WorldWideScience

Sample records for catalyst packing mode

  1. Packing mode and optimization of flotation column

    Energy Technology Data Exchange (ETDEWEB)

    Li Yan-feng; Zhang Min; Liu Jiong-tian [University of Mining and Technology, Xuzhou (China). School of Chemical Engineering and Technology

    2008-04-15

    The effects of the two usual packing types, namely filling material and sieve plates, on flotation environment were analyzed and it was pointed out that sieve plate filling could be integrated with the fluid regime and mineralization environment with the results of stabilizing bubbles and enhancing the efficiencies of flotation and mineralization. The tests show that the ash gradient of the flotation column increases from 1.62%/m to 6.80%/m as a result of sieve plate filling. Material filling can clean the froth, reduce the ash of clean coal and make the froth steady. To form the two non-linear-change separation environments suitable for mineral separation, the mixed filling mode of packing sieve plates in the middle and lower parts of the column and packing material in the foam area was proposed. By optimizing the packing mode, the mixed packing mode of the sieve plates and honeycomb tubes were introduced. The simulation results show that obligatory suppression of the honeycomb tubes make the radial distribution of the fluid at the second sieve plate completely disappear and the axial velocity stable. It makes the flow regime transfers from turbulent flow to plug flow in a short distance come true. 7 refs., 5 figs., 2 tabs.

  2. EFFECTS OF TEMPERATURE AND CATALYST ON OXIDATION OF AQUEOUS CYANIDES IN PACKED COLUMNS

    OpenAIRE

    Ahmet ALICILAR; MURATHAN, Atilla

    2000-01-01

    The oxidation of aqueous cyanides in packed columns has been studied. The experiment was performed in three different temperatures on inert packing at co- and counter-current conditions. In addition to this, experiments made on room temperature were repeated in the presence of catalyst. After reaching to steady state in each case, cyanide concentrations of liquid samples taken from the column outlet were titrimetrically determined. Oxidation yields were calculated by comparing these values to...

  3. Elastic moduli and vibrational modes in jammed particulate packings

    Science.gov (United States)

    Mizuno, Hideyuki; Saitoh, Kuniyasu; Silbert, Leonardo E.

    2016-06-01

    When we elastically impose a homogeneous, affine deformation on amorphous solids, they also undergo an inhomogeneous, nonaffine deformation, which can have a crucial impact on the overall elastic response. To correctly understand the elastic modulus M , it is therefore necessary to take into account not only the affine modulus MA, but also the nonaffine modulus MN that arises from the nonaffine deformation. In the present work, we study the bulk (M =K ) and shear (M =G ) moduli in static jammed particulate packings over a range of packing fractions φ . The affine MA is determined essentially by the static structural arrangement of particles, whereas the nonaffine MN is related to the vibrational eigenmodes. We elucidate the contribution of each vibrational mode to the nonaffine MN through a modal decomposition of the displacement and force fields. In the vicinity of the (un)jamming transition φc, the vibrational density of states g (ω ) shows a plateau in the intermediate-frequency regime above a characteristic frequency ω*. We illustrate that this unusual feature apparent in g (ω ) is reflected in the behavior of MN: As φ →φc , where ω*→0 , those modes for ω ω* approach a constant value which results in MN to approach a critical value MN c, as MN-MN c˜ω* . At φc itself, the bulk modulus attains a finite value Kc=KA c-KN c>0 , such that KN c has a value that remains below KA c. In contrast, for the critical shear modulus Gc, GN c and GA c approach the same value so that the total value becomes exactly zero, Gc=GA c-GN c=0 . We explore what features of the configurational and vibrational properties cause such a distinction between K and G , allowing us to validate analytical expressions for their critical values.

  4. New proposition on performance evaluation of hydrophobic Pt catalyst packed in trickle bed

    International Nuclear Information System (INIS)

    On the evaluation of the performance of the hydrophobic Pt catalyst packed in the trickle-bed test column, the conventionally defined (Ksub(y)a) and the newly defined (Ksub(f))sub (G) are compared with each other as a measure of the overall D-transfer coefficient. The value of (Ksub(y)a) varies in a wide range in accordance with the length of the test column. On the other hand (Ksub(f))sub (G sub (l = L)) has a finite value in the test column longer than about 0.5 m. By considering the values of ksub(g) and ksub(l) which are the constituents of (Ksub(f))sub (G), it is possible to improve the hydrophobic Pt catalyst trickle bed and to design the H2/H2O-isotopic exchange trickle-bed column packed with this catalyst. (author)

  5. Catalyst-Packed Non-Thermal Plasma Reactor for Removal of Nitrogen Oxides

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A single-stage plasma-catalytic reactor in which catalytic materials were packedwas used to remove nitrogen oxides. The packing material was scoria being made of various metaloxides including A12O3, MgO, TiO2, etc. Scoria was able to act not only as dielectric pelletsbut also as a catalyst in the presence of reducing agent such as ethylene and ammonia. Withoutplasma discharge, scoria did not work well as a catalyst in the temperature range of 100 °Cto 200 °C, showing less than 10% of NOx removal efficiency. When plasma is produced inside thereactor, the NOx removal efficiency could be increased to 60% in this temperature range.

  6. Modeling of methanol decomposition on Pt/CeO2/ZrO2 catalyst in a packed bed microreactor

    Science.gov (United States)

    Pohar, Andrej; Belavič, Darko; Dolanc, Gregor; Hočevar, Stanko

    2014-06-01

    Methanol decomposition on Pt/CeO2/ZrO2 catalyst is studied inside a packed bed microreactor in the temperature range of 300-380 °C. The microreactor is fabricated using low-temperature co-fired ceramic (LTCC) technology, which is well suited for the production of relatively complex three-dimensional structures. It is packed with 2 wt% Pt-CeO2 catalyst, which is deposited onto ZrO2 spherical particles. A 1D mathematical model, which incorporates diffusion, convection and mass transfer through the boundary layer to the catalyst particles, as well as a 3D computational fluid dynamics model, are developed to describe the methanol decomposition process inside the packed bed. The microreactor exhibits reliable operation and no catalyst deactivation was observed during three months of experimentation. A comparison between the 1D mathematical model and the 3D model, considering the full 3D geometry of the microreactor is made and the differences between the models are identified and evaluated.

  7. Investigation of hydrodynamic behavior of a pilot-scale trickle bed reactor packed with hydrophobic catalyst using radiotracer technique

    International Nuclear Information System (INIS)

    Exchange of isotopes of hydrogen between aqueous phase and hydrogen gas is one of the most efficient methods for separation of hydrogen isotopes and is commonly used for production of heavy water or removal of tritium from tritiated water effluents. The isotope exchange reaction can be effectively executed in a counter-current trickle bed reactor (TBR) packed with a novel metal (Pt, Pd, Ni) based hydrophobic catalyst as the conventional novel metal based hydrophilic catalysts become ineffective after they come in contact with liquid effluents. The overall exchange reaction in the TBR mainly consists of a gas-liquid mass transfer process that transfers reactants from liquid to gaseous phase followed by an isotopic exchange reaction between the reactants in gaseous phase in presence of a solid hydrophobic catalyst. However, due to water repellent nature of the catalyst, poor liquid distribution in the reactor is normally observed that deteriorates the gas-liquid mass transfer. Therefore, it was thought that if a mixture of hydrophobic catalyst and a suitable hydrophilic mass transfer packing is used to fill the TBR column then, it can improve the distribution or mixing of the liquid and gas phase and thus improve the gas-liquid mass transfer and overall performance of the reactor and needs to be confirmed

  8. Deformation Modes of a Packing of Rigid Grains: Rotation, Counter-rotation, dislocation field

    OpenAIRE

    Evesque, P.

    2005-01-01

    The properties of the processes of deformation of a packing of rigid grains are analysed when the exact distribution of the normal forces at contacts is known. Importance of grain rotation and of counter-rotation of adjacent grains is stressed. It is shown that all deformation modes form an incomplete vectorial space D. This allows the statistics of fluctuation to be determined. Parallel with anti-ferromagnetism is then drawn and frustration of rotation is shown to be the leading dissipating ...

  9. Experimental, kinetic and numerical modeling of hydrogen production by catalytic reforming of crude ethanol over a commercial catalyst in packed bed tubular reactor and packed bed membrane reactor

    International Nuclear Information System (INIS)

    The demand for hydrogen energy has increased tremendously in recent years essentially because of the increase in the word energy consumption as well as recent developments in fuel cell technologies. The energy information administration has projected that world energy consumption will increase by 59% over the next two decades, from 1999 to 2020, in which the largest share is still dominated by fossil fuels (oil, natural gas and coal). Carbon dioxide (CO2) emissions resulting from the combustion of these fossil fuels currently are estimated to account for three-fourth of human-caused CO2 emissions worldwide. Greenhouse gas emission, including CO2, should be limited, as recommended at the Kyoto Conference, Japan, in December 1997. In this regard, hydrogen (H2) has a significant future potential as an alternative fuel that can solve the problems of CO2 emissions as well as the emissions of other air contaminants. One of the techniques to produce hydrogen is by reforming of hydrocarbons or biomass. Crude ethanol (a form of biomass, which essentially is fermentation broth) is easy to produce, is free of sulphur, has low toxicity, and is also safe to handle, transport and store. In addition, crude ethanol consists of oxygenated hydrocarbons, such as ethanol, lactic acid, glycerol, and maltose. These oxygenated hydrocarbons can be reformed completely to H2 and CO2, the latter of which could be separated from H2 by membrane technology. This provides for CO2 capture for eventual storage or destruction. In the case of using crude ethanol, this will result in negative CO2, emissions. In this paper, we conducted experimental work on production of hydrogen by the catalytic reforming of crude ethanol over a commercial promoted Ni-based catalyst in a packed bed tubular reactor as well as a packed bed membrane reactor. As well, a rigorous numerical model was developed to simulate this process in both the catalytic packed bed tubular reactor and packed bed membrane reactor. The

  10. Super-radiant plasmon mode is more efficient for SERS than the sub-radiant mode in highly packed 2D gold nanocube arrays

    International Nuclear Information System (INIS)

    The field coupling in highly packed plasmonic nanoparticle arrays is not localized due to the energy transport via the sub-radiant plasmon modes, which is formed in addition to the regular super-radiant plasmon mode. Unlike the sub-radiant mode, the plasmon field of the super-radiant mode cannot extend over long distances since it decays radiatively with a shorter lifetime. The coupling of the plasmon fields of gold nanocubes (AuNCs) when organized into highly packed 2D arrays was examined experimentally. Multiple plasmon resonance optical peaks are observed for the AuNC arrays and are compared to those calculated using the discrete dipole approximation. The calculated electromagnetic plasmon fields of the arrays displayed high field intensity for the nanocubes located in the center of the arrays for the lower energy super-radiant mode, while the higher energy sub-radiant plasmon mode displayed high field intensity at the edges of the arrays. The Raman signal enhancement by the super-radiant plasmon mode was found to be one hundred fold greater than that by sub-radiant plasmon mode because the super-radiant mode has higher scattering and stronger plasmon field intensity relative to the sub-radiant mode

  11. Super-radiant plasmon mode is more efficient for SERS than the sub-radiant mode in highly packed 2D gold nanocube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Mahmoud A., E-mail: mmahmoud@gatech.edu [Laser Dynamics Laboratory, School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400 (United States)

    2015-08-21

    The field coupling in highly packed plasmonic nanoparticle arrays is not localized due to the energy transport via the sub-radiant plasmon modes, which is formed in addition to the regular super-radiant plasmon mode. Unlike the sub-radiant mode, the plasmon field of the super-radiant mode cannot extend over long distances since it decays radiatively with a shorter lifetime. The coupling of the plasmon fields of gold nanocubes (AuNCs) when organized into highly packed 2D arrays was examined experimentally. Multiple plasmon resonance optical peaks are observed for the AuNC arrays and are compared to those calculated using the discrete dipole approximation. The calculated electromagnetic plasmon fields of the arrays displayed high field intensity for the nanocubes located in the center of the arrays for the lower energy super-radiant mode, while the higher energy sub-radiant plasmon mode displayed high field intensity at the edges of the arrays. The Raman signal enhancement by the super-radiant plasmon mode was found to be one hundred fold greater than that by sub-radiant plasmon mode because the super-radiant mode has higher scattering and stronger plasmon field intensity relative to the sub-radiant mode.

  12. Thermo-catalytic pyrolysis of waste polyethylene bottles in a packed bed reactor with different bed materials and catalysts

    International Nuclear Information System (INIS)

    Highlights: • Thermo-catalytic pyrolysis of waste polyethylene bottles was investigated. • The highest yield of liquid (82%) was obtained over a cement powder bed. • Acidic catalysts narrowed the carbon chain length of the paraffins to C10–C28. • Combination of cement bed with HBeta catalyst gave the highest yield of liquid. • Significant yield of aromatics was obtained mainly naphthalene and D-limonene. - Abstract: Plastic waste is an increasing economic and environmental problem as such there is a great need to process this waste and reduce its environmental impact. In this work, the pyrolysis of high density polyethylene (HDPE) waste products was investigated using both thermal and catalytic cracking techniques. The experimental work was carried out using packed bed reactor operating under an inert atmosphere at 450 °C. Different reactor bed materials, including sand, cement and white clay were used to enhance the thermal cracking of HDPE. In addition, the catalytic effect of sodium hydroxide, HUSY and HBeta zeolite catalysts on the degradation of HDPE waste was also investigated. The reactor beds were found to significantly alter the yield as well as the product composition. Products such as paraffins (⩽C44), olefins (⩽C22), aromatics (⩽C14) and alcohols (C16 and C17) were obtained at varying rates. The highest yield of liquid (82%) was obtained over a cement powder bed with a paraffin yield of 58%. The yield of paraffins and olefins followed separate paths, for paraffins it was found to increase in the order or Cement > White clay > Silica Sand, whereas for the olefins it was in the reverse order Silica Sand > White clay > Cement. The results obtained in this work exhibited a higher P/O ratio than expected, where the amount of generated paraffins was greater than 60% in most cases. Less olefin was generated as a consequence. This indicates that the product generated is more suited to be used as a fuel rather than as a chemical feedstock. The

  13. Effect of Temperature Gradient Direction in the Catalyst Nanoparticle on CNTs Growth Mode

    Directory of Open Access Journals (Sweden)

    Liu Shang-Bin

    2010-01-01

    Full Text Available Abstract To improve the understanding on CNT growth modes, the various processes, including thermal CVD, MP-CVD and ECR-CVD, have been used to deposit CNTs on nanoporous SBA-15 and Si wafer substrates with C2H2 and H2 as reaction gases. The experiments to vary process parameter of ΔT, defined as the vector quantities of temperature at catalyst top minus it at catalyst bottom, were carried out to demonstrate its effect on the CNT growth mode. The TEM and TGA analyses were used to characterize their growth modes and carbon yields of the processes. The results show that ΔT can be used to monitor the temperature gradient direction across the catalyst nanoparticle during the growth stage of CNTs. The results also indicate that the tip-growth CNTs, base-growth CNTs and onion-like carbon are generally fabricated under conditions of ΔT > 0, <0 and ~0, respectively. Our proposed growth mechanisms can be successfully adopted to explain why the base- and tip-growth CNTs are common in thermal CVD and plasma-enhanced CVD processes, respectively. Furthermore, our experiments have also successfully demonstrated the possibility to vary ΔT to obtain the desired growth mode of CNTs by thermal or plasma-enhanced CVD systems for different applications.

  14. Active coupling control in densely packed subwavelength waveguides via dark mode

    CERN Document Server

    Suchowski, Haim; Hatakeyama, Taiki; Wu, Chihhui; Feng, Liang; OBrien, Kevin; Wang, Yuan; Zhang, Xiang

    2015-01-01

    The ever growing need for energy-efficient and fast communications is driving the development of highly integrated photonic circuits where controlling light at the nanoscale becomes the most critical aspect of information transfer . Directional couplers, two interacting optical waveguides placed in close proximity, are important building blocks in these integrated photonics circuits and have been employed as optical modulators and switches for high speed communication, data processing and integrated quantum operations. However, active control over the coupling between closely packed waveguides is highly desirable and yet remains a critical barrier towards ultra small footprint devices. A general approach to achieve active control in waveguide systems is to exploit optical nonlinearities enabled by a strong control pulse. However these devices suffer from the nonlinear absorption induced by the intense control pulse as the signal and its control propagate in the same waveguide. Here we experimentally demonstra...

  15. The unusual thermochromic NIR luminescence of Cu(I) clusters: tuned by Cu-Cu interactions and packing modes.

    Science.gov (United States)

    Shan, Xiao-Chen; Jiang, Fei-Long; Yuan, Da-Qiang; Wu, Ming-Yan; Zhang, Shu-Quan; Hong, Mao-Chun

    2012-08-21

    Two hexanuclear Cu(I) clusters [Cu(I)(3)(4-ptt)(3)](2)·3DMF·3H(2)O (1) and [Cu(I)(4-ptt)](6)·8DMF·7H(2)O (2) (4-Hptt = 5-(pyridin-4-yl)-1H-1,2,4-triazole-3-thiol, DMF = N,N-dimethylformamide), were synthesized and characterized. Compounds 1 and 2 with similar coordination environments are isomers, but their detailed structures are different due to the reaction temperature tuning effect. Both 1 and 2 extend from monomers to 3D supramolecules with the help of hydrogen bonding between the triazole and pyridine from the 4-ptt ligands. The Cu(6)S(6) units of 1 pack in a polydirectional array, while the Cu(6)S(6) units in 2 extend in one direction and link the planes of adjacent ligands to enhance the delocalization of π electrons. Their varied Cu-Cu interactions and individual packing modes cause differences in luminescent and thermostable behaviors. Compound 1 exhibits an unusually long wavelength at about 900 nm and a higher thermal stability; while the emission of 2 splits into two bands (high-energy and low-energy emission bands) as the temperature decreases. Therefore, the emissions of 1 originate from a (3)CC transition, and those of 2 are from a mixture of (3)CC and MLCT. PMID:22740116

  16. A continuous process for biodiesel production in a fixed bed reactor packed with cation-exchange resin as heterogeneous catalyst.

    Science.gov (United States)

    Feng, Yaohui; Zhang, Aiqing; Li, Jianxin; He, Benqiao

    2011-02-01

    Continuous esterification of free fatty acids (FFA) from acidified oil with methanol was carried out with NKC-9 cation-exchange resin in a fixed bed reactor with an internal diameter of 25 mm and a height of 450 mm to produce biodiesel. The results showed that the FFA conversion increased with increases in methanol/oil mass ratio, reaction temperature and catalyst bed height, whereas decreased with increases in initial water content in feedstock and feed flow rate. The FFA conversion kept over 98.0% during 500 h of continuous esterification processes under 2.8:1 methanol to oleic acid mass ratio, 44.0 cm catalyst bed height, 0.62 ml/min feed flow rate and 65°C reaction temperature, showing a much high conversion and operational stability. Furthermore, the loss of sulfonic acid groups from NKC-9 resin into the production was not found during continuous esterification. In sum, NKC-9 resin shows the potential commercial applications to esterification of FFA. PMID:21078550

  17. Optimal Switching Table-Based Sliding Mode Control of an Energy Recovery Li-Ion Power Accumulator Battery Pack Testing System

    Directory of Open Access Journals (Sweden)

    Kil To Chong

    2013-10-01

    Full Text Available The main objective of the present work is to apply a sliding mode controller (SMC to medium voltage and high power output energy recovery Li-ion power accumulator battery pack testing systems (ERLPABTSs, which are composed of a three-level neutral-point-clamped (NPC three-phase voltage source inverter (VSI and a two-level buck-boost converter without an isolating transformer. An inner current decoupled control scheme for the aforementioned system is proposed and two sliding mode planes for active and reactive current control are designed based on the control scheme. An optimized switching table for current convergence is used according to the error sign of the equivalent input voltage and feedback voltage. The proposed ERLPABTS could be used to integrate discharging energy into the power grid when performing high accuracy current testing. The active and reactive power references for the grid-connected inverter are determined based on the discharging energy from the DC-DC converter. Simulations and experiments on a laboratory hardware platform using a 175 kW insulated gate bipolar transistor (IGBT-based ERLPABTS have been implemented and verified, and the performance is found satisfactory and superior to conventional ERLPABPTS.

  18. New improved hydrophobic Pt-catalyst for hydrogen isotope separation

    International Nuclear Information System (INIS)

    This paper presents the studies on preparation methods and applications of the hydrophobic catalysts in deuterium and tritium separation. The objectives of the paper are: (1) to provide a database for selection of the most appropriate catalyst and catalytic packing for above mentioned processes; (2) to evaluate the potentiality of hydrophobic Pt-catalysts in the deuterium and tritium separation; (3) to assess and to find a new procedure for preparation of a new improved hydrophobic catalyst. Unlike the conventional hydrophilic catalysts, the hydrophobic catalysts maintain a high catalytic activity and stability even under the direct contact to liquid water or in the presence of saturated humidity. A large diversity of catalyst types (over 100 catalysts) was prepared and tested for hydrogen isotope separation. The impregnation modes, the type of precursor of active metal, conditions of reduction and waterproofing methods are in detail analysed. As result of this assessment, platinum appears to be the most active catalytic metal and TEFLON is the most hydrophobic agent. A method for preparation of new improved hydrophobic Pt-catalysed has been proposed. The main steps and experimental conditions are largely discussed. The advantages of the hydrophobic catalysts are shown in comparison to hydrophilic catalysts. Some suggestions concerning the deuterium and tritium enrichment by means of hydrophobic catalysts are also discussed.The extension of hydrophobic Pt-catalysts' applications in environmental field is proposed. (author)

  19. Supported Tetrahedral Oxo-Sn Catalyst: Single Site, Two Modes of Catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Beletskiy, Evgeny V.; Hou, Xianliang; Shen, Zhongliang; Gallagher, James R.; Miller, Jeffrey T.; Wu, Yuyang; Li, Tiehu; Kung, Mayfair C.; Kung, Harold H.

    2016-04-06

    Mild calcination in ozone of a (POSS)-Sn- (POSS) complex grafted on silica generated a heterogenized catalyst that mostly retained the tetrahedral coordination of its homogeneous precursor, as evidenced by spectroscopic characterizations using EXAFS, NMR, UV-vis, and DRIFT. The Sn centers are accessible and uniform and can be quantified by stoichiometric pyridine poisoning. This Sn-catalyst is active in hydride transfer reactions as a typical solid Lewis acid. However, the Sn centers can also create Brønsted acidity with alcohol by binding the alcohol strongly as alkoxide and transferring the hydroxyl H to the neighboring Sn-O-Si bond. The resulting acidic silanol is active in epoxide ring opening and acetalization reactions.

  20. Supported Tetrahedral Oxo-Sn Catalyst: Single Site, Two Modes of Catalysis.

    Science.gov (United States)

    Beletskiy, Evgeny V; Hou, Xianliang; Shen, Zhongliang; Gallagher, James R; Miller, Jeffrey T; Wu, Yuyang; Li, Tiehu; Kung, Mayfair C; Kung, Harold H

    2016-04-01

    Mild calcination in ozone of a (POSS)-Sn-(POSS) complex grafted on silica generated a heterogenized catalyst that mostly retained the tetrahedral coordination of its homogeneous precursor, as evidenced by spectroscopic characterizations using EXAFS, NMR, UV-vis, and DRIFT. The Sn centers are accessible and uniform and can be quantified by stoichiometric pyridine poisoning. This Sn-catalyst is active in hydride transfer reactions as a typical solid Lewis acid. However, the Sn centers can also create Brønsted acidity with alcohol by binding the alcohol strongly as alkoxide and transferring the hydroxyl H to the neighboring Sn-O-Si bond. The resulting acidic silanol is active in epoxide ring opening and acetalization reactions. PMID:26986621

  1. Power Packing

    Centers for Disease Control (CDC) Podcasts

    2011-08-16

    In this podcast for kids, the Kidtastics talk about how to pack a lunch safely, to help keep you from getting sick.  Created: 8/16/2011 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/16/2011.

  2. Packing Smart

    Centers for Disease Control (CDC) Podcasts

    2011-08-22

    In this podcast for kids, the Kidtastics talk about packing a lunch that's not boring and is full of the power and energy kids need to make it through the day.  Created: 8/22/2011 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 8/22/2011.

  3. Supramolecular Packing Controls H₂ Photocatalysis in Chromophore Amphiphile Hydrogels.

    Science.gov (United States)

    Weingarten, Adam S; Kazantsev, Roman V; Palmer, Liam C; Fairfield, Daniel J; Koltonow, Andrew R; Stupp, Samuel I

    2015-12-01

    Light harvesting supramolecular assemblies are potentially useful structures as components of solar-to-fuel conversion materials. The development of these functional constructs requires an understanding of optimal packing modes for chromophores. We investigated here assembly in water and the photocatalytic function of perylene monoimide chromophore amphiphiles with different alkyl linker lengths separating their hydrophobic core and the hydrophilic carboxylate headgroup. We found that these chromophore amphiphiles (CAs) self-assemble into charged nanostructures of increasing aspect ratio as the linker length is increased. The addition of salt to screen the charged nanostructures induced the formation of hydrogels and led to internal crystallization within some of the nanostructures. For linker lengths up to seven methylenes, the CAs were found to pack into 2D crystalline unit cells within ribbon-shaped nanostructures, whereas the nine methylene CAs assembled into long nanofibers without crystalline molecular packing. At the same time, the different molecular packing arrangements after charge screening led to different absorbance spectra, despite the identical electronic properties of all PMI amphiphiles. While the crystalline CAs formed electronically coupled H-aggregates, only CAs with intermediate linker lengths showed evidence of high intermolecular orbital overlap. Photocatalytic hydrogen production using a nickel-based catalyst was observed in all hydrogels, with the highest turnovers observed for CA gels having intermediate linker lengths. We conclude that the improved photocatalytic performance of the hydrogels formed by supramolecular assemblies of the intermediate linker CA molecules likely arises from improved exciton splitting efficiencies due to their higher orbital overlap. PMID:26593389

  4. Agro-industrial waste: a low cost adsorbent for effective removal of 4-chloro-2-methylphenoxyacetic acid herbicide in batch and packed bed modes.

    Science.gov (United States)

    Deokar, Sunil K; Mandavgane, Sachin A; Kulkarni, Bhaskar D

    2016-08-01

    The present work describes the aqueous phase removal of 4-chloro-2-methylphenoxyacetic acid herbicide by rice husk ash (RHA) using batch and packed bed adsorption techniques. The effects of dosage, initial concentration, time, pH, temperature, and particle size of adsorbent in batch compared with effects of influent concentration, flow rate, and bed height in packed bed were studied. The particle size effect reveals that the removal is dependent on chemical composition (silica and carbon content) together with BET surface area of RHA. The aptness of Langmuir isotherm to batch data indicates the favorable adsorption whereas that of Temkin isotherm informs the heterogeneous nature of RHA. The kinetics of adsorption follows the pseudo-second order and Elovich models while thermodynamics of process indicates the exothermic adsorption. Among the models applied in packed bed study, the deactivation kinetic, Yoon-Nelson and bed depth service time (BDST) models are suitable to explain the packed bed adsorption. The adsorption capacity of RHA in packed bed study is found greater than that in batch. The adsorption capacity of RHA determined by the BDST model is 3019 mg/L for 90 % saturation of bed. The adsorption capacity of RHA based on weight is ∼2.3 times and that based on surface area is ∼55.55 times greater than that of granular activated carbon. PMID:27151241

  5. Wolf Pack Algorithm for Unconstrained Global Optimization

    OpenAIRE

    Hu-Sheng Wu; Feng-Ming Zhang

    2014-01-01

    The wolf pack unites and cooperates closely to hunt for the prey in the Tibetan Plateau, which shows wonderful skills and amazing strategies. Inspired by their prey hunting behaviors and distribution mode, we abstracted three intelligent behaviors, scouting, calling, and besieging, and two intelligent rules, winner-take-all generation rule of lead wolf and stronger-survive renewing rule of wolf pack. Then we proposed a new heuristic swarm intelligent method, named wolf pack algorithm (WPA). E...

  6. Effects of hydrophobic carrier and packing on the mass transfer capabilities in hydrogen-water liquid phase catalytic exchange bed

    International Nuclear Information System (INIS)

    Hydrogen-water liquid phase catalytic exchange bed was packed with 'sandwich' layers of the catalyst and the packing, and the effects of catalyst carrier, inert packing and their filled ratio on the overall mass transfer coefficient (Kya) were investigated experimentally. The results show that C-PTFE is suitable for hydrophobic catalyst. Kya of the bed with catalyst-stainless steel mini-spiral packing is better than that with stainless steel θ-packing, and the active Al2O3 is not suitable for the exchange bed. Moreover, if the stainless steel mini-spiral packing is etched in aqua regia, the operating flexibility and overall mass transfer capability of exchange bed are improved notably. The preferable packing ratio (catalyst/packing) is 1:4. (authors)

  7. The Performance of Structured Packings in Trickle-Bed Reactors

    NARCIS (Netherlands)

    Frank, M.J.W.; Kuipers, J.A.M.; Versteeg, G.F.; Swaaij, W.P.M. van

    1999-01-01

    An experimental study was carried out to investigate whether the use of structured packings might improve the mass transfer characteristics and the catalyst effectiveness of a trickle-bed reactor. Therefore, the performances of a structured packing, consisting of KATAPAK elements, and a dumped packi

  8. The performance of structured packings in trickle-bed reactors.

    NARCIS (Netherlands)

    Frank, M.J.W.; Kuipers, J.A.M.; Versteeg, G.F.; Swaaij, van W.P.M.

    1999-01-01

    An experimental study was carried out to investigate whether the use of structured packings might improve the mass transfer characteristics and the catalyst effectiveness of a trickle-bed reactor. Therefore, the performances of a structured packing, consisting of KATAPAK elements, and a dumped packi

  9. Hydrodynamics of multi-phase packed bed micro-reactors

    NARCIS (Netherlands)

    Márquez Luzardo, N.M.

    2010-01-01

    Why to use packed bed micro-reactors for catalyst testing? Miniaturized packed bed reactors have a large surface-to-volume ratio at the reactor and particle level that favors the heat- and mass-transfer processes at all scales (intra-particle, inter-phase and inter-particle or reactor level). If the

  10. Molecular structure of 2-chloro-2'-deoxyadenosine an agent used in therapy for multiple sclerosis and its unusual crystal packing mode

    Science.gov (United States)

    Koellner, Gertraud; Kazimierczuk, Zygmunt; Steiner, Thomas; Kaminski, Jaroslaw

    1998-03-01

    The X-ray crystal structure of 2-chloro-2'-deoxyadenosine was determined at low temperature [space group orthorhombic P2 12 12, a = 7.493(6), b = 16.894(4), c = 9.065(4) → A, V = 1147.6(11) →A 3, 4097 unique reflections, R = 0.050]. The ribose unit is in 23T conformation, and the orientation around the Cl'-N glycosylic bond is syn with respect to the base. The 2-chloro-substitution leads to small but significant changes of the covalent geometry of the base at the substitution site, particularly to widening of the endocyclic angle at C2. The crystal packing is unusual foradenine nucleosides: molecules form stacks with parallel bases which are aligned by chains of short chlorine-chlorine contacts.

  11. Tunable random packings

    International Nuclear Information System (INIS)

    We present an experimental protocol that allows one to tune the packing fraction η of a random pile of ferromagnetic spheres from a value close to the lower limit of random loose packing ηRLP≅0.56 to the upper limit of random close packing ηRCP≅0.64. This broad range of packing fraction values is obtained under normal gravity in air, by adjusting a magnetic cohesion between the grains during the formation of the pile. Attractive and repulsive magnetic interactions are found to affect stongly the internal structure and the stability of sphere packing. After the formation of the pile, the induced cohesion is decreased continuously along a linear decreasing ramp. The controlled collapse of the pile is found to generate various and reproducible values of the random packing fraction η

  12. Toric symplectic ball packing

    OpenAIRE

    Pelayo, Alvaro

    2007-01-01

    We define and solve the toric version of the symplectic ball packing problem, in the sense of listing all 2n-dimensional symplectic-toric manifolds which admit a perfect packing by balls embedded in a symplectic and torus equivariant fashion. In order to do this we first describe a problem in geometric-combinatorics which is equivalent to the toric symplectic ball packing problem. Then we solve this problem using arguments from Convex Geometry and Delzant theory. Applications to symplectic bl...

  13. Flat Pack Toy Design

    Science.gov (United States)

    Hutcheson, Brian

    2007-01-01

    In this article, the author introduces the concept of flat pack toys. Flat pack toys are designed using a template on a single sheet of letter-sized card stock paper. Before being cut out and built into a three-dimensional toy, they are scanned into the computer and uploaded to a website. With the template accessible from the website, anyone with…

  14. TLC Pack Unpacked

    Science.gov (United States)

    Oberhofer, Margret; Colpaert, Jozef

    2015-01-01

    TLC Pack stands for Teaching Languages to Caregivers and is a course designed to support migrants working or hoping to work in the caregiving sector. The TLC Pack resources range from A2 to B2 level of the Common European Framework of Reference for Languages (CEFR), and will be made available online in the six project languages: Dutch, English,…

  15. Quasiperiodic packing densities

    International Nuclear Information System (INIS)

    The problem of the packing density on quasiperiodic lattices is discussed in a systematic way using projection techniques. For compact domains a direct construction is presented using a Voronoi construction on a quasilattice in perpendicular space defined by the forbidden volume of the packed objects. A generalized inflation law, valid for arbitrary shapes of the acceptance domain using the properties of linear mappings of the hyperlattice on itself which commute with the symmetry group, is used to show that the packing densities and the whole structure of the projected quasilattice are periodic under scale transformations. We find the optimal compact acceptance domains and packing densities for several icosahedral problems. For the packing of spheres on the primitive lattice, an icosahedron and the truncated triacontahedron give equal densities but different quasilattices. For the packing of icosahedra one finds only the second lattice and a very high density. For the fcc and bcc lattices the maximum density acceptance domain is a triacontahedron and the densities are considerably lower. The results of Henley for including correlations to increase the density are reformulated in terms of a graph problem in perpendicular space. Including only the graphs equivalent to his, we find the same packing density for the two primitive and for the fcc lattice. It is shown that a generalization leads to an interesting and very complex problem in graph theory which we are unable to solve

  16. Manufacture of Catalyst Systems for Ammonia Conversion

    Institute of Scientific and Technical Information of China (English)

    GAKH S.V.; SAVENKOV D.A.

    2012-01-01

    Platinum catalyst gauzes have been in use since the moment of development of the process of catalyst oxidation of ammonia for production of nitric acid or hydrocyanic acid.Catalyst gauzes are usually made of platinum or its alloys with rhodium and palladium.These precious metals have remarkable properties that make them ideal catalysts for acceleration of the ammonia/oxygen reaction.In 2008,OJSC "SIC ‘Supermetal’" and Umicore AG&Co.KG launched a production line for Pt-alloy-based catalyst systems to be used for ammonia oxidation in the production of weak nitric acid.Catalyst systems consist of a pack of catalyst gauzes and a pack of catchment gauzes,which are made using flat-bed knitting machines and wire-cloth looms.Today,up-to-date catalyst systems MKSpreciseTM are being manufactured,the basic advantages of which are an individual structure of gauzes and composition of the material,which allows to define precisely the position of each gauze in the catalyst pack,a high activity of the catalyst pack,direct catching of platinum and rhodium in the catalyst system,and a reasonable combination of single- and multilayer types of gauzes.This makes it possible to vary the configuration of the catalyst and select an optimum composition of the system to ensure the maximum efficiency of the ammonia oxidation process.We also produce the catchment systems that allow to find the best decision from the economic point view for each individual case.

  17. Optimized packings with applications

    CERN Document Server

    Pintér, János

    2015-01-01

    This volume presents a selection of case studies that address a substantial range of optimized object packings (OOP) and their applications. The contributing authors are well-recognized researchers and practitioners. The mathematical modelling and numerical solution aspects of each application case study are presented in sufficient detail. A broad range of OOP problems are discussed: these include various specific and non-standard container loading and object packing problems, as well as the stowing of hazardous and other materials on container ships, data centre resource management, automotive engineering design, space station logistic support, cutting and packing problems with placement constraints, the optimal design of LED street lighting, robust sensor deployment strategies, spatial scheduling problems, and graph coloring models and metaheuristics for packing applications. Novel points of view related to model development and to computational nonlinear, global, mixed integer optimization and heuristic st...

  18. Separation of deuterium by H2/H2O reaction with hydrophobic platinum catalyst

    International Nuclear Information System (INIS)

    The separation performance of a trickle bed exchange column packed with a hydrophobic or waterproof catalyst is related to operating conditions such as hydrogen surface velocity, water flow rate, and temperature. The optimum carrier type and catalyst platinum content were determined. The continuous injection of roughly 103 ppm O2 regenerates the catalyst effectively. The ratio of hydrophobic catalyst to hydrophilic packing is an important factor in increasing the exchange rate in deuterium extraction

  19. Influence of packing material and method on the efficiency of liquid phase water-hydrogen isotope exchange

    International Nuclear Information System (INIS)

    The influence of packing material in the countercurrent catalytic column on the efficiency of liquid phase water-hydrogen isotope exchange is studied. Stainless steel triangle spring packing demonstrates best performance among the tested three hydrophilic packing materials. Pretreatment of the stainless steel packing lowers the height of a mass transfer unit (HTU) by about 50%. The effectiveness of a catalytic column for water-hydrogen isotope exchange is proved to be higher when the column is packed in layers with hydrophilic packing and hydrophobic catalyst in the volume ratio 1:4

  20. Battery Pack Thermal Design

    Energy Technology Data Exchange (ETDEWEB)

    Pesaran, Ahmad

    2016-06-14

    This presentation describes the thermal design of battery packs at the National Renewable Energy Laboratory. A battery thermal management system essential for xEVs for both normal operation during daily driving (achieving life and performance) and off-normal operation during abuse conditions (achieving safety). The battery thermal management system needs to be optimized with the right tools for the lowest cost. Experimental tools such as NREL's isothermal battery calorimeter, thermal imaging, and heat transfer setups are needed. Thermal models and computer-aided engineering tools are useful for robust designs. During abuse conditions, designs should prevent cell-to-cell propagation in a module/pack (i.e., keep the fire small and manageable). NREL's battery ISC device can be used for evaluating the robustness of a module/pack to cell-to-cell propagation.

  1. DIY Fraction Pack.

    Science.gov (United States)

    Graham, Alan; Graham, Louise

    2003-01-01

    Describes a very successful attempt to teach fractions to year 5 pupils based on pupils making their own fraction pack. Children decided for themselves how to make the fractional slices used in the activity using colored cardboard sheets and templates of a paper circle consisting of 24 equal slices. (Author/NB)

  2. Optimal Packed String Matching

    DEFF Research Database (Denmark)

    Ben-Kiki, Oren; Bille, Philip; Breslauer, Dany;

    2011-01-01

    In the packed string matching problem, each machine word accommodates – characters, thus an n-character text occupies n/– memory words. We extend the Crochemore-Perrin constantspace O(n)-time string matching algorithm to run in optimal O(n/–) time and even in real-time, achieving a factor – speedup...

  3. Effect of packing method on the randomness of disc packings

    Science.gov (United States)

    Zhang, Z. P.; Yu, A. B.; Oakeshott, R. B. S.

    1996-06-01

    The randomness of disc packings, generated by random sequential adsorption (RSA), random packing under gravity (RPG) and Mason packing (MP) which gives a packing density close to that of the RSA packing, has been analysed, based on the Delaunay tessellation, and is evaluated at two levels, i.e. the randomness at individual subunit level which relates to the construction of a triangle from a given edge length distribution and the randomness at network level which relates to the connection between triangles from a given triangle frequency distribution. The Delaunay tessellation itself is also analysed and its almost perfect randomness at the two levels is demonstrated, which verifies the proposed approach and provides a random reference system for the present analysis. It is found that (i) the construction of a triangle subunit is not random for the RSA, MP and RPG packings, with the degree of randomness decreasing from the RSA to MP and then to RPG packing; (ii) the connection of triangular subunits in the network is almost perfectly random for the RSA packing, acceptable for the MP packing and not good for the RPG packing. Packing method is an important factor governing the randomness of disc packings.

  4. The Six Pack Model

    DEFF Research Database (Denmark)

    Andersen, Henrik; Ritter, Thomas

    Ever seen a growth strategies fail because it was not connect ed to the firm’s customer base? Or a customer relationship strategy falters just because it was the wrong thing to do with that given customer? This article presents the six pack model, a tool that makes growth profitable and predictab....... Not all customers can and should grow – thus a firm needs to classify its customers in order to implement the right customer strategy.......Ever seen a growth strategies fail because it was not connect ed to the firm’s customer base? Or a customer relationship strategy falters just because it was the wrong thing to do with that given customer? This article presents the six pack model, a tool that makes growth profitable and predictable...

  5. Argo packing friction research update

    International Nuclear Information System (INIS)

    This paper focuses on the issue of valve packing friction and its affect on the operability of motor- and air-operated valves (MOVs and AOVs). At this time, most nuclear power plants are required to perform postmaintenance testing following a packing adjustment or replacement. In many cases, the friction generated by the packing does not impact the operability window of a valve. However, to date there has not been a concerted effort to substantiate this claim. To quantify the effects of packing friction, it has become necessary to develop a formula to predict the friction effects accurately. This formula provides a much more accurate method of predicting packing friction than previously used factors based strictly on stem diameter. Over the past 5 years, Argo Packing Company has been developing and testing improved graphite packing systems at research facilities, such as AECL Chalk River and Wyle Laboratories. Much of this testing has centered around reducing and predicting friction that is related to packing. In addition, diagnostic testing for Generic Letter 89-10 MOVs and AOVs has created a significant data base. In July 1992 Argo asked several utilities to provide running load data that could be used to quantify packing friction repeatability and predictability. This technical paper provides the basis to predict packing friction, which will improve calculations for thrust requirements for Generic Leter 89-10 and future AOV programs. In addition, having an accurate packing friction formula will improve packing performance when low running loads are identified that would indicate insufficient sealing force

  6. Separable subgroups have bounded packing

    CERN Document Server

    Yang, Wen-yuan

    2010-01-01

    In this note, we prove that separable subgroups have bounded packing in ambient groups. The notion bounded packing was introduced by Hruska-Wise \\cite{HrWi} and in particular, our result confirms a conjecture in \\cite{HrWi} which states each subgroup of a virtually polycyclic group has the bounded packing property.

  7. Optimal packing of a rotating packed bed for H(2)S removal.

    Science.gov (United States)

    Guo, Kai; Wen, Jiawu; Zhao, Ying; Wang, Yu; Zhang, Zhenzhen; Li, Zongxiang; Qian, Zhi

    2014-06-17

    The existence of H2S in a system could lead to catalyst deactivation, pipeline corrosion, and environmental pollution. A rotating packed bed (RPB), a novel reactor with high mass transfer efficiency and small dimension, is employed in this study to remove H2S. For RPB, the most significant section for mass transfer is the end-effect zone of packing. A mathematical model for liquid flow in the packing is established to quantify the length of the end-effect zone. A simple and effective visual experimental method is then proposed to investigate the end-effect zone in the RPB. A gas-liquid mass transfer experiment is finally employed to confirm the validity of the proposed mathematical model. With the aid of this model, the length of packing of a RPB used for pilot-scale H2S removal is optimized. The optimized RPB removes 99.8% of H2S (15 vol % to 0.03 vol %) from the system. The proposed model can help optimize the design of a RPB reactor. PMID:24798198

  8. Hydrodynamics of multi-phase packed bed micro-reactors

    OpenAIRE

    Márquez Luzardo, N.M.

    2010-01-01

    Why to use packed bed micro-reactors for catalyst testing? Miniaturized packed bed reactors have a large surface-to-volume ratio at the reactor and particle level that favors the heat- and mass-transfer processes at all scales (intra-particle, inter-phase and inter-particle or reactor level). If the mass-transfer processes are fast in respect to the reaction-rate, then the reaction-rate is under kinetic control over the entire range of conversion and it is possible to measure intrinsic kineti...

  9. PlanetPack: Radial-velocity time-series analysis tool

    Science.gov (United States)

    Baluev, Roman V.

    2013-11-01

    PlanetPack facilitates and standardizes the advanced analysis of radial velocity (RV) data for the goal of exoplanets detection, characterization, and basic dynamical N-body simulations. PlanetPack is a command-line interpreter that can run either in an interactive mode or in a batch mode of automatic script interpretation.

  10. Method of making hydrophobic industrial catalyst for water-hydrogen isotope exchange

    International Nuclear Information System (INIS)

    The authors have performed the research centering around the development of platinum catalyst carried by styrene divinylbenzene copolymer as the hydrophobic catalyst for water-hydrogen isotope exchange for the purpose of heavy water concentration and especially tritium removal. In this paper, the method of industrial production of this catalyst, the results of catalytic performance test by trickle bed and the problems are reported. It was found that only chloroplatinic acid was suitable as the practical raw material of the catalyst. The ethanol solution of chloroplatinic acid is practically most desirable. Generally, the catalytic activity increases by the aging of SDB in pure hydrogen flow. For the impregnation of chloroplatinic acid into SDB, the column method is suitable. The impregnated carriers are dried with an air drier. Then the carriers carrying chloroplatinic acid are reduced in a reaction tube with highly pure hydrogen. The catalytic performance test was performed in a packed tower, and the effects of the shape of catalysts, flow mode, oxygen, scale-up, pressure and impurities are reported. (Kako, I.)

  11. Nuclear energy pack

    International Nuclear Information System (INIS)

    The pack contains teaching material to supply factual information about nuclear energy for those teaching physics or chemistry or general science for GCE examinations. It is intended for use either in class teaching or in some forms of resource-based learning systems. The material comprises: illustrated booklets and accompanying filmstrips on (1) energy from atoms, (2) ionising radiation and its detection, (3) nuclear reactors, and (4) the uses of radioisotopes; wallcharts on (1) nuclear fuel cycle, (2) radioactivity at work, and (3) nuclear reactors for producing electricity; glossary of atomic terms; and teachers' guide. (U.K.)

  12. ExactPack Documentation

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, Jr., Robert [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Israel, Daniel M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Doebling, Scott William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Woods, Charles Nathan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kaul, Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Walter, Jr., John William [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rogers, Michael Lloyd [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-09

    For code verification, one compares the code output against known exact solutions. There are many standard test problems used in this capacity, such as the Noh and Sedov problems. ExactPack is a utility that integrates many of these exact solution codes into a common API (application program interface), and can be used as a stand-alone code or as a python package. ExactPack consists of python driver scripts that access a library of exact solutions written in Fortran or Python. The spatial profiles of the relevant physical quantities, such as the density, fluid velocity, sound speed, or internal energy, are returned at a time specified by the user. The solution profiles can be viewed and examined by a command line interface or a graphical user interface, and a number of analysis tools and unit tests are also provided. We have documented the physics of each problem in the solution library, and provided complete documentation on how to extend the library to include additional exact solutions. ExactPack’s code architecture makes it easy to extend the solution-code library to include additional exact solutions in a robust, reliable, and maintainable manner.

  13. Cell packing structures

    KAUST Repository

    Pottmann, Helmut

    2015-03-03

    This paper is an overview of architectural structures which are either composed of polyhedral cells or closely related to them. We introduce the concept of a support structure of such a polyhedral cell packing. It is formed by planar quads and obtained by connecting corresponding vertices in two combinatorially equivalent meshes whose corresponding edges are coplanar and thus determine planar quads. Since corresponding triangle meshes only yield trivial structures, we focus on support structures associated with quad meshes or hex-dominant meshes. For the quadrilateral case, we provide a short survey of recent research which reveals beautiful relations to discrete differential geometry. Those are essential for successfully initializing numerical optimization schemes for the computation of quad-based support structures. Hex-dominant structures may be designed via Voronoi tessellations, power diagrams, sphere packings and various extensions of these concepts. Apart from the obvious application as load-bearing structures, we illustrate here a new application to shading and indirect lighting. On a higher level, our work emphasizes the interplay between geometry, optimization, statics, and manufacturing, with the overall aim of combining form, function and fabrication into novel integrated design tools.

  14. Heuristics for Multidimensional Packing Problems

    DEFF Research Database (Denmark)

    Egeblad, Jens

    minimum height container required for the items. The main contributions of the thesis are three new heuristics for strip-packing and knapsack packing problems where items are both rectangular and irregular. In the two first papers we describe a heuristic for the multidimensional strip-packing problem that...... results of this heuristic are among the best published in the literature both for two- and three-dimensional strip-packing problems for irregular shapes. In the third paper, we introduce a heuristic for two- and three-dimensional rectangular knapsack packing problems. The two-dimensional heuristic uses...... promising. A heuristic for a three-dimensional knapsack packing problem involving furniture is presented in the fourth paper. The heuristic is based on a variety of techniques including tree-search, wall-building, and sequential placement. The solution process includes considerations regarding stability and...

  15. Dense packing on uniform lattices

    CERN Document Server

    Eloranta, Kari

    2009-01-01

    We study the Hard Core Model on the graphs ${\\rm {\\bf \\scriptstyle G}}$ obtained from Archimedean tilings i.e. configurations in $\\scriptstyle \\{0,1\\}^{{\\rm {\\bf G}}}$ with the nearest neighbor 1's forbidden. Our particular aim in choosing these graphs is to obtain insight to the geometry of the densest packings in a uniform discrete set-up. We establish density bounds, optimal configurations reaching them in all cases, and introduce a probabilistic cellular automaton that generates the legal configurations. Its rule involves a parameter which can be naturally characterized as packing pressure. It can have a critical value but from packing point of view just as interesting are the noncritical cases. These phenomena are related to the exponential size of the set of densest packings and more specifically whether these packings are maximally symmetric, simple laminated or essentially random packings.

  16. Homogeneous catalysts

    CERN Document Server

    Chadwick, John C; Freixa, Zoraida; van Leeuwen, Piet W N M

    2011-01-01

    This first book to illuminate this important aspect of chemical synthesis improves the lifetime of catalysts, thus reducing material and saving energy, costs and waste.The international panel of expert authors describes the studies that have been conducted concerning the way homogeneous catalysts decompose, and the differences between homogeneous and heterogeneous catalysts. The result is a ready reference for organic, catalytic, polymer and complex chemists, as well as those working in industry and with/on organometallics.

  17. Regular Totally Separable Sphere Packings

    OpenAIRE

    Reid, Samuel

    2015-01-01

    The topic of totally separable sphere packings is surveyed with a focus on regular constructions, uniform tilings, and contact number problems. An enumeration of all regular totally separable sphere packings in $\\mathbb{R}^2$, $\\mathbb{R}^3$, and $\\mathbb{R}^4$ which are based on convex uniform tessellations, honeycombs, and tetracombs, respectively, is presented, as well as a construction of a family of regular totally separable sphere packings in $\\mathbb{R}^d$ that is not based on a convex...

  18. Rhodium catalysts for isotopic exchange between hydrogen and water vapor

    International Nuclear Information System (INIS)

    Catalysts were prepared by depositing rhodium on porous polystyrene copolymer. The activity of the catalysts for the isotopic exchange reaction in the hydrogen-water vapor system was determined by the nearness of approach to isotopic equilibrium between the two reactants after passing through the column. A known quantity of catalyst was packed in a 1 cm diameter glass column to depth varying 2 to 5 cm. The degree of approach to isotopic equilibrium was as high as 60 to 100 %

  19. Random sequential packing of cubes

    CERN Document Server

    Sikiric, Mathieu Dutour

    2011-01-01

    In this volume very simplified models are introduced to understand the random sequential packing models mathematically. The 1-dimensional model is sometimes called the Parking Problem, which is known by the pioneering works by Flory (1939), Renyi (1958), Dvoretzky and Robbins (1962). To obtain a 1-dimensional packing density, distribution of the minimum of gaps, etc., the classical analysis has to be studied. The packing density of the general multi-dimensional random sequential packing of cubes (hypercubes) makes a well-known unsolved problem. The experimental analysis is usually applied to t

  20. Packing solutions for power plants

    International Nuclear Information System (INIS)

    Asbestos packings are being replaced in more and more countries with alternative products. This paper discusses modern packing solutions for valves and pumps in power plants. Die-moulded packing rings made of expanded graphite foil are described m detail, with recommendations for correct installation. Application examples for spring-loaded valves and cover lid seals are given. As an alternative for repair and service use, a braided expanded graphite packing reinforced with Inconel wire is described. Proposals for sealing various pump applications in power plants are also made. (Author)

  1. Random very loose packings.

    Science.gov (United States)

    Ciamarra, Massimo Pica; Coniglio, Antonio

    2008-09-19

    We measure the number Omega(phi) of mechanically stable states of volume fraction phi of a granular assembly under gravity. The granular entropy S(phi)=logOmega(phi) vanishes both at high density, at phi approximately equal to phi_rcp, and a low density, at phi approximately equal to phi_rvlp, where phi_rvlp is a new lower bound we call random very loose pack. phi_rlp is the volume fraction where the entropy is maximal. These findings allow for a clear explanation of compaction experiments and provide the first first-principle definition of the random loose volume fraction. In the context of the statistical mechanics approach to static granular materials, states with phi

  2. Polarizable protein packing

    KAUST Repository

    Ng, Albert H.

    2011-01-24

    To incorporate protein polarization effects within a protein combinatorial optimization framework, we decompose the polarizable force field AMOEBA into low order terms. Including terms up to the third-order provides a fair approximation to the full energy while maintaining tractability. We represent the polarizable packing problem for protein G as a hypergraph and solve for optimal rotamers with the FASTER combinatorial optimization algorithm. These approximate energy models can be improved to high accuracy [root mean square deviation (rmsd) < 1 kJ mol -1] via ridge regression. The resulting trained approximations are used to efficiently identify new, low-energy solutions. The approach is general and should allow combinatorial optimization of other many-body problems. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011 Copyright © 2011 Wiley Periodicals, Inc.

  3. Packing for food irradiation

    International Nuclear Information System (INIS)

    Joint FAO/IAEA/WHO Expert Committee approved the use of radiation treatment of foods. Nowadays food packaging are mostly made of plastics, natural or synthetic, therefore effect of irradiation on these materials is crucial for packing engineering for food irradiation technology. By selecting the right polymer materials for food packaging it can be ensured that the critical elements of material and product performance are not compromised. When packaging materials are in contact with food at the time of irradiation that regulatory approvals sometimes apply. The review of the R-and-D and technical papers regarding material selection, testing and approval is presented in the report. The most information come from the USA where this subject is well elaborated, the International Atomic Energy Agency (IAEA) reports are reviewed as well. The report can be useful for scientists and food irradiation plants operators. (author)

  4. Polarizable protein packing.

    Science.gov (United States)

    Ng, Albert H; Snow, Christopher D

    2011-05-01

    To incorporate protein polarization effects within a protein combinatorial optimization framework, we decompose the polarizable force field AMOEBA into low order terms. Including terms up to the third-order provides a fair approximation to the full energy while maintaining tractability. We represent the polarizable packing problem for protein G as a hypergraph and solve for optimal rotamers with the FASTER combinatorial optimization algorithm. These approximate energy models can be improved to high accuracy [root mean square deviation (rmsd) < 1 kJ mol(-1)] via ridge regression. The resulting trained approximations are used to efficiently identify new, low-energy solutions. The approach is general and should allow combinatorial optimization of other many-body problems. PMID:21264879

  5. A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed-bed microreactor

    OpenAIRE

    Andrew Bogdan; D. Tyler McQuade

    2009-01-01

    We demonstrate the preparation and characterization of a simplified packed-bed microreactor using an immobilized TEMPO catalyst shown to oxidize primary and secondary alcohols via the biphasic Anelli-Montanari protocol. Oxidations occurred in high yields with great stability over time. We observed that plugs of aqueous oxidant and organic alcohol entered the reactor as plugs but merged into an emulsion on the packed-bed. The emulsion coalesced into larger plugs upon exiting the reactor, leavi...

  6. Bimetallic Catalysts.

    Science.gov (United States)

    Sinfelt, John H.

    1985-01-01

    Chemical reaction rates can be controlled by varying composition of miniscule clusters of metal atoms. These bimetallic catalysts have had major impact on petroleum refining, where work has involved heterogeneous catalysis (reacting molecules in a phase separate from catalyst.) Experimentation involving hydrocarbon reactions, catalytic…

  7. Sugar exported: sugar packed in containers

    Directory of Open Access Journals (Sweden)

    José Alberto Yemal

    2010-04-01

    Full Text Available This paper presents a study in the port sector specialized in handling of bagged sugar. Sugar has always been exported in bags of 50 kg, placed directly in the holds of ships for general cargo. It appears that this form of transport has become obsolete now, the market for the direct form of transport of sugar packed in containers. Companies involved in this type of port handling need understand the reasons that are influencing this new mode of transportation as a way to fit and remain active and competitive in the industry.

  8. Random packing of digitized particles

    NARCIS (Netherlands)

    Korte, de A.C.J.; Brouwers, H.J.H.

    2012-01-01

    The random packing of regularly and irregularly shaped particles has been studied extensively. Within this paper, packing is studied from the perspective of digitized particles. These digitized particles are developed for and used in cellular automata systems, which are employed for the simple mathe

  9. Fast searching in packed strings

    DEFF Research Database (Denmark)

    Bille, Philip

    2011-01-01

    the time. However, most strings are stored in a computer in a packed representation with several characters in a single word, giving us the opportunity to read multiple characters simultaneously. In this paper we study the worst-case complexity of string matching on strings given in packed...

  10. Fast Searching in Packed Strings

    DEFF Research Database (Denmark)

    Bille, Philip

    2009-01-01

    . However, most strings are stored in a computer in a packed representation with several characters in a single word, giving us the opportunity to read multiple characters simultaneously. In this paper we study the worst-case complexity of string matching on strings given in packed representation. Let m...

  11. Online Mixed Packing and Covering

    CERN Document Server

    Bhaskar, Umang

    2012-01-01

    In many problems, the inputs arrive over time, and must be dealt with irrevocably when they arrive. Such problems are online problems. A common method of solving online problems is to first solve the corresponding linear program, and then round the fractional solution online to obtain an integral solution. We give algorithms for solving linear programs with mixed packing and covering constraints online. We first consider mixed packing and covering linear programs, where packing constraints are given offline and covering constraints are received online. The objective is to minimize the maximum multiplicative factor by which any packing constraint is violated, while satisfying the covering constraints. No prior sublinear competitive algorithms are known for this problem. We give the first such --- a polylogarithmic-competitive algorithm for solving mixed packing and covering linear programs online. We also show a nearly tight lower bound. Our techniques for the upper bound use an exponential penalty function in...

  12. Using atomic layer deposited tungsten to increase thermal conductivity of a packed bed

    Energy Technology Data Exchange (ETDEWEB)

    Van Norman, Staci A.; Falconer, John L.; Weimer, Alan W., E-mail: alan.weimer@colorado.edu [Department of Chemical and Biological Engineering, University of Colorado, UCB 596, Boulder, Colorado 80309-0596 (United States); Tringe, Joseph W.; Sain, John D. [Lawrence Livermore National Laboratory, 7000 East Ave, Livermore, California 94550 (United States); Yang, Ronggui [Department of Mechanical Engineering, University of Colorado, UCB 427, Boulder, Colorado 80309-0427 (United States)

    2015-04-13

    This study investigated the effective thermal conductivity (k{sub eff}) of packed-beds that contained porous particles with nanoscale tungsten (W) films of different thicknesses formed by atomic layer deposition (ALD). A continuous film on the particles is vital towards increasing k{sub eff} of the packed beds. For example, the k{sub eff} of an alumina packed bed was increased by three times after an ∼8-nm continuous W film with 20 cycles of W ALD, whereas k{sub eff} was decreased on a polymer packed bed with discontinuous, evenly dispersed W-islands due to nanoparticle scattering of phonons. For catalysts, understanding the thermal properties of these packed beds is essential for developing thermally conductive supports as alternatives to structured supports.

  13. Using atomic layer deposited tungsten to increase thermal conductivity of a packed bed

    International Nuclear Information System (INIS)

    This study investigated the effective thermal conductivity (keff) of packed-beds that contained porous particles with nanoscale tungsten (W) films of different thicknesses formed by atomic layer deposition (ALD). A continuous film on the particles is vital towards increasing keff of the packed beds. For example, the keff of an alumina packed bed was increased by three times after an ∼8-nm continuous W film with 20 cycles of W ALD, whereas keff was decreased on a polymer packed bed with discontinuous, evenly dispersed W-islands due to nanoparticle scattering of phonons. For catalysts, understanding the thermal properties of these packed beds is essential for developing thermally conductive supports as alternatives to structured supports

  14. On Packing Densities of Set Partitions

    OpenAIRE

    Goyt, Adam M.; Pudwell, Lara K.

    2013-01-01

    We study packing densities for set partitions, which is a generalization of packing words. We use results from the literature about packing densities for permutations and words to provide packing densities for set partitions. These results give us most of the packing densities for partitions of the set $\\{1,2,3\\}$. In the final section we determine the packing density of the set partition $\\{\\{1,3\\},\\{2\\}\\}$.

  15. Photo-oxidation catalysts

    Science.gov (United States)

    Pitts, J. Roland; Liu, Ping; Smith, R. Davis

    2009-07-14

    Photo-oxidation catalysts and methods for cleaning a metal-based catalyst are disclosed. An exemplary catalyst system implementing a photo-oxidation catalyst may comprise a metal-based catalyst, and a photo-oxidation catalyst for cleaning the metal-based catalyst in the presence of light. The exposure to light enables the photo-oxidation catalyst to substantially oxidize absorbed contaminants and reduce accumulation of the contaminants on the metal-based catalyst. Applications are also disclosed.

  16. The pursuit of perfect packing

    CERN Document Server

    Weaire, Denis

    2008-01-01

    Coauthored by one of the creators of the most efficient space packing solution, the Weaire-Phelan structure, The Pursuit of Perfect Packing, Second Edition explores a problem of importance in physics, mathematics, chemistry, biology, and engineering: the packing of structures. Maintaining its mathematical core, this edition continues and revises some of the stories from its predecessor while adding several new examples and applications. The book focuses on both scientific and everyday problems ranging from atoms to honeycombs. It describes packing models, such as the Kepler conjecture, Voronoï decomposition, and Delaunay decomposition, as well as actual structure models, such as the Kelvin cell and the Weaire-Phelan structure. The authors discuss numerous historical aspects and provide biographical details on influential contributors to the field, including emails from Thomas Hales and Ken Brakke. With examples from physics, crystallography, engineering, and biology, this accessible and whimsical bo...

  17. On the tree packing conjecture

    OpenAIRE

    Balogh, József; Palmer, Cory

    2012-01-01

    The Gy\\'arf\\'as tree packing conjecture states that any set of $n-1$ trees $T_{1},T_{2},..., T_{n-1}$ such that $T_i$ has $n-i+1$ vertices pack into $K_n$. We show that $t=1/10n^{1/4}$ trees $T_1,T_2,..., T_t$ such that $T_i$ has $n-i+1$ vertices pack into $K_{n+1}$ (for $n$ large enough). We also prove that any set of $t=1/10n^{1/4}$ trees $T_1,T_2,..., T_t$ such that no tree is a star and $T_i$ has $n-i+1$ vertices pack into $K_{n}$ (for $n$ large enough). Finally, we prove that $t=1/4n^{1/...

  18. Catalytic Pyrolysis of Oak via Pyroprobe and Bench Scale, Packed Bed Pyrolysis Reactors

    Science.gov (United States)

    The pyrolytic conversion of oak sawdust at 500°C in flowing He over eight proprietary catalysts is described and compared to the control bed material, quartz sand. The reactions were conducted and compared in two reactors, an analytical, ug-scale pyroprobe reactor and a bench, g-scale packed bed re...

  19. Hydrodynamic behaviour of a gas—solid counter-current packed column at trickle flow

    NARCIS (Netherlands)

    Roes, A.W.M.; Swaaij, van W.P.M.

    1979-01-01

    Trickle flow of a more or less fluidized catalyst through a packed column is a promising new gas—solid counter-current operation. The hydrodynamic, behaviour of such a column, filled with dumped PALL rings, has been investigated, while some results have been obtained with RASCHIG rings and cylindric

  20. Catalyst Architecture

    DEFF Research Database (Denmark)

    Kiib, Hans; Marling, Gitte; Hansen, Peter Mandal

    2014-01-01

    How can architecture promote the enriching experiences of the tolerant, the democratic, and the learning city - a city worth living in, worth supporting and worth investing in? Catalyst Architecture comprises architectural projects, which, by virtue of their location, context and their combination...... of programs, have a role in mediating positive social and/or cultural development. In this sense, we talk about architecture as a catalyst for: sustainable adaptation of the city’s infrastructure appropriate renovation of dilapidated urban districts strengthening of social cohesiveness in the city...

  1. Hard sphere packings within cylinders.

    Science.gov (United States)

    Fu, Lin; Steinhardt, William; Zhao, Hao; Socolar, Joshua E S; Charbonneau, Patrick

    2016-02-23

    Arrangements of identical hard spheres confined to a cylinder with hard walls have been used to model experimental systems, such as fullerenes in nanotubes and colloidal wire assembly. Finding the densest configurations, called close packings, of hard spheres of diameter σ in a cylinder of diameter D is a purely geometric problem that grows increasingly complex as D/σ increases, and little is thus known about the regime for D > 2.873σ. In this work, we extend the identification of close packings up to D = 4.00σ by adapting Torquato-Jiao's adaptive-shrinking-cell formulation and sequential-linear-programming (SLP) technique. We identify 17 new structures, almost all of them chiral. Beyond D ≈ 2.85σ, most of the structures consist of an outer shell and an inner core that compete for being close packed. In some cases, the shell adopts its own maximum density configuration, and the stacking of core spheres within it is quasiperiodic. In other cases, an interplay between the two components is observed, which may result in simple periodic structures. In yet other cases, the very distinction between the core and shell vanishes, resulting in more exotic packing geometries, including some that are three-dimensional extensions of structures obtained from packing hard disks in a circle. PMID:26843132

  2. Dosimetry effects of film packing

    International Nuclear Information System (INIS)

    Full text: Dosimetric artefacts in film based dosimetry have been addressed by a number of authors. We have investigated the influence on film dose results, of a number of materials that are commonly packed against the film including, solid water, paper, air and plastic. The results indicate that variations in optical density occur due to the character and relative quantity of the packing material as well as the film itself. Kodak X-omat V and GAFChromic film samples were placed in a solid water cassette with packing sheets of various materials placed in contact with the film. Photon and electron exposures were carried out with various film orientation and beam qualities. Results have been obtained for solid water, paper and air. An example of the relative change in film density as a function of depth due to four paper sheets packed adjacent to a film aligned with the central axis of a 6MV photon beam is shown. Other results indicate dose variation can be attributed to Cerenkov radiation. Packing materials in contact or in close proximity with dosimetric film, contribute to optical density variations of the order of several percent. Careful consideration of these effects is necessary when using film in high accuracy dosimetry. Copyright (2001) Australasian College of Physical Scientists and Engineers in Medicine

  3. Sleeping distance in wild wolf packs

    Science.gov (United States)

    Knick, S.T.; Mech, L.D.

    1980-01-01

    Sleeping distances were observed among members of 13 wild wolf (Canis lupus) packs and 11 pairs in northeastern Minnesota to determine if the distances correlated with pack size and composition. The study utilized aerial radio-tracking and observation during winter. Pack size and number of adults per pack were inversely related to pack average sleeping distance and variability. No correlation between sleeping distance and microclimate was observed. Possible relationships between social bonding and our results are discussed.

  4. Commercial Application of Novel FDFCC Grid Packing Type Stripper

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhenqian; Tian Geng; Lei Shiyuan

    2007-01-01

    The novel FDFCC grid packing stripper is used to raise the stripping efficiency of the equipment.This technology aims to increase the gas-solid contact area and improve the gas-solid contact efficiency.This technology has been applied in the revamped 1.05 Mt/a No.1 FCC unit at the SINOPEC Changling Branch Company.The outcome on application of this equipment has revealed that the fluidization of the stripper was stable coupled with smooth operation.At a steam stripping load of less than 50%of the design value the spent catalyst had a lower H/C ratio,and the hydrogen content in the coke after revamp of the FCC unit decreased by 8.1%compared to the case before the equipment revamp.The spent catalyst had higher activity with the dry gasand coke yields reduced by over 0.5%.resulting in good economic benefits.

  5. Critical packing fraction in multicomponent, glass forming metallic liquids

    International Nuclear Information System (INIS)

    Glass forming Ni59.5Nb40.5 and Ni60Nb34.8Sn5.2 have been investigated in their equilibrium liquid by quasielastic neutron scattering. These liquids exhibit extraordinary high packing fraction. Structural relaxation shows stretching in time and extent of stretching depends on the temperature of the liquid. The self-diffusivity decreases about two orders of magnitude within 360 K. From the β-relaxation, τ-scaling analysis of self-diffusion and mean relaxation times of the α-process the critical packing fraction of these liquids have been derived. Our results provide, for the first time, an experimentally observed value for the critical packing fraction in the glass forming metallic liquids and is in good agreement with mode-coupling theory prediction

  6. Towards optimal packed string matching

    DEFF Research Database (Denmark)

    Ben-Kiki, Oren; Bille, Philip; Breslauer, Dany;

    2014-01-01

    -time, achieving a factor α speedup over traditional algorithms that examine each character individually. Our macro-level algorithm only uses the standard AC0 instructions of the word-RAM model (i.e. no integer multiplication) plus two specialized micro-level AC0 word-size packed-string instructions. The main word-size...... string-matching instruction wssm is available in contemporary commodity processors. The other word-size maximum-suffix instruction wslm is only required during the pattern pre-processing. Benchmarks show that our solution can be efficiently implemented, unlike some prior theoretical packed string...... matching work.(b) We also consider the complexity of the packed string matching problem in the classical word-RAM model in the absence of the specialized micro-level instructions wssm and wslm. We propose micro-level algorithms for the theoretically efficient emulation using parallel algorithms techniques...

  7. The pursuit of perfect packing

    CERN Document Server

    Weaire, Denis

    2000-01-01

    In 1998 Thomas Hales dramatically announced the solution of a problem that has long teased eminent mathematicians: what is the densest possible arrangement of identical spheres? The Pursuit of Perfect Packing recounts the story of this problem and many others that have to do with packing things together. The examples are taken from mathematics, physics, biology, and engineering, including the arrangement of soap bubbles in foam, atoms in a crystal, the architecture of the bee''s honeycomb, and the structure of the Giant''s Causeway. Using an informal style and with key references, the book also includes brief accounts of the lives of many of the scientists who devoted themselves to problems of packing over many centuries, together with wry comments on their efforts. It is an entertaining introduction to the field for both specialists and the more general public.

  8. Planet Packing in Circumbinary Systems

    CERN Document Server

    Kratter, Kaitlin M

    2013-01-01

    The recent discovery of planets orbiting main sequence binaries will provide crucial constraints for theories of binary and planet formation. The formation pathway for these planets is complicated by uncertainties in the formation mechanism of the host stars. In this paper, we compare the dynamical states of single and binary star planetary systems. Specifically, we pose two questions: (1) What does it mean for a circumbinary system to be dynamically packed? (2) How many systems are required to differentiate between a population of packed or sparse planets? We determine when circumbinary systems become dynamically unstable as a function of the separation between the host-stars and the inner planet, and the first and second planets. We show that these represent unique stability constraints compared to single-star systems. We find that although the existing Kepler data is insufficient to distinguish between a population of packed or sparse circumbinary systems, a more thorough study of circumbinary TTVs combine...

  9. Packing element of a packer

    Energy Technology Data Exchange (ETDEWEB)

    Safin, V.A.

    1982-01-01

    The packing element of a packer is proposed which consists of an elastic core and outer layer made of plastic sealing material. It is distinguished by the fact that in order to facilitate removal of the packing element from the site of installation, the outer layer has a sublayer made of polymer material which is chemically inactive in relationship to the material of the core, for example polytetrafluoroethylene. The element is also distinguished by the fact that the outer layer together with the sublayer is attached to the core through a nonhardening and nondrying glue composition, for example, based on rubber, rosin, lanolin, vaseline oil and zinc oxide.

  10. Cylinder valve packing nut studies

    Energy Technology Data Exchange (ETDEWEB)

    Blue, S.C. [Martin Marietta Energy Systems, Inc., Paducah, KY (United States)

    1991-12-31

    The design, manufacture, and use of cylinder valve packing nuts have been studied to improve their resistance to failure from stress corrosion cracking. Stress frozen photoelastic models have been analyzed to measure the stress concentrations at observed points of failure. The load effects induced by assembly torque and thermal expansion of stem packing were observed by strain gaging nuts. The effects of finishing operations and heat treatment were studied by the strain gage hole boring and X-ray methods. Modifications of manufacturing and operation practices are reducing the frequency of stress corrosion failures.

  11. Hydroliquefaction of coal with supported catalysts: 1980 status review

    Energy Technology Data Exchange (ETDEWEB)

    Polinski, Leon M.; Stiegel, Gary J.; Tischer, Richard E.

    1981-06-01

    The objectives of the program have been to determine catalyst deactivation kinetic models and catalyst deactivation modes for supported Co-Mo and Ni-Mo catalysts used primarily in coal liquefaction via the H-COAL process. Emphasis has been on developing methods to increase catalyst usage by determining how to decrease catalyst replacement rates in the process and how to decrease catalyst poisoning. An important conclusion reached via model analysis and verified by experiment is that larger diameter (1/16 in.) catalysts resist poisoning deactivation much more than smaller (1/32 in.) catalysts over extended periods (60 to 110 hours) of time. If this trend can be verified, it gives a powerful tool for reducing catalyst replacement rate in the H-COAL ebullated bed system by factors of 2 or more. A second conclusion is that poisoning of catalysts occurs by several possible mechanisms or modes. Indirect or direct evidence of all these modes can be presented, though the relative importance of each mechanism has not been established. The modes include (a) poisoning by coking - with gradual increase in C/H ratio (more refractory coke) with time, (b) poisoning by metallization (selective/non-selective adsorption of inorganics such as Ti and Fe on the catalyst), (c) sintering - increase in larger pores/decrease in surface area, and (d) parallel poisoning by irreversible nitrogen compound adsorption.

  12. Pack cementation coatings for alloys

    Energy Technology Data Exchange (ETDEWEB)

    He, Yi-Rong; Zheng, Minhui; Rapp, R.A. [Ohio State Univ., Columbus, OH (United States)

    1996-08-01

    The halide-activated pack cementation process was modified to produce a Ge-doped silicide diffusion coating on a Cr-Cr{sub 2}Nb alloy in a single processing step. The morphology and composition of the coating depended both on the composition of the pack and on the composition and microstructure of the substrate. Higher Ge content in the pack suppressed the formation of CrSi{sub 2} and reduced the growth kinetics of the coating. Ge was not homogeneously distributed in the coatings. In cyclic and isothermal oxidation in air at 700 and 1050{degrees}C, the Ge-doped silicide coating protected the Cr-Nb alloys from significant oxidation by the formation of a Ge-doped silica film. The codeposition and diffusion of aluminum and chromium into low alloy steel have been achieved using elemental Al and Cr powders and a two-step pack cementation process. Sequential process treatments at 925{degrees}C and 1150{degrees}C yield dense and uniform ferrite coatings, whose compositions are close to either Fe{sub 3}Al or else FeAl plus a lower Cr content, when processed under different conditions. The higher content of Al in the coatings was predicted by thermodynamic calculations of equilibrium in the gas phase. The effect of the particle size of the metal powders on the surface composition of the coating has been studied for various combinations of Al and Cr powders.

  13. The Maximum Resource Bin Packing Problem

    DEFF Research Database (Denmark)

    Boyar, J.; Epstein, L.; Favrholdt, L.M.;

    2006-01-01

    Usually, for bin packing problems, we try to minimize the number of bins used or in the case of the dual bin packing problem, maximize the number or total size of accepted items. This paper presents results for the opposite problems, where we would like to maximize the number of bins used or...... algorithms, First-Fit-Increasing and First-Fit-Decreasing for the maximum resource variant of classical bin packing. For the on-line variant, we define maximum resource variants of classical and dual bin packing. For dual bin packing, no on-line algorithm is competitive. For classical bin packing, we find...

  14. Valve packing manual. A maintenance application guide

    International Nuclear Information System (INIS)

    Since 1970, AECL Chalk River Mechanical Equipment Development (MED) branch has invested over 175 person years in testing related to improving valve packing performance. Successful developments, including, 'live-loading', reduced packing heights, and performance-based packing qualification testing have been implemented. Since 1986, MED and the Integrated Valve Actuator Program Task Force - Valve Packing Steering Committee (IVAP-VPSC) have been involved in the development of combination die-formed graphite packing for use in CANDU plants. Many reports, articles, and specifications have been issued. Due to the large amount of test data and reports, a more user-friendly document has been prepared for everyday use. The Valve Packing Manual is based on many years of MED research and testing, as well as operating experience from CANDU nuclear generating stations (NGS). Since 1986, packing research and testing has been funded by the CANDU Owners Group (COG), the Electric Power Research Institute (EPRI), and participating valve packing manufacturers. The Valve Packing Manual (VPM) provides topical summaries of all work related to valve packing done since 1985. It includes advances in configuration design, stem packing friction, materials specifications, and installation procedures. This paper provides an overview on the application of the VPM with a focus on qualification testing, packing configuration, and stem packing friction. (author)

  15. Packing, coding, and ground states

    OpenAIRE

    Cohn, Henry

    2016-01-01

    These are the lecture notes from my 2014 PCMI graduate summer school lectures. In these lectures, we'll study simple models of materials from several different perspectives: geometry (packing problems), information theory (error-correcting codes), and physics (ground states of interacting particle systems). These perspectives each shed light on some of the same problems and phenomena, while highlighting different techniques and connections. One noteworthy phenomenon is the exceptional symmetr...

  16. [A novel multiple-channel apparatus for packing capillary chromatographic column and its application].

    Science.gov (United States)

    Lü, Yayao; Hao, Feiran; Wang, Huanhuan; Fu, Bin; Qian, Xiaohong; Zhang, Yangjun

    2015-11-01

    A novel multiple-channel apparatus for packing capillary chromatographic column was designed and manufactured for packing six capillary chromatographic columns with close column efficiency at the same time. Briefly, it consists of a magnetic stirrer, a liquid chromatographic pump and a multiple-channel can. The reagents used for preparing ODS (C18) slurry and stirring condition of the magnetic stirrer were optimized in the study. Two batches of capillary chromatographic columns were packed under the optimum condition, and these packed capillary chromatographic columns were evaluated in the terms of peak capacity, sequence coverage, retention times of three peptide ions and column pressure using the tryptic digest of a bovine serum albumin (BSA) and detected by LC-MS in electrospray ionization (ESI) mode. The experimental results showed that the six capillary chromatographic columns packed at the same time had close column efficiencies, however, the column efficiencies of twelve capillary chromatographic columns packed at two times were significantly different. In addition, there was no significant column efficiency difference when packing one or six capillary chromatographic columns at the same time. The multiple-channel apparatus designed by us is simple, time-saving, and can be applied to pack capillary chromatographic columns with similar column efficiencies, thus it is of evident advantage over traditional one-channel apparatus. PMID:26939361

  17. A High-temperature, High-Pressure Integrated Laboratory Packed-bed Rreactor for Use in a Modular Process Environment

    Czech Academy of Sciences Publication Activity Database

    Herbstritt, F.; Heck, J.; Křišťál, Jiří; Stavárek, Petr; Vajglová, Zuzana; Jiřičný, Vladimír

    Frankfurt am Main : DECHEMA, 2012, 4.05_7743. ISBN N. [International Congress on Catalysis /15./. Munich (DE), 01.07.2012-06.07.2012] Institutional support: RVO:67985858 Keywords : gas-phase reactions * packed-bed reactor * catalyst http://events.dechema.de/events/en/test_posterlist.html

  18. Packing, tiling, orthogonality and completeness

    OpenAIRE

    Kolountzakis, Mihail N.

    1999-01-01

    Let $\\Omega \\subseteq {\\bf R}^d$ be an open set of measure 1. An open set $D \\subseteq {\\bf R}^d$ is called a ``tight orthogonal packing region'' for $\\Omega$ if $D-D$ does not intersect the zeros of the Fourier Transform of the indicator function of $\\Omega$ and $D$ has measure 1. Suppose that $\\Lambda$ is a discrete subset of ${\\bf R}^d$. The main contribution of this paper is a new way of proving the following result (proved by different methods by Lagarias, Reeds and Wang and, in the case...

  19. PlanetPack: a radial-velocity time-series analysis tool facilitating exoplanets detection, characterization, and dynamical simulations

    OpenAIRE

    Baluev, Roman V.

    2013-01-01

    We present PlanetPack, a new software tool that we developed to facilitate and standardize the advanced analysis of radial velocity (RV) data for the goal of exoplanets detection, characterization, and basic dynamical $N$-body simulations. PlanetPack is a command-line interpreter, that can run either in an interactive mode or in a batch mode of automatic script interpretation. Its major abilities include: (i) Advanced RV curve fitting with the proper maximum-likelihood treatment of unknown RV...

  20. Recycling and Activity Recovery of Chloroaluminate Ionic Liquid as Catalyst for Alkylation of Benzene with 1-Dodecene

    Institute of Scientific and Technical Information of China (English)

    乔聪震; 李成岳

    2006-01-01

    Performances of 1-butyl-3-methylimidazolium aluminium chloride ([BMIM]Cl-AlCl3) ionic liquid as catalyst for the alkylation of benzene with long chain olefins were investigated in a continuous operation mode. A small pilot plant with continuous mixing-reacting-separating-recycling functions, equipped with a static mixer reactor, a tube packed with metal Al thread and a combined liquid-liquid settling phase separator, was introduced as an alternative. The results showed that the continuous fast mixing and separation of ionic liquid catalyst from reactant mixture could be synchronously accomplished within a wider flow rate ratio range of the recycling reaction mixture to the ionic liquid catalyst. The recycling of chloroaluminate ionic liquid was realized. ICP-AES detection results of Al content in the reactants proves that in-situ Al compensation to the reaction system may be an important choice to prolong the stable running time of moisture-sensitive ionic liquid [BMIM]Cl-AlCl3 when feedstock inevitably contains trace water. It suggests that the activity of chloroaluminate ionic liquid is recovered under the in-situ Al compensation operation.

  1. Hydrogenation of Aliphatic Alkenes in a High-Temperature High-Pressure Packed-Bed Microreactor

    OpenAIRE

    Stavárek, Petr

    2012-01-01

    This contribution presents results of the characterization of a new high-temperature high-pressure integrated packed-bed microreactor (MCTU 600 from Ehrfeld Mikrotechnik BTS GmbH) for lab-scale catalyst testing. As the model reaction we used the hydrogenation of C4-C5 aliphatic alkenes heterogeneously catalyzed by Pt/Al2O3 or Pd/Al2O3.

  2. Performance assessment of a packed bed microstructured reactor - heat exchanger for methanol synthesis from syngas

    OpenAIRE

    Bakhtiary-Davijany, Hamidreza

    2010-01-01

    About 25% of the world’s proven natural gas reserves are located offshore with no present economic feasibility to be produced, shipped and sold. Utilization of these resources calls for developing new technologies, which enable conversion of “remote natural gas” to transportable fuels and chemicals at lower production capacities. On this context, investigation of compact methanol synthesis from synthesis gas over Cu based catalysts in a multi-slit Integrated Micro Packed Bed Reactor-Heat Exch...

  3. The “Theoreticals” Pack

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    The Particle Zoo is a colourful set of hand-made soft toys representing the particles in the Standard Model and beyond. It includes a “theoreticals” pack where you can find yet undiscovered particles: the best-selling Higgs boson, the graviton, the tachyon, and dark matter. Supersymmetric particle soft toys are also available on demand. But what would happen to the zoo if Nature had prepared some unexpected surprises? Julie Peasley, the zookeeper, is ready to sew new smiling faces…   The "Theoreticals" pack in the Particle Zoo. There is only one place in the world where you can buy a smiling Higgs boson and it’s not at CERN, although this is where scientists hope to observe it. The blue star-shaped particle is the best seller of Julie Peasley’s Particle Zoo – a collection of tens of soft toys representing all sorts of particles, including composite and decaying particles.  Over the years Julie’s zoo ...

  4. Temperature response to reactant concentration perturbations in a packed-bed reactor

    International Nuclear Information System (INIS)

    Unsteady-state operations are known to enhance the performance of some packed-bed reactor systems. However, negative effects of this type of operation should not be neglected. Temperature excursions developed during transients may accelerate some deactivation mechanisms, reducing catalyst lifetime and selectivity. Temperature response to perturbations in reactant concentration was studied for CO oxidation over Pt/Al2O3, in a packed-bed reactor. Experiments were conducted in the CO concentration range for which multiple steady states are observed. Temperature and concentration profiles in the packed-bed reactor at steady state were found to depend on the dynamic history of the reactor prior to the steady-state condition. (author)

  5. Structured packing: an opportunity for energy savings

    International Nuclear Information System (INIS)

    This work emphasizes the advantages about the use of structured packing. This type of packings allows by its geometry to reduce the processing time giving energy savings and throw down the production costs in several industries such as heavy water production plants, petrochemical industry and all industries involved with separation processes. There is a comparative results of energy consumption utilizing the structured vs. Raschig packings. (Author)

  6. Call packing bounds for overflow queues

    OpenAIRE

    van Dijk; Sluis, van der, B.

    2004-01-01

    Finite queueing loss systems are studied with overflow. For these systems there is no simple analytic expression for the loss probability or throughput. This paper aims to prove and promote easily computable bounds as based upon the so-called call packing principle. Under call packing a standard product form expression is available. It is proven that call packing leads to a guaranteed upper bound for the loss probability. In addition, an analytic error bound for the accuracy is derived which ...

  7. L1-norm packings from function fields

    Institute of Scientific and Technical Information of China (English)

    LI; Hongli

    2005-01-01

    In this paper, we study some packings in a cube, namely, how to pack n points in a cube so as to maximize the minimal distance. The distance is induced by the L1-norm which is analogous to the Hamming distance in coding theory. Two constructions with reasonable parameters are obtained, by using some results from a function field including divisor class group, narrow ray class group, and so on. We also present some asymptotic results of the two packings.

  8. Three techniques for obtaining algebraic circle packings

    OpenAIRE

    Louder, Larsen; Mishchenko, Andrey M.; Souto, Juan

    2014-01-01

    The main purpose of this article is to demonstrate three techniques for proving algebraicity statements about circle packings. We give proofs of three related theorems: (1) that every finite simple planar graph is the contact graph of a circle packing on the Riemann sphere, equivalently in the complex plane, all of whose tangency points, centers, and radii are algebraic, (2) that every flat conformal torus which admits a circle packing whose contact graph triangulates the torus has algebraic ...

  9. The advantages of hydraulic packing extraction

    International Nuclear Information System (INIS)

    Today's competitive environment, coupled with industry's desire to improve the efficiency of plant maintenance and operations, has management continually seeking ways to save time, money, and, at nuclear plants, radiation exposure. One area where a tremendous improvement in efficiency can be realized is valve packing removal. For example, industry experience indicates that up to 70% of the time it takes to repack a valve can be spent just removing the old packing. In some case, the bonnets of small valves are removed to facilitate packing removal and prevent stem and stuffing box damage that can occur when using packing removal picks. In other cases, small valves are simply removed and discarded because it costs less to replace the valves than to remove the packing using conventional methods. Hydraulic packing extraction greatly reduces packing removal time and will not damage the stem nor stuffing box, thus eliminating the need for bonnet removal or valve replacement. This paper will review some of the more common problems associated with manual packing extraction techniques. It will explain how hydraulic packing extraction eliminates or greatly reduces the impact of each of the problem areas. A discussion will be provided of some actual industry operating experiences related to success stories using hydraulic packing extraction. The paper will also briefly describe the operating parameters associated with hydraulic packing extraction tools. Throughout the paper, actual operating experiences from the nuclear power, fossil power, petrochemical, and refinery industries will be used to support the conclusion that hydraulic packing extraction is an alternative that can save time, money, and exposure

  10. SPECTRUM OF DIRECTED KIRKMAN PACKING DESIGNS

    Institute of Scientific and Technical Information of China (English)

    ZhangYan; DuBeiliang

    2003-01-01

    The problem studied in this article is the directed Kirkman packing, the resolvable directed packing which requires all blocks to be of size three except that ,each resolution class should contain either one block of size two(when v=2(mod 3)) or one block of size four (when v=l (mod 3)). A directed Kirkman packing design DKPD(v) is a resolvable directed packing of a v-set by the maximum possible number of resolution classes of this type. This article investigates the spectrum of DKPD(v) and it is found that it contains all positive integers v≥3 and v≠5,6.

  11. Pebble bed packing in prismatic containers

    International Nuclear Information System (INIS)

    Highlights: • The essential part of ceramic breeder blankets is pebble beds. • The packing factor for blanket relevant cavities must be known. • Tomography experiments revealed details of packing arrangements. • Packing experiments confirm that reference packing factors will be achieved. -- Abstract: New analyses of previous tomography investigations show in detail void fraction fluctuations close to walls generated by regular pebble arrangements. Local packing factors within the pebble bed were determined for characteristic zones. These results are very helpful for the interpretation of the packing experiments performed with spherical pebbles in different kinds of Plexiglas containers dominated by flat walls. The packing factors for single-size pebbles in the containers with a piston on top are fairly independent of bed height unless the height to diameter ratio becomes less than 10. For the closed rectangular containers, the development of structured packings is rendered more difficult. However, for blanket relevant bed heights, both for orthosilicate and beryllium pebbles, the packing factors obtained which agree well with previously obtained reference values

  12. Minimally packed phases in holography

    CERN Document Server

    Donos, Aristomenis

    2015-01-01

    We numerically construct asymptotically AdS black brane solutions of $D=4$ Einstein-Maxwell theory coupled to a pseudoscalar. The solutions are holographically dual to $d=3$ CFTs held at constant chemical potential and magnetic field that spontaneously break translation invariance leading to the spontaneous formation of abelian and momentum magnetisation currents flowing around the plaquettes of a periodic Bravais lattice. We analyse the three-dimensional moduli space of lattice solutions, which are generically oblique, and show that the free energy is minimised by the triangular lattice, associated with minimal packing of circles in the plane. The triangular structure persists at low temperatures indicating the existence of novel crystalline ground states.

  13. Minimally packed phases in holography

    Science.gov (United States)

    Donos, Aristomenis; Gauntlett, Jerome P.

    2016-03-01

    We numerically construct asymptotically AdS black brane solutions of D = 4 Einstein-Maxwell theory coupled to a pseudoscalar. The solutions are holographically dual to d = 3 CFTs at finite chemical potential and in a constant magnetic field, which spontaneously break translation invariance leading to the spontaneous formation of abelian and momentum magnetisation currents flowing around the plaquettes of a periodic Bravais lattice. We analyse the three-dimensional moduli space of lattice solutions, which are generically oblique, and show, for a specific value of the magnetic field, that the free energy is minimised by the triangular lattice, associated with minimal packing of circles in the plane. We show that the average stress tensor for the thermodynamically preferred phase is that of a perfect fluid and that this result applies more generally to spontaneously generated periodic phases. The triangular structure persists at low temperatures indicating the existence of novel crystalline ground states.

  14. Chain packing in polycarbonate glasses

    Science.gov (United States)

    Stueber, Dirk; Yu, Tsyr-Yan; Hess, Berk; Kremer, Kurt; O'Connor, Robert D.; Schaefer, Jacob

    2010-03-01

    Chain packing in homogeneous blends of carbonate C13-labeled bisphenol A polycarbonate with either (i) CF3-labeled bisphenol A polycarbonate or (ii) ring-F-labeled bisphenol A polycarbonate has been characterized using C13{F19} rotational-echo double-resonance (REDOR) nuclear magnetic resonance. In both blends, the C13 observed spin was at high concentration, and the F19 dephasing or probe spin was at low concentration. In this situation, an analysis in terms of a distribution of isolated heteronuclear pairs of spins is valid. Nearest-neighbor separation of C13 and F19 labels was determined by accurately mapping the initial dipolar evolution using a shifted-pulse version of REDOR. Based on the results of this experiment, the average distance from a ring-fluorine to the nearest C13O is more than 1.2 Å greater than the corresponding CF3C13O distance. Next-nearest and more-distant-neighbor separations of labels were measured in a 416-rotor-cycle constant-time version of REDOR for both blends. Statistically significant local order was established for the nearest-neighbor labels in the methyl-labeled blend. These interchain packing results are in qualitative agreement with predictions based on coarse-grained simulations of a specially adapted model for bisphenol A polycarbonate. The model itself has been previously used to determine static and dynamic properties of polycarbonate with results in good agreement with those from rheological and neutron scattering experiments.

  15. Confined disordered strictly jammed binary sphere packings

    Science.gov (United States)

    Chen, D.; Torquato, S.

    2015-12-01

    Disordered jammed packings under confinement have received considerably less attention than their bulk counterparts and yet arise in a variety of practical situations. In this work, we study binary sphere packings that are confined between two parallel hard planes and generalize the Torquato-Jiao (TJ) sequential linear programming algorithm [Phys. Rev. E 82, 061302 (2010), 10.1103/PhysRevE.82.061302] to obtain putative maximally random jammed (MRJ) packings that are exactly isostatic with high fidelity over a large range of plane separation distances H , small to large sphere radius ratio α , and small sphere relative concentration x . We find that packing characteristics can be substantially different from their bulk analogs, which is due to what we term "confinement frustration." Rattlers in confined packings are generally more prevalent than those in their bulk counterparts. We observe that packing fraction, rattler fraction, and degree of disorder of MRJ packings generally increase with H , though exceptions exist. Discontinuities in the packing characteristics as H varies in the vicinity of certain values of H are due to associated discontinuous transitions between different jammed states. When the plane separation distance is on the order of two large-sphere diameters or less, the packings exhibit salient two-dimensional features; when the plane separation distance exceeds about 30 large-sphere diameters, the packings approach three-dimensional bulk packings. As the size contrast increases (as α decreases), the rattler fraction dramatically increases due to what we call "size-disparity" frustration. We find that at intermediate α and when x is about 0.5 (50-50 mixture), the disorder of packings is maximized, as measured by an order metric ψ that is based on the number density fluctuations in the direction perpendicular to the hard walls. We also apply the local volume-fraction variance στ2(R ) to characterize confined packings and find that these

  16. Evaluation of a commercial packed bed flow hydrogenator for reaction screening, optimization, and synthesis

    Directory of Open Access Journals (Sweden)

    Marian C. Bryan

    2011-08-01

    Full Text Available The performance of the ThalesNano H-Cube®, a commercial packed bed flow hydrogenator, was evaluated in the context of small scale reaction screening and optimization. A model reaction, the reduction of styrene to ethylbenzene through a 10% Pd/C catalyst bed, was used to examine performance at various pressure settings, over sequential runs, and with commercial catalyst cartridges. In addition, the consistency of the hydrogen flow was indirectly measured by in-line UV spectroscopy. Finally, system contamination due to catalyst leaching, and the resolution of this issue, is described. The impact of these factors on the run-to-run reproducibility of the H-Cube® reactor for screening and reaction optimization is discussed.

  17. Particle-size distribution and packing fraction of geometric random packings

    NARCIS (Netherlands)

    Brouwers, H.J.H.

    2006-01-01

    This paper addresses the geometric random packing and void fraction of polydisperse particles. It is demonstrated that the bimodal packing can be transformed into a continuous particle-size distribution of the power law type. It follows that a maximum packing fraction of particles is obtained when t

  18. Foundation Flash Catalyst

    CERN Document Server

    Goralski, Greg

    2010-01-01

    This book offers an introduction to Flash Catalyst for designers with intermediate to advanced skills. It discusses where Catalyst sits within the production process and how it communicates with other programs. It covers all of the features of the Flash Catalyst workspace, teaching you how to create designs from scratch, how to build application designs and add functionality, and how to master the Catalyst/Flex workflow. * Introduces Flash Catalyst * Focuses on production process * Covers the interrelation between Flash Catalyst and Photoshop/Illustrator/Flex/Flash What you'll learn Starting f

  19. Multi objective optimization of line pack management of gas pipeline system

    International Nuclear Information System (INIS)

    This paper addresses the Line Pack Management of the ''GZ1 Hassi R'mell-Arzew'' gas pipeline. For a gas pipeline system, the decision-making on the gas line pack management scenarios usually involves a delicate balance between minimization of the fuel consumption in the compression stations and maximizing gas line pack. In order to select an acceptable Line Pack Management of Gas Pipeline scenario from these two angles for ''GZ1 Hassi R'mell- Arzew'' gas pipeline, the idea of multi-objective decision-making has been introduced. The first step in developing this approach is the derivation of a numerical method to analyze the flow through the pipeline under transient isothermal conditions. In this paper, the solver NSGA-II of the modeFRONTIER, coupled with a matlab program was used for solving the multi-objective problem

  20. Optimization of the packing design for manifold catalytic converter application

    Energy Technology Data Exchange (ETDEWEB)

    Kil, J.; Yeo, G.

    1996-09-01

    A preconverter is an essential component of the new vehicle exhaust system for the achievement of tightened emission standards. To meet those standards, the Manifold Catalytic Converter (MCC) system has been developed in the Hyundai Motor Company (HMC). Unfortunately, the conventional MCC is no longer a suitable design for the exhaust gas treatment of the newly developed high performance engine since it cannot withstand the engine`s exhaust temperature, vibration, pressure pulsation, and many other severe conditions. This paper is focused on a failure-mode analysis and new packing designs for the MCC application through a series of durability tests.

  1. Call packing bound for overflow loss systems

    NARCIS (Netherlands)

    N.M. van Dijk; E. van der Sluis

    2009-01-01

    Finite loss queues with overflow naturally arise in a variety of communications structures. For these systems, there is no simple analytic expression for the loss probability. This paper proves and promotes easily computable bounds based on the so-called call packing principle. Under call packing, a

  2. Call packing bounds for overflow queues

    NARCIS (Netherlands)

    N.M. van Dijk; E. van der Sluis

    2004-01-01

    Finite queueing loss systems are studied with overflow. For these systems there is no simple analytic expression for the loss probability or throughput. This paper aims to prove and promote easily computable bounds as based upon the so-called call packing principle. Under call packing a standard pro

  3. Pack Density Limitations of Hybrid Parachutes

    Science.gov (United States)

    Zwicker, Matthew L.; Sinclair, Robert J.

    2013-01-01

    The development and testing of the Orion crew capsule parachute system has provided a unique opportunity to study dense parachute packing techniques and limits, in order to establish a new baseline for future programs. The density of parachute packs has a significant influence on vibration loads, retention system stresses, and parachute mortar performance. Material compositions and pack densities of existing designs for space capsule recovery were compared, using the pack density of the Apollo main parachutes as the current baseline. The composition of parachutes has changed since Apollo, incorporating new materials such as Kevlar , Vectran , Teflon and Spectra . These materials have different specific densities than Nylon, so the densities of hybrid parachute packs cannot be directly compared to Nylon parachutes for determination of feasibility or volume allocation. Six parachute packs were evaluated in terms of weighted average solid density in order to achieve a non-dimensional comparison of packing density. Means of mitigating damage due to packing pressure and mortar firing were examined in light of the Capsule Parachute Assembly System (CPAS) and Apollo experience. Parachute design improvements including incorporation of modern materials and manufacturing processes serves to make CPAS the new knowledge base on which future spacecraft parachute systems will be built.

  4. Development of an effective valve packing program

    Energy Technology Data Exchange (ETDEWEB)

    Hart, K.A.

    1996-12-01

    Current data now shows that graphite valve packing installed within the guidance of a controlled program produces not only reliable stem sealing but predictable running loads. By utilizing recent technological developments in valve performance monitoring for both MOV`s and AOV`s, valve packing performance can be enhanced while reducing maintenance costs. Once known, values are established for acceptable valve packing loads, the measurement of actual valve running loads via the current MOV/AOV diagnostic techniques can provide indication of future valve stem sealing problems, improper valve packing installation or identify the opportunity for valve packing program improvements. At times the full benefit of these advances in material and predictive technology remain under utilized due to simple past misconceptions associated with valve packing. This paper will explore the basis for these misconceptions, provide general insight into the current understanding of valve packing and demonstrate how with this new understanding and current valve diagnostic equipment the key aspects required to develop an effective, quality valve packing program fit together. The cost and operational benefits provided by this approach can be significant impact by the: elimination of periodic valve repacking, reduction of maintenance costs, benefits of leak-free valve operation, justification for reduced Post Maintenance Test Requirements, reduced radiation exposure, improved plant appearance.

  5. 21 CFR 890.5700 - Cold pack.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cold pack. 890.5700 Section 890.5700 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5700 Cold pack. (a) Identification....

  6. On maximum cycle packings in polyhedral graphs

    Directory of Open Access Journals (Sweden)

    Peter Recht

    2014-04-01

    Full Text Available This paper addresses upper and lower bounds for the cardinality of a maximum vertex-/edge-disjoint cycle packing in a polyhedral graph G. Bounds on the cardinality of such packings are provided, that depend on the size, the order or the number of faces of G, respectively. Polyhedral graphs are constructed, that attain these bounds.

  7. On maximum cycle packings in polyhedral graphs

    OpenAIRE

    Peter Recht; Stefan Stehling

    2014-01-01

    This paper addresses upper and lower bounds for the cardinality of a maximum vertex-/edge-disjoint cycle packing in a polyhedral graph G. Bounds on the cardinality of such packings are provided, that depend on the size, the order or the number of faces of G, respectively. Polyhedral graphs are constructed, that attain these bounds.

  8. Protein Packing Quality Using Delaunay Complexes

    DEFF Research Database (Denmark)

    Fonseca, Rasmus; Winter, Pawel; Karplus, Kevin

    A new method for estimating the packing quality of protein structures is presented. Atoms in high quality protein crystal structures are very uniformly distributed which is difficult to reproduce using structure prediction methods. Packing quality measures can therefore be used to assess structur...

  9. BIPP (BISMUTH IODINE PARAFFINE PASTE PACK REVISITED

    Directory of Open Access Journals (Sweden)

    Balasubramanian Thiagarajan

    2011-09-01

    Full Text Available This review article takes a new look at the use of BIPP pack following nasal and ear surgeries. It lists the advantages and pitfalls of using this packing material. Pubmed search revealed very little material on this topic hence I compiled existing data to bring out an article.

  10. Difference packing arrays and systematic authentication codes

    Institute of Scientific and Technical Information of China (English)

    2004-01-01

    In this paper, a type of combinatorial design (called difference packing array)is proposed and used to give a construction of systematic authentication codes. Taking advantage of this construction, some new series of systematic authentication codes are obtainable in terms of existing difference packing arrays.

  11. Does Post Septoplasty Nasal Packing Reduce Complications?

    Directory of Open Access Journals (Sweden)

    Bijan Naghibzadeh

    2011-01-01

    Full Text Available The main issues in nasal surgery are to stabilize the nose in the good position after surgery and preserve the cartilages and bones in the favorable situation and reduce the risk of deviation recurrence. Also it is necessary to avoid the synechia formation, nasal valve narrowing, hematoma and bleeding. Due to the above mentioned problems and in order to solve and minimize them nasal packing, nasal splint and nasal mold have been advised. Patients for whom the nasal packing used may faced to some problems like naso-pulmonary reflex, intractable pain, sleep disorder, post operation infection and very dangerous complication like toxic shock syndrome. We have two groups of patients and three surgeons (one of the surgeons used post operative nasal packing in his patients and the two others surgeons did not.Complications and morbidities were compared in these two groups. Comparing the two groups showed that the rate of complication and morbidities between these two groups were same and the differences were not valuable, except the pain and discomfort post operatively and at the time of its removal. Nasal packing has several risks for the patients while its effects are not studied. Septoplasty can be safely performed without postoperative nasal packing. Nasal packing had no main findings that compensated its usage. Septal suture is one of the procedures that can be used as alternative method to nasal packing. Therefore the nasal packing after septoplasty should be reserved for the patients with increased risk of bleeding.

  12. Hawking Colloquium Packed CERN Auditoriums

    CERN Multimedia

    2006-01-01

    Stephen Hawking's week long visit to CERN included an 'exceptional CERN colloquium' which filled six auditoriums. Stephen Hawking during his visit to the ATLAS experiment. Stephen Hawking, Lucasian Professor of Cambridge University, visited the Theory Unit of the Physics Department from 24 September to 1 October 2006. As part of his visit, he gave two lectures in the main auditorium - a theoretical seminar on 'The Semi-Classical Birth of The Universe', attended by about 120 specialists; and a colloquium titled 'The Origin of The Universe'. As a key public figure in theoretical physics, his presence was eagerly awaited on both occasions. Those who wanted to attend the colloquium had to arrive early and be equipped with plenty of patience. An hour before it was due to begin, the 400 capacity of the main auditorium was already full. The lecture, simultaneously broadcast to five other fully packed CERN auditoriums, was attended by an estimated total of 850. Stephen Hawking attracted a large CERN crowd, filling ...

  13. Packing defects into ordered structures

    DEFF Research Database (Denmark)

    Bechstein, R.; Kristoffersen, Henrik Høgh; Vilhelmsen, L.B.; Rieboldt, F.; Stausholm-Møller, Jess; Wendt, S.; Hammer, B.; Besenbacher, F.

    2012-01-01

    We have studied vicinal TiO2(110) surfaces by high-resolution scanning tunneling microscopy and density functional theory calculations. On TiO2 surfaces characterized by a high density of ⟨11̅ 1⟩ steps, scanning tunneling microscopy reveals a high density of oxygen-deficient strandlike adstructur...... surfaces because building material is available at step sites. The strands on TiO2(110) represent point defects that are densely packed into ordered adstructures.......We have studied vicinal TiO2(110) surfaces by high-resolution scanning tunneling microscopy and density functional theory calculations. On TiO2 surfaces characterized by a high density of ⟨11̅ 1⟩ steps, scanning tunneling microscopy reveals a high density of oxygen-deficient strandlike adstructures....... With the help of density functional theory calculations we develop a complete structural model for the entire strand and demonstrate these adstructures to be more stable than an equivalent amount of bulk defects such as Ti interstitials. We argue that strands can form particularly easy on stepped...

  14. Pd Close Coupled Catalyst

    Institute of Scientific and Technical Information of China (English)

    Zhong Hua SHI; Mao Chu GONG; Yao Qiang CHEN

    2006-01-01

    A catalyst comprised novel high surface area alumina support was prepared to control emission of automobiles. The results showed that prepared catalyst could satisfy the requirements of a high performance close coupled catalyst for its good catalytic activity at low temperature and good stability at high temperature.

  15. Packing configuration performance for small stem diameters

    International Nuclear Information System (INIS)

    The extensive use of graphite packing and its excellent track record for large isolating valves in CANDU, Primary Heat Transfer (PHT) systems has resulted in an increased application of graphite packing on the conventional side. Many of these applications are in air operated valves (AOVs) where the packing sets are used on small stem diameters (<1 inch) with frequent short-cycling strokes (± 10% of full stroke). The direct application of the proven packing configurations for large isolated valves to control valve application has generated problems such as stiction, packing wear and, in isolated cases, stem stall. To address this issue, a test program was conducted at AECL, CRL by MED branch. The testing showed that by reconfiguring the packing sets and using PTFE wafers reductions in stem friction of 50% at ambient conditions, a 3 fold at hot conditions are achievable. The test program also demonstrated benefits gained in packing wear with different stem roughness finishes and the potential need to exercise small stems valves that see less than full stroke cycling. The paper describes the tests results and provides field support experience. (author)

  16. [Review: pathophysiology and methodology of nasal packing].

    Science.gov (United States)

    Beule, A G; Weber, R K; Kaftan, H; Hosemann, W

    2004-08-01

    Nasal packing is a frequent procedure to control spontaneous nasal bleeding or postoperative oozing following different types of nasal surgery. It strives for internal stabilization of the nasal framework and for optimizing wound healing by prevention of stenosis or synechia. A lot of different materials is used and there is no accepted standard concerning the type and application. A review on pathophysiology of the packed nose is given together with a survey on customary packing materials focussing on the specific merits, demerits and side-effects including economical aspects. PMID:15316896

  17. Improved Taxation Rate for Bin Packing Games

    Science.gov (United States)

    Kern, Walter; Qiu, Xian

    A cooperative bin packing game is a N-person game, where the player set N consists of k bins of capacity 1 each and n items of sizes a 1, ⋯ ,a n . The value of a coalition of players is defined to be the maximum total size of items in the coalition that can be packed into the bins of the coalition. We present an alternative proof for the non-emptiness of the 1/3-core for all bin packing games and show how to improve this bound ɛ= 1/3 (slightly). We conjecture that the true best possible value is ɛ= 1/7.

  18. Design of heterogeneous catalysts

    DEFF Research Database (Denmark)

    Frey, Anne Mette

    was inspired by a computational screening, suggesting that alloys such as Ni-Fe, Co-Ni, and Co-Fe should show superior activity to the industrially used nickel catalyst. Especially the Ni-Fe system was considered to be interesting, since such alloy catalysts should be both more active and cheaper than...... turned out to work well, and the best catalyst prepared had a C5+ yield almost a factor of two higher than a standard air calcined Co catalyst. In the NH3-SCR reaction it is desirable to develop an active and stable catalyst for NOx removal in automotive applications, since the traditionally used...

  19. Deactivation by carbon of iron catalysts for indirect liquefaction

    Energy Technology Data Exchange (ETDEWEB)

    Bartholomew, C.H.

    1991-01-10

    Although promoted cobalt and iron catalysts for Fischer-Tropsch (FT) synthesis of gasoline feedstock were first developed more than three decades ago, a major technical problem still limiting the commercial use of these catalysts today is carbon deactivation. This report describes recent progress in a fundamental, three-year investigation of carbon formation and its effects on the activity and selectivity of promoted iron catalysts for FT synthesis, the objectives of which are to: determine rates and mechanisms of carbon deactivation of unsupported Fe and Fe/K catalysts during CO hydrogenation over a range of CO concentrations, CO:H{sub 2} ratios, and temperatures; and model the rates of deactivation of the same catalysts in fixed-bed reactors. To accomplish the above objectives, the project is divided into the following tasks: (1) determine the kinetics of reaction and of carbon deactivation during CO hydrogenation on Fe and Fe/K catalysts coated on monolith bodies. (2) Determine the reactivities and types of carbon deposited during reaction on the same catalysts from temperature-programmed-surface-reaction spectroscopy (TPSR) and transmission electron microscopy (TEM). Determine the types of iron carbides formed at various temperatures and H{sub 2}/CO ratios using x-ray diffraction and Moessbauer spectroscopy. (3) Develop mathematical deactivation models which include heat and mass transport contributions for FT synthesis is packed-bed reactors. Progress to date is described. 48 refs., 3 figs., 1 tab.

  20. A preliminary process design and economic assessment of a catalyst rejuvenation process for waste disposal of refinery spent catalysts.

    Science.gov (United States)

    Marafi, Meena; Stanislaus, Antony; Kam, Ezra

    2008-03-01

    Spent hydroprocessing catalysts from refineries have been classified as hazardous solid waste by the United States Environmental Protection Agency (USEPA), refiners must find a viable but economical solution to solve this serious environmental issue. Catalyst rejuvenation is an attractive option for minimizing the environmental problems associated with spent catalysts. In this study, a preliminary design for such a process and the corresponding economic analysis are performed to assess the proposed catalyst rejuvenation process for metal-fouled spent catalysts generated in residue hydroprocessing units. The scenarios used in the economic assessment are based on three options of process synthesis and two operator modes. It is found that the option of rejuvenating medium and lightly fouled spent catalyst produced by the refinery will be the best solution for refiners, both environmentally and economically. PMID:17316960

  1. A New Hydrophobic Catalyst for Tritium Separation from Nuclear Effluents

    International Nuclear Information System (INIS)

    The hydrophobic catalysts were originally conceived in Canada for the deuterium enrichment and tritium separation by hydrogen-liquid water isotopic exchange in nuclear field. Unlike the conventional hydrophilic catalysts, which becomes inefficient to direct contact with liquid water, the hydrophobic catalysts kept a high catalytic activity and stability, even under the direct contact with liquid water or in presence of humid gas. Based on the long experience of the authors, in the preparation, testing and evaluation of the performances of hydrophobic catalysts, and based on the reviewed references, this paper presents up-to-date R and D activities on the preparation methods and applications of the hydrophobic catalysts, in tritium separation. The objectives of the paper are: (1) to provide a database for selection of the most appropriate catalyst and catalytic packing for above mentioned processes, (2) to asses and to find a new procedure for preparation of a new improved hydrophobic catalyst. From reviewed references we consider that platinum remains the most active and efficient catalytic metal and the TEFLON is the best wetproofing agent. A new improved hydrophobic Pt-catalyst has been proposed and is now underway. The main steps and experimental conditions of preparation are largely discussed. A new wet-proofing agent and a new binding agents (titanium oxide, cerium oxide, zirconium oxide) with catalytic role are proposed and tested. The physico-structural parameters of new improved catalyst have been determined and are discussed in details. The new proposal is a promising idea to improve the performances of conventional hydrophobic Pt-catalysts

  2. A New hydrophobic catalyst for tritium separation from nuclear effluents

    International Nuclear Information System (INIS)

    Full text: The hydrophobic catalysts were originally conceived in Canada for the deuterium enrichment and tritium separation by hydrogen-liquid water isotopic exchange in nuclear field. Unlike the conventional hydrophilic catalysts, which becomes inefficient to direct contact with liquid water, the hydrophobic catalysts kept a high catalytic activity and stability, even under the direct contact with liquid water or in presence of humid gas. Based on the long experience of the authors, in the preparation, testing and evaluation of the performances of hydrophobic catalysts, and based on the reviewed references, this paper presents current R and D activities on the preparation methods and applications of the hydrophobic catalysts, in tritium separation. The objectives of the paper are: (1) to provide a database for selection of the most appropriate catalyst and catalytic packing for above mentioned processes; (2) to find and to asses a new procedure for preparation of a new improved hydrophobic catalyst. Based on reviewed references we concluded that platinum appears to be the most active and efficient catalytic metal while the Teflon is the best wet-proofing agent. A new improved hydrophobic Pt-catalyst has been proposed and its study is now underway. The main steps and experimental conditions of preparation are largely discussed. A new wet-proofing agent and new binding agents (titanium oxide, cerium oxide, zirconium oxide) with catalytic role were proposed and now are tested. The physico-structural parameters of newly improved catalyst have been determined and are discussed in details. The new proposal is a promising idea to improve the performances of conventional hydrophobic Pt-catalysts. (authors)

  3. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander

    2009-01-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry. © 2009 ACM.

  4. Packing circles and spheres on surfaces

    KAUST Repository

    Schiftner, Alexander

    2009-12-01

    Inspired by freeform designs in architecture which involve circles and spheres, we introduce a new kind of triangle mesh whose faces\\' incircles form a packing. As it turns out, such meshes have a rich geometry and allow us to cover surfaces with circle patterns, sphere packings, approximate circle packings, hexagonal meshes which carry a torsion-free support structure, hybrid tri-hex meshes, and others. We show how triangle meshes can be optimized so as to have the incircle packing property. We explain their relation to conformal geometry and implications on solvability of optimization. The examples we give confirm that this kind of meshes is a rich source of geometric structures relevant to architectural geometry.

  5. Think Safety When Picking, Packing School Backpacks

    Science.gov (United States)

    ... 160523.html Think Safety When Picking, Packing School Backpacks Heavy, unbalanced loads can cause injury that is ... Aug. 19, 2016 (HealthDay News) -- Many students use backpacks to carry their school books and supplies, but ...

  6. Statistical inference for disordered sphere packings

    Directory of Open Access Journals (Sweden)

    Jeffrey Picka

    2012-01-01

    Full Text Available This paper gives an overview of statistical inference for disordered sphere packing processes. These processes are used extensively in physics and engineering in order to represent the internal structure of composite materials, packed bed reactors, and powders at rest, and are used as initial arrangements of grains in the study of avalanches and other problems involving powders in motion. Packing processes are spatial processes which are neither stationary nor ergodic. Classical spatial statistical models and procedures cannot be applied to these processes, but alternative models and procedures can be developed based on ideas from statistical physics.Most of the development of models and statistics for sphere packings has been undertaken by scientists and engineers. This review summarizes their results from an inferential perspective.

  7. On perfect packings in dense graphs

    CERN Document Server

    Balogh, József; Treglown, Andrew

    2011-01-01

    We say that a graph G has a perfect H-packing if there exists a set of vertex-disjoint copies of H which cover all the vertices in G. We consider various problems concerning perfect H-packings: Given positive intergers n, r, D, we characterise the edge density threshold that ensures a perfect K_r-packing in any graph G on n vertices and with minimum degree at least D. We also give two conjectures concerning degree sequence conditions which force a graph to contain a perfect H-packing. Other related embedding problems are also considered. Indeed, we give a degree sequence condition which forces a graph to contain a copy of K_r, thereby strengthening the minimum degree version of Turan's theorem. We also characterise the edge density threshold that ensures a graph G contains k vertex-disjoint cycles.

  8. An assessment on preparation methods and applications of hydrophobic Pt-catalyst in nuclear and environmental field

    International Nuclear Information System (INIS)

    Based on the long experience of the authors in the preparation, testing and evaluation of the performances of hydrophobic catalysts and based on the reviewed references, this paper presents up-to-date R and D activities on the preparation and application of hydrophobic catalysts for use in nuclear and environmental fields. Unlike the conventional hydrophilic catalysts, the hydrophobic catalysts repel the liquid water and allow the transport of the gaseous reactants and reaction products to and from catalytic active centers. For deuterium and tritium separation, over one hundred hydrophobic catalyst types have been prepared in different experimental conditions and by a large diversity of wet proofing methods. The influence of about twenty parameters on catalytic activity have been also studied. The purpose of this paper is: (1) to provide a database for preparation and selection of he most appropriate method for preparing an active hydrophobic catalyst, (2) to show how to use the hydrophobic catalyst and how to operate efficiently the reactor packed with hydrophobic catalyst, (3) to evaluate the performances and potentiality of hydrophobic catalysts in nuclear and environmental field, (4) evaluation of applications of hydrophobic catalysts in nuclear and environmental fields. As result, the following categories are shown: (1) the hydrophobic catalysts based on platinum and Teflon as wet-proofing proved to have the highest activity and the longest stability, (2) the utilization of hydrophobic catalyst as ordered mixed catalytic packing in the trickle bed or separated bed reactors is more efficient and has been entirely proved on industrial scale for tritium separation process, (3) the extension of the applications of hydrophobic catalysts for other processes which take place in the presence of saturated humidity or liquid water in environmental protection field. The merits of hydrophobic Pt-catalysts for tritium separation are discussed in comparison to other

  9. Co-Assembled Supported Catalysts: Synthesis of Nano-Structured Supported Catalysts with Hierarchic Pores through Combined Flow and Radiation Induced Co-Assembled Nano-Reactors

    Directory of Open Access Journals (Sweden)

    Galip Akay

    2016-05-01

    Full Text Available A novel generic method of silica supported catalyst system generation from a fluid state is presented. The technique is based on the combined flow and radiation (such as microwave, thermal or UV induced co-assembly of the support and catalyst precursors forming nano-reactors, followed by catalyst precursor decomposition. The transformation from the precursor to supported catalyst oxide state can be controlled from a few seconds to several minutes. The resulting nano-structured micro-porous silica supported catalyst system has a surface area approaching 300 m2/g and X-ray Diffraction (XRD-based catalyst size controlled in the range of 1–10 nm in which the catalyst structure appears as lamellar sheets sandwiched between the catalyst support. These catalyst characteristics are dependent primarily on the processing history as well as the catalyst (Fe, Co and Ni studied when the catalyst/support molar ratio is typically 0.1–2. In addition, Ca, Mn and Cu were used as co-catalysts with Fe and Co in the evaluation of the mechanism of catalyst generation. Based on extensive XRD, Scanning Electron Microscopy (SEM and Transmission Electron Microscopy (TEM studies, the micro- and nano-structure of the catalyst system were evaluated. It was found that the catalyst and silica support form extensive 0.6–2 nm thick lamellar sheets of 10–100 nm planar dimensions. In these lamellae, the alternate silica support and catalyst layer appear in the form of a bar-code structure. When these lamellae structures pack, they form the walls of a micro-porous catalyst system which typically has a density of 0.2 g/cm3. A tentative mechanism of catalyst nano-structure formation is provided based on the rheology and fluid mechanics of the catalyst/support precursor fluid as well as co-assembly nano-reactor formation during processing. In order to achieve these structures and characteristics, catalyst support must be in the form of silane coated silica nano

  10. Preparation of Weak Cation Exchange Packings Based on Monodisperse Poly (chloromethylstyrene-co-divinylbenzene) Particles and Its Chromatographic Properties

    Institute of Scientific and Technical Information of China (English)

    卫引茂; 陈强; 耿信笃

    2001-01-01

    Monodisperse poly ( chloromethylstyrene-co-divinylbenzene )particles were firstly prepared by a two-step swelling method.Based on this media, one kind of weak cation ion exchange packings was prepared. It was demonstrated that the prepared packings have comparative advantages for biopolymer separation with high column efficiency, low interstitial volume and low column backpressure, and have good resolution to proteins. The effects of salt concentration and pH of mobile phase on protein retentions were investigated. The properties of the weak cation ion exchange packings were evaluated by the unified retention model for mixed-mode interaction mechanison in ion exchange and hydrophobic interaction chromatography.

  11. iTreePack: Protein Complex Side-Chain Packing by Dual Decomposition

    OpenAIRE

    Peng, Jian; Hosur, Raghavendra; Berger, Bonnie; Xu, Jinbo

    2015-01-01

    Protein side-chain packing is a critical component in obtaining the 3D coordinates of a structure and drug discovery. Single-domain protein side-chain packing has been thoroughly studied. A major challenge in generalizing these methods to protein complexes is that they, unlike monomers, often have very large treewidth, and thus algorithms such as TreePack cannot be directly applied. To address this issue, SCWRL4 treats the complex effectively as a monomer, heuristically excluding weak interac...

  12. Multistep continuous-flow synthesis of (R)- and (S)-rolipram using heterogeneous catalysts

    Science.gov (United States)

    Tsubogo, Tetsu; Oyamada, Hidekazu; Kobayashi, Shū

    2015-04-01

    Chemical manufacturing is conducted using either batch systems or continuous-flow systems. Flow systems have several advantages over batch systems, particularly in terms of productivity, heat and mixing efficiency, safety, and reproducibility. However, for over half a century, pharmaceutical manufacturing has used batch systems because the synthesis of complex molecules such as drugs has been difficult to achieve with continuous-flow systems. Here we describe the continuous-flow synthesis of drugs using only columns packed with heterogeneous catalysts. Commercially available starting materials were successively passed through four columns containing achiral and chiral heterogeneous catalysts to produce (R)-rolipram, an anti-inflammatory drug and one of the family of γ-aminobutyric acid (GABA) derivatives. In addition, simply by replacing a column packed with a chiral heterogeneous catalyst with another column packed with the opposing enantiomer, we obtained antipole (S)-rolipram. Similarly, we also synthesized (R)-phenibut, another drug belonging to the GABA family. These flow systems are simple and stable with no leaching of metal catalysts. Our results demonstrate that multistep (eight steps in this case) chemical transformations for drug synthesis can proceed smoothly under flow conditions using only heterogeneous catalysts, without the isolation of any intermediates and without the separation of any catalysts, co-products, by-products, and excess reagents. We anticipate that such syntheses will be useful in pharmaceutical manufacturing.

  13. A biphasic oxidation of alcohols to aldehydes and ketones using a simplified packed-bed microreactor

    Directory of Open Access Journals (Sweden)

    Andrew Bogdan

    2009-04-01

    Full Text Available We demonstrate the preparation and characterization of a simplified packed-bed microreactor using an immobilized TEMPO catalyst shown to oxidize primary and secondary alcohols via the biphasic Anelli-Montanari protocol. Oxidations occurred in high yields with great stability over time. We observed that plugs of aqueous oxidant and organic alcohol entered the reactor as plugs but merged into an emulsion on the packed-bed. The emulsion coalesced into larger plugs upon exiting the reactor, leaving the organic product separate from the aqueous by-products. Furthermore, the microreactor oxidized a wide range of alcohols and remained active in excess of 100 trials without showing any loss of catalytic activity.

  14. Resin Catalyst Hybrids

    Institute of Scientific and Technical Information of China (English)

    S. Asaoka

    2005-01-01

    @@ 1Introduction: What are resin catalyst hybrids? There are typically two types of resin catalyst. One is acidic resin which representative is polystyrene sulfonic acid. The other is basic resin which is availed as metal complex support. The objective items of this study on resin catalyst are consisting of pellet hybrid, equilibrium hybrid and function hybrid of acid and base,as shown in Fig. 1[1-5].

  15. Quasistatic packings of droplets in flat microfluidic channels

    Science.gov (United States)

    Kadivar, Erfan

    2016-02-01

    As observed in recent experiments, monodisperse droplets self-assemble spontaneously in different ordered packings. In this work, we present a numerical study of the droplet packings in the flat rectangular microfluidic channels. Employing the boundary element method, we numerically solve the Stokes equation in two-dimension and investigate the appearance of droplet packing and transition between one and two-row packings of monodisperse emulsion droplets. By calculating packing force applied on the droplet interface, we investigate the effect of flow rate, droplet size, and surface tension on the packing configurations of droplets and transition between different topological packings.

  16. Research on the hydrogen-water isotope exchange reaction by Pt-SDB hydrophobic catalyst

    International Nuclear Information System (INIS)

    The authors study the Pt-SDB hydrophobic catalyst used in the hydrogen-water exchange reaction. Platinum is as active metal and the polystyrene divinylbenzene (SDB) is as hydrophobic carrier in the Pt-SDB hydrophobic catalyst. The experimental results show that the efficiency of catalytic exchange reaction is higher in random bed with a packing ratio of 1:1 mixture of catalyst and hydrophilic or 1:4 in order bed. The volume transfer coefficient increases with increasing temperature, but the trend is slow down when the temperature is above 60 degree C

  17. Coalescence preference in dense packing of bubbles

    Science.gov (United States)

    Kim, Yeseul; Gim, Bopil; Gim, Bopil; Weon, Byung Mook

    2015-11-01

    Coalescence preference is the tendency that a merged bubble from the contact of two original bubbles (parent) tends to be near to the bigger parent. Here, we show that the coalescence preference can be blocked by densely packing of neighbor bubbles. We use high-speed high-resolution X-ray microscopy to clearly visualize individual coalescence phenomenon which occurs in micro scale seconds and inside dense packing of microbubbles with a local packing fraction of ~40%. Previous theory and experimental evidence predict a power of -5 between the relative coalescence position and the parent size. However, our new observation for coalescence preference in densely packed microbubbles shows a different power of -2. We believe that this result may be important to understand coalescence dynamics in dense packing of soft matter. This work (NRF-2013R1A22A04008115) was supported by Mid-career Researcher Program through NRF grant funded by the MEST and also was supported by Ministry of Science, ICT and Future Planning (2009-0082580) and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry and Education, Science and Technology (NRF-2012R1A6A3A04039257).

  18. Direct contact condensation in packed beds

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yi; Klausner, James F.; Mei, Renwei; Knight, Jessica [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL 32611 (United States)

    2006-12-15

    A diffusion driven desalination process was recently described where a very effective direct contact condenser with a packed bed is used to condense water vapor out of an air/vapor mixture. A laboratory scale direct contact condenser has been fabricated as a twin tower structure with two stages, co-current and countercurrent. Experiments have been operated in each stage with respective saturated air inlet temperatures of 36, 40 and 43{sup o}C. The temperature and humidity data have been collected at the inlet and exit of the packed bed for different water to air mass flow ratios that vary between 0 and 2.5. A one-dimensional model based on conservation principles has been developed, which predicts the variation of temperature, humidity, and condensation rate through the condenser stages. Agreement between the model and experiments is very good. It is observed that the countercurrent flow stage condensation effectiveness is significantly higher than that for the co-current stage. The condensation heat and mass transfer rates were found to decrease when water blockages occur within the packed bed. Using high-speed digital cinematography, it was observed that this problem can occur at any operating condition, and is dependent on the packing surface wetting characteristics. This observation is used to explain the requirement for two different empirical constants, depending on packing diameter, suggested by Onda for the air side mass transfer coefficient correlation. (author)

  19. Preparation of biodiesel from soybean oil by using heterogeneous catalyst

    Directory of Open Access Journals (Sweden)

    Kaniz Ferdous, M. Rakib Uddin, Maksudur R. Khan, M. A. Islam

    2013-01-01

    Full Text Available The predicted shortage of fossil fuels and related environmental concerns has recently attracted significant attention to search alternative fuel. Biodiesel is one of the alternatives to fossil fuel. Now-a-days, most biodiesel is produced by the transesterification of oils using methanol and a homogeneous base catalyst. The use of homogeneous catalysts is normally limited to batch mode processing followed by a catalyst separation step. The immiscible glycerol phase, which accumulates during the course of the reaction, solubilizes the homogeneous base catalyst and therefore, withdraws from the reaction medium. Moreover, other difficulties of using homogeneous base catalysts relate to their sensitivity to free fatty acid (FFA and water and resulting saponification phenomenon. High energy consumption and costly separation of the catalyst from the reaction mixture have inspired the use of heterogeneous catalyst. The use of heterogeneous catalysts does not lead to the formation of soaps through neutralization of FFA and saponification of oil. In the present paper, biodiesel was prepared from crude (soybean oil by transesterification reaction using heterogeneous base catalyst name calcium oxide (CaO. Various reaction parameters were optimized and the biodiesel properties were evaluated.

  20. Preparation of biodiesel from soybean oil by using heterogeneous catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Ferdous, Kaniz; Rakib Uddin, M.; Islam, M.A. [Department of Chemical Engineering and Polymer Science, Shah Jalal University of Science and Technology, Sylhet 3114 (Bangladesh); Khan, Maksudur R. [Department of Chemical Engineering and Polymer Science, Shah Jalal University of Science and Technology, Sylhet 3114 (Bangladesh); Faculty of Chemical and Natural Resources Engineering, University Malaysia Pahang, 26300 Gambang, Kuantan, Pahang (Malaysia)

    2013-07-01

    The predicted shortage of fossil fuels and related environmental concerns has recently attracted significant attention to search alternative fuel. Biodiesel is one of the alternatives to fossil fuel. Now-a-days, most biodiesel is produced by the transesterification of oils using methanol and a homogeneous base catalyst. The use of homogeneous catalysts is normally limited to batch mode processing followed by a catalyst separation step. The immiscible glycerol phase, which accumulates during the course of the reaction, solubilizes the homogeneous base catalyst and therefore, withdraws from the reaction medium. Moreover, other difficulties of using homogeneous base catalysts relate to their sensitivity to free fatty acid (FFA) and water and resulting saponification phenomenon. High energy consumption and costly separation of the catalyst from the reaction mixture have inspired the use of heterogeneous catalyst. The use of heterogeneous catalysts does not lead to the formation of soaps through neutralization of FFA and saponification of oil. In the present paper, biodiesel was prepared from crude (soybean) oil by transesterification reaction using heterogeneous base catalyst name calcium oxide (CaO). Various reaction parameters were optimized and the biodiesel properties were evaluated.

  1. Bifunctional anode catalysts for direct methanol fuel cells

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Ferrin, Peter; Tritsaris, Georgios;

    2012-01-01

    Using the binding energy of OH* and CO* on close-packed surfaces as reactivity descriptors, we screen bulk and surface alloy catalysts for methanol electro-oxidation activity. Using these two descriptors, we illustrate that a good methanol electro-oxidation catalyst must have three key properties......: (1) the ability to activate methanol, (2) the ability to activate water, and (3) the ability to react off surface intermediates (such as CO* and OH*). Based on this analysis, an alloy catalyst made up of Cu and Pt should have a synergistic effect facilitating the activity towards methanol electro....... Adding Cu to a Pt(111) surface increases the methanol oxidation current by more than a factor of three, supporting our theoretical predictions for improved electrocatalysts....

  2. Towards the Rational Design of Nanoparticle Catalysts

    Science.gov (United States)

    Dash, Priyabrat

    This research is focused on development of routes towards the rational design of nanoparticle catalysts. Primarily, it is focused on two main projects; (1) the use of imidazolium-based ionic liquids (ILs) as greener media for the design of quasi-homogeneous nanoparticle catalysts and (2) the rational design of heterogeneous-supported nanoparticle catalysts from structured nanoparticle precursors. Each project has different studies associated with the main objective of the design of nanoparticle catalysts. In the first project, imidazolium-based ionic liquids have been used for the synthesis of nanoparticle catalysts. In particular, studies on recyclability, reuse, mode-of-stability, and long-term stability of these ionic-liquid supported nanoparticle catalysts have been done; all of which are important factors in determining the overall "greenness" of such synthetic routes. Three papers have been published/submitted for this project. In the first publication, highly stable polymer-stabilized Au, Pd and bimetallic Au-Pd nanoparticle catalysts have been synthesized in imidazolium-based 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) ionic liquid (Journal of Molecular Catalysis A: Chemical, 2008, 286, 114). The resulting nanoparticles were found to be effective and selective quasi-homogeneous catalysts towards a wide-range of hydrogenation reactions and the catalyst solution was reused for further catalytic reactions with minimal loss in activity. The synthesis of very pure and clean ILs has allowed a platform to study the effects of impurities in the imidazolium ILs on nanoparticle stability. In a later study, a new mode of stabilization was postulated where the presence of low amounts of 1-methylimidazole has substantial effects on the resulting stability of Au and Pd-Au nanoparticles in these ILs (Chemical Communications, 2009, 812). In further continuation of this study, a comparative study involving four stabilization protocols for nanoparticle

  3. Packing of ganglioside-phospholipid monolayers

    DEFF Research Database (Denmark)

    Majewski, J.; Kuhl, T.L.; Kjær, K.; Smith, G.S.

    2001-01-01

    Using synchrotron grazing-incidence x-ray diffraction (GIXD) and reflectivity, the in-plane and out-of-plane structure of mixed ganglioside-phospholipid monolayers was investigated at the air-water interface. Mixed monolayers of 0, 5, 10, 20, and 100 mol% ganglioside GM, and the phospholipid...... DPPE monolayer and does not distort the hexagonal in-plane unit cell or out-of-plane two-dimensional (2-D) packing compared with a pure DPPE monolayer. The oligosaccharide headgroups were found to extend normally from the monolayer surface, and the incorporation of these glycolipids into DPPE...... monolayers did not affect hydrocarbon tail packing (fluidization or condensation of the hydrocarbon region). This is in contrast to previous investigations of lipopolymer-lipid mixtures, where the packing structure of phospholipid monolayers was greatly altered by the inclusion of lipids bearing hydrophilic...

  4. On the Multiple Packing Densities of Triangles

    OpenAIRE

    Sriamorn, Kirati

    2014-01-01

    Given a convex disk $K$ and a positive integer $k$, let $\\delta_T^k(K)$ and $\\delta_L^k(K)$ denote the $k$-fold translative packing density and the $k$-fold lattice packing density of $K$, respectively. Let $T$ be a triangle. In a very recent paper, K. Sriamorn proved that $\\delta_L^k(T)=\\frac{2k^2}{2k+1}$. In this paper, I will show that $\\delta_T^k(T)=\\delta_L^k(T)$.

  5. Testing of packings for stuffing boxes

    International Nuclear Information System (INIS)

    The stuffing box packings function when they are sealed tight and do not obstruct the movement of the spindle. Characteristic values are necessary to characterise the materials properties of stuffing box packings. Essentially, the definitions of the characteristic values are known and can be calculated in experimental setups. It is absolutely necessary to standardise the characteristic values as well as the testing procedures in order to be able to provide comparable and reproduceable characteristic values. Depending upon the importance of the fittings, it is necessary to guarantee sufficiently exact and reliable assembly for defined operating conditions. (orig.)

  6. Imaging of drug smuggling by body packing.

    Science.gov (United States)

    Sica, Giacomo; Guida, Franco; Bocchini, Giorgio; Iaselli, Francesco; Iadevito, Isabella; Scaglione, Mariano

    2015-02-01

    Body packing, pushing, and stuffing are hazardous practices with complex medicolegal and social implications. A radiologist plays both a social and a medicolegal role in their assessment, and it should not be limited only to the identification of the packages but must also provide accurate information about their number and their exact location so as to prevent any package remains in the body packer. Radiologists must also be able to recognize the complications associated with these risky practices. Imaging assessment of body packing is performed essentially through plain abdominal X-ray and computed tomography scans. Ultrasound and magnetic resonance imaging, although with some advantages, actually have a limited use. PMID:25639176

  7. Correlation between Voronoi volumes in disc packings

    OpenAIRE

    Zhao, Song-Chuan; Sidle, Stacy; Swinney, Harry L.; Schröter, Matthias

    2011-01-01

    We measure the two-point correlation of free Voronoi volumes in binary disc packings, where the packing fraction $\\phi_{\\rm avg}$ ranges from 0.8175 to 0.8380. We observe short-ranged correlations over the whole range of $\\phi_{\\rm avg}$ and anti-correlations for $\\phi_{\\rm avg}>0.8277$. The spatial extent of the anti-correlation increases with $\\phi_{\\rm avg}$ while the position of the maximum of the anti-correlation and the extent of the positive correlation shrink with $\\phi_{\\rm avg}$. We...

  8. Catalyst for Ammonia Oxidation

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a bimetallic catalyst for ammonia oxidation, a method for producing a bimetallic catalyst for ammonia oxidation and a method for tuning the catalytic activity of a transition metal. By depositing an overlayer of less catalytic active metal onto a more catalytic...

  9. Alloy catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel alloy catalyst material for use in the synthesis of hydrogen peroxide from oxygen and hydrogen, or from oxygen and water. The present invention also relates to a cathode and an electrochemical cell comprising the novel catalyst material, and the process use...

  10. Development of a Novel Catalyst for No Decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Ates Akyurtlu; Jale Akyurtlu

    2007-06-22

    different noble metal concentrations and pretreated under different conditions were done. It is also planned to perform NO decomposition tests in a laboratory-size packed-bed reactor to obtain long-term deactivation data. Temperature programmed desorption and temperature controlled reaction runs were made with catalysts containing 15% Pt and 10% Pt on SnO{sub 2}. Catalysts containing 10% Pt resulted in significantly lower activities than 15% PT catalysts. Therefore, in the remainder of the tests 15% Pt/SnO{sub 2} catalysts were used. Isothermal reaction studies were made to elucidate the effects of temperature, oxygen, water vapor, pretreatment temperature, and space velocity on NO dissociation. It was found that the presence of oxygen and water vapor did not affect the activation energy of the NO dissociation reaction indicating the presence of the same rate controlling step for all feed compositions. Activation energy was higher for higher gas velocities suggesting the presence of mass transfer limitations at lower velocities. Presence of oxygen in the feed inhibited the NO decomposition. Having water vapor in the feed did not significantly affect the catalyst activity for catalysts pretreated at 373 K, but significantly reduced catalyst activity for catalysts pretreated at 900 K. Long-term deactivation studies indicated that the catalyst deactivated slowly both with and without the presence of added oxygen in the feed, Deactivation started later in the presence of oxygen. The activities of the catalysts investigated were too low below 1000 K for commercial applications. Their selectivity towards N{sub 2} was good at temperatures above 700 K. A different method for catalyst preparation is needed to improve the catalyst performance.

  11. Heterogeneous hydrogenation catalysts

    International Nuclear Information System (INIS)

    The main types of heterogeneous catalysts used for hydrogenation, the methods for their preparation, and the structure and chemistry of their surfaces are considered, as well as the catalytic activity and the mechanism of action in the hydrogenation of unsaturated and aromatic compounds, of CO, and of carbonyl compounds and in the hydrorefining of fuels. Chief attention is paid to supported Ni catalysts, to the methods for their preparation and physicochemical studies, and to the development of novel catalytic systems through modification. A novel type of catalyst for hydrogenation, viz. metal carbides, is described. Some aspects of the mechanochemical treatment of hydrogenation catalysts, including in situ methods, are discussed. Sulfide catalysts for hydrotreating are also discussed in detail. The bibliography includes 340 references.

  12. Bacteriological Survey of AFD (Meat Packing Plant

    Directory of Open Access Journals (Sweden)

    T. N. Rawal

    1974-04-01

    Full Text Available The paper describes the manufacturing process of freeze dried mutton from slaughtering to packing and makes an assessment of microbial build-up on equipment, hands of workers and environment in which the mutton comes in contact during processing.

  13. Optimal online bounded space multidimensional packing

    NARCIS (Netherlands)

    Epstein, L.; Stee, R. van

    2003-01-01

    We solve an open problem in the literature by providing an online algorithm for multidimensional bin packing that uses only bounded space. We show that it is optimal among bounded space algorithms for any dimension $d>1$. Its asymptotic performance ratio is $(Pi_{infty})^d$, where $Pi_{infty}approx1

  14. Close packing of rods on spherical surfaces

    Science.gov (United States)

    Smallenburg, Frank; Löwen, Hartmut

    2016-04-01

    We study the optimal packing of short, hard spherocylinders confined to lie tangential to a spherical surface, using simulated annealing and molecular dynamics simulations. For clusters of up to twelve particles, we map out the changes in the geometry of the closest-packed configuration as a function of the aspect ratio L/D, where L is the cylinder length and D the diameter of the rods. We find a rich variety of cluster structures. For larger clusters, we find that the best-packed configurations up to around 100 particles are highly dependent on the exact number of particles and aspect ratio. For even larger clusters, we find largely disordered clusters for very short rods (L/D = 0.25), while slightly longer rods (L/D = 0.5 or 1) prefer a global baseball-like geometry of smectic-like domains, similar to the behavior of large-scale nematic shells. Intriguingly, we observe that when compared to their optimal flat-plane packing, short rods adapt to the spherical geometry more efficiently than both spheres and longer rods. Our results provide predictions for experimentally realizable systems of colloidal rods trapped at the interface of emulsion droplets.

  15. Random close packing in protein cores

    Science.gov (United States)

    Gaines, Jennifer C.; Smith, W. Wendell; Regan, Lynne; O'Hern, Corey S.

    2016-03-01

    Shortly after the determination of the first protein x-ray crystal structures, researchers analyzed their cores and reported packing fractions ϕ ≈0.75 , a value that is similar to close packing of equal-sized spheres. A limitation of these analyses was the use of extended atom models, rather than the more physically accurate explicit hydrogen model. The validity of the explicit hydrogen model was proved in our previous studies by its ability to predict the side chain dihedral angle distributions observed in proteins. In contrast, the extended atom model is not able to recapitulate the side chain dihedral angle distributions, and gives rise to large atomic clashes at side chain dihedral angle combinations that are highly probable in protein crystal structures. Here, we employ the explicit hydrogen model to calculate the packing fraction of the cores of over 200 high-resolution protein structures. We find that these protein cores have ϕ ≈0.56 , which is similar to results obtained from simulations of random packings of individual amino acids. This result provides a deeper understanding of the physical basis of protein structure that will enable predictions of the effects of amino acid mutations to protein cores and interfaces of known structure.

  16. Porous bead packings for gas chromatography

    Science.gov (United States)

    Pollock, G. E.; Woeller, F. H.

    1979-01-01

    Porous polyaromatic packing beads have low polarity, high efficiency, short retention time, and may be synthesized in size range of 50 to 150 micrometers (100 to 270 mesh). Mechanically strong beads may be produced using various materials depending on elements and compounds to be identified.

  17. Radiological and practical aspects of body packing.

    Science.gov (United States)

    Pinto, A; Reginelli, A; Pinto, F; Sica, G; Scaglione, M; Berger, F H; Romano, L; Brunese, L

    2014-04-01

    Body packing represents the concealment of illegal substances in a person's body with the aim of smuggling. "Body packers" either swallow drug-filled packets or introduce drug-filled packets into their bodies rectally or vaginally with the purpose of concealing them. The three main smuggled drugs are cocaine, heroin and cannabis products. Body packing represents a serious risk of acute narcotic toxicity from drug exposure, intestinal obstruction owing to pellet impaction and bowel perforation with consequent abdominal sepsis. A suspected body packer is generally admitted to hospital to perform imaging investigations and confirm the presence of drugs in his/her body. Radiological imaging methods are essential to diagnose body packing and to detect potential complications. Increasing sophistication of traffickers and improvements in packaging add to the detection difficulty. Radiologists should be aware of the appearance of drug packets in a range of imaging modalities. This article informs physicians about the challenging aspects of body packing, its background and medicolegal issues, what imaging methods can be used and what criteria are necessary to perform a correct diagnosis. PMID:24472727

  18. Simple Cloud Chambers Using Gel Ice Packs

    Science.gov (United States)

    Kamata, Masahiro; Kubota, Miki

    2012-01-01

    Although cloud chambers are highly regarded as teaching aids for radiation education, school teachers have difficulty in using cloud chambers because they have to prepare dry ice or liquid nitrogen before the experiment. We developed a very simple and inexpensive cloud chamber that uses the contents of gel ice packs which can substitute for dry…

  19. Close packing of rods on spherical surfaces.

    Science.gov (United States)

    Smallenburg, Frank; Löwen, Hartmut

    2016-04-28

    We study the optimal packing of short, hard spherocylinders confined to lie tangential to a spherical surface, using simulated annealing and molecular dynamics simulations. For clusters of up to twelve particles, we map out the changes in the geometry of the closest-packed configuration as a function of the aspect ratio L/D, where L is the cylinder length and D the diameter of the rods. We find a rich variety of cluster structures. For larger clusters, we find that the best-packed configurations up to around 100 particles are highly dependent on the exact number of particles and aspect ratio. For even larger clusters, we find largely disordered clusters for very short rods (L/D = 0.25), while slightly longer rods (L/D = 0.5 or 1) prefer a global baseball-like geometry of smectic-like domains, similar to the behavior of large-scale nematic shells. Intriguingly, we observe that when compared to their optimal flat-plane packing, short rods adapt to the spherical geometry more efficiently than both spheres and longer rods. Our results provide predictions for experimentally realizable systems of colloidal rods trapped at the interface of emulsion droplets. PMID:27131565

  20. Catalysts, methods of making catalysts, and methods of use

    KAUST Repository

    Renard, Laetitia

    2014-03-06

    Embodiments of the present disclosure provide for catalysts, methods of making catalysts, methods of using catalysts, and the like. In an embodiment, the method of making the catalysts can be performed in a single step with a metal nanoparticle precursor and a metal oxide precursor, where a separate stabilizing agent is not needed.

  1. Catalyst in Basic Oleochemicals

    Directory of Open Access Journals (Sweden)

    Eva Suyenty

    2007-10-01

    Full Text Available Currently Indonesia is the world largest palm oil producer with production volume reaching 16 million tones per annum. The high crude oil and ethylene prices in the last 3 – 4 years contribute to the healthy demand growth for basic oleochemicals: fatty acids and fatty alcohols. Oleochemicals are starting to replace crude oil derived products in various applications. As widely practiced in petrochemical industry, catalyst plays a very important role in the production of basic oleochemicals. Catalytic reactions are abound in the production of oleochemicals: Nickel based catalysts are used in the hydrogenation of unsaturated fatty acids; sodium methylate catalyst in the transesterification of triglycerides; sulfonic based polystyrene resin catalyst in esterification of fatty acids; and copper chromite/copper zinc catalyst in the high pressure hydrogenation of methyl esters or fatty acids to produce fatty alcohols. To maintain long catalyst life, it is crucial to ensure the absence of catalyst poisons and inhibitors in the feed. The preparation methods of nickel and copper chromite catalysts are as follows: precipitation, filtration, drying, and calcinations. Sodium methylate is derived from direct reaction of sodium metal and methanol under inert gas. The sulfonic based polystyrene resin is derived from sulfonation of polystyrene crosslinked with di-vinyl-benzene. © 2007 BCREC UNDIP. All rights reserved.[Presented at Symposium and Congress of MKICS 2007, 18-19 April 2007, Semarang, Indonesia][How to Cite: E. Suyenty, H. Sentosa, M. Agustine, S. Anwar, A. Lie, E. Sutanto. (2007. Catalyst in Basic Oleochemicals. Bulletin of Chemical Reaction Engineering and Catalysis, 2 (2-3: 22-31.  doi:10.9767/bcrec.2.2-3.6.22-31][How to Link/DOI: http://dx.doi.org/10.9767/bcrec.2.2-3.6.22-31 || or local: http://ejournal.undip.ac.id/index.php/bcrec/article/view/6

  2. Characterization of deactivated bio-oil hydrotreating catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Huamin; Wang, Yong

    2016-01-18

    Deactivation of bio-oil hydrotreating catalysts remains a significant challenge because of the poor quality of pyrolysis bio-oil input for hydrotreating and understanding their deactivation mode is critical to developing improved catalysts and processes. In this research, we developed an understanding of the deactivation of two-step bio-oil hydrotreating catalysts (sulfided Ru/C and sulfided CoMo/C) through detailed characterization of the catalysts using various complimentary analytical techniques. Severe fouling of both catalysts by carbonaceous species was the major form of deactivation, which is consistent with the significant loss of surface area and pore volume of both deactivated catalysts and the significant increase of the bulk density. Further analysis of the carbonaceous species by thermogravimetric analysis and x-ray photoelectron spectroscopy indicated that the carbonaceous species was formed by condensation reaction of active species such as sugars and sugar derivatives (aldehydes and ketones) in bio-oil feedstock during bio-oil hydrotreating under the conditions and catalysts used. Microscopy results did not show metal sintering of the Ru/C catalyst. However, X-ray diffraction indicated a probable transformation of the highly-active CoMoS phase in the sulfided CoMo/C catalyst to Co8S9 and MoS2 phase with low activity. Loss of the active site by transport of inorganic elements from the bio-oil and the reactor construction material onto the catalyst surface also might be a cause of deactivation as indicated by elemental analysis of spent catalysts.

  3. Operation of FCC with mixtures of regenerated and deactivated catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Spretz, R.; Sedran, U. [INCAPE, FIQ, UNL - CONICET, Instituto de Investigaciones en Catalisis y Petroquimica, Santiago del Estero 2654, 3000 Santa Fe (Argentina)

    2001-07-13

    The operation of FCC with mixtures of coked and regenerated catalyst was studied with a riser simulator reactor on two equilibrium catalysts at 550C. The coked catalysts maintain an activity level that enables them to be used in the mixtures. The catalytic performances of the regenerated catalysts were used as references against which the behaviors of 25:75 and 50:50 (coked:regenerated) mixtures were compared. It was observed that overall catoil has to be increased to maintain conversion. While the yields of gases, gasoline and LCO showed to be independent of the operative mode, changes were observed in the selectivity to light olefins C4-C6 that are mainly due to changes in the yields of the isoparaffins in the groups. In turn, these changes could be the consequence of the resulting density of paired acid sites in the zeolite components on hydrogen transfer reactions, due to the contributions by the coked and regenerated portions of catalysts. Coke yields in mixtures of coked and regenerated catalysts are not higher, which would allow increasing catalyst circulation without impacting on heat balance. The particularities of this new operation of FCC are very dependent on catalyst properties.

  4. Correlation of atomic packing with the boson peak in amorphous alloys

    International Nuclear Information System (INIS)

    Boson peaks (BP) have been observed from phonon specific heats in 10 studied amorphous alloys. Two Einstein-type vibration modes were proposed in this work and all data can be fitted well. By measuring and analyzing local atomic structures of studied amorphous alloys and 56 reported amorphous alloys, it is found that (a) the BP originates from local harmonic vibration modes associated with the lengths of short-range order (SRO) and medium-range order (MRO) in amorphous alloys, and (b) the atomic packing in amorphous alloys follows a universal scaling law, i.e., the ratios of SRO and MRO lengths to solvent atomic diameter are 3 and 7, respectively, which exact match with length ratios of BP vibration frequencies to Debye frequency for the studied amorphous alloys. This finding provides a new perspective for atomic packing in amorphous materials, and has significant implications for quantitative description of the local atomic orders and understanding the structure-property relationship.

  5. Modified strip packing heuristics for the rectangular variable-sized bin packing problem

    Directory of Open Access Journals (Sweden)

    FG Ortmann

    2010-06-01

    Full Text Available Two packing problems are considered in this paper, namely the well-known strip packing problem (SPP and the variable-sized bin packing problem (VSBPP. A total of 252 strip packing heuristics (and variations thereof from the literature, as well as novel heuristics proposed by the authors, are compared statistically by means of 1170 SPP benchmark instances in order to identify the best heuristics in various classes. A combination of new heuristics with a new sorting method yields the best results. These heuristics are combined with a previous heuristic for the VSBPP by the authors to find good feasible solutions to 1357 VSBPP benchmark instances. This is the largest statistical comparison of algorithms for the SPP and the VSBPP to the best knowledge of the authors.

  6. Study of spent hydrorefining catalysts

    International Nuclear Information System (INIS)

    Aluminonickelmolybdenum catalysts for diesel fuel hydrorefining have been studied by DTA, XSPS, and diffuse reflection spectroscopy. Chemical and phase states of molybdenum compounds in samples of fresh catalyst, regenerated one after one year operation, and clogged with coke catalyst after five year operation, are determined. Chemical reactions and crystal-phase transformations of the molybdenum compounds during catalyst deactivation and regeneration are discussed

  7. Power generation by packed-bed air-cathode microbial fuel cells

    KAUST Repository

    Zhang, Xiaoyuan

    2013-08-01

    Catalysts and catalyst binders are significant portions of the cost of microbial fuel cell (MFC) cathodes. Many materials have been tested as aqueous cathodes, but air-cathodes are needed to avoid energy demands for water aeration. Packed-bed air-cathodes were constructed without expensive binders or diffusion layers using four inexpensive carbon-based materials. Cathodes made from activated carbon produced the largest maximum power density of 676±93mW/m2, followed by semi-coke (376±47mW/m2), graphite (122±14mW/m2) and carbon felt (60±43mW/m2). Increasing the mass of activated carbon and semi-coke from 5 to ≥15g significantly reduced power generation because of a reduction in oxygen transfer due to a thicker water layer in the cathode (~3 or ~6cm). These results indicate that a thin packed layer of activated carbon or semi-coke can be used to make inexpensive air-cathodes for MFCs. © 2013 Elsevier Ltd.

  8. Dynamic Arrest in Polymer Melts: Competition between Packing and Intramolecular Barriers

    OpenAIRE

    Bernabei, Marco; Moreno, Ángel J.; Colmenero, Juan

    2008-01-01

    We present molecular dynamics simulations of a simple model for polymer melts with intramolecular barriers. We investigate structural relaxation as a function of the barrier strength. Dynamic correlators can be consistently analyzed within the framework of the mode coupling theory of the glass transition. Control parameters are tuned in order to induce a competition between general packing effects and polymer-specific intramolecular barriers as mechanisms for dynamic arrest. This competition ...

  9. Experimental studies on the coolability of packed beds. Flooding of hot dry packed beds

    International Nuclear Information System (INIS)

    In case of a severe accident in a nuclear power plant meltdown of the reactor core can occur and form a packed bed in the lower plenum of the reactor pressure vessel (RPV) after solidification due to contact with water. The removal of after-heat and the long-term coolability is of essential interest. The efficient injection of cooling water into the packed bed has to be assured without endangering the structural integrity of the reactor pressure vessel. The experiments performed aimed to study the dry-out and the quenching (flooding) of hot dry packed beds. Two different inflow variants, bottom- and top-flooding including the variation of the starting temperature of the packed bed and the injection rate were studied. In case of bottom flooding the quenching time increases with increasing packed bed temperature and decreasing injection rate. In case of top flooding the flow pattern is more complex, in a first phase the water flows preferentially toward the RPV wall, the flow paths conduct the water downwards. The flow resistance of the packed bed increases with increasing bed temperatures. The quenching temperatures increase significantly above average.

  10. Production of syngas by ethanol reforming on Ni catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Catapan, Rafael C.; Oliveira, Amir A.M.; Donadel, Karina; Oliveira, Antonio Pedro N.; Rambo, Carlos R. [Federal University of Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. of Mechanical Engineering. Lab. of Combustion and Thermal Systems Engineering], Emails: catapan@labcet.ufsc.br, donadel@emc.ufsc.br, pedronovaes@emc.ufsc.br, rambo@enq.ufsc.br; Oliveira, Therezinha Maria N.; Wagner, Theodoro M. [Universidade da Regiao de Joinville, SC (Brazil). Campus Universitario Bom Retiro], E-mails: tnovais@univille.br, theowag@terra.com.br

    2010-07-01

    In the recent literature, attention has been directed to the development of noble metals based catalysts for the ethanol reforming. However, the high costs and low availability of noble metals, e.g. platinum, as a resource justify the development of alternatives technologically, economically and environmentally viable such as Ni-based catalysts. Here, the thermal decomposition, partial oxidation and steam reforming of ethanol over SiO{sub 2} supported Ni was studied in a packed bed reactor in the 673 - 973 K temperature range at 1 atm. The catalyst was produced from 10% NiO, 5% of bentonite and 85% (wt.) of natural amorphous silica fibers (NASF). Scanning Electron Microscopy (SEM) evaluation revealed that particles of Ni were homogeneously distributed over the NASF. The X-ray diffraction (XRD) patterns did not show peaks related to silicates in all spectra, which indicates that there is no, apparently, interaction between the nickel catalysts and SiO{sub 2} or devitrification The reactions of ethanol on this catalyst occurs mainly by the dehydrogenation reaction generating acetaldehyde. Further, CH{sub 3}CHO is decomposed to CH{sub 4} and CO. In parallel to this route, ethanol is dehydrated producing ethylene, which is successively dehydrogenated in Ni sites generating carbon on the surface. Also, carbon can be produced by consecutive dehydrogenation of CH{sub 4}. Both reactions contribute to increase the production of H{sub 2} to values higher than those predicted by the thermodynamic equilibrium. (author)

  11. Catalyst for microelectromechanical systems microreactors

    Energy Technology Data Exchange (ETDEWEB)

    Morse, Jeffrey D. (Martinez, CA); Sopchak, David A. (Livermore, CA); Upadhye, Ravindra S. (Pleasanton, CA); Reynolds, John G. (San Ramon, CA); Satcher, Joseph H. (Patterson, CA); Gash, Alex E. (Brentwood, CA)

    2011-11-15

    A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.

  12. Catalyst for microelectromechanical systems microreactors

    Science.gov (United States)

    Morse, Jeffrey D.; Sopchak, David A.; Upadhye, Ravindra S.; Reynolds, John G.; Satcher, Joseph H.; Gash, Alex E.

    2010-06-29

    A microreactor comprising a silicon wafer, a multiplicity of microchannels in the silicon wafer, and a catalyst coating the microchannels. In one embodiment the catalyst coating the microchannels comprises a nanostructured material. In another embodiment the catalyst coating the microchannels comprises an aerogel. In another embodiment the catalyst coating the microchannels comprises a solgel. In another embodiment the catalyst coating the microchannels comprises carbon nanotubes.

  13. Mesoporous molecular sieve catalysts

    DEFF Research Database (Denmark)

    Højholt, Karen Thrane

    the micropores. Furthermore, preliminary work was done using mesoporous ZSM-5 zeolites as support material for anchoring molecular CoMo6 species for the application as potential bi-functional catalyst in simultaneous hydrodesulfurisation (HDS) and hydrocracking. HDS activity tests revealed that the...... of different catalytic applications. Primarily the zeolites were modified regarding the porosity and the introduction of metals to the framework. The obtained materials were used as solid acid catalysts, as an inert matrix for stabilising metal nanoparticles and as an anchoring material for molecular...... only be used as solid acid catalysts but can also be used as a size-selective matrix. It was shown that it is possible to encapsulate 1-2 nm sized gold nanoparticles by silicalite-1 or ZSM-5 zeolite crystals thereby forming a sintering-stable and substrate size-selective oxidation catalyst. After...

  14. Epoxidation catalyst and process

    Science.gov (United States)

    Linic, Suljo; Christopher, Phillip

    2010-10-26

    Disclosed herein is a catalytic method of converting alkenes to epoxides. This method generally includes reacting alkenes with oxygen in the presence of a specific silver catalyst under conditions suitable to produce a yield of the epoxides. The specific silver catalyst is a silver nanocrystal having a plurality of surface planes, a substantial portion of which is defined by Miller indices of (100). The reaction is performed by charging a suitable reactor with this silver catalyst and then feeding the reactants to the reactor under conditions to carry out the reaction. The reaction may be performed in batch, or as a continuous process that employs a recycle of any unreacted alkenes. The specific silver catalyst has unexpectedly high selectivity for epoxide products. Consequently, this general method (and its various embodiments) will result in extraordinarily high epoxide yields heretofore unattainable.

  15. Self-similar space-filling packings in three dimensions

    OpenAIRE

    Baram, Reza Mahmoodi; Herrmann, Hans J.

    2003-01-01

    We develop an algorithm to construct new self-similar space-filling packings of spheres. Each topologically different configuration is characterized by its own fractal dimension. We also find the first bi-cromatic packing known up to now.

  16. Heterogeneous chromium catalysts

    OpenAIRE

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based silica-containing support, (c) activating the chromium-based silica-containing support, (d) chemically reducing the activated chromium-based silica-containing support to produce a precursor catalyst, (e) r...

  17. Aftermarket catalyst durability evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Bruetsch, R.I.; Cheng, J.P.; Hellman, K.H.

    1986-01-01

    Suppliers have introduced replacement aftermarket catalytic converters which are characterized by design differences from the original equipment converters in the direction of lower costs. The objective of the work reported here was to test a group of nine aftermarket catalysts from three manufacturers for 25,000 miles. Mileage was accumulated on three routes in Maryland and West Virginia characterized by varying degrees of tire wear. All catalysts were dynamometer tested on the same vehicle at the same laboratory.

  18. A multiscale methodology for CFD simulation of catalytic distillation bale packings

    Directory of Open Access Journals (Sweden)

    Ding Huidian

    2016-03-01

    Full Text Available A multiscale model for simulating the hydrodynamic behavior of catalytic bale packings has been proposed. This model combines computational fluid dynamics (CFD and macroscopic calculation. At small scale calculation, the CFD model includes 3-D volume-of-fluid (VOF simulation within representative elementary unit (REU under unsteady-state conditions. The REU constitutes gauze and catalyst domain, and porous media model is applied. At large scale calculation, a new mechanistic model deduced from the unit network model is employed. Based on liquid split proportion from small scale calculation, liquid distribution of the entire bale packing can be predicted. To evaluate different packing design, three common bale arrangements, i.e. one-bale, nine-bales and seven-bales, are compared. The area-weighted Christiansen uniformity coefficient is introduced to assess the distribution performance. A comparison between simulation and experimental results is made to validate the multiscale model. The present methodology is proved to be effective to analysis and design of catalytic distillation columns.

  19. Power Cycle Testing of Press-Pack IGBT Chips

    OpenAIRE

    Frank, Øyvind Bjerke

    2014-01-01

    In this thesis the power cycling capability of individual press-pack IGBT chips is investigated. Press-pack is a packaging technology used for power semiconductors. For press-packs, both thermal and electrical contact to the semiconductor chip is obtained by the application of force on the package. Press-pack IGBTs is claimed by the manufacturers to be especially suitable for high-power applications with large variations in power output. Power cycle testing is an accelerated lifetime stress t...

  20. On Approximating Four Covering and Packing Problems

    CERN Document Server

    Ashley, Mary; Berman, Piotr; Chaovalitwongse, Wanpracha; DasGupta, Bhaskar; Kao, Ming-Yang; 10.1016/j.jcss.2009.01.002

    2011-01-01

    In this paper, we consider approximability issues of the following four problems: triangle packing, full sibling reconstruction, maximum profit coverage and 2-coverage. All of them are generalized or specialized versions of set-cover and have applications in biology ranging from full-sibling reconstructions in wild populations to biomolecular clusterings; however, as this paper shows, their approximability properties differ considerably. Our inapproximability constant for the triangle packing problem improves upon the previous results; this is done by directly transforming the inapproximability gap of Haastad for the problem of maximizing the number of satisfied equations for a set of equations over GF(2) and is interesting in its own right. Our approximability results on the full siblings reconstruction problems answers questions originally posed by Berger-Wolf et al. and our results on the maximum profit coverage problem provides almost matching upper and lower bounds on the approximation ratio, answering a...

  1. Packing and Disorder in Substituted Fullerenes

    KAUST Repository

    Tummala, Naga Rajesh

    2016-07-15

    Fullerenes are ubiquitous as electron-acceptor and electron-transport materials in organic solar cells. Recent synthetic strategies to improve the solubility and electronic characteristics of these molecules have translated into a tremendous increase in the variety of derivatives employed in these applications. Here, we use molecular dynamics (MD) simulations to examine the impact of going from mono-adducts to bis- and tris-adducts on the structural, cohesive, and packing characteristics of [6,6]-phenyl-C60-butyric acid methyl ester (PCBM) and indene-C60. The packing configurations obtained at the MD level then serve as input for density functional theory calculations that examine the solid-state energetic disorder (distribution of site energies) as a function of chemical substitution. The variations in structural and site-energy disorders reflect the fundamental materials differences among the derivatives and impact the performance of these materials in thin-film electronic devices.

  2. Body Packing: From Seizures to Laparotomy

    Directory of Open Access Journals (Sweden)

    Joanna M. Janczak

    2015-01-01

    Full Text Available Body packing is a common method for illegal drug trafficking. Complications associated with body packing can be severe and even lead to rapid death. Thus, a timely diagnosis is warranted. As most body packers initially do not show any symptoms, making a correct diagnosis can be rather challenging. We describe a case of a 41-year-old male, who was admitted with an epileptic seizure and who turned out to be a cocaine intoxicated body packer. Due to neurological and cardiovascular deterioration an emergency surgery was performed. Four bags of cocaine could be removed. We discuss the current management regimen in symptomatic and asymptomatic body packers and highlight pearls and pitfalls with diagnosis and treatment.

  3. Liquid fluidization of particles in packed beds

    Energy Technology Data Exchange (ETDEWEB)

    Glasserman, P. (Dept. de Industrias, Universidad de Buenos Aires (Argentina)); Videla, D. (Dept. de Industrias, Universidad de Buenos Aires (Argentina)); Boehm, U. (Dept. de Industrias, Universidad de Buenos Aires (Argentina))

    1994-06-01

    The expansion behavior of solid particles fluidized by liquid within fixed packings was studied by the conductimetric method. The electrodes conforming the conductivity cell were embedded in the container walls with their center at half the height of the fluidized bed. The axial solids distribution was also measured by this technique by placing ten conductivity cells along the column. The study is limited to intermediate and turbulent flow regimes, due to the density and size of the particles used. Depending on the geometry of the packed bed, the operating range in terms of superficial velocity and the homogeneity of the fluidized bed differ from those obtained for fluidization in an empty column. Taking into account geometric aspects of the systems, a method of estimating the fluidization parameters is derived. (orig.)

  4. Pattern Generation by Bubble Packing Method

    Directory of Open Access Journals (Sweden)

    Goel V.K.

    2013-06-01

    Full Text Available This paper presents a new computational method forornamental Pattern design. The work is a concerted effort ofevaluation of various methods and the comparatively betterprocess is used for designing keeping in mind the accuracyrequirement for such Indian traditional ethnic designs. The firststep in the process to apply the CAD tools to design the patterns.Small semantics (profile are made using the mathematicalmodelling to make different pattern. Geometric constraints suchas scaling, rotation, transformation etc. are applied to make andmodify the profiles. To create patterns, obtains node locationsthrough a physically based particle simulation, which we call'bubble packing. Bubbles are closely packed on the corners,edges and on the surface domain, and nodes are placed at thecenters of the bubbles. Experimental results show that ourmethod can create high quality ornamental patterns. Thefabrication of the ornaments is on rapid prototype machine.

  5. TIBER-II TF winding pack design

    International Nuclear Information System (INIS)

    The superconducting, toroidal-field (TF) coils in the Tokamak Ignition/Burn Engineering Reactor (TIBER II) are designed with cable-in-conduit conductor (CICC) using NB3Sn composite strands. To design the CICC winding pack, the authors used an optimization technique that maximizes the conductor stability without violating the constraints imposed by the structure, electrical insulation, quench protection, and fabrication technique. Detailed helium-properties codes calculate the heat removal along a flow path, and detailed field calculations determine the temperature, current, and stability margins. The conductor sheath is designed as distributed structure to partially support the combined in-plane and out-of-plane loads generated within the winding pack. Pancakes of the coil are wound, reacted, and insulated before being potted in the case. This design is aggressive but fully consistent with good engineering practice

  6. Body packing: from seizures to laparotomy.

    Science.gov (United States)

    Janczak, Joanna M; Beutner, Ulrich; Hasler, Karin

    2015-01-01

    Body packing is a common method for illegal drug trafficking. Complications associated with body packing can be severe and even lead to rapid death. Thus, a timely diagnosis is warranted. As most body packers initially do not show any symptoms, making a correct diagnosis can be rather challenging. We describe a case of a 41-year-old male, who was admitted with an epileptic seizure and who turned out to be a cocaine intoxicated body packer. Due to neurological and cardiovascular deterioration an emergency surgery was performed. Four bags of cocaine could be removed. We discuss the current management regimen in symptomatic and asymptomatic body packers and highlight pearls and pitfalls with diagnosis and treatment. PMID:25883813

  7. Is incest common in gray wolf packs?

    Science.gov (United States)

    Smith, D.; Meier, T.; Geffen, E.; Mech, L.D.; Burch, J.W.; Adams, L.G.; Wayne, R.K.

    1997-01-01

    Wolf packs generally consist of a breeding pair and their maturing offspring that help provision and protect pack young. Because the reproductive tenure in wolves often is short, reproductively mature offspring might replace their parents, resulting in sibling or parent-offspring matings. To determine the extent of incestuous pairings, we measure relatedness based on variability in 20 microsatellite loci of mated pairs, parent-offspring pairs and siblings in two populations of gray wolves. Our 16 sampled mated pairs had values of relatedness not overlapping those of known parent-offspring or sibling dyads, which is consistent with their being unrelated or distantly related. These results suggest that full siblings or a parent and their offspring rarely mate and that incest avoidance is an important constraint on gray wolf behavioral ecology.

  8. Optimal analysis of best fit bin packing

    Czech Academy of Sciences Publication Activity Database

    Dósa, G.; Sgall, Jiří

    Berlin: Springer, 2014 - (Esparza, J.; Fraigniaud, P.; Husfeldt, T.; Koutsoupias, E.), s. 429-441. (Lecture Notes in Computer Science. 8572). ISBN 978-3-662-43947-0. [41st International Colloquium, ICALP 2014. Copenhagen (DK), 08.07.2014-11.07.2014] R&D Projects: GA ČR GBP202/12/G061 Keywords : approximation * packing Subject RIV: BA - General Mathematics http://link.springer.com/chapter/10.1007%2F978-3-662-43948-7_36

  9. Energy Efficient, Electric-Hydraulic Power Pack

    OpenAIRE

    Nyman, Johan; Rankka, Amy

    2015-01-01

    Along with increased oil prices and rising environmental issues, a demand for alternatives to combustion engine driven hydraulic applications has risen. In the field of mobile hydraulics, the hydraulic applications have traditionally been driven by the combustion engine of the vehicle on which they are mounted. By instead using a battery driven power pack the hydraulic application is able to operate without the engine running, saving fuel costs and reducing sound levels. In this thesis, the c...

  10. Force Dynamics in Weakly Vibrated Granular Packings

    OpenAIRE

    Umbanhowar, Paul; Van Hecke, Martin

    2004-01-01

    The oscillatory force F_b^ac on the bottom of a rigid, vertically vibrated, grain filled column, reveals rich granular dynamics, even when the peak acceleration of the vibrations is signicantly less than the gravitational acceleration at the earth's surface. For loose packings or high frequencies, F_b^ac 's dynamics are dominated by grain motion. For moderate driving conditions in more compact samples, grain motion is virtually absent, but F_b^ac nevertheless exhibits strongly nonlinear and h...

  11. Leaflet of the Rose4Pack project

    OpenAIRE

    Silva, A. Sanches; Costa, H. S.; F. Ramos; Castilho, M.C.; Machado, A. V.; Nóbrega, J. M.; Carneiro, O.S.; Albuquerque, T.G.; Cunha, E. (Emília)

    2013-01-01

    Projeto “Rose4Pack – Embalagem biodegradável ativa com extracto de alecrim (Rosmarinus officinalis L.) para incrementar a vida útil dos alimentos”, financiado por Fundos FEDER através do Programa Operacional Fatores de Competitividade – COMPETE (FCOMP-01-0124-FEDER-028015) e por Fundos nacionais da FCT – Fundação para a Ciência e a Tecnologia (PTDC/AGR-TEC/3366/2012).

  12. Oxygen supply for CHO cells immobilized on a packed-bed of Fibra-Cel disks.

    Science.gov (United States)

    Meuwly, F; Loviat, F; Ruffieux, P-A; Bernard, A R; Kadouri, A; von Stockar, U

    2006-03-01

    Packed-bed bioreactors (PBR) have proven to be efficient systems to culture mammalian cells at very high cell density in perfusion mode, thus leading to very high volumetric productivity. However, the immobilized cells must be continuously supplied with all nutrients in sufficient quantities to remain viable and productive over the full duration of the perfusion culture. Among all nutrients, oxygen is the most critical since it is present at very low concentration due to its low solubility in cell culture medium. This work presents the development of a model for oxygenation in a packed-bed bioreactor system. The experimental system used to develop the model was a packed-bed of Fibra-Cel disk carriers used to cultivate Chinese Hamster Ovary cells at high density ( approximately 6.1 x 10(7) cell/mL) in perfusion mode. With the help of this model, it was possible to identify if a PBR system is operated in optimal or sub-optimal conditions. Using the model, two options were proposed, which could improve the performance of the basal system by about twofold, that is, by increasing the density of immobilized cells per carrier volume from 6.1 x 10(7) to 1.2 x 10(8) cell/mL, or by increasing the packed-bed height from 0.2 to 0.4 m. Both strategies would be rather simple to test and implement in the packed-bed bioreactor system used for this study. As a result, it would be possible to achieve a substantial improvement of about twofold higher productivity as compared with the basal conditions. PMID:16358288

  13. Influence of catalyst deactivation on N2O emissions from automobiles

    International Nuclear Information System (INIS)

    Though estimates of the total N2O emitted by automobiles differ widely, automobiles are believed to be a significant source of non-agricultural anthropogenic N2O emissions. At the Third Conference of the Parties (COP-3) UN Framework Convention on Climate Change, held in Kyoto in 1997, N2O was designated as a greenhouse gas whose release into the atmosphere must be reduced. This action increased the need for more accurate estimates of automotive N2O emissions. The wide variation in estimates may be attributed to differences in emission test modes, types of catalysts, and levels of catalyst deactivation involved in the tests. In this study, we examined the influence of automotive catalyst deactivation on N2O emissions from the perspective of catalyst temperature frequency distribution. Using a model gas and deactivated three-way catalysts (TWCs), we applied the exhaust emission test modes of various countries. The results indicate that the factor behind the increase of N2O emissions following catalyst deactivation is not growth in N2O generation, but a decline in the N2O decomposition capability of the catalyst. It was also found that the effect of catalyst deactivation differs according to the catalyst composition and the emission test mode.(author)

  14. 36 CFR 34.10 - Saddle and pack animals.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Saddle and pack animals. 34... INTERIOR EL PORTAL ADMINISTRATIVE SITE REGULATIONS § 34.10 Saddle and pack animals. The use of saddle and pack animals is prohibited without a permit from the Superintendent....

  15. 21 CFR 133.124 - Cold-pack cheese food.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Cold-pack cheese food. 133.124 Section 133.124 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD... Cheese and Related Products § 133.124 Cold-pack cheese food. (a)(1) Cold-pack cheese food is the...

  16. 27 CFR 24.308 - Bottled or packed wine record.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottled or packed wine record. 24.308 Section 24.308 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS WINE Records and Reports § 24.308 Bottled or packed wine record. A proprietor who bottles, packs,...

  17. 36 CFR 2.16 - Horses and pack animals.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Horses and pack animals. 2.16... RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.16 Horses and pack animals. The following are prohibited... equipment. (b) The use of horses or pack animals outside of trails, routes or areas designated for their...

  18. 36 CFR 1002.16 - Horses and pack animals.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 3 2010-07-01 2010-07-01 false Horses and pack animals. 1002... AND RECREATION § 1002.16 Horses and pack animals. The following are prohibited: (a) The use of animals... horses or pack animals outside of trails, routes or areas designated for their use. (c) The use of...

  19. CoolPack – Simulation tools for refrigeration systems

    DEFF Research Database (Denmark)

    Jakobsen, Arne; Rasmussen, Bjarne D.; Andersen, Simon Engedal

    1999-01-01

    CoolPack is a collection of programs used for energy analysis and optimisation of refrigeration systems. CoolPack is developed at the Department of Energy Engineering at the Technical University of Denmark. The Danish Energy Agency finances the project. CoolPack is freeware and can be downloaded...

  20. 48 CFR 211.272 - Alternate preservation, packaging, and packing.

    Science.gov (United States)

    2010-10-01

    ..., packaging, and packing. 211.272 Section 211.272 Federal Acquisition Regulations System DEFENSE ACQUISITION... Requirements Documents 211.272 Alternate preservation, packaging, and packing. Use the provision at 252.211-7004, Alternate Preservation, Packaging, and Packing, in solicitations which include...

  1. Investigations on a new internally-heated tubular packed-bed methanol–steam reformer

    KAUST Repository

    Nehe, Prashant

    2015-05-01

    Small-scale reformers for hydrogen production through steam reforming of methanol can provide an alternative solution to the demand of continuous supply of hydrogen gas for the operation of Proton Exchange Membrane Fuel Cells (PEMFCs). A packed-bed type reformer is one of the potential designs for such purpose. An externally heated reformer has issues of adverse lower temperature in the core of the reformer and significant heat loss to the environment thus impacting its performance. Experimental and numerical studies on a new concept of internally heated tubular packed-bed methanol-steam reformer have been reported in this paper with improved performance in terms of higher methanol conversion and reduced heat losses to surroundings. CuO/ZnO/Al2O3 is used as the catalyst for the methanol-steam reforming reaction and a rod-type electric heater at the center of the reactor is used for supplying necessary heat for endothermic steam reforming reaction. The vaporizer and the reformer unit with a constant volume catalyst bed are integrated in the annular section of a tubular reformer unit. The performance of the reformer was investigated at various operating conditions like feed rate of water-methanol mixture, mass of the catalyst and reforming temperature. The experimental and numerical results show that the methanol conversion and CO concentration increase with internal heating for a wide range of operating conditions. The developed reformer unit generates 50-80W (based on lower heating value) of hydrogen gas for applications in PEMFCs. For optimized design and operating conditions, the reformer unit produced 298sccm reformed gas containing 70% H2, 27% CO2 and 3% CO at 200-240°C which can produce a power output of 25-32W assuming 60% fuel cell efficiency and 80% of hydrogen utilization in a PEMFC. © 2015 Hydrogen Energy Publications, LLC.

  2. Myosin molecule packing within the vertebrate skeletal muscle thick filaments. A complete bipolar model.

    Science.gov (United States)

    Skubiszak, Ludmila; Kowalczyk, Leszek

    2002-01-01

    Computer modelling related to the real dimensions of both the whole filament and the myosin molecule subfragments has revealed two alternative modes for myosin molecule packing which lead to the head disposition similar to that observed by EM on the surface of the cross-bridge zone of the relaxed vertebrate skeletal muscle thick filaments. One of the modes has been known for three decades and is usually incorporated into the so-called three-stranded model. The new mode differs from the former one in two aspects: (1) myosin heads are grouped into asymmetrical cross-bridge crowns instead of symmetrical ones; (2) not the whole myosin tail, but only a 43-nm C-terminus of each of them is straightened and near-parallel to the filament axis, the rest of the tail is twisted. Concurrent exploration of these alternative modes has revealed their influence on the filament features. The parameter values for the filament models as well as for the building units depicting the myosin molecule subfragments are verified by experimental data found in the literature. On the basis of the new mode for myosin molecule packing a complete bipolar structure of the thick filament is created. PMID:12545190

  3. HETP evaluation of structured packing distillation column

    Directory of Open Access Journals (Sweden)

    A. E. Orlando Jr.

    2009-09-01

    Full Text Available Several tests with a hydrocarbon mixture of known composition (C8-C14, obtained from DETEN Chemistry S.A., have been performed in a laboratory distillation column, having 40mm of nominal diameter and 2.2m high, with internals of Sulzer DX gauze stainless steel structured packing. The main purpose of this work was to evaluate HETP of a structured packing laboratory scale distillation column, operating continuously. Six HETP correlations available in the literature were compared in order to find out which is the most appropriate for structured packing columns working with medium distillates. Prior to the experimental tests, simulation studies using commercial software PRO/II® were performed in order to establish the optimum operational conditions for the distillation, especially concerning operating pressure, top and bottom temperatures, feed location and reflux ratio. The results of PRO/II® were very similar to the analysis of the products obtained during continuous operation, therefore permitting the use of the properties calculated by that software on the theoretical models investigated. The theoretical models chosen for HETP evaluation were: Bravo, Rocha and Fair (1985; Rocha, Bravo and Fair (1993, 1996; Brunazzi and Pagliant (1997; Carlo, Olujić and Pagliant (2006; Olujić et al., (2004. Modifications concerning calculation of specific areas were performed on the correlations in order to fit them for gauze packing HETP evaluation. As the laboratory distillation column was operated continuously, different HETP values were found by the models investigated for each section of the column. The low liquid flow rates in the top section of the column are a source of error for HETP evaluation by the models; therefore, more reliable HETP values were found in the bottom section, in which liquid flow rates were much greater. Among the theoretical models, Olujić et al. (2004 has shown good results relative to the experimental tests. In addition, the

  4. The mechanical behaviour of packed particulates

    International Nuclear Information System (INIS)

    Within the Canadian Nuclear Fuel Waste Management program, the central concept is to package used fuel in containers that would be deposited in an underground vault in a plutonic rock formation. To provide internal mechanical support for the container, the reference design specifies it to be filled with a matrix of compacted particulate material (called 'packed particulate'), such as quartz sand granules. The focus of this report is on the mechanical properties of the packed-particulate material, based on information drawn from the extant literature. We first consider the packing density of particulate matrices to minimize the remnant porosity and maximize mechanical stability under conditions of external pressure. Practical methods, involving vibratory packing, are reviewed and recommendations made to select techniques to achieve optimum packing density. The behaviour of particulates under compressive loading has been of interest to the powder metallurgy industry (i.e., the manufacture of products from pressed/sintered metal and ceramic powders) since the early decades of this century. We review the evidence showing that in short timescales, stress induced compaction occurs by particle shuffling and rearrangement, elastic distortion, plastic yielding and microfracturing. Analytical expressions are available to describe these processes in a semiquantitative fashion. Time-dependent compaction, mainly via creep mechanisms, is more complex. Much of the theoretical and experimental information is confined to higher temperatures (> 500 degrees C), where deformation rates are more rapid. Thus, for the relatively low ambient temperatures of the waste container (∼100 degrees C), we require analytical techniques to extrapolate the collective particulate creep behaviour. This is largely accomplished by employing current theories of creep deformation, particularly in the form of Deformation Mechanism Maps, which allow estimation of creep rates over a wide range of stress

  5. Magnetic and dendritic catalysts.

    Science.gov (United States)

    Wang, Dong; Deraedt, Christophe; Ruiz, Jaime; Astruc, Didier

    2015-07-21

    The recovery and reuse of catalysts is a major challenge in the development of sustainable chemical processes. Two methods at the frontier between homogeneous and heterogeneous catalysis have recently emerged for addressing this problem: loading the catalyst onto a dendrimer or onto a magnetic nanoparticle. In this Account, we describe representative examples of these two methods, primarily from our research group, and compare them. We then describe new chemistry that combines the benefits of these two methods of catalysis. Classic dendritic catalysis has involved either attaching the catalyst covalently at the branch termini or within the dendrimer core. We have used chelating pyridyltriazole ligands to insolubilize catalysts at the termini of dendrimers, providing an efficient, recyclable heterogeneous catalysts. With the addition of dendritic unimolecular micelles olefin metathesis reactions catalyzed by commercial Grubbs-type ruthenium-benzylidene complexes in water required unusually low amounts of catalyst. When such dendritic micelles include intradendritic ligands, both the micellar effect and ligand acceleration promote faster catalysis in water. With these types of catalysts, we could carry out azide alkyne cycloaddition ("click") chemistry with only ppm amounts of CuSO4·5H2O and sodium ascorbate under ambient conditions. Alternatively we can attach catalysts to the surface of superparamagnetic iron oxide nanoparticles (SPIONs), essentially magnetite (Fe3O4) or maghemite (γ-Fe2O3), offering the opportunity to recover the catalysts using magnets. Taking advantage of the merits of both of these strategies, we and others have developed a new generation of recyclable catalysts: dendritic magnetically recoverable catalysts. In particular, some of our catalysts with a γ-Fe2O3@SiO2 core and 1,2,3-triazole tethers and loaded with Pd nanoparticles generate strong positive dendritic effects with respect to ligand loading, catalyst loading, catalytic activity and

  6. Multi-pack Disposal Concepts for Spent Fuel (Rev. 0)

    Energy Technology Data Exchange (ETDEWEB)

    Hadgu, Teklu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hardin, Ernest [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Matteo, Edward N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    At the initiation of the Used Fuel Disposition (UFD) R&D campaign, international geologic disposal programs and past work in the U.S. were surveyed to identify viable disposal concepts for crystalline, clay/shale, and salt host media (Hardin et al., 2012). Concepts for disposal of commercial spent nuclear fuel (SNF) and high-level waste (HLW) from reprocessing are relatively advanced in countries such as Finland, France, and Sweden. The UFD work quickly showed that these international concepts are all “enclosed,” whereby waste packages are emplaced in direct or close contact with natural or engineered materials . Alternative “open” modes (emplacement tunnels are kept open after emplacement for extended ventilation) have been limited to the Yucca Mountain License Application Design (CRWMS M&O, 1999). Thermal analysis showed that, if “enclosed” concepts are constrained by peak package/buffer temperature, waste package capacity is limited to 4 PWR assemblies (or 9-BWR) in all media except salt. This information motivated separate studies: 1) extend the peak temperature tolerance of backfill materials, which is ongoing; and 2) develop small canisters (up to 4-PWR size) that can be grouped in larger multi-pack units for convenience of storage, transportation, and possibly disposal (should the disposal concept permit larger packages). A recent result from the second line of investigation is the Task Order 18 report: Generic Design for Small Standardized Transportation, Aging and Disposal Canister Systems (EnergySolution, 2015). This report identifies disposal concepts for the small canisters (4-PWR size) drawing heavily on previous work, and for the multi-pack (16-PWR or 36-BWR).

  7. Multi-Pack Disposal Concepts for Spent Fuel (Revision 1)

    Energy Technology Data Exchange (ETDEWEB)

    Hardin, Ernest [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Matteo, Edward N. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hadgu, Teklu [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    At the initiation of the Used Fuel Disposition (UFD) R&D campaign, international geologic disposal programs and past work in the U.S. were surveyed to identify viable disposal concepts for crystalline, clay/shale, and salt host media. Concepts for disposal of commercial spent nuclear fuel (SNF) and high-level waste (HLW) from reprocessing are relatively advanced in countries such as Finland, France, and Sweden. The UFD work quickly showed that these international concepts are all “enclosed,” whereby waste packages are emplaced in direct or close contact with natural or engineered materials . Alternative “open” modes (emplacement tunnels are kept open after emplacement for extended ventilation) have been limited to the Yucca Mountain License Application Design. Thermal analysis showed that if “enclosed” concepts are constrained by peak package/buffer temperature, that waste package capacity is limited to 4 PWR assemblies (or 9 BWR) in all media except salt. This information motivated separate studies: 1) extend the peak temperature tolerance of backfill materials, which is ongoing; and 2) develop small canisters (up to 4-PWR size) that can be grouped in larger multi-pack units for convenience of storage, transportation, and possibly disposal (should the disposal concept permit larger packages). A recent result from the second line of investigation is the Task Order 18 report: Generic Design for Small Standardized Transportation, Aging and Disposal Canister Systems. This report identifies disposal concepts for the small canisters (4-PWR size) drawing heavily on previous work, and for the multi-pack (16-PWR or 36-BWR).

  8. Multi-Pack Disposal Concepts for Spent Fuel (Revision 1)

    International Nuclear Information System (INIS)

    At the initiation of the Used Fuel Disposition (UFD) R&D campaign, international geologic disposal programs and past work in the U.S. were surveyed to identify viable disposal concepts for crystalline, clay/shale, and salt host media. Concepts for disposal of commercial spent nuclear fuel (SNF) and high-level waste (HLW) from reprocessing are relatively advanced in countries such as Finland, France, and Sweden. The UFD work quickly showed that these international concepts are all "enclosed,"whereby waste packages are emplaced in direct or close contact with natural or engineered materials . Alternative "open"modes (emplacement tunnels are kept open after emplacement for extended ventilation) have been limited to the Yucca Mountain License Application Design. Thermal analysis showed that if "enclosed"concepts are constrained by peak package/buffer temperature, that waste package capacity is limited to 4 PWR assemblies (or 9 BWR) in all media except salt. This information motivated separate studies: 1) extend the peak temperature tolerance of backfill materials, which is ongoing; and 2) develop small canisters (up to 4-PWR size) that can be grouped in larger multi-pack units for convenience of storage, transportation, and possibly disposal (should the disposal concept permit larger packages). A recent result from the second line of investigation is the Task Order 18 report: Generic Design for Small Standardized Transportation, Aging and Disposal Canister Systems. This report identifies disposal concepts for the small canisters (4-PWR size) drawing heavily on previous work, and for the multi-pack (16-PWR or 36-BWR).

  9. Multi-pack Disposal Concepts for Spent Fuel (Rev. 0)

    International Nuclear Information System (INIS)

    At the initiation of the Used Fuel Disposition (UFD) R&D campaign, international geologic disposal programs and past work in the U.S. were surveyed to identify viable disposal concepts for crystalline, clay/shale, and salt host media (Hardin et al., 2012). Concepts for disposal of commercial spent nuclear fuel (SNF) and high-level waste (HLW) from reprocessing are relatively advanced in countries such as Finland, France, and Sweden. The UFD work quickly showed that these international concepts are all 'enclosed', whereby waste packages are emplaced in direct or close contact with natural or engineered materials . Alternative 'open' modes (emplacement tunnels are kept open after emplacement for extended ventilation) have been limited to the Yucca Mountain License Application Design (CRWMS M&O, 1999). Thermal analysis showed that, if 'enclosed' concepts are constrained by peak package/buffer temperature, waste package capacity is limited to 4 PWR assemblies (or 9-BWR) in all media except salt. This information motivated separate studies: 1) extend the peak temperature tolerance of backfill materials, which is ongoing; and 2) develop small canisters (up to 4-PWR size) that can be grouped in larger multi-pack units for convenience of storage, transportation, and possibly disposal (should the disposal concept permit larger packages). A recent result from the second line of investigation is the Task Order 18 report: Generic Design for Small Standardized Transportation, Aging and Disposal Canister Systems (EnergySolution, 2015). This report identifies disposal concepts for the small canisters (4-PWR size) drawing heavily on previous work, and for the multi-pack (16-PWR or 36-BWR).

  10. Gaseous phase benzene decomposition by non-thermal plasma coupled with nano titania catalyst

    International Nuclear Information System (INIS)

    Synergistic effect of atmospheric non-thermal plasma generated by dielectric barrier discharge and nano titania photo catalyst for benzene decomposition was tested. The paper indicated the effect of photo catalyst on removal efficiency of benzene, the compare of photo catalyst characteristic in different high temperatures by heat treatment, analysis of by-products. The results showed that the effect of degradation was visible by added photo catalyst in the plasma reactor. When concentration of benzene was 600 mg/m3 and electric field strength was 10 kV/cm, the removal efficiency of benzene was increased up to 81 % without photo catalyst. At the same condition, the removal efficiency was increased to 15 % higher with photo catalyst. Nano titania crystal was anatase crystal in 450 degC heat treatment which is best for benzene removal. The plasma reactor packed with photo catalyst shows a better selectivity of carbon dioxide than that without photo catalyst. By-products are mostly carbon dioxide, water and a small quantity of carbon monoxide

  11. Eating less from bigger packs: Preventing the pack size effect with diet primes.

    Science.gov (United States)

    Versluis, Iris; Papies, Esther K

    2016-05-01

    An increase in the package size of food has been shown to lead to an increase in energy intake from this food, the so-called pack size effect. Previous research has shown that providing diet-concerned individuals with a reminder, or prime, of their dieting goal can help them control their consumption. Here, we investigated if providing such a prime is also effective for reducing the magnitude of the pack size effect. We conducted two experiments in which the cover of a dieting magazine (Experiment 1) and diet-related commercials (Experiment 2) served as diet goal primes. Both experiments had a 2 (pack size: small vs. large) × 2 (prime: diet vs. control) × 2 (dietary restraint: high vs. low) between participants design. We measured expected consumption of four snack foods in Experiment 1 (N = 477), and actual consumption of M&M's in Experiment 2 (N = 224). Results showed that the diet prime reduced the pack size effect for both restrained and unrestrained eaters in Experiment 1 and for restrained eaters only in Experiment 2. Although effect sizes were small, these findings suggest that a diet prime motivates restrained eaters to limit their consumption, and as a result the pack size has less influence on the amount consumed. We discuss limitations of this research as well as potential avenues for further research and theoretical and practical implications. PMID:26876911

  12. Full-scale experimental studies of the various type mass exchange packings by water distillation

    International Nuclear Information System (INIS)

    The full scale experimental assembly for study of water distillation and experimental Deprotization Plant are described. The packed sections height of the assembly was 2000 mm. Their inner diameters were from 80 to 150 mm. Characteristics of water distillation columns were studied for three species of random packing. The overall height equivalent to a theoretical plate (HETP) values measured during total reflux mode showed no apparent dependence on vapor flow rate and pressure. The spiral prismatic packing has the HETP value of 26 mm and 43 mm for column of 80 and 150 mm respectively. The ring packing (type Dixon ring) from brass gauze has the smallest pressure drop and the larger operating flow rate of vapor. The Deprotization Plant was built and successfully operates. It allows to remove up to 20 kg H2O per year and upgrade the concentration in heavy water reflector of critical assembly on the level 99.8% D2O. In addition the plant has a possibility for reprocessing of heavy water wastes. 7 refs., 7 figs., 1 tab

  13. Improved Absolute Approximation Ratios for Two-Dimensional Packing Problems

    Science.gov (United States)

    Harren, Rolf; van Stee, Rob

    We consider the two-dimensional bin packing and strip packing problem, where a list of rectangles has to be packed into a minimal number of rectangular bins or a strip of minimal height, respectively. All packings have to be non-overlapping and orthogonal, i.e., axis-parallel. Our algorithm for strip packing has an absolute approximation ratio of 1.9396 and is the first algorithm to break the approximation ratio of 2 which was established more than a decade ago. Moreover, we present a polynomial time approximation scheme (mathcal{PTAS}) for strip packing where rotations by 90 degrees are permitted and an algorithm for two-dimensional bin packing with an absolute worst-case ratio of 2, which is optimal provided mathcal{P} not= mathcal{NP}.

  14. Catalyst component interactions in nickel/alumina catalyst

    Directory of Open Access Journals (Sweden)

    Kiš Erne E.

    2007-01-01

    Full Text Available The influence of nickel loading (5; 10; 20 wt% Ni, temperature of heat treatment (400; 700; 1100°C and way of catalyst preparation on the catalyst component interactions (CCI in the impregnated, mechanical powder mixed and co-precipitated catalyst was investigated. For sample characterization, low temperature nitrogen adsorption (LTNA and X-ray diffraction (XRD were applied. Significant differences were revealed, concerning CCI in dependence of nickel loading, temperature of heat treatment and way of catalyst preparation. The obtained results show that the support metal oxide interactions (SMI in impregnated and co-precipitated catalysts are more intensive than in the mechanical powder mixed catalyst. The degree and intensity of CCI is expressed by the ratio of real and theoretical surface area of the catalyst. This ratio can be used for a quantitative estimation of CCI and it is generally applicable to all types of heterogeneous catalysts.

  15. Method of synthesizing bulk transition metal carbide, nitride and phosphide catalysts

    Science.gov (United States)

    Choi, Jae Soon; Armstrong, Beth L; Schwartz, Viviane

    2015-04-21

    A method for synthesizing catalyst beads of bulk transmission metal carbides, nitrides and phosphides is provided. The method includes providing an aqueous suspension of transition metal oxide particles in a gel forming base, dropping the suspension into an aqueous solution to form a gel bead matrix, heating the bead to remove the binder, and carburizing, nitriding or phosphiding the bead to form a transition metal carbide, nitride, or phosphide catalyst bead. The method can be tuned for control of porosity, mechanical strength, and dopant content of the beads. The produced catalyst beads are catalytically active, mechanically robust, and suitable for packed-bed reactor applications. The produced catalyst beads are suitable for biomass conversion, petrochemistry, petroleum refining, electrocatalysis, and other applications.

  16. Mesoporous zeolite single crystal catalysts: Diffusion and catalysis in hierarchical zeolites

    DEFF Research Database (Denmark)

    Christensen, Christina Hviid; Johannsen, Kim; Toernqvist, Eric; Schmidt, Iver; Topsoe, Henrik; Christensen, Claus H.

    exhibit higher catalytic activity, but in some cases also improved selectivity and longer catalyst lifetime has been reported. The beneficial effects of introducing mesopores into the zeolites has in most instances been attributed to improved mass transport to and from the active sites located in the...... zeolite micropores. Here, we briefly discuss the most important ways of introducing mesopores into zeolites and, for the first time, we show experimentally that the presence of mesopores dramatically increases the rate of diffusion in zeolite catalysts. This is done by studying the elution of iso......-butane from packed beds of conventional and mesoporous zeolite catalysts. Moreover, we discuss in detail the recent observation of improved activity and selectivity in the alkylation of benzene with ethene using mesoporous zeolite single crystal catalysts. For this reaction, we show by calculation of the...

  17. Deactivation-resistant catalyst for selective catalyst reduction of NOx

    OpenAIRE

    Jensen, Anker Degn; Castellino, Francesco; Rams, Per Donskov; Pedersen, Jannik Blaabjerg; Putluru, Siva Sankar Reddy

    2011-01-01

    The present invention relates to a catalyst for selective catalytic reduction of NOx in alkali metal containing flue gas using ammonia as reductant, the catalyst comprising a surface with catalytically active sites, wherein the surface is at least partly coated with a coating comprising at least one metal oxide. In another aspect the present invention relates to the use of said catalyst and to a method of producing said catalyst. In addition, the present invention relates to a method of treat...

  18. Supported organoiridium catalysts for alkane dehydrogenation

    Energy Technology Data Exchange (ETDEWEB)

    Baker, R. Thomas; Sattelberger, Alfred P.; Li, Hongbo

    2013-09-03

    Solid supported organoiridium catalysts, a process for preparing such solid supported organoiridium catalysts, and the use of such solid supported organoiridium catalysts in dehydrogenation reactions of alkanes is provided. The catalysts can be easily recovered and recycled.

  19. Hydrophobic catalyst applications in the nuclear field and in environmental studies

    International Nuclear Information System (INIS)

    The paper presents methods of preparation and applications of hydrophobic platinum catalysts in nuclear field and environmental protection. These catalysts allow the transport of gaseous reactants and reaction products to and from catalytic active centers since the pore blocking by water is avoided. Hence the activity and stability of the catalysts increase and isotopic exchange columns with simpler internal structure can be achieved. The aim of the paper is: 1. to give a data base regarding the preparation methods of the optimal catalyst type; 2. to indicate the utilization and operation procedures of hydrophobic catalysts with mixed and simple packings; 3. to evaluate the performances and applications of hydrophobic catalysts. Over one hundred of hydrophobic catalysts of the active metal/support type were prepared in our laboratory. Hydrophobic features were obtained by different methods like these: - coating a hydrophilic conventional catalyst with a hydrophobic agent such as silicone or teflon; - supporting the active metal directly into the pores of a hydrophobic support; - mixing the teflon powder with a hydrophilic conventional catalyst; coating the support with teflon followed by the impregnation with the precursor of the active metal. The most important application of these catalysts is detritiation of the heavy water used as moderator and coolant in CANDU type reactors. Build-up of tritium in heavy water following the neutron capture by deuterium leads to a reduction in the moderating properties and at the same time leads to a contamination hazard for both operation personnel and environment. Tritium recovery leads this way to both improving the moderating qualities of the heavy water and obtaining valuable pure tritium of high importance in fusion research and other laboratory studies. One gram of tritium costs about USD 10,000. The physical chemical process is water-hydrogen catalyzed isotopic exchange. Also discussed in the paper is the separation of

  20. Comparing Online Algorithms for Bin Packing Problems

    DEFF Research Database (Denmark)

    Epstein, Leah; Favrholdt, Lene Monrad; Kohrt, Jens Svalgaard

    2012-01-01

    The relative worst-order ratio is a measure of the quality of online algorithms. In contrast to the competitive ratio, this measure compares two online algorithms directly instead of using an intermediate comparison with an optimal offline algorithm. In this paper, we apply the relative worst......-order ratio to online algorithms for several common variants of the bin packing problem. We mainly consider pairs of algorithms that are not distinguished by the competitive ratio and show that the relative worst-order ratio prefers the intuitively better algorithm of each pair....

  1. Importance of packing in spiral defect chaos

    Indian Academy of Sciences (India)

    Kapilanjan Krishna

    2008-04-01

    We develop two measures to characterize the geometry of patterns exhibited by the state of spiral defect chaos, a weakly turbulent regime of Rayleigh-Bénard convection. These describe the packing of contiguous stripes within the pattern by quantifying their length and nearest-neighbor distributions. The distributions evolve towards unique distribution with increasing Rayleigh number that suggests power-law scaling for the dynamics in the limit of infinite system size. The techniques are generally applicable to patterns that are reducible to a binary representation.

  2. School meal sociality or lunch pack individualism?

    DEFF Research Database (Denmark)

    Andersen, Sidse Schoubye; Holm, Lotte; Baarts, Charlotte

    2015-01-01

    the social life of a school class, and how these arrangements involve strategies of both inclusion and exclusion. Two types of school meals are compared in the intervention study: a hot meal based on Nordic ingredients and the normal Danish school meal arrangement in which children bring lunch packs...... to school. The study discusses commensality by examining and comparing lunchtime interactions within the same group of children in the two contrasting meal situations. The results fail to confirm the conventional view that shared meals have greater social impacts and benefits than eating individualized...

  3. Dynamics of Catalyst Nanoparticles

    DEFF Research Database (Denmark)

    Hansen, Thomas Willum; Cavalca, Filippo; Wagner, Jakob Birkedal

    under gas exposure, dynamic phenomena such as sintering and growth can be observed with sub-Ångstrøm resolution. Metal nanoparticles contain the active sites in heterogeneous catalysts, which are important for many industrial applications including the production of clean fuels, chemicals...... and pharmaceuticals, and the cleanup of exhaust from automobiles and stationary power plants. Sintering, or thermal deactivation, is an important mechanism for the loss of catalyst activity. In order to initiate a systematic study of the dynamics and sintering of nanoparticles, various catalytic systems have been...

  4. An efficient block-discriminant identification of packed malware

    Indian Academy of Sciences (India)

    Smita Naval; Vijay Laxmi; Manoj Singh Gaur; P Vinod

    2015-08-01

    Advanced persistent attacks, incorporated by sophisticated malware, are on the rise against hosts, user applications and utility software. Modern malware hide their malicious payload by applying packing mechanism. Packing tools instigate code encryption to protect the original malicious payload. Packing is employed in tandem with code obfuscation/encryption/compression to create malware variants. Despite being just a variant of known malware, the packed malware invalidates the traditional signature based malware detection as packing tools create an envelope of packer code around the original base malware. Therefore, unpacking becomes a mandatory phase prior to anti-virus scanning for identifying the known malware hidden behind packing layers. Existing techniques of unpacking solutions increase execution overhead of AV scanners in terms of time. This paper illustrates an easy to use approach which works in two phases to reduce this overhead. The first phase (ESCAPE) discriminates the packed code from the native code (non-packed) by using random block entropy. The second phase (PEAL) validates inferences of ESCAPE by employing bi-classification (packed vs native) model using relevant hex byte features extracted blockwise. The proposed approach is able to shrink the overall execution time of AV scanners by filtering out native samples and avoiding excessive unpacking overhead. Our method has been evaluated against a set consisting of real packed instances of malware and benign programs.

  5. Study of vibration packing characteristics with simulated fuel particles

    International Nuclear Information System (INIS)

    This report presents the results of vibration packing experiments and computational simulations of particle compaction behavior. Both sphere and shard particles were evaluated in these works. Experiments with simulated fuel particles were conducted to investigate the factors affecting packing behavior. The factors are classified into geometrical and dynamics factors. With regard to the geometrical factors for sphere packing, the experimental results proved that the achievable packing fraction can be predicted by the equation derived by Ayer, which is relationship of inner diameter of cladding and diameters of particles. As for the dynamics factors, less vibration displacement is preferable, because it produces faster packing with less segregation. Similar experiments were conducted for the shard particles. The results indicate the packing characteristics of the shard particles are different from those of the sphere particles. Optimum weight ratio between particle sizes is different from the ratio given by Ayer's equation. As for the dynamics factors, the sweeping frequencies while packing were sufficient to obtain high packing fraction. Computational simulations were performed to investigate the particle behavior during packing. The movement of infiltrating and bed particles during packing was well understood. (author)

  6. Water detritiation: better catalysts for liquid phase catalytic exchange

    International Nuclear Information System (INIS)

    Fusion reactors are our hope for a clean nuclear energy. But as they shall handle huge amounts of tritium, 1.5 1019 Bq GWth-1 a-1 or about 50 000 times more tritium than light water fission reactors, they need detritiation. Most tritium losses can be trapped as or can easily be transformed into tritiated water. Water detritiation is preferably based on the multiplication of the large equilibrium isotope effect during the exchange reaction of tritium between hydrogen gas and liquid water in a counter current trickle bed reactor. Such LPCE (Liquid Phase Catalytic Exchange) requires an efficient hydrophobic catalyst. SCK-CEN invented and developed such a catalyst in the past. In combination with an appropriate packing, different batches of this catalyst performed very well during years of extensive testing, allowing to develop the ELEX process for water detritiation at inland reprocessing plants. The main objectives of this study were to reproduce and possibly improve the SCK-CEN catalyst for tritium exchange between hydrogen and liquid water; and to demonstrate the high overall exchange rate and thus high detritiation factors that can be realized with it in a small and simple LPCE column under typical but conservative operating conditions

  7. Bifunctional Anode Catalysts for Direct Methanol Fuel Cells

    Energy Technology Data Exchange (ETDEWEB)

    Rossmeisl, Jan; Ferrin, Peter A.; Tritsaris, Georgios A.; Nilekar, Anand U.; Koh, Shirlaine; Bae, Sang Eun; Brankovic, Stanko R.; Strasser, Peter; Mavrikakis, Manos

    2012-06-13

    Using the binding energy of OH* and CO* on close-packed surfaces as reactivity descriptors, we screen bulk and surface alloy catalysts for methanol electro-oxidation activity. Using these two descriptors, we illustrate that a good methanol electro-oxidation catalyst must have three key properties: (1) the ability to activate methanol, (2) the ability to activate water, and (3) the ability to react off surface intermediates (such as CO* and OH*). Based on this analysis, an alloy catalyst made up of Cu and Pt should have a synergistic effect facilitating the activity towards methanol electro-oxidation. Using these two reactivity descriptors, a surface PtCu3 alloy is proposed to have the best catalytic properties of the Pt–Cu model catalysts tested, similar to those of a Pt–Ru bulk alloy. To validate the model, experiments on a Pt(111) surface modified with different amounts of Cu adatoms are performed. Adding Cu to a Pt(111) surface increases the methanol oxidation current by more than a factor of three, supporting our theoretical predictions for improved electrocatalysts.

  8. Catalysts for Environmental Remediation

    DEFF Research Database (Denmark)

    Abrams, B. L.; Vesborg, Peter Christian Kjærgaard

    2013-01-01

    The properties of catalysts used in environmental remediation are described here through specific examples in heterogeneous catalysis and photocatalysis. In the area of heterogeneous catalysis, selective catalytic reduction (SCR) of NOx was used as an example reaction with vanadia and tungsta on...

  9. Tight bifunctional hierarchical catalyst.

    Science.gov (United States)

    Højholt, Karen T; Vennestrøm, Peter N R; Tiruvalam, Ramchandra; Beato, Pablo

    2011-12-28

    A new concept to prepare tight bifunctional catalysts has been developed, by anchoring CoMo(6) clusters on hierarchical ZSM-5 zeolites for simultaneous use in HDS and hydrocracking catalysis. The prepared material displays a significant improved activity in HDS catalysis compared to the impregnated counterpart. PMID:22048337

  10. Hydrogen evolution reaction catalyst

    Science.gov (United States)

    Subbaraman, Ram; Stamenkovic, Vojislav; Markovic, Nenad; Tripkovic, Dusan

    2016-02-09

    Systems and methods for a hydrogen evolution reaction catalyst are provided. Electrode material includes a plurality of clusters. The electrode exhibits bifunctionality with respect to the hydrogen evolution reaction. The electrode with clusters exhibits improved performance with respect to the intrinsic material of the electrode absent the clusters.

  11. Ethylene Oligomerization and Polymerization: Alternative Iron Catalysts beyond 2,6-Bisiminopyridyl Iron Complexes

    Institute of Scientific and Technical Information of China (English)

    Suyun Jie; Shu Zhang; Wenjuan Zhang; Yingxia Song; Junxian Hou; Wen-Hua Sun

    2005-01-01

    @@ 1Introduction Polyolefin industry arrives the option to transfer from multiple-site systems of the classical Ziegler-Natta catalysts to more sophisticated single-site catalysts. The late-transition metal compounds were traditionally assumed with poor polymerization properties due to the highly competitive chain-termination step, and produced the short-chain oligomers up to 40 carbon atoms (SHOP catalysts). Recently the polyolefins employing latetransition metal complexes as catalysts became a hot research subject with the pioneering works by Brookhart and Gibson. It is promising for nickel catalysts to use solely ethylene as monomer for highly branched polyethylenes, and the designed nickel catalysts were not useful in industry. It is critical time to investigate the relationship of coordination modes of nickel complexes and its catalytic activities and the properties of resultant polyethylenes.

  12. Transport apparatus for location of shear pack in shear machine

    International Nuclear Information System (INIS)

    An apparatus for moving a shear pack of a shear machine between operative and inoperative position is described. It comprises a trolley to support the shear pack, the trolley being mounted on a bogie movable on rails between the inoperative position, at which the shear pack is loaded on to the trolley, and the operative position at which the shear pack is located at the shear machine. The trolley is mounted on inclined runners on the bogie and is releasably connected to the bogie by latching means. This permits the displacement of the trolley relative to the bogie to effect vertical displacement of the shear pack when the shear pack is at the shear machine. (author)

  13. Preparation of HZSM-5 membrane packed CuO–ZnO–Al2O3 nanoparticles for catalysing carbon dioxide hydrogenation to dimethyl ether

    International Nuclear Information System (INIS)

    Highlights: • CuO–ZnO–Al2O3 composite nanoparticles were successfully prepared using carbon sphere as template. • HZSM-5@CuO–ZnO–Al2O3 capsule catalyst was prepared hydrothermally. • Zeolite capsule catalysts exhibited an extremely good selectivity for DME compared with the conventional hybrid catalyst. - Abstract: Spherical carbons were prepared successfully from aqueous glucose using hydrothermal method. After covered with aqueous Cu2+, Zn2+ and Al3+ ions during the co-precipitation treatment, carbons were removed via calcination to yield CuO–ZnO–Al2O3 nanoparticles. HZSM-5 membrane, which was synthesized using tetrapropylammonium hydroxide as templating agent, was packed onto CuO–ZnO–Al2O3 nanoparticles hydrothermally to form HZSM-5 packed CuO–ZnO–Al2O3 nanoparticles. It was characterized by the method of X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen sorption measurement. HZSM-5 packed CuO–ZnO–Al2O3 nanoparticles were used as catalysts for the CO2 hydrogenation to dimethyl ether. The catalyst activity was investigated in a fixed-bed reactor. Under the reaction conditions of pressure at 3.0 MPa, space velocity (SV) of 1800 mL gcat−1 h−1, volume ratio of CO2/H2 to 1:3 and temperature at 270 °C, the conversion of CO2 could reach to 48.3%, with a dimethyl ether yield and selectivity of 23.4% and 48.5%, respectively

  14. Preparation of HZSM-5 membrane packed CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles for catalysing carbon dioxide hydrogenation to dimethyl ether

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rong; Tian, Haifeng; Yang, Aimei; Zha, Fei, E-mail: zhafei@nwnu.edu.cn; Ding, Jian; Chang, Yue

    2015-08-01

    Highlights: • CuO–ZnO–Al{sub 2}O{sub 3} composite nanoparticles were successfully prepared using carbon sphere as template. • HZSM-5@CuO–ZnO–Al{sub 2}O{sub 3} capsule catalyst was prepared hydrothermally. • Zeolite capsule catalysts exhibited an extremely good selectivity for DME compared with the conventional hybrid catalyst. - Abstract: Spherical carbons were prepared successfully from aqueous glucose using hydrothermal method. After covered with aqueous Cu{sup 2+}, Zn{sup 2+} and Al{sup 3+} ions during the co-precipitation treatment, carbons were removed via calcination to yield CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles. HZSM-5 membrane, which was synthesized using tetrapropylammonium hydroxide as templating agent, was packed onto CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles hydrothermally to form HZSM-5 packed CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles. It was characterized by the method of X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen sorption measurement. HZSM-5 packed CuO–ZnO–Al{sub 2}O{sub 3} nanoparticles were used as catalysts for the CO{sub 2} hydrogenation to dimethyl ether. The catalyst activity was investigated in a fixed-bed reactor. Under the reaction conditions of pressure at 3.0 MPa, space velocity (SV) of 1800 mL g{sub cat}{sup −1} h{sup −1}, volume ratio of CO{sub 2}/H{sub 2} to 1:3 and temperature at 270 °C, the conversion of CO{sub 2} could reach to 48.3%, with a dimethyl ether yield and selectivity of 23.4% and 48.5%, respectively.

  15. Statistical theory of correlations in random packings of hard particles

    OpenAIRE

    Jin, Yuliang; Puckett, James G.; Makse, Hernan A.

    2014-01-01

    A random packing of hard particles represents a fundamental model for granular matter. Despite its importance, analytical modeling of random packings remains difficult due to the existence of strong correlations which preclude the development of a simple theory. Here, we take inspiration from liquid theories for the $n$-particle angular correlation function to develop a formalism of random packings of hard particles from the bottom-up. A progressive expansion into a shell of particles converg...

  16. Contact nonlinearities and linear response in jammed particulate packings

    OpenAIRE

    Goodrich, Carl P.; Liu, Andrea J.; Nagel, Sidney R.

    2014-01-01

    Packings of frictionless athermal particles that interact only when they overlap experience a jamming transition as a function of packing density. Such packings provide the foundation for the theory of jamming. This theory rests on the observation that, despite the multitude of disordered configurations, the mechanical response to linear order depends only on the distance to the transition. We investigate the validity and utility of such measurements that invoke the harmonic approximation and...

  17. Low density gravel substitute gravel pack in Marlim

    Energy Technology Data Exchange (ETDEWEB)

    Albino, E.

    1996-12-31

    Successful gravel pack completion means optimization of production. This has been PETROBRAS` task regarding completion of the giant Marlim field. Significant improvement have been noticed recently with the introduction of techniques such as horizontal drilling, frac pack and low density gravel substitute gravel pack. This paper discusses the introduction and results of the system, its advantages and trends since this technique can become an excellent alternative when a more aggressive technique is no economical. (author). 5 refs., 4 figs.

  18. Human Error in Throat Pack Management: Report of Two Cases.

    Science.gov (United States)

    Baranger, Violaine; Bon Mardion, Nicolas; Dureuil, Bertrand; Compère, Vincent

    2016-06-15

    Throat packs are frequently used after tracheal intubation during ear, nose, and throat surgery. We report 2 cases of complications related to throat packs retained at the end of surgery. Miscommunication between anesthesiology and surgery teams on throat pack management led to an upper gastrointestinal endoscopy examination under general anesthesia in the first case and to severe respiratory distress requiring tracheal reintubation in the second case. Our 2 case reports highlight the importance of good communication between anesthesiology and surgery teams and of standardized procedures and checklists for the management of throat packs to ensure patient safety. PMID:27301056

  19. Voronoi tessellation of the packing of fine uniform spheres

    Science.gov (United States)

    Yang, R. Y.; Zou, R. P.; Yu, A. B.

    2002-04-01

    The packing of uniform fine spherical particles ranging from 1 to 1000 μm has been simulated by means of discrete particle simulation. The packing structure is analyzed, facilitated by the well established Voronoi tessellation. The topological and metric properties of Voronoi polyhedra are quantified as a function of particle size and packing density. The results show that as particle size or packing density decreases, (i) the average face number of Voronoi polyhedra decreases, and the distributions of face number and edge number become broader and more asymmetric; (ii) the average perimeter and area of polyhedra increase, and the distributions of polyhedron surface area and volume become more flat and can be described by the log-normal distribution. The topological and metric properties depicted for the packing of fine particles differ either quantitatively or qualitatively from those reported in the literature although they all can be related to packing density. In particular, our results show that the average sphericity coefficient of Voronoi polyhedra varies with packing density, and although Aboav-Weaire's law is generally applicable, Lewis's law is not valid when packing density is low, which are contrary to the previous findings for other packing systems.

  20. Continuous glycerolysis in an immobilized enzyme packed reactor for industrial monoacylglycerol production

    DEFF Research Database (Denmark)

    spite of optimal reaction conditions a complex heterogeneous reactant mixture with a glycerol in oil emulsion occurs. Hence, the movement of material from phase to phase as well as through the catalyst pores becomes important since it can influence the performance of the immobilized enzyme reactor. To...... examine which basic features that need to be considered to obtain an industrially beneficial procedure continuous and easily operated glycerolysis was studied in different lipase packed columns. Immobilized Candida antarctica lipase B was used to catalyze the glycerolysis reaction between glycerol and...... sunflower oil dissolved in a binary tert-butanol:tert-pentanol medium. Practical design-related issues such as required reaction time, enzyme capacity, expansion of the enzyme during wetting, and the effect of different column length-to-diameter ratios, fluid velocities and particle sizes of the enzymes...

  1. Bucking the pack ice to Prudhoe Bay

    Energy Technology Data Exchange (ETDEWEB)

    Kizzia, T.

    1976-05-01

    Forty-seven giant barges with a billion dollars worth of freight for the Alaska pipeline had been waiting since July 4, 1975 to proceed on through the ice to make the 300-mile run to Prudhoe Bay. Normally, easterly summer winds blow the pack ice into the Chukchi Sea where wave action breaks it up, leaving a broad highway of open water along Alaska's north coast, but the winds in 1975 failed to materialize. Ten of the barges had gone through during August and then a violent westerly storm swept in. When the storm was over, 22 barge skippers returned to Seward, and in mid-September 15 mammouth barges were ice bound. The Coast Guard was called out and with success the icebreakers and tugs began arriving with the cargo in Prudhoe Bay on September 30. The unloading of the cargo also brought difficulties, but before the cargo became frozen in, much of it was unloaded. (MCW)

  2. Meromorphic Vector Fields and Circle Packings

    DEFF Research Database (Denmark)

    Dias, Kealey

    The objective of the Ph.D. project is to initiate a classification of bifurcations of meromorphic vector fields and to clarify their relation to circle packings. Technological applications are to image analysis and to effective grid generation using discrete conformal mappings. The two branches of...... dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions or meromorphic (allowing poles as...... singularities) functions. There already exists a well-developed theory for iterative holomorphic dynamical systems, and successful relations found between iteration theory and flows of vector fields have been one of the main motivations for the recent interest in holomorphic vector fields. Restricting to...

  3. Narrow sieves for parameterized paths and packings

    CERN Document Server

    Björklund, Andreas; Kaski, Petteri; Koivisto, Mikko

    2010-01-01

    We present randomized algorithms for some well-studied, hard combinatorial problems: the k-path problem, the p-packing of q-sets problem, and the q-dimensional p-matching problem. Our algorithms solve these problems with high probability in time exponential only in the parameter (k, p, q) and using polynomial space; the constant bases of the exponentials are significantly smaller than in previous works. For example, for the k-path problem the improvement is from 2 to 1.66. We also show how to detect if a d-regular graph admits an edge coloring with $d$ colors in time within a polynomial factor of O(2^{(d-1)n/2}). Our techniques build upon and generalize some recently published ideas by I. Koutis (ICALP 2009), R. Williams (IPL 2009), and A. Bj\\"orklund (STACS 2010, FOCS 2010).

  4. Continuous catalyst free production of biodiesel from agro industrial waste with green solvents

    OpenAIRE

    Montoya, Carmen Alicia Moreno

    2012-01-01

    The aim of this thesis consists in the study of the production of biodiesel via catalyst free direct transesterification of spent coffee ground oil with supercritical methanol in a continuous process. Supercritical methanol is passed through a packed bed reactor with the spent coffee grounds. Inside the reactor supercritical methanol extracts the triacylglycerols, which are immediately transesterified into fatty acid methyl esters. Therefore, the extraction and transesterification proce...

  5. Obesity prevention and personal responsibility: the case of front-of-pack food labelling in Australia

    Directory of Open Access Journals (Sweden)

    Magnusson Roger S

    2010-11-01

    Full Text Available Abstract Background In Australia, the food industry and public health groups are locked in serious struggle for regulatory influence over the terms of front-of-pack food labelling. Clear, unambiguous labelling of the nutritional content of pre-packaged foods and of standardized food items sold in chain restaurants is consistent with the prevailing philosophy of 'personal responsibility'. An interpretive, front-of-pack labelling scheme has the capacity to encourage healthier patterns of eating, and to be a catalyst for improvements in the nutritional quality of food products through re-formulation. On the other hand, the strength of opposition of the Australian Food and Grocery Council to 'Traffic Light Labelling', and its efforts to promote a non-interpretive, voluntary scheme, invite the interpretation that the food industry is resistant to any reforms that could destabilise current (unhealthy purchasing patterns and the revenues they represent. Discussion This article argues that although policies that aim to educate consumers about the nutritional content of food are welcome, they are only one part of a broader basket of policies that are needed to make progress on obesity prevention and public health nutrition. However, to the extent that food labelling has the capacity to inform and empower consumers to make healthier choices - and to be a catalyst for improving the nutritional quality of commercial recipes - it has an important role to play. Furthermore, given the dietary impact of meals eaten in fast food and franchise restaurants, interpretive labelling requirements should not be restricted to pre-packaged foods. Summary Food industry resistance to an interpretive food labelling scheme is an important test for government, and a case study of how self-interest prompts industry to promote weaker, voluntary schemes that pre-empt and undermine progressive public health regulation.

  6. Regulation relative to the packing and packing wastes; Reglementation relative aux emballages et dechets d'emballages

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-08-01

    The objectives of the european directive 94/62/CE of the 20 december 1994, relative to the packing and the packing wastes, are the harmonization between the States members, the environment protection and a management of the internal market in agreement with the Treaty. This text recalls the regulations in the french domain. Industrial and municipal packings wastes are concerned. (A.L.B.)

  7. VOC removal by microwave, electron beam and catalyst technique

    International Nuclear Information System (INIS)

    A hybrid technique, developed for VOCs removal using microwave (MW) treatment, electron beam (EB) irradiation and catalyst method, is presented. Two hybrid laboratory installations, developed for the study of air pollution control by combined EB irradiation, MW irradiation and catalyst, are described. Air loaded with toluene was treated at different MW power levels, water content, flow rates, and different irradiation modes, separately and combined with MW and EB. Also, simultaneous EB and MW irradiation method was applied to SO2 and NOx removal. Real synergy effects between EB induced NTP, MW induced NTP and catalysis can be observed

  8. Self-diffusion of carbon dioxide in samaria/alumina aerogel catalyst using high field NMR diffusometry

    Science.gov (United States)

    Mueller, Robert; Zhang, Suihua; Neumann, Björn; Bäumer, Marcus; Vasenkov, Sergey

    2013-10-01

    Pulsed field gradient (PFG) NMR was used to investigate the self-diffusion of carbon dioxide in alumina stabilized samaria aerogel catalyst, a promising porous catalyst for gas-phase reactions featuring high porosity and high surface area. For diffusion studies, the catalyst was prepared in two sample packing types, macroscopic monoliths (i.e., macroscopic cylindrical particles) and powder beds with particle sizes around 200 μm that are considered for catalytic applications. Studies of diffusion in these samples revealed how macroscopic packing influences the catalyst transport properties. Application of a high magnetic field of 17.6 T in the reported PFG NMR studies enabled diffusion measurements for relatively low carbon dioxide densities in the catalyst samples corresponding to a gas loading pressure of around 0.1 atm. As a result, it was possible to perform diffusion measurements for a large range of carbon dioxide loading pressures between 0.1 and 10 atm. The measured carbon dioxide diffusivities in the beds of catalyst particles are interpreted in the context of a simple diffusion-mediated exchange model previously used for zeolites and other porous materials.

  9. Sound wave velocities in dry and lubricated granular packings packings: numerical simulations and experiments

    CERN Document Server

    Agnolin, Ivana; Massaad, Pascal; Jia, Xiaoping; Mills, Pierre

    2009-01-01

    Numerical simulations are used to investigate the origins of the different wave velocities measured in dense granular samples assembled with different methods. Glass bead packings are prepared in the lab either by pouring and vibrating the dry material in a container, or by mixing with a very small amount of a viscous lubricant. Lubricated samples, although less dense, exhibit significantly higher wave velocities for confining pressures in the 100 kPa range. Numerical predictions for elastic moduli agree much better with experimental results when the computational preparation of the samples mimics the laboratory one, albeit in a simplified manner. A plausible explanation to the laboratory observations is that the coordination number, which influences the material stiffness more than its density, is notably higher in lubricated packings.

  10. Experimental and modeling study of sulfur dioxide oxidation in packed-bed tubular reactor

    Directory of Open Access Journals (Sweden)

    Hanen NOURI

    2013-08-01

    Full Text Available The conversion of sulfur dioxide into sulfur trioxide is a reaction which interests not only the industry of sulfuric acid production but also the processes of pollution control of certain gas effluents containing SO2. This exothermic reaction needs a very good control of temperature, that's why it is led in the industry in a multistage converter with intermediate heat exchangers. Microreactors represent a good alternative for such reaction due to their intensification of mass and heat transfer and enhancement of temperature control. In this study, this reaction was conducted in a stainless steel tubular (4mm ID packed bed reactor using particles of vanadium pentoxide as catalyst at atmospheric pressure. Experiments were performed with different inlet SO2 concentration in 3-9% range and reaction temperature between 685-833K. We noticed that the conversion decreases with the amount of SO2 and increases with the temperature until an optimum, above this value the conversion drop according to the shape of the equilibrium curve. Controlling rate mechanism is studied by varying temperature. Pseudohomogeneous perfect plug flow is used to describe this small tubular reactor. Numerical simulations with MATLAB were performed to validate the experimental results. Good agreement between the model predictions and the experimental results is achieved. Fluid flow description inside the packed bed reactor was performed by using the free fluid and porous media flow model. This model was solved by the commercial software COMSOL Multiphysics. Velocity profile inside the reactor is theoretically obtained.

  11. Measured Black Carbon Deposition on the Sierra Nevada Snow Pack and Implication for Snow Pack Retreat

    Energy Technology Data Exchange (ETDEWEB)

    Hadley, O.L.; Corrigan, C.E.; Kirchstetter, T.W.; Cliff, S.S.; Ramanathan, V.

    2010-01-12

    Modeling studies show that the darkening of snow and ice by black carbon deposition is a major factor for the rapid disappearance of arctic sea ice, mountain glaciers and snow packs. This study provides one of the first direct measurements for the efficient removal of black carbon from the atmosphere by snow and its subsequent deposition to the snow packs of California. The early melting of the snow packs in the Sierras is one of the contributing factors to the severe water problems in California. BC concentrations in falling snow were measured at two mountain locations and in rain at a coastal site. All three stations reveal large BC concentrations in precipitation, ranging from 1.7 ng/g to 12.9 ng/g. The BC concentrations in the air after the snow fall were negligible suggesting an extremely efficient removal of BC by snow. The data suggest that below cloud scavenging, rather than ice nuclei, was the dominant source of BC in the snow. A five-year comparison of BC, dust, and total fine aerosol mass concentrations at multiple sites reveals that the measurements made at the sampling sites were representative of large scale deposition in the Sierra Nevada. The relative concentration of iron and calcium in the mountain aerosol indicates that one-quarter to one-third of the BC may have been transported from Asia.

  12. Solid-fluid response of packed-bed regenerators by Crump's numerical inversion of Laplace transforms

    International Nuclear Information System (INIS)

    The temperature histories in the fluid and the solid phases of a fixed-matrix (packed-bed) thermal storage unit in the regenerative mode of operation, with complete reversals of the flow direction, are traced. The heat conduction and energy storage are considered in the solid, but neglected in the fluid. The problem is solved numerically by the technique of Laplace transforms, with the inversion effected by a fast and robust scheme due to Crump. Sample results are plotted and discussed in physical terms

  13. Growth of Vanadium Carbide by Halide-Activated Pack Diffusion

    DEFF Research Database (Denmark)

    Fernandes, Frederico Augusto Pires; Christiansen, Thomas Lundin; Dahl, Kristian Vinter;

    The present work investigates growth of vanadium carbide (VC) layers by the pack diffusion method on a Vanadis 6 tool steel. The VC layers were produced by pack diffusion at 1000°C for 1, 4 and 16 hours. The VC layers were characterized with optical and electron microscopy, Vickers hardness tests...

  14. 76 FR 251 - Country of Origin Labeling of Packed Honey

    Science.gov (United States)

    2011-01-04

    ... Service 7 CFR Part 52 RIN 0581-AC89 Country of Origin Labeling of Packed Honey AGENCY: Agricultural..., establishing new regulations addressing country of origin labeling for packed honey bearing any official USDA... service for honey if country of origin labeling requirements are not met for packages of honey...

  15. A selection-quotient process for packed word Hopf algebra

    CERN Document Server

    Duchamp, G H E; Tanasa, A

    2013-01-01

    In this paper, we define a Hopf algebra structure on the vector space spanned by packed words using a selection-quotient coproduct. We show that this algebra is free on its irreducible packed words. Finally, we give some brief explanations on the Maple codes we have used.

  16. 21 CFR 890.5730 - Moist heat pack.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Moist heat pack. 890.5730 Section 890.5730 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Therapeutic Devices § 890.5730 Moist heat pack....

  17. 27 CFR 24.255 - Bottling or packing wine.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Bottling or packing wine. 24.255 Section 24.255 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY LIQUORS WINE Storage, Treatment and Finishing of Wine Bottling, Packing, and Labeling of Wine § 24.255 Bottling...

  18. On spanning tree packings of highly edge connected graphs

    OpenAIRE

    Lehner, Florian

    2011-01-01

    We prove a refinement of the tree packing theorem by Tutte/Nash-Williams for finite graphs. This result is used to obtain a similar result for end faithful spanning tree packings in certain infinite graphs and consequently to establish a sufficient Hamiltonicity condition for the line graphs of such graphs.

  19. Online Variable-Sized Bin Packing with Conflicts

    DEFF Research Database (Denmark)

    Epstein, Leah; Favrholdt, Lene Monrad; Levin, Asaf

    2011-01-01

    We study a new kind of on-line bin packing with conflicts, motivated by a problem arising when scheduling jobs on the Grid. In this bin packing problem, the set of items is given at the beginning, together with a set of conflicts on pairs of items. A conflict on a pair of items implies that they...

  20. 48 CFR 852.214-73 - Alternate packaging and packing.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Alternate packaging and....214-73 Alternate packaging and packing. As prescribed in 814.201-6(b)(3), insert the following provision: Alternate Packaging and Packing (JAN 2008) The bidder's offer must clearly indicate the...

  1. 48 CFR 552.211-75 - Preservation, Packaging and Packing.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 4 2010-10-01 2010-10-01 false Preservation, Packaging....211-75 Preservation, Packaging and Packing. As prescribed in 511.204(b)(2), insert the following clause: Preservation, Packaging, and Packing (FEB 1996) Unless otherwise specified, all items shall...

  2. Dense Packings of Polyhedra: Platonic and Archimedean Solids

    CERN Document Server

    Torquato, S

    2009-01-01

    We formulate the problem of generating dense packings of nonoverlapping, non-tiling polyhedra within an adaptive fundamental cell subject to periodic boundary conditions as an optimization problem, which we call the Adaptive Shrinking Cell (ASC) scheme. This novel optimization problem is solved here (using a variety of multi-particle initial configurations) to find the dense packings of each of the Platonic solids in three-dimensional Euclidean space R3 , except for the cube, which is the only Platonic solid that tiles space. We find the densest known packings of tetrahedra, icosahedra, dodecahedra, and octahedra with densities 0:823:::, 0:836:::, 0:904:::, and 0:947:::, respectively. It is noteworthy that the densest tetrahedral packing possesses no long-range order. Unlike the densest tetrahedral packing, which must not be a Bravais lattice packing, the densest packings of the other non-tiling Platonic solids that we obtain are their previously known optimal (Bravais) lattice packings. We also derive a simp...

  3. Tandem isomerization-decarboxylation of unsaturated fatty acids to olefins via ruthenium metal-as-ligand catalysts

    Science.gov (United States)

    A new facile Ru-catalyzed route to bio-olefins3 from unsaturated fatty acids via readily accessible metal-as-ligand type catalyst precursors, [Ru(CO)2RCO2]n and Ru3(CO)12, will be described. The catalyst apparently functions in a tandem mode by dynamically isomerizing the positions of double bonds i...

  4. A fungal biofilm reactor based on metal structured packing improves the quality of a Gla::GFP fusion protein produced by Aspergillus oryzae.

    Science.gov (United States)

    Zune, Q; Delepierre, A; Gofflot, S; Bauwens, J; Twizere, J C; Punt, P J; Francis, F; Toye, D; Bawin, T; Delvigne, F

    2015-08-01

    Fungal biofilm is known to promote the excretion of secondary metabolites in accordance with solid-state-related physiological mechanisms. This work is based on the comparative analysis of classical submerged fermentation with a fungal biofilm reactor for the production of a Gla::green fluorescent protein (GFP) fusion protein by Aspergillus oryzae. The biofilm reactor comprises a metal structured packing allowing the attachment of the fungal biomass. Since the production of the target protein is under the control of the promoter glaB, specifically induced in solid-state fermentation, the biofilm mode of culture is expected to enhance the global productivity. Although production of the target protein was enhanced by using the biofilm mode of culture, we also found that fusion protein production is also significant when the submerged mode of culture is used. This result is related to high shear stress leading to biomass autolysis and leakage of intracellular fusion protein into the extracellular medium. Moreover, 2-D gel electrophoresis highlights the preservation of fusion protein integrity produced in biofilm conditions. Two fungal biofilm reactor designs were then investigated further, i.e. with full immersion of the packing or with medium recirculation on the packing, and the scale-up potentialities were evaluated. In this context, it has been shown that full immersion of the metal packing in the liquid medium during cultivation allows for a uniform colonization of the packing by the fungal biomass and leads to a better quality of the fusion protein. PMID:25935344

  5. The effect of nanoparticle packing on capacitive electrode performance

    Science.gov (United States)

    Lee, Younghee; Noh, Seonmyeong; Kim, Min-Sik; Kong, Hye Jeong; Im, Kyungun; Kwon, Oh Seok; Kim, Sungmin; Yoon, Hyeonseok

    2016-06-01

    Nanoparticles pack together to form macro-scale electrodes in various types of devices, and thus, optimization of the nanoparticle packing is a prerequisite for the realization of a desirable device performance. In this work, we provide in-depth insight into the effect of nanoparticle packing on the performance of nanoparticle-based electrodes by combining experimental and computational findings. As a model system, polypyrrole nanospheres of three different diameters were used to construct pseudocapacitive electrodes, and the performance of the electrodes was examined at various nanosphere diameter ratios and mixed weight fractions. Two numerical algorithms are proposed to simulate the random packing of the nanospheres on the electrode. The binary nanospheres exhibited diverse, complicated packing behaviors compared with the monophasic packing of each nanosphere species. The packing of the two nanosphere species with lower diameter ratios at an optimized composition could lead to more dense packing of the nanospheres, which in turn could contribute to better device performance. The dense packing of the nanospheres would provide more efficient transport pathways for ions because of the reduced inter-nanosphere pore size and enlarged surface area for charge storage. Ultimately, it is anticipated that our approach can be widely used to define the concept of ``the best nanoparticle packing'' for desirable device performance.Nanoparticles pack together to form macro-scale electrodes in various types of devices, and thus, optimization of the nanoparticle packing is a prerequisite for the realization of a desirable device performance. In this work, we provide in-depth insight into the effect of nanoparticle packing on the performance of nanoparticle-based electrodes by combining experimental and computational findings. As a model system, polypyrrole nanospheres of three different diameters were used to construct pseudocapacitive electrodes, and the performance of the

  6. Statistical theory of correlations in random packings of hard particles.

    Science.gov (United States)

    Jin, Yuliang; Puckett, James G; Makse, Hernán A

    2014-05-01

    A random packing of hard particles represents a fundamental model for granular matter. Despite its importance, analytical modeling of random packings remains difficult due to the existence of strong correlations which preclude the development of a simple theory. Here, we take inspiration from liquid theories for the n-particle angular correlation function to develop a formalism of random packings of hard particles from the bottom up. A progressive expansion into a shell of particles converges in the large layer limit under a Kirkwood-like approximation of higher-order correlations. We apply the formalism to hard disks and predict the density of two-dimensional random close packing (RCP), ϕ(rcp) = 0.85 ± 0.01, and random loose packing (RLP), ϕ(rlp) = 0.67 ± 0.01. Our theory also predicts a phase diagram and angular correlation functions that are in good agreement with experimental and numerical data. PMID:25353787

  7. Simulation and control of water-gas shift packed bed reactor with inter-stage cooling

    Science.gov (United States)

    Saw, S. Z.; Nandong, J.

    2016-03-01

    Water-Gas Shift Reaction (WGSR) has become one of the well-known pathways for H2 production in industries. The issue with WGSR is that it is kinetically favored at high temperatures but thermodynamically favored at low temperatures, thus requiring careful consideration in the control design in order to ensure that the temperature used does not deactivate the catalyst. This paper studies the effect of a reactor arrangement with an inter-stage cooling implemented in the packed bed reactor to look at its effect on outlet temperature. A mathematical model is developed based on one-dimensional heat and mass transfers which incorporate the intra-particle effects. It is shown that the placement of the inter-stage cooling and the outlet temperature exiting the inter-stage cooling have strong influence on the reaction conversion. Several control strategies are explored for the process. It is shown that a feedback- feedforward control strategy using Multi-scale Control (MSC) is effective to regulate the reactor temperature profile which is critical to maintaining the catalysts activity.

  8. Chromate reduction by Arthrobacter CR47 in biofilm packed bed reactors

    International Nuclear Information System (INIS)

    Bacterial strain Cr47 was isolated from a landfarming process soil sample. It was identified, by 16s rDNA sequencing, as Arthrobacter sp. The time course of the Cr(VI) reduction was monitored in batch operated packed bed biofilm reactors (12mL void volume) and in recirculating packed bed biofilm reactors (100 mL void volume) inoculated with bacterial strain Cr47. The reduction was evaluated with, 30 mg L-1 Cr(VI) laboratory solutions prepared with K2Cr2O7 and enriched with glucose-minimal medium, and with 30 mg L-1 Cr(VI) industrial model solutions prepared with chrome plating waste waters enriched with sucrose-minimal medium. Under batch mode the reduction reaction by the biofilm seemed to fit well an exponential-decay model with a first order kinetic parameter of 0.071 mg(L h)-1 Cr(VI). In the recirculating reactor, monitored after 4 weeks from inoculation and fed with laboratory solutions the removal rate was 0.79 mg(L h)-1. In the reactor fed with the industrial model solutions the maximum Cr(VI) removal rate attained was 0.49 mg(L h)-1. Artrobacter sp. packed bed biofilm reactors achieved Cr(VI) reduction rates comparable to other aerobic and anaerobic fixed film bioreactors previously reported

  9. Oxygen-reducing catalyst layer

    Science.gov (United States)

    O'Brien, Dennis P.; Schmoeckel, Alison K.; Vernstrom, George D.; Atanasoski, Radoslav; Wood, Thomas E.; Yang, Ruizhi; Easton, E. Bradley; Dahn, Jeffrey R.; O'Neill, David G.

    2011-03-22

    An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

  10. Development of GREET Catalyst Module

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhichao [Argonne National Lab. (ANL), Argonne, IL (United States); Benavides, Pahola T. [Argonne National Lab. (ANL), Argonne, IL (United States); Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States); Cronauer, Donald C. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-01

    In this report, we develop energy and material flows for the production of five different catalysts (tar reforming, alcohol synthesis, Zeolite Socony Mobil-5 [ZSM-5], Mo/Co/ γ-Al2O3, and Pt/ γ-Al2O3) and two chemicals (olivine, dimethyl ether of polyethylene glycol [DEPG]). These compounds and catalysts are now included in the Greenhouse Gases, Regulated Emissions and Energy Use in Transportation (GREET™) catalyst module.

  11. Privileged chiral ligands and catalysts

    CERN Document Server

    Zhou, Qi-Lin

    2011-01-01

    This ultimate ""must have"" and long awaited reference for every chemist working in the field of asymmetric catalysis starts with the core structure of the catalysts, explaining why a certain ligand or catalyst is so successful. It describes in detail the history, the basic structural characteristics, and the applications of these ""privileged catalysts"". A novel concept that gives readers a much deeper insight into the topic.

  12. SEPTOPLASTY WITH AND WITHOUT NASAL PACKING: A COMPARATIVE STUDY

    Directory of Open Access Journals (Sweden)

    Mitta

    2016-05-01

    Full Text Available Septoplasty is one of the most commonly performed surgeries in rhinology to relieve nasal obstruction of patients with distortion in the midline cartilage or septum of the nose to relieve nasal obstruction of patient and findings consistent with nasal endoscopy. The anterior nasal packing routinely done following septoplasty is usually conventional and not evidence based. The purpose of nasal packing is to obtain haemostasis, enhance opposition of septal flaps, avoid septal haematoma formation, close the dead space, avoid synechiae formation, provide support to septal cartilage and prevent its displacement. OBJECTIVE This study intends to evaluate the effects of nasal packing on surgical success and related complications in septoplasty. MATERIALS AND METHODS The present clinical prospective and randomised study was carried out on patients attending Otorhinolaryngology Department of Santhiram Medical College & General Hospital between March 2012 and March 2015. Patients undergoing septoplasty were randomised either to receive anterior nasal packing or to not receive nasal packing postoperatively. RESULTS Levels of pain experienced by patients with nasal packing postoperatively during the initial 24 hours postoperatively and during the removal of the pack were significantly more. Post-operative headache, epiphora, swallowing discomfort and sleep disturbance were more in patients with nasal packing and statistically (p.05. Septal haematoma, adhesions and local infections in both groups were statistically insignificant (p>.05. CONCLUSION Septoplasty enhances the standard of living of patients with septal deviation and nasal obstruction. Our study results suggest that nasal packing after septoplasty is not obligatory. Nasal packing causes considerably more pain and complications, and it should be reserved only for those who have bleeding predisposition.

  13. Packing regularities in biological structures relate to their dynamics.

    Science.gov (United States)

    Jernigan, Robert L; Kloczkowski, Andrzej

    2007-01-01

    The high packing density inside proteins leads to certain geometric regularities and also is one of the most important contributors to the high extent of cooperativity manifested by proteins in their cohesive domain motions. The orientations between neighboring nonbonded residues in proteins substantially follow the similar geometric regularities, regardless of whether the residues are on the surface or buried, a direct result of hydrophobicity forces. These orientations are relatively fixed and correspond closely to small deformations from those of the face-centered cubic lattice, which is the way in which identical spheres pack at the highest density. Packing density also is related to the extent of conservation of residues, and we show this relationship for residue packing densities by averaging over a large sample or residue packings. There are three regimes: (1) over a broad range of packing densities the relationship between sequence entropy and inverse packing density is nearly linear, (2) over a limited range of low packing densities the sequence entropy is nearly constant, and (3) at extremely low packing densities the sequence entropy is highly variable. These packing results provide important justification for the simple elastic network models that have been shown for a large number of proteins to represent protein dynamics so successfully, even when the models are extremely coarse grained. Elastic network models for polymeric chains are simple and could be combined with these protein elastic networks to represent partially denatured parts of proteins. Finally, we show results of applications of the elastic network model to study the functional motions of the ribosome, based on its known structure. These results indicate expected correlations among its components for the step-wise processing steps in protein synthesis, and suggest ways to use these elastic network models to develop more detailed mechanisms, an important possibility because most

  14. Failure Modes

    DEFF Research Database (Denmark)

    Jakobsen, K. P.; Burcharth, H. F.; Ibsen, Lars Bo; Sørensen, John Dalsgaard

    1999-01-01

    The present appendix contains the derivation of ten different limit state equations divided on three different failure modes. Five of the limit state equations can be used independently of the characteristics of the subsoil, whereas the remaining five can be used for either drained or undrained s...

  15. Reuse of Hydrotreating Spent Catalyst

    International Nuclear Information System (INIS)

    All hydro treating catalysts used in petroleum refining processes gradually lose activity through coking, poisoning by metal, sulfur or halides or lose surface area from sintering at high process temperatures. Waste hydrotreating catalyst, which have been used in re-refining of waste lube oil at Alexandria Petroleum Company (after 5 years lifetime) compared with the same fresh catalyst were used in the present work. Studies are conducted on partial extraction of the active metals of spent catalyst (Mo and Ni) using three leaching solvents,4% oxidized oxalic acid, 10% aqueous sodium hydroxide and 10% citric acid. The leaching experiments are conducting on the de coked extrude [un crushed] spent catalyst samples. These steps are carried out in order to rejuvenate the spent catalyst to be reused in other reactions. The results indicated that 4% oxidized oxalic acid leaching solution gave total metal removal 45.6 for de coked catalyst samples while NaOH gave 35% and citric acid gave 31.9 % The oxidized leaching agent was the most efficient leaching solvent to facilitate the metal removal, and the rejuvenated catalyst was characterized by the unchanged crystalline phase The rejuvenated catalyst was applied for hydrodesulfurization (HDS) of vacuum gas oil as a feedstock, under different hydrogen pressure 20-80 bar in order to compare its HDS activity

  16. Hydrodewaxing with mixed zeolite catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Chester, A.W.; McHale, W.D.; Yen, J.H.

    1986-03-11

    A process is described for catalytically dewaxing a hydrocarbon lubricating oil feedstock comprising contacting the feedstock with a dewaxing catalyst, the dewaxing catalyst comprising, in combination: (a) a zeolite catalyst having a Constraint Index not less than 1, (b) an acidic catalytic material selected from the group consisting of Mordenite, TEA Mordenite, Dealuminized Y, Ultrastable Y, Rare Earth Y, amorphous silica-alumina chlorinated alumina, ZSM-4 and ZSM-20, and (c) a hydrogenation component, and recovering a dewaxed product. A process is also described for catalytically dewaxing a hydrocarbon lubricating oil feedstock comprising contacting the feedstock with a dewaxing catalyst, the dewaxing catalyst comprising, in combinations: (a) a first zeolite catalyst selected from the group consisting of ZSM-5, ZMS-11, ZSM-12, ZSM-22, ZSM-23, ZSM-34, ZSM-35, ZSM-38, ZSM-48, TMA Offretite and Erionite, (b) a second catalyst selected from the group consisting of ZSM-12, ZSM-22, ZSM-38 and ZSM-48, the second zeolite catalyst being different from the first zeolite catalyst, and (c) a hydrogenation component, and recovering a dewaxed product.

  17. Geometry of Online Packing Linear Programs

    CERN Document Server

    Molinaro, Marco

    2012-01-01

    We consider packing LP's with $m$ rows where all constraint coefficients are normalized to be in the unit interval. The n columns arrive in random order and the goal is to set the corresponding decision variables irrevocably when they arrive so as to obtain a feasible solution maximizing the expected reward. Previous (1 - \\epsilon)-competitive algorithms require the right-hand side of the LP to be Omega((m/\\epsilon^2) log (n/\\epsilon)), a bound that worsens with the number of columns and rows. However, the dependence on the number of columns is not required in the single-row case and known lower bounds for the general case are also independent of n. Our goal is to understand whether the dependence on n is required in the multi-row case, making it fundamentally harder than the single-row version. We refute this by exhibiting an algorithm which is (1 - \\epsilon)-competitive as long as the right-hand sides are Omega((m^2/\\epsilon^2) log (m/\\epsilon)). Our techniques refine previous PAC-learning based approaches ...

  18. Experimental study of simultaneous Athabasca bitumen recovery and upgrading using ultradispersed catalysts injection

    Energy Technology Data Exchange (ETDEWEB)

    Hashemi, R.; Pereira, P. [University of Calgary (Canada)

    2011-07-01

    As the demand for oil is continuously increasing, the need for unconventional resources is rising. Oil extraction from bitumen and heavy oil reservoirs requires advanced techniques in order to decrease the viscosity of the oil. To increase the recovered original oil in place (OOIP) of a reservoir and decrease refining costs, new techniques to upgrade oil in situ are being developed. The current study investigates the use of ultra-dispersed (UD) submicronic catalysts to decrease oil viscosity. The experiment involved the injection of the catalyst and hydrogen gas in a sand pack saturated with Athabasca bitumen. Analysis was carried out by building recovery curves, and by comparing the oil recovery from the catalyzed process with that of catalyst-free processes. The study demonstrated that the oil recovered from the new technique had higher API gravity and lower viscosity, indicating the success of the in situ upgrading process.

  19. DEHYDROGENATION CATALYST FOR PRODUCTION OF MTBE

    Science.gov (United States)

    The objectives of this project were to better understand the effect of different catalyst preparation parameters, the effect of different catalyst treatment parameters, and the mechanism of deactivation. Accordingly, catalysts were made using various preparation methods and with...

  20. Deactivation-resistant catalyst for selective catalyst reduction of NOx

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to a catalyst for selective catalytic reduction of NOx in alkali metal containing flue gas using ammonia as reductant, the catalyst comprising a surface with catalytically active sites, wherein the surface is at least partly coated with a coating comprising at least...

  1. Novel Reforming Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Pfefferle, Lisa D; Haller, Gary L

    2012-10-16

    Aqueous phase reforming is useful for processing oxygenated hydrocarbons to hydrogen and other more useful products. Current processing is hampered by the fact that oxide based catalysts are not stable under high temperature hydrothermal conditions. Silica in the form of structured MCM-41 is thermally a more stable support for Co and Ni than conventional high surface area amorphous silica but hydrothermal stability is not demonstrated. Carbon nanotube supports, in contrast, are highly stable under hydrothermal reaction conditions. In this project we show that carbon nanotubes are stable high activity/selectivity supports for the conversion of ethylene glycol to hydrogen.

  2. Optimization of operating parameters for gas-phase photocatalytic splitting of H2S by novel vermiculate packed tubular reactor.

    Science.gov (United States)

    Preethi, V; Kanmani, S

    2016-10-01

    Hydrogen production by gas-phase photocatalytic splitting of Hydrogen Sulphide (H2S) was investigated on four semiconductor photocatalysts including CuGa1.6Fe0.4O2, ZnFe2O3, (CdS + ZnS)/Fe2O3 and Ce/TiO2. The CdS and ZnS coated core shell particles (CdS + ZnS)/Fe2O3 shows the highest rate of hydrogen (H2) production under optimized conditions. Packed bed tubular reactor was used to study the performance of prepared photocatalysts. Selection of the best packing material is a key for maximum removal efficiency. Cheap, lightweight and easily adsorbing vermiculate materials were used as a novel packing material and were found to be effective in splitting H2S. Effect of various operating parameters like flow rate, sulphide concentration, catalyst dosage, light irradiation were tested and optimized for maximum H2 conversion of 92% from industrial waste H2S. PMID:27562700

  3. Do gray wolves (Canis lupus) support pack mates during aggressive inter-pack interactions?

    Science.gov (United States)

    Cassidy, Kira A; McIntyre, Richard T

    2016-09-01

    For group-living mammals, social coordination increases success in everything from hunting and foraging (Crofoot and Wrangham in Mind the Gap, Springer, Berlin, 2010; Bailey et al. in Behav Ecol Sociobiol 67:1-17, 2013) to agonism (Mosser and Packer in Anim Behav 78:359-370, 2009; Wilson et al. in Anim Behav 83:277-291, 2012; Cassidy et al. in Behav Ecol 26:1352-1360, 2015). Cooperation is found in many species and, due to its low costs, likely is a determining factor in the evolution of living in social groups (Smith in Anim Behav 92:291-304, 2014). Beyond cooperation, many mammals perform costly behaviors for the benefit of group mates (e.g., parental care, food sharing, grooming). Altruism is considered the most extreme case of cooperation where the altruist increases the fitness of the recipient while decreasing its own fitness (Bell in Selection: the mechanism of evolution. Oxford University Press, Oxford 2008). Gray wolf life history requires intra-pack familiarity, communication, and cooperation in order to succeed in hunting (MacNulty et al. in Behav Ecol doi: 10.1093/beheco/arr159 2011) and protecting group resources (Stahler et al. in J Anim Ecol 82: 222-234, 2013; Cassidy et al. in Behav Ecol 26:1352-1360, 2015). Here, we report 121 territorial aggressive inter-pack interactions in Yellowstone National Park between 1 April 1995 and 1 April 2011 (>5300 days of observation) and examine each interaction where one wolf interferes when its pack mate is being attacked by a rival group. This behavior was recorded six times (17.6 % of interactions involving an attack) and often occurred between dyads of closely related individuals. We discuss this behavior as it relates to the evolution of cooperation, sociality, and altruism. PMID:27193460

  4. Effect of structured packing density on performance of air dehumidifier

    International Nuclear Information System (INIS)

    An experimental study has been conducted to investigate the performance of a liquid desiccant air dehumidifier equipped with a structured packing made of wood for three different densities using triethylene glycol (TEG) as the liquid desiccant. The structured packing densities used were 77, 100 and 200 m2/m3. The performance of the dehumidifier was expressed in terms of the moisture removal rate and the dehumidifier effectiveness under different air and desiccant parameters, i.e. the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. In general, the trend in the dehumidifier performance was similar to that reported by other investigators using random packing. The effect of packing density on moisture removal rate and dehumidifier effectiveness is assessed. The differences in the effectiveness of different packing densities are attributed to the wetting condition. Lower effectiveness of the column is shown with the packing density of 200 m2/m3 compared to the other two packing densities when the air flow rate, inlet concentration and desiccant flow rate are increased. However, higher effectiveness is shown when either the inlet temperature of the air or desiccant is increased

  5. Effect of structured packing density on performance of air dehumidifier

    Energy Technology Data Exchange (ETDEWEB)

    Abdul-Wahab, S.A. E-mail: sabah1@squ.edu.om; Abu-Arabi, M.K.; Zurigat, Y.H

    2004-09-01

    An experimental study has been conducted to investigate the performance of a liquid desiccant air dehumidifier equipped with a structured packing made of wood for three different densities using triethylene glycol (TEG) as the liquid desiccant. The structured packing densities used were 77, 100 and 200 m{sup 2}/m{sup 3}. The performance of the dehumidifier was expressed in terms of the moisture removal rate and the dehumidifier effectiveness under different air and desiccant parameters, i.e. the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. In general, the trend in the dehumidifier performance was similar to that reported by other investigators using random packing. The effect of packing density on moisture removal rate and dehumidifier effectiveness is assessed. The differences in the effectiveness of different packing densities are attributed to the wetting condition. Lower effectiveness of the column is shown with the packing density of 200 m{sup 2}/m{sup 3} compared to the other two packing densities when the air flow rate, inlet concentration and desiccant flow rate are increased. However, higher effectiveness is shown when either the inlet temperature of the air or desiccant is increased.

  6. Air dehumidification by triethylene glycol desiccant in a packed column

    International Nuclear Information System (INIS)

    The performance of an air dehumidifier using triethylene glycol (TEG) as desiccant under hot and humid conditions was investigated. The performance of the dehumidifier was evaluated and expressed in terms of the moisture removal rate and the dehumidifier effectiveness. A packed bed column (dehumidifier) was employed, with low packing density (77 m2/m3), to provide direct contact between the air and the TEG. Two different structured packings were used, wood and aluminum. The experiments covered a wide range of parameter space that included the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. The liquid flow rate investigated is much less than that covered in previous studies (2 s). The trend of the dehumidifier performance was similar to that reported in the literature using high density and random packing. The results were compared to the Chung and Luo correlation, which over predicted the effectiveness. The Martin and Goswami correlation failed to predict the effectiveness under the conditions of this study. In the present study, it was found that the moisture removal rate increased with increasing inlet TEG concentration, TEG flow rate and air flow rate. This was seen for both the wood and the aluminum packings. In addition, the moisture removal rate is increased with increasing the inlet air temperature for the aluminum packing only. The effectiveness of the column was increased by increasing the TEG flow rate and inlet TEG temperature for the two packings

  7. Air dehumidification by triethylene glycol desiccant in a packed column

    Energy Technology Data Exchange (ETDEWEB)

    Zurigat, Y.H.; Abu-Arabi, M.K.; Abdul-Wahab, S.A. E-mail: sabah1@squ.edu.om

    2004-01-01

    The performance of an air dehumidifier using triethylene glycol (TEG) as desiccant under hot and humid conditions was investigated. The performance of the dehumidifier was evaluated and expressed in terms of the moisture removal rate and the dehumidifier effectiveness. A packed bed column (dehumidifier) was employed, with low packing density (77 m{sup 2}/m{sup 3}), to provide direct contact between the air and the TEG. Two different structured packings were used, wood and aluminum. The experiments covered a wide range of parameter space that included the air and TEG flow rates, air and TEG inlet temperatures, inlet air humidity and inlet TEG concentration. The liquid flow rate investigated is much less than that covered in previous studies (<1 kg/m{sup 2} s). The trend of the dehumidifier performance was similar to that reported in the literature using high density and random packing. The results were compared to the Chung and Luo correlation, which over predicted the effectiveness. The Martin and Goswami correlation failed to predict the effectiveness under the conditions of this study. In the present study, it was found that the moisture removal rate increased with increasing inlet TEG concentration, TEG flow rate and air flow rate. This was seen for both the wood and the aluminum packings. In addition, the moisture removal rate is increased with increasing the inlet air temperature for the aluminum packing only. The effectiveness of the column was increased by increasing the TEG flow rate and inlet TEG temperature for the two packings.

  8. PackBot: a versatile platform for military robotics

    Science.gov (United States)

    Yamauchi, Brian M.

    2004-09-01

    The iRobot PackBot is a combat-tested, man-portable UGV that has been deployed in Afghanistan and Iraq. The PackBot is also a versatile platform for mobile robotics research and development that supports a wide range of payloads suitable for many different mission types. In this paper, we describe four R&D projects that developed experimental payloads and software using the PackBot platform. CHARS was a rapid development project to develop a chemical/radiation sensor for the PackBot. We developed the CHARS payload in six weeks and deployed it to Iraq to search for chemical and nuclear weapons. Griffon was a research project to develop a flying PackBot that combined the capabilities of a UGV and a UAV. We developed a Griffon prototype equipped with a steerable parafoil and gasoline-powered motor, and we completed successful flight tests including remote-controlled launch, ascent, cruising, descent, and landing. Valkyrie is an ongoing research and development project to develop a PackBot payload that will assist medics in retrieving casualties from the battlefield. Wayfarer is an applied research project to develop autonomous urban navigation capabilities for the PackBot using laser, stereo vision, GPS, and INS sensors.

  9. In-situ characterization of heterogeneous catalysts

    CERN Document Server

    Rodriguez, Jose A; Chupas, Peter J

    2013-01-01

    Helps researchers develop new catalysts for sustainable fuel and chemical production Reviewing the latest developments in the field, this book explores the in-situ characterization of heterogeneous catalysts, enabling readers to take full advantage of the sophisticated techniques used to study heterogeneous catalysts and reaction mechanisms. In using these techniques, readers can learn to improve the selectivity and the performance of catalysts and how to prepare catalysts as efficiently as possible, with minimum waste. In-situ Characterization of Heterogeneous Catalysts feat

  10. Enabling Microliquid Chromatography by Microbead Packing of Microchannels

    Science.gov (United States)

    Balvin, Manuel; Zheng, Yun

    2014-01-01

    The microbead packing is the critical element required in the success of on-chip microfabrication of critical microfluidic components for in-situ analysis and detection of chiral amino acids. In order for microliquid chromatography to occur, there must be a stationary phase medium within the microchannel that interacts with the analytes present within flowing fluid. The stationary phase media are the microbeads packed by the process discussed in this work. The purpose of the microliquid chromatography is to provide a lightweight, low-volume, and low-power element to separate amino acids and their chiral partners efficiently to understand better the origin of life. In order to densely pack microbeads into the microchannels, a liquid slurry of microbeads was created. Microbeads were extracted from a commercially available high-performance liquid chromatography column. The silica beads extracted were 5 microns in diameter, and had surface coating of phenyl-hexyl. These microbeads were mixed with a 200- proof ethanol solution to create a microbead slurry with the right viscosity for packing. A microfilter is placed at the outlet via of the microchannel and the slurry is injected, then withdrawn across a filter using modified syringes. After each injection, the channel is flushed with ethanol to enhance packing. This cycle is repeated numerous times to allow for a tightly packed channel of microbeads. Typical microbead packing occurs in the macroscale into tubes or channels by using highly pressurized systems. Moreover, these channels are typically long and straight without any turns or curves. On the other hand, this method of microbead packing is completed within a microchannel 75 micrometers in diameter. Moreover, the microbead packing is completed into a serpentine type microchannel, such that it maximizes microchannel length within a microchip. Doing so enhances the interactions of the analytes with the microbeads to separate efficiently amino acids and amino acid

  11. Localized breathing modes in granular crystals with defects

    OpenAIRE

    Theocharis, G.; Kavousanakis, M; Kevrekidis, P. G.; Daraio, Chiara; Porter, Mason A.; Kevrekidis, I. G.

    2009-01-01

    We study localized modes in uniform one-dimensional chains of tightly packed and uniaxially compressed elastic beads in the presence of one or two light-mass impurities. For chains composed of beads of the same type, the intrinsic nonlinearity, which is caused by the Hertzian interaction of the beads, appears not to support localized, breathing modes. Consequently, the inclusion of light-mass impurities is crucial for their appearance. By analyzing the problem’s linear limit, we identify the ...

  12. Theory of paramagnetic singlet-doublet excitations in double-hexagonal close-packed praseodymium

    International Nuclear Information System (INIS)

    The magnetic excitation spectrum of the singlet-doublet magnet double-hexagonal close-packed praseodymium, which has been measured by means of inelastic neutron scattering, is analyzed using a diagrammatic high-density expansion technique. The lowest-order random-phase-approximation diagrams give a detailed description of the wave-vector and temperature dependence of the four modes in terms of a Hamiltonian including isotropic Heisenberg interatomic exchange interactions and anisotropic, dipolar-like exchange interactions. In general, the modes are linearly or elliptically polarized. The leading contributions to the line shapes of the excitations are obtained by extending the 1/Z expansion of the generalized susceptibility propagators one order beyond the random-phase approximation. This damping corresponds to spin-wave scattering on single-site fluctuations. The propagators are calculated self-consistently by including internally renormalized Green's functions. The theoretical spectral functions are in detailed agreement with experiment

  13. Multi-dimensional Bin Packing Problems with Guillotine Constraints

    DEFF Research Database (Denmark)

    Amossen, Rasmus Resen; Pisinger, David

    2010-01-01

    The problem addressed in this paper is the decision problem of determining if a set of multi-dimensional rectangular boxes can be orthogonally packed into a rectangular bin while satisfying the requirement that the packing should be guillotine cuttable. That is, there should exist a series of face...... parallel straight cuts that can recursively cut the bin into pieces so that each piece contains a box and no box has been intersected by a cut. The unrestricted problem is known to be NP-hard. In this paper we present a generalization of a constructive algorithm for the multi-dimensional bin packing...

  14. The Use of Inorganic Packing Materials during Methane Biofiltration

    OpenAIRE

    Josiane Nikiema; Michèle Heitz

    2010-01-01

    The objective behind this study is to select a suitable inorganic packing material for methane biofiltration. Three packing materials are to be compared: two rock materials (average particles' sizes: 2 and 5 mm) and one porous clay particles (average particle size of 7 mm). The main parameter used to assess the efficiency of the packing material is the methane elimination capacity. The study reveals that the rock material having an average particle size around 2 mm is to be preferred. This re...

  15. UNIFORM PACKING DIMENSION RESULTS FOR MULTIPARAMETER STABLE PROCESSES

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In this article, authors discuss the problem of uniform packing dimension of the image set of multiparameter stochastic processes without random uniform H(o)lder condition, and obtain the uniform packing dimension of multiparameter stable processes.If Z is a stable (N, d, α)-process and αN ≤ d, then the following holds with probability 1 Dim Z(E) = α DimE for any Borel setE ∈ B(R+N),where Z(E) = {x: (E) t ∈ E, Z(t) = x}. Dim(E) denotes the packing dimension of E.

  16. Intelligent charging and control of portable battery packs

    OpenAIRE

    Kjellberg, Olof

    2008-01-01

    This report describes thesis work performed at SAAB Aerotech in Link oping, Sweden. The task was to nd a way to have portable electronics' battery packs supervise their own charg- ing i.e. designing a charger that would t inside the battery pack itself. The work was started by identifying the demands that SAAB Aerotech and their customer have on portable bat- tery packs. A survey was done, forming the basis of a design specication that species what an implementation should aim at fullling. Th...

  17. Multilayer DNA Origami Packed on Hexagonal and Hybrid Lattices

    DEFF Research Database (Denmark)

    Ke, Yonggang; Voigt, Niels Vinther; Shih, William M.; Gothelf, Kurt Vesterager

    2012-01-01

    “Scaffolded DNA origami” has been proven to be a powerful and efficient approach to construct two-dimensional or three-dimensional objects with great complexity. Multilayer DNA origami has been demonstrated with helices packing along either honeycomb-lattice geometry or square-lattice geometry....... Here we report successful folding of multilayer DNA origami with helices arranged on a close-packed hexagonal lattice. This arrangement yields a higher density of helical packing and therefore higher resolution of spatial addressing than has been shown previously. We also demonstrate hybrid multilayer...

  18. Packing parameters effect on injection molding of polypropylene nanostructured surfaces

    DEFF Research Database (Denmark)

    Calaon, Matteo; Tosello, Guido; Hansen, Hans Nørgaard;

    2012-01-01

    In today´s industry, applications involving surface patterning of sub-μm to nanometer scale structures have shown a high growth potential. To investigate the injection molding capability of replicating sub-μm surface texture on a large scale area, a 30x80 mm2 tool insert with surface structures...... having a diameter of 500 nm was employed. The tool insert surface was produced using chemical-based-batch techniques such aluminum anodization and nickel electroplating. During the injection molding process, polypropylene (PP) was employed as material and packing phase parameters (packing time, packing...

  19. Contact nonlinearities and linear response in jammed particulate packings.

    Science.gov (United States)

    Goodrich, Carl P; Liu, Andrea J; Nagel, Sidney R

    2014-08-01

    Packings of frictionless athermal particles that interact only when they overlap experience a jamming transition as a function of packing density. Such packings provide the foundation for the theory of jamming. This theory rests on the observation that, despite the multitude of disordered configurations, the mechanical response to linear order depends only on the distance to the transition. We investigate the validity and utility of such measurements that invoke the harmonic approximation and show that, despite particles coming in and out of contact, there is a well-defined linear regime in the thermodynamic limit. PMID:25215727

  20. Startup procedure for reforming catalysts

    Energy Technology Data Exchange (ETDEWEB)

    McHale, W.D.; Schoennagel, H.J.

    1984-08-14

    Process for reforming a hydrocarbon charge under reforming conditions in a reforming zone containing a sulfur-sensitive metal containing reforming catalyst wherein over-cracking of the charge stock and excessive temperature rise in the reforming zone is suppressed by pre-conditioning the catalyst, prior to contact with the charge, with a reformate of specified octane number and aromatics content.

  1. Doped palladium containing oxidation catalysts

    Science.gov (United States)

    Mohajeri, Nahid

    2014-02-18

    A supported oxidation catalyst includes a support having a metal oxide or metal salt, and mixed metal particles thereon. The mixed metal particles include first particles including a palladium compound, and second particles including a precious metal group (PMG) metal or PMG metal compound, wherein the PMG metal is not palladium. The oxidation catalyst may also be used as a gas sensor.

  2. Catalysts for low temperature oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Toops, Todd J.; Parks, III, James E.; Bauer, John C.

    2016-03-01

    The invention provides a composite catalyst containing a first component and a second component. The first component contains nanosized gold particles. The second component contains nanosized platinum group metals. The composite catalyst is useful for catalyzing the oxidation of carbon monoxide, hydrocarbons, oxides of nitrogen, and other pollutants at low temperatures.

  3. Catalyst design for biorefining.

    Science.gov (United States)

    Wilson, Karen; Lee, Adam F

    2016-02-28

    The quest for sustainable resources to meet the demands of a rapidly rising global population while mitigating the risks of rising CO2 emissions and associated climate change, represents a grand challenge for humanity. Biomass offers the most readily implemented and low-cost solution for sustainable transportation fuels, and the only non-petroleum route to organic molecules for the manufacture of bulk, fine and speciality chemicals and polymers. To be considered truly sustainable, biomass must be derived from resources which do not compete with agricultural land use for food production, or compromise the environment (e.g. via deforestation). Potential feedstocks include waste lignocellulosic or oil-based materials derived from plant or aquatic sources, with the so-called biorefinery concept offering the co-production of biofuels, platform chemicals and energy; analogous to today's petroleum refineries which deliver both high-volume/low-value (e.g. fuels and commodity chemicals) and low-volume/high-value (e.g. fine/speciality chemicals) products, thereby maximizing biomass valorization. This article addresses the challenges to catalytic biomass processing and highlights recent successes in the rational design of heterogeneous catalysts facilitated by advances in nanotechnology and the synthesis of templated porous materials, as well as the use of tailored catalyst surfaces to generate bifunctional solid acid/base materials or tune hydrophobicity. PMID:26755755

  4. Latent catalyst; Senzaisei shokubai

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    Epoxy resin, an important function material to support such main industries as electric and electronic devices, automobiles, civil engineering, and building construction, is demanded of development of single liquid type resin having excellent quick hardening performance and storage stability. This requirement comes from environmental problems with an intention of saving energies and reducing resin wastes. The Company, using freely its independent phase separation technology that controls molecular structure of catalysts, developed a latent catalyst having excellent storage stability and high-temperature quick hardening performance. Its major features may be summarized as follows: (1) excellent storage stability at room temperature keeping the product stable for 2.5 months or longer (2 days in conventional products); (2) quick hardening performance hardening the resin in seven seconds at 150 degrees C (equivalent to conventional products); and (3) excellent insulation performance of hardened resin at 140 degrees C of 7 times 10 {sup 13} (ohm) (center dot) cm (2 times 10 {sup 12} (ohm) (center dot) cm in conventional products) (translated by NEDO)

  5. Replacement of the cooling tower packing at the Goesgen-Daeniken AG nuclear power plant

    International Nuclear Information System (INIS)

    In 2005 the asbestos cement cooling tower packing was replaced by plastic material. Two years later, the packing showed strong deformations, deposits of solids and weight gain. At the end of 2007 parts of the packing collapsed into the cooling tower basin. Investigations were made, revealing that the thickness of the packing foil was too low and that packing geometry and biofilms on the surface of the packing favoured deposition of solids. Successful measures were taken to solve the problems. (orig.)

  6. Effect of Packing Cost on The Sales Price and Contribution Margin

    OpenAIRE

    Gülşah ATAĞAN; Yükçü, Süleyman

    2013-01-01

    The basic characteristic of packing is to protect the product from external factors while the product is delivering to consumers. However, recently packing has become an indispensable aspect of marketing. Because, packing is considered as a silent dealer which directly reaches consumers. Packing is one of the most important factor of product sales. Consumers assess a product with its packing and make up a purchasing decision accordingly. In addition to its protective function, packing also p...

  7. Supported molten-metal catalysts

    Science.gov (United States)

    Datta, Ravindra; Singh, Ajeet; Halasz, Istvan; Serban, Manuela

    2001-01-01

    An entirely new class of catalysts called supported molten-metal catalysts, SMMC, which can replace some of the existing precious metal catalysts used in the production of fuels, commodity chemicals, and fine chemicals, as well as in combating pollution. SMMC are based on supporting ultra-thin films or micro-droplets of the relatively low-melting (<600.degree. C.), inexpensive, and abundant metals and semimetals from groups 1, 12, 13, 14, 15 and 16, of the periodic table, or their alloys and intermetallic compounds, on porous refractory supports, much like supported microcrystallites of the traditional solid metal catalysts. It thus provides orders of magnitude higher surface area than is obtainable in conventional reactors containing molten metals in pool form and also avoids corrosion. These have so far been the chief stumbling blocks in the application of molten metal catalysts.

  8. Preparation of HZSM-5 membrane packed CuO-ZnO-Al2O3 nanoparticles for catalysing carbon dioxide hydrogenation to dimethyl ether

    Science.gov (United States)

    Liu, Rong; Tian, Haifeng; Yang, Aimei; Zha, Fei; Ding, Jian; Chang, Yue

    2015-08-01

    Spherical carbons were prepared successfully from aqueous glucose using hydrothermal method. After covered with aqueous Cu2+, Zn2+ and Al3+ ions during the co-precipitation treatment, carbons were removed via calcination to yield CuO-ZnO-Al2O3 nanoparticles. HZSM-5 membrane, which was synthesized using tetrapropylammonium hydroxide as templating agent, was packed onto CuO-ZnO-Al2O3 nanoparticles hydrothermally to form HZSM-5 packed CuO-ZnO-Al2O3 nanoparticles. It was characterized by the method of X-ray powder diffraction (XRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and nitrogen sorption measurement. HZSM-5 packed CuO-ZnO-Al2O3 nanoparticles were used as catalysts for the CO2 hydrogenation to dimethyl ether. The catalyst activity was investigated in a fixed-bed reactor. Under the reaction conditions of pressure at 3.0 MPa, space velocity (SV) of 1800 mL gcat-1 h-1, volume ratio of CO2/H2 to 1:3 and temperature at 270 °C, the conversion of CO2 could reach to 48.3%, with a dimethyl ether yield and selectivity of 23.4% and 48.5%, respectively.

  9. The monolithic lawn-like CuO-based nanorods array used for diesel soot combustion under gravitational contact mode.

    Science.gov (United States)

    Yu, Yifu; Meng, Ming; Dai, Fangfang

    2013-02-01

    A simple and feasible contact mode called gravitational contact mode (GCM) was developed for the first time to imitate the practical state between soot and catalyst. By simulating rainwater adsorption on a lawn in nature, we synthesized a lawn-like CuO nanorods array, which exhibited rather good catalytic activity for diesel soot combustion under GCM. Moreover, the CuO nanorods array could serve as a support for composite catalysts through a sequential chemical bath deposition method and exhibited higher catalytic activity than a traditional supported catalyst. The monolithic macroscopic structure of such a catalyst shows its potential for large-scale preparation and application. PMID:23254389

  10. NO_x-assisted soot oxidation over K/CuCe catalyst

    Institute of Scientific and Technical Information of China (English)

    翁端; 李佳; 吴晓东; 司知蠢

    2010-01-01

    CeO2 and CuOx-CeO2 supported potassium catalysts were synthesized by wetness impregnation method. The catalysts were characterized by BET, NO-TPO, NOx-TPD and soot-TPO measurements. By the decoration of potassium and copper, the maximum soot combustion temperature of the ceria-based catalyst decreased to 338 and 379 °C in the presence and absence of NO under a loose contact mode, re- spectively. The pronouncedly enhanced NO oxidation ability by copper introduction and NOx storage capacity by potassium modif...

  11. Modethema Mode

    Directory of Open Access Journals (Sweden)

    Julia Bertschik

    2001-07-01

    Full Text Available Das Themenheft „Mode/Kunst – Fashion/Art“ der Zeitschrift figurationen versammelt heterogene Beiträge, die die Beziehung zwischen Kleidermode und Kunst von der Renaissance bis in die Gegenwart unter literaturwissenschaftlichem Schwerpunkt untersuchen. Reflexionen internationaler Künstler/-innen, Autorinnen und Autoren über die modischen Inszenierungsweisen des Körpers werden dabei auf ihre Darstellung der Geschlechter ebenso überprüft wie auf ihre ästhetische Stellung innerhalb des künstlerischen Gesamtwerks oder des zeitspezifischen Kanons.

  12. Preparation and characterization of hexagonal close-packed Ni nanoparticles

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Hexagonal close-packed Ni nanoparticles were synthesized using a heat-treating technique with the precursors prepared by the sol-gel method.The synthesis condition,structure,and morphology of the samples were characterized and analysed by thermogravimetric analysis (TG),differential thermal analysis (DTA),X-ray diffraction (XRD) and transmission electron microscopy (TEM).Results indicate that the hexagonal close packed Ni nanoparticles were synthesized at a heat-treating temperature of 300℃.The cell constants are calculated at a=0.2652 nm and c=0.4334 nm.The average grain size of the hexagonal close-packed Ni particles evaluated by Scherrer equation is about 12 nm.The phase transformation from a hexagonal close-packed Ni to a face-centered cubic Ni structure occurred when the heat-treating temperature was increased.

  13. Radiation sterilization of plastic packing materials and aseptic packaging

    International Nuclear Information System (INIS)

    In the present day of 'satiation', quality, not quantity, is emphasized for foods, the consumers being oriented toward raw and healthy foodstuff. Aseptic Packaging is excellent means of conservation. While conventionally chemicals have been used for sterilization of packing materials for aseptic packaging, the sterilization by radiation is used in part recently. The following are described : history of aseptic packaging and its features, sterilization by radiation, γ-ray sterilization of large-sized containers, the development of an aseptic packaging system using electron rays, the occurrence of offensive odors from packing materials (comparison of odors from various materials, volatile substances occurring in irradiated polyethylene, influence of film grade upon the formation of carboxylic acid, influence of the irradiation conditions upon the occurrences of volatile substances, volatile substances occurring in the irradiation of bag-in-box packing materials), changes in properties of the packing materials. (Mori, K.)

  14. Estimation of maximum coated particle fuel compact packing fraction

    International Nuclear Information System (INIS)

    This work develops an analytic fuel fraction packing model for a high temperature gas cooled reactor fuel compact fabricated from overcoated particles of a single size. The model includes the effects of one dimensional compression and finite matrix grain size. One dimensional compression limits the maximum fuel packing fraction to about 48% for the pressed compact in this single sized particle system. This limit is due to two effects. The first is that the process of die loading limits the pre-compression packing configuration to one that is stable under gravity, which is not the most space efficient one. The second effect is due to the one dimensional compression which reduces only the axial dimension of the particle lattice rather than uniformly compressing the lattice. The die wall can also limit the maximum packing fraction by preventing the nearby particles from moving into a more space efficient configuration

  15. Structural Evolution of a Granular Pack under Manual Tapping

    Science.gov (United States)

    Iikawa, Naoki; Bandi, Mahesh M.; Katsuragi, Hiroaki

    2015-09-01

    We experimentally study a two-dimensional (2D) granular pack of photoelastic disks subject to vertical manual tapping. Using bright- and dark-field images, we employ gradient-based image analysis methods to analyze various structural quantities. These include the packing fraction (ϕ), force per disk (Fd), and force chain segment length (l) as functions of the tapping number (τ). The increase in the packing fraction with the tapping number is found to exponentially approach an asymptotic value. An exponential distribution is observed for the cumulative numbers of both the force per disk Fd:Ncum(Fd) = AFexp ( - Fd/F0), and the force chain segment length l:Ncum(l) = Alexp ( - l/l0). Whereas the coefficient AF varies with τ for Fd, l shows no dependence on τ. The τ dependences of Fd and ϕ allow us to posit a linear relationship between the total force of the granular pack Ftot*(τ ) and ϕ(τ).

  16. Excise Tax Rates On Packs Of Cigarettes PDF Slides

    Data.gov (United States)

    U.S. Department of Health & Human Services — Download the current excise tax rates on packs of cigarettes slides. These slides are available in PDF and PowerPoint formats. The PowerPoint version can be found...

  17. Integrating packing and distribution problems and optimization through mathematical programming

    OpenAIRE

    Fabio Miguel; Mariano Frutos; Fernando Tohmé; Máximo Méndez

    2016-01-01

    This paper analyzes the integration of two combinatorial problems that frequently arise in production and distribution systems. One is the Bin Packing Problem (BPP) problem, which involves finding an ordering of some objects of different volumes to be packed into the minimal number of containers of the same or different size. An optimal solution to this NP-Hard problem can be approximated by means of meta-heuristic methods. On the other hand, we consider the Capacitated Vehicle Routing Proble...

  18. Damped Arrow-Hurwicz algorithm for sphere packing

    OpenAIRE

    Degond, Pierre; Ferreira, Marina A.; Motsch, Sébastien

    2016-01-01

    We consider algorithms that, from an arbitrarily sampling of $N$ spheres (possibly overlapping), find a close packed configuration without overlapping. These problems can be formulated as minimization problems with non-convex constraints. For such packing problems, we observe that the classical iterative Arrow-Hurwicz algorithm does not converge. We derive a novel algorithm from a multi-step variant of the Arrow-Hurwicz scheme with damping. We compare this algorithm with classical algorithms ...

  19. A SAT Encoding for Multi-dimensional Packing Problems

    Science.gov (United States)

    Grandcolas, Stéphane; Pinto, Cédric

    The Orthogonal Packing Problem (OPP) consists in determining if a set of items can be packed into a given container. This decision problem is NP-complete. Fekete et al. modelled the problem in which the overlaps between the objects in each dimension are represented by interval graphs. In this paper we propose a SAT encoding of Fekete et al. characterization. Some results are presented, and the efficiency of this approach is compared with other SAT encodings.

  20. Random close packing fractions of lognormal distributions of hard spheres

    OpenAIRE

    Farr, Robert S.

    2013-01-01

    We apply a recent one-dimensional algorithm for predicting random close packing fractions of polydisperse hard spheres [Farr and Groot, J. Chem. Phys. 133, 244104 (2009)] to the case of lognormal distributions of sphere sizes and mixtures of such populations. We show that the results compare well to two much slower algorithms for directly simulating spheres in three dimensions, and show that the algorithm is fast enough to tackle inverse problems in particle packing: designing size distributi...

  1. Computational Fluid Dynamics Simulation of Multiphase Flow in Structured Packings

    OpenAIRE

    Saeed Shojaee; Seyyed Hossein Hosseini; Behzad Saeedi Razavi

    2012-01-01

    A volume of fluid multiphase flow model was used to investigate the effective area and the created liquid film in the structured packings. The computational results revealed that the gas and liquid flow rates play significant roles in the effective interfacial area of the packing. In particular, the effective area increases as the flow rates of both phases increase. Numerical results were compared with the Brunazzi and SRP models, and a good agreement between them was found. Attention was gi...

  2. Preparation of Zirconia Based Packing Material and Its Evaluation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new reversed-phase packing (C18-PBD-ZrO2) was prepared by depositing and cross-linking 1-octadecene (ODE or C18) and polybutadiene (PBD) onto the surface of porous zirconia microspheres (5~10 mm in diameter) which were synthesized by a sol-gel process. These novel column packings possess high mechanical and chemical stability,wider usable pH range and can be used to separate basic compounds with no observable peak tailing.

  3. Shock-Induced Flows through Packed Beds: Transient Regimes

    CERN Document Server

    Shtemler, Yuri M; Britan, Alex

    2006-01-01

    The early stage of the transient regimes in the shock-induced flows within solid-packed beds are investigated in the linear longwave and high-frequency approximation. The transient resistance law is refined as the Duhameltime integral that follows from the general concept of dynamic tortuosity and compressibility of the packed beds. A closed-form solution is expected to describe accurately the early stage of the transient regime flow and is in qualitative agreement with available experimental data.

  4. Online Stochastic Packing Applied to Display Ad Allocation

    OpenAIRE

    Feldman, Jon; Henzinger, Monika; Korula, Nitish; Mirrokni, Vahab S.; Stein, Cliff

    2010-01-01

    Inspired by online ad allocation, we study online stochastic packing linear programs from theoretical and practical standpoints. We first present a near-optimal online algorithm for a general class of packing linear programs which model various online resource allocation problems including online variants of routing, ad allocations, generalized assignment, and combinatorial auctions. As our main theoretical result, we prove that a simple primal-dual training-based algorithm achieves a (1 - o(...

  5. Upper threshold for stability of multipole-mode solitons in nonlocal nonlinear media

    OpenAIRE

    Xu, Zhiyong; Kartashov, Yaroslav V.; Torner, Lluis

    2005-01-01

    We address the stability of multipole-mode solitons in nonlocal Kerr-type nonlinear media. Such solitons comprise several out-of-phase peaks packed together by the forces acting between them. We discover that dipole-, triple-, and quadrupole-mode solitons can be made stable, whereas all higher-order soliton bound states are unstable.

  6. Automating the packing heuristic design process with genetic programming.

    Science.gov (United States)

    Burke, Edmund K; Hyde, Matthew R; Kendall, Graham; Woodward, John

    2012-01-01

    The literature shows that one-, two-, and three-dimensional bin packing and knapsack packing are difficult problems in operational research. Many techniques, including exact, heuristic, and metaheuristic approaches, have been investigated to solve these problems and it is often not clear which method to use when presented with a new instance. This paper presents an approach which is motivated by the goal of building computer systems which can design heuristic methods. The overall aim is to explore the possibilities for automating the heuristic design process. We present a genetic programming system to automatically generate a good quality heuristic for each instance. It is not necessary to change the methodology depending on the problem type (one-, two-, or three-dimensional knapsack and bin packing problems), and it therefore has a level of generality unmatched by other systems in the literature. We carry out an extensive suite of experiments and compare with the best human designed heuristics in the literature. Note that our heuristic design methodology uses the same parameters for all the experiments. The contribution of this paper is to present a more general packing methodology than those currently available, and to show that, by using this methodology, it is possible for a computer system to design heuristics which are competitive with the human designed heuristics from the literature. This represents the first packing algorithm in the literature able to claim human competitive results in such a wide variety of packing domains. PMID:21609273

  7. Spectral action models of gravity on packed swiss cheese cosmology

    Science.gov (United States)

    Ball, Adam; Marcolli, Matilde

    2016-06-01

    We present a model of (modified) gravity on spacetimes with fractal structure based on packing of spheres, which are (Euclidean) variants of the packed swiss cheese cosmology models. As the action functional for gravity we consider the spectral action of noncommutative geometry, and we compute its expansion on a space obtained as an Apollonian packing of three-dimensional spheres inside a four-dimensional ball. Using information from the zeta function of the Dirac operator of the spectral triple, we compute the leading terms in the asymptotic expansion of the spectral action. They consist of a zeta regularization of the divergent sum of the leading terms of the spectral actions of the individual spheres in the packing. This accounts for the contribution of points 1 and 3 in the dimension spectrum (as in the case of a 3-sphere). There is an additional term coming from the residue at the additional point in the real dimension spectrum that corresponds to the packing constant, as well as a series of fluctuations coming from log-periodic oscillations, created by the points of the dimension spectrum that are off the real line. These terms detect the fractality of the residue set of the sphere packing. We show that the presence of fractality influences the shape of the slow-roll potential for inflation, obtained from the spectral action. We also discuss the effect of truncating the fractal structure at a certain scale related to the energy scale in the spectral action.

  8. Flow boiling heat transfer in volumetrically heated packed bed

    International Nuclear Information System (INIS)

    Highlights: • The onset of nucleate boiling in the volumetrically heated packed bed is researched. • A correlation for predicting qONB is developed. • The effects on boiling heat transfer coefficient are investigated. - Abstract: The volumetrically heated packed bed has been widely utilized in modern industry. However, due to the variability and randomness of packed bed channels, flow boiling heat transfer characteristics becomes complex, and there are no published research regarding this topic. To study flow boiling heat transfer characteristics of volumetrically heated packed beds, electromagnetic induction heating method is used to heat oxidized carbon steel balls adopted to stack the packed bed, with water as coolant in the experiment. The experimental results indicate that heat flux at onset of nucleate boiling (ONB) increases as mass flux and inlet subcooling are increased. A new correlation is developed to predict the ONB heat flux qONB in volumetrically heated packed bed, the predictions by which agree well with the experimental data, and the deviation remains less than 15%. Subcooled flow boiling heat transfer coefficient (hsub) increases with increasing mass flux, and equilibrium quality is slightly affected by heat flux. The saturated flow boiling heat transfer coefficient (hsat) increases with mass flux and equilibrium quality when equilibrium quality is lower than about 0.05, while the nucleate boiling is suppressed when the equilibrium quality exceeds a certain value

  9. CALCULATION OF TECHNOLOGICAL PARAMETERS OF OUT-PIPE REAGENT CIRCULAR IRRIGATION OF GRAVEL-PACKED FILTERS OF WATER SUPPLY WELLS

    Directory of Open Access Journals (Sweden)

    V. V. Ivashechkin

    2015-02-01

    Full Text Available The purpose of this work is the study of decolmatation rate of granular layer of gravel pack of well during creating inside of it flushing of reagent with given hydrodynamic parameters and determination the duration of treatment. This article deals with radical movement of chemical solutions by injection of it outside of gravel pack of filter when the flow directs to borehole axis under conditions of quasi-steady-state mode of filtration for equal yield of input and output reagent from borehole.Colmataged layer of gravel pack is schematized in the form of porous ring cylinder with outside radius which is equal to radius of line of gravel pack and the height which is equal to the length of filter made in formation drilling and inside radius which is equal to radius of filter. Initial saturation of subsoil with colmatant is given. It was accepted that reagent with given rate flows through outside surface of ring cylinder equal along all height. Near-filtering zone is given uniform and movement is quasi-steady-state.Equations’ system is composed including: joint equation of movement and mass conservation and generalized equation of kinetics, which describes kinetics of colmatant dissolution in the regime of out-pipe watering of ring gravel pack of well taking into account the change of structure of porous medium. The analytic solution of equations’ system was obtained, which allow to calculate salt content in reagent during the leaching process and to determine the specific volume of deposits in the point of gravel pack at any moment of time in the process of regent injection. The analytic dependence was obtained for calculation of duration of complete regeneration of soil grains’ layer of outer contour of gravel packing. For calculation of duration of full regeneration of the whole thickness of packing it is suggested to divide the regeneration period into a series of stages of salt transferring from subsoil. Duration of one stage is equal

  10. Ceramic catalyst materials

    Energy Technology Data Exchange (ETDEWEB)

    Sault, A.G.; Gardner, T.J. [Sandia National Laboratories, Albuquerque, NM (United States); Hanprasopwattanna, A.; Reardon, J.; Datye, A.K. [Univ. of New Mexico, Albuquerque, NM (United States)

    1995-08-01

    Hydrous titanium oxide (HTO) ion-exchange materials show great potential as ceramic catalyst supports due to an inherently high ion-exchange capacity which allows facile loading of catalytically active transition metal ions, and an ability to be cast as thin films on virtually any substrate. By coating titania and HTO materials onto inexpensive, high surface area substrates such as silica and alumina, the economics of using these materials is greatly improved, particularly for the HTO materials, which are substantially more expensive in the bulk form than other oxide supports. In addition, the development of thin film forms of these materials allows the catalytic and mechanical properties of the final catalyst formulation to be separately engineered. In order to fully realize the potential of thin film forms of titania and HTO, improved methods for the deposition and characterization of titania and HTO films on high surface area substrates are being developed. By varying deposition procedures, titania film thickness and substrate coverage can be varied from the submonolayer range to multilayer thicknesses on both silica and alumina. HTO films can also be formed, but the quality and reproducibility of these films is not nearly as good as for pure titania films. The films are characterized using a combination of isopropanol dehydration rate measurements, point of zero charge (PZC) measurements, BET surface area, transmission electron microscopy (TEM), and elemental analysis. In order to assess the effects of changes in film morphology on catalytic activity, the films are being loaded with MoO{sub 3} using either incipient wetness impregnation or ion-exchange of heptamolybdate anions followed by calcining. The MoO{sub 3} is then sulfided to form MOS{sub 2}, and tested for catalytic activity using pyrene hydrogenation and dibenzothiophene (DBT) desulfurization, model reactions that simulate reactions occurring during coal liquefaction.

  11. Packing schemes of cavities in selected clathrasils and zeolites and the analogous packings of atoms in crystal structures

    DEFF Research Database (Denmark)

    Hem, Caroline Piper; Makovicky, Emil; Balic Zunic, Tonci

    2010-01-01

    ] cages, associated with other cavity types. The packing of cavities in melanophlogite is analogous to the packing of atoms in the structure of Cr3Si, where the Cr atoms form icosahedra around the Si sites. Dodecasil 3C has a cubic arrangement of [512] cavities, which is described as ABC stacking of...... kagome nets and its cavity packing is an analog to the packing scheme of atoms in the cubic Laves phase MgCu2. Dodecasil 1H has an arrangement of [512] cavities in an AA stacking of kagome nets and is analogous to the alloy structure type CaZn5. Edingtonite and natrolite are built from two types of...

  12. Magnetically Recoverable Ruthenium Catalysts in Organic Synthesis

    OpenAIRE

    Dong Wang; Didier Astruc

    2014-01-01

    Magnetically recyclable catalysts with magnetic nanoparticles (MNPs) are becoming a major trend towards sustainable catalysts. In this area, recyclable supported ruthenium complexes and ruthenium nanoparticles occupy a key place and present great advantages compared to classic catalysts. In this micro-review, attention is focused on the fabrication of MNP-supported ruthenium catalysts and their catalytic applications in various organic syntheses.

  13. Impeded solid state reactions and transformations in ceramic catalysts supports and catalysts

    Directory of Open Access Journals (Sweden)

    Ernő E. Kiss

    2012-12-01

    Full Text Available Impeded chemical reactions and impeded polymorphous transformation in materials are discussed, as desired effects, for stabilization of ceramic catalyst supports and ceramic based catalysts. This paper gives a short overview about the possibilities of slowing down the aging processes in ceramic catalyst supports and catalysts. Special attention is given to alumina and titania based catalysts.

  14. Generation of Random Particle Packings for Discrete Element Models

    Science.gov (United States)

    Abe, S.; Weatherley, D.; Ayton, T.

    2012-04-01

    An important step in the setup process of Discrete Element Model (DEM) simulations is the generation of a suitable particle packing. There are quite a number of properties such a granular material specimen should ideally have, such as high coordination number, isotropy, the ability to fill arbitrary bounding volumes and the absence of locked-in stresses. An algorithm which is able to produce specimens fulfilling these requirements is the insertion based sphere packing algorithm originally proposed by Place and Mora, 2001 [2] and extended in this work. The algorithm works in two stages. First a number of "seed" spheres are inserted into the bounding volume. In the second stage the gaps between the "seed" spheres are filled by inserting new spheres in a way so they have D+1 (i.e. 3 in 2D, 4 in 3D) touching contacts with either other spheres or the boundaries of the enclosing volume. Here we present an implementation of the algorithm and a systematic statistical analysis of the generated sphere packings. The analysis of the particle radius distribution shows that they follow a power-law with an exponent ≈ D (i.e. ≈3 for a 3D packing and ≈2 for 2D). Although the algorithm intrinsically guarantees coordination numbers of at least 4 in 3D and 3 in 2D, the coordination numbers realized in the generated packings can be significantly higher, reaching beyond 50 if the range of particle radii is sufficiently large. Even for relatively small ranges of particle sizes (e.g. Rmin = 0.5Rmax) the maximum coordination number may exceed 10. The degree of isotropy of the generated sphere packing is also analysed in both 2D and 3D, by measuring the distribution of orientations of vectors joining the centres of adjacent particles. If the range of particle sizes is small, the packing algorithm yields moderate anisotropy approaching that expected for a face-centred cubic packing of equal-sized particles. However, once Rmin < 0.3Rmax a very high degree of isotropy is demonstrated in

  15. Preparation and characteristics of carbon-supported platinum catalyst and its application in the removal of phenolic pollutants in aqueous solution by microwave-assisted catalytic oxidation

    International Nuclear Information System (INIS)

    Granular activated carbon-supported platinum (Pt/GAC) catalysts were prepared by microwave irradiation and characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). Pt particles dispersing onto the surface of GAC could be penetrated by microwave and acted as 'reaction centre' in the degradations of p-nitrophenol (PNP) and pentachlorophenol (PCP) in aqueous solution by microwave-assisted catalytic oxidation. The reaction was carried out through a packed bed reactor under ambient pressure and continuous flow mode. Under the conditions of microwave power 400 W, influent flow 6.4 mL min-1 and air flow 120 mL min-1, phenolic solutions with high concentration (initial concentrations of PNP and PCP solutions were 1469 and 1454 mg L-1, respectively) were treated effectively by Pt/GAC, 86% PNP and 90% PCP were degraded and total organic carbon (TOC) removal reached 85% and 71%, respectively. Compared with GAC, loaded Pt apparently accelerated oxidative reaction so that Pt/GAC had a better degrading and mineralizing efficiencies for PNP. Hydraulic retention time was only 16 min in experiment, which was shortened greatly compared with catalytic wet air oxidation. Pyrolysis and oxidation of phenolic pollutants occurred simultaneously on the surface of Pt/GAC by microwave irradiation

  16. Tritium removal by hydrogen isotopic exchange between hydrogen gas and water on hydrophobic catalyst

    International Nuclear Information System (INIS)

    Many kinds of the hydrophobic catalysts for hydrogen isotopic exchange between hydrogen gas and water have been prepared. The carriers are the hydrophobic organic materials such as polytetrafluoroethylene(PTFE), monofluorocarbon-PTFE mixture(PTFE-FC), and styrene-divinylbenzene copolymer(SDB). 0.1 to 2 wt % Pt is deposited on the carriers. The Pt/SDB catalyst has much higher activity than the Pt/PTFE catalyst and the Pt/PTFE-FC catalyst shows the intermediate value of catalytic activity. The observation of electron microscope shows that the degrees of dispersion of Pt particles on the hydrophobic carriers result in the difference of catalytic activities. A gas-liquid separated type column containing ten stages is constructed. Each stage is composed of both the hydrophobic catalyst bed for the hydrogen gas/water vapor isotopic exchange and the packed column type bed for the water vapor/liquid water isotopic exchange. In the column hydrogen gas and water flow countercurrently and hydrogen isotopes are separated

  17. Computational Chemistry-Based Identification of Ultra-Low Temperature Water-Gas-Shift Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Manos Mavrikakis

    2008-08-31

    The current work seeks to identify novel, catalytically-active, stable, poison-resistant LWGS catalysts that retain the superior activity typical of conventional Cu catalysts but can be operated at similar or lower temperatures. A database for the Binding Energies (BEs) of the LWGS relevant species, namely CO, O and OH on the most-stable, close-packed facets of a set of 17 catalytically relevant transition metals was established. This BE data and a database of previously established segregation energies was utilized to predict the stability of bimetallic NSAs that could be synthesized by combinations of the 17 parent transition metals. NSAs that were potentially stable both in vacuo and under the influence of strong-binding WGS intermediates were then selected for adsorption studies. A set of 40 NSAs were identified that satisfied all three screener criteria and the binding energies of CO, O and OH were calculated on a set of 66, 43 and 79 NSA candidates respectively. Several NSAs were found that bound intermediates weaker than the monometallic catalysts and were thus potentially poison-resistant. Finally, kinetic studies were performed and resulted in the discovery of a specific NSA-based bimetallic catalyst Cu/Pt that is potentially a promising LWGS catalyst. This stable Cu/Pt subsurface alloy is expected to provide facile H{sub 2}O activation and remain relatively resistant from the poisoning by CO, S and formate intermediates.

  18. Duplex steam reformer: alternate catalyst

    International Nuclear Information System (INIS)

    The manufacturing feasibility of a duplex steam reformer tube for potential use in a high temperature gas cooled reactor has been successfully demonstrated. This technique consists of explosively expanding the inner tube into the outer tube. To successfully achieve the desired 0 to 3 mil radial gap between the tubes it is necessary to perform the expansion in two steps with an intermediate anneal. A catalyst design that would have replaced the conventional Raschig rings with a metal supported catalyst has been evaluated and it has been concluded that further development and testing are needed before fabrication of a full scale prototype is warranted. Consequently, the immediate efforts are directed towards reevaluating the incentives for developing a catalyst and the probability of successfully developing a catalyst that could be used for steam reforming

  19. Alumina supported iridium catalysts - preparation

    International Nuclear Information System (INIS)

    This report describes the method employed in the preparation of alumina supported iridium catalysts, with metal contents between 30 and 40%, that will be used for hydrazine monopropellant decomposition. (author)

  20. Separately supported polymetallic reforming catalyst

    Energy Technology Data Exchange (ETDEWEB)

    Kresge, C. T.; Krishnamurthy, S.; McHale, W. D.

    1985-01-15

    There is provided, in accordance with the present invention, a catalyst composition made up of a mixture of two components, one component comprising a minor proportion of platinum and rhenium on a support and the second component comprising a minor proportion of iridium and rhenium on a separate support. A process for reforming a charge stock, such as naphtha, utilizing such catalyst is also provided.

  1. Performance of high-rate gravel-packed oil wells

    Energy Technology Data Exchange (ETDEWEB)

    Unneland, Trond

    2001-05-01

    Improved methods for the prediction, evaluation, and monitoring of performance in high-rate cased-hole gravel-packed oil wells are presented in this thesis. The ability to predict well performance prior to the gravel-pack operations, evaluate the results after the operation, and monitor well performance over time has been improved. This lifetime approach to performance analysis of gravel-packed oil wells contributes to increase oil production and field profitability. First, analytical models available for prediction of performance in gravel-packed oil wells are reviewed, with particular emphasis on high-velocity flow effects. From the analysis of field data from three North Sea oil fields, improved and calibrated cased-hole gravel-pack performance prediction models are presented. The recommended model is based on serial flow through formation sand and gravel in the perforation tunnels. In addition, new correlations for high-velocity flow in high-rate gravel-packed oil wells are introduced. Combined, this improves the performance prediction for gravel-packed oil wells, and specific areas can be targeted for optimized well design. Next, limitations in the current methods and alternative methods for evaluation and comparison of well performance are presented. The most widely used parameter, the skin factor, remains a convenient and important parameter. However, using the skin concept in direct comparisons between wells with different reservoir properties may result in misleading or even invalid conclusions. A discussion of the parameters affecting the skin value, with a clarification of limitations, is included. A methodology for evaluation and comparison of gravel-packed well performance is presented, and this includes the use of results from production logs and the use of effective perforation tunnel permeability as a parameter. This contributes to optimized operational procedures from well to well and from field to field. Finally, the data sources available for

  2. Nonequilibrium hard-disk packings with controlled orientational order

    International Nuclear Information System (INIS)

    This paper addresses one of the fundamental questions in the theory of hard-disk packings--how order within a system relates to packing density. The algorithm presented is a seed-based, growth protocol in which new disks are added sequentially to the surface of a growing cluster. The angular position of the new disk is chosen based on the minimization of an objective function designed to control order, as measured by the global bond-orientational order parameter ψ6, which varies between 0 and 1 (with 1 indicating perfect hexagonal close-packed order). Modifying the objective function allows the final packing fraction to be biased while maintaining tight control over ψ6. Inside of the range 0≤ψ6≤0.70, the targeted order parameter ψ6 is achieved to within two decimal places of accuracy. Furthermore, it is found that random structures (ψ6∼0.01) can be generated with packing fractions in the range 0.40≤η≤0.77. Interestingly, the algorithm can produce nonequilibrium hard-disk configurations that are considerably more disordered than those typical of the equilibrium fluid. (c) 2000 American Institute of Physics

  3. The progress in the study of Arctic pack ice ecology

    Institute of Scientific and Technical Information of China (English)

    何剑锋; 王桂忠; 蔡明红; 李少菁

    2004-01-01

    The sea ice community plays an important role in the Arctic marine ecosystem. Because of the predicted environmental changes in the Arctic environment and specifically related to sea ice, the Arctic pack ice biota has received more attention in recent years using modern ice-breaking research vessels. Studies show that the Arctic pack ice contains a diverse biota and besides ice algae, the bacterial and protozoan biomasses can be high. Surprisingly high primary production values were observed in the pack ice of the central Arctic Ocean. Occasionally biomass maximum were discovered in the interior of the ice floes, a habitat that had been ignored in most Arctic studies. Many scientific questions, which deserve special attention, remained unsolved due to logistic limitations and the sea ice characteristics. Little is know about the pack ice community in the central Arctic Ocean. Almost no data exists from the pack ice zone for the winter season. Concerning the abundance of bacteria and protozoa, more studies are needed to understand the microbial network within the ice and its role in material and energy flows. The response of the sea ice biota to global change will impact the entire Arctic marine ecosystem and a long-term monitoring program is needed. The techniques, that are applied to study the sea ice biota and the sea ice ecology, should be improved.

  4. Test apparatus for ITER blanket pebble packing behavior

    International Nuclear Information System (INIS)

    Current Japanese design for ITER Driver Blanket consists of three breeder layers, nine multiplier layers and five cooling panels. The breeder layers and the multiplier layers contain 1 mm diameter spheres of Li2O and Be, respectively. The heat transfer in such 'Pebble Layered Blanket' is largely affected by the packing fraction of the pebbles which can be easily changed by the vibration during the operation. The packing fraction of the pebbles are expected to be as high as possible on the view point of nuclear heat design to maintain the optimum temperature of the breeder layer. Thus, it is necessary to establish the stable packed bed of the breeder and multiplier. The present experimental apparatus was fabricated for the engineering tests with the partial model of Japanese blanket. Test apparatus consists of stainless steel test panels, transparent plastic test panels, vibrators and measurement instruments. The apparatus can examine various parameters of sphere packed beds such as packing fraction, panels deformation, loading weight at the bottom of the panels and so on under various vibrating conditions. (author)

  5. A Geometric-Structure Theory for Maximally Random Jammed Packings

    Science.gov (United States)

    Tian, Jianxiang; Xu, Yaopengxiao; Jiao, Yang; Torquato, Salvatore

    2015-11-01

    Maximally random jammed (MRJ) particle packings can be viewed as prototypical glasses in that they are maximally disordered while simultaneously being mechanically rigid. The prediction of the MRJ packing density ϕMRJ, among other packing properties of frictionless particles, still poses many theoretical challenges, even for congruent spheres or disks. Using the geometric-structure approach, we derive for the first time a highly accurate formula for MRJ densities for a very wide class of two-dimensional frictionless packings, namely, binary convex superdisks, with shapes that continuously interpolate between circles and squares. By incorporating specific attributes of MRJ states and a novel organizing principle, our formula yields predictions of ϕMRJ that are in excellent agreement with corresponding computer-simulation estimates in almost the entire α-x plane with semi-axis ratio α and small-particle relative number concentration x. Importantly, in the monodisperse circle limit, the predicted ϕMRJ = 0.834 agrees very well with the very recently numerically discovered MRJ density of 0.827, which distinguishes it from high-density “random-close packing” polycrystalline states and hence provides a stringent test on the theory. Similarly, for non-circular monodisperse superdisks, we predict MRJ states with densities that are appreciably smaller than is conventionally thought to be achievable by standard packing protocols.

  6. Important notice for Windows 2000 Service Pack 3 computers

    CERN Multimedia

    The NICE Team

    2005-01-01

    Microsoft is ending support for Windows 2000 Service Pack 3, which was introduced in 2002. As a consequence, computers running Windows 2000 Service Pack 3 (or older versions1)) must be updated. It is recommended that Windows 2000 computers be re-installed with Windows XP Service Pack 2 (see http://cern.ch/Win/Services/Installation/Diane). If this is not possible for compatibility reasons, Windows 2000 Service Pack 4 must be installed to ensure the computers continue to receive security patches (see http://cern.ch/Win/Docs/2000SP4). In the next few days, NICE 2000 computers requiring an update will receive a pop-up window with instructions. Users requiring help with the update can contact Helpdesk@cern.ch or call 78888. If your computer needs to be updated you are recommended to read the additional information available at http://cern.ch/Win/Docs/2000SP3. The NICE Team 1) To determine your Windows service pack version, use the ‘Start' button and select ‘Run'. In the new window that open...

  7. Important notice for Windows 2000 Service Pack 3 computers

    CERN Multimedia

    The NICE Team

    2005-01-01

    Microsoft is ending support for Windows 2000 Service Pack 3, which was introduced in 2002. As a consequence, computers running Windows 2000 Service Pack 3 (or older versions1) ) must be updated. It is recommended that Windows 2000 computers be re-installed with Windows XP Service Pack 2 (see http://cern.ch/Win/Services/Installation/Diane). If this is not possible for compatibility reasons, Windows 2000 Service Pack 4 must be installed to ensure the computers continue to receive security patches (see http://cern.ch/Win/Docs/2000SP4). In the next few days, NICE 2000 computers requiring an update will receive a pop-up window with instructions. Users requiring help with the update can contact Helpdesk@cern.ch or call 78888. If your computer needs to be updated you are recommended to read the additional information available at http://cern.ch/Win/Docs/2000SP3. The NICE Team 1) To determine your Windows service pack version, use the ‘Start' button and select ‘Run'. In the new window that opens, type ‘wi...

  8. Bernal's road to random packing and the structure of liquids

    Science.gov (United States)

    Finney, John L.

    2013-11-01

    Until the 1960s, liquids were generally regarded as either dense gases or disordered solids, and theoretical attempts at understanding their structures and properties were largely based on those concepts. Bernal, himself a crystallographer, was unhappy with either approach, preferring to regard simple liquids as 'homogeneous, coherent and essentially irregular assemblages of molecules containing no crystalline regions'. He set about realizing this conceptual model through a detailed examination of the structures and properties of random packings of spheres. In order to test the relevance of the model to real liquids, ways had to be found to realize and characterize random packings. This was at a time when computing was slow and in its infancy, so he and his collaborators set about building models in the laboratory, and examining aspects of their structures in order to characterize them in ways which would enable comparison with the properties of real liquids. Some of the imaginative - often time consuming and frustrating - routes followed are described, as well the comparisons made with the properties of simple liquids. With the increase of the power of computers in the 1960s, computational approaches became increasingly exploited in random packing studies. This enabled the use of packing concepts, and the tools developed to characterize them, in understanding systems as diverse as metallic glasses, crystal-liquid interfaces, protein structures, enzyme-substrate interactions and the distribution of galaxies, as well as their exploitation in, for example, oil extraction, understanding chromatographic separation columns, and packed beds in industrial processes.

  9. Studies of Particle Packings in Mixtures of Pharmaceutical Excipients

    Science.gov (United States)

    Bentham, Craig; Dutt, Meenakshi; Hancock, Bruno; Elliott, James

    2005-03-01

    Pharmaceutical powder blends used to generate tablets are complex multicomponent mixtures of the drug powder and excipients which facilitate the delivery of the required drug. The individual constituents of these blends can be noncohesive and cohesive powders. We study the geometric and mechanical characteristics of idealized mixtures of excipient particle packings, for a small but representative number of dry noncohesive particles, generated via gravitational compaction followed by uniaxial compaction. We discuss particle packings in 2- and 3- component mixtures of microcrystalline cellulose (MCC) & lactose and MCC, starch & lactose, respectively. We have computed the evolution of the force and stress distributions in monodisperse and polydisperse mixtures comprised of equal parts of each excipient; comparisons are made with results for particles packings of pure blends of MCC and lactose. We also compute the stress-strain relations for these mixtures. In order to obtain insight into details of the particle packings, we calculate the coordination number, packing fraction, radial distribution functions and contact angle distributions for the various mixtures. The numerical experiments have been performed on spheroidal idealizations of the excipient grains using Discrete Element Method simulations (Dutt et al., 2004 to be published).

  10. Spectral Action Models of Gravity on Packed Swiss Cheese Cosmology

    CERN Document Server

    Ball, Adam

    2015-01-01

    We present a model of (modified) gravity on spacetimes with fractal structure based on packing of spheres, which are (Euclidean) variants of the Packed Swiss Cheese Cosmology models. As the action functional for gravity we consider the spectral action of noncommutative geometry, and we compute its asymptotic expansion on a space obtained as an Apollonian packing of 3-dimensional spheres inside a 4-dimensional ball. Using information from the zeta function of the Dirac operator of the spectral triple, we show that the leading terms in the asymptotic expansion of the spectral action consist of a zeta regularization of the divergent sum of the leading terms of the spectral actions of the individual spheres in the packing, which accounts for the contribution of the points 1 and 3 in the dimension spectrum (as in the case of a 3-sphere). There is also an additional term coming from the residue at the additional point in the dimension spectrum that corresponds to the packing constant. It detects the fractality of t...

  11. Experimental and modelling study of drinking water hydrogenotrophic denitrification in packed-bed reactors

    International Nuclear Information System (INIS)

    The aim of this work was to study hydrogenotrophic denitrification in packed-bed reactors under draw-fill and continuous operation. Three bench-scale packed-bed reactors with gravel in different sizes (mean diameter 1.75, 2.41 and 4.03 mm) as support media were used, in order to study the effect of particle size on reactors performance. The maximum denitrification rate achieved under draw-fill operation was 4.4 g NO3--N/ld for the filter with gravel of 2.41 mm. This gravel size was chosen to perform experiments under continuous operation. Feed NO3--N concentrations and hydraulic loadings (HL) ranged between 20-200 mg/l and 5.7-22.8 m3/m2 d, respectively. A comparison between the two operating modes showed that, for low HL the draw-fill operation achieved higher denitrification rates, while for high HL and intermediate feed concentrations (40-60 mg NO3--N/l) the continuous operation achieved higher denitrification rates (4.67-5.65 g/ld). Finally, experiments with three filters in series (with gravels of 4.03, 2.41 and 1.75 mm mean diameter) were also performed under continuous operation. The maximum denitrification rate achieved was 6.2 g NO3--N/ld for feed concentration of 340 mg/l and HL of 11.5 m3/m2 d. A model, which describes denitrification in packed-bed reactors, was also developed. The model predicts the concentration profiles of NO3--N along filter height, in draw-fill as well as in continuous operation, satisfactorily.

  12. The innovation catalysts.

    Science.gov (United States)

    Martin, Roger L

    2011-06-01

    A few years ago the software development company Intuit realized that it needed a new approach to galvanizing customers. The company's Net Promoter Score was faltering, and customer recommendations of new products were especially disappointing. Intuit decided to hold a two-day, off-site meeting for the company's top 300 managers with a focus on the role of design in innovation. One of the days was dedicated to a program called Design for Delight. The centerpiece of the day was a PowerPoint presentation by Intuit founder Scott Cook, who realized midway through that he was no Steve Jobs: The managers listened dutifully, but there was little energy in the room. By contrast, a subsequent exercise in which the participants worked through a design challenge by creating prototypes, getting feedback, iterating, and refining, had them mesmerized. The eventual result was the creation of a team of nine design-thinking coaches--"innovation catalysts"--from across Intuit who were made available to help any work group create prototypes, run experiments, and learn from customers. The process includes a "painstorm" (to determine the customer's greatest pain point), a "soljam" (to generate and then winnow possible solutions), and a "code-jam" (to write code "good enough" to take to customers within two weeks). Design for Delight has enabled employees throughout Intuit to move from satisfying customers to delighting them. PMID:21714388

  13. PlanetPack: A radial-velocity time-series analysis tool facilitating exoplanets detection, characterization, and dynamical simulations

    Science.gov (United States)

    Baluev, Roman V.

    2013-08-01

    We present PlanetPack, a new software tool that we developed to facilitate and standardize the advanced analysis of radial velocity (RV) data for the goal of exoplanets detection, characterization, and basic dynamical N-body simulations. PlanetPack is a command-line interpreter, that can run either in an interactive mode or in a batch mode of automatic script interpretation. Its major abilities include: (i) advanced RV curve fitting with the proper maximum-likelihood treatment of unknown RV jitter; (ii) user-friendly multi-Keplerian as well as Newtonian N-body RV fits; (iii) use of more efficient maximum-likelihood periodograms that involve the full multi-planet fitting (sometimes called as “residual” or “recursive” periodograms); (iv) easily calculatable parametric 2D likelihood function level contours, reflecting the asymptotic confidence regions; (v) fitting under some useful functional constraints is user-friendly; (vi) basic tasks of short- and long-term planetary dynamical simulation using a fast Everhart-type integrator based on Gauss-Legendre spacings; (vii) fitting the data with red noise (auto-correlated errors); (viii) various analytical and numerical methods for the tasks of determining the statistical significance. It is planned that further functionality may be added to PlanetPack in the future. During the development of this software, a lot of effort was made to improve the calculational speed, especially for CPU-demanding tasks. PlanetPack was written in pure C++ (standard of 1998/2003), and is expected to be compilable and useable on a wide range of platforms.

  14. Measurement of HETP of SUS Dixon ring and porcelain packing in small-scale water distillation column for H2O-HTO isotope separation

    International Nuclear Information System (INIS)

    Series of water distillations in a total reflux mode have been performed in a 100 cm height column of 1.6 cm I.D. in order to measure values of HETP for various packings, that is, one brass or three SUS Dixon rings and three porcelain packings. The HETP were measured by changing the vapor flow rate within the column. The SUS Dixon ring of 1.5 mm diameter and the porcelain packing of 1.2 mm O.D. had a small HETP (∼5 cm), but could not meet a large vapor flow rate because of a large pressure drop. The SUS Dixon ring of 6.0 mm diameter had a small HETP (∼6 cm) in the vapor flow rate under 2 g/min, but the HETP value increased with increasing the vapor flow rate. The pressure drop for the ring, however, was almost constant in the range of these measurements. (author)

  15. FY-87 packing fabrication techniques (commercial waste form) results

    Energy Technology Data Exchange (ETDEWEB)

    Werry, E.V.; Gates, T.E.; Cabbage, K.S.; Eklund, J.D.

    1988-04-01

    This report covers the investigation of fabrication techniques associated with the development of suitable materials and methods to provide a prefabricated packing for waste packages for the Basalt Waste Isolation Project (BWIP). The principal functions of the packing are to minimize container corrosion during the 300 to 1000 years following repository closure and provide long-term control of the release of radionuclides from the waste package. The investigative work, discussed in this report, was specifically conceived to develop the design criteria for production of full-scale prototypical packing rings. The investigative work included the preparation of procedures, the preparation of fabrication materials, physical properties, and the determination of the engineering properties. The principal activities were the preparation of the materials and the determination of the physical properties. 21 refs., 20 figs., 14 tabs.

  16. A Heuristic Algorithm for Solving Triangle Packing Problem

    Directory of Open Access Journals (Sweden)

    Ruimin Wang

    2013-01-01

    Full Text Available The research on the triangle packing problem has important theoretic significance, which has broad application prospects in material processing, network resource optimization, and so forth. Generally speaking, the orientation of the triangle should be limited in advance, since the triangle packing problem is NP-hard and has continuous properties. For example, the polygon is not allowed to rotate; then, the approximate solution can be obtained by optimization method. This paper studies the triangle packing problem by a new kind of method. Such concepts as angle region, corner-occupying action, corner-occupying strategy, and edge-conjoining strategy are presented in this paper. In addition, an edge-conjoining and corner-occupying algorithm is designed, which is to obtain an approximate solution. It is demonstrated that the proposed algorithm is highly efficient, and by the time complexity analysis and the analogue experiment result is found.

  17. A Novel GRASP Algorithm for Solving the Bin Packing Problem

    Directory of Open Access Journals (Sweden)

    Abdesslem Layeb

    2012-04-01

    Full Text Available The Bin Packing Problem (BPP is one of the most known combinatorial optimization problems. This problem consists in packing a set of items into a minimum number of bins. There are several variants of this problem; the most basic problem is the one-dimensional bin packing problem (1-BPP. In this paper, we present a new approach based on the GRASP procedure to deal with the1-BPP problem. The first GRASP phase is based on a new random heuristics based on hybridization between First Fit and Best Fit heuristics. The second GRASP phase is based on Tabu search algorithm used for the enhancement of the solutions found in the first phase. The obtained results are very encouraging and show the feasibility and effectiveness of the proposed approach

  18. A Personified Annealing Algorithm for Circles Packing Problem

    Institute of Scientific and Technical Information of China (English)

    ZHANGDe-Fu; LIXin

    2005-01-01

    Circles packing problem is an NP-hard problem and is difficult to solve. In this paper, a hybrid search strategy for circles packing problem is discussed. A way of generating new configuration is presented by simulating the moving of elastic objects, which can avoid the blindness of simulated annealing search and make iteration process converge fast. Inspired by the life experiences of people,an effective personified strategy to jump out of local minima is given. Based on the simulated annealing idea and personification strategy, an effective personified annealing algorithm for circles packing problem is developed. Numerical experiments on benchmark problem instances show that the proposed algorithm outperforms the best algorithm in the literature.

  19. Study on the performance of new structured packings

    International Nuclear Information System (INIS)

    The metal gauze structured packings are widely used in many distillation processes because of the low pressure drop and high numbers of theoretical plate. To provide the fundamental datas for the industrialization of boron isotope separation, experiments were carried out to investigate the performance of CDG1700Y and CDG2500Y metal gauze structured packings using the mixture of cyclohexane-n-heptane and n-heptane-methylbenzene under the conditions of total reflux and different reflux ratios. Experimental results show that the pressure drop rises with the increase of reflux ratio and the adverse change trend happens for the height equivalent to theoretical plate. In addition, the two kinds of packings have high numbers of theoretical plate and narrower range of operation. (authors)

  20. Emergence of Gamma distributions in granular materials and packing models

    Science.gov (United States)

    Aste, T.; di Matteo, T.

    2008-02-01

    We study the distribution of volume fluctuations in experiments and numerical simulations concerning equal-sized sphere packings prepared with different techniques. We show that the distribution of the local volumes (Voronoï cells) and also the distributions of the global volumes (whole samples) follow remarkably well a shifted and rescaled Gamma distribution that we name a k-Gamma distribution. Such agreement is robust over a broad range of packing fractions and it is observed for several distinct systems. This distribution is characterized by the average packing fraction and a shape parameter “ k ” which is very sensitive to changes in the structural organization. A statistical mechanics approach predicts such k-Gamma distribution at statistical equilibrium and it links the parameter k with the number of elementary cells which are exchanging volume during the system preparation. The thermodynamical equivalent of k and its relation with the “granular temperature” are also discussed.

  1. Bin Completion Algorithms for Multicontainer Packing, Knapsack, and Covering Problems

    CERN Document Server

    Fukunaga, A S; 10.1613/jair.2106

    2011-01-01

    Many combinatorial optimization problems such as the bin packing and multiple knapsack problems involve assigning a set of discrete objects to multiple containers. These problems can be used to model task and resource allocation problems in multi-agent systems and distributed systms, and can also be found as subproblems of scheduling problems. We propose bin completion, a branch-and-bound strategy for one-dimensional, multicontainer packing problems. Bin completion combines a bin-oriented search space with a powerful dominance criterion that enables us to prune much of the space. The performance of the basic bin completion framework can be enhanced by using a number of extensions, including nogood-based pruning techniques that allow further exploitation of the dominance criterion. Bin completion is applied to four problems: multiple knapsack, bin covering, min-cost covering, and bin packing. We show that our bin completion algorithms yield new, state-of-the-art results for the multiple knapsack, bin covering,...

  2. Lightweight, Flexible, Thin, Integrated Solar-Power Packs

    Science.gov (United States)

    Hanson, Robert R.

    2004-01-01

    Lightweight, flexible, thin, one-piece, solar-power packs are undergoing development. Each power pack of this type is a complete, modular, integrated power-supply system comprising three power subsystems that, in conventional practice, have been constructed as separate units and connected to each other by wires. These power packs are amenable to a variety of uses: For example, they could be laminated to the tops of tents and other shelters to provide or augment power for portable electronic equipment in the field, and they could be used as power sources for such small portable electronic systems as radio transceivers (including data relays and cellular telephones), laptop computers, video camcorders, and Global Positioning System receivers.

  3. Patterned graphone—a novel template for molecular packing

    Science.gov (United States)

    Reddy, C. D.; Zhang, Y. W.; Shenoy, V. B.

    2012-04-01

    Precise positioning and packing of nanoscale building blocks is essential for the fabrication of many nanoelectro-mechanical devices. Carrying out such manipulations at the nanoscale still remains a challenge. Here we propose the use of graphone domain arrays embedded in a graphene sheet as a template to precisely position and pack molecules. Our atomistic simulations show that a graphone domain is able to adopt well-defined three-dimensional geometries, which in turn create ‘energy wells’ to trap molecules by means of physisorption. Using the C60 molecule as a model block, the stable trapping conditions are identified. The present work presents a novel route to position and pack molecules for nanoengineering applications.

  4. FY-87 packing fabrication techniques (commercial waste form) results

    International Nuclear Information System (INIS)

    This report covers the investigation of fabrication techniques associated with the development of suitable materials and methods to provide a prefabricated packing for waste packages for the Basalt Waste Isolation Project (BWIP). The principal functions of the packing are to minimize container corrosion during the 300 to 1000 years following repository closure and provide long-term control of the release of radionuclides from the waste package. The investigative work, discussed in this report, was specifically conceived to develop the design criteria for production of full-scale prototypical packing rings. The investigative work included the preparation of procedures, the preparation of fabrication materials, physical properties, and the determination of the engineering properties. The principal activities were the preparation of the materials and the determination of the physical properties. 21 refs., 20 figs., 14 tabs

  5. CFD study of pressure drop and flow through corrugated structured packing to be used for tritium extraction in TBM

    International Nuclear Information System (INIS)

    In this paper we have presented the flow profiles of the gas in the packing and the dry pressure drop respectively using commercial Computational Fluid Dynamics (CFD) software. Due to the complexity of the geometry of the packing and intense requirement of the CPU time, calculations have been carried out for estimation of pressure drop and flow pattern for only gas flow though both gauze type and sheet type corrugated packing with different combinations of packing elements as: a) 2 sheet model for corrugated sheet packing, b) 2 sheet model for corrugated gauze packing, c) Packing element model for corrugated sheet packing, d) Packing element model for corrugated gauze packing

  6. A Quantitative Study on Packing Density and Pozzolanic Activity of Cementitious Materials Based on the Compaction Packing Model

    Science.gov (United States)

    Gong, Jianqing; Chou, Kai; Huang, Zheng Yu; Zhao, Minghua

    2014-08-01

    A brief introduction to the theoretical basis of compaction packing model (CPM) and an over-view of the principle of the specific strength method provided the starting point of this study. Then, research on quantitative relations was carried out to find the correlation between the contribution rate of the pozzolanic activity and the contribution value of packing density when CPM was applied to fine powder mixture systems. The concept of the contribution value of the packing density being in direct correspondence with the contribution rate was proved by the compressive strength results and SEM images. The results indicated that the variation rule of the contribution rate of the pozzolanic activity is similar to that of the contribution value of packing density as calculated by CPM. This means the contribution value of the packing density could approximately simulate the change tendency of the contribution rate of the pozzolanic activity, which is of significant value for the future of mix designs for high and ultra-high performance concrete.

  7. Acid monolayer functionalized iron oxide nanoparticle catalysts

    Science.gov (United States)

    Ikenberry, Myles

    Superparamagnetic iron oxide nanoparticle functionalization is an area of intensely active research, with applications across disciplines such as biomedical science and heterogeneous catalysis. This work demonstrates the functionalization of iron oxide nanoparticles with a quasi-monolayer of 11-sulfoundecanoic acid, 10-phosphono-1-decanesulfonic acid, and 11-aminoundecanoic acid. The carboxylic and phosphonic moieties form bonds to the iron oxide particle core, while the sulfonic acid groups face outward where they are available for catalysis. The particles were characterized by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), potentiometric titration, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectrometry (XPS), and dynamic light scattering (DLS). The sulfonic acid functionalized particles were used to catalyze the hydrolysis of sucrose at 80° and starch at 130°, showing a higher activity per acid site than the traditional solid acid catalyst Amberlyst-15, and comparing well against results reported in the literature for sulfonic acid functionalized mesoporous silicas. In sucrose catalysis reactions, the phosphonic-sulfonic nanoparticles (PSNPs) were seen to be incompletely recovered by an external magnetic field, while the carboxylic-sulfonic nanoparticles (CSNPs) showed a trend of increasing activity over the first four recycle runs. Between the two sulfonic ligands, the phosphonates produced a more tightly packed monolayer, which corresponded to a higher sulfonic acid loading, lower agglomeration, lower recoverability through application of an external magnetic field, and higher activity per acid site for the hydrolysis of starch. Functionalizations with 11-aminoundecanoic acid resulted in some amine groups binding to the surfaces of iron oxide nanoparticles. This amine binding is commonly ignored in iron oxide

  8. Is Random Close Packing of Spheres Well Defined?

    International Nuclear Information System (INIS)

    Despite its long history, there are many fundamental issues concerning random packings of spheres that remain elusive, including a precise definition of random close packing (RCP). We argue that the current picture of RCP cannot be made mathematically precise and support this conclusion via a molecular dynamics study of hard spheres using the Lubachevsky-Stillinger compression algorithm. We suggest that this impasse can be broken by introducing the new concept of a maximally random jammed state, which can be made precise. (c) 2000 The American Physical Society

  9. Excluded volumes of clusters in tetrahedral particle packing

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lufeng; Lu, Peng; Meng, Lingyi; Jin, Weiwei; Li, Shuixiang, E-mail: lsx@pku.edu.cn

    2014-02-01

    We investigate the excluded volumes of clusters in tetrahedral particle packing using an ideal tetrahedron model and Monte Carlo simulation. Both the influences of the size and topology of clusters on the excluded volume are studied. We find that the excluded volumes of the dimer composed of two tetrahedra and the wagon wheel composed of five tetrahedra are relatively lower than other cluster forms. For large clusters, the excluded volume decreases when the topology of a cluster approaches the wagon-wheel geometry. The results give an explanation to the cluster distribution which demonstrates that the dimer and wagon wheel are the dominative cluster forms in the packing structure of tetrahedra.

  10. NO removal by nonthermal plasma with modified sepiolite catalyst

    International Nuclear Information System (INIS)

    Non-Thermal Plasma (NTP) combined with a catalyst is one of the effective ways to remove NO from auto exhaust gas. Sepiolite Ore Powder (SOP), which was modified by acid washing, copper nitrate soaking, drying and calcinations, served as the Modified Sepiolite Catalyst (MSC) for NO removal in a rod-cylinder Dielectric Barrier Discharge (DBD) reactor. The characteristic of the MSC was characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The experiment showed that the acid concentration, washing time, the packed site of MSC and input voltage of the NTP impacted the NO removal rate effectively. The NO removal rate increased and then decreased with an increase in the acid concentration and the washing time, and the NO removal rate increased monotonously with the increased input voltage. The NO removal rate was higher at the beginning, decreased gradually then maintained stability after 10 min. Thus, the result indicated that MSC has a good ability for adsorption and storage of NO.

  11. Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles

    Energy Technology Data Exchange (ETDEWEB)

    Amitava Sarkar; James K. Neathery; Burtron H. Davis

    2006-12-31

    A fundamental filtration study was started to investigate the separation of Fischer-Tropsch Synthesis (FTS) liquids from iron-based catalyst particles. Slurry-phase FTS in slurry bubble column reactor systems is the preferred mode of operation since the reaction is highly exothermic. Consequently, heavy wax products in one approach may be separated from catalyst particles before being removed from the reactor system. Achieving an efficient wax product separation from iron-based catalysts is one of the most challenging technical problems associated with slurry-phase iron-based FTS and is a key factor for optimizing operating costs. The separation problem is further compounded by attrition of iron catalyst particles and the formation of ultra-fine particles.

  12. Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

    International Nuclear Information System (INIS)

    Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, we introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties of suitably designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, we demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm(sub 2) for 40-(micro)m wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection

  13. Laser-Induced Fluorescence Detection in High-Throughput Screening of Heterogeneous Catalysts and Single Cells Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hui Su

    2001-05-01

    Laser-induced fluorescence detection is one of the most sensitive detection techniques and it has found enormous applications in various areas. The purpose of this research was to develop detection approaches based on laser-induced fluorescence detection in two different areas, heterogeneous catalysts screening and single cell study. First, we introduced laser-induced imaging (LIFI) as a high-throughput screening technique for heterogeneous catalysts to explore the use of this high-throughput screening technique in discovery and study of various heterogeneous catalyst systems. This scheme is based on the fact that the creation or the destruction of chemical bonds alters the fluorescence properties of suitably designed molecules. By irradiating the region immediately above the catalytic surface with a laser, the fluorescence intensity of a selected product or reactant can be imaged by a charge-coupled device (CCD) camera to follow the catalytic activity as a function of time and space. By screening the catalytic activity of vanadium pentoxide catalysts in oxidation of naphthalene, we demonstrated LIFI has good detection performance and the spatial and temporal resolution needed for high-throughput screening of heterogeneous catalysts. The sample packing density can reach up to 250 x 250 subunits/cm{sub 2} for 40-{micro}m wells. This experimental set-up also can screen solid catalysts via near infrared thermography detection.

  14. High-power RF distribution system for the 8-pack project

    CERN Document Server

    Nantista, C; Chan, J; Kazakov, S; Schultz, D; Tantawi, S

    2004-01-01

    The 8-Pack Project at SLAC is a prototype rf system whose goal is to demonstrate the high-power X-band technology developed in the NLC/GLC program. In its first phase, it has reliably produced a 400 ns rf pulse of over 500 MW using a solid-state modulator, four 11.424 GHz klystrons and a dual-moded SLED-II pulse compressor [1]. In Phase 2, the output power of our system has been delivered into the bunker of the NLCTA (Next Linear Collider Test Accelerator) and divided between several accelerating structures, first four and finally eight, for beam acceleration. We describe here the design, cold-test measurements, and processing of this power distribution system. Due to the high power levels and the need for efficiency, overmoded waveguide and components are used. For power transport, the TE 01 mode is used in 7.44 cm and 4.064 cm diameter circular waveguide. Only near the structures is standard WR90 rectangular waveguide employed. Components used to manipulate the rf power include transitional tapers, mode con...

  15. Rolling-induced Face Centered Cubic Titanium in Hexagonal Close Packed Titanium at Room Temperature

    Science.gov (United States)

    Wu, H. C.; Kumar, A.; Wang, J.; Bi, X. F.; Tomé, C. N.; Zhang, Z.; Mao, S. X.

    2016-04-01

    Combining transmission electron microscopes and density functional theory calculations, we report the nucleation and growth mechanisms of room temperature rolling induced face-centered cubic titanium (fcc-Ti) in polycrystalline hexagonal close packed titanium (hcp-Ti). Fcc-Ti and hcp-Ti take the orientation relation: hcp||fcc and , different from the conventional one. The nucleation of fcc-Ti is accomplished via pure-shuffle mechanism with a minimum stable thickness of three atomic layers, and the growth via shear-shuffle mechanisms through gliding two-layer disconnections or pure-shuffle mechanisms through gliding four-layer disconnections. Such phase transformation offers an additional plastic deformation mode comparable to twinning.

  16. Static and dynamic magnetic properties of densely packed magnetic nanowire arrays

    DEFF Research Database (Denmark)

    Dmytriiev, O.; Al-Jarah, U.A.S.; Gangmei, P.;

    2013-01-01

    between experimental and simulated spectra are observed when the field is applied perpendicular to the nanowire axes. The dependence of the magnetic excitation spectra upon the array packing density is explored, and dispersion curves for spin waves propagating within the array parallel to the nanowire....... The excitation spectra obtained from experiment and micromagnetic simulations are in qualitative agreement for magnetic fields applied both parallel and perpendicular to the axes of the nanowires. For the field parallel to the nanowire axes, there is also good quantitative agreement between experiment...... and simulation. The resonant frequencies are initially found to decrease as the applied field is increased from remanence. This is the result of a change of mode profile within the plane of the array from nonuniform to uniform as the ground state evolves with increasing applied field. Quantitative differences...

  17. Influence of Catalyst Type and Regeneration on Upgrading of Crude Bio-oil through Catalytical Thermal Cracking

    Institute of Scientific and Technical Information of China (English)

    郭晓亚; 颜涌捷; 李庭琛

    2004-01-01

    Catalysts, such as HZSM-5(Si/Al=50), HZSM-5(25), zeolite 5A, CaHZSM-5(50), ZnHZSM-5(50), and Kaolin were used in upgrading of crude biomass oil from pyrolysis in a fixed-bed reactor under atmospheric pressure, in order to investigate the effects of catalyst type on the yield of desired product. A blank test was carried out in a bed of inert packings to determine the extent of non-catalytical thermal cracking. The gas produced in the reaction was analyzed by the chemical absorption method. Among those catalysts, HZSM-5(50) gave the highest yield of the desired organic distillate while Kaolin gave the least formation of coke. Regeneration of deactivated HZSM-5(50) was studied. In terms of yield of organic distillate and formation rate of coke, the catalytic activity did not change much during the first 3 times of regeneration.

  18. Production and optimization of biodiesel using mixed immobilized biocatalysts in packed bed reactor.

    Science.gov (United States)

    Bakkiyaraj, S; Syed, Mahin Basha; Devanesan, M G; Thangavelu, Viruthagiri

    2016-05-01

    Vegetable oils are used as raw materials for biodiesel production using transesterification reaction. Several methods for the production of biodiesel were developed using chemical (alkali and acidic compounds) and biological catalysts (lipases). Biodiesel production catalyzed by lipases is energy and cost-saving processes and is carried out at normal temperature and pressure. The need for an efficient method for screening larger number of variables has led to the adoption of statistical experimental design. In the present study, packed bed reactor was designed to study with mixed immobilized biocatalysts to have higher productivity under optimum conditions. Contrary to the single-step acyl migration mechanism, a two-step stepwise reaction mechanism involving immobilized Candida rugosa lipase and immobilized Rhizopus oryzae cells was employed for the present work. This method was chosen because enzymatic hydrolysis followed by esterification can tolerate high free fatty acid containing oils. The effects of flow rate and bed height on biodiesel yield were studied using two factors five-level central composite design (CCD) and response surface methodology (RSM). Maximum biodiesel yield of 85 and 81 % was obtained for jatropha oil and karanja oil with the optimum bed height and optimum flow rate of 32.6 cm and 1.35 L/h, and 32.6 cm and 1.36 L/h, respectively. PMID:25940482

  19. Regeneration of Hydrotreating and FCC Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    CM Wai; JG Frye; JL Fulton; LE Bowman; LJ Silva; MA Gerber

    1999-09-30

    Hydrotreating, hydrocracking, and fluid catalytic cracking (FCC) catalysts are important components of petroleum refining processes. Hydrotreating and hydrocracking catalysts are used to improve the yield of high-quality light oil fractions from heavier crude oil and petroleum feedstocks containing high levels of impurities. FCC catalysts improve the yield of higher octane gasoline from crude oil. Residuum hydrotreating and cracking catalysts are susceptible to irreversible deactivation caused by adsorption of sulfur and by metals impurities, such as vanadium and nickel. The gradual buildup of these impurities in a hydrotreating catalyst eventually plugs the pores and deactivates it. Nickel and vanadium adversely affect the behavior of cracking catalysts, reducing product yield and quality. Replacing deactivated catalysts represents a significant cost in petroleum refining. Equally important are the costs and potential liabilities associated with treating and disposing spent catalysts. For example, recent US Environmental Protection Agency rulings have listed spent hydrotreating and hydrorefining catalysts as hazardous wastes. FCC catalysts, though more easily disposed of as road-base or as filler in asphalt and cement, are still an economic concern mainly because of the large volumes of spent catalysts generated. New processes are being considered to increase the useful life of catalysts or for meeting more stringent disposal requirements for spent catalysts containing metals. This report discusses a collaborative effort between Pacific Northwest National Laboratory (PNNL) and Phillips Petroleum, Inc., to identify promising chemical processes for removing metals adhered to spent hydrodesulfurization (HDS, a type of hydrotreating catalyst) and FCC catalysts. This study, conducted by PNNL, was funded by the US Department of Energy's Bartlesville Project Office. Fresh and spent catalysts were provided by Phillips Petroleum. The FCC catalyst was a rare

  20. Impact of conduit geometry on the performance of typical particulate microchip packings.

    Science.gov (United States)

    Jung, Stephanie; Höltzel, Alexandra; Ehlert, Steffen; Mora, Jose-Angel; Kraiczek, Karsten; Dittmann, Monika; Rozing, Gerard P; Tallarek, Ulrich

    2009-12-15

    This work investigates the impact of conduit geometry on the chromatographic performance of typical particulate microchip packings. For this purpose, high-performance liquid chromatography (HPLC)/UV-microchips with separation channels of quadratic, trapezoidal, or Gaussian cross section were fabricated by direct laser ablation and lamination of multiple polyimide layers and then slurry-packed with either 3 or 5 microm spherical porous C8-silica particles under optimized packing conditions. Experimentally determined plate height curves for the empty microchannels are compared with dispersion coefficients from theoretical calculations. Packing densities and plate height curves for the various microchip packings are presented and conclusively explained. The 3 microm packings display a high packing density irrespective of their conduit geometries, and their performance reflects the dispersion behavior of the empty channels. Dispersion in 5 microm packings correlates with the achieved packing densities, which are limited by the number and accessibility of corners in a given conduit shape. PMID:19916548

  1. Reference book for design of valve packings, sealing high temperature water

    International Nuclear Information System (INIS)

    Mockups of stuffing boxes for valves in the 1/4 to 1 in. (0.6-2.54cm) pipe size range and ASA 900 and up pressure class were tested to determine how temperature, stuffing box dimensions, packing compressive stress and stem surface finish affect water leak rate, packing friction torque and packing volume loss (creep). One brand of wire-reinforced asbestos braid on graphite-and-asbestos core packing was used in all tests. The theory of leakage through porous media was reviewed with emphasis on application to packed stuffing boxes, and a mathematical framework for relating leakage and packing friction to stuffing box dimensions and compressive stress was developed. The tests gave empirical relationships (1) for leak rate vs temperature, packing compressive stress, stem diameter and packing size, (2) for packing friction torque vs the above variables and (3) for packing creep vs temperature and stress. Packing stress affected leakage far more than any other variable, the leak rate being inversely proportional to stress to the 7.3 power at a packing temperature of 350 deg F (175 deg C). Factors which increase packing compression (density) have a strong reducing effect on leakage and a moderate to zero effect on packing friction torque. Surface finish had no visible effect on leakage, torque or creep. Empirical results and theory have been combined to show how stuffing boxes can be designed for a given leakage rate. Suggestions for decreasing leakage from existing high temperature stuffing boxes are included. (author)

  2. Continuous Production of Lipase-Catalyzed Biodiesel in a Packed-Bed Reactor: Optimization and Enzyme Reuse Study

    Directory of Open Access Journals (Sweden)

    Hsiao-Ching Chen

    2011-01-01

    Full Text Available An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435 as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1∘C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31±2.07% and 82.81±.98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis.

  3. Catalyst containing oxygen transport membrane

    Science.gov (United States)

    Christie, Gervase Maxwell; Wilson, Jamie Robyn; van Hassel, Bart Antonie

    2012-12-04

    A composite oxygen transport membrane having a dense layer, a porous support layer and an intermediate porous layer located between the dense layer and the porous support layer. Both the dense layer and the intermediate porous layer are formed from an ionic conductive material to conduct oxygen ions and an electrically conductive material to conduct electrons. The porous support layer has a high permeability, high porosity, and a high average pore diameter and the intermediate porous layer has a lower permeability and lower pore diameter than the porous support layer. Catalyst particles selected to promote oxidation of a combustible substance are located in the intermediate porous layer and in the porous support adjacent to the intermediate porous layer. The catalyst particles can be formed by wicking a solution of catalyst precursors through the porous support toward the intermediate porous layer.

  4. Packing of protein structures in clusters with magic numbers

    DEFF Research Database (Denmark)

    Lindgård, Per-Anker; Bohr, Henrik

    1997-01-01

    Recently we have proposed a model for folding proteins into packed `clusters'. We have constructed a local homology measure for protein fold classes by projecting consecutively secondary structures onto a lattice. Taking into account hydrophobic forces we have found a mechanism for formation of...... abundances. In this paper we demonstrate that the results are robust to variations in the coordination number of the model....

  5. The use of particle packing models to design ecological concrete

    NARCIS (Netherlands)

    Fennis, S.A.A.M.; Walraven, J.C.; Den Uijl, J.A.

    2009-01-01

    Ecological concrete can be designed by replacing cement with fillers. With low amounts of cement it becomes increasingly important to control the water demand of concrete mixtures. In this paper a cyclic design method based on particle packing is presented and evaluated on the basis of experiments o

  6. Shelf-life extension of packed meat by irradiation

    International Nuclear Information System (INIS)

    The shelf-life extension of sliced pork under modified atmosphere (vacuum-, CO2-, CO2-N2-packaging), at different storage temperature (3-5 and 8-10 deg. C) and irradiation doses (1, 2, 4 kGy) was studied. Pork meat vacuum-packed and irradiated at 2 kGy had a shelf-life of between 28-35 days at 3-5 deg. C temperature, the actual extension depending on the initial contamination. The pathogenic microorganisms were eliminated by irradiation. The microbiological quality of gas-packed and irradiated (stored at 3-5 deg. C) meat was in the first two weeks better, than that of the vacuum-packed sampled, but on the 20th day the results were better for vacuum-packed meat. Therefore, from technological and economical point of view, gas-packaging-systems are not recommended. The colour changes (pink) in the irradiated pork did not influence its quality. (author). 16 refs, 9 figs

  7. Rapidly falling costs of battery packs for electric vehicles

    Science.gov (United States)

    Nykvist, Björn; Nilsson, Måns

    2015-04-01

    To properly evaluate the prospects for commercially competitive battery electric vehicles (BEV) one must have accurate information on current and predicted cost of battery packs. The literature reveals that costs are coming down, but with large uncertainties on past, current and future costs of the dominating Li-ion technology. This paper presents an original systematic review, analysing over 80 different estimates reported 2007-2014 to systematically trace the costs of Li-ion battery packs for BEV manufacturers. We show that industry-wide cost estimates declined by approximately 14% annually between 2007 and 2014, from above US$1,000 per kWh to around US$410 per kWh, and that the cost of battery packs used by market-leading BEV manufacturers are even lower, at US$300 per kWh, and has declined by 8% annually. Learning rate, the cost reduction following a cumulative doubling of production, is found to be between 6 and 9%, in line with earlier studies on vehicle battery technology. We reveal that the costs of Li-ion battery packs continue to decline and that the costs among market leaders are much lower than previously reported. This has significant implications for the assumptions used when modelling future energy and transport systems and permits an optimistic outlook for BEVs contributing to low-carbon transport.

  8. Packing states of multilamellar vesicles in a nonionic surfactant system

    DEFF Research Database (Denmark)

    Le, T.D.; Olsson, U.; Mortensen, K.

    2001-01-01

    under shear. Here, we focused only in the MLV region, L-alpha(*), of a temperature sensitive surfactant system (C12E4-water) to investigate the packing of multilamellar vesicles as a function of temperature under constant shear. Two sets of temperature scan experiments were performed in the L...

  9. Mass transfer models analysis for the structured packings

    International Nuclear Information System (INIS)

    The models that have been developing, to understand the mechanism of the mass transfer through the structured packings, present limitations for their application, existing then uncertainty in order to use them in the chemical industrial processes. In this study the main parameters used in the mass transfer are: the hydrodynamic of the bed of the column, the geometry of the bed, physical-chemical properties of the mixture and the flow regime of the operation between the flows liquid-gas. The sensibility of each one of these parameters generate an arduous work to develop right proposals and good interpretation of the phenomenon. With the purpose of showing the importance of these parameters mentioned in the mass transfer, this work is analyzed the process of absorption for the system water-air, using the models to the structured packings in packed columns. The models selected were developed by Bravo and collaborators in 1985 and 1992, in order to determine the parameters previous mentioned for the system water-air, using a structured packing built in the National Institute of Nuclear Research. In this work is showed the results of the models application and their discussion. (Author)

  10. Packed bed heat storage: Continuum mechanics model and validation

    Science.gov (United States)

    Knödler, Philipp; Dreißigacker, Volker; Zunft, Stefan

    2016-05-01

    Thermal energy storage (TES) systems are key elements for various types of new power plant concepts. As possible cost-effective storage inventory option, packed beds of miscellaneous material come into consideration. However, high technical risks arise due to thermal expansion and shrinking of the packed bed's particles during cyclic thermal operation, possibly leading to material failure. Therefore, suitable tools for designing the heat storage system are mandatory. While particle discrete models offer detailed simulation results, the computing time for large scale applications is inefficient. In contrast, continuous models offer time-efficient simulation results but are in need of effective packed bed parameters. This work focuses on providing insight into some basic methods and tools on how to obtain such parameters and on how they are implemented into a continuum model. In this context, a particle discrete model as well as a test rig for carrying out uniaxial compression tests (UCT) is introduced. Performing of experimental validation tests indicate good agreement with simulated UCT results. In this process, effective parameters required for a continuous packed bed model were identified and used for continuum simulation. This approach is validated by comparing the simulated results with experimental data from another test rig. The presented method significantly simplifies subsequent design studies.

  11. Social Interactions Sparked by Pictorial Warnings on Cigarette Packs

    Science.gov (United States)

    Hall, Marissa G.; Peebles, Kathryn; Bach, Laura E.; Noar, Seth M.; Ribisl, Kurt M.; Brewer, Noel T.

    2015-01-01

    The Message Impact Framework suggests that social interactions may offer smokers the opportunity to process pictorial warnings on cigarette packs more deeply. We aimed to describe adult smokers’ social interactions about pictorial cigarette pack warnings in two longitudinal pilot studies. In Pilot Study 1, 30 smokers used cigarette packs with one of nine pictorial warnings for two weeks. In Pilot Study 2, 46 smokers used cigarette packs with one of five pictorial warnings for four weeks. Nearly all smokers (97%/96% in Pilot Study 1/2) talked about the warnings with other people, with the most common people being friends (67%/87%) and spouses/significant others (34%/42%). Pilot Study 2 found that 26% of smokers talked about the warnings with strangers. Discussions about the health effects of smoking and quitting smoking were more frequent during the first week of exposure to pictorial warnings than in the week prior to beginning the study (both p < 0.05). Pictorial warnings sparked social interactions about the warnings, the health effects of smoking, and quitting smoking, indicating that pictorial warnings may act as a social intervention reaching beyond the individual. Future research should examine social interactions as a potential mediator of the impact of pictorial warnings on smoking behavior. PMID:26506363

  12. Consumer preferences for front-of-pack calories labelling

    NARCIS (Netherlands)

    Kleef, van E.; Trijp, van J.C.M.; Paeps, F.; Fernández-Celemín, L.

    2008-01-01

    Objective In light of the emerging obesity pandemic, front-of-pack calories labels may be an important tool to assist consumers in making informed healthier food choices. However, there is little prior research to guide key decisions on whether caloric content should be expressed in absolute terms o

  13. Imaging of body packing: errors and medico-legal issues.

    Science.gov (United States)

    Reginelli, Alfonso; Russo, Anna; Urraro, Fabrizio; Maresca, Duilia; Martiniello, Ciro; D'Andrea, Alfredo; Brunese, Luca; Pinto, Antonio

    2015-10-01

    Body packing is the ingestion or insertion in the human body of packed illicit substances. Over the last 20 years, drug smuggling has increased global and new means of transport of narcotics have emerged. Among these, the most frequent one is the gastrointestinal tract: from mouth to anus, vagina, and ears. Cocaine is one of the most traded drugs, followed by heroin. Condoms, latex gloves, and balloons are typically used as drug packets for retention in the body. There are different radiologic modalities to detect illicit drugs in body packing: Plain radiography, computed tomography (CT), ultrasound, and magnetic resonance. Current protocols recommend the use of radiography to confirm packet retention and, in case of doubt, the use of abdominal CT scan with reduced mAs. In case of packet rupture, catastrophic effects can occur. Management of patients carrying packets of drugs is a recurrent medico-legal problem. To improve diagnostic accuracy and prevent hazardous complications, radiologists and emergency physicians should be familiar with radiologic features of body packing. The radiologist plays both a social and a medico-legal role in their assessment, and it should not be limited only to the identification of the packages but must also provide accurate information about their number and their exact location. In this review, we focus on diagnostic errors and medico-legal issues related to the radiological assessment of body packers. PMID:26063072

  14. An approximate version of the Tree Packing Conjecture

    Czech Academy of Sciences Publication Activity Database

    Böttcher, J.; Hladký, Jan; Piguet, Diana; Taraz, A.

    2016-01-01

    Roč. 211, č. 1 (2016), s. 391-446. ISSN 0021-2172 Institutional support: RVO:67985840 ; RVO:67985807 Keywords : Ringel's conjecture * Gyarfas-Lehel conjecture * Tree packing Subject RIV: BA - General Mathematics Impact factor: 0.787, year: 2014 http://link.springer.com/article/10.1007%2Fs11856-015-1277-2

  15. Frac-and-pack stimulation: Application, design, and field experience

    Energy Technology Data Exchange (ETDEWEB)

    Roodhart, L.P.; Fokker, P.A.; Davies, D.R.; Shlyapobersky, J.; Wong, G.K.

    1994-03-01

    This paper discusses the criteria for selecting wells to be frac-and-packed. The authors show how systematic study of the inflow performance can be used to assess the potential of frac-and-packed wells, to identify the controlling factors, and to optimize design parameters. They also show that fracture conductivity is often the key to successful treatment. This conductivity depends largely on proppant size; formation permeability damage around the created fracture has less effect. Appropriate allowance needs to be made for flow restrictions caused by the presence of the perforations, partial penetration, and non-Darcy effects. They describe the application of the overpressure-calibrated hydraulic fracture model in frac-and-pack treatment design, and discuss some operational considerations with reference to field examples. The full potential of this promising new completion method can be achieved only if the design is tailored to the individual well. This demands high-quality input data, which can be obtained only from a calibration test. This paper presents their strategy for frac-and-pack design, drawing on examples from field experience. They also point out several areas that the industry needs to address, such as the sizing of proppant in soft formations and the interaction between fracturing fluids and resin in resin-coated proppant.

  16. Energy landscapes, scale-free networks and Apollonian packings

    OpenAIRE

    Doye, Jonathan P. K.; Massen, Claire P.

    2006-01-01

    We review recent results on the topological properties of two spatial scale-free networks, the inherent structure and Apollonian networks. The similarities between these two types of network suggest an explanation for the scale-free character of the inherent structure networks. Namely, that the energy landscape can be viewed as a fractal packing of basins of attraction.

  17. Behaviour of L. monocytogenes in sliced, vacuum-packed mortadella

    OpenAIRE

    Bersot, Luciano dos Santos; Gillio, Cíntia; Tavolaro, Paula; Landgraf, Mariza; de Melo Franco, Bernadette Dora Gombossy; Destro, Maria Teresa

    2008-01-01

    This study evaluated the growth of naturally occurring L. monocytogenes in sliced, vacuum-packed mortadella samples during storage at 5°C until the expiration date. Tukey’s test indicated that counts of L. monocytogenes on 0, 10, 20, 30 and 40 days of storage were significantly different (p

  18. Optimizing packing fraction in granular media composed of overlapping spheres.

    Science.gov (United States)

    Roth, Leah K; Jaeger, Heinrich M

    2016-01-28

    What particle shape will generate the highest packing fraction when randomly poured into a container? In order to explore and navigate the enormous search space efficiently, we pair molecular dynamics simulations with artificial evolution. Arbitrary particle shape is represented by a set of overlapping spheres of varying diameter, enabling us to approximate smooth surfaces with a resolution proportional to the number of spheres included. We discover a family of planar triangular particles, whose packing fraction of ϕ ∼ 0.73 is among the highest experimental results for disordered packings of frictionless particles. We investigate how ϕ depends on the arrangement of spheres comprising an individual particle and on the smoothness of the surface. We validate the simulations with experiments using 3D-printed copies of the simplest member of the family, a planar particle consisting of three overlapping spheres with identical radius. Direct experimental comparison with 3D-printed aspherical ellipsoids demonstrates that the triangular particles pack exceedingly well not only in the limit of large system size but also when confined to small containers. PMID:26592541

  19. A NOTE ON MULTIFRACTAL PACKING DIMENSION OF MEASURES

    Institute of Scientific and Technical Information of China (English)

    Jinjun Li

    2009-01-01

    The relations between the multifractal packing dimension of Borel probability measures and the asymptotic behavior of the function φ*(x)=lim sup/r→0 logv(V(x, r))-qlogμ(B(x, r))/logr are discussed and some applications are given.

  20. Design of Engine-Generator Work Mode for Hybrid Electric Vehicle

    Institute of Scientific and Technical Information of China (English)

    何洪文; 余晓江; 孙逢春

    2004-01-01

    From electric circuit theory view, a system model of series hybrid electric vehicle was built which uses engine-generator and battery pack as its on-board energy source in this paper. Based on the analysis for the constant power work mode and constant bus voltage work mode of engine-generator, a third work mode was put forward which combined the advantages of constant power and constant bus voltage work modes. The new work mode is reasonable to keep the battery in good working conditions and to extend its life. Also the working conditions of engine can be bettered to get low pollution and high efficiency.

  1. Flame synthesis of carbon nano onions using liquefied petroleum gas without catalyst

    International Nuclear Information System (INIS)

    Densely agglomerated, high specific surface area carbon nano onions with diameter of 30–40 nm have been synthesized. Liquefied petroleum gas and air mixtures produced carbon nano onions in diffusion flames without catalyst. The optimized oxidant to fuel ratio which produces carbon nano onions has been found to be 0.1 slpm/slpm. The experiment yielded 70% pure carbon nano onions with a rate of 5 g/h. X-ray diffraction, high-resolution electron microscopy and Raman spectrum reveal the densely packed sp2 hybridized carbon with (002) semi-crystalline hexagonal graphite reflection. The carbon nano onions are thermally stable up to 600 °C. - Highlights: ►Flame synthesized carbon nano onions with 30–40 nm diameters. ►LPG/air, diffusion type flame used in absence of catalyst to produce nano onions. ►Carbon nano onion production rate is 5 g/hr and with 70% purity.

  2. Recovery of Dilute Acetic Acid by Catalytic Distillation Using NKC-9 as Catalyst

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhigang; LI Xiaofeng; XU Shimin; LI Xingang

    2006-01-01

    The reaction kinetics of dilute acetic acid with methanol using NKC-9 as catalyst was studied at temperatures of 308 K, 318 K, 323 K, 328 K. The kinetic model based on Langmuir-Hinshelwood rate model was derived and the activation energy was 6.13 x 104 kJ/kmol. The experiment of recovery of dilute acetic acid was conducted in a packed bed catalytic distillation column. The optimal process parameters and operational conditions determined to make up to 85.9% conversion of acetic acid are as follows:the height of catalyst bed is 1 100 mm, reflux ratio is 4: 1, and the ratio of methanol to acetic acid is 2: 1. The method can be used as a guide in industrial scale recovery of 15%-30% dilute acetic acid.

  3. Catalyst for Decomposition of Nitrogen Oxides

    Science.gov (United States)

    Schryer, David R. (Inventor); Jordan, Jeffrey D. (Inventor); Akyurtlu, Ates (Inventor); Akyurtlu, Jale (Inventor)

    2015-01-01

    This invention relates generally to a platinized tin oxide-based catalyst. It relates particularly to an improved platinized tin oxide-based catalyst able to decompose nitric oxide to nitrogen and oxygen without the necessity of a reducing gas.

  4. Use of lanthanide catalysts in air electrodes

    International Nuclear Information System (INIS)

    A review on the lanthanide catalysts suitable for the reduction catalysis of oxygen in air electrodes is presented. The kinds of lanthanide indicated to be used as catalysts of oxygen reduction are shown. (A.R.H.)

  5. Novel Fischer-Tropsch catalysts. [DOE patent

    Science.gov (United States)

    Vollhardt, K.P.C.; Perkins, P.

    Novel compounds are described which are used as improved Fischer-Tropsch catalysts particularly for the conversion of CO + H/sub 2/ to gaseous and liquid hydrocarbons at milder conditions than with prior catalysts.

  6. Catalytic flash pyrolysis of oil-impregnated-wood and jatropha cake using sodium based catalysts

    NARCIS (Netherlands)

    Ali Imran, A.; Bramer, E.A.; Seshan, K.; Brem, G.

    2016-01-01

    Catalytic pyrolysis of wood with impregnated vegetable oil was investigated and compared with catalytic pyrolysis of jatropha cake making use of sodium based catalysts to produce a high quality bio-oil. The catalytic pyrolysis was carried out in two modes: in-situ catalytic pyrolysis and post treatm

  7. Catalyst Degradation in High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    DEFF Research Database (Denmark)

    Cleemann, Lars Nilausen; Buazar, F.; Li, Qingfeng; Jensen, Jens Oluf; Pan, Chao; Steenberg, T.; Dai, S.; Bjerrum, Niels J.

    2013-01-01

    Degradation of carbon supported platinum catalysts is a major failure mode for the long term durability of high temperature proton exchange membrane fuel cells based on phosphoric acid doped polybenzimidazole membranes. With Vulcan carbon black as a reference, thermally treated carbon black and...

  8. Filling the void in confined polymer nematics: phase transitions in a minimal model of dsDNA packing

    OpenAIRE

    Shin, Homin; Grason, Gregory M.

    2011-01-01

    Inspired to understand the complex spectrum of space-filling organizations the dsDNA genome within the capsid of bacterial viruses, we study a minimal, coarse-grained model of single chains densely-packed into a finite spherical volume. We build the three basic elements of the model--i) the absence of chain ends ii) the tendency of parallel-strand alignment and iii) a preference of uniform areal density of chain segments--into a polymer nematic theory for confined chains. Given the geometric ...

  9. Biomass processing over gold catalysts

    CERN Document Server

    Simakova, Olga A; Murzin, Dmitry Yu

    2013-01-01

    The book describes the valorization of biomass-derived compounds over gold catalysts. Since biomass is a rich renewable feedstock for diverse platform molecules, including those currently derived from petroleum, the interest in various transformation routes has become intense. Catalytic conversion of biomass is one of the main approaches to improving the economic viability of biorefineries.  In addition, Gold catalysts were found to have outstanding activity and selectivity in many key reactions. This book collects information about transformations of the most promising and important compounds

  10. Rhenium Nanochemistry for Catalyst Preparation

    Directory of Open Access Journals (Sweden)

    Vadim G. Kessler

    2012-08-01

    Full Text Available The review presents synthetic approaches to modern rhenium-based catalysts. Creation of an active center is considered as a process of obtaining a nanoparticle or a molecule, immobilized within a matrix of the substrate. Selective chemical routes to preparation of particles of rhenium alloys, rhenium oxides and the molecules of alkyltrioxorhenium, and their insertion into porous structure of zeolites, ordered mesoporous MCM matrices, anodic mesoporous alumina, and porous transition metal oxides are considered. Structure-property relationships are traced for these catalysts in relation to such processes as alkylation and isomerization, olefin metathesis, selective oxidation of olefins, methanol to formaldehyde conversion, etc.

  11. Quick Guide to Flash Catalyst

    CERN Document Server

    Elmansy, Rafiq

    2011-01-01

    How do you transform user interface designs created in Photoshop or Illustrator into interactive web pages? It's easier than you think. This guide shows you how to use Adobe Flash Catalyst to create interactive UIs and website wireframes for Rich Internet Applications-without writing a single line of code. Ideal for web designers, this book introduces Flash Catalyst basics with detailed step-by-step instructions and screenshots that illustrate every part of the process. You'll learn hands-on how to turn your static design or artwork into working user interfaces that can be implemented in Fla

  12. Colloidal nanoparticles as catalysts and catalyst precursors for nitrite hydrogenation

    NARCIS (Netherlands)

    Zhao, Yingnan

    2015-01-01

    The most distinguished advantage to use colloidal methods for catalyst preparation is that the size and the shape of nanoparticles can be manipulated easily under good control, which is normally difficult to achieve by using traditional methods, such as impregnation and precipitation. This facilitat

  13. Catalyst-assisted Probabilistic Entanglement Transformation

    OpenAIRE

    Feng, Yuan; Duan, Runyao; Ying, Mingsheng

    2004-01-01

    We are concerned with catalyst-assisted probabilistic entanglement transformations. A necessary and sufficient condition is presented under which there exist partial catalysts that can increase the maximal transforming probability of a given entanglement transformation. We also design an algorithm which leads to an efficient method for finding the most economical partial catalysts with minimal dimension. The mathematical structure of catalyst-assisted probabilistic transformation is carefully...

  14. Cotter's new plant diets on spent catalysts

    International Nuclear Information System (INIS)

    Cotter Corp.'s new 60-tpd spent-catalyst processing plant that recovers molybdenum, nickel, tungsten and vanadium products from spent catalysts is described. The company entered the business as a sideline to its main activity--the mining and processing of uranium ore. The spent-catalyst plant contains ammonium carbonate and sodium hydroxide leach circuits to provide the versatility required to recover various metals from a variety of spent catalysts

  15. Polymer-bound rhodium hydroformylation catalysts

    OpenAIRE

    Jongsma, Tjeerd

    1992-01-01

    Homogeneous catalysts are superior in activity, selectivity as well as specificity, but heterogeneous catalyst are often preferred in industrial processes, because of their good recoverability and their applicability in continuous flow reactors. It would be of great environmental, commercial and scientific interest to combine the advantages of both catalysts. A route to achieve this goal is to immobilize a potent homogeneous catalyst onto an insoluble resin. In this thesis we have used solubl...

  16. EFFECTS OF CATALYST MORPHOLOGY ON HYDROTREATING REACTIONS

    OpenAIRE

    TYE CHING THIAN

    2008-01-01

    Due to the new environmental regulations for fuel quality, refineries need to process cleaner fuel. This requires an improvement in performance of hydrotreating catalysts. Improvements in catalyst activity require knowledge of the relationships between catalyst morphology and activity. Molybdenum sulfide, the generally agreed catalysts that give the best performance in hydrocracking and hydrotreating was investigated for its morphology effects on hydrotreating reactions. Three types of MoS2 c...

  17. Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gangwal, S.; Jothimurugesan, K.

    1999-07-27

    A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption process, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gases from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or passivating the heavy metals on the spent FCC catalyst as an intermediate step.

  18. Attrition resistant catalysts and sorbents based on heavy metal poisoned FCC catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Gangwal, Santosh (Cary, NC); Jothimurugesan, Kandaswamy (Hampton, VA)

    1999-01-01

    A heavy metal poisoned, spent FCC catalyst is treated by chemically impregnating the poisoned catalyst with a new catalytic metal or metal salt to provide an attrition resistant catalyst or sorbent for a different catalytic or absorption processes, such as catalysts for Fischer-Tropsh Synthesis, and sorbents for removal of sulfur gasses from fuel gases and flue-gases. The heavy metal contaminated FCC catalyst is directly used as a support for preparing catalysts having new catalytic properties and sorbents having new sorbent properties, without removing or "passivating" the heavy metals on the spent FCC catalyst as an intermediate step.

  19. Alternative alkali resistant deNOx catalysts

    DEFF Research Database (Denmark)

    Putluru, Siva Sankar Reddy; Kristensen, Steffen Buus; Due-Hansen, Johannes;

    2012-01-01

    Alternative alkali resistant deNOx catalysts were prepared using three different supports ZrO2, TiO2 and Mordenite zeolite. The majority of the catalysts were prepared by incipient wetness impregnation of a commercial support, with vanadium, copper or iron precursor, one catalyst was prepared by...

  20. deNOx catalysts for biomass combustion

    DEFF Research Database (Denmark)

    Kristensen, Steffen Buus

    , however the alkali in biomass complicate matters. Alkali in biomass severely deactivates the catalyst used for the selective catalytic reduction in matter of weeks, hence a more alkali resistant catalyst is needed. In the thesis a solution to the problem is presented, the nano particle deNOx catalyst...

  1. Silver doped catalysts for treatment of exhaust

    Energy Technology Data Exchange (ETDEWEB)

    Park, Paul Worn (Peoria, IL); Hester, Virgil Raymond (Edelstein, IL); Ragle, Christie Susan (Havana, IL); Boyer, Carrie L. (Shiloh, IL)

    2009-06-02

    A method of making an exhaust treatment element includes washcoating a substrate with a slurry that includes a catalyst support material. At least some of the catalyst support material from the slurry may be transferred to the substrate, and silver metal (Ag) is dispersed within the catalyst support material.

  2. Catalyst for selective oxidation of hydrocarbons

    OpenAIRE

    Álvaro Rodríguez, Mercedes; Amarajothi, Dhakshinamoorthy; García Gómez, Hermenegildo

    2010-01-01

    [EN] The present invention relates to a solid catalyst that includes a metal-organic reticular pattem and an agent promoting the generation of radicals, to a method for obtaining said catalyst and to the use thereof as a catalyst in the selective aerobic oxidation reaction ofhydrocarbons.

  3. Efficient epoxidation of propene using molecular catalysts

    DEFF Research Database (Denmark)

    Markovits, Iulius I. E.; Anthofer, Michael H.; Kolding, Helene; Cokoja, Mirza; Pöthig, Alexander; Raba, Andreas; Herrmann, Wolfgang A.; Fehrmann, Rasmus; Kühn, Fritz E.

    2014-01-01

    The epoxidation of propene is performed in homogeneous phase using various molecular catalysts and H2O2 or tert-butyl hydroperoxide as oxidants. A comparison between some molybdenum catalysts and methyltrioxorhenium (MTO) shows that the well known Re catalyst is the best among the examined...

  4. Intrinsic Selectivity and Structure Sensitivity of Rhodium Catalysts for C(2+) Oxygenate Production.

    Science.gov (United States)

    Yang, Nuoya; Medford, Andrew J; Liu, Xinyan; Studt, Felix; Bligaard, Thomas; Bent, Stacey F; Nørskov, Jens K

    2016-03-23

    Synthesis gas (CO + H2) conversion is a promising route to converting coal, natural gas, or biomass into synthetic liquid fuels. Rhodium has long been studied as it is the only elemental catalyst that has demonstrated selectivity to ethanol and other C2+ oxygenates. However, the fundamentals of syngas conversion over rhodium are still debated. In this work a microkinetic model is developed for conversion of CO and H2 into methane, ethanol, and acetaldehyde on the Rh (211) and (111) surfaces, chosen to describe steps and close-packed facets on catalyst particles. The model is based on DFT calculations using the BEEF-vdW functional. The mean-field kinetic model includes lateral adsorbate-adsorbate interactions, and the BEEF-vdW error estimation ensemble is used to propagate error from the DFT calculations to the predicted rates. The model shows the Rh(211) surface to be ∼6 orders of magnitude more active than the Rh(111) surface, but highly selective toward methane, while the Rh(111) surface is intrinsically selective toward acetaldehyde. A variety of Rh/SiO2 catalysts are synthesized, tested for catalytic oxygenate production, and characterized using TEM. The experimental results indicate that the Rh(111) surface is intrinsically selective toward acetaldehyde, and a strong inverse correlation between catalytic activity and oxygenate selectivity is observed. Furthermore, iron impurities are shown to play a key role in modulating the selectivity of Rh/SiO2 catalysts toward ethanol. The experimental observations are consistent with the structure-sensitivity predicted from theory. This work provides an improved atomic-scale understanding and new insight into the mechanism, active site, and intrinsic selectivity of syngas conversion over rhodium catalysts and may also guide rational design of alloy catalysts made from more abundant elements. PMID:26958997

  5. Berreman mode and epsilon near zero mode.

    Science.gov (United States)

    Vassant, Simon; Hugonin, Jean-Paul; Marquier, Francois; Greffet, Jean-Jacques

    2012-10-01

    In this paper, we discuss the existence of an electromagnetic mode propagating in a thin dielectric film deposited on a metallic film at the particular frequency such that the dielectric permittivity vanishes. We discuss the remarkable properties of this mode in terms of extreme subwavelength mode confinment and its potential applications. We also discuss the link between this mode, the IR absorption peak on a thin dielectric film known as Berreman effect and the surface phonon polariton mode at the air/dielectric interface. Finally, we establish a connection with the polarization shift occuring in quantum wells. PMID:23188363

  6. Potent inhibition of mandelate racemase by a fluorinated substrate-product analogue with a novel binding mode.

    Science.gov (United States)

    Nagar, Mitesh; Lietzan, Adam D; St Maurice, Martin; Bearne, Stephen L

    2014-02-25

    Mandelate racemase (MR) from Pseudomonas putida catalyzes the Mg(2+)-dependent 1,1-proton transfer that interconverts the enantiomers of mandelate. Because trifluorolactate is also a substrate of MR, we anticipated that replacing the phenyl rings of the competitive, substrate-product analogue inhibitor benzilate (Ki = 0.7 mM) with trifluoromethyl groups might furnish an inhibitor. Surprisingly, the substrate-product analogue 3,3,3-trifluoro-2-hydroxy-2-(trifluoromethyl)propanoate (TFHTP) was a potent competitive inhibitor [Ki = 27 ± 4 μM; cf. Km = 1.2 mM for both (R)-mandelate and (R)-trifluorolactate]. To understand the origins of this high binding affinity, we determined the X-ray crystal structure of the MR-TFHTP complex to 1.68 Å resolution. Rather than chelating the active site Mg(2+) with its glycolate moiety, like other ground state analogues, TFHTP exhibited a novel binding mode with the two trifluoromethyl groups closely packed against the 20s loop and the carboxylate bridging the two active site Brønsted acid-base catalysts Lys 166 and His 297. Recognizing that positioning a carboxylate between the Brønsted acid-base catalysts could yield an inhibitor, we showed that tartronate was a competitive inhibitor of MR (Ki = 1.8 ± 0.1 mM). The X-ray crystal structure of the MR-tartronate complex (1.80 Å resolution) revealed that the glycolate moiety of tartronate chelated the Mg(2+) and that the carboxylate bridged Lys 166 and His 297. Models of tartronate in monomers A and B of the crystal structure mimicked the binding orientations of (S)-mandelate and that anticipated for (R)-mandelate, respectively. For the latter monomer, the 20s loop appeared to be disordered, as it also did in the X-ray structure of the MR triple mutant (C92S/C264S/K166C) complexed with benzilate, which was determined to 1.89 Å resolution. These observations indicate that the 20s loop likely undergoes a significant conformational change upon binding (R)-mandelate. In general, our

  7. Perovskite catalysts for oxidative coupling

    Science.gov (United States)

    Campbell, Kenneth D.

    1991-01-01

    Perovskites of the structure A.sub.2 B.sub.2 C.sub.3 O.sub.10 are useful as catalysts for the oxidative coupling of lower alkane to heavier hydrocarbons. A is alkali metal; B is lanthanide or lanthanum, cerium, neodymium, samarium, praseodymium, gadolinium or dysprosium; and C is titanium.

  8. Biodiesel production using heterogenous catalyst

    Science.gov (United States)

    The current transesterification of triacylglycerides (TAG) to produce biodiesel is based on the homogenous catalyst method using strong base such as hydroxides or methoxides. However, this method results in a number of problems: (1) acid pre-treatment is required of feedstocks high in free fatty ac...

  9. Part I: A Comparative Thermal Aging Study on the Regenerability of Rh/Al2O3 and Rh/CexOy-ZrO2 as Model Catalysts for Automotive Three Way Catalysts

    Directory of Open Access Journals (Sweden)

    Qinghe Zheng

    2015-10-01

    Full Text Available The rhodium (Rh component in automotive three way catalysts (TWC experiences severe thermal deactivation during fuel shutoff, an engine mode (e.g., at downhill coasting used for enhancing fuel economy. In a subsequent switch to a slightly fuel rich condition, in situ catalyst regeneration is accomplished by reduction with H2 generated through steam reforming catalyzed by Rh0 sites. The present work reports the effects of the two processes on the activity and properties of 0.5% Rh/Al2O3 and 0.5% Rh/CexOy-ZrO2 (CZO as model catalysts for Rh-TWC. A very brief introduction of three way catalysts and system considerations is also given. During simulated fuel shutoff, catalyst deactivation is accelerated with increasing aging temperature from 800 °C to 1050 °C. Rh on a CZO support experiences less deactivation and faster regeneration than Rh on Al2O3. Catalyst characterization techniques including BET surface area, CO chemisorption, TPR, and XPS measurements were applied to examine the roles of metal-support interactions in each catalyst system. For Rh/Al2O3, strong metal-support interactions with the formation of stable rhodium aluminate (Rh(AlO2y complex dominates in fuel shutoff, leading to more difficult catalyst regeneration. For Rh/CZO, Rh sites were partially oxidized to Rh2O3 and were relatively easy to be reduced to active Rh0 during regeneration.

  10. Toward Molecular Catalysts by Computer

    Energy Technology Data Exchange (ETDEWEB)

    Raugei, Simone; DuBois, Daniel L.; Rousseau, Roger J.; Chen, Shentan; Ho, Ming-Hsun; Bullock, R. Morris; Dupuis, Michel

    2015-02-17

    Rational design of molecular catalysts requires a systematic approach to designing ligands with specific functionality and precisely tailored electronic and steric properties. It then becomes possible to devise computer protocols to predict accurately the required properties and ultimately to design catalysts by computer. In this account we first review how thermodynamic properties such as oxidation-reduction potentials (E0), acidities (pKa), and hydride donor abilities (ΔGH-) form the basis for a systematic design of molecular catalysts for reactions that are critical for a secure energy future (hydrogen evolution and oxidation, oxygen and nitrogen reduction, and carbon dioxide reduction). We highlight how density functional theory allows us to determine and predict these properties within “chemical” accuracy (~ 0.06 eV for redox potentials, ~ 1 pKa unit for pKa values, and ~ 1.5 kcal/mol for hydricities). These quantities determine free energy maps and profiles associated with catalytic cycles, i.e. the relative energies of intermediates, and help us distinguish between desirable and high-energy pathways and mechanisms. Good catalysts have flat profiles that avoid high activation barriers due to low and high energy intermediates. We illustrate how the criterion of a flat energy profile lends itself to the prediction of design points by computer for optimum catalysts. This research was carried out in the Center for Molecular Electro-catalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences. Pacific Northwest National Laboratory (PNNL) is operated for the DOE by Battelle.

  11. Catalysis Science Initiative: Catalyst Design by Discovery Informatics

    Energy Technology Data Exchange (ETDEWEB)

    Delgass, William Nicholas [Purdue Univ., West Lafayette, IN (United States). Chemical Engineering; Abu-Omar, Mahdi [Purdue Univ., West Lafayette, IN (United States) Department of Chemistry; Caruthers, James [Purdue Univ., West Lafayette, IN (United States). Chemical Engineering; Ribeiro, Fabio [Purdue Univ., West Lafayette, IN (United States). Chemical Engineering; Thomson, Kendall [Purdue Univ., West Lafayette, IN (United States). Chemical Engineering; Schneider, William [Univ. of Notre Dame, IN (United States)

    2016-07-08

    Catalysts selectively enhance the rates of chemical reactions toward desired products. Such reactions provide great benefit to society in major commercial sectors such as energy production, protecting the environment, and polymer products and thereby contribute heavily to the country’s gross national product. Our premise is that the level of fundamental understanding of catalytic events at the atomic and molecular scale has reached the point that more predictive methods can be developed to shorten the cycle time to new processes. The field of catalysis can be divided into two regimes: heterogeneous and homogeneous. For the heterogeneous catalysis regime, we have used the water-gas shift (WGS) reaction (CO + H2O + CO2 + H2O) over supported metals as a test bed. Detailed analysis and strong coupling of theory with experiment have led to the following conclusions: • The sequence of elementary steps goes through a COOH intermediate • The CO binding energy is a strong function of coverage of CO adsorbed on the surface in many systems • In the case of Au catalysts, the CO adsorption is generally too weak on surface with close atomic packing, but the enhanced binding at corner atoms (which are missing bonding partners) of cubo-octahedral nanoparticles increases the energy to a near optimal value and produces very active catalysts. • Reaction on the metal alone cannot account for the experimental results. The reaction is dual functional with water activation occurring at the metal-support interface. It is clear from our work that the theory component is essential, not only for prediction of new systems, but also for reconciling data and testing hypotheses regarding potential descriptors. Particularly important is the finding that the interface between nano-sized metal particles and the oxides that are used to support them represent a new state of matter in the sense that the interfacial bonding perturbs the chemical state of both metals atoms and the support

  12. Strategies for catalyst development: possibilities of the ``rational approach`` illustrated with partial oxidation reactions

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, W.; Schedel-Niedrig, T.; Schloegl, R. [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (Germany). Abt. Oberflaechenphysik

    1998-12-31

    The paper discusses two petrochemical selective oxidation reactions namely the practised formation of styrene (STY) and the desired oxidative functionalisation of propane. The present knowledge about the mode of operation of oxide catalysts is critically considered. The dehydrogenation of ethylbenzene (EB) should be described by an oxidehydration with water acting as oxidant. The potential role of the coke formed during catalytic reaction as co-catalyst will be discussed. Selective oxidation is connected with the participation of lattice oxygen mechanism which transforms unselective gas phase oxygen into selective oxygen. The atomistic description of this process is still quite unclear as well as the electron structural properties of the activated oxygen atom. The Role of solid state acidity as compared to the role of lattice oxygen is much less well investigated modern multiphase-multielement oxide (MMO) catalysts. The rationale is that the significant efforts made to improve current MMO systems by chemical modifications can be very much more fruitful when in a first step the mode of action of a catalyst is clarified on the basis of suitable experiments. Such time-consuming experiments at the beginning of a campaign for catalyst improvement pay back their investment in later stages of the project when strategies of chemical development can be derived on grounds of understanding. (orig.)

  13. Treatment of azo dye-containing wastewater by a Fenton-like process in a continuous packed-bed reactor filled with activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Isabel; Matos, Luis C. [Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Duarte, Filipa [Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); LEPAE - Laboratory for Process, Environmental and Energy Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto (Portugal); Maldonado-Hodar, F.J. [Department of Inorganic Chemistry, Faculty of Sciences, University of Granada, Av. Fuentenueva, 18071 Granada (Spain); Mendes, Adelio [Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); LEPAE - Laboratory for Process, Environmental and Energy Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto (Portugal); Madeira, Luis M., E-mail: mmadeira@fe.up.pt [Chemical Engineering Department, Faculty of Engineering, University of Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); LEPAE - Laboratory for Process, Environmental and Energy Engineering, Department of Chemical Engineering, Faculty of Engineering, University of Porto, Porto (Portugal)

    2012-10-30

    Highlights: Black-Right-Pointing-Pointer Oxidation with the Fenton's reagent was carried out in a packed-bed reactor. Black-Right-Pointing-Pointer The packed-bed was filled with iron-impregnated activated carbon. Black-Right-Pointing-Pointer The increment of temperature increases the Chicago Sky Blue removal and mineralization. Black-Right-Pointing-Pointer The values of iron leaching were below 0.4 ppm in the outlet effluent. Black-Right-Pointing-Pointer It was possible to reach a dye conversion of 88% in steady-state. - Abstract: In this work, oxidation with a Fenton-like process of a dye solution was carried out in a packed-bed reactor. Activated carbon Norit RX 3 Extra was impregnated with ferrous sulfate and used as catalyst (7 wt.% of iron). The effect of the main operating conditions in the Chicago Sky Blue (CSB) degradation was analyzed. It was found that the increase in temperature leads to a higher removal of the dye and an increased mineralization. However, it also increases the iron leaching, but the values observed were below 0.4 ppm (thus, far below European Union limits). It was possible to reach, at steady-state, a dye conversion of 88%, with a total organic carbon (TOC) removal of ca. 47%, being the reactor operated at 50 Degree-Sign C, pH 3, W{sub cat}/Q = 4.1 g min mL{sup -1} (W{sub cat} is the mass of catalyst and Q the total feed flow rate) and a H{sub 2}O{sub 2} feed concentration of 2.25 mM (for a CSB feed concentration of 0.012 mM). The same performance was reached in three consecutive cycles.

  14. Treatment of azo dye-containing wastewater by a Fenton-like process in a continuous packed-bed reactor filled with activated carbon

    International Nuclear Information System (INIS)

    Highlights: ► Oxidation with the Fenton's reagent was carried out in a packed-bed reactor. ► The packed-bed was filled with iron-impregnated activated carbon. ► The increment of temperature increases the Chicago Sky Blue removal and mineralization. ► The values of iron leaching were below 0.4 ppm in the outlet effluent. ► It was possible to reach a dye conversion of 88% in steady-state. - Abstract: In this work, oxidation with a Fenton-like process of a dye solution was carried out in a packed-bed reactor. Activated carbon Norit RX 3 Extra was impregnated with ferrous sulfate and used as catalyst (7 wt.% of iron). The effect of the main operating conditions in the Chicago Sky Blue (CSB) degradation was analyzed. It was found that the increase in temperature leads to a higher removal of the dye and an increased mineralization. However, it also increases the iron leaching, but the values observed were below 0.4 ppm (thus, far below European Union limits). It was possible to reach, at steady-state, a dye conversion of 88%, with a total organic carbon (TOC) removal of ca. 47%, being the reactor operated at 50 °C, pH 3, Wcat/Q = 4.1 g min mL−1 (Wcat is the mass of catalyst and Q the total feed flow rate) and a H2O2 feed concentration of 2.25 mM (for a CSB feed concentration of 0.012 mM). The same performance was reached in three consecutive cycles.

  15. Hydroprocessing using regenerated spent heavy hydrocarbon catalyst

    International Nuclear Information System (INIS)

    This patent describes a process for hydroprocessing a hydrocarbon feedstock. It comprises: contacting the feedstock with hydrogen under hydroprocessing conditions with a hydroprocessing catalyst wherein the hydroprocessing catalyst contains a total contaminant metals build-up of greater than about 4 wt. % nickel plus vanadium, a hydrogenation component selected from the group consisting of Group VIB metals and Group VIII metals and is regenerated spent hydroprocessing catalyst regenerated by a process comprising the steps: partially decoking the spent catalyst in an initial coke-burning step; impregnating the partially decoked catalyst with a Group IIA metal-containing impregnation solution; and decoking the impregnated catalyst in a final coke-burning step wherein the impregnated catalyst is contacted with an oxygen-containing gas at a temperature of about 600 degrees F to about 1400 degrees F

  16. Autothermal reforming catalyst having perovskite structure

    Science.gov (United States)

    Krumpel, Michael; Liu, Di-Jia

    2009-03-24

    The invention addressed two critical issues in fuel processing for fuel cell application, i.e. catalyst cost and operating stability. The existing state-of-the-art fuel reforming catalyst uses Rh and platinum supported over refractory oxide which add significant cost to the fuel cell system. Supported metals agglomerate under elevated temperature during reforming and decrease the catalyst activity. The catalyst is a perovskite oxide or a Ruddlesden-Popper type oxide containing rare-earth elements, catalytically active firs row transition metal elements, and stabilizing elements, such that the catalyst is a single phase in high temperature oxidizing conditions and maintains a primarily perovskite or Ruddlesden-Popper structure under high temperature reducing conditions. The catalyst can also contain alkaline earth dopants, which enhance the catalytic activity of the catalyst, but do not compromise the stability of the perovskite structure.

  17. Integrating packing and distribution problems and optimization through mathematical programming

    Directory of Open Access Journals (Sweden)

    Fabio Miguel

    2016-06-01

    Full Text Available This paper analyzes the integration of two combinatorial problems that frequently arise in production and distribution systems. One is the Bin Packing Problem (BPP problem, which involves finding an ordering of some objects of different volumes to be packed into the minimal number of containers of the same or different size. An optimal solution to this NP-Hard problem can be approximated by means of meta-heuristic methods. On the other hand, we consider the Capacitated Vehicle Routing Problem with Time Windows (CVRPTW, which is a variant of the Travelling Salesman Problem (again a NP-Hard problem with extra constraints. Here we model those two problems in a single framework and use an evolutionary meta-heuristics to solve them jointly. Furthermore, we use data from a real world company as a test-bed for the method introduced here.

  18. GravitinoPack and late decays involving gravitinos

    CERN Document Server

    Eberl, Helmut

    2015-01-01

    In this talk, we present the package GravitinoPack that calculates decays of unstable supersymmetric particles, involving gravitinos in the final or initial state. If the gravitino is the dark matter particle and therefore stable, the package calculates the decays of the lightest neutralino, and the lighter stau or stop NLSP into the gravitino LSP and one or two Standard Model particles. On the other hand, assuming that the gravitino is unstable, GravitinoPack calculates all its two-body and the three-body decay widths to the neutralino LSP and Standard Model particles. Since all these decays, involving the gravitino, are of gravitational nature, the lifetime of the decaying particle can be of the order of seconds are more, hence called "late decays". The precise knowledge of all these partial decay widths enables the user to apply accurately the relevant cosmological constraints.

  19. Packing properties 1-alkanols and alkanes in a phospholipid membrane

    DEFF Research Database (Denmark)

    Westh, Peter

    2006-01-01

    We have used vibrating tube densitometry to investigate the packing properties of four alkanes and a homologous series of ten alcohols in fluid-phase membranes of dimyristoyl phosphatidylcholine (DMPC). It was found that the volume change of transferring these compounds from their pure states into...... the membrane, Vm(puremem), was positive for small (C4-C6) 1-alkanols while it was negative for larger alcohols and all alkanes. The magnitude of Vm(puremem) ranged from about +4 cm3/mol for alcohols with an alkyl chain about half the length of the fatty acids of DMPC, to -10 to -15 cm3/mol for the...... alkanes and long chain alcohols. On the basis of these observations, previously published information on the structure of the membrane-solute complexes and the free volume properties of (pure) phospholipid membranes, we suggest that two effects dominate the packing properties of hydrophobic solutes in...

  20. Simulated Annealing Algorithm and Its Application in Irregular Polygons Packing

    Institute of Scientific and Technical Information of China (English)

    段国林; 王彩红; 张健楠

    2003-01-01

    Two-dimensional irregular polygons packing problem is very difficult to be solved in traditional optimal way.Simulated annealing(SA)algorithm is a stochastic optimization technique that can be used to solve packing problems.The whole process of SA is introduced firstly in this paper. An extended neighborhood searching method in SA is mainly analyzed. A general module of SA algorithm is given and used to lay out the irregular polygons. The judgment of intersection and other constrains of irregular polygons are analyzed. Then an example that was used in the paper of Stefan Jakobs is listed.Results show that this SA algorithm shortens the computation time and improves the solution.

  1. Construction of optimal supersaturated designs by the packing method

    Institute of Scientific and Technical Information of China (English)

    FANG Kaitai; GE Gennian; LIU Minqian

    2004-01-01

    A supersaturated design is essentially a factorial design with the equal occurrence of levels property and no fully aliased factors in which the number of main efits potential in factor screening experiments. A packing design is an important object in combinatorial design theory. In this paper, a strong link between the two apparently unrelated kinds of designs is shown. Several criteria for comparing supersaturated designs are proposed, their properties and connections with other existing criteria are discussed.A combinatorial approach, called the packing method, for constructing optimal supersaturated designs is presented, and properties of the resulting designs are also investigated.Comparisons between the new designs and other existing designs are given, which show that our construction method and the newly constructed designs have good properties.

  2. Liquid Axial Mixing in Packed Tower at Elevated Pressure

    Institute of Scientific and Technical Information of China (English)

    唐忠利; 张鹏; 等

    2003-01-01

    Liquid phase axial mixing was measured with the tracer technique in a packed column with inner diameter of 0.15m,in which the structured packing,Mellapak 350Y,was installed.Tap water as the liquid phase flowed down through the column and stagnant gas was at elevated pressure ranging from atmospheric to 2.0MPa.The model parameters of Bo andθwere estimated with the least square method in the time domain.As liquid flow rate was increased,the liquid axial mixing decreased.under our experimental conditions,the effect of pressure on Bo number on single liquid phase was negligible,and eddy diffusion was believed to be the primary cause of axial mixing in liquid phase.

  3. Mobility of icy sand packs, with application to Martian permafrost

    Science.gov (United States)

    Durham, W.B.; Pathare, A.V.; Stern, L.A.; Lenferink, H.J.

    2009-01-01

    [1] The physical state of water on Mars has fundamental ramifications for both climatology and astrobiology. The widespread presence of "softened" Martian landforms (such as impact craters) can be attributed to viscous creep of subsurface ground ice. We present laboratory experiments designed to determine the minimum amount of ice necessary to mobilize topography within Martian permafrost. Our results show that the jammed-to-mobile transition of icy sand packs neither occurs at fixed ice content nor is dependent on temperature or stress, but instead correlates strongly with the maximum dry packing density of the sand component. Viscosity also changes rapidly near the mobility transition. The results suggest a potentially lower minimum volatile inventory for the impact-pulverized megaregolith of Mars. Furthermore, the long-term preservation of partially relaxed craters implies that the ice content of Martian permafrost has remained close to that at the mobility transition throughout Martian history. Copyright 2009 by the American Geophysical Union.

  4. The fine triangle intersections for maximum kite packings

    OpenAIRE

    Zhang, Guizhi; Chang, Yanxun; Feng, Tao

    2012-01-01

    In this paper the fine triangle intersection problem for a pair of maximum kite packings is investigated. Let $Fin(v)={(s,t):$ $\\exists$ a pair of maximum kite packings of order $v$ intersecting in $s$ blocks and $s+t$ triangles$}$. Let $Adm(v)={(s,t): s+t\\leq b_v, s,t$ are non-negative integers$}$, where $b_v=\\lfloor v(v-1)/8\\rfloor$. It is established that $Fin(v)= Adm(v)\\setminus {(b_v-1,0),(b_v-1,1)}$ for any integer $v\\equiv 0,1 ({\\rm mod} 8)$ and $v\\geq 8$; $Fin(v)=Adm(v)$ for any integ...

  5. Packing Different Cuboids with Rotations and Spheres into a Cuboid

    Directory of Open Access Journals (Sweden)

    Y. G. Stoyan

    2014-01-01

    Full Text Available The paper considers a packing optimization problem of different spheres and cuboids into a cuboid of the minimal height. Translations and continuous rotations of cuboids are allowed. In the paper, we offer a way of construction of special functions (Φ-functions describing how rotations can be dealt with. These functions permit us to construct the mathematical model of the problem as a classical mathematical programming problem. Basic characteristics of the mathematical model are investigated. When solving the problem, the characteristics allow us to apply a number of original and state-of-the-art efficient methods of local and global optimization. Numerical examples of packing from 20 to 300 geometric objects are given.

  6. Packing of Fruit Fly Parasitoids for Augmentative Releases

    OpenAIRE

    Pablo Montoya; Lía Ruiz; Jorge Cancino

    2012-01-01

    The successful application of Augmentative Biological Control (ABC) to control pest fruit flies (Diptera: Tephritidae) confronts two fundamental requirements: (1) the establishment of efficient mass rearing procedures for the species to be released, and (2) the development of methodologies for the packing and release of parasitoids that permit a uniform distribution and their optimal field performance under an area-wide approach. Parasitoid distributions have been performed by ground and by a...

  7. Generic Unpacking of Self-modifying, Aggressive, Packed Binary Programs

    OpenAIRE

    Bania, Piotr

    2009-01-01

    Nowadays most of the malware applications are either packed or protected. This techniques are applied especially to evade signature based detectors and also to complicate the job of reverse engineers or security analysts. The time one must spend on unpacking or decrypting malware layers is often very long and in fact remains the most complicated task in the overall process of malware analysis. In this report author proposes MmmBop as a relatively new concept of using dynamic binary instrument...

  8. Pulp moulding machines for the production of packing paper elements

    OpenAIRE

    Lukić Ljubomir S.; Krgović Milorad V.; Jaraković Ilija M.

    2005-01-01

    Paper pulp molds are now commonly applied in the technology of modern packing for a wide range of products. The technological process of producing the paper molds has three basic phases: paper pulp preparation, in which water and waste paper are the basic raw materials, the formation of product in tool pulp moulding machines and process drying. The firm "SERVOTEH" from Belgrade has developed various pulp moulding machines for different operating conditions (manual, semiautomatic and automatic...

  9. QUALITY ASSESSMENT OF EGGS PACKED UNDER MODIFIED ATMOSPHERE

    OpenAIRE

    Aline Giampietro-Ganeco; Hirasilva Borba; Aline Mary Scatolini-Silva; Marcel Manente Boiago; Pedro Alves de Souza; Juliana Lolli Malagoli de Mello

    2015-01-01

    Eggs are perishable foods and lose quality quickly if not stored properly. From the moment of posture to the marketing of egg, quality loss occurs through gas exchange and water through the pores of the shell with the external environment and thus, studies involving modified atmosphere packaging are extremely important. The aim of the present study is to assess the internal quality of eggs packed under modified atmosphere and stored at room temperature. Six hundred and twelve fresh commercial...

  10. A genetic programming hyper-heuristic approach to automated packing

    OpenAIRE

    Hyde, Matthew

    2010-01-01

    This thesis presents a programme of research which investigated a genetic programming hyper-heuristic methodology to automate the heuristic design process for one, two and three dimensional packing problems. Traditionally, heuristic search methodologies operate on a space of potential solutions to a problem. In contrast, a hyper-heuristic is a heuristic which searches a space of heuristics, rather than a solution space directly. The majority of hyper-heuristic research papers, so far, hav...

  11. Controlling droplet incubation using close-packed plug flow

    OpenAIRE

    Mary, Pascaline; Abate, Adam R.; Agresti, Jeremy J.; Weitz, David A.

    2011-01-01

    Controlling droplet incubation is critical for droplet-based microfluidic applications; however, current techniques are either of limited precision or place strict limits on the incubation times that can be achieved. Here, we present a simple technique to control incubation time by exploiting close-packed plug flow. In contrast to other techniques, this technique is applicable to very short and very long incubation times.

  12. Learning from drivers and conflicts around bedded pack barns

    OpenAIRE

    Galama, P.J.; Dooren, van, H.J.C.; Eilers, C.H.A.M.

    2012-01-01

    Due to problems with the freestall a network of dairy farmers in the Netherlands started looking for alternative housing systems for dairy cattle. Therefore researchers and dairy farmers shared ideas and looked abroad in America and Israel for housing systems without cubicles. This gave inspiration for deep bedded pack systems like in these countries. The drivers (motivations) for these housing systems were animal welfare and manure quality. However, they had to be made suitable for the Dutch...

  13. Nearly-Linear Time Packing and Covering LP Solvers

    OpenAIRE

    Allen-Zhu, Zeyuan; Orecchia, Lorenzo

    2014-01-01

    Packing and covering linear programs (PC-LPs) form an important class of linear programs (LPs) across computer science, operations research, and optimization. In 1993, Luby and Nisan constructed an iterative first-order algorithm for approximately solving PC-LPs in $\\textit{nearly-linear time}$, independently of the program's $\\textit{width}$, i.e., the largest value in the program's description. Unfortunately, all existing nearly-linear-time algorithms for solving PC-LPs require time at leas...

  14. Matroid intersection, base packing and base covering for infinite matroids

    OpenAIRE

    Bowler, Nathan; Carmesin, Johannes

    2012-01-01

    As part of the recent developments in infinite matroid theory, there have been a number of conjectures about how standard theorems of finite matroid theory might extend to the infinite setting. These include base packing, base covering, and matroid intersection and union. We show that several of these conjectures are equivalent, so that each gives a perspective on the same central problem of infinite matroid theory. For finite matroids, these equivalences give new and simpler proofs for the f...

  15. Packing Regularities in Biological Structures Relate to Their Dynamics

    OpenAIRE

    Jernigan, Robert L.; Kloczkowski, Andrzej

    2007-01-01

    The high packing density inside proteins leads to certain geometric regularities and also is one of the most important contributors to the high extent of cooperativity manifested by proteins in their cohesive domain motions. The orientations between neighboring non-bonded residues in proteins substantially follow the similar geometric regularities, regardless of whether the residues are on the surface or buried - a direct result of hydrophobicity forces. These orientations are relatively fixe...

  16. Using particle packing technology for sustainable concrete mixture design

    OpenAIRE

    Fennis, S.A.A.M.; Walraven, J.C.

    2012-01-01

    The annual production of Portland cement, estimated at 3.4 billion tons in 2011, is responsible for about 7% of the total worldwide CO2-emission. To reduce this environmental impact it is important to use innovative technologies for the design of concrete structures and mixtures. In this paper, it is shown how particle packing technology can be used to reduce the amount of cement in concrete by concrete mixture optimization, resulting in more sustainable concrete. First, three different metho...

  17. Design of ecological concrete by particle packing optimization

    OpenAIRE

    Fennis, S.A.A.M.

    2011-01-01

    The goal of this research project on Ecological Concrete was to reduce the CO2-emission of concrete and to reuse secondary materials form concrete production and other industries simultaneously. This also minimizes the use of natural resources and the production costs. To replace cement in concrete in a safe way, the main question answered in this thesis was how particle packing models can be used to predict the mechanical properties of ecological concrete from its basic components. To optimi...

  18. Catalyst for Carbon Monoxide Oxidation

    Science.gov (United States)

    Davis, Patricia; Brown, Kenneth; VanNorman, John; Brown, David; Upchurch, Billy; Schryer, David; Miller, Irvin

    2010-01-01

    In many applications, it is highly desirable to operate a CO2 laser in a sealed condition, for in an open system the laser requires a continuous flow of laser gas to remove the dissociation products that occur in the discharge zone of the laser, in order to maintain a stable power output. This adds to the operating cost of the laser, and in airborne or space applications, it also adds to the weight penalty of the laser. In a sealed CO2 laser, a small amount of CO2 gas is decomposed in the electrical discharge zone into corresponding quantities of CO and O2. As the laser continues to operate, the concentration of CO2 decreases, while the concentrations of CO and O2 correspondingly increase. The increasing concentration of O2 reduces laser power, because O2 scavenges electrons in the electrical discharge, thereby causing arcing in the electric discharge and a loss of the energetic electrons required to boost CO2 molecules to lasing energy levels. As a result, laser power decreases rapidly. The primary object of this invention is to provide a catalyst that, by composition of matter alone, contains chemisorbed water within and upon its structure. Such bound moisture renders the catalyst highly active and very long-lived, such that only a small quantity of it needs to be used with a CO2 laser under ambient operating conditions. This object is achieved by a catalyst that consists essentially of about 1 to 40 percent by weight of one or more platinum group metals (Pt, Pd, Rh, Ir, Ru, Os, Pt being preferred); about 1 to 90 percent by weight of one or more oxides of reducible metals having multiple valence states (such as Sn, Ti, Mn, Cu, and Ce, with SnO2 being preferred); and about 1 to 90 percent by weight of a compound that can bind water to its structure (such as silica gel, calcium chloride, magnesium sulfate, hydrated alumina, and magnesium perchlorate, with silica gel being preferred). Especially beneficial results are obtained when platinum is present in the

  19. A study on the turbine efficiency through the shaft packing improvement of new fossil power plant

    International Nuclear Information System (INIS)

    The main reason for applying positive pressure variable clearance packing in fossil power plant is high efficiency and energy saving movement in the government. This study intends to analyze the turbine efficiency through the shaft packing improvement in thermal power plant and makes its comparison to that of the used packing

  20. A Recursive Formulation of Cholesky Factorization of a Matrix in Packed Storage Format

    DEFF Research Database (Denmark)

    Andersen, Bjarne Stig; Gustavson, Fred; Wasniewski, Jerzy

    2001-01-01

    A new compact way to store a symmetric or triangular matrix called RPF for Recursive Packed Format is fully described. Novel ways to transform RPF to and from standard packed format are included. A new algorithm, called RPC for Recursive Packed Cholesky that operates on the RPF format is presente...

  1. Regular Packing for Heat and Mass Exchange Processes by the Direct Contact of Phases

    OpenAIRE

    Pushnov, A. S.; Kagan, A. M.; Berengarten, M. G.; Ryabushenko, A. S.; Stremyakov, A. V.

    2008-01-01

    The new effective regular packing PN-3D for heat and mast exchange processes performance with quasi-isotropic properties of structure was offered. The test results of new packing are shown in comparison with other well-known regular and irregular industrial packing.

  2. 48 CFR 252.211-7004 - Alternate preservation, packaging, and packing.

    Science.gov (United States)

    2010-10-01

    ..., packaging, and packing. 252.211-7004 Section 252.211-7004 Federal Acquisition Regulations System DEFENSE... CLAUSES Text of Provisions And Clauses 252.211-7004 Alternate preservation, packaging, and packing. As prescribed in 211.272, use the following provision: Alternate Preservation, Packaging, and Packing (DEC...

  3. 21 CFR 133.123 - Cold-pack and club cheese.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 2 2010-04-01 2010-04-01 false Cold-pack and club cheese. 133.123 Section 133.123... FOR HUMAN CONSUMPTION CHEESES AND RELATED CHEESE PRODUCTS Requirements for Specific Standardized Cheese and Related Products § 133.123 Cold-pack and club cheese. (a)(1) Cold-pack cheese, club cheese,...

  4. Pack hunting by a common soil amoeba on nematodes.

    Science.gov (United States)

    Geisen, Stefan; Rosengarten, Jamila; Koller, Robert; Mulder, Christian; Urich, Tim; Bonkowski, Michael

    2015-11-01

    Soils host the most complex communities on Earth, including the most diverse and abundant eukaryotes, i.e. heterotrophic protists. Protists are generally considered as bacterivores, but evidence for negative interactions with nematodes both from laboratory and field studies exist. However, direct impacts of protists on nematodes remain unknown. We isolated the soil-borne testate amoeba Cryptodifflugia operculata and found a highly specialized and effective pack-hunting strategy to prey on bacterivorous nematodes. Enhanced reproduction in presence of prey nematodes suggests a beneficial predatory life history of these omnivorous soil amoebae. Cryptodifflugia operculata appears to selectively impact the nematode community composition as reductions of nematode numbers were species specific. Furthermore, we investigated 12 soil metatranscriptomes from five distinct locations throughout Europe for 18S ribosomal RNA transcripts of C. operculata. The presence of C. operculata transcripts in all samples, representing up to 4% of the active protist community, indicates a potential ecological importance of nematophagy performed by C. operculata in soil food webs. The unique pack-hunting strategy on nematodes that was previously unknown from protists, together with molecular evidence that these pack hunters are likely to be abundant and widespread in soils, imply a considerable importance of the hitherto neglected trophic link 'nematophagous protists' in soil food webs. PMID:26079718

  5. The structure of tropical forests and sphere packings.

    Science.gov (United States)

    Taubert, Franziska; Jahn, Markus Wilhelm; Dobner, Hans-Jürgen; Wiegand, Thorsten; Huth, Andreas

    2015-12-01

    The search for simple principles underlying the complex architecture of ecological communities such as forests still challenges ecological theorists. We use tree diameter distributions--fundamental for deriving other forest attributes--to describe the structure of tropical forests. Here we argue that tree diameter distributions of natural tropical forests can be explained by stochastic packing of tree crowns representing a forest crown packing system: a method usually used in physics or chemistry. We demonstrate that tree diameter distributions emerge accurately from a surprisingly simple set of principles that include site-specific tree allometries, random placement of trees, competition for space, and mortality. The simple static model also successfully predicted the canopy structure, revealing that most trees in our two studied forests grow up to 30-50 m in height and that the highest packing density of about 60% is reached between the 25- and 40-m height layer. Our approach is an important step toward identifying a minimal set of processes responsible for generating the spatial structure of tropical forests. PMID:26598678

  6. Performance of Structured Packing in High Pressure Distillation

    Institute of Scientific and Technical Information of China (English)

    张鹏; 刘春江; 等

    2002-01-01

    Performance of Mellapak 250Y and 350Y corrugated structured packing in distillation applications at pressures ranging from 0.3 to 2.0MPa is analysed by using HTU-NTU method.These data are obtained in distillation column with 0.15m diameter operated with n-butane/n-pentane system at total reflux.In considering the axial backmixing effects.the height of an overall gas phase transfer unit,HTUOG,is divided into two parts.One part represents the height of an overall gas phase transfer unit,without backmixing, designated as HUTOG,and the other part,designated as the height of a backmixing unit(HBUO),accounts for the backmixing effects.The HTUOG is evaluated from the measured concentration profile of n-butane in liquid phase.The HBUO obtained experimentally is correlated in terms of the properties of the materials being separated and the equivalent diameter of the structured packing.Our result shows that HBUO varies from 0.12 to 0.34m as pressure increases from 1.0 to 1.9MPa.It indicates that the overall efficiency of the structured packing decreas gradually at high pressure,as a result of the vapor backmixing.

  7. Gradient packing bed bio-filter for landfill methane mitigation.

    Science.gov (United States)

    Obulisamy, Parthiba Karthikeyan; Sim Yan May, Jane; Rajasekar, Balasubramanian

    2016-10-01

    We assessed the suitability of various biogenic materials for development of a gradient packed bed bio-filter to mitigate the methane (CH4) emission from landfills. Five different biogenic materials (windrow compost-WC; vermicompost-VC; landfill top cover-LTC; landfill bottom soil-LBS; and river soil sediment-SS) were screened. Among these materials, the VC showed a better CH4 oxidation potential (MOP) of 12.6μg CH4 gdw(-1)h(-1). Subsequently, the VC was used as a packing material along with wood chips in proto-type bio-filters. Wood chips were mixed at 5-15% to form three distinct gradients in a test bio-filter. Under the three different CH4 loading rates of 33, 44 and 55 gCH4 m(-3)h(-1), the achieved MOPs were 31, 41, and 47gCH4 m(-3)h(-1), respectively. The gradient packed bed bio-filter is effective for landfill CH4 mitigation than the conventional bio-filter as the latter shows gas channeling effects with poor MOPs. PMID:26883060

  8. Influence of Crystal Packing on Global Protein Conformation

    Science.gov (United States)

    Ahlstrom, Logan; Miyashita, Osamu

    2011-10-01

    X-ray crystallography is the most robust method for solving protein structure. However, packing forces in the crystal lattice select just a snapshot of a protein's conformational ensemble, whereas proteins are flexible and can adopt different conformations. Here we compare molecular dynamics (MD) simulations in solution and the crystal lattice to add dynamical insight to the static X-ray images of proteins. As a model system, we consider the λ Cro dimer, whose solved X-ray structures range from a ``closed'' to an ``open'' global conformation. Free energy profiles depicting the conformational space sampled by the dimer in solution show some reported structures correspond to stable states. Yet other conformations, while accessible, lie higher in energy, indicating the effect of crystal packing. Subsequent crystal MD simulations estimated the strength of packing interfaces in the lattice, showing the influence of crystal form and mutation in stabilizing different dimer conformations. Our quantitative results will aid analysis of X-ray data in establishing protein structure-function relationships.

  9. Pack cementation diffusion coatings for iron-base alloys

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, R.A. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering

    1995-02-01

    With the aid of computer-assisted calculations of the equilibrium vapor pressures in halide-activated cementation packs, processing conditions have been identified and experimentally verified for the codeposition of two or more alloying elements in a diffusion coating on a variety of steels. The Cr-Si ferrite layers have proven to be very resistant to high temperature cyclic oxidation and to pitting in aqueous solutions. The process has been patented, and is being transferred for industrial application, e.g. for water walls of utility boilers, etc. In the proposed extension of this project, the use of mixed pure metal powders in the pack will be extended to achieve similar ferrite Fe-Cr-Al coatings with excellent oxidation resistance, with the eventual transfer of the technology to industry. In other recent studies, Ni-base alloy rods were aluminized by the halide-activated pack cementation process to bring their average composition to that for the ORNL-developed Ni{sub 3}Al, for use as a welding rod. A similar effort to develop a welding rod for the ORNL Fe{sub 3}Al alloy did not yield reproducible coating compositions or growth kinetics. The continued effort to produce Duriron-type (Fe-18Si-5Cr) coatings on steels was not successful. Literature for the intrinsic diffusion coefficients suggests that this task cannot be achieved.

  10. A new look at gravel pack carrier fluid properties

    Energy Technology Data Exchange (ETDEWEB)

    Scheuerman, R.F.

    1984-02-01

    For gravel pack carrier fluids, less viscosity is needed downhole than for suspending and pumping high gravel loadings on the surface. To achieve this dual viscosity need, breakers are added to degrade the viscosifying polymers. Unfortunately, viscosity breakback criteria are not well defined. In addition to the type and concentration of breaker and temperature, the apparent viscosity breakback time of a polymer solution also depends on the shear rate at which the viscosity is measured. As a result, industry breakback data generally disagree because of the variety of instruments and shear rates used to measure viscosity. This paper discusses two new viscosity breakback criteria for gravel packing carrier fluids: The time for the apparent viscosity at 0.03 sec/sup -1/ to decrease to 1000 cp, and start of compaction of the settled gravel bed. These criteria correlate well with fluid performance and apply to slurries with different initial viscosities (including crosslinked gels), brine densities, and gravel sizes. Data useful for formulating gravel pack carrier fluids are also presented. Although this paper does not define optimum downhole carrier fluid properties, the new criteria reflect downhole conditions better than most previous criteria. They should give better correlation with model studies and field experience, and, in turn, lead to a better understanding of the requirements for optimum downhole performance.

  11. Localized Disturbance in a 2D Cohesive Granular Packing

    Science.gov (United States)

    Rieser, Jennifer; Laplagne, Mathilde; Durian, Douglas

    2015-03-01

    How the local structural configuration influences large-scale deformation in disordered materials is not known. Inspired by nano-indentation experiments, we characterize the response of disordered granular packing to a localized disturbance by driving a triangular wedge into the packing. The extent of the disturbance is explored by performing experiments with several wedge angles. The two-dimensionality of the system allows for direct observation of all particle dynamics during the indentation. The grains can be cohesive, with an attraction governed by tunable capillary forces that are induced through an interstitial fluid. Topological quantities derived from a radical Voronoi diagram as well as the resulting triangulation are used to characterize local structure within the packing. Dynamics are characterized by local deformations to the triangulation as well as the local non-affine motion. For all wedge angles, a boundary develops between moving and static grains. This size and shape of this boundary depend on the indenter angle, and in all cases, the size of the boundary increases with time. During the deformation, non-affine grain motion occurs both throughout the moving region as well as along the boundary, while holes tend to develop primarily along this boundary. MRSEC/DMR-1120901.

  12. Phenomenological Anisotropic Study of Surface Finish in Pack Rolling

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A phenomenological anisotropic model has been presented for the surface roughness modeling of pack rolling. The model is an assembly of grains in different orientations and sizes. The grain size is assumed to be in log-normal distribution. To model the macro anisotropic mechanical behavior of the grains induced by the slip deformation, the grains are assumed as isolated anisotropic units. The units have different mechanic behavior, and depend on the crystallographic orientations and the external loading as well as the interaction of the adjunctive grains. In the paper,the material properties of the grains are assumed as uniform distributions. The roughness of the contact surfaces depends on the distribution types and the scatters of the distributions. It is found that the initial roughness of the contact surfaces has a little influence on the surface roughness when the rolling deformation is large. The comparison between the phenomenological model and crystallographic model shows that the phenomenological model can also give out a reasonable result, while it only takes much less CPU time. The agreement between the single sheet model and the pack rolling model shows that in a certain degree the pack rolling model can be replaced by the single sheet model to decrease the CPU time.

  13. Particle size and packing characterization by diffuse light transmission

    Institute of Scientific and Technical Information of China (English)

    Henrik Ehlers; Jyrki Hein(a)m(a)ki; Jouko Yliruusi

    2012-01-01

    Particle size,packing density and blend composition of glass ballotini,microcrystalline cellulose pellets and theophylline granules were studied by diffuse light transmission.Diffuse visible light was directed to the sample and the intensity of the light transmitted to the opposite side of the sample was measured through a diffusing lens using a phototransistor.Light transmission was found to decrease with decreasing particle size and with increasing packing density.There was a correlation,though somewhat irregular,between light transmission and particle size for glass ballotini and microcrystalline cellulose pellets,and a strong near-linear correlation between light transmission and particle size for theophylline granules.The effect of packing density on light transmission was significant.Differentiating the composition of binary blends of microcrystalline cellulose pellets and glass ballotini and blends of theophylline granules was found possible on the basis of light transmission.The method proposed showed potential as a rapid,simple and inexpensive analytical tool for basic process diagnostics.

  14. List mode multichannel analyzer

    Science.gov (United States)

    Archer, Daniel E.; Luke, S. John; Mauger, G. Joseph; Riot, Vincent J.; Knapp, David A.

    2007-08-07

    A digital list mode multichannel analyzer (MCA) built around a programmable FPGA device for onboard data analysis and on-the-fly modification of system detection/operating parameters, and capable of collecting and processing data in very small time bins (<1 millisecond) when used in histogramming mode, or in list mode as a list mode MCA.

  15. PlanetPack: a radial-velocity time-series analysis tool facilitating exoplanets detection, characterization, and dynamical simulations

    CERN Document Server

    Baluev, Roman V

    2013-01-01

    We present PlanetPack, a new software tool that we developed to facilitate and standardize the advanced analysis of radial velocity (RV) data for the goal of exoplanets detection, characterization, and basic dynamical $N$-body simulations. PlanetPack is a command-line interpreter, that can run either in an interactive mode or in a batch mode of automatic script interpretation. Its major abilities include: (i) Advanced RV curve fitting with the proper maximum-likelihood treatment of unknown RV jitter; (ii) User-friendly multi-Keplerian as well as Newtonian $N$-body RV fits; (iii) Use of more efficient maximum-likelihood periodograms that involve the full multi-planet fitting (sometimes called as ``residual'' or ``recursive'' periodograms); (iv) Easily calculatable parametric 2D likelihood function level contours, reflecting the asymptotic confidence regions; (v) Fitting under some useful functional constraints is user-friendly; (vi) Basic tasks of short- and long-term planetary dynamical simulation using a fas...

  16. MECHANISTIC KINETIC MODELS FOR STEAM REFORMING OF CONCENTRATED CRUDE ETHANOL ON NI/AL2O3 CATALYST

    Directory of Open Access Journals (Sweden)

    O. A. OLAFADEHAN

    2015-05-01

    Full Text Available Mechanistic kinetic models were postulated for the catalytic steam reforming of concentrated crude ethanol on a Ni-based commercial catalyst at atmosphere pressure in the temperature range of 673-863 K, and at different catalyst weight to the crude ethanol molar flow rate ratio (in the range 0.9645-9.6451 kg catalyst h/kg mole crude ethanol in a stainless steel packed bed tubular microreactor. The models were based on Langmuir-Hinshelwood-Hougen-Watson (LHHW and Eley-Rideal (ER mechanisms. The optimization routine of Nelder-Mead simplex algorithm was used to estimate the inherent kinetic parameters in the proposed models. The selection of the best kinetic model amongst the rival kinetic models was based on physicochemical, statistical and thermodynamic scrutinies. The rate determining step for the steam reforming of concentrated crude ethanol on Ni/Al2O3 catalyst was found to be surface reaction between chemisorbed CH3O and O when hydrogen and oxygen were adsorbed as monomolecular species on the catalyst surface. Excellent agreement was obtained between the experimental rate of reaction and conversion of crude ethanol, and the simulated results, with ADD% being ±0.46.

  17. Attachment-less rack mounted paper-pack automatic vending machine; Atacchimentoresu rakku tosai paper pack jido hanbaiki

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-01-10

    Under the circumstances that over 90% of automatic paper-pack vending machines are installed indoors, a new series was developed with an aim to enhance installation convenience and operation performance. Automatic paper-pack vending machines selling merchandises reaching as many as 30 models have required a number of attachments. The new series mounted with attachment-less directly loaded racks eliminating all of the attachments was put into mass production for the first time in the industry. Its major features are as follows: (1) the directly loaded racks requiring no attachments can be mounted by making the rack side plate movable when merchandises are changed; (2) improvement in the main box body construction reduced the box width by 7 cm; (3) 10% energy conservation was achieved as compared to conventional machines; and (4) merchandise moving noise was reduced by adopting plastic chains. (translated by NEDO)

  18. Territoriality and inter-pack aggression in gray wolves: shaping a social carnivore's life history

    Science.gov (United States)

    Cassidy, Kira A.; Smith, Douglas W.; Mech, L. David; MacNulty, Daniel R.; Stahler, Daniel R.; Metz, Matthew C.

    2016-01-01

    When Rudyard Kipling wrote The Jungle Book in 1894 and included the famous line "For the strength of the Wolf is the Pack, and the strength of the Pack is the Wolf," he would have had no idea that over a century later, scientific research would back up his poetic phrase. Recent studies in Yellowstone have found that both the individual wolf and the collective pack rely on each other and play important roles in territoriality. At a time when most fairy tales and fables were portraying wolves as demonic killers or, at best, slapstick gluttons, Kipling seemed to have a respect or even reverence for the wolf. Wolves in The Jungle Book raise and mentor the main character Mowgli, with the pack's leader eventually dying to save the "man-cub" from a pack of wolves. Kipling may have extended intra- pack benevolence to a human boy for literary sake, but he was clearly enthralled with how pack members treat each other. As wolf packs are almost always family units, most commonly comprised of a breeding pair and their offspring from several years, amiable behavior within the pack is unsurprising. By contrast, wolf packs are fiercely intolerant of their neighbors, their rivals. And this competition is proving to be an important facet in the life of a wolf and its pack.

  19. Tapping-mode atomic force microscopy produces faithful high-resolution images of protein surfaces.

    OpenAIRE

    Möller, C; Allen, M.; Elings, V; Engel, A.; Müller, D J

    1999-01-01

    Compared to contact-mode atomic force microscopy (CMAFM), tapping-mode atomic force microscopy (TMAFM) has the advantage of allowing imaging surfaces of macromolecules, even when they are only weakly attached to the support. In this study, TMAFM is applied to two different regular protein layers whose structures are known to great detail, the purple membrane from Halobacterium salinarum and the hexagonally packed intermediate (HPI) layer from Deinococcus radiodurans, to assess the faithfulnes...

  20. Development of cooling strategy for an air cooled lithium-ion battery pack

    Science.gov (United States)

    Sun, Hongguang; Dixon, Regan

    2014-12-01

    This paper describes a cooling strategy development method for an air cooled battery pack with lithium-ion pouch cells used in a hybrid electric vehicle (HEV). The challenges associated with the temperature uniformity across the battery pack, the temperature uniformity within each individual lithium-ion pouch cell, and the cooling efficiency of the battery pack are addressed. Initially, a three-dimensional battery pack thermal model developed based on simplified electrode theory is correlated to physical test data. An analytical design of experiments (DOE) approach using Optimal Latin-hypercube technique is then developed by incorporating a DOE design model, the correlated battery pack thermal model, and a morphing model. Analytical DOE studies are performed to examine the effects of cooling strategies including geometries of the cooling duct, cooling channel, cooling plate, and corrugation on battery pack thermal behavior and to identify the design concept of an air cooled battery pack to maximize its durability and its driving range.