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1

Ammonia-recycled percolation process for pretreatment of biomass feedstock  

Microsoft Academic Search

An ammonia-based biomass pretreatment method named ammonia recycled percolation (ARP) process was investigated. The process\\u000a characteristics are:\\u000a \\u000a \\u000a 1. \\u000a \\u000a Aqueous ammonia is used as a pretreatment reagent;\\u000a \\u000a \\u000a \\u000a \\u000a 2. \\u000a \\u000a A packed bed flowthrough-type reactor (percolation reactor) is used in recirculation mode;\\u000a \\u000a \\u000a \\u000a \\u000a 3. \\u000a \\u000a ARP-Ammonia is continuously recycled.\\u000a \\u000a \\u000a \\u000a \\u000a \\u000a \\u000a The experimental data on hybrid poplar indicate that the ARP is a highly effective pretreatment method.

H. H. Yoon; Z. W. Wu; Y. Y. Lee

1995-01-01

2

Bioethanol production from ammonia percolated wheat straw  

Microsoft Academic Search

This study examined the effectiveness of ammonia percolation pretreatment of wheat straw for ethanol production. Ground wheat\\u000a straw at a 10% (w\\/v) loading was pretreated with a 15% (v\\/v) ammonia solution. The experiments were performed at treatment\\u000a temperature of 50?170°C and residence time of 10?150 min. The solids treated with the ammonia solution showed high lignin\\u000a degradation and sugar availability.

Minhee Han; Se-Kwon Moon; Yule Kim; Youngran Kim; Bongwoo Chung; Gi-Wook Choi

2009-01-01

3

Pretreatment Characteristics of Waste Oak Wood by Ammonia Percolation  

NASA Astrophysics Data System (ADS)

A log of waste oak wood collected from a Korean mushroom farm has been tested for ammonia percolation pretreatment. The waste log has different physical characteristics from that of virgin oak wood. The density of the waste wood was 30% lower than that of virgin oak wood. However, there is little difference in the chemical compositions between the woods. Due to the difference in physical characteristics, the optimal pretreatment conditions were also quite different. While for waste oak the optimum temperature was determined to be 130°C, for virgin oak wood the optimum pretreatment was only achieved at 170°C. Presoaking for 12 h with ammonia solution before pretreatment was helpful to increase the delignification efficiency.

Kim, Jun-Seok; Kim, Hyunjoon; Lee, Jin-Suk; Lee, Joon-Pyo; Park, Soon-Chul

4

Ammonia recycling enables sustainable operation of bioelectrochemical systems.  

PubMed

Ammonium (NH4(+)) migration across a cation exchange membrane is commonly observed during the operation of bioelectrochemical systems (BES). This often leads to anolyte acidification (pH <5.5) and complete inactivation of biofilm electroactivity. Without using conventional pH controls (dosage of alkali or pH buffers), the present study revealed that anodic biofilm activity (current) could be sustained if recycling of ammonia (NH3) was implemented. A simple gas-exchange apparatus was designed to enable continuous recycling of NH3 (released from the catholyte at pH >10) from the cathodic headspace to the acidified anolyte. Results indicated that current (110 mA or 688 Am(-3) net anodic chamber volume) was sustained as long as the NH3 recycling path was enabled, facilitating continuous anolyte neutralization with the recycled NH3. Since the microbial current enabled NH4(+) migration against a strong concentration gradient (~10-fold), a novel way of ammonia recovery from wastewaters could be envisaged. PMID:23774293

Cheng, Ka Yu; Kaksonen, Anna H; Cord-Ruwisch, Ralf

2013-05-31

5

Improved methane fermentation of chicken manure via ammonia removal by biogas recycle  

Microsoft Academic Search

This study demonstrates methane fermentation that was carried out along with ammonia striping to avoid ammonia accumulation that significantly inhibited methane production. Ammonia was successfully removed by means of recycling of biogas followed by gas washing in sulfuric acid to capture ammonia, when chicken manure was anaerobically digested for 4days at 55°C and at an initial pH of 8–9. By

Fatma Abouelenien; Wataru Fujiwara; Yuzaburo Namba; Maria Kosseva; Naomichi Nishio; Yutaka Nakashimada

2010-01-01

6

Recycle of tin thiolate compounds relevant to ammonia-borane regeneration.  

PubMed

The use of benzenedithiol as a digestant for ammonia-borane spent fuel has been shown to result in tin thiolate compounds which we demonstrate can be recycled, yielding Bu(3)SnH and ortho-benzenedithiol for reintroduction to the ammonia-borane regeneration scheme. PMID:20024322

Sutton, Andrew D; Davis, Benjamin L; Bhattacharyya, Koyel X; Ellis, Bobby D; Gordon, John C; Power, Philip P

2009-11-13

7

Graphene oxide based recyclable dehydrogenation of ammonia borane within a hybrid nanostructure.  

PubMed

The recyclable dehydrogenation of ammonia borane (AB) is achievable within a graphene oxide (GO)-based hybrid nanostructure, in which a combined modification strategy of acid activation and nanoconfinement by GO allows AB to release more than 2 equiv of pure H(2) at temperatures below 100 °C. This process yields polyborazylene (PB) as a single product and, thus, promotes the chemical regeneration of AB via reaction of PB with hydrazine in liquid ammonia. PMID:22417383

Tang, Ziwei; Chen, Hao; Chen, Xiaowei; Wu, Limin; Yu, Xuebin

2012-03-19

8

Improved methane fermentation of chicken manure via ammonia removal by biogas recycle.  

PubMed

This study demonstrates methane fermentation that was carried out along with ammonia striping to avoid ammonia accumulation that significantly inhibited methane production. Ammonia was successfully removed by means of recycling of biogas followed by gas washing in sulfuric acid to capture ammonia, when chicken manure was anaerobically digested for 4 days at 55 degrees C and at an initial pH of 8-9. By using this method, 80% of total nitrogen in chicken manure was converted to ammonia and 82% of the produced ammonia was removed. A bench scale reactor equipped with an ammonia-stripping unit for methane production from chicken manure was developed and operated in repeated batch mode. At an initial pH of 8 and at 55 degrees C, 195 and 157 ml g-VS(-1) of methane was successfully produced from the treated chicken manure and the mixture of treated chicken manure and raw chicken manure in the ratio of 1:1, respectively. In this method, ammonia concentration was maintained at a level lower than 2g-N kg-wet sludge(-1) in the reactor. PMID:20378337

Abouelenien, Fatma; Fujiwara, Wataru; Namba, Yuzaburo; Kosseva, Maria; Nishio, Naomichi; Nakashimada, Yutaka

2010-04-08

9

Recycling of Aluminum Salt Cake: Utilization of Evolved Ammonia  

NASA Astrophysics Data System (ADS)

The communication presents an extension of the leaching process of the salt cake earlier developed by the present authors. The process describes the investigations in capturing the ammonia gas evolved by hydrolysis of AlN during aqueous leaching at 373 K (100 °C) by CO2-saturated water. The product, i.e., ammonium bicarbonate which is free of chlorides, is a value-added product and can find application in the fertilizer industry. The present method has the added advantage of fixing CO2 as well.

Li, Peng; Zhang, Mei; Teng, Lidong; Seetharaman, Seshadri

2013-02-01

10

AMMONIA  

EPA Science Inventory

This document summarizes the available information on ammonia as it relates to its effects on man and his environment. Ammonia is a ubiquitous substance and is known widely as a household cleaning agent and as a fertilizer. It plays an important role in the nitrogen cycle--in the...

11

Pretreatment of Biomass by Aqueous Ammonia for Bioethanol Production  

NASA Astrophysics Data System (ADS)

The methods of pretreatment of lignocellulosic biomass using aqueous ammonia are described. The main effect of ammonia treatment of biomass is delignification without significantly affecting the carbohydrate contents. It is a very effective pretreatment method especially for substrates that have low lignin contents such as agricultural residues and herbaceous feedstock. The ammonia-based pretreatment is well suited for simultaneous saccharification and co-fermentation (SSCF) because the treated biomass retains cellulose as well as hemicellulose. It has been demonstrated that overall ethanol yield above 75% of the theoretical maximum on the basis of total carbohydrate is achievable from corn stover pretreated with aqueous ammonia by way of SSCF. There are two different types of pretreatment methods based on aqueous ammonia: (1) high severity, low contact time process (ammonia recycle percolation; ARP), (2) low severity, high treatment time process (soaking in aqueous ammonia; SAA). Both of these methods are described and discussed for their features and effectiveness.

Kim, Tae Hyun; Gupta, Rajesh; Lee, Y. Y.

12

Recycling  

NSDL National Science Digital Library

You will be learning all about recycling and asking questions as you learn more about recycling. Afterward, you will be making recycling bins that we will use in our classroom. Click on each of the different links and research about recycling. Find out what recycling is, what can be recycled, and why we should recycle. As you find information, add it to the "describing wheel" that is given to you by Ms. Pollak. Answer the main question: What is recycling? Come ...

sgp0002

2010-03-27

13

Recycling.  

ERIC Educational Resources Information Center

|Discusses the range of benefits resulting from recycling efforts and projects. Presents information and data related to the recycling of metals, cans, paper, fans, and plastics. Suggestions for motivating and involving youth in recycling programs are also offered. (ML)|

Sinker, Barbara

1986-01-01

14

Recycling.  

ERIC Educational Resources Information Center

Discusses the range of benefits resulting from recycling efforts and projects. Presents information and data related to the recycling of metals, cans, paper, fans, and plastics. Suggestions for motivating and involving youth in recycling programs are also offered. (ML)

Sinker, Barbara

1986-01-01

15

Recycling  

NSDL National Science Digital Library

What objects can be recycled? 1. Click on link. Watch video. Recycle Guy Video 2. Click on link. Watch video. Talking Trash Video 3. Click on link. Watch video. Recycling At School Video 4. Click on link. Play game. Star Fall Recycling Game 5. Click on link. Play game. National Geographic Recycling Game 6. Click on link. Ask Ms. Owens how to do it. Things We Recycle Chart 7. Please see Miss Owens for instructions on the following ...

2011-04-07

16

Recycling  

Microsoft Academic Search

\\u000a Recycling systems are classified into those employing typically three methods, and the progress of each method is described.\\u000a In mechanical recycling, powders of phenolic materials are recovered via a mechanical process and reused as fillers or additives in virgin materials.\\u000a The effects to flowability, curability, and mechanical properties of the materials are explained. In feedstock recycling, monomers, oligomers, or oils

Junya Goto; Michael Santorelli

2010-01-01

17

Recycling  

NSDL National Science Digital Library

Let\\'s learn how to reduce, reuse and recycle waste! BUILDING YOUR KNOWLEDGE ABOUT RECYCLING 1. Learn the abc\\'s of recycling found here A is for Air. Be sure to click on each letter of the alphabet and read what it stands for. 2. Read the Adventures of the Garbage Gremlin in this Comic Book. 3. Steel is used to build cars, household appliances and cans. Read ...

Sykes, Miss

2005-10-20

18

Stimulation of Ammonia and 2-Oxoglutarate-Dependent O2 Evolution in Isolated Chloroplasts by Dicarboxylates and the Role of the Chloroplast in Photorespiratory Nitrogen Recycling  

PubMed Central

Intact chloroplasts isolated from spinach (Spinacia oleracea L.) leaves showed a light-dependent O2 evolution (5.5 ± 0.75 micromoles per milligram chlorophyll per hour) when supplied with ammonia and 2-oxoglutarate. This (ammonia, 2-oxoglutarate)-dependent O2 evolution was stimulated 2- to 4-fold by the dicarboxylates, malate, succinate, fumarate, glutarate, and l-tartarate. Evolution of O2 in the presence of malate was dependent on the presence of both 2-oxoglutarate and NH4Cl; malate with only either 2-oxoglutarate and NH4Cl alone did not support O2 evolution. Furthermore, in the presence of malate, the amount of O2 evolved was solely dependent on the amount of NH4Cl or 2-oxoglutarate added and malate did not affect the ratio of O2 evolved to NH4Cl or 2-oxoglutarate consumed. Studies with inhibitors (2-(3,4-dichlorophenyl)-1,1-dimethyl urea, methionine sulfoximine, and azaserine) indicated that the above activity was directly linked to glutamine synthetase and glutamate synthase activity in the chloroplast and was not caused by the metabolism of malate. The Vmax/2 of (ammonia, 2-oxoglutarate)-dependent O2 evolution was reached at 32 micromolar NH4Cl and 6 millimolar (approximately) 2-oxoglutarate in the absence of malate, and at 22 micromolar NH4Cl and 73 micromolar 2-oxoglutarate when malate (3 millimolar) was present. Intact chloroplasts isolated from pea (Pisum sativum) leaves also showed a stimulation of (ammonia, 2-oxoglutarate)-dependent O2 evolution by malate. However glutamine was required for this activity even though glutamine with only either NH4Cl or 2-oxoglutarate did not respond to malate stimulation. The measured rates of (ammonia, 2-oxoglutarate)-dependent O2 evolution in isolated spinach chloroplasts in the presence of malate were about 19.5 ± 4.5 micromoles O2 evolved per milligram chlorophyll per hour. This is adequate to sustain photorespiratory NH3 recycling and the refixation of NH3 arising from NO3 under ambient conditions in the light. The role of the chloroplast in photorespiratory NH3 recycling and the nature of the associated transport of 2-oxoglutarate into the chloroplast is discussed.

Woo, K. C.; Osmond, C. Barry

1982-01-01

19

Introduction to Percolation and Determinate Percolation  

Microsoft Academic Search

Take a porous stone and immerse it in water. Does the center of the stone contain water? The answer to this question can be given by understanding mathematical percolation. The percolation process is a model of an event passing through a space. The event can be one such as a disease spreading, or such as an object being permeated by

David Darling

2007-01-01

20

Percolation and Conduction  

Microsoft Academic Search

Extensions of percolation theory to treat transport are described. Resistor networks, from which resistors are removed at random, provide the natural generalization of the lattice models for which percolation thresholds and percolation probabilities have previously been considered. The normalized conductance, G, of such networks proves to be a sharply defined quantity with a characteristic concentration dependence near threshold which appears

Scott Kirkpatrick

1973-01-01

21

Elimination of phenols, ammonia and cyanide in wash water from biomass gasification, and nitrogen recycling using planted trickling filters.  

PubMed

Trickling filters were used to treat wash water from a wood gasifier. This wash water contained toxic substances such as ammonium, cyanide, phenols, and PAH. The goal was to develop a system that degraded toxic substances, and achieved full nitrification of ammonia. A 1 kW model wood gasifier plant delivered wash water for the experiments, which was standardised to a conductivity of 3 mS/cm by dilution. Toxicity was assessed by bacterial luminescence detection, germination test with cress (Lepidium sativum), and pot plants cultivated in a hydroponic setup irrigated continuously with the wastewater. Treatment experiments were done in both planted and unplanted trickling filters. Plant yield was similar to conventional hydroponic production systems. The trickling filters achieved complete detoxification of phenol, PAH and cyanide as well as full nitrification. The specific elimination rates were 100 g m(-3) Leca d(-1) for phenols and 90 g m(-3) Leca d(-1) for ammonium in planted systems. In unplanted trickling filters circulated for 63 h, phenol concentration decreased from 83.5 mg/L to 2.5 mg/L and cyanide concentration from 0.32 mg/L to 0.02 mg/L. PAH concentrations were reduced from 3,050 microg/L to 0.89 microg/L within 68 days. The assays demonstrated the feasibility of using the technique to construct a treatment system in a partially closed circulation for gasifier wash water. The principal advantage is to convert toxic effluents from biomass gasifiers into a non-toxic, nitrogen-rich fertiliser water, enabling subsequent use in plant production and thus income generation. However, the questions of long-term performance and possible accumulation of phenols and heavy metals in the produce still have to be studied. PMID:19955650

Graber, Andreas; Skvarc, Robert; Junge-Berberovi?, Ranka

2009-01-01

22

Substrate Dependency and Effect of Xylanase Supplementation on Enzymatic Hydrolysis of Ammonia-Treated Biomass  

NASA Astrophysics Data System (ADS)

Pretreatment based on aqueous ammonia was investigated under two different modes of operation: soaking in aqueous ammonia and ammonia recycle percolation. These processes were applied to three different feedstocks with varied composition: corn stover, high lignin (HL), and low lignin (LL) hybrid poplars. One of the important features of ammonia-based pretreatment is that most of the hemicellulose is retained after treatment, which simplifies the overall bioconversion process and enhances the conversion efficiency. The pretreatment processes were optimized for these feedstocks, taking carbohydrate retention as well as sugar yield in consideration. The data indicate that hybrid poplar is more difficult to treat than corn stover, thus, requires more severe conditions. On the other hand, hybrid poplar has a beneficial property that it retains most of the hemicellulose after pretreatment. To enhance the digestibility of ammonia-treated poplars, xylanase was supplemented during enzymatic hydrolysis. Because of high retention of hemicellulose in treated hybrid poplar, xylanase supplementation significantly improved xylan as well as glucan digestibility. Of the three feedstocks, best results and highest improvement by xylanase addition was observed with LL hybrid poplar, showing 90% of overall sugar yield.

Gupta, Rajesh; Kim, Tae Hyun; Lee, Yoon Y.

23

Multipartite entanglement percolation  

SciTech Connect

We present a percolation strategy based on multipartite measurements to propagate entanglement in quantum networks. We consider networks spanned on regular lattices whose bonds correspond to pure but nonmaximally entangled pairs of qubits, with any quantum operation allowed at the nodes. Despite significant effort in the past, improvements over standard (classical) percolation have been found for only a few lattices, often with restrictions on the initial amount of entanglement in the bonds. In contrast, multipartite entanglement percolation outperform the classical percolation protocols, as well as all previously known quantum ones, over the entire range of initial entanglement and for every lattice that we considered. Finally, we briefly show that our ideas also find application in noisy networks.

Perseguers, S. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Cavalcanti, D. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Spain); Center for Quantum Technologies, National University of Singapore (Singapore); Lapeyre, G. J. Jr. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Spain); Lewenstein, M.; Acin, A. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, Lluis Companys 23, E-08010 Barcelona (Spain)

2010-03-15

24

Effect of vortex flows on ammonia oxidation  

SciTech Connect

The oxidation of ammonia over platinum sieve catalysts was investigated given the vortex flows found in industrial contact units. Mathematical and physical models were used to assess the influence of vortices on ammonia oxidation. The flow pattern of the ammonia-air mixture in the reactor was modeled as a stream with a partial recycle. It is shown that vortex flows reduce the conversion of ammonia to nitrogen monoxide and increase the passage of unconverted ammonia through the catalyst sieve. Over long contact periods, the main effect of vortices is to increase the passage of unconverted ammonia, which may lead to the formation of explosive compounds.

Beskov, V.S.; Shpinel', E.E.

1988-09-01

25

Self-Destructive Percolation.  

National Technical Information Service (NTIS)

Consider ordinary site percolation on an infinite graph in which the sites, independent of each other, are occupied with probability p and vacant with probability 1-p. Now suppose that, by some 'catastrophe', all sites which are in an infinite occupied cl...

J. Van den Berg R. M. Brouwer

2003-01-01

26

Ammonia Process by Pressure Swing Adsorption  

SciTech Connect

The overall objective of the project is to design, develop and demonstrate a technically feasible and commercially viable system to produce ammonia along with recovery of the products by adsorption separation methods and significantly decrease the energy requirement in ammonia production. This is achieved through a significantly more efficient ammonia psa recovery system. The new ammonia recovery system receives the reactor effluents and achieves complete ammonia recovery, (which completely eliminates the energy intensive refrigeration and condensation system currently used in ammonia production). It also recovers the unused reactants and recycles them back to the reactor, free of potential reactor contaminants, and without the need for re-compression and re-heat of recycle stream thereby further saving more energy. The result is a significantly lower energy consumption, along with capital cost savings.

Dr Felix Jegede

2010-12-27

27

Electrical percolation based biosensors.  

PubMed

A new approach to label free biosensing has been developed based on the principle of "electrical percolation". In electrical percolation, long-range electrical connectivity is formed in randomly oriented and distributed systems of discrete elements. By applying this principle to biological interactions, it is possible to measure biological components both directly and electronically. The main element for electrical percolation biosensor is the biological semiconductor (BSC) which is a multi-layer 3-D carbon nanotube-antibody network. In the BSC, molecular interactions, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. BSCs can be fabricated by immobilizing conducting elements, such as pre-functionalized single-walled carbon nanotubes (SWNTs)-antibody complex, directly onto a substrate, such as a Poly(methyl methacrylate) (PMMA) surface (also known as plexi-glass or Acrylic). BSCs have been demonstrated for direct (label-free) electronic measurements of antibody-antigen binding using SWNTs. If the concentration of the SWNT network is slightly above the electrical percolation threshold, then binding of a specific antigen to the pre-functionalized SWNT dramatically increases the electrical resistance due to changes in the tunneling between the SWNTs. Using anti-staphylococcal enterotoxin B (SEB) IgG as a "gate" and SEB as an "actuator", it was demonstrated that the BSC was able to detect SEB at concentrations of 1ng/ml. Based on this concept, an automated configuration for BSCs is described here that enables real time continuous detection. The new BSC configuration may permit assembly of multiple sensors on the same chip to create "biological central processing units (CPUs)" with multiple biological elements, capable of processing and sorting out information on multiple analytes simultaneously. PMID:24041756

Bruck, Hugh Alan; Yang, Minghui; Kostov, Yordan; Rasooly, Avraham

2013-09-14

28

Ammonia Synthesis  

Microsoft Academic Search

\\u000a Ammonia production is a very energy- and capital-intensive industry as it requires high temperature (400–500°C) and also high\\u000a pressure (150–300 bar) for its daily operations. Two moles of ammonia are obtained by reacting one mole of nitrogen and three\\u000a moles of hydrogen gases in the presence of conventional catalyst which is magnetite. The process to produce ammonia is known\\u000a as

Noorhana Yahya; Poppy Puspitasari; Krzysztof Koziol; Pavia Guiseppe

29

The contact percolation transition  

NASA Astrophysics Data System (ADS)

Typical quasistatic compression algorithms for generating jammed packings of athermal, purely repulsive particles begin with dilute configurations and then apply successive compressions with relaxation of the elastic energy allowed between each compression step. It is well-known that during isotropic compression athermal systems with purely repulsive interactions undergo a jamming transition at packing fraction ?J from an unjammed state with zero pressure to a jammed, rigid state with nonzero pressure. Using extensive computer simulations, we show that a novel second-order-like, contact percolation, which signals the formation of a system-spanning cluster of mutually contacting particles, occurs at ?P< ?J, preceding the jamming transition. By measuring the number of non-floppy modes of the dynamical matrix, the displacement field between successive compression steps, and the overlap between the adjacency matrix, which represents the network of contacting grains, at ? and ?J, we find that the contact percolation transition also heralds the onset of nontrivial response to applied stress. Highly heterogeneous, cooperative, and non-affine particle motion occurs in unjammed systems significantly below the jamming transition for ?P< ?< ?J,

Shen, Tianqi; O'Hern, Corey; Shattuck, Mark

2012-02-01

30

Liquid Ammonia  

Microsoft Academic Search

This is a review of the use of liquid ammonia as a solvent for chemical processes. Among the subjects covered are the physical properties of the solvent that defines it as “water like.” The physical and chemical processes associated with the formation of solutions and the properties of those solutions are also convered. Included is a discussion of metal?ammonia solutions,

J. J. Lagowski

2007-01-01

31

Crackling noise in fractional percolation  

NASA Astrophysics Data System (ADS)

Crackling noise is a common feature in many systems that are pushed slowly, the most familiar instance of which is the sound made by a sheet of paper when crumpled. In percolation and regular aggregation, clusters of any size merge until a giant component dominates the entire system. Here we establish ‘fractional percolation’, in which the coalescence of clusters that substantially differ in size is systematically suppressed. We identify and study percolation models that exhibit multiple jumps in the order parameter where the position and magnitude of the jumps are randomly distributed—characteristic of crackling noise. This enables us to express crackling noise as a result of the simple concept of fractional percolation. In particular, the framework allows us to link percolation with phenomena exhibiting non-self-averaging and power law fluctuations such as Barkhausen noise in ferromagnets.

Schröder, Malte; Rahbari, S. H. Ebrahimnazhad; Nagler, Jan

2013-07-01

32

Crackling noise in fractional percolation.  

PubMed

Crackling noise is a common feature in many systems that are pushed slowly, the most familiar instance of which is the sound made by a sheet of paper when crumpled. In percolation and regular aggregation, clusters of any size merge until a giant component dominates the entire system. Here we establish 'fractional percolation', in which the coalescence of clusters that substantially differ in size is systematically suppressed. We identify and study percolation models that exhibit multiple jumps in the order parameter where the position and magnitude of the jumps are randomly distributed--characteristic of crackling noise. This enables us to express crackling noise as a result of the simple concept of fractional percolation. In particular, the framework allows us to link percolation with phenomena exhibiting non-self-averaging and power law fluctuations such as Barkhausen noise in ferromagnets. PMID:23887743

Schröder, Malte; Rahbari, S H Ebrahimnazhad; Nagler, Jan

2013-01-01

33

Ammonia (GCMP)  

NSDL National Science Digital Library

Ammonia fountain: this is a resource in the collection "General Chemistry Multimedia Problems". In an ammonia fountain, a flask is filled with ammonia gas. A tube from the flask extends into a pan of water that contains phenolphthalein. When a rubber bulb full of water is squeezed, the water squirts into the flask. Water from the pan then is pushed into the flask and the indicator changes color. General Chemistry Multimedia Problems ask students questions about experiments they see presented using videos and images. The questions asked apply concepts from different parts of an introductory course, encouraging students to decompartmentalize the material.

34

Ammonia poisoning  

MedlinePLUS

Ammonia gas Some household cleaners Some liniments Some fertilizers Note: This list may not be all-inclusive. ... pulse, breathing rate, and blood pressure. Blood and urine tests will be done. The patient may receive: ...

35

Direct observation of the infinite percolation cluster in thin films: Evidence for a double percolation process  

NASA Astrophysics Data System (ADS)

Direct observation of the infinite percolation cluster at the percolation threshold is shown. We use crystallization propagation in an amorphous thin film. The morphological analysis of the infinite cluster shows good agreement with that predicted by percolation theory. The crystallization process can be described using an invasion percolation model in a fractal network. At the macroscopic scale, crystallization induces a double percolation.

Jensen, Pablo; Melinon, Patrice; Treilleux, Michel; Hu, Jian Xiong; Dumas, Jean; Hoareau, Alain; Cabaud, Bernard

1993-03-01

36

Dimensional Crossover in Directed Percolation.  

National Technical Information Service (NTIS)

We study the dimensional crossover in directed percolation in three dimensions. Bonds are allowed to have different concentrations along the three cartesian axes of the lattice. Through a Position Space Renormalization Group we obtain the phase-diagrams w...

A. M. N. Chame S. L. A. Queiroz R. R. Santos

1984-01-01

37

Percolation model of fire dynamic  

NASA Astrophysics Data System (ADS)

A percolation model for fire dynamic is proposed, with two parameters, related to the combustibility and the ignitability of the medium. The expression of the critical line and of the rate of spread are given in function of that of bond percolation (BP). Finally, the relevance of the model is discussed in the light of results of experiments taken from literature: this simple model catches both the dynamical and static qualitative properties of fire propagation.

Favier, Charly

2004-09-01

38

The Percolation Rate of a Soil  

NSDL National Science Digital Library

This activity demonstrates how particle size and soil texture control water flow, and therefore percolation rate, through a soil. Students will construct a percolation column from a plastic tube and use it to test the percolation rates of three separated soil fractions (sand, silt, and clay). They will add water to samples in the percolation column and record the time it takes to drain out. They then make duration, volume and percolation calculations and answer questions about the soil types.

39

Constraint percolation on hyperbolic lattices  

NASA Astrophysics Data System (ADS)

Constraint percolation models include constraints on the occupation of sites to, for example, better understand the onset of glassiness in glass-forming liquids. The dynamical glass transition in the Fredrickson-Andersen model simplifies to the study of the percolation transition in k-core percolation where every occupied site must have at least k occupied neighbors. Other constraint percolation models, such as force-balance percolation, have been introduced to begin to account for mechanical equilibrium on each particle arising during the onset of jamming. To study a mean-field-like version of force-balance percolation in which the directionality of forces becomes important, we consider clusters with occupied particles satisfying the k=3-core condition and lying inside a triangle determined by three of its occupied neighbors. The model is constructed on a tessellation of the Poincar'e disk, thus, bearing a hyperbolic structure. Models on such spaces exhibit mean-field-like behavior and also play an important role in generating geometric frustration in glassy systems. We analytically investigate the conditions under which there exists a transition as well as the underlying nature of the transition. We also present numerical results to compare with our analytical results.

Lopez, Jorge; Schwarz, J. M.

2012-02-01

40

Ordinary percolation with discontinuous transitions  

NASA Astrophysics Data System (ADS)

Percolation on a one-dimensional lattice and fractals, such as the Sierpinski gasket, is typically considered to be trivial, because they percolate only at full bond density. By dressing up such lattices with small-world bonds, a novel percolation transition with explosive cluster growth can emerge at a non-trivial critical point. There, the usual order parameter, describing the probability of any node to be part of the largest cluster, jumps instantly to a finite value. Here we provide a simple example in the form of a small-world network consisting of a one-dimensional lattice which, when combined with a hierarchy of long-range bonds, reveals many features of this transition in a mathematically rigorous manner.

Boettcher, Stefan; Singh, Vijay; Ziff, Robert M.

2012-04-01

41

Spectral analysis on explosive percolation  

NASA Astrophysics Data System (ADS)

We study the spectral properties of the process of explosive percolation. In particular, we explore how the maximum eigenvalue of the adjacency matrix of a network which governs the spreading efficiency evolves as the density of connection increases. Interestingly, for networks with connectivity that grow in an explosive way, information spreading and mass transport are found to be carried out inefficiently. In the conventional explosive percolation models that we studied, the sudden emergences of large-scale connectivity are found to come with relatively lowered efficiency of spreading. Nevertheless, the spreading efficiency of the explosive model can be increased by introducing heterogeneous structures into the networks.

Chung, N. N.; Chew, L. Y.; Lai, C. H.

2013-03-01

42

From Next Nearest Neighbor Site Percolation to Continuum Percolation:  

NASA Astrophysics Data System (ADS)

In high-Tc superconductors dopant atoms supply holes or excess electrons, and electric conduction is established in the neighborhood of the dopant. We propose that percolation of these conducting areas leads to global electric conduction. To investigate these processes numerical procedures to simulate continuum percolation are developed. The relation between the concentration of connecting discs and the fraction of the area of the plane covered by all discs is computed in the whole range between next nearest neighbor site percolation and continuum percolation. This method is applied to investigate underdoped copper oxides where small hole or excess electron concentrations are insufficient to establish electric conduction. The results of this study are applied to the model of mobile charge carriers which consist of or are accompanied by diffusing d-electrons. Our investigations show that with increasing doping the Neel temperature of the antiferromagnetism vanishes and spin glass states appear in accordance with experiments. Furthermore, the peaks in the specific heat become very broad. This broadening due to randomness and loss of translation invariance has been observed in nuclear magnetic resonance peaks of doped superconducting cuprates.

Stoll, E. P.

43

Direct observation of the infinite percolation cluster in thin films: Evidence for a double percolation process  

Microsoft Academic Search

Direct observation of the infinite percolation cluster at the percolation threshold is shown. We use crystallization propagation in an amorphous thin film. The morphological analysis of the infinite cluster shows good agreement with that predicted by percolation theory. The crystallization process can be described using an invasion percolation model in a fractal network. At the macroscopic scale, crystallization induces a

Pablo Jensen; Patrice Melinon; Michel Treilleux; Jian Xiong Hu; Jean Dumas; Alain Hoareau; Bernard Cabaud

1993-01-01

44

Hierarchical aggregation in percolation model  

Microsoft Academic Search

There is a growing belief that the complex dynamics of seismicity can be better understood by studying the collective behavior of numerous lithosphere instability sources rather than focusing on the details of each of them. Classical site-percolation is a simple and tractable model which exhibits such important general features of complex systems as criticality and phase transitions of second kind.

Ilya Zaliapin; Henry Wong; Andrei Gabrielov

2006-01-01

45

Critical percolation and conformal invariance  

NASA Astrophysics Data System (ADS)

Many 2D critical lattice models are believed to have conformally invariant scaling limits. This belief allowed physicists to predict (unrigorously) many of their properties, including exact values of various dimensions and scaling exponents. We describe some of the recent progress in the mathematical understanding of these models, using critical percolation as an example.

Smirnov, Stanislav

2006-03-01

46

Critical percolation and conformal invariance  

Microsoft Academic Search

Many 2D critical lattice models are believed to have conformally invariant scaling limits. This belief allowed physicists to predict (unrigorously) many of their properties, including exact values of various dimensions and scaling exponents. We describe some of the recent progress in the mathematical understanding of these models, using critical percolation as an example.

Stanislav Smirnov

2006-01-01

47

Responsible recycling  

SciTech Connect

The issues that affect the recycling of lead-acid batteries and the challenges that this issue brings to both the lead industry and to the battery manufacturers are covered. Topics include the lead market (its size and structure), the economic constraints on the recycling system, recycling rates for batteries, the technology of recycling, and future considerations.

Pugh, A. (Britannia Refined Metals, Northfleet (United Kingdom))

1993-05-01

48

Background Information on Ammonia.  

National Technical Information Service (NTIS)

Information on the synthesis, production, and use of ammonia (7664417) is reviewed. The importance of a catalyst in the process of uniting hydrogen and nitrogen to form ammonia, producers of ammonia between 1961 and 1974, their annual production capacity,...

R. Hartle

1975-01-01

49

Ordinary Percolation with Discontinuous Transitions  

NASA Astrophysics Data System (ADS)

We study percolation on hierarchical networks using generating functions and renormalization group techniques. Our exact results show the presence of novel features in these networks including the existence of non-trivial critical points, three distinct regimes in the phase diagram and, most importantly, a discontinuity in the formation of the extensive cluster at a critical point pc<1 . At pc , the order parameter P? describing the probability of any node to be a part of the largest cluster, jumps instantly to a finite value. We present simple examples of small-world networks with various hierarchies of long range bonds, indicating that the presence of discontinuous transitions is generic.[4pt] [1] S. Boettcher, V. Singh, and R.M. Ziff. Ordinary Percolation with Discontinuous Transitions. Arxiv preprint arXiv:1110.4288, (2):25, 2011.

Singh, Vijay; Boettcher, Stefan

2012-02-01

50

Continuum percolation of permeable objects  

NASA Astrophysics Data System (ADS)

We study the extent to which excluded volume determines the percolation threshold for permeable elements in the continuum. An expansion due to Coniglio, De Angelis, Forlani, and Lauro exploits a similarity between the statistical mechanics of hard particles and statistics of percolation of permeable objects. This expansion shows that the expectation value of the excluded volume completely determines the threshold at lowest order in element density. Permeable rods in the continuum may be analyzed with the help of Onsager's treatment of virial coefficients for hard rods. Systems of rods provide cases in which higher-order terms will alter the proportionality of threshold to the inverse of the expected excluded volume and cases in which this proportionality remains exact.

Bug, A. L. R.; Safran, S. A.; Webman, I.

1986-04-01

51

Percolation in the canonical ensemble  

NASA Astrophysics Data System (ADS)

We study the bond percolation problem under the constraint that the total number of occupied bonds is fixed, so that the canonical ensemble applies. We show via an analytical approach that at criticality, the constraint can induce new finite-size corrections with exponent ycan = 2yt - d both in energy-like and magnetic quantities, where yt = 1/? is the thermal renormalization exponent and d is the spatial dimension. Furthermore, we find that while most of the universal parameters remain unchanged, some universal amplitudes, like the excess cluster number, can be modified and become non-universal. We confirm these predictions by extensive Monte Carlo simulations of the two-dimensional percolation problem which has ycan = -1/2. This article is part of ‘Lattice models and integrability’, a special issue of Journal of Physics A: Mathematical and Theoretical in honour of F Y Wu's 80th birthday.

Hu, Hao; Blöte, Henk W. J.; Deng, Youjin

2012-12-01

52

Anomalous diffusion and continuum percolation  

NASA Astrophysics Data System (ADS)

Anomalous diffusion for continuum percolation is simulated by considering systems of randomly distributed circles and spheres. Universal behavior is obtained for the case of equal local conductances and nonuniversal behavior for diverging distributions of the local conductances. Diffusion in the continuum has a behavior consistent with that of other transport properties in the continuum. In addition, the results suggest that different algorithms for diffusion, which differ only in the random walker sitting times, are equivalent.

Wagner, N.; Balberg, I.

1987-10-01

53

Hall effect in percolating systems  

NASA Astrophysics Data System (ADS)

The interpenetrating-network model that Bergman has proposed for the Hall effect in a percolating system is discussed, and it is shown that it gives incorrect exponents in the high-dimensionality limit, because a relevant variable has been excluded. A more general model is proposed which remedies this fault. Simulations of cubic lattices up to L=20 give an estimate for the exponent which describes the divergence of the Hall coefficient at pc:g=0.

Straley, Joseph P.

1988-12-01

54

Percolation in dense storage arrays  

NASA Astrophysics Data System (ADS)

As computers and their accessories become smaller, cheaper, and faster the providers of news, retail sales, and other services we now take for granted on the Internet have met their increasing computing needs by putting more and more computers, hard disks, power supplies, and the data communications linking them to each other and to the rest of the wired world into ever smaller spaces. This has created a new and quite interesting percolation problem. It is no longer desirable to fix computers, storage or switchgear which fail in such a dense array. Attempts to repair things are all too likely to make problems worse. The alternative approach, letting units ``fail in place'', be removed from service and routed around, means that a data communications environment will evolve with an underlying regular structure but a very high density of missing pieces. Some of the properties of this kind of network can be described within the existing paradigm of site or bond percolation on lattices, but other important questions have not been explored. I will discuss 3D arrays of hundreds to thousands of storage servers (something which it is quite feasible to build in the next few years), and show that bandwidth, but not percolation fraction or shortest path lengths, is the critical factor affected by the ``fail in place'' disorder. Redundancy strategies traditionally employed in storage systems may have to be revised. Novel approaches to routing information among the servers have been developed to minimize the impact.

Kirkpatrick, Scott; Wilcke, Winfried W.; Garner, Robert B.; Huels, Harald

2002-11-01

55

Percolation transitions with nonlocal constraint.  

PubMed

We investigate percolation transitions in a nonlocal network model numerically. In this model, each node has an exclusive partner and a link is forbidden between two nodes whose r-neighbors share any exclusive pair. The r-neighbor of a node x is defined as a set of at most N(r) neighbors of x, where N is the total number of nodes. The parameter r controls the strength of a nonlocal effect. The system is found to undergo a percolation transition belonging to the mean-field universality class for r<1/2. On the other hand, for r>1/2, the system undergoes a peculiar phase transition from a nonpercolating phase to a quasicritical phase where the largest cluster size G scales as G~N(?) with ?=0.74(1). In the marginal case with r=1/2, the model displays a percolation transition that does not belong to the mean-field universality class. PMID:23030872

Shim, Pyoung-Seop; Lee, Hyun Keun; Noh, Jae Dong

2012-09-10

56

Recycle City  

NSDL National Science Digital Library

Recycle City contains an interactive city map that demonstrates how residents of every section of the city, formerly Dumptown, have recycled, reduced, and reused waste to turn their town around. There is a Dumptown Game with a Control Center to monitor displays while Dumptown changes as waste reduction programs are put in place. Students can create their own Recycle City scavenger hunt or go to the Activities area and see other ways to put Recycle City to use to help protect the environment.

1997-01-01

57

Hanford recycling.  

National Technical Information Service (NTIS)

This paper is a study of the past and present recycling efforts on the Hanford site and options for future improvements in the recycling program. Until 1996, recycling goals were voluntarily set by the waste generators: this year, DOE has imposed goals fo...

I. M. Leonard

1996-01-01

58

Explosive percolation transitions in Euclidean space  

NASA Astrophysics Data System (ADS)

Since the explosive percolation transition was discovered in a random graph model in the Achlioptas process, whether the explosive percolation transition is indeed discontinuous or continuous has been controversial. Even though extensive studies have been focused on the mean-field behavior of the type of the explosive percolation transition, only a few studies are carried out in Euclidean space, Here, we show that depending on a parameter we introduce, the explosive percolation transition can be either discontinuous or continuous transition in Euclidean space, and is reduced to be continuous in the mean-field limit, which can be shown using an analytic approach.

Sul Cho, Young; Hwang, Sungmin; Jürgen Herrmann, Hans; Kahng, Byungnam

2013-03-01

59

Suppression Effect on Explosive Percolation  

NASA Astrophysics Data System (ADS)

Percolation transitions (PTs) of networks, leading to the formation of a macroscopic cluster, are conventionally considered to be continuous transitions. However, a modified version of the classical random graph model was introduced in which the growth of clusters was suppressed, and a PT occurs explosively at a delayed transition point. Whether the explosive PT is indeed discontinuous or continuous becomes controversial. Here, we show that the behavior of the explosive PT depends on detailed dynamic rules. Thus, when dynamic rules are designed to suppress the growth of all clusters, the discontinuity of the order parameter tends to a finite value as the system size increases, indicating that the explosive PT could be discontinuous.

Cho, Y. S.; Kahng, B.

2011-12-01

60

Percolation in Living Neural Networks  

NASA Astrophysics Data System (ADS)

We study living neural networks by measuring the neurons’ response to a global electrical stimulation. Neural connectivity is lowered by reducing the synaptic strength, chemically blocking neurotransmitter receptors. We use a graph-theoretic approach to show that the connectivity undergoes a percolation transition. This occurs as the giant component disintegrates, characterized by a power law with an exponent ??0.65. ? is independent of the balance between excitatory and inhibitory neurons and indicates that the degree distribution is Gaussian rather than scale free.

Breskin, Ilan; Soriano, Jordi; Moses, Elisha; Tlusty, Tsvi

2006-11-01

61

RECYCLING TODAY  

NSDL National Science Digital Library

We have probably heard of recycling but what is it really and why is it so improtant to do? Please answer the questions below as well as visiting the different websites to explore what recycling really is. Form groups of 4 and explore the following websites as well as answer the questions which follow. The first website is of Recycle City where you will be exploring the City and how they recycle. Recyle City Why Recycling is Important Now please answer the following questions on paper. 1. What are the 3 R's? Explain in further ...

Smith, Miss

2010-12-03

62

Percolation model with continuously varying exponents  

NASA Astrophysics Data System (ADS)

This work analyzes a percolation model on the diamond hierarchical lattice (DHL), where the percolation transition is retarded by the inclusion of a probability of erasing specific connected structures. It has been inspired by the recent interest on the existence of other universality classes of percolation models. The exact scale invariance and renormalization properties of DHL leads to recurrence maps, from which analytical expressions for the critical exponents and precise numerical results in the limit of very large lattices can be derived. The critical exponents ? and ? of the investigated model vary continuously as the erasing probability changes. An adequate choice of the erasing probability leads to the result ?=?, like in some phase transitions involving vortex formation. The percolation transition is continuous, with ?>0, but ? can be as small as desired. The modified percolation model turns out to be equivalent to the Q?1 limit of a Potts model with specific long range interactions on the same lattice.

Andrade, R. F. S.; Herrmann, H. J.

2013-10-01

63

Percolation and scaling on a quasilattice  

SciTech Connect

The authors report results of a study of percolation on a two-dimensional Penrose quasilattice. After an extensive numerical analysis, they find that two-dimensional universality is obeyed. The scaling exponents sigma and tau have the values expected, tau = 2.04 and sigma = 0.39 consistent with the universality class for percolation on a 2D periodic lattice. But the percolation threshold p/sub c/ = 0.483, differs from other 2D lattices with the same average coordination number z vector = 4.

Lu, J.P.; Birman, J.L.

1987-03-01

64

Optical properties of nanocomposites: Percolation films, nanowires, and nanoholes  

Microsoft Academic Search

The optical properties of percolation films, nanowires, nanowire composites, and nanoholes composites were studied theoretically. Developed theory predicts the existence of localized plasmon modes in metal-dielectric percolation films when the metal concentration is close to the percolation threshold. Due to the plasmon localization local fields, local field fluctuations are extremely enhanced on the surface of percolation composite. This explains enormous

Viktor Anatolyevich Podolskiy

2002-01-01

65

Process for treating gases in the ammonia synthesis. [separation and dehydration of gases leaving synthesis reactor  

Microsoft Academic Search

In the synthesis of ammonia, a process is disclosed for treating the gases flowing from the synthesis reactor wherein those gases flow through a film absorber countercurrent to a cooled aqueous film to extract ammonia which is withdrawn as a strong solution from the absorber and scrubbed gases are combined for recycle with a stream of fresh feed which is

Guadalupi

1977-01-01

66

Modeling of heat generation in ammonia-treated solid rocket propellant  

Microsoft Academic Search

With the end of the Cold War, safe, environmentally sound separation, recycling, and disposal of ingredients in solid rocket propellants and munitions has become a national priority. One approach to demilitarize solid rocket propellants is treatment with ammonia. Ammonia extracts the oxidizers ammonium perchlorate and HMX, yielding a solid reside that is more suitable for incineration and less sensitive to

Richard L. Raun; K. Bruce Isom

1995-01-01

67

Percolation model of relative permeability hysteresis  

NASA Astrophysics Data System (ADS)

A mathematical model of relative permeability hysteresis in drainage and imbibition is constructed on the basis of percolation theory. It is shown that the results are in qualitatively agreement with experimental data.

Kadet, V. V.; Galechyan, A. M.

2013-05-01

68

Inducing effect on the percolation transition in complex networks  

NASA Astrophysics Data System (ADS)

Percolation theory concerns the emergence of connected clusters that percolate through a networked system. Previous studies ignored the effect that a node outside the percolating cluster may actively induce its inside neighbours to exit the percolating cluster. Here we study this inducing effect on the classical site percolation and K-core percolation, showing that the inducing effect always causes a discontinuous percolation transition. We precisely predict the percolation threshold and core size for uncorrelated random networks with arbitrary degree distributions. For low-dimensional lattices the percolation threshold fluctuates considerably over realizations, yet we can still predict the core size once the percolation occurs. The core sizes of real-world networks can also be well predicted using degree distribution as the only input. Our work therefore provides a theoretical framework for quantitatively understanding discontinuous breakdown phenomena in various complex systems.

Zhao, Jin-Hua; Zhou, Hai-Jun; Liu, Yang-Yu

2013-09-01

69

Directed Percolation and the Golden Ratio  

Microsoft Academic Search

Applying the theory of Yang-Lee zeros to nonequilibrium critical phenomena,\\u000awe investigate the properties of a directed bond percolation process for a\\u000acomplex percolation parameter p. It is shown that for the Golden Ratio\\u000ap=(1(+\\/-)sqrt(5))\\/2 and for p=2 the survival probability of a cluster can be\\u000acomputed exactly.

Stephan M Dammer; Silvio R Dahmen; Haye Hinrichsenk

2001-01-01

70

Domain walls, percolation theory, and Abell clusters  

SciTech Connect

We consider theories with late-time phase transitions that lead to the formation of energetically soft domain wall effects. These transitions occur in the vacuum state of a weakly coupled scalar field which is not in thermal equilibrium. The spatial properties and distribution of these domain walls are computed using percolation theory. Assuming spherical collapse of matter, the percolation results are used to accurately predict the richness distribution of Abell clusters.

Lalak, Z.; Ovrut, B.A. (Department of Physics, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396 (United States))

1993-08-16

71

Generalized epidemic process and tricritical dynamic percolation  

NASA Astrophysics Data System (ADS)

The renowned general epidemic process describes the stochastic evolution of a population of individuals which are either susceptible, infected, or dead. A second order phase transition belonging to the universality class of dynamic isotropic percolation lies between the endemic and pandemic behavior of the process. We generalize the general epidemic process by introducing a fourth kind of individuals, viz., individuals which are weakened by the process but not yet infected. This weakening gives rise to a mechanism that introduces a global instability in the spreading of the process and therefore opens the possibility of a discontinuous transition in addition to the usual continuous percolation transition. The tricritical point separating the lines of first and second order transitions constitutes an independent universality class, namely, the universality class of tricritical dynamic isotropic percolation. Using renormalized field theory we work out a detailed scaling description of this universality class. We calculate the scaling exponents in an ? expansion below the upper critical dimension dc=5 for various observables describing tricritical percolation clusters and their spreading properties. In a remarkable contrast to the usual percolation transition, the exponents ? and ?' governing the two order parameters, viz., the mean density and the percolation probability, turn out to be different at the tricritical point. In addition to the scaling exponents we calculate for all our static and dynamic observables logarithmic corrections to the mean-field scaling behavior at dc=5 .

Janssen, Hans-Karl; Müller, Martin; Stenull, Olaf

2004-08-01

72

Percolation of dimers on square lattices  

NASA Astrophysics Data System (ADS)

A theoretical approach, based on exact calculations of configurations on finite rectangular cells, is applied to study the percolation of homonuclear dimers on square lattices. An efficient algorithm allows us to calculate the detailed structure of the configuration space for M=Lx×Ly cells, with M varying from 16 to 36. The percolation process has been monitored by following the percolation function, defined as the ratio between the number of percolating configurations and the total number of available configurations for a given cell size and concentration of occupied sites. The percolation threshold has been calculated by means of two complementary methods: one based on well-known renormalization techniques and the other based on determining the inflection point of the percolation function curves. A comparison of the results obtained by these two methods has been performed. The study includes the use of finite-size scaling theory to extrapolate numerical results towards the thermodynamic limit. The effect of jamming due to dimers is also established. Finally, the critical exponents ?, ? and ? have been obtained and values compared with numerical results and expected theoretical estimations. The present results show agreement and even improvement (in the case of ?) with respect to some numeric values available in the literature.

Lebrecht, W.; Valdés, J. F.; Vogel, E. E.; Nieto, F.; Ramirez-Pastor, A. J.

2013-01-01

73

Recycle City  

NSDL National Science Digital Library

Recycling made fun. The Environmental Protection Agency's Recycle City Web site offers students an interactive way to learn how recycling can affect their environment. Users can click any part of the cartoon drawing of the city to learn about that particular building or site and what can be done to decrease waste. The site also contains a more involved exercise called the Dumptown game, where visitors click on City Hall to view various recycling programs and choose the program(s) the city will implement. Once implemented, that activity can be seen taking place in Dumptown. Although the Dumptown exercise may require the help of a teacher to navigate for younger students, both exercises are excellent for K-12 teachers and students.

1997-01-01

74

Application of percolation theory to microtomography of structured media: percolation threshold, critical exponents, and upscaling.  

PubMed

Percolation theory provides a tool for linking microstructure and macroscopic material properties. In this paper, percolation theory is applied to the analysis of microtomographic images for the purpose of deriving scaling laws for upscaling of properties. We have tested the acquisition of quantities such as percolation threshold, crossover length, fractal dimension, and critical exponent of correlation length from microtomography. By inflating or deflating the target phase and percolation analysis, we can get a critical model and an estimation of the percolation threshold. The crossover length is determined from the critical model by numerical simulation. The fractal dimension can be obtained either from the critical model or from the relative size distribution of clusters. Local probabilities of percolation are used to extract the critical exponent of the correlation length. For near-isotropic samples such as sandstone and bread, the approach works very well. For strongly anisotropic samples, such as highly deformed rock (mylonite) and a tree branch, the percolation threshold and fractal dimension can be assessed with accuracy. However, the uncertainty of the correlation length makes it difficult to accurately extract its critical exponents. Therefore, this aspect of percolation theory cannot be reliably used for upscaling properties of strongly anisotropic media. Other methods of upscaling have to be used for such media. PMID:21405743

Liu, Jie; Regenauer-Lieb, Klaus

2011-01-18

75

Percolation Centrality: Quantifying Graph-Theoretic Impact of Nodes during Percolation in Networks  

PubMed Central

A number of centrality measures are available to determine the relative importance of a node in a complex network, and betweenness is prominent among them. However, the existing centrality measures are not adequate in network percolation scenarios (such as during infection transmission in a social network of individuals, spreading of computer viruses on computer networks, or transmission of disease over a network of towns) because they do not account for the changing percolation states of individual nodes. We propose a new measure, percolation centrality, that quantifies relative impact of nodes based on their topological connectivity, as well as their percolation states. The measure can be extended to include random walk based definitions, and its computational complexity is shown to be of the same order as that of betweenness centrality. We demonstrate the usage of percolation centrality by applying it to a canonical network as well as simulated and real world scale-free and random networks.

Piraveenan, Mahendra; Prokopenko, Mikhail; Hossain, Liaquat

2013-01-01

76

Development of ammonia synthesis  

Microsoft Academic Search

Ammonia production is a high energy and capital-intensive industry as it obliges high temperature (400–500°C) and also high pressure (150–300 bar) for its daily processes. Two moles of ammonia are obtained by reacting one mole of nitrogen and three moles of hydrogen gases in the existence of conventional catalyst which are magnetite (Fe3O4). The process to produce ammonia is known

Poppy Puspitasari; Noorhana Yahya

2011-01-01

77

Transport and percolation in complex networks  

NASA Astrophysics Data System (ADS)

To design complex networks with optimal transport properties such as flow efficiency, we consider three approaches to understanding transport and percolation in complex networks. We analyze the effects of randomizing the strengths of connections, randomly adding long-range connections to regular lattices, and percolation of spatially constrained networks. Various real-world networks often have links that are differentiated in terms of their strength, intensity, or capacity. We study the distribution P(?) of the equivalent conductance for Erdo?s-Rényi (ER) and scale-free (SF) weighted resistor networks with N nodes, for which links are assigned with conductance ? i ? e-axi, where xi is a random variable with 0 < xi < 1. We find, both analytically and numerically, that P(?) for ER networks exhibits two regimes: (i) For ? < e-apc, P(?) is independent of N and scales as a power law P(?) ˜ sk/a-1 . Here pc = 1/ is the critical percolation threshold of the network and is the average degree of the network. (ii) For ? > e -apc, P(?) has strong N dependence and scales as P(?) ˜ f(?, apc/N1/3). Transport properties are greatly affected by the topology of networks. We investigate the transport problem in lattices with long-range connections and subject to a cost constraint, seeking design principles for optimal transport networks. Our network is built from a regular d-dimensional lattice to be improved by adding long-range connections with probability Pij ˜ r-aij , where rij is the lattice distance between site i and j. We introduce a cost constraint on the total length of the additional links and find optimal transport in the system for ? = d + 1, established here for d = 1, 2 and 3 for regular lattices and df for fractals. Remarkably, this cost constraint approach remains optimal, regardless of the strategy used for transport, whether based on local or global knowledge of the network structure. To further understand the role that long-range connections play in optimizing the transport of complex systems, we study the percolation of spatially constrained networks. We now consider originally empty lattices embedded in d dimensions by adding long-range connections with the same power law probability p(r) ˜ r -?. We find that, for ? ? d, the percolation transition belongs to the universality class of percolation in ER networks, while for ? > 2d it belongs to the universality class of percolation in regular lattices (for one-dimensional linear chain, there is no percolation transition). However for d < ? < 2d, the percolation properties show new intermediate behavior different from ER networks, with critical exponents that depend on ?.

Li, Guanliang

78

Growth dominates choice in network percolation  

NASA Astrophysics Data System (ADS)

The onset of large-scale connectivity in a network (i.e., percolation) often has a major impact on the function of the system. Traditionally, graph percolation is analyzed by adding edges to a fixed set of initially isolated nodes. Several years ago, it was shown that adding nodes as well as edges to the graph can yield an infinite order transition, which is much smoother than the traditional second-order transition. More recently, it was shown that adding edges via a competitive process to a fixed set of initially isolated nodes can lead to a delayed, extremely abrupt percolation transition with a significant jump in large but finite systems. Here we analyze a process that combines both node arrival and edge competition. If started from a small collection of seed nodes, we show that the impact of node arrival dominates: although we can significantly delay percolation, the transition is of infinite order. Thus, node arrival can mitigate the trade-off between delay and abruptness that is characteristic of explosive percolation transitions. This realization may inspire new design rules where network growth can temper the effects of delay, creating opportunities for network intervention and control.

Vijayaraghavan, Vikram S.; Noël, Pierre-André; Waagen, Alex; D'Souza, Raissa M.

2013-09-01

79

Percolation phenomena in disordered topological networks  

NASA Astrophysics Data System (ADS)

Topological polymer networks consist of circular polymers that are topologically linked. Topological networks made of small circular DNA or protein molecules are of great interest in biology and nanotechnology because they are found in living organisms and can be constructed in-vitro. The physical factors that determine the topology of a network as well as the pathways that are followed for its formation remain poorly understood. In our previous work we proposed a novel biophysical/computational approach to model the formation of planar DNA minicircle networks in trypanosomatid parasites. This model suggests that minicircle networks in trypanosomatid parasites emerged from topologically free minicircles upon space confinement through a percolation pathway. Our model however is somewhat idealized because it assumes that the centers of the minicircles in the network are positioned following a regular planar lattice. Here we propose an extension of the model by allowing the centers of the minicircles to be randomly displaced from the vertices of the lattice. We numerically show that networks form following a percolation pathway upon increasing minicircle density. Our model suggests that the critical percolation density increases as Dperc = 0.8357 - 1.4297 exp(0.6439x) with x is the maximum displacement of the centers of the minicircles. Our results therefore show that the plane distribution of minicircles does not dramatically affect the percolation of minicircles and therefore supports they hypothesis that DNA minicircle networks in trypanosomes evolved through a percolation pathway.

Rodriguez, V.; Diao, Y.; Arsuaga, J.

2013-08-01

80

Textile recycling  

SciTech Connect

The most common household textiles include clothing, linens, draperies, carpets, shoes, handbags, and rugs. Old clothing, of course, is the most readily reused and/or recycled residentially generated textile category. State and/or local mandates to recycle a percentage of the waste stream are providing the impetus to add new materials to existing collection programs. Concurrently, the textile industry is aggressively trying to increase its throughput by seeking new sources of material to meet increased world demand for product. As experienced with drop-off programs for traditional materials, a majority of residents will not recycle materials unless the collection programs are convenient, i.e., curbside collection. The tonnage of marketable textiles currently being landfilled provide evidence of this. It is the authors' contention that if textile recycling is made convenient and accessible to every household in a municipality or region, then the waste stream disposed may be reduced in a similar fashion as when traditional recyclables are included in curbside programs.

Jablonowski, E. (Killam Associates, Millburn, NJ (United States)); Carlton, J.

1995-01-01

81

Metal ammonia solutions: A lattice model approach  

SciTech Connect

A generalized Falicov{endash}Kimball model is applied to study the phase diagram of metal ammonia solutions. The model includes a fluid{endash}fluid interaction term and an electron{endash}fluid interaction with a hard core and an attractive tail. Mean-field theories are derived for the localized and delocalized electron phases using ideas from the slave-boson approach to the Hubbard model. The attractive force stabilizes both the homogeneous delocalized electron phase and a regime where the electrons localize in cavities devoid of fluid particles. In its absence, the localized states are found to be unstable towards phase separation, in contrast to previous predictions. The Gaussian fluctuations and structure factors derived from this theory suggest the existence of bicontinuous channels percolating through the system. These findings agree qualitatively with experiments and computer simulations. {copyright} {ital 1998 American Institute of Physics.}

Leung, K.; Csajka, F.S. [Department of Chemistry, University of California at Berkeley, Berkeley, California 94720 (United States)

1998-06-01

82

Utility of recycled bedding for laboratory rodents.  

PubMed

Animal facilities generate a large amount of used bedding containing excrement as medical waste. We developed a recycling system for used bedding that involves soft hydrothermal processing. In this study, we examined the effects of bedding type on growth, hematologic and serum biochemical values, and organ weights of female and male mice reared on either recycled or fresh bedding from 3 to 33 wk of age. Neither growth nor physiology differed between mice housed on recycled bedding compared with fresh bedding. When 14-wk-old mice were bred, litter size and total number of weaned pups showed no significant differences between animals raised on recycled or fresh bedding. Because bedding type influences the environment within cages and animal rooms, we evaluated particulate and ammonia data from cages and animal rooms. Values were significantly lower from cages and rooms that used recycled bedding than from those using fresh bedding, thus indicating that recycled bedding has the potential to improve the environment within both cages and animal rooms. Overall, this study revealed that recycled bedding is an excellent material for use in housing laboratory rodents. Specifically, recycled bedding may reduce medical waste and maintain healthy environments within cages and animal rooms. PMID:19653951

Miyamoto, Toru; Li, Zhixia; Kibushi, Tomomi; Okano, Shinya; Yamasaki, Nakamichi; Kasai, Noriyuki

2009-07-01

83

Accessibility percolation on n-trees  

NASA Astrophysics Data System (ADS)

Accessibility percolation is a new type of percolation problem inspired by evolutionary biology. To each vertex of a graph a random number is assigned and a path through the graph is called accessible if all numbers along the path are in ascending order. For the case when the random variables are independent and identically distributed, we derive an asymptotically exact expression for the probability that there is at least one accessible path from the root to the leaves in an n-tree. This probability tends to 1 (0) if the branching number is increased with the height of the tree faster (slower) than linearly. When the random variables are biased such that the mean value increases linearly with the distance from the root, a percolation threshold emerges at a finite value of the bias.

Nowak, S.; Krug, J.

2013-03-01

84

Recycling polyurethanes  

SciTech Connect

This article reports on the PolyUrethane Recycle and Recovery Council`s continuing evaluation of the technical and commercial viability of polyurethane recovery and recycling technologies. In North America, 240,000 tonnes of post-industrial and 16,000 tonnes of post-consumer polyurethane foam was recycled into carpet rebound underlay and other applications in 1993. Demand was so great in North America that 60,000 t of primarily post-industrial scarp was imported from Europe and the Far East. Polyurethane from the seats of the 9 million vehicles scrapped each year could yield 82,000 t of flexible post-consumer foam scrap: instrument and door panels could yield another 10,000 t of semi-flexible scrap.

NONE

1995-08-01

85

Recycled pulsars  

NASA Astrophysics Data System (ADS)

Pulsars that have undergone a binary history have come to be known as "recycled pulsars". The very first binary pulsar to be discovered-the Hulse-Taylor pulsar-provided evidence for such a recycling. It is now widely accepted that the first-born neutron star dies a natural death as a pulsar due to its period lengthening. But eventually, it is spun back into life, once again, when it accretes matter and angular momentum from its companion. Such a spin up continues till the neutron star attains an "equilibrium period", which is determined by the strength of its magnetic field and the accretion rate. This article will attempt to give a historical perspective of how the various steps in the evolution of such a recycled neutron star were understood.

Srinivasan, G.

2010-03-01

86

Method for forming ammonia  

DOEpatents

A method for forming ammonia is disclosed and which includes the steps of forming a plasma; providing a source of metal particles, and supplying the metal particles to the plasma to form metal nitride particles; and providing a substance, and reacting the metal nitride particles with the substance to produce ammonia, and an oxide byproduct.

Kong; ,Peter C. (Idaho Falls, ID); Pink, Robert J. (Pocatello, ID); Zuck, Larry D. (Idaho Falls, ID)

2008-08-19

87

Assessing Ammonia Treatment Options  

EPA Science Inventory

This is the second of three articles to help water system operators understand ammonia and how to monitor and control its effects at the plant and in the distribution system. The first article (Opflow, April 2012) provided an overview of ammonia's chemistry, origins, and water sy...

88

DWPF recycle stream corrosion tests  

SciTech Connect

Coupon immersion tests were performed on ASTM A537 Class 1 carbon steel in simulated DWPF recycle solutions at 90 [+-] 2[degrees]C, as part of the continuing effort to investigate the formation of shock-sensitive deposits. Coupons were partially immersed for four months in solutions of the same composition used previously at SRTC and at the DuPont Engineering Test Center (a salt solution containing 0.5 M hydroxide and 0.043 M nitrite). Shock-sensitive deposits were not seen on the coupons from this test. There was considerable general corrosion above the water line due to condensate and distilled water contact of the steel. New immersion tests are being planned for completion by September, 1993. The new test solution will reflect the recycle stream chemistry changes brought about by planned ammonia scrubbing in the DWPF.

Zapp, P.E.

1993-04-21

89

Dynamic Renormalization and Continuity of the Percolation Transition in Orthants  

Microsoft Academic Search

\\u000a A dynamic renormalization procedure, presented in the context of independent nearest-neighbor percolation in the d-dimensional orthant ?+\\u000a d implies the absence of percolation at the critical point, together with related results.

David J. Barsky; Geoffrey R. Grimmett; Charles M. Newman

90

Endocytic recycling  

Microsoft Academic Search

After endocytosis, most membrane proteins and lipids return to the cell surface, but some membrane components are delivered to late endosomes or the Golgi. We now understand that the pathways taken by internalized molecules that eventually recycle to the cell surface can be surprisingly complex and can involve a series of sorting events that occur in several organelles. The molecular

Frederick R. Maxfield; Timothy E. McGraw

2004-01-01

91

Pivotal, cluster and interface measures for critical planar percolation  

Microsoft Academic Search

This work is the first in a series of papers devoted to the construction and study of scaling limits of dynamical and near-critical planar percolation and related objects like invasion percolation and the Minimal Spanning Tree. We show here that the counting measure on the set of pivotal points of critical site percolation on the triangular grid, normalized appropriately, has

Christophe Garban; Gábor Pete; Oded Schramm

2010-01-01

92

Bootstrap Percolation: A Renormalization Group Approach.  

National Technical Information Service (NTIS)

In bootstrap percolation, sites are occupied at random with probability p, but each site is considered active only if at least m of its neighbours are also active. Within an approximate position-space renormalization group framework on a square lattice, w...

N. S. Branco R. R. Santos S. L. A. Queiroz

1984-01-01

93

Crossover from isotropic to directed percolation  

NASA Astrophysics Data System (ADS)

We generalize the directed percolation (DP) model by relaxing the strict directionality of DP such that propagation can occur in either direction but with anisotropic probabilities. We denote the probabilities as p?=ppd and p?=p(1-pd), with p representing the average occupation probability and pd controlling the anisotropy. The Leath-Alexandrowicz method is used to grow a cluster from an active seed site. We call this model with two main growth directions biased directed percolation (BDP). Standard isotropic percolation (IP) and DP are the two limiting cases of the BDP model, corresponding to pd=1/2 and pd=0,1 respectively. In this work, besides IP and DP, we also consider the 1/2percolation thresholds of the BDP model for pd=0.6 and 0.8, and determine various critical exponents. These exponents are found to be consistent with those for standard DP. We also determine the renormalization exponent associated with the asymmetric perturbation due to pd-1/2?0 near IP, and confirm that such an asymmetric scaling field is relevant at IP.

Zhou, Zongzheng; Yang, Ji; Ziff, Robert M.; Deng, Youjin

2012-08-01

94

Disorder-induced Limited Path Percolation  

NASA Astrophysics Data System (ADS)

We introduce a model of percolation induced by disorder, where an initially homogeneous network with links of equal weight is disordered by the introduction of heterogeneous weights for the links. We consider a pair of nodes i and j to be mutually reachable when the ratio ?ij of the optimal path length between them before and after the introduction of disorder does not increase beyond a tolerance ratio ?. These conditions reflect practical limitations of reachability better than the usual percolation model, which entirely disregards path length when defining connectivity and, therefore, communication. We find that this model leads to a first-order phase transition in both 2-dimensional lattices and in Erd?s-Rényi networks, and in the case of the latter, the size of the discontinuity implies that the transition is effectively catastrophic, with almost all system pairs undergoing the change from reachable to unreachable. Using the theory of optimal path lengths under disorder, we are able to predict the percolation threshold. For real networks subject to changes while in operation, this model should perform better in predicting functional limits than current percolation models.

López, E.; Braunstein, L. A.

2012-03-01

95

Superdiffusivity in first-passage percolation  

Microsoft Academic Search

Summary.  In standard first-passage percolation on (with ), the time-minimizing paths from a point to a plane at distance are expected to have transverse fluctuations of order . It has been conjectured that with the inequality strict (superdiffusivity) at least for low and with . We prove (versions of) for all and .

C. Licea; C. M. Newman; M. S. T. Piza

1996-01-01

96

Percolation in a fractional Brownian motion lattice  

SciTech Connect

Many applications of engineering interest involve spatially correlated properties obeying the statistics of fractional Brownian motion (fBm). Of specific interest to this note are percolation processes in a field described by fBm. There are two applications where such processes may arise: The immiscible displacement of one fluid by another in a 2-D fracture, the aperture of which obeys fBm statistics; and the same displacement in a heterogeneous porous medium, the permeability of which obeys fBm statistics. In either case, it is assumed that capillary forces dominate the displacement. In previous works, Yortsos and Chang (1990) and van Batenburg et al. (1991) simulated displacements in such fields by considering both capillary and viscous forces. Here, the authors consider the case where viscous forces are small (low flow rates). As capillary-controlled displacement is described by invasion percolation (IP), the problem of interest is one of percolation in a correlated lattice. In this note the authors present numerical results of both ordinary percolation and IP in an fBm lattice, which expand on their previous study (Satik and Yortsos, 1991) and support the findings of Isichenko (1992) and Schmittbuhl et al. (1993). The statistics of the random variables p{sub c} and P(p, H) obtained should be useful in problems involving fBm lattices. More generally, the results should be useful in the study of invasion processes in correlated media.

Du, C.; Satik, C.; Yortsos, Y.C. [Univ. of Southern California, Los Angeles, CA (United States)

1996-08-01

97

Percolation on general trees and HIV modeling  

NASA Astrophysics Data System (ADS)

Percolation on a general tree is studied. A general tree is used to model the transition from HIV infection into AIDS and to explain the large differences of the transition time from one patient to another. HIV has some autoimmune effects due to its low antigenic mutants. Fuzzy mathematics is used to explain these effects.

Ahmed, E.; Agiza, H. N.

1996-12-01

98

Spatial Gossip on the Percolation Model  

Microsoft Academic Search

For scalability and reliability, gossip protocol is widely used in distributed database updates, information dissemination, membership maintenance et al. Spatial gossip [9], which means gossiping within a finite distance independent of the network size, was also proposed to rapidly locate resource in some networks, such as wireless sensor networks. The previous study on spatial gossip used a percolation model, where

Qi Xia; Ruijun Yang; Weinong Wang

2005-01-01

99

Random Walks and Percolation on Trees  

Microsoft Academic Search

There is a way to define an average number of branches per vertex for an arbitrary infinite locally finite tree. It equals the exponential of the Hausdorff dimension of the boundary in an appropriate metric. Its importance for probabilistic processes on a tree is shown in several ways, including random walk and percolation, where it provides points of phase transition.

Russell Lyons

1990-01-01

100

Bootstrap Percolation: A Renormalisation Group Approach.  

National Technical Information Service (NTIS)

In bootstrap percolation, sites are occupied at random with probability p, but each site is considered active only if at least m of its neighbors are also active. Within an approximate position-space renormalisation group framework on a square lattice, we...

N. S. Branco R. R. dos Santos S. L. A. de Queiroz

1983-01-01

101

Directed Percolation with Colors and Flavors  

Microsoft Academic Search

A model of directed percolation processes with colors and flavors that is equivalent to a population model with many species near their extinction thresholds is presented. We use renormalized field theory and demonstrate that all renormalizations needed for the calculation of the universal scaling behavior near the multicritical point can be gained from the one-species Gribov process (Reggeon field theory).

Hans-Karl Janssen

2001-01-01

102

Assessment of Deep Percolation in Citrus Orchard  

Microsoft Academic Search

Australian irrigators are under considerable pressure to increase irrigation efficiency and reduce deep drainage, driven by environmental and economic imperatives. Capacitance probe sensors are relatively cheap and popular electromagnetic equipment to measure soil water content. A field experiment was performed with capacitance probe in Mallee area of Australia, to collect the water content dynamics and deep percolation below of root

Fachao Zhou; Jinzhong Yang; Tapas Biswas

2010-01-01

103

Virtual Pervious Concrete: Microstructure, Percolation, and Permeability  

Microsoft Academic Search

As the usage of pervious concrete continues to increase dramatically, a better understanding of the linkages between microstructure, transport properties, and durability will assist suppliers in mixture proportioning and design. This paper presents various virtual pervious concrete microstructural models and compares their percolation characteristics and computed transport properties to those of real world pervious concretes. Of the various virtual pervious

Dale P. Bentz

2007-01-01

104

Molecular Structure of Ammonia  

NSDL National Science Digital Library

Ammonia is a non-ionic colorless gas at ambient temperatures and a hydrogen bonding liquid at 240 Kelvin that has the remarkable ability to dissolve alkali metals. Ammonia is a Lewis base and is readily absorbed by water to form small amounts of ammonium hydroxide (pKb = 4.74). Naturally, ammonia has its sources in the biosphere (the nitrogen cycle) and is a trace gas in air and a source of ammonium ions in rain and atmospheric aerosols. Ammonia is prepared industrially by the Haber-Bosch process in quantities exceeding 120 million metric tons per year. In this process, ammonia gas is formed when hydrogen and nitrogen (3:1) are compressed to pressures of 200 atm and passed over an iron catalyst at 380-450 degrees C. Much of the ammonia produced this way (85%) is used as fertilizers on crops, a significant portion of which leaches from croplands into streams causing nitrate pollution and eutrophication of waterways (e.g., dead-zone in the Gulf of Mexico). Other sources of ammonia include combustion (coal and biomass burning) and from bacterial decomposition of animal excreta.

2006-05-02

105

Steel Recycling Institute (SRI)  

NSDL National Science Digital Library

The Steel Recycling Institute (SRI) provides information and statistics on steel recycling; it was founded by a group of steel companies and the American Iron and Steel Institute (AISI). Originally a grassroots effort focused only on the recycling of steel cans, the SRI now promotes the recycling of all steel products. The SRI homepage provides online access to its three publications, The Dockside Recycler, The Recycling Magnet, and The Appliance Recycler. Recycling information is divided into four categories: cans, cars, appliances, and construction material. Users can use the recycling database to find the nearest steel recycling location. Links provides a large list of both commercial and non-commercial steel sites.

1998-01-01

106

Process for synthesizing ammonia  

SciTech Connect

In a continuous ammonia synthesis process in which a synthesis gas mixture containing nitrogen and hydrogen is passed sequentially over two or more catalyst beds containing ammonia synthesis catalyst to produce a gaseous effluent from each of the catalyst beds containing ammonia and unreacted nitrogen and hydrogen, the improvements is described which comprises cooling the gaseous effluent from the first of the catalyst beds, before the effluent enters the second catalyst bed, by heat exchange in a stream superheater to control the temperature of the effluent entering the second catalyst bed to a desired level.

Grotz, B.J.

1988-05-17

107

Disinfection of secondary effluents by infiltration percolation.  

PubMed

Among the most attractive applications of reclaimed wastewater are: irrigation of public parks, sports fields, golf courses and market gardening. These uses require advanced wastewater treatment including disinfection. According to WHO guidelines (1989) and current rules and regulations in Tunisia, faecal coliform levels have to be reduced to < 10(3) or 10(2) CFU/100 mL. In Tunisia, most wastewater plants are only secondary treatment and, in order to meet health related regulations, the effluents need to be disinfected. However, it is usual for secondary effluents to need filtration prior to disinfection. Effectiveness of conventional disinfection processes, such as chlorination and UV radiation, are dependent upon the oxidation level and the levels of suspended solids of the treated water. Ozonation is relatively expensive and energy consuming. The consideration of the advantages and disadvantages of conventional techniques, their reliability, investment needs and operational costs will lead to the use of less sophisticated alternative techniques for certain facilities. Among alternative techniques, soil aquifer treatment and infiltration percolation through sand beds have been studied in Arizona, Israel, France, Spain and Morocco. Infiltration percolation plants have been intermittently fed with secondary or high quality primary effluents which percolated through 1.5-2 m unsaturated coarse sand and were recovered by under-drains. In such infiltration percolation facilities, microorganisms were eliminated through numerous physical, physicochemical and biological inter-related processes (mechanical filtration, adsorption and microbial degradation respectively). Efficiency of faecal coliform removal was dependent upon the water detention times in the filtering medium and on the oxidation of the filtered water. Effluents of Sfax town aerated ponds were infiltrated through 1.5 m deep sand columns in order to determine the performance of infiltration percolation in the polishing of secondary effluents. Elimination of bacteria (total and coliforms, faecal streptococci) and their relationship with the hydraulic load and the temperature were investigated. PMID:11464749

Makni, H

2001-01-01

108

Phase transitions in supercritical explosive percolation  

NASA Astrophysics Data System (ADS)

Percolation describes the sudden emergence of large-scale connectivity as edges are added to a lattice or random network. In the Bohman-Frieze-Wormald model (BFW) of percolation, edges sampled from a random graph are considered individually and either added to the graph or rejected provided that the fraction of accepted edges is never smaller than a decreasing function with asymptotic value of ?, a constant. The BFW process has been studied as a model system for investigating the underlying mechanisms leading to discontinuous phase transitions in percolation. Here we focus on the regime ??[0.6,0.95] where it is known that only one giant component, denoted C1, initially appears at the discontinuous phase transition. We show that at some point in the supercritical regime C1 stops growing and eventually a second giant component, denoted C2, emerges in a continuous percolation transition. The delay between the emergence of C1 and C2 and their asymptotic sizes both depend on the value of ? and we establish by several techniques that there exists a bifurcation point ?c=0.763±0.002. For ??[0.6,?c), C1 stops growing the instant it emerges and the delay between the emergence of C1 and C2 decreases with increasing ?. For ??(?c,0.95], in contrast, C1 continues growing into the supercritical regime and the delay between the emergence of C1 and C2 increases with increasing ?. As we show, ?c marks the minimal delay possible between the emergence of C1 and C2 (i.e., the smallest edge density for which C2 can exist). We also establish many features of the continuous percolation of C2 including scaling exponents and relations.

Chen, Wei; Nagler, Jan; Cheng, Xueqi; Jin, Xiaolong; Shen, Huawei; Zheng, Zhiming; D'Souza, Raissa M.

2013-05-01

109

Recycling BIOPOL–Composting and Material Recycling  

Microsoft Academic Search

The recycling of biodegradable thermoplastics such as ZENECA's BIOPOL range of poly-3-hydroxybutyrate and poly-3-hydroxyvalerate copolymers needs to be considered in terms of both material recycling and organic recycling by composting. BIOPOL can be recycled as regrind. The addition of BIOPOL to a model waste stream demonstrates that at the anticipated addition levels, BIOPOL should not have a deleterious effect on

M. K. Cox

1995-01-01

110

Monitoring ammonia to assess halitosis  

Microsoft Academic Search

Objective. This study examined the applicability of ammonia monitoring for assessing halitosis. Study Design. The actual degree of halitosis was determined by using an organoleptic test in 61 subjects aged 28 ± 10 years (mean ± SD). Levels of volatile sulfur compounds and ammonia were determined by using gas chromatography and ammonia monitoring, respectively. Levels of ammonia and methyl mercaptan

Akiko Amano; Yasuo Yoshida; Takahiko Oho; Toshihiko Koga

2002-01-01

111

Reactor for removing ammonia  

DOEpatents

Disclosed is a device for removing trace amounts of ammonia from a stream of gas, particularly hydrogen gas, prepared by a reformation apparatus. The apparatus is used to prevent PEM "poisoning" in a fuel cell receiving the incoming hydrogen stream.

Luo, Weifang (Livermore, CA); Stewart, Kenneth D. (Valley Springs, CA)

2009-11-17

112

Ammonia Production Systems Integration.  

National Technical Information Service (NTIS)

Conceptual designs of 11 mobile ammonia fuel production systems were prepared. These systems represent various combinations of total electric power to the system, mobility class, electrical power frequency, and cooling medium. This report presents a descr...

B. N. Thomson G. E. Hook N. T. Mills R. A. Coval R. M. Reinstrom

1966-01-01

113

Computer Recycling  

NSDL National Science Digital Library

Given current rates of computer consumerism and technological advances, one might expect to find a lot of computers out there in the world. What happens to these old computers? This Topic in Depth explores this issue, reviews some options for recycling computers, and provides tips for anyone considering purchasing a refurbished computer. The first article from BBC News (1) reports on research which suggests that "the number of personal computers worldwide is expected to double by 2010 to 1.3 billion machines." The second article from Oasis, a project of the Irish eGovernment initiative, (2) reviews some of the issues surrounding waste from electrical and electronic equipment. This next article from PC World (3) gives some ideas for how to dispose of an old notebook computer. One option, of course, is to donate your notebook, which is discussed in this article from Tech Soup (4). Another resource for information on computer recycling and reuse is this website from CompuMentor (5). Given the current market for computers, many are considering refurbished computers. This article from Vnunet (6 ) explains what a refurbished computer is while the next website provides some tips for buying a refurbished computer (7 ). Finally, this article from About.com reports on the recently introduced National Computer Recycling Act (8).

114

Titan's Ammonia Feature  

NASA Astrophysics Data System (ADS)

NH3 has long been considered an important component in the formation and evolution of the outer planet satellites. NH3 is particularly important for Titan, since it may serve as the reservoir for atmospheric nitrogen. A brightening seen on Titan starting in 2004 may arise from a transient low-lying fog or surface coating of ammonia. The spectral shape suggests the ammonia is anhydrous, a molecule that hydrates quickly in the presence of water.

Smythe, W.; Nelson, R.; Boryta, M.; Choukroun, M.

2011-10-01

115

Critical Percolation, Universality, and SLE6  

NASA Astrophysics Data System (ADS)

Since the introduction of the Schramm-Loewner-Evolution (SLE) in 2000 ([25]), tremendous progress has been made in rigorously understanding the scaling limits of various 2D critical statistical mechanics models in two dimensions (see [22]). The starting point of understanding the scaling limit of a 2D critical lattice model is to consider the model on a bounded domain O ? R2 and find a suitable observable at the discrete level which satisfies some discrete analyticity or harmonicity limit and, together with establishment of suitable boundary values, leads to conformal invariance in the continuum limit. For percolation, the appropriate observable is the crossing probability - conjectured to converge to the so-called Cardy's Formula in the continuum. In [7], Smirnov established conformal invariance of critical site percolation on the triangular lattice (in the scaling limit) by considering a triplet of observables related to crossing probability. However, Smirnov's proof takes advantage of the complete symmetry in the case of site percolation on the triangular lattice, and the triplet observables do not easily adapt themselves to percolation on other lattices. This dissertation, representing joint work with L. Chayes and I. Binder (see [4], [5], [1], [2], [3]), contains construction of a non-trivial class of models for which we establish Cardy's Formula and, following the approach outlined in [8], establishes convergence to SLE6 for the law of the interface, thus establishing some limited statement of universality. In the course of (and in addition to) accomplishing this, we obtain some results which may find applicability to other percolation models: (1) We show how to extract Cardy's Formula given some interior analyticity statement (this requires some treatment of the discretization procedure in relation to retrieval of suitable boundary values) for a general class of domains; (2) our convergence to SLE6 proof is applicable for any percolation model satisfying reasonable assumptions and for which Cardy's Formula can be established; (3) we obtain some (almost) uniform estimates on crossing probabilities which may lead to some statement of rate of convergence to SLE6.

Lei, Guo-Ying

116

Factors affecting product yields and oil quality during retorting of Stuart oil shale with recycled shale: a screening study  

Microsoft Academic Search

Seven process variables—retort temperature, solids recycle ratio, char content of recycle solids, recycle solids temperature, pretreatment of recycle solids with ammonia, solids residence time and steam concentration—were studied. The Plackett-Burman statistical experimental design, highly effective for detecting main effects of large number of variables with a minimum number of experiments, was used to screen these variables. Each variable was tested

Nguyen V. Dung

1995-01-01

117

Integration of a turbine expander with an exothermic reactor loop—Flow sheet development and application to ammonia production  

Microsoft Academic Search

This paper investigates the direct integration of a gas turbine power cycle with an ammonia synthesis loop. Such a loop represents a typical reactor–separator system with a recycle stream and cold separation of the product from the recycle loop. The hot reaction products are expanded directly instead of raising steam in a waste heat boiler to drive a steam turbine.

I. L. Greeff; J. A. Visser; K. J. Ptasinski; F. J. J. G. Janssen

2003-01-01

118

Recycling Lesson Plans.  

ERIC Educational Resources Information Center

|This document contains lesson plans about recycling for teachers in grades K-12. Titles include: (1) "Waste--Where Does It Come From? Where Does It Go?" (2) "Litter Detectives," (3) "Classroom Paper Recycling," (4) "Recycling Survey," (5) "Disposal and Recycling Costs," (6) "Composting Project," (7) Used Motor Oil Recycling," (8) "Unwrapping…

Pennsylvania State Dept. of Environmental Resources, Harrisburg.

119

Green Science: Revisiting Recycling  

ERIC Educational Resources Information Center

|Recycling has been around for a long time--people have reused materials and refashioned them into needed items for thousands of years. More recently, war efforts encouraged conservation and reuse of materials, and in the 1970s recycling got its official start when recycling centers were created. Now, curbside recycling programs and recycling

Palliser, Janna

2011-01-01

120

Green Science: Revisiting Recycling  

ERIC Educational Resources Information Center

Recycling has been around for a long time--people have reused materials and refashioned them into needed items for thousands of years. More recently, war efforts encouraged conservation and reuse of materials, and in the 1970s recycling got its official start when recycling centers were created. Now, curbside recycling programs and recycling

Palliser, Janna

2011-01-01

121

Percolation and Tunneling in Composite Materials  

NASA Astrophysics Data System (ADS)

Classical percolation theory is concerned with the onset of geometrical connectivity and the accompanied onset of electrical connectivity in disordered systems. It was found, however, that in many systems, such as various composites, the geometrical and electrical onsets of the connectivity are not simultaneous and the correlation between them depends on physical processes such as tunneling. The difference between the above two types of systems and the consequences for the electrical transport properties of the latter composites have been largely ignored in the past. The application of scanning local probe microscopies and some recent theoretical developments have enabled a better understanding of the latter systems and their sometimes "strange" behavior as bona fide percolation systems. In this review we consider the above issues and their manifestation in three types of systems: Carbon Black-Polymer composites, metal-insulator cermets and hydrogenated microcrystalline silicon.

Balberg, I.; Azulay, D.; Toker, D.; Millo, O.

122

Percolation and criticality in a mitochondrial network.  

PubMed

Synchronization of mitochondrial function is an important determinant of cell physiology and survival, yet little is known about the mechanism of interorganellar communication. We have recently observed that coordinated cell-wide oscillations in the mitochondrial energy state of heart cells can be induced by a highly localized perturbation of a few elements of the mitochondrial network, indicating that mitochondria represent a complex, self-organized system. Here, we apply percolation theory to explain the mechanism of intermitochondrial signal propagation in response to oxidative stress. A global phase transition (mitochondrial depolarization) is shown to occur when a critical density of mitochondria accumulate reactive oxygen species above a threshold to form an extended spanning cluster. The scaling and fractal properties of the mitochondrial network at the edge of instability agree remarkably well with the idea that mitochondria are organized as a percolation matrix, with reactive oxygen species as a key messenger. PMID:15070738

Aon, Miguel A; Cortassa, Sonia; O'Rourke, Brian

2004-03-18

123

Percolation and criticality in a mitochondrial network  

PubMed Central

Synchronization of mitochondrial function is an important determinant of cell physiology and survival, yet little is known about the mechanism of interorganellar communication. We have recently observed that coordinated cell-wide oscillations in the mitochondrial energy state of heart cells can be induced by a highly localized perturbation of a few elements of the mitochondrial network, indicating that mitochondria represent a complex, self-organized system. Here, we apply percolation theory to explain the mechanism of intermitochondrial signal propagation in response to oxidative stress. A global phase transition (mitochondrial depolarization) is shown to occur when a critical density of mitochondria accumulate reactive oxygen species above a threshold to form an extended spanning cluster. The scaling and fractal properties of the mitochondrial network at the edge of instability agree remarkably well with the idea that mitochondria are organized as a percolation matrix, with reactive oxygen species as a key messenger.

Aon, Miguel A.; Cortassa, Sonia; O'Rourke, Brian

2004-01-01

124

Transit time during the interparticle percolation process.  

PubMed

A numerical investigation of jamming effect during the spontaneous interparticle percolation process of small beads through an unconsolidated porous media has been performed. The size ratio between the moving beads and the ones building up the porous medium was chosen larger than the geometrical trapping threshold: ?(c)=(2/?3]-1)(-1)=6.464.... In this paper, we used the discrete element method algorithm to study the rebounds of particles on the top of the porous medium and the transit times of an assembly of particles through it. Several parameters such as the number of injected particles, the size ratio between beads, and the energy restitution coefficient are investigated. This study leads to give some important results of the evolution of the transit time versus the contiguous volume occupied by the percolating particles. PMID:21230267

Lominé, Franck; Oger, Luc

2010-10-06

125

a Theoretical Analysis of a Percolation Model  

NASA Astrophysics Data System (ADS)

This is an analytical analysis of a previously published research for a percolation simulation. In that research the effect of mutations on adaptability was investigated in a bit-string model of invading species in a random environment. However, analytical analysis was missing which will be the topic here. The Hausdorff dimensions are calculated for the fractals and the conditions on invasion are analyzed analytically by manipulation of partial differential equations. Thus, various conclusions may be reached without having to run long simulations.

Taneri, Sencer

2012-10-01

126

Percolative transport in fractal porous media  

Microsoft Academic Search

Application of continuum percolation theory to a fractal pore space model yields results for the constitutive relationships for unsaturated flow in agreement with experiment. This application also unites understanding in that the same dry end moisture content, ?t=0.039SAvol0.52 as a function of the surface area to volume ratio, is shown to be associated with the deviation of experimental water retention

A. G. Hunt

2004-01-01

127

The Transition from ERD?S-RÉNYI Percolation to Explosive Percolation Under the Partial Product Rule  

NASA Astrophysics Data System (ADS)

Explosive percolation proposed by Achlioptas et al. has attracted much attention recently. To understand how the product rule delays the phase transition, in this paper, we will concentrate our efforts on the influence of product rule in the transition from Erd?s-Rényi (ER) percolation to Achlioptas explosive percolation. In our model, only a fraction of the adding edges will obey the product rule. With the probability p, the edge is selected under the Achlioptas's product rule; with 1 - p the edge is added between two randomly chosen nodes, that is, the ER rule. When the product rule plays a dominant role in the evolution, p > 0.5, the percolation transition delays more abruptly and instantaneously. The location of the critical points is independent of the network size and satisfies tc=(tc {AP}-tc {ER})p+tc {ER}, where tc {ER} and tc {AP} are the critical points of ER percolation and Achlioptas one. We present the largest gap ?smax and the critical region ? as a function of p and N. The giant component s in terms of the edge density t above tc is also analyzed. We find that all the critical values have a linear relationship against p.

Chi, Liping; Cai, Xu

2012-12-01

128

A biological semiconductor based on electrical percolation  

PubMed Central

We have developed a novel biological semiconductor (BSC) based on electrical percolation through a multi-layer 3-D carbon nanotube-antibody network, which can measure biological interactions directly and electronically. In Electrical Percolation, the passage of current through the conductive network is dependent upon the continuity of the network. Molecular interactions, such as binding of antigens to the antibodies, disrupt the network continuity causing increased resistance of the network. A BSC is fabricated by immobilizing a pre-functionalized single-walled carbon nanotubes (SWNTs)-antibody complex directly on a Poly(methyl methacrylate) (PMMA) surface (also known as plexi-glass or Acrylic). We used the BSC for direct (label-free) electronic measurements of antibody-antigen binding, showing that, at slightly above the electrical percolation threshold of the network, binding of a specific antigen dramatically increases the electrical resistance. Using anti-Staphylococcal enterotoxin B (SEB) IgG as a “gate” and SEB as an “actuator”, we demonstrated that the BSC was able to detect SEB at concentrations of 1 ng/ml. The new BSCs may permit assembly of multiple sensors on the same chip to create “Biological Central Processing Units (CPUs)” with multiple biological elements, capable of processing and sorting out information on multiple analytes simultaneously.

Yang, Minghui; Bruck, Hugh Alan; Kostov, Yordan; Rasooly, Avraham

2010-01-01

129

Contact percolation transition in athermal particulate systems.  

PubMed

Typical quasistatic compression algorithms for generating jammed packings of purely repulsive, frictionless particles begin with dilute configurations and then apply successive compressions with the relaxation of the elastic energy allowed between each compression step. It is well known that during isotropic compression these systems undergo a first-order-like jamming transition at packing fraction ?(J) from an unjammed state with zero pressure and no force-bearing contacts to a jammed, rigid state with nonzero pressure, a percolating network of force-bearing contacts, and contact number z=2d, where d is the spatial dimension. Using computer simulations of two-dimensional systems with monodisperse and bidisperse particle size distributions, we investigate the second-order-like contact percolation transition, which precedes the jamming transition with ?(P)percolation transition also signals the onset of a nontrivial mechanical response to applied stress. Our results show that cooperative particle motion occurs in unjammed systems significantly below the jamming transition for ?(P)?(J). PMID:22400566

Shen, Tianqi; O'Hern, Corey S; Shattuck, M D

2012-01-27

130

Contact percolation transition in athermal particulate systems  

NASA Astrophysics Data System (ADS)

Typical quasistatic compression algorithms for generating jammed packings of purely repulsive, frictionless particles begin with dilute configurations and then apply successive compressions with the relaxation of the elastic energy allowed between each compression step. It is well known that during isotropic compression these systems undergo a first-order-like jamming transition at packing fraction ?J from an unjammed state with zero pressure and no force-bearing contacts to a jammed, rigid state with nonzero pressure, a percolating network of force-bearing contacts, and contact number z=2d, where d is the spatial dimension. Using computer simulations of two-dimensional systems with monodisperse and bidisperse particle size distributions, we investigate the second-order-like contact percolation transition, which precedes the jamming transition with ?Ppercolation transition also signals the onset of a nontrivial mechanical response to applied stress. Our results show that cooperative particle motion occurs in unjammed systems significantly below the jamming transition for ?P?J.

Shen, Tianqi; O'Hern, Corey S.; Shattuck, M. D.

2012-01-01

131

Percolative phenomena in branched reverse micelles  

NASA Astrophysics Data System (ADS)

The role played by the solvation water molecules on the macroscopically observed sol-gel transition in lecithin/cyclohexane/water reverse micelles is investigated. The self-diffusion properties of both the surfactant and the water molecules entrapped in the micellar cores are investigated by quasi-elastic neutron scattering, while dielectric relaxation and conductivity measurements furnish information on the structural relaxation processes taking place in the system. The obtained results are compared with the experimental indications for AOT/cyclohexane/water systems. The data from lecithin-based systems can be interpreted only by assuming that, contrary to AOT systems, the water molecules are entrapped at the interfaces without coalescing into an inner water pool. Also, the charge transport mechanisms look very different in the two kinds of systems. In particular, in the case of lecithin, it is shown how the conductivity appears mainly due to inter-micellar bond percolation: it is suggested that the solvated water molecules can induce a change of the surface curvature, in such a way promoting the formation of branch points. The idea of the existence of a percolated network of branched cylindrical micelles agrees with the observed temperature dependence of the system conductivity. The study of the electrorheologic behavior of the system under electric field confirms the existence of a percolated transient network in the gel phase.

Aliotta, F.; Fazio, B.

2002-02-01

132

Topology of a percolating soil pore network  

NASA Astrophysics Data System (ADS)

A connectivity function defined by the 3D-Euler number, is a topological indicator and can be related to hydraulic properties (Vogel and Roth, 2001). This study aims to develop connectivity Euler indexes as indicators of the ability of soils for fluid percolation. The starting point was a 3D grey image acquired by X-ray computed tomography of a soil at bulk density of 1.2 mg cm-3. This image was used in the simulation of 40000 particles following a directed random walk algorithms with 7 binarization thresholds. These data consisted of 7 files containing the simulated end points of the 40000 random walks, obtained in Ruiz-Ramos et al. (2010). MATLAB software was used for computing the frequency matrix of the number of particles arriving at every end point of the random walks and their 3D representation. In a former work (Capa et al., 2011) a criteria for choosing the optimal threshold of grey value was identified: Final positions were divided in two subgroups, cg1 (positions with frequency of the number of particles received greater than the median) and cg2 (frequency lower or equal to median). Images with maximum difference between the Z coordinate of the center of gravity of both subgroups were selected as those with optimal threshold that reflects the major internal differences in soil structure that are relevant to percolation. According to this criterion, the optimal threshold for the soil with density 1.2 mg cm-3 was 24.Thresholds above and below the optimal (23 and 25) were also considered to confirm this selection; therefore the analysis were conducted for three files (1 image with 3 grey threshold values, which have different porosity). Additionally, three random matrix simulations with the same porosity than the selected binaries images were used to test the existence of pore connectivity as a consequence of a non-random soil structure. Therefore, 6 matrix were considered (three structured and three random) for this study. Random matrix presented a normal distribution of percolation speed contrary to the simulated percolation speed for structured soil images. For all of them, Minkowski functionals were calculated applying Ohser and Mucklich (2001) methodology. Interpretation of results in terms of soil percolation behavior of these soils will be derived.

Capa-Morocho, M.; Ruiz-Ramos, M.; Hapca, S. M.; Houston, A.; Tarquis, A. M.

2012-04-01

133

Percolation behavior in metallic-insulator composite systems and the filling factor near the percolation threshold  

NASA Astrophysics Data System (ADS)

We investigate the percolation behavior in various composite metal -- insulator systems including LiCoO2/ CrO2, MgB2/Al2O3, CrO2/Al2O3, CrO2/ CaCO3. The effect of particle size and shapes in these systems has been studied to better understand the geometrical phase transitions. The power law exponent around the percolation threshold has been found to be 2.0±0.04 in all the cases, which agrees well with the theoretical result. Interestingly, the filling factor of these composite systems also exhibits the power law dependence near the percolation threshold with the value found to be dependent on the shape of the insulating particle. The exponent ranges from 0.2 to 0.4 depending on size of particles of a given shape in the composite system.

Mukherjee, Rupam; Mishra, Debabrata; Huang, Zhifeng; Nadgorny, Boris

2012-10-01

134

Recycling: Additional Efforts Could Increase Municipal Recycling.  

National Technical Information Service (NTIS)

Although recycling can generate environmental and economic benefits, the national recycling rate has increased only slightly since 2000, according to the Environmental Protection Agency (EPA). While local governments have the primary role in operating rec...

2006-01-01

135

Explosive site percolation and finite-size hysteresis.  

PubMed

We report the critical point for site percolation for the "explosive" type for two-dimensional square lattices using Monte Carlo simulations and compare it to the classical well-known percolation. We use similar algorithms as have been recently reported for bond percolation and networks. We calculate the explosive site percolation threshold as p(c) = 0.695 and we find evidence that explosive site percolation surprisingly may belong to a different universality class than bond percolation on lattices, providing that the transitions (a) are continuous and (b) obey the conventional finite size scaling forms. Finally, we study and compare the direct and reverse processes, showing that while the reverse process is different from the direct process for finite size systems, the two cases become equivalent in the thermodynamic limit of large L. PMID:22304160

Bastas, Nikolaos; Kosmidis, Kosmas; Argyrakis, Panos

2011-12-15

136

Explosive site percolation and finite-size hysteresis  

NASA Astrophysics Data System (ADS)

We report the critical point for site percolation for the “explosive” type for two-dimensional square lattices using Monte Carlo simulations and compare it to the classical well-known percolation. We use similar algorithms as have been recently reported for bond percolation and networks. We calculate the explosive site percolation threshold as pc=0.695 and we find evidence that explosive site percolation surprisingly may belong to a different universality class than bond percolation on lattices, providing that the transitions (a) are continuous and (b) obey the conventional finite size scaling forms. Finally, we study and compare the direct and reverse processes, showing that while the reverse process is different from the direct process for finite size systems, the two cases become equivalent in the thermodynamic limit of large L.

Bastas, Nikolaos; Kosmidis, Kosmas; Argyrakis, Panos

2011-12-01

137

Continuum percolation of carbon nanotubes in polymeric and colloidal media  

PubMed Central

We apply continuum connectedness percolation theory to realistic carbon nanotube systems and predict how bending flexibility, length polydispersity, and attractive interactions between them influence the percolation threshold, demonstrating that it can be used as a predictive tool for designing nanotube-based composite materials. We argue that the host matrix in which the nanotubes are dispersed controls this threshold through the interactions it induces between them during processing and through the degree of connectedness that must be set by the tunneling distance of electrons, at least in the context of conductivity percolation. This provides routes to manipulate the percolation threshold and the level of conductivity in the final product. We find that the percolation threshold of carbon nanotubes is very sensitive to the degree of connectedness, to the presence of small quantities of longer rods, and to very weak attractive interactions between them. Bending flexibility or tortuosity, on the other hand, has only a fairly weak impact on the percolation threshold.

Kyrylyuk, Andriy V.; van der Schoot, Paul

2008-01-01

138

Research on percolation model and criticality of seismicity  

NASA Astrophysics Data System (ADS)

Making use of modern nonlinear physics theory and earthquake focus theory, combined with seismicity characteristics, the percolation model of earthquake activity is given in this paper. We take the seismogenic process of a large earthquake as a phase transition process of percolation and apply the renormalization method to phase transition of percolation. The critical property of the system, which is like percolation probability exponential and correlative length exponential, etc, can be calculated under the fixed point as which in the renormalization transformation infinite correlative length in percolation phase transition is taken. The percolation phase transition process of two large earthquakes, which are Haicheng and Tangshan event occurred in 1975 and 1976 respectively, has been discussed by means of seismicity data before and after two shocks.

Ke, Shan-Ming; Gu, Hao-Ding; Zhai, Wen-Jie

1999-07-01

139

Liberation of ammonia by cyanobacteria  

SciTech Connect

Photoheterotrophic nitrogen-fixing cyanobacteria release ammonia when treated with methionine sulfoximine (MSX) to inhibit nitrogen incorporation into protein. This released ammonia can be derived from recently fixed nitrogen (nitrogen atmosphere) or endogenous reserves (argon atmosphere). Anaerobic ammonia release requires light and is stimulated by the photosystem II herbicides DCMU and Atrazine, regardless of the source of ammonia. As much as one quarter of the total cellular nitrogen can be released as ammonia by cyanbacteria treated with MSX and DCMU under argon in light. Chromatography of cell extracts indicates that virtually all cellular proteins are degraded. DCMU and Atrazine, at very low concentration, inhibit sustained uptake of the ammonia analog /sup 14/C methylamine. These data indicate that the herbicides interrupt ammonia uptake and retention by the cells, and support a role for photosystem II in ammonia metabolism.

Newton, J.W.

1986-04-01

140

The Ammonia-Soda Process.  

ERIC Educational Resources Information Center

|This article is a condensed version of a commentary written to accompany a set of slides which describes the ammonia-soda process used by the ammonia-soda plant at Northwich of the United Kingdom. (HM)|

Tingle, M.

1979-01-01

141

Ammonia toxicity, tolerance, and excretion  

Microsoft Academic Search

Ammonia is an unusual toxicant in that it is produced by, as well as being poisonous to, animals. In aqueous solution ammonia has two species, NH3 and NH4+, total ammonia is the sum of [NH3] + [NH4+] and the pK of this ammonia\\/ammonium ion reaction is around 9.5. The NH3\\/NH4+ equilibrium both internally in animals and in ambient water depends

Y. K. Ip; S. F. Chew; D. J. Randall

2001-01-01

142

Connectedness percolation of elongated hard particles in an external field.  

PubMed

A theory is presented of how orienting fields and steric interactions conspire against the formation of a percolating network of, in some sense, connected elongated colloidal particles in fluid dispersions. We find that the network that forms above a critical loading breaks up again at higher loadings due to interaction-induced enhancement of the particle alignment. Upon approach of the percolation threshold, the cluster dimensions diverge with the same critical exponent parallel and perpendicular to the field direction, implying that connectedness percolation is not in the universality class of directed percolation. PMID:22463580

Otten, Ronald H J; van der Schoot, Paul

2012-02-22

143

Correction-to-scaling exponent for two-dimensional percolation  

SciTech Connect

We show that the correction-to-scaling exponents in two-dimensional percolation are bounded by {Omega}{<=}72/91, {omega}=D{Omega}{<=}3/2, and {Delta}{sub 1}={nu}{omega}{<=}2, based upon Cardy's result for the crossing probability on an annulus. The upper bounds are consistent with many previous measurements of site percolation on square and triangular lattices and new measurements for bond percolation, suggesting that they are exact. They also agree with exponents for hulls proposed recently by Aharony and Asikainen, based upon results of den Nijs. A corrections scaling form evidently applicable to site percolation is also found.

Ziff, Robert M. [Center for the Study of Complex Systems and Department of Chemical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2011-02-15

144

Connectedness Percolation of Elongated Hard Particles in an External Field  

NASA Astrophysics Data System (ADS)

A theory is presented of how orienting fields and steric interactions conspire against the formation of a percolating network of, in some sense, connected elongated colloidal particles in fluid dispersions. We find that the network that forms above a critical loading breaks up again at higher loadings due to interaction-induced enhancement of the particle alignment. Upon approach of the percolation threshold, the cluster dimensions diverge with the same critical exponent parallel and perpendicular to the field direction, implying that connectedness percolation is not in the universality class of directed percolation.

Otten, Ronald H. J.; van der Schoot, Paul

2012-02-01

145

Experimental Ammonia Battery.  

National Technical Information Service (NTIS)

An engineering investigation was performed to design and develop a 10 watt, 24/32 volt, low temperature primary reserve liquid ammonia battery with minimum requirements for a prototype of 20 milliamperes output, 36 hours life, 5 pounds over-all weight, 55...

B. Sykes

1966-01-01

146

Symposium explores percolation in porous media  

NASA Astrophysics Data System (ADS)

The 6th International Conference on Electrical Transport and Optical Properties of Inhomogeneous Media (ETOPIM 6) broke new ground by inviting members of the geosciences community Previous conferences in this series had been attended primarily by physicists and mathematicians. The organizers decided to broaden attendance because geological materials are inhomogeneous media of widespread interest, and many challenges faced by physicists, such as homogenization, scaling, and dynamically changing properties, are also common to soil and rocks. This effort toward inclusion resulted in a symposium on percolation theory in geological porous media, and many fruitful exchanges between the geoscientists and others in attendance.

Ewing, Robert

147

First passage percolation has sublinear distance variance  

Microsoft Academic Search

Let $0 < a < b < \\\\infty$, and for each edge e of $\\\\Z^d$ let\\u000a$\\\\omega_e=a$ or $\\\\omega_e=b$, each with probability $1\\/2$,\\u000aindependently. This induces a random metric $\\\\dist_\\\\omega$\\u000aon the vertices of $\\\\Z^d$, called first passage percolation.\\u000aWe prove that for $d>1$, the distance $\\\\dist_\\\\omega(0,v)$ from the origin\\u000ato a vertex $v$, $|v|>2$, has variance bounded by $C|v|\\/\\\\log|v|$,

Itai Benjamini; Gil Kalai; Oded Schramm

2003-01-01

148

First Passage Percolation Has Sublinear Distance Variance  

Microsoft Academic Search

\\u000a Let 0 , and for each edge e of ?\\u000a d\\u000a let ?\\u000a \\u000a e\\u000a = a or ?\\u000a \\u000a e\\u000a = b, each with probability 1\\/2, independently. This induces a random metric dist\\u000a ?\\u000a on the vertices of ?\\u000a d\\u000a , called first passage percolation. We prove that for d > 1, the distance dist\\u000a ?\\u000a (0, ?) from the origin

Itai Benjamini; Gil Kalai; Oded Schramm

2002-01-01

149

Recycling Improves USA  

Microsoft Academic Search

Changes are occurring in recycling that will improve the United States. There are significant improvements in the economy, environment and the health of Americans due to recycling efforts. Recycling will be shown as a superior option compared to landfill, incineration and virgin material processing. Many Case studies will be discussed that show how communities are making long-term decisions for recycling.

Luke Monroe

150

Visiting a Recycling Plant  

NSDL National Science Digital Library

Recycling is perhaps the most well-known and successful part of the popular three-pronged resource conservation strategy known as 'reduce, reuse, and recycle'. This site provides some general information about recycling, and a video segment from the television program 'ZOOM', in which a cast member visits a material recovery center to watch the recycling process unfold.

2005-01-01

151

Recycled pulsars  

NASA Astrophysics Data System (ADS)

In a survey of ~4,150 square degrees, we discovered 26 previously unknown pulsars, including 7 "recycled" millisecond or binary pulsars. The most significant discovery of this survey is PSR J1909-3744, a 2.95 ms pulsar in an extremely circular 1.5 d orbit with a low-mass white dwarf companion. Though this system is a fairly typical low-mass binary pulsar (LMBP) system, it has several exceptional qualities: an extremely narrow pulse profile and stable rotation have enabled the most precise long-term timing ever reported, and a nearly edge-on orbit gives rise to a strong Shapiro delay which has allowed the most precise measurement of the mass of a millisecond pulsar: m p = (1.438 +/- 0.024) [Special characters omitted.] . Our accurate parallax distance measurement, d p = ([Special characters omitted.] ) kpc, combined with the mass of the optically-detected companion, m c = (0.2038 +/- 0.022) [Special characters omitted.] , will provide an important calibration for white dwarf models relevant to other LMBP companions. We have detected optical counterparts for two intermediate mass binary pulsar (IMBP) systems; taken together with optical detections and non-detections of several similar systems, our results indicate that the characteristic age t = c P /2 P consistently overestimates the time since the end of mass accretion in these recycled systems. We have measured orbital decay in the double neutron star system PSR B2127+11C in the globular cluster M15. This has allowed an improved measurement of the mass of the pulsar, m p = (1.3584 +/- 0.0097) [Special characters omitted.] , and companion, m c = (1.3544 +/- 0.0097) [Special characters omitted.] , as well as a test of general relativity at the 3% level. We find that the proper motions of this pulsar as well as PSR B2127+11A and PSR B2127+11B are consistent with each other and with one published measurement of the cluster proper motion. We have discovered three binary millisecond pulsars in the globular cluster M62 using the 100-m Green Bank Telescope (GBT). These pulsars are the first objects discovered with the GBT. We briefly describe a wide-bandwidth coherent dedispersion backend used for some of the high precision pulsar timing observations presented here.

Jacoby, Bryan Anthony

2005-11-01

152

Percolation experiments in complex fractal media  

NASA Astrophysics Data System (ADS)

Series of flow percolation experiments under gravity were performed in different glass model and real karstic media samples. We present a multifractal characterization of the experiments in several parametric non-dimensional flow descriptors. Using the maximum local multifractal dimension as an additional flow indicator. Also experiments on Non laminar flow and transport conditions in fractured and karstified media were performed at Bari. The investigation on hypothesis of non linear flow and non fickian transport in fractured aquifers led to a distinction on the different role of channels and microchannels and of the presence of vortices and eddy trapping. The dominance of the elongated channels produced early arrival times, with the solute traveling along the high velocity channel network. On the other hand in a lumped structured karstic media, the percolation flow produced long tails with local Eddy mixing, entrapment in eddies, and slow flow out of the eddies. In The laboratory experiments performed in Madrid and in DAMTP Cambridge the role of the initial pressure produced fractal pathway structures even in iniatilly uniform ballotini substrates.

Redondo, Jose Manuel; Tarquis, Ana Maria; Cherubini, Claudia; Lopez Gzlez-Nieto, Pilar; Vila, Teresa

2013-04-01

153

Geometrical percolation threshold of overlapping ellipsoids  

NASA Astrophysics Data System (ADS)

A recurrent problem in materials science is the prediction of the percolation threshold of suspensions and composites containing complex-shaped constituents. We consider an idealized material built up from freely overlapping objects randomly placed in a matrix, and numerically compute the geometrical percolation threshold pc where the objects first form a continuous phase. Ellipsoids of revolution, ranging from the extreme oblate limit of platelike particles to the extreme prolate limit of needlelike particles, are used to study the influence of object shape on the value of pc. The reciprocal threshold 1/pc (pc equals the critical volume fraction occupied by the overlapping ellipsoids) is found to scale linearly with the ratio of the larger ellipsoid dimension to the smaller dimension in both the needle and plate limits. Ratios of the estimates of pc are taken with other important functionals of object shape (surface area, mean radius of curvature, radius of gyration, electrostatic capacity, excluded volume, and intrinsic conductivity) in an attempt to obtain a universal description of pc. Unfortunately, none of the possibilities considered proves to be invariant over the entire shape range, so that pc appears to be a rather unique functional of object shape. It is conjectured, based on the numerical evidence, that 1/pc is minimal for a sphere of all objects having a finite volume.

Garboczi, E. J.; Snyder, K. A.; Douglas, J. F.; Thorpe, M. F.

1995-07-01

154

Percolation Processes in Scintillation of Organic Crystals  

NASA Astrophysics Data System (ADS)

The use of organic crystals as scintillators that can discriminate between incident neutrons and gamma rays is gaining interest, particularly for applications in nonproliferation and diagnostics. Discrimination is achieved by measuring the delay of scintillation from neutrons, which arises from the predominant generation of triplet excited states that must diffuse and undergo a bimolecular Auger process to produce excited singlets before luminescence occurs. To understand this delayed scintillation process, we have studied triplet migration in two organic crystals: trans-stilbene (TS) and diphenylacetylene (DPAC). Both TS and DPAC show delayed neutron scintillation when pure, but the effect is quenched in DPAC if small amounts of TS impurity are present. We find that the first triplet excited state of TS is 0.3 eV lower than that of DPAC, creating a triplet trap in the impure DPAC crystals. Percolation theory is applied to predict a critical concentration of the mixed crystal to restore delayed scintillation, which compares favorably to experiments. We compute the triplet migration rate in different directions in the crystals and discuss the transport anisotropy in view of our percolation model.

Lordi, Vincenzo; Hamel, Sebastien; Carman, Leslie; Payne, Stephen; Zaitseva, Natalia

2010-03-01

155

Percolation and hysteresis in macroscopic capillarity  

NASA Astrophysics Data System (ADS)

The concepts of relative permeability and capillary pressure are crucial for the accepted traditional theory of two phase flow in porous media. Recently a theoretical approach was introduced that does not require these concepts as input [1][2][3]. Instead it was based on the concept of hydraulic percolation of fluid phases. The presentation will describe this novel approach. It allows to simulate processes with simultaneous occurence of drainage and imbibition. Furthermore, it predicts residual saturations and their spatiotemporal changes during two phase immiscible displacement [1][2][3][4][5]. [1] R. Hilfer. Capillary Pressure, Hysteresis and Residual Saturation in Porous Media, Physica A, vol. 359, pp. 119, 2006. [2] R. Hilfer. Macroscopic Capillarity and Hysteresis for Flow in Porous Media, Physical Review E, vol. 73, pp. 016307, 2006. [3] R. Hilfer. Macroscopic capillarity without a constitutive capillary pressure function, Physica A, vol. 371, pp. 209, 2006. [4] R. Hilfer. Modeling and Simulation of Macrocapillarity, in: P. Garrido et al. (eds.) Modeling and Simulation of Materials vol. CP1091, pp. 141, American Institute of Physcis, New York, 2009. [5] R. Hilfer and F. Doster. Percolation as a basic concept for macroscopic capillarity, Transport in Porous Media, DOI 10.1007/s11242-009-9395-0, in print, 2009.

Hilfer, Rudolf

2010-05-01

156

Percolation critical polynomial as a graph invariant  

NASA Astrophysics Data System (ADS)

Every lattice for which the bond percolation critical probability can be found exactly possesses a critical polynomial, with the root in [0,1] providing the threshold. Recent work has demonstrated that this polynomial may be generalized through a definition that can be applied on any periodic lattice. The polynomial depends on the lattice and on its decomposition into identical finite subgraphs, but once these are specified, the polynomial is essentially unique. On lattices for which the exact percolation threshold is unknown, the polynomials provide approximations for the critical probability with the estimates appearing to converge to the exact answer with increasing subgraph size. In this paper, I show how this generalized critical polynomial can be viewed as a graph invariant, similar to the Tutte polynomial. In particular, the critical polynomial is computed on a finite graph and may be found using the recursive deletion-contraction algorithm. This allows calculation on a computer, and I present such results for the kagome lattice using subgraphs of up to 36 bonds. For one of these, I find the prediction pc=0.52440572⋯, which differs from the numerical value, pc=0.52440503(5), by only 6.9×10-7.

Scullard, Christian R.

2012-10-01

157

Percolation on bipartite scale-free networks  

NASA Astrophysics Data System (ADS)

Recent studies introduced biased (degree-dependent) edge percolation as a model for failures in real-life systems. In this work, such process is applied to networks consisting of two types of nodes with edges running only between nodes of unlike type. Such bipartite graphs appear in many social networks, for instance in affiliation networks and in sexual-contact networks in which both types of nodes show the scale-free characteristic for the degree distribution. During the depreciation process, an edge between nodes with degrees k and q is retained with a probability proportional to (k, where ? is positive so that links between hubs are more prone to failure. The removal process is studied analytically by introducing a generating functions theory. We deduce exact self-consistent equations describing the system at a macroscopic level and discuss the percolation transition. Critical exponents are obtained by exploiting the Fortuin-Kasteleyn construction which provides a link between our model and a limit of the Potts model.

Hooyberghs, H.; van Schaeybroeck, B.; Indekeu, J. O.

2010-08-01

158

Quantized Conductance and Switching in Percolating Nanoparticle Films  

NASA Astrophysics Data System (ADS)

We demonstrate switching behavior and quantized conductance at room temperature in percolating films of nanoparticles. Our experiments and complementary simulations show that switching and quantization result from the formation of atomic-scale wires in the gaps between particles. These effects occur only when tunnel gaps are present in the film, close to the percolation threshold.

Sattar, Abdul; Fostner, Shawn; Brown, Simon A.

2013-09-01

159

Percolation, statistical topography, and transport in random media  

Microsoft Academic Search

A review of classical percolation theory is presented, with an emphasis on novel applications to statistical topography, turbulent diffusion, and heterogeneous media. Statistical topography involves the geometrical properties of the isosets (contour lines or surfaces) of a random potential Ï({bold x}). For rapidly decaying correlations of Ï, the isopotentials fall into the same universality class as the perimeters of percolation

M. Isichenko

1992-01-01

160

Cytoskeleton as a Fractal Percolation Cluster: Some Biological Remarks  

Microsoft Academic Search

The possibility being discussed is that the cytoskeleton, the intricate polymeric meshwork which spans the cytoplasm, may be regarded as a percolation system and that at the edge of the percolation transition mechanotransduction may be enhanced. Since calcium ion can be considered the main factor controlling the state of the cytoskeletal network, it is hypothesized that the increase of free

Silvano Traverso

161

Percolation Segregation Model for Similar and Differing Constituents  

Microsoft Academic Search

Segregation is a ubiquitous and undesirable phenomenon that occurs nearly anywhere and anytime as particulate materials are stored, handled, processed, or conveyed. New percolation segregation mechanistic hypotheses were formulated to interpret the percolation and sieving mechanisms. The theoretical hypotheses consist of two attributes: hypothesis I, larger particle sizes have higher potential of segregation rate; hypothesis II, falling path become less

P. Tang; V. M. Puri

2010-01-01

162

Tunneling and percolation in metal-insulator composite materials  

Microsoft Academic Search

In many composites, the electrical transport takes place only by tunneling between isolated particles. For a long time, it was quite a puzzle how, in spite of the incompatibility of tunneling and percolation networks, these composites conform well to percolation theory. We found, by conductance atomic force microscopy measurements on granular metals, that it is the apparent cut off of

D. Toker; D. Azulay; N. Shimoni; I. Balberg; O. Millo

2003-01-01

163

Social percolation and the influence of mass media  

Microsoft Academic Search

In the marketing model of Solomon and Weisbuch, people buy a product only if their neighbours tell them of its quality, and if this quality is higher than their own quality expectations. Now we introduce additional information from the mass media, which is analogous to the ghost field in percolation theory. The mass media shift the percolative phase transition observed

Ana Proykova; Dietrich Stauffer

2002-01-01

164

Percolation Thresholds in the Three-Dimensional Sticks System  

Microsoft Academic Search

We report the dependence of the percolation threshold of the three-dimensional sticks systems on aspect ratio and on macroscopic anisotropy. This Monte Carlo study is the first determination of percolation thresholds for randomly oriented objects in three-space. The results show that the above dependence is determined by the excluded volume of the sticks. However, the total excluded volume of randomly

I. Balberg; N. Binenbaum; N. Wagner

1984-01-01

165

Anhydrous ammonia injuries.  

PubMed

Anhydrous ammonia, a pungent, colorless gas or liquid, is commonly used around the world as a refrigerant and fertilizer in agriculture. It is an alkali causing liquefaction or freeze-dry lesions with skin contact. Initial emergency response involves evacuation, decontamination, first aid and alerting proper authorities. Decontamination must be complete and rescuers must avoid being overcome by fumes. Emergency department care is directed at respiratory, ocular, skin and gastrointestinal treatment. Respiratory and ocular lesions tend to be the most severe and can be used as a triage guide. The need for a multidisciplinary approach to hospital care is stressed. In severe exposures, adult respiratory distress syndrome is a common finding. In children who have ingested aqua ammonia, early endoscopy, aggressive antibiotic therapy and serial dilatations of strictures are recommended. Long-term complications occur predominately to the eyes and respiratory tract. PMID:19785216

Lessenger, James E

2004-01-01

166

Ammonia abundances in comets  

NASA Astrophysics Data System (ADS)

The emission band strengths of the NH2 bands of Comets Halley, Hartley-Good, Thiele, and Borrelly were measured to determine the NH2 column densities for the comets. Production rates obtained using the Haser and vectorial models are in agreement within the observational errors, suggesting that a simple two-step decay model may be used to approximate the NH2 distribution in a comet's coma. Ammonia-to-water abundance ratios from 0.01 to 0.4 percent were found for the four comets. The ratio in Comet Halley is found to be Q(NH3)/Q(H2O) = 0.002 + or - 0.001. No significant difference in the ammonia abundance was found before or after perihelion in Comet Halley.

Wyckoff, S.; Tegler, S.; Engel, L.

167

Recovery of ammonia nitrogen in livestock and industrial wastes using gas permeable membranes  

Technology Transfer Automated Retrieval System (TEKTRAN)

New waste management methods are needed that can protect the environment and allow manure management to switch back to a recycling view of manure handling. We investigated the use of gas-permeable membranes as components of new processes to capture and recover the ammonia in the liquid manures or in...

168

Equilibrium ammonium concentration in slurry mix evaporator condensate tank (SMECT) with ammonia scrubbers.  

National Technical Information Service (NTIS)

During design reviews of the Recycle Colection Tank (RCT) at the Savannah River Site it was determined that in all cases the RCT scrub solution could not be routed to the RCT. During transfers to the tank farm (estimated ten hour cycle), the ammonia evolv...

D. P. Lambert

1992-01-01

169

Recycled Art: Create Puppets Using Recycled Objects.  

ERIC Educational Resources Information Center

Presents an activity from "Healthy Foods from Healthy Soils" for making puppets using recycled food packaging materials. Includes background information, materials, instructions, literature links, resources, and benchmarks. (NB)

Clearing, 2003

2003-01-01

170

Recycle Used Oil on America Recycles Day.  

ERIC Educational Resources Information Center

Explains that motor oils can be reused and recycled. Educates students about environmental hazards and oil management and includes classroom activities. Addresses the National Science Education Standards. (YDS)

White, Boyd W.

2000-01-01

171

Recycled Art: Create Puppets Using Recycled Objects.  

ERIC Educational Resources Information Center

|Presents an activity from "Healthy Foods from Healthy Soils" for making puppets using recycled food packaging materials. Includes background information, materials, instructions, literature links, resources, and benchmarks. (NB)|

Clearing, 2003

2003-01-01

172

Challenges in metal recycling.  

PubMed

Metals are infinitely recyclable in principle, but in practice, recycling is often inefficient or essentially nonexistent because of limits imposed by social behavior, product design, recycling technologies, and the thermodynamics of separation. We review these topics, distinguishing among common, specialty, and precious metals. The most beneficial actions that could improve recycling rates are increased collection rates of discarded products, improved design for recycling, and the enhanced deployment of modern recycling methodology. As a global society, we are currently far away from a closed-loop material system. Much improvement is possible, but limitations of many kinds--not all of them technological--will preclude complete closure of the materials cycle. PMID:22879508

Reck, Barbara K; Graedel, T E

2012-08-10

173

Chaos and irregularity in karst percolation  

NASA Astrophysics Data System (ADS)

This paper focuses on analyzing chaos in cave percolation water drip rates, which has implications for flow routing in fractured media and on the use of speleothems for paleoclimate reconstructions. It has been shown that the physics of dripping faucets involve a set of non-linear equations leading to chaotic drip rate, meaning that, for a given drip rate, the interval between individual drops can vary greatly. It can be expected that drip waters supplying stalagmites show similar properties, and consequently the dependency between water flux and stalagmite growth rate or geochemistry could be more complicated than usually assumed. We used high-frequency monitoring of two contrasting drips in a cave in Australia, and identified chaos in cave drip rate. Our findings also indicate that the occurrence of chaos can give insights into flow routing in fractured media.

Mariethoz, Gregoire; Baker, Andy; Sivakumar, Bellie; Hartland, Adam; Graham, Peter

2012-12-01

174

Temporal percolation of a susceptible adaptive network  

NASA Astrophysics Data System (ADS)

In the past decades, many authors have used the susceptible–infected–recovered model to study the impact of the disease spreading on the evolution of the infected individuals. However, few authors focused on the temporal unfolding of the susceptible individuals. In this paper, we study the dynamic of the susceptible–infected–recovered model in an adaptive network that mimics the transitory deactivation of permanent social contacts, such as friendship and work-ship ties. Using an edge-based compartmental model and percolation theory, we obtain the evolution equations for the fraction susceptible individuals in the susceptible biggest component. In particular, we focus on how the individual's behavior impacts on the dilution of the susceptible network. We show that, as a consequence, the spreading of the disease slows down, protecting the biggest susceptible cluster by increasing the critical time at which the giant susceptible component is destroyed. Our theoretical results are fully supported by extensive simulations.

Valdez, L. D.; Macri, P. A.; Braunstein, L. A.

2013-09-01

175

Ammonia emissions from seabird colonies  

NASA Astrophysics Data System (ADS)

Ammonia emissions were measured from two entire seabird colonies with contrasting species assemblages, to ascertain the ammonia volatilisation potentials among seabird species in relation to their nesting behaviour. Emissions were calculated from downwind plume measurements of ammonia concentration using both inverse dispersion and tracer ratio methods. Measured colony emissions ranged 1-90 kg NH3 hour-1, and equated to 16 and 36% volatilization of excreted nitrogen for colonies dominated by ground/burrow nesting and bare rock nesting birds, respectively. The results were applied in a bioenergetics model with a global seabird database. Seabird colonies are found to represent the largest point sources of ammonia globally (up to ~6 Gg NH3 colony-1 year-1). Moreover the largest emissions occur mainly in remote environments with otherwise low NH3 emissions. These ammonia ``hot spots'' explain significant perturbations of the nitrogen cycle in these regions and add ~20% to oceanic ammonia emissions south of latitude 45°S.

Blackall, Trevor D.; Wilson, Linda J.; Theobald, Mark R.; Milford, Celia; Nemitz, Eiko; Bull, Jennifer; Bacon, Philip J.; Hamer, Keith C.; Wanless, Sarah; Sutton, Mark A.

2007-05-01

176

Equilibria of the marine multiphase ammonia system  

Microsoft Academic Search

A lack of empirical data has made it difficult to ascertain whether ammonia is in equilibrium between the oceanic, atmospheric gas and atmospheric particle phases in the remote marine environment. Reported here are simultaneous measurements of the saturation concentration of ammonia relative to ammonia concentrations in ocean surface waters; total seawater ammonia; atmospheric gas phase ammonia; and atmospheric particulate-phase ammonium,

P. K. Quinn; W. E. Asher; R. J. Charlson

1992-01-01

177

Hydraulic Properties of Unsaturated Porous Media From Percolation Theory  

NASA Astrophysics Data System (ADS)

Percolation theory can be used to calculate transport properties in disordered media, such as solute diffusion and the hydraulic conductivity. Experiments have shown that diffusion of solutes in porous media vanishes linearly as threshold moisture content is approached. An empirical relationship gives the threshold moisture content as approximately the square root of the surface area to volume ratio of the medium. The first relationship demonstrates the relevance of percolation theory in its continuum application (non-zero transport in a given phase requires phase continuity), while the second can be shown to be based on the validity of a fractal description of the medium. Percolation-type scaling behavior of the unsaturated hydraulic conductivity is not observed; in fact critical path analysis from percolation theory using the threshold moisture content for the critical moisture content for percolation gives the hydraulic conductivity in agreement with experiment. However, cross-over from the validity of critical path analysis to the percolation scaling regime is accompanied by a rapid change in the slope of the conductivity, leading to rapid increases in experimental equilibration times, failure to observe equilibrium pressure-saturation relations, and excess water in the medium for a given tension. These effects confound interpretation of experiments, but unification within a percolation perspective allows quantitative predictions of both the equilibrium and non-equilibrium behavior.

Hunt, A. G.

2004-05-01

178

Recycling Research. Tracking Trash.  

ERIC Educational Resources Information Center

|An activity in which students research the effectiveness of recycling is presented. Students compare the types and amount of litter both before and after recycling is implemented. Directions for the activity and a sample data sheet are included. (KR)|

DeLago, Louise Furia

1991-01-01

179

Recycling Rules: Understanding Recycling and a MRF  

NSDL National Science Digital Library

In this activity, learners simulate the separation techniques that materials recovery facilities (MRFs) use and then design their own series of recycling techniques. Learners identify four ways recyclable materials can be separated and sorted at a MRF: conveyor belts, blowers, flotation, and magnetism.

Keep America Beautiful, Inc.

2010-01-01

180

Double Percolation in the Intermediate Phase of Network Glasses  

NASA Astrophysics Data System (ADS)

Intermediate Phases (IP) in network glasses, discovered by Boolchand and coworkers, exhibit two striking properties: a nearly reversible glass transition, and nearly zero internal network stress. Double percolation, a well-established phenomenon in polymer blend-carbon black composites and numerical simulations, explains quantitatively the ranges of the intermediate phase observed in ternary chalcogenide alloys. The mechanism underlying IP double percolation in network glasses is spinodal enthalpy-entropy balance. Triple percolation also explains many aspects of the phase diagrams of cuprate high-temperature superconductors.

Phillips, J. C.; Lucovsky, Gerry

2008-03-01

181

Recycling of automotive aluminum  

Microsoft Academic Search

With the global warming of concern, the secondary aluminum stream is becoming an even more important component of aluminum production and is attractive because of its economic and environmental benefits. In this work, recycling of automotive aluminum is reviewed to highlight environmental benefits of aluminum recycling, use of aluminum alloys in automotive applications, automotive recycling process, and new technologies in

Jirang CUI; Hans J. ROVEN

2010-01-01

182

Recycling and the automobile  

SciTech Connect

This article examines the current status of automobile recycling and contains a summary of a survey which points out the major drivers and their impacts on automotive recycling. The topics of the article include computerized dismantling, polyurethane, sheet molding compound, polyester, thermoplastic polyester, recycling salvaged parts, vinyl and automotive shredder residue.

Holt, D.J.

1993-10-01

183

Rethink, Rework, Recycle.  

ERIC Educational Resources Information Center

|Information about the recycling and reuse of plastics, aluminum, steel, glass, and newspapers is presented. The phases of recycling are described. An activity that allows students to separate recyclable materials is included. The objectives, a list of needed materials, and procedure are provided. (KR)|

Wrhen, Linda; DiSpezio, Michael A.

1991-01-01

184

Rethink, Rework, Recycle.  

ERIC Educational Resources Information Center

Information about the recycling and reuse of plastics, aluminum, steel, glass, and newspapers is presented. The phases of recycling are described. An activity that allows students to separate recyclable materials is included. The objectives, a list of needed materials, and procedure are provided. (KR)

Wrhen, Linda; DiSpezio, Michael A.

1991-01-01

185

Recycling calls for revaluation  

Microsoft Academic Search

Purpose – The purpose of this paper is to develop the value concept for recycling contexts. Design\\/methodology\\/approach – The paper is a conceptual discussion supported by empirical illustrations of value development for recycled paper and electric and electronics products. Findings – Demonstrates the fundamental effects of applying the economic value concept for recycling. Suggests that value can be seen as

Maria Huge Brodin; Helén Anderson

2008-01-01

186

Highly conductive die attach adhesive from percolation control and its applications in light-emitting device thermal management  

NASA Astrophysics Data System (ADS)

Herein, we reported on the study of percolation dynamics in thermoset-based die attach (DA) materials and its effect on percolation conductivity. Two types of percolation mechanism in thermoset based DA were discovered, i.e., the curing reaction-induced percolation and the physical aging-induced percolation. The former features in a fast percolation network growth rate, which is one order of magnitude higher than the latter. It is demonstrated that the percolation kinetics largely affects the apparent percolation conductivity under the traditional packaging conditions; and reaction-induced percolation allows ultrahigh efficiency in reaching the volume fraction-limiting percolation conductance, resulting in enhanced thermal performance of DA.

Zhang, Xinfeng; Zhang, Kai; Zhang, Min; Yang, Chen; Sun, Hongye; Gao, Zhaoli; Yuen, Matthew M. F.; Yang, Shihe

2013-01-01

187

Percolation transition of siloxane domain in partially phenylated organic\\/inorganic hybrid glass  

Microsoft Academic Search

Organic–inorganic hybrid glass undergoes a percolation transition of the organic or inorganic moiety at a certain volume fraction of either phase. At the percolation threshold, various properties of the hybrid glass exhibit an abrupt change. We attempted to evaluate the threshold volume fraction of the percolation transition in partially phenylated glass from the measurable or observable behavior at the percolation

Yoshihiro Kamimura; Ken-ichi Kurumada

2007-01-01

188

46 CFR 154.1760 - Liquid ammonia.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 2012-10-01 false Liquid ammonia. 154.1760 Section 154...Operating Requirements § 154.1760 Liquid ammonia. The master shall ensure that no person sprays liquid ammonia into a cargo tank containing...

2012-10-01

189

46 CFR 154.1760 - Liquid ammonia.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 2011-10-01 false Liquid ammonia. 154.1760 Section 154...Operating Requirements § 154.1760 Liquid ammonia. The master shall ensure that no person sprays liquid ammonia into a cargo tank containing...

2011-10-01

190

Ammonia plant designers talk of big energy savings  

SciTech Connect

The ammonia plant that Pullman Kellogg has designed for Sherritt-Gordon Mines Ltd. in Alberta will require < 27 million Btu/ton of ammonia, and save $8.10/ton in energy costs because of improvements involving increased pressure in the primary reformer; more efficient use of the heat from the secondary reformer; carbon dioxide recovery by Allied Chemical Corp.'s Selexol process; the reduction of power requirements in the synthesis recycle loop; and the use of a horizontal reactor. C. F. Braun and Co. claims that its Purifier process will require < 25 million Btu/ton, due to the use of excess air in the secondary reformer. C-E Lummus offers a 1500 ton/day plant which, incorporating cryogenic recovery of hydrogen from purge gas and operation at a lower steam-to-carbon ratio, would require only 26 million Btu/ton; Haldor Topsoe Inc. offers a design rated at 26.3 million Btu/ton. According to L. C. Axelrod of Pullman Kellogg, ammonia plant construction will shift to gas-rich areas outside the U.S. and Europe. The 3% of the U.S. natural gas used by the fertilizer industry accounts for > 95% of ammonia feedstock.

Axelrod, L.C.

1980-08-27

191

Biological nitrogen removal of ammonia-rich centrate in batch systems.  

PubMed

This study addressed the removal of ammonia from recycled centrate via biological nitrification and denitrification in batch reactors. Nitrification was successful at ammonia feed concentrations up to 400 mg/L and carbon-to-nitrogen (C/N) ratios greater than 1. The use of pre-exposed biomass to ammonia-rich centrate reduced considerably the overall time required for nitrification, which was also reflected on the corresponding specific rates. The denitrification of naturally-generated nitrates proceeded smoothly, with methanol modestly outperforming acetate as external carbon source. Furthermore, simultaneous nitrification and denitrification (SND) was induced in the presence of readily biodegradable organic carbon (i.e., methanol or acetate) under aerobic conditions. Overall, total nitrogen removal from ammonia-rich centrate by biological methods was viable under the conditions investigated. PMID:23245308

Boyle-Gotla, Aparajita; Elefsiniotis, Panagiotis

2013-01-01

192

Double percolation transition in superconductor-ferromagnet nanocomposites.  

PubMed

A double percolation transition is identified in a binary network composed of nanoparticles of MgB2 superconductor and CrO2 half-metallic ferromagnet. Anomalously high-resistance or insulating state, as compared to the conducting or superconducting states in single-component systems of either constituent, is observed between two distinct percolation thresholds. This double percolation effect, which is especially pronounced at liquid helium temperatures, is controlled by composite volume fraction and originates from the suppressed interface conduction and tunneling as well as a large geometric disparity between nanoparticles of different species. We investigate the scaling behavior near both percolation thresholds and determine the distinct critical exponents associated with two different types of transitions. PMID:20366657

Liu, Xiangdong; Panguluri, Raghava P; Huang, Zhi-Feng; Nadgorny, Boris

2010-01-21

193

Double Percolation Transition in Superconductor/Ferromagnet Nanocomposites  

NASA Astrophysics Data System (ADS)

A double percolation transition is identified in a binary network composed of nanoparticles of MgB2 superconductor and CrO2 half-metallic ferromagnet. Anomalously high-resistance or insulating state, as compared to the conducting or superconducting states in single-component systems of either constituent, is observed between two distinct percolation thresholds. We investigate the scaling behavior near both percolation thresholds, and determine the distinct critical exponents associated with two different types of transitions. This double percolation effect, which is especially pronounced at liquid helium temperatures, is controlled by composite volume fraction and originates from the suppressed interface conduction and tunneling as well as a large geometric disparity between nanoparticles of different species. This sensitivity of the threshold to the geometry is confirmed by replacing CrO2 with LSMO particles of different size and shape, which results in significantly different threshold for MgB2.

Liu, Xiangdong; Panguluri, Raghava P.; Shoemaker, Daniel P.; Huang, Zhi-Feng; Nadgorny, Boris

2010-03-01

194

Double Percolation Transition in Superconductor-Ferromagnet Nanocomposites  

NASA Astrophysics Data System (ADS)

A double percolation transition is identified in a binary network composed of nanoparticles of MgB2 superconductor and CrO2 half-metallic ferromagnet. Anomalously high-resistance or insulating state, as compared to the conducting or superconducting states in single-component systems of either constituent, is observed between two distinct percolation thresholds. This double percolation effect, which is especially pronounced at liquid helium temperatures, is controlled by composite volume fraction and originates from the suppressed interface conduction and tunneling as well as a large geometric disparity between nanoparticles of different species. We investigate the scaling behavior near both percolation thresholds and determine the distinct critical exponents associated with two different types of transitions.

Liu, Xiangdong; Panguluri, Raghava P.; Huang, Zhi-Feng; Nadgorny, Boris

2010-01-01

195

Directed rigidity and bootstrap percolation in 1+1 dimensions.  

PubMed

We study directed rigidity percolation (equivalent to directed bootstrap percolation) on three different lattices: square, triangular, and augmented triangular. The first two of these display a first-order transition at p=1, while the augmented triangular lattice shows a continuous transition at a nontrivial p(c). On the augmented triangular lattice we find, by extensive numerical simulation, that the the directed rigidity percolation transition belongs to the same universality class as the directed percolation. The same conclusion is reached by studying its surface critical behavior, i.e., the spreading of rigidity from finite clusters close to a nonrigid wall. Near the discontinuous transition at p=1 on the triangular lattice, we are able to calculate the finite-size behavior of the density of rigid sites analytically. Our results are confirmed by numerical simulation. PMID:11970465

de Menezes, M A; Moukarzel, C F

1999-11-01

196

Increased Water Conservation and Percolation through Improved Tillage Practices.  

National Technical Information Service (NTIS)

A technique was developed to determine soil water storage and predict deep percolation under different tillage treatments and moisture levels. The dryland farmer can use the findings to vary his tillage practices to conserve the maximum amount of moisture...

H. D. Wittmuss

1980-01-01

197

The percolation staircase model and its manifestation in composite materials  

NASA Astrophysics Data System (ADS)

We studied the tunneling percolation conductivity dependence on the site or bond occupation probability in the square lattice. The model predicts that in both, lattice and continuum systems in which there is a hierarchy of the local conductances, the dependence of the global conductivity on the site or volume occupation probability will yield a conductivity staircase. In particular we evaluate the implications of the staircase on the critical behavior of the conductivity. We then show experimental evidence for the predicted percolation-tunneling staircase in a Ag-Al2O3 granular metal system and in a carbon black-polymer composite. Following that, we propose that for carbon nanotube (CNT) polymer composites the data in the literature give ample support to a percolation-dispersion staircase behavior. The implication of the present findings on the percolation-hopping problem in composite materials is also discussed.

Balberg, I.; Azulay, D.; Goldstein, Y.; Jedrzejewski, J.; Ravid, G.; Savir, E.

2013-10-01

198

Percolation on Interdependent Networks with a Fraction of Antagonistic Interactions  

NASA Astrophysics Data System (ADS)

Recently, the percolation transition has been characterized on interacting networks both in presence of interdependent interactions and in presence of antagonistic interactions. Here we characterize the phase diagram of the percolation transition in two Poisson interdependent networks with a percentage q of antagonistic nodes. We show that this system can present a bistability of the steady state solutions, and both discontinuous and continuous phase transitions. In particular, we observe a bistability of the solutions in some regions of the phase space also for a small fraction of antagonistic interactions 0< q<0.4. Moreover, we show that a fraction q> q c =2/3 of antagonistic interactions is necessary to strongly reduce the region in phase-space in which both networks are percolating. This last result suggests that interdependent networks are robust to the presence of antagonistic interactions. Our approach can be extended to multiple networks, and to complex boolean rules for regulating the percolation phase transition.

Zhao, Kun; Bianconi, Ginestra

2013-09-01

199

Percolation thresholds of two-dimensional continuum systems of rectangles.  

PubMed

The present paper introduces an efficient Monte Carlo algorithm for continuum percolation composed of randomly oriented rectangles. By conducting extensive simulations, we report high-precision percolation thresholds for a variety of homogeneous systems with different rectangle aspect ratios. This paper verifies and extends the excluded area theory. It is confirmed that percolation thresholds are dominated by the average excluded areas for both homogeneous and heterogeneous rectangle systems (except for some special heterogeneous systems where the rectangle lengths differ too much from one another). In terms of the excluded areas, generalized formulas are proposed to effectively predict precise percolation thresholds for all these rectangle systems. This paper is, therefore, helpful for both practical applications and theoretical studies concerning relevant systems. PMID:23944408

Li, Jiantong; Ostling, Mikael

2013-07-03

200

Percolation thresholds of two-dimensional continuum systems of rectangles  

NASA Astrophysics Data System (ADS)

The present paper introduces an efficient Monte Carlo algorithm for continuum percolation composed of randomly oriented rectangles. By conducting extensive simulations, we report high-precision percolation thresholds for a variety of homogeneous systems with different rectangle aspect ratios. This paper verifies and extends the excluded area theory. It is confirmed that percolation thresholds are dominated by the average excluded areas for both homogeneous and heterogeneous rectangle systems (except for some special heterogeneous systems where the rectangle lengths differ too much from one another). In terms of the excluded areas, generalized formulas are proposed to effectively predict precise percolation thresholds for all these rectangle systems. This paper is, therefore, helpful for both practical applications and theoretical studies concerning relevant systems.

Li, Jiantong; Östling, Mikael

2013-07-01

201

Social percolation and the influence of mass media  

NASA Astrophysics Data System (ADS)

In the marketing model of Solomon and Weisbuch, people buy a product only if their neighbours tell them of its quality, and if this quality is higher than their own quality expectations. Now we introduce additional information from the mass media, which is analogous to the ghost field in percolation theory. The mass media shift the percolative phase transition observed in the model, and decrease the time after which the stationary state is reached.

Proykova, Ana; Stauffer, Dietrich

2002-09-01

202

Percolation thresholds for rod-like particles: polydispersity effects  

NASA Astrophysics Data System (ADS)

A model based upon excluded volume considerations is presented for the connectedness percolation thresholds in polydisperse systems of cylindrical rod-like nanoparticles. The dependence of the percolation threshold upon polydispersity index and number-averaged aspect ratio is examined for two different distribution functions for the rod radii and lengths. The importance of accounting for polydispersity is explored in the context of measurements of the elastic moduli and electrical conductance in fibre-filled nanocomposites.

Chatterjee, Avik P.

2008-06-01

203

Critical indexes of conductivity in two-dimensional percolation problems  

Microsoft Academic Search

The results of model experiments for critical behaviour of conductivity in two-dimensional percolation problems are presented. It is found that for the system consisting of conductive and non-conductive elements conductivity vanishes as sigma (x) infinity (xc-x)t; where t is equal to 1.15+or-0.2 for both bond and site percolation problems. For the two-component system consisting of metallic and dielectric elements it

M. E. Levinshtein

1977-01-01

204

Scaling properties of diffusion-limited aggregation, the percolation hull, and invasion percolation  

NASA Astrophysics Data System (ADS)

We study various properties of the surface of diffusion-limited aggregation (DLA) and invasion percolation clusters using a ``glove algorithm.'' Specifically, we define the l-perimeter to be the set of nonfractal sites with a chemical distance l from a fractal with M sites. We argue that P(M,l), the number of sites of the l-perimeter, should obey a scaling law of the form P(M,l)/l~f(l/M1/df), where f(u)~u-df for u-->0 and f(u)-->const for u-->?. Simulations of two-dimensional off-lattice DLA clusters, invasion percolation clusters, and percolation hulls-as well as an exact treatment of the Sierpi?ski gasket-support this scaling form. We find that an analogous scaling form holds for G(M,l), the number of sites in the ``l-glove,'' which is composed of the sites of the l-perimeter accessible to particles of radius l from the exterior. Moreover, we define a hierarchy of ``lagoons'' for the case of loopless fractals as regions that are inaccessible to particles of different sizes. We apply this definition to DLA and find that the lagoon-size distribution in DLA is consistent with a self-similar structure of the aggregate. However, we find even for large lagoons a surprisingly small most probable width of the necks that separate the lagoons from the exterior of the cluster. Small neck widths of large lagoons are consistent with a recently proposed void-neck model for the geometric structure of DLA.

Schwarzer, Stefan; Havlin, Shlomo; Stanley, H. Eugene

1994-02-01

205

Temperature controlled ammonia synthesis process  

SciTech Connect

A process is described for the synthesis of ammonia carried out at a pressure greater than 100 atmospheres which process comprises passing a mixture of gases in continuous flow through apparatus so as to carry out the following steps: (a) passing at least a portion of an ammonia feed syngas through a heat exchanger to increase its temperature; (b) passing the feed syngas from (a) through a first ammonia synthesis catalyst bed to obtain an effluent; (c) passing at least a portion of the effluent from (b) through the heat exchanger of (a) to decrease the temperature of the effluent; (d) passing the effluent from (c) through a series of at least two additional ammonia synthesis catalysts beds and then subsequent to each bed through a high temperature heat sink to decrease the temperature of the effluent and to obtain a final product effluent; and (c) recovering ammonia from the final product effluent of the series in (d).

Grotz, B.J. Jr.

1986-11-25

206

Deriving an underlying mechanism for discontinuous percolation  

NASA Astrophysics Data System (ADS)

Understanding what types of phenomena lead to discontinuous phase transitions in the connectivity of random networks is an outstanding challenge. Here we show that a simple stochastic model of graph evolution leads to a discontinuous percolation transition and we derive the underlying mechanism responsible: growth by overtaking. Starting from a collection of n isolated nodes, potential edges chosen uniformly at random from the complete graph are examined one at a time while a cap, k, on the maximum allowed component size is enforced. Edges whose addition would exceed k can be simply rejected provided the accepted fraction of edges never becomes smaller than a function which decreases with k as g(k) = 1/2 + (2k)-?. We show that if ? < 1 it is always possible to reject a sampled edge and the growth in the largest component is dominated by an overtaking mechanism leading to a discontinuous transition. If ? > 1, once k ? n1/?, there are situations when a sampled edge must be accepted leading to direct growth dominated by stochastic fluctuations and a “weakly” discontinuous transition. We also show that the distribution of component sizes and the evolution of component sizes are distinct from those previously observed and show no finite-size effects for the range of ? studied.

Chen, W.; Zheng, Z.; D'Souza, R. M.

2012-12-01

207

Modeling of heat generation in ammonia-treated solid rocket propellant  

SciTech Connect

With the end of the Cold War, safe, environmentally sound separation, recycling, and disposal of ingredients in solid rocket propellants and munitions has become a national priority. One approach to demilitarize solid rocket propellants is treatment with ammonia. Ammonia extracts the oxidizers ammonium perchlorate and HMX, yielding a solid reside that is more suitable for incineration and less sensitive to impact and other modes of accidental initiation. Ammonia treatment of nitroglycerin-containing propellants is complicated by an exothermic reaction between ammonia and nitroglycerin. If not removed, the heat generated by this reaction can cause propellant ignition. To help design safe treatment processes, a model for the ammonia-propellant reaction was developed, which integrates transient energy and species conservation equations to simulate ammonia diffusion, heat generation, and heat flow in a propellant and in the solid residue resulting from ammonia treatment. It was calibrated using residue thickness and thermocouple data for one propellant. The calibrated model was used to predict conditions leading to ignition of thin propellant strips. The results agree well with experimental observations.

Raun, R.L.; Isom, K.B. [Hercules, Inc., Magna, UT (United States)

1995-06-01

208

Leaching standards for mineral recycling materials--a harmonized regulatory concept for the upcoming German Recycling Decree.  

PubMed

In this contribution we give a first general overview of results of recent studies in Germany which focused on contaminant leaching from various materials and reactive solute transport in the unsaturated soil zone to identify the key factors for groundwater risk assessment. Based on these results we developed new and improved existing methods for groundwater risk assessment which are used to derive a new regulatory concept for the upcoming "Decree for the Requirements of the Use of Alternative Mineral Building Materials in Technical Constructions and for the Amendment of the Federal Soil Protection and Contaminated Sites Ordinance" of the German Federal Ministry of Environment. The new concept aims at a holistic and scientifically sound assessment of the use of mineral recycling materials (e.g., mineral waste, excavated soils, slag and ashes, recycling products, etc.) in technical constructions (e.g., road dams) and permanent applications (e.g., backfilling and landscaping) which is based on a mechanistic understanding of leaching and transport processes. Fundamental for risk assessment are leaching standards for the mineral recycling materials. For each application of mineral recycling materials specific maximum concentrations of a substance in the seepage water at the bottom of an application were calculated. Technical boundary conditions and policy conventions derived from the "German precautionary groundwater and soil protection policy" were accounted to prevent adverse environmental effects on the media soil and groundwater. This includes the concentration decline of highly soluble substances (e.g., chloride and sulphate), retardation or attenuation of solutes, accumulation of contaminants in sub-soils and the hydraulic properties of recycling materials used for specific applications. To decide whether the use of a mineral recycling material is possible in a specific application, the leaching qualities were evaluated based on column percolation tests with various samples and compared with application-specific maximum concentrations. In the upcoming federal decree this simplified concept is realized using detailed tables which classify the leaching quality of mineral recycling materials and demonstrate potential application. A quality assurance system will be mandatory which defines specific testing programs (material properties and limit concentrations to be tested, number and schedule of testing) for the different mineral recycling materials using standardized methods (column percolation test). PMID:20933380

Susset, Bernd; Grathwohl, Peter

2010-10-08

209

Recycling Service Learning Activity  

NSDL National Science Digital Library

The recycling project begins with students learning about waste and resources. They complete background assignments about the energy and materials required to manufacture paper, aluminum, etc. They study landfills and the issues related to space, pollution, etc. They look at what is different if these things are recycled. The students work in groups of two or three and adopt and academic building on campus. They educate the staff and faculty about recycling - what can be recycled and where. They arrange to pick-up paper from each office. My hope is that the college faculty, staff and students will eventually recycle paper at common bins and that our project will progress to adding other recyclables to our project.

Faatz, Renee

210

AQUEOUS AMMONIA EQUILIBRIUM - TABULATION OF PERCENT UN-IONIZED AMMONIA  

EPA Science Inventory

The percent of un-ionized ammonia as a function of pH and temperature in aqueous ammonia solutions of zero salinity is presented in tabular form over the following ranges: temperature 0.0 to 40.0 C in increments of 0.2 degree, and pH 5.00 to 12.00 in increments of 0.01 pH unit....

211

ENGINEERING DESIGN CONFIGURATIONS FOR BIOLOGICAL AMMONIA REMOVAL  

EPA Science Inventory

Many regions in the United States have excessive levels of nutrients including ammonia in their source waters. For example, farming and agricultural sources of ammonia in the Midwest contribute to relatively high levels of ammonia in many ground waters. Although ammonia in water ...

212

Breath Ammonia Analysis: Clinical Application and Measurement  

Microsoft Academic Search

This review covers in detail the complexity of human breath, how the body metabolizes ammonia, clinical conditions which are directly related to the regulation of ammonia concentration, and analysis of current techniques that are capable of detecting breath ammonia. Focusing on these areas provides the information needed to develop a breath ammonia sensor for monitoring dysfunction of the human body.

Troy Hibbard; Anthony J. Killard

2011-01-01

213

Ammonia distribution and excretion in fish  

Microsoft Academic Search

This paper reviews the literature concerning ammonia production, storage and excretion in fish. Ammonia is the end product of protein catabolism and is stored in the body of fish in high concentrations relative to basal excretion rates. Ammonia, if allowed to accumulate, is toxic and is converted to less toxic compounds or excreted. Like other weak acids and bases, ammonia

David J. Randall; Patricia A. Wright

1987-01-01

214

Factors Influencing Household Recycling Behavior  

Microsoft Academic Search

To investigate factors encouraging or deterring recycling, telephone interviews were used to study recycling behavior, attitudes, and knowledge of 221 randomly selected adults in a suburban city that had begun a citywide curbside recycling program within the past year. Approximately 40% reported participation in the curbside recycling program, and nearly 20% more claimed that their household had been recycling in

Stuart Oskamp; Maura J. Harrington; Todd C. Edwards; Deborah L. Sherwood; Shawn M. Okuda; Deborah C. Swanson

1991-01-01

215

Benchmarking survey for recycling.  

SciTech Connect

This report describes the methodology, analysis and conclusions of a comparison survey of recycling programs at ten Department of Energy sites including Sandia National Laboratories/New Mexico (SNL/NM). The goal of the survey was to compare SNL/NM's recycling performance with that of other federal facilities, and to identify activities and programs that could be implemented at SNL/NM to improve recycling performance.

Marley, Margie Charlotte; Mizner, Jack Harry

2005-06-01

216

Ammonia transport by terrestrial and aquatic insects.  

PubMed

Ammonia, an end product from amino acid and nucleic acid metabolism, is highly toxic for most animals. This review will provide an update on nitrogen metabolism in terrestrial and aquatic insects with emphasis on ammonia generation and transport. Aspects that will be discussed include metabolic pathways of nitrogenous compounds, the origin of ammonia and other nitrogenous waste products, ammonia toxicity, putative ammonia transporters as well as ammonia transport processes known in insects. Ammonia transport mechanisms in the mosquito Aedes aegypti, the tobacco hornworm Manduca sexta and the locust Schistocerca gregaria will be discussed in detail while providing additional, novel data. PMID:22100291

Weihrauch, Dirk; Donini, Andrew; O'Donnell, Michael J

2011-11-10

217

20 Watt Liquid Ammonia Battery.  

National Technical Information Service (NTIS)

The application of existing technology in the field of nonaqueous electrochemistry was applied to specific requirements for a liquid ammonia primary reserve battery that could be used with manpack communications equipment. The design requirements were tai...

R. J. Horning

1970-01-01

218

On position-space renormalization group approach to percolation  

NASA Astrophysics Data System (ADS)

In a position-space renormalization group (PSRG) approach to percolation one calculates the probability R(p,b) that a finite lattice of linear size b percolates, where p is the occupation probability of a site or bond. A sequence of percolation thresholds p c (b) is then estimated from R(p c , b)=p c (b) and extrapolated to the limit b?? to obtain p c = p c (?). Recently, it was shown that for a certain spanning rule and boundary condition, R(p c , ?)=R c is universal, and since p c is not universal, the validity of PSRG approaches was questioned. We suggest that the equation R(p c , b)=?, where ? is any number in (0,1), provides a sequence of p c (b)'s that always converges to p c as b??. Thus, there is an envelope from any point inside of which one can converge to p c . However, the convergence is optimal if ?= R c . By calculating the fractal dimension of the sample-spanning cluster at p c , we show that the same is true about any critical exponent of percolation that is calculated by a PSRG method. Thus PSRG methods are still a useful tool for investigating percolation properties of disordered systems.

Sahimi, Muhammad; Rassamdana, Hossein

1995-02-01

219

Ammonia abundances in four comets  

Microsoft Academic Search

NH2 emission band strengths were measured in four comets and the NH2 column densities were determined in order to measure the ammonia content of the comets. The mean ammonia\\/water abundance ratio derived for the four comets is found to be 0.13 + or - 0.06 percent, with no significant variation among the comets. The uniformity of this abundance attests to

S. Wyckoff; S. C. Tegler; L. Engel

1991-01-01

220

Resid hydrotreating with high temperature flash drum recycle oil  

SciTech Connect

A hydrotreating process is described, comprising the steps of: mixing recycled flash drum oil with nonhydrotreated virgin resid oil in a feed drum; while concurrently heating the nonhydrotreated virgin resid oil with the recycled flash drum oil; feeding the feed oil comprising the nonhydrotreated virgin resid oil and the recycled flash drum oil to a reactor train comprising a series of ebullated bed reactors; conveying a hydrotreating catalyst to the reactor train; injecting feed gases comprising hydrogen and methane into the ebullated bed reactors; ebullating and hydrotreating the feed oil with the feed gases in the presence of the hydrotreating catalyst at a hydrotreating temperature in the ebullated bed reactors to produce an upgraded product stream comprising hydrotreated resid oil and effluent tail gases comprising hydrogen, hydrogen sulfide, ammonia, water, and methane; and separating the product stream in a separator into an overhead stream of gases and oil vapors and a bottom stream of separator oil.

McDaniel, N.K.; Vasti, N.C.; Woods, N.R.; Boening, R.E.

1989-02-28

221

Percolation and localization dynamics in silicon nanocrystal films  

NASA Astrophysics Data System (ADS)

We apply time-resolved THz spectroscopy [1] to probe the time progression of the ac-conductivity in optically excited Si nanocrystal (NC) films with varying Si vol %, NC sizes and separations. A percolation transition is observed at 38 ± 1 vol % Si. Above this threshold, we observe a transition form initial (<50 ps) long-range percolative inter-NC transport characterized by a non-zero DC conductivity to eventual localization of carriers at individual NCs. Below percolation threshold, early-time (<25 ps) inter-NC tunneling conduction is observed in films with sub-nm separations, followed by the final localization of the photoexcited carriers in the largest NCs. In the films with larger (> 1 nm) inter-NC spacing, long-range transport is suppressed suggesting strong photoexcited carrier localization. Comparison of the observed dynamics to Monte Carlo simulations will be discussed. [1] D. G. Cooke et al, Phys. Rev. B 73, 193311 (2006).

Titova, L. V.; Cocker, T. L.; Wang, X. Y.; Cooke, D. G.; Meldrum, A.; Hegmann, F. A.

2010-03-01

222

Three-dimensional Ising model, percolation theory and conformal invariance  

NASA Astrophysics Data System (ADS)

The fractal structure and scaling properties of a 2d slice of the 3d Ising model is studied using Monte Carlo techniques. The percolation transition of geometric spin (GS) clusters is found to occur at the Curie point, reflecting the critical behavior of the 3d model. The fractal dimension and the winding angle statistics of the perimeter and external perimeter of the geometric spin clusters at the critical point suggest that, if conformally invariant in the scaling limit, they can be described by the theory of Schramm-Löwner evolution (SLE?) with diffusivity of ?=5 and 16/5, respectively, putting them in the same universality class as the interfaces in 2d tricritical Ising model. It is also found that the Fortuin-Kasteleyn (FK) clusters associated with the cross-sections undergo a nontrivial percolation transition, in the same universality class as the ordinary 2d critical percolation.

Saberi, A. A.; Dashti-Naserabadi, H.

2010-12-01

223

Critical phenomena in heterogeneous k-core percolation.  

PubMed

k-core percolation is a percolation model which gives a notion of network functionality and has many applications in network science. In analyzing the resilience of a network under random damage, an extension of this model is introduced, allowing different vertices to have their own degree of resilience. This extension is named heterogeneous k-core percolation and it is characterized by several interesting critical phenomena. Here we analytically investigate binary mixtures in a wide class of configuration model networks and categorize the different critical phenomena which may occur. We observe the presence of critical and tricritical points and give a general criterion for the occurrence of a tricritical point. The calculated critical exponents show cases in which the model belongs to the same universality class of facilitated spin models studied in the context of the glass transition. PMID:23496486

Cellai, Davide; Lawlor, Aonghus; Dawson, Kenneth A; Gleeson, James P

2013-02-21

224

Households’ recycling efforts  

Microsoft Academic Search

Households’ recycling effort is often argued to be of an insignificant size. It is also frequently argued that this contribution, if significant, is not a cost to households, since it is voluntary. Thus households’ use of time and energy are frequently disregarded in cost-benefit analyses of stricter recycling targets. In this survey, based on 1162 interviews, we find that sorting

Annegrete Bruvoll; Bente Halvorsen; Karine Nyborg

2002-01-01

225

Economics of PC Recycling  

Microsoft Academic Search

As the use of personal computers (PCs) increases, their short life cycle and the fact that they contain many hazardous materials means that their retirement and disposal represents a significant environmental concern. Many communities are mandating the recycling of these PCs, to recover parts and materials, and to minimize the amount of waste landfilled or incinerated. An industry to recycle

Jane E. Boon; Jacqueline A. Isaacs; Surendra M. Gupta

226

Refuse recycling and recovery  

Microsoft Academic Search

A growing sense of dissatisfaction over the waste of resources in traditional disposal methods has not yet overcome the economic barriers of recycling costs and the difficulties of marketing recycled materials. The author examines several waste-recovery technologies, such as incineration and waste-derived fuels, and the constraints which work against time. He describes two plants in the United Kingdom and the

1981-01-01

227

Recycling TATB PBX.  

National Technical Information Service (NTIS)

The feasibility of recycling IHE has been successfully demonstrated on a large scale by processing over 750 kg of machining scrap. The content of machine cuttings in the recycled PBX lots was 50, 75, and 100%. Physical strengths were generally above norma...

A. G. Osborn H. D. Johnson T. L. Stallings

1978-01-01

228

Is mandated recycling possible  

Microsoft Academic Search

If piles of potentially recyclable materials are accumulated as a result of a mandatory source separation program, what options exist for the community First, it could attempt to market the recyclables through normal commercial channels. Second, the community could attempt to market the materials at lower prices to the consumers, since any contribution above available disposal cost is a profit

Cutler

1988-01-01

229

Recycling the junk car  

Microsoft Academic Search

A systems approach to recycling junk cars as a major renewable resource is proposed, although this will require some legislative, technological, and economic changes. The volume of materials contained in automobiles makes them the major source of scrap steel, but recycling can also yield secondary supplies of zinc, copper, aluminum, rubber, and plastics. Economic considerations have historically singled out scrap

Harwood

1977-01-01

230

Recycle of battery materials  

SciTech Connect

Studies were conducted on the recycling of advanced battery system components for six different battery systems. These include: Nickel/Zinc, Nickel/Iron, Zinc/Chlorine, Zinc/Bromine, Sodium/Sulfur, and Lithium-Aluminum/Iron Sulfide. For each battery system, one or more processes has been developed which would permit recycling of the major or active materials.

Pemsler, J.P.; Spitz, R.A.

1981-01-01

231

Study on TV recyclability  

Microsoft Academic Search

Due to the depletion of natural resources, the shortage of dumping sites and the environmental pollution caused by hazardous chemical substances, there is a growing demand for the recycling of discarded products. The electrical home appliance industry has continued its efforts to develop easy-to-recycle products. In order to recognize the effects of these improvements and to identify subjects for future

Takayuki Nishi; M. Hirano; T. Ohashi; K. Ueno; Y. Hiroshige

1999-01-01

232

AIRCRAFT INDUSTRY WASTEWATER RECYCLING  

EPA Science Inventory

The feasibility of recycling certain categories of water used in the manufacture of airplanes was demonstrated. Water in four categories was continuously recycled in 380-liter (100-gallon) treatment plants; chemical process rinse water, dye-penetrant crack-detection rinse water, ...

233

Visiting a Recycling Plant  

NSDL National Science Digital Library

In this ZOOM video segment, cast member Francesco follows the paper trail to find out what happens to his recyclables. He visits a material recovery center and learns how paper is recycled and the number of trees that are saved as a result.

Foundation, Wgbh E.

2005-10-21

234

Recycling into Art  

NSDL National Science Digital Library

This interdisciplinary unit weaves art and science together to help students appreciate the importance of recycling. In this engaging activity, students collected items worthy of recycling from home, and with the help of the art teacher, used a loom to cr

Fioranelli, Debra

2000-10-01

235

Recycling at Camp.  

ERIC Educational Resources Information Center

Outlines a Michigan summer camp's efforts to reduce solid waste disposal by recycling cardboard, tin, glass, aluminum, and plastic milk containers. Points out variables affecting the success of such efforts. Discusses Michigan state funding for the development of recycling programs. (SV)

Cummins, William M.

1988-01-01

236

Partnership: Recycling $/$ Outdoor Education.  

ERIC Educational Resources Information Center

|The Ottawa Board of Education (Ontario, Canada) has committed revenues generated by a districtwide recycling program to help fund the MacSkimming Outdoor Education Centre. A partnership between recycling and outdoor education is valuable in developing an environmental ethic among students and in finding new ways to fund outdoor education. (LP)|

Weir, Phil

1996-01-01

237

Advances in plastic recycling. Volume 1: Recycling of polyurethanes  

SciTech Connect

``Recycling of Polyurethanes'', the first volume in the Advances in Plastics Recycling series, is focused on the physical and chemical recycling of polyurethanes, with attention given to energy conversion. A compilation of the present ongoing studies on recycling of urethane and, in general, isocyanate-based polymers, the focus is on thermosetting urethane polymers. Contents include: Recycling of Polyurethane Plastics in the European Automotive Industry; Present State of Polyurethane Recycling in Europe; Processing Overview of Bonded Polyurethane Foam; Mechanical Recycling of Polyurethane Scrap; Ecostream{trademark}--A Technology Beyond Recycling; Recycling of Flexible polyurethane Foam; General purpose Adhesives Prepared from Chemically Recycled Waste Rigid Polyurethane Foams; and Utilization of Isocyanate Binders in Recycling of Scrap Automotive Headliners.

Frisch, K.C.; Klempner, D.; Prentice, G.

1999-07-01

238

Percolation models for boiling and bubble growth in porous media  

SciTech Connect

We analyze the liquid-to-vapor phase change in single-component fluids in porous media at low superheats. Conditions typical to steam injection in porous media are taken. We examine nucleation, phase equilibria and their stability, and the growth of vapor bubbles. Effects of pore structure are emphasized. It is shown that at low supersaturations, bubble growth can be described as a percolation process. In the absence of spatial gradients, macroscopic flow properties are calculated in terms of nucleation parameters. A modification of gradient percolation is also proposed in the case of spatial temperature gradients, when solid conduction predominates. 22 refs., 10 figs., 1 tab.

Yortsos, Y.C.

1991-05-01

239

Coexistence in two-type first-passage percolation models  

Microsoft Academic Search

We study the problem of coexistence in a two-type competition model governed by first-passage percolation on ?d<\\/sup> or on the infinite cluster in Bernoulli percolation. We prove for a large class of ergodic stationary passage times that for distinct points x,y??d<\\/sup>, there is a strictly positive probability that {z??d<\\/sup>;d(y,z)d<\\/sup>;d(y,z)>d(x,z)} are both infinite sets. We also show that there

Olivier Garet; Régine Marchand

2005-01-01

240

Critical behavior of nanoemitter radiation in a percolation material  

NASA Astrophysics Data System (ADS)

We studied the field radiation of disordered optical nanoemitters incorporated into three-dimensional (3D) spanning cluster in a percolation material. In supercritical state, the field intensity is large enough to produce a dynamic high-density coherent field. The resulting state becomes different for lossless and lossy mediums. For material with small losses the long-term coherence arises in the supercritical area close to the percolation threshold. As a result, the dynamic non-monotonic behavior of the field order parameter raises that allows to reach the optimal field intensity. This effect can allow optimization of the disordered optical nanostructures with incorporated radiating nanoemitters in various applications of information technology.

Burlak, G.; Díaz-de-Anda, A.; Karlovich, Yu.; Klimov, A. B.

2009-04-01

241

Scaling Theory for Percolative Charge Transport in Disordered Molecular Semiconductors  

NASA Astrophysics Data System (ADS)

We present a scaling theory for charge transport in disordered molecular semiconductors that extends percolation theory by including bonds with conductances close to the percolating one in the random-resistor network representing charge hopping. A general and compact expression is given for the charge mobility for Miller-Abrahams and Marcus hopping on different lattices with Gaussian energy disorder, with parameters determined from numerically exact results. The charge-concentration dependence is universal. The model-specific temperature dependence can be used to distinguish between the hopping models.

Cottaar, J.; Koster, L. J. A.; Coehoorn, R.; Bobbert, P. A.

2011-09-01

242

Remnant percolative disorder in highly-cured networks  

SciTech Connect

The authors have previously reported viscoelastic measurements demonstrating that fully-cured networks and critical gels exhibit similar relaxation spectra, implying that fully-cured networks are somewhat ill- connected. Here, they present restricted valence percolation simulations of networks well beyond the percolation transition that explicitly display remnant disorder over length scales less than the correlation length of the network. They conclude that the topology of highly-cured networks is not well described by a regular three- dimensional tennis net but is ill-connected over length scales that correspond to relaxation modes of practical interest.

Adolf, D.; Hance, B.; Martin, J.E. (Sandia National Labs., Albuquerque, NM (United States))

1993-05-24

243

Global Seabird Ammonia Emissions  

NASA Astrophysics Data System (ADS)

Seabird colonies represent a major source of atmospheric ammonia (NH3) in remote coastal and marine systems in temperate, tropical and polar regions. Previous studies have shown that NH3 emissions from Scottish seabird colonies were substantial - of similar magnitude to the most intensive agricultural point source emissions. The UK data were used to model global seabird NH3 emissions and suggested that penguins are a major source of emissions on and around the Antarctic continent. The largest seabird colonies are in the order of millions of seabirds. Due to the isolation of these colonies from anthropogenic nitrogen sources, they may play a major role in the nitrogen cycle within these ecosystems. A global seabird database was constructed and used in conjunction with a species-specific seabird bioenergetics model to map the locations of NH3 emissions from seabird colonies. The accuracy of the modelled emissions was validated with field data of NH3 emissions measured at key seabird colonies in different climatic regions of the world: temperate (Isle of May, Scotland), tropical (Ascension Island) and polar (Signy Island, South Georgia). The field data indicated good agreement between modelled and measured NH3 emissions. The measured NH3 emissions also showed the variability of emission with climate. Climate dependence of seabird NH3 emissions may have further implications under a changing global climate. Seabird colonies represent NH3 emission ‘hotspots’, often far from anthropogenic sources, and are likely to be the major source of nitrogen input to these remote coastal ecosystems. The direct manuring by seabirds at colony locations may strongly influence species richness and biodiversity. The subsequent volatilisation and deposition of NH3 increases the spatial extent of seabird influence on nitrogen cycling in their local ecosystem. As many seabird populations are fluctuating due to changing food supply, climate change or anthropogenic pressures, these factors may have far reaching impact on the supply of nitrogen from seabird colonies to their current local ecosystems.

Riddick, S. N.; Blackall, T. D.; Dragosits, U.; Daunt, F. H.; Braban, C. F.; Tang, Y. S.; Trathan, P.; Wanless, S.; Sutton, M. A.

2010-12-01

244

Apparatus for ammonia synthesis  

SciTech Connect

Apparatus is described for the synthesis of ammonia, comprising: a first vertical synthesis reactor comprising a first reactor shell and a first catalyst bed contained in a first catalyst holder positioned within and spaced apart from the first reactor shell to provide a first annulus between the first catalyst holder and the first reactor shell to allow feed gas to enter the first catalyst bed; a second vertical synthesis reactor comprising a second reactor shell and a second catalyst bed contained in a second catalyst holder positioned within and spaced apart from the second reactor shell to provide a second annulus between the second catalyst holder and second reactor shell to allow feed gas to enter the second catalyst bed; a gas-gas heat exchanger; a first coupling means for coupling the bottom end of the first reactor to the gas-gas heat exchanger, the first coupling means having a first conduit between the fist annulus and the gas-gas heat exchanger for passage of feed to the first catalyst bed and a second conduit to pass effluent from the first catalyst bed to the gas-gas heat exchanger; a second heat exchanger comprising an exchanger shell having disposed therein a first tube bundle and a second tube bundle disposed in an interior portion of the exchanger shell inside of the first tube bundle; a second coupling means for coupling the bottom end of the second reactor to the second heat exchanger, the second coupling means having a third conduit between the second annulus and the outlet of the first tube bundle for passage of feed to the second catalyst bed and a fourth conduit to pass effluent from the second catalyst bed to the second tube bundle; and a fifth conduit to pass effluent from the gas-gas heat exchanger to the inlet of the first tube bundle.

Grotz, B.J.

1993-08-17

245

MEASUREMENT OF AMMONIA RELEASE FROM SALTSTONE  

SciTech Connect

SRNL was requested by WSRC Waste Solidification Engineering to characterize the release of ammonia from saltstone curing at 95 C by performing experimental testing. These tests were performed with an MCU-type Tank 50H salt simulant containing 0, 50, and 200 mg/L ammonia. The testing program showed that above saltstone made from the 200 mg/L ammonia simulant, the vapor space ammonia concentration was about 2.7 mg/L vapor at 95 C. An upper 95% confidence value for this concentration was found to be 3.9 mg/L. Testing also showed that ammonia was chemically generated from curing saltstone at 95 C; the amount of ammonia generated was estimated to be equivalent to 121 mg/L additional ammonia in the salt solution feed. Even with chemical generation, the ammonia release from saltstone was found to be lower than its release from salt solution only with 200 mg/L ammonia.

Zamecnik, J; Alex Cozzi, A

2009-01-15

246

75 FR 71003 - America Recycles Day, 2010  

Federal Register 2010, 2011, 2012, 2013

...our planet, participating in curbside recycling and community composting programs, and...of recyclable and recycled materials. Recycling not only preserves our environment by...workers nationwide, and evolving our recycling practices can help create green...

2010-11-19

247

Numerical calculation of the conductivity of percolation clusters and the use of special purpose computers.  

National Technical Information Service (NTIS)

Electrical conductivity diffusion or phonons, have an anomalous behaviour on percolation clusters at the percolation threshold due to the fractality of these clusters. The results that have been found numerically for this anomalous behaviour are reviewed....

H. J. Herrmann

1989-01-01

248

Comparison of Analytic and Numerical Results for the Mean Cluster Density in Continuum Percolation.  

National Technical Information Service (NTIS)

The Kirkwood-Salsburg equations for percolation give formally exact relations that hold for large classes of continuum percolation models. These bounding procedures provide valuable constraints on any approximation scheme. These bounds do not converge rap...

J. A. Given I. C. Kim S. Torquato G. Stell

1990-01-01

249

Recycle Used Oil on America Recycles Day  

NSDL National Science Digital Library

Motor oil doesn't wear out--it just gets dirty. Students and the general public may not know that used oil can be reused or recycled. The fact is, used oil can be re-fined, blended with additives, and used again. When you consider that 1.4 billion gallons

White, Boyd W.

2000-11-01

250

Fractional scaling of quantum walks on two-dimensional percolation lattices  

NASA Astrophysics Data System (ADS)

We study the spreading behaviour of coined quantum walks on percolation lattices for both bond and site percolation on two-dimensional Cartesian lattices. Using numerical simulation, we observe fractional scaling of the spreading with the number of steps of the walk. The exponent varies from zero at the critical percolation probability through to unity for the full lattice. For the lattices we simulate, up to 140×140, we observe faster than classical scaling for percolation probabilities above about 0.85.

Kendon, Viv; Leung, Godfrey; Knott, Paul; Bailey, Joe

2011-10-01

251

A Percolation Explanation of the Temperature Dependent Resistivity in Disordered Carbon-Black/Polymer Composites  

NASA Astrophysics Data System (ADS)

We have measured the resistivity of a series of disordered carbon-black/polymer composites between 25C and 100C. The resistivity data at every measured temperature can be explained by percolation scaling laws with universal exponents. The temperature dependence of the fitted percolation parameters suggests the changes in resistivity are caused by abrupt breaking of some of the percolative pathways, and gradual increases in the resistivity of the remaining percolative pathways.

Heaney, Michael B.; Pan, Heidi

1998-03-01

252

Motivation recycling: pre-recycling case study in Minsk, Belarus.  

PubMed

Given the aim of motivating householders to behave in a recycling-friendly manner, there is a need to understand consumers' recycling behaviour. This paper documents and analyses acceptability and awareness of a pre-recycling society, through a survey carried out in the region of Minsk, Belarus. The results show a large number of people have no strong awareness about separate collection of household waste for recycling. By analysing the pre-recycling behaviour of Minsk citizens and substantive comparison with literature studies of a more mature recycling society such as Sweden, we indicate common sociodemographic variables for both cases and determine that these sociodemographic characteristics will directly influence recycling behaviour in countries like Belarus. It is also noted that the lack of recycling habit cannot directly predict subsequent recycling behaviour on the stage of implementation the recycling system. PMID:20124319

Miafodzyeva, Sviatlana; Brandt, Nils; Olsson, Monika

2010-02-02

253

The Ammonia Dimer Revisited  

NASA Astrophysics Data System (ADS)

The conclusion from microwave spectra by Nelson, Fraser, and Klemperer that the ammonia dimer has a nearly cyclic structure led to much debate about the issue of whether (NH_3)_2 is hydrogen bonded. This structure was surprising because most {ab initio} calculations led to a classical, nearly linear, hydrogen-bonded structure. An obvious explanation of the discrepancy between the outcome of these calculations and the microwave data which led Nelson {et al.} to their ``surprising structure'' might be the effect of vibrational averaging: the electronic structure calculations focus on finding the minimum of the intermolecular potential, the experiment gives a vibrationally averaged structure. Isotope substitution studies seemed to indicate, however, that the complex is nearly rigid. Additional data became available from high-resolution molecular beam far-infrared spectroscopy in the Saykally group. These spectra, displaying large tunneling splittings, indicate that the complex is very floppy. The seemingly contradictory experimental data were explained when it became possible to calculate the vibration-rotation-tunneling (VRT) states of the complex on a six-dimensional intermolecular potential surface. The potential used was a simple model potential, with parameters fitted to the far-infrared data. Now, for the first time, a six-dimensional potential was computed by high level {ab initio} methods and this potential will be used in calculations of the VRT states of (NH_3)_2 and (ND_3)_2. So, we will finally be able to answer the question whether the conclusions from the model calculations are indeed a valid explanation of the experimental data. D. Nelson, G. T. Fraser, and W. Klemperer J. Chem. Phys. 83 6201 (1985) J. G. Loeser, C. A. Schmuttenmaer, R. C. Cohen, M. J. Elrod, D. W. Steyert, R. J. Saykally, R. E. Bumgarner, and G. A. Blake J. Chem. Phys. 97 4727 (1992) E. H. T. Olthof, A. van der Avoird, and P. E. S. Wormer J. Chem. Phys. 101 8430 (1994) E. H. T. Olthof, A. van der Avoird, P. E. S. Wormer, J. G. Loeser, and R. J. Saykally J. Chem. Phys. 101 8443 (1994)

Dawes, Richard; Van Der Avoird, Ad

2012-06-01

254

The electrical conductivity of binary disordered systems, percolation clusters, fractals and related models  

Microsoft Academic Search

We review theoretical and experimental studies of the AC dielectric response of inhomogeneous materials, modelled as bond percolation networks, with a binary (conductor-dielectric) distribution of bond conductances. We first summarize the key results of percolation theory, concerning mostly geometrical and static (DC) transport properties, with emphasis on the scaling properties of the critical region around the percolation threshold. The frequency-dependent

J. P. Clerc; G. Giraud; J. M. Laugier; J. M. Luck

1990-01-01

255

Dragnet: Nonprofit Computer Recyclers  

NSDL National Science Digital Library

If you have ever wondered what happens to obsolete computers, check out these current awareness Websites. The disposal of computers is classified as hazardous waste, which has become an environmental concern as the number of obsolete computers rises. In fact, the Wisconsin Department of Natural Resources and the State of Massachusetts have banned computer equipment from landfills. Dragnet: Nonprofit Computer Recyclers is an EPA-licensed computer recycling organization that reuses all acceptable components and systems or recycles damaged or unusable components. Rebuilt computer systems are given to "persons with disabilities and persons living in disadvantaged situations."

256

Water-network percolation transitions in hydrated yeast  

NASA Astrophysics Data System (ADS)

We discovered two percolation processes in succession in dc conductivity of bulk baker’s yeast in the course of dehydration. Critical exponents characteristic for the three-dimensional network for heavily hydrated system, and two dimensions in the light hydration limit, evidenced a dramatic change of the water network dimensionality in the dehydration process.

Soko?owska, Dagmara; Król-Otwinowska, Agnieszka; Mo?cicki, Józef K.

2004-11-01

257

First-passage percolation on the random graph  

Microsoft Academic Search

We study rst passage percolation on the random graph Gp(N) with exponentially distributed weights on the links. For the special case of the complete graph this problem can be described in terms of a continuous time Markov chain and recursive trees. The Markov chain X(t) describes the number of nodes that can be reached from the initial node in time

Remco van der Hofstad; Gerard Hooghiemstra; Piet Van Mieghem

2001-01-01

258

Epidemics and percolation in small-world networks  

Microsoft Academic Search

We study some simple models of disease transmission on small-world networks, in which either the probability of infection by a disease or the probability of its transmission is varied, or both. The resulting models display epidemic behavior when the infection or transmission probability rises above the threshold for site or bond percolation on the network, and we give exact solutions

Cristopher Moore; M. E. J. Newman

2000-01-01

259

Continuum Percolation with Unreliable and Spread-Out Connections  

Microsoft Academic Search

We derive percolation results in the continuum plane that lead to what appears to be a general tendency of many stochastic network models. Namely, when the selection mechanism according to which nodes are connected to each other, is sufficiently spread out, then a lower density of nodes, or on average fewer connections per node, are sufficient to obtain an unbounded

Massimo Franceschetti; Lorna Booth; Matthew Cook; Ronald Meester; Jehoshua Bruck

2005-01-01

260

Finite-Size Effects for Anisotropic Bootstrap Percolation: Logarithmic Corrections  

NASA Astrophysics Data System (ADS)

In this note we analyse an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced by Duarte.

van Enter, Aernout C. D.; Hulshof, Tim

2007-09-01

261

Percolation modeling of foam generation in porous media  

Microsoft Academic Search

A foam is a dispersion of a large volume of gas in a continuous liquid phase, stabilized by surfactant. Foams can improve sweep efficiency and oil recovery in gas-injection enhanced oil recovery projects. An important issue for these foam processes is the ease of foam generation in porous media. Previously, Rossen and Gauglitz (1990) derived a percolation model for foam

William R. Rossen; Jianxin Shi; Sabine C. Zeilinger

1994-01-01

262

Analysis of percolation and seepage through paddy bunds  

Microsoft Academic Search

This study investigates percolation and seepage through the bunds of flat and terraced paddies. Field experiments were conducted in Hsin-Pu of Hsin-Chu County, Taiwan, to measure the soil water content of various types of bund. Measurements revealed that the soil was unsaturated along the sloped surface of the terrace. Experimental results also indicated that seepage face flow did not develop

Han-Chen Huang; Chen-Wuing Liu; Shih-Kai Chen; Jui-Sheng Chen

2003-01-01

263

Percolative theories of strongly disordered ceramic high-temperature superconductors.  

PubMed

Optimally doped ceramic superconductors (cuprates, pnictides, etc.) exhibit transition temperatures T(c) much larger than strongly coupled metallic superconductors like Pb (T(c) = 7.2 K, E(g)/kT(c) = 4.5) and exhibit many universal features that appear to contradict the Bardeen, Cooper, and Schrieffer theory of superconductivity based on attractive electron-phonon pairing interactions. These complex materials are strongly disordered and contain several competing nanophases that cannot be described effectively by parameterized Hamiltonian models, yet their phase diagrams also exhibit many universal features in both the normal and superconductive states. Here we review the rapidly growing body of experimental results that suggest that these anomalously universal features are the result of marginal stabilities of the ceramic electronic and lattice structures. These dual marginal stabilities favor both electronic percolation of a dopant network and rigidity percolation of the deformed lattice network. This "double percolation" model has previously explained many features of the normal-state transport properties of these materials and is the only theory that has successfully predicted strict lowest upper bounds for T(c) in the cuprate and pnictide families. Here it is extended to include Coulomb correlations and percolative band narrowing, as well as an angular energy gap equation, which rationalizes angularly averaged gap/T(c) ratios, and shows that these are similar to those of conventional strongly coupled superconductors. PMID:20080578

Phillips, J C

2010-01-06

264

Asperity distribution and percolation as fundamentals of an earthquake cycle  

Microsoft Academic Search

A seismic cycle model is proposed, based on the existence of an asperity space-strength distribution along the fault plane and the applicability of the percolation theory to earthquakes, as suggested by Vrancea seismotectonic data. Two seismic regions, somewhat decoupled, are emphasized in the lower lithosphere, roughly between 80 and 110 km and between 120 and 170 km depth, and an

Cezar-Ioan Trifu; Mircea Radulian

1989-01-01

265

Ammonia observations of outflow regions  

SciTech Connect

Observations of the (J,K) = (1,1) ammonia transition toward the suspected exciting sources of 12 regions with molecular or optical outflows are presented. In nine of these regions, ammonia emission was detected and mapped. The spatial coincidence of the high-density gas in the proposed exciting sources in five of the mapped regions supports the identification as exciting sources. A new location is proposed for the outflow exciting sources of L1524 (Haro 6-10) and HH 38,43. Also, in L1448, a radio continuum source and an unusually strong H2O maser coinciding with the maximum ammonia emission is detected. It is proposed that this region is the site of very recent star formation. 73 refs.

Anglada, G.; Estalella, R.; Rodriguez, L.F.; Ho, P.T.P.; Torrelles, J.M. (Barcelona Universidad (Spain); Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (USA); Instituto de Astrofisica de Andalucia, Granada (Spain))

1989-06-01

266

Novel percolation phenomena and mechanism of strengthening elastomers by nanofillers.  

PubMed

Nano-strengthening by employing nanoparticles is necessary for high-efficiency strengthening of elastomers, which has already been validated by numerous researches and industrial applications, but the underlying mechanism is still an open challenge. In this work, we mainly focus our attention on studying the variation of the tensile strength of nanofilled elastomers by gradually increasing the filler content, within a low loading range. Interestingly, the percolation phenomenon is observed in the relationship between the tensile strength and the filler loading, which shares some similarities with the percolation phenomenon occurring in rubber toughened plastics. That is, as the loading of nanofillers (carbon black, zinc oxide) increases, the tensile strength of rubber nanocomposites (SBR, EPDM) increases slowly at first, then increases abruptly and finally levels off. Meanwhile, the bigger the particle size, the higher the filler content at the percolation point, and the lower the corresponding tensile strength of rubber nanocomposites. The concept of a critical particle-particle distance (CPD) is proposed to explain the observed percolation phenomenon. It is suggested that rubber strengthening through nanoparticles is attributed to the formation of stretched straight polymer chains between neighbor particles, induced by the slippage of adsorbed polymer chains on the filler surface during tension. Meanwhile, the factors to govern this CPD and the critical minimum particle size (CMPS) figured out in this work are both discussed and analyzed in detail. Within the framework of this percolation phenomenon, this paper also clearly answers two important and intriguing issues: (1) why is it necessary and essential to strengthen elastomers through nanofillers; (2) why does it need enough loading of nanofillers to effectively strengthen elastomers. Moreover, on the basis of the percolation phenomenon, we give out some guidance for reinforcement design of rubbery materials: the interfacial interactions between rubber and fillers cannot be complete chemical bonding, and partial physical absorption of macromolecular chains on the filler surface is necessary, otherwise the formation of stretched straight chains would be seriously hindered. There should exist such an optimum crosslinking density for a certain filler reinforced rubber system, and as well an optimum filler loading for rubber strengthening. Additionally, the different percolation behaviors of Young's modulus, the tensile strength and the electrical conductivity are compared and analyzed in our work. Lastly, molecular simulation indicates that it is not possible to strengthen glassy or hard polymer matrices by incorporating spherical nanoparticles. In general, by providing substantial experimental data and detailed analyses, this work is believed to promote the fundamental understanding of rubber reinforcement, as well provide better guidance for the design of high-performance and multi-functional rubber nanocomposites. PMID:20449394

Wang, Zhenhua; Liu, Jun; Wu, Sizhu; Wang, Wenchuan; Zhang, Liqun

2010-02-09

267

Porous silicon ammonia gas sensor  

NASA Astrophysics Data System (ADS)

A planar optical waveguide is manufactured by the functionnalisation of oxidised mesoporous silicon with Bromothymol Blue to achieve a sensitive ammonia sensor suitable for low gas concentrations. The propagated light intensity is measured at the output of the waveguide. The sensitivity at low concentrations and the short time of reaction of the sensor are enhanced by a confinement effect of the gas molecules inside the pores. The dependence of the output signal with gas concentration is demonstrated. When the ammonia flow is stopped, the reversibility of the initial characteristics of the propagated light is naturally obtained with the disappearance of the gas molecules.

Chaillou, A.; Charrier, J.; Lorrain, N.; Sarret, M.; Haji, L.

2006-03-01

268

The abundance threshold for plague as a critical percolation phenomenon.  

PubMed

Percolation theory is most commonly associated with the slow flow of liquid through a porous medium, with applications to the physical sciences. Epidemiological applications have been anticipated for disease systems where the host is a plant or volume of soil, and hence is fixed in space. However, no natural examples have been reported. The central question of interest in percolation theory, the possibility of an infinite connected cluster, corresponds in infectious disease to a positive probability of an epidemic. Archived records of plague (infection with Yersinia pestis) in populations of great gerbils (Rhombomys opimus) in Kazakhstan have been used to show that epizootics only occur when more than about 0.33 of the burrow systems built by the host are occupied by family groups. The underlying mechanism for this abundance threshold is unknown. Here we present evidence that it is a percolation threshold, which arises from the difference in scale between the movements that transport infectious fleas between family groups and the vast size of contiguous landscapes colonized by gerbils. Conventional theory predicts that abundance thresholds for the spread of infectious disease arise when transmission between hosts is density dependent such that the basic reproduction number (R(0)) increases with abundance, attaining 1 at the threshold. Percolation thresholds, however, are separate, spatially explicit thresholds that indicate long-range connectivity in a system and do not coincide with R(0) = 1. Abundance thresholds are the theoretical basis for attempts to manage infectious disease by reducing the abundance of susceptibles, including vaccination and the culling of wildlife. This first natural example of a percolation threshold in a disease system invites a re-appraisal of other invasion thresholds, such as those for epidemic viral infections in African lions (Panthera leo), and of other disease systems such as bovine tuberculosis (caused by Mycobacterium bovis) in badgers (Meles meles). PMID:18668107

Davis, S; Trapman, P; Leirs, H; Begon, M; Heesterbeek, J A P

2008-07-31

269

Newell's metals recycling tradition  

SciTech Connect

Since 1976, Newell Recycling Co., Inc.'s metals recycling facility in Atlanta has been processing everything from aluminum cans to automobiles. It is a full-service metals recycling center, handling both ferrous and non-ferrous metals. Newell Recycling takes metal components and machinery and processes it into usable feedstock for metal smelters and steel mills. The facility is split into five basic processing operations: ferrous metal shredding; ferrous shearing and torching; a heavy media separation plant; a nonferrous warehouse; and aluminum can operations. The shredder is capable of handling 100 tons of steel an hour, but the actual amount varies depending on the market demand. Anywhere from between 7,000 and 9,000 tons a month are typically shredded at the facility. The Atlanta facility also processes aluminum and steel cans, demolition scrap, copper wire, brass, and over 200 other products.

Dabaie, M.

1994-11-01

270

Reduce, Reuse, Recycle  

NSDL National Science Digital Library

In this media-rich lesson featuring LOOP SCOOPS videos, students consider how the concept of needs vs. wants can help them think about ways to protect Earth's natural resources by reducing, reusing, and recycling materials.

Foundation, Wgbh E.

2010-11-30

271

A Practical Recycling Project . . .  

ERIC Educational Resources Information Center

Descirbes a school district's recycling program of aluminum lunch trays that are collected after their use. The trays are used as scrap metal in industrial education workshop and used for sand castings. (PS)

Durant, Raymond H.; Mikuska, James M.

1973-01-01

272

Recycling of nonmetallics  

USGS Publications Warehouse

The first factor determining recyclability is the composition of the material itself. Metals, for example, can be reused with little or no loss in quality. Paper and rubber, by this criterion, are less recyclable. Each time paper is recycled, some cellulose fibers are broken. Shorter fibers can mean weaker paper of perceived lower quality and value. Vulcanizing is an irreversible chemical process that precludes recycling rubber in its original form. Both materials may be reused in other applications often of lower value than the original one. To be recyclable, the discarded material must have a collection infrastructure at the source of waste generation, at a central collection site, or at curbside. The recovered material must also have a market. If it is priced noncompetitively or no market exists, if it does not meet specifications, or if it requires special technology investments which cannot be recovered through future sales, the recovered material may be stockpiled or discarded rather than recycled. ?? 1996 International Association for Mathematical Geology.

Amey, E. B.; Kelly, T. D.

1996-01-01

273

Measuring Ammonia Content in Flue Gas.  

National Technical Information Service (NTIS)

As ammonia is utilized in the desulfurization of emission from power plants, there is a standing need for efficient instruments for measuring ammonia content in flue gas. Analysis is hampered by the tendency of ammonia to be adsorbed on solid surfaces whe...

P. R. Nielsen

1988-01-01

274

Glycopyrrolate in toxic exposure to ammonia gas.  

PubMed

Ammonia (NH(3)) is a highly water-soluble, colorless, irritant gas with a unique pungent odor. Liquid ammonia stored under high pressure is still widely used for refrigeration in cold stores used for storing grains. Severe toxicity may occur following accidental exposure. We report an interesting case of accidental exposure to ammonia treated with glycopyrrolate along with other supportive measures. PMID:21633586

Bhalla, A; Mahi, S; Sharma, N; Singh, S

2011-01-01

275

21 CFR 573.180 - Anhydrous ammonia.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Anhydrous ammonia. 573.180 Section 573.180 Food and...Additive Listing § 573.180 Anhydrous ammonia. (a) The food additive anhydrous ammonia is applied directly to corn plant...

2009-04-01

276

Ammonia emissions from cattle feeding operations.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ammonia is a colorless gas with an pungent odor that occurs naturally in trace amounts in the atmosphere, where it is the dominant base. Ammonia is produced during the decomposition of livestock manure. There is concern about atmospheric ammonia because of its potential effects on air quality, wat...

277

AMBIENT AMMONIA MEASUREMENTS IN COASTAL SOUTHEASTERN VIRGINIA  

EPA Science Inventory

Results are presented from a measurement program to test an in situ ammonia measurement technique and to document the temporal and spatial variability associated with ammonia. The ammonia data were accumulated for two sites in coastal Southeastern Virginia from 15 Aug. 1979 to 31...

278

Glycopyrrolate in toxic exposure to ammonia gas  

PubMed Central

Ammonia (NH3) is a highly water-soluble, colorless, irritant gas with a unique pungent odor. Liquid ammonia stored under high pressure is still widely used for refrigeration in cold stores used for storing grains. Severe toxicity may occur following accidental exposure. We report an interesting case of accidental exposure to ammonia treated with glycopyrrolate along with other supportive measures.

Bhalla, A; Mahi, S; Sharma, N; Singh, S

2011-01-01

279

Methanol and ammonia from biomass  

Microsoft Academic Search

A wide variety of petrochemicals can be produced from wood first converting the wood to synthesis gas, which can then be converted to either methanol or ammonia and further processed to produce the desired chemical product. Some of the chemical derivatives that can be produced from these two basic intermediate products are summarized. Pacific Northwest Laboratory is currently developing a

E. G. Baker; L. K. Mudge; M. D. Brown

1984-01-01

280

Percolation effects on entangled polymer rheology and the glass transition  

NASA Astrophysics Data System (ADS)

Current thinking on the fundamentals of entangled polymer melt rheology suggests that stress relaxation in the terminal zone occurs via Reptation, chain-end fluctuation and (convective) constraint release. This scenario is not correct. It is shown through a series of experiments with selectively deuterated model polymers that relaxation occurs through a percolation process which permits large clusters of entangled polymers to stress relax before their conformations are fully relaxed. The percolation model of entanglements (R.P. Wool, Macromolecules 26, 1564, 1993) makes unique predictions regarding the dynamics of polymer chains in the terminal relaxation zone. These include: (a) Reptating homopolymer chains with molecular weight M >> Mc appear to be non-Reptating as their ends and centers relax at the same rate in a Rouse-like manner during percolation. (b) The mechanical relaxation time ?(M) is related to the Reptation time Tr~ M3 by ?(M) = Tr[(1-Mc/M)Me/Mc]2, which is the origin of the zero shear viscosity behaving as ?o~M3.4 (c) The biggest surprise is that during stress relaxation, the random coil dimensions Rg(//) and Rg(?) are not fully relaxed when the stress and birefringence relax to zero. (d) Matrix molecular weight P effects on relaxation time ?(M) of the probe chain M are as follows: When the probe chain M>>P, the matrix P-chains percolate and Rouse-like dynamics is observed for the M-Reptating chains with ?(M) ~ P1M2. (e) When the matrix P>>M, percolation does not occur for the M-chain and the relaxation time of the probe chain ?(M) ~ PoM3 is in accord with DeGennes Reptation theory. These unusual results predicted by entanglement percolation are supported by extensive experimental data (NR, SANS, DSIMS, FTIR, BR) from selectively deuterated polystyrene chains HDH, DHD, HPS and DPS. These results clearly suggest that current notions of polymer rheology need to be reconsidered. Near Tg, a new perspective on the Glass Transition of amorphous materials is offered by the Twinkling Fractal Theory (TFT). [R. P. Wool, J. Polym. Sci, Part B: Polym Phys. 46, 2765 (2008)]. TFT applications to entangled polymers include: (a) rate dependence of dynamical mechanical properties, particularly the tan delta damping peak used to measure Tg, (b) derivation of the empirical WLF and Vogel Fulcher time-temperature superposition empirical relation, (c) Physical Aging and (d) Nanoconfinement.

Wool, Richard P.

2012-07-01

281

Transcriptional Response of the Archaeal Ammonia Oxidizer Nitrosopumilus maritimus to Low and Environmentally Relevant Ammonia Concentrations.  

PubMed

The ability of chemoautotrophic ammonia-oxidizing archaea to compete for ammonia among marine microorganisms at low ambient concentrations has been in part attributed to their extremely high affinity for ammonia, but as yet there is no mechanistic understanding of supporting metabolism. We examined transcription of selected genes for anabolic functions (CO2 fixation, ammonia transport, and cell wall synthesis) and a central catabolic function (ammonia oxidation) in the thaumarchaeon Nitrosopumilus maritimus SCM1 growing at two ammonia concentrations, as measured by combined ammonia and ammonium, one well above the Km for ammonia oxidation (?500 ?M) and the other well below the Km (<10 nM). Transcript levels were generally immediately and differentially repressed when cells transitioned from ammonia-replete to ammonia-limiting conditions. Transcript levels for ammonia oxidation, CO2 fixation, and one of the ammonia transport genes were approximately the same at high and low ammonia availability. Transcripts for all analyzed genes decreased with time in the complete absence of ammonia, but with various rates of decay. The new steady-state mRNA levels established are presumably more reflective of the natural physiological state of ammonia-oxidizing archaea and offer a reference for interpreting message abundance patterns in the natural environment. PMID:23995944

Nakagawa, Tatsunori; Stahl, David A

2013-08-30

282

Recycling in a megacity.  

PubMed

In the aftermath of the 9/11 disaster, Mayor Bloomberg of New York City unveiled an aggressive budget plan that included the temporary suspension of glass and plastics recycling. This was considered by many to be anti-environmental, but the results of this study show that for lack of markets, even at zero or negative prices, nearly 90% of the plastic and glass set aside by thoughtful New Yorkers was transported to materials recovery facilities (MRFs) and from there to landfills. Sending bales of plastics to landfills is not limited to New York City. It is an environmental paradox that the United States is digging up new oil fields in pristine areas and, at the same time, continues to convert greenfields to brownfields by burying nearly 20 million tons of plastic fuel annually. The study also determined that at the present rate of source separation, estimated to be less than 30% of the available recyclables in 1999, building large, modern MRFs may increase substantially the rate of New York City recycling and also allow single-stream collection of commingled recyclables, as is done in Phoenix, AZ. Single-stream collection simplifies separation at the source by citizens and increases the amount of collected recyclables. Also, because collection represents a large fraction of the costs of waste management, it may have a significant economic advantage. PMID:15115367

Themelis, Nickolas J; Todd, Claire E

2004-04-01

283

The September 11 attack: A percolation of individual passive support  

NASA Astrophysics Data System (ADS)

A model to terrorism is presented using the theory of percolation. Terrorism power is related to the spontaneous formation of random backbones of people who are sympathetic to terrorism but without being directly involved in it. They just don't oppose in case they could. In the past such friendly-to-terrorism backbones have been always existing but were of finite size and localized to a given geographical area. The September 11 terrorist attack on the US has revealed for the first time the existence of a world wide spread extension. It is argued to have result from a sudden world percolation of otherwise unconnected and dormant world spread backbones of passive supporters. The associated strategic question is then to determine if collecting ground information could have predict and thus avoid such a transition. Our results show the answer is no, voiding the major criticism against intelligence services. To conclude the impact of military action is discussed.

Galam, S.

2002-04-01

284

The chemical gelation viewed through a percolation model simulation  

NASA Astrophysics Data System (ADS)

Many papers or reviews present the percolation theory as pertinent to the chemical gelation problem. But most of these studies are related to the critical behaviour of standard bond or site percolation models. Such approaches ignore totally the specific chemical features which allow the large variety of structures and properties exhibited by chemical networks. The ideal would be to have a model able to mimic realistically the chemical gelation process by taking into account the specificities of each chemical system investigated. But then a basic question arises : do the singularities change the universal behaviour ? This study aims to contribute to answer this question in the particular case of the gelation made by stepwise polymerization. In such systems, gelation may be avoided by introducing monofunctional monomers which are killing the cluster growth. This case is examined in this paper and corresponds to a site-bond percolation problem. Phase diagram is established and the different ways to cross the critical line of this diagram are investigated. The results outline the fact that topological constraints applied to the monomer connection may prevent the system from having a universal critical behaviour. Deleting these topological constraints, by giving a fictive mobility to the monomers, allows us to find again a universal behaviour for the system. This work justifies a posteriori experimental studies on the critical behaviour of the chemical gelation run with quenched systems. It also confirms that chemical stepwise gelation and standard percolation belong to the same universality class and illustrates how this model may be modified to be more realistic. De nombreux articles ou revues présentent la théorie de la percolation comme pertinente pour le problème de la gélification chimique. Mais la plupart de ces études concernent le comportement critique du modèle de percolation normal de site ou de lien. De tels modèles ignorent totalement les aspects chimiques spécifiques qui autorisent la grande variété de structures et de propriétés des réseaux macromoléculaires. L'idéal serait d'aboutir à un modèle capable de tenir compte des particularités de chaque système étudié. Mais une question de fond se pose alors : ces singularités changent-elles le comportement universel ? Cette étude tente de répondre à cette question dans le cas particulier de la gélification obtenue par polymérisation par étape. Une telle gélification peut-être évitée par l'introduction de monomères monofonctionnels tuant la croissance des amas. Ce cas qui est étudié dans cet article, correspond à un problème de percolation de site-lien. Le diagramme des phases est établi et différents chemins traversant la ligne critique de ce diagramme sont étudiés. Les résultats soulignent que les contraintes topologiques à la connexion des monomères peuvent conduire à un comportement critique non universel. La levée de ces contraintes en donnant une mobilité fictive aux monomères, redonne au système un comportement critique universel. Ce travail justifie a posteriori les études expérimentales du comportement critique de la gélification conduite sur des systèmes figés arrivés à complète réaction. Il confirme également l'appartenance de la gélification chimique par polymérisation par étape à la même classe d'universalité que le modèle de percolation normale et illustre la façon dont ce model peut être rendu plus réaliste.

Lairez, D.; Durand, D.; Emery, J. R.

1991-08-01

285

Dynamics of viscous penetration in percolation porous media  

NASA Astrophysics Data System (ADS)

We investigate the dynamics of viscous penetration in two-dimensional percolation networks at criticality for the case in which the ratio between the viscosities of displaced and injected fluids is very large. We report extensive numerical simulations that indicate that the scaling exponents for the breakthrough time distribution are the same as the previously reported values computed for the case of unit viscosity ratio. Our results are consistent with the possibility that viscous displacement through critical percolation networks constitutes a single universality class, independent of the viscosity ratio. We also find that the distributions of mass and breakthrough time of the invaded clusters have the same scaling form, but with different critical exponents.

Andrade, J. S.; Araújo, A. D.; Buldyrev, S. V.; Havlin, S.; Stanley, H. E.

2001-05-01

286

A rapid Percoll gradient procedure for preparation of synaptosomes.  

PubMed

Homogenization of fresh brain tissue in isotonic medium shears plasma membranes causing nerve terminals to become separated from their axons and postsynaptic connections. The nerve terminal membranes then reseal to form synaptosomes. The discontinuous Percoll gradient procedure described here is designed to isolate synaptosomes from brain homogenates in the minimum time to allow functional experiments to be performed. Synaptosomes are isolated using a medium-speed centrifuge, while maintaining isotonic conditions and minimizing mechanically damaging resuspension steps. This protocol has advantages over other procedures in terms of speed and by producing relatively homogeneous synaptosomes, minimizing the presence of synaptic and glial plasma membranes and extrasynaptosomal mitochondria. The purified synaptosomes are viable and take up and release neurotransmitters very efficiently. A typical yield of synaptosomes is between 2.5 and 4 mg of synaptosomal protein per gram rat brain. The procedure takes approximately 1 h from homogenization of the brain until collection of the synaptosomal suspension from the Percoll gradient. PMID:18927557

Dunkley, Peter R; Jarvie, Paula E; Robinson, Phillip J

2008-01-01

287

Mesoscale modeling of intergranular bubble percolation in nuclear fuels  

NASA Astrophysics Data System (ADS)

Phase-field simulations are used to examine the variability of intergranular fission gas bubble growth and percolation on uranium dioxide grain boundaries on a mesoscopic length scale. Three key parameters are systematically varied in this study: the contact angle (or dihedral angle) defining the bubble shape, the initial bubble density on the grain boundary plane, and the ratio of the gas diffusivity on the grain boundary versus the grain interiors. The simulation results agree well with previous experimental data obtained for bubble densities and average bubble areas during coalescence events. Interestingly, the rate of percolation is found to be highly variable, with a large dependency on the contact angle and the initial bubble density and little-to-no dependency on the grain boundary gas diffusivity.

Millett, Paul C.; Tonks, Michael; Biner, S. B.

2012-04-01

288

Piezoresistivity and conductance anisotropy of tunneling-percolating systems  

NASA Astrophysics Data System (ADS)

Percolating networks based on interparticle tunneling conduction are shown to yield a logarithmic divergent piezoresistive response close to the critical point as long as the electrical conductivity becomes nonuniversal. At the same time, the piezoresistivity or, equivalently, the conductivity anisotropy exponent ? remains universal also when the conductive exponent is not, suggesting a purely geometric origin of ?. We obtain these results by an exact solution of the piezoresistive problem on a Bethe lattice and by Monte Carlo calculations and finite-size scaling analysis on square lattices. We discuss our results in relation to the nature of transport for a variety of materials such as carbon-black polymer composites and RuO2-glass systems which show nonuniversal transport properties and coexistence between tunneling and percolating behaviors.

Grimaldi, C.; Maeder, T.; Ryser, P.; Strässler, S.

2003-01-01

289

Damage percolation during stretch flange forming of aluminum alloy sheet  

NASA Astrophysics Data System (ADS)

A multi-scale finite element (FE)-damage percolation model was employed to simulate stretch flange forming of aluminum alloys AA5182 and AA5754. Material softening and strain gradients were captured using a Gurson-based FE model. FE results were then fed into the so-called damage percolation code, from which the damage development was modelled within measured microstructures. The formability of the stretch flange samples was predicted based upon the onset of catastrophic failure triggered by profuse void coalescence within the measured second-phase particle field. Damage development is quantified in terms of crack and void areal fractions, and compared to metallographic results obtained from interrupted stretch flange specimens. Parametric study is conducted on the effect of void nucleation strain in the prediction of formability of stretch flanges to “calibrate” proper nucleation strains for both alloys.

Chen, Zengtao; Worswick, Michael J.; Keith Pilkey, A.; Lloyd, David J.

2005-12-01

290

Unusual percolation in simple small-world networks.  

PubMed

We present an exact solution of percolation in a generalized class of Watts-Strogatz graphs defined on a one-dimensional underlying lattice. We find a nonclassical critical point in the limit of the number of long-range bonds in the system going to zero, with a discontinuity in the percolation probability and a divergence in the mean finite-cluster size. We show that the critical behavior falls into one of three regimes depending on the proportion of occupied long-range to unoccupied nearest-neighbor bonds, with each regime being characterized by different critical exponents. The three regimes can be united by a single scaling function around the critical point. These results can be used to identify the number of long-range links necessary to secure connectivity in a communication or transportation chain. As an example, we can resolve the communication problem in a game of "telephone." PMID:19658569

Cohen, Reuven; Dawid, Daryush Jonathan; Kardar, Mehran; Bar-Yam, Yaneer

2009-06-23

291

Minimal spanning trees at the percolation threshold: A numerical calculation  

NASA Astrophysics Data System (ADS)

The fractal dimension of minimal spanning trees on percolation clusters is estimated for dimensions d up to d=5. A robust analysis technique is developed for correlated data, as seen in such trees. This should be a robust method suitable for analyzing a wide array of randomly generated fractal structures. The trees analyzed using these techniques are built using a combination of Prim's and Kruskal's algorithms for finding minimal spanning trees. This combination reduces memory usage and allows for simulation of larger systems than would otherwise be possible. The path length fractal dimension ds of MSTs on critical percolation clusters is found to be compatible with the predictions of the perturbation expansion developed by T. S. Jackson and N. Read [Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.81.021131 81, 021131 (2010)].

Sweeney, Sean M.; Middleton, A. Alan

2013-09-01

292

Percolation of diffusionally evolved two-phase systems.  

PubMed

Percolation thresholds and critical exponents for universal scaling laws are computed for microstructures that derive from phase-transformation processes in two dimensions. The computed percolation threshold for nucleation and growth processes, p(c)?0.6612, is similar to those obtained by random placement of disks and greater than that of spinodal decomposition, p(c)?0.4987. Three critical exponents for scaling behavior were computed and do not differ significantly from universal values. The time evolution of a characteristic microstructural length was also computed: For spinodal decomposition, this length grows according to a power law after a short incubation period; for nucleation and growth, there are several transitions in the nature of the growth law. We speculate that the transitions in nucleation and growth derive from competing effects of coalescence at short times and then subsequent coarsening. Short-range order is present, but different, for both classes of microstructural evolution. PMID:21405830

Brunini, Victor E; Schuh, Christopher A; Carter, W Craig

2011-02-28

293

Fire spread and percolation in polydisperse compartment structures  

NASA Astrophysics Data System (ADS)

In this paper, we employ a cellular automata and percolation analysis to model fire spread in polydisperse amorphous massively multi-compartmented structures (e.g. naval vessels, high-rise buildings, warehouses, or nuclear plants). Various shapes and sizes of compartments are considered. Each compartment is composed of nc equal-size cells. It is found that increasing nc increases fingering and lacunarities of fire patterns, and subsequently front roughness. However, this also increases the probability of fire propagation throughout the system as the percolation threshold presents a power-law decrease with nc -1 for small values of nc. For large polydisperse compartments, the propagation/non propagation transition seems to be size-independent. A special emphasis is put on the dynamics of fire propagation. Further study is needed to evaluate network properties that should help in developing better strategies to reduce fire consequences.

Zekri, N.; Zekri, L.; Lallemand, C.; Pizzo, Y.; Kaiss, A.; Clerc, J.-P.; Porterie, B.

2012-11-01

294

Percolation and fire spread with power-law flame radiations  

NASA Astrophysics Data System (ADS)

Percolation and non-equilibrium front propagation in a two-dimensional network modeling wildfire spread is studied. The model includes a deterministic long-range interaction induced by flame radiation. It includes also a time weighting process due to the flame residence time and the activation (ignition) energy of the exposed combustible. For the square power decreasing radiation interaction, three weight-dependent regimes were previously found; a dynamical, a static, and a non-propagative regime (Zekri N. et al. Phys. Lett. A, 376 (2012) 2522). The weight effect on the percolation threshold is found here independent of the deterministic interaction. Using the Family-Vicsek scaling ansatz, the front dynamical exponents belong to the Edwards-Wilkinson model universality class at the saturation of the dynamical regime. They are weight dependent beyond saturation.

Khelloufi, K.; Baara, Y.; Zekri, N.

2013-07-01

295

Mesoscale modeling of intergranular bubble percolation in nuclear fuels  

SciTech Connect

Phase-field simulations are used to examine the variability of intergranular fission gas bubble growth and percolation on uranium dioxide grain boundaries on a mesoscopic length scale. Three key parameters are systematically varied in this study: the contact angle (or dihedral angle) defining the bubble shape, the initial bubble density on the grain boundary plane, and the ratio of the gas diffusivity on the grain boundary versus the grain interiors. The simulation results agree well with previous experimental data obtained for bubble densities and average bubble areas during coalescence events. Interestingly, the rate of percolation is found to be highly variable, with a large dependency on the contact angle and the initial bubble density and little-to-no dependency on the grain boundary gas diffusivity.

Millett, Paul C.; Tonks, Michael; Biner, S. B. [Nuclear Fuels and Materials, Idaho National Laboratory, Idaho Falls, Idaho 83415 (United States)

2012-04-15

296

Percolation, Bose-Einstein condensation, and string proliferation.  

PubMed

The close analogy between cluster percolation and string proliferation in the context of critical phenomena is studied. Like clusters in percolation theory, closed strings, which can be either finite-temperature worldlines or topological line defects, are described by a distribution parametrized by only two exponents. On approaching the critical point, the string tension vanishes and the loops proliferate, thereby signalling the onset of Bose-Einstein condensation (in the case of worldlines) or the disordering of the ordered state (in the case of vortices). The ideal Bose gas with modified energy spectrum is used as a stepping stone to derive general expressions for the critical exponents in terms of the two exponents parametrizing the loop distribution near criticality. PMID:11308550

Schakel, A M

2001-01-25

297

Double site-bond percolation model for biomaterial implants  

NASA Astrophysics Data System (ADS)

We present a double site-bond percolation model to account, on the one hand, for the vascularization and/or resorption of biomaterial implant in bones, and on the other hand, for its mechanical continuity. The transformation of the implant into osseous material, and the dynamical formation/destruction of this osseous material is accounted for by creation and destruction of links and sites in two, entangled, networks. We identify the relevant parameters to describe the implant and its evolution, and separate their biological or chemical origin from their physical one. We classify the various phenomena in the two regimes, percolating or nonpercolating, of the networks. We present first numerical results in two dimensions.

Mely, H.; Mathiot, J.-F.

2012-03-01

298

Largest cluster in percolation: Implications for fragmentation studies  

SciTech Connect

The probability distribution of the largest cluster size is studied within a three-dimensional bond percolation model on small lattices. Cumulants of the distribution exhibit distinct features near the percolation transition (pseudocritical point), providing a method for its identification. The location of the critical point in the continuous limit can be estimated without variation of the system size. This method is remarkably insensitive to finite-size effects and may be applied even for a very small system. The possibility of using various measurable quantities for sorting events makes the procedure useful in studying clusterization phenomena, in particular nuclear multifragmentation. Finite-size scaling and {delta}-scaling relations are examined. The role of surface effects is evaluated by a comparison of results for free and periodic boundary conditions.

Brzychczyk, Janusz [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Cracow (Poland)

2006-02-15

299

Percolation model of polydisperse composite solid propellant combustion  

SciTech Connect

The composition dependence of the burn rate of polydisperse composite solid propellants is predicted by analyzing the least-time path of the burn front through the propellant. The predicted burn rate is the average burn rate along the least-time path divided by the tortuosity, or arc length per streamwise interval, of the least-time path. The tortuosity analysis is based on percolation theory. Aspects of percolation theory which are pertinent to the analysis are introduced in a self-contained Appendix. The model, which contains four adjustable parameters, is validated by comparison to measured burn rates for a suite of polydisperse ammonium perchlorate composites. The data correlations are found to be significantly better than for a three-parameter version of the model which omits tortuosity considerations.

Kerstein, A.R.

1987-07-01

300

Fracture In Disordered Media: Nucleated, Critical or Percolative?  

NASA Astrophysics Data System (ADS)

Fracture is often considered to be an abrupt transition and is modeled by nucleation theory. However, the precursor events leading to macroscopic failure display scaling behavior and are understood in terms of critical phenomena. Further, the universal roughness properties of fracture surfaces have been explained by modeling fracture as a percolative process. We attempt to unify these disparate descriptions of fracture in one comprehensive theory. We study the random fuse network as a typical model of disordered brittle media. We show that in this model fracture can be nucleated, critical or percolative depending on the behavior of the tail of the distribution of fuse strengths. We explore the phase diagram by using numerical simulations as well as theoretical arguments.

Shekhawat, Ashivni; Zapperi, Stefano; Sethna, James

2012-02-01

301

Quantum percolation in cuprate high-temperature superconductors  

PubMed Central

Although it is now generally acknowledged that electron–phonon interactions cause cuprate superconductivity with Tc values ?100 K, the complexities of atomic arrangements in these marginally stable multilayer materials have frustrated both experimental analysis and theoretical modeling of the remarkably rich data obtained both by angle-resolved photoemission (ARPES) and high-resolution, large-area scanning tunneling microscopy (STM). Here, we analyze the theoretical background in terms of our original (1989) model of dopant-assisted quantum percolation (DAQP), as developed further in some two dozen articles, and apply these ideas to recent STM data. We conclude that despite all of the many difficulties, with improved data analysis it may yet be possible to identify quantum percolative paths.

Phillips, J. C.

2008-01-01

302

Quantum percolation in cuprate high-temperature superconductors.  

PubMed

Although it is now generally acknowledged that electron-phonon interactions cause cuprate superconductivity with T(c) values approximately 100 K, the complexities of atomic arrangements in these marginally stable multilayer materials have frustrated both experimental analysis and theoretical modeling of the remarkably rich data obtained both by angle-resolved photoemission (ARPES) and high-resolution, large-area scanning tunneling microscopy (STM). Here, we analyze the theoretical background in terms of our original (1989) model of dopant-assisted quantum percolation (DAQP), as developed further in some two dozen articles, and apply these ideas to recent STM data. We conclude that despite all of the many difficulties, with improved data analysis it may yet be possible to identify quantum percolative paths. PMID:18626024

Phillips, J C

2008-07-14

303

Chiral Potts Models, Friendly Walkers and Directed Percolation Problem  

Microsoft Academic Search

The lambda-state chiral Potts model on a finite directed latticeis defined, whose partition function under a certain boundarycondition becomes the directed percolation (DP)probability for a finite lattice in the lambda-->1 limit.We also introduce the system of m friendly walkers of Ltime-steps and prove that its generating functionof trajectories is equal to the partition function of the lambda-state chiral Potts model

Tomoko Tsuchiya; Makoto Katori

1998-01-01

304

Network Robustness and Fragility: Percolation on Random Graphs  

Microsoft Academic Search

Recent work on the internet, social networks, and the power grid has\\u000aaddressed the resilience of these networks to either random or targeted\\u000adeletion of network nodes. Such deletions include, for example, the failure of\\u000ainternet routers or power transmission lines. Percolation models on random\\u000agraphs provide a simple representation of this process, but have typically been\\u000alimited to graphs

Duncan S. Callaway; M. E. J. Newman; Steven H. Strogatz; Duncan J. Watts

2000-01-01

305

Percolation model of polydisperse composite solid propellant combustion  

Microsoft Academic Search

The composition dependence of the burn rate of polydisperse composite solid propellants is predicted by analyzing the least-time path of the burn front through the propellant. The predicted burn rate is the average burn rate along the least-time path divided by the tortuosity, or arc length per streamwise interval, of the least-time path. The tortuosity analysis is based on percolation

A KERSTEIN

1987-01-01

306

Restricted exclusion processes without particle conservation flows to directed percolation  

NASA Astrophysics Data System (ADS)

Absorbing phase transitions in restricted exclusion processes are characterized by simple integer exponents. We show that this critical behaviour flows to the directed percolation (DP) universality class when particle conservation is broken suitably. The same transition, when studied using the average density as the controlling parameter, yields critical exponents quite different from DP; we argue that these exponents are actually related to DP by a scaling factor 1/?DP. These conclusions also apply to conserved lattice gas in one dimension.

Basu, Urna; Mohanty, P. K.

2012-09-01

307

Geodesics in two-dimensional first-passage percolation  

Microsoft Academic Search

We consider standard first-passage percolation on $\\\\mathbb{Z}^2$.\\u000aGeodesics are nearest-neighbor paths in $\\\\mathbb{Z}^2$, each of whose segments\\u000ais time-minimizing. We prove part of the conjecture that doubly infinite\\u000ageodesics do not exist. Our main tool is a result of independent interest about\\u000athe coalescing of semi-infinite geodesics.

Cristina Licea; Charles M. Newman

1996-01-01

308

First-passage percolation, network flows and electrical resistances  

Microsoft Academic Search

We show that the first-passage times of first-passage percolation on ?2 are such that P(?0nP(?0n>n(?+?)) decay geometrically as n??, where ? may represent any of the four usual first-passage-time processes. The former estimate requires no moment condition on the time coordinates, but there exists a geometrically-decaying estimate for the latter quantity if and only if the time coordinate distribution has

Geoffrey Grimmett; Harry Kesten

1984-01-01

309

The time constant and critical probabilities in percolation models  

Microsoft Academic Search

We consider a first-passage percolation model on a Delaunay triangulation of\\u000athe plane. In this model each edge is independently equipped with a nonnegative\\u000arandom variable, with distribution function F, which is interpreted as the time\\u000ait takes to traverse the edge. Vahidi-Asl and Wierman have shown that, under a\\u000asuitable moment condition on F, the minimum time taken to

Leandro P. R. Pimentel

2004-01-01

310

Percolation network modeling of electrical properties of reservoir rock  

Microsoft Academic Search

Based on the percolation network model characterizing reservoir rock’s pore structure and fluid characteristics, this paper\\u000a qualitatively studies the effects of pore size, pore shape, pore connectivity, and the amount of micropores on the I-S\\u000a \\u000a w\\u000a curve using numerical modeling. The effects of formation water salinity on the electrical resistivity of the rock are discussed.\\u000a Then the relative magnitudes of

Kewen Wang; Jianmeng Sun; Jiteng Guan; Yuanda Su

2005-01-01

311

Conductivity percolation in carbon–carbon supercapacitor electrodes  

Microsoft Academic Search

Composite electrodes which comprise a non-conductive activated carbon of large surface area (1420m2g?1) and a conductive carbon black (CB) of small surface area (220m2g?1) have been prepared and studied for their capacitive properties in aqueous KOH and Na2SO4 electrolytes. For either electrolyte, maximum capacitance exists at the composition believed to correspond to the percolation threshold for CB, the conductive phase.

N. L Wu; S. Y Wang

2002-01-01

312

Rigidity percolation and molecular clustering in network glasses  

Microsoft Academic Search

129I Mössbauer spectra of g-GexSe1-x alloys display a local maximum in the site-intensity ratio IB\\/IA(x) at the critical composition x=xc=0.23+\\/-0.02. This observation is consistent with the realization of mechanical critical behavior in a covalent network glass recently predicted by Phillips and Thorpe. We identify xc with the onset of percolation of a specific molecular fragment based on the layered form

W. Bresser; P. Boolchand; P. Suranyi

1986-01-01

313

A sharper threshold for bootstrap percolation in two dimensions  

Microsoft Academic Search

Two-dimensional bootstrap percolation is a cellular automaton in which sites become ‘infected’ by contact with two or more\\u000a already infected nearest neighbours. We consider these dynamics, which can be interpreted as a monotone version of the Ising\\u000a model, on an n × n square, with sites initially infected independently with probability p. The critical probability p\\u000a \\u000a c\\u000a is the smallest

Janko Gravner; Alexander E. Holroyd; Robert Morris

2010-01-01

314

Estimates of deep percolation beneath cotton in the Macquarie Valley  

Microsoft Academic Search

Expansion of flood irrigation in the Lower Macquarie Valley of New South Wales, Australia, has been suggested as a major\\u000a cause of increased groundwater recharge. The aim of this study was to estimate deep percolation under irrigation on two soils\\u000a in the valley, in order to infer groundwater recharge. Three methods were used; water balance, Darcian flux calculations and\\u000a chloride

Tracy M. Willis; A. Scott Black; Wayne S. Meyer

1997-01-01

315

Traveling time and traveling length in critical percolation clusters  

Microsoft Academic Search

We study traveling time and traveling length for tracer dispersion in two-dimensional bond percolation, modeling flow by tracer particles driven by a pressure difference between two points separated by Euclidean distance r. We find that the minimal traveling time tmin scales as tmin~r1.33, which is different from the scaling of the most probable traveling time, t~~r1.64. We also calculate the

Youngki Lee; José S. Andrade Jr.; Sergey V. Buldyrev; Nikolay V. Dokholyan; Shlomo Havlin; Peter R. King; Gerald Paul; H. Eugene Stanley

1999-01-01

316

Percolation for a model of statistically inhomogeneous random media  

SciTech Connect

We study clustering and percolation phenomena for a model of statistically inhomogeneous two-phase random media, including functionally graded materials. This model consists of inhomogeneous fully penetrable (Poisson distributed) disks and can be constructed for any specified variation of volume fraction. We quantify the transition zone in the model, defined by the frontier of the cluster of disks which are connected to the disk-covered portion of the model, by defining the coastline function and correlation functions for the coastline. We find that the behavior of these functions becomes largely independent of the specific choice of grade in volume fraction as the separation of length scales becomes large. We also show that the correlation function behaves in a manner similar to that of fractal Brownian motion. Finally, we study fractal characteristics of the frontier itself and compare to similar properties for two-dimensional percolation on a lattice. In particular, we show that the average location of the frontier appears to be related to the percolation threshold for homogeneous fully penetrable disks. {copyright} {ital 1999 American Institute of Physics.}

Quintanilla, J. [Department of Mathematics, University of North Texas, Denton, Texas 76203 (United States); Torquato, S. [School of Mathematics, Institute for Advanced Study, Princeton, New Jersey 08540 (United States)

1999-10-01

317

Can percolation theory be applied to the stock market?  

NASA Astrophysics Data System (ADS)

The fluctuations of the stock market - the price changes per unit time - seem to deviate from Gaussians for short time steps. Power laws, exponentials, and multifractal descriptions have been offered to explain this short-time behavior. Microscopic models dealing with the decisions of single traders on the market have tried to reproduce this behavior. Possibly the simplest of these models is the herding approach of Cont and Bouchaud. Here a total of Nt traders cluster together randomly as in percolation theory. Each cluster randomly decides by buy or sell an amount proportional to its size, or not to trade. Monte Carlo simulations in two to seven dimensions at the percolation threshold depend on the number N of clusters trading within one time step. For N 1, the changes follow a power law; for 1 N Nt they are bell-shaped with power-law tails; for N Nt they crossover to a Gaussian. The correlations in the absolute value of the change decay slowly with time. Thus percolation not only describes the origin of life or the boiling of your breakfast egg, but also explains why we are not rich.

Stauffer, Dietrich

1998-11-01

318

Fractional scaling of quantum walks on percolation lattices  

NASA Astrophysics Data System (ADS)

Quantum walks can be used to model processes such as transport in spin chains and bio-molecules. The enhanced spreading and mixing properties of quantum walks compared with their classical counterparts have been well-studied on regular structures and also shown to be sensitive to defects and imperfections. Using numerical simulation, we study the spreading properties of quantum walks on percolation lattices for both bond and site percolation. The randomly missing edges or sites provide a controlled amount of disorder in the regular Cartesian lattice. In one dimension (the line) we introduce a simple model of quantum tunneling to allow the walk to proceed past the missing edges or sites. This allows the quantum walk to spread faster than a classical random walk for short times, but at longer times the disorder localises the quantum walk. In two dimensions, we observe fractional scaling of the spreading with the number of steps of the walk. For percolation above the 85% level, we obtain faster spreading than classical random walks on the full lattice.

Kendon, Viv; Leung, Godfrey; Bailey, Joe; Knott, Paul

2011-03-01

319

Coalescence of Pb and Sn nanoclusters in percolating films  

NASA Astrophysics Data System (ADS)

The effects of coalescence on Pb and Sn nanoclusters are investigated. Percolating films of Pb and Sn nanoclusters (size ~7 nm in diameter) were deposited on Si3N4 passivated Si substrates with thermally evaporated NiCr/Au electrodes, using a UHV compatible cluster deposition system. The conductance of the percolating films was measured during and after the deposition process. A large increase in conductance is observed at the percolation threshold, when a conducting path is formed between the electrodes, followed by a further increase due to the generation of new paths as more clusters land. It was found that the conductance of these films keeps on increasing even after the end of the deposition process. This increase in conductance can be explained in terms of coalescence of connecting clusters. The increase in conductance follows a power law G = a(t-t1)b, where G is the conductance of the film and t is the time elapsed after the end of deposition. The value of the power law exponent b was found to be between 0.01 to 0.03 for Pb and Sn.

Sattar, A.; Convers, P. Y.; Brown, S. A.

2009-07-01

320

Continuum Percolation Theory for Water Retention and Hydraulic Conductivity of Fractal Soils: Estimation of the Critical Volume Fraction for Percolation and Extension to Non-Equilibrium  

Microsoft Academic Search

Systematic experimental deviations from theoretical predictions derived for water retention characteristics of fractal porous media have previously been interpreted in terms of continuum percolation theory (at low moisture contents, below the critical volume fraction of water, ?c, capillary flow ceases). In other work, continuum percolation theory was applied to find the hydraulic conductivity as a function of saturation for saturations

AG Hunt

321

Scrap tire recycling  

SciTech Connect

As the automobile tire technology has grown and met the need for safer and more durable tires, stronger reinforcement and more chemically resistant rubber compounds have made recycling tires more difficult. In an effort to resolve this problem, techniques and equipment were developed to grind tires into small pieces, and new markets were sought to utilize the crumb rubber product streams from ground tires. Industrial combustion processes were modified to accept scrap tires as fuel. These efforts have been beneficial, steadily increasing the percentage of scrap tires recycled to about 10% in 1985, and reaching 72% in 1995. By the end of 1997, fully 100% of tires generated in the U.S. are expected to be recycled.

Lula, J.W.; Bohnert, G.W.

1997-03-01

322

Effect of phosphate on lead removal during a copper recycling process from wastes using ammoniacal chloride solution  

Microsoft Academic Search

Techniques for the removal of lead have been studied in order to develop a hydrometallurgical copper recycling process consisting of copper leaching from wastes using an ammoniacal chloride solution and subsequent copper electrowinning. The solubility of Pb(II) in the ammoniacal chloride solution increased with ammonia concentration; this was attributable to the formation of a lead ammine complex. The lead dissolution

T. Oishi; M. Yaguchi; K. Koyama; M. Tanaka; J.-C. Lee

2008-01-01

323

Ammonia abundances in four comets  

NASA Astrophysics Data System (ADS)

NH2 emission band strengths were measured in four comets and the NH2 column densities were determined in order to measure the ammonia content of the comets. The mean ammonia/water abundance ratio derived for the four comets is found to be 0.13 + or - 0.06 percent, with no significant variation among the comets. The uniformity of this abundance attests to a remarkable degree of chemical homogeneity over large scales in the comet-forming region of the primordial solar nebula, and contrasts with the CO abundance variations found previously in comets. The N2 and NH3 abundances indicate a condensation temperature in the range 20-160 K, consistent with virtually all comet formation hypotheses.

Wyckoff, S.; Tegler, S. C.; Engel, L.

1991-02-01

324

Recycling Opportunities for Neighbourhoods and Communities.  

National Technical Information Service (NTIS)

This paper discusses recycling paper, glass, plastics, and metals. It presents a community technology approach to recycling, and reviews present efforts in repair and renovation, reuse, and recycling. A final chapter on the appropriateness of recycling te...

C. Thomas

1981-01-01

325

OTEC ammonia turbine design study  

Microsoft Academic Search

The design of an ammonia turbine generator for OTEC which uses high-performance state-of-the-art hardware is presented. Turbine aerodynamic performance was calculated using a modification of the Ainley and Mathieson (1951) pressure loss method to determine thermodynamic conditions at various locations within the turbine for a given geometry on the basis of mass flow continuity. It is found that the optimum

C. H. Kostors; S. P. Vincent

1979-01-01

326

Dipole hyperpolarizability surfaces of ammonia  

Microsoft Academic Search

Full-dimensional first dipole hyperpolarizability surfaces of NH3 are determined by means of multiconfigurational quadratic response theory. On the basis of the two-dimensional, symmetric stretching vs inversion, hyperpolarizability functions, and approximate vibrational wave functions, effective inversional hyperpolarizability moments are evaluated for the D3h ammonia isotopomers. The calculations have revealed their strong vibrational and frequency dependence. A fairly close reproduction of the

Vladimir Spirko; Yi Luo

1993-01-01

327

Botswana's environmental policy on recycling  

Microsoft Academic Search

Recycling operations have become one of the primary strategies for waste management, worldwide. Especially, recycling operations are viewed as among the most effective techniques for reducing the amount of municipal solid waste disposed at landfill sites. Botswana's environmental policy on recycling stipulates, among others, that all waste management authorities should provide information on the classification and quantities of controlled waste

C. Ketlogetswe; T. H. Mothudi

2005-01-01

328

Study on electronics recycling process  

Microsoft Academic Search

The discarding of electronics is a growing problem around the world. This paper first analyzes the possible limitations in current electronics recycling models and methods through the review of the literature, and this paper then presents a study of the complete electronics recycling process based on electronics features. The five main stages in the recycling process are described: collection, product

Weiwei Chen; Rui Kang; Diganta Das; Michael Pecht

2009-01-01

329

Recycling incineration: Evaluating the choices  

Microsoft Academic Search

Conflicts between proponents of municipal solid waste incineration and advocates of recycling have escalated with efforts to reduce the volume of waste that ends up in landfills. Central to this debate is competition for materials that are both combustible and recyclable. Environmental and economic concerns also play a major role. This book, produced by the Environmental Defense Fund, compares recycling

R. A. Denison; J. Ruston

1993-01-01

330

Minerals Yearbook, 1992: Materials Recycling.  

National Technical Information Service (NTIS)

A large variety of materials are recycled by different sectors of our society. The materials recycling that is mainly addressed in this writing is from waste that is generated after manufacturing and use. Included is recycling that is generally more obvio...

A. O. Tanner

1992-01-01

331

Recycling Behavior: A Multidimensional Approach  

ERIC Educational Resources Information Center

|This work centers on the study of consumer recycling roles to examine the sociodemographic and psychographic profile of the distribution of recycling tasks and roles within the household. With this aim in mind, an empirical work was carried out, the results of which suggest that recycling behavior is multidimensional and comprises the undertaking…

Meneses, Gonzalo Diaz; Palacio, Asuncion Beerli

2005-01-01

332

Public participation in plastics recycling schemes  

Microsoft Academic Search

Without public contributions, recycling from domestic waste would not be possible. In order to support recycling projects it is important to try to understand who recycles, how they recycle, and why they recycle. This paper presents the results of a structured survey of 500 members of the public served by schemes to collect plastics waste for recycling. Data were gathered

Seonaidh McDonald; Rob Ball

1998-01-01

333

THE OPTIMAL LOCATION OF TWO RECYCLING CENTERS  

Microsoft Academic Search

Suppose a municipality optimally locates two recycling\\/sorting centers to minimize the sum of the transportation costs from i) households to the recycling centers and ii) recycling centers to the landfill. Assume that all household waste is taken to a recycling center, sorted, and the non-recyclables are subsequently transported to the landfill. The landfill location and the proportion of waste recycled

Jannett Highfill; Michael McAsey; Libin Mou

334

Fuels from Recycling Systems  

ERIC Educational Resources Information Center

|Three systems, operating at sufficient scale, produce fuels that may be alternatives to oil and gas. These three recycling systems are: Black Clawson Fiberclaim, Franklin, Ohio; Union Carbide, South Charleston, West Virginia; and Union Electric, St. Louis, Missouri. These produce a wet fuel, a pyrolytic gas, and a dry fuel, respectively. (BT)|

Tillman, David A.

1975-01-01

335

Recycling in a Megacity  

Microsoft Academic Search

In the aftermath of the 9\\/11 disaster, Mayor Bloomberg of New York City unveiled an aggressive budget plan that included the temporary suspension of glass and plastics recycling. This was considered by many to be anti-environmental, but the results of this study show that for lack of markets, even at zero or negative prices, nearly 90% of the plastic and

Nickolas J. Themelis; Claire E. Todd

2004-01-01

336

Recycling Study Guide.  

ERIC Educational Resources Information Center

This study guide was designed to help teachers and students understand the problems surrounding solid wastes. It includes an overview of solid waste and recycling, a glossary, suggested activities and a list of resource publications, audiovisual materials and organizations. There are 19 activity suggestions included in this guide designed for use…

Hallowell, Anne; And Others

337

Designing for recycling  

SciTech Connect

The instrument panel (IP) with its variety of materials is one of the most difficult parts of the automobile to recycle. Selection of materials to minimize material count and maximize separability is critical to cost-effective IP recycling. Choices of assembly and disassembly techniques also should consider recycling. Current practices for recycling automobiles focus on the recovery of usable parts and metals with other materials becoming landfill. New design practices or significant developments in recovery technology must occur to reduce the volume of landfill materials. Design practices will be most effective if they allow cost-effective recovery of desired materials from the plastic components before shredding. Recovery technology continues to improve, but most parts are shredded with the car and land-filled as automotive shredder residue (ASR). Shredding followed by mechanical separation conceptually is the most cost-effective option, but the typical instrument panel contains six or more plastic materials. This makes separation difficult and expensive to get acceptable material yields and purity.

NONE

1997-08-01

338

Computer Recycling Farm USA  

USGS Multimedia Gallery

USGS conducted a study of plastic pollution at this rural US site in the Midwest.  The recycler was receiving computers from companies at a rate which greatly exceeded the capacity of the operation.  Approximately 50,000 computers remained outdoors on 15 acres for nearly a decade.  The site has sinc...

2010-08-13

339

Reduce, Reuse, and Recycle  

NSDL National Science Digital Library

Boys and girls, grab your nose-plugs because today we are going to be digging through some garbage! We use a lot of garbage; the average American throws away nearly four pounds everyday. That\\'s a whopping 1,600 pounds a year! That means that every year, EACH one of you toss enough trash to equal the weight of all the students in our class...COMBINED! That\\'s a lot of garbage. Our world is big, but you might not have realized just how small it really is when it comes to holding all this trash. Would you want garbage in your backyard? Your playground? The park? There\\'s only so many places to store our waste. So, what do we do? We RECYCLE! What Does It Mean To Recycle? Recycling is taking things we use and would normally through into the trash can and putting them in a separate container. Instead of going to the dump, it goes to a recycling plant. Things like paper, newspaper, cardboard, plastic, glass, and aluminum are all products ...

Nicole

2008-11-19

340

DRAINAGE WATER RECYCLING  

Technology Transfer Automated Retrieval System (TEKTRAN)

Researchers in Ohio have developed a drainage water recycling approach that is called Wetland, Reservoir, SubIrrigation System, or WRSIS. This system directs surface runoff and subsurface drainage water to a constructed wetland where there is opportunity for some sediment and nutrient removal from t...

341

Recycling and Restoration  

NSDL National Science Digital Library

This video explains how Bernheim Arboretum and Research Forest near Louisville, Kentucky used recycled cypress from pickle vats to build its visitor center and then “paid back” nature by creating a cypress-tupelo swamp at one end of a lake on the park grounds.

Ket

2011-01-11

342

Recycled Insect Models  

ERIC Educational Resources Information Center

|This article presents an engaging activity in which high school students use a dichotomous key to guide the creation and classification of model insects from recycled plastic lids and containers. Besides teaching the use of a dichotomous key and the effect of evolutionary descent upon groupings of organisms, this activity focuses on an…

Rule, Audrey C.; Meyer, Mary Ann

2007-01-01

343

WRAMS, sustainable water recycling  

Microsoft Academic Search

The Water Reclamation and Management Scheme (WRAMS) at Sydney Olympic Park was built as part of the Olympic Games in 2000. The Scheme was designed to treat raw domestic sewage into recycled water which is then sold back to consumers. The main elements of WRAMS are a water reclamation plant, a water treatment plant, storm water collection, clean water storage

H. Chapman

2006-01-01

344

Measuring Recycling Guidance Glossary  

EPA Pesticide Factsheets

PVC:  (Polyvinyl Chloride) Refers to the family of plastic copolymers, also known as vinyl. PVC is used to make products such as pipes, bottles, upholstery, and automotive parts. (U.S. EPA, 1995c)   From Measuring Recycling Guidance Glossary  -  Search all glossaries for terms containing "PVC"

2011-04-14

345

Thermodynamic Properties of Aqueous Solution of Ammonia  

NASA Astrophysics Data System (ADS)

Present status on the thermodynamic properties of experimental data and their correlations of both ammonia and aqueous solution of ammonia was introduced in this paper. The aqueous solution of ammonia is used for not only a working fluid in absorption refrigerator cycles but also working fluids in bottoming cycles of steam power plants and other heat recovering systems. Therefore, the thermodynamic properties of this substance are required in a wide range of temperatures, pressures and compositions. The experimental results of pVTx properties for ammonia and aqueous solution of ammonia and their comparisons with a formulation by Tillner-Roth and Friend1) were critically surveyed. The “Guideline on the IAPWS Formulation 2000 for the Thermodynamic Properties of Ammonia-Water Mixtures”, correlated by Tillner-Roth and Friend1), was approved on September, 2001, by the International Association for the Properties of Water and Steam (IAPWS) 2).

Kitamura, Hiroshi; Oguchi, Kosei

346

Phospholipid fatty acid composition of microbiota in the percolating water from a rice paddy microcosm  

Microsoft Academic Search

The microbiota in the percolating water from the plow layer soil in paddy fields was studied based on the composition of phospholipid fatty acids (PLFAs) in a pot experiment. The mean concentrations of PLFAs in the percolating water were 17±5 and 11±4 µg L in the planted and non-planted pots, respectively. The dominant PLFAs in the percolating water were 16:

Makoto Kimura; Hirokazu Kishi; Akiko Okabe; Nagamitsu Maie

2001-01-01

347

Estimation of percolation flux from borehole temperature data at Yucca Mountain, Nevada  

Microsoft Academic Search

Temperature data from the unsaturated zone (UZ) at Yucca Mountain are analyzed to estimate percolation-flux rates and overall heat flux. A multilayer, one-dimensional analytical solution is presented for determining percolation flux from temperature data. Case studies have shown that the analytical solution agrees very well with results from the numerical code, TOUGH2. The results of the analysis yield percolation fluxes

G. S. Bodvarsson; E. Kwicklis; C. Shan; Y. S. Wu

2003-01-01

348

Asymptotic shape for the chemical distance and first-passage percolation on the infinite Bernoulli cluster  

Microsoft Academic Search

The aim of this paper is to extend the well-known asymptotic shape result for first-passage percolation on Zd to first-passage percolation on a random environment given by the infinite cluster of a supercritical Bernoulli percolation model. We prove the convergence of the renormalized set of wet vertices to a deterministic shape that does not depend on the realization of the

Olivier Garet

2004-01-01

349

Transfer-matrix approach to the one-dimensional percolation problem  

Microsoft Academic Search

The transfer-matrix method is used to find the exact phase diagrams and the correlation length exponents v for the one-dimensional site, bond and site-bond percolation problems with bonds connecting the Lth-nearest neighbours (L up to 3). For the site percolation, the authors' results agree with the exact result obtained from the generating function method, v=L, while for the bond percolation

Zhao-qing Zhang; Jue-lian Shen

1982-01-01

350

Reversible intercalation of ammonia molecules into a layered double hydroxide structure without exchanging nitrate counter-ions  

SciTech Connect

A zinc/aluminum LDH was precipitated with recycled ammonia from a chemical vapor deposition reaction. The LDH presented a crystalline phase with basal distance of 8.9 A, typical for nitrate-containing LDHs, and another phase with a basal distance of 13.9 A. Thermal treatment at 150 {sup o}C eliminated the phase with the bigger basal distance leaving only the anhydrous nitrate-intercalated LDH structure with 8.9 A. Intense N-H stretching modes in the FTIR spectra suggested that the expansion was due to intercalation of ammonia in the form of [NH{sub 4}(NH{sub 3}){sub n}]{sup +} species. When additional samples were precipitated with pure ammonia, the conventional LDH nitrate structure was obtained (8.9 A basal distance) at pH=7, as well as a pure crystalline phase with 13.9 A basal distance at pH=10 due to ammonia intercalation that can be removed by heating at 150 {sup o}C or by stirring in acetone, confirming a unusual sensu stricto intercalation process into a LDH without exchanging nitrate ions. - Graphical abstract: LDH-nitrate precipitated with ammonia expands the interlayer space if ammonia is bubbled up to pH 10. The basal distance decreased when the compound was heated at 150 {sup o}C or stirred in acetone. Nitrate ions are not exchanged.

Carbajal Arizaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.m [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Km. 107 Carretera Tijuana-Ensenada, Apdo. Postal 14, C.P. 22800. Ensenada, Baja California (Mexico); Wypych, Fernando [CEPESQ-Research Centre of Applied Chemistry, Department of Chemistry, Federal University of Parana, P.O. Box 19081, 81531-980 Curitiba, PR (Brazil); Castillon Barraza, Felipe; Contreras Lopez, Oscar Edel [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Km. 107 Carretera Tijuana-Ensenada, Apdo. Postal 14, C.P. 22800. Ensenada, Baja California (Mexico)

2010-10-15

351

Ammonia Assimilation by Rhizobium Cultures and Bacteroids  

Microsoft Academic Search

SUMMARY The enzymes involved in the assimilation of ammonia by free-living cultures of Rhizobium spp. are glutamine synthetase (EC. 6.3. I. 2), glutamate synthase (L- glutamine : a-oxoglutarate amino transferase) and glutamate dehydrogenase (EC I.4. I.4). Under conditions of ammonia or nitrate limitation in a chemostat the assimilation of ammonia by cultures of R. leguminosarum, R. trifolii and R. japonicum

C. M. BROWN; M. J. DILWORTH

1975-01-01

352

Quality Improvement for Ammonia Emission Inventory  

Microsoft Academic Search

Ammonia gas reactions in the atmosphere are a significant source of PM2.5. Due to the increasing concentration of PM2.5 in atmosphere, the need for improved ammonia emission inventories has become an increasingly important air quality issue. A comparison is shown of ammonia inventory data from CMU (Carnegie Mellon University) based on the years 1996 and 1997, and NET99 (EPA's National

Joshua Fu; Yunhee Kim; Wayne Davis; Terry Miller

353

Adsorption of ammonia on multilayer iron phthalocyanine  

SciTech Connect

The adsorption of ammonia on multilayers of well-ordered, flat-lying iron phthalocyanine (FePc) molecules on a Au(111) support was investigated by x-ray photoelectron spectroscopy. We find that the electron-donating ammonia molecules coordinate to the metal centers of iron phthlalocyanine. The coordination of ammonia induces changes of the electronic structure of the iron phthalocyanine layer, which, in particular, lead to a modification of the FePc valence electron spin.

Isvoranu, Cristina; Knudsen, Jan; Ataman, Evren; Andersen, Jesper N.; Schnadt, Joachim [Division of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, 221 00 Lund (Sweden); Schulte, Karina [MAX-lab, Lund University, Box 118, 221 00 Lund (Sweden); Wang Bin; Bocquet, Marie-Laure [Laboratoire de chimie, Ecole normale superieure de Lyon, 46, Allee d'Italie, 69364 Lyon Cedex 07 (France)

2011-03-21

354

Densification-induced conductivity percolation in high-porosity pharmaceutical microcrystalline cellulose compacts  

NASA Astrophysics Data System (ADS)

The percolation theory is established as a useful tool in the field of pharmaceutical materials science. It is shown that percolation theory, developed for analyzing insulator-conductor transitions, can be applied to describe imperfect dc conduction in pharmaceutical microcrystalline cellulose during densification. The system, in fact, exactly reproduces the values of the percolation threshold and exponent estimated for a three-dimensional random continuum. Our data clearly show a crossover from a power-law percolation theory region to a linear effective medium theory region at a cellulose porosity of ~0.7.

Strømme, M.; Niklasson, G. A.; Ek, R.

2003-01-01

355

Site-bond percolation on triangular lattices: Monte Carlo simulation and analytical approach  

NASA Astrophysics Data System (ADS)

A generalization of the pure site and pure bond percolation problems called site-bond percolation on a triangular lattice is studied. Motivated by considerations of cluster connectivity, two distinct schemes (denoted as S?B and S?B) for site-bond percolation are used. In S?B (S?B), two points are said to be connected if a sequence of occupied sites and (or) bonds joins them. By using finite-size scaling theory, data from S?B and S?B are analyzed in order to determine (i) the phase boundary between the percolating and non-percolating regions and (ii) the numerical values of the critical exponents of the phase transition occurring in the system. A theoretical approach, based on exact calculations of configurations on finite triangular cells, is applied to study the site-bond percolation on triangular lattices. The percolation processes have been monitored by following the percolation function, defined as the ratio between the number of percolating configurations and the total number of available configurations for a given cell size and concentration of occupied elements. A comparison of the results obtained by these two methods has been performed and discussed.

González, M. I.; Centres, P.; Lebrecht, W.; Ramirez-Pastor, A. J.; Nieto, F.

2013-12-01

356

Effect of conductivity of filler on the percolation threshold of composites  

NASA Astrophysics Data System (ADS)

Polytetrafluoroethylene (PTFE)-silver composites were prepared and the influence of conductivity, particle size, and interfacial area of Ag particle on the percolative behavior were investigated. Silver particles of two different grain sizes (3.5 and 5 ?m) were individually mixed with PTFE and the corresponding variations in the dielectric properties were studied. The composite containing Ag particles of size 3.5 ?m showed the percolation at 7 vol %, while for Ag particles of size 5 ?m, the percolation is at 10 vol %. In both cases near the percolation, the interparticle distances were in the range of ~3.3-3.8 ?m.

Deepa, K. S.; Kumari Nisha, S.; Parameswaran, P.; Sebastian, M. T.; James, J.

2009-04-01

357

Spatial and temporal variations in percolation fluxes in a tropical Andosol influenced by banana cropping patterns  

NASA Astrophysics Data System (ADS)

Spatial variability in percolation fluxes was studied in field plots cropped with banana plants, which induce very heterogeneous rainfall partitioning at the soil surface, with high subsequent infiltration in Andosols. Percolation fluxes were measured for just over a year at 1 7 day intervals in eight wick (WL) and gravity lysimeters (GL) that had been buried in the soil at a depth of 60 cm. The results revealed that WL captured unsaturated fluxes while GL only functioned after ponding occurred. The percolation flux measurements were highly biased with both systems, i.e. overpercolation with WL and underpercolation with GL. Percolation fluxes seemed, however, to be mainly unsaturated in the soil types studied. High percolation flux variability was noted on a plot scale, which could be explained by the vegetation structure: total percolation flux (WL) was 2.1-fold higher under banana plants; saturated percolation flux (GL) was 7-fold higher under banana plants and almost absent between banana plants. Eighty-eight per cent of the total variance in percolation flux could be explained by the rainfall intensity under the banana canopy, calculated while taking the rainfall partitioning by the vegetation and the initial water status into account. The number of lysimeters required for assessing percolation flux in a field plot can be reduced by taking the spatial patterns of the flux boundary conditions into account.

Cattan, P.; Voltz, M.; Cabidoche, Y.-M.; Lacas, J.-G.; Sansoulet, J.

2007-03-01

358

Quarkyonic percolation and deconfinement at finite density and number of colors  

NASA Astrophysics Data System (ADS)

We examine the interplay between the percolation and the deconfinement phase transitions of Yang-Mills matter at finite temperature, quark chemical potential ?Q, and number of colors Nc. We find that, whereas the critical Nc for percolation goes down with density, the critical Nc for confinement generally goes up. Because of this, Yang-Mills matter falls into two qualitatively different regimes: the “low-Nc limit,” where percolation does not occur because matter deconfines before it percolates, and the “high-Nc limit,” where there are three distinct phases—confined, deconfined, and confined but percolating matter—characterizing Yang-Mills matter at finite temperature and density. The latter can be thought of as the recently conjectured “quarkyonic phase.” We attempt an estimate of the critical Nc to see if the percolating phase can occur in our world. We find that, while percolation will not occur at normal nuclear density as in the large-Nc limit, a sliver of the phase diagram in Nc, energy density and baryonic density where percolation occurs while confinement persists is possible. We conclude by speculating on the phenomenological properties of such percolating “quarkyonic” matter and suggesting avenues by which to study it quantitatively and to look for it in experiment.

Lottini, Stefano; Torrieri, Giorgio

2013-08-01

359

Diversity of ammonia monooxygenase operon in autotrophic ammonia-oxidizing bacteria  

Microsoft Academic Search

Autotrophic ammonia-oxidizing bacteria use the essential enzyme ammonia monooxygenase (AMO) to transform ammonia to hydroxylamine. The amo operon consists of at least three genes, amoC, amoA, and amoB; amoA encodes the subunit containing the putative enzyme active site. The use of the amo genes as functional markers for ammonia-oxidizing bacteria in environmental applications requires knowledge of the diversity of the

Jeanette M. Norton; Javier J. Alzerreca; Yuichi Suwa; Martin G. Klotz

2002-01-01

360

Ammonia removal by sweep gas membrane distillation.  

PubMed

Wastewater containing low levels of ammonia (100 mg/L) has been simulated in experiments with sweep gas membrane distillation at pH 11.5. The effects of feed temperature, gas flow rate and feed flow rate on ammonia removal, permeate flux and selectivity were investigated. The feed temperature is a crucial operating factor, with increasing feed temperature increasing the permeate flux significantly, but reducing the selectivity. The best-performing conditions of highest temperature and fastest gas flow rate resulted in 97% removal of the ammonia, to give a treated water containing only 3.3 mg/L of ammonia. PMID:19195677

Xie, Zongli; Duong, Tuan; Hoang, Manh; Nguyen, Cuong; Bolto, Brian

2009-01-18

361

Cylinder supplied ammonia scrubber testing in IDMS  

SciTech Connect

This report summarizes the results of the off-line testing the Integrated DWPF Melter System (IDMS) ammonia scrubbers using ammonia supplied from cylinders. Three additional tests with ammonia are planned to verify the data collected during off-line testing. Operation of the ammonia scrubber during IDMS SRAT and SME processing will be completed during the next IDMS run. The Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) scrubbers were successful in removing ammonia from the vapor stream to achieve ammonia vapor concentrations far below the 10 ppM vapor exit design basis. In most of the tests, the ammonia concentration in the vapor exit was lower than the detection limit of the analyzers so results are generally reported as <0.05 parts per million (ppM). During SRAT scrubber testing, the ammonia concentration was no higher than 2 ppM and during SME testing the ammonia concentration was no higher than 0.05 m.

Lambert, D.P.

1994-08-31

362

Limited-path-length entanglement percolation in quantum complex networks  

NASA Astrophysics Data System (ADS)

We study entanglement distribution in quantum complex networks where nodes are connected by bipartite entangled states. These networks are characterized by a complex structure, which dramatically affects how information is transmitted through them. For pure quantum state links, quantum networks exhibit a remarkable feature absent in classical networks: it is possible to effectively rewire the network by performing local operations on the nodes. We propose a family of such quantum operations that decrease the entanglement percolation threshold of the network and increase the size of the giant connected component. We provide analytic results for complex networks with an arbitrary (uncorrelated) degree distribution. These results are in good agreement with numerical simulations, which also show enhancement in correlated and real-world networks. The proposed quantum preprocessing strategies are not robust in the presence of noise. However, even when the links consist of (noisy) mixed-state links, one can send quantum information through a connecting path with a fidelity that decreases with the path length. In this noisy scenario, complex networks offer a clear advantage over regular lattices, namely, the fact that two arbitrary nodes can be connected through a relatively small number of steps, known as the small-world effect. We calculate the probability that two arbitrary nodes in the network can successfully communicate with a fidelity above a given threshold. This amounts to working out the classical problem of percolation with a limited path length. We find that this probability can be significant even for paths limited to few connections and that the results for standard (unlimited) percolation are soon recovered if the path length exceeds by a finite amount the average path length, which in complex networks generally scales logarithmically with the size of the network.

Cuquet, Martí; Calsamiglia, John

2011-03-01

363

Statistics of rocky coast erosion and percolation theory  

NASA Astrophysics Data System (ADS)

The dynamics of rocky coasts is an erratic phenomenon featuring numerous small erosion events, but sometimes large dramatic collapses. In this sense, its study should not limit or rely on average erosion rates. Recent studies, based on historical as well as recent data, have indicated that the frequency of magnitude of erosion events display long tail distribution, similar to what observed in landslide. In other words the time evolution of a coast morphology does not enter the classical category of Gaussian process, but rather that of critical systems in physics. We recently proposed a minimal dynamical model of rocky coast erosion which is able to reproduce the diversity of rocky coast morphologies and their dynamics. This model is based on a single, simple ingredient, the retroaction of the coast morphology on the erosive power of the sea. It follows from the idea that erosion can spontaneously create irregular seashores, but, in turn, the geometrical irregularity of the coast participates to the damping of sea-waves, decreasing the average wave amplitude and erosive power. The resulting mutual self-stabilization dynamics of the sea erosion power and coastal irregular morphology leads spontaneously the system to a critical dynamics. Our results indicate then that rocky coast erosion and the statistical theory of percolation are closely related. In this framework, the sometimes fractal geometry of coastlines can be recovered and understood in terms of fractal dimension of the external perimeter of a percolation cluster. From a more practical point of view, the analogy with percolation interfaces means that the coast constitutes a strong, but possibly fragile, barrier to sea erosion, emerging from a self-organised selection process. Accordingly, the effect of a slow weathering degradation of the rocks mechanical properties, as well as other perturbations from natural or human cause, can trigger random and large erosion events difficult to predict and control. To the extent that these ideas apply, natural coasts should be "preserved" and managed with care.

Baldassarri, A.; Sapoval, B.

2012-04-01

364

Estimating ammonia emission factors in Europe. Summary of the work of the UNECE ammonia expert panel  

NASA Astrophysics Data System (ADS)

The UNECE ammonia expert panel presents emission factors for the ammonia emissions from agriculture. Included are emissions from animal husbandry (housing, storage of the wastes outside the building, grazing and application of the wastes), application of fertilizers to crops and grasslands, stubble burning of agricultural residues and finally ammonia emissions from latrines.

Van Der Hoek, K. W.

365

Statics of a ``self-organized'' percolation model  

NASA Astrophysics Data System (ADS)

A stochastic ``forest-fire'' model is considered. Sites are filled individually at a constant mean rate; also, ``sparks'' are dropped at a small rate k, and instantaneously burn up the entire cluster they hit. I find nontrivial critical exponents in the self-organized critical limit k-->0, contrary to earlier results of Drossel and Schwabl. Spatial correlation functions and a site occupancy correlation exponent are measured for the first time. Scaling relations, derived by analogy to uncorrelated percolation, are used extensively as numerical checks. Hyperscaling is violated in this system.

Henley, Christopher L.

1993-10-01

366

On the Speed of Convergence in First-Passage Percolation  

Microsoft Academic Search

We consider the standard first-passage percolation problem on $\\\\mathbb{Z}^d: \\\\{t(e): e \\\\text{an edge of} \\\\mathbb{Z}^d\\\\}$ is an i.i.d. family of random variables with common distribution $F, a_{0,n} := \\\\inf\\\\{\\\\sum^k_1 t(e_1): (e_1, \\\\cdots, e_k)$ a path on $\\\\mathbb{Z}^d$ from 0 to $n \\\\xi_1\\\\}$, where $\\\\xi_1$ is the first coordinate vector. We show that $\\\\sigma^2(a_{0,n}) \\\\leq C_1 n$ and that $P\\\\{|a_{0,n} -

Harry Kesten

1993-01-01

367

FAST TRACK COMMUNICATION: Percolation crossing formulae and conformal field theory  

NASA Astrophysics Data System (ADS)

Using conformal field theory, we derive several new crossing formulae at the two-dimensional percolation point. High-precision simulation confirms these results. Integrating them gives a unified derivation of Cardy's formula for the horizontal crossing probability ?h(r), Watts' formula for the horizontal-vertical crossing probability ?hv(r) and Cardy's formula for the expected number of clusters crossing horizontally \\mathcal{N}_h(r) . The main step in our approach implies the identification of the derivative of one primary operator with another. We present operator identities that support this idea and suggest the presence of additional symmetry in c = 0 conformal field theories.

Simmons, Jacob J. H.; Kleban, Peter; Ziff, Robert M.

2007-08-01

368

Percolation in insect nest networks: Evidence for optimal wiring  

NASA Astrophysics Data System (ADS)

Optimization has been shown to be a driving force for the evolution of some biological structures, such as neural maps in the brain or transport networks. Here we show that insect networks also display characteristic traits of optimality. By using a graph representation of the chamber organization of termite nests and a disordered lattice model, it is found that these spatial nests are close to a percolation threshold. This suggests that termites build efficient systems of galleries spanning most of the nest volume at low cost. The evolutionary consequences are outlined.

Valverde, Sergi; Corominas-Murtra, Bernat; Perna, Andrea; Kuntz, Pascale; Theraulaz, Guy; Solé, Ricard V.

2009-06-01

369

On the genre-fication of music: a percolation approach  

NASA Astrophysics Data System (ADS)

We analyze web-downloaded data on people sharing their music library. By attributing to each music group usual music genres (Rock, Pop ...), and analysing correlations between music groups of different genres with percolation-idea based methods, we probe the reality of these subdivisions and construct a music genre cartography, with a tree representation. We also discuss an alternative objective way to classify music, that is based on the complex structure of the groups audience. Finally, a link is drawn with the theory of hidden variables in complex networks.

Lambiotte, R.; Ausloos, M.

2006-03-01

370

Band and percolation approaches to low temperature properties of manganites  

SciTech Connect

Properties of the parent compound, LaMnO[sub 3] are greatly affected by strong Hund's coupling. Assuming the antiferromagnetic ordering (with a low Neel temperature) along one of the cubic axes, this coupling would result in formation of disconnected ferromagnetic layers. Furthermore, in the presence of the cooperative Jahn-Teller effect the compound becomes a band insulator. At small doping (La[sub 1[minus]x]Ca[sub x]MnO[sub 3], x [much lt] 1) the band insulator phase coexists with the presence of localized holes. An insulator-ferromagnetic metal transition occurs at the percolation point x[sub c] = 0.16.

Gor'kov, L.P. (Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. L.D. Landau Inst. for Theoretical Physics (Russian Federation)); Kresin, V.Z. (Lawrence Berkeley Lab., CA (United States))

1998-12-20

371

Emergent Spin Excitations in a Bethe Lattice at Percolation  

NASA Astrophysics Data System (ADS)

We study the spin-1/2 quantum Heisenberg antiferromagnet on a Bethe lattice diluted to the percolation threshold. Dilution creates areas of even or odd sublattice imbalance resulting in “dangling spins” [L. Wang and A. W. Sandvik, Phys. Rev. Lett. 97, 117204 (2006); Phys. Rev. B 81, 054417 (2010)]. These collectively act as “emergent” spin-1/2 degrees of freedom and are responsible for the creation of a set of low-lying “quasidegenerate states.” Using density matrix renormalization group calculations, we detect the presence and location of these emergent spins. We find an effective Hamiltonian of these emergent spins, with Heisenberg interactions that decay exponentially with the distance between them.

Changlani, Hitesh J.; Ghosh, Shivam; Pujari, Sumiran; Henley, Christopher L.

2013-10-01

372

Capillary condensation, invasion percolation, hysteresis, and discrete memory  

SciTech Connect

A model of the capillary condensation process, i.e., of adsorption-desorption isotherms, having only pore-pore interactions is constructed. The model yields (1) hysteretic isotherms, (2) invasion percolation on desorption, and (3) hysteresis with discrete memory for interior chemical potential loops. All of these features are seen in experiment. The model is compared to a model with no pore-pore interactions (the Preisach model) and to a related model of interacting pore systems (the random field Ising model). The capillary condensation model differs from both. {copyright} {ital 1996 The American Physical Society.}

Guyer, R.A. [Department of Physics and Astronomy, University of Massachusetts, Amherst, Massachusetts 01003 (United States); McCall, K.R. [Department of Physics, University of Nevada, Reno, Nevada 89557 (United States)

1996-07-01

373

From damage percolation to crack nucleation through finite size criticality.  

PubMed

We present a unified theory of fracture in disordered brittle media that reconciles apparently conflicting results reported in the literature. Our renormalization group based approach yields a phase diagram in which the percolation fixed point, expected for infinite disorder, is unstable for finite disorder and flows to a zero-disorder nucleation-type fixed point, thus showing that fracture has a mixed first order and continuous character. In a region of intermediate disorder and finite system sizes, we predict a crossover with mean-field avalanche scaling. We discuss intriguing connections to other phenomena where critical scaling is only observed in finite size systems and disappears in the thermodynamic limit. PMID:23683218

Shekhawat, Ashivni; Zapperi, Stefano; Sethna, James P

2013-04-29

374

Percolative phenomena and electrorheological structures in reverse micelles  

NASA Astrophysics Data System (ADS)

Structural relaxations in AOT (sodium bis(2-ethylhexyl) sulphosuccinate) and lecithin reverse micelles are investigated by means of dielectric relaxation and conductivity measurements. The different behaviours exhibited by the two systems are interpreted in terms of the different kinds of interaction between the water and the surfactant molecules. In the case of lecithin, the application of an external electric field induces the establishing of some electrorheological structure. The temperature dependence of the observed electrorheological effects agrees with the hypothesis of a structural arrangement consisting in a percolated network of branched cylindrical micelles. The experimental results are compared with other literature data and discussed within the framework of the current theories.

Aliotta, F.

2002-03-01

375

Evidence of percolative phenomena in a lecithin-based gel  

NASA Astrophysics Data System (ADS)

The structure of the gel-phase, observed in a number of lecithin-in-oil microemulsions after addition of water, is the topic of a controversy actually taking place in the literature. In this paper, we will show how the dynamical properties of water confined in the inner core of the micelles, as investigated by QENS and INS, turn out to be inconsistent with the usually proposed model of entangled (not interconnected) polymer-like micelles. A percolated structure of branched cylindrical aggregates could agree with the presented data.

Aliotta, F.; Vasi, C.; Lechner, R. E.; Ruffle, B.

2000-03-01

376

COPPER CABLE RECYCLING TECHNOLOGY  

SciTech Connect

The United States Department of Energy (DOE) continually seeks safer and more cost-effective technologies for use in deactivation and decommissioning (D&D) of nuclear facilities. The Deactivation and Decommissioning Focus Area (DDFA) of the DOE's Office of Science and Technology (OST) sponsors large-scale demonstration and deployment projects (LSDDPs). At these LSDDPs, developers and vendors of improved or innovative technologies showcase products that are potentially beneficial to the DOE's projects and to others in the D&D community. Benefits sought include decreased health and safety risks to personnel and the environment, increased productivity, and decreased costs of operation. The Idaho National Engineering and Environmental Laboratory (INEEL) generated a list of statements defining specific needs and problems where improved technology could be incorporated into ongoing D&D tasks. One such need is to reduce the volume of waste copper wire and cable generated by D&D. Deactivation and decommissioning activities of nuclear facilities generates hundreds of tons of contaminated copper cable, which are sent to radioactive waste disposal sites. The Copper Cable Recycling Technology separates the clean copper from contaminated insulation and dust materials in these cables. The recovered copper can then be reclaimed and, more importantly, landfill disposal volumes can be reduced. The existing baseline technology for disposing radioactively contaminated cables is to package the cables in wooden storage boxes and dispose of the cables in radioactive waste disposal sites. The Copper Cable Recycling Technology is applicable to facility decommissioning projects at many Department of Energy (DOE) nuclear facilities and commercial nuclear power plants undergoing decommissioning activities. The INEEL Copper Cable Recycling Technology Demonstration investigated the effectiveness and efficiency to recycle 13.5 tons of copper cable. To determine the effectiveness of separating out radioactive contamination, the copper cable was coated with a surrogate contaminant. The demonstration took place at the Bonneville County Technology Center in Idaho Falls, Idaho.

Chelsea Hubbard

2001-05-01

377

Municipal solid waste recycling issues  

SciTech Connect

Municipal solid waste (MSW) recycling targets have been set nationally and in many states. Unfortunately, the definitions of recycling, rates of recycling, and the appropriate components of MSW vary. MSW recycling has been found to be costly for most municipalities compared to landfill disposal. MSW recycling policy should be determined by the cost to the community and to society more generally. In particular, recycling is a good policy only if environmental impacts and the resources used to collect, sort, and recycle a material are less than the environmental impacts and resources needed to provide equivalent virgin material plus the resources needed to dispose of the postconsumer material safely. From a review of the existing economic experience with recycling and an analysis of the environmental benefits (including estimation of external social costs), the authors find that, for most communities, curbside recycling is only justifiable for some postconsumer waste, such as aluminum and other metals. They argue that alternatives to curbside recycling collection should be explored, including product takeback for products with a toxic content (such as batteries) or product redesign to permit more effective product remanufacture.

Lave, L.B.; Hendrickson, C.T.; Conway-Schempf, N.M.; McMichael, F.C. [Carnegie-Mellon Univ., Pittsburgh, PA (United States)

1999-10-01

378

Ammonia-oxidizing archaea involved in nitrogen removal  

Microsoft Academic Search

Ammonia oxidation is critical to global nitrogen cycling and is often thought to be driven only by ammonia-oxidizing bacteria. The recent finding of new ammonia-oxidizing organisms belonging to the archaeal domain challenges this perception. Two major microbial groups are now believed to be involved in ammonia oxidation: chemolithotrophic ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA). Candidatus “Nitrosopumilus maritimus”, the first

Jia You; Atreyee Das; Elizabeth M. Dolan; Zhiqiang Hu

2009-01-01

379

Percolation phenomenon in ternary microemulsions: The effect of pressure  

NASA Astrophysics Data System (ADS)

The electrical conductivity ? and dynamic viscosity ? of water-based water-AOT-undecane [AOT:sodium bis(2-ethylhexyl) sulfosuccinate] microemulsions and waterless glycerol-AOT-isooctane microemulsions were studied as a function of volume fraction ? in dispersed matter (water plus AOT or glycerol plus AOT) and pressure up to 1000 bar. The realm of existence of the single-phase zone was also determined versus pressure P. The curves ?(P) and ?(P) at constant ? and temperature T, and the curves ?(?) and ?(?) at constant P and T were analyzed within the framework of percolation theory. For water-based microemulsions the percolation threshold ?c decreases when P increases, corresponding to an increase in interactions. For waterless microemulsions ?c varies very little. The scaling exponents are ~=2 above the threshold and ~=-1.2 below, whatever the pressure, the system, and the property studied (values which have already between obtained at 1 bar). This corresponds to the fact that these systems belong to the same class of universality.

Boned, C.; Saidi, Z.; Xans, P.; Peyrelasse, J.

1994-06-01

380

High volumetric capacitance near the insulator-metal percolation transition  

NASA Astrophysics Data System (ADS)

I propose a new type of capacitor with a very high volumetric capacitance. It is based on the known phenomenon of the sharp increase of the dielectric constant of a metal-insulator composite in the vicinity of the percolation threshold on the insulator side. The optimization suggests that the sizes of the metallic particles should fall within the nanoscale. The distance between planar electrodes should be somewhat larger than the correlation length of the percolation theory and ?10-20 times larger than the size of the particles while the area of the electrodes could be unlimited. The random electric field in the capacitor is calculated and is shown to be larger than the average field corresponding to the potential difference of the electrodes. This random field is potentially responsible for the dielectric breakdown. The estimated breakdown voltage of the capacitor shows that the stored energy density might be significantly larger than that of electrolytic capacitors while the volumetric capacitances might be comparable. The charging and discharging times should be significantly smaller than the corresponding times of batteries and even electrolytic capacitors.

Efros, A. L.

2011-10-01

381

Dielectric relaxation and percolation phenomena in ternary microemulsions  

NASA Astrophysics Data System (ADS)

Dielectric relaxation of water/AOT/oil (iso-octane, undecane, dodecane, cyclohexane) microemulsions was studied by means of time-domain spectroscopy. [Here AOT is an abbreviation for sodium bis(2-ethylhexyl)sulfosuccinate.] The experiments were carried out for several values of the volume fraction ? (water + AOT) and of the molar ratio n= [water]/[AOT]. They showed the presence of a maximum of static permittivity ?s associated with a minimum of the relaxation frequency ?R and a maximum of the frequency-spread parameter ?. The influence of the salt content was also considered. The results are discussed with reference to the theory of percolation, and were found to be in close agreement with the theoretical predictions. By analogy with previous results on conductivity [M. Moha-Ouchane, J. Peyrelasse, and C. Boned, Phys. Rev. A 35, 3027 (1987)], the influence of temperature is discussed. The important part played by interactions and the phenomenon of ``hopping'' are demonstrated in connection with an already existing model (an off-lattice simulation). Finally, the results show the importance of the notion of ``percolation threshold lines'' introduced previously (Moha-Ouchane, Peyrelasse, and Boned).

Peyrelasse, J.; Moha-Ouchane, M.; Boned, C.

1988-07-01

382

a Percolation Model of Mobile Ad-Hoc Networks  

NASA Astrophysics Data System (ADS)

Mobile ad-hoc networks (MANETs) are random, self-configurable and rapidly-deployable networks. The main goal of developing the MANETs is not only obtaining better service, but also having networks that can serve in situations in which no other means of communications can operate. Examples include networks that are used in battlefields, in search-and-rescue operations, and networks of sensors. We propose a percolation model for studying the properties of the MANETs. The model is based on a random network of sites, distributed in space, which represent the mobile nodes. Two nodes are linked if they are within each other's transmission ranges. A node may be lost or become inactive if, for example, it runs out of energy (provided by its batteries). A link can be lost if, for example, one of its two end nodes moves outside of the other's transmission range. Extensive Monte Carlo simulations are carried out to study the properties of the model. The network's topology is characterized by a critical transmission range, which is the analogue of the percolation threshold. It is shown that not only can the model take into account several important features of the real MANETs and explain them in physical terms, but also leads to the development of efficient protocols for self-configuration, adaptability, and disaster survival, which are of utmost importance to the practical applications.

Mohammadi, Hossein; Oskoee, Ehsan Nedaaee; Afsharchi, Mohsen; Yazdani, Nasser; Sahimi, Muhammad

383

Experimental and computational investigation of percolation in complex polymer nanocomposites  

NASA Astrophysics Data System (ADS)

The continuing development of polymer nanocomposites has led to increasingly complex morphology, such as the mats of composite nanofibers formed from electrospinning. The formation of particle networks within the composite volume that leads to enhanced properties, such as electrical conductivity, may be influenced by this complex sample geometry. In this work, experimental and computational efforts are utilized to understand and predict the percolation threshold (critical volume fraction) for two cases: single ultra-high aspect ratio fibers (where fiber diameter can be similar to the particle dimensions) and these same fibers arranged in a random mat with up to 80% porosity. 2D and 3D Monte Carlo simulations, modeled on the actual parameters of our experimental system [1], are utilized and the results are compared with our experimental findings. In particular, confinement to fibers increases the percolation threshold; however the multi-fiber pathways available in mats partially reduce this constraint [2]. [1] S.S. Ojha, D.R. Stevens, K. Stano, T. Hoffman, L.I. Clarke, R.E. Gorga, Macromolecules 41, 2509 (2008). [2] D.R. Stevens, L.N. Downen, L.I. Clarke, Phys. Rev. B in press (2008).

Stevens, Derrick; Downen, Lori; Gorga, Russell; Clarke, Laura

2009-03-01

384

METHODOLOGY AND INSTRUMENTATION TO MEASURE GASEOUS AMMONIA  

EPA Science Inventory

Methodology for the time integrated collection and analysis of atmospheric ammonia was developed. Ammonia is primarily measured because it can react with SOx to produce ammonium sulfate. Since SOx is one of the principle air pollutants, it is important to determine its atmospheri...

385

Evaluation of ammonia emissions from broiler litter  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ammonia emissions from poultry litter results in air pollution and can cause high levels of ammonia in poultry houses, which negatively impacts bird performance. The objectives of this study were to: (1) conduct a nitrogen (N) mass balance in broiler houses by measuring the N inputs (bedding, chick...

386

CHRONIC TOXICITY OF AMMONIA OF RAINBOW TROUT  

EPA Science Inventory

The chronic effects of ammonia to rainbow trout Salmo gairdneri were studied in a laboratory test conducted over a 5-year period. Fish were tested at five concentrations over the range 0.01-0.07 mg/liter un-ionized ammonia; the mean pH of the test water was 7.7, and the mean temp...

387

Autotrophic Ammonia Removal Processes: Ecology to Technology  

Microsoft Academic Search

The last decade has witnessed rapid spur in technoeconomic autotrophic ammonia removal technologies for wastewater treatment such as SHARON, ANAMMOX, SNAD, CANON, OLAND, DEMON, and BABE. These technologies have the potential to remove high concentrations of ammonia in wastewaters. Despite their high removal efficiency, the quantum of full-scale applications of these processes is far from trivial. The issues that create

Samik Bagchi; Rima Biswas; Tapas Nandy

2012-01-01

388

AMMONIUM DIURANATE PRECIPITATION WITH ANHYDROUS AMMONIA  

Microsoft Academic Search

Ammonium diuranate has been precipitated from nitric acid solutions by ; the addition of anhydrpus ammonia on both laboratory and production scales. This ; process produced more dense and morc rapidly filtered precipitates than those ; formed by the addition of aqueous amonia or slurried calcium hydroxide. Thc ; filtrates from the anhydrous ammonia process were lower in uranium content

L. C. Farrell; L. F. Grill

1959-01-01

389

Depletion of Ammonia Gas onto Jovian Ices  

NASA Astrophysics Data System (ADS)

The microwave spectrum of Jupiter is consistent with supersolar ammonia deeper than 6 bar, and subsolar ammonia at pressures less than 2 bar. Because the Galileo Probe Mass Spectrometer measured a deep NH3/H2 mixing ratio of 6.4x10-4---or five times the protosolar ratio---the microwave data show that there must be a global-scale depletion mechanism for ammonia gas, operating between the 2 and 6 bar levels. Candidate depletion mechanisms include dynamics, condensation of species with higher nitrogen fractions than NH4SH (including clathrates), and adsorption of ammonia onto NH4SH or water ices. -- We have begun laboratory experiments designed to measure the uptake of ammonia by H2O and H2O-NH4SH ice mixtures. We also plan model calculations to apply the experimental results to Jupiter's atmosphere and quantify the effect of ammonia uptake by ices. The laboratory study uses a Knudsen cell apparatus in a temperature regime (130-250 K) appropriate to the troposphere of Jupiter around the 2-4 bar pressure level, where the microwave data indicate depletion of ammonia gas. We will discuss the key parameters and processes that influence the ammonia uptake and their relevance to Jupiter's atmosphere. This work is supported by the NASA Planetary Atmospheres Program.

Wong, Michael H.; Kasper, T.; Marschall, J.; de Pater, I.; Romani, P. N.; Kalogerakis, K. S.

2010-10-01

390

Method for releasing hydrogen from ammonia borane  

DOEpatents

A method of releasing hydrogen from ammonia borane is disclosed. The method comprises heating an aqueous ammonia borane solution to between about 80-135.degree. C. at between about 14.7 and 200 pounds per square inch absolute (psia) to release hydrogen by hydrothermolysis.

Varma, Arvind; Diwan, Moiz; Shafirovich, Evgeny; Hwang, Hyun-Tae; Al-Kukhun, Ahmad

2013-02-19

391

Critical litter moisture maximizes ammonia generation  

Technology Transfer Automated Retrieval System (TEKTRAN)

The natural breakdown of litter (bedding material mixed with deposits of feces, feathers, spilled feed and water) generates ammonia in poultry houses. Good management practices can reduce ammonia concentrations in poultry houses. Findings from a recent publication indicate there is a critical litt...

392

Fabrication of Functional Nanofibrous Ammonia Sensor  

Microsoft Academic Search

A nanofibrous sensor for ammonia gas is fabricated by electrospinning the composite of poly(diphenylamine) (PDPA) with poly(methyl methacrylate) (PMMA) onto the patterned interdigit electrode. The composite electrospun membrane shows interconnected fibrous morphology. Functional groups in PDPA and the high active surface area of the fibrous membrane make the device detect a lower concentration of ammonia with a good reproducibility. The

Kalayil Manian Manesh; Anantha Iyengar Gopalan; Kwang-Pill Lee; Padmanabhan Santhosh; Kap-Duk Song; Duk-Dong Lee

2007-01-01

393

EFFLUENT AMMONIA VARIABILITY FROM NITRIFICATION FACILITIES  

EPA Science Inventory

A statistical analysis was made on several years worth of daily effluent ammonia concentrations from seven Ohio nitrification plants. Significant seasonal and annual trends were found in six of the plants. The full range of ammonia variability within a season could not generally ...

394

AMMONIA EMISSION FACTORS FROM SWINE FINISHING OPERATIONS  

Microsoft Academic Search

Concentrated animal feeding operations (CAFOs) are being examined in several regions of the U.S. as major sources of ammonia and particulate matter precursors. The National Risk Management Research Laboratory (NRMRL) has previously measured ammonia concentrations around and estimated emissions from a swine production facility. In this paper we present the results from two new studies at swine finishing facilities. New

D. Bruce Harris; Richard C. Shores; Larry G. Jones

395

Hydrogen gas generator from hydrazine\\/ammonia  

Microsoft Academic Search

A catalyst bed containing alumina pellets on which an active catalyst metal selected from iridium, nickel, niobium, and molybdenum has been deposited is employed to decompose a compound selected from deuterohydrazine, deuteroammonia, hydrazine, and ammonia to yield ammonia free deuterium and nitrogen or hydrogen and nitrogen at a temperature required for immediate use in a DF or HF laser which

P. Martignoni; W. M. Chew; O. E. Ayers; J. A. Jr. Murfree

1979-01-01

396

21 CFR 573.180 - Anhydrous ammonia.  

Code of Federal Regulations, 2013 CFR

...anhydrous ammonia is applied directly to corn plant material and thoroughly blended...percent of body weight daily in shelled corn; and a warning not to use additional trace...anhydrous ammonia is applied directly to corn plant material for use in dairy or...

2013-04-01

397

Why recycle? A comparison of recycling motivations in four communities  

NASA Astrophysics Data System (ADS)

Four Illinois communities with different sociode-mographic compositions and at various stages of planning for solid waste management were surveyed to determine the influence of sociodemographic variables and planning stages on the factors that motivate recycling behavior. A factor analysis of importance ratings of reasons for recycling and for not recycling yielded five factors interpreted as altruism, personal inconvenience, social influences, economic incentives, and household storage. The four communities were shown to be significantly different in multivariate analyses of the five motivational factors. However, attempts to explain these community differences with regression analyses, which predicted the motivational factors with dummy codes for planning stages, a measure of self-reported recycling behavior, and sociodemographic measures were unsatisfactory. Contrary to expectation, the solid waste management planning stages of the cities (curbside pickup, recycling dropoff center, and planning in progress) contributed only very slightly to the prediction of motivational factors for recycling. Community differences were better explained by different underlying motivational structures among the four communities. Altruistic reasons for recycling (e.g., conserving resources) composed the only factor which was similar across the four communities. This factor was also perceived to be the most important reason for recycling by respondents from all four communities. The results of the study supported the notion that convenient, voluntary recycling programs that rely on environmental concern and conscience for motivation are useful approaches to reducing waste.

Vining, Joanne; Linn, Nancy; Burdge, Rabel J.

1992-11-01

398

Dynamics of Ammonia Borane Using Neutron Scattering  

SciTech Connect

We have used both the backscattering (HFBS) and time-of-flight (DCS) neutron spectrometers to investigate the proton dynamics in ammonia borane, a compound of intense interest as a model for 'chemical hydrogen storage' materials. Results indicate that the deposition of ammonia borane on a mesoporous silicate results in longer proton residence times and lower energy barriers for proton motion compared to bulk ammonia borane. The reduced activation energy for proton motions may partly explain the improved thermolysis and lowering the activation barrier for the loss of the first equivalent of H2. In addition, the phonon density of states for neat ammonia borane compares well with other spectroscopic results, with the intense peak at 22 meV assigned to the librational NH3 and BH3 modes, whereas ammonia borane on MCM-41 displays a broad, featureless spectrum indicating a poorly crystalline material.

Brown, Craig; Jacques, Teresa; Hess, Nancy J.; Daemen, Luke L.; Mamontov, Eugene; Linehan, John C.; Stowe, Ashley C.; Autrey, Thomas

2006-11-15

399

Ammonia plant waste is good fertilizer  

SciTech Connect

According to C. M. Farris of United States Steel Corp., Agri-Chemicals Division , the process condensate from ammonia plants should be applied to the land. Work at his firm's Alabama ammonia plant showed that the condensate can be used safely to irrigate and fertilize a variety of crops. Under law, the condensate must be treated, usually by steam stripping, to reduce the ammonia content before discharge to waterways, a procedure that wastes money and energy. If instead of treating the condensate which contains 400-2000 ppm of ammonia and 200-1200 ppm of methanol, the entire U.S. ammonia industry applied the condensate to the land, energy equivalent to > 1 million bbl/yr of oil would be savd.

Farris, C.M.

1980-09-08

400

Isothermal drying on non-hygroscopic capillary-porous materials as an invasion percolation process  

Microsoft Academic Search

Numerical simulations of drainage and drying at low capillary number are performed. Drainage is simulated by means of the standard invasion percolation algorithm. Simulations of drying are based on an invasion algorithm combining elements of the invasion percolation algorithm with the computation of the vapour flux at each elementary liquid-gas interface. The simulations show that the invasion front is the

M. Prat

1995-01-01

401

The use of macroscopic percolation theory to construct large-scale capillary pressure curves  

Microsoft Academic Search

This paper introduces a macroscopic invasion percolation process suitable for simulating the displacement of one immiscible fluid by another through porous media under conditions of capillary-dominated flow. The theory is similar to classical percolation theory in that the structure of a real porous medium is represented as an ordered lattice, but differs in that each point of the lattice is

Bernard H. Kueper; David B. McWhorter

1992-01-01

402

The Use of Macroscopic Percolation Theory to Construct Large-Scale Capillary Pressure Curves  

Microsoft Academic Search

This paper introduces a macroscopic invasion percolation process suitable for simulating the displacement of one immiscible fluid by another through porous media under conditions of capillary-dominated flow. The theory is similar to classical percolation theory in that the structure of a real porous medium is represented as an ordered lattice, but differs in that each point of the lattice is

Bernard H. Kueper; David B. McWhorter

1992-01-01

403

An improved Percoll density gradient for measurements of experimental brain edema  

Microsoft Academic Search

Microgravimetric methods are very useful for quantitative studies on brain edema. One of the techniques available is based on a gradient made up by NaCl and polyvinyl pyrrolidone-coated silica particles (Percoll). The present study was performed to find a way of minimizing fluid shifts between the gradient and the samples. For this purpose, five Percoll density gradients containing various concentrations

C. Tengvar; D. Hultström; Y. Olsson

1983-01-01

404

Combining percolator with X!Tandem for accurate and sensitive peptide identification.  

PubMed

In this work, Percolator was successfully interfaced with X!Tandem using a PHP program to generate an improved search platform, X!Tandem Percolator. In order to achieve the best classification performance of peptide identifications in Percolator, a set of experimentally validated spectral identifications (34,993 MS/MS spectra) were used to guide the development of discriminatory features from X!Tandem search results. By comparing the features (e.g., Log(E) and mass error) of these experimentally validated peptide matches with those of false identifications, a comprehensive set of features can be chosen for Percolator in an objective and rational manner. The accuracy of X!Tandem Percolator was demonstrated by comparing the estimated q-value of the validated data set with the empirical q-value. By comparing the results from the X!Tandem Percolator and the original X!Tandem, superior sensitivity and specificity of the X!Tandem Percolator result was demonstrated on various shotgun proteomic data sets under different search conditions. In all of the cases studied in this work, X!Tandem Percolator could improve the number of peptide identifications at the same level of q-values. PMID:23581882

Xu, Mingguo; Li, Zhendong; Li, Liang

2013-05-01

405

Percolation model of immiscible displacement in the presence of buoyancy forces  

Microsoft Academic Search

We consider the quasistatic displacement of a nonwetting fluid by a wetting one in a porous medium in the presence of buoyancy forces. A simple percolation model of this process is presented and analyzed both theoretically and by Monte Carlo simulation. It is shown that the fact that percolation is a critical phenomenon, with diverging correlation length at the critical

David Wilkinson

1984-01-01

406

Applications of percolation theory to porous media with distributed local conductances  

Microsoft Academic Search

Critical path analysis and percolation theory are known to predict accurately dc and low frequency ac electrical conductivity in strongly heterogeneous solids, and have some applications in statistics. Much of this work is dedicated to review the current state of these theories. Application to heterogeneous porous media has been slower, though the concept of percolation was invented in that context.

A. G. Hunt

2001-01-01

407

Continuum percolation theory for pressure–saturation characteristics of fractal soils: extension to non-equilibrium  

Microsoft Academic Search

Systematic experimental deviations from theoretical predictions derived for water retention characteristics of fractal porous media have previously been interpreted in terms of continuum percolation theory (at low moisture contents, below the critical volume fraction of water, ?c capillary flow ceases). In other work, continuum percolation theory was applied to find the hydraulic conductivity as a function of saturation for saturations

A. G. Hunt

2004-01-01

408

Autotrophic ammonia oxidation by soil thaumarchaea  

PubMed Central

Nitrification plays a central role in the global nitrogen cycle and is responsible for significant losses of nitrogen fertilizer, atmospheric pollution by the greenhouse gas nitrous oxide, and nitrate pollution of groundwaters. Ammonia oxidation, the first step in nitrification, was thought to be performed by autotrophic bacteria until the recent discovery of archaeal ammonia oxidizers. Autotrophic archaeal ammonia oxidizers have been cultivated from marine and thermal spring environments, but the relative importance of bacteria and archaea in soil nitrification is unclear and it is believed that soil archaeal ammonia oxidizers may use organic carbon, rather than growing autotrophically. In this soil microcosm study, stable isotope probing was used to demonstrate incorporation of 13C-enriched carbon dioxide into the genomes of thaumarchaea possessing two functional genes: amoA, encoding a subunit of ammonia monooxygenase that catalyses the first step in ammonia oxidation; and hcd, a key gene in the autotrophic 3-hydroxypropionate/4-hydroxybutyrate cycle, which has been found so far only in archaea. Nitrification was accompanied by increases in archaeal amoA gene abundance and changes in amoA gene diversity, but no change was observed in bacterial amoA genes. Archaeal, but not bacterial, amoA genes were also detected in 13C-labeled DNA, demonstrating inorganic CO2 fixation by archaeal, but not bacterial, ammonia oxidizers. Autotrophic archaeal ammonia oxidation was further supported by coordinate increases in amoA and hcd gene abundance in 13C-labeled DNA. The results therefore provide direct evidence for a role for archaea in soil ammonia oxidation and demonstrate autotrophic growth of ammonia oxidizing archaea in soil.

Zhang, Li-Mei; Offre, Pierre R.; He, Ji-Zheng; Verhamme, Daniel T.; Nicol, Graeme W.; Prosser, James I.

2010-01-01

409

Ammonia gas permeability of meat packaging materials.  

PubMed

Meat products are packaged in polymer films designed to protect the product from exterior contaminants such as light, humidity, and harmful chemicals. Unfortunately, there is almost no data on ammonia permeability of packaging films. We investigated ammonia permeability of common meat packaging films: low-density polyethylene (LDPE; 2.2 mil), multilayer polyolefin (MLP; 3 mil), and vacuum (V-PA/PE; 3 mil, 0.6 mil polyamide/2.4 mil polyethylene). The films were fabricated into 10 × 5 cm pouches and filled with 50 mL deionized water. Pouches were placed in a plexiglass enclosure in a freezer and exposed to 50, 100, 250, or 500 ppm ammonia gas for 6, 12, 24, and 48 h at -17 ± 3 °C and 21 ± 3 °C. At freezing temperatures, no ammonia residues were detected and no differences in pH were found in the water. At room temperature, ammonia levels and pH of the water increased significantly (P < 0.05) with increasing exposure times and ammonia concentrations. Average ammonia levels in the water were 7.77 ppm for MLP, 5.94 ppm for LDPE, and 0.89 ppm for V-PA/PE at 500 ppm exposure for 48 h at 21 ± 3 °C. Average pH values were 8.64 for MLP, 8.38 for LDPE, and 7.23 for V-PA/PE (unexposed ranged from 5.49 to 6.44) at 500 ppm exposure for 48 h. The results showed that temperature influenced ammonia permeability. Meat packaging materials have low ammonia permeability and protect meat products exposed to ammonia leaks during frozen storage. PMID:21535796

Karim, Faris; Hijaz, Faraj; Kastner, Curtis L; Smith, J Scott

2011-02-01

410

Jupiter's ammonia clouds—localized or ubiquitous?  

NASA Astrophysics Data System (ADS)

From an analysis of the Galileo Near Infrared Imaging Spectrometer (NIMS) data, Baines et al. (Icarus 159 (2002) 74) have reported that spectrally identifiable ammonia clouds (SIACs) cover less than 1% of Jupiter. Localized ammonia clouds have been identified also in the Cassini Composite Infrared Spectrometer (CIRS) observations (Planet. Space Sci. 52 (2004a) 385). Yet, ground-based, satellite and spacecraft observations show that clouds exist everywhere on Jupiter. Thermochemical models also predict that Jupiter must be covered with clouds, with the top layer made up of ammonia ice. For a solar composition atmosphere, models predict the base of the ammonia clouds to be at 720 mb, at 1000 mb if N/H were 4×solar, and at 0.5 bar for depleted ammonia of 10 -2×solar (Planet. Space Sci. 47 (1999) 1243). Thus, the above NIMS and CIRS findings are seemingly at odds with other observations and cloud physics models. We suggest that the clouds of ammonia ice are ubiquitous on Jupiter, but that spectral identification of all but the freshest of the ammonia clouds and high altitude ammonia haze is inhibited by a combination of (i) dusting, starting with hydrocarbon haze particles falling from Jupiter's stratosphere and combining with an even much larger source - the hydrazine haze; (ii) cloud properties, including ammonia aerosol particle size effects. In this paper, we investigate the role of photochemical haze and find that a substantial amount of haze material can deposit on the upper cloud layer of Jupiter, possibly enough to mask its spectral signature. The stratospheric haze particles result from condensation of polycyclic aromatic hydrocarbons (PAHs), whereas hydrazine ice is formed from ammonia photochemistry. We anticipate similar conditions to prevail on Saturn.

Atreya, S. K.; Wong, A. S.; Baines, K. H.; Wong, M. H.; Owen, T. C.

2005-04-01

411

Numerical studies of gravity destabilized percolation in 2D porous media  

NASA Astrophysics Data System (ADS)

Two dimensional simulations of percolation are realized on square networks of pore throats with a random capillary pressure distribution. We analyse the influence of a destabilizing gravity field (g) and of the standard deviation of the distribution of the capillary pressure thresholds (Wt). The fragmentation process is not taken into account in this study. For an increase of g or/and when Wt decreases, two transitions are analyzed with three different regimes displacement patterns: Invasion percolation, invasion percolation in a gradient, and invasion in a pure gradient. The transitions are controlled both by the ratio g/Wt and by the sample size (L). A scaling law between the saturation at the percolation threshold and g/Wt allows delineating the three regimes in agreement with theoretical argument of the percolation in a gradient.

Bo, Z.; Loggia, D.; Xiaorong, L.; Vasseur, G.; Ping, H.

2006-04-01

412

Estimation of percolation flux from borehole temperature data at Yucca Mountain, Nevada.  

PubMed

Temperature data from the unsaturated zone (UZ) at Yucca Mountain are analyzed to estimate percolation-flux rates and overall heat flux. A multilayer, one-dimensional analytical solution is presented for determining percolation flux from temperature data. Case studies have shown that the analytical solution agrees very well with results from the numerical code, TOUGH2. The results of the analysis yield percolation fluxes in the range from 0 to 20 mm/year for most of the deep boreholes. This range is in good agreement with the results of infiltration studies at Yucca Mountain. Percolation flux for the shallower boreholes, however, cannot be accurately determined from temperature data alone because large gas flow in the shallow system alters the temperature profiles. Percolation-flux estimates for boreholes located near or intersecting major faults are significantly higher than those for other boreholes. These estimates may be affected by gas flow in the faults. PMID:12714282

Bodvarsson, G S; Kwicklis, E; Shan, C; Wu, Y S

413

Regeneration of ammonia borane spent fuel  

SciTech Connect

A necessary target in realizing a hydrogen (H{sub 2}) economy, especially for the transportation sector, is its storage for controlled delivery, presumably to an energy producing fuel cell. In this vein, the U.S. Department of Energy's Centers of Excellence (CoE) in Hydrogen Storage have pursued different methodologies, including metal hydrides, chemical hydrides, and sorbents, for the expressed purpose of supplanting gasoline's current > 300 mile driving range. Chemical H{sub 2} storage has been dominated by one appealing material, ammonia borane (H{sub 3}N-BH{sub 3}, AB), due to its high gravimetric capacity of H{sub 2} (19.6 wt %) and low molecular weight (30.7 g mol{sup -1}). In addition, AB has both hydridic and protic moieties, yielding a material from which H{sub 2} can be readily released in contrast to the loss of H{sub 2} from C{sub 2}H{sub 6} which is substantially endothermic. As such, a number of publications have described H{sub 2} release from amine boranes, yielding various rates depending on the method applied. The viability of any chemical H{sub 2} storage system is critically dependent on efficient recyclability, but reports on the latter subject are sparse, invoke the use of high energy reducing agents, and suffer from low yields. Our group is currently engaged in trying to find and fully demonstrate an energy efficient regeneration process for the spent fuel from H{sub 2} depleted AB with a minimum number of steps. Although spent fuel composition depends on the dehydrogenation method, we have focused our efforts on the spent fuel resulting from metal-based catalysis, which has thus far shown the most promise. Metal-based catalysts have produced the fastest rates for a single equivalent of H{sub 2} released from AB and up to 2.5 equiv. of H{sub 2} can be produced within 2 hours. While ongoing work is being carried out to tailor the composition of spent AB fuel, a method has been developed for regenerating the predominant product, polyborazylene (PB) which can be obtained readily from the decomposition of borazine or from nickel carbene catalyst dehydrogenation. In this cycle, the PB is digested with benzenedithiol to yield two products which can both be converted to AB using Bu{sub 3}SnH and BU{sub 2}SnH{sub 2} as reductants. However, in a real world situation the process becomes more complicated for several reasons. Bu{sub 2}SnH{sub 2} is thermally unstable and therefore not viable in a process scale operation. This has led to the development of Bu{sub 3}SnH as the sole reductant although this requires an additional amine exchange step in order to facilitate the reduction to an amine-borane which can then be converted to AB. The tin by-products also need to be recycled in order to maximize the overall energy efficiency and therefore minimize the overall cost of the process. In addition, on an industrial scale, the mass of the tin reductant generates significant cost due to the manipulation of the relatively large quantities involved so reducing the mass at this stage would be of vast significance. We will discuss further developments made to the tin recycle component of the cycle (including methods to minimize tin usage) and investigate new methods of reduction of the digested products, primarily focusing on lighter reductants, including lighter analogs of Bu{sub 2}SnH{sub 2} and Bu{sub 3}SnH. These advances will have a significant impact on the cost of production and therefore the viability of AB as a fuel. Minimization of tin reagents and their recycle will contribute to reduction of the overall cost of AB regeneration and all stages of AB regeneration have been demonstrated.

Sutton, Andrew David [Los Alamos National Laboratory; Davis, Benjamin L [Los Alamos National Laboratory; Gordon, John C [Los Alamos National Laboratory

2009-01-01

414

Process for ammonia syngas manufacture  

SciTech Connect

This patent describes an improved process for reforming hydrocarbons to obtain a synthesis gas containing an approximately stoichiometric amount of hydrogen and nitrogen from which ammonia may be formed in which a hydrocarbon is reacted with steam and air in a reforming operation to obtain a first effluent. This effluent consists of hydrogen, nitrogen and carbon monoxide. The carbon monoxide is reacted in a shift conversion stage to produce a second effluent consisting of hydrogen, nitrogen, and carbon dioxide. The improved process has the additional steps of separating the second effluent into a first stream and a second stream. The first stream is reacted with air in a fuel cell to produce a byproduct stream and a product stream which is passed through a de-oxygenation stage to produce a purified stream. The second stream and the purified stream is passed into a pressure swing adsorption unit in which the synthesis gas and a waste fuel stream are separated.

Jungerhans, R.R.J.

1986-03-25

415

A model of plastics recycling: Does recycling reduce the amount of waste?  

Microsoft Academic Search

A model for recycling plastics is made to ‘phase in’ recycling over a given period. The recycled plastic can either replace virgin plastic or enter a new market where plastics are not normally used. The former is denoted as ‘true recycling’ and the latter, ‘new market recycling’. It is shown that ‘true recycling’ will eventually reduce the amount of waste

Brenton L. Fletcher; Michael E. Mackay

1996-01-01

416

Bubble expansion, gas percolation and preservation of pyroclasts (Invited)  

NASA Astrophysics Data System (ADS)

Prior to eruption, almost all magmas contained enough dissolved water and carbon dioxide to vesiculate at atmospheric pressure into foams with gas volume fractions greater than 95%. However, such high-vesicularity volcanic foams, called reticulite, are rare and form primarily in high lava fountains of crystal-poor basalt. Most eruptions produce pyroclasts of 65-85% vesicularity as well as ash formed by complete fragmentation of magma, often at the scale of individual bubbles. For this reason, the amount of ash produced is commonly taken as a measure of fragmentation efficiency. Here we re-examine this concept by considering the roles of both permeability and isolated bubbles in magma expansion and fragmentation. Syn-eruptive magma expansion requires that gas in the component bubbles expands due to decompression and volatile exsolution faster than it escapes by permeable flow through pathways of interconnected bubbles. Much like a hole in a balloon can make it impossible to inflate, an increase in permeability will halt or drastically slow down magma expansion despite continued decompression and degassing. Evidence for permeability increases ? 2 orders of magnitude across a threshold vesicularity (e.g., Eichelberger et al., 1986) would further suggest that pyroclasts should preserve vesicularities that are close to this threshold. Observed pumice vesicularities of 65-85% are consistent with laboratory studies indicating gas percolation thresholds of ? 60%; however, numerous permeability measurements from other suites of volcanic samples suggest percolation thresholds much lower than 60%. We review these findings in the context of percolation theory, consider reasons for apparent discrepancies in the data, and discuss implications for conditions of vesiculation during volcanic eruptions. We then re-evaluate the conditions required for bubble expansion and reticulite development. In particular, a comparisons of basaltic scoria and reticulite suggests that these two clast types have different vesiculation histories, with proto-reticulite having less-well-connected bubbles than scoria of the same vesicularity. We assess the implications for fragmentation and eruption dynamics, and potential biases in inferring magma properties from studies of relatively large pyroclasts. Central to our argument is that preserved scoria and pumice clasts were too permeable to expand further, and, as suggested by Witham and Sparks (1986) and Klug and Cashman (1996), bubble connectivity is key to the preservation of pumice. In particular, we conclude that reticulite cannot form in explosive rhyolite eruptions because closed-system degassing at the relevant decompression rates leads to stresses sufficient to fragment the magma into ash. This interpretation is consistent with the observed correlation between the intensity of (sub)Plinian eruptions and the proportion of ash relative to pumice erupted (Walker 1973, 1980).

Rust, A.; Cashman, K. V.; Wright, H. M.

2009-12-01

417

Emulsified industrial oils recycling  

SciTech Connect

The industrial lubricant market has been analyzed with emphasis on current and/or developing recycling and re-refining technologies. This task has been performed for the United States and other industrialized countries, specifically France, West Germany, Italy and Japan. Attention has been focused at emulsion-type fluids regardless of the industrial application involved. It was found that emulsion-type fluids in the United States represent a much higher percentage of the total fluids used than in other industrialized countries. While recycling is an active matter explored by the industry, re-refining is rather a result of other issues than the mere fact that oil can be regenerated from a used industrial emulsion. To extend the longevity of an emulsion is a logical step to keep expenses down by using the emulsion as long as possible. There is, however, another important factor influencing this issue: regulations governing the disposal of such fluids. The ecological question, the respect for nature and the natural balances, is often seen now as everybody's task. Regulations forbid dumping used emulsions in the environment without prior treatment of the water phase and separation of the oil phase. This is a costly procedure, so recycling is attractive since it postpones the problem. It is questionable whether re-refining of these emulsions - as a business - could stand on its own if these emulsions did not have to be taken apart for disposal purposes. Once the emulsion is separated into a water and an oil phase, however, re-refining of the oil does become economical.

Gabris, T.

1982-04-01

418

Recycled rubber roads  

SciTech Connect

The paper describes several innovative approaches for recycling old tires in the construction of roads. In one, 18 inches of shredded tire chips (2 X 2 inches) were used on top of 6-8 inches of small stone to construct a road across a sanitary landfill. No compacting or linders were needed. In another application, sidewall mats linked together with steel strapping were used as a sub-base for a road across a swampy area. A third application uses 1/2 inch bits of groundup rubber tires as a replacement for aggregate in an asphalt road base.

Not Available

1989-02-01

419

Energy and Recycling  

NSDL National Science Digital Library

Energy and Garbage is one section of a US Department of Energy's educational Web site for kids. Features of this Web site include a section detailing the connection between energy and garbage, a thorough introduction to the history of garbage that includes facts and figures on how much waste we produce, information on recycling and reducing garbage at the source, and much more. The information in this Web site is presented in a friendly, narrative style. A short downloadable activity titled Energy from Garbage, created by the National Energy Education Development Project, is also available (grades 4-6).

420

Recycling and Composting  

NSDL National Science Digital Library

In this lesson, students learn about the value renewable resources hold for our society and the broader community of living things. Because trees, fresh water, and clean air support most forms of life, we must protect these and other critical natural resources from over exploitation and pollution. Conservation, the practice of using natural resources in a way that ensures their continuing availability to future generations, is one approach. Through class discussion and various activities, students broaden their understanding of two important conservation activities that humans can engage in: recycling and composting.

Foundation, Wgbh E.

2009-07-13

421

Modernizing the assay for ammonia in pharmaceuticals.  

PubMed

The United States Pharmacopeia USP35-NF30 contains monographs for adenosine and sodium bicarbonate with imprecise and outdated color comparison assays for ammonia. In the spirit of monograph modernization we developed ion chromatography (IC) assays for ammonia that meet the requirements of the adenosine and sodium bicarbonate monographs. Ammonia, as ammonium, in a solution of adenosine is separated on a high-performance cation-exchange column and detected by suppressed conductivity. This assay requires <5min per sample and accurately determines the ammonia content of adenosine. For sodium bicarbonate a different IC method was required to determine ammonia due to the high concentration of sodium relative to ammonia in a sodium bicarbonate solution. This assay uses a high-capacity cation-exchange column that has the appropriate selectivity for determining low concentrations of ammonia in the presence of high concentrations of sodium. For both the methods, the precisions (retention time RSD<0.1%, peak area RSD<2.3%), accuracy (average recovery 70-117), limits of detection (LOD) and quantitation (LOQ), and robustness were measured according to the analytical performance requirements described in USP General Chapter <1225>. PMID:24001904

Basumallick, Lipika; Rohrer, Jeffrey S

2013-08-14

422

INFRARED SPECTRA OF AMMONIA-WATER ICES  

SciTech Connect

We conducted a systematic study of the near-IR and mid-IR spectra of ammonia-water ices at various NH{sub 3}/H{sub 2}O ratios. The differences between the spectra of amorphous and crystalline ammonia-water ices were also investigated. The 2.0 {mu}m ammonia band central wavelength is a function of the ammonia/water ratio. It shifts from 2.006 {+-} 0.003 {mu}m (4985 {+-} 5 cm{sup -1}) to 1.993 {+-} 0.003 {mu}m (5018 {+-} 5 cm{sup -1}) as the percentage of ammonia decreases from 100% to 1%. The 2.2 {mu}m ammonia band center shifts from 2.229 {+-} 0.003 {mu}m (4486 {+-} 5 cm{sup -1}) to 2.208 {+-} 0.003 {mu}m (4528 {+-} 5 cm{sup -1}) over the same range. Temperature-dependent shifts of those bands are below the uncertainty of the measurement, and therefore are not detectable. These results are important for comparison with astronomical observations as well as for estimating the concentration of ammonia in outer solar system ices.

Zheng Weijun; Jewitt, David [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Kaiser, Ralf I. [Department of Chemistry, University of Hawaii, Honolulu, HI 96822 (United States)], E-mail: jewitt@ifa.hawaii.edu, E-mail: ralfk@hawaii.edu, E-mail: zhengwj@iccas.ac.cn

2009-03-15

423

Depletion of Ammonia Gas onto Jovian Ices  

NASA Astrophysics Data System (ADS)

The altitude profile of ammonia in Jupiter’s atmosphere, as constrained by microwave spectra, is poorly understood. The microwave spectrum of Jupiter is consistent with supersolar ammonia deeper than 6 bar, and subsolar ammonia at pressures less than 2 bar. In addition, the Galileo Probe Mass Spectrometer measured a deep NH3/H2 mixing ratio of approximately five times the protosolar ratio. Consequently, a global-scale depletion mechanism for ammonia gas can be anticipated, operating between the 2 and 6 bar levels. Candidate depletion mechanisms include dynamics, condensation of species with higher nitrogen fractions than NH4SH (including clathrates), and adsorption of ammonia onto NH4SH or water ices. Measured uptake coefficients of ammonia provide valuable constraints for model calculations testing the ammonia depletion hypothesis in Jupiter’s atmosphere. We have begun laboratory experiments designed to measure the uptake of ammonia by H2O and H2O-NH4SH ice mixtures with a Knudsen cell apparatus in the temperature range 130-250 K. These conditions are appropriate to the troposphere of Jupiter around the 2-4 bar pressure level. Initial results show that the uptake coefficient is larger than 10-4 in this temperature range. We also plan model calculations to apply the experimental results to Jupiter's atmosphere and will discuss the key parameters and processes that influence the ammonia uptake and their relevance to Jupiter's atmosphere. This work is supported by the NASA Planetary Atmospheres Program under grant NNX09AB69G.

Kasper, T.; Wong, M. H.; Marschall, J.; de Pater, I.; Romani, P. N.; Kalogerakis, K.

2010-12-01

424

State Strategy for Recycling Market Development.  

National Technical Information Service (NTIS)

The ultimate importance of developing recycling markets is to accomplish these five objectives: Assist local governments and state offices in achieving the recycling goals in the SCORE (Select Committee on Recycling and the Environment) legislation throug...

L. Millberg

1991-01-01

425

No Objection Letter for Recycled Plastics #0041  

Center for Food Safety and Applied Nutrition (CFSAN)

... bags are an acceptable use of recycled plastic. ... of recycled HDPE in produce bags is acceptable ... use of post-consumer recycled plastics in contact ... More results from www.fda.gov/food/ingredientspackaginglabeling/packagingfcs

426

40 CFR 141.76 - Recycle provisions.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Recycle provisions. 141.76 Section 141...Filtration and Disinfection § 141.76 Recycle provisions. (a) Applicability...or direct filtration treatment and that recycle spent filter backwash water,...

2010-07-01

427

40 CFR 141.76 - Recycle provisions.  

Code of Federal Regulations, 2010 CFR

...and Disinfection] [Sec. 141.76 - Recycle provisions.] 40 PROTECTION OF ENVIRONMENT...Filtration and Disinfection Sec. 141.76 Recycle provisions. (a) Applicability. All...or direct filtration treatment and that recycle spent filter backwash water,...

2009-07-01

428

40 CFR 141.76 - Recycle provisions.  

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false Recycle provisions. 141.76 Section 141...Filtration and Disinfection § 141.76 Recycle provisions. (a) Applicability...or direct filtration treatment and that recycle spent filter backwash water,...

2012-07-01

429

16 CFR 260.12 - Recyclable claims.  

Code of Federal Regulations, 2013 CFR

...the waste stream through an established recycling program for reuse or use in manufacturing...deception about the availability of recycling programs and collection sites to consumers. (1) When recycling facilities are available to a...

2013-01-01

430

76 FR 71861 - America Recycles Day, 2011  

Federal Register 2010, 2011, 2012, 2013

...advanced the common good of our Nation by recycling regularly and promoting conservation...growth. Since then, we have bolstered recycling programs through individual action...we must update and expand existing recycling programs and dedicate ourselves to...

2011-11-18

431

Zipf's law in nuclear multifragmentation and percolation theory  

SciTech Connect

We investigate the average sizes of the n largest fragments in nuclear multifragmentation events near the critical point of the nuclear matter phase diagram. We perform analytic calculations employing Poisson statistics as well as Monte Carlo simulations of the percolation type. We find that previous claims of manifestations of Zipf's Law in the rank-ordered fragment size distributions are not borne out in our result, in neither finite nor infinite systems. Instead, we find that Zipf-Mandelbrot distributions are needed to describe the results, and we show how one can derive them in the infinite size limit. However, we agree with previous authors that the investigation of rank-ordered fragment size distributions is an alternative way of looking for the critical point in the nuclear matter diagram.

Paech, Kerstin; Bauer, Wolfgang; Pratt, Scott [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-2320 (United States)

2007-11-15

432

Finite-size scaling theory for explosive percolation transitions.  

PubMed

The finite-size scaling (FSS) theory for continuous phase transitions has been useful in determining the critical behavior from the size-dependent behaviors of thermodynamic quantities. When the phase transition is discontinuous, however, FSS approach has not been well established yet. Here, we develop a FSS theory for the explosive percolation transition arising in the Erd?s and Rényi model under the Achlioptas process. A scaling function is derived based on the observed fact that the derivative of the curve of the order parameter at the critical point t(c) diverges with system size in a power-law manner, which is different from the conventional one based on the divergence of the correlation length at t(c). We show that the susceptibility is also described in the same scaling form. Numerical simulation data for different system sizes are well collapsed on the respective scaling functions. PMID:21230331

Cho, Y S; Kim, S-W; Noh, J D; Kahng, B; Kim, D

2010-10-08

433

Percolation and Burgers' dynamics in a model of capillary formation  

NASA Astrophysics Data System (ADS)

Capillary networks are essential in vertebrates to supply tissues with nutrients. Experiments of in vitro capillary formation show that cells randomly spread on a gel matrix autonomously organize to form vascular networks. Cells form disconnected networks at low densities and connected ones above a critical density. Above the critical density the network is characterized by a typical mesh size ˜200 ?m , which is approximately constant on a wide range of density values. In this paper we present a full characterization of a recently proposed model which reproduces the main features of the biological system, focusing on its dynamical properties, on the fractal properties of patterns, and on the percolative phase transition. We discuss the relevance of the model in relation with some experiments in living beings and proposed diagnostic methods based on the measurement of the fractal dimension of vascular networks.

Coniglio, A.; de Candia, A.; di Talia, S.; Gamba, A.

2004-05-01

434

Bond and Site Percolation and Habitat Destruction in Model Ecosystems  

NASA Astrophysics Data System (ADS)

Habitat destruction is one of the primary causes of species extinction. In the present article, we apply bond and site destructions to a prey-predator system. Predator reproduction is disturbed by these destructions, while prey sustains no direct damage. It is found for both bond and site destructions that the number of predators increases in spite of the increase in destruction. However, if the destruction is too great, the predators decreases and eventually goes extinct. The mean-field theories for both type of destruction predict the same extinction threshold values. In contrast, the simulations for bond and site destructions reveal that extinction thresholds are much smaller than the mean-field theory predicts. This may be the result of the fragmentation of habitat via the percolation of habitat destruction.

Nakagiri, Nariyuki; Tainaka, Kei-ichi; Yoshimura, Jin

2005-12-01

435

Algorithm to determine the percolation largest component in interconnected networks  

NASA Astrophysics Data System (ADS)

Interconnected networks have been shown to be much more vulnerable to random and targeted failures than isolated ones, raising several interesting questions regarding the identification and mitigation of their risk. The paradigm to address these questions is the percolation model, where the resilience of the system is quantified by the dependence of the size of the largest cluster on the number of failures. Numerically, the major challenge is the identification of this cluster and the calculation of its size. Here, we propose an efficient algorithm to tackle this problem. We show that the algorithm scales as O(NlogN), where N is the number of nodes in the network, a significant improvement compared to O(N2) for a greedy algorithm, which permits studying much larger networks. Our new strategy can be applied to any network topology and distribution of interdependencies, as well as any sequence of failures.

Schneider, Christian M.; Araújo, Nuno A. M.; Herrmann, Hans J.

2013-04-01

436

Emergent spin excitations in a bethe lattice at percolation.  

PubMed

We study the spin-1/2 quantum Heisenberg antiferromagnet on a Bethe lattice diluted to the percolation threshold. Dilution creates areas of even or odd sublattice imbalance resulting in "dangling spins" [L. Wang and A.?W. Sandvik, Phys. Rev. Lett. 97, 117204 (2006); Phys. Rev. B 81, 054417 (2010)]. These collectively act as "emergent" spin-1/2 degrees of freedom and are responsible for the creation of a set of low-lying "quasidegenerate states." Using density matrix renormalization group calculations, we detect the presence and location of these emergent spins. We find an effective Hamiltonian of these emergent spins, with Heisenberg interactions that decay exponentially with the distance between them. PMID:24160622

Changlani, Hitesh J; Ghosh, Shivam; Pujari, Sumiran; Henley, Christopher L

2013-10-07

437

[Impact of liquid volume of recycled methanogenic effluent on anaerobic hydrolysis].  

PubMed

Methanogenic effluent was recycled to regulate hydrolysis during two-phase anaerobic digestion of organic solid wastes. In order to study the impact of recycled effluent's volume on hydrolysis, four hydrolysis reactors filled with vegetable and flower wastes were constructed, with different liquid volumes of recycled methanogenic effluent, i.e., 0.1, 0.5, 1.0, 2.0 m3/(m3 x d), respectively. The parameters related to hydrolytic environment (pH, alkalinity, ORP, concentrations of ammonia and reducing sugar), microbial biomass and hydrolysis efficiency (accumulated SCOD, accumulated reducing sugar, and hydrolysis rate constants) were monitored. This research shows that recycling methanogenic effluent into the hydrolysis reactor can enhance its buffer capability and operation stability; higher recycled volume is favorable for microbial anabolism and further promotes hydrolysis. After 9 days of reaction, the accumulated SCOD in the hydrolytic effluent reach 334, 407, 413, 581 mg/g at recycled volumes of 0.1, 0.5, 1.0, 2.0 m3/(m3 x d) and their first-order hydrolysis rate kinetic constants are 0.065, 0.083, 0.089, 0.105 d(-1), respectively. PMID:19068657

Hao, Li-ping; Lü, Fan; He, Pin-jing; Shao, Li-ming

2008-09-01

438

A Cube Dismantling Problem Related to Bootstrap Percolation  

NASA Astrophysics Data System (ADS)

An n× n×⋯× n hypercube is made from n d unit hypercubes. Two unit hypercubes are neighbours if they share a ( d-1)-dimensional face. In each step of a dismantling process, we remove a unit hypercube that has precisely d neighbours. A move is balanced if the neighbours are in d orthogonal directions. In the extremal case, there are n d-1 independent unit hypercubes left at the end of the dismantling. We call this set of hypercubes a solution. If a solution is projected in d orthogonal directions and we get the entire [ n] d-1 hypercube in each direction, then the solution is perfect. We show that it is possible to use a greedy algorithm to test whether a set of hypercubes forms a solution. Perfect solutions turn out to be precisely those which can be reached using only balanced moves. Every perfect solution corresponds naturally to a Latin hypercube. However, we show that almost all Latin hypercubes do not correspond to solutions. In three dimensions, we find at least n perfect solutions for every n, and we use our greedy algorithm to count the perfect solutions for n?6. We also construct an infinite family of imperfect solutions and show that the total size of its three orthogonal projections is asymptotic to the minimum possible value. Our results solve several conjectures posed in a proceedings paper by Barát, Korondi and Varga. If our dismantling process is reversed we get a build-up process very closely related to well-studied models of bootstrap percolation. We show that in an important special case our build-up reaches the same maximal position as bootstrap percolation.

Barát, János; Wanless, Ian M.

2012-11-01

439

Scaling and percolation in the small-world network model  

SciTech Connect

In this paper we study the small-world network model of Watts and Strogatz, which mimics some aspects of the structure of networks of social interactions. We argue that there is one nontrivial length-scale in the model, analogous to the correlation length in other systems, which is well-defined in the limit of infinite system size and which diverges continuously as the randomness in the network tends to zero, giving a normal critical point in this limit. This length-scale governs the crossover from large- to small-world behavior in the model, as well as the number of vertices in a neighborhood of given radius on the network. We derive the value of the single critical exponent controlling behavior in the critical region and the finite size scaling form for the average vertex-vertex distance on the network, and, using series expansion and Pade approximants, find an approximate analytic form for the scaling function. We calculate the effective dimension of small-world graphs and show that this dimension varies as a function of the length-scale on which it is measured, in a manner reminiscent of multifractals. We also study the problem of site percolation on small-world networks as a simple model of disease propagation, and derive an approximate expression for the percolation probability at which a giant component of connected vertices first forms (in epidemiological terms, the point at which an epidemic occurs). The typical cluster radius satisfies the expected finite size scaling form with a cluster size exponent close to that for a random graph. All our analytic results are confirmed by extensive numerical simulations of the model. (c) 1999 The American Physical Society.

Newman, M. E. J. [Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States); Watts, D. J. [Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501 (United States)

1999-12-01

440

Recycling Solid Waste in Chattanooga  

ERIC Educational Resources Information Center

|Students undertook a group project in collaboration with city officials to study garbage types in the community and possibilities of recycling solid wastes. Data collected from various sources revealed that public attitude was favorable for recycling efforts and that it was feasible economically. (PS)|

Vredeveld, Ruth; Martin, Robin

1973-01-01

441

Garbage project on recycling behavior  

SciTech Connect

Results are presented of a study undertaken to determine the factors which are most effective in motivating different socio-economic groups to change their recycling behaviors and participate in recycling programs. Four types of data were collected and analyzed in Tucson: (1) purchase data from local recyclers, (2) traditional interview-survey data on recycling behavior, (3) long-term and short-term household refuse data, and (4) combined interview-garbage data. Findings reveal that disposal patterns for newspapers and aluminum cans are tuse data, and (4) combined interview-garbage data. Findings reveal that disposal patterns for newspapers and aluminum cans are the same across census tracts with significantly different socio-economic characteristics. Further, analysis of interview and garbage data matched by household reaffirm that what people say about recycling and how they dispose of recyclable materials are two different things. Thus, interview reports of newspaper recycling correlate with higher income informants, but their interview reports do not correlate with what is thrown into their garbage cans. Money is concluded to be the most powerful incentive toward recycling.

McGuire, R.H.; Hughes, W.W.; Rathje, W.L.

1982-02-01

442

Recycling oceanic crust: Quantitative constraints  

Microsoft Academic Search

Recycled ancient oceanic crust with variable amounts of aging, or inclusion of sediments of differing types and origins has often been invoked as a source for present-day ocean island basalts (OIB), but the current evidence remains largely qualitative. Previous quantitative modeling has shown that much has to be learned in order to better understand the implications of crustal recycling on

Andreas Stracke; Michael Bizimis; Vincent J. M. Salters

2003-01-01

443

MAGNESIUM RECYCLING YESTERDAY, TODAY, TOMORROW  

Microsoft Academic Search

Magnesium recycling has been used to recover both new scrap and old scrap. It was used extensively in Germany during WWII to expand the magnesium supply. There were a large number of magnesium recyclers in the US who got their start smelting old scrap, old airplanes and old waste dumps from the WWII build up. As the world magnesium industry

Robert E. Brown

444

Recycling TATB PBX. [Machining scrap  

Microsoft Academic Search

The feasibility of recycling IHE has been successfully demonstrated on a large scale by processing over 750 kg of machining scrap. The content of machine cuttings in the recycled PBX lots was 50, 75, and 100%. Physical strengths were generally above normal and tensile strains were 0.29% or better.

A. G. Osborn; T. L. Stallings; H. D. Johnson

1978-01-01

445

Plastic recycling in business machines  

Microsoft Academic Search

A process was developed and implemented for the recovery and recycling of plastics from end-of-life IBM products into new IBM products. In general, the economics for this type of recycling, closed loop, has the greatest potential for achieving profitability. In addition to keeping the plastic out of the landfill, product material cost is reduced and there is no expense for

S. Ching; J. R. Kirby; O. D. Pitts

1993-01-01

446

Recycling Study Guide [Resource Packet].  

ERIC Educational Resources Information Center

|This resource packet contains six documents developed by the Wisconsin Department of Natural Resources in order to help teachers infuse the environmental education topics of recycling and solid waste into social studies, art, English, health, mathematics, science, and environmental education classes. "Recycling Study Guide" contains 19 activities…

Wisconsin State Dept. of Natural Resources, Madison.

447

Bacterial cell-wall recycling.  

PubMed

Many Gram-negative and Gram-positive bacteria recycle a significant proportion of the peptidoglycan components of their cell walls during their growth and septation. In many--and quite possibly all--bacteria, the peptidoglycan fragments are recovered and recycled. Although cell-wall recycling is beneficial for the recovery of resources, it also serves as a mechanism to detect cell-wall-targeting antibiotics and to regulate resistance mechanisms. In several Gram-negative pathogens, anhydro-MurNAc-peptide cell-wall fragments regulate AmpC ?-lactamase induction. In some Gram-positive organisms, short peptides derived from the cell wall regulate the induction of both ?-lactamase and ?-lactam-resistant penicillin-binding proteins. The involvement of peptidoglycan recycling with resistance regulation suggests that inhibitors of the enzymes involved in the recycling might synergize with cell-wall-targeted antibiotics. Indeed, such inhibitors improve the potency of ?-lactams in vitro against inducible AmpC ?-lactamase-producing bacteria. We describe the key steps of cell-wall remodeling and recycling, the regulation of resistance mechanisms by cell-wall recycling, and recent advances toward the discovery of cell-wall-recycling inhibitors. PMID:23163477

Johnson, Jarrod W; Fisher, Jed F; Mobashery, Shahriar

2012-11-16

448

Recycling Study Guide [Resource Packet].  

ERIC Educational Resources Information Center

This resource packet contains six documents developed by the Wisconsin Department of Natural Resources in order to help teachers infuse the environmental education topics of recycling and solid waste into social studies, art, English, health, mathematics, science, and environmental education classes. "Recycling Study Guide" contains 19 activities…

Wisconsin State Dept. of Natural Resources, Madison.

449

Vehicle fluids: The other recycling  

Microsoft Academic Search

Recycling is no longer limited to paper and various types of plastics and metals. Many truck and automotive fluids, including antifreeze, are also recycled regularly throughout the US. Antifreeze is used today in almost every type of internal combustion engine. Whether the fuel is gasoline, diesel, propane, or natural gas, almost all engines need to use a liquid medium to

Walther

1994-01-01

450

A feasibility study of implementing an Ammonia Economy  

Microsoft Academic Search

This thesis reports the results of a feasibility study performed on the concept of an Ammonia Economy, which treats ammonia as an alternative fuel and energy storage mechanism. As part of the Ammonia Economy, costs for production, storage, and transportation of this alternative fuel are also presented. The cost of hydrogen, which is the main feedstock for ammonia production, was

Jeffrey Ralph Bartels

2008-01-01

451

AMMONIA EFFECTS ON MICROINVERTEBRATES AND FISH IN OUTDOOR EXPERIMENTAL STREAMS  

EPA Science Inventory

Laboratory data on ammonia effects, the US EPA national water quality criteria for ammonia, and ammonia site-specific criteria were evaluated in four outdoor experimental streams (one control and three treatment streams) over a 76-week period. Calculated un-ionized ammonia concen...

452

No Objection Letter for Recycled Plastics #153  

Center for Food Safety and Applied Nutrition (CFSAN)

... Packaging & Food Contact Substances (FCS). Recycled Plastics. -. No Objection Letter for Recycled Plastics #153. August 24, 2011. ... More results from www.fda.gov/food/ingredientspackaginglabeling/packagingfcs

453

No Objection Letter for Recycled Plastics #166  

Center for Food Safety and Applied Nutrition (CFSAN)

... Packaging & Food Contact Substances (FCS). Recycled Plastics. -. No Objection Letter for Recycled Plastics #166. March 25, 2013. ... More results from www.fda.gov/food/ingredientspackaginglabeling/packagingfcs

454

Percolation, phase separation, and gelation in fluids and mixtures of spheres and rods  

NASA Astrophysics Data System (ADS)

The relationship between kinetic arrest, connectivity percolation, structure and phase separation in protein, nanoparticle, and colloidal suspensions is a rich and complex problem. Using a combination of integral equation theory, connectivity percolation methods, naïve mode coupling theory, and the activated dynamics nonlinear Langevin equation approach, we study this problem for isotropic one-component fluids of spheres and variable aspect ratio rigid rods, and also percolation in rod-sphere mixtures. The key control parameters are interparticle attraction strength and its (short) spatial range, total packing fraction, and mixture composition. For spherical particles, formation of a homogeneous one-phase kinetically stable and percolated physical gel is predicted to be possible, but depends on non-universal factors. On the other hand, the dynamic crossover to activated dynamics and physical bond formation, which signals discrete cluster formation below the percolation threshold, almost always occurs in the one phase region. Rods more easily gel in the homogeneous isotropic regime, but whether a percolation or kinetic arrest boundary is reached first upon increasing interparticle attraction depends sensitively on packing fraction, rod aspect ratio and attraction range. Overall, the connectivity percolation threshold is much more sensitive to attraction range than either the kinetic arrest or phase separation boundaries. Our results appear to be qualitatively consistent with recent experiments on polymer-colloid depletion systems and brush mediated attractive nanoparticle suspensions.

Jadrich, Ryan; Schweizer, Kenneth S.

2011-12-01

455

Factors affecting water balance and percolate production for a landfill in operation.  

PubMed

Percolate production and precipitation data for a full-scale landfill in operation measured over a 13-year period were used to evaluate the impact and importance of the hydrological conditions of landfill sections on the percolate production rates. Both active (open) and closed landfill sections were included in the evaluation. A simple top cover model requiring a minimum of input data was used to simulate the percolate production as a function of precipitation and landfill section hydrology. The results showed that changes over time in the hydrology of individual landfill sections (such as section closure or plantation of trees on top of closed sections) can change total landfill percolate production by more than 100%; thus, percolate production at an active landfill can be very different from percolate production at the same landfill after closure. Furthermore, plantation of willow on top of closed sections can increase the evapotranspiration rate thereby reducing percolate production rates by up to 47% compared to a grass cover. This process, however, depends upon the availability of water in the top layer, and so the evaporation rate will be less than optimal during the summer where soil-water contents in the top cover are low. PMID:15751398

Poulsen, Tjalfe G; Møoldrup, Per

2005-02-01

456

Percolation transition of short-ranged square well fluids in bulk and confinement.  

PubMed

Using grand canonical Monte Carlo simulations, we investigate the percolation behavior of a square-well fluid with an ultra-short range of attraction in three dimension (3D) and in confined geometry. The latter is defined through two parallel and structureless walls (slit-pore). We focus on temperatures above the critical temperature of the (metastable) condensation transition of the 3D system. Investigating a broad range of systems sizes, we first determine the percolation thresholds, i.e., the critical packing fraction for percolation ?(c). For the slit-pore systems, ?(c) is found to vary with the wall separation L(z) in a continuous but non-monotonic way, ?(c)(L(z)??)=?(c)(3D). We also report results for critical exponents of the percolation transition, specifically, the exponent ? of the correlation length ? and the two fisher exponents ? and ? of the cluster-size distribution. These exponents are obtained from a finite-size analysis involving the cluster-size distribution and the radii of gyration distribution at the percolation threshold. Within the accuracy of our simulations, the values of the critical exponents of our 3D system are comparable to those of 3D random percolation theory. For narrow slit-pores, the estimated exponents are found to be close to those obtained from the random percolation theory in two dimensions. PMID:23425490

Neitsch, Helge; Klapp, Sabine H L

2013-02-14

457

Two-Dimensional Continuum Percolation Threshold for Diffusing Particles of Nonzero Radius  

PubMed Central

Lateral diffusion in the plasma membrane is obstructed by proteins bound to the cytoskeleton. The most important parameter describing obstructed diffusion is the percolation threshold. The thresholds are well known for point tracers, but for tracers of nonzero radius, the threshold depends on the excluded area, not just the obstacle concentration. Here thresholds are obtained for circular obstacles on the continuum. Random obstacle configurations are generated by Brownian dynamics or Monte Carlo methods, the obstacles are immobilized, and the percolation threshold is obtained by solving a bond percolation problem on the Voronoi diagram of the obstacles. The percolation threshold is expressed as the diameter of the largest tracer that can cross a set of immobile obstacles at a prescribed number density. For random overlapping obstacles, the results agree with the known analytical solution quantitatively. When the obstacles are soft disks with a 1/r12 repulsion, the percolating diameter is ?20% lower than for overlapping obstacles. A percolation model predicts that the threshold is highly sensitive to the tracer radius. To our knowledge, such a strong dependence has so far not been reported for the plasma membrane, suggesting that percolation is not the factor controlling lateral diffusion. A definitive experiment is proposed.

Saxton, Michael J.

2010-01-01

458

Stimulation of thaumarchaeal ammonia oxidation by ammonia derived from organic nitrogen but not added inorganic nitrogen.  

PubMed

Ammonia oxidation, the first step in nitrification, is performed by autotrophic bacteria and thaumarchaea, whose relative contributions vary in different soils. Distinctive environmental niches for the two groups have not been identified, but evidence from previous studies suggests that activity of thaumarchaea, unlike that of bacterial ammonia oxidizers, is unaffected by addition of inorganic N fertilizer and that they preferentially utilize ammonia generated from the mineralization of organic N. This hypothesis was tested by determining the influence of both inorganic and organic N sources on nitrification rate and ammonia oxidizer growth and community structure in microcosms containing acidic, forest soil in which ammonia oxidation was dominated by thaumarchaea. Nitrification rate was unaffected by the incubation of soil with inorganic ammonium but was significantly stimulated by the addition of organic N. Oxidation of ammonia generated from native soil organic matter or added organic N, but not added inorganic N, was accompanied by increases in abundance of the thaumarchaeal amoA gene, a functional gene for ammonia oxidation, but changes in community structure were not observed. Bacterial amoA genes could not be detected. Ammonia oxidation was completely inhibited by 0.01% acetylene in all treatments, indicating ammonia monooxygenase-dependent activity. The findings have implications for current models of soil nitrification and for nitrification control strategies to minimize fertilizer loss and nitrous oxide production. PMID:22150211

Levi?nik-Höfferle, Spela; Nicol, Graeme W; Ausec, Luka; Mandi?-Mulec, Ines; Prosser, James I

2012-01-09

459

Ammonia emissions during vermicomposting of sheep manure.  

PubMed

The effect of C:N ratio, temperature and water content on ammonia volatilization during two-phase composting of sheep manure was evaluated. The aerobic phase was conducted under field conditions. This was followed by Phase II, vermicomposting, conducted in the laboratory under controlled conditions of water content (70% and 80%) and temperature (15 and 22 °C). The addition of extra straw lead to a 10% reduction in NH3 volatilization compared to sheep manure composted without extra straw. Temperature and water content significantly effected ammonia volatilization at 0 day in Phase II, with a water content of 70% and temperature of 22 °C leading to greater losses of ammonia. Nitrogen loss by ammonia volatilization during vermicomposting ranged from 8% to 15% of the initial N content. The addition of extra straw did not result in significant differences in total carbon content following vermicomposting. PMID:21996478

Velasco-Velasco, Joel; Parkinson, Robert; Kuri, Victor

2011-09-22

460

INVESTIGATION OF THE ORION RESEARCH AMMONIA MONITOR  

EPA Science Inventory

The Orion Research ammonia monitor was investigated using the Orion specifications and environmental considerations as a guide. Laboratory tests under controlled environmental conditions showed the electronic stability (drift) to be well within + or - 10 percent of reading over t...

461

Grain Boundary Percolation Modeling of Fission Gas Release in Oxide Fuels  

SciTech Connect

We present a new approach to fission gas release modeling in oxide fuels based on grain boundary network percolation. The method accounts for variability in the bubble growth and coalescence rates on individual grain boundaries, and the resulting effect on macroscopic fission gas release. Two-dimensional representa- tions of fuel pellet microstructures are considered, and the resulting gas release rates are compared with traditional two-stage Booth models, which do not account for long-range percolation on grain boundary net- works. The results show that the requirement of percolation of saturated grain boundaries can considerably reduce the total gas release rates, particularly when gas resolution is considered.

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

2012-05-01

462

Effect of filler auto-assembly on percolation transition in carbon nanotube/polymer composites  

NASA Astrophysics Data System (ADS)

A series of composites with various content of multi-walled carbon nanotubes dispersed in polymer was tested for electrical properties. During isothermal annealing in the melt, dynamic percolation transition induced a tremendous increase in conductivity. The unstable structure also experienced a more than one order of magnitude reduction in percolation threshold. The insulator to conductor transition concurrently became softer, as revealed by a monotonous increase in the critical exponent, gradually departing from the universal value. These large and concomitant changes in percolation transition with annealing time were ascribed to the self-organization of the filler that favors the completion of the conductive network.

Combessis, Anthony; Bayon, Lorrène; Flandin, Lionel

2013-01-01

463

Exact solution of site and bond percolation on small-world networks  

NASA Astrophysics Data System (ADS)

We study percolation on small-world networks, which has been proposed as a simple model of the propagation of disease. The occupation probabilities of sites and bonds correspond to the susceptibility of individuals to the disease, and the transmissibility of the disease respectively. We give an exact solution of the model for both site and bond percolation, including the position of the percolation transition at which epidemic behavior sets in, the values of the critical exponents governing this transition, the mean and variance of the distribution of cluster sizes (disease outbreaks) below the transition, and the size of the giant component (epidemic) above the transition.

Moore, Cristopher; Newman, M. E. J.

2000-11-01

464

A precise determination of the void percolation threshold for two distributions of overlapping spheres  

SciTech Connect

The void percolation threshold is calculated for a distribution of overlapping spheres with equal radii, and for a binary sized distribution of overlapping spheres, where half of the spheres have radii twice as large as the other half. Using systems much larger than previous work, the authors determine a much more precise value for the percolation thresholds and correlation length exponent. The values for the percolation thresholds are shown to be significantly different, in contrast with previous, less precise works that speculated that the threshold might be universal with respect to sphere size distribution.

RINTOUL,MARK DANIEL

2000-01-25

465

Network-Growth Rule Dependence of Fractal Dimension of Percolation Cluster on Square Lattice  

NASA Astrophysics Data System (ADS)

To investigate the network-growth rule dependence of certain geometric aspects of percolation clusters, we propose a generalized network-growth rule introducing a generalized parameter q and we study the time evolution of the network. The rule we propose includes a rule in which elements are randomly connected step by step and the rule recently proposed by Achlioptas et al. [Science 323 (2009) 1453]. We consider the q-dependence of the dynamics of the number of elements in the largest cluster. As q increases, the percolation step is delayed. Moreover, we also study the q-dependence of the roughness and the fractal dimension of the percolation cluster.

Tanaka, Shu; Tamura, Ryo

2013-05-01

466

Response of bacteriorhodopsin thin films to ammonia  

Microsoft Academic Search

The optical response of optical fibres end-coated with bacteriorhodopsin-containing films to ammonia vapour was investigated. Both static absorptance changes and changes in the dynamic parameters of the actinic light-induced photocycle were determined. Simple optical adsorption measurements can be used to detect ammonia with a detection limit of 5ppm and a dynamic range of 10–10,000ppm, over which the response is logarithmic.

S. O. Korposh; Y. P. Sharkan; J. J. Ramsden

2008-01-01

467

Ammonia Concentration in Porcine Ovarian Developing Follicles  

Microsoft Academic Search

An experiment was conducted to investigate pH, osmolality, and the concentration of ammonia, total protein, glutamine and glutamic acid in follicular fluid at different developmental stages (<2, 3-4 and 5-6 mm in diameter) and serum of porcine. The concentrations of ammonia and total protein content were determined with the catalyzed indophenols reaction and the Bradford assay method and read on

K. M. A. Tareq; Ryuichiro Obata; A. G. Miah; Ko-ichi Hammano; Hirotada Tsujii

2005-01-01

468

Ammonia removal from coal dry distillation wastewater  

Microsoft Academic Search

the article used coke oven gas as desorption agent, pilot-scale packed tower as desorption equipment, removed ammonia from wastewater produced by coal dry distillation process. Gas stripping method is a new technology for ammonia removal. Through experiments conducted in the coking plant, when the temperature of wastewater T=85°C, pH=1l.5, the ratio of liquid and gas volume n=550:1 and the addition

Guanghua Wang; Fanjie Gong; Wenbing Li; Yunzhou Lu; Mingdong Sun; Tiejun Liu; Yuhe Liang; Xiaoyuan Li; Zengqiang Huang

2011-01-01

469

Ammonia Policy Context and Future Challenges  

Microsoft Academic Search

Ammonia emissions are major contributors to eutrophication and acidification of ecosystems and secondary PM2.5 concentrations in Europe. Reduction of the ammonia emissions in Europe has been on the agenda for more than a decade, first\\u000a on a national scale, e.g. in Denmark and the Netherlands, followed by international efforts. The latter include the UNECE\\u000a CLRTAP Gothenburg Protocol and EU directives

Till Spranger; Zbigniew Klimont; Michel Sponar; Caroline Raes; Samantha M. H. Baker; Mark A. Sutton; Collin Gillespie; Y. Sim Tang; Helle Vibeke Andersen; Thomas Ellerman; Chris Flechard; Nick J. Hutchings

470

Supercritical ammonia pretreatment of lignocellulosic materials  

SciTech Connect

A pretreatment technique using ammonia in a supercritical or near-critical fluid state was shown to substantially enhance the susceptibility of polysaccharides in lignocellulosics to subsequent hydrolysis by Trichoderma reesei cellulase. Near-theoretical conversion of cellulose and 70-80% conversion of hemicellulose to sugars from supercritical ammonia pretreated hardwoods or agricultural byproducts were obtained with a small dosage of cellulase. This technique was less effective toward softwoods. The pretreatment results are discussed in light of the properties of supercritical fluids.

Chou, Y.C.T.; Scott, C.D. (ed.)

1986-01-01

471

Ammonia and Urea Permeability of Mammalian Aquaporins  

Microsoft Academic Search

The humanaquaporins,AQP3,AQP7, AQP8,AQP9, and possibly AQP10, are permeable to ammonia, and AQP7, AQP9, and possibly AQP3,\\u000a are permeable to urea. In humans, these aquaporins supplement the ammonia transport of the Rhesus (Rh) proteins and the urea\\u000a transporters (UTs). The mechanism by which ammonium is transported by aquaporins is not fully resolved. A comparison of transport\\u000a equations, models, and experimental data

Thomas Litman; Rikke Søgaard; Thomas Zeuthen

472

Percolative diffusion of a dumbbell interstitial defect on a fcc lattice: Calculation of a percolation threshold with use of a series method  

NASA Astrophysics Data System (ADS)

The analogy between electrical conductivity and matter transport holds only in simple cases, where the point defect which is responsible for the diffusion does not alter the shape of the percolating cluster. In the five variants of a model of matter transport by a dumbbell interstitial defect mechanism in fcc alloys, the point defect migrates on a sublattice of coordinance 8 and has only two jump frequencies at its disposal. When the disparity between these frequencies tends to infinity, a percolative regime of diffusion is observed, but the critical threshold arising in the diffusion problem can be identified with a standard percolation one only under restrictive conditions. The present paper evaluates the site percolation threshold pc corresponding to one of the five variants by the usual series method. Extensive computer enumeration yields perimeter polynomials for clusters containing up to 14 sites. A classical analysis by Dlog-Padé approximants to the first two moments of the cluster density function n(s) yields the two critical exponents ?(pc) and ?(pc) associated to the percolation probability and the mean cluster size, respectively, as functions of the (unknown) threshold pc. It is shown further that, using the higher-order moments of the cluster density function n(s), a very tight range for pc can be proposed (0.2775

Bocquet, J. L.

1994-12-01

473

Open-loop recycling: A LCA case study of PET bottle-to-fibre recycling  

Microsoft Academic Search

This study assesses the environmental impact of polyethylene terephthalate (PET) bottle-to-fibre recycling using the methodology of life-cycle assessment (LCA). Four recycling cases, including mechanical recycling, semi-mechanical recycling, back-to-oligomer recycling and back-to-monomer recycling were analysed. Three allocation methods are applied for open-loop recycling, i.e. the “cut-off” approach, the “waste valuation” approach and the “system expansion” approach. Nine environmental impact indicators were

Li Shen; Ernst Worrell; Martin K. Patel

2010-01-01

474

Exploring Waste and Recycling  

NSDL National Science Digital Library

This resource, created by Eleanor Camann of Red Rocks Community College, will introduce students to the concept of sustainability in terms of waste products and recycling practices. The overall premise of the project is to "get students to think critically about which earth materials are used to make things, and where all the waste from both mining and consumption ends up." The activity employs skills in basic mathematics, reasoning and writing. It also crosses disciplines by implementing skills in environmental geology and science. The learning activity only takes about two hours of in-class time and an additional three outside of the classroom. It uses simple materials such as a calculator, periodic table, household scale and digital camera. Lessons plans such as these are supported by a grant under the National Science Foundation's Advanced Technological Education (ATE) program.

Camann, Eleanor

2010-11-09

475

Recycling microcavity optical biosensors.  

PubMed

Optical biosensors have tremendous potential for commercial applications in medical diagnostics, environmental monitoring, and food safety evaluation. In these applications, sensor reuse is desirable to reduce costs. To achieve this, harsh, wet chemistry treatments are required to remove surface chemistry from the sensor, typically resulting in reduced sensor performance and increased noise due to recognition moiety and optical transducer degradation. In the present work, we suggest an alternative, dry-chemistry method, based on O2 plasma treatment. This approach is compatible with typical fabrication of substrate-based optical transducers. This treatment completely removes the recognition moiety, allowing the transducer surface to be refreshed with new recognition elements and thus enabling the sensor to be recycled. PMID:21478993

Hunt, Heather K; Armani, Andrea M

2011-04-01

476

Recycling in Puerto Rico  

SciTech Connect

The commonwealth of Puerto Rico has never had a traditional, centrally organized solid waste management system. In the past, municipalities provided service for their own residents and the island used 62 unlined landfills. In April 1994, 32 of those landfills closed. A study released in 1995 found that residents of Puerto Rico generate 8,100 tons of waste each day, at a per capita rate of 4.9 pounds per day. A solid waste management strategy unveiled with much fanfare early last year included plans to build an integrated system of collection, transfer stations, and disposal sites. These sites would be market-driven by recycling and hinged on partnerships between the public and private sectors and public education. A key to Puerto Rico`s plan was investment by the private sector.

McAdams, C.L.

1996-05-01

477

Ammonia chemistry in a flameless jet  

SciTech Connect

In this paper, the nitrogen chemistry in an ammonia (NH{sub 3}) doped flameless jet is investigated using a kinetic reactor network model. The reactor network model is used to explain the main differences in ammonia chemistry for methane (CH{sub 4})-containing fuels and methane-free fuels. The chemical pathways of nitrogen oxides (NO{sub x}) formation and destruction are identified using rate-of-production analysis. The results show that in the case of natural gas, ammonia reacts relatively late at fuel lean condition leading to high NO{sub x} emissions. In the pre-ignition zone, the ammonia chemistry is blocked due to the absence of free radicals which are consumed by methane-methyl radical (CH{sub 3}) conversion. In the case of methane-free gas, the ammonia reacted very rapidly and complete decomposition was reached in the fuel rich region of the jet. In this case the necessary radicals for the ammonia conversion are generated from hydrogen (H{sub 2}) oxidation. (author)

Zieba, Mariusz; Schuster, Anja; Scheffknecht, Guenter [Institute of Process Engineering and Power Plant Technology, University of Stuttgart, Pfaffenwaldring 23, D-70569 Stuttgart (Germany); Brink, Anders; Hupa, Mikko [Process Chemistry Centre, Aabo Akademi University, Biskopsgatan 8, 20500 Aabo (Finland)

2009-10-15

478

Corrosion inhibitor for aqueous ammonia absorption system  

DOEpatents

A method of inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425.degree. F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25.degree. C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425.degree. F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer.

Phillips, Benjamin A. (Benton Harbor, MI); Whitlow, Eugene P. (St. Joseph, MI)

1998-09-22

479

Corrosion inhibitor for aqueous ammonia absorption system  

DOEpatents

A method is described for inhibiting corrosion and the formation of hydrogen and thus improving absorption in an ammonia/water absorption refrigeration, air conditioning or heat pump system by maintaining the hydroxyl ion concentration of the aqueous ammonia working fluid within a selected range under anaerobic conditions at temperatures up to 425 F. This hydroxyl ion concentration is maintained by introducing to the aqueous ammonia working fluid an inhibitor in an amount effective to produce a hydroxyl ion concentration corresponding to a normality of the inhibitor relative to the water content ranging from about 0.015 N to about 0.2 N at 25 C. Also, working fluids for inhibiting the corrosion of carbon steel and resulting hydrogen formation and improving absorption in an ammonia/water absorption system under anaerobic conditions at up to 425 F. The working fluids may be aqueous solutions of ammonia and a strong base or aqueous solutions of ammonia, a strong base, and a specified buffer. 5 figs.

Phillips, B.A.; Whitlow, E.P.

1998-09-22

480

Plastics recycling: challenges and opportunities.  

PubMed

Plastics are inexpensive, lightweight and durable materials, which can readily be moulded into a variety of products that find use in a wide range of applications. As a consequence, the production of plastics has increased markedly over the last 60 years. However, current levels of their usage and disposal generate several environmental problems. Around 4 per cent of world oil and gas production, a non-renewable resource, is used as feedstock for plastics and a further 3-4% is expended to provide energy for their manufacture. A major portion of plastic produced each year is used to make disposable items of packaging or other short-lived products that are discarded within a year of manufacture. These two observations alone indicate that our current use of plastics is not sustainable. In addition, because of the durability of the polymers involved, substantial quantities of discarded end-of-life plastics are accumulating as debris in landfills and in natural habitats worldwide. Recycling is one of the most important actions currently available to reduce these impacts and represents one of the most dynamic areas in the plastics industry today. Recycling provides opportunities to reduce oil usage, carbon dioxide emissions and the quantities of waste requiring disposal. Here, we briefly set recycling into context against other waste-reduction strategies, namely reduction in material use through downgauging or product reuse, the use of alternative biodegradable materials and energy recovery as fuel. While plastics have been recycled since the 1970s, the quantities that are recycled vary geographically, according to plastic type and application. Recycling of packaging materials has seen rapid expansion over the last decades in a number of countries. Advances in technologies and systems for the collection, sorting and reprocessing of recyclable plastics are creating new opportunities for recycling, and with the combined actions of the public, industry and governments it may be possible to divert the majority of plastic waste from landfills to recycling over the next decades. PMID:19528059

Hopewell, Jefferson; Dvorak, Robert; Kosior, Edward

2009-07-27

481

Continuum percolation for randomly oriented soft-core prisms.  

PubMed

We study continuum percolation of three-dimensional randomly oriented soft-core polyhedra (prisms). The prisms are biaxial or triaxial and range in aspect ratio over six orders of magnitude. Results for prisms are compared with studies for ellipsoids, rods, ellipses, and polygons and differences are explained using the concept of the average excluded volume, . For large-shape anisotropies we find close agreement between prisms and most of the above-mentioned shapes for the critical total average excluded volume, n(c), where n(c) is the critical number density of objects at the percolation threshold. In the extreme oblate and prolate limits simulations yield n(c) approximately 2.3 and n(c) approximately 1.3, respectively. Cubes exhibit the lowest-shape anisotropy of prisms minimizing the importance of randomness in orientation. As a result, the maximum prism value, n(c) approximately 2.79, is reached for cubes, a value close to n(c)=2.8 for the most equant shape, a sphere. Similarly, cubes yield a maximum critical object volume fraction of phi(c)=0.22. phi(c) decreases for more prolate and oblate prisms and reaches a linear relationship with respect to aspect ratio for aspect ratios greater than about 50. Curves of phi(c) as a function of aspect ratio for prisms and ellipsoids are offset at low-shape anisotropies but converge in the extreme oblate and prolate limits. The offset appears to be a function of the ratio of the normalized average excluded volume for ellipsoids over that for prisms, R=(e)/(p). This ratio is at its minimum of R=0.758 for spheres and cubes, where phi(c(sphere))=0.2896 may be related to phi c(cube))=0.22 by phi(c(cube))=1-[1-phi(c(sphere))](R)=0.23. With respect to biaxial prisms, triaxial prisms show increased normalized average excluded volumes, , due to increased shape anisotropies, resulting in reduced values of phi(c). We confirm that B(c)=n(c)=2C(c) applies to prisms, where B(c) and C(c) are the average number of bonds per object and average number of connections per object, respectively. PMID:12059671

Saar, Martin O; Manga, Michael

2002-05-22

482

Continuum percolation for randomly oriented soft-core prisms  

NASA Astrophysics Data System (ADS)

We study continuum percolation of three-dimensional randomly oriented soft-core polyhedra (prisms). The prisms are biaxial or triaxial and range in aspect ratio over six orders of magnitude. Results for prisms are compared with studies for ellipsoids, rods, ellipses, and polygons and differences are explained using the concept of the average excluded volume, . For large-shape anisotropies we find close agreement between prisms and most of the above-mentioned shapes for the critical total average excluded volume, nc, where nc is the critical number density of objects at the percolation threshold. In the extreme oblate and prolate limits simulations yield nc~2.3 and nc~1.3, respectively. Cubes exhibit the lowest-shape anisotropy of prisms