum, and modifying it for a FLiBe system with an argon sweep gas on the downstream side of the permeation interface. Results suggest that tritium removal with a simple tubular permeation device will occur readily. Although this system is idealized, it suggests that rapid measurement capability in the loop may be necessary to study and understand tritium removal from the system.

  17. Criteria for saturated magnetization loop

    International Nuclear Information System (INIS)

    Harres, A.; Mikhov, M.; Skumryev, V.; Andrade, A.M.H. de; Schmidt, J.E.; Geshev, J.

    2016-01-01

    Proper estimation of magnetization curve parameters is vital in studying magnetic systems. In the present article, criteria for discrimination non-saturated (minor) from saturated (major) hysteresis loops are proposed. These employ the analysis of (i) derivatives of both ascending and descending branches of the loop, (ii) remanent magnetization curves, and (iii) thermomagnetic curves. Computational simulations are used in order to demonstrate their validity. Examples illustrating the applicability of these criteria to well-known real systems, namely Fe_3O_4 and Ni fine particles, are provided. We demonstrate that the anisotropy-field value estimated from a visual examination of an only apparently major hysteresis loop could be more than two times lower than the real one. - Highlights: • Proper estimation of hysteresis-loop parameters is vital in magnetic studies. • We propose criteria for discrimination minor from major hysteresis loops. • The criteria analyze magnetization, remanence and ZFC/FC curves and/or their derivatives. • Examples of their application on real nanoparticles systems are given. • Using the criteria could avoid twofold or bigger saturation-field underestimation errors.

  18. Criteria for saturated magnetization loop

    Energy Technology Data Exchange (ETDEWEB)

    Harres, A. [Departamento de Física, UFSM, Santa Maria, 97105-900 Rio Grande do Sul (Brazil); Mikhov, M. [Faculty of Physics, University of Sofia, 1164 Sofia (Bulgaria); Skumryev, V. [Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona (Spain); Departament de Física, Universitat Autònoma de Barcelona, 08193 Barcelona (Spain); Andrade, A.M.H. de; Schmidt, J.E. [Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil); Geshev, J., E-mail: julian@if.ufrgs.br [Departament de Física, Universitat Autònoma de Barcelona, 08193 Barcelona (Spain); Instituto de Física, UFRGS, Porto Alegre, 91501-970 Rio Grande do Sul (Brazil)

    2016-03-15

    Proper estimation of magnetization curve parameters is vital in studying magnetic systems. In the present article, criteria for discrimination non-saturated (minor) from saturated (major) hysteresis loops are proposed. These employ the analysis of (i) derivatives of both ascending and descending branches of the loop, (ii) remanent magnetization curves, and (iii) thermomagnetic curves. Computational simulations are used in order to demonstrate their validity. Examples illustrating the applicability of these criteria to well-known real systems, namely Fe{sub 3}O{sub 4} and Ni fine particles, are provided. We demonstrate that the anisotropy-field value estimated from a visual examination of an only apparently major hysteresis loop could be more than two times lower than the real one. - Highlights: • Proper estimation of hysteresis-loop parameters is vital in magnetic studies. • We propose criteria for discrimination minor from major hysteresis loops. • The criteria analyze magnetization, remanence and ZFC/FC curves and/or their derivatives. • Examples of their application on real nanoparticles systems are given. • Using the criteria could avoid twofold or bigger saturation-field underestimation errors.

  19. Effect of field deposition and pore size on Co/Cu barcode nanowires by electrodeposition

    International Nuclear Information System (INIS)

    Cho, Ji Ung; Wu, J.-H.; Min, Ji Hyun; Lee, Ju Hun; Liu, H.-L.; Kim, Young Keun

    2007-01-01

    We have studied the effect of an external magnetic field applied during electrodeposition of Co/Cu barcode nanowires in anodic aluminum oxide nanotemplates. The magnetic properties of the barcode nanowires were greatly enhanced for 50 nm pore diameter regardless of segment aspect ratio, but field deposition has little effect on the 200 nm nanowires. The magnetic improvement is correlated with a structural change, attributed to field modification of the growth habit of the barcode nanowires. A mechanism of growth subject to geometric confinement is proposed

  20. Effect of field deposition and pore size on Co/Cu barcode nanowires by electrodeposition

    Science.gov (United States)

    Cho, Ji Ung; Wu, Jun-Hua; Min, Ji Hyun; Lee, Ju Hun; Liu, Hong-Ling; Kim, Young Keun

    2007-03-01

    We have studied the effect of an external magnetic field applied during electrodeposition of Co/Cu barcode nanowires in anodic aluminum oxide nanotemplates. The magnetic properties of the barcode nanowires were greatly enhanced for 50 nm pore diameter regardless of segment aspect ratio, but field deposition has little effect on the 200 nm nanowires. The magnetic improvement is correlated with a structural change, attributed to field modification of the growth habit of the barcode nanowires. A mechanism of growth subject to geometric confinement is proposed.

  1. Laboratory isotopic behaviour (2H, 18O) of sediments pore water during evaporation

    International Nuclear Information System (INIS)

    Ciolzyk, A.; Bariac, T.; Klamecki, A.; Jusserand, C.

    1987-01-01

    Two bare sediments (sand and loam) wetted with water of known isotopic composition have been subjected to evaporation in laboratory conditions. An attempt of application of classical isotopic evaporation models for free waters with reducing reservoir has been made, the better fit implies: a)laminar conditions of the atmosphere in the sediment under evaporation; b) a similar isotopic composition of water vapor as the isotopic composition of the water vapor of the external atmosphere. Variation of ε K and δ V H implies a better knowledge of the complex mechanisms of the atmosphere behaviour in the pore path of porous media under evaporation [fr

  2. Pore structure in blended cement pastes

    DEFF Research Database (Denmark)

    Canut, Mariana Moreira Cavalcanti

    Supplementary cementitious materials (SCMs), such as slag and fly ash, are increasingly used as a substitute for Portland cement in the interests of improvement of engineering properties and sustainability of concrete. According to studies improvement of engineering properties can be explained by...... on assumptions of degree of reaction and product densities gave for plain cement pastes results comparable to MIP data.......Supplementary cementitious materials (SCMs), such as slag and fly ash, are increasingly used as a substitute for Portland cement in the interests of improvement of engineering properties and sustainability of concrete. According to studies improvement of engineering properties can be explained...... supplement each other. Cement pastes (w/b=0.4) with and without slag and fly ash cured at two moisture (sealed and saturated) and temperature (20 and 55ºC) conditions were used to investigate the combined impact of SCMs addition and curing on the pore structure of pastes cured up to two years. Also...

  3. Conservation agriculture effects on soil pore characteristics

    DEFF Research Database (Denmark)

    Munkholm, Lars Juhl; Abdollahi, Lotfollah

    ploughing to a depth of 20 cm (MP), harrowing to a depth of 8-10 cm (H) and direct drilling (D). Minimally disturbed core samples were taken at 4-8, 12-16 and 18-27 cm depths 11 years after experimental start. Water retention characteristics were measured for a range of matric potential ranging from -10......Conservation tillage in combination with crop rotation, residue management and cover crops are key components of conservation agriculture. A positive long-term effect of applying all components of conservation agriculture on soil structural quality is expected. However, there is a lack...... of quantitative knowledge to support this statement. This study examines the long-term effects of crop rotations, residue management and tillage on soil pore characteristics of two sandy loam soils in Denmark. Results are reported from a split plot field experiment rotation as main plot factor and tillage...

  4. Thermodynamics in Loop Quantum Cosmology

    International Nuclear Information System (INIS)

    Li, L.F.; Zhu, J.Y.

    2009-01-01

    Loop quantum cosmology (LQC) is very powerful to deal with the behavior of early universe. Moreover, the effective loop quantum cosmology gives a successful description of the universe in the semiclassical region. We consider the apparent horizon of the Friedmann-Robertson-Walker universe as a thermodynamical system and investigate the thermodynamics of LQC in the semiclassical region. The effective density and effective pressure in the modified Friedmann equation from LQC not only determine the evolution of the universe in LQC scenario but also are actually found to be the thermodynamic quantities. This result comes from the energy definition in cosmology (the Misner-Sharp gravitational energy) and is consistent with thermodynamic laws. We prove that within the framework of loop quantum cosmology, the elementary equation of equilibrium thermodynamics is still valid.

  5. Preferential flow from pore to landscape scales

    Science.gov (United States)

    Koestel, J. K.; Jarvis, N.; Larsbo, M.

    2017-12-01

    In this presentation, we give a brief personal overview of some recent progress in quantifying preferential flow in the vadose zone, based on our own work and those of other researchers. One key challenge is to bridge the gap between the scales at which preferential flow occurs (i.e. pore to Darcy scales) and the scales of interest for management (i.e. fields, catchments, regions). We present results of recent studies that exemplify the potential of 3-D non-invasive imaging techniques to visualize and quantify flow processes at the pore scale. These studies should lead to a better understanding of how the topology of macropore networks control key state variables like matric potential and thus the strength of preferential flow under variable initial and boundary conditions. Extrapolation of this process knowledge to larger scales will remain difficult, since measurement technologies to quantify macropore networks at these larger scales are lacking. Recent work suggests that the application of key concepts from percolation theory could be useful in this context. Investigation of the larger Darcy-scale heterogeneities that generate preferential flow patterns at the soil profile, hillslope and field scales has been facilitated by hydro-geophysical measurement techniques that produce highly spatially and temporally resolved data. At larger regional and global scales, improved methods of data-mining and analyses of large datasets (machine learning) may help to parameterize models as well as lead to new insights into the relationships between soil susceptibility to preferential flow and site attributes (climate, land uses, soil types).

  6. Phase transitions of fluids in heterogeneous pores

    Directory of Open Access Journals (Sweden)

    A. Malijevský

    2016-03-01

    Full Text Available We study phase behaviour of a model fluid confined between two unlike parallel walls in the presence of long range (dispersion forces. Predictions obtained from macroscopic (geometric and mesoscopic arguments are compared with numerical solutions of a non-local density functional theory. Two capillary models are considered. For a capillary comprising two (differently adsorbing walls we show that simple geometric arguments lead to the generalized Kelvin equation locating very accurately capillary condensation, provided both walls are only partially wet. If at least one of the walls is in complete wetting regime, the Kelvin equation should be modified by capturing the effect of thick wetting films by including Derjaguin's correction. Within the second model, we consider a capillary formed of two competing walls, so that one tends to be wet and the other dry. In this case, an interface localized-delocalized transition occurs at bulk two-phase coexistence and a temperature T*(L depending on the pore width L. A mean-field analysis shows that for walls exhibiting first-order wetting transition at a temperature T_{w}, T_{s} > T*(L > T_{w}, where the spinodal temperature Ts can be associated with the prewetting critical temperature, which also determines a critical pore width below which the interface localized-delocalized transition does not occur. If the walls exhibit critical wetting, the transition is shifted below Tw and for a model with the binding potential W(l=A(Tl-2+B(Tl-3+..., where l is the location of the liquid-gas interface, the transition can be characterized by a dimensionless parameter κ=B/(AL, so that the fluid configuration with delocalized interface is stable in the interval between κ=-2/3 and κ ~ -0.23.

  7. Automated External Defibrillator

    Science.gov (United States)

    ... leads to a 10 percent reduction in survival. Training To Use an Automated External Defibrillator Learning how to use an AED and taking a CPR (cardiopulmonary resuscitation) course are helpful. However, if trained ...

  8. Energy policy and externalities

    International Nuclear Information System (INIS)

    Bertel, E.; Fraser, P.

    2002-01-01

    External costs of energy have been assessed in a number of authoritative and reliable studies based upon widely accepted methodologies such as life cycle analysis (LCA). However, although those costs are recognised by most stakeholders and decision makers, results from analytical work on externalities and LCA studies are seldom used in policy making. The International Energy Agency (IEA) and the Nuclear Energy Agency (NEA) convened a joint workshop in November 2001 to offer experts and policy makers an opportunity to present state-of-the-art results from analytical work on externalities and debate issues related to the relevance of external costs and LCA for policy-making purposes. The findings from the workshop highlight the need for further work in the field and the potential rote of international organisations like the IEA and the NEA in this context. (authors)

  9. Externally Verifiable Oblivious RAM

    Directory of Open Access Journals (Sweden)

    Gancher Joshua

    2017-04-01

    Full Text Available We present the idea of externally verifiable oblivious RAM (ORAM. Our goal is to allow a client and server carrying out an ORAM protocol to have disputes adjudicated by a third party, allowing for the enforcement of penalties against an unreliable or malicious server. We give a security definition that guarantees protection not only against a malicious server but also against a client making false accusations. We then give modifications of the Path ORAM [15] and Ring ORAM [9] protocols that meet this security definition. These protocols both have the same asymptotic runtimes as the semi-honest original versions and require the external verifier to be involved only when the client or server deviates from the protocol. Finally, we implement externally verified ORAM, along with an automated cryptocurrency contract to use as the external verifier.

  10. [Influence of surface chemical properties and pore structure characteristics of activated carbon on the adsorption of nitrobenzene from aqueous solution].

    Science.gov (United States)

    Liu, Shou-Xin; Chen, Xi; Zhang, Xian-Quan

    2008-05-01

    Commercial activated carbon was treated by HNO3 oxidation and then subsequently heat treated under N2 atmosphere. Effect of surface chemical properties and pore structure on the adsorption performance of nitrobenzene was investigated. N2/77K adsorption isotherm and scanning electron microscopy (SEM) were used to characterize the pore structure and surface morphology of carbon. Boehm titration, Fourier transform infrared spectroscopy (FTIR), the point of zero charge (pH(PZC)) measurement and elemental analysis were used to characterize the surface properties. The results reveal that HNO3 oxidation can modify the surface chemical properties, increase the number of acidic surface oxygen-containing groups and has trivial effect on the pore structure of carbon. Further heat treatment can cause the decomposition of surface oxygen-containing groups, and increase the external surface area and the number of mesopores. Adsorption capacity of nitrobenzene on AC(NO-T), AC(raw) and AC(NO) was 1011.31, 483.09 and 321.54 mg x g(-1), respectively. Larger external surface area and the number of meso-pores, together with the less acid surface oxygen-containing groups were the main reason for the larger adsorption capacity AC(NO-T).

  11. High pressure experimental water loop

    International Nuclear Information System (INIS)

    Grenon, M.

    1958-01-01

    A high pressure experimental water loop has been made for studying the detection and evolution of cladding failure in a pressurized reactor. The loop has been designed for a maximum temperature of 360 deg. C, a maximum of 160 kg/cm 2 and flow rates up to 5 m 3 /h. The entire loop consists of several parts: a main circuit with a canned rotor circulation pump, steam pressurizer, heating tubes, two hydro-cyclones (one de-gasser and one decanter) and one tubular heat exchanger; a continuous purification loop, connected in parallel, comprising pressure reducing valves and resin pots which also allow studies of the stability of resins under pressure, temperature and radiation; following the gas separator is a gas loop for studying the recombination of the radiolytic gases in the steam phase. The preceding circuits, as well as others, return to a low pressure storage circuit. The cold water of the low pressure storage flask is continuously reintroduced into the high pressure main circuit by means of a return pump at a maximum head of 160 kg /cm 2 , and adjusted to the pressurizer level. This loop is also a testing bench for the tight high pressure apparatus. The circulating pump and the connecting flanges (Oak Ridge type) are water-tight. The feed pump and the pressure reducing valves are not; the un-tight ones have a system of leak recovery. To permanently check the tightness the circuit has been fitted with a leak detection system (similar to the HRT one). (author) [fr

  12. Pore structure of natural and regenerated soil aggregates

    DEFF Research Database (Denmark)

    Naveed, Muhammad; Arthur, Emmanuel; de Jonge, Lis Wollesen

    2014-01-01

    Quantitative characterization of aggregate pore structure can reveal the evolution of aggregates under different land use and management practices and their effects on soil processes and functions. Advances in X-ray Computed Tomography (CT) provide powerful means to conduct such characterization....... This study examined aggregate pore structure of three differently managed same textured Danish soils (mixed forage cropping, MFC; mixed cash cropping, MCC; cereal cash cropping, CCC) for (i) natural aggregates, and (ii) aggregates regenerated after 20 months of incubation. In total, 27 aggregates (8-16 mm...... pore diameter of 200 and 170 Hm, respectively. Pore shape analysis indicated that CCC and MFC aggregates had an abundance of rounded and elongated pores, respectively, and those of MCC were in-between CCC and MFC. Aggregate pore structure development in the lysimeters was nearly similar irrespective...

  13. Characteristics of Pore Structure and Fractal Dimension of Isometamorphic Anthracite

    Directory of Open Access Journals (Sweden)

    Di Gao

    2017-11-01

    Full Text Available The geologic conditions of No. 3 coal seams are similar to Sihe and Zhaozhuang Collieries, however, the gas production is significantly different. To better understand the effect of pores, by means of experimental measurements and quantitative analysis, the pore properties of high-rank isometamorphic anthracite were thoroughly studied. Our study showed that the pore structures were predominantly adsorptive, accounting for more than 88% of the specific surface area. The coal pores showed typical three-stage fractal characteristics at boundary points of 1 nm and 9 nm (7 nm of coal samples from Zhaozhuang Colliery, and the fractal dimension with 1–9 nm (or 1–7 nm, as being significantly larger than those measured outside the given ranges. Pores in samples from Sihe Colliery were mainly open spherical or ellipsoidal pores in shape; conversely, those from Zhaozhuang Colliery were mainly Y-shaped, V-shaped, or ‘ink-bottle’ type.

  14. Preparation of micro-pored silicone elastomer through radiation crosslinking

    International Nuclear Information System (INIS)

    Gao Xiaoling; Gu Mei; Xie Xubing; Huang Wei

    2013-01-01

    The radiation crosslinking was adopted to prepare the micro-pored silicone elastomer, which was performed by vulcanization and foaming respectively. Radiation crosslinking is a new method to prepare micro-pored material with high performance by use of radiation technology. Silicon dioxide was used as filler, and silicone elastomer was vulcanized by electron beams, then the micro-pored material was made by heating method at a high temperature. The effects of absorbed dose and filler content on the performance and morphology were investigated. The structure and distribution of pores were observed by SEM. The results show that the micro-pored silicon elastomer can be prepared successfully by controlling the absorbed dose and filler content. It has a smooth surface similar to a rubber meanwhile the pores are round and unconnected to each other with the minimum size of 14 μm. And the good mechanical performance can be suitable for further uses. (authors)

  15. Integrable systems and loop coproducts

    International Nuclear Information System (INIS)

    Musso, Fabio

    2010-01-01

    We present a generalization of a framework for the construction of classical integrable systems that we call loop coproduct formulation (Musso 2010 J. Phys. A: Math. Theor. 43 434026). In this paper, the loop coproduct formulation includes systems of Gelfand-Tsetlin type, the linear r-matrix formulation, the Sklyanin algebras, the reflection algebras, the coalgebra symmetry approach and some of its generalizations as particular cases, showing that all these apparently different approaches have a common algebraic origin. On the other hand, all these subcases do not exhaust the domain of applicability of this new technique, so that new possible directions of investigation do naturally emerge in this framework.

  16. Perturbations in loop quantum cosmology

    International Nuclear Information System (INIS)

    Nelson, W; Agullo, I; Ashtekar, A

    2014-01-01

    The era of precision cosmology has allowed us to accurately determine many important cosmological parameters, in particular via the CMB. Confronting Loop Quantum Cosmology with these observations provides us with a powerful test of the theory. For this to be possible, we need a detailed understanding of the generation and evolution of inhomogeneous perturbations during the early, quantum gravity phase of the universe. Here, we have described how Loop Quantum Cosmology provides a completion of the inflationary paradigm, that is consistent with the observed power spectra of the CMB

  17. LISA Pathfinder: OPD loop characterisation

    Science.gov (United States)

    Born, Michael; LPF Collaboration

    2017-05-01

    The optical metrology system (OMS) of the LISA Pathfinder mission is measuring the distance between two free-floating test masses with unprecedented precision. One of the four OMS heterodyne interferometers reads out the phase difference between the reference and the measurement laser beam. This phase from the reference interferometer is common to all other longitudinal interferometer read outs and therefore subtracted. In addition, the phase is fed back via the digital optical pathlength difference (OPD) control loop to keep it close to zero. Here, we analyse the loop parameters and compare them to on-ground measurement results.

  18. LOOP: engineering marvel, economic calamity

    Energy Technology Data Exchange (ETDEWEB)

    Brossard, E B

    1985-01-01

    The Louisiana Offshore Oil Port (LOOP) is the first superport built in the Lower 48. The United States was the only major oil-importing country that did not have a superport, and therefore, could not offload very large crude carriers (VLCCs). Unfortunately, a number of factors changed after it was decided to build LOOP, and these, plus the onerous provisions of the Deepwater Ports Act of 1974, which authorized superports, prevented LOOP from operating economically. LOOP's facilities consist of an offshore platform complex with three single-point-mooring (SPM) system buoys, 19 miles offshore in 110 feet of water, as well as a 32-million-barrel storage terminal 31 miles inland at Clovelly Salt Dome, and connecting pipelines offshore and onshore. By the time LOOP was started-up in May 1981, demand for oil had declined, because of rises in the price of oil, and the source of US oil imports had shifted back to the western hemisphere, away from the eastern hemisphere, closer to the US. The refinery mix in the US also changed, because of up-grading of a number of big refineries, which further reduced demand and made heavier crudes from countries like Mexico and Venezuela more economical. Because of reduced oil imports and shorter hauls, oil shippers started using or continued to use smaller tankers. Smaller tankers are not economical for LOOP, nor do they need LOOP. The start-up of the Trans-Alaska Pipeline System (TAPS) in mid-1977 backed out 1.5 million bd/sup -1/ of foreign imports. TAPS' capacity coincides with LOOP's offloading capacity of 1.4 million bd/sup -1/. US decontrol of domestic crude in 1981 and increased drilling, plus general energy conservation further reduced US oil imports. US consumption declined to 15.1 million bd/sup -1/ in 1983, from 18.8 million bd/sup -1/ in 1978. This award-winning superport needed federal decontrol and increased oil imports along with more VLCCs, in order to operate economically.

  19. Fermions and loops on graphs: I. Loop calculus for determinants

    International Nuclear Information System (INIS)

    Chernyak, Vladimir Y; Chertkov, Michael

    2008-01-01

    This paper is the first in a series devoted to evaluation of the partition function in statistical models on graphs with loops in terms of the Berezin/fermion integrals. The paper focuses on a representation of the determinant of a square matrix in terms of a finite series, where each term corresponds to a loop on the graph. The representation is based on a fermion version of the loop calculus, previously introduced by the authors for graphical models with finite alphabets. Our construction contains two levels. First, we represent the determinant in terms of an integral over anti-commuting Grassmann variables, with some reparametrization/gauge freedom hidden in the formulation. Second, we show that a special choice of the gauge, called the BP (Bethe–Peierls or belief propagation) gauge, yields the desired loop representation. The set of gauge fixing BP conditions is equivalent to the Gaussian BP equations, discussed in the past as efficient (linear scaling) heuristics for estimating the covariance of a sparse positive matrix

  20. A virtual closed loop method for closed loop identification

    NARCIS (Netherlands)

    Agüero, J.C.; Goodwin, G.C.; Hof, Van den P.M.J.

    2011-01-01

    Indirect methods for the identification of linear plant models on the basis of closed loop data are based on the use of (reconstructed) input signals that are uncorrelated with the noise. This generally requires exact (linear) controller knowledge. On the other hand, direct identification requires

  1. Phase transitions in single macromolecules: Loop-stretch transition versus loop adsorption transition in end-grafted polymer chains

    Science.gov (United States)

    Zhang, Shuangshuang; Qi, Shuanhu; Klushin, Leonid I.; Skvortsov, Alexander M.; Yan, Dadong; Schmid, Friederike

    2018-01-01

    We use Brownian dynamics simulations and analytical theory to compare two prominent types of single molecule transitions. One is the adsorption transition of a loop (a chain with two ends bound to an attractive substrate) driven by an attraction parameter ɛ and the other is the loop-stretch transition in a chain with one end attached to a repulsive substrate, driven by an external end-force F applied to the free end. Specifically, we compare the behavior of the respective order parameters of the transitions, i.e., the mean number of surface contacts in the case of the adsorption transition and the mean position of the chain end in the case of the loop-stretch transition. Close to the transition points, both the static behavior and the dynamic behavior of chains with different length N are very well described by a scaling ansatz with the scaling parameters (ɛ - ɛ*)Nϕ (adsorption transition) and (F - F*)Nν (loop-stretch transition), respectively, where ϕ is the crossover exponent of the adsorption transition and ν is the Flory exponent. We show that both the loop-stretch and the loop adsorption transitions provide an exceptional opportunity to construct explicit analytical expressions for the crossover functions which perfectly describe all simulation results on static properties in the finite-size scaling regime. Explicit crossover functions are based on the ansatz for the analytical form of the order parameter distributions at the respective transition points. In contrast to the close similarity in equilibrium static behavior, the dynamic relaxation at the two transitions shows qualitative differences, especially in the strongly ordered regimes. This is attributed to the fact that the surface contact dynamics in a strongly adsorbed chain is governed by local processes, whereas the end height relaxation of a strongly stretched chain involves the full spectrum of Rouse modes.

  2. Coarse and fine root plants affect pore size distributions differently

    OpenAIRE

    Bodner, G.; Leitner, D.; Kaul, H.-P.

    2014-01-01

    Aims Small scale root-pore interactions require validation of their impact on effective hydraulic processes at the field scale. Our objective was to develop an interpretative framework linking root effects on macroscopic pore parameters with knowledge at the rhizosphere scale. Methods A field experiment with twelve species from different families was conducted. Parameters of Kosugi?s pore size distribution (PSD) model were determined inversely from tension infiltrometer data. Measured root tr...

  3. Response of the primary piping loop to an HCDA

    International Nuclear Information System (INIS)

    Chang, Y.W.; Moneim, M.T.A.; Wang, C.Y.; Gvildys, J.

    1975-01-01

    The paper describes a method for analyzing the response of the primary piping loop that consists of straight pipes, elbows, and other components connected in series and subject to hypothetical core disruptive accident (HCDA) loads at both ends of the loop. The complete hydrodynamic equations in two-dimensions, that include both the nonlinear convective and viscous dissipation terms are used for the fluid dynamics together with the implicit ICE technique. The external walls of the pipes and components are treated as thin shells in which the analysis accounts for the membrane and bending strength of the wall, elastic-plastic material behavior, as well as large deformation under the effect of transient loading conditions. In the straight pipes, the flow is assumed to be axisymmetric; in the elbow regions, the two dimensions considered are the r and theta directions. The flow in the other components is also assumed to be axisymmetric; the components are modeled as a circular cylinder, in which the radius of the cylinder can be varied to conform with the outside shape of the component and the flow area inside can be changed independently from the outside shape. However, they must remain axially symmetric. The method is applied to a piping loop which consists of six elastic-plastic pipes and five rigid elbows connected in series and subjected to pressure pulses at both ends of the loop

  4. Two-loop feed water control system in BWR plants

    International Nuclear Information System (INIS)

    Omori, Takashi; Watanabe, Takao; Hirose, Masao.

    1982-01-01

    In the process of the start-up and shutdown of BWR plants, the operation of changing over feed pumps corresponding to plant output is performed. Therefore, it is necessary to develop the automatic changeover system for feed pumps, which minimizes the variation of water level in reactors and is easy to operate. The three-element control system with the water level in reactors, the flow rate of main steam and the flow rate of feed water as the input is mainly applied, but long time is required for the changeover of feed pumps. The two-loop feed control system can control simultaneously two pumps being changed over, therefore it is suitable to the automatic changeover control system for feed pumps. Also it is excellent for the control of the recirculating valves of feed pumps. The control characteristics of the two-loop feed water control system against the external disturbance which causes the variation of water level in reactors were examined. The results of analysis by simulation are reported. The features of the two-loop feed water control system, the method of simulation and the evaluation of the two-loop feed water control system are described. Its connection with a digital feed water recirculation control system is expected. (Kako, I.)

  5. Permeability changes induced by microfissure closure and opening in tectonized materials. Effect on slope pore pressure regime.

    Science.gov (United States)

    De la Fuente, Maria; Vaunat, Jean; Pedone, Giuseppe; Cotecchia, Federica; Sollecito, Francesca; Casini, Francesca

    2015-04-01

    Tectonized clays are complex materials characterized by several levels of structures that may evolve during load and wetting/drying processes. Some microstructural patterns, as microfissures, have a particular influence on the value of permeability which is one of the main factors controlling pore pressure regime in slopes. In this work, the pore pressure regime measured in a real slope of tectonized clay in Southern Italy is analyzed by a numerical model that considers changes in permeability induced by microfissure closure and opening during the wetting and drying processes resulting from climatic actions. Permeability model accounts for the changes in Pore Size Distribution observed by Microscopy Intrusion Porosimetry. MIP tests are performed on representative samples of ground in initial conditions ("in situ" conditions) and final conditions (deformed sample after applying a wetting path that aims to reproduce the saturation of the soil under heavy rains). The resulting measurements allow for the characterization at microstructural level of the soil, identifying the distribution of dominant families pores in the sample and its evolution under external actions. Moreover, comparison of pore size density functions allows defining a microstructural parameter that depends on void ratio and degree of saturation and controls the variation of permeability. Model has been implemented in a thermo-hydro-mechanical code provided with a special boundary condition for climatic actions. Tool is used to analyze pore pressure measurements obtained in the tectonized clay slope. Results are analyzed at the light of the effect that permeability changes during wetting and drying have on the pore pressure regime.

  6. The effect of scaffold pore size in cartilage tissue engineering.

    Science.gov (United States)

    Nava, Michele M; Draghi, Lorenza; Giordano, Carmen; Pietrabissa, Riccardo

    2016-07-26

    The effect of scaffold pore size and interconnectivity is undoubtedly a crucial factor for most tissue engineering applications. The aim of this study was to examine the effect of pore size and porosity on cartilage construct development in different scaffolds seeded with articular chondrocytes. We fabricated poly-L-lactide-co-trimethylene carbonate scaffolds with different pore sizes, using a solvent-casting/particulate-leaching technique. We seeded primary bovine articular chondrocytes on these scaffolds, cultured the constructs for 2 weeks and examined cell proliferation, viability and cell-specific production of cartilaginous extracellular matrix proteins, including GAG and collagen. Cell density significantly increased up to 50% with scaffold pore size and porosity, likely facilitated by cell spreading on the internal surface of bigger pores, and by increased mass transport of gases and nutrients to cells, and catabolite removal from cells, allowed by lower diffusion barriers in scaffolds with a higher porosity. However, both the cell metabolic activity and the synthesis of cartilaginous matrix proteins significantly decreased by up to 40% with pore size. We propose that the association of smaller pore diameters, causing 3-dimensional cell aggregation, to a lower oxygenation caused by a lower porosity, could have been the condition that increased the cell-specific synthesis of cartilaginous matrix proteins in the scaffold with the smallest pores and the lowest porosity among those tested. In the initial steps of in vitro cartilage engineering, the combination of small scaffold pores and low porosity is an effective strategy with regard to the promotion of chondrogenesis.

  7. Real-Time Pore Pressure Detection: Indicators and Improved Methods

    Directory of Open Access Journals (Sweden)

    Jincai Zhang

    2017-01-01

    Full Text Available High uncertainties may exist in the predrill pore pressure prediction in new prospects and deepwater subsalt wells; therefore, real-time pore pressure detection is highly needed to reduce drilling risks. The methods for pore pressure detection (the resistivity, sonic, and corrected d-exponent methods are improved using the depth-dependent normal compaction equations to adapt to the requirements of the real-time monitoring. A new method is proposed to calculate pore pressure from the connection gas or elevated background gas, which can be used for real-time pore pressure detection. The pore pressure detection using the logging-while-drilling, measurement-while-drilling, and mud logging data is also implemented and evaluated. Abnormal pore pressure indicators from the well logs, mud logs, and wellbore instability events are identified and analyzed to interpret abnormal pore pressures for guiding real-time drilling decisions. The principles for identifying abnormal pressure indicators are proposed to improve real-time pore pressure monitoring.

  8. Fusion Pore Diameter Regulation by Cations Modulating Local Membrane Anisotropy

    Directory of Open Access Journals (Sweden)

    Doron Kabaso

    2012-01-01

    Full Text Available The fusion pore is an aqueous channel that is formed upon the fusion of the vesicle membrane with the plasma membrane. Once the pore is open, it may close again (transient fusion or widen completely (full fusion to permit vesicle cargo discharge. While repetitive transient fusion pore openings of the vesicle with the plasma membrane have been observed in the absence of stimulation, their frequency can be further increased using a cAMP-increasing agent that drives the opening of nonspecific cation channels. Our model hypothesis is that the openings and closings of the fusion pore are driven by changes in the local concentration of cations in the connected vesicle. The proposed mechanism of fusion pore dynamics is considered as follows: when the fusion pore is closed or is extremely narrow, the accumulation of cations in the vesicle (increased cation concentration likely leads to lipid demixing at the fusion pore. This process may affect local membrane anisotropy, which reduces the spontaneous curvature and thus leads to the opening of the fusion pore. Based on the theory of membrane elasticity, we used a continuum model to explain the rhythmic opening and closing of the fusion pore.

  9. X-ray microtomography application in pore space reservoir rock.

    Science.gov (United States)

    Oliveira, M F S; Lima, I; Borghi, L; Lopes, R T

    2012-07-01

    Characterization of porosity in carbonate rocks is important in the oil and gas industry since a major hydrocarbons field is formed by this lithology and they have a complex media porous. In this context, this research presents a study of the pore space in limestones rocks by x-ray microtomography. Total porosity, type of porosity and pore size distribution were evaluated from 3D high resolution images. Results show that carbonate rocks has a complex pore space system with different pores types at the same facies. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. Role of the synaptobrevin C terminus in fusion pore formation

    DEFF Research Database (Denmark)

    Ngatchou, Annita N; Kisler, Kassandra; Fang, Qinghua

    2010-01-01

    Neurotransmitter release is mediated by the SNARE proteins synaptobrevin II (sybII, also known as VAMP2), syntaxin, and SNAP-25, generating a force transfer to the membranes and inducing fusion pore formation. However, the molecular mechanism by which this force leads to opening of a fusion pore...... stimulation, the SNARE complex pulls the C terminus of sybII deeper into the vesicle membrane. We propose that this movement disrupts the vesicular membrane continuity leading to fusion pore formation. In contrast to current models, the experiments suggest that fusion pore formation begins with molecular...

  11. Extraction of pores from microtomographic reconstructions of intact soil aggregates

    Energy Technology Data Exchange (ETDEWEB)

    Albee, P. B.; Stockman, G. C.; Smucker, A. J. M.

    2000-02-29

    Segmentation of features is often a necessary step in the analysis of volumetric data. The authors have developed a simple technique for extracting voids from irregular volumetric data sets. In this work they look at extracting pores from soil aggregates. First, they identify a threshold that gives good separability of the object from the background. They then segment the object, and perform connected components analysis on the pores within the object. Using their technique pores that break the surface can be segmented along with pores completely contained in the initially segmented object.

  12. Pore-size Distributions from Nitrogen Adsorption Revisited: Models Comparison with Controlled-pore Glasses

    Czech Academy of Sciences Publication Activity Database

    Šolcová, Olga; Matějová, Lenka; Schneider, Petr

    2006-01-01

    Roč. 313, č. 2 (2006), s. 167-176 ISSN 0926-860X R&D Projects: GA ČR(CZ) GA104/04/2116; GA ČR GD203/03/H140; GA AV ČR IAA4072404 Institutional research plan: CEZ:AV0Z40720504 Keywords : pore size distribution * physical adsorption * standard nitrogen isotherm Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.630, year: 2006

  13. Free loop spaces and cyclohedra

    Czech Academy of Sciences Publication Activity Database

    Markl, Martin

    2003-01-01

    Roč. 71, - (2003), s. 151-157 R&D Projects: GA AV ČR IAA1019203 Institutional research plan: CEZ:AV0Z1019905; CEZ:AV0Z1019905 Keywords : cyclohedron * free loop space * recognition Subject RIV: BA - General Mathematics

  14. Feedback - closing the loop digitally

    International Nuclear Information System (INIS)

    Zagel, J.; Chase, B.

    1992-01-01

    Many feedback and feedforward systems are now using microprocessors within the loop. We describe the wide range of possibilities and problems that arise. We also propose some ideas for analysis and testing, including examples of motion control in the Flying Wire systems in Main Ring and Tevatron and Low Level RF control now being built for the Fermilab Linac upgrade. (author)

  15. Morbidity of temporary loop ileostomies

    NARCIS (Netherlands)

    Bakx, R.; Busch, O. R. C.; Bemelman, W. A.; Veldink, G. J.; Slors, J. F. M.; van Lanschot, J. J. B.

    2004-01-01

    Background/Aims: A temporary loop ileostomy is constructed to protect a distal colonic anastomosis. Closure is usually performed not earlier than 8 - 12 weeks after the primary operation. During this period, stoma-related complications can occur and enhance the adverse effect on quality of life. The

  16. Wilson loops in Kerr gravitation

    International Nuclear Information System (INIS)

    Bollini, C.G.; Giambiagi, J.J.; Tiomno, J.

    1981-01-01

    The ordered integrals for several paths in Kerr gravitation is computed in a compact form. When the path is closed its relation with the angular parallel displacement is discussed and the corresponding Wilson loop is calculated. The validity of Mandelstam relations for gauge fields is also explicitly verified. (Author) [pt

  17. Loop quantum cosmology: Recent progress

    Indian Academy of Sciences (India)

    Aspects of the full theory of loop quantum gravity can be studied in a simpler .... group) 1-forms and vector fields and Λ is an SO(3)-matrix indicating the internal ... are p and c which are related to the more familiar scale factor by the relations.

  18. PONDEROMOTIVE ACCELERATION IN CORONAL LOOPS

    Energy Technology Data Exchange (ETDEWEB)

    Dahlburg, R. B.; Obenschain, K. [LCP and FD, Naval Research Laboratory, Washington, DC 20375 (United States); Laming, J. M. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Taylor, B. D. [AFRL Eglin AFB, Pensacola, FL 32542 (United States)

    2016-11-10

    Ponderomotive acceleration has been asserted to be a cause of the first ionization potential (FIP) effect, the well-known enhancement in abundance by a factor of 3–4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a “by-product” of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of coronal loops with an axial magnetic field from 0.005 to 0.02 T and lengths from 25,000 to 75,000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets, which act to heat the loop. As a consequence of coronal magnetic reconnection, small-scale, high-speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.

  19. Loop quantum cosmology and singularities.

    Science.gov (United States)

    Struyve, Ward

    2017-08-15

    Loop quantum gravity is believed to eliminate singularities such as the big bang and big crunch singularity. This belief is based on studies of so-called loop quantum cosmology which concerns symmetry-reduced models of quantum gravity. In this paper, the problem of singularities is analysed in the context of the Bohmian formulation of loop quantum cosmology. In this formulation there is an actual metric in addition to the wave function, which evolves stochastically (rather than deterministically as the case of the particle evolution in non-relativistic Bohmian mechanics). Thus a singularity occurs whenever this actual metric is singular. It is shown that in the loop quantum cosmology for a homogeneous and isotropic Friedmann-Lemaître-Robertson-Walker space-time with arbitrary constant spatial curvature and cosmological constant, coupled to a massless homogeneous scalar field, a big bang or big crunch singularity is never obtained. This should be contrasted with the fact that in the Bohmian formulation of the Wheeler-DeWitt theory singularities may exist.

  20. PONDEROMOTIVE ACCELERATION IN CORONAL LOOPS

    International Nuclear Information System (INIS)

    Dahlburg, R. B.; Obenschain, K.; Laming, J. M.; Taylor, B. D.

    2016-01-01

    Ponderomotive acceleration has been asserted to be a cause of the first ionization potential (FIP) effect, the well-known enhancement in abundance by a factor of 3–4 over photospheric values of elements in the solar corona with FIP less than about 10 eV. It is shown here by means of numerical simulations that ponderomotive acceleration occurs in solar coronal loops, with the appropriate magnitude and direction, as a “by-product” of coronal heating. The numerical simulations are performed with the HYPERION code, which solves the fully compressible three-dimensional magnetohydrodynamic equations including nonlinear thermal conduction and optically thin radiation. Numerical simulations of coronal loops with an axial magnetic field from 0.005 to 0.02 T and lengths from 25,000 to 75,000 km are presented. In the simulations the footpoints of the axial loop magnetic field are convected by random, large-scale motions. There is a continuous formation and dissipation of field-aligned current sheets, which act to heat the loop. As a consequence of coronal magnetic reconnection, small-scale, high-speed jets form. The familiar vortex quadrupoles form at reconnection sites. Between the magnetic footpoints and the corona the reconnection flow merges with the boundary flow. It is in this region that the ponderomotive acceleration occurs. Mirroring the character of the coronal reconnection, the ponderomotive acceleration is also found to be intermittent.

  1. Independent SU(2)-loop variables

    International Nuclear Information System (INIS)

    Loll, R.

    1991-04-01

    We give a reduction procedure for SU(2)-trace variables and introduce a complete set of indepentent, gauge-invariant and almost local loop variables for the configuration space of SU(2)-lattice gauge theory in 2+1 dimensions. (orig.)

  2. An experimental study of dislocation loop nucleation

    International Nuclear Information System (INIS)

    Bounaud, J.Y.; Leteurtre, J.

    1975-01-01

    The nucleation of dislocation loops is experimentally studied by observing the demixion of the Burgers vectors of dislocation loops nucleated in copper whiskers irradiated in flexion by fission fragments at room temperature. The demixion of Burgers vectors is observed by the dimensional effects of dislocation loops: after irradiation, the applied stress is removed; the whisker shows a residual strain that is due to loops because, after an annealing treatment to evaporate dislocation loops, each whisker recovers its initial straight shape. Everywhere along the whisker, the radius of curvature is measured and plotted vs the max. applied stress. Estimations of the interstitial and vacancy dislocation loop nuclei are derived [fr

  3. The effect of the atmosphere and the role of pore filling on the sintering of aluminium

    International Nuclear Information System (INIS)

    Schaffer, G.B.; Hall, B.J.; Bonner, S.J.; Huo, S.H.; Sercombe, T.B.

    2006-01-01

    Alloys of Al-3.8Cu-1Mg-0.7Si, Al-4Cu-0.6Si-0.1Mg, Al-4Cu-1.2Mg and Al-1.9Mg-1.9Si were made using air atomised powder and conventional press-and-sinter powder metallurgy techniques. These were sintered under nitrogen with a controlled water content which varied from 3 to 630 ppm (a dew point of -69 to -25 deg. C), nitrogen-5%hydrogen, argon and argon-5%hydrogen, all at atmospheric pressure, or a vacuum of -2 torr. Dry nitrogen is the most efficacious atmosphere. Vacuum is more effective than argon while hydrogen, and thus water, is extremely prejudicial to sintered density. The minimum dew point for optimum sintering is -60 deg. C (10.5 ppm H 2 O). The key feature in the beneficial effect of nitrogen is the formation of aluminium nitride. This reduces the pressure in the pore spaces relative to the external atmosphere, which induces pore filling at grain sizes that are smaller than those required for sintering in inert atmospheres. It is suggested that pore filling is an important densification mechanism during the sintering of aluminium

  4. Propagation of a plasma streamer in catalyst pores

    Science.gov (United States)

    Zhang, Quan-Zhi; Bogaerts, Annemie

    2018-03-01

    Although plasma catalysis is gaining increasing interest for various environmental applications, the underlying mechanisms are still far from understood. For instance, it is not yet clear whether and how plasma streamers can propagate in catalyst pores, and what is the minimum pore size to make this happen. As this is crucial information to ensure good plasma-catalyst interaction, we study here the mechanism of plasma streamer propagation in a catalyst pore, by means of a two-dimensional particle-in-cell/Monte Carlo collision model, for various pore diameters in the nm-range to μm-range. The so-called Debye length is an important criterion for plasma penetration into catalyst pores, i.e. a plasma streamer can penetrate into pores when their diameter is larger than the Debye length. The Debye length is typically in the order of a few 100 nm up to 1 μm at the conditions under study, depending on electron density and temperature in the plasma streamer. For pores in the range of ∼50 nm, plasma can thus only penetrate to some extent and at very short times, i.e. at the beginning of a micro-discharge, before the actual plasma streamer reaches the catalyst surface and a sheath is formed in front of the surface. We can make plasma streamers penetrate into smaller pores (down to ca. 500 nm at the conditions under study) by increasing the applied voltage, which yields a higher plasma density, and thus reduces the Debye length. Our simulations also reveal that the plasma streamers induce surface charging of the catalyst pore sidewalls, causing discharge enhancement inside the pore, depending on pore diameter and depth.

  5. Pore dimensions and the role of occupancy in unitary conductance of Shaker K channels

    Science.gov (United States)

    Díaz-Franulic, Ignacio; Sepúlveda, Romina V.; Navarro-Quezada, Nieves; González-Nilo, Fernando

    2015-01-01

    K channels mediate the selective passage of K+ across the plasma membrane by means of intimate interactions with ions at the pore selectivity filter located near the external face. Despite high conservation of the selectivity filter, the K+ transport properties of different K channels vary widely, with the unitary conductance spanning a range of over two orders of magnitude. Mutation of Pro475, a residue located at the cytoplasmic entrance of the pore of the small-intermediate conductance K channel Shaker (Pro475Asp (P475D) or Pro475Gln (P475Q)), increases Shaker’s reported ∼20-pS conductance by approximately six- and approximately threefold, respectively, without any detectable effect on its selectivity. These findings suggest that the structural determinants underlying the diversity of K channel conductance are distinct from the selectivity filter, making P475D and P475Q excellent probes to identify key determinants of the K channel unitary conductance. By measuring diffusion-limited unitary outward currents after unilateral addition of 2 M sucrose to the internal solution to increase its viscosity, we estimated a pore internal radius of capture of ∼0.82 Å for all three Shaker variants (wild type, P475D, and P475Q). This estimate is consistent with the internal entrance of the Kv1.2/2.1 structure if the effective radius of hydrated K+ is set to ∼4 Å. Unilateral exposure to sucrose allowed us to estimate the internal and external access resistances together with that of the inner pore. We determined that Shaker resistance resides mainly in the inner cavity, whereas only ∼8% resides in the selectivity filter. To reduce the inner resistance, we introduced additional aspartate residues into the internal vestibule to favor ion occupancy. No aspartate addition raised the maximum unitary conductance, measured at saturating [K+], beyond that of P475D, suggesting an ∼200-pS conductance ceiling for Shaker. This value is approximately one third of the maximum

  6. Double closed-loop cascade control for lower limb exoskeleton with elastic actuation.

    Science.gov (United States)

    Zhu, Yanhe; Zheng, Tianjiao; Jin, Hongzhe; Yang, Jixing; Zhao, Jie

    2015-01-01

    Unlike traditional rigid actuators, the significant features of Series Elastic Actuator (SEA) are stable torque control, lower output impedance, impact resistance and energy storage. Recently, SEA has been applied in many exoskeletons. In such applications, a key issue is how to realize the human-exoskeleton movement coordination. In this paper, double closed-loop cascade control for lower limb exoskeleton with SEA is proposed. This control method consists of inner SEA torque loop and outer contact force loop. Utilizing the SEA torque control with a motor velocity loop, actuation performances of SEA are analyzed. An integrated exoskeleton control system is designed, in which joint angles are calculated by internal encoders and resolvers and contact forces are gathered by external pressure sensors. The double closed-loop cascade control model is established based on the feedback signals of internal and external sensor. Movement experiments are accomplished in our prototype of lower limb exoskeleton. Preliminary results indicate the exoskeleton movements with pilot can be realized stably by utilizing this double closed-loop cascade control method. Feasibility of the SEA in our exoskeleton robot and effectiveness of the control method are verified.

  7. Malignant external otitis

    International Nuclear Information System (INIS)

    Dupuch, K.M.; Iryboz, T.; Firat, M.; Levy, C.; Tubiana, J.M.

    1991-01-01

    This paper illustrates the value of CT and MR in early diagnosis and spread of malignant external otitis. The authors retrospectively analyzed 15 patients with proved malignant external otitis examined with postcontrast high-resolution CT (15/15) and MR (6/15) (T1- and T2-weighting). Gallium studies were done in 6/15 patients. Early diagnosis was made when CT demonstrated a soft-tissue mass of the external auditory canal associated with scattered zones of cortical bone erosions (13/15). Spread of the disease was better delineated by MR than CT, especially skull base extension (6/15). Temporomandibular joint involvement with extension into parotid or/and masticator spaces 6/15 was as well detected with CT as with MR. If CT remains the first and best procedure for diagnosis, MR - despite its cost - appears a good procedure to depict exact anatomic spread, allowing therapeutic management

  8. Productivity Change and Externalities

    DEFF Research Database (Denmark)

    Kravtsova, Victoria

    2014-01-01

    This paper contributes to the analysis of the impact of externalities on the host country's total factor productivity by taking into account different dimensions of spillover effects. Namely, engagement in exporting and foreign ownership is generally perceived as being beneficial to individual...... firms and the economy as a whole. The approach used in the current research accounts for different internal as well as external factors that individual firms face and evaluates the effect on changes in productivity, technology as well as the efficiency of domestic firms. The empirical analysis focuses...... on Hungary. While the country leads the group of post-socialist countries in the amount of attracted foreign direct investments (FDI) the effect of this policy on the economy remains unclear. The research finds that different externalities play a different role in productivity, technological and efficiency...

  9. Externality or sustainability economics?

    International Nuclear Information System (INIS)

    Bergh, Jeroen C.J.M. van den

    2010-01-01

    In an effort to develop 'sustainability economics' Baumgaertner and Quaas (2010) neglect the central concept of environmental economics-'environmental externality'. This note proposes a possible connection between the concepts of environmental externality and sustainability. In addition, attention is asked for other aspects of 'sustainability economics', namely the distinction weak/strong sustainability, spatial sustainability and sustainable trade, distinctive sustainability policy, and the ideas of early 'sustainability economists'. I argue that both sustainability and externalities reflect a systems perspective and propose that effective sustainability solutions require that more attention is given to system feedbacks, notably other-regarding preferences and social interactions, and energy and environmental rebound. The case of climate change and policy is used to illustrate particular statements. As a conclusion, a list of 20 insights and suggestions for research is offered. (author)

  10. Metasurface external cavity laser

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Luyao, E-mail: luyaoxu.ee@ucla.edu; Curwen, Christopher A.; Williams, Benjamin S. [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); California NanoSystems Institute, University of California, Los Angeles, California 90095 (United States); Hon, Philip W. C.; Itoh, Tatsuo [Department of Electrical Engineering, University of California, Los Angeles, California 90095 (United States); Chen, Qi-Sheng [Northrop Grumman Aerospace Systems, Redondo Beach, California 90278 (United States)

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  11. Two- and three-loop amplitudes in covariant loop calculus

    International Nuclear Information System (INIS)

    Roland, K.

    1988-04-01

    We study 2- and 3-loop vacuum-amplitudes for the closed bosonic string. We compare two sets of expressions for the corresponding density on moduli space: One, based on the covariant Reggeon loop calculus (where modular invariance is not manifest). The other, based on analytic geometry. We want to prove identity between the two sets of expressions. Quite apart from demonstrating modular invariance of the Reggeon results, this would in itself be a remarkable mathematical feature. Identity is established to 'high' order in some moduli and exactly in others. The expansions reveal an essentially number-theoretical structure. Agreement is found only by exploiting the connection between the 4 Jacobi θ-functions and number theory. (orig.)

  12. Two- and three-loop amplitudes in covariant loop calculus

    International Nuclear Information System (INIS)

    Roland, K.

    1989-01-01

    We study two- and three-loop vacuum amplitudes for the closed bosonic string. We compare two sets of expressions for the corresponding density on moduli space. One is based on the covariant reggeon loop calculus (where modular invariance is not manifest). The other is based on analytic geometry. We want to prove identity between the two sets of expressions. Quite apart from demonstrating modular invariance of the reggeon results, this would in itself be a remarkable mathematical feature. Identity is established to ''high'' order in some moduli and exactly in others. The expansions reveal an essentially number-theoretic structure. Agreement is found only by exploiting the connection between the four Jacobi θ-functions and number theory. (orig.)

  13. Performance of multilayer coated silicon pore optics

    Science.gov (United States)

    Ackermann, M. D.; Collon, M. J.; Jensen, C. P.; Christensen, F. E.; Krumrey, M.; Cibik, L.; Marggraf, S.; Bavdaz, M.; Lumb, D.; Shortt, B.

    2010-07-01

    The requirements for the IXO (International X-ray Observatory) telescope are very challenging in respect of angular resolution and effective area. Within a clear aperture with 1.7 m > R > 0.25 m that is dictated by the spacecraft envelope, the optics technology must be developed to satisfy simultaneously requirements for effective area of 2.5 m2 at 1.25 keV, 0.65 m2 at 6 keV and 150 cm2 at 30 keV. The reflectivity of the bare mirror substrate materials does not allow these requirements to be met. As such the IXO baseline design contains a coating layout that varies as a function of mirror radius and in accordance with the variation in grazing incidence angle. The higher energy photon response is enhanced through the use of depth-graded multilayer coatings on the inner radii mirror modules. In this paper we report on the first reflectivity measurements of wedged ribbed silicon pore optics mirror plates coated with a depth graded W/Si multilayer. The measurements demonstrate that the deposition and performance of the multilayer coatings is compatible with the SPO production process.

  14. Current concepts in nuclear pore electrophysiology.

    Science.gov (United States)

    Bustamante, José Omar

    2006-01-01

    Over 4 decades ago, microelectrode studies of in situ nuclei showed that, under certain conditions, the nuclear envelope (NE) behaves as a barrier opposing the nucleocytoplasmic flow of physiological ions. As the nuclear pore complexes (NPCs) of the NE are the only pathways for direct nucleocytoplasmic flow, those experiments implied that the NPCs are capable of restricting ion flow. These early studies validated electrophysiology as a useful approach to quantify some of the mechanisms by which NPCs mediate gene activity and expression. Since electron microscopy (EM) and other non-electrophysiological investigations, showed that the NPC lumen is a nanochannel, the opinion prevailed that the NPC could not oppose the flow of ions and, therefore, that electrophysiological observations resulted from technical artifacts. Consequently, the initial enthusiasm with nuclear electrophysiology faded out in less than a decade. In 1990, nuclear electrophysiology was revisited with patch-clamp, the most powerful electrophysiological technique to date. Patch-clamp has consistently demonstrated that the NE has intrinsic ion channel activity. Direct demonstrations of the NPC on-off ion channel gating behavior were published for artificial conditions in 1995 and for intact living nuclei in 2002. This on-off switching/gating behavior can be interpreted in terms of a metastable energy barrier. In the hope of advancing nuclear electrophysiology, and to complement the other papers contained in this special issue of the journal, here I review some of the main technical, experimental, and theoretical issues of the field, with special focus on NPCs.

  15. Multi-loop correlators for rational theories of 2D gravity from the generalized Kontsevich models

    DEFF Research Database (Denmark)

    Kristjansen, C.

    1994-01-01

    functions of the susceptibilities and the eigenvalues of the external field. We furthermore use the moment technique to derive a closed expression for the genus zero multi-loop correlators for $(3,3m-1)$ and $(3,3m-2)$ rational matter fields coupled to gravity. We comment on the relation between the two-matrix...

  16. Appell functions and the scalar one-loop three-point integrals in Feynman diagrams

    Energy Technology Data Exchange (ETDEWEB)

    Cabral-Rosetti, L G [Departamento de Posgrado, Centro Interdisciplinario de Investigacion y Docencia en Educacion Tecnica (CIIDET), Av. Universidad 282 Pte., Col. Centro, A. Postal 752, C.P. 76000, Santiago de Queretaro, Qro. (Mexico); Sanchis-Lozano, M A [Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, 46100 Burjassot, Valencia (Spain)

    2006-05-15

    The scalar three-point function appearing in one-loop Feynman diagrams is compactly expressed in terms of a generalized hypergeometric function of two variables. Use is made of the connection between such Appell function and dilogarithms coming from a previous investigation. Special cases are obtained for particular values of internal masses and external momenta.

  17. The hydraulic conductivity of sediments: A pore size perspective

    KAUST Repository

    Ren, X.W.; Santamarina, Carlos

    2017-01-01

    in the void ratio is higher than the theoretical value due to two concurrent phenomena: 1) percolating large pores are responsible for most of the flow, and 2) the larger pores close first during compaction. The prediction of hydraulic conductivity based

  18. Pore fluids from the argillaceous rocks of the Harwell region

    International Nuclear Information System (INIS)

    Brightman, M.A.; Bath, A.H.; Cave, M.R.; Darling, W.G.

    1985-06-01

    The aim of this work was to obtain samples of pore water from argillaceous formations in the Harwell area for chemical analysis to provide a background for radionuclide migration studies and regional groundwater flow pattern. This report describes the samples, development of a pore-water squeezing cell and its operation. Chemical and analytical studies are summarized. (UK)

  19. Molecular Dynamics Simulations of Hydrophilic Pores in Lipid Bilayers

    NARCIS (Netherlands)

    Leontiadou, Hari; Mark, Alan E.; Marrink, Siewert J.

    Hydrophilic pores are formed in peptide free lipid bilayers under mechanical stress. It has been proposed that the transport of ionic species across such membranes is largely determined by the existence of such meta-stable hydrophilic pores. To study the properties of these structures and understand

  20. The study of the relationship between pore structure and ...

    Indian Academy of Sciences (India)

    Administrator

    The pore structure was determined by the N2 adsorption/desorption method below. 73 K and calculated using the BJH model. TEM characterizations show that the pores are ... Mesoporous TiO2 was obtained by calcination of the gel at 500°C for 6 h in air to remove the surfactant species. The samples were designated as ...

  1. Pore size distribution in tablets measured with a morphological sieve

    NARCIS (Netherlands)

    Wu, Yu San; van Vliet, Lucas J.; Frijlink, Henderik W.; van der Voort Maarschalk, Kees

    2007-01-01

    Porosity and pore structure are important characteristics of tablets, since they influence mechanical strength and many other proper-ties. This paper proposes an alternative method for the characterization of pore structure based on image analysis of SEM micrographs. SEM images were made of sodium

  2. The Pore Structure of Direct Methanol Fuel Cell Electrodes

    DEFF Research Database (Denmark)

    Lund, Peter Brilner

    2005-01-01

    The pore structure and morphology of direct methanol fuel cell electrodes are characterized using mercury intrusion porosimetry and scanning electron microscopy. It is found that the pore size distributions of printed primer and catalyst layers are largely dictated by the powders used to make...

  3. Pore size determination from charged particle energy loss measurement

    International Nuclear Information System (INIS)

    Brady, F.P.; Armitage, B.H.

    1977-01-01

    A new method aimed at measuring porosity and mean pore size in materials has been developed at Harwell. The energy width or variance of a transmitted or backscattered charged particle beam is measured and related to the mean pore size via the assumption that the variance in total path length in the porous material is given by (Δx 2 )=na 2 , where n is the mean number of pores and a the mean pore size. It is shown on the basis of a general and rigorous theory of total path length distribution that this approximation can give rise to large errors in the mean pore size determination particularly in the case of large porosities (epsilon>0.5). In practice it is found that it is not easy to utilize fully the general theory because accurate measurements of the first four moments are required to determine the means and variances of the pore and inter-pore length distributions. Several models for these distributions are proposed. When these are incorporated in the general theory the determinations of mean pore size from experimental measurements on powder samples are in good agreement with values determined by other methods. (Auth.)

  4. A FILTRATION METHOD AND APPARATUS INCLUDING A ROLLER WITH PORES

    DEFF Research Database (Denmark)

    2008-01-01

    The present invention offers a method for separating dry matter from a medium. A separation chamber is at least partly defined by a plurality of rollers (2,7) and is capable of being pressure regulated. At least one of the rollers is a pore roller (7) having a surface with pores allowing permeabi...

  5. The External Mind

    DEFF Research Database (Denmark)

    , Extended Mind and Distributed Cognition by Claudio Paolucci pp. 69-96 The Social Horizon of Embodied Language and Material Symbols by Riccardo Fusaroli pp. 97-123 Semiotics and Theories of Situated/Distributed Action and Cognition: a Dialogue and Many Intersections by Tommaso Granelli pp. 125-167 Building......The External Mind: an Introduction by Riccardo Fusaroli, Claudio Paolucci pp. 3-31 The sign of the Hand: Symbolic Practices and the Extended Mind by Massimiliano Cappuccio, Michael Wheeler pp. 33-55 The Overextended Mind by Shaun Gallagher pp. 57-68 The "External Mind": Semiotics, Pragmatism...

  6. Counting loop diagrams: computational complexity of higher-order amplitude evaluation

    International Nuclear Information System (INIS)

    Eijk, E. van; Kleiss, R.; Lazopoulos, A.

    2004-01-01

    We discuss the computational complexity of the perturbative evaluation of scattering amplitudes, both by the Caravaglios-Moretti algorithm and by direct evaluation of the individual diagrams. For a self-interacting scalar theory, we determine the complexity as a function of the number of external legs. We describe a method for obtaining the number of topologically inequivalent Feynman graphs containing closed loops, and apply this to 1- and 2-loop amplitudes. We also compute the number of graphs weighted by their symmetry factors, thus arriving at exact and asymptotic estimates for the average symmetry factor of diagrams. We present results for the asymptotic number of diagrams up to 10 loops, and prove that the average symmetry factor approaches unity as the number of external legs becomes large. (orig.)

  7. Integrative structure and functional anatomy of a nuclear pore complex

    Science.gov (United States)

    Kim, Seung Joong; Fernandez-Martinez, Javier; Nudelman, Ilona; Shi, Yi; Zhang, Wenzhu; Raveh, Barak; Herricks, Thurston; Slaughter, Brian D.; Hogan, Joanna A.; Upla, Paula; Chemmama, Ilan E.; Pellarin, Riccardo; Echeverria, Ignacia; Shivaraju, Manjunatha; Chaudhury, Azraa S.; Wang, Junjie; Williams, Rosemary; Unruh, Jay R.; Greenberg, Charles H.; Jacobs, Erica Y.; Yu, Zhiheng; de La Cruz, M. Jason; Mironska, Roxana; Stokes, David L.; Aitchison, John D.; Jarrold, Martin F.; Gerton, Jennifer L.; Ludtke, Steven J.; Akey, Christopher W.; Chait, Brian T.; Sali, Andrej; Rout, Michael P.

    2018-03-01

    Nuclear pore complexes play central roles as gatekeepers of RNA and protein transport between the cytoplasm and nucleoplasm. However, their large size and dynamic nature have impeded a full structural and functional elucidation. Here we determined the structure of the entire 552-protein nuclear pore complex of the yeast Saccharomyces cerevisiae at sub-nanometre precision by satisfying a wide range of data relating to the molecular arrangement of its constituents. The nuclear pore complex incorporates sturdy diagonal columns and connector cables attached to these columns, imbuing the structure with strength and flexibility. These cables also tie together all other elements of the nuclear pore complex, including membrane-interacting regions, outer rings and RNA-processing platforms. Inwardly directed anchors create a high density of transport factor-docking Phe-Gly repeats in the central channel, organized into distinct functional units. This integrative structure enables us to rationalize the architecture, transport mechanism and evolutionary origins of the nuclear pore complex.

  8. Integrative structure and functional anatomy of a nuclear pore complex.

    Science.gov (United States)

    Kim, Seung Joong; Fernandez-Martinez, Javier; Nudelman, Ilona; Shi, Yi; Zhang, Wenzhu; Raveh, Barak; Herricks, Thurston; Slaughter, Brian D; Hogan, Joanna A; Upla, Paula; Chemmama, Ilan E; Pellarin, Riccardo; Echeverria, Ignacia; Shivaraju, Manjunatha; Chaudhury, Azraa S; Wang, Junjie; Williams, Rosemary; Unruh, Jay R; Greenberg, Charles H; Jacobs, Erica Y; Yu, Zhiheng; de la Cruz, M Jason; Mironska, Roxana; Stokes, David L; Aitchison, John D; Jarrold, Martin F; Gerton, Jennifer L; Ludtke, Steven J; Akey, Christopher W; Chait, Brian T; Sali, Andrej; Rout, Michael P

    2018-03-22

    Nuclear pore complexes play central roles as gatekeepers of RNA and protein transport between the cytoplasm and nucleoplasm. However, their large size and dynamic nature have impeded a full structural and functional elucidation. Here we determined the structure of the entire 552-protein nuclear pore complex of the yeast Saccharomyces cerevisiae at sub-nanometre precision by satisfying a wide range of data relating to the molecular arrangement of its constituents. The nuclear pore complex incorporates sturdy diagonal columns and connector cables attached to these columns, imbuing the structure with strength and flexibility. These cables also tie together all other elements of the nuclear pore complex, including membrane-interacting regions, outer rings and RNA-processing platforms. Inwardly directed anchors create a high density of transport factor-docking Phe-Gly repeats in the central channel, organized into distinct functional units. This integrative structure enables us to rationalize the architecture, transport mechanism and evolutionary origins of the nuclear pore complex.

  9. X-ray microtomography application in pore space reservoir rock

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, M.F.S.; Lima, I. [Nuclear Instrumentation Laboratory, COPPE/UFRJ, P.O. Box 68509, 21.941-972, Rio de Janeiro (Brazil); Borghi, L. [Geology Department, Geosciences Institute, Federal University of Rio de Janeiro, Brazil. (Brazil); Lopes, R.T., E-mail: ricardo@lin.ufrj.br [Nuclear Instrumentation Laboratory, COPPE/UFRJ, P.O. Box 68509, 21.941-972, Rio de Janeiro (Brazil)

    2012-07-15

    Characterization of porosity in carbonate rocks is important in the oil and gas industry since a major hydrocarbons field is formed by this lithology and they have a complex media porous. In this context, this research presents a study of the pore space in limestones rocks by x-ray microtomography. Total porosity, type of porosity and pore size distribution were evaluated from 3D high resolution images. Results show that carbonate rocks has a complex pore space system with different pores types at the same facies. - Highlights: Black-Right-Pointing-Pointer This study is about porosity parameter in carbonate rocks by 3D X-Ray Microtomography. Black-Right-Pointing-Pointer This study has become useful as data input for modeling reservoir characterization. Black-Right-Pointing-Pointer This technique was able to provide pores, grains and mineralogical differences among the samples.

  10. Measurements of pore-scale flow through apertures

    Energy Technology Data Exchange (ETDEWEB)

    Chojnicki, Kirsten [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-09-01

    Pore-scale aperture effects on flow in pore networks was studied in the laboratory to provide a parameterization for use in transport models. Four cases were considered: regular and irregular pillar/pore alignment with and without an aperture. The velocity field of each case was measured and simulated, providing quantitatively comparable results. Two aperture effect parameterizations were considered: permeability and transmission. Permeability values varied by an order of magnitude between the cases with and without apertures. However, transmission did not correlate with permeability. Despite having much greater permeability the regular aperture case permitted less transmission than the regular case. Moreover, both irregular cases had greater transmission than the regular cases, a difference not supported by the permeabilities. Overall, these findings suggest that pore-scale aperture effects on flow though a pore-network may not be adequately captured by properties such as permeability for applications that are interested in determining particle transport volume and timing.

  11. Modelling bentonite pore waters for the Swiss high-level radioactive waste repository

    International Nuclear Information System (INIS)

    Curti, E.

    1993-11-01

    The main objective of this investigation is to contribute to definition of representative compositions of bentonite pore waters in the near-field of the Swiss repository for high-level radioactive waste. Such compositions are necessary for determining the solubility limits of radionuclides for the safety analysis KRISTALLIN I. The model developed here is based on the premise, supported by experimental data, that the composition of bentonite pore waters is largely controlled by the dissolution or precipitation of reactive trace solids in bentonite. Selectivity constants for the exchange equilibria among Na-K, Na-Ca, and Ca-Mg were derived from water-bentonite interaction experiments performed for NAGRA by the British Geological Survey (BGS). An important parameter for the prediction of radionuclide solubilities is the oxidation potential of the bentonite water. Since the BGS experiments yielded no information on this, the oxidation potential had to be estimated from model assumptions. Bentonite pore waters were defined by computer simulation with the geochemical code MINEQL. They have been modelled in a closed system, i.e. assuming the bentonite, once it has reacted with a fixed volume of groundwater, does not exchange further chemical species with an external reservoir. No attempt was made to model the evolution of the pore water by simulating diffusive exchange processes. It can be anticipated that uncertainties in the concentrations of some major elements (e.g. Al, Si) will not significantly affect the calculated radionuclide solubilities. The latter will depend primarily on the concentrations of a few major ligands (OH - , Cl - and CO 3 -2 ) and, for multivalent elements, also on the oxidation potential of the solution. (author) 10 figs., 22 tabs., 40 refs

  12. Background noise of acoustic emission signals in sodium piping loop

    International Nuclear Information System (INIS)

    Mori, Y.; Aoki, K.; Kuribayashi, K.; Kishi, T.; Sakakibara, Y.

    1985-01-01

    Background noise measurement in the frequency range of acoustic emission (AE) signals was made on the sodium piping loops of a 50 MW steam generator test facility in the Power Reactor and Nuclear Fuel Development Corporation (PNC). During the dynamic characteristics test of the steam generator over a wide range of operating conditions, the background noise generated on the pipe surface was measured using wideband AE sensor externally mounted with waveguide. Data were obtained for the effect of power loads of steam generator on both amplitude and frequency spectra of background noise signals. Source and nature of background noise were established

  13. Covariant loop-calculus for the closed bosonic string

    International Nuclear Information System (INIS)

    Petersen, J.L.; Sidenius, J.R.

    1987-06-01

    A previously suggested N-reggeon (N-string) amplitude based on the BRST-formulation is extended by obtaining integrations over Koba-Nielsen-like variables in terms of integrations over quasiconformal ghost fields. Simple sewing rules for reggeons are set up and the N-reggeon amplitude is shown to factorize correctly and to have satisfactory BRST-cohomology properties. Multi-loop amplitudes for arbitrary external states are constructed in the Schottky parametrization. The sewing prescription for antighost zero-modes produces a measure on Schottky space with the characteristic BRST properties. The treatment is inherently local on moduli space, however. (orig./HSI)

  14. Numerical investigation of closed-loop control for Hall accelerators

    International Nuclear Information System (INIS)

    Barral, S.; Miedzik, J.

    2011-01-01

    Low frequency discharge current oscillations in Hall accelerators are conventionally damped with external inductor-capacitor (LC) or resistor-inductor-capacitor (RLC) networks. The role of such network in the stabilization of the plasma discharge is investigated with a numerical model and the potential advantages of proportional-integral-derivative (PID) closed-loop control over RLC networks are subsequently assessed using either discharge voltage or magnetic field modulation. Simulations confirm the reduction of current oscillations in the presence of a RLC network, but suggest that PID control could ensure nearly oscillation-free operation with little sensitivity toward the PID settings.

  15. Estimation of complex permittivity using loop antenna

    DEFF Research Database (Denmark)

    Lenler-Eriksen, Hans-Rudolph; Meincke, Peter

    2004-01-01

    A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna.......A method for estimating the complex permittivity of materials in the vicinity of a loop antenna is proposed. The method is based on comparing measured and numerically calculated input admittances for the loop antenna....

  16. A True Open-Loop Synchronization Technique

    DEFF Research Database (Denmark)

    Golestan, Saeed; Vidal, Ana; Yepes, Alejandro G.

    2016-01-01

    Synchronization techniques can be broadly classified into two major categories: Closed-loop and open-loop methods. The open-loop synchronization (OLS) techniques, contrary to the closed-loop ones, are unconditionally stable and benefit from a fast dynamic response. Their performance, however, tends...... is to develop a true OLS (and therefore, unconditionally stable) technique without any need for the calculation of sine and cosine functions. The effectiveness of the proposed synchronization technique is confirmed through the simulation and experimental results....

  17. Externalities - an analysis using the EU ExternE-results

    International Nuclear Information System (INIS)

    2003-10-01

    The EU project ExternE quantified the externalities for the different energy technologies. In this work, the ExternE results are used in a MARKAL-analysis for the Nordic countries. The analysis does not go into detail, but gives some interesting indications: The external costs are not fully covered in the Nordic energy systems, the present taxes and charges are not high enough. The emissions from the energy systems would be strongly reduced, if taxes/environmental charges were set at the level ExternE calculate. The emissions from power production would be reduced most. Renewable energy sources and natural gas dominate the energy systems in the ExternE case

  18. HYDROXYETHYL METHACRYLATE BASED NANOCOMPOSITE HYDROGELS WITH TUNABLE PORE ARCHITECTURE

    Directory of Open Access Journals (Sweden)

    Erhan Bat

    2016-10-01

    Full Text Available Hydroxyethyl methacrylate (HEMA based hydrogels have found increasing number of applications in areas such as chromatographic separations, controlled drug release, biosensing, and membrane separations. In all these applications, the pore size and pore interconnectivity are crucial for successful application of these materials as they determine the rate of diffusion through the matrix. 2-Hydroxyethyl methacrylate is a water soluble monomer but its polymer, polyHEMA, is not soluble in water. Therefore, during polymerization of HEMA in aqueous media, a porous structure is obtained as a result of phase separation. Pore size and interconnectivity in these hydrogels is a function of several variables such as monomer concentration, cross-linker concentration, temperature etc. In this study, we investigated the effect of monomer concentration, graphene oxide addition or clay addition on hydrogel pore size, pore interconnectivity, water uptake, and thermal properties. PolyHEMA hydrogels have been prepared by redox initiated free radical polymerization of the monomer using ethylene glycol dimethacrylate as a cross-linker. As a nanofiller, a synthetic hectorite Laponite® XLG and graphene oxide were used. Graphene oxide was prepared by the Tour Method. Pore morphology of the pristine HEMA based hydrogels and nanocomposite hydrogels were studied by scanning electron microscopy. The formed hydrogels were found to be highly elastic and flexible. A dramatic change in the pore structure and size was observed in the range between 22 to 24 wt/vol monomer at 0.5 % of cross-linker. In this range, the hydrogel morphology changes from typical cauliflower architecture to continuous hydrogel with dispersed water droplets forming the pores where the pores are submicron in size and show an interconnected structure. Such controlled pore structure is highly important when these hydrogels are used for solute diffusion or when there’s flow through monolithic hydrogels

  19. X-ray CT analysis of pore structure in sand

    Science.gov (United States)

    Mukunoki, Toshifumi; Miyata, Yoshihisa; Mikami, Kazuaki; Shiota, Erika

    2016-06-01

    The development of microfocused X-ray computed tomography (CT) devices enables digital imaging analysis at the pore scale. The applications of these devices are diverse in soil mechanics, geotechnical and geoenvironmental engineering, petroleum engineering, and agricultural engineering. In particular, the imaging of the pore space in porous media has contributed to numerical simulations for single-phase and multiphase flows or contaminant transport through the pore structure as three-dimensional image data. These obtained results are affected by the pore diameter; therefore, it is necessary to verify the image preprocessing for the image analysis and to validate the pore diameters obtained from the CT image data. Moreover, it is meaningful to produce the physical parameters in a representative element volume (REV) and significant to define the dimension of the REV. This paper describes the underlying method of image processing and analysis and discusses the physical properties of Toyoura sand for the verification of the image analysis based on the definition of the REV. On the basis of the obtained verification results, a pore-diameter analysis can be conducted and validated by a comparison with the experimental work and image analysis. The pore diameter is deduced from Young-Laplace's law and a water retention test for the drainage process. The results from previous study and perforated-pore diameter originally proposed in this study, called the voxel-percolation method (VPM), are compared in this paper. In addition, the limitations of the REV, the definition of the pore diameter, and the effectiveness of the VPM for an assessment of the pore diameter are discussed.

  20. Surfactant-enhanced control of track-etch pore morphology

    International Nuclear Information System (INIS)

    Apel', P.Yu.; Blonskaya, I.V.; Didyk, A.Yu.; Dmitriev, S.N.; Orelovich, O.L.; Samojlova, L.I.; Vutsadakis, V.A.; Root, D.

    2000-01-01

    The influence of surfactants on the process of chemical development of ion tracks in polymers is studied. Based on the experimental data, a mechanism of the surfactant effect on the track-etch pore morphology is proposed. In the beginning of etching the surfactant is adsorbed on the surface and creates a layer that is quasi-solid and partially protects the surface from the etching agent. However, some etchant molecules diffuse through the barrier and react with the polymer surface. This results in the formation of a small hole at the entrance to the ion track. After the hole has attained a few annometers in diameter, the surfactant molecules penetrate into the track and cover its walls. Further diffusion of the surfactant into the growing pore is hindered. The adsorbed surfactant layer is not permeable for large molecules. In contrast, small alkali molecules and water molecules diffuse into the track and provide the etching process enlarging the pore. At this stage the transport of the surfactant into the pore channel can proceed only due to the lateral diffusion in the adsorbed layer. The volume inside the pore is free of surfactant molecules and grows at a higher rate than pore entrance. After a more prolonged etching the bottle-like (or 'cigar-like') pore channels are formed. The bottle-like shape of the pore channels depends on the etching conditions such as alkali and surfactant concentration, temperature, and type of the surfactant. The use of surfactants enables one to produce track-etch membranes with improved flow rate characteristics compared with those having cylindrical pores with the same nominal pore diameters

  1. External costs of electricity

    International Nuclear Information System (INIS)

    Rabl, A.; Spadaro, J.V.

    2005-01-01

    This article presents a synthesis of the ExternE project (External costs of Energy) of the European community about the external costs of power generation. Pollution impacts are calculated using an 'impact pathways' analysis, i.e. an analysis of the emission - dispersion - dose-response function - cost evaluation chain. Results are presented for different fuel cycles (with several technological variants) with their confidence intervals. The environmental impact costs are particularly high for coal: for instance, in France, for coal-fired power plants it is of the same order as the electricity retail price. For natural gas, this cost is about a third of the one for coal. On the contrary, the environmental impact costs for nuclear and renewable energies are low, typically of few per cent of the electricity price. The main part of these costs corresponds to the sanitary impacts, in particular the untimely mortality. In order to avoid any controversy about the cost evaluation of mortality, the reduction of the expectation of life due to the different fuel cycles is also indicated and the risks linked with nuclear energy are presented using several comparisons. (J.S.)

  2. On parabolic external maps

    DEFF Research Database (Denmark)

    Lomonaco, Luna; Petersen, Carsten Lunde; Shen, Weixiao

    2017-01-01

    We prove that any C1+BV degree d ≥ 2 circle covering h having all periodic orbits weakly expanding, is conjugate by a C1+BV diffeomorphism to a metrically expanding map. We use this to connect the space of parabolic external maps (coming from the theory of parabolic-like maps) to metrically expan...

  3. Stochastic Control - External Models

    DEFF Research Database (Denmark)

    Poulsen, Niels Kjølstad

    2005-01-01

    This note is devoted to control of stochastic systems described in discrete time. We are concerned with external descriptions or transfer function model, where we have a dynamic model for the input output relation only (i.e.. no direct internal information). The methods are based on LTI systems...

  4. Automation of loop amplitudes in numerical approach

    International Nuclear Information System (INIS)

    Fujimoto, J.; Ishikawa, T.; Shimizu, Y.; Kato, K.; Nakazawa, N.; Kaneko, T.

    1997-01-01

    An automatic calculating system GRACE-L1 of one-loop Feynman amplitude is reviewed. This system can be applied to 2 to 2-body one-loop processes. A sample calculation of 2 to 3-body one-loop amplitudes is also presented. (orig.)

  5. Two-loop operator matrix elements for massive fermionic local twist-2 operators in QED

    International Nuclear Information System (INIS)

    Bluemlein, J.; Freitas, A. de; Universidad Simon Bolivar, Caracas; Neerven, W.L. van

    2011-11-01

    We describe the calculation of the two--loop massive operator matrix elements with massive external fermions in QED. We investigate the factorization of the O(α 2 ) initial state corrections to e + e - annihilation into a virtual boson for large cms energies s >>m 2 e into massive operator matrix elements and the massless Wilson coefficients of the Drell-Yan process adapting the color coefficients to the case of QED, as proposed by F. A. Berends et. al. (Nucl. Phys. B 297 (1988)429). Our calculations show explicitly that the representation proposed there works at one-loop order and up to terms linear in ln (s/m 2 e ) at two-loop order. However, the two-loop constant part contains a few structural terms, which have not been obtained in previous direct calculations. (orig.)

  6. A statistical image analysis framework for pore-free islands derived from heterogeneity distribution of nuclear pore complexes.

    Science.gov (United States)

    Mimura, Yasuhiro; Takemoto, Satoko; Tachibana, Taro; Ogawa, Yutaka; Nishimura, Masaomi; Yokota, Hideo; Imamoto, Naoko

    2017-11-24

    Nuclear pore complexes (NPCs) maintain cellular homeostasis by mediating nucleocytoplasmic transport. Although cyclin-dependent kinases (CDKs) regulate NPC assembly in interphase, the location of NPC assembly on the nuclear envelope is not clear. CDKs also regulate the disappearance of pore-free islands, which are nuclear envelope subdomains; this subdomain gradually disappears with increase in homogeneity of the NPC in response to CDK activity. However, a causal relationship between pore-free islands and NPC assembly remains unclear. Here, we elucidated mechanisms underlying NPC assembly from a new perspective by focusing on pore-free islands. We proposed a novel framework for image-based analysis to automatically determine the detailed 'landscape' of pore-free islands from a large quantity of images, leading to the identification of NPC intermediates that appear in pore-free islands with increased frequency in response to CDK activity. Comparison of the spatial distribution between simulated and the observed NPC intermediates within pore-free islands showed that their distribution was spatially biased. These results suggested that the disappearance of pore-free islands is highly related to de novo NPC assembly and indicated the existence of specific regulatory mechanisms for the spatial arrangement of NPC assembly on nuclear envelopes.

  7. Fluctuation current in superconducting loops

    International Nuclear Information System (INIS)

    Berger, Jorge

    2012-01-01

    A superconducting loop that encloses noninteger flux holds a permanent current. On the average, this current is also present above T c , and has been measured in recent years. We are able to evaluate the permanent current within the TDGL or the Kramer-Watts-Tobin models for loops of general configuration, i.e., we don't require uniform cross section, material or temperature. We can also consider situations in which the width is not negligible in comparison to the radius. Our results agree with experiments. The situations with which we deal at present include fluctuation superconductivity in two-band superconductors, equilibrium thermal fluctuations of supercurrent along a weak link, and ratchet effects.

  8. Loop connectors in dentogenic diastema

    Directory of Open Access Journals (Sweden)

    Sanjna Nayar

    2015-01-01

    Full Text Available Patients with a missing tooth along with diastema have limited treatment options to restore the edentulous space. The use of a conventional fixed partial denture (FPD to replace the missing tooth may result in too wide anterior teeth leading to poor esthetics. Loss of anterior teeth with existing diastema may result in excess space available for pontic. This condition presents great esthetic challenge for prosthodontist. If implant supported prosthesis is not possible because of inadequate bone support, FPD along with loop connector may be a treatment option to maintain the diastema and provide optimal esthetic restoration. Here, we report a clinical case where FPD along with loop connector was used to achieve esthetic rehabilitation in maxillary anterior region in which midline diastema has been maintained.

  9. Functional Architecture of the Cytoplasmic Entrance to the Cystic Fibrosis Transmembrane Conductance Regulator Chloride Channel Pore.

    Science.gov (United States)

    El Hiani, Yassine; Linsdell, Paul

    2015-06-19

    As an ion channel, the cystic fibrosis transmembrane conductance regulator must form a continuous pathway for the movement of Cl(-) and other anions between the cytoplasm and the extracellular solution. Both the structure and the function of the membrane-spanning part of this pathway are well defined. In contrast, the structure of the pathway that connects the cytoplasm to the membrane-spanning regions is unknown, and functional roles for different parts of the protein forming this pathway have not been described. We used patch clamp recording and substituted cysteine accessibility mutagenesis to identify positively charged amino acid side chains that attract cytoplasmic Cl(-) ions to the inner mouth of the pore. Our results indicate that the side chains of Lys-190, Arg-248, Arg-303, Lys-370, Lys-1041, and Arg-1048, located in different intracellular loops of the protein, play important roles in the electrostatic attraction of Cl(-) ions. Mutation and covalent modification of these residues have charge-dependent effects on the rate of Cl(-) permeation, demonstrating their functional role in maximization of Cl(-) flux. Other nearby positively charged side chains were not involved in electrostatic interactions with Cl(-). The location of these Cl(-)-attractive residues suggests that cytoplasmic Cl(-) ions enter the pore via a lateral portal located between the cytoplasmic extensions to the fourth and sixth transmembrane helices; a secondary, functionally less relevant portal might exist between the extensions to the 10th and 12th transmembrane helices. These results define the cytoplasmic mouth of the pore and show how it attracts Cl(-) ions from the cytoplasm. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. Impact of pore-pressure cycling on bentonite in constant volume experiments

    International Nuclear Information System (INIS)

    Graham, C.C.; Harrington, J.F.; Cuss, R.J.; Sellin, P.

    2012-01-01

    Document available in extended abstract form only. The SKB safety case for a KBS-3 repository highlights the potential importance of future successive glaciation events on repository functions. One particular uncertainty is the likely affect of elevated pore-water pressures on barrier safety functions. Over the repository lifetime such changes in pore-water pressure are likely to be cyclic in nature, as successive glacial episodes lead to loading and unloading of the engineered barrier. For a clay-water system with the pore-water in thermodynamic equilibrium with an external reservoir of water at pressure, p w , the total stress acting on the surrounding vessel can be expressed as: (1) σ = Π + αp w where Π is the swelling pressure and α is a proportionality constant. We present results from a series of laboratory experiments designed to investigate this relationship, in the context of glacial loading. Blocks of pre-compacted Mx80 bentonite were manufactured by Clay Technology AB (Lund, Sweden), by rapidly compacting bentonite granules in a mould under a one dimensionally applied stress (Johannesson et al., 1995). The blocks were then sub-sampled and cylindrical specimens prepared for testing (120 mm in length and 60 mm in diameter). The experiments were conducted using a specially designed constant volume cell, which allows the evolution of the total stresses acting on the surrounding vessel to be monitored during clay swelling (at three radial and two axial locations). A high precision syringe pump was used to maintain a constant applied pore pressure within the bentonite, while the rate of hydraulic inflow, and consequent stress development, were monitored to determine the point at which hydraulic equilibrium was reached. During the tests each sample was subjected to an incremental series of constant pore-pressure steps, with all samples experiencing at least one loading and unloading cycle. The resulting average total stress data yield alpha values in the

  11. In pile helium loop ''COMEDIE''

    International Nuclear Information System (INIS)

    Abassin, J.J.; Blanchard, R.J.; Gentil, J.

    1981-01-01

    The SR1 test in the COMEDIE loop has permitted to demonstrate particularly the device operation reliability with a fuel loading. The post-irradiation examinations have pointed out the good filter efficiency and have enabled to determine the deposition profiles either for the activation products (e.g.: 51 Cr, 60 Co) or for the fission products (e.g.: sup(110m)Ag, 131 I, 134 Cs, 137 Cs). (author)

  12. Closed Loop Experiment Manager (CLEM—An Open and Inexpensive Solution for Multichannel Electrophysiological Recordings and Closed Loop Experiments

    Directory of Open Access Journals (Sweden)

    Hananel Hazan

    2017-10-01

    Full Text Available There is growing need for multichannel electrophysiological systems that record from and interact with neuronal systems in near real-time. Such systems are needed, for example, for closed loop, multichannel electrophysiological/optogenetic experimentation in vivo and in a variety of other neuronal preparations, or for developing and testing neuro-prosthetic devices, to name a few. Furthermore, there is a need for such systems to be inexpensive, reliable, user friendly, easy to set-up, open and expandable, and possess long life cycles in face of rapidly changing computing environments. Finally, they should provide powerful, yet reasonably easy to implement facilities for developing closed-loop protocols for interacting with neuronal systems. Here, we survey commercial and open source systems that address these needs to varying degrees. We then present our own solution, which we refer to as Closed Loop Experiments Manager (CLEM. CLEM is an open source, soft real-time, Microsoft Windows desktop application that is based on a single generic personal computer (PC and an inexpensive, general-purpose data acquisition board. CLEM provides a fully functional, user-friendly graphical interface, possesses facilities for recording, presenting and logging electrophysiological data from up to 64 analog channels, and facilities for controlling external devices, such as stimulators, through digital and analog interfaces. Importantly, it includes facilities for running closed-loop protocols written in any programming language that can generate dynamic link libraries (DLLs. We describe the application, its architecture and facilities. We then demonstrate, using networks of cortical neurons growing on multielectrode arrays (MEA that despite its reliance on generic hardware, its performance is appropriate for flexible, closed-loop experimentation at the neuronal network level.

  13. Pore Scale Dynamics of Microemulsion Formation.

    Science.gov (United States)

    Unsal, Evren; Broens, Marc; Armstrong, Ryan T

    2016-07-19

    Experiments in various porous media have shown that multiple parameters come into play when an oleic phase is displaced by an aqueous solution of surfactant. In general, the displacement efficiency is improved when the fluids become quasi-miscible. Understanding the phase behavior oil/water/surfactant systems is important because microemulsion has the ability to generate ultralow interfacial tension (microemulsion formation and the resulting properties under equilibrium conditions. However, the majority of applications where microemulsion is present also involve flow, which has received relatively less attention. It is commonly assumed that the characteristics of an oil/water/surfactant system under flowing conditions are identical to the one under equilibrium conditions. Here, we show that this is not necessarily the case. We studied the equilibrium phase behavior of a model system consisting of n-decane and an aqueous solution of olefin sulfonate surfactant, which has practical applications for enhanced oil recovery. The salt content of the aqueous solution was varied to provide a range of different microemulsion compositions and oil-water interfacial tensions. We then performed microfluidic flow experiments to study the dynamic in situ formation of microemulsion by coinjecting bulk fluids of n-decane and surfactant solution into a T-junction capillary geometry. A solvatochromatic fluorescent dye was used to obtain spatially resolved compositional information. In this way, we visualized the microemulsion formation and the flow of it along with the excess phases. A complex interaction between the flow patterns and the microemulsion properties was observed. The formation of microemulsion influenced the flow regimes, and the flow regimes affected the characteristics of the microemulsion formation. In particular, at low flow rates, slug flow was observed, which had profound consequences on the pore scale mixing behavior and resulting microemulsion properties.

  14. Dispersion relations in loop calculations

    International Nuclear Information System (INIS)

    Kniehl, B.A.

    1996-01-01

    These lecture notes give a pedagogical introduction to the use of dispersion relations in loop calculations. We first derive dispersion relations which allow us to recover the real part of a physical amplitude from the knowledge of its absorptive part along the branch cut. In perturbative calculations, the latter may be constructed by means of Cutkosky's rule, which is briefly discussed. For illustration, we apply this procedure at one loop to the photon vacuum-polarization function induced by leptons as well as to the γf anti-f vertex form factor generated by the exchange of a massive vector boson between the two fermion legs. We also show how the hadronic contribution to the photon vacuum polarization may be extracted from the total cross section of hadron production in e + e - annihilation measured as a function of energy. Finally, we outline the application of dispersive techniques at the two-loop level, considering as an example the bosonic decay width of a high-mass Higgs boson. (author)

  15. Identification and validation of a linear protective neutralizing epitope in the β-pore domain of alpha toxin.

    Science.gov (United States)

    Oscherwitz, Jon; Cease, Kemp B

    2015-01-01

    The plethora of virulence factors associated with Staphylococcus aureus make this bacterium an attractive candidate for a molecularly-designed epitope-focused vaccine. This approach, which necessitates the identification of neutralizing epitopes for incorporation into a vaccine construct, is being evaluated for pathogens where conventional approaches have failed to elicit protective humoral responses, like HIV-1 and malaria, but may also hold promise for pathogens like S. aureus, where the elicitation of humoral immunity against multiple virulence factors may be required for development of an effective vaccine. Among the virulence factors employed by S. aureus, animal model and epidemiological data suggest that alpha toxin, a multimeric β-pore forming toxin like protective antigen from Bacillus anthracis, is particularly critical, yet no candidate neutralizing epitopes have been delineated in alpha toxin to date. We have previously shown that a linear determinant in the 2β2-2β3 loop of the pore forming domain of B. anthracis protective antigen is a linear neutralizing epitope. Antibody against this site is highly potent for neutralizing anthrax lethal toxin in vitro and for protection of rabbits in vivo from virulent B. anthracis. We hypothesized that sequences in the β-pore of S. aureus alpha toxin that share structural and functional homology to β-pore sequences in protective antigen would contain a similarly critical neutralizing epitope. Using an in vivo mapping strategy employing peptide immunogens, an optimized in vitro toxin neutralization assay, and an in vivo dermonecrosis model, we have now confirmed the presence of this epitope in alpha toxin, termed the pore neutralizing determinant. Antibody specific for this determinant neutralizes alpha toxin in vitro, and is highly effective for mitigating dermonecrosis and bacterial growth in a mouse model of S. aureus USA300 skin infection. The delineation of this linear neutralizing determinant in alpha

  16. Identification and validation of a linear protective neutralizing epitope in the β-pore domain of alpha toxin.

    Directory of Open Access Journals (Sweden)

    Jon Oscherwitz

    Full Text Available The plethora of virulence factors associated with Staphylococcus aureus make this bacterium an attractive candidate for a molecularly-designed epitope-focused vaccine. This approach, which necessitates the identification of neutralizing epitopes for incorporation into a vaccine construct, is being evaluated for pathogens where conventional approaches have failed to elicit protective humoral responses, like HIV-1 and malaria, but may also hold promise for pathogens like S. aureus, where the elicitation of humoral immunity against multiple virulence factors may be required for development of an effective vaccine. Among the virulence factors employed by S. aureus, animal model and epidemiological data suggest that alpha toxin, a multimeric β-pore forming toxin like protective antigen from Bacillus anthracis, is particularly critical, yet no candidate neutralizing epitopes have been delineated in alpha toxin to date. We have previously shown that a linear determinant in the 2β2-2β3 loop of the pore forming domain of B. anthracis protective antigen is a linear neutralizing epitope. Antibody against this site is highly potent for neutralizing anthrax lethal toxin in vitro and for protection of rabbits in vivo from virulent B. anthracis. We hypothesized that sequences in the β-pore of S. aureus alpha toxin that share structural and functional homology to β-pore sequences in protective antigen would contain a similarly critical neutralizing epitope. Using an in vivo mapping strategy employing peptide immunogens, an optimized in vitro toxin neutralization assay, and an in vivo dermonecrosis model, we have now confirmed the presence of this epitope in alpha toxin, termed the pore neutralizing determinant. Antibody specific for this determinant neutralizes alpha toxin in vitro, and is highly effective for mitigating dermonecrosis and bacterial growth in a mouse model of S. aureus USA300 skin infection. The delineation of this linear neutralizing

  17. One-loop tensor integrals in dimensional regularisation

    International Nuclear Information System (INIS)

    Campbell, J.M.; Glover, E.W.N.; Miller, D.J.

    1997-01-01

    We show how to evaluate tensor one-loop integrals in momentum space avoiding the usual plague of Gram determinants. We do this by constructing combinations of n- and (n-1)-point scalar integrals that are finite in the limit of vanishing Gram determinant. These non-trivial combinations of dilogarithms, logarithms and constants are systematically obtained by either differentiating with respect to the external parameters - essentially yielding scalar integrals with Feynman parameters in the numerator - or by developing the scalar integral in D=6-2ε or higher dimensions. An additional advantage is that other spurious kinematic singularities are also controlled. As an explicit example, we develop the tensor integrals and associated scalar integral combinations for processes where the internal particles are massless and where up to five (four massless and one massive) external particles are involved. For more general processes, we present the equations needed for deriving the relevant combinations of scalar integrals. (orig.)

  18. Study of phosphate release from Bogor botanical gardens’ sediment into pore water using diffusive gradient in thin film (DGT)

    Science.gov (United States)

    Tirta, A. P.; Saefumillah, A.; Foliatini

    2017-04-01

    Eutrophication is one of the environmental problems caused by the excessive nutrients in aquatic ecosystems. In most lakes, phosphate is a limiting nutrient for algae photosynthesis. Even though the concentration of phosphate from external loading into the water body has been reduced, eutrophication could still be occured due to internal mobilization of phosphate from the sediment pore water into the overlying water. Therefore, the released phosphate from sediments and their interaction in the pore water must be included in the monitoring of phosphate concentration in aquatic system. The released phosphate from sediment into pore water has been studied by DGT device with ferrihydrite as binding gel and N-N‧-methylenebisacrylamide as crosslinker. The results showed that DGT with 15% acrylamide; 0.1 % N-N‧-methylenebisacrylamide and ferrihydrite as binding gel was suitable for the measurement of the released phosphate from sediment into pore water. The result of the deployed DGT in oxic and anoxic conditions in seven days incubation showed the released phosphate process from the sediment into pore water was affected by incubation time and the existence of oxygen in the environment. The released phosphate from the sediment into pore water in anoxic condition has a higher value than oxic condition. The experimental results of the deployed DGT in natural sediment core at a depth of 1 to 15 cm from the surface of the water for 7 days showed that the sediment has a different phosphate mass profile based on depth. The concentration of phosphate tends to be increased with depth. The maximum CDGT of phosphate released in oxic and anoxic conditions at 7th day period of incubation are 29.23 μg/L at 14 cm depth and 30.19 μg/L at 8 cm depth, respectively.

  19. Oscillation damping of chiral string loops

    International Nuclear Information System (INIS)

    Babichev, Eugeny; Dokuchaev, Vyacheslav

    2002-01-01

    Chiral cosmic string loops tend to the stationary (vorton) configuration due to energy loss into gravitational and electromagnetic radiation. We describe the asymptotic behavior of near stationary chiral loops and their fading to vortons. General limits on the gravitational and electromagnetic energy losses by near stationary chiral loops are found. For these loops we estimate the oscillation damping time. We present solvable examples of gravitational radiation energy loss by some chiral loop configurations. The analytical dependence of string energy with time is found in the case of the chiral ring with small amplitude radial oscillations

  20. Modular invariance and covariant loop calculus

    International Nuclear Information System (INIS)

    Petersen, J.L.; Roland, K.O.; Sidenius, J.R.

    1988-01-01

    The covariant loop calculus provides and efficient technique for computing explicit expressions for the density on moduli space corresponding to arbitrary (bosonic string) loop diagrams. Since modular invariance is not manifest, however, we carry out a detailed comparison with known explicit 2- and 3- loop results derived using analytic geometry (1 loop is known to be ok). We establish identity to 'high' order in some moduli and exactly in others. Agreement is found as a result of various non-trivial cancellations, in part related to number theory. We feel our results provide very strong support for the correctness of the covariant loop calculus approach. (orig.)

  1. Algorithm for counting large directed loops

    Energy Technology Data Exchange (ETDEWEB)

    Bianconi, Ginestra [Abdus Salam International Center for Theoretical Physics, Strada Costiera 11, 34014 Trieste (Italy); Gulbahce, Natali [Theoretical Division and Center for Nonlinear Studies, Los Alamos National Laboratory, NM 87545 (United States)

    2008-06-06

    We derive a Belief-Propagation algorithm for counting large loops in a directed network. We evaluate the distribution of the number of small loops in a directed random network with given degree sequence. We apply the algorithm to a few characteristic directed networks of various network sizes and loop structures and compare the algorithm with exhaustive counting results when possible. The algorithm is adequate in estimating loop counts for large directed networks and can be used to compare the loop structure of directed networks and their randomized counterparts.

  2. Functional Fourier transforms and the loop equation

    International Nuclear Information System (INIS)

    Bershadskii, M.A.; Vaisburd, I.D.; Migdal, A.A.

    1986-01-01

    The Migdal-Makeenko momentum-space loop equation is investigated. This equation is derived from the ordinary loop equation by taking the Fourier transform of the Wilson functional. A perturbation theory is constructed for the new equation and it is proved that the action of the loop operator is determined by vertex functions which coincide with those of the previous equation. It is shown how the ghost loop arises in direct iterations of the momentum-space equation with respect to the coupling constant. A simple example is used to illustrate the mechanism of appearance of an integration in the interior loops in transition to observables

  3. Modular invariance and covariant loop calculus

    International Nuclear Information System (INIS)

    Petersen, J.L.; Roland, K.O.; Sidenius, J.R.

    1988-01-01

    The covariant loop calculus provides an efficient technique for computing explicit expressions for the density on moduli space corresponding to arbitrary (bosonic string) loop diagrams. Since modular invariance is not manifest, however, we carry out a detailed comparison with known explicit two- and three-loop results derived using analytic geometry (one loop is known to be okay). We establish identity to 'high' order in some moduli and exactly in others. Agreement is found as a result of various nontrivial cancellations, in part related to number theory. We feel our results provide very strong support for the correctness of the covariant loop calculus approach. (orig.)

  4. Superplastically foaming method to make closed pores inclusive porous ceramics

    International Nuclear Information System (INIS)

    Kishimoto, Akira; Hayashi, Hidetaka

    2011-01-01

    Porous ceramics incorporates pores to improve several properties including thermal insulation maintaining inherenet ceramic properties such as corrosion resistance and large mechanical strength. Conventional porous ceramics is usually fabricated through an insufficient sintering. Since the sintering accompanies the exclusion of pores, it must be terminated at the early stage to maintain the high porosity, leading to degraded strength and durability. Contrary to this, we have innovated superplastically foaming method to make ceramic foams only in the solid state. In this method, the previously inserted foam agent evaporates after the full densification of matrix at around the sintering temperature. Closed pores expand utilizing the superplastic deformation driven by the evolved gas pressure. The typical features of this superplastically foaming method are listed as follows, 1. The pores are introduced after sintering the solid polycrystal. 2. Only closed pores are introduced, improving the insulation of gas and sound in addition to heat. 3. The pore walls are fully densified expecting a large mechanical strength. 4. Compared with the melt foaming method, this method is practical because the fabrication temperature is far below the melting point and it does not need molds. 5. The size and the location pores can be controlled by the amount and position of the foam agent.

  5. Pore formation by actinoporins, cytolysins from sea anemones.

    Science.gov (United States)

    Rojko, Nejc; Dalla Serra, Mauro; Maček, Peter; Anderluh, Gregor

    2016-03-01

    Actinoporins (APs) from sea anemones are ~20 kDa pore forming toxins with a β-sandwich structure flanked by two α-helices. The molecular mechanism of APs pore formation is composed of several well-defined steps. APs bind to membrane by interfacial binding site composed of several aromatic amino acid residues that allow binding to phosphatidylcholine and specific recognition of sphingomyelin. Subsequently, the N-terminal α-helix from the β-sandwich has to be inserted into the lipid/water interphase in order to form a functional pore. Functional studies and single molecule imaging revealed that only several monomers, 3-4, oligomerise to form a functional pore. In this model the α-helices and surrounding lipid molecules build toroidal pore. In agreement, AP pores are transient and electrically heterogeneous. On the contrary, crystallized oligomers of actinoporin fragaceatoxin C were found to be composed of eight monomers with no lipids present between the adjacent α-helices. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Maur Dalla Serra and Franco Gambale. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Nuclear Pore-Like Structures in a Compartmentalized Bacterium.

    Directory of Open Access Journals (Sweden)

    Evgeny Sagulenko

    Full Text Available Planctomycetes are distinguished from other Bacteria by compartmentalization of cells via internal membranes, interpretation of which has been subject to recent debate regarding potential relations to Gram-negative cell structure. In our interpretation of the available data, the planctomycete Gemmata obscuriglobus contains a nuclear body compartment, and thus possesses a type of cell organization with parallels to the eukaryote nucleus. Here we show that pore-like structures occur in internal membranes of G.obscuriglobus and that they have elements structurally similar to eukaryote nuclear pores, including a basket, ring-spoke structure, and eight-fold rotational symmetry. Bioinformatic analysis of proteomic data reveals that some of the G. obscuriglobus proteins associated with pore-containing membranes possess structural domains found in eukaryote nuclear pore complexes. Moreover, immunogold labelling demonstrates localization of one such protein, containing a β-propeller domain, specifically to the G. obscuriglobus pore-like structures. Finding bacterial pores within internal cell membranes and with structural similarities to eukaryote nuclear pore complexes raises the dual possibilities of either hitherto undetected homology or stunning evolutionary convergence.

  7. Impedance nanopore biosensor: influence of pore dimensions on biosensing performance.

    Science.gov (United States)

    Kant, Krishna; Yu, Jingxian; Priest, Craig; Shapter, Joe G; Losic, Dusan

    2014-03-07

    Knowledge about electrochemical and electrical properties of nanopore structures and the influence of pore dimensions on these properties is important for the development of nanopore biosensing devices. The aim of this study was to explore the influence of nanopore dimensions (diameter and length) on biosensing performance using non-faradic electrochemical impedance spectroscopy (EIS). Nanoporous alumina membranes (NPAMs) prepared by self-ordered electrochemical anodization of aluminium were used as model nanopore sensing platforms. NPAMs with different pore diameters (25-65 nm) and lengths (4-18 μm) were prepared and the internal pore surface chemistry was modified by covalently attaching streptavidin and biotin. The performance of this antibody nanopore biosensing platform was evaluated using various concentrations of biotin as a model analyte. EIS measurements of pore resistivity and conductivity were carried out for pores with different diameters and lengths. The results showed that smaller pore dimensions of 25 nm and pore lengths up to 10 μm provide better biosensing performance.

  8. Robust H-infinity control in CD players to suppress external disturbances and defects on the disk

    DEFF Research Database (Denmark)

    Vidal, E.; Andersen, B.; Karlsson, R.V.

    2000-01-01

    This paper deals with the design and implementation of robust H8 controllers in order to suppress external disturbances and defects on the disk. Due to the conflictive requirements concerning the bandwidth of the closed loop to suppress external disturbances and defects on the disk, two independe...

  9. Novel Techniques to Characterize Pore Size of Porous Materials

    KAUST Repository

    Alabdulghani, Ali J.

    2016-01-01

    Porous materials are implemented in several industrial applications such as water desalination, gas separation and pharmaceutical care which they are mainly governed by the pore size and the PSD. Analyzing shale reservoirs are not excluded from these applications and numerous advantages can be gained by evaluating the PSD of a given shale reservoir. Because of the limitations of the conventional characterization techniques, novel methods for characterizing the PSD have to be proposed in order to obtain better characterization results for the porous materials, in general, and shale rocks in particular. Thus, permporosimetry and evapoporometry (EP) technologies were introduced, designed and utilized for evaluating the two key parameters, pore size and pore size distribution. The pore size and PSD profiles of different shale samples from Norway and Argentina were analyzed using these technologies and then confirmed by mercury intrusion porosimeter (MIP). Norway samples showed an average pore diameter of 12.94 nm and 19.22 nm with an average diameter of 13.77 nm and 23.23 nm for Argentina samples using permporosimetry and EP respectively. Both techniques are therefore indicative of the heterogeneity of the shales. The results from permporosimetry are in good agreement with those obtained from MIP technique, but EP for most part over-estimates the average pore size. The divergence of EP results compared to permporosimetry results is referred to the fact that the latter technique measures only the active pores which is not the case with the former technique. Overall, both techniques are complementary to each other which the results from both techniques seem reasonable and reliable and provide two simple techniques to estimate the pore size and pore size distributions for shale rocks.

  10. Novel Techniques to Characterize Pore Size of Porous Materials

    KAUST Repository

    Alabdulghani, Ali J.

    2016-04-24

    Porous materials are implemented in several industrial applications such as water desalination, gas separation and pharmaceutical care which they are mainly governed by the pore size and the PSD. Analyzing shale reservoirs are not excluded from these applications and numerous advantages can be gained by evaluating the PSD of a given shale reservoir. Because of the limitations of the conventional characterization techniques, novel methods for characterizing the PSD have to be proposed in order to obtain better characterization results for the porous materials, in general, and shale rocks in particular. Thus, permporosimetry and evapoporometry (EP) technologies were introduced, designed and utilized for evaluating the two key parameters, pore size and pore size distribution. The pore size and PSD profiles of different shale samples from Norway and Argentina were analyzed using these technologies and then confirmed by mercury intrusion porosimeter (MIP). Norway samples showed an average pore diameter of 12.94 nm and 19.22 nm with an average diameter of 13.77 nm and 23.23 nm for Argentina samples using permporosimetry and EP respectively. Both techniques are therefore indicative of the heterogeneity of the shales. The results from permporosimetry are in good agreement with those obtained from MIP technique, but EP for most part over-estimates the average pore size. The divergence of EP results compared to permporosimetry results is referred to the fact that the latter technique measures only the active pores which is not the case with the former technique. Overall, both techniques are complementary to each other which the results from both techniques seem reasonable and reliable and provide two simple techniques to estimate the pore size and pore size distributions for shale rocks.

  11. ExternE transport methodology for external cost evaluation of air pollution

    DEFF Research Database (Denmark)

    Jensen, S. S.; Berkowicz, R.; Brandt, J.

    The report describes how the human exposure estimates based on NERI's human exposure modelling system (AirGIS) can improve the Danish data used for exposure factors in the ExternE Transport methodology. Initially, a brief description of the ExternE Tranport methodology is given and it is summarised...

  12. Hyperstaticity and loops in frictional granular packings

    Science.gov (United States)

    Tordesillas, Antoinette; Lam, Edward; Metzger, Philip T.

    2009-06-01

    The hyperstatic nature of granular packings of perfectly rigid disks is analyzed algebraically and through numerical simulation. The elementary loops of grains emerge as a fundamental element in addressing hyperstaticity. Loops consisting of an odd number of grains behave differently than those with an even number. For odd loops, the latent stresses are exterior and are characterized by the sum of frictional forces around each loop. For even loops, the latent stresses are interior and are characterized by the alternating sum of frictional forces around each loop. The statistics of these two types of loop sums are found to be Gibbsian with a "temperature" that is linear with the friction coefficient μ when μ<1.

  13. Checklists for external validity

    DEFF Research Database (Denmark)

    Dyrvig, Anne-Kirstine; Kidholm, Kristian; Gerke, Oke

    2014-01-01

    to an implementation setting. In this paper, currently available checklists on external validity are identified, assessed and used as a basis for proposing a new improved instrument. METHOD: A systematic literature review was carried out in Pubmed, Embase and Cinahl on English-language papers without time restrictions....... The retrieved checklist items were assessed for (i) the methodology used in primary literature, justifying inclusion of each item; and (ii) the number of times each item appeared in checklists. RESULTS: Fifteen papers were identified, presenting a total of 21 checklists for external validity, yielding a total...... of 38 checklist items. Empirical support was considered the most valid methodology for item inclusion. Assessment of methodological justification showed that none of the items were supported empirically. Other kinds of literature justified the inclusion of 22 of the items, and 17 items were included...

  14. Pore Structures in the Biomineralized Byssus of Anomia simplex

    DEFF Research Database (Denmark)

    Frølich, Simon; Leemreize, Hanna; Thomsen, Jesper Skovhus

    2016-01-01

    that uses a biomineralized byssus to permanently anchor itself to substrates. The byssus has a highly complex hierarchical structure and contains over 90 wt% CaCO3. The byssus features a complex set of porosities, presumed to be highly important for the function of the attachment system. The pore space...... is the main focus of the present work. We characterize the three dimensional distribution of pore spaces in the byssus using micro-computed tomography (µCT) through a combination of in house CT and high-resolution synchrotron CT. The pore structures are observed to fall into distinct categories in various...

  15. Crystalline mesoporous zirconia catalysts having stable tetragonal pore wall structure

    Science.gov (United States)

    Sachtler, W.M.H.; Huang, Y.Y.

    1998-07-28

    Methods are disclosed for the preparation of new sulfated mesoporous zirconia materials/catalysts with crystalline pore walls of predominantly tetragonal crystal structure, characterized by nitrogen physical sorption measurement, X-ray diffraction, transmission electron microscopy and catalytic tests using n-butane isomerization to iso-butane and alkylation of 1-naphthol with 4-tert-butylstyrene as probe reactions. Sulfate deposition is preferred for the transformation of a mesoporous precursor with amorphous pore walls into a material with crystalline pore walls maintaining the mesoporous characteristics. 17 figs.

  16. Tension-induced vesicle fusion: pathways and pore dynamics

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2008-01-01

    and eventually opens a pore to complete the fusion process. In pathway II, at higher tension, a stalk is formed during the fusion process that is then transformed by transmembrane pore formation into a fusion pore. Whereas the latter pathway II resembles stalk pathways as observed in other simulation studies......, fusion pathway I, which does not involve any stalk formation, has not been described previously to the best of our knowledge. A statistical analysis of the various processes shows that fusion is the dominant pathway for releasing the tension of the vesicles. The functional dependence of the observed...

  17. Time evolution of pore system in lime - Pozzolana composites

    Science.gov (United States)

    Doleželová, Magdaléna; Čáchová, Monika; Scheinherrová, Lenka; Keppert, Martin

    2017-11-01

    The lime - pozzolana mortars and plasters are used in restoration works on building cultural heritage but these materials are also following the trend of energy - efficient solutions in civil engineering. Porosity and pore size distribution is one of crucial parameters influencing engineering properties of porous materials. The pore size distribution of lime based system is changing in time due to chemical processes occurring in the material. The present paper describes time evolution of pore system in lime - pozzolana composites; the obtained results are useful in prediction of performance of lime - pozzolana systems in building structures.

  18. Cross-Sectional Information on Pore Structure and Element Distribution of Sediment Particles by SEM and EDS

    Directory of Open Access Journals (Sweden)

    Minghong Chen

    2017-01-01

    Full Text Available The interaction between pollutants and sediment particles often occurs on the particle surface, so surface properties directly affect surface reaction. The physical and chemical processes occurring on sediment particle surfaces are microscopic processes and as such need to be studied from a microscopic perspective. In this study, field emission scanning electron microscopy (SEM and energy dispersive X-ray spectrometer (EDS were adopted to observe and analyze the pore structure and element distribution of sediment particles. In particular, a special method of sample preparation was used to achieve the corresponding cross-sectional information of sediment particles. Clear images of a particle profile and pore microstructure were obtained by high-resolution SEM, while element distribution maps of sediment particles were obtained by EDS. The results provide an intuitive understanding of the internal microenvironment and external behavior of sediment particles, in addition to revealing a significant role of pore microstructure in the adsorption and desorption of pollutants. Thus, a combination of different experimental instruments and observation methods can provide real images and information on microscopic pore structure and element distribution of sediment particles. These results should help to improve our understanding of sediment dynamics and its environmental effects.

  19. 3-D pore-scale resolved model for coupled species/charge/fluid transport in a vanadium redox flow battery

    International Nuclear Information System (INIS)

    Qiu Gang; Joshi, Abhijit S.; Dennison, C.R.; Knehr, K.W.; Kumbur, E.C.; Sun Ying

    2012-01-01

    The vanadium redox flow battery (VRFB) has emerged as a viable grid-scale energy storage technology that offers cost-effective energy storage solutions for renewable energy applications. In this paper, a novel methodology is introduced for modeling of the transport mechanisms of electrolyte flow, species and charge in the VRFB at the pore scale of the electrodes; that is, at the level where individual carbon fiber geometry and electrolyte flow are directly resolved. The detailed geometry of the electrode is obtained using X-ray computed tomography (XCT) and calibrated against experimentally determined pore-scale characteristics (e.g., pore and fiber diameter, porosity, and surface area). The processed XCT data is then used as geometry input for modeling of the electrochemical processes in the VRFB. The flow of electrolyte through the pore space is modeled using the lattice Boltzmann method (LBM) while the finite volume method (FVM) is used to solve the coupled species and charge transport and predict the performance of the VRFB under various conditions. An electrochemical model using the Butler–Volmer equations is used to provide species and charge coupling at the surfaces of the carbon fibers. Results are obtained for the cell potential distribution, as well as local concentration, overpotential and current density profiles under galvanostatic discharge conditions. The cell performance is investigated as a function of the electrolyte flow rate and external drawing current. The model developed here provides a useful tool for building the structure–property–performance relationship of VRFB electrodes.

  20. Hexadecane trapped in nano-pores of silica-aerogel

    International Nuclear Information System (INIS)

    Slavikova, B.; Jesenak, K.; Iskrova, M.; Majernik, V.; Sausa, O.; Kristiak, J.

    2009-01-01

    Ways of filling of the high-porous silica-aerogel with hydrocarbon C 16 H 34 and its efficient removal from the pores by physical method of the Positron Annihilation Spectroscopy were studied. As the most effective way to fill the SiO 2 aerogel appears through the implementation of a liquid phase, while the most appropriate way of removing of hexadecane is firing at an elevated temperature. Molecular system of hexadecane closed in nano-pores of silica-aerogel behaves otherwise than volume system of the same molecules. In the case of pure hexadecane phase transition was observed at 291 K, while solidification process is gradual with decrease of temperature in cetane trapped in pores of silica-aerogel. The results of the periods of life of o-Ps indicate greater turbidity in the pores of the molecular system compared to the volume sample of hexadecane.

  1. A simulation of earthquake induced undrained pore pressure ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Plains, Kandla River and Gulf of Kachch, between .... We consider the role of induced pore pressure ... location of the Bhuj earthquake epicentre as estimated by US Geological Survey. .... war R 2001 Changes in Ocean; GIS @ development 5.

  2. Microfiltration of distillery stillage: Influence of membrane pore size

    Directory of Open Access Journals (Sweden)

    Vasić Vesna M.

    2012-01-01

    Full Text Available Stillage is one of the most polluted waste products of the food industry. Beside large volume, the stillage contains high amount of suspended solids, high values of chemical oxygen demand and biological oxygen demand, so it should not be discharged in the nature before previous purification. In this work, three ceramic membranes for microfiltration with different pore sizes were tested for stillage purification in order to find the most suitable membrane for the filtration process. Ceramic membranes with a nominal pore size of 200 nm, 450 nm and 800 nm were used for filtration. The influence of pore size on permeate flux and removal efficiency was investigated. A membrane with the pore size of 200 nm showed the best filtration performance so it was chosen for the microfiltration process.

  3. Mesoporous Akaganeite of Adjustable Pore Size Synthesized using Mixed Templates

    Science.gov (United States)

    Zhang, Y.; Ge, D. L.; Ren, H. P.; Fan, Y. J.; Wu, L. M.; Sun, Z. X.

    2017-12-01

    Mesoporous akaganeite with large and adjustable pore size was synthesized through a co-template method, which was achieved by the combined interaction between PEG2000 and alkyl amines with different lengths of the straight carbon chain. The characterized results indicate that the synthesized samples show comparatively narrow BJH pore size distributions and centered at 14.3 nm when PEG and HEPA was used, and it could be enlarged to 16.8 and 19.4 nm respectively through changing the alkyl amines to DDA and HDA. Meanwhile, all the synthesized akaganeite possess relativity high specific surface area ranging from 183 to 281 m2/g and high total pore volume of 0.98 to 1.5 cm3/g. A possible mechanism leading to the pore size changing was also proposed.

  4. Loop diagrams without γ matrices

    International Nuclear Information System (INIS)

    McKeon, D.G.C.; Rebhan, A.

    1993-01-01

    By using a quantum-mechanical path integral to compute matrix elements of the form left-angle x|exp(-iHt)|y right-angle, radiative corrections in quantum-field theory can be evaluated without encountering loop-momentum integrals. In this paper we demonstrate how Dirac γ matrices that occur in the proper-time ''Hamiltonian'' H lead to the introduction of a quantum-mechanical path integral corresponding to a superparticle analogous to one proposed recently by Fradkin and Gitman. Direct evaluation of this path integral circumvents many of the usual algebraic manipulations of γ matrices in the computation of quantum-field-theoretical Green's functions involving fermions

  5. Perturbation calculations with Wilson loop

    International Nuclear Information System (INIS)

    Peixoto Junior, L.B.

    1984-01-01

    We present perturbative calculations with the Wilson loop (WL). The dimensional regularization method is used with a special attention concerning to the problem of divergences in the WL expansion in second and fourth orders, in three and four dimensions. We show that the residue in the pole, in 4d, of the fourth order graphs contribution sum is important for the charge renormalization. We compute up to second order the exact expression of the WL, in three-dimensional gauge theories with topological mass as well as its assimptotic behaviour for small and large distances. the author [pt

  6. Light-by-light-type corrections to the muon anomalous magnetic moment at four-loop order

    International Nuclear Information System (INIS)

    Kurz, Alexander; Smirnov, Alexander V.; Smirnov, Vladimir A.

    2015-08-01

    The numerically dominant QED contributions to the anomalous magnetic moment of the muon stem from Feynman diagrams with internal electron loops. We consider such corrections and present a calculation of the four-loop light-by-light-type corrections where the external photon couples to a closed electron or muon loop. We perform an asymptotic expansion in the ratio of electron and muon mass and reduce the resulting integrals to master integrals which we evaluate using analytical and numerical methods. We confirm the results present in the literature which are based on different computational methods.

  7. Closed loop problems in biomechanics. Part II--an optimization approach.

    Science.gov (United States)

    Vaughan, C L; Hay, J G; Andrews, J G

    1982-01-01

    A closed loop problem in biomechanics may be defined as a problem in which there are one or more closed loops formed by the human body in contact with itself or with an external system. Under certain conditions the problem is indeterminate--the unknown forces and torques outnumber the equations. Force transducing devices, which would help solve this problem, have serious drawbacks, and existing methods are inaccurate and non-general. The purposes of the present paper are (1) to develop a general procedure for solving closed loop problems; (2) to illustrate the application of the procedure; and (3) to examine the validity of the procedure. A mathematical optimization approach is applied to the solution of three different closed loop problems--walking up stairs, vertical jumping and cartwheeling. The following conclusions are drawn: (1) the method described is reasonably successful for predicting horizontal and vertical reaction forces at the distal segments although problems exist for predicting the points of application of these forces; (2) the results provide some support for the notion that the human neuromuscular mechanism attempts to minimize the joint torques and thus, to a certain degree, the amount of muscular effort; (3) in the validation procedure it is desirable to have a force device for each of the distal segments in contact with a fixed external system; and (4) the method is sufficiently general to be applied to all classes of closed loop problems.

  8. Diffusion in the pore water of compacted crushed salt

    Energy Technology Data Exchange (ETDEWEB)

    Fluegge, Judith; Herr, Sebastian; Lauke, Thomas; Meleshyn, Artur; Miehe, Ruediger; Ruebel, Andre

    2016-07-15

    Diffusion of dissolved radionuclides in the pore water of compacted crushed salt in the long-term is the most relevant process for the release of radionuclides from a dedicated repository for high-level waste in a salt formation as has been shown in latest safety assessments and research projects /BUH 16/. So far, diffusion coefficients for free water have been applied for the diffusion in pore water in models for long-term safety assessments. This conservative assumption was used, because data on the diffusion coefficient of dissolved substances in crushed salt have been missing. Furthermore, the diffusion coefficient in the pore water was assumed to be constant and independent from the degree of compaction of the crushed salt. The work presented in this report was intended to contribute to fill this gap of knowledge about how the diffusion of radionuclides takes place in the compacted backfill of a repository in salt. For the first time, the pore diffusion coefficient as well as its dependence on the porosity of the crushed salt was determined experimentally by means of through-diffusion experiments using caesium as tracer. The results achieved in this project suggest that the diffusion in compacted crushed salt is not fully comparable to that in a homogeneous, temporally stable porous medium like sand or clay. The results obtained from four diffusion experiments show a remarkably different behaviour and all yield unique concentration versus time plots which includes highly temporal variable tracer fluxes with even full interruptions of the flux for longer periods of time. This effect cannot be explained by assuming a tracer transport by diffusion in a temporarily invariant pore space and / or under temporally invariant experimental conditions. From our point of view, a restructuring of the pore space seems to lead to closed areas of pore water in the sample which may open up again after some time, leading to a variable pore space and hence variable diffusive

  9. Gauge theory loop operators and Liouville theory

    International Nuclear Information System (INIS)

    Drukker, Nadav; Teschner, Joerg

    2009-10-01

    We propose a correspondence between loop operators in a family of four dimensional N=2 gauge theories on S 4 - including Wilson, 't Hooft and dyonic operators - and Liouville theory loop operators on a Riemann surface. This extends the beautiful relation between the partition function of these N=2 gauge theories and Liouville correlators found by Alday, Gaiotto and Tachikawa. We show that the computation of these Liouville correlators with the insertion of a Liouville loop operator reproduces Pestun's formula capturing the expectation value of a Wilson loop operator in the corresponding gauge theory. We prove that our definition of Liouville loop operators is invariant under modular transformations, which given our correspondence, implies the conjectured action of S-duality on the gauge theory loop operators. Our computations in Liouville theory make an explicit prediction for the exact expectation value of 't Hooft and dyonic loop operators in these N=2 gauge theories. The Liouville loop operators are also found to admit a simple geometric interpretation within quantum Teichmueller theory as the quantum operators representing the length of geodesics. We study the algebra of Liouville loop operators and show that it gives evidence for our proposal as well as providing definite predictions for the operator product expansion of loop operators in gauge theory. (orig.)

  10. Gauge theory loop operators and Liouville theory

    Energy Technology Data Exchange (ETDEWEB)

    Drukker, Nadav [Humboldt Univ. Berlin (Germany). Inst. fuer Physik; Gomis, Jaume; Okuda, Takuda [Perimeter Inst. for Theoretical Physics, Waterloo, ON (Canada); Teschner, Joerg [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2009-10-15

    We propose a correspondence between loop operators in a family of four dimensional N=2 gauge theories on S{sup 4} - including Wilson, 't Hooft and dyonic operators - and Liouville theory loop operators on a Riemann surface. This extends the beautiful relation between the partition function of these N=2 gauge theories and Liouville correlators found by Alday, Gaiotto and Tachikawa. We show that the computation of these Liouville correlators with the insertion of a Liouville loop operator reproduces Pestun's formula capturing the expectation value of a Wilson loop operator in the corresponding gauge theory. We prove that our definition of Liouville loop operators is invariant under modular transformations, which given our correspondence, implies the conjectured action of S-duality on the gauge theory loop operators. Our computations in Liouville theory make an explicit prediction for the exact expectation value of 't Hooft and dyonic loop operators in these N=2 gauge theories. The Liouville loop operators are also found to admit a simple geometric interpretation within quantum Teichmueller theory as the quantum operators representing the length of geodesics. We study the algebra of Liouville loop operators and show that it gives evidence for our proposal as well as providing definite predictions for the operator product expansion of loop operators in gauge theory. (orig.)

  11. Pore Structure and Fractal Characteristics of Niutitang Shale from China

    Directory of Open Access Journals (Sweden)

    Zhaodong Xi

    2018-04-01

    Full Text Available A suite of shale samples from the Lower Cambrian Niutitang Formation in northwestern Hunan Province, China, were investigated to better understand the pore structure and fractal characteristics of marine shale. Organic geochemistry, mineralogy by X-ray diffraction, porosity, permeability, mercury intrusion and nitrogen adsorption and methane adsorption experiments were conducted for each sample. Fractal dimension D was obtained from the nitrogen adsorption data using the fractal Frenkel-Halsey-Hill (FHH model. The relationships between total organic carbon (TOC content, mineral compositions, pore structure parameters and fractal dimension are discussed, along with the contributions of fractal dimension to shale gas reservoir evaluation. Analysis of the results showed that Niutitang shale samples featured high TOC content (2.51% on average, high thermal maturity (3.0% on average, low permeability and complex pore structures, which are highly fractal. TOC content and mineral compositions are two major factors affecting pore structure but they have different impacts on the fractal dimension. Shale samples with higher TOC content had a larger specific surface area (SSA, pore volume (PV and fractal dimension, which enhanced the heterogeneity of the pore structure. Quartz content had a relatively weak influence on shale pore structure, whereas SSA, PV and fractal dimension decreased with increasing clay mineral content. Shale with a higher clay content weakened pore structure heterogeneity. The permeability and Langmuir volume of methane adsorption were affected by fractal dimension. Shale samples with higher fractal dimension had higher adsorption capacity but lower permeability, which is favorable for shale gas adsorption but adverse to shale gas seepage and diffusion.

  12. Direct Numerical Simulation of Low Capillary Number Pore Scale Flows

    Science.gov (United States)

    Esmaeilzadeh, S.; Soulaine, C.; Tchelepi, H.

    2017-12-01

    The arrangement of void spaces and the granular structure of a porous medium determines multiple macroscopic properties of the rock such as porosity, capillary pressure, and relative permeability. Therefore, it is important to study the microscopic structure of the reservoir pores and understand the dynamics of fluid displacements through them. One approach for doing this, is direct numerical simulation of pore-scale flow that requires a robust numerical tool for prediction of fluid dynamics and a detailed understanding of the physical processes occurring at the pore-scale. In pore scale flows with a low capillary number, Eulerian multiphase methods are well-known to produce additional vorticity close to the interface. This is mainly due to discretization errors which lead to an imbalance of capillary pressure and surface tension forces that causes unphysical spurious currents. At the pore scale, these spurious currents can become significantly stronger than the average velocity in the phases, and lead to unphysical displacement of the interface. In this work, we first investigate the capability of the algebraic Volume of Fluid (VOF) method in OpenFOAM for low capillary number pore scale flow simulations. Afterward, we compare VOF results with a Coupled Level-Set Volume of Fluid (CLSVOF) method and Iso-Advector method. It has been shown that the former one reduces the VOF's unphysical spurious currents in some cases, and both are known to capture interfaces sharper than VOF. As the conclusion, we will investigate that whether the use of CLSVOF or Iso-Advector will lead to less spurious velocities and more accurate results for capillary driven pore-scale multiphase flows or not. Keywords: Pore-scale multiphase flow, Capillary driven flows, Spurious currents, OpenFOAM

  13. The influence of internal current loop on transient response performance of I-V droop controlled paralleled DC-DC converters

    DEFF Research Database (Denmark)

    Wang, Haojie; Han, Minxiao; Guerrero, Josep M.

    2017-01-01

    The external droop control loop of I-V droop control is designed as a voltage loop with embedded virtual impedance, so the internal current loop plays a major role in the system bandwidth. Thus, in this paper, the influence of internal current loop on transient response performance of I-V droop...... controlled paralleled dc-dc converters is analyzed, which is guided and significant for its industry application. The model which is used for dynamic analysis is built, and the root locus method is used based on the model to analyze the dynamic response of the system by shifting different control parameters...

  14. Interactions between bedforms, turbulence and pore flow

    Science.gov (United States)

    Blois, G.; Best, J.; Sambrook Smith, G.; Hardy, R. J.; Lead, J.

    2010-12-01

    A widespread occurrence of flow-form interaction in rivers is represented by subaqueous bedforms such as dunes. Many models have been proposed to explain how bedform generation and evolution are driven by turbulent flow structures that control the incipient motion of cohesionless sediments and later bedform development. However, most of these models have assumed such bedforms to be migrating over an impermeable bed, and that any surface-subsurface flow interaction is negligible. However, for some gravel-bed rivers the porosity can be high, up to 43%, which may result in significant flow both through the permeable bed (hyporheic flow) and across the surface-subsurface interface. The mass and momentum exchange occurring at the interface may have a strong impact on the structure of turbulent flow in the near-bed region. In the case of a dune, its topography induces a local pressure gradient that enhances flow across the interface. This results in a flow structure that may be radically different from that commonly proposed by past work. This paper presents results from a simplified laboratory model akin to a fine-grained bedform generated on top of a coarser sediment bed. Particle imaging velocimetry (PIV) measurements were conducted in order to characterise flow both over and underneath an idealised 2-dimensional dune (0.41 m long, 0.056 m high and having a leeside angle of 27°) overlaying a packed bed of uniform size spheres (D = 0.04 m diameter). Experiments were conducted in free surface flow conditions (Froude number = 0.1; Reynolds number = 25,000) for one bedform height: flow depth ratio (0.31). The flow above the dune was measured using a standard PIV technique while a novel endoscopic PIV (EPIV) system allowed collection of flow data within the pore spaces beneath the dune. The results show that topographically-induced subsurface flow significantly modifies the structure of flow in the leeside of the dune, resulting in a flow field that is radically different

  15. Excitation and damping of transversal oscillation in coronal loops by wake phenomena

    Directory of Open Access Journals (Sweden)

    A abedini

    2018-02-01

    Full Text Available Transversal oscillation of coronal loops that are interpreted as signatures of magneto hydrodynamics (MHD waves are observed frequently in active region corona loops. The amplitude of this oscillation has been found to be strongly attenuated. The damping of transverse oscillation may be produced by the dissipation mechanism and the wake of the traveling disturbance. The damping of transversal loop oscillations with wake phenomena is not related to any dissipation mechanism. Also, these kinds of coronal loop oscillations are not related to the kink mode, although this mode can be occurred after the attenuation process by the energy of the wave packet deposited in the loop.  In this paper the excitation and damping of transversal coronal loop oscillations with wake of traveling wave packet is discussed in detail, both theoretically and observationally. Here, the transversal coronal loop oscillations is modeled with a one dimensional simple line-tied. The dynamics of the loop and the coronal is governed by the Klein–Gordon differential equation. A localized disturbance that can be generated by nearby flare produces a perturbation that undergoes dispersion as it propagates toward the loop. As a consequence, the amplitudes of oscillates decay with time roughly t-1/2 at the external cutoff frequency. These observed data on 2016-Dec-4 by Atmospheric Imaging Assembly (AIA onboard Solar Dynamic Observatory (SDO observations data, consisting of 560 images with an interval of 24 seconds in the 171 A0 pass band is analyzed for evidence of excitation and damping of transverse oscillations of coronal loop that is situated near a flare. In this analyzed signatures of transverse oscillations that are damped rapidly were found, with periods in the range of P=18.5-23.85 minutes. Furthermore, oscillation of loop segments attenuate with time roughly as t-α that average values of α for 4 different loops change form 0.65-0.80. The magnitude values of α are in

  16. Pore volume and pore size distribution of cement samples measured by a modified mercury intrusion porosimeter

    International Nuclear Information System (INIS)

    Zamorani, E.; Blanchard, H.

    1987-01-01

    Important parameters for the characterization of cement specimens are mechanical properties and porosity. This work is carried out at the Ispra Establishment of the Joint Research Centre in the scope of the Radioactive Waste Management programme. A commercial Mercury Intrusion Porosimeter was modified in an attempt to improve the performance of the instrument and to provide fast processing of the recorded values: pressure-volume of pores. The dead volume of the instrument was reduced and the possibility of leakage from the moving parts eliminated. In addition, the modification allows an improvement of data acquisition thus increasing data accuracy and reproducibility. In order to test the improved performance of the modified instrument, physical characterizations of cement forms were carried out. Experimental procedures and results are reported

  17. Final Report for Subcontract B541028,Pore-Scale Modeling to Support 'Pore Connectivity' Research Work

    International Nuclear Information System (INIS)

    Ewing, R.P.

    2008-01-01

    A central concept for the geological barrier at the proposed Yucca Mountain radioactive waste repository is diffusive retardation: solute moving through a fracture diffuses into and out of the rock matrix. This diffusive exchange retards overall solute movement, and retardation both dilutes waste being released, and allows additional decay. The original concept of diffusive retardation required knowledge only of the fracture conductivity and the matrix diffusion. But that simple concept is unavoidably complicated by other issues and processes: contaminants may sorb to the rock matrix, fracture flow may be episodic, a given fracture may or may not flow depending on the volume of flow and the fracture's connection to the overall fracture network, the matrix imbibes water during flow episodes and dries between episodes, and so on. Some of these issues have been examined by other projects. This particular project is motivated by a simple fact: Yucca Mountain tuff has low pore connectivity. This fact is not widely recognized, nor are its implications widely appreciated. Because low pore connectivity affects many processes, it may invalidate many assumptions that are basic (though perhaps not stated) to other investigations. The overall project's objective statement (from the proposal) was: This proposal aims to improve our understanding of diffusive retardation of radionuclides due to fracture/matrix interactions. Results from this combined experimental/modeling work will (1) determine whether the current understanding and model representation of matrix diffusion is valid, (2) provide insights into the upscaling of laboratory-scale diffusion experiments, and (3) evaluate the impact on diffusive retardation of episodic fracture flow and pore connectivity in Yucca Mountain tuffs. An obvious data gap addressed by the project was that there were only a few limited measurements of the diffusion coefficient of the rock at the repository level. That is, at the time we wrote

  18. A method for external measurement of toroidal equilibrium parameters

    International Nuclear Information System (INIS)

    Brunsell, P.; Hellblom, G.; Brynolf, J.

    1992-01-01

    A method has been developed for determining from external magnetic field measurements the horizontal shift, the vertical shift and the poloidal field asymmetry parameter (Λ) of a toroidal plasma in force equilibrium. The magnetic measurements consist of two toroidal differential flux loops, giving the average vertical magnetic field and the average radial magnetic field respectively, together with cosine-coils for obtaining the m=1 cosine harmonic of the external poloidal magnetic field component. The method is used to analyse the evolution of the toroidal equilibrium during reversed-field pinch discharges in the Extrap T1-U device. We find that good equilibrium control is needed for long plasma pulses. For non-optimized externally applied vertical fields, the diagnostic clearly shows a horizontal drift motion of the pinch resulting in earlier discharge termination. (au)

  19. Impact of Pore-Scale Wettability on Rhizosphere Rewetting

    Directory of Open Access Journals (Sweden)

    Pascal Benard

    2018-04-01

    Full Text Available Vast amounts of water flow through a thin layer of soil around the roots, the rhizosphere, where high microbial activity takes place—an important hydrological and biological hotspot. The rhizosphere was shown to turn water repellent upon drying, which has been interpreted as the effect of mucilage secreted by roots. The effects of such rhizosphere water dynamics on plant and microbial activity are unclear. Furthermore, our understanding of the biophysical mechanisms controlling the rhizosphere water repellency remains largely speculative. Our hypothesis is that the key to describe the emergence of water repellency lies within the microscopic distribution of wettability on the pore-scale. At a critical mucilage content, a sufficient fraction of pores is blocked and the rhizosphere turns water repellent. Here we tested whether a percolation approach is capable to predict the flow behavior near the critical mucilage content. The wettability of glass beads and sand mixed with chia seed mucilage was quantified by measuring the infiltration rate of water drops. Drop infiltration was simulated using a simple pore-network model in which mucilage was distributed heterogeneously throughout the pore space with a preference for small pores. The model approach proved capable to capture the percolation nature of the process, the sudden transition from wettable to water repellent and the high variability in infiltration rates near the percolation threshold. Our study highlights the importance of pore-scale distribution of mucilage in the emergent flow behavior across the rhizosphere.

  20. Pore Scale Analysis of Oil Shale/Sands Pyrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chen-Luh [Univ. of Utah, Salt Lake City, UT (United States); Miller, Jan [Univ. of Utah, Salt Lake City, UT (United States)

    2011-03-01

    There are important questions concerning the quality and volume of pore space that is created when oil shale is pyrolyzed for the purpose of producing shale oil. In this report, 1.9 cm diameter cores of Mahogany oil shale were pyrolyzed at different temperatures and heating rates. Detailed 3D imaging of core samples was done using multiscale X-ray computed tomography (CT) before and after pyrolysis to establish the pore structure. The pore structure of the unreacted material was not clear. Selected images of a core pyrolyzed at 400oC were obtained at voxel resolutions from 39 microns (Οm) to 60 nanometers (nm). Some of the pore space created during pyrolysis was clearly visible at these resolutions and it was possible to distinguish between the reaction products and the host shale rock. The pore structure deduced from the images was used in Lattice Boltzmann simulations to calculate the permeability in the pore space. The permeabilities of the pyrolyzed samples of the silicate-rich zone were on the order of millidarcies, while the permeabilities of the kerogen-rich zone after pyrolysis were very anisotropic and about four orders of magnitude higher.

  1. Pore growth in U-Mo/Al dispersion fuel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yeon Soo, E-mail: yskim@anl.gov [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Jeong, G.Y.; Sohn, D.-S. [Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan, 689-798 (Korea, Republic of); Jamison, L.M. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States)

    2016-09-15

    U-Mo/Al dispersion fuel is currently under development in the DOE’s Material Management and Minimization program to convert HEU-fueled research reactors to LEU-fueled reactors. In some demanding conditions in high-power and high-performance reactors, large pores form in the interaction layers between the U-Mo fuel particles and the Al matrix, which pose a potential to cause fuel failure. In this study, comprehension of the formation and growth of these pores was explored. As a product, a model to predict pore growth and porosity increase was developed. The model includes three major topics: fission gas release from the U-Mo and the IL to the pores, stress evolution in the fuel meat, and the effect of amorphous IL growth. Well-characterized in-pile data from reduced-size plates were used to fit the model parameters. A data set from full-sized plates, independent and distinctively different from those used to fit the model parameters, was used to examine the accuracy of the model. The model showed fair agreement with the measured data. The model suggested that the growth of the IL has a critical effect on pore growth, as both its material properties and energetics are favorable to pore formation. Therefore, one area of the current effort, focused on suppressing IL growth, appears to be on the right track to improve the performance of this fuel.

  2. Software Image J to study soil pore distribution

    Directory of Open Access Journals (Sweden)

    Sabrina Passoni

    2014-04-01

    Full Text Available In the soil science, a direct method that allows the study of soil pore distribution is the bi-dimensional (2D digital image analysis. Such technique provides quantitative results of soil pore shape, number and size. The use of specific softwares for the treatment and processing of images allows a fast and efficient method to quantify the soil porous system. However, due to the high cost of commercial softwares, public ones can be an interesting alternative for soil structure analysis. The objective of this work was to evaluate the quality of data provided by the Image J software (public domain used to characterize the voids of two soils, characterized as Geric Ferralsol and Rhodic Ferralsol, from the southeast region of Brazil. The pore distribution analysis technique from impregnated soil blocks was utilized for this purpose. The 2D image acquisition was carried out by using a CCD camera coupled to a conventional optical microscope. After acquisition and treatment of images, they were processed and analyzed by the software Noesis Visilog 5.4® (chosen as the reference program and ImageJ. The parameters chosen to characterize the soil voids were: shape, number and pore size distribution. For both soils, the results obtained for the image total porosity (%, the total number of pores and the pore size distribution showed that the Image J is a suitable software to be applied in the characterization of the soil sample voids impregnated with resin.

  3. Pore opening dynamics in the exocytosis of serotonin

    Science.gov (United States)

    Ramirez-Santiago, Guillermo; Cercos, Montserrat G.; Martinez-Valencia, Alejandro; Salinas Hernandez, Israel; Rodríguez-Sosa, Leonardo; de-Miguel, Francisco F.

    2015-03-01

    The current view of the exocytosis of transmitter molecules is that it starts with the formation of a fusion pore that connects the intravesicular and the extracellular spaces, and is completed by the release of the rest of the transmitter contained in the vesicle upon the full fusion and collapse of the vesicle with the plasma membrane. However, under certain circumstances, a rapid closure of the pore before the full vesicle fusion produces only a partial release of the transmitter. Here we show that whole release of the transmitter occurs through fusion pores that remain opened for tens of milliseconds without vesicle collapse. This was demonstrated through amperometric measurements of serotonin release from electrodense vesicles in the axon of leech Retzius neurons and mathematical modelling. By modeling transmitter release with a diffusion equation subjected to boundary conditions that are defined by the experiment, we showed that those pores with a fast half rise time constant remained opened and allowed the full quantum release without vesicle collapse, whereas pores with a slow rise time constant closed rapidly, thus producing partial release. We conclude that a full transmitter release may occur through the fusion pore in the absence of vesicle collapse. This work was founded by a DGAPA-UNAM grants IN200914 and IN118410 CONACYT GRANT 130031, and CONACyT doctoral fellowships.

  4. Asymmetric dual-loop feedback to suppress spurious tones and reduce timing jitter in self-mode-locked quantum-dash lasers emitting at 155 μm

    Science.gov (United States)

    Asghar, Haroon; McInerney, John G.

    2017-09-01

    We demonstrate an asymmetric dual-loop feedback scheme to suppress external cavity side-modes induced in self-mode-locked quantum-dash lasers with conventional single and dual-loop feedback. In this letter, we achieved optimal suppression of spurious tones by optimizing the length of second delay time. We observed that asymmetric dual-loop feedback, with large (~8x) disparity in cavity lengths, eliminates all external-cavity side-modes and produces flat RF spectra close to the main peak with low timing jitter compared to single-loop feedback. Significant reduction in RF linewidth and reduced timing jitter was also observed as a function of increased second feedback delay time. The experimental results based on this feedback configuration validate predictions of recently published numerical simulations. This interesting asymmetric dual-loop feedback scheme provides simplest, efficient and cost effective stabilization of side-band free optoelectronic oscillators based on mode-locked lasers.

  5. Accurate relations between pore size and the pressure of capillary condensation and the evaporation of nitrogen in cylindrical pores.

    Science.gov (United States)

    Morishige, Kunimitsu; Tateishi, Masayoshi

    2006-04-25

    To examine the theoretical and semiempirical relations between pore size and the pressure of capillary condensation or evaporation proposed so far, we constructed an accurate relation between the pore radius and the capillary condensation and evaporation pressure of nitrogen at 77 K for the cylindrical pores of the ordered mesoporous MCM-41 and SBA-15 silicas. Here, the pore size was determined from a comparison between the experimental and calculated X-ray diffraction patterns due to X-ray structural modeling recently developed. Among the many theoretical relations that differ from each other in the degree of theoretical improvements, a macroscopic thermodynamic approach based on Broekhoff-de Boer equations was found to be in fair agreement with the experimental relation obtained in the present study.

  6. Environmental external effects from wind power based on the EU ExternE methodology

    DEFF Research Database (Denmark)

    Ibsen, Liselotte Schleisner; Nielsen, Per Sieverts

    1998-01-01

    of the Danish part of the project is to implement the framework for externality evaluation, for three different power plants located in Denmark. The paper will focus on the assessment of the impacts of the whole fuel cycles for wind, natural gas and biogas. Priority areas for environmental impact assessment......The European Commission has launched a major study project, ExternE, to develop a methodology to quantify externalities. A “National Implementation Phase”, was started under the Joule II programme with the purpose of implementing the ExternE methodology in all member states. The main objective...

  7. Three-Dimensional Phase Field Simulations of Hysteresis and Butterfly Loops by the Finite Volume Method

    International Nuclear Information System (INIS)

    Xi Li-Ying; Chen Huan-Ming; Zheng Fu; Gao Hua; Tong Yang; Ma Zhi

    2015-01-01

    Three-dimensional simulations of ferroelectric hysteresis and butterfly loops are carried out based on solving the time dependent Ginzburg–Landau equations using a finite volume method. The influence of externally mechanical loadings with a tensile strain and a compressive strain on the hysteresis and butterfly loops is studied numerically. Different from the traditional finite element and finite difference methods, the finite volume method is applicable to simulate the ferroelectric phase transitions and properties of ferroelectric materials even for more realistic and physical problems. (paper)

  8. External corners as heat bridges

    Energy Technology Data Exchange (ETDEWEB)

    Berber, J.

    1984-08-01

    The maximum additional heat loss in vertical external corners depending on wall thickness is determined. In order to amire at a low k-value, a much smaller wall thickness is required in externally insulated walls than in monolithic constructions; the greater loss of heat bridge with external insulation stands in contrast to a higher loss in thick, monolithic walls. In relation to total losses, the additional losses through external corners are practically negligible.

  9. Mechanistic modeling of the loss of protein sieving due to internal and external fouling of microfilters.

    Science.gov (United States)

    Bolton, Glen R; Apostolidis, Alex J

    2017-09-01

    Fed-batch and perfusion cell culture processes used to produce therapeutic proteins can use microfilters for product harvest. In this study, new explicit mathematical models of sieving loss due to internal membrane fouling, external membrane fouling, or a combination of the two were generated. The models accounted for membrane and cake structures and hindered solute transport. Internal membrane fouling was assumed to occur due to the accumulation of foulant on either membrane pore walls (pore-retention model) or membrane fibers (fiber-retention model). External cake fouling was assumed to occur either by the growth of a single incompressible cake layer (cake-growth) or by the accumulation of a number of independent cake layers (cake-series). The pore-retention model was combined with either the cake-series or cake-growth models to obtain models that describe internal and external fouling occurring either simultaneously or sequentially. The models were tested using well-documented sieving decline data available in the literature. The sequential pore-retention followed by cake-growth model provided a good fit of sieving decline data during beer microfiltration. The cake-series and cake-growth models provided good fits of sieving decline data during the microfiltration of a perfusion cell culture. The new models provide insights into the mechanisms of fouling that result in the loss of product sieving. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1323-1333, 2017. © 2017 American Institute of Chemical Engineers.

  10. [External pancreatic fistulas management].

    Science.gov (United States)

    Stepan, E V; Ermolov, A S; Rogal', M L; Teterin, Yu S

    The main principles of treatment of external postoperative pancreatic fistulas are viewed in the article. Pancreatic trauma was the reason of pancreatic fistula in 38.7% of the cases, operations because of acute pancreatitis - in 25.8%, and pancreatic pseudocyst drainage - in 35.5%. 93 patients recovered after the treatment. Complex conservative treatment of EPF allowed to close fistulas in 74.2% of the patients with normal patency of the main pancreatic duct (MPD). The usage of octreotide 600-900 mcg daily for at least 5 days to decrease pancreatic secretion was an important part of the conservative treatment. Endoscopic papillotomy was performed in patients with major duodenal papilla obstruction and interruption of transporting of pancreatic secretion to duodenum. Stent of the main pancreatic duct was indicated in patients with extended pancreatic duct stenosis to normalize transport of pancreatic secretion to duodenum. Surgical formation of anastomosis between distal part of the main pancreatic duct and gastro-intestinal tract was carried out when it was impossible to fulfill endoscopic stenting of pancreatic duct either because of its interruption and diastasis between its ends, or in the cases of unsuccessful conservative treatment of external pancreatic fistula caused by drainage of pseudocyst.

  11. Loop quantization as a continuum limit

    International Nuclear Information System (INIS)

    Manrique, Elisa; Oeckl, Robert; Weber, Axel; Zapata, Jose A

    2006-01-01

    We present an implementation of Wilson's renormalization group and a continuum limit tailored for loop quantization. The dynamics of loop-quantized theories is constructed as a continuum limit of the dynamics of effective theories. After presenting the general formalism we show as a first explicit example the 2D Ising field theory, an interacting relativistic quantum field theory with local degrees of freedom quantized by loop quantization techniques

  12. Quantum chromodynamics as dynamics of loops

    International Nuclear Information System (INIS)

    Makeenko, Yu.M.; Migdal, A.A.

    1981-01-01

    QCD is entirely reformulated in terms of white composite fields - the traces of the loop products. The 1/N expansion turns out to be the WKB (Hartree-Fock) approximation for these fields. The 'classical' equation describing the N = infinite case is reduced tp a bootstrap form. New, manifestly gauge-invariant perturbation theory in the loop space, reproducing asymptotic freedom, is developed by iterations of this equation. The area law appears to be a self-consistent solution at large loops. (orig.)

  13. Lattice QED in the loop space

    International Nuclear Information System (INIS)

    Fort, H.

    1994-01-01

    We present a survey on the state of the art in the formulation of lattice compact QED in the space of loops. In a first part we review our most recent Hamiltonian results which signal a second order transition for (3+1) compact QED. We devote the second part to the Lagrangian loop formalism, showing the equivalence of the recently proposed loop action with the Villain form. (orig.)

  14. LMFBR with booster pump in pumping loop

    International Nuclear Information System (INIS)

    Rubinstein, H.J.

    1975-01-01

    A loop coolant circulation system is described for a liquid metal fast breeder reactor (LMFBR) utilizing a low head, high specific speed booster pump in the hot leg of the coolant loop with the main pump located in the cold leg of the loop, thereby providing the advantages of operating the main pump in the hot leg with the reliability of cold leg pump operation

  15. Soft Neutrosophic Loops and Their Generalization

    Directory of Open Access Journals (Sweden)

    Mumtaz Ali

    2014-06-01

    Full Text Available Soft set theory is a general mathematical tool for dealing with uncertain, fuzzy, not clearly defined objects. In this paper we introduced soft neutrosophic loop,soft neutosophic biloop, soft neutrosophic N -loop with the discuission of some of their characteristics. We also introduced a new type of soft neutrophic loop, the so called soft strong neutrosophic loop which is of pure neutrosophic character. This notion also found in all the other corresponding notions of soft neutrosophic thoery. We also given some of their properties of this newly born soft structure related to the strong part of neutrosophic theory.

  16. Vertically Polarized Omnidirectional Printed Slot Loop Antenna

    DEFF Research Database (Denmark)

    Kammersgaard, Nikolaj Peter Iversen; Kvist, Søren H.; Thaysen, Jesper

    2015-01-01

    A novel vertically polarized omnidirectional printed slot loop antenna has been designed, simulated, fabricated and measured. The slot loop works as a magnetic loop. The loop is loaded with inductors to insure uniform and in-phase fields in the slot in order to obtain an omnidirectional radiation...... pattern. The antenna is designed for the 2.45 GHz Industrial, Scientific and Medical band. Applications of the antenna are many. One is for on-body applications since it is ideal for launching a creeping waves due to the polarization....

  17. Quantum chromodynamics as dynamics of loops

    International Nuclear Information System (INIS)

    Makeenko, Yu.; Migdal, A.A.

    1980-01-01

    The problem of a possibility of reformulating quantum chromodynamics (QCD) in terms of colourless composite fields instead of coloured quarks and gluons is considered. The role of such fields is played by the gauge invariant loop functionals. The Shwinger equations of motion is derived in the loop space which completely describe dynamics of the loop fields. New manifestly gauge invariant diagram technique in the loop space is developed. These diagrams reproduce asymptotic freedom in the ultraviolet range and are consistent with the confinement law in the infrared range

  18. In pile helium loop ''Comedie''

    International Nuclear Information System (INIS)

    Blanchard, R.J.

    1985-01-01

    The loop is located in the SILOE reactor at Centre d'Etudes Nucleaires de Grenoble. The purpose and objectives are divided into two groups, principal and secondary. The primary objective was to provide basic data on the deposition behavior of important condensable fission products on a variety of steel surfaces, i.e. temperature (sorption isotherms) and mass transfer (physical adsorption) dependencies; to provide information concerning the degree of penetration of important fission products into the metals comprising the heat exchanger-recuperator tubes as a function of alloy type and/or metal temperature; to provide complementary information on the reentrainment (liftoff) of important fission and activation products by performing out-of-pile blowdown experiments on tube samples representative of the alloy types used in the heat exchanger-recuperator and of the surface temperatures experienced during plateout. The secondary objective was to provide information concerning the migration of important fission products through graphite. To this end, concentration profiles in the web between the fuel rods containing the fission product source and the coolant channels and in the graphite diffusion sample will be measured to study the corrosion of metallic specimens placed in the conditions of high temperature gas cooled reactor. The first experiment SRO enables to determine the loop characteristics and possibilities related to thermal, thermodynamic, chemical and neutronic properties. The second experiment has been carried out in high temperature gas cooled reactor operating conditions. It enables to determine in particular the deposition axial profile of activation and fission products in the plateout section constituting the heat exchanger, the fission products balance trapped in the different filter components, and the cumulated released fraction of solid fission products. The SR1 test permits to demonstrate in particular the Comedie loop operation reliability, either

  19. Synthesis of Novel Mesoporous Silica Materials with Hierarchical Pore Structures

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Suk Bon; Choi, Wang Kyu; Choi, Byung Seon; Moon, Jei Kwon [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Porous materials with various pore sizes in the range of micropore (< 2 nm), mesopore (2-50 nm), and macropore (> 50 nm) are attractive due to their many emerging applications such as catalysts, separation systems, and low dielectric constant materials. The discovery of new M41S mesoporous silica families with pore sizes larger than 2 nm in diameter in 1992 extended the applications into much wider pore ranges, bringing in a new prosperous era in porous material research. The synthesis of these silica materials has been mainly accomplished through a self-assembly between surfactant molecules and inorganic species under various pH conditions. Recently, core-shell nanoparticles with a silica core and mesoporous shell under basic conditions were synthesized using the silica nanoparticles as a core, and a silica precursor (TEOS) and cationic surfactant (CTABr) as a material for the formation of the mesoporous shell. The resultant materials were very monodispersive in size and showed a narrow pore size distribution in the range of ca 2-3 nm in diameter, depending on the alkyl-chain length of the surfactants used. In this work, the mesoporous shell coated-fumed silicas (denoted as MS M-5s) were synthesized by using fumed silica instead of the silica nanoparticle as a core based on previous reports. Also, the structural properties of the MS M-5s such as the specific surface area and pore volume were easily controlled by varying the amount of the silica precursor and surfactant. The resultant materials exhibited a BET surface area of ca 279-446 m{sup 2}/g and total pore volume of ca 0.64-0.74 cm{sup 3}/g and showed a narrow pore size distribution (PSD) due to the removal of the organic surfactant molecules

  20. Long-pore Electrostatics in Inward-rectifier Potassium Channels

    Science.gov (United States)

    Robertson, Janice L.; Palmer, Lawrence G.; Roux, Benoît

    2008-01-01

    Inward-rectifier potassium (Kir) channels differ from the canonical K+ channel structure in that they possess a long extended pore (∼85 Å) for ion conduction that reaches deeply into the cytoplasm. This unique structural feature is presumably involved in regulating functional properties specific to Kir channels, such as conductance, rectification block, and ligand-dependent gating. To elucidate the underpinnings of these functional roles, we examine the electrostatics of an ion along this extended pore. Homology models are constructed based on the open-state model of KirBac1.1 for four mammalian Kir channels: Kir1.1/ROMK, Kir2.1/IRK, Kir3.1/GIRK, and Kir6.2/KATP. By solving the Poisson-Boltzmann equation, the electrostatic free energy of a K+ ion is determined along each pore, revealing that mammalian Kir channels provide a favorable environment for cations and suggesting the existence of high-density regions in the cytoplasmic domain and cavity. The contribution from the reaction field (the self-energy arising from the dielectric polarization induced by the ion's charge in the complex geometry of the pore) is unfavorable inside the long pore. However, this is well compensated by the electrostatic interaction with the static field arising from the protein charges and shielded by the dielectric surrounding. Decomposition of the static field provides a list of residues that display remarkable correspondence with existing mutagenesis data identifying amino acids that affect conduction and rectification. Many of these residues demonstrate interactions with the ion over long distances, up to 40 Å, suggesting that mutations potentially affect ion or blocker energetics over the entire pore. These results provide a foundation for understanding ion interactions in Kir channels and extend to the study of ion permeation, block, and gating in long, cation-specific pores. PMID:19001143

  1. Rapid Simulation of Flat Knitting Loops Based On the Yarn Texture and Loop Geometrical Model

    Directory of Open Access Journals (Sweden)

    Lu Zhiwen

    2017-06-01

    Full Text Available In order to create realistic loop primitives suitable for the fast computer-aided design (CAD of the flat knitted fabric, we have a research on the geometric model of the loop as well as the variation of the loop surface. Establish the texture variation model based on the changing process from the normal yarn to loop that provides the realistic texture of the simulative loop. Then optimize the simulative loop based on illumination variation. This paper develops the computer program with the optimization algorithm and achieves the loop simulation of different yarns to verify the feasibility of the proposed algorithm. Our work provides a fast CAD of the flat knitted fabric with loop simulation, and it is not only more realistic but also material adjustable. Meanwhile it also provides theoretical value for the flat knitted fabric computer simulation.

  2. Impact of pore characteristics of silica materials on loading capacity and release behavior of ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Numpilai, Thanapha [Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900 (Thailand); Muenmee, Suthaporn [Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900 (Thailand); Center for Advanced Studies in Nanotechnology and Its Applications in Chemical Food and Agricultural Industries, Kasetsart University, Bangkok 10900 (Thailand); Witoon, Thongthai, E-mail: fengttwi@ku.ac.th [Department of Chemical Engineering, Faculty of Engineering, Kasetsart University, Bangkok 10900 (Thailand); Center for Advanced Studies in Nanotechnology and Its Applications in Chemical Food and Agricultural Industries, Kasetsart University, Bangkok 10900 (Thailand); NANOTEC-KU-Center of Excellence on Nanoscale Materials Design for Green Nanotechnology, Kasetsart University, Bangkok 10900 (Thailand)

    2016-02-01

    Impact of pore characteristics of porous silica supports on loading capacity and release behavior of ibuprofen was investigated. The porous silica materials and ibuprofen-loaded porous silica materials were thoroughly characterized by N{sub 2}-sorption, thermal gravimetric and derivative weight analyses (TG-DTW), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) to determine the physical properties of materials, amount of ibuprofen adsorbed and position of ibuprofen. The detailed characterization reveals that the ibuprofen molecules adsorbed inside the mesopores. Increasing the mesopore size from 5 nm to 10 nm increased the ibuprofen loading from 0.74 to 0.85 mmol/g, respectively. Incorporation of macropore into the structure of porous silica materials enhanced the ibuprofen loading capacity of 11.8–20.3%. The ibuprofen-loaded bimodal meso-macroporous silica materials exhibited the highest dissolution of 92 wt.% within an hour. The ibuprofen particles deposited on the external surface of the porous silica materials showed a lower dissolution rate than the ibuprofen adsorbed inside the mesopores due to the formation of ibuprofen crystalline. - Highlights: • Impacts of pore characteristics of supports on adsorption and release of ibuprofen • Increasing mesopore size increased the ibuprofen loading and dissolution rate. • Macropores reduced the diffusion pathway of ibuprofen and dissolution medium.

  3. Impact of pore characteristics of silica materials on loading capacity and release behavior of ibuprofen

    International Nuclear Information System (INIS)

    Numpilai, Thanapha; Muenmee, Suthaporn; Witoon, Thongthai

    2016-01-01

    Impact of pore characteristics of porous silica supports on loading capacity and release behavior of ibuprofen was investigated. The porous silica materials and ibuprofen-loaded porous silica materials were thoroughly characterized by N 2 -sorption, thermal gravimetric and derivative weight analyses (TG-DTW), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM) to determine the physical properties of materials, amount of ibuprofen adsorbed and position of ibuprofen. The detailed characterization reveals that the ibuprofen molecules adsorbed inside the mesopores. Increasing the mesopore size from 5 nm to 10 nm increased the ibuprofen loading from 0.74 to 0.85 mmol/g, respectively. Incorporation of macropore into the structure of porous silica materials enhanced the ibuprofen loading capacity of 11.8–20.3%. The ibuprofen-loaded bimodal meso-macroporous silica materials exhibited the highest dissolution of 92 wt.% within an hour. The ibuprofen particles deposited on the external surface of the porous silica materials showed a lower dissolution rate than the ibuprofen adsorbed inside the mesopores due to the formation of ibuprofen crystalline. - Highlights: • Impacts of pore characteristics of supports on adsorption and release of ibuprofen • Increasing mesopore size increased the ibuprofen loading and dissolution rate. • Macropores reduced the diffusion pathway of ibuprofen and dissolution medium.

  4. Lose Your Loops with Numpy

    CERN Multimedia

    CERN. Geneva

    2016-01-01

    Developing in python is fast. Computation, however, can often be another story. Or at least that is how it may seem. When working with arrays and numerical datasets one can subvert many of python’s computational limitations by utilizing numpy. Numpy is python’s standard matrix computation library. Many python users only use numpy to store and generate arrays, failing to utilize one of python’s most powerful computational tools. By leveraging numpy’s ufuncs, aggregation, broadcasting and slicing/masking/indexing functionality one can cut back on slow python loops and increase the speed of their programs by as much as 100x. This talk aims at teaching attendees how to use these tools through toy examples.

  5. Closed loop steam cooled airfoil

    Science.gov (United States)

    Widrig, Scott M.; Rudolph, Ronald J.; Wagner, Gregg P.

    2006-04-18

    An airfoil, a method of manufacturing an airfoil, and a system for cooling an airfoil is provided. The cooling system can be used with an airfoil located in the first stages of a combustion turbine within a combined cycle power generation plant and involves flowing closed loop steam through a pin array set within an airfoil. The airfoil can comprise a cavity having a cooling chamber bounded by an interior wall and an exterior wall so that steam can enter the cavity, pass through the pin array, and then return to the cavity to thereby cool the airfoil. The method of manufacturing an airfoil can include a type of lost wax investment casting process in which a pin array is cast into an airfoil to form a cooling chamber.

  6. External Measures of Cognition

    Directory of Open Access Journals (Sweden)

    Osvaldo eCairo

    2011-10-01

    Full Text Available The human brain is undoubtedly the most impressive, complex and intricate organ that has evolved over time. It is also probably the least understood, and for that reason, the one that is currently attracting the most attention. In fact, the number of comparative analyses that focus on the evolution of brain size in Homo sapiens and other species has increased dramatically in recent years. In neuroscience, no other issue has generated so much interest and been the topic of so many heated debates as the difference in brain size between socially defined population groups, both its connotations and implications. For over a century, external measures of cognition have been related to intelligence. However, it is still unclear whether these measures actually correspond to cognitive abilities. In summary, this paper must be reviewed with this premise in mind.

  7. Hanford External Dosimetry Program

    International Nuclear Information System (INIS)

    Fix, J.J.

    1990-10-01

    This document describes the Hanford External Dosimetry Program as it is administered by Pacific Northwest Laboratory (PNL) in support of the US Department of Energy (DOE) and its Hanford contractors. Program services include administrating the Hanford personnel dosimeter processing program and ensuring that the related dosimeter data accurately reflect occupational dose received by Hanford personnel or visitors. Specific chapters of this report deal with the following subjects: personnel dosimetry organizations at Hanford and the associated DOE and contractor exposure guidelines; types, characteristics, and procurement of personnel dosimeters used at Hanford; personnel dosimeter identification, acceptance testing, accountability, and exchange; dosimeter processing and data recording practices; standard sources, calibration factors, and calibration processes (including algorithms) used for calibrating Hanford personnel dosimeters; system operating parameters required for assurance of dosimeter processing quality control; special dose evaluation methods applied for individuals under abnormal circumstances (i.e., lost results, etc.); and methods for evaluating personnel doses from nuclear accidents. 1 ref., 14 figs., 5 tabs

  8. Bevalac external beamline optics

    Energy Technology Data Exchange (ETDEWEB)

    Kalnins, J.G.; Krebs, G.F.; Tekawa, M.M.; Alonso, J.R.

    1987-04-01

    This handbook is intended as an aid for tuning the external particle beam (EPB) lines at the Lawrence Berkeley Laboratory's Bevalac. The information contained within will be useful to the Bevalac's Main Control Room and experimenters alike. First, some general information is given concerning the EPB lines and beam optics. Next, each beam line is described in detail: schematics of the beam line components are shown, all the variables required to run a beam transport program are presented, beam envelopes are given with wire chamber pictures and magnet currents, focal points and magnifications. Some preliminary scaling factors are then presented which should aid in choosing a given EPB magnet's current for a given central Bevalac field. Finally, some tuning hints are suggested.

  9. Bevalac external beamline optics

    International Nuclear Information System (INIS)

    Kalnins, J.G.; Krebs, G.F.; Tekawa, M.M.; Alonso, J.R.

    1987-04-01

    This handbook is intended as an aid for tuning the external particle beam (EPB) lines at the Lawrence Berkeley Laboratory's Bevalac. The information contained within will be useful to the Bevalac's Main Control Room and experimenters alike. First, some general information is given concerning the EPB lines and beam optics. Next, each beam line is described in detail: schematics of the beam line components are shown, all the variables required to run a beam transport program are presented, beam envelopes are given with wire chamber pictures and magnet currents, focal points and magnifications. Some preliminary scaling factors are then presented which should aid in choosing a given EPB magnet's current for a given central Bevalac field. Finally, some tuning hints are suggested

  10. Final Report for Subcontract B541028, Pore-Scale Modeling to Support 'Pore Connectivity' Research Work

    International Nuclear Information System (INIS)

    Ewing, R.P.

    2009-01-01

    This report covers modeling aspects of a combined experimental and modeling task in support of the DOE Science and Technology Program (formerly OSTI) within the Office of Civilian Radioactive Waste Management (OCRWM). Research Objectives The research for this project dealt with diffusive retardation: solute moving through a fracture diffuses into and out of the rock matrix. This diffusive exchange retards overall solute movement, and retardation both dilutes waste being released, and allows additional decay. Diffusive retardation involves not only fracture conductivity and matrix diffusion, but also other issues and processes: contaminants may sorb to the rock matrix, fracture flow may be episodic, a given fracture may or may not flow depending on the volume of flow and the fracture's connection to the overall fracture network, the matrix imbibes water during flow episodes and dries between episodes, and so on. The objective of the project was to improve understanding of diffusive retardation of radionuclides due to fracture / matrix interactions. Results from combined experimental/modeling work were to (1) determine whether the current understanding and model representation of matrix diffusion is valid, (2) provide insights into the upscaling of laboratory-scale diffusion experiments, and (3) help in evaluating the impact on diffusive retardation of episodic fracture flow and pore connectivity in Yucca Mountain tuffs. Questions explored included the following: (1) What is the relationship between the diffusion coefficient measured at one scale, to that measured or observed at a different scale? In classical materials this relationship is trivial; in low-connectivity materials it is not. (2) Is the measured diffusivity insensitive to the shape of the sample? Again, in classical materials there should be no sample shape effect. (3) Does sorption affect diffusive exchange in low-connectivity media differently than in classical media? (4) What is the effect of matrix

  11. Study of pore pressure reaction on hydraulic fracturing

    Science.gov (United States)

    Trimonova, Mariia; Baryshnikov, Nikolay; Turuntaev, Sergey; Zenchenko, Evgeniy; Zenchenko, Petr

    2017-04-01

    We represent the results of the experimental study of the hydraulic fracture propagation influence on the fluid pore pressure. Initial pore pressure was induced by injection and production wells. The experiments were carried out according to scaling analysis based on the radial model of the fracture. All required geomechanical and hydrodynamical properties of a sample were derived from the scaling laws. So, gypsum was chosen as a sample material and vacuum oil as a fracturing fluid. The laboratory setup allows us to investigate the samples of cylindrical shape. It can be considered as an advantage in comparison with standard cubic samples, because we shouldn't consider the stress field inhomogeneity induced by the corners. Moreover, we can set 3D-loading by this setting. Also the sample diameter is big enough (43cm) for placing several wells: the fracturing well in the center and injection and production wells on two opposite sides of the central well. The experiment consisted of several stages: a) applying the horizontal pressure; b) applying the vertical pressure; c) water solution injection in the injection well with a constant pressure; d) the steady state obtaining; e) the oil injection in the central well with a constant rate. The pore pressure was recorded in the 15 points along bottom side of the sample during the whole experiment. We observe the pore pressure change during all the time of the experiment. First, the pore pressure changed due to water injection. Then we began to inject oil in the central well. We compared the obtained experimental data on the pore pressure changes with the solution of the 2D single-phase equation of pore-elasticity, and we found significant difference. The variation of the equation parameters couldn't help to resolve the discrepancy. After the experiment, we found that oil penetrated into the sample before and after the fracture initiation. This fact encouraged us to consider another physical process - the oil

  12. Neocortical electrical stimulation for epilepsy : Closed-loop versus open-loop

    NARCIS (Netherlands)

    Vassileva, Albena; van Blooijs, Dorien; Leijten, Frans; Huiskamp, Geertjan

    2018-01-01

    The aim of this review is to evaluate whether open-loop or closed-loop neocortical electrical stimulation should be the preferred approach to manage seizures in intractable epilepsy. Twenty cases of open-loop neocortical stimulation with an implanted device have been reported, in 5 case studies.

  13. Acoustic characteristics of sand sediment with circular cylindrical pores

    International Nuclear Information System (INIS)

    Roh, Heui-Seol; Lee, Kang-Il; Yoon, Suk-Wang

    2004-01-01

    The acoustic pressure transmission coefficient and the phase velocity are experimentally measured as functions of the frequency and the porosity in sand sediment slabs with circular cylindrical pores filled with water and air. They are also theoretically estimated with the modified Biot-Attenborough (MBA) model, which uses a separate treatment of the viscous and the thermal effects in a non-rigid porous medium with water- and air-filled cylindrical pores. In this study, the fast (first kind) wave and the slow (second kind) wave are not separated in the transmitted signals through a sediment slab without the circular cylindrical pores, but they are separated in the transmitted signals through a sediment slab with pores. Both the phase velocities and the transmission coefficients of the fast wave and the slow wave in the sediment slabs with water- and air-filled cylindrical pores are sensitive to the air and the water porosities. It is proposed that the fast and the slow waves have opposite behaviors for several acoustic characteristics. The generalized tortuosity factor and the dynamic shape factor are introduced from the acoustic characteristics of the fast wave. The experimental results show reasonable agreement with the theoretical results estimated with the MBA model. These results suggest the possibility of predicting the acoustic characteristics of a sediment as functions of arbitrary water and air porosities. This study may also be applicable to understanding acoustic wave propagations in a bubbly liquid sediment for underwater applications and in cancellous bone for the diagnosis of osteoporosis.

  14. Blocking of Single α-Hemolysin Pore by Rhodamine Derivatives.

    Science.gov (United States)

    Rokitskaya, Tatyana I; Nazarov, Pavel A; Golovin, Andrey V; Antonenko, Yuri N

    2017-06-06

    Measurements of ion conductance through α-hemolysin pore in a bilayer lipid membrane revealed blocking of the ion channel by a series of rhodamine 19 and rhodamine B esters. The longest dwell closed time of the blocking was observed with rhodamine 19 butyl ester (C4R1), whereas the octyl ester (C8R1) was of poor effect. Voltage asymmetry in the binding kinetics indicated that rhodamine derivatives bound to the stem part of the aqueous pore lumen. The binding frequency was proportional to a quadratic function of rhodamine concentrations, thereby showing that the dominant binding species were rhodamine dimers. Two levels of the pore conductance and two dwell closed times of the pore were found. The dwell closed times lengthened as the voltage increased, suggesting impermeability of the channel for the ligands. Molecular docking analysis revealed two distinct binding sites within the lumen of the stem of the α-hemolysin pore for the C4R1 dimer, but only one binding site for the C8R1 dimer. The blocking of the α-hemolysin nanopore by rhodamines could be utilized in DNA sequencing as additional optical sensing owing to bright fluorescence of rhodamines if used for DNA labeling. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  15. MODERN ROUTES TO EXPLORE CONCRETE’S COMPLEX PORE SPACE

    Directory of Open Access Journals (Sweden)

    Piet Stroeven

    2011-05-01

    Full Text Available This paper concentrates on discrete element computer-simulation of concrete. It is argued on the basis of stochastic heterogeneity theory that modern concurrent-algorithm-based systems should be employed for the assessment of pore characteristics underlying durability performance of cementitious materials. The SPACE system was developed at Delft University of Technology for producing realistic schematizations of realcrete for a wide range of other particle packing problems, involving aggregate and fresh cement, and for the purpose of exploring characteristics in the hardened state of concrete, including of the pore network structure because of obvious durability problems. Since structure-sensitive properties are involved, schematization of reality should explicitly deal with the configuration of the cement particles in the fresh state. The paper concentrates on the stereological and mathematical morphology operations executed to acquire information on particle size, global porosity, and on distribution of porosity and of the connected pore fraction as a result of the near neighbourhood of aggregate grains. Goal is to provide information obtained along different exploration routes of concrete's pore space for setting up a pore network modelling approach. This type of methodological papers is scarce in concrete technology, if not missing at all. Technical publications that report on obtained results in our investigations are systematically referred to.

  16. Self-injection locking of the DFB laser through an external ring fiber cavity: Polarization behavior

    Directory of Open Access Journals (Sweden)

    J.L. Bueno Escobedo

    Full Text Available We study stability of self-injection locking realized with DFB laser coupled with an external fiber optic ring cavity. Polarization behavior of the radiation circulating in the feedback loop is reported. Two regimes of mode hopping have been observed; one of them is accompanied by polarization bistability involving two orthogonal polarization states. Keywords: Self-injection locking, Polarization, Optical fiber

  17. A free software for pore-scale modelling: solving Stokes equation for velocity fields and permeability values in 3D pore geometries

    KAUST Repository

    Gerke, Kirill; Vasilyev, Roman; Khirevich, Siarhei; Karsanina, Marina; Collins, Daniel; Korost, Dmitry; Mallants, Dirk

    2015-01-01

    In this contribution we introduce a novel free software which solves the Stokes equation to obtain velocity fields for low Reynolds-number flows within externally generated 3D pore geometries. Provided with velocity fields, one can calculate permeability for known pressure gradient boundary conditions via Darcy's equation. Finite-difference schemes of 2nd and 4th order of accuracy are used together with an artificial compressibility method to iteratively converge to a steady-state solution of Stokes' equation. This numerical approach is much faster and less computationally demanding than the majority of open-source or commercial softwares employing other algorithms (finite elements/volumes, lattice Boltzmann, etc.) The software consists of two parts: 1) a pre and post-processing graphical interface, and 2) a solver. The latter is efficiently parallelized to use any number of available cores (the speedup on 16 threads was up to 10-12 depending on hardware). Due to parallelization and memory optimization our software can be used to obtain solutions for 300x300x300 voxels geometries on modern desktop PCs. The software was successfully verified by testing it against lattice Boltzmann simulations and analytical solutions. To illustrate the software's applicability for numerous problems in Earth Sciences, a number of case studies have been developed: 1) identifying the representative elementary volume for permeability determination within a sandstone sample, 2) derivation of permeability/hydraulic conductivity values for rock and soil samples and comparing those with experimentally obtained values, 3) revealing the influence of the amount of fine-textured material such as clay on filtration properties of sandy soil. This work was partially supported by RSF grant 14-17-00658 (pore-scale modelling) and RFBR grants 13-04-00409-a and 13-05-01176-a.

  18. A free software for pore-scale modelling: solving Stokes equation for velocity fields and permeability values in 3D pore geometries

    KAUST Repository

    Gerke, Kirill

    2015-04-01

    In this contribution we introduce a novel free software which solves the Stokes equation to obtain velocity fields for low Reynolds-number flows within externally generated 3D pore geometries. Provided with velocity fields, one can calculate permeability for known pressure gradient boundary conditions via Darcy\\'s equation. Finite-difference schemes of 2nd and 4th order of accuracy are used together with an artificial compressibility method to iteratively converge to a steady-state solution of Stokes\\' equation. This numerical approach is much faster and less computationally demanding than the majority of open-source or commercial softwares employing other algorithms (finite elements/volumes, lattice Boltzmann, etc.) The software consists of two parts: 1) a pre and post-processing graphical interface, and 2) a solver. The latter is efficiently parallelized to use any number of available cores (the speedup on 16 threads was up to 10-12 depending on hardware). Due to parallelization and memory optimization our software can be used to obtain solutions for 300x300x300 voxels geometries on modern desktop PCs. The software was successfully verified by testing it against lattice Boltzmann simulations and analytical solutions. To illustrate the software\\'s applicability for numerous problems in Earth Sciences, a number of case studies have been developed: 1) identifying the representative elementary volume for permeability determination within a sandstone sample, 2) derivation of permeability/hydraulic conductivity values for rock and soil samples and comparing those with experimentally obtained values, 3) revealing the influence of the amount of fine-textured material such as clay on filtration properties of sandy soil. This work was partially supported by RSF grant 14-17-00658 (pore-scale modelling) and RFBR grants 13-04-00409-a and 13-05-01176-a.

  19. One-loop tensor Feynman integral reduction with signed minors

    International Nuclear Information System (INIS)

    Fleischer, J.; Yundin, V.

    2011-12-01

    We present an algebraic approach to one-loop tensor integral reduction. The integrals are presented in terms of scalar one- to four-point functions. The reduction is worked out explicitly until five-point functions of rank five. The numerical C++ package PJFry evaluates tensor coefficients in terms of a basis of scalar integrals, which is provided by an external library, e.g. QCDLoop. We shortly describe installation and use of PJFry. Examples for numerical results are shown, including a special treatment for small or vanishing inverse four-point Gram determinants. An extremely efficient application of the formalism is the immediate evaluation of complete contractions of the tensor integrals with external momenta. This leads to the problem of evaluating sums over products of signed minors with scalar products of chords. Chords are differences of external momenta. These sums may be evaluated analytically in a systematic way. The final expressions for the numerical evaluation are then compact combinations of the contributing basic scalar functions. (orig.)

  20. One-loop tensor Feynman integral reduction with signed minors

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, J. [Bielefeld Univ. (Germany). Fakultaet fuer Physik; Riemann, T. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Yundin, V. [Copenhagen Univ. (Denmark). Niels Bohr International Academy and Discovery Center

    2011-12-15

    We present an algebraic approach to one-loop tensor integral reduction. The integrals are presented in terms of scalar one- to four-point functions. The reduction is worked out explicitly until five-point functions of rank five. The numerical C++ package PJFry evaluates tensor coefficients in terms of a basis of scalar integrals, which is provided by an external library, e.g. QCDLoop. We shortly describe installation and use of PJFry. Examples for numerical results are shown, including a special treatment for small or vanishing inverse four-point Gram determinants. An extremely efficient application of the formalism is the immediate evaluation of complete contractions of the tensor integrals with external momenta. This leads to the problem of evaluating sums over products of signed minors with scalar products of chords. Chords are differences of external momenta. These sums may be evaluated analytically in a systematic way. The final expressions for the numerical evaluation are then compact combinations of the contributing basic scalar functions. (orig.)

  1. Supersymmetric Yang-Mills and supergravity amplitudes at one loop

    International Nuclear Information System (INIS)

    Hall, Anthony

    2009-01-01

    By applying the known expressions for super Yang-Mills (SYM) and supergravity (SUGRA) tree amplitudes, we write generating functions for the next-to-next-to-maximally helicity violating (NNMHV) box coefficients of SYM as well as the maximally helicity violating, next-to-maximally helicity violating, and NNMHV box coefficients for SUGRA. The all-multiplicity generating functions utilize covariant, on-shell superspace whereby the contribution from arbitrary external states in the supermultiplet can be extracted by Grassmann operators. In support of the relation between dual-Wilson loops and SYM scattering amplitudes at weak coupling, the SYM amplitudes are presented in a manifestly dual superconformal form. We introduce ordered box coefficients for calculating SUGRA quadruple cuts and prove that ordered coefficients generate physical cut amplitudes after summing over permutations of the external legs. The ordered box coefficients are produced by sewing ordered subamplitudes, previously used in applying on-shell recursion relations at tree level. We describe our verification of the results against the literature, and a formula for extracting the contributions from external gluons or gravitons to NNMHV superamplitudes is presented.

  2. Newtonian gravity in loop quantum gravity

    OpenAIRE

    Smolin, Lee

    2010-01-01

    We apply a recent argument of Verlinde to loop quantum gravity, to conclude that Newton's law of gravity emerges in an appropriate limit and setting. This is possible because the relationship between area and entropy is realized in loop quantum gravity when boundaries are imposed on a quantum spacetime.

  3. Holonomy loops, spectral triples and quantum gravity

    DEFF Research Database (Denmark)

    Johannes, Aastrup; Grimstrup, Jesper Møller; Nest, Ryszard

    2009-01-01

    We review the motivation, construction and physical interpretation of a semi-finite spectral triple obtained through a rearrangement of central elements of loop quantum gravity. The triple is based on a countable set of oriented graphs and the algebra consists of generalized holonomy loops...

  4. Conformal anomaly of super Wilson loop

    Energy Technology Data Exchange (ETDEWEB)

    Belitsky, A.V., E-mail: andrei.belitsky@asu.edu [Department of Physics, Arizona State University, Tempe, AZ 85287-1504 (United States)

    2012-09-11

    Classically supersymmetric Wilson loop on a null polygonal contour possesses all symmetries required to match it onto non-MHV amplitudes in maximally supersymmetric Yang-Mills theory. However, to define it quantum mechanically, one is forced to regularize it since perturbative loop diagrams are not well defined due to presence of ultraviolet divergences stemming from integration in the vicinity of the cusps. A regularization that is adopted by practitioners by allowing one to use spinor helicity formalism, on the one hand, and systematically go to higher orders of perturbation theory is based on a version of dimensional regularization, known as Four-Dimensional Helicity scheme. Recently it was demonstrated that its use for the super Wilson loop at one loop breaks both conformal symmetry and Poincare supersymmetry. Presently, we exhibit the origin for these effects and demonstrate how one can undo this breaking. The phenomenon is alike the one emerging in renormalization group mixing of conformal operators in conformal theories when one uses dimensional regularization. The rotation matrix to the diagonal basis is found by means of computing the anomaly in the Ward identity for the conformal boost. Presently, we apply this ideology to the super Wilson loop. We compute the one-loop conformal anomaly for the super Wilson loop and find that the anomaly depends on its Grassmann coordinates. By subtracting this anomalous contribution from the super Wilson loop we restore its interpretation as a dual description for reduced non-MHV amplitudes which are expressed in terms of superconformal invariants.

  5. Feedback loop compensates for rectifier nonlinearity

    Science.gov (United States)

    1966-01-01

    Signal processing circuit with two negative feedback loops rectifies two sinusoidal signals which are 180 degrees out of phase and produces a single full-wave rectified output signal. Each feedback loop incorporates a feedback rectifier to compensate for the nonlinearity of the circuit.

  6. Loop calculus for lattice gauge theories

    International Nuclear Information System (INIS)

    Gambini, R.; Leal, L.; Trias, A.; Departamento de Fisica Aplicada, Facultad de Ingenieria, Universidad Central de Venezuela, Apartado 47724, Caracas 1051, Venezuela; Departament de Matematiques, Universitat Politecnica de Catalunya, Escuela Tecnica Superior de Enginyers de Telecomunicaciones, Barcelona 08034, Spain)

    1989-01-01

    Hamiltonian calculations are performed using a loop-labeled basis where the full set of identities for the SU(N) gauge models has been incorporated. The loops are classified as clusterlike structures and the eigenvalue problem leads to a linear set of finite-difference equations easily amenable to numerical treatment. Encouraging results are reported for SU(2) at spatial dimension 2

  7. Design Principles for Closed Loop Supply Chains

    NARCIS (Netherlands)

    H.R. Krikke (Harold); C.P. Pappis (Costas); G.T. Tsoulfas; J.M. Bloemhof-Ruwaard (Jacqueline)

    2001-01-01

    textabstractIn this paper we study design principles for closed loop supply chains. Closed loop supply chains aim at closing material flows thereby limiting emission and residual waste, but also providing customer service at low cost. We study 'traditional' and 'new' design principles known in the

  8. Why liquid displacement methods are sometimes wrong in estimating the pore-size distribution

    NARCIS (Netherlands)

    Gijsbertsen-Abrahamse, A.J.; Boom, R.M.; Padt, van der A.

    2004-01-01

    The liquid displacement method is a commonly used method to determine the pore size distribution of micro- and ultrafiltration membranes. One of the assumptions for the calculation of the pore sizes is that the pores are parallel and thus are not interconnected. To show that the estimated pore size

  9. Highly Aminated Mesoporous Silica Nanoparticles with Cubic Pore Structure

    KAUST Repository

    Suteewong, Teeraporn

    2011-01-19

    Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.

  10. Highly Aminated Mesoporous Silica Nanoparticles with Cubic Pore Structure

    KAUST Repository

    Suteewong, Teeraporn; Sai, Hiroaki; Cohen, Roy; Wang, Suntao; Bradbury, Michelle; Baird, Barbara; Gruner, Sol M.; Wiesner, Ulrich

    2011-01-01

    Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.

  11. Fines Classification Based on Sensitivity to Pore-Fluid Chemistry

    KAUST Repository

    Jang, Junbong

    2015-12-28

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil "electrical sensitivity." Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems. © ASCE.

  12. Fines classification based on sensitivity to pore-fluid chemistry

    Science.gov (United States)

    Jang, Junbong; Santamarina, J. Carlos

    2016-01-01

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing characteristic of fine grains, pore-fluid chemistry is not addressed in current classification systems. Liquid limits obtained with electrically contrasting pore fluids (deionized water, 2-M NaCl brine, and kerosene) are combined to define the soil “electrical sensitivity.” Liquid limit and electrical sensitivity can be effectively used to classify fine grains according to their fluid-soil response into no-, low-, intermediate-, or high-plasticity fine grains of low, intermediate, or high electrical sensitivity. The proposed methodology benefits from the accumulated experience with liquid limit in the field and addresses the needs of a broader range of geotechnical engineering problems.

  13. Influence of crosslinking agents on the pore structure of skin.

    Science.gov (United States)

    Fathima, N Nishad; Dhathathreyan, Aruna; Ramasami, T

    2007-05-15

    Analysis of pore structure of skin is important to understand process of diffusion and adsorption involved during any application of the skin matrix. In this study, the effect of thermal shrinkage on the pore structure of chromium and vegetable treated skin has been analyzed as these tanning agents are known to bring about thermal stability to the matrix. The changes brought about in the pore structure have been studied using mercury intrusion porosimetry and scanning electron microscopy. Response of the chromium treated and vegetable tanning treated skin structure to heat has been found to be quite different from each other. About 41% decrease in porosity is observed for chromium treated skin as against 97% decrease for the skin treated with vegetable tannins. This is primarily attributed to the basic nature of these materials and the nature of interaction of them towards skin.

  14. Internal and External Reconnection Series Homologous Solar Flares

    Science.gov (United States)

    Sterling, Alphonse C.; Moore, Ronald L.

    2001-01-01

    Using data from the extreme ultraviolet imaging telescope (EIT) on SOHO and the soft X-ray telescope (SXT) on Yohkoh, we examine a series of morphologically homologous solar flares occurring in National Oceanic and Atmospheric Administration (NOAA) active region 8210 over May 1-2, 1998. An emerging flux region (EFR) impacted against a sunspot to the west and next to a coronal hole to the east is the source of the repeated flaring. An SXT sigmoid parallels the EFR's neutral line at the site of the initial flaring in soft X rays. In EIT each flaring episode begins with the formation of a crinkle pattern external to the EFR. These EIT crinkles move out from, and then in toward, the EFR with velocities approx. 20 km/ s. A shrinking and expansion of the width of the coronal hole coincides with the crinkle activity, and generation and evolution of a postflare loop system begins near the time of crinkle formation. Using a schematic based on magnetograms of the region, we suggest that these observations are consistent with the standard reconnection-based model for solar eruptions but are modified by the presence of the additional magnetic fields of the sunspot and coronal hole. In the schematic, internal reconnection begins inside of the EFR-associated fields, unleashing a flare, postflare loops, and a coronal mass ejection (CME). External reconnection, first occurring between the escaping CME and the coronal hole field and second occurring between fields formed as a result of the first external reconnection, results in the EIT crinkles and changes in the coronal hole boundary. By the end of the second external reconnection, the initial setup is reinstated; thus the sequence can repeat, resulting in morphologically homologous eruptions. Our inferred magnetic topology is similar to that suggested in the "breakout model" of eruptions although we cannot determine if our eruptions are released primarily by the breakout mechanism (external reconnection) or, alternatively

  15. The Wilson loop and some applications

    International Nuclear Information System (INIS)

    Bezerra, V.B.

    1983-04-01

    A simple relation between the classical Wilson loop and the angular deviation in the parallel displacement is found. An example of potentials which give field copies and which suplly the same classical Wilson loop for a particular trajectory is exhibited. The asymptotic behaviour of the Wilson loop for the BPST instanton and the meron, is discussed. By using the dimensional regularization technique to calculate the second order term of the quantum Wilson loop, the influence of geometrical factors for the residue in the pole due to contact points, cuspides and intersections, in function of the space-time ν, is investigated. Charge renormalization in Quantum electrodynamics is finally calculated by using the quantum Wilson loop. (L.C.) [pt

  16. The Wilson loop and some applications

    International Nuclear Information System (INIS)

    Bezerra, V.B.

    1983-01-01

    A simple relation between the classical Wilson loop and the angular deviation in the parallel shift is found. An example of potential which given field copies and which give the same classical Wilson loop for a given trajectory is exchibited. Afterwards, the asymptotic behaviour of the Wilson loop for the BPST instanton and meron is discussed. Using the dimensional regularization technique to calculate the second order term of Quantum Wilson loop, the influence of geometrical factors for the residue in the polo due to contact points, cusp and intersections, in function of the upsilon dimension of the space-time is investigated. Finally, the charge renormalization in Quantum Electrodynamics using Quantum Wilson loop is calculated. (L.C.) [pt

  17. Hydraulic loop: practices using open control systems

    International Nuclear Information System (INIS)

    Carrasco, J.A.; Alonso, L.; Sanchez, F.

    1998-01-01

    The Tecnatom Hydraulic Loop is a dynamic training platform. It has been designed with the purpose of improving the work in teams. With this system, the student can obtain a full scope vision of a system. The hydraulic Loop is a part of the Tecnatom Maintenance Centre. The first objective of the hydraulic Loop is the instruction in components, process and process control using open control system. All the personal of an electric power plant can be trained in the Hydraulic Loop with specific courses. The development of a dynamic tool for tests previous to plant installations has been an additional objective of the Hydraulic Loop. The use of this platform is complementary to the use of full-scope simulators in order to debug and to analyse advanced control strategies. (Author)

  18. Osmotic mechanism of the loop extrusion process

    Science.gov (United States)

    Yamamoto, Tetsuya; Schiessel, Helmut

    2017-09-01

    The loop extrusion theory assumes that protein factors, such as cohesin rings, act as molecular motors that extrude chromatin loops. However, recent single molecule experiments have shown that cohesin does not show motor activity. To predict the physical mechanism involved in loop extrusion, we here theoretically analyze the dynamics of cohesin rings on a loop, where a cohesin loader is in the middle and unloaders at the ends. Cohesin monomers bind to the loader rather frequently and cohesin dimers bind to this site only occasionally. Our theory predicts that a cohesin dimer extrudes loops by the osmotic pressure of cohesin monomers on the chromatin fiber between the two connected rings. With this mechanism, the frequency of the interactions between chromatin segments depends on the loading and unloading rates of dimers at the corresponding sites.

  19. Feedback Loop Gains and Feedback Behavior (1996)

    DEFF Research Database (Denmark)

    Kampmann, Christian Erik

    2012-01-01

    Linking feedback loops and system behavior is part of the foundation of system dynamics, yet the lack of formal tools has so far prevented a systematic application of the concept, except for very simple systems. Having such tools at their disposal would be a great help to analysts in understanding...... large, complicated simulation models. The paper applies tools from graph theory formally linking individual feedback loop strengths to the system eigenvalues. The significance of a link or a loop gain and an eigenvalue can be expressed in the eigenvalue elasticity, i.e., the relative change...... of an eigenvalue resulting from a relative change in the gain. The elasticities of individual links and loops may be found through simple matrix operations on the linearized system. Even though the number of feedback loops can grow rapidly with system size, reaching astronomical proportions even for modest systems...

  20. The Disulfide Bond Cys255-Cys279 in the Immunoglobulin-Like Domain of Anthrax Toxin Receptor 2 Is Required for Membrane Insertion of Anthrax Protective Antigen Pore.

    Directory of Open Access Journals (Sweden)

    Pedro Jacquez

    Full Text Available Anthrax toxin receptors act as molecular clamps or switches that control anthrax toxin entry, pH-dependent pore formation, and translocation of enzymatic moieties across the endosomal membranes. We previously reported that reduction of the disulfide bonds in the immunoglobulin-like (Ig domain of the anthrax toxin receptor 2 (ANTXR2 inhibited the function of the protective antigen (PA pore. In the present study, the disulfide linkage in the Ig domain was identified as Cys255-Cys279 and Cys230-Cys315. Specific disulfide bond deletion mutants were achieved by replacing Cys residues with Ala residues. Deletion of the disulfide bond C255-C279, but not C230-C315, inhibited the PA pore-induced release of the fluorescence dyes from the liposomes, suggesting that C255-C279 is essential for PA pore function. Furthermore, we found that deletion of C255-C279 did not affect PA prepore-to-pore conversion, but inhibited PA pore membrane insertion by trapping the PA membrane-inserting loops in proteinaceous hydrophobic pockets. Fluorescence spectra of Trp59, a residue adjacent to the PA-binding motif in von Willebrand factor A (VWA domain of ANTXR2, showed that deletion of C255-C279 resulted in a significant conformational change on the receptor ectodomain. The disulfide deletion-induced conformational change on the VWA domain was further confirmed by single-particle 3D reconstruction of the negatively stained PA-receptor heptameric complexes. Together, the biochemical and structural data obtained in this study provides a mechanistic insight into the role of the receptor disulfide bond C255-C279 in anthrax toxin action. Manipulation of the redox states of the receptor, specifically targeting to C255-C279, may become a novel strategy to treat anthrax.

  1. Employing optical code division multiple access technology in the all fiber loop vibration sensor system

    Science.gov (United States)

    Tseng, Shin-Pin; Yen, Chih-Ta; Syu, Rong-Shun; Cheng, Hsu-Chih

    2013-12-01

    This study proposes a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) framework to access the vibration frequency of a test object on the all fiber loop vibration sensor (AFLVS). Each user possesses an individual SAC, and fiber Bragg grating (FBG) encoders/decoders using multiple FBG arrays were adopted, providing excellent orthogonal properties in the frequency domain. The system also mitigates multiple access interference (MAI) among users. When an optical fiber is bent to a point exceeding the critical radius, the fiber loop sensor becomes sensitive to external physical parameters (e.g., temperature, strain, and vibration). The AFLVS involves placing a fiber loop with a specific radius on a designed vibration platform.

  2. Evaluation of Colloid Retention Site Dominance in Variably Saturated Porous Media: An All Pores Pore-Scale Analysis

    Science.gov (United States)

    Morales, Veronica; Perez-Reche, Francisco; Holzner, Markus; Kinzelbach, Wolfgang

    2016-04-01

    It is well accepted that colloid and nanoparticle transport processes in porous media differ substantially between water saturated and unsaturated conditions. Differences are frequently ascribed to particle immobilization by association with interfaces with the gas, as well as to restrictions of the liquid medium through which colloids are transported. Yet, the current understanding of the importance of particle retention at gas interfaces is based on observations of single pores or two-dimensional pore network representations, leaving open the question of their statistical significance when all pores in the medium are considered. In order to address this question, column experiments were performed using a model porous medium of glass beads through which Silver particles were transported for conditions of varying water content and water chemistry. X-ray microtomography was subsequently employed as a non-destructive imaging technique to obtain pore-scale information of the entire column regarding: i) the presence and distribution of the main locations where colloids can become retained (interfaces with the water-solid, air-water, air-solid, and air-water-solid, grain-grain contacts, and the bulk liquid), ii) deposition profiles of colloids along the column classified by the available retention location, and iii) channel widths of 3-dimensional pore-water network representations. The results presented provide a direct statistical evaluation on the significance of colloid retention by attachment to interfaces or by strainig at contact points where multiple interfaces meet.

  3. Pore-Width-Dependent Preferential Interaction of sp2 Carbon Atoms in Cyclohexene with Graphitic Slit Pores by GCMC Simulation

    Directory of Open Access Journals (Sweden)

    Natsuko Kojima

    2011-01-01

    Full Text Available The adsorption of cyclohexene with two sp2 and four sp3 carbon atoms in graphitic slit pores was studied by performing grand canonical Monte Carlo simulation. The molecular arrangement of the cyclohexene on the graphitic carbon wall depends on the pore width. The distribution peak of the sp2 carbon is closer to the pore wall than that of the sp3 carbon except for the pore width of 0.7 nm, even though the Lennard-Jones size of the sp2 carbon is larger than that of the sp3 carbon. Thus, the difference in the interactions of the sp2 and sp3 carbon atoms of cyclohexene with the carbon pore walls is clearly observed in this study. The preferential interaction of sp2 carbon gives rise to a slight tilting of the cyclohexene molecule against the graphitic wall. This is suggestive of a π-π interaction between the sp2 carbon in the cyclohexene molecule and graphitic carbon.

  4. Dispersion upscaling from a pore scale characterization of Lagrangian velocities

    Science.gov (United States)

    Turuban, Régis; de Anna, Pietro; Jiménez-Martínez, Joaquín; Tabuteau, Hervé; Méheust, Yves; Le Borgne, Tanguy

    2013-04-01

    Mixing and reactive transport are primarily controlled by the interplay between diffusion, advection and reaction at pore scale. Yet, how the distribution and spatial correlation of the velocity field at pore scale impact these processes is still an open question. Here we present an experimental investigation of the distribution and correlation of pore scale velocities and its relation with upscaled dispersion. We use a quasi two-dimensional (2D) horizontal set up, consisting of two glass plates filled with cylinders representing the grains of the porous medium : the cell is built by soft lithography technique, wich allows for full control of the system geometry. The local velocity field is quantified from particle tracking velocimetry using microspheres that are advected with the pore scale flow. Their displacement is purely advective, as the particle size is chosen large enough to avoid diffusion. We thus obtain particle trajectories as well as lagrangian velocities in the entire system. The measured velocity field shows the existence of a network of preferential flow paths in channels with high velocities, as well as very low velocity in stagnation zones, with a non Gaussian distribution. Lagrangian velocities are long range correlated in time, which implies a non-fickian scaling of the longitudinal variance of particle positions. To upscale this process we develop an effective transport model, based on correlated continous time random walk, which is entirely parametrized by the pore scale velocity distribution and correlation. The model predictions are compared with conservative tracer test data for different Peclet numbers. Furthermore, we investigate the impact of different pore geometries on the distribution and correlation of Lagrangian velocities and we discuss the link between these properties and the effective dispersion behavior.

  5. Pore-water chemistry explains zinc phytotoxicity in soil.

    Science.gov (United States)

    Kader, Mohammed; Lamb, Dane T; Correll, Ray; Megharaj, Mallavarapu; Naidu, Ravi

    2015-12-01

    Zinc (Zn) is a widespread soil contaminant arising from a numerous anthropogenic sources. However, adequately predicting toxicity of Zn to ecological receptors remains difficult due to the complexity of soil characteristics. In this study, we examined solid-solution partitioning using pore-water data and toxicity of Zn to cucumber (Cucumis sativus L.) in spiked soils. Pore-water effective concentration (ECx, x=10%, 20% and 50% reduction) values were negatively related to pH, indicating lower Zn pore water concentration were needed to cause phytotoxicity at high pH soils. Total dissolved zinc (Znpw) and free zinc (Zn(2+)) in soil-pore water successfully described 78% and 80.3% of the variation in relative growth (%) in the full dataset. When the complete data set was used (10 soils), the estimated EC50pw was 450 and 79.2 µM for Znpw and Zn(2+), respectively. Total added Zn, soil pore water pH (pHpw) and dissolve organic carbon (DOC) were the best predictors of Znpw and Zn(2+) in pore-water. The EC10 (total loading) values ranged from 179 to 5214 mg/kg, depending on soil type. Only pH measurements in soil were related to ECx total Zn data. The strongest relationship to ECx overall was pHca, although pHw and pHpw were in general related to Zn ECx. Similarly, when a solution-only model was used to predict Zn in shoot, DOC was negatively related to Zn in shoot, indicating a reduction in uptake/ translocation of Zn from solution with increasing DOC. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Microfluidic Experiments Studying Pore Scale Interactions of Microbes and Geochemistry

    Science.gov (United States)

    Chen, M.; Kocar, B. D.

    2016-12-01

    Understanding how physical phenomena, chemical reactions, and microbial behavior interact at the pore-scale is crucial to understanding larger scale trends in groundwater chemistry. Recent studies illustrate the utility of microfluidic devices for illuminating pore-scale physical-biogeochemical processes and their control(s) on the cycling of iron, uranium, and other important elements 1-3. These experimental systems are ideal for examining geochemical reactions mediated by microbes, which include processes governed by complex biological phenomenon (e.g. biofilm formation, etc.)4. We present results of microfluidic experiments using a model metal reducing bacteria and varying pore geometries, exploring the limitations of the microorganisms' ability to access tight pore spaces, and examining coupled biogeochemical-physical controls on the cycling of redox sensitive metals. Experimental results will provide an enhanced understanding of coupled physical-biogeochemical processes transpiring at the pore-scale, and will constrain and compliment continuum models used to predict and describe the subsurface cycling of redox-sensitive elements5. 1. Vrionis, H. A. et al. Microbiological and geochemical heterogeneity in an in situ uranium bioremediation field site. Appl. Environ. Microbiol. 71, 6308-6318 (2005). 2. Pearce, C. I. et al. Pore-scale characterization of biogeochemical controls on iron and uranium speciation under flow conditions. Environ. Sci. Technol. 46, 7992-8000 (2012). 3. Zhang, C., Liu, C. & Shi, Z. Micromodel investigation of transport effect on the kinetics of reductive dissolution of hematite. Environ. Sci. Technol. 47, 4131-4139 (2013). 4. Ginn, T. R. et al. Processes in microbial transport in the natural subsurface. Adv. Water Resour. 25, 1017-1042 (2002). 5. Scheibe, T. D. et al. Coupling a genome-scale metabolic model with a reactive transport model to describe in situ uranium bioremediation. Microb. Biotechnol. 2, 274-286 (2009).

  7. A kinematic view of loop closure.

    Science.gov (United States)

    Coutsias, Evangelos A; Seok, Chaok; Jacobson, Matthew P; Dill, Ken A

    2004-03-01

    We consider the problem of loop closure, i.e., of finding the ensemble of possible backbone structures of a chain segment of a protein molecule that is geometrically consistent with preceding and following parts of the chain whose structures are given. We reduce this problem of determining the loop conformations of six torsions to finding the real roots of a 16th degree polynomial in one variable, based on the robotics literature on the kinematics of the equivalent rotator linkage in the most general case of oblique rotators. We provide a simple intuitive view and derivation of the polynomial for the case in which each of the three pair of torsional axes has a common point. Our method generalizes previous work on analytical loop closure in that the torsion angles need not be consecutive, and any rigid intervening segments are allowed between the free torsions. Our approach also allows for a small degree of flexibility in the bond angles and the peptide torsion angles; this substantially enlarges the space of solvable configurations as is demonstrated by an application of the method to the modeling of cyclic pentapeptides. We give further applications to two important problems. First, we show that this analytical loop closure algorithm can be efficiently combined with an existing loop-construction algorithm to sample loops longer than three residues. Second, we show that Monte Carlo minimization is made severalfold more efficient by employing the local moves generated by the loop closure algorithm, when applied to the global minimization of an eight-residue loop. Our loop closure algorithm is freely available at http://dillgroup. ucsf.edu/loop_closure/. Copyright 2004 Wiley Periodicals, Inc. J Comput Chem 25: 510-528, 2004

  8. An addendum to the Heisenberg-Euler effective action beyond one loop

    Energy Technology Data Exchange (ETDEWEB)

    Gies, Holger; Karbstein, Felix [Helmholtz-Institut Jena,Fröbelstieg 3, 07743 Jena (Germany); Theoretisch-Physikalisches Institut, Abbe Center of Photonics,Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany)

    2017-03-21

    We study the effective interactions of external electromagnetic fields induced by fluctuations of virtual particles in the vacuum of quantum electrodynamics. Our main focus is on these interactions at two-loop order. We discuss in detail the emergence of the renowned Heisenberg-Euler effective action from the underlying microscopic theory of quantum electrodynamics, emphasizing its distinction from a standard one-particle irreducible effective action. In our explicit calculations we limit ourselves to constant and slowly varying external fields, allowing us to adopt a locally constant field approximation. One of our main findings is that at two-loop order there is a finite one-particle reducible contribution to the Heisenberg-Euler effective action in constant fields, which was previously assumed to vanish. In addition to their conceptual significance, our results are relevant for high-precision probes of quantum vacuum nonlinearity in strong electromagnetic fields.

  9. Silicon pore optics for future x-ray telescopes

    DEFF Research Database (Denmark)

    Wille, Eric; Bavdaz, Marcos; Wallace, Kotska

    2017-01-01

    arcsec or better. These specifications can only be achieved with a novel technology like Silicon Pore Optics, which is being developed by ESA together with a consortium of European industry. Silicon Pore Optics are made of commercial Si wafers using process technology adapted from the semiconductor...... industry. We present the recent upgrades made to the manufacturing processes and equipment, ranging from the manufacture of single mirror plates towards complete focusing mirror modules mounted in flight configuration, and results from first vibration tests. The performance of the mirror modules is tested...

  10. Gas Adsorption in Novel Environments, Including Effects of Pore Relaxation

    International Nuclear Information System (INIS)

    Cole, Milton W; Gatica, Silvina M; Kim, Hye-Young; Lueking, Angela D; Sircar, Sarmishtha

    2012-01-01

    Adsorption experiments have been interpreted frequently with simplified model geometries, such as ideally flat surfaces and slit or cylindrical pores. Recent explorations of unusual environments, such as fullerenes and metal-organic-framework materials, have led to a broadened scope of experimental, theoretical and simulation investigations. This paper reviews a number of such studies undertaken by our group. Among the topics receiving emphasis are these: universality of gas uptake in pores, relaxation of a porous absorbent due to gas uptake and the novel phases of gases on a single nanotube, all of which studies have been motivated by recent experiments.

  11. Role of scaffold mean pore size in meniscus regeneration.

    Science.gov (United States)

    Zhang, Zheng-Zheng; Jiang, Dong; Ding, Jian-Xun; Wang, Shao-Jie; Zhang, Lei; Zhang, Ji-Ying; Qi, Yan-Song; Chen, Xue-Si; Yu, Jia-Kuo

    2016-10-01

    Recently, meniscus tissue engineering offers a promising management for meniscus regeneration. Although rarely reported, the microarchitectures of scaffolds can deeply influence the behaviors of endogenous or exogenous stem/progenitor cells and subsequent tissue formation in meniscus tissue engineering. Herein, a series of three-dimensional (3D) poly(ε-caprolactone) (PCL) scaffolds with three distinct mean pore sizes (i.e., 215, 320, and 515μm) were fabricated via fused deposition modeling. The scaffold with the mean pore size of 215μm significantly improved both the proliferation and extracellular matrix (ECM) production/deposition of mesenchymal stem cells compared to all other groups in vitro. Moreover, scaffolds with mean pore size of 215μm exhibited the greatest tensile and compressive moduli in all the acellular and cellular studies. In addition, the relatively better results of fibrocartilaginous tissue formation and chondroprotection were observed in the 215μm scaffold group after substituting the rabbit medial meniscectomy for 12weeks. Overall, the mean pore size of 3D-printed PCL scaffold could affect cell behavior, ECM production, biomechanics, and repair effect significantly. The PCL scaffold with mean pore size of 215μm presented superior results both in vitro and in vivo, which could be an alternative for meniscus tissue engineering. Meniscus tissue engineering provides a promising strategy for meniscus regeneration. In this regard, the microarchitectures (e.g., mean pore size) of scaffolds remarkably impact the behaviors of cells and subsequent tissue formation, which has been rarely reported. Herein, three three-dimensional poly(ε-caprolactone) scaffolds with different mean pore sizes (i.e., 215, 320, and 515μm) were fabricated via fused deposition modeling. The results suggested that the mean pore size significantly affected the behaviors of endogenous or exogenous stem/progenitor cells and subsequent tissue formation. This study furthers

  12. Dynamics of phase ordering of nematics in a pore

    International Nuclear Information System (INIS)

    Bhattacharya, A.; Chakrabarti, A.

    1994-06-01

    We study the kinetics of phase ordering of a nematic liquid crystal, modeled by a spin-rotor Hamiltonian, confined within a parallel piped pore. The dynamics of the rotor obeys the time-dependent Ginzburg-Landau equation. We study the generation and evolution of a variety of defect structures, and the growth of domains, with different anchoring conditions at the pore surface. Unlike in binary fluids, mere confinement with no anchoring field, does not result in slow dynamics. Homeotropic anchoring, however, leads to slow logarithmic growth. Interestingly, homogeneous anchoring dynamically generates wall defects, resulting in an Ising like structure factor at late times. (author). 27 refs, 4 figs

  13. Sequence-structure relationships in RNA loops: establishing the basis for loop homology modeling.

    Science.gov (United States)

    Schudoma, Christian; May, Patrick; Nikiforova, Viktoria; Walther, Dirk

    2010-01-01

    The specific function of RNA molecules frequently resides in their seemingly unstructured loop regions. We performed a systematic analysis of RNA loops extracted from experimentally determined three-dimensional structures of RNA molecules. A comprehensive loop-structure data set was created and organized into distinct clusters based on structural and sequence similarity. We detected clear evidence of the hallmark of homology present in the sequence-structure relationships in loops. Loops differing by structures. Thus, our results support the application of homology modeling for RNA loop model building. We established a threshold that may guide the sequence divergence-based selection of template structures for RNA loop homology modeling. Of all possible sequences that are, under the assumption of isosteric relationships, theoretically compatible with actual sequences observed in RNA structures, only a small fraction is contained in the Rfam database of RNA sequences and classes implying that the actual RNA loop space may consist of a limited number of unique loop structures and conserved sequences. The loop-structure data sets are made available via an online database, RLooM. RLooM also offers functionalities for the modeling of RNA loop structures in support of RNA engineering and design efforts.

  14. A general reduction method for one-loop N-point integrals

    International Nuclear Information System (INIS)

    Heinrich, G.; Binoth, T.

    2000-01-01

    In order to calculate cross sections with a large number of particles/jets in the final state at next-to-leading order, one has to reduce the occurring scalar and tensor one-loop integrals to a small set of known integrals. In massless theories, this reduction procedure is complicated by the presence of infrared divergences. Working in n = 4 - 2ε dimensions, it will be outlined how to achieve such a reduction for diagrams with an arbitrary number of external legs. As a result, any integral with more than four propagators and generic 4-dimensional external momenta can be reduced to box integrals

  15. BOKASUN: a fast and precise numerical program to calculate the Master Integrals of the two-loop sunrise diagrams

    OpenAIRE

    Caffo, Michele; Czyz, Henryk; Gunia, Michal; Remiddi, Ettore

    2008-01-01

    We present the program BOKASUN for fast and precise evaluation of the Master Integrals of the two-loop self-mass sunrise diagram for arbitrary values of the internal masses and the external four-momentum. We use a combination of two methods: a Bernoulli accelerated series expansion and a Runge-Kutta numerical solution of a system of linear differential equations.

  16. A Series Active Damper with Closed-loop Control for Stabilizing Single-phase Power-Electronics-Based Power System

    DEFF Research Database (Denmark)

    Lu, Dapeng; Wang, Xiongfei; Bai, Haofeng

    2016-01-01

    resistance through detection and resonant controller, the series active damper can suppress the resonance with its external damping character in closed-loop damping character are carried out. Simulation and experimental results are presented to verify the effectiveness of the proposed series active damper....

  17. Pore facies analysis: incorporation of rock properties into pore geometry based classes in a Permo-Triassic carbonate reservoir in the Persian Gulf

    International Nuclear Information System (INIS)

    Rahimpour-Bonab, H; Aliakbardoust, E

    2014-01-01

    Pore facies analysis is a useful method for the classification of reservoir rocks according to pore geometry characteristics. The importance of this method is related to the dependence of the dynamic behaviour of the reservoir rock on the pore geometry. In this study, pore facies analysis was performed by the quantification and classification of the mercury injection capillary pressure (MICP) curves applying the multi-resolution graph-based clustering (MRGC) method. Each pore facies includes a limited variety of rock samples with different depositional fabrics and diagenetic histories, which are representative of one type of pore geometry. The present pore geometry is the result of the interaction between the primary rock fabric and its diagenetic overprint. Thus the variations in petrographic properties can be correlated with the pore geometry characteristics. Accordingly, the controlling parameters in the pore geometry characteristics were revealed by detailed petrographic analysis in each pore facies. The reservoir rock samples were then classified using the determined petrographic properties which control the pore system quality. This method is proposed for the classification of reservoir rocks in complicated carbonate reservoirs, in order to reduce the incompatibility of traditional facies analysis with pore system characteristics. The method is applicable where enough capillary pressure data is not available. (papers)

  18. An approach to the calculation of many-loop massless Feynman integrals

    International Nuclear Information System (INIS)

    Gorishnii, S.G.; Isaev, A.P.

    1985-01-01

    A generalization of the identity of dimensionless regular-zation is proposed. The generalization is used to divide the complete set of dimensionally (and analytically) regularized Feynman integrals with one external momentum into classes of equal integrals, and also for calculating some of them. A nontrivial symmetry of the propagator integrals is revealed, on the basis of which a complete system of functional equations for determining two-loop integrals is derived. Possible generalizations of these equations are discussed

  19. Structure of liquid metal cooled nuclear reactor with loops and steady vessel

    International Nuclear Information System (INIS)

    Costes, D.

    1990-01-01

    This structure comprises, in a vessel containing liquid metal, a nuclear core steadied on an alimentation diagrid and external loops comprising heat exchanger and reinjection pump of sodium in the diagrid. The vessel has the bottom resting on the concrete surround with a thermal stratification of the sodium between the bottom and the diagrid. This disposition has for advantage to allow a vertical connection of the sodium reinjection channel. This channel is contained in a metal sheath with a sliding leak tightness [fr

  20. TS LOOP ALCOVE VENTILATION ANALYSIS

    International Nuclear Information System (INIS)

    T.M. Lahnalampi

    2000-01-01

    The scope of this analysis is to examine the existing, constructor installed, physical ventilation installations located in each of the Exploratory Studies Facility (ESF) Topopah Springs (TS) Loop Alcoves No.1, No.2, No.3, No.4, No.6, and No.7. Alcove No.5 is excluded from the scope of this analysis since it is an A/E design system. Each ventilation installation will be analyzed for the purpose of determining if requirements for acceptance into the A/E design technical baseline have been met. The ventilation installations will be evaluated using Occupational Safety and Health Administration (OSHA) standards and Exploratory Studies Facility Design Requirements (ESFDR) (YMP 1997) requirements. The end product will be a technical analysis that will define ventilation installation compliance issues, any outstanding field changes, and use-as-is design deviations that are required to bring the ventilation installations into compliance with requirements for acceptance into the A/E design technical baseline. The analysis will provide guidance for alcove ventilation component design modifications to be developed to correct any deficient components that do not meet minimum requirements and standards

  1. Loops in hierarchical channel networks

    Science.gov (United States)

    Katifori, Eleni; Magnasco, Marcelo

    2012-02-01

    Nature provides us with many examples of planar distribution and structural networks having dense sets of closed loops. An archetype of this form of network organization is the vasculature of dicotyledonous leaves, which showcases a hierarchically-nested architecture. Although a number of methods have been proposed to measure aspects of the structure of such networks, a robust metric to quantify their hierarchical organization is still lacking. We present an algorithmic framework that allows mapping loopy networks to binary trees, preserving in the connectivity of the trees the architecture of the original graph. We apply this framework to investigate computer generated and natural graphs extracted from digitized images of dicotyledonous leaves and animal vasculature. We calculate various metrics on the corresponding trees and discuss the relationship of these quantities to the architectural organization of the original graphs. This algorithmic framework decouples the geometric information from the metric topology (connectivity and edge weight) and it ultimately allows us to perform a quantitative statistical comparison between predictions of theoretical models and naturally occurring loopy graphs.

  2. Towards conformal loop quantum gravity

    International Nuclear Information System (INIS)

    Wang, Charles H-T

    2006-01-01

    A discussion is given of recent developments in canonical gravity that assimilates the conformal analysis of gravitational degrees of freedom. The work is motivated by the problem of time in quantum gravity and is carried out at the metric and the triad levels. At the metric level, it is shown that by extending the Arnowitt-Deser-Misner (ADM) phase space of general relativity (GR), a conformal form of geometrodynamics can be constructed. In addition to the Hamiltonian and Diffeomorphism constraints, an extra first class constraint is introduced to generate conformal transformations. This phase space consists of York's mean extrinsic curvature time, conformal three-metric and their momenta. At the triad level, the phase space of GR is further enlarged by incorporating spin-gauge as well as conformal symmetries. This leads to a canonical formulation of GR using a new set of real spin connection variables. The resulting gravitational constraints are first class, consisting of the Hamiltonian constraint and the canonical generators for spin-gauge and conformorphism transformations. The formulation has a remarkable feature of being parameter-free. Indeed, it is shown that a conformal parameter of the Barbero-Immirzi type can be absorbed by the conformal symmetry of the extended phase space. This gives rise to an alternative approach to loop quantum gravity that addresses both the conceptual problem of time and the technical problem of functional calculus in quantum gravity

  3. Capillary pressure-saturation relationships for porous granular materials: Pore morphology method vs. pore unit assembly method

    Science.gov (United States)

    Sweijen, Thomas; Aslannejad, Hamed; Hassanizadeh, S. Majid

    2017-09-01

    In studies of two-phase flow in complex porous media it is often desirable to have an estimation of the capillary pressure-saturation curve prior to measurements. Therefore, we compare in this research the capability of three pore-scale approaches in reproducing experimentally measured capillary pressure-saturation curves. To do so, we have generated 12 packings of spheres that are representative of four different glass-bead packings and eight different sand packings, for which we have found experimental data on the capillary pressure-saturation curve in the literature. In generating the packings, we matched the particle size distributions and porosity values of the granular materials. We have used three different pore-scale approaches for generating the capillary pressure-saturation curves of each packing: i) the Pore Unit Assembly (PUA) method in combination with the Mayer and Stowe-Princen (MS-P) approximation for estimating the entry pressures of pore throats, ii) the PUA method in combination with the hemisphere approximation, and iii) the Pore Morphology Method (PMM) in combination with the hemisphere approximation. The three approaches were also used to produce capillary pressure-saturation curves for the coating layer of paper, used in inkjet printing. Curves for such layers are extremely difficult to determine experimentally, due to their very small thickness and the presence of extremely small pores (less than one micrometer in size). Results indicate that the PMM and PUA-hemisphere method give similar capillary pressure-saturation curves, because both methods rely on a hemisphere to represent the air-water interface. The ability of the hemisphere approximation and the MS-P approximation to reproduce correct capillary pressure seems to depend on the type of particle size distribution, with the hemisphere approximation working well for narrowly distributed granular materials.

  4. The ExternE project: methodology, objectives and limitations

    International Nuclear Information System (INIS)

    Rabl, A.; Spadaro, J.V.

    2002-01-01

    This paper presents a summary of recent studies on external costs of energy systems, in particular the ExternE (External Costs of Energy) Project of the European Commission. To evaluate the impact and damage cost of a pollutant, one needs to carry out an impact pathway analysis; this involves the calculation of increased pollutant concentrations in all affected regions due to an incremental emission (e.g. μg/m 3 of particles, using models of atmospheric dispersion and chemistry), followed by the calculation of physical impacts (e.g. number of cases of asthma due to these particles, using a dose-response function). The entire so-called fuel chain (or fuel cycle) is evaluated and compared on the basis of delivered end use energy. Even though the uncertainties are large, the results provide substantial evidence that the classical air pollutants (particles, NO x and SO x ) from the combustion of fossil fuels impose a heavy toll, in addition to the cost of global warming. The external costs are especially large for coal; even for 'good current technology' they may be comparable to the price of electricity. For natural gas the external costs are about a third to a half of coal. The external costs of nuclear are small compared to the price of electricity (at most a few %), and so are the external costs of most renewable energy systems. (authors)

  5. A transimpedance amplifier using a novel current mode feedback loop

    CERN Document Server

    Anghinolfi, Francis; Delagnes, E; Jarron, Pierre; Scharfetter, L H H

    1995-01-01

    We present a transimpedance amplifier stage based on a novel current mode feedback topology. This circuit employs NMOS and PMOS transistors exclusively and requires neither capacitor for stabilizing the transimpedance loop nor resistor for the transresistance feedback and transistor loading. This amplifier circuit is fully compatible with submicron digital CMOS processes. The active feedback network consists of two grounded-gate MOS devices which split the output current in both the feedback and output branches. The transresistance and the phase margin are adjustable through external DC signals. The measured rise time of the impulse response of the amplifier implemented in an industrial 0,7µm CMOS process is 18 ns for a transresistance of 180 k‡ and 30 ns for a transresistance of 560 k‡. The measured Equivalent Noise Charge (ENC) is 800 rms e¯ for an input capacitance of 20 pF with the transresistance adjusted to 560 k‡.

  6. Foundry fabricated photonic integrated circuit optical phase lock loop.

    Science.gov (United States)

    Bałakier, Katarzyna; Fice, Martyn J; Ponnampalam, Lalitha; Graham, Chris S; Wonfor, Adrian; Seeds, Alwyn J; Renaud, Cyril C

    2017-07-24

    This paper describes the first foundry-based InP photonic integrated circuit (PIC) designed to work within a heterodyne optical phase locked loop (OPLL). The PIC and an external electronic circuit were used to phase-lock a single-line semiconductor laser diode to an incoming reference laser, with tuneable frequency offset from 4 GHz to 12 GHz. The PIC contains 33 active and passive components monolithically integrated on a single chip, fully demonstrating the capability of a generic foundry PIC fabrication model. The electronic part of the OPLL consists of commercially available RF components. This semi-packaged system stabilizes the phase and frequency of the integrated laser so that an absolute frequency, high-purity heterodyne signal can be generated when the OPLL is in operation, with phase noise lower than -100 dBc/Hz at 10 kHz offset from the carrier. This is the lowest phase noise level ever demonstrated by monolithically integrated OPLLs.

  7. Arbitrary digital pulse sequence generator with delay-loop timing

    Science.gov (United States)

    Hošák, Radim; Ježek, Miroslav

    2018-04-01

    We propose an idea of an electronic multi-channel arbitrary digital sequence generator with temporal granularity equal to two clock cycles. We implement the generator with 32 channels using a low-cost ARM microcontroller and demonstrate its capability to produce temporal delays ranging from tens of nanoseconds to hundreds of seconds, with 24 ns timing granularity and linear scaling of delay with respect to the number of delay loop iterations. The generator is optionally synchronized with an external clock source to provide 100 ps jitter and overall sequence repeatability within the whole temporal range. The generator is fully programmable and able to produce digital sequences of high complexity. The concept of the generator can be implemented using different microcontrollers and applied for controlling of various optical, atomic, and nuclear physics measurement setups.

  8. Stability, structure, and evolution of cool loops

    International Nuclear Information System (INIS)

    Cally, P.S.; Robb, T.D.

    1991-01-01

    The criteria for the existence and stability of cool loops are reexamined. It is found that the stability of the loops strongly depends on the form of the heating and radiative loss functions and that if the Ly-alpha peak which appears in most calculations of the radiative loss function is real, cool loops are almost certainly unstable. Removing the hydrogen contribution from the recent loss function Q(T) by Cook et al. (1989) does not produce the much-used result, Q proportional to T-cubed, which is so favorable to cool loop stability. Even using the probably unrealistically favorable loss function Q1 of Cook et al. with the hydrogen contribution removed, the maximum temperature attainable in stable cool loops is a factor of 2-3 too small to account for the excess emission observed in lower transition region lines. Dynamical simulations of cool loop instabilities reveal that the final state of such a model is the hot loop equilibrium. 26 refs

  9. Second and third stages of project for the implementation of two asymmetric cooling loops modeled by the ALMOD3 code

    International Nuclear Information System (INIS)

    Dominguez, L.; Camargo, C.T.M.

    1985-04-01

    The second and third steps of the project for implementation of two non-symmetric cooling loops modeled by the ALMOD3 computer code are presented. These steps consists in activate the option for 2 loops already present in ALMOD3 original version and to introduce the GEVAP model for one of the two steam generators. In ALMOD3 original version the simulation of two non-symmetric loops was only possible using external functions, which provide the removed heat for each time step for one of the steam generators. With the introduction of GEVAP model, it is possible to obtain more accurate results. Due to its simplicity, the computer time required for execution is short. The results obtained in Angra 1 simulations are presented, analysed and compared with results obtained using one loop for simulating symmetric transients. (Author) [pt

  10. Septal Pore Caps in Basidiomycetes, Composition and Ultrastructure

    NARCIS (Netherlands)

    Driel, K.G.A. van

    2007-01-01

    Filamentous fungi, including Ascomycota and Basidiomycota, form mycelia that consist of a network of apical growing hyphae. These hyphae are separated into cellular compartments by septa that have pores of about 70 to 500 nm in diameter. The cytoplasm within the mycelium is thus continuous

  11. Enhanced water transport and salt rejection through hydrophobic zeolite pores

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N.

    2017-12-01

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  12. Pore-scale uncertainty quantification with multilevel Monte Carlo

    KAUST Repository

    Icardi, Matteo

    2014-01-06

    Computational fluid dynamics (CFD) simulations of pore-scale transport processes in porous media have recently gained large popularity. However the geometrical details of the pore structures can be known only in a very low number of samples and the detailed flow computations can be carried out only on a limited number of cases. The explicit introduction of randomness in the geometry and in other setup parameters can be crucial for the optimization of pore-scale investigations for random homogenization. Since there are no generic ways to parametrize the randomness in the porescale structures, Monte Carlo techniques are the most accessible to compute statistics. We propose a multilevel Monte Carlo (MLMC) technique to reduce the computational cost of estimating quantities of interest within a prescribed accuracy constraint. Random samples of pore geometries with a hierarchy of geometrical complexities and grid refinements, are synthetically generated and used to propagate the uncertainties in the flow simulations and compute statistics of macro-scale effective parameters.

  13. The dimension of the pore space in sponges

    International Nuclear Information System (INIS)

    Silva, L H F; Yamashita, M T

    2009-01-01

    A simple experiment to reveal the dimension of the pore space in sponges is proposed. This experiment is suitable for the first year of a physics or engineering course. The calculated dimension of the void space in a sponge of density 16 mg cm -3 was 2.948± 0.008

  14. Microstructural characterization and pore structure analysis of nuclear graphite

    International Nuclear Information System (INIS)

    Kane, J.; Karthik, C.; Butt, D.P.; Windes, W.E.; Ubic, R.

    2011-01-01

    Graphite will be used as a structural and moderator material in next-generation nuclear reactors. While the overall nature of the production of nuclear graphite is well understood, the historic nuclear grades of graphite are no longer available. This paper reports the virgin microstructural characteristics of filler particles and macro-scale porosity in virgin nuclear graphite grades of interest to the Next Generation Nuclear Plant program. Optical microscopy was used to characterize filler particle size and shape as well as the arrangement of shrinkage cracks. Computer aided image analysis was applied to optical images to quantitatively determine the variation of pore structure, area, eccentricity, and orientation within and between grades. The overall porosity ranged between ∼14% and 21%. A few large pores constitute the majority of the overall porosity. The distribution of pore area in all grades was roughly logarithmic in nature. The average pore was best fit by an ellipse with aspect ratio of ∼2. An estimated 0.6-0.9% of observed porosity was attributed to shrinkage cracks in the filler particles. Finally, a preferred orientation of the porosity was observed in all grades.

  15. Energetics of Transport through the Nuclear Pore Complex

    NARCIS (Netherlands)

    Ghavami, Ali; van der Giessen, Erik; Onck, Patrick R

    2016-01-01

    Molecular transport across the nuclear envelope in eukaryotic cells is solely controlled by the nuclear pore complex (NPC). The NPC provides two types of nucleocytoplasmic transport: passive diffusion of small molecules and active chaperon-mediated translocation of large molecules. It has been shown

  16. The hydraulic conductivity of sediments: A pore size perspective

    KAUST Repository

    Ren, X.W.

    2017-12-06

    This article presents an analysis of previously published hydraulic conductivity data for a wide range of sediments. All soils exhibit a prevalent power trend between the hydraulic conductivity and void ratio. Data trends span 12 orders of magnitude in hydraulic conductivity and collapse onto a single narrow trend when the hydraulic conductivity data are plotted versus the mean pore size, estimated using void ratio and specific surface area measurements. The sensitivity of hydraulic conductivity to changes in the void ratio is higher than the theoretical value due to two concurrent phenomena: 1) percolating large pores are responsible for most of the flow, and 2) the larger pores close first during compaction. The prediction of hydraulic conductivity based on macroscale index parameters in this and similar previous studies has reached an asymptote in the range of kmeas/5≤kpredict≤5kmeas. The remaining uncertainty underscores the important role of underlying sediment characteristics such as pore size distribution, shape, and connectivity that are not measured with index properties. Furthermore, the anisotropy in hydraulic conductivity cannot be recovered from scalar parameters such as index properties. Overall, results highlight the robustness of the physics inspired data scrutiny based Hagen–Poiseuille and Kozeny-Carman analyses.

  17. On the Mechanism of Pore Formation by Melittin

    NARCIS (Netherlands)

    van den Bogaart, Geert; Guzman, Jeanette Velasquez; Mika, Jacek T.; Poolman, Bert

    2008-01-01

    The mechanism of pore formation of lytic peptides, such as melittin from bee venom, is thought to involve binding to the membrane surface, followed by insertion at threshold levels of bound peptide. We show that in membranes composed of zwitterionic lipids, i.e. phosphatidylcholine, melittin not

  18. Plastic strain caused by contraction of pores in polycrystalline graphites

    International Nuclear Information System (INIS)

    Ioka, Ikuo; Yoda, Shinichi; Konishi, Takashi.

    1989-01-01

    The effects of porosity on mechanical properties and deformation behavior of four isotropic polycrystalline graphites were studied. The pore size distributions of the graphites were measured using a conventional mercury penetration technique. The average pore radius of ISO-88 graphite was about one-tenth of that of ISEM-1, IG-11 or IG-15 graphites. Young's modulus of the graphites decreased with increasing porosity. The stress-strain curve of each graphite was measured in its lateral and axial directions. Young's modulus of graphite decreased with increasing load. The plastic strain at a given compressive load was calculated from the stress-strain curve and the initial gradient of the unloading curve at the load. The ratio of lateral plastic strain to axial plastic strain for the graphites was less than 0.5, indicating that the volume of the graphites decreased during compressive loading. By assuming that the volume change was caused by contraction of pores, plastic strain associated with contraction of pores was calculated from the axial plastic strain and lateral plastic strain by slips along the basal planes. The plastic strain increased with increasing axial plastic strain and porosity of graphite. (author)

  19. Pore collapse and regrowth in silicon electrodes for rechargeable batteries

    Energy Technology Data Exchange (ETDEWEB)

    DeCaluwe, S. C. [Department of Mechanical Engineering; Colorado School of Mines; USA; Center for Neutron Research; National Institute of Standards and Technology; Dhar, B. M. [Institute for Materials Research and Dept. of Mechanical Engineering; State University of New York; Binghamton; USA; Material Measurement Laboratory; Huang, L. [Institute for Materials Research and Dept. of Mechanical Engineering; State University of New York; Binghamton; USA; He, Y. [Institute for Materials Research and Dept. of Mechanical Engineering; State University of New York; Binghamton; USA; Department of Physics and Astronomy; Yang, K. [Institute for Materials Research and Dept. of Mechanical Engineering; State University of New York; Binghamton; USA; Owejan, J. P. [Department of Mechanical and Electrical Engineering Technology; State University of New York; Alfred; USA; Zhao, Y. [Department of Physics and Astronomy; University of Georgia; Athens; USA; Talin, A. A. [Center for Nanoscale Science and Technology; National Institute of Standards and Technology; Gaithersburg; USA; Sandia National Laboratories; Dura, J. A. [Center for Neutron Research; National Institute of Standards and Technology; Gaithersburg; USA; Wang, H. [Department of Materials Science and Engineering; University of Maryland; College Park; USA; Institute for Materials Research and Dept. of Mechanical Engineering

    2015-01-01

    In-operando Neutron Reflectometry establishes the pore collapse and regrowth (PCRG) mechanism in amorphous Si. Upon lithiation, porosity is first consumed by expansion of solid Si domains, with little thickness increase. After, the whole film expands. Porosity returns upon delithiation.

  20. Alumina ceramics prepared with new pore-forming agents

    Directory of Open Access Journals (Sweden)

    Zuzana Živcová

    2008-06-01

    Full Text Available Porous ceramics have a wide range of applications at all length scales, ranging from fi ltration membranes and catalyst supports to biomaterials (scaffolds for bone ingrowths and thermally or acoustically insulating bulk materials or coating layers. Organic pore-forming agents (PFAs of biological origin can be used to control porosity, pore size and pore shape. This work concerns the characterization and testing of several less common pore-forming agents (lycopodium, coffee, fl our and semolina, poppy seed, which are of potential interest from the viewpoint of size, shape or availability. The performance of these new PFAs is compared to that of starch, which has become a rather popular PFA for ceramics during the last decade. The PFAs investigated in this work are in the size range from 5 μm (rice starch to approximately 1 mm (poppy seed, all with more or less isometric shape. The burnout behavior of PFAs is studied by thermal analysis, i.e. thermogravimetry and differential thermal analysis. For the preparation of porous alumina ceramics from alumina suspensions containing PFAs traditional slip casting (into plaster molds and starch consolidation casting (using metal molds are used in this work. The resulting microstructures are investigated using optical microscopy, combined with image analysis, as well as other methods (Archimedes method of double-weighing in water, mercury intrusion porosimetry.

  1. Enhanced water transport and salt rejection through hydrophobic zeolite pores.

    Science.gov (United States)

    Humplik, Thomas; Lee, Jongho; O'Hern, Sean; Laoui, Tahar; Karnik, Rohit; Wang, Evelyn N

    2017-12-15

    The potential of improvements to reverse osmosis (RO) desalination by incorporating porous nanostructured materials such as zeolites into the selective layer in the membrane has spurred substantial research efforts over the past decade. However, because of the lack of methods to probe transport across these materials, it is still unclear which pore size or internal surface chemistry is optimal for maximizing permeability and salt rejection. We developed a platform to measure the transport of water and salt across a single layer of zeolite crystals, elucidating the effects of internal wettability on water and salt transport through the ≈5.5 Å pores of MFI zeolites. MFI zeolites with a more hydrophobic (i.e., less attractive) internal surface chemistry facilitated an approximately order of magnitude increase in water permeability compared to more hydrophilic MFI zeolites, while simultaneously fully rejecting both potassium and chlorine ions. However, our results also demonstrated approximately two orders of magnitude lower permeability compared to molecular simulations. This decreased performance suggests that additional transport resistances (such as surface barriers, pore collapse or blockages due to contamination) may be limiting the performance of experimental nanostructured membranes. Nevertheless, the inclusion of hydrophobic sub-nanometer pores into the active layer of RO membranes should improve both the water permeability and salt rejection of future RO membranes (Fasano et al 2016 Nat. Commun. 7 12762).

  2. Concentration Polarization to Measure Nano-pore Accessibility

    NARCIS (Netherlands)

    Solsona, Miguel; Eijkel, Jan C.T.; Olthuis, Wouter; Papadimitriou, Vasileios; van den Berg, Albert; Abelmann, Leon; Weckhuysen, Bert M.; Nieuwelink, A. E.

    2017-01-01

    Understanding the deactivation process in porous catalysts is of tremendous economic significance. We demonstrate the feasibility of using the concentration polarization method to obtain the pore accessibility distribution at single particle level for the first time. By using this technique we could

  3. Fines Classification Based on Sensitivity to Pore-Fluid Chemistry

    KAUST Repository

    Jang, Junbong; Santamarina, Carlos

    2015-01-01

    The 75-μm particle size is used to discriminate between fine and coarse grains. Further analysis of fine grains is typically based on the plasticity chart. Whereas pore-fluid-chemistry-dependent soil response is a salient and distinguishing

  4. Theory of vibratory mobilization and break-up of non-wetting fluids entrapped in pore constrictions

    Science.gov (United States)

    Beresnev, I.; Li, W.; Vigil, D.

    2006-12-01

    Quantitative dynamics of a non-wetting (e. g., NAPL) ganglion entrapped in a pore constriction and subjected to vibrations can be approximated by the equation of motion of an oscillator moving under the effect of the external pressure gradient, inertial oscillatory force, and restoring capillary force. The solution of the equation provides the conditions under which the droplet experiences forced oscillations without being mobilized or is liberated upon the acceleration of the wall exceeding an "unplugging" threshold. This solution provides a quantitative tool for the estimation of the parameters of vibratory fields needed to liberate entrapped non-wetting fluids. For typical pore sizes encountered in reservoirs and aquifers, wall accelerations must exceed at least several m/sec2 and even higher levels to mobilize the droplets of NAPL; however, in the populations of ganglia entrapped in natural porous environments, many may reside very near their mobilization thresholds and may be mobilized by extremely low accelerations as well. For given acceleration, lower seismic frequencies are more efficient. The ganglia may also break up into smaller pieces when passing through pore constrictions. The snap-off is governed by the geometry only; for constrictions with sinusoidal profile (spatial wavelength of L and maximum and minimum radii of rmax and rmin, the break-up occurs if L > 2π(rmin rmax)1/2. Computational fluid dynamics shows the details of the break-up process.

  5. Ambitwistor strings and the scattering equations at one loop

    Energy Technology Data Exchange (ETDEWEB)

    Adamo, Tim; Casali, Eduardo; Skinner, David [Department of Applied Mathematics & Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2014-04-15

    Ambitwistor strings are chiral, infinite tension analogues of conventional string theory whose target space is the space of complex null geodesics and whose spectrum consists exclusively of massless states. At genus zero, these strings underpin the Cachazo-He-Yuan formulæ for tree level scattering of gravitons, gluons and scalars. In this paper we extend these formulæ in a number of directions. Firstly, we consider Ramond sector vertex operators and construct simple amplitudes involving space-time fermions. These agree with tree amplitudes in ten dimensional supergravity and super Yang-Mills. We then show that, after the usual GSO projections, the ambitwistor string partition function is modular invariant. We consider the scattering equations at genus one, and calculate one loop scattering amplitudes for NS-NS external states in the Type II ambitwistor string. We conjecture that these give new representations of (the integrand of) one loop supergravity amplitudes and we show that they have the expected behaviour under factorization of the worldsheet in both non-separating and separating degenerations.

  6. A translational platform for prototyping closed-loop neuromodulation systems

    Science.gov (United States)

    Afshar, Pedram; Khambhati, Ankit; Stanslaski, Scott; Carlson, David; Jensen, Randy; Linde, Dave; Dani, Siddharth; Lazarewicz, Maciej; Cong, Peng; Giftakis, Jon; Stypulkowski, Paul; Denison, Tim

    2013-01-01

    While modulating neural activity through stimulation is an effective treatment for neurological diseases such as Parkinson's disease and essential tremor, an opportunity for improving neuromodulation therapy remains in automatically adjusting therapy to continuously optimize patient outcomes. Practical issues associated with achieving this include the paucity of human data related to disease states, poorly validated estimators of patient state, and unknown dynamic mappings of optimal stimulation parameters based on estimated states. To overcome these challenges, we present an investigational platform including: an implanted sensing and stimulation device to collect data and run automated closed-loop algorithms; an external tool to prototype classifier and control-policy algorithms; and real-time telemetry to update the implanted device firmware and monitor its state. The prototyping system was demonstrated in a chronic large animal model studying hippocampal dynamics. We used the platform to find biomarkers of the observed states and transfer functions of different stimulation amplitudes. Data showed that moderate levels of stimulation suppress hippocampal beta activity, while high levels of stimulation produce seizure-like after-discharge activity. The biomarker and transfer function observations were mapped into classifier and control-policy algorithms, which were downloaded to the implanted device to continuously titrate stimulation amplitude for the desired network effect. The platform is designed to be a flexible prototyping tool and could be used to develop improved mechanistic models and automated closed-loop systems for a variety of neurological disorders. PMID:23346048

  7. Loop-quantum-gravity vertex amplitude.

    Science.gov (United States)

    Engle, Jonathan; Pereira, Roberto; Rovelli, Carlo

    2007-10-19

    Spin foam models are hoped to provide the dynamics of loop-quantum gravity. However, the most popular of these, the Barrett-Crane model, does not have the good boundary state space and there are indications that it fails to yield good low-energy n-point functions. We present an alternative dynamics that can be derived as a quantization of a Regge discretization of Euclidean general relativity, where second class constraints are imposed weakly. Its state space matches the SO(3) loop gravity one and it yields an SO(4)-covariant vertex amplitude for Euclidean loop gravity.

  8. Technical specification of HANARO fuel test loop

    Energy Technology Data Exchange (ETDEWEB)

    Kim, J. Y

    1998-03-01

    The design and installation of the irradiation test facility for verification test of the fuel performance are very important in connection with maximization of the utilization of HANARO. HANARO fuel test loop was designed in accordance with the same code and standards of nuclear power plant because HANARO FTL will be operated the high pressure and temperature same as nuclear power plant operation conditions. The objective of this study is to confirm the operation limit, safety limit, operation condition and checking points of HANARO fuel test loop. This results will become guidances for the planning of irradiation testing and operation of HANARO fuel test loop. (author). 13 refs., 13 tabs., 8 figs.

  9. Numerical approach to one-loop integrals

    International Nuclear Information System (INIS)

    Fujimoto, Junpei; Shimizu, Yoshimitsu; Kato, Kiyoshi; Oyanagi, Yoshio.

    1992-01-01

    Two numerical methods are proposed for the calculation of one-loop scalar integrals. In the first method, the singularity is cancelled by the symmetrization of the integrand and the integration is done by a Monte-Carlo method. In the second one, after the transform of the integrand into a standard form, the integral is reduced into a regular numerical integral. These methods provide us practical tools to evaluate one-loop Feynman diagrams with desired numerical accuracy. They are extended to the integral with numerator and the treatment of the one-loop virtual correction to the cross section is also presented. (author)

  10. Zero point energy of renormalized Wilson loops

    International Nuclear Information System (INIS)

    Hidaka, Yoshimasa; Pisarski, Robert D.

    2009-01-01

    The quark-antiquark potential, and its associated zero point energy, can be extracted from lattice measurements of the Wilson loop. We discuss a unique prescription to renormalize the Wilson loop, for which the perturbative contribution to the zero point energy vanishes identically. A zero point energy can arise nonperturbatively, which we illustrate by considering effective string models. The nonperturbative contribution to the zero point energy vanishes in the Nambu model, but is nonzero when terms for extrinsic curvature are included. At one loop order, the nonperturbative contribution to the zero point energy is negative, regardless of the sign of the extrinsic curvature term.

  11. Loop corrections to primordial non-Gaussianity

    Science.gov (United States)

    Boran, Sibel; Kahya, E. O.

    2018-02-01

    We discuss quantum gravitational loop effects to observable quantities such as curvature power spectrum and primordial non-Gaussianity of cosmic microwave background (CMB) radiation. We first review the previously shown case where one gets a time dependence for zeta-zeta correlator due to loop corrections. Then we investigate the effect of loop corrections to primordial non-Gaussianity of CMB. We conclude that, even with a single scalar inflaton, one might get a huge value for non-Gaussianity which would exceed the observed value by at least 30 orders of magnitude. Finally we discuss the consequences of this result for scalar driven inflationary models.

  12. Sigma models and renormalization of string loops

    International Nuclear Information System (INIS)

    Tseytlin, A.A.

    1989-05-01

    An extension of the ''σ-model β-functions - string equations of motion'' correspondence to the string loop level is discussed. Special emphasis is made on how the renormalization group acts in string loops and, in particular, on the renormalizability property of the generating functional Z-circumflex for string amplitudes (related to the σ model partition function integrated over moduli). Renormalization of Z-circumflex at one and two loop order is analyzed in some detail. We also discuss an approach to renormalization based on operators of insertion of topological fixtures. (author). 70 refs

  13. Construction of the blowdown and condensation loop

    Energy Technology Data Exchange (ETDEWEB)

    Park, Choon Kyung; Song, Chul Kyung; Cho, Seok; Chun, S. Y.; Chung, Moon Ki

    1997-12-01

    The blowdown and condensation loop (B and C loop) has been constructed to get experimental data for designing the safety depressurization system (SDS) and steam sparger which are considered to implement in the Korea Next Generation Reactor (KNGR). In this report, system description on the B and C loop is given in detail, which includes the drawings and technical specification of each component, instrumentation and control system, and the operational procedures and the results of the performance testing. (author). 7 refs., 11 tabs., 48 figs.

  14. Mesoporous templated silicas: stability, pore size engineering and catalytic activation

    International Nuclear Information System (INIS)

    Vansant, Etienne

    2003-01-01

    The Laboratory of Adsorption and Catalysis has focused its research activities on the synthesis and activation of new porous materials. In the past few years, we have succeeded in developing easy and reproducible pathways to synthesize a huge variety of mesoporous crystalline materials. Points of interest in the synthesis of Mesoporous Templated Silicas are (i) stabilization of the structure, to withstand hydrothermal, thermal and mechanical pressure, (ii) pore size engineering to systematically control the pore size, pore volume and the ratio micro/mesopores and (iii) ease and reproducibility of the synthesis procedure, applying green principles, such as template recuperation. By carefully adapting the synthesis conditions and composition of the synthesis gel, using surfactants (long chain quaternary ammonium ions) and co-templates (long chain amines, alcohols or alkanes), the pore size of the obtained materials can be controlled from 1.5 to 7.0 nm, retaining the very narrow pore size distribution. Alternatively, materials with combined micro- and mesoporosity can be synthesized, using neutral surfactants (triblock copolymers). Hereby, the optimization of the SBA-15 and SBA-16 synthesis is being done in order to create mesoporous materials with microporous walls. The second research line is the controlled activation of MTS materials, by grafting or incorporation of catalytic active centers. We have developed for this purpose the Molecular Designed Dispersion method, which uses metal diketonate complexes as precursors. It is shown that in all cases the dispersion of the metal oxides on the surface is much better compared to the conventional grafting techniques. We have studied and published activation with V, Ti, Mo, Fe, Al and Cr species on different MTS materials. The structure and location of the active metal ion is the subject of an extensive spectroscopic investigation, using FT-IR, FT-Raman, UV-Vis DR coupled with selective chemisorption experiments and

  15. Eigenvalue distributions of Wilson loops

    International Nuclear Information System (INIS)

    Lohmayer, Robert

    2010-01-01

    In the first part of this thesis, we focus on the distribution of the eigenvalues of the unitary Wilson loop matrix in the two-dimensional case at arbitrary finite N. To characterize the distribution of the eigenvalues, we introduce three density functions (the ''symmetric'', the ''antisymmetric'', and the ''true'' eigenvalue density) which differ at finite N but possess the same infinite-N limit, exhibiting the Durhuus-Olesen phase transition. Using expansions of determinants and inverse determinants in characters of totally symmetric or totally antisymmetric representations of SU(N), the densities at finite N can be expressed in terms of simple sums involving only dimensions and quadratic Casimir invariants of certain irreducible representations of SU(N), allowing for a numerical computation of the densities at arbitrary N to any desired accuracy. We find that the true eigenvalue density, adding N oscillations to the monotonic symmetric density, is in some sense intermediate between the symmetric and the antisymmetric density, which in turn is given by a sum of N delta peaks located at the zeros of the average of the characteristic polynomial. Furthermore, we show that the dependence on N can be made explicit by deriving integral representations for the resolvents associated to the three eigenvalue densities. Using saddle-point approximations, we confirm that all three densities reduce to the Durhuus-Olesen result in the infinite-N limit. In the second part, we study an exponential form of the multiplicative random complex matrix model introduced by Gudowska-Nowak et al. Varying a parameter which can be identified with the area of the Wilson loop in the unitary case, the region of non-vanishing eigenvalue density of the N-dimensional complex product matrix undergoes a topological change at a transition point in the infinite-N limit. We study the transition by a detailed analysis of the average of the modulus square of the characteristic polynomial. Furthermore

  16. Eigenvalue distributions of Wilson loops

    Energy Technology Data Exchange (ETDEWEB)

    Lohmayer, Robert

    2010-07-01

    In the first part of this thesis, we focus on the distribution of the eigenvalues of the unitary Wilson loop matrix in the two-dimensional case at arbitrary finite N. To characterize the distribution of the eigenvalues, we introduce three density functions (the ''symmetric'', the ''antisymmetric'', and the ''true'' eigenvalue density) which differ at finite N but possess the same infinite-N limit, exhibiting the Durhuus-Olesen phase transition. Using expansions of determinants and inverse determinants in characters of totally symmetric or totally antisymmetric representations of SU(N), the densities at finite N can be expressed in terms of simple sums involving only dimensions and quadratic Casimir invariants of certain irreducible representations of SU(N), allowing for a numerical computation of the densities at arbitrary N to any desired accuracy. We find that the true eigenvalue density, adding N oscillations to the monotonic symmetric density, is in some sense intermediate between the symmetric and the antisymmetric density, which in turn is given by a sum of N delta peaks located at the zeros of the average of the characteristic polynomial. Furthermore, we show that the dependence on N can be made explicit by deriving integral representations for the resolvents associated to the three eigenvalue densities. Using saddle-point approximations, we confirm that all three densities reduce to the Durhuus-Olesen result in the infinite-N limit. In the second part, we study an exponential form of the multiplicative random complex matrix model introduced by Gudowska-Nowak et al. Varying a parameter which can be identified with the area of the Wilson loop in the unitary case, the region of non-vanishing eigenvalue density of the N-dimensional complex product matrix undergoes a topological change at a transition point in the infinite-N limit. We study the transition by a detailed analysis of the average of the

  17. Current-Loop Control for the Pitching Axis of Aerial Cameras via an Improved ADRC

    Directory of Open Access Journals (Sweden)

    BingYou Liu

    2017-01-01

    Full Text Available An improved active disturbance rejection controller (ADRC is designed to eliminate the influences of the current-loop for the pitching axis control system of an aerial camera. The improved ADRC is composed of a tracking differentiator (TD, an improved extended state observer (ESO, an improved nonlinear state error feedback (NLSEF, and a disturbance compensation device (DCD. The TD is used to arrange transient process. The improved ESO is utilized to observe the state extended by nonlinear dynamics, model uncertainty, and external disturbances. Overtime variation of the current-loop can be predicted by the improved ESO. The improved NLSEF is adopted to restrain the residual errors of the current-loop. The DCD is used to compensate the overtime variation of the current-loop in real time. The improved ADRC is designed based on a new nonlinear function newfal(·. This function exhibits enhanced continuity and smoothness compared to previously available nonlinear functions. Thus, the new nonlinear function can effectively decrease the high-frequency flutter phenomenon. The improved ADRC exhibits improved control performance, and disturbances of the current-loop can be eliminated by the improved ADRC. Finally, simulation experiments are performed. Results show that the improved ADRC displayed better performance than the proportional integral (PI control strategy and traditional ADRC.

  18. Adaptive Sliding Mode Control of Dynamic Systems Using Double Loop Recurrent Neural Network Structure.

    Science.gov (United States)

    Fei, Juntao; Lu, Cheng

    2018-04-01

    In this paper, an adaptive sliding mode control system using a double loop recurrent neural network (DLRNN) structure is proposed for a class of nonlinear dynamic systems. A new three-layer RNN is proposed to approximate unknown dynamics with two different kinds of feedback loops where the firing weights and output signal calculated in the last step are stored and used as the feedback signals in each feedback loop. Since the new structure has combined the advantages of internal feedback NN and external feedback NN, it can acquire the internal state information while the output signal is also captured, thus the new designed DLRNN can achieve better approximation performance compared with the regular NNs without feedback loops or the regular RNNs with a single feedback loop. The new proposed DLRNN structure is employed in an equivalent controller to approximate the unknown nonlinear system dynamics, and the parameters of the DLRNN are updated online by adaptive laws to get favorable approximation performance. To investigate the effectiveness of the proposed controller, the designed adaptive sliding mode controller with the DLRNN is applied to a -axis microelectromechanical system gyroscope to control the vibrating dynamics of the proof mass. Simulation results demonstrate that the proposed methodology can achieve good tracking property, and the comparisons of the approximation performance between radial basis function NN, RNN, and DLRNN show that the DLRNN can accurately estimate the unknown dynamics with a fast speed while the internal states of DLRNN are more stable.

  19. Reconfiguration of the NRAD delay loop for proposed 1 MW operations

    International Nuclear Information System (INIS)

    Heidel, C.C.; Richards, W.J.; Pruett, D.P.

    1984-01-01

    Neutron radiography is provided by the NRAD reactor facility, which is located beneath the HFEF hot cell. The NRAD reactor is a TRIGA reactor and is operated at a steady-state power level of 250 kw solely for neutron radiography and the development of radiography techniques. When the NRAD facility was designed and constructed, an operating power level of 250 kw was considered to be adequate for obtaining radiographs of the type of specimens envisaged at that time. Since that time a second radiography station was installed and the thickness of the specimens being radiographed is greater than was initially envisaged. In order to decrease exposure times, the reactor power level is to be increased to 1 Mw. The present delay loop can not to be used at 1 Mw operation, because the passage way where the primary piping exits the reactor room must be maintained less than 1 MR/hr. To obtain the needed delay before the primary water exits the reactor room using the present internal delay loop system would require two more delay loops of the same size to be placed in series with the present delay loop. Because the NRAD reactor tank is small this is not possible; therefore, the delay must take place external to the reactor tank. The delay loop will have to be located in a shielded area to allow the decay of N 16 . The best location for the delay tank will be in the east radiography

  20. Irradiation Testing Vehicles for Fast Reactors from Open Test Assemblies to Closed Loops

    Energy Technology Data Exchange (ETDEWEB)

    Sienicki, James J. [Argonne National Lab. (ANL), Argonne, IL (United States); Grandy, Christopher [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-12-15

    A review of irradiation testing vehicle approaches and designs that have been incorporated into past Sodium-Cooled Fast Reactors (SFRs) or envisioned for incorporation has been carried out. The objective is to understand the essential features of the approaches and designs so that they can inform test vehicle designs for a future U.S. Fast Test Reactor. Fast test reactor designs examined include EBR-II, FFTF, JOYO, BOR-60, PHÉNIX, JHR, and MBIR. Previous designers exhibited great ingenuity in overcoming design and operational challenges especially when the original reactor plant’s mission changed to an irradiation testing mission as in the EBRII reactor plant. The various irradiation testing vehicles can be categorized as: Uninstrumented open assemblies that fit into core locations; Instrumented open test assemblies that fit into special core locations; Self-contained closed loops; and External closed loops. A special emphasis is devoted to closed loops as they are regarded as a very desirable feature of a future U.S. Fast Test Reactor. Closed loops are an important technology for irradiation of fuels and materials in separate controlled environments. The impact of closed loops on the design of fast reactors is also discussed in this report.