WorldWideScience

Sample records for anion relay chemistry

  1. Interstellar Anions: The Role of Quantum Chemistry.

    Science.gov (United States)

    Fortenberry, Ryan C

    2015-10-01

    Six anions have been conclusively detected in the interstellar medium (ISM). They all arrived within a five-year window ending five years ago. Why have no new anions been detected? It is likely a lack of laboratory data for novel anions. This work reviews the role that valence and dipole-bound excited states may play in the formation, detection, and lifetime of anions that may yet be observed in the ISM and how quantum chemistry enhances this understanding. The list of interstellar anions has certainly not been exhausted by any means, but electronic, spectroscopic, and structural data must be provided to aid in any future detections. Quantum chemistry has the flexibility and completeness to provide a full picture of these systems and has shown exceptional accuracies of late. The work reviewed herein gives an overview of what quantum chemical computations have produced and will continue to provide related to anions and how this will enhance both laboratory experiment and astronomical observation.

  2. Advances in anion supramolecular chemistry: from recognition to chemical applications.

    Science.gov (United States)

    Evans, Nicholas H; Beer, Paul D

    2014-10-27

    Since the start of this millennium, remarkable progress in the binding and sensing of anions has been taking place, driven in part by discoveries in the use of hydrogen bonding, as well as the previously under-exploited anion-π interactions and halogen bonding. However, anion supramolecular chemistry has developed substantially beyond anion recognition, and now encompasses a diverse range of disciplines. Dramatic advance has been made in the anion-templated synthesis of macrocycles and interlocked molecular architectures, while the study of transmembrane anion transporters has flourished from almost nothing into a rapidly maturing field of research. The supramolecular chemistry of anions has also found real practical use in a variety of applications such as catalysis, ion extraction, and the use of anions as stimuli for responsive chemical systems. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. GAS-GRAIN MODELS FOR INTERSTELLAR ANION CHEMISTRY

    International Nuclear Information System (INIS)

    Cordiner, M. A.; Charnley, S. B.

    2012-01-01

    Long-chain hydrocarbon anions C n H – (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n H 2 ∼>10 5 cm –3 ). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C 6 H – anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C 6 O, C 7 O, HC 6 O, and HC 7 O, the abundances of which depend on the assumed branching ratios for associative electron detachment.

  4. Gas-Grain Models for Interstellar Anion Chemistry

    Science.gov (United States)

    Cordiner, M. A.; Charnely, S. B.

    2012-01-01

    Long-chain hydrocarbon anions C(sub n) H(-) (n = 4, 6, 8) have recently been found to be abundant in a variety of interstellar clouds. In order to explain their large abundances in the denser (prestellar/protostellar) environments, new chemical models are constructed that include gas-grain interactions. Models including accretion of gas-phase species onto dust grains and cosmic-ray-induced desorption of atoms are able to reproduce the observed anion-to-neutral ratios, as well as the absolute abundances of anionic and neutral carbon chains, with a reasonable degree of accuracy. Due to their destructive effects, the depletion of oxygen atoms onto dust results in substantially greater polyyne and anion abundances in high-density gas (with n(sub H2) approx > / cubic cm). The large abundances of carbon-chain-bearing species observed in the envelopes of protostars such as L1527 can thus be explained without the need for warm carbon-chain chemistry. The C6H(-) anion-to-neutral ratio is found to be most sensitive to the atomic O and H abundances and the electron density. Therefore, as a core evolves, falling atomic abundances and rising electron densities are found to result in increasing anion-to-neutral ratios. Inclusion of cosmic-ray desorption of atoms in high-density models delays freeze-out, which results in a more temporally stable anion-to-neutral ratio, in better agreement with observations. Our models include reactions between oxygen atoms and carbon-chain anions to produce carbon-chain-oxide species C6O, C7O, HC6O, and HC7O, the abundances of which depend on the assumed branching ratios for associative electron detachment

  5. Chemistry of nitrile anions in the interstellar medium

    Energy Technology Data Exchange (ETDEWEB)

    Carles, S.; Le Garrec, J.-L.; Biennier, L. [Institut de Physique de Rennes, Département de Physique Moléculaire, Astrophysique de Laboratoire, UMR CNRS 6251, Université de Rennes 1, Campus de Beaulieu, 35042 Rennes Cedex (France); Guillemin, J.-C. [Institut des Sciences Chimiques de Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 11 Allée de Beaulieu, CS 50837,35708 Rennes Cedex 7 (France)

    2015-12-31

    Despite the extreme conditions of temperature (down to 10K) and density (down to 100 molecules/cm{sup 3}), the giant molecular clouds and the circumstellar envelopes present a rich and complex chemistry. To date, more than 180 molecules have been detected in the InterStellar Medium (ISM) with a large abundance of nitriles (RC≡N). In addition, several anions have been recently observed in this medium: C{sub 4}H{sup ¯}, C{sub 6}H{sup ¯}, C{sub 8}H{sup ¯}, CN{sup ¯}, C{sub 3}N{sup ¯} and C{sub 5}N{sup ¯}. These last species should play a key role in the molecular growth towards complexity. To explore this hypothesis, their reactivity must be studied in the laboratory. The FALP-MS and the CRESU experimental apparatuses of the Rennes University are able to measure absolute rate coefficient of various chemical reactions, including the ion – molecule reactions, in gas phase at low temperature (from 300K for the FALP-MS down to 15K for the CRESU). Therefore, these experimental tools are particularly adapted to the kinetic studies of reactions potentially involved in the Interstellar Medium. One of the difficulties encountered in experiments with anions is their generation. We describe here the formation of the CN{sup ¯} and C{sub 3}N{sup ¯} anions by dissociative electron attachment on the molecular precursors BrCN and BrC{sub 3}N.

  6. Supramolecular Chemistry of Selective Anion Recognition for Anions of Environmental Relevance

    International Nuclear Information System (INIS)

    Bowman-James, K.; Wilson, G.; Moyer, B. A.

    2004-01-01

    This project involves the design and synthesis of receptors for oxoanions of environmental importance, including emphasis on high level and low activity waste. Target anions have included primarily oxoanions and a study of the basic concepts behind selective binding of target anions. A primary target has been sulfate because of its deleterious influence on the vitrification of tank wastes

  7. Expanding frontiers in materials chemistry and physics with multiple anions.

    Science.gov (United States)

    Kageyama, Hiroshi; Hayashi, Katsuro; Maeda, Kazuhiko; Attfield, J Paul; Hiroi, Zenji; Rondinelli, James M; Poeppelmeier, Kenneth R

    2018-02-22

    During the last century, inorganic oxide compounds laid foundations for materials synthesis, characterization, and technology translation by adding new functions into devices previously dominated by main-group element semiconductor compounds. Today, compounds with multiple anions beyond the single-oxide ion, such as oxyhalides and oxyhydrides, offer a new materials platform from which superior functionality may arise. Here we review the recent progress, status, and future prospects and challenges facing the development and deployment of mixed-anion compounds, focusing mainly on oxide-derived materials. We devote attention to the crucial roles that multiple anions play during synthesis, characterization, and in the physical properties of these materials. We discuss the opportunities enabled by recent advances in synthetic approaches for design of both local and overall structure, state-of-the-art characterization techniques to distinguish unique structural and chemical states, and chemical/physical properties emerging from the synergy of multiple anions for catalysis, energy conversion, and electronic materials.

  8. Monocarbaborane anion chemistry. The elusive C-arylated [PhCB11H11](-), [PhCB9H9]- and [PhCB8H8](-) anions

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Tomáš; Kilner, C. A.; Thornton-Pett, M.; Kennedy, J. D.

    č. 18 (2001), s. 1790-1791 ISSN 1359-7345 Institutional research plan: CEZ:AV0Z4032918 Keywords : weakly coordinating anions * carboranes Subject RIV: CA - Inorganic Chemistry Impact factor: 3.902, year: 2001

  9. Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules

    OpenAIRE

    El Sayed Shehata Nasr, Sameh

    2015-01-01

    [EN] Abstract The present PhD thesis entitled "Supramolecular Chemistry: New chemodosimeters and hybrid materials for the chromo-fluorogenic detection of anions and neutral molecules" is based on the application of supramolecular chemistry and material science principles for the development of optical chemosensors for anions and neutral molecules detection. The second chapter of this PhD thesis is devoted to the preparation of chemodosimeters for the chromo-fluorogenic detection of f...

  10. Supramolecular chemistry-general principles and selected examples from anion recognition and metallosupramolecular chemistry.

    Science.gov (United States)

    Albrecht, Markus

    2007-12-01

    This review gives an introduction into supramolecular chemistry describing in the first part general principles, focusing on terms like noncovalent interaction, molecular recognition, self-assembly, and supramolecular function. In the second part those will be illustrated by simple examples from our laboratories. Supramolecular chemistry is the science that bridges the gap between the world of molecules and nanotechnology. In supramolecular chemistry noncovalent interactions occur between molecular building blocks, which by molecular recognition and self-assembly form (functional) supramolecular entities. It is also termed the "chemistry of the noncovalent bond." Molecular recognition is based on geometrical complementarity based on the "key-and-lock" principle with nonshape-dependent effects, e.g., solvatization, being also highly influential. Self-assembly leads to the formation of well-defined aggregates. Hereby the overall structure of the target ensemble is controlled by the symmetry features of the certain building blocks. Finally, the aggregates can possess special properties or supramolecular functions, which are only found in the ensemble but not in the participating molecules. This review gives an introduction on supramolecular chemistry and illustrates the fundamental principles by recent examples from our group.

  11. Ubiquitous trisulfur radical anion: fundamentals and applications in materials science, electrochemistry, analytical chemistry and geochemistry.

    Science.gov (United States)

    Chivers, Tristram; Elder, Philip J W

    2013-07-21

    The trisulfur radical anion [S3]˙(-) is well-known from inorganic chemistry textbooks as the blue chromophore in ultramarine blues in which this highly reactive species is trapped in a zeolitic framework. Recent findings have revealed that [S3]˙(-) has a multi-faceted role in a variety of media, including alkali metal-sulfur batteries, aqueous solutions at high temperatures and pressures, and ionic liquids; it has also been used to detect trace amounts of water in organic solvents. This tutorial review illustrates how various physical techniques are used to identify a reactive species in solution and shows how elucidation of electronic structures can be used to explain spectroscopic and structural properties. Examples of the function of [S3]˙(-) in materials science, electrochemistry, analytical chemistry and geochemistry are used to illustrate the widespread influence of this fundamentally important triatomic sulfur species.

  12. Relay race

    CERN Document Server

    Staff Association

    2011-01-01

    The CERN relay race will take place around the Meyrin site on Thursday 19th May starting at 12:15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on the course, and how to register your team for the relay race, can be found at: https://espace.cern.ch/Running-Club/CERN-Relay Some advice for all runners from the medical service can also be found here: https://espace.cern.ch/Running-Club/CERN-Relay/RelayPagePictures/MedicalServiceAnnoncement.pdf

  13. Relay race

    CERN Document Server

    Staff Association

    2011-01-01

    The CERN relay race will take place around the Meyrin site on Thursday 19th May starting at 12·15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details on the course, and how to register your team for the relay race, can be found at: https://espace.cern.ch/Running-Club/CERN-Relay Some advice for all runners from the medical service can also be found here: https://espace.cern.ch/Running-Club/CERN-Relay/RelayPagePictures/MedicalServiceAnnoncement.pdf

  14. Recoil chemistry in inorganic solids with simultaneous activation of anion and cation: indium iodate system [ Paper No. NC-14

    International Nuclear Information System (INIS)

    Recoil chemistry of indium iodate has been worked out along with that of indium sulphate and potassium iodate with a view to find out the role of hot atoms of cation and anion being activated simultaneously. The chemical identification and separation has been presented in this paper along with some preliminary results on retention and yield of different hot species produced under (n,γ) process. (author)

  15. Reactions of Azine Anions with Nitrogen and Oxygen Atoms: Implications for Titan's Upper Atmosphere and Interstellar Chemistry.

    Science.gov (United States)

    Wang, Zhe-Chen; Cole, Callie A; Demarais, Nicholas J; Snow, Theodore P; Bierbaum, Veronica M

    2015-08-26

    Azines are important in many extraterrestrial environments, from the atmosphere of Titan to the interstellar medium. They have been implicated as possible carriers of the diffuse interstellar bands in astronomy, indicating their persistence in interstellar space. Most importantly, they constitute the basic building blocks of DNA and RNA, so their chemical reactivity in these environments has significant astrobiological implications. In addition, N and O atoms are widely observed in the ISM and in the ionospheres of planets and moons. However, the chemical reactions of molecular anions with abundant interstellar and atmospheric atomic species are largely unexplored. In this paper, gas-phase reactions of deprotonated anions of benzene, pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine with N and O atoms are studied both experimentally and computationally. In all cases, the major reaction channel is associative electron detachment; these reactions are particularly important since they control the balance between negative ions and free electron densities. The reactions of the azine anions with N atoms exhibit larger rate constants than reactions of corresponding chain anions. The reactions of azine anions with O atoms are even more rapid, with complex product patterns for different reactants. The mechanisms are studied theoretically by employing density functional theory; spin conversion is found to be important in determining some product distributions. The rich gas-phase chemistry observed in this work provides a better understanding of ion-atom reactions and their contributions to ionospheric chemistry as well as the chemical processing that occurs in the boundary layers between diffuse and dense interstellar clouds.

  16. Reactions of substituted benzene anions with N and O atoms: Chemistry in Titan's upper atmosphere and the interstellar medium.

    Science.gov (United States)

    Wang, Zhe-Chen; Bierbaum, Veronica M

    2016-06-07

    The likely existence of aromatic anions in many important extraterrestrial environments, from the atmosphere of Titan to the interstellar medium (ISM), is attracting increasing attention. Nitrogen and oxygen atoms are also widely observed in the ISM and in the ionospheres of planets and moons. In the current work, we extend previous studies to explore the reactivity of prototypical aromatic anions (deprotonated toluene, aniline, and phenol) with N and O atoms both experimentally and computationally. The benzyl and anilinide anions both exhibit slow associative electron detachment (AED) processes with N atom, and moderate reactivity with O atom in which AED dominates but ionic products are also formed. The reactivity of phenoxide is dramatically different; there is no measurable reaction with N atom, and the moderate reactivity with O atom produces almost exclusively ionic products. The reaction mechanisms are studied theoretically by employing density functional theory calculations, and spin conversion is found to be critical for understanding some product distributions. This work provides insight into the rich gas-phase chemistry of aromatic ion-atom reactions and their relevance to ionospheric and interstellar chemistry.

  17. Using Distonic Radical Ions to Probe the Chemistry of Key Combustion Intermediates: The Case of the Benzoxyl Radical Anion

    Science.gov (United States)

    Li, Cong; Lam, Adrian K. Y.; Khairallah, George N.; White, Jonathan M.; O'Hair, Richard A. J.; da Silva, Gabriel

    2013-04-01

    The benzoxyl radical is a key intermediate in the combustion of toluene and other aromatic hydrocarbons, yet relatively little experimental work has been performed on this species. Here, a combination of electrospray ionization (ESI), multistage mass spectrometry experiments, and density functional theory (DFT) calculations are used to examine the formation and fragmentation of a benzoxyl (benzyloxyl) distonic radical anion. Excited 4-carboxylatobenzoxyl radical anions were produced via two methods: (1) collision induced dissociation (CID) of the nitrate ester 4-(nitrooxymethyl)benzoate, -O2CC6H4CH2ONO2, and (2) reaction of ozone with the 4-carboxylatobenzyl radical anion, -O2CC6H4CH2 •. In neither case was the stabilized -O2CC6H4CH2O• radical anion intermediate detected. Instead, dissociation products at m/ z 121 and 149 were observed. These products are attributed to benzaldehyde (O2 -CC6H4CHO) and benzene (-O2CC6H5) products from respective loss of H and HCO radicals in the vibrationally excited benzoxyl intermediate. In no experiments was a product at m/ z 120 (i.e., -O2CC6H4 •) detected, corresponding to absence of the commonly assumed phenyl radical + CH2=O channel. The results reported suggest that distonic ions are useful surrogates for reactive intermediates formed in combustion chemistry.

  18. Fluorine-Rich Fluorides: New Insights into the Chemistry of Polyfluoride Anions.

    Science.gov (United States)

    Vent-Schmidt, Thomas; Brosi, Felix; Metzger, Jens; Schlöder, Tobias; Wang, Xuefeng; Andrews, Lester; Müller, Carsten; Beckers, Helmut; Riedel, Sebastian

    2015-07-06

    Polyfluoride anions have been investigated by matrix-isolation spectroscopy and quantum-chemical methods. For the first time the higher polyfluoride anion [F5 ](-) has been observed under cryogenic conditions in neon matrices at 850 cm(-1) . In addition, a new band for the Cs(+) [F3 ](-) complex in neon is reported. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Importance of sulfate radical anion formation and chemistry in heterogeneous OH oxidation of sodium methyl sulfate, the smallest organosulfate

    Directory of Open Access Journals (Sweden)

    K. C. Kwong

    2018-02-01

    Full Text Available Organosulfates are important organosulfur compounds present in atmospheric particles. While the abundance, composition, and formation mechanisms of organosulfates have been extensively investigated, it remains unclear how they transform and evolve throughout their atmospheric lifetime. To acquire a fundamental understanding of how organosulfates chemically transform in the atmosphere, this work investigates the heterogeneous OH radical-initiated oxidation of sodium methyl sulfate (CH3SO4Na droplets, the smallest organosulfate detected in atmospheric particles, using an aerosol flow tube reactor at a high relative humidity (RH of 85 %. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (direct analysis in real time, DART coupled with a high-resolution mass spectrometer showed that neither functionalization nor fragmentation products are detected. Instead, the ion signal intensity of the bisulfate ion (HSO4− has been found to increase significantly after OH oxidation. We postulate that sodium methyl sulfate tends to fragment into a formaldehyde (CH2O and a sulfate radical anion (SO4 ⋅ − upon OH oxidation. The formaldehyde is likely partitioned back to the gas phase due to its high volatility. The sulfate radical anion, similar to OH radical, can abstract a hydrogen atom from neighboring sodium methyl sulfate to form the bisulfate ion, contributing to the secondary chemistry. Kinetic measurements show that the heterogeneous OH reaction rate constant, k, is (3.79 ± 0.19  ×  10−13 cm3 molecule−1 s−1 with an effective OH uptake coefficient, γeff, of 0.17 ± 0.03. While about 40 % of sodium methyl sulfate is being oxidized at the maximum OH exposure (1.27  ×  1012 molecule cm−3 s, only a 3 % decrease in particle diameter is observed. This can be attributed to a small fraction of particle mass lost via the formation and volatilization of formaldehyde. Overall, we

  20. Importance of sulfate radical anion formation and chemistry in heterogeneous OH oxidation of sodium methyl sulfate, the smallest organosulfate

    Science.gov (United States)

    Chung Kwong, Kai; Chim, Man Mei; Davies, James F.; Wilson, Kevin R.; Nin Chan, Man

    2018-02-01

    Organosulfates are important organosulfur compounds present in atmospheric particles. While the abundance, composition, and formation mechanisms of organosulfates have been extensively investigated, it remains unclear how they transform and evolve throughout their atmospheric lifetime. To acquire a fundamental understanding of how organosulfates chemically transform in the atmosphere, this work investigates the heterogeneous OH radical-initiated oxidation of sodium methyl sulfate (CH3SO4Na) droplets, the smallest organosulfate detected in atmospheric particles, using an aerosol flow tube reactor at a high relative humidity (RH) of 85 %. Aerosol mass spectra measured by a soft atmospheric pressure ionization source (direct analysis in real time, DART) coupled with a high-resolution mass spectrometer showed that neither functionalization nor fragmentation products are detected. Instead, the ion signal intensity of the bisulfate ion (HSO4-) has been found to increase significantly after OH oxidation. We postulate that sodium methyl sulfate tends to fragment into a formaldehyde (CH2O) and a sulfate radical anion (SO4 ṡ -) upon OH oxidation. The formaldehyde is likely partitioned back to the gas phase due to its high volatility. The sulfate radical anion, similar to OH radical, can abstract a hydrogen atom from neighboring sodium methyl sulfate to form the bisulfate ion, contributing to the secondary chemistry. Kinetic measurements show that the heterogeneous OH reaction rate constant, k, is (3.79 ± 0.19) × 10-13 cm3 molecule-1 s-1 with an effective OH uptake coefficient, γeff, of 0.17 ± 0.03. While about 40 % of sodium methyl sulfate is being oxidized at the maximum OH exposure (1.27 × 1012 molecule cm-3 s), only a 3 % decrease in particle diameter is observed. This can be attributed to a small fraction of particle mass lost via the formation and volatilization of formaldehyde. Overall, we firstly demonstrate that the heterogeneous OH oxidation of an

  1. Combining research in physical chemistry and chemical education: Part A. The femtosecond molecular dynamics of small gas-phase anion clusters. Part B. Surveying student beliefs about chemistry and the development of physical chemistry learning tutorials

    Science.gov (United States)

    Barbera, Jack

    2007-12-01

    This dissertation combines work in the areas of experimental physical chemistry and chemical education. In the area of physical chemistry, femtosecond pump-probe spectroscopy is used to interrogate the time-dependence for energy redistribution, solvent reorientation, and dissociation dynamics in small gas-phase anion clusters. The chemical education research addressed in this manuscript include the development and validation of a survey to measure students' beliefs about chemistry and the learning of chemistry and the development and testing of learning tutorials for use in undergraduate physical chemistry courses in thermodynamics and kinetics. In the first part of this dissertation, the Cu(CD3OD) dynamics are investigated using a combination of femtosecond pump-probe experiments and ab initio calculations. Dissociation of this complex into Cu and CD3OD occurs on two distinct time scales: 3 and 30 ps, which arise, respectively, from the coupling of intermolecular solvent rotations and excited methyl rotor rotation into the Cu-O dissociation component upon electron photodetachment of the precursor anion. In the second part of this dissertation, the time-resolved recombination of photodissociated IBr-(CO2)n (n = 5 - 10) cluster anions is investigated. Upon excitation to the A' 2pi 1/2 state of the chromophore, the bare anion results in I- and Br products, upon solvation with CO2, the IBr- chromophore regains near-IR absorption after recombination and vibrational relaxation on the ground electronic state. The recombination times vary with the number of solvent molecules from 12 ps for n = 5 to 900 ps for n = 10. Extensive electronic structure and non-adiabatic molecular dynamic simulations provide a framework to understand this behavior. In the third part of this dissertation, the modification and validation of the Colorado Learning Attitudes about Science Survey (CLASS) for use in chemistry is presented in detail. The CLASS survey is designed to measure student

  2. Monocarbaborane anion chemistry. Syntheses and structures within the closo nine-vertex system

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Tomáš; Thornton-Pett, M.; Kennedy, J. D.

    2002-01-01

    Roč. 67, č. 7 (2002), s. 1035-1050 ISSN 0010-0765 R&D Projects: GA AV ČR IBS4032007 Institutional research plan: CEZ:AV0Z4032918 Keywords : boranes * monocarbaboranes * thermolyses Subject RIV: CA - Inorganic Chemistry Impact factor: 0.848, year: 2002

  3. Closo-dodecaborate (2-) anion as a potential prosthetic group for attachment of astatine to proteins. Aspects of the labelling chemistry with Chloramine-T

    Czech Academy of Sciences Publication Activity Database

    Orlova, A.; Lebeda, Ondřej; Tolmachev, V.; Sjoberg, S.; Carsllon, J.; Lundqvist, H.

    2000-01-01

    Roč. 43, č. 43 (2000), s. 251-260 ISSN 0362-4803 Institutional research plan: CEZ:AV0Z1048901 Keywords : closo-dodecaborate (2-) anion * AT-211 * astatination Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 0.756, year: 2000

  4. Telecommunications Relay Services

    Science.gov (United States)

    ... Home » Health Info » Hearing, Ear Infections, and Deafness Telecommunications Relay Services On this page: What are telecommunication ... additional information about telecommunication relay services? What are telecommunication relay services? Title IV of the Americans with ...

  5. Relay race

    CERN Document Server

    Staff Association

    2012-01-01

    The CERN Relay Race will take place around the Meyrin site on Thursday 24th May at 12:00. This annual event is for teams of six runners covering distances of 1000 m, 800 m, 800 m, 500 m, 500 m and 300 m respectively. Teams may be entered in the Seniors, Veterans, Ladies, Mixed or Open categories. There will also this year be a Nordic Walking event, as part of the Medical Service’s initiative “Move more, eat better!” The registration fee is 10 CHF per runner, and each runner will receive a souvenir prize. There will be a programme of entertainment from 12:00 on the arrival area (the lawn in front of Restaurant 1): 12:00 - 12:45  Music from the Old Bottom Street band 12:15 Start of the race 12:45 - 13h Demonstrations by the Fitness club and Dancing club 13:00 Results and prize giving (including a raffle to win an iPad2 3G offered by the Micro club) 13:20 à 14:00 Music from “What’s next” And many information st...

  6. Efficient incremental relaying

    KAUST Repository

    Fareed, Muhammad Mehboob

    2013-07-01

    We propose a novel relaying scheme which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from destination. Our scheme capitalizes on the fact that relaying is only required when direct transmission suffers deep fading. We calculate the packet error rate for the proposed efficient incremental relaying scheme with both amplify and forward and decode and forward relaying. Numerical results are also presented to verify their analytical counterparts. © 2013 IEEE.

  7. Reactions of substituted benzene anions with N and O atoms: Chemistry in Titan’s upper atmosphere and the interstellar medium

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhe-Chen; Bierbaum, Veronica M. [Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado 80309 (United States)

    2016-06-07

    The likely existence of aromatic anions in many important extraterrestrial environments, from the atmosphere of Titan to the interstellar medium (ISM), is attracting increasing attention. Nitrogen and oxygen atoms are also widely observed in the ISM and in the ionospheres of planets and moons. In the current work, we extend previous studies to explore the reactivity of prototypical aromatic anions (deprotonated toluene, aniline, and phenol) with N and O atoms both experimentally and computationally. The benzyl and anilinide anions both exhibit slow associative electron detachment (AED) processes with N atom, and moderate reactivity with O atom in which AED dominates but ionic products are also formed. The reactivity of phenoxide is dramatically different; there is no measurable reaction with N atom, and the moderate reactivity with O atom produces almost exclusively ionic products. The reaction mechanisms are studied theoretically by employing density functional theory calculations, and spin conversion is found to be critical for understanding some product distributions. This work provides insight into the rich gas-phase chemistry of aromatic ion-atom reactions and their relevance to ionospheric and interstellar chemistry.

  8. Can a pentamethylcyclopentadienyl ligand act as a proton-relay in f-element chemistry? Insights from a joint experimental/theoretical study.

    Science.gov (United States)

    Kefalidis, Christos E; Perrin, Lionel; Burns, Carol J; Berg, David J; Maron, Laurent; Andersen, Richard A

    2015-02-14

    Isomerisation of buta-1,2-diene to but-2-yne by (Me(5)C(5))(2)Yb is a thermodynamically favourable reaction, with the Δ(r)G° estimated from experimental data at 298 K to be -3.0 kcal mol(-1). It proceeds in hydrocarbon solvents with a pseudo first-order rate constant of 6.4 × 10(-6) s(-1) and 7.4 × 10(-5) s(-1) in C(6)D(12) and C(6)D(6), respectively, at 20 °C. This 1,3-hydrogen shift is formally forbidden by symmetry and has to occur by an alternative pathway. The proposed mechanism for buta-1,2-diene to but-2-yne isomerisation by (Me(5)C(5))(2)Yb involves coordination of methylallene (buta-1,2-diene) to (Me(5)C(5))(2)Yb, and deprotonation of methylallene by one of the Me(5)C(5) ligands followed by protonation of the terminal methylallenyl carbon to yield the known coordination compound (Me(5)C(5))(2)Yb(η(2)-MeC[triple bond, length as m-dash]CMe). Computationally, this mechanism is not initiated by a single electron transfer step, and the ytterbium retains its oxidation state (II) throughout the reactivity. Experimentally, the influence of the metal centre is discussed by comparison with the reaction of (Me(5)C(5))(2)Ca towards buta-1,2-diene, and (Me(5)C(5))(2)Yb with ethylene. The mechanism by which the Me(5)C(5) acts as a proton-relay within the coordination sphere of a metal also rationalises the reactivity of (i) (Me(5)C(5))(2)Eu(OEt(2)) with phenylacetylene, (ii) (Me(5)C(5))(2)Yb(OEt(2)) with phenylphosphine and (iii) (Me(5)C(5))(2)U(NPh)(2) with H(2) to yield (Me(5)C(5))(2)U(HNPh)(2). In the latter case, the computed mechanism is the heterolytic activation of H(2) by (Me(5)C(5))(2)U(NPh)(2) to yield (Me(5)C(5))(2)U(H)(HNPh)(NPh), followed by a hydrogen transfer from uranium back to the imido nitrogen atom using one Me(5)C(5) ligand as a proton-relay. The overall mechanism by which hydrogen shifts using a pentamethylcyclopentadienyl ligand as a proton-relay is named Carambole in reference to carom billiards.

  9. Anion-π Catalysis of Enolate Chemistry: Rigidified Leonard Turns as a General Motif to Run Reactions on Aromatic Surfaces.

    Science.gov (United States)

    Cotelle, Yoann; Benz, Sebastian; Avestro, Alyssa-Jennifer; Ward, Thomas R; Sakai, Naomi; Matile, Stefan

    2016-03-18

    To integrate anion-π, cation-π, and ion pair-π interactions in catalysis, the fundamental challenge is to run reactions reliably on aromatic surfaces. Addressing a specific question concerning enolate addition to nitroolefins, this study elaborates on Leonard turns to tackle this problem in a general manner. Increasingly refined turns are constructed to position malonate half thioesters as close as possible on π-acidic surfaces. The resulting preorganization of reactive intermediates is shown to support the disfavored addition to enolate acceptors to an absolutely unexpected extent. This decisive impact on anion-π catalysis increases with the rigidity of the turns. The new, rigidified Leonard turns are most effective with weak anion-π interactions, whereas stronger interactions do not require such ideal substrate positioning to operate well. The stunning simplicity of the motif and its surprisingly strong relevance for function should render the introduced approach generally useful. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Power system relaying

    CERN Document Server

    Horowitz, Stanley H; Niemira, James K

    2013-01-01

    The previous three editions of Power System Relaying offer comprehensive and accessible coverage of the theory and fundamentals of relaying and have been widely adopted on university and industry courses worldwide. With the third edition, the authors have added new and detailed descriptions of power system phenomena such as stability, system-wide protection concepts and discussion of historic outages. Power System Relaying, 4th Edition continues its role as an outstanding textbook on power system protection for senior and graduate students in the field of electric power engineering and a refer

  11. Gaseous anion chemistry. Hydrogen-deuterium exchange in mono- and dialcohol alkoxide ions: ionization reactions in dialcohols

    International Nuclear Information System (INIS)

    Lloyd, J.R.; Agosta, W.C.; Field, F.H.

    1980-01-01

    The subject of this work is H-D exchange in certain gaseous anions using D 2 as the exchanging agent. The anions involved are produced from ethylene glycol, 1,3-propanediol, 1,4-butanediol, ethanol, 1-propanol, and 1-butanol. Spectra and postulated ionization reactions for these mono- and dialcohols are given. Hydrogen-deuterium exchange occurs in the (M - 1) - and (2M - 1) - ions of ethylene glycol, 1,3-propanediol, and 1,4-butanediol. The amount of exchange occurring is 3-8 times greater in (2M - 1) - than in (M - 1) - . The amount of H-D exchange occurring in ethanol, 1-propanol, and 1-butanol is small or zero in the (2M - 1) - ions and in the (M - 1) - ion for 1-butanol [the only (M - 1) - ion which could be examined experimentally]. The amount of exchange occurring in the (2M - 1) - and (M - 1) - ions from ethylene glycol is not affected by the total pressure or composition of the reaction mixture in the ionization chamber of the mass spectrometer. A novel hydrogen-bridging mechanism is suggested to account for the observed exchange occurring in the dialcohols

  12. Macropolyhedral boron-containing cluster chemistry [S2B16H17](-). A new eighteen-vertex thiaborane anion

    Czech Academy of Sciences Publication Activity Database

    Carr, MJ.; Clegg, W.; Kennedy, J.D.; Londesborough, Michael Geoffrey Stephen; Kilner, C. A.

    2010-01-01

    Roč. 75, č. 8 (2010), s. 807-812 ISSN 0010-0765 Institutional research plan: CEZ:AV0Z40320502 Keywords : borane cluster * thiaborane * macropolyhedral Subject RIV: CA - Inorganic Chemistry Impact factor: 0.853, year: 2010

  13. Ready, steady… relay!

    CERN Multimedia

    2008-01-01

    Thursday 5 June. With another year comes another success for CERN’s Relay Race. With 76 teams taking part it was the second highest turnout in the race’s history. ‘The Shabbys’ won the relay race in 10 minutes 51 seconds.As popular as ever, this year the relay race took on the atmosphere of a mini carnival. Gathering on the lawn outside Restaurant 1, various stalls and attractions added to the party feeling of the event, with beer courtesy of ‘AGLUP’, the Belgian beer club, and a wandering jazz group entertaining spectators and competitors alike. Reflecting the greater involvement of other associations in the relay race, the president of the Staff Association Clubs Committee, James Purvis, was the guest of honour, launching the start of the race and presenting the prizes. As regular followers of the race could have probably predicted, The Shabbys were once again victorious and claimed first place. The team members th...

  14. Asymmetric Carbamoyl Anion Additions to Chiral N-Phosphonyl Imines via the GAP Chemistry Process and Stereoselectivity Enrichments.

    Science.gov (United States)

    Seifert, Cole W; Pindi, Suresh; Li, Guigen

    2015-01-02

    Carbamoyl anions were found to smoothly react with chiral N-phosphonyl imines in toluene at -78 °C to r.t. using LiHMDS as the base. Group-assisted purification (GAP) has been utilized to give the pure amides without using column chromatography or recrystallization. The asymmetric reaction resulted in chiral N-phosphonyl amino amides with good to excellent yields (71-99%) and good crude diastereoselectivities (dr 84:16-95:5). In this GAP procedure, the crude solids are washed with diethyl ether to afford the pure products, as revealed by (1)H NMR analysis; GAP washing consistently increases the diastereopurity of the products, resulting in excellent diastereoselectivities, often with final dr > 99:1. Interestingly, the diastereoenriched products can be obtained either in the ether solution or as the suspended solid, depending on the substrate.

  15. Monocarbaborane chemistry. Preparation and characterisation of [4-CB8H9](-), the 'missing' closo-carbaborane anion

    Czech Academy of Sciences Publication Activity Database

    Jelínek, Tomáš; Štíbr, Bohumil; Holub, Josef; Bakardjiev, Mario; Hnyk, Drahomír; Ormsby, D. L.; Kilner, C. A.; Thornton-Pett, M.; Schanz, H. J.; Wrackmeyer, B.; Kennedy, J. D.

    č. 18 (2001), s. 1756-1757 ISSN 1359-7345 R&D Projects: GA ČR GA203/99/M037; GA MŠk LN00A028; GA MŠk LB98233 Institutional research plan: CEZ:AV0Z4032918 Keywords : carboranes * C2B10H12 Subject RIV: CA - Inorganic Chemistry Impact factor: 3.902, year: 2001

  16. Preparation, surface chemistry, and electrical conductivity of novel silicon carbide/polypyrrole composites containing an anionic surfactant

    Czech Academy of Sciences Publication Activity Database

    Mičušík, M.; Omastová, M.; Boukerma, K.; Albouy, A.; Chehimi, M. M.; Trchová, Miroslava; Fedorko, P.

    2007-01-01

    Roč. 47, č. 8 (2007), s. 1198-1206 ISSN 0032-3888. [Bratislava International Conference on Macromolecules: Advanced Polymeric Materials /20./. Bratislava, 11.06.2006-15.06.2006] R&D Projects: GA AV ČR IAA400500504 Institutional research plan: CEZ:AV0Z40500505 Keywords : composites Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.272, year: 2007

  17. Opportunistic relaying in multipath and slow fading channel: Relay selection and optimal relay selection period

    KAUST Repository

    Sungjoon Park,

    2011-11-01

    In this paper we present opportunistic relay communication strategies of decode and forward relaying. The channel that we are considering includes pathloss, shadowing, and fast fading effects. We find a simple outage probability formula for opportunistic relaying in the channel, and validate the results by comparing it with the exact outage probability. Also, we suggest a new relay selection algorithm that incorporates shadowing. We consider a protocol of broadcasting the channel gain of the previously selected relay. This saves resources in slow fading channel by reducing collisions in relay selection. We further investigate the optimal relay selection period to maximize the throughput while avoiding selection overhead. © 2011 IEEE.

  18. Alternate MIMO relaying with three AF relays using interference alignment

    KAUST Repository

    Park, Kihong

    2012-06-01

    In this paper, we study a two-hop half-duplex relaying network with one source, one destination, and three amplify-and-forward (AF) relays equipped with M antennas each. We consider alternate transmission to compensate for the inherent loss of capacity pre-log factor 1/2 in half duplex mode, where source transmit message to two relays and the other relay alternately. The inter-relay interference caused by alternate transmission is aligned to make additional degrees of freedom (DOFs). It is shown that the proposed scheme enables us to exploit 3M/4 DOFs compared with the M/2 DOFs of conventional AF relaying. More specifically, suboptimal linear filter designs for a source and three relays are proposed to maximize the achievable sum-rate. We verify using some selected numerical results that the proposed filter designs give significant improvement of the sum-rate over a naive filter and conventional relaying schemes. © 2012 IEEE.

  19. CERN Relay Race

    CERN Document Server

    2011-01-01

    The CERN relay race will take place around the Meyrin site on Thursday 19 May starting at 12-15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. Thank you for your cooperation. Details of the course and of how to register your team for the relay race can be found here. Some advice for all runners from the Medical Service can also be found here.   

  20. Surface chemistry on bimetallic alloy surfaces: adsorption of anions and oxidation of CO on Pt3Sn(111).

    Science.gov (United States)

    Stamenković, Vojislav R; Arenz, Matthias; Lucas, Christopher A; Gallagher, Mark E; Ross, Philip N; Marković, Nenad M

    2003-03-05

    The microscopic structure of the Pt(3)Sn(111) surface in an electrochemical environment has been studied by a combination of ex situ low-energy electron diffraction (LEED), Auger electron spectroscopy (AES), and low-energy ion scattering (LEIS) and in situ surface X-ray scattering (SXS) and Fourier transform infrared (FTIR) spectroscopy. In ultrahigh vacuum (UHV) the clean-annealed surface produces a p(2 x 2) LEED pattern consistent with the surface composition, determined by LEIS, of 25 at. % Sn. SXS results show that the p(2 x 2) structure can be "transferred" from UHV into 0.5 M H(2)SO(4) and that the surface structure remains stable from 0.05 to 0.8 V. At 0.05 V the expansion of Pt surface atoms, ca. +2% from the bulk lattice spacing, is induced by adsorption of underpotential-deposited (UPD) hydrogen. At 0.5 V, where Pt atoms are covered by (bi)sulfate anions, the topmost layer is contracted relative to 0.05 V, although Sn atoms expand significantly, ca. 8.5%. The p(2 x 2) structure is stable even in solutions containing CO. In contrast to the Pt(111)-CO system, no ordered structures of CO are formed on the Pt(3)Sn(111) surface and the topmost layer expands relatively little (ca. 1.5%) from the bulk lattice spacing upon the adsorption of CO. The binding site geometry of CO on Pt(3)Sn(111) is determined by FTIR. In contrast to the near invariant band shape of a-top CO on Pt(111), changes in band morphology (splitting of the band) and vibrational properties (increase in the frequency mode) are clearly visible on the Pt(3)Sn(111) surface. To explain the line shape of the CO bands, we suggest that in addition to alloying effects other factors, such as intermolecular repulsion between coadsorbed CO and OH species, are controlling segregation of CO into cluster domains where the local CO coverage is different from the coverage expected for the CO-CO interaction on an unmodified Pt(111) surface.

  1. CERN Relay Race

    CERN Multimedia

    2009-01-01

    The CERN relay race, now in its 39th year, is already a well-known tradition, but this year the organizers say the event will have even more of a festival feeling. Just off the starting line of the CERN relay race.For the past few years, spectators and runners at the CERN relay race have been able to enjoy a beer while listening to music from the CERN music and jazz clubs. But this year the organizers are aiming for "even more of a festival atmosphere". As David Nisbet, President of the CERN running club and organizer of the relay race, says: "Work is not just about getting your head down and doing the theory, it’s also about enjoying the company of your colleagues." This year, on top of music from the Santa Luis Band and the Canettes Blues Band, there will be demonstrations from the Aikido and softball clubs, a stretching session by the Fitness club, as well as various stalls and of course, the well-earned beer from AGLUP, the B...

  2. 2005 CERN Relay Race

    CERN Document Server

    Patrice Loiez

    2005-01-01

    The CERN Relay Race takes place each year in May and sees participants from all areas of the CERN staff. The winners in 2005 were The Shabbys with Los Latinos Volantes in second and Charmilles Technologies a close third. To add a touch of colour and levity, the CERN Jazz Club provided music at the finishing line.

  3. The crystal chemistry of novel thorium and uranium compounds with oxo-anions from group VI of periodic table (S, Se, Te, Cr, Mo and W)

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Bin

    2016-01-26

    used as the flux for the high-temperature synthesis method to decrease the crystal growth temperature. This also gives an opportunity to allow Te{sup 4+} anion to interact with anion of Mo{sup 6+} or W{sup 6+}, leading to a more complex mixed oxo-anion system, which is reported in Chapter 7 from page 122. Last, some attractive features of structural chemistry of actinides, such as cation-cation interaction of uranyl groups(Chapter 8.1 from page 136), and the first thorium compounds containing alkaline-earth or rare earth metals (Chapter 8.2 from page 145) are discussed in Chapter 8.

  4. Chemistry

    International Nuclear Information System (INIS)

    Gomez G, H.

    1989-01-01

    A brief description about the development and activities executed in chemistry, in the Instituto de Asuntos Nucleares, during the last years is presented. The plans and feasibility of nuclear techniques in Colombia are also described

  5. Unprecedented conformational variability in main group inorganic chemistry: the tetraazidoarsenite and -antimonite salts A+ [M(N3)4]- (A = NMe4, PPh4, (Ph3P)2N; M = As, Sb), five similar salts, five different anion structures.

    Science.gov (United States)

    Haiges, Ralf; Rahm, Martin; Christe, Karl O

    2013-01-07

    A unique example for conformational variability in inorganic main group chemistry has been discovered. The arrangement of the azido ligands in the pseudotrigonal bipyramidal [As(N(3))(4)](-) and [Sb(N(3))(4)](-) anions theoretically can give rise to seven different conformers which have identical MN(4) skeletons but different azido ligand arrangements and very similar energies. We have now synthesized and structurally characterized five of these conformers by subtle variations in the nature of the counterion. Whereas conformational variability is common in organic chemistry, it is rare in inorganic main group chemistry and is usually limited to two. To our best knowledge, the experimental observation of five distinct single conformers for the same type of anion is unprecedented. Theoretical calculations at the M06-2X/cc-pwCVTZ-PP level for all seven possible basic conformers show that (1) the energy differences between the five experimentally observed conformers are about 1 kcal/mol or less, and (2) the free monomeric anions are the energetically favored species in the gas phase and also for [As(N(3))(4)](-) in the solid state, whereas for [Sb(N(3))(4)](-) associated anions are energetically favored in the solid state and possibly in solutions. Raman spectroscopy shows that in the azide antisymmetric stretching region, the solid-state spectra are distinct for the different conformers, and permits their identification. The spectra of solutions are solvent dependent and differ from those of the solids indicating the presence of rapidly exchanging equilibria of different conformers. The only compound for which a solid with a single well-ordered conformer could not be isolated was [N(CH(3))(4)][As(N(3))(4)] which formed a viscous, room-temperature ionic liquid. Its Raman spectrum was identical to that of its CH(3)CN solution indicating the presence of an equilibrium of multiple conformers.

  6. Mechanistic investigation on N → Cα → O relay via non-Brook rearrangement: reaction conditions promote synthesis of furo[3,2-c]pyridinones.

    Science.gov (United States)

    Zhu, Lihan; Yuan, Haiyan; Zhang, Jingping

    2017-11-07

    A comprehensive density functional theory investigation was employed to disclose the effect of reaction conditions on the mechanism and effective anion relay sequence of a NaH promoted non-Brook rearrangement of benzaldehyde and 1-cinnamoylcyclopropanecarboxamides. Two main mechanisms were explored under four different reaction conditions: Na + -assisted and nH 2 O-Na + , 2H 2 O-DMSO-Na + , and Na + -DMSO co-assisted, and the difference relies on the reaction sequence between the concerted ring-opening and recyclization and electrophilic addition. Being different from previous reports, a cooperative participation of water, solvent DMSO and counterion Na + is revealed in the preferential mechanism. The preferred scenario undergoes five major steps: deprotonation, aza-Michael addition, electrophilic addition, NaOH elimination and a concerted ring-opening and recyclization step. The rate-determining step is the concerted ring-opening and recyclization process with an energy barrier of 30.2 kcal mol -1 . We found that the effective anion relay of a non-Brook rearrangement order is N → C α → O rather than the previously proposed aza-oxy-carbanion. Meanwhile, a mixed type of ARC chemistry through a novel non-Brook rearrangement was disclosed. Moreover, the non-covalent interactions between substrate and reactant extensively affect the anion relay process by hydrogen-bonding (O-HO and C-HO) and electrostatic (Na + O) interactions. Thus, our results provide insightful clues to the mechanism of the reaction condition catalyzed non-Brook rearrangement reaction.

  7. Opportunistic Relay Selection in Multicast Relay Networks using Compressive Sensing

    KAUST Repository

    Elkhalil, Khalil

    2014-12-01

    Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. However, for relay selection algorithms to make a selection decision, channel state information (CSI) from all cooperating relays is usually required at a central node. This requirement poses two important challenges. Firstly, CSI acquisition generates a great deal of feedback overhead (air-time) that could result in significant transmission delays. Secondly, the fed back channel information is usually corrupted by additive noise. This could lead to transmission outages if the central node selects the set of cooperating relays based on inaccurate feedback information. In this paper, we introduce a limited feedback relay selection algorithm for a multicast relay network. The proposed algorithm exploits the theory of compressive sensing to first obtain the identity of the “strong” relays with limited feedback. Following that, the CSI of the selected relays is estimated using linear minimum mean square error estimation. To minimize the effect of noise on the fed back CSI, we introduce a back-off strategy that optimally backs-off on the noisy estimated CSI. For a fixed group size, we provide closed form expressions for the scaling law of the maximum equivalent SNR for both Decode and Forward (DF) and Amplify and Forward (AF) cases. Numerical results show that the proposed algorithm drastically reduces the feedback air-time and achieves a rate close to that obtained by selection algorithms with dedicated error-free feedback channels.

  8. Relay Selection for Cooperative Relaying in Wireless Energy Harvesting Networks

    Science.gov (United States)

    Zhu, Kaiyan; Wang, Fei; Li, Songsong; Jiang, Fengjiao; Cao, Lijie

    2018-01-01

    Energy harvesting from the surroundings is a promising solution to provide energy supply and extend the life of wireless sensor networks. Recently, energy harvesting has been shown as an attractive solution to prolong the operation of cooperative networks. In this paper, we propose a relay selection scheme to optimize the amplify-and-forward (AF) cooperative transmission in wireless energy harvesting cooperative networks. The harvesting energy and channel conditions are considered to select the optimal relay as cooperative relay to minimize the outage probability of the system. Simulation results show that our proposed relay selection scheme achieves better outage performance than other strategies.

  9. Chemistry

    International Nuclear Information System (INIS)

    Ferris, L.M.

    1975-01-01

    The chemical research and development efforts related to the design and ultimate operation of molten-salt breeder reactor systems are concentrated on fuel- and coolant-salt chemistry, including the development of analytical methods for use in these systems. The chemistry of tellurium in fuel salt is being studied to help elucidate the role of this element in the intergranular cracking of Hastelloy N. Studies were continued of the effect of oxygen-containing species on the equilibrium between dissolved UF 3 and dissolved UF 4 , and, in some cases, between the dissolved uranium fluorides and graphite, and the UC 2 . Several aspects of coolant-salt chemistry are under investigation. Hydroxy and oxy compounds that could be formed in molten NaBF 4 are being synthesized and characterized. Studies of the chemistry of chromium (III) compounds in fluoroborate melts were continued as part of a systematic investigation of the corrosion of structural alloys by coolant salt. An in-line voltammetric method for determining U 4+ /U 3+ ratios in fuel salt was tested in a forced-convection loop over a six-month period. (LK)

  10. Joint source and relay optimization for interference MIMO relay networks

    Science.gov (United States)

    Khandaker, Muhammad R. A.; Wong, Kai-Kit

    2017-12-01

    This paper considers multiple-input multiple-output (MIMO) relay communication in multi-cellular (interference) systems in which MIMO source-destination pairs communicate simultaneously. It is assumed that due to severe attenuation and/or shadowing effects, communication links can be established only with the aid of a relay node. The aim is to minimize the maximal mean-square-error (MSE) among all the receiving nodes under constrained source and relay transmit powers. Both one- and two-way amplify-and-forward (AF) relaying mechanisms are considered. Since the exactly optimal solution for this practically appealing problem is intractable, we first propose optimizing the source, relay, and receiver matrices in an alternating fashion. Then we contrive a simplified semidefinite programming (SDP) solution based on the error covariance matrix decomposition technique, avoiding the high complexity of the iterative process. Numerical results reveal the effectiveness of the proposed schemes.

  11. Relay mirror experiment

    Science.gov (United States)

    Begley, David L.

    1996-04-01

    Originating out of a SDIO-funded, Phase 1 study effort, two ground systems and an orbiting EO payload/spacecraft were the primary equipment for the RME. The RME was originally conceived to be a shuttle deployed experiment. Shortly after program start, the Challenger disaster occurred, with the promise of extensive delays. A completely new space segment was to be designed incorporating a free-flying spacecraft. During the midphase of the program, a variety of launch vehicles were envisioned to replace the shuttle, requiring the BASD team to design accommodations for Delta, Atlas, and Titan, with a Delta launch being the final solution. The ground systems tracked the spacecraft and illuminated it with green and blue beacon lasers. The Payload Experiment Package (PEP) housed the bisection tracker, a key innovation central to the experiment. The bisection tracker acquired both beacons and controlled steerable mirrors to accomplish fine tracking of the two cooperative beacons. In the process, the relay mirror was precisely positioned to enable a successful relay of a third infrared laser between the two ground sites via the orbiting spacecraft. Many of the key technologies employed in the PEP were originally developed for Ball laser communications research and development programs and other laser pointing efforts. The WAVE sensor package, built by ATA and integrated by Ball, measured the vibrations of the optical base structure on which it was mounted. These spacecraft vibration data are critical to the accurate pointing of space laser communication terminals.

  12. CERN Relay Race

    CERN Multimedia

    Running Club

    2010-01-01

    This year’s CERN Relay Race will take place around the Meyrin site on Thursday 20th May at 12h00. This annual event is for teams of 6 runners covering distances of 1000m, 800m, 800m, 500m, 500m and 300m respectively. Teams may be entered in the Seniors, Veterans, Ladies, Mixed or Open categories. The registration fee is 10 CHF per runner, and each runner receives a souvenir prize. As usual, there will be a programme of entertainments from 12h in the arrival area, in front of the Restaurant no. 1. Drinks, food, CERN club information and music will be available for the pleasure of both runners and spectators. The race starts at 12h15, with results and prize giving at 13:15.   For details of the race, and of how to sign up a team, please visit: https://espace.cern.ch/Running-Club/CERN-Relay The event is organised by the CERN Running Club with the support of the CERN Staff Association.  

  13. CERN Relay Race 2018

    CERN Multimedia

    CERN Running club

    2018-01-01

    The CERN running club, in collaboration with the Staff Association, is happy to announce the 2018 relay race edition. It will take place on Thursday, May 24th and will consist as every year in a round trip of the CERN Meyrin site in teams of 6 members. It is a fun event, and you do not have to run fast to enjoy it. Registrations will be open from May 1st to May 22nd on the running club web site. All information concerning the race and the registration are available there too: http://runningclub.web.cern.ch/content/cern-relay-race. A video of the previous edition is also available here : http://cern.ch/go/Nk7C. As every year, there will be animations starting at noon on the lawn in front of restaurant 1, and information stands for many CERN associations and clubs will be available. The running club partners will also be participate in the event, namely Berthie Sport, Interfon and Uniqa.

  14. 47th Relay Race!

    CERN Multimedia

    Staff Association

    2017-01-01

    On Thursday June 1st at 12.15, Fabiola Gianotti, our Director-General, will fire the starting shot for the 47th Relay Race. This Race is above all a festive CERN event, open for runners and walkers, as well as the people cheering them on throughout the race, and those who wish to participate in the various activities organised between 11.30 and 14.30 out on the lawn in front of Restaurant 1. In order to make this sports event accessible for everyone, our Director-General will allow for flexible lunch hours on the day, applicable for all the members of personnel. An alert for the closure of roads will be send out on the day of the event. The Staff Association and the CERN Running Club thank you in advance for your participation and your continued support throughout the years. This year the CERN Running Club has announced the participation of locally and internationally renowned runners, no less! A bit over a week from the Relay Race of 1st June, the number of teams is going up nicely (already almost 40). Am...

  15. 49 CFR 234.263 - Relays.

    Science.gov (United States)

    2010-10-01

    .... (b)(1) Alternating current vane type relays, direct current polar type relays, and relays with soft iron magnetic structure shall be tested at least once every two years. (2) Alternating current...

  16. MIMO Four-Way Relaying

    DEFF Research Database (Denmark)

    Liu, Huaping; Sun, Fan; De Carvalho, Elisabeth

    2013-01-01

    the sum-rate of the new scheme for Decode-and-Forward (DF) operational model for the RS. We compare the performance with state-of-the-art reference schemes, based on two-way relaying with DF. The results indicate that the sum-rate of the two-phase four-way relaying scheme largely outperforms the four...

  17. Autonomous Adaptive Acoustic Relay Positioning

    Science.gov (United States)

    2013-09-01

    dataset contained 835 detected transmis- sions from source to relay and 636 detected transmissions from relay to destination, with 493 of these being...Krishnamachari, and R. Jain. Learning Multiuser Channel Allocations in Cognitive Radio Networks: A Combinatorial Multi-Armed Bandit Formula- tion. In Proc

  18. CERN Relay Race

    CERN Document Server

    2005-01-01

    The CERN Relay Race will take place around the Meyrin site on Wednesday 18 May between 12.15 and 12.35. This year, weather permitting, there will be some new attractions in the start/finish area on the field behind the Main Building. You will be able to: listen to music played by the CERN Jazz Club; buy drinks at the bar organised by the CERN Running Club; buy lunch served directly on the terrace by the restaurant Novae. ATTENTION: concerning traffic, the recommendations are the same as always: If possible, please avoid driving on the site during this 20 minute period. If you do meet runners in your car, please STOP until they all have passed. Thank you for your understanding.

  19. Radio Relays Improve Wireless Products

    Science.gov (United States)

    2009-01-01

    Signal Hill, California-based XCOM Wireless Inc. developed radio frequency micromachine (RF MEMS) relays with a Phase II Small Business Innovation Research (SBIR) contract through NASA?s Jet Propulsion Laboratory. In order to improve satellite communication systems, XCOM produced wireless RF MEMS relays and tunable capacitors that use metal-to-metal contact and have the potential to outperform most semiconductor technologies while using less power. These relays are used in high-frequency test equipment and instrumentation, where increased speed can mean significant cost savings. Applications now also include mainstream wireless applications and greatly improved tactical radios.

  20. PHOTOSENSITIVE RELAY CONTROL CIRCUIT

    Science.gov (United States)

    Martin, C.F.

    1958-01-14

    adapted for the measurement of the time required for an oscillating member to pass through a preselected number of oscillations, after being damped to a certain maximum amplitude of oscillation. A mirror is attached to the moving member and directs light successively to a photocell which is part of a trigger unit and to first and second photocells which are part of a starter unit, as the member swings to its maximum amplitude. The starter and trigger units comprise thyratrons and relays so interconnected that the trigger circuit, although generating a counter pulse, does not register a count in the counter when the light traverses both photocells of the starter unit. When the amplitude of oscillation of the member decreases to where the second photocell is not transversed, the triggei pulse is received by the counter. The counter taen operates to register the desired number of oscillations and initiates and terminates a timer for measuring the time irterval for the preselected number of oscillations.

  1. The 2009 Relay Race

    CERN Multimedia

    2009-01-01

    The 2009 CERN Relay Race was as popular as ever, with a record number of 88 teams competing. var flash_video_player=get_video_player_path(); insert_player_for_external('Video/Public/Movies/2009/CERN-MOVIE-2009-048/CERN-MOVIE-2009-048-0753-kbps-480x360-25-fps-audio-64-kbps-44-kHz-stereo', 'mms://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2009/CERN-MOVIE-2009-048/CERN-MOVIE-2009-048-Multirate-200-to-753-kbps-480x360.wmv', 'false', 288, 216, 'https://mediastream.cern.ch/MediaArchive/Video/Public/Movies/2009/CERN-MOVIE-2009-048/CERN-MOVIE-2009-048-posterframe-480x360-at-10-percent.jpg', '1178303', true, 'Video/Public/Movies/2009/CERN-MOVIE-2009-048/CERN-MOVIE-2009-048-0600-kbps-maxH-360-25-fps-audio-128-kbps-48-kHz-stereo.mp4'); Even the rain didn’t dampen the spirits, and it still managed to capture the ‘festival feeling’ with live music, beer and stalls from various CERN clubs set up outside Restaurant 1. The Powercuts on the podium after win...

  2. EAGLE: relay mirror technology development

    Science.gov (United States)

    Hartman, Mary; Restaino, Sergio R.; Baker, Jeffrey T.; Payne, Don M.; Bukley, Jerry W.

    2002-06-01

    EAGLE (Evolutionary Air & Space Global Laser Engagement) is the proposed high power weapon system with a high power laser source, a relay mirror constellation, and the necessary ground and communications links. The relay mirror itself will be a satellite composed of two optically-coupled telescopes/mirrors used to redirect laser energy from ground, air, or space based laser sources to distant points on the earth or space. The receiver telescope captures the incoming energy, relays it through an optical system that cleans up the beam, then a separate transmitter telescope/mirror redirects the laser energy at the desired target. Not only is it a key component in extending the range of DoD's current laser weapon systems, it also enables ancillary missions. Furthermore, if the vacuum of space is utilized, then the atmospheric effects on the laser beam propagation will be greatly attenuated. Finally, several critical technologies are being developed to make the EAGLE/Relay Mirror concept a reality, and the Relay Mirror Technology Development Program was set up to address them. This paper will discuss each critical technology, the current state of the work, and the future implications of this program.

  3. Performance limitations of relay neurons.

    Directory of Open Access Journals (Sweden)

    Rahul Agarwal

    Full Text Available Relay cells are prevalent throughout sensory systems and receive two types of inputs: driving and modulating. The driving input contains receptive field properties that must be transmitted while the modulating input alters the specifics of transmission. For example, the visual thalamus contains relay neurons that receive driving inputs from the retina that encode a visual image, and modulating inputs from reticular activating system and layer 6 of visual cortex that control what aspects of the image will be relayed back to visual cortex for perception. What gets relayed depends on several factors such as attentional demands and a subject's goals. In this paper, we analyze a biophysical based model of a relay cell and use systems theoretic tools to construct analytic bounds on how well the cell transmits a driving input as a function of the neuron's electrophysiological properties, the modulating input, and the driving signal parameters. We assume that the modulating input belongs to a class of sinusoidal signals and that the driving input is an irregular train of pulses with inter-pulse intervals obeying an exponential distribution. Our analysis applies to any [Formula: see text] order model as long as the neuron does not spike without a driving input pulse and exhibits a refractory period. Our bounds on relay reliability contain performance obtained through simulation of a second and third order model, and suggest, for instance, that if the frequency of the modulating input increases or the DC offset decreases, then relay increases. Our analysis also shows, for the first time, how the biophysical properties of the neuron (e.g. ion channel dynamics define the oscillatory patterns needed in the modulating input for appropriately timed relay of sensory information. In our discussion, we describe how our bounds predict experimentally observed neural activity in the basal ganglia in (i health, (ii in Parkinson's disease (PD, and (iii in PD during

  4. Metallacarborane chemistry of the hypho-[6,7-C2B6H13](-) anion: Reaction with nickelocene and the formation of three multimetallic nickel-boron clusters

    Czech Academy of Sciences Publication Activity Database

    Londesborough, Michael Geoffrey Stephen; Jelínek, Tomáš; Grüner, Bohumír; Štíbr, Bohumil; Císařová, I.; Carr, MJ.

    2005-01-01

    Roč. 690, č. 11 (2005), s. 2835-2839 ISSN 0022-328X R&D Projects: GA ČR(CZ) GA203/05/2646 Institutional research plan: CEZ:AV0Z40320502 Keywords : boranes * carboranes * metallacarboranes Subject RIV: CA - Inorganic Chemistry Impact factor: 2.025, year: 2005

  5. Paper-Based Heavy Metal Sensors from the Concise Synthesis of an Anionic Porphyrin: A Practical Application of Organic Synthesis to Environmental Chemistry

    Science.gov (United States)

    Prabpal, Jutamat; Vilaivan, Tirayut; Praneenararat, Thanit

    2017-01-01

    Tetrakis(4-sulfonatophenyl)porphyrin (TSPP) was immobilized on patterned paper and used as a sensor for heavy metal ions in an advanced organic chemistry course. The resulting sensor could detect Hg[superscript 2+] and Cd[superscript 2+] ions colorimetrically, while Cu[superscript 2+] ion resulted in fluorescence quenching, thus demonstrating a…

  6. Handover Framework for Relay Enhanced LTE Networks

    DEFF Research Database (Denmark)

    Teyeb, Oumer Mohammed; Van Phan, Vinh; Raaf, Bernhard

    2009-01-01

    Relaying is one of the proposed technologies for future releases of UTRAN Long Term Evolution (LTE) networks. Introducing relaying is expected to increase the coverage and capacity of LTE networks. In order to enable relaying, the architecture, protocol and radio resource management procedures...... of LTE, such as handover, have to be modified. A user can be handed over not only between two base stations, but also between relays and base stations, and between two relays. With the introduction of relaying, there is a need for a new procedure to hand over a relay and all its associated users...... to another base station, allowing a flexible and dynamic relay deployment. In this paper, we extend the LTE release 8 handover mechanisms so that it can accommodate these new handover functionalities in a flexible manner....

  7. Speech-to-Speech Relay Service

    Science.gov (United States)

    Consumer Guide Speech to Speech Relay Service Speech-to-Speech (STS) is one form of Telecommunications Relay Service (TRS). TRS is a service that allows persons with hearing and speech disabilities ...

  8. Robust distributed cognitive relay beamforming

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2012-05-01

    In this paper, we present a distributed relay beamformer design for a cognitive radio network in which a cognitive (or secondary) transmit node communicates with a secondary receive node assisted by a set of cognitive non-regenerative relays. The secondary nodes share the spectrum with a licensed primary user (PU) node, and each node is assumed to be equipped with a single transmit/receive antenna. The interference to the PU resulting from the transmission from the cognitive nodes is kept below a specified limit. The proposed robust cognitive relay beamformer design seeks to minimize the total relay transmit power while ensuring that the transceiver signal-to-interference- plus-noise ratio and PU interference constraints are satisfied. The proposed design takes into account a parameter of the error in the channel state information (CSI) to render the performance of the beamformer robust in the presence of imperfect CSI. Though the original problem is non-convex, we show that the proposed design can be reformulated as a tractable convex optimization problem that can be solved efficiently. Numerical results are provided and illustrate the performance of the proposed designs for different network operating conditions and parameters. © 2012 IEEE.

  9. Quantum cryptography with an ideal local relay

    DEFF Research Database (Denmark)

    Spedalieri, Gaetana; Ottaviani, Carlo; Braunstein, Samuel L.

    2015-01-01

    We consider two remote parties connected to a relay by two quantum channels. To generate a secret key, they transmit coherent states to the relay, where the states are subject to a continuous-variable (CV) Bell detection. We study the ideal case where Alice's channel is lossless, i.e., the relay ...

  10. Relay Selection with Limited and Noisy Feedback

    KAUST Repository

    Eltayeb, Mohammed E.

    2016-01-28

    Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. Nonetheless, relay selection algorithms generally require error-free channel state information (CSI) from all cooperating relays. Practically, CSI acquisition generates a great deal of feedback overhead that could result in significant transmission delays. In addition to this, the fed back channel information is usually corrupted by additive noise. This could lead to transmission outages if the central node selects the set of cooperating relays based on inaccurate feedback information. In this paper, we propose a relay selection algorithm that tackles the above challenges. Instead of allocating each relay a dedicated channel for feedback, all relays share a pool of feedback channels. Following that, each relay feeds back its identity only if its effective channel (source-relay-destination) exceeds a threshold. After deriving closed-form expressions for the feedback load and the achievable rate, we show that the proposed algorithm drastically reduces the feedback overhead and achieves a rate close to that obtained by selection algorithms with dedicated error-free feedback from all relays. © 2015 IEEE.

  11. Alternate transmission with half-duplex relaying in MIMO interference relay networks

    KAUST Repository

    Park, Seongho

    2013-12-01

    In this paper, we consider an alternate transmission scheme for a multiple-input multiple-output interference relay channel where multiple sources transmit their own signals to their corresponding destinations via one of two relaying groups alternately every time phase. Each of the relaying groups has arbitrary number of relays, and each relay operates in half-duplex amplify-and-forward mode. In our scheme, the received signals at the relay nodes consist of desired signals and two different interference signals such as the inter-source interferences and the inter-group interferences which are caused by the phase incoherence of relaying. As such, we propose an iterative interference alignment algorithm to mitigate the interferences. We show that our proposed scheme achieves additional degrees of freedom compared to the conventional half-duplex relaying system in the interference relay channels. © 2013 IEEE.

  12. The magic of relay mirrors

    Science.gov (United States)

    Duff, Edward A.; Washburn, Donald C.

    2004-09-01

    Laser weapon systems would be significantly enhanced with the addition of high altitude or space-borne relay mirrors. Such mirrors, operating alone with a directed energy source, or many in a series fashion, can be shown to effectively move the laser source to the last, so-called fighting mirror. This "magically" reduces the range to target and offers to enhance the performance of directed energy systems like the Airborne Laser and even ground-based or ship-based lasers. Recent development of high altitude airships will be shown to provide stationary positions for such relay mirrors thereby enabling many new and important applications for laser weapons. The technical challenges to achieve this capability are discussed.

  13. Beam shaping for relay mirrors

    Science.gov (United States)

    Mansell, Justin D.

    2006-08-01

    Relay mirrors offer a method of extending the range and efficacy of laser weapons systems by providing a platform that can relay the high power beam from the source to a target at a lower cost than building more laser weapons. Most laser weapons' platforms use a Cassegrain aperture telescope to project the high-power beam to a target. Diffraction causes power in the projected beam to move out beyond the edge of the receiving aperture and into the central obscuration of the receiving Cassegrain telescope. This paper presents a method of increasing the power coupling between a projected beam and a receiving telescope by warping the phase of the projected beam and shows that the spatial frequency and amplitude of the phase aberration is consistent with being integrated with the adaptive optics control loop on the source beam projector.

  14. Physical-Layer MIMO Relaying

    OpenAIRE

    Khina, A.; Kochman, Y.; Erez, U.

    2011-01-01

    The physical-layer network coding (PNC) approach provides improved performance in many scenarios over "traditional" relaying techniques or network coding. This work addresses the generalization of PNC to wireless scenarios where network nodes have multiple antennas. We use a recent matrix decomposition, which allows, by linear pre- and post-processing, to simultaneously transform both channel matrices to triangular forms, where the diagonal entries, corresponding to both channels, are equal. ...

  15. DESIGN THREE PHASE OVERCURRENT RELAYS

    Directory of Open Access Journals (Sweden)

    Mohammed Y Suliman,

    2015-02-01

    Full Text Available  A new design of three phase overcurrent relay described in this paper. The performance of the new design shows the ability to obtain any shape of characteristic with high accuracy and distinguish between transient and steady state fault. This design used more precise and flexible model Sachdev linear model for get any characteristic, also fast measurement theory to measure load current for less than half cycle and good hardware system design controlled by Pentium version 4 processor.

  16. Opportunistic Relay Selection With Limited Feedback

    KAUST Repository

    Eltayeb, Mohammed E.

    2015-08-01

    Relay selection is a simple technique that achieves spatial diversity in cooperative relay networks. Generally, relay selection algorithms require channel state information (CSI) feedback from all cooperating relays to make a selection decision. This requirement poses two important challenges, which are often neglected in the literature. Firstly, the fed back channel information is usually corrupted by additive noise. Secondly, CSI feedback generates a great deal of feedback overhead (air-time) that could result in significant performance hits. In this paper, we propose a compressive sensing (CS) based relay selection algorithm that reduces the feedback overhead of relay networks under the assumption of noisy feedback channels. The proposed algorithm exploits CS to first obtain the identity of a set of relays with favorable channel conditions. Following that, the CSI of the identified relays is estimated using least squares estimation without any additional feedback. Both single and multiple relay selection cases are considered. After deriving closed-form expressions for the asymptotic end-to-end SNR at the destination and the feedback load for different relaying protocols, we show that CS-based selection drastically reduces the feedback load and achieves a rate close to that obtained by selection algorithms with dedicated error-free feedback. © 1972-2012 IEEE.

  17. Creating molecular macrocycles for anion recognition

    Directory of Open Access Journals (Sweden)

    Amar H. Flood

    2016-03-01

    Full Text Available The creation and functionality of new classes of macrocycles that are shape persistent and can bind anions is described. The genesis of triazolophane macrocycles emerges out of activity surrounding 1,2,3-triazoles made using click chemistry; and the same triazoles are responsible for anion capture. Mistakes made and lessons learnt in anion recognition provide deeper understanding that, together with theory, now provides for computer-aided receptor design. The lessons are acted upon in the creation of two new macrocycles. First, cyanostars are larger and like to capture large anions. Second is tricarb, which also favors large anions but shows a propensity to self-assemble in an orderly and stable manner, laying a foundation for future designs of hierarchical nanostructures.

  18. Performance analysis of opportunistic nonregenerative relaying

    KAUST Repository

    Tourki, Kamel

    2013-01-01

    Opportunistic relaying in cooperative communication depends on careful relay selection. However, the traditional centralized method used for opportunistic amplify-and-forward protocols requires precise measurements of channel state information at the destination. In this paper, we adopt the max-min criterion as a relay selection framework for opportunistic amplify-and-forward cooperative communications, which was exhaustively used for the decode-and-forward protocol, and offer an accurate performance analysis based on exact statistics of the local signal-to-noise ratios of the best relay. Furthermore, we evaluate the asymptotical performance and deduce the diversity order of our proposed scheme. Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over Rayleigh fading channels, and we compare the max-min relay selection with their centralized channel state information-based and partial relay selection counterparts.

  19. Alternate transmission relaying based on interference alignment in 3-relay half-duplex MIMO systems

    KAUST Repository

    Park, Seongho

    2012-09-01

    In a half-duplex relaying, the capacity pre-log factor 1/2 is a major drawback in spectral efficiency. This paper proposes a linear precoding/decoding scheme and an alternate relaying protocol in a dual-hop half-duplex system where three relays help the communication between the source and the destination. In our proposed scheme, we consider a phase incoherent method in relays in which the source alternately transmits message signals to the different relays. In addition, we propose a linear interference alignment scheme which can suppress the inter-relay interference resulting from the phase incoherence of relaying. Based on our analysis of degrees of freedom and our simulation results, we show that our proposed scheme achieves additional degrees of freedom compared to the conventional half-duplex relaying. © 2012 IEEE.

  20. Quake's motion modeled in relay test

    International Nuclear Information System (INIS)

    Calhoun, H.J.

    1978-01-01

    Relays in safety-related functions at nuclear plants can now be tested seismically at lower frequencies and with more meaningful force mangnitudes than ever before. A massive, computer-controlled machine shakes the relays with a complex set of frequencies to determine their fragility. NRC has examined the technique by which relay movement is programmed, and has accepted it as an adequate means to do so. The machine, installed last fall, will improve the ability of manufacturers to produce more rugged, vibration-resistant relays, thus increasing system reliability

  1. Relay self interference minimisation using tapped filter

    KAUST Repository

    Jazzar, Saleh

    2013-05-01

    In this paper we introduce a self interference (SI) estimation and minimisation technique for amplify and forward relays. Relays are used to help forward signals between a transmitter and a receiver. This helps increase the signal coverage and reduce the required transmitted signal power. One problem that faces relays communications is the leaked signal from the relay\\'s output to its input. This will cause an SI problem where the new received signal at the relay\\'s input will be added with the unwanted leaked signal from the relay\\'s output. A Solution is proposed in this paper to estimate and minimise this SI which is based upon using a tapped filter at the destination. To get the optimum weights for this tapped filter, some channel parameters must be estimated first. This is performed blindly at the destination without the need of any training. This channel parameter estimation method is named the blind-self-interference-channel-estimation (BSICE) method. The next step in the proposed solution is to estimate the tapped filter\\'s weights. This is performed by minimising the mean squared error (MSE) at the destination. This proposed method is named the MSE-Optimum Weight (MSE-OW) method. Simulation results are provided in this paper to verify the performance of BSICE and MSE-OW methods. © 2013 IEEE.

  2. Protective relaying theory and applications

    CERN Document Server

    Elmore, Walter A

    2003-01-01

    Targeting the latest microprocessor technologies for more sophisticated applications in the field of power system short circuit detection, this revised and updated source imparts fundamental concepts and breakthrough science for the isolation of faulty equipment and minimization of damage in power system apparatus. The Second Edition clearly describes key procedures, devices, and elements crucial to the protection and control of power system function and stability. It includes chapters and expertise from the most knowledgeable experts in the field of protective relaying, and describes micropro

  3. 77 FR 43538 - Misuse of Internet Protocol (IP) Relay Service; Telecommunications Relay Services and Speech-to...

    Science.gov (United States)

    2012-07-25

    ...] Misuse of Internet Protocol (IP) Relay Service; Telecommunications Relay Services and Speech-to-Speech...-Protocol (IP) Relay providers from handling non- emergency calls made by new IP Relay registrants as guest... action is intended to eliminate abuse that has resulted from unauthorized users having access to IP Relay...

  4. Relay Selection and Resource Allocation in One-Way and Two-Way Cognitive Relay Networks

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-05-08

    In this work, the problem of relay selection and resource power allocation in one- way and two-way cognitive relay networks using half duplex channels with different relaying protocols is investigated. Optimization problems for both single and multiple relay selection that maximize the sum rate of the secondary network without degrading the quality of service of the primary network by respecting a tolerated interference threshold were formulated. Single relay selection and optimal power allocation for two-way relaying cognitive radio networks using decode-and-forward and amplify-and-forward protocols were studied. Dual decomposition and subgradient methods were used to find the optimal power allocation. The transmission process to exchange two different messages between two transceivers for two-way relaying technique takes place in two time slots. In the first slot, the transceivers transmit their signals simultaneously to the relay. Then, during the second slot the relay broadcasts its signal to the terminals. Moreover, improvement of both spectral and energy efficiency can be achieved compared with the one-way relaying technique. As an extension, a multiple relay selection for both one-way and two-way relaying under cognitive radio scenario using amplify-and-forward were discussed. A strong optimization tool based on genetic and iterative algorithms was employed to solve the 
formulated optimization problems for both single and multiple relay selection, where discrete relay power levels were considered. Simulation results show that the practical and low-complexity heuristic approaches achieve almost the same performance of the optimal relay selection schemes either with discrete or continuous power distributions while providing a considerable saving in terms of computational complexity.

  5. 77 FR 1039 - Internet-Based Telecommunications Relay Service Numbering

    Science.gov (United States)

    2012-01-09

    ...-Based Telecommunications Relay Service Numbering AGENCY: Federal Communications Commission. ACTION... toll-free numbers by users of Internet- based Telecommunications Relay Services (iTRS). DATES... any rules of particular applicability. Subject: Internet-Based Telecommunications Relay Service...

  6. Opportunistic Relay Selection with Cooperative Macro Diversity

    Directory of Open Access Journals (Sweden)

    Yu Chia-Hao

    2010-01-01

    Full Text Available We apply a fully opportunistic relay selection scheme to study cooperative diversity in a semianalytical manner. In our framework, idle Mobile Stations (MSs are capable of being used as Relay Stations (RSs and no relaying is required if the direct path is strong. Our relay selection scheme is fully selection based: either the direct path or one of the relaying paths is selected. Macro diversity, which is often ignored in analytical works, is taken into account together with micro diversity by using a complete channel model that includes both shadow fading and fast fading effects. The stochastic geometry of the network is taken into account by having a random number of randomly located MSs. The outage probability analysis of the selection differs from the case where only fast fading is considered. Under our framework, distribution of the received power is formulated using different Channel State Information (CSI assumptions to simulate both optimistic and practical environments. The results show that the relay selection gain can be significant given a suitable amount of candidate RSs. Also, while relay selection according to incomplete CSI is diversity suboptimal compared to relay selection based on full CSI, the loss in average throughput is not too significant. This is a consequence of the dominance of geometry over fast fading.

  7. Decode and Zero-Forcing Forward Relaying with Relay Selection in Cognitive Radio Systems

    KAUST Repository

    Park, Kihong

    2014-05-01

    In this paper, we investigate a cognitive radio (CR) relay network with multiple relay nodes that help forwarding the signal of CR users. Best relay selection is considered to take advantage of its low complexity of implementation. When the primary user (PU) is located close to the relay nodes, the performance of the secondary network is severely degraded due to the interference power constraint during the transmission in the second hop. We propose a decode and zero-forcing forward scheme to suppress the interference power at the relay nodes and analyze the statistics of the end-to-end signal-to-noise ratio when the relay nodes are located arbitrarily and experience therefore non-identical Rayleigh fading channels. Numerical results validate our theoretical results and show that our proposed scheme improves the performance of the CR network when the PU is close to the relay nodes. © 2014 IEEE.

  8. On the achievable degrees of freedom of alternate MIMO relaying with multiple AF relays

    KAUST Repository

    Park, Kihong

    2012-03-01

    In this paper, we consider a two-hop relaying network where one source, one destination, and multiple amplify-and-forward (AF) relays equipped with M antennas operate in a half-duplex mode. In order to compensate for the inherent loss of capacity pre-log factor of 1/2 due to half-duplex relaying, we propose a new transmission protocol which combines alternate relaying and inter-relay interference alignment. We prove that the proposed scheme can (i) exploits M degrees of freedom (DOFs) and (ii) perfectly recover the pre-log factor loss if the number of relays is at least six. From our selected numerical results, we show that our proposed scheme gives significant improvement over conventional AF relaying which offers only M/2 DOFs. © 2012 IEEE.

  9. On Alternate Relaying with Improper Gaussian Signaling

    KAUST Repository

    Gaafar, Mohamed

    2016-06-06

    In this letter, we investigate the potential benefits of adopting improper Gaussian signaling (IGS) in a two-hop alternate relaying (AR) system. Given the known benefits of using IGS in interference-limited networks, we propose to use IGS to relieve the inter-relay interference (IRI) impact on the AR system assuming no channel state information is available at the source. In this regard, we assume that the two relays use IGS and the source uses proper Gaussian signaling (PGS). Then, we optimize the degree of impropriety of the relays signal, measured by the circularity coefficient, to maximize the total achievable rate. Simulation results show that using IGS yields a significant performance improvement over PGS, especially when the first hop is a bottleneck due to weak source-relay channel gains and/or strong IRI.

  10. Planetary Sources for Reducing Sulfur Compounds for Cyanosulfidic Origins of Life Chemistry

    Science.gov (United States)

    Ranjan, S.; Todd, Z.; Sutherland, J.; Sasselov, D. D.

    2017-11-01

    Sulfidic anions (e.g, HS-, HSO3-) are invoked in prebiotic chemistries, but their abundance on early Earth is poorly constrained. We use simple equilibrium chemistry to estimate the abundance of sulfidic anions in surficial aquatic reservoirs.

  11. A NEW RELAY DESIGN FOR REACTIVE POWER COMPENSATION AND ECONOMICAL COMPARISION WITH CLASSICAL RELAY

    Directory of Open Access Journals (Sweden)

    Mustafa ŞEKKELİ

    2007-02-01

    Full Text Available In most cases, reactive power compensation is otomatically achieved with reactive power control relay by switching on and off, stationary shunt capasitors to the electrical network. İn this study , a new relay has been designed and developed. İn this method, capasitors which is switched on and of are optimally choosen. İn classical relay , only one capasitor can be added or extructed to the network. But,in designing new relay, 1,2 or 3 capasitor banks which are nearest value for desired inductive reactive power can be optimally choosen. As a result , switching number of capacitor and contactor is reduced minimum value and line is loaded less inductive current , it means that less active power losses. New designed relay has been compared with classical one economically . This relay has been manufactured and approved experimantally.

  12. Time of arrival based location estimation for cooperative relay networks

    KAUST Repository

    Çelebi, Hasari Burak

    2010-09-01

    In this paper, we investigate the performance of a cooperative relay network performing location estimation through time of arrival (TOA). We derive Cramer-Rao lower bound (CRLB) for the location estimates using the relay network. The analysis is extended to obtain average CRLB considering the signal fluctuations in both relay and direct links. The effects of the channel fading of both relay and direct links and amplification factor and location of the relay node on average CRLB are investigated. Simulation results show that the channel fading of both relay and direct links and amplification factor and location of relay node affect the accuracy of TOA based location estimation. ©2010 IEEE.

  13. Modeling study of the ABS relay valve

    Science.gov (United States)

    Lei, Ming; Lin, Min; Guo, Bin; Luo, Zai; Xu, Weidong

    2011-05-01

    The ABS (anti-lock braking system) relay valve is the key component of anti-lock braking system in most commercial vehicles such as trucks, tractor-trailers, etc. In this paper, structure of ABS relay valve and its work theory were analyzed. Then a mathematical model of ABS relay valve, which was investigated by dividing into electronic part, magnetic part, pneumatic part and mechanical part, was set up. The displacement of spools and the response of pressure increasing, holding, releasing of ABS relay valve were simulated and analyzed under conditions of control pressure 500 KPa, braking pressure 600 KPa, atmospheric pressure 100 KPa and air temperature 310 K. Thisarticle provides reliable theory for improving the performance and efficiency of anti-lock braking system of vehicles.

  14. A MHO distance relay device in EMTPWorks

    Energy Technology Data Exchange (ETDEWEB)

    Gerin-Lajoie, Luc [Etudes de reseaux, Planification des actifs, Hydro-Quebec (TransEnergie), Complexe Desjardins, East Tower, 10th Floor, Montreal, QC (Canada)

    2009-03-15

    Distance relays are widely used for protection of transmission lines. Usually, the nonlinear nature of an arcing fault requires that a time model be implemented to determine if the relay detects or not this fault condition. Moreover, the mutual effect of line conductors for single or multiphase faults requires that all three phases of the relay be modelized. This paper describes in detail a first generic MHO distance relay in EMTPWorks based on three separate single-phase impedance vectors. Cosine-sine filters are used to perform the phasor representation of the fundamental current and voltage computed over a 50/60 Hz sliding time window. Validation of the measured impedance function of the model is compared with the real apparent impedance of the network. This paper also discusses logical operations to initiate the opening of line breakers. (author)

  15. LTE-Advanced Relay Technology and Standardization

    CERN Document Server

    Yuan, Yifei

    2013-01-01

    LTE-Advanced Relay Technology and Standardization provides a timely reference work for relay technology with the finalizing of LTE Release 10 specifications. LTE-Advanced is quickly becoming the global standard for 4G cellular communications. The relay technology, as one of the key features in LTE-Advanced, helps not only to improve the system coverage and capacity, but also to save the costs of laying wireline backhaul. As a leading researcher in the field of LTE-Advanced standards, the author provides an in-depth description of LTE-A relay technology, and explains in detail the standard specification and design principles.     Readers from both academic and industrial fields can find sections of interest to them: Sections 2 & 4 could benefit researchers in academia and those who are engaged in exploratory work, while Sections 3 & 4 are more useful to engineers. Dr. Yifei Yuan is the Technical Director at the Standards Department of ZTE Inc.

  16. Coordinated Direct and Relay Transmission with Linear Non-Regenerative Relay Beamforming

    DEFF Research Database (Denmark)

    Sun, Fan; De Carvalho, Elisabeth; Popovski, Petar

    2012-01-01

    Joint processing of multiple communication flows in wireless systems has given rise to a number of novel transmission techniques, notably the two-way relaying, but also more general traffic scenarios, such as coordinated direct and relay (CDR) transmissions. In a CDR scheme the relay has a central...... role in managing the interference and boosting the overall system performance. In this letter we consider the case in which an amplify-and-forward relay has multiple antennas and can use beamforming to support the coordinated transmissions. We focus on one representative traffic type with one uplink...

  17. Distributed Antenna Channels with Regenerative Relaying: Relay Selection and Asymptotic Capacity

    Directory of Open Access Journals (Sweden)

    Aitor del Coso

    2007-11-01

    Full Text Available Multiple-input-multiple-output (MIMO techniques have been widely proposed as a means to improve capacity and reliability of wireless channels, and have become the most promising technology for next generation networks. However, their practical deployment in current wireless devices is severely affected by antenna correlation, which reduces their impact on performance. One approach to solve this limitation is relaying diversity. In relay channels, a set of N wireless nodes aids a source-destination communication by relaying the source data, thus creating a distributed antenna array with uncorrelated path gains. In this paper, we study this multiple relay channel (MRC following a decode-and-forward (D&F strategy (i.e., regenerative forwarding, and derive its achievable rate under AWGN. A half-duplex constraint on relays is assumed, as well as distributed channel knowledge at both transmitter and receiver sides of the communication. For this channel, we obtain the optimum relay selection algorithm and the optimum power allocation within the network so that the transmission rate is maximized. Likewise, we bound the ergodic performance of the achievable rate and derive its asymptotic behavior in the number of relays. Results show that the achievable rate of regenerative MRC grows as the logarithm of the Lambert W function of the total number of relays, that is, 𝒞=log⁡2(W0(N. Therefore, D&F relaying, cannot achieve the capacity of actual MISO channels.

  18. Distributed Antenna Channels with Regenerative Relaying: Relay Selection and Asymptotic Capacity

    Directory of Open Access Journals (Sweden)

    del Coso Aitor

    2007-01-01

    Full Text Available Multiple-input-multiple-output (MIMO techniques have been widely proposed as a means to improve capacity and reliability of wireless channels, and have become the most promising technology for next generation networks. However, their practical deployment in current wireless devices is severely affected by antenna correlation, which reduces their impact on performance. One approach to solve this limitation is relaying diversity. In relay channels, a set of wireless nodes aids a source-destination communication by relaying the source data, thus creating a distributed antenna array with uncorrelated path gains. In this paper, we study this multiple relay channel (MRC following a decode-and-forward (D&F strategy (i.e., regenerative forwarding, and derive its achievable rate under AWGN. A half-duplex constraint on relays is assumed, as well as distributed channel knowledge at both transmitter and receiver sides of the communication. For this channel, we obtain the optimum relay selection algorithm and the optimum power allocation within the network so that the transmission rate is maximized. Likewise, we bound the ergodic performance of the achievable rate and derive its asymptotic behavior in the number of relays. Results show that the achievable rate of regenerative MRC grows as the logarithm of the Lambert W function of the total number of relays, that is, . Therefore, D&F relaying, cannot achieve the capacity of actual MISO channels.

  19. Partial relay selection in underlay cognitive networks with fixed gain relays

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-05-01

    In a communication system with multiple cooperative relays, selecting the best relay utilizes the available spectrum more efficiently. However, selective relaying poses a different problem in underlay cognitive networks compared to the traditional cooperative networks due to interference thresholds to the primary users. In most cases, a best relay is the one which provides the maximum end-to-end signal to noise ratio (SNR). This approach needs plenty of instantaneous channel state information (CSI). The CSI burden could be reduced by partial relay selection. In this paper, a partial relay selection scheme is presented and analyzed for an underlay cognitive network with fixed gain relays operating in the vicinity of a primary user. The system model is adopted in a way that each node needs minimal CSI to perform its task. The best relay is chosen on the basis of maximum source to relay link SNR which then forwards the message to the destination. We derive closed form expressions for the received SNR distributions, system outage, probability of bit error and average channel capacity of the system. The derived results are confirmed through simulations. © 2012 IEEE.

  20. Relay Runners Catch The Rays

    CERN Multimedia

    2004-01-01

    Athletes sizzled around CERN on Wednesday 19 May at the 34th annual relay race. On one of the warmest days of the year so far, sunkissed competitors ran for the finish line and then straight for the drinks table. The Shabbys were on fire again, hurtling across the line first in a time of 10 min. 42.6 sec. and making an even stronger claim to being hailed as the traditional winners of the race with their fourth triumph in a row. Also on form were the Lynx Runners who won the Veteran's trophy, continuing their winning ways since 2002 and placing 29th overall. Ildefons Magrans of the ALICE Quarks on the Loose team ran the fastest 1000m in a time of 2 min. 47 sec. Second-placed Charmilles Technologies won the Open category in a time of 11 min. 03 sec., taking the prize for teams whose members work in different departments or who come from outside CERN. The OPALadies won the women's trophy and placed 48th. With 9 trophies up for grabs, more than 300 people in 55 teams ran the fun run, covering distances of 1000m ...

  1. Relay selection from an effective capacity perspective

    KAUST Repository

    Yang, Yuli

    2013-09-01

    In this work, we consider a cooperative network where multiple relay nodes having different modulation capabilities assist the end-to-end communication between a source and its destination. Firstly, we evaluate the effective capacity (EC) performance of the network under study. According to the analysis, an EC-based relay selection criterion is proposed. Based on the proposed selection rule and half-duplex decode-and-forward protocol, the activated relays cooperatively help with the packet transmission from the source. At the destination, packet combining is taken into account to improve the quality of service. Compared to the popular scheme, opportunistic relay selection, numerical results are provided to prove the validity and advantages of our proposed scheme in certain scenarios. Moreover, the analysis presented herein offers a convenient tool to the relaying transmission design, specifically on which relay selection scheme should be used as well as how to choose the receiving strategy between with and without packet combining at the destination. © 2013 IEEE.

  2. Physical Layer Security Using Two-Path Successive Relaying.

    Science.gov (United States)

    Liau, Qian Yu; Leow, Chee Yen; Ding, Zhiguo

    2016-06-09

    Relaying is one of the useful techniques to enhance wireless physical-layer security. Existing literature shows that employing full-duplex relay instead of conventional half-duplex relay improves secrecy capacity and secrecy outage probability, but this is at the price of sophisticated implementation. As an alternative, two-path successive relaying has been proposed to emulate operation of full-duplex relay by scheduling a pair of half-duplex relays to assist the source transmission alternately. However, the performance of two-path successive relaying in secrecy communication remains unexplored. This paper proposes a secrecy two-path successive relaying protocol for a scenario with one source, one destination and two half-duplex relays. The relays operate alternately in a time division mode to forward messages continuously from source to destination in the presence of an eavesdropper. Analytical results reveal that the use of two half-duplex relays in the proposed scheme contributes towards a quadratically lower probability of interception compared to full-duplex relaying. Numerical simulations show that the proposed protocol achieves the ergodic achievable secrecy rate of full-duplex relaying while delivering the lowest probability of interception and secrecy outage probability compared to the existing half duplex relaying, full duplex relaying and full duplex jamming schemes.

  3. Physical Layer Security Using Two-Path Successive Relaying

    Directory of Open Access Journals (Sweden)

    Qian Yu Liau

    2016-06-01

    Full Text Available Relaying is one of the useful techniques to enhance wireless physical-layer security. Existing literature shows that employing full-duplex relay instead of conventional half-duplex relay improves secrecy capacity and secrecy outage probability, but this is at the price of sophisticated implementation. As an alternative, two-path successive relaying has been proposed to emulate operation of full-duplex relay by scheduling a pair of half-duplex relays to assist the source transmission alternately. However, the performance of two-path successive relaying in secrecy communication remains unexplored. This paper proposes a secrecy two-path successive relaying protocol for a scenario with one source, one destination and two half-duplex relays. The relays operate alternately in a time division mode to forward messages continuously from source to destination in the presence of an eavesdropper. Analytical results reveal that the use of two half-duplex relays in the proposed scheme contributes towards a quadratically lower probability of interception compared to full-duplex relaying. Numerical simulations show that the proposed protocol achieves the ergodic achievable secrecy rate of full-duplex relaying while delivering the lowest probability of interception and secrecy outage probability compared to the existing half duplex relaying, full duplex relaying and full duplex jamming schemes.

  4. Individual Channel Estimation in a Diamond Relay Network Using Relay-Assisted Training

    Directory of Open Access Journals (Sweden)

    Xianwen He

    2017-01-01

    Full Text Available We consider the training design and channel estimation in the amplify-and-forward (AF diamond relay network. Our strategy is to transmit the source training in time-multiplexing (TM mode while each relay node superimposes its own relay training over the amplified received data signal without bandwidth expansion. The principal challenge is to obtain accurate channel state information (CSI of second-hop link due to the multiaccess interference (MAI and cooperative data interference (CDI. To maintain the orthogonality between data and training, a modified relay-assisted training scheme is proposed to migrate the CDI, where some of the cooperative data at the relay are discarded to accommodate relay training. Meanwhile, a couple of optimal zero-correlation zone (ZCZ relay-assisted sequences are designed to avoid MAI. At the destination node, the received signals from the two relay nodes are combined to achieve spatial diversity and enhanced data reliability. The simulation results are presented to validate the performance of the proposed schemes.

  5. Reactive relay selection in underlay cognitive networks with fixed gain relays

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-06-01

    Best relay selection is a bandwidth efficient technique for multiple relay environments without compromising the system performance. The problem of relay selection is more challenging in underlay cognitive networks due to strict interference constraints to the primary users. Generally, relay selection is done on the basis of maximum end-to-end signal to noise ratio (SNR). However, it requires large amounts of channel state information (CSI) at different network nodes. In this paper, we present and analyze a reactive relay selection scheme in underlay cognitive networks where the relays are operating with fixed gains near a primary user. The system model minimizes the amount of CSI required at different nodes and the destination selects the best relay on the basis of maximum relay to destination SNR. We derive close form expressions for the received SNR statistics, outage probability, bit error probability and average channel capacity of the system. Simulation results are also presented to confirm the validity of the derived expressions. © 2012 IEEE.

  6. A genetic algorithm for multiple relay selection in two-way relaying cognitive radio networks

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-09-01

    In this paper, we investigate a multiple relay selection scheme for two-way relaying cognitive radio networks where primary users and secondary users operate on the same frequency band. More specifically, cooperative relays using Amplifyand- Forward (AF) protocol are optimally selected to maximize the sum rate of the secondary users without degrading the Quality of Service (QoS) of the primary users by respecting a tolerated interference threshold. A strong optimization tool based on genetic algorithm is employed to solve our formulated optimization problem where discrete relay power levels are considered. Our simulation results show that the practical heuristic approach achieves almost the same performance of the optimal multiple relay selection scheme either with discrete or continuous power distributions. Copyright © 2013 by the Institute of Electrical and Electronic Engineers, Inc.

  7. Capacity Bounds and Mapping Design for Binary Symmetric Relay Channels

    Directory of Open Access Journals (Sweden)

    Majid Nasiri Khormuji

    2012-12-01

    Full Text Available Capacity bounds for a three-node binary symmetric relay channel with orthogonal components at the destination are studied. The cut-set upper bound and the rates achievable using decode-and-forward (DF, partial DF and compress-and-forward (CF relaying are first evaluated. Then relaying strategies with finite memory-length are considered. An efficient algorithm for optimizing the relay functions is presented. The Boolean Fourier transform is then employed to unveil the structure of the optimized mappings. Interestingly, the optimized relay functions exhibit a simple structure. Numerical results illustrate that the rates achieved using the optimized low-dimensional functions are either comparable to those achieved by CF or superior to those achieved by DF relaying. In particular, the optimized low-dimensional relaying scheme can improve on DF relaying when the quality of the source-relay link is worse than or comparable to that of other links.

  8. Cognitive Relay Networks: A Comprehensive Survey

    Directory of Open Access Journals (Sweden)

    Ayesha Naeem

    2015-07-01

    Full Text Available Cognitive radio is an emerging technology to deal with the scarcity and requirement of radio spectrum by dynamically assigning spectrum to unlicensed user . This revolutionary technology shifts the paradigm in the wireless system design by all owing unlicensed user the ability to sense, adapt and share the dynamic spectrum. Cognitive radio technology have been applied to different networks and applications ranging from wireless to public saf ety, smart grid, medical, rela y and cellular applications to increase the throughput and spectrum efficiency of the network. Among these applications, cognitive relay networks is one of the application where cognitive radio technology has been applied. Cognitiv e rela y network increases the network throughput by reducing the complete pa th loss and also by ensuring cooper ation among secondary users and cooperation among primary and secondary users. In this paper , our aim is to provide a survey on cognitive relay network. We also provide a detailed review on existing schemes in cognitive relay networks on the basis of relaying protocol, relay cooperation and channel model.

  9. Developing a Domain Model for Relay Circuits

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth

    2009-01-01

    for railways madeby Bjørner et.al., however our model is more general: the components can be of any kind and can later be refined to e.g. railway components or circuit components. Then we show how the abstract network model can be refined into an explicit model for relay circuits. The circuit model describes...... the statics as well as the dynamics of relay circuits, i.e. how a relay circuit can be composed legally from electrical components as well as how the components may change state over time. Finally the circuit model is transformed into an executable model, and we show how a concrete circuit can be defined...

  10. Performance of a Cognitive Relay Network under AF Relay Selection Scheme with Imperfect Channel Estimation

    Directory of Open Access Journals (Sweden)

    B. Prasad

    2016-06-01

    Full Text Available In this paper outage performance of a secondary user (SU is evaluated under amplify and forward (AF relay selection scheme with an imperfect channel state information (CSIwhile sharing spectrum in an underlay cognitive radio network (CRN. In underlay, the SU coexists with primary user (PU in the same band provided the interference produced by SU at the PU receiver is below the interference threshold of PU which limits the transmission power of SU and coverage area. Relays help to improve the performance of SU in underlay. However relays are also constrained in transmit power due to interference constraint imposed by PU. Closed form expression of the outage probability of SU with maximum transmit power constraint of relay under imperfect CSI is derived. A scaling factor based power control is used for the SU transmitter and the relay in order to maintain the interference constraint at PU receiver due to imperfect CSI. The impact of different parameters viz. correlation coefficient, channel estimation error, tolerable interference threshold, number of relays and the maximum transmit power constraint of relay on SU performance is investigated. A MATLAB based test bed has also been developed to carry out simulation in order to validate the theoretical result.

  11. CERN Relay Race: information for drivers

    CERN Multimedia

    2012-01-01

    The CERN relay race will take place around the Meyrin site on Thursday, 24 May starting at 12.15. If possible, please avoid driving on the site during this 20-minute period. If you do meet runners while driving your car, please STOP until they have all passed. In addition, there will be a Nordic Walking event which will finish around 12.50. This should not block the roads, but please drive carefully during this time. Thank you for your cooperation. Details on how to register your team for the relay race can be found here.

  12. Deep space optical communication via relay satellite

    Science.gov (United States)

    Dolinar, S.; Vilnrotter, V.; Gagliardi, R.

    1981-01-01

    The application of optical communications for a deep space link via an earth-orbiting relay satellite is discussed. The system uses optical frequencies for the free-space channel and RF links for atmospheric transmission. The relay satellite is in geostationary orbit and contains the optics necessary for data processing and formatting. It returns the data to earth through the RF terrestrial link and also transmits an optical beacon to the satellite for spacecraft return pointing and for the alignment of the transmitting optics. Future work will turn to modulation and coding, pointing and tracking, and optical-RF interfacing.

  13. Advanced Strategic and Tactical Relay Request Management for the Mars Relay Operations Service

    Science.gov (United States)

    Allard, Daniel A.; Wallick, Michael N.; Gladden, Roy E.; Wang, Paul; Hy, Franklin H.

    2013-01-01

    This software provides a new set of capabilities for the Mars Relay Operations Service (MaROS) in support of Strategic and Tactical relay, including a highly interactive relay request Web user interface, mission control over relay planning time periods, and mission management of allowed strategic vs. tactical request parameters. Together, these new capabilities expand the scope of the system to include all elements critical for Tactical relay operations. Planning of replay activities spans a time period that is split into two distinct phases. The first phase is called Strategic, which begins at the time that relay opportunities are identified, and concludes at the point that the orbiter generates the flight sequences for on board execution. Any relay request changes from this point on are called Tactical. Tactical requests, otherwise called Orbit - er Relay State Changes (ORSC), are highly restricted in terms of what types of changes can be made, and the types of parameters that can be changed may differ from one orbiter to the next. For example, one orbiter may be able to delay the start of a relay request, while another may not. The legacy approach to ORSC management involves exchanges of e-mail with "requests for change" and "acknowledgement of approval," with no other tracking of changes outside of e-mail folders. MaROS Phases 1 and 2 provided the infrastructure for strategic relay for all supported missions. This new version, 3.0, introduces several capabilities that fully expand the scope of the system to include tactical relay. One new feature allows orbiter users to manage and "lock" Planning Periods, which allows the orbiter team to formalize the changeover from Strategic to Tactical operations. Another major feature allows users to interactively submit tactical request changes via a Web user interface. A third new feature allows orbiter missions to specify allowed tactical updates, which are automatically incorporated into the tactical change process

  14. Outage performance of two-way DF relaying systems with a new relay selection metric

    KAUST Repository

    Hyadi, Amal

    2012-04-01

    This paper investigates a new constrained relay selection scheme for two-way relaying systems where two end terminals communicate simultaneously via a relay. The introduced technique is based on the maximization of the weighted sum rate of both users. To evaluate the performance of the proposed system, the outage probability is derived in a general case (where an arbitrary channel is considered), and then over independently but not necessarily identically distributed (i.n.i.d.) Rayleigh fading channels. The analytical results are verified through simulations. © 2012 IEEE.

  15. Relay communications strategies for Mars exploration through 2020

    Science.gov (United States)

    Edwards, Charles D., Jr.; Arnold, B.; DePaula, R.; Kazz, G.; Lee, C.; Noreen, G.

    2005-01-01

    In this paper we will examine NASA's strategy for relay communications support of missions planned for this decade, and discuss options for longer-term relay network evolution in support of second-decade missions.

  16. Adaptive relaying for ground fault protection of a distribution network

    Energy Technology Data Exchange (ETDEWEB)

    Sachdev, M.S.; Sidhu, T.S.; Talukdar, B.K.

    1995-12-31

    With the advent of digital technology and microprocessor-based relays, it is possible to continuously monitor a power network, analyze it in real time, and change the relay settings to those most suitable at that time, thereby achieving improved protection of the network. This approach, known as adaptive relaying, was applied to the Saskatoon distribution network. This paper describes the software modules developed for setting ground fault overcurrent relays in the adaptive relay protection system. The major task in this system was the on-line coordination of relays, as most faults in a distribution system are of the single-phase to ground type and current unbalance due to single-phase loading contributes to the complexity of relay coordination. The modules served for network topology detection, state estimation, fault analysis, and relay setting and coordination. The paper also presents results of a study of the proposed adaptive ground fault protection scheme using a model distribution network.

  17. Dynamic Relaying in 3GPP LTE-Advanced Networks

    Directory of Open Access Journals (Sweden)

    Van Phan Vinh

    2009-01-01

    Full Text Available Relaying is one of the proposed technologies for LTE-Advanced networks. In order to enable a flexible and reliable relaying support, the currently adopted architectural structure of LTE networks has to be modified. In this paper, we extend the LTE architecture to enable dynamic relaying, while maintaining backward compatibility with LTE Release 8 user equipments, and without limiting the flexibility and reliability expected from relaying. With dynamic relaying, relays can be associated with base stations on a need basis rather than in a fixed manner which is based only on initial radio planning. Proposals are also given on how to further improve a relay enhanced LTE network by enabling multiple interfaces between the relay nodes and their controlling base stations, which can possibly be based on technologies different from LTE, so that load balancing can be realized. This load balancing can be either between different base stations or even between different networks.

  18. Capacity gains of buffer-aided moving relays

    KAUST Repository

    Zafar, Ammar

    2017-03-14

    This work investigates the gain due to reduction in path loss by deploying buffer-aided moving relaying. In particular, the increase in gain due to moving relays is studied for dual-hop broadcast channels and the bidirectional relay channel. It is shown that the exploited gains in these channels due to buffer-aided relaying can be enhanced by utilizing the fact that a moving relay can communicate with the terminal closest to it and store the data in the buffer and then forward the data to the intended destination when it comes in close proximity with the destination. Numerical results show that for both the considered channels the achievable rates are increased as compared to the case of stationary relays. Numerical results also show that more significant increase in performance is seen when the relay moves to-and-fro between the source and the relay.

  19. Improper Signaling for Virtual Full-Duplex Relay Systems

    KAUST Repository

    Gaafar, Mohamed

    2017-02-14

    Virtual full-duplex (VFD) is a powerful solution to compensate the rate loss of half-duplex relaying without the need to full-duplex capable nodes. Inter-relay interference (IRI) challenges the operation of VFD relaying systems. Recently, improper signaling is employed at both relays of the VFD to mitigate the IRI by imposing the same signal characteristics for both relays. To further boost the achievable rate performance, asymmetric time sharing VFD relaying system is adopted with different improper signals at the half-duplex relays. The joint tuning of the three design parameters improves the achievable rate performance at different ranges of IRI and different relays locations. Extensive simulation results are presented and analyzed to show the achievable rate gain of the proposed system and understand the system behavior.

  20. Capacity Bounds and Mapping Design for Binary Symmetric Relay Channels

    OpenAIRE

    Majid Nasiri Khormuji; Mikael Skoglund

    2012-01-01

    Capacity bounds for a three-node binary symmetric relay channel with orthogonal components at the destination are studied. The cut-set upper bound and the rates achievable using decode-and-forward (DF), partial DF and compress-and-forward (CF) relaying are first evaluated. Then relaying strategies with finite memory-length are considered. An efficient algorithm for optimizing the relay functions is presented. The Boolean Fourier transform is then employed to unveil the structure of the optimi...

  1. Modelling and Verification of Relay Interlocking Systems

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth; Bliguet, Marie Le; Kjær, Andreas

    2010-01-01

    This paper describes how relay interlocking systems as used by the Danish railways can be formally modelled and verified. Such systems are documented by circuit diagrams describing their static layout. It is explained how to derive a state transition system model for the dynamic behaviour of a re...

  2. 49 CFR 236.589 - Relays.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Relays. 236.589 Section 236.589 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF... once every six years. (b) [Reserved] [49 FR 3387, Jan. 26, 1984] ...

  3. Relay cropping as a sustainable approach

    NARCIS (Netherlands)

    Tanveer, Mohsin; Anjum, Shakeel Ahmad; Hussain, Saddam; Cerda Bolinches, Artemio; Ashraf, Umair

    2017-01-01

    Climate change, soil degradation, and depletion of natural resources are becoming the most prominent challenges for crop productivity and environmental sustainability in modern agriculture. In the scenario of conventional farming system, limited chances are available to cope with these issues. Relay

  4. Relay Feedback Analysis for Double Integral Plants

    Directory of Open Access Journals (Sweden)

    Zhen Ye

    2011-01-01

    Full Text Available Double integral plants under relay feedback are studied. Complete results on the uniqueness of solutions, existence, and stability of the limit cycles are established using the point transformation method. Analytical expressions are also given for determining the amplitude and period of a limit cycle from the plant parameters.

  5. SWIPT in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma

    2017-02-09

    In this paper, we consider a multiuser multiple- input multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting relays and multiple destinations. Since the end-to-end sum rate maximization problem is intractable, we tackle a simplified problem where we maximize the sum of the harvested energy at the relays, we employ the block diagonalization (BD) procedure at the source, and we mitigate the interference between the relay- destination channels. The interference mitigation at the destinations is managed in two ways: either to fix the interference covariance matrices at the destination and update them at each iteration until convergence, or to cancel the interference using an algorithm similar to the BD method. We provide numerical results to show the relevance of our proposed solution.

  6. A low complexity algorithm for multiple relay selection in two-way relaying Cognitive Radio networks

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-06-01

    In this paper, a multiple relay selection scheme for two-way relaying cognitive radio network is investigated. We consider a cooperative Cognitive Radio (CR) system with spectrum sharing scenario using Amplify-and-Forward (AF) protocol, where licensed users and unlicensed users operate on the same frequency band. The main objective is to maximize the sum rate of the unlicensed users allowed to share the spectrum with the licensed users by respecting a tolerated interference threshold. A practical low complexity heuristic approach is proposed to solve our formulated optimization problem. Selected numerical results show that the proposed algorithm reaches a performance close to the performance of the optimal multiple relay selection scheme either with discrete or continuous power distributions while providing a considerable saving in terms of computational complexity. In addition, these results show that our proposed scheme significantly outperforms the single relay selection scheme. © 2013 IEEE.

  7. Optimal relay selection and power allocation for cognitive two-way relaying networks

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2012-06-01

    In this paper, we present an optimal scheme for power allocation and relay selection in a cognitive radio network where a pair of cognitive (or secondary) transceiver nodes communicate with each other assisted by a set of cognitive two-way relays. The secondary nodes share the spectrum with a licensed primary user (PU), and each node is assumed to be equipped with a single transmit/receive antenna. The interference to the PU resulting from the transmission from the cognitive nodes is kept below a specified limit. We propose joint relay selection and optimal power allocation among the secondary user (SU) nodes achieving maximum throughput under transmit power and PU interference constraints. A closed-form solution for optimal allocation of transmit power among the SU transceivers and the SU relay is presented. Furthermore, numerical simulations and comparisons are presented to illustrate the performance of the proposed scheme. © 2012 IEEE.

  8. 76 FR 18490 - Contributions to the Telecommunications Relay Service Fund

    Science.gov (United States)

    2011-04-04

    ...] Contributions to the Telecommunications Relay Service Fund AGENCY: Federal Communications Commission. ACTION... service to participate in and contribute to the Telecommunications Relay Services (TRS) Fund. The law... INFORMATION: This is a summary of the Commission's Contributions to the Telecommunications Relay Service Fund...

  9. 76 FR 65965 - Contributions to the Telecommunications Relay Services Fund

    Science.gov (United States)

    2011-10-25

    ...] Contributions to the Telecommunications Relay Services Fund AGENCY: Federal Communications Commission. ACTION... Telecommunications Relay Services (TRS) Fund in a manner prescribed by regulation that is consistent with and... . SUPPLEMENTARY INFORMATION: This is a summary of the Commission's Contributions to the Telecommunications Relay...

  10. 76 FR 59551 - Internet-Based Telecommunications Relay Service Numbering

    Science.gov (United States)

    2011-09-27

    ... Docket No. 10-191; FCC 11-123] Internet-Based Telecommunications Relay Service Numbering AGENCY: Federal... Telecommunications Relay Service (iTRS). These rules specifically address Video Relay Service (VRS), which allows... SBA has developed a small business size standard for Wired Telecommunications Carriers, which consists...

  11. 76 FR 72124 - Internet-Based Telecommunications Relay Service Numbering

    Science.gov (United States)

    2011-11-22

    ... Docket No. 10-191; FCC 11-123] Internet-Based Telecommunications Relay Service Numbering AGENCY: Federal..., the information collection associated with the Commission's Internet- Based Telecommunications Relay... Telecommunications Relay Service Numbering, CG Docket No. 03-123; WC Docket No. 05-196; WC Docket No. 10-191; FCC 11...

  12. Dynamic Relaying in 3GPP LTE-Advanced Networks

    DEFF Research Database (Denmark)

    Teyeb, Oumer Mohammed; Van Phan, Vinh; Redana, Simone

    2009-01-01

    Relaying is one of the proposed technologies for LTE-Advanced networks. In order to enable a flexible and reliable relaying support, the currently adopted architectural structure of LTE networks has to be modified. In this paper, we extend the LTE architecture to enable dynamic relaying, while ma...

  13. Chemistry of rare elements

    International Nuclear Information System (INIS)

    Tananaev, I.V.

    1988-01-01

    The main directions of the research in the field of rare element chemistry (mainly rare earths, as well as In, U, Th, V, Nb, Ta, Mo, W) carried out for the recent decade in the laboratory of chemistry of rare elements and inorganic polymers of the USSR Academy of Sciences Institute, of General and Inorganic Chemistry (IGIC) are reviewed. The research of synthesis, structure and properties of rare earth phosphites, phoshates, arsenates, selenates, selenites and borates, as well as rare earth compounds with mixed oxide anions is of great importance. The fields of practical application of these compounds in view of their unique properties are noted

  14. Iterative Relay Scheduling with Hybrid ARQ under Multiple User Equipment (Type II) Relay Environments

    KAUST Repository

    Nam, Sung Sik

    2018-01-09

    In this work, we propose an iterative relay scheduling with hybrid ARQ (IRS-HARQ) scheme which realizes fast jump-in/successive relaying and subframe-based decoding under the multiple user equipment (UE) relay environments applicable to the next-generation cellular systems (e.g., LTE-Advanced and beyond). The proposed IRS-HARQ aims to increase the achievable data rate by iteratively scheduling a relatively better UE relay closer to the end user in a probabilistic sense, provided that the relay-to-end user link should be operated in an open-loop and transparent mode. The latter is due to the fact that not only there are no dedicated control channels between the UE relay and the end user but also a new cell is not created. Under this open-loop and transparent mode, our proposed protocol is implemented by partially exploiting the channel state information based on the overhearing mechanism of ACK/NACK for HARQ. Further, the iterative scheduling enables UE-to-UE direct communication with proximity that offers spatial frequency reuse and energy saving.

  15. Relay Precoder Optimization in MIMO-Relay Networks With Imperfect CSI

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2011-11-01

    In this paper, we consider robust joint designs of relay precoder and destination receive filters in a nonregenerative multiple-input multiple-output (MIMO) relay network. The network consists of multiple source-destination node pairs assisted by a MIMO-relay node. The channel state information (CSI) available at the relay node is assumed to be imperfect. We consider robust designs for two models of CSI error. The first model is a stochastic error (SE) model, where the probability distribution of the CSI error is Gaussian. This model is applicable when the imperfect CSI is mainly due to errors in channel estimation. For this model, we propose robust minimum sum mean square error (SMSE), MSE-balancing, and relay transmit power minimizing precoder designs. The next model for the CSI error is a norm-bounded error (NBE) model, where the CSI error can be specified by an uncertainty set. This model is applicable when the CSI error is dominated by quantization errors. In this case, we adopt a worst-case design approach. For this model, we propose a robust precoder design that minimizes total relay transmit power under constraints on MSEs at the destination nodes. We show that the proposed robust design problems can be reformulated as convex optimization problems that can be solved efficiently using interior-point methods. We demonstrate the robust performance of the proposed design through simulations. © 2011 IEEE.

  16. Using a micromachined magnetostatic relay in commutating a DC motor

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Wright, John A. (Inventor); Lilienthal, Gerald (Inventor)

    2004-01-01

    A DC motor is commutated by rotating a magnetic rotor to induce a magnetic field in at least one magnetostatic relay in the motor. Each relay is activated in response to the magnetic field to deliver power to at least one corresponding winding connected to the relay. In some cases, each relay delivers power first through a corresponding primary winding and then through a corresponding secondary winding to a common node. Specific examples include a four-pole, three-phase motor in which each relay is activated four times during one rotation of the magnetic rotor.

  17. Relay Architectures for 3GPP LTE-Advanced

    Directory of Open Access Journals (Sweden)

    Peters StevenW

    2009-01-01

    Full Text Available The Third Generation Partnership Project's Long Term Evolution-Advanced is considering relaying for cost-effective throughput enhancement and coverage extension. While analog repeaters have been used to enhance coverage in commercial cellular networks, the use of more sophisticated fixed relays is relatively new. The main challenge faced by relay deployments in cellular systems is overcoming the extra interference added by the presence of relays. Most prior work on relaying does not consider interference, however. This paper analyzes the performance of several emerging half-duplex relay strategies in interference-limited cellular systems: one-way, two-way, and shared relays. The performance of each strategy as a function of location, sectoring, and frequency reuse are compared with localized base station coordination. One-way relaying is shown to provide modest gains over single-hop cellular networks in some regimes. Shared relaying is shown to approach the gains of local base station coordination at reduced complexity, while two-way relaying further reduces complexity but only works well when the relay is close to the handset. Frequency reuse of one, where each sector uses the same spectrum, is shown to have the highest network throughput. Simulations with realistic channel models provide performance comparisons that reveal the importance of interference mitigation in multihop cellular networks.

  18. Opportunistic Fixed Gain Bidirectional Relaying with Outdated CSI

    KAUST Repository

    Khan, Fahd Ahmed

    2015-05-01

    In a network with multiple relays, relay selection has been shown as an effective scheme to achieve diversity as well as to improve the overall throughput. This paper studies the impact of using outdated channel state information for relay selection on the performance of a network where two sources communicate with each other via fixed-gain amplify-and-forward relays. For a Rayleigh faded channel, closed-form expressions for the outage probability, moment generating function and symbol error rate are derived. Simulations results are also presented to corroborate the derived analytical results. It is shown that adding relays does not improve the performance if the channel is substantially outdated. Furthermore, relay location is also taken into consideration and it is shown that the performance can be improved by placing the relay closer to the source whose channel is more outdated. © 2015 IEEE.

  19. Anion-π catalysis.

    Science.gov (United States)

    Zhao, Yingjie; Beuchat, César; Domoto, Yuya; Gajewy, Jadwiga; Wilson, Adam; Mareda, Jiri; Sakai, Naomi; Matile, Stefan

    2014-02-05

    The introduction of new noncovalent interactions to build functional systems is of fundamental importance. We here report experimental and theoretical evidence that anion-π interactions can contribute to catalysis. The Kemp elimination is used as a classical tool to discover conceptually innovative catalysts for reactions with anionic transition states. For anion-π catalysis, a carboxylate base and a solubilizer are covalently attached to the π-acidic surface of naphthalenediimides. On these π-acidic surfaces, transition-state stabilizations up to ΔΔGTS = 31.8 ± 0.4 kJ mol(-1) are found. This value corresponds to a transition-state recognition of KTS = 2.7 ± 0.5 μM and a catalytic proficiency of 3.8 × 10(5) M(-1). Significantly increasing transition-state stabilization with increasing π-acidity of the catalyst, observed for two separate series, demonstrates the existence of "anion-π catalysis." In sharp contrast, increasing π-acidity of the best naphthalenediimide catalysts does not influence the more than 12 000-times weaker substrate recognition (KM = 34.5 ± 1.6 μM). Together with the disappearance of Michaelis-Menten kinetics on the expanded π-surfaces of perylenediimides, this finding supports that contributions from π-π interactions are not very important for anion-π catalysis. The linker between the π-acidic surface and the carboxylate base strongly influences activity. Insufficient length and flexibility cause incompatibility with saturation kinetics. Moreover, preorganizing linkers do not improve catalysis much, suggesting that the ideal positioning of the carboxylate base on the π-acidic surface is achieved by intramolecular anion-π interactions rather than by an optimized structure of the linker. Computational simulations are in excellent agreement with experimental results. They confirm, inter alia, that the stabilization of the anionic transition states (but not the neutral ground states) increases with the π-acidity of the

  20. Finite-SNR analysis for partial relaying cooperation with channel coding and opportunistic relay selection

    Science.gov (United States)

    Vu, Thang X.; Duhamel, Pierre; Chatzinotas, Symeon; Ottersten, Bjorn

    2017-12-01

    This work studies the performance of a cooperative network which consists of two channel-coded sources, multiple relays, and one destination. To achieve high spectral efficiency, we assume that a single time slot is dedicated to relaying. Conventional network-coded-based cooperation (NCC) selects the best relay which uses network coding to serve the two sources simultaneously. The bit error rate (BER) performance of NCC with channel coding, however, is still unknown. In this paper, we firstly study the BER of NCC via a closed-form expression and analytically show that NCC only achieves diversity of order two regardless of the number of available relays and the channel code. Secondly, we propose a novel partial relaying-based cooperation (PARC) scheme to improve the system diversity in the finite signal-to-noise ratio (SNR) regime. In particular, closed-form expressions for the system BER and diversity order of PARC are derived as a function of the operating SNR value and the minimum distance of the channel code. We analytically show that the proposed PARC achieves full (instantaneous) diversity order in the finite SNR regime, given that an appropriate channel code is used. Finally, numerical results verify our analysis and demonstrate a large SNR gain of PARC over NCC in the SNR region of interest.

  1. Adjustable electronic load-alarm relay

    International Nuclear Information System (INIS)

    Mason, C.H.; Sitton, R.S.

    1976-01-01

    An improved electronic alarm relay for monitoring the current drawn by an ac motor or other electrical load is described. The circuit is designed to measure the load with high accuracy and to have excellent alarm repeatability. Chattering and arcing of the relay contacts are minimal. The operator can adjust the set point easily and can re-set both the high and the low alarm points by means of one simple adjustment. The relay includes means for generating a signal voltage proportional to the motor current. In a preferred form of the invention a first operational amplifier is provided to generate a first constant reference voltage which is higher than a preselected value of the signal voltage. A second operational amplifier is provided to generate a second constant reference voltage which is lower than the aforementioned preselected value of the signal voltage. A circuit comprising a first resistor serially connected to a second resistor is connected across the outputs of the first and second amplifiers, and the junction of the two resistors is connected to the inverting terminal of the second amplifier. Means are provided to compare the aforementioned signal voltage with both the first and second reference voltages and to actuate an alarm if the signal voltage is higher than the first reference voltage or lower than the second reference voltage

  2. Relaying Strategies and Protocols for Efficient Wireless Networks

    KAUST Repository

    Zafar, Ammar

    2014-10-01

    Next generation wireless networks are expected to provide high data rate and satisfy the Quality-of-Service (QoS) constraints of the users. A significant component of achieving these goals is to increase the effi ciency of wireless networks by either optimizing current architectures or exploring new technologies which achieve that. The latter includes revisiting technologies which were previously proposed, but due to a multitude of reasons were ignored at that time. One such technology is relaying which was initially proposed in the latter half of the 1960s and then was revived in the early 2000s. In this dissertation, we study relaying in conjunction with resource allocation to increase the effi ciency of wireless networks. In this regard, we differentiate between conventional relaying and relaying with buffers. Conventional relaying is traditional relaying where the relay forwards the signal it received immediately. On the other hand, in relaying with buffers or buffer-aided relaying as it is called, the relay can store received data in its buffer and forward it later on. This gives the benefit of taking advantage of good channel conditions as the relay can only transmit when the channel conditions are good. The dissertation starts with conventional relaying and considers the problem of minimizing the total consumed power while maintaining system QoS. After upper bounding the system performance, more practical algorithms which require reduced feedback overhead are explored. Buffer-aided relaying is then considered and the joint user-and-hop scheduler is introduced which exploits multi-user diversity (MUD) and 5 multi-hop diversity (MHD) gains together in dual-hop broadcast channels. Next joint user-and-hop scheduling is extended to the shared relay channel where two source-destination pairs share a single relay. The benefits of buffer-aided relaying in the bidirectional relay channel utilizing network coding are then explored. Finally, a new transmission protocol

  3. A Reliability Assessment Method for High Speed Train Electromagnetic Relays

    Directory of Open Access Journals (Sweden)

    Jianqiang Liu

    2018-03-01

    Full Text Available The condition of electromagnetic relays is crucial to the safe and normal operation of the high-speed train (HST. At present, there are no proper testing and assessment methods for the condition of electromagnetic relays. Electromagnetic relays experience aging and failure over their service time, which causes many potential security problems. To solve these problems, the failure mechanisms of electromagnetic relays are analyzed. The Fick diffusion theory and the Larson–Miller method are used to deduce the degradation models for contact resistance and closing time. Based on these models, an approach to calculate relay life is proposed. To verify the effectiveness of the proposed method, a test platform was designed and built. The accelerated life test was carried out by using Siemens 3TH electromagnetic relays (3TH4244-OLF4, Siemens, Suzhou, China. Contact resistance and closing time were measured using a test platform. The least squares fitting was used to calculate the residual sum of squares and the unknown parameters in the degradation models with the test data. The optimal degradation model was chosen according to the fitting results. Relay life at four temperature stress levels was predicted by the optimal degradation model and failure threshold of the relays. The result indicates that the life of the electromagnetic relays at ambient temperature is 11,874 days and prediction error is about 5%, which provides important guidance for the maintenance of electromagnetic relays.

  4. An assessment of fire vulnerability for aged electrical relays

    International Nuclear Information System (INIS)

    Vigil, R.A.; Nowlen, S.P.

    1995-03-01

    There has been some concern that, as nuclear power plants age, protective measures taken to control and minimize the impact of fire may become ineffective, or significantly less effective, and hence result in an increased fire risk. One objective of the Fire Vulnerability of Aged Electrical Components Program is to assess the effects of aging and service wear on the fire vulnerability of electrical equipment. An increased fire vulnerability of components may lead to an overall increase in fire risk to the plant. Because of their widespread use in various electrical safety systems, electromechanical relays were chosen to be the initial components for evaluation. This test program assessed the impact of operational and thermal aging on the vulnerability of these relays to fire-induced damage. Only thermal effects of a fire were examined in this test program. The impact of smoke, corrosive materials, or fire suppression effects on relay performance were not addressed in this test program. The purpose of this test program was to assess whether the fire vulnerability of electrical relays increased with aging. The sequence followed for the test program was to: identify specific relay types, develop three fire scenarios, artificially age several relays, test the unaged and aged relays in the fire exposure scenarios, and compare the results. The relays tested were Agastat GPI, General Electric (GE) HMA, HGA, and HFA. At least two relays of each type were artificially aged and at least two relays of each type were new. Relays were operationally aged by cycling the relay under rated load for 2,000 operations. These relays were then thermally aged for 60 days with their coil energized

  5. Potentiometric anion selective sensors

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Reinhoudt, David

    1999-01-01

    In comparison with selective receptors (and sensors) for cationic species, work on the selective complexation and detection of anions is of more recent date. There are three important components for a sensor, a transducer element, a membrane material that separates the transducer element and the

  6. Anionic polymerization and polyhomologation: An ideal combination to synthesize polyethylene-based block copolymers

    KAUST Repository

    Zhang, H.

    2013-08-07

    A novel one-pot methodology combining anionic polymerization and polyhomologation, through a "bridge" molecule (BF3OEt 2), was developed for the synthesis of polyethylene (PE)-based block copolymers. The anionically synthesized macroanion reacts with the "bridge" molecule to afford a 3-arm star (trimacromolecular borane) which serves as an initiator for the polyhomologation. 2013 The Royal Society of Chemistry.

  7. A performance analysis in AF full duplex relay selection network

    Science.gov (United States)

    Ngoc, Long Nguyen; Hong, Nhu Nguyen; Loan, Nguyen Thi Phuong; Kieu, Tam Nguyen; Voznak, Miroslav; Zdralek, Jaroslav

    2018-04-01

    This paper studies on the relaying selective matter in amplify-and-forward (AF) cooperation communication with full-duplex (FD) activity. Various relay choice models supposing the present of different instant information are investigated. We examine a maximal relaying choice that optimizes the instant FD channel capacity and asks for global channel state information (CSI) as well as partial CSI learning. To make comparison easy, accurate outage probability clauses and asymptote form of these strategies that give a diversity rank are extracted. From that, we can see clearly that the number of relays, noise factor, the transmittance coefficient as well as the information transfer power had impacted on their performance. Besides, the optimal relay selection (ORS) model can promote than that of the partial relay selection (PRS) model.

  8. Generalized instantly decodable network coding for relay-assisted networks

    KAUST Repository

    Elmahdy, Adel M.

    2013-09-01

    In this paper, we investigate the problem of minimizing the frame completion delay for Instantly Decodable Network Coding (IDNC) in relay-assisted wireless multicast networks. We first propose a packet recovery algorithm in the single relay topology which employs generalized IDNC instead of strict IDNC previously proposed in the literature for the same relay-assisted topology. This use of generalized IDNC is supported by showing that it is a super-set of the strict IDNC scheme, and thus can generate coding combinations that are at least as efficient as strict IDNC in reducing the average completion delay. We then extend our study to the multiple relay topology and propose a joint generalized IDNC and relay selection algorithm. This proposed algorithm benefits from the reception diversity of the multiple relays to further reduce the average completion delay in the network. Simulation results show that our proposed solutions achieve much better performance compared to previous solutions in the literature. © 2013 IEEE.

  9. Anion complexation by calix[4]arene–TTF conjugates

    Czech Academy of Sciences Publication Activity Database

    Flídrová, K.; Tkadlecová, M.; Lang, Kamil; Lhoták, P.

    2012-01-01

    Roč. 92, č. 1 (2012), s. 668-673 ISSN 0143-7208 R&D Projects: GA ČR GA203/09/0691 Institutional research plan: CEZ:AV0Z40320502 Keywords : calix[4]arene * tetrathiafulvalene * anion recognition * receptor * NMR titration * UV/vis spectroscopy Subject RIV: CA - Inorganic Chemistry Impact factor: 3.532, year: 2012

  10. Novel Biscalix[4]arene-based Anion Receptors

    Czech Academy of Sciences Publication Activity Database

    Šťastný, V.; Lhoták, P.; Michlová, V.; Stibor, I.; Sýkora, Jan

    2002-01-01

    Roč. 58, č. 36 (2002), s. 7207-7211 ISSN 0040-4020 R&D Projects: GA ČR GA104/00/1722; GA ČR GA203/00/1011 Keywords : calixarenes * anion receptors * NMR titration Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.420, year: 2002

  11. Amplify-and-forward relaying in wireless communications

    CERN Document Server

    Rodriguez, Leonardo Jimenez; Le-Ngoc, Tho

    2015-01-01

    This SpringerBrief explores the advantage of relaying techniques in addressing the increasing demand for high data rates and reliable services over the air. It demonstrates how to design cost-effective relay systems that provide high spectral efficiency and fully exploit the diversity of the relay channel. The brief covers advances in achievable rates, power allocation schemes, and error performance for half-duplex (HD) and full-duplex (FD) amplify-and-forward (AF) single-relay systems. The authors discuss the capacity and respective optimal power allocation for a wide range of HD protocols ov

  12. Relay Telecommunications for the Coming Decade of Mars Exploration

    Science.gov (United States)

    Edwards, C.; DePaula, R.

    2010-01-01

    Over the past decade, an evolving network of relay-equipped orbiters has advanced our capabilities for Mars exploration. NASA's Mars Global Surveyor, 2001 Mars Odyssey, and Mars Reconnaissance Orbiter (MRO), as well as ESA's Mars Express Orbiter, have provided telecommunications relay services to the 2003 Mars Exploration Rovers, Spirit and Opportunity, and to the 2007 Phoenix Lander. Based on these successes, a roadmap for continued Mars relay services is in place for the coming decade. MRO and Odyssey will provide key relay support to the 2011 Mars Science Laboratory (MSL) mission, including capture of critical event telemetry during entry, descent, and landing, as well as support for command and telemetry during surface operations, utilizing new capabilities of the Electra relay payload on MRO and the Electra-Lite payload on MSL to allow significant increase in data return relative to earlier missions. Over the remainder of the decade a number of additional orbiter and lander missions are planned, representing new orbital relay service providers and new landed relay users. In this paper we will outline this Mars relay roadmap, quantifying relay performance over time, illustrating planned support scenarios, and identifying key challenges and technology infusion opportunities.

  13. Full-Duplex Relay Selection in Cognitive Underlay Networks

    KAUST Repository

    Khafagy, Mohammad Galal

    2017-09-30

    In this work, we analyze the performance of full-duplex relay selection (FDRS) in spectrum-sharing networks. Contrary to half-duplex relaying, full-duplex relaying (FDR) enables simultaneous listening/forwarding at the secondary relay(s), thereby allowing for a higher spectral efficiency. However, since the source and relay simultaneously transmit in FDR, their superimposed signal at the primary receiver should now satisfy the existing interference constraint, which can considerably limit the secondary network throughput. In this regard, relay selection can offer an adequate solution to boost the secondary throughput while satisfying the imposed interference limit. We first analyze the performance of opportunistic FDRS with residual self-interference (RSI) by deriving the exact cumulative distribution function of its end-to-end signal-to-interference-plus-noise ratio under Nakagami-m fading. We also evaluate the offered diversity gain of relay selection for different full-duplex cooperation schemes in the presence/absence of a direct source-destination link. When the adopted RSI link gain model is sublinear in the relay power, which agrees with recent research findings, we show that remarkable diversity gain can be recovered even in the presence of an interfering direct link. Second, we evaluate the end-to-end performance of FDRS with interference constraints due to the presence of a primary receiver. Finally, the presented exact theoretical findings are verified by numerical simulations.

  14. Cooperative relay-based multicasting for energy and delay minimization

    KAUST Repository

    Atat, Rachad

    2012-08-01

    Relay-based multicasting for the purpose of cooperative content distribution is studied. Optimized relay selection is performed with the objective of minimizing the energy consumption or the content distribution delay within a cluster of cooperating mobiles. Two schemes are investigated. The first consists of the BS sending the data only to the relay, and the second scheme considers the scenario of threshold-based multicasting by the BS, where a relay is selected to transmit the data to the mobiles that were not able to receive the multicast data. Both schemes show significant superiority compared to the non-cooperative scenarios, in terms of energy consumption and delay reduction. © 2012 IEEE.

  15. Power supply devices and systems of relay protection

    CERN Document Server

    Gurevich, Vladimir

    2013-01-01

    Power Supply Devices and Systems of Relay Protection brings relay protection and electrical power engineers a single, concentrated source of information on auxiliary power supply systems and devices. The book also tackles specific problems and solutions of relay protection power supply systems and devices, which are often not dealt with in the literature. The author, an experienced engineer with more than 100 patents, draws on his own experience to offer practical, tested advice to readers. A Guide to Relay Protection Power Supply for Engineers and Technicians The first chapter reviews the ele

  16. Modified Dynamic Decode-and-Forward Relaying Protocol for Type II Relay in LTE-Advanced and Beyond.

    Science.gov (United States)

    Nam, Sung Sik; Alouini, Mohamed-Slim; Choi, Seyeong

    2016-01-01

    In this paper, we propose a modified dynamic decode-and-forward (MoDDF) relaying protocol to meet the critical requirements for user equipment (UE) relays in next-generation cellular systems (e.g., LTE-Advanced and beyond). The proposed MoDDF realizes the fast jump-in relaying and the sequential decoding with an application of random codeset to encoding and re-encoding process at the source and the multiple UE relays, respectively. A subframe-by-subframe decoding based on the accumulated (or buffered) messages is employed to achieve energy, information, or mixed combining. Finally, possible early termination of decoding at the end user can lead to the higher spectral efficiency and more energy saving by reducing the frequency of redundant subframe transmission and decoding. These attractive features eliminate the need of directly exchanging control messages between multiple UE relays and the end user, which is an important prerequisite for the practical UE relay deployment.

  17. Performance analysis of two-way amplify and forward relaying with adaptive modulation over multiple relay network

    KAUST Repository

    Hwang, Kyusung

    2011-02-01

    In this letter, we propose two-way amplify-and-forward relaying in conjunction with adaptive modulation in order to improve spectral efficiency of relayed communication systems while monitoring the required error performance. We also consider a multiple relay network where only the best relay node is utilized so that the diversity order increases while maintaining a low complexity of implementation as the number of relays increases. Based on the best relay selection criterion, we offer an upper bound on the signal-to-noise ratio to keep the performance analysis tractable. Our numerical examples show that the proposed system offers a considerable gain in spectral efficiency while satisfying the error rate requirements. © 2011 IEEE.

  18. Laser Communications Relay Demonstration: Introduction for Experimenters

    Science.gov (United States)

    Israel, David J.

    2017-01-01

    This document provides guidance to individuals or groups considering proposing an experiment for the Laser Communications Relay Demonstration (LCRD) Experiment Program. For the purposes of this document, the term experiment refers to both experiments and demonstrations. The documents goals are: (1) to introduce potential experimenters to the LCRD mission, its purpose, and its system architecture; (2) to help them understand the types of experiments that are possible using LCRD; and (3) to provide an overview of the experiment proposal process and explain how and where to obtain further information about making a proposal.

  19. Relay testing at Brookhaven National Laboratory

    International Nuclear Information System (INIS)

    Bandyopadhyay, K.; Hofmayer, C.

    1989-01-01

    Brookhaven National Laboratory (BNL) is conducting a seismic test program on relays. The purpose of the test program is to investigate the influence of various designs, electrical and vibration parameters on the seismic capacity levels. The first series of testing has been completed and performed at Wyle Laboratories. The major part of the test program consisted of single axis, single frequency sine dwell tests. Random multiaxis, multifrequency tests were also performed. Highlights of the test results as well as a description of the testing methods are presented in this paper. 10 figs

  20. Uplink Capacity of 802.16j Mobile Multihop Relay Networks with Transparent Relays

    DEFF Research Database (Denmark)

    Wang, Hua; Andrews, Jeffrey G.; Iversen, Villy Bæk

    2009-01-01

    -to-end spectral efficiency. Furthermore, the position and the number of relay stations (RSs) have a great impact on the capacity gain. These results are further verified in the evaluation of the system Erlang capacity. The study demonstrates that with proper deployment of RSs and use of MIMO transmission...

  1. 78 FR 40407 - Structure and Practices of the Video Relay Service Program: Telecommunications Relay Services and...

    Science.gov (United States)

    2013-07-05

    ... locations. Several VRS providers also provide VRI. How do such providers allocate costs that may be shared...); (5) eligibility, registration, and verification; and (6) porting and slamming. In addition, comments... for application to IP Relay and IP CTS providers, and the rules on prevention of slamming appear to be...

  2. Structures and properties of anionic clay minerals

    International Nuclear Information System (INIS)

    Koch, Chr. Bender

    1998-01-01

    The Moessbauer spectra of pyroaurite-sjoegrenite-type compounds (PTC) (layered anion exchangers) are discussed with reference to the crystal structure, cation order, and crystallite morphology. It is shown that cation-ordered layers are produced in the synthesis of carbonate and sulphate types of green rust. In contrast, synthetic and natural pyroaurite only occurs as disordered types. The redox chemistry of Fe(III) within the metal hydroxide layer is illustrated with examples of electrochemical oxidation and reversible reduction by boiling glycerol. The chemistry of iron in the interlayer is exemplified by the intercalation of Fe-cyanide complexes in hydrotalcite. This reaction may be used as a probe for the charge distribution in the interlayer

  3. Satellite-Relayed Intercontinental Quantum Network

    Science.gov (United States)

    Liao, Sheng-Kai; Cai, Wen-Qi; Handsteiner, Johannes; Liu, Bo; Yin, Juan; Zhang, Liang; Rauch, Dominik; Fink, Matthias; Ren, Ji-Gang; Liu, Wei-Yue; Li, Yang; Shen, Qi; Cao, Yuan; Li, Feng-Zhi; Wang, Jian-Feng; Huang, Yong-Mei; Deng, Lei; Xi, Tao; Ma, Lu; Hu, Tai; Li, Li; Liu, Nai-Le; Koidl, Franz; Wang, Peiyuan; Chen, Yu-Ao; Wang, Xiang-Bin; Steindorfer, Michael; Kirchner, Georg; Lu, Chao-Yang; Shu, Rong; Ursin, Rupert; Scheidl, Thomas; Peng, Cheng-Zhi; Wang, Jian-Yu; Zeilinger, Anton; Pan, Jian-Wei

    2018-01-01

    We perform decoy-state quantum key distribution between a low-Earth-orbit satellite and multiple ground stations located in Xinglong, Nanshan, and Graz, which establish satellite-to-ground secure keys with ˜kHz rate per passage of the satellite Micius over a ground station. The satellite thus establishes a secure key between itself and, say, Xinglong, and another key between itself and, say, Graz. Then, upon request from the ground command, Micius acts as a trusted relay. It performs bitwise exclusive or operations between the two keys and relays the result to one of the ground stations. That way, a secret key is created between China and Europe at locations separated by 7600 km on Earth. These keys are then used for intercontinental quantum-secured communication. This was, on the one hand, the transmission of images in a one-time pad configuration from China to Austria as well as from Austria to China. Also, a video conference was performed between the Austrian Academy of Sciences and the Chinese Academy of Sciences, which also included a 280 km optical ground connection between Xinglong and Beijing. Our work clearly confirms the Micius satellite as a robust platform for quantum key distribution with different ground stations on Earth, and points towards an efficient solution for an ultralong-distance global quantum network.

  4. Satellite-Relayed Intercontinental Quantum Network.

    Science.gov (United States)

    Liao, Sheng-Kai; Cai, Wen-Qi; Handsteiner, Johannes; Liu, Bo; Yin, Juan; Zhang, Liang; Rauch, Dominik; Fink, Matthias; Ren, Ji-Gang; Liu, Wei-Yue; Li, Yang; Shen, Qi; Cao, Yuan; Li, Feng-Zhi; Wang, Jian-Feng; Huang, Yong-Mei; Deng, Lei; Xi, Tao; Ma, Lu; Hu, Tai; Li, Li; Liu, Nai-Le; Koidl, Franz; Wang, Peiyuan; Chen, Yu-Ao; Wang, Xiang-Bin; Steindorfer, Michael; Kirchner, Georg; Lu, Chao-Yang; Shu, Rong; Ursin, Rupert; Scheidl, Thomas; Peng, Cheng-Zhi; Wang, Jian-Yu; Zeilinger, Anton; Pan, Jian-Wei

    2018-01-19

    We perform decoy-state quantum key distribution between a low-Earth-orbit satellite and multiple ground stations located in Xinglong, Nanshan, and Graz, which establish satellite-to-ground secure keys with ∼kHz rate per passage of the satellite Micius over a ground station. The satellite thus establishes a secure key between itself and, say, Xinglong, and another key between itself and, say, Graz. Then, upon request from the ground command, Micius acts as a trusted relay. It performs bitwise exclusive or operations between the two keys and relays the result to one of the ground stations. That way, a secret key is created between China and Europe at locations separated by 7600 km on Earth. These keys are then used for intercontinental quantum-secured communication. This was, on the one hand, the transmission of images in a one-time pad configuration from China to Austria as well as from Austria to China. Also, a video conference was performed between the Austrian Academy of Sciences and the Chinese Academy of Sciences, which also included a 280 km optical ground connection between Xinglong and Beijing. Our work clearly confirms the Micius satellite as a robust platform for quantum key distribution with different ground stations on Earth, and points towards an efficient solution for an ultralong-distance global quantum network.

  5. CERN Relay Race: sporty and colourful

    CERN Multimedia

    Andy Butterworth, CERN Running Club

    2013-01-01

    On Thursday 23 May, the 43rd CERN Relay Race took place, with 108 teams on the starting line, the largest participation ever!       The DG was present at the start and said a few words to encourage the runners. At 12:15, the Solar Club and handbike racers, led by Jean-Yves Le Meur, were the first to set off. And as last year, the relay runners were accompanied by an enthusiastic group of Nordic walkers. The first team across the finish line was "Velo City", in a very fast time of 10'31". New this year was a prize category for the best fancy dress, which was won by Les Schtroumpfs from the BE Department. The challenge for the best represented department was won for the third year in a row by FP, but second and third were HR and IT, up from 6th and 9th places last year. To see all the pictures of the event, click here.

  6. Record Participation in the Relay Race!

    CERN Multimedia

    2002-01-01

    CERN has a more sporting spirit than ever before. This is not the result of any survey, but the impression you got as soon as you saw the 62 teams of six runners each speeding around the laboratory in the 32nd annual relay race. This year 11 more teams competed than in 2001.   First changeover: Hervé Cornet takes over from Camille Ruiz Llamas for The Shabbys, and Sebastian Dorthe from Daniel Matteazzi for Charmilles Technologies. Jérôme Bendotti (EP/TA1) just holding off the team from the WHO at the finish. A total of 372 people ran together last Wednesday in this year's relay race, making for a record participation. It also seems that women are becoming more and more attracted by this competition, since this year there were eight ladies teams, also a new record. The first team were The Shabbys in a time of 10 minutes 45 seconds, finishing almost before the second team had started its last 300 metre leg. The 6 runners in each team cover distances of 1000, 800, 800,...

  7. Spurious Hyperchloremia and Negative Anion Gap in a Child with Refractory Epilepsy.

    Science.gov (United States)

    Chegondi, Madhuradhar; Totapally, Balagangadhar R

    2016-01-01

    We report a case with spurious hyperchloremia with negative anion gap in a child who was taking potassium bromide for refractory epilepsy. Blood chemistry showed a high chloride level (171 mEq/L) and a negative anion gap (-52 mEq/L). Plasma chloride concentration is measured by an ion-selective electrode method; however the presence of other anions like bromide and iodides can interfere with chloride level and largely overestimates the chloride concentration. Thus hyperchloremia with a negative anion gap is a clue to the diagnosis of halides like bromide and iodide ingestion.

  8. 77 FR 42187 - Relay Services for Deaf-Blind Individuals

    Science.gov (United States)

    2012-07-18

    ... COMMISSION 47 CFR Part 64 Relay Services for Deaf-Blind Individuals AGENCY: Federal Communications Commission... Communications and Video Accessibility Act of 2010, Section 105, Relay Services for Deaf-Blind Individuals, Order... Services for Deaf-Blind Individuals, CG Docket No. 10-210. Form Number: N/A. Type of Review: Revision of a...

  9. Effects of Unified Power Flow Controller (UPFC) on Distance Relay ...

    African Journals Online (AJOL)

    This paper investigates the effects of UPFC on Distance Relay tripping characteristics in Nigerian 330kV (North-Central) Network. Its operation is based on impedance measurement at the relaying point. However, the system performance is often impeded by certain operational or structural factors such as load angle, the ...

  10. Efficient Resource Scheduling by Exploiting Relay Cache for Cellular Networks

    Directory of Open Access Journals (Sweden)

    Chun He

    2015-01-01

    Full Text Available In relay-enhanced cellular systems, throughput of User Equipment (UE is constrained by the bottleneck of the two-hop link, backhaul link (or the first hop link, and access link (the second hop link. To maximize the throughput, resource allocation should be coordinated between these two hops. A common resource scheduling algorithm, Adaptive Distributed Proportional Fair, only ensures that the throughput of the first hop is greater than or equal to that of the second hop. But it cannot guarantee a good balance of the throughput and fairness between the two hops. In this paper, we propose a Two-Hop Balanced Distributed Scheduling (TBS algorithm by exploiting relay cache for non-real-time data traffic. The evolved Node Basestation (eNB adaptively adjusts the number of Resource Blocks (RBs allocated to the backhaul link and direct links based on the cache information of relays. Each relay allocates RBs for relay UEs based on the size of the relay UE’s Transport Block. We also design a relay UE’s ACK feedback mechanism to update the data at relay cache. Simulation results show that the proposed TBS can effectively improve resource utilization and achieve a good trade-off between system throughput and fairness by balancing the throughput of backhaul and access link.

  11. Spectral efficiency enhancement with interference cancellation for wireless relay network

    DEFF Research Database (Denmark)

    Yomo, Hiroyuki; De Carvalho, Elisabeth

    The introduction of relaying into wireless communication system for coverage enhancement can cause severe decrease of spectral efficiency due to the requirement on extra radio resource. In this paper, we propose a method to increase spectral efficiency in such a wireless relay network by employin...

  12. A Game-Theoretical Model of Cognitive Relay

    OpenAIRE

    Wang, Chih-Yu; Hsu, Wei-Che; Wei, Hung-Yu

    2009-01-01

    Cognitive Radio provides enhanced wireless communication performance through context-aware sensing and adaptation. Cooperative relay enhances network connection quality and improved system throughput. Applying cooperative relay communication technique on Cognitive Radio networks enables Cognitive Radio to opportunistically exploit cooperation between network nodes. This integrated design that benefits from both cognitive network operation and cooperative communications. One of the key challen...

  13. Sum-Rate Maximization of Coordinated Direct and Relay Systems

    DEFF Research Database (Denmark)

    Sun, Fan; Popovski, Petar; Thai, Chan

    2012-01-01

    Joint processing of multiple communication flows in wireless systems has given rise to a number of novel transmission techniques, notably the two-way relaying based on wireless network coding. Recently, a related set of techniques has emerged, termed coordinated direct and relay (CDR) transmissio...

  14. Beamforming Design for Coordinated Direct and Relay Systems

    DEFF Research Database (Denmark)

    Sun, Fan; De Carvalho, Elisabeth; Thai, Chan

    2012-01-01

    Joint processing of multiple communication flows in wireless systems has given rise to a number of novel transmission techniques, notably the two-way relaying based on wireless network coding. Recently, a related set of techniques has emerged, termed coordinated direct and relay (CDR) transmissions...

  15. Relay studies - existing data, current testing and cabinet amplification

    International Nuclear Information System (INIS)

    Bandyopadhyay, K.; Hofmayer, C.; Kassir, M.; Pepper, S.

    1989-01-01

    The seismic fragility of most electrical equipment is governed by the malfunction of relays. This paper discusses the combined study being performed at BNL by evaluating existing fragility test data, conducting a new relay test program and estimating the cabinet amplification at relay locations. Existing test data for relays have been collected and evaluated at BNL. The data base consists of results from a wide variety of test programs - single frequency, single axis, multifrequency, multiaxis tests. For most relays, the non-operating condition controls the chatter fragility limit. In order to characterize the effect of various parameters on the relay seismic capacity, a test program has been initiated at BNL. Selected test specimens will be tested to determine the influence of frequency of vibration, direction of motion, adjustments of relay parts, among others, on the relay capacities. The amplification study involves computing dynamic amplification factors at various device locations in motor control center and switchgear cabinets. Fragility and high level qualification data have been used for this purpose. This paper includes a summary of the amplification results. 4 refs., 6 figs., 1 tab

  16. Protective Relay Studies for the Nigerian National Electric 330 KV ...

    African Journals Online (AJOL)

    An indepth study and analysis has been performed on the 330KV transmission protective relay schemes of the National Electric Power Authority. Some of the basic considerations taken into account in the study to optimize the settings on the existing protective relay schemes are presented. Typical calculations are ...

  17. Using the 5 P Relay in Task Groups

    Science.gov (United States)

    Stanley, Paula Helen

    2006-01-01

    This article describes the 5 P Relay, a group exercise that can increase the effectiveness of task groups. The 5 P Relay is based on the principles and concepts of the Invitational Model, which emphasizes the importance of assessing the effectiveness or health of five aspects of an organization's environment: people, places, programs, processes,…

  18. Improper signaling in two-path relay channels

    KAUST Repository

    Gaafar, Mohamed

    2017-07-03

    Inter-relay interference (IRI) challenges the operation of two-path relaying systems. Furthermore, the unavailability of the channel state information (CSI) at the source and the limited detection capabilities at the relays prevent neither eliminating the interference nor adopting joint detection at the relays nodes. Improper signaling is a powerful signaling scheme that has the capability to reduce the interference impact at the receiver side and improves the achievable rate performance. Therefore, improper signaling is adopted at both relays, which have access to the global CSI. Then, improper signal characteristics are designed to maximize the total end-to-end achievable rate at the relays. To this end, both the power and the circularity coefficient, a measure of the impropriety degree of the signal, are optimized at the relays. Although the optimization problem is not convex, optimal power allocation for both relays for a fixed circularity coefficient is obtained. Moreover, the circularity coefficient is tuned to maximize the rate for a given power allocation. Finally, a joint solution of the optimization problem is proposed using a coordinate descent method based on alternate optimization. The simulation results show that employing improper signaling improves the achievable rate at medium and high IRI.

  19. relay coordination in the protection of radially-connected power

    African Journals Online (AJOL)

    Abstract. Protective relays detect intolerable or unwanted conditions within an assigned area, and then trip or open one or more circuit breakers to isolate the problem area before it can damage or otherwise interfere with the effective operation of the rest of the power system. It often happens that a substation feeder relay ...

  20. MaROS Strategic Relay Planning and Coordination Interfaces

    Science.gov (United States)

    Allard, Daniel A.

    2010-01-01

    The Mars Relay Operations Service (MaROS) is designed to provide planning and analysis tools in support of ongoing Mars Network relay operations. Strategic relay planning requires coordination between lander and orbiter mission ground data system (GDS) teams to schedule and execute relay communications passes. MaROS centralizes this process, correlating all data relevant to relay coordination to provide a cohesive picture of the relay state. Service users interact with the system through thin-layer command line and web user interface client applications. Users provide and utilize data such as lander view periods of orbiters, Deep Space Network (DSN) antenna tracks, and reports of relay pass performance. Users upload and download relevant relay data via formally defined and documented file structures including some described in Extensible Markup Language (XML). Clients interface with the system via an http-based Representational State Transfer (ReST) pattern using Javascript Object Notation (JSON) formats. This paper will provide a general overview of the service architecture and detail the software interfaces and considerations for interface design.

  1. Relay Coordination in the Protection of Radially-Connected Power ...

    African Journals Online (AJOL)

    Protective relays detect intolerable or unwanted conditions within an assigned area, and then trip or open one or more circuit breakers to isolate the problem area before it can damage or otherwise interfere with the eective operation of the rest of the power system. It often happens that a substation feeder relay and ...

  2. Opportunistic Cognitive Relaying: A Win-Win Spectrum Sharing Scheme

    Directory of Open Access Journals (Sweden)

    Luo Haiyan

    2010-01-01

    Full Text Available A cost-effective spectrum sharing architecture is proposed to enable the legacy noncognitive secondary system to coexist with the primary system. Specifically, we suggest to install a few intermediate nodes, namely, the cognitive relays, to conduct the spectrum sensing and coordinate the spectrum access. To achieve the goal of win-win between primary and secondary systems, the cognitive relay may act as a cooperator for both of them, and an Opportunistic Cognitive Relaying (OCR scheme is specially devised. In this scheme, the cognitive relay opportunistically switches among three different working modes, that is, Relay for Primary Link (RPL, Relay for Secondary Link (RSL, or Relay for Neither of the Links (RNL, respectively, based on the channel-dependent observation of both systems. In addition, the transmit power for cognitive relay and secondary transmitter in each mode are optimally determined by maximizing the transmission rate of secondary system while keeping or even reducing the outage probability of primary system. Simulation results validate the efficiency of the proposed spectrum sharing scheme.

  3. Whether and Where to Code in the Wireless Relay Channel

    DEFF Research Database (Denmark)

    Shi, Xiaomeng; Médard, Muriel; Roetter, Daniel Enrique Lucani

    2013-01-01

    The throughput benefits of random linear network codes have been studied extensively for wirelined and wireless erasure networks. It is often assumed that all nodes within a network perform coding operations. In energy-constrained systems, however, coding subgraphs should be chosen to control...... the number of coding nodes while maintaining throughput. In this paper, we explore the strategic use of network coding in the wireless packet erasure relay channel according to both throughput and energy metrics. In the relay channel, a single source communicates to a single sink through the aid of a half......-duplex relay. The fluid flow model is used to describe the case where both the source and the relay are coding, and Markov chain models are proposed to describe packet evolution if only the source or only the relay is coding. In addition to transmission energy, we take into account coding and reception...

  4. Effects of relay chatter in seismic probabilistic safety analysis

    International Nuclear Information System (INIS)

    Reed, J.W.; Shiu, K.K.

    1985-01-01

    In the Zion and Indian Point Probabilistic Safety Studies, relay chatter was dismissed as a credible event and hence was not formally included in the analyses. Although little discussion is given in the Zion and Indian Point PSA documentation concerning the basis for this decision, it has been expressed informally that it was assumed that the operators will be able to reset all relays in a timely manner. Currently, it is the opinion of many professionals that this may be an oversimplification. The three basic areas which must be considered in addressing relay chatter include the fragility of the relays per se, the reliability of the operators to reset the relays and finally the systems response aspects. Each of these areas is reviewed and the implications for seismic PSA are discussed. Finally, recommendations for future research are given

  5. Distance relay performance in future converter dominated power systems

    DEFF Research Database (Denmark)

    Sarkar, Moumita; Jia, Jundi; Yang, Guangya

    2017-01-01

    relay is major concern as miscoordination of backup relays in case of cascading faults can lead to severe stress in system, which can develop into blackout. In this paper, response of relays in traditional system is compared with response of relays in low short-circuit-current power systems. Impact...... of converter controls on fault current response of converter-based generations is also investigated. Index Terms—Converter control, distance relays, power system protection, system modelling.......Increasing penetration of converter-based generations in power system has led to new system challenges. Short circuit power response from converter-based generations is different from that of traditional synchronous generators. Power electronic converters can be designed for over-current only up...

  6. Multiple relay selection for delay-limited applications

    KAUST Repository

    Alsharoa, Ahmad M.

    2013-12-01

    A multiple relay selection system model that implements the decode-and-forward mode is investigated. All communication nodes are assumed to be equipped by multiple antennas. Furthermore, lattices space-time coded multiple-input multiple-output half duplex channel is applied. The main goal is to increase the throughput of the system by selecting multiple number of relays. The selection criteria depends on the maximum decoding delay at relays where the system implements a decoding time-out algorithm at each relay. This leads to a significant saving in the overall system power consumptions and attempts to solve the relays synchronization problem. All results are presented using numerical simulations. © 2012 IEEE.

  7. An RSS based location estimation technique for cognitive relay networks

    KAUST Repository

    Qaraqe, Khalid A.

    2010-11-01

    In this paper, a received signal strength (RSS) based location estimation method is proposed for a cooperative wireless relay network where the relay is a cognitive radio. We propose a method for the considered cognitive relay network to determine the location of the source using the direct and the relayed signal at the destination. We derive the Cramer-Rao lower bound (CRLB) expressions separately for x and y coordinates of the location estimate. We analyze the effects of cognitive behaviour of the relay on the performance of the proposed method. We also discuss and quantify the reliability of the location estimate using the proposed technique if the source is not stationary. The overall performance of the proposed method is presented through simulations. ©2010 IEEE.

  8. Derivatives of Dodecahalo-Closo-Dodecaborate Di-Anion

    OpenAIRE

    Avelar, Amy Cindy

    2009-01-01

    ABSTRACT OF THE DISSERTATIONDerivatives of the Dodecahalo-Closo-Dodecaborate Di-AnionbyAmy AvelarDoctor of Philosophy, Graduate Program in ChemistryUniversity of California, Riverside, December 2009Dr. Christopher A. Reed, ChairpersonThe di-anion, dodecahalo-closo-dodecaborate, B12X122-, where the X = Cl or Br, has been determined to be a useful weakly coordinating anion, WCA. Despite the di- negative charge, several elusive and reactive cationic species were stabilized with B12X122- as the c...

  9. Relay protection coordination with generator capability curve, excitation system limiters and power system relay protections settings

    Directory of Open Access Journals (Sweden)

    Buha Danilo

    2016-01-01

    Full Text Available The relay protection settings performed in the largest thermal powerplant (TE "Nikola Tesla B" are reffered and explained in this paper. The first calculation step is related to the coordination of the maximum stator current limiter settings, the overcurrent protection with inverse characteristics settings and the permitted overload of the generator stator B1. In the second calculation step the settings of impedance generator protection are determined, and the methods and criteria according to which the calculations are done are described. Criteria used to provide the protection to fulfill the backup protection role in the event of malfunction of the main protection of the transmission system. are clarified. The calculation of all protection functions (32 functions of generator B1 were performed in the project "Coordination of relay protection blocks B1 and B2 with the system of excitation and power system protections -TENT B".

  10. Anion Rreceptors Based on Intramolecularly Bridged Calix[4]arenes Bearing Ureido Functions.

    Czech Academy of Sciences Publication Activity Database

    Řezanková, M.; Budka, J.; Mikšátko, J.; Eigner, V.; Císařová, I.; Cuřínová, Petra; Lhoták, P.

    2017-01-01

    Roč. 73, č. 6 (2017), s. 742-749 ISSN 0040-4020 Institutional support: RVO:67985858 Keywords : calixarene * reductive coupling * anion recognition Subject RIV: CC - Organic Chemistry OBOR OECD: Organic chemistry Impact factor: 2.651, year: 2016

  11. Characterization of oligosaccharides using ESI-MS in presence of anions

    Czech Academy of Sciences Publication Activity Database

    Čmelík, Richard; Bobálová, Janette

    2008-01-01

    Roč. 102, č. 15 (2008), s965-s966 ISSN 1803-2389. [Meeting on Chemistry and Life /4./. Brno, 09.09.2008-11.09.2008] R&D Projects: GA MŠk 2B06037 Institutional research plan: CEZ:AV0Z40310501 Keywords : oligosaccharide * anionic adduct * mass spectrometry Subject RIV: CB - Analytical Chemistry , Separation

  12. Large Efficient Intelligent Heating Relay Station System

    Science.gov (United States)

    Wu, C. Z.; Wei, X. G.; Wu, M. Q.

    2017-12-01

    The design of large efficient intelligent heating relay station system aims at the improvement of the existing heating system in our country, such as low heating efficiency, waste of energy and serious pollution, and the control still depends on the artificial problem. In this design, we first improve the existing plate heat exchanger. Secondly, the ATM89C51 is used to control the whole system and realize the intelligent control. The detection part is using the PT100 temperature sensor, pressure sensor, turbine flowmeter, heating temperature, detection of user end liquid flow, hydraulic, and real-time feedback, feedback signal to the microcontroller through the heating for users to adjust, realize the whole system more efficient, intelligent and energy-saving.

  13. Digital model of overcurrent relay characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Darwish, H.A.; Rahman, M.A. [Memorial Univ. of Newfoundland, St. John`s, Newfoundland (Canada). Faculty of Engineering and Applied Science; Taalab, A.I.; Shaaban, H. [Menoufiya Univ., Shebin El-Kom (Egypt). Faculty of Engineering

    1995-12-31

    In this paper a novel model of the overcurrent relay standard curves is presented. This model facilitates the implementation of these curves using microprocessors and personal computer. The proposed model uniquely combines both direct data storage and curve fitting techniques. Tabulating one time-current curve corresponding to any time dial setting in addition to a number of coefficients are quite sufficient to get the tripping time values at any other time dial setting. The selection of the most suitable time-current curve and the minimum length of its corresponding table are determined. An alternative form of the model is developed for computer applications, in particular by replacing the table by its equivalent fitted equation. Both forms of the model are adapted to occupy the lowest possible storage memory. The validity of the analytical models is provided by the test results.

  14. Generalized routing protocols for multihop relay networks

    KAUST Repository

    Khan, Fahd Ahmed

    2011-07-01

    Performance of multihop cooperative networks depends on the routing protocols employed. In this paper we propose the last-n-hop selection protocol, the dual path protocol, the forward-backward last-n-hop selection protocol and the forward-backward dual path protocol for the routing of data through multihop relay networks. The average symbol error probability performance of the schemes is analysed by simulations. It is shown that close to optimal performance can be achieved by using the last-n-hop selection protocol and its forward-backward variant. Furthermore we also compute the complexity of the protocols in terms of number of channel state information required and the number of comparisons required for routing the signal through the network. © 2011 IEEE.

  15. CERN Relay Race | 5 June | Get ready!

    CERN Multimedia

    CERN Medical Service

    2014-01-01

    In anticipation of the CERN relay race, the Medical Service would like to remind all participants that preparing for this sporting activity is essential - even though it is a short event.   Progressive and regular training. Adequate nutrition and hydration. Advice and information is available at the infirmary in Building 57. Everyone should adapt their physical activity to match their fitness levels, bearing in mind that the aim of this race is not necessarily to achieve great success but to participate in a collective sporting event. In the framework of the "Move! Eat better" campaign and for the third successive year, a 2.4 km route is open to walkers, both beginners and experts. Before, during and after this event, test yourself with a pedometer, available from the CERN infirmary! 

  16. Relay protection coordination with generator capability curve, excitation system limiters and power system relay protections settings

    OpenAIRE

    Buha Danilo; Buha Boško; Jačić Dušan; Gligorov Saša; Božilov Marko; Marinković Savo; Milosavljević Srđan

    2016-01-01

    The relay protection settings performed in the largest thermal powerplant (TE "Nikola Tesla B") are reffered and explained in this paper. The first calculation step is related to the coordination of the maximum stator current limiter settings, the overcurrent protection with inverse characteristics settings and the permitted overload of the generator stator B1. In the second calculation step the settings of impedance generator protection are determined, and the methods and criteria according ...

  17. OFDMA Cellular Networks with Opportunistic Two-Hop Relays

    Directory of Open Access Journals (Sweden)

    Calcev George

    2009-01-01

    Full Text Available We investigate the benefits of two-hop opportunistic relay in time division duplex (TDD OFDMA cellular network configurations. The paper starts with a short analytical model for the two-hop opportunistic relay. The model expresses the probability of finding a suitable relay node in the presence of lognormal fading and it allows the computation of the expected number of out-of-coverage nodes, as well as the end-to-end spectrum efficiency increase due to opportunistic relaying. The paper then presents results for Monte Carlo simulations of opportunistic relay in some realistic scenarios. Specifically, the simulations consider two scenarios. The first scenario uses the propagation model and a wide-area 19-cell configuration specified in 802.16 OFDMA cellular standard evaluation methodologies. In the second scenario, a Manhattan-like 19-cell topology is used. Our simulations show 11% to 33% in throughput increase when the opportunistic relay technology is used. Our results evaluate the benefits of the opportunistic relay in both scenarios in terms of coverage extension and throughput increase.

  18. Analysis of Relay Selection Game in a Cooperative Communication Scenario

    DEFF Research Database (Denmark)

    Craciunescu, Razvan; Mihovska, Albena; Halunga, Simona

    This paper analysis the performances of a proposed set of functions that model the relay selection process in a cooperative communication scenario. The behavior and influence proposed functions create a mechanism for selecting the best relays to be used to send certain types of data. The mechanism...... is based on a Nash Equilibrium algorithm and on a marriage equation, that predicts the degree of satisfaction between married couples. We consider an opportunistic cooperative communication settings in which multiple nodes are competing for a poll of relay nodes. The performances are evaluated in terms...

  19. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Unknown

    trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange properties together with surface basicity making them materials of importance ...

  20. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Together with hydrotalcite-like layered double hydroxides, bivalent and trivalent metal hydroxides and their hydroxy salts are actually anionic clays consisting of positively charged hydroxide layers with anions intercalated in the interlayer region. The anionic clays exhibit anion sorption, anion diffusion and exchange ...

  1. Synthesis and anion binding properties of porphyrins and related compounds

    KAUST Repository

    Figueira, Flávio

    2016-12-02

    Over the last two decades the preparation of pyrrole-based receptors for anion recognition has attracted considerable attention. In this regard porphyrins, phthalocyanines and expanded porphyrins have been used as strong and selective receptors while the combination of those with different techniques and materials can boost their applicability in different applications as chemosensors and extracting systems. Improvements in the field, including the synthesis of this kind of compounds, can contribute to the development of efficient, cheap, and easy-to-prepare anion receptors. Extensive efforts have been made to improve the affinity and selectivity of these compounds and the continuous expansion of related research makes this chemistry even more promising. In this review, we summarize the most recent developments in anion binding studies while outlining the strategies that may be used to synthesize and functionalize these type of macrocycles. © 2016 World Scientific Publishing Company.

  2. Calix[4]arenes Containing a Ureido Functionality on the Lower Rim as Highly Efficient Receptors for Anion Recognition.

    Czech Academy of Sciences Publication Activity Database

    Klejch, T.; Slavíček, J.; Hudeček, O.; Eigner, V.; Gutierrez, Natalia Andrea; Cuřínová, Petra; Lhoták, P.

    2016-01-01

    Roč. 40, č. 9 (2016), s. 7935-7942 ISSN 1144-0546 Institutional support: RVO:67985858 Keywords : calix[4]arene * anion recognition * receptors Subject RIV: CC - Organic Chemistry Impact factor: 3.269, year: 2016

  3. Overlay cognitive radio systems with adaptive two-way relaying

    KAUST Repository

    Hyadi, Amal

    2013-12-01

    In this paper, we propose a spectrum sharing mechanism with a two-phase two-way relaying protocol for an overlay cognitive network. The system comprises two primary users (PUs) and two secondary users (SUs). One of the SUs acts as a relay for the PUs and gains spectrum sharing as long as he respects outage probability constraints of the primary system. Moreover, we consider that the relaying node performs an optimal power allocation scheme that minimizes the outage performance of the secondary receiver. Closed form expressions for the outage probability are derived for the cases of Decode-and-Forward (DF), Amplify-and-Forward (AF), and adaptive relaying. Numerical simulations are presented to illustrate and compare the obtained results. © 2013 IEEE.

  4. Performance analysis of two-way DF relay selection techniques

    Directory of Open Access Journals (Sweden)

    Samer Alabed

    2016-09-01

    Full Text Available This work proposes novel bi-directional dual-relay selection techniques based on Alamouti space-time block coding (STBC using the decode and forward (DF protocol and analyzes their performance. In the proposed techniques, two- and the three-phase relaying schemes are used to perform bi-directional communication between the communicating terminals via two selected single-antenna relays that employ the Alamouti STBC in a distributed fashion to achieve diversity and orthogonalization of the channels and hence improve the reliability of the system and enable the use of a symbol-wise detector. Furthermore, the network coding strategy applied at all relays is not associated with any power wastage for broadcasting data already known at any terminal, resulting in improved overall performance at the terminals. Our simulations confirm the analytical results and show a substantially improved bit error rate (BER performance of our proposed techniques compared with the current state of the art.

  5. SIMULASI SISTEM KELISTRIKAN KAMAR HOTEL MENGGUNAKAN SMART RELAY

    Directory of Open Access Journals (Sweden)

    I Nyoman Sukarma

    2018-03-01

    Full Text Available Fungsi dari alat key tag atau hotel switch atau key card adalah memutus atau menyambungkan aliran listrik ke dalam suatu area tertentu atau ruang. Key tag memiliki peran penting pada kamar hotel untuk mencegah pemborosan energi pada saat kamar hotel tidak berpenghuni atau belum tersewakan. Untuk itu, penulis merancang simulasi sistem kelistrikan pada kamar hotel yang dikontrol dengan smart relay. Pada simulasi ini digunakan smart relay Zelio Logic buatan Schneider Electric. Pemrograman smart relay ini menggunakan ladder diagram yang disusun menggunakan perangkat lunak ZelioSoft2 dari Schneider Electric. Smart relay menerima sinyal masukan dari sensor, key tag dan sakelar. Sinyal masukan tersebut selanjutnya diproses agar lampu, kotak-kontak, exhaust fan, dan AC (Air Conditioner pada kamar hotel dapat bekerja.

  6. Error-rate performance analysis of opportunistic regenerative relaying

    KAUST Repository

    Tourki, Kamel

    2011-09-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path can be considered unusable, and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We first derive the exact statistics of each hop, in terms of probability density function (PDF). Then, the PDFs are used to determine accurate closed form expressions for end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation where the detector may use maximum ration combining (MRC) or selection combining (SC). Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over linear network (LN) architecture and considering Rayleigh fading channels. © 2011 IEEE.

  7. New results on performance analysis of opportunistic regenerative relaying

    KAUST Repository

    Tourki, Kamel

    2013-12-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path may be unusable, and takes into account the effect of the possible erroneously detected and transmitted data at the selected relay. We first derive the signal-to-noise (SNR) statistics for each hop, which are used to determine accurate closed form expressions for end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation and end-to-end outage probability for a transmission rate R over Rayleigh fading channels. Furthermore, we evaluate the asymptotical performance and deduce the diversity order. Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over linear network architecture. © 2013 Elsevier B.V.

  8. Data Relay Satellites and remote sensing

    Science.gov (United States)

    Kingwell, Jeff

    1988-05-01

    Issues concerning the operation and use of Data Relay Satellites (DRS) are discussed. Advantages of instituting DRS systems include continuous direct access to large amounts of data, frequent contact with satellites for TTC activities, and the ability to initiate global scientific observation to improve weather forecasting. DRS systems would allow for better control of ballistic missles and would reduce costs for commercial information-based business operations. Disadvantages of fully replacing direct transmissions with DRS include the fact that DRS would make present facilities obsolete, would lead to an increased risk of countries being able to obtain access to data of their own territory, could possibly allow operators to control the release of processed information, would use uniform processing techniques that might not meet the needs of every nation, might lead to an increase in the price of obtaining data in order to cover the high cost of implementing a DRS system, and would increase the chance of data loss and service delays if direct downlinking were not used as a backup.

  9. CERN Relay Race: a great success!

    CERN Multimedia

    Staff Association

    2016-01-01

    On Thursday May 19, the traditional relay race was held at CERN, organised jointly by the Running Club and the CERN Staff Association. In spite of the less than optimal weather, the 127 registered teams were not discouraged. Warmed by their efforts on the roads of CERN, the participants were able to withstand the chilly May weather. The start signal for the race was given by our Director General, demonstrating the interest in this event at the highest level of the Organization. Thank you for this much appreciated commitment! Can we hope for next year to see a team from the Directorate in the race? The many spectators who had come to cheer on the runners could also visit the stalls staffed by a few clubs and some of Interfon’s commercial partners. Refreshment and food stands contributed to the friendly atmosphere. The organisation of such an event requires however a substantial investment in order to cover all aspects of logistics, from preparation before the race, to the actual establishment ...

  10. CERN Relay Race: a great success!

    CERN Multimedia

    Staff Association

    2017-01-01

    Thursday 1st June marked the traditional Relay Race at CERN, organised jointly by the Running Club and the CERN Staff Association. Once again, the Race lived up to the expectations and the number of participants came close to last year’s all-time high with no less than 715 entries across different categories! In total 116 teams of 6 runners and 19 walkers completed the course at the Meyrin site in bright sunshine. Congratulations to all of them! Our Director-General gave the starting signal for the Race, demonstrating the interest in this event at the highest level of the Organization. Thank you for this much appreciated commitment! Moreover, a number of very high-level runners came to spice up this 2017 edition. The 1000-meter race was a tight one between Alexandre Roche (top 5 in the “Tour du canton”) and Baptiste Fieux who tore up the race at 2’36 and 2’42 respectively. Baptiste passed the baton to Pierre Baqué, the winner of the 2015 Saint&a...

  11. Thermal behaviour of synthetic pyroaurite-like anionic clay

    Czech Academy of Sciences Publication Activity Database

    Kovanda, F.; Balek, Vladimír; Dorničák, V.; Martinec, P.; Mašláň, M.; Bílková, L.; Koloušek, D.; Bountsewa, I. M.

    2003-01-01

    Roč. 72, č. 1 (2003), s. 727-737 ISSN 1388-6150 R&D Projects: GA MŠk LN00A028; GA ČR GA202/00/0982; GA ČR GA106/02/0523 Institutional research plan: CEZ:AV0Z4032918 Keywords : layered double hydroxide * pyroaurite-like anionic clay * thermal decomposition Subject RIV: CA - Inorganic Chemistry Impact factor: 1.094, year: 2003

  12. Impact Analysis of Electrical Current Characteristics in Relay Function for Electrical and Electronic Protection

    International Nuclear Information System (INIS)

    Syirrazie Che Soh; Harzawadi Hasim

    2013-01-01

    This paper is to study effect of electrical current on relay reaction, which has coil and switch inside the relay. An analysis on the electrical current will be conducted to determine current limitation for relay activation purpose. The result of analysis showing that current characteristic of relay and applied load will present their affect to the relay function performance. Finding from this result will bring the idea to develop a suitable design circuit for electrical and electronic protection. (author)

  13. Bad chemistry

    OpenAIRE

    Petsko, Gregory A

    2004-01-01

    General chemistry courses haven't changed significantly in forty years. Because most basic chemistry students are premedical students, medical schools have enormous influence and could help us start all over again to create undergraduate chemistry education that works.

  14. Identification of inorganic anions by gas chromatography/mass spectrometry.

    Science.gov (United States)

    Sakayanagi, Masataka; Yamada, Yaeko; Sakabe, Chikako; Watanabe, Kunio; Harigaya, Yoshihiro

    2006-03-10

    Inorganic anions were identified by using gas chromatography/mass spectrometry (GC/MS). Derivatization of the anions was achieved with pentafluorobenzyl p-toluenesulphonate (PFB-Tos) as the reaction reagent and a crown ether as a phase transfer catalyst. When PFB-Br was used as the reaction reagent, the retention time of it was close to those of the derivatized inorganic anions and interfered with the analysis. In contrast, the retention time of PFB-Tos differed greatly from the PFB derivatives of the inorganic anions and the compounds of interest could be detected without interference. Although the PFB derivatives of SO4, S2O3, CO3, ClO4, and ClO3 could not be detected, the derivatives of F, Cl, Br, I, CN, OCN, SCN, N3, NO3, and NO2 were detected using PFB-Tos as the derivatizing reagent. The inorganic anions were detectable within 30 ng approximately, which is of sufficient sensitivity for use in forensic chemistry. Accurate mass number was measured for each PFB derivative by high-resolution mass spectrometry (HRMS) within a measurement error of 2 millimass units (mmu), which allowed determination of the compositional formula from the mass number. In addition, actual analysis was performed successively by our method using trial samples of matrix.

  15. A SDP based design of relay precoding for the power minimization of MIMO AF-relay networks

    KAUST Repository

    Rao, Anlei

    2015-09-11

    Relay precoding for multiple-input and multiple-output (MIMO) relay networks has been approached by either optimizing the efficiency performance with given power consumption constraints or minimizing the power consumption with quality-of-service (QoS) requirements. For the later type design, previous works has worked on minimizing the approximated power consumption. In this paper, exact power consumption for all relays is derived into a quadratic form by diagonalizing the minimum-square error (MSE) matrix, and the relay precoding matrix is designed by optimizing this quadratic form with the help of semidefinite programming (SDP) relaxation. Our simulation results show that such a design can achieve a gain of around 3 dB against the previous design, which optimized the approximated power consumption. © 2015 IEEE.

  16. Discovery of Interstellar Anions in Cepheus and Auriga

    Science.gov (United States)

    Cordiner, M. A.; Charnely, S. B.; Buckle, J. V.; Walsh, C.

    2011-01-01

    We report the detection of microwave emission lines from the hydrocarbon anion C6H(-) and its parent neutral C6H in the star-forming region LI251 A (in Cepheus), and the pre-stellar core LI512 (in Auriga). The carbon chain-bearing species C4H, HC3N, HC5N, HC7N, and C3S are also detected in large abundances. The observations of L1251A constitute the first detections of anions and long-chain polyynes and cyanopolyynes (with more than five carbon atoms) in the Cepheus Flare star-forming region, and the first detection of anions in the vicinity of a protostar outside of the Taurus molecular cloud complex, indicating a possible wider importance for anions in the chemistry of star formation. Rotational excitation temperatures have been derived from the HC3N hyperfine structure lines and are found to be 6.2 K for L1251A and 8.7 K for LI5l2. The anion-to-neutral ratios are 3.6% and 4.1%, respectively, which are within the range of values previously observed in the interstellar medium, and suggest a relative uniformity in the processes governing anion abundances in different dense interstellar clouds. This research contributes toward the growing body of evidence that carbon chain anions are relatively abundant in interstellar clouds throughout the Galaxy, but especially in the regions of relatively high density and high depletion surrounding pre-stellar cores and young, embedded protostars.

  17. Once upon Anion: A Tale of Photodetachment

    Science.gov (United States)

    Lineberger, W. Carl

    2013-04-01

    This contribution is very much a personal history of a journey through the wonderful world of anion chemistry, and a tale of how advances in laser technologies, theoretical methods, and computational capabilities continuously enabled advances in our understanding. It is a story of the excitement and joy that come from the opportunity to add to the fabric of science, and to do so by working as a group of excited explorers with common goals. The participants in this journey include me, my students and postdoctoral associates, my collaborators, and our many generous colleagues. It all happened, in the words of the Beatles, “with a little help from my friends.” Actually, it was so much more than a little help!

  18. Phosphazene-promoted anionic polymerization

    KAUST Repository

    Zhao, Junpeng

    2014-01-01

    In the recent surge of metal-free polymerization techniques, phosphazene bases have shown their remarkable potential as organic promoters/catalysts for the anionic polymerization of various types of monomers. By complexation with the counterion (e.g. proton or lithium cation), phosphazene base significantly improve the nucleophilicity of the initiator/chain-end resulting in rapid and usually controlled anionic/quasi-anionic polymerization. In this review, we will introduce the general mechanism, i.e. in situ activation (of initiating sites) and polymerization, and summarize the applications of such a mechanism on macromolecular engineering toward functionalized polymers, block copolymers and complex macromolecular architectures.

  19. Modified Dynamic Decode-and-Forward Relaying Protocol for Type II Relay in LTE-Advanced and Beyond

    KAUST Repository

    Nam, Sung Sik

    2016-11-29

    In this paper, we propose a modified dynamic decode-and-forward (MoDDF) relaying protocol to meet the critical requirements for user equipment (UE) relays in next-generation cellular systems (e.g., LTE-Advanced and beyond). The proposed MoDDF realizes the fast jump-in relaying and the sequential decoding with an application of random codeset to encoding and re-encoding process at the source and the multiple UE relays, respectively. A subframe-by-subframe decoding based on the accumulated (or buffered) messages is employed to achieve energy, information, or mixed combining. Finally, possible early termination of decoding at the end user can lead to the higher spectral efficiency and more energy saving by reducing the frequency of redundant subframe transmission and decoding. These attractive features eliminate the need of directly exchanging control messages between multiple UE relays and the end user, which is an important prerequisite for the practical UE relay deployment. Copyright: © 2016 Nam et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

  20. Sum-Rate Enhancement in Multiuser MIMO Decode-and-Forward Relay Broadcasting Channel with Energy Harvesting Relays

    KAUST Repository

    Benkhelifa, Fatma

    2016-09-20

    In this paper, we consider a multiuser multipleinput multiple-output (MIMO) decode-and-forward (DF) relay broadcasting channel (BC) with single source, multiple energy harvesting (EH) relays and multiple destinations. All the nodes are equipped with multiple antennas. The EH and information decoding (ID) tasks at the relays and destinations are separated over the time, which is termed as the time switching (TS) scheme. As optimal solutions for the sum-rate maximization problems of BC channels and the MIMO interference channels are hard to obtain, the end-to-end sum rate maximization problem of a multiuser MIMO DF relay BC channel is even harder. In this paper, we propose to tackle a simplified problem where we employ the block diagonalization (BD) procedure at the source, and we mitigate the interference between the relaydestination channels using an algorithm similar to the BD method. In order to show the relevance of our low complex proposed solution, we compare it to the minimum mean-square error (MMSE) solution that was shown in the literature to be equivalent to the solution of the sum-rate maximization in MIMO broadcasting interfering channels. We also investigate the time division multiple access (TDMA) solution which separates all the information transmissions from the source to the relays and from the relays to the destinations over time. We provide numerical results to show the relevance of our proposed solution, in comparison with the no co-channel interference (CCI) case, the TDMA based solution and the MMSE based solution.

  1. Pentaarylfullerenes as noncoordinating cyclopentadienyl anions

    NARCIS (Netherlands)

    Bouwkamp, Marco W.; Meetsma, Auke

    2009-01-01

    The first example of an early-transition-metal complex involving a pentaarylfullerene was prepared. Instead of half-sandwich complexes, solvent separated ion pairs were obtained in which the pentaarylfullerene moiety acts as noncoordinating cyclopentadienyl anion.

  2. Performance Analysis of Selective Decode-and-Forward Multinode Incremental Relaying with Maximal Ratio Combining

    KAUST Repository

    Hadjtaieb, Amir

    2013-09-12

    In this paper, we propose an incremental multinode relaying protocol with arbitrary N-relay nodes that allows an efficient use of the channel spectrum. The destination combines the received signals from the source and the relays using maximal ratio Combining (MRC). The transmission ends successfully once the accumulated signal-to-noise ratio (SNR) exceeds a predefined threshold. The number of relays participating in the transmission is adapted to the channel conditions based on the feedback from the destination. The use of incremental relaying allows obtaining a higher spectral efficiency. Moreover, the symbol error probability (SEP) performance is enhanced by using MRC at the relays. The use of MRC at the relays implies that each relay overhears the signals from the source and all previous relays and combines them using MRC. The proposed protocol differs from most of existing relaying protocol by the fact that it combines both incremental relaying and MRC at the relays for a multinode topology. Our analyses for a decode-and-forward mode show that: (i) compared to existing multinode relaying schemes, the proposed scheme can essentially achieve the same SEP performance but with less average number of time slots, (ii) compared to schemes without MRC at the relays, the proposed scheme can approximately achieve a 3 dB gain.

  3. Complex chemistry

    International Nuclear Information System (INIS)

    Kim, Bong Gon; Kim, Jae Sang; Kim, Jin Eun; Lee, Boo Yeon

    2006-06-01

    This book introduces complex chemistry with ten chapters, which include development of complex chemistry on history coordination theory and Warner's coordination theory and new development of complex chemistry, nomenclature on complex with conception and define, chemical formula on coordination compound, symbol of stereochemistry, stereo structure and isomerism, electron structure and bond theory on complex, structure of complex like NMR and XAFS, balance and reaction on solution, an organo-metallic chemistry, biology inorganic chemistry, material chemistry of complex, design of complex and calculation chemistry.

  4. Bound anionic states of adenine

    Energy Technology Data Exchange (ETDEWEB)

    Haranczyk, Maciej; Gutowski, Maciej S; Li, Xiang; Bowen, Kit H

    2007-03-20

    Anionic states of nucleic acid bases are involved in DNA damage by low-energy electrons and in charge transfer through DNA. Previous gas phase studies of free, unsolvated nucleic acid base parent anions probed only dipole-bound states, which are not present in condensed phase environments, but did not observe valence anionic states, which for purine bases, are thought to be adiabatically unbound. Contrary to this expectation, we have demonstrated that some thus far ignored tautomers of adenine, which result from enamine-imine transformations, support valence anionic states with electron vertical detachment energies as large as 2.2 eV, and at least one of these anionic tautomers is adiabatically bound. Moreover, we predict that the new anionic tautomers should also dominate in solutions and should be characterized by larger values of electron vertical detachment energy than the canonical valence anion. All of the new-found anionic tautomers might be formed in the course of dissociative electron attachment followed by a hydrogen atom attachment to a carbon atom, and they might affect the structure and properties of DNA and RNA exposed to low-energy electrons. The discovery of these valence anionic states of adenine was facilitated by the development of: (i) a new experimental method for preparing parent anions of nucleic acid bases for photoelectron experiments, and (ii) a new combinatorial/ quantum chemical approach for identification of the most stable tautomers of organic molecules. The computational portion of this work was supported by the: (i) Polish State Committee for Scientific Research (KBN) Grants: DS/8000-4-0140-7 (M.G.) and N204 127 31/2963 (M.H.), (ii) European Social Funds (EFS) ZPORR/2.22/II/2.6/ARP/U/2/05 (M.H.), and (iii) US DOE Office of Biological and Environmental Research, Low Dose Radiation Research Program (M.G.). M.H. holds the Foundation for Polish Science (FNP) award for young scientists. The calculations were performed at the Academic

  5. Mathematical Chemistry

    OpenAIRE

    Trinajstić, Nenad; Gutman, Ivan

    2002-01-01

    A brief description is given of the historical development of mathematics and chemistry. A path leading to the meeting of these two sciences is described. An attempt is made to define mathematical chemistry, and journals containing the term mathematical chemistry in their titles are noted. In conclusion, the statement is made that although chemistry is an experimental science aimed at preparing new compounds and materials, mathematics is very useful in chemistry, among other things, to produc...

  6. Relay-based information broadcast in complex networks

    Science.gov (United States)

    Fan, Zhongyan; Han, Zeyu; Tang, Wallace K. S.; Lin, Dong

    2018-04-01

    Information broadcast (IB) is a critical process in complex network, usually accomplished by flooding mechanism. Although flooding is simple and no prior topological information is required, it consumes a lot of transmission overhead. Another extreme is the tree-based broadcast (TB), for which information is disseminated via a spanning tree. It achieves the minimal transmission overhead but the maintenance of spanning tree for every node is an obvious obstacle for implementation. Motivated by the success of scale-free network models for real-world networks, in this paper, we investigate the issues in IB by considering an alternative solution in-between these two extremes. A novel relay-based broadcast (RB) mechanism is proposed by employing a subset of nodes as relays. Information is firstly forwarded to one of these relays and then re-disseminated to others through the spanning tree whose root is the relay. This mechanism provides a trade-off solution between flooding and TB. On one hand, it saves up a lot of transmission overhead as compared to flooding; on the other hand, it costs much less resource for maintenance than TB as only a few spanning trees are needed. Based on two major criteria, namely the transmission overhead and the convergence time, the effectiveness of RB is confirmed. The impacts of relay assignment and network structures on performance are also studied in this work.

  7. Learning relay start strategies in swimming: What feedback is best?

    Science.gov (United States)

    Fischer, Sebastian; Braun, Claudia; Kibele, Armin

    2017-04-01

    In the past, studies and book recommendations on relay starts in swimming have been predominantly focused on the change-over time (COT) as a performance criterion. Aside from the circular backswing start with parallel foot placement, few studies have analysed differences in the take-off movement including step approaches as well. Although trends could be identified, the results remained still somewhat inconclusive. In contrast, no study has examined as has examined whether a reduction of COT in between wall contact of the income swimmer and the take-off of the outgoing swimmer is an optimal relay start strategy, as advocated by various swimming experts. Therefore, the purpose of this study was to compare two different relay start strategies: offensive strategy minimizing COT and conservative strategy to maximize horizontal peak force (HPF). In this regard, a learning intervention with 24 elite-level swimmers (12 females, 12 male) was conducted to compare both strategies regarding relay start time, HPF and COT. Subjects were randomly assigned to two feedback groups: COT versus HPF at take-off. The results of this study showed a clear advantage for HPF feedback for relay start performance measured by wall contact of the incoming swimmer and head passage at 7.5 m of the outgoing swimmer. In addition, similar reductions in COTs were found in both training groups. In conclusion, swimmers should focus on force production rather than minimizing COT. For the latter, deteriorating consequences for force production must be considered.

  8. Efficient incremental relaying for packet transmission over fading channels

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-07-01

    In this paper, we propose a novel relaying scheme for packet transmission over fading channels, which improves the spectral efficiency of cooperative diversity systems by utilizing limited feedback from the destination. Our scheme capitalizes on the fact that relaying is only required when direct transmission suffers deep fading. We calculate the packet error rate for the proposed efficient incremental relaying (EIR) scheme with both amplify and forward and decode and forward relaying. We compare the performance of the EIR scheme with the threshold-based incremental relaying (TIR) scheme. It is shown that the efficiency of the TIR scheme is better for lower values of the threshold. However, the efficiency of the TIR scheme for higher values of threshold is outperformed by the EIR. In addition, three new threshold-based adaptive EIR are devised to further improve the efficiency of the EIR scheme. We calculate the packet error rate and the efficiency of these new schemes to provide the analytical insight. © 2014 IEEE.

  9. Implementing Strategic Planning Capabilities Within the Mars Relay Operations Service

    Science.gov (United States)

    Hy, Franklin; Gladden, Roy; Allard, Dan; Wallick, Michael

    2011-01-01

    Since the Mars Exploration Rovers (MER), Spirit and Opportunity, began their travels across the Martian surface in January of 2004, orbiting spacecraft such as the Mars 2001 Odyssey orbiter have relayed the majority of their collected scientific and operational data to and from Earth. From the beginning of those missions, it was evident that using orbiters to relay data to and from the surface of Mars was a vastly more efficient communications strategy in terms of power consumption and bandwidth compared to direct-to-Earth means. However, the coordination between the various spacecraft, which are largely managed independently and on differing commanding timelines, has always proven to be a challenge. Until recently, the ground operators of all these spacecraft have coordinated the movement of data through this network using a collection of ad hoc human interfaces and various, independent software tools. The Mars Relay Operations Service (MaROS) has been developed to manage the evolving needs of the Mars relay network, and specifically to standardize and integrate the relay planning and coordination data into a centralized infrastructure. This paper explores the journey of developing the MaROS system, from inception to delivery and acceptance by the Mars mission users.

  10. Systematic Network Coding with the Aid of a Full-Duplex Relay

    DEFF Research Database (Denmark)

    Giacaglia, Giuliano; Shi, Xiaomeng; Kim, MinJi

    2013-01-01

    is to deliver a given number of data packets to a receiver with the aid of a relay. The source broadcasts to both the receiver and the relay using one frequency, while the relay uses another frequency for transmissions to the receiver, allowing for a full-duplex operation of the relay. We analyze the decoding...... complexity and delay performance of two types of relays: one that preserves the systematic structure of the code from the source; another that does not. A systematic relay forwards uncoded packets upon reception, but transmits coded packets to the receiver after receiving the first coded packet from...

  11. Alternate MIMO AF relaying networks with interference alignment: Spectral efficient protocol and linear filter design

    KAUST Repository

    Park, Kihong

    2013-02-01

    In this paper, we study a two-hop relaying network consisting of one source, one destination, and three amplify-and-forward (AF) relays with multiple antennas. To compensate for the capacity prelog factor loss of 1/2$ due to the half-duplex relaying, alternate transmission is performed among three relays, and the inter-relay interference due to the alternate relaying is aligned to make additional degrees of freedom. In addition, suboptimal linear filter designs at the nodes are proposed to maximize the achievable sum rate for different fading scenarios when the destination utilizes a minimum mean-square error filter. © 1967-2012 IEEE.

  12. Diastereomerically and enantiomerically pure 2,3-disubstituted pyrrolidines from 2,3-aziridin-1-ols using a sulfoxonium ylide: a one-carbon homologative relay ring expansion.

    Science.gov (United States)

    Schomaker, Jennifer M; Bhattacharjee, Somnath; Yan, Jun; Borhan, Babak

    2007-02-21

    An ylide-based aza-Payne rearrangement of 2,3-aziridin-1-ols leads to an efficient process for the preparation of pyrrolidines. The aza-Payne rearrangement under basic reaction conditions favors the formation of epoxy amines. Subsequent nucleophilic attack of the epoxide by the ylide yields a bis-anion, which upon a 5-exo-tet ring-closure yields the desired pyrrolidine, thus completing the relay of the three-membered to the five-membered nitrogen-containing ring system. This process takes place with complete transfer of stereochemical fidelity and can be applied to sterically hindered aziridinols.

  13. Joint opportunistic scheduling and network coding for bidirectional relay channel

    KAUST Repository

    Shaqfeh, Mohammad

    2013-07-01

    In this paper, we consider a two-way communication system in which two users communicate with each other through an intermediate relay over block-fading channels. We investigate the optimal opportunistic scheduling scheme in order to maximize the long-term average transmission rate in the system assuming symmetric information flow between the two users. Based on the channel state information, the scheduler decides that either one of the users transmits to the relay, or the relay transmits to a single user or broadcasts to both users a combined version of the two users\\' transmitted information by using linear network coding. We obtain the optimal scheduling scheme by using the Lagrangian dual problem. Furthermore, in order to characterize the gains of network coding and opportunistic scheduling, we compare the achievable rate of the system versus suboptimal schemes in which the gains of network coding and opportunistic scheduling are partially exploited. © 2013 IEEE.

  14. Telecommunications Relay Support of the Mars Phoenix Lander Mission

    Science.gov (United States)

    Edwards, Charles D., Jr.; Erickson, James K.; Gladden, Roy E.; Guinn, Joseph R.; Ilott, Peter A.; Jai, Benhan; Johnston, Martin D.; Kornfeld, Richard P.; Martin-Mur, Tomas J.; McSmith, Gaylon W.; hide

    2010-01-01

    The Phoenix Lander, first of NASA's Mars Scout missions, arrived at the Red Planet on May 25, 2008. From the moment the lander separated from its interplanetary cruise stage shortly before entry, the spacecraft could no longer communicate directly with Earth, and was instead entirely dependent on UHF relay communications via an international network of orbiting Mars spacecraft, including NASA's 2001 Mars Odyssey (ODY) and Mars Reconnaissance Orbiter (MRO) spacecraft, as well as ESA's Mars Express (MEX) spacecraft. All three orbiters captured critical event telemetry and/or tracking data during Phoenix Entry, Descent and Landing. During the Phoenix surface mission, ODY and MRO provided command and telemetry services, far surpassing the original data return requirements. The availability of MEX as a backup relay asset enhanced the robustness of the surface relay plan. In addition to telecommunications services, Doppler tracking observables acquired on the UHF link yielded an accurate position for the Phoenix landing site.

  15. Accurate performance analysis of opportunistic decode-and-forward relaying

    KAUST Repository

    Tourki, Kamel

    2011-07-01

    In this paper, we investigate an opportunistic relaying scheme where the selected relay assists the source-destination (direct) communication. In our study, we consider a regenerative opportunistic relaying scheme in which the direct path may be considered unusable, and the destination may use a selection combining technique. We first derive the exact statistics of each hop, in terms of probability density function (PDF). Then, the PDFs are used to determine accurate closed form expressions for end-to-end outage probability for a transmission rate R. Furthermore, we evaluate the asymptotical performance analysis and the diversity order is deduced. Finally, we validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures. © 2011 IEEE.

  16. Latest Changes to NASA's Laser Communication Relay Demonstration Project

    Science.gov (United States)

    Edwards, Bernard L.; Israel, David J.; Vithlani, Seema K.

    2018-01-01

    Over the last couple of years, NASA has been making changes to the Laser Communications Relay Demonstration Project (LCRD), a joint project between NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). The changes made makes LCRD more like a future Earth relay system that has both high speed optical and radio frequency links. This will allow LCRD to demonstrate a more detailed concept of operations for a future operational mission critical Earth relay. LCRD is expected to launch in June 2019 and is expected to be followed a couple of years later with a prototype user terminal on the International Space Station. LCRD's architecture will allow it to serve as a testbed in space and this paper will provide an update of its planned capabilities and experiments.

  17. Exact performance analysis of decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2010-06-01

    In this paper, we investigate a dual-hop decode-and-forward opportunistic relaying scheme where the source may or may not be able to communicate directly with the destination. In our study, we consider a regenerative relaying scheme in which the decision to cooperate takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive an exact closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact statistics of each hop. Unlike existing works where the analysis focused on high signal-to-noise ratio (SNR) regime, such results are important to enable the designers to take decisions regarding practical systems that operate at low SNR regime. We show that performance simulation results coincide with our analytical results.

  18. Outage analysis for underlay relay-assisted cognitive networks

    KAUST Repository

    Tourki, Kamel

    2012-12-01

    Cooperative relay technology was recently introduced into cognitive radio networks in order to enhance network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where the quality of service of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. We first provide the exact cumulative density function (CDF) of received signal-to-noise (SNR) over each hop with co-located relays. Then, the CDFs are used to determine very accurate closed-form expression for the outage probability for a transmission rate R. We validate our analysis by showing that simulation results coincide with our analytical results in Rayleigh fading channels. © 2012 IEEE.

  19. Cooperative AF Relaying in Spectrum-Sharing Systems: Outage Probability Analysis under Co-Channel Interferences and Relay Selection

    KAUST Repository

    Xia, Minghua

    2012-11-01

    For cooperative amplify-and-forward (AF) relaying in spectrum-sharing wireless systems, secondary users share spectrum resources originally licensed to primary users to communicate with each other and, thus, the transmit power of secondary transmitters is strictly limited by the tolerable interference powers at primary receivers. Furthermore, the received signals at a relay and at a secondary receiver are inevitably interfered by the signals from primary transmitters. These co-channel interferences (CCIs) from concurrent primary transmission can significantly degrade the performance of secondary transmission. This paper studies the effect of CCIs on outage probability of the secondary link in a spectrum-sharing environment. In particular, in order to compensate the performance loss due to CCIs, the transmit powers of a secondary transmitter and its relaying node are respectively optimized with respect to both the tolerable interference powers at the primary receivers and the CCIs from the primary transmitters. Moreover, when multiple relays are available, the technique of opportunistic relay selection is exploited to further improve system performance with low implementation complexity. By analyzing lower and upper bounds on the outage probability of the secondary system, this study reveals that it is the tolerable interference powers at primary receivers that dominate the system performance, rather than the CCIs from primary transmitters. System designers will benefit from this result in planning and designing next-generation broadband spectrum-sharing systems.

  20. Enhancing overcurrent relay performance using wavelet packet transform

    International Nuclear Information System (INIS)

    Adly, A.R.

    2012-01-01

    The function of a power system relaying is to cause the prompt removal of any element of power system from service when it is subjected to short circuit or it starts to operate in any abnormal manner that might cause damage or otherwise interfere with the effective operation of the rest of the system. Overcurrent protection is one of the most widely used relays in power system which is used for both primary and back-up protective relays, and applied in every protective zone in the system. The application of time overcurrent relays in power system presents serious limitations in terms of sensitivity and selectivity. Digital forms of such relays are being mostly used which have the advantages of data recording and adaptive features. This thesis introduces a technique based on Wavelet Packet Transform (WPT) to detect short circuit faults within wide variation in generating conditions, with very small voltage variation, and High-Impedance Faults (HIFs). Besides, it examines the load current continuously and changes the relay pick up value adaptively. WPT is used to estimate proper value for the RMS fundamental and hence calculate trip time accurately even that when the signals have been contaminated with other harmonics, inter harmonics or subharmonic. Simulation work was conducted using Alternative Transient Program (ATP) package. A radial distribution system and series compensated line are modeled as case studies. The performance of the proposed overcurrent scheme for both lines is extensively tested during different operating conditions including; normal, internal short circuit faults, HIFs and similar situations to HIFs: such as capacitor switching (in), capacitor switching (out), load switching, and no load line switching. This thesis also uses a technique that estimates the location of short circuit faults on a radial distribution system. The technique was tested to evaluate its suitability. The results indicate that the proposed technique works well. It also

  1. The Anion Gap is a Predictive Clinical Marker for Death in Patients with Acute Pesticide Intoxication.

    Science.gov (United States)

    Lee, Sun-Hyo; Park, Samel; Lee, Jung-Won; Hwang, Il-Woong; Moon, Hyung-Jun; Kim, Ki-Hwan; Park, Su-Yeon; Gil, Hyo-Wook; Hong, Sae-Yong

    2016-07-01

    Pesticide formulation includes solvents (methanol and xylene) and antifreeze (ethylene glycol) whose metabolites are anions such as formic acid, hippuric acid, and oxalate. However, the effect of the anion gap on clinical outcome in acute pesticide intoxication requires clarification. In this prospective study, we compared the anion gap and other parameters between surviving versus deceased patients with acute pesticide intoxication. The following parameters were assessed in 1,058 patients with acute pesticide intoxication: blood chemistry (blood urea nitrogen, creatinine, glucose, lactic acid, liver enzymes, albumin, globulin, and urate), urinalysis (ketone bodies), arterial blood gas analysis, electrolytes (Na(+), K(+), Cl(-) HCO3 (-), Ca(++)), pesticide field of use, class, and ingestion amount, clinical outcome (death rate, length of hospital stay, length of intensive care unit stay, and seriousness of toxic symptoms), and the calculated anion gap. Among the 481 patients with a high anion gap, 52.2% had a blood pH in the physiologic range, 35.8% had metabolic acidosis, and 12.1% had acidemia. Age, anion gap, pesticide field of use, pesticide class, seriousness of symptoms (all P anion gap, and pesticide class were significant risk factors for death in a multiple logistic regression analysis (P anion gap is a significant risk factor for death, regardless of the accompanying acid-base balance status in patients with acute pesticide intoxication.

  2. Resource allocation for relay assisted cognitive radio networks

    KAUST Repository

    Zafar, Ammar

    2012-09-16

    In this paper, we present two optimal resource allocation schemes that maximize throughput and symbol correct rate (SCR). The throughput and SCR are derived. The derived throughput and SCR are optimized with respect to the sensing time, the source transmission power and the relay transmission power. Numerical results show that the optimal sensing time is dependent on the primary user\\'s signal-to-noise-ratio (SNR). They also show that SCR increases with increase in the number of relays. © 2012 IEEE.

  3. Asymmetric Modulation Gains in Network Coded Relay Networks

    DEFF Research Database (Denmark)

    Roetter, Daniel Enrique Lucani; Fitzek, Frank

    2015-01-01

    –to–end throughput by (i) using network coding to control the use of the relay in an effective manner, and (ii) leveraging asymmetric modulation to enable the source to efficiently allocate its resources. We provide mathematical analysis and a simple optimization mechanism. Numerical results for the case of fading...... channels and standard error correcting codes at the physical layer show that gains of up to four-fold gains with respect to the use of the direct link are possible for a wide range of locations of the relay in between the source and the destination....

  4. An airborne meteorological data collection system using satellite relay /ASDAR/

    Science.gov (United States)

    Bagwell, J. W.; Lindow, B. G.

    1978-01-01

    The paper describes the aircraft to satellite data relay (ASDAR) project which processes information collected by the navigation and data systems of widebody jet aircraft which cross data-sparse areas of the tropics and southern hemisphere. The ASDAR system consists of a data acquisition and control unit to acquire, store, and format latitude, longitude, altitude, wind speed, wind direction, and outside air temperature data; a transmitter to relay the formatted data via satellite to the ground; and a clock to time the data sampling and transmission periods.

  5. Mobility Impact on Centralized Selection of Mobile Relays

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

    2010-01-01

    This paper considers the impact of node mobility on the selection of the lowest bit error rate (BER) relay path from access point to destination node in a downlink data transmission scenario. The access point uses link signal to noise ratio (SNR) measurements provided by the mobile nodes to select...... the path either as direct or two-hop via a mobile relay. The impact of delays in the measurement collection procedure in this scheme is analyzed in comparison to an ideal selection and an always direct scheme. An ns-2 and matlab based simulation framework is used to investigate effects of varying scenario...

  6. Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere

    Energy Technology Data Exchange (ETDEWEB)

    Desai, R. T.; Coates, A. J.; Wellbrock, A.; González-Caniulef, D.; Jones, G. H.; Lewis, G. R.; Taylor, S. A.; Kataria, D. O. [Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Surrey RH5 6NT (United Kingdom); Vuitton, V. [Université Grenoble Alpes, CNRS, IPAG, F-38000 Grenoble (France); Crary, F. J. [Laboratory for Atmospheric and Space Physics, University of Colorado, Innovation Drive, Boulder, CO 80303 (United States); Shebanits, O.; Wahlund, J.-E. [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden); Waite, J. H. [Space Science and Engineering Division, Southwest Research Institute (SWRI), 6220 Culebra Road, San Antonio, TX 78238 (United States); Cordiner, M.; Sittler, E. C. [NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Edberg, N. J. T., E-mail: r.t.desai@ucl.ac.uk [Swedish Institute of Space Physics, Box 537, SE-751 21 Uppsala (Sweden)

    2017-08-01

    Cassini discovered a plethora of neutral and ionized molecules in Titan’s ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q{sup −1}. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass resolving capability for negatively charged species observed at Titan altitudes of 950–1300 km. We report on detections consistently centered between 25.8 and 26.0 u q{sup −1} and between 49.0–50.1 u q{sup −1} which are identified as belonging to the carbon chain anions, CN{sup −}/C{sub 3}N{sup −} and/or C{sub 2}H{sup −}/C{sub 4}H{sup −}, in agreement with chemical model predictions. At higher ionospheric altitudes, detections at 73–74 u q{sup −1} could be attributed to the further carbon chain anions C{sub 5}N{sup −}/C{sub 6}H{sup −} but at lower altitudes and during further encounters extend over a higher mass/charge range. This, as well as further intermediary anions detected at >100 u, provide the first evidence for efficient anion chemistry in space involving structures other than linear chains. Furthermore, at altitudes below <1100 km, the low-mass anions (<150 u q{sup −1}) were found to deplete at a rate proportional to the growth of the larger molecules, a correlation that indicates the anions are tightly coupled to the growth process. This study adds Titan to an increasing list of astrophysical environments where chain anions have been observed and shows that anion chemistry plays a role in the formation of complex organics within a planetary atmosphere as well as in the interstellar medium.

  7. Physical-Layer Security of a Buffer-Aided Full-Duplex Relaying System

    KAUST Repository

    El Shafie, Ahmed

    2016-07-07

    This letter proposes a novel hybrid half-/full-duplex relaying scheme to enhance the relay channel security. A source node (Alice) communicates with her destination node (Bob) in the presence of a buffer-aided full-duplex relay node (Rooney) and a potential eavesdropper (Eve). Rooney adopts two different relaying, namely randomize-and-forward and decode-andforward relaying strategies, to improve the security of the legitimate system. In the first relaying strategy, Rooney uses a codebook different from that used at Alice. In the second relaying strategy, Rooney and Alice use the same codebooks. In addition, Rooney switches between half-duplex and full-duplex modes to further enhance the security of the legitimate system. The numerical results demonstrate that our proposed scheme achieves a significant average secrecy end-to-end throughput improvement relative to the conventional bufferless full-duplex relaying scheme.

  8. Optimal Contract Design for Cooperative Relay Incentive Mechanism under Moral Hazard

    Directory of Open Access Journals (Sweden)

    Nan Zhao

    2015-01-01

    Full Text Available Cooperative relay can effectively improve spectrum efficiency by exploiting the spatial diversity in the wireless networks. However, wireless nodes may acquire different network information with various users’ location and mobility, channels’ conditions, and other factors, which results in asymmetric information between the source and the relay nodes (RNs. In this paper, the relay incentive mechanism between relay nodes and the source is investigated under the asymmetric information. By modelling multiuser cooperative relay as a labour market, a contract model with moral hazard for relay incentive is proposed. To effectively incentivize the potential RNs to participate in cooperative relay, the optimization problems are formulated to maximize the source’s utility while meeting the feasible conditions under both symmetric and asymmetric information scenarios. Numerical simulation results demonstrate the effectiveness of the proposed contract design scheme for cooperative relay.

  9. Secure relay selection based on learning with negative externality in wireless networks

    Science.gov (United States)

    Zhao, Caidan; Xiao, Liang; Kang, Shan; Chen, Guiquan; Li, Yunzhou; Huang, Lianfen

    2013-12-01

    In this paper, we formulate relay selection into a Chinese restaurant game. A secure relay selection strategy is proposed for a wireless network, where multiple source nodes send messages to their destination nodes via several relay nodes, which have different processing and transmission capabilities as well as security properties. The relay selection utilizes a learning-based algorithm for the source nodes to reach their best responses in the Chinese restaurant game. In particular, the relay selection takes into account the negative externality of relay sharing among the source nodes, which learn the capabilities and security properties of relay nodes according to the current signals and the signal history. Simulation results show that this strategy improves the user utility and the overall security performance in wireless networks. In addition, the relay strategy is robust against the signal errors and deviations of some user from the desired actions.

  10. Interference alignment for degrees of freedom improvement in 3-relay half-duplex systems

    KAUST Repository

    Park, Seongho

    2011-12-01

    In a half-duplex relaying, the capacity pre-log factor is a major drawback in spectral efficiency. This paper proposes a linear precoding scheme and an alternate relaying protocol in a dual-hop half-duplex system where three relays help the communication between the source and the destination. In our proposed scheme, we consider a phase incoherent method in relays in which the source alternately transmits message signals to the different relays. In addition, we propose a linear interference alignment scheme which can eliminate the inter-relay interference resulted from the phase incoherence of relaying. Based on our analysis of degrees of freedom and our simulation results, we show that our proposed scheme achieves additional degrees of freedom compared to the conventional half-duplex relaying. © 2011 IEEE.

  11. Chemistry Notes

    Science.gov (United States)

    School Science Review, 1976

    1976-01-01

    Described are eight chemistry experiments and demonstrations applicable to introductory chemistry courses. Activities include: measure of lattice enthalpy, Le Chatelier's principle, decarboxylation of soap, use of pocket calculators in pH measurement, and making nylon. (SL)

  12. Chemistry Dashboard

    Science.gov (United States)

    The Chemistry Dashboard is part of a suite of dashboards developed by EPA to help evaluate the safety of chemicals. The Chemistry Dashboard provides access to a variety of information on over 700,000 chemicals currently in use.

  13. Positronium chemistry

    CERN Document Server

    Green, James

    1964-01-01

    Positronium Chemistry focuses on the methodologies, reactions, processes, and transformations involved in positronium chemistry. The publication first offers information on positrons and positronium and experimental methods, including mesonic atoms, angular correlation measurements, annihilation spectra, and statistical errors in delayed coincidence measurements. The text then ponders on positrons in gases and solids. The manuscript takes a look at the theoretical chemistry of positronium and positronium chemistry in gases. Topics include quenching, annihilation spectrum, delayed coincidence

  14. Aquatic Chemistry

    International Nuclear Information System (INIS)

    Kim, Dong Yeun; Kim, Oh Sik; Kim, Chang Guk; Park, Cheong Gil; Lee, Gwi Hyeon; Lee, Cheol Hui

    1987-07-01

    This book deals aquatic chemistry, which treats water and environment, chemical kinetics, chemical balance like dynamical characteristic, and thermodynamics, acid-base chemistry such as summary, definition, kinetics, and PH design for mixture of acid-base chemistry, complex chemistry with definition, and kinetics, precipitation and dissolution on summary, kinetics of precipitation and dissolution, and balance design oxidation and resolution with summary, balance of oxidation and resolution.

  15. Combinatorial chemistry

    DEFF Research Database (Denmark)

    Nielsen, John

    1994-01-01

    An overview of combinatorial chemistry is presented. Combinatorial chemistry, sometimes referred to as `irrational drug design,' involves the generation of molecular diversity. The resulting chemical library is then screened for biologically active compounds.......An overview of combinatorial chemistry is presented. Combinatorial chemistry, sometimes referred to as `irrational drug design,' involves the generation of molecular diversity. The resulting chemical library is then screened for biologically active compounds....

  16. Optimal Contract Design for Cooperative Relay Incentive Mechanism under Moral Hazard

    OpenAIRE

    Zhao, Nan; Wu, Minghu; Xiong, Wei; Liu, Cong

    2015-01-01

    Cooperative relay can effectively improve spectrum efficiency by exploiting the spatial diversity in the wireless networks. However, wireless nodes may acquire different network information with various users’ location and mobility, channels’ conditions, and other factors, which results in asymmetric information between the source and the relay nodes (RNs). In this paper, the relay incentive mechanism between relay nodes and the source is investigated under the asymmetric information. By mode...

  17. 77 FR 20553 - Relay Services for Deaf-Blind Individuals

    Science.gov (United States)

    2012-04-05

    ... COMMISSION 47 CFR Part 64 Relay Services for Deaf-Blind Individuals AGENCY: Federal Communications Commission... the requirement for National Deaf Blind Equipment Distribution Program (NDBEDP) certified programs to... to better enable selected participants to fully meet the needs of eligible low- income, deaf-blind...

  18. 76 FR 31261 - Relay Services for Deaf-Blind Individuals

    Science.gov (United States)

    2011-05-31

    ... COMMISSION 47 CFR Part 64 Relay Services for Deaf-Blind Individuals AGENCY: Federal Communications Commission... to establish the National Deaf-Blind Equipment Distribution Program (NDBEDP) pilot program in... environments shall be considered when determining whether the individual is deaf-blind under clauses (c)(2)(i...

  19. 2 Gigahertz Light Route Radio Relay Link between Asmara and ...

    African Journals Online (AJOL)

    In this paper is discussed the general problem involved in the introduclion of a recently installed light capacity radio relay system in the network of the Imperial Board of Telecommunications of Ethiopia. An outline of the factors governing the choice of appropriate systems and reasons for selecting microwave is given.

  20. Nitrogen economy in relay intercropping systems of wheat and cotton

    NARCIS (Netherlands)

    Zhang, L.Z.; Spiertz, J.H.J.; Zhang, S.; Li, B.; Werf, van der W.

    2008-01-01

    Relay intercropping of wheat and cotton is practiced on a large scale in China. Winter wheat is thereby grown as a food crop from November to June and cotton as a cash crop from April to October. The crops overlap in time, growing as an intercrop, from April till June. High levels of nitrogen are

  1. 49 CFR 236.556 - Adjustment of relay.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Adjustment of relay. 236.556 Section 236.556 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION...

  2. 47 CFR 90.243 - Mobile relay stations.

    Science.gov (United States)

    2010-10-01

    ... utilize a combination of digital selection and continuous coded tone control where required to insure... controlled from a manned fixed control point; shall have an automatic time delay or clock device that will... stations on fixed frequencies for any necessary interconnect circuits between the mobile relay stations. ...

  3. Appendices for: Improper Signaling in Two-Path Relay Channels

    KAUST Repository

    Gaafar, Mohamed

    2016-12-01

    This document contains the appendices for the work in “Improper Signaling in Two-Path Relay Channels,” which is submitted to 2017 IEEE International Conference on Communications (ICC) Workshop on Full-Duplex Communications for Future Wireless Networks, Paris, France.

  4. Micro-relay technology for energy-efficient integrated circuits

    CERN Document Server

    Kam, Hei

    2015-01-01

    This book describes the design of relay-based circuit systems from device fabrication to circuit micro-architectures. This book is ideal for both device engineers as well as circuit system designers and highlights the importance of co-design across design hierarchies when optimizing system performance (in this case, energy-efficiency). This book is ideal for researchers and engineers focused on semiconductors, integrated circuits, and energy efficient electronics. This book also: ·         Covers microsystem fabrication, MEMS device design, circuit design, circuit micro-architecture, and CAD ·         Describes work previously done in the field and also lays the groundwork and criteria for future energy-efficient device and system design ·         Maximizes reader insights into the design and modeling of micro-relay, micro-relay reliability, integrated circuit design with micro-relays, and more

  5. Optical bus of centralized relay protection and automation system of ...

    African Journals Online (AJOL)

    The article deals with the system of information collection and transfer from a centralized relay protection and automation system for medium voltage electrical units based on a passive optical bus. The issues of electromagnetic compatibility of technical devices are also considered, and the intensity of electromagnetic ...

  6. Boarding Team Networking on the Move: Applying Unattended Relay Nodes

    Science.gov (United States)

    2014-09-01

    overheads. International/Multinational companies built sophisticated trade networks all over the world based on low transportation costs. Competitive...Africa, China, or Brazil . As Metaparti indicates, companies use registration flags of convenience to circumvent tax evasion and other responsibilities...release; distribution is unlimited BOARDING TEAM NETWORKING ON THE MOVE: APPLYING UNATTENDED RELAY NODES Ercan Aras Lieutenant Junior Grade

  7. Demonstration Model of Self Inductance Using Relay Using an ...

    Indian Academy of Sciences (India)

    IAS Admin

    utilizes manual control and a complex electronic circuit to oscillate the relay. The glow of the neon bulb due to back emf from the coil and transformer was used to demonstrate the concept. In the present article, we first elaborate ... Q terminals, the current flow through the coil produces an electromagnetic field in the vicinity of ...

  8. Commercial Grade Item (CGI) Dedication for Leak Detection Relays

    International Nuclear Information System (INIS)

    KOCH, M.R.; JOHNS, B.R.

    1999-01-01

    This Test Plan provides a test method to dedicate the leak detection relays used on the new Pumping and Instrumentation Control (PIC) skids. The new skids are fabricated on-site. The leak detection system is a safety class system per the Authorization Basis

  9. Spatial organisation and biomass development after relaying of mussel seed

    NARCIS (Netherlands)

    Capelle, J.J.; Wijsman, J.W.M.; Schellekens, T.; van Stralen, M.R.; Herman, P.M.J.; Smaal, A.C.

    2014-01-01

    It is not known whether and by what factors spatial heterogeneity in mussels (Mytilus edulis L.) affects mussel production in human-created mussel beds. In a field experiment, the same number of mussels was relayed on four different areas within plots of the same size, resulting in four treatments

  10. System Requirements for Satellite Video Relays Supporting Unmanned Ground Vehicles

    OpenAIRE

    Randorf, Jeffrey

    1991-01-01

    The Unmanned Ground Vehicle Joint Project Office (UGV/JPO) has identified communications and control as the single most important issue concerning unmanned ground vehicle (UGV) deployment. This paper outlines needed capabilities for potential small satellite data relays for unmanned ground vehicle operations. Satellites could offer a solution to the inherent non-line-of-sight (NLOS), wide bandwidth dilemma.

  11. Advanced relay technologies in next generation wireless communications

    CERN Document Server

    Krikidis, Ioannis

    2016-01-01

    This book details the use of the cooperative networks/relaying approach in new and emerging telecommunications technologies such as full-duplex radio, massive multiple-input multiple-output (MIMO), network coding and spatial modulation, and new application areas including visible light communications (VLC), wireless power transfer, and 5G.

  12. protective relay studies for the nigerian national electric 330 kv

    African Journals Online (AJOL)

    user

    1985-09-01

    Sep 1, 1985 ... PROTECTIVE RELAY STUDIES FOR THE NIGERIAN NATIONAL ELECTRIC. 330 KV TRANSMISSION SYSTEM. By. A.U. CHUKU. Electrical Engineering Department. Ahmadu Bello University, Zaria, Nigeria. D.A. OYEYELE, S.K. AFOLABI. National Electric Power Authority. Electricity Headquarters, Marina'.

  13. On full duplex Gaussian relay channels with self-interference

    KAUST Repository

    Behboodi, Arash

    2016-08-15

    Self interference (SI) in full duplex (FD) systems is the interference caused by the transmission stream on the reception stream. Being one of the main restrictive factors for performance of practical full duplex systems, however, not too much is known about its effect on the fundamental limits of relaying systems. In this work, we consider the full duplex three-node relay channel with SI where SI is modeled as an additive Gaussian noise whose variance is dependent on instantaneous input power. The classical achievable rates and upper bounds for the single three-node relay channel no longer apply due to the structure of SI. Achievable rates for Decode-and-Forward (DF) and Compress-and-Forward (CF) and upper bounds on the capacity are derived assuming Gaussian inputs and SI. The deterministic model is also introduced and its capacity is characterized. The optimal joint source-relay distributions is discussed. Numerical results are provided comparing the achievable rates and upper bound. © 2016 IEEE.

  14. CERN’s annual relay a runaway success

    CERN Multimedia

    Klaus Hanke for the CERN Running Club

    2016-01-01

    With a record participation of 128 teams of six runners each, this year’s CERN Relay Race took place on 19 May on the Meyrin site.   One of the many winning teams from the 2016 relay race. (Image: Sophia Bennett/CERN) With a record participation of 128 teams and 768 runners, this year’s CERN Relay Race took place on 19 May on the Meyrin site. The teams were mainly composed of CERN staff or contractors working on the CERN site.  A few external teams took also part in the race. Times ranged from 10 min 19 s to over 18 min. The Running Club website now has both the results, and the photos from race day. The CERN Relay Race is jointly organised every year by the CERN Running Club and the Staff Association. It is a tradition that is appreciated by many as a team building, rather than a competitive event. The CERN Running Club wishes to thank all runners and all volunteers for making this event a success.

  15. 75 FR 51735 - Structure and Practices of the Video Relay Service Program

    Science.gov (United States)

    2010-08-23

    ... billing of illegitimate minutes to the Interstate Telecommunications Relay Service (TRS) Fund (Fund... Practices of the Video Relay Service Program AGENCY: Federal Communications Commission. [[Page 51736... to detect and prevent fraud and misuse in the provision of Video Relay Service (VRS). Because the VRS...

  16. Development of a Relay Performance Web Tool for the Mars Network

    Science.gov (United States)

    Allard, Daniel A.; Edwards, Charles D.

    2009-01-01

    Modern Mars surface missions rely upon orbiting spacecraft to relay communications to and from Earth systems. An important component of this multi-mission relay process is the collection of relay performance statistics supporting strategic trend analysis and tactical anomaly identification and tracking.

  17. Performance of Ad Hoc Networks with Two-Hop Relay Routing and Limited Packet Lifetime

    NARCIS (Netherlands)

    Al Hanbali, Ahmad; Nain, Philippe; Altman, Eitan

    2006-01-01

    Considered is a mobile ad hoc network consisting of three types of nodes (source, destination and relay nodes) and using the two-hop relay routing protocol. Packets at relay nodes are assumed to have a limited lifetime in the network. All nodes are moving inside a bounded region according to some

  18. 47 CFR 64.606 - VRS and IP Relay provider and TRS program certification.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 3 2010-10-01 2010-10-01 false VRS and IP Relay provider and TRS program... Services and Related Customer Premises Equipment for Persons With Disabilities § 64.606 VRS and IP Relay... including notification in the Federal Register. (2) VRS and IP Relay provider. Any entity desiring to...

  19. Calcium-tolerant anionic surfactants

    NARCIS (Netherlands)

    Kooreman, Alexander

    1995-01-01

    One of the problems of applying anionic surfactants in, for example, laundry detergents is the precipitation of calcium salts. Much effort has been directed towards avoiding precipitation. There are at least three ways for tackling the problem. The first involves the use of a large quantity of

  20. Quantum mechanics of toroidal anions

    International Nuclear Information System (INIS)

    Afanas'ev, G.N.

    1990-01-01

    We consider a toroidal solenoid with an electric charge attached to it. It turns out that statistical properties of the wave function describing interacting toroidal anions depend on both their relative position and orientation. The influence of the particular gauge choice on the exchange properties of the wave function is studied. 30 refs.; 6 figs

  1. Pu Anion Exchange Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

    Taylor-Pashow, Kathryn M. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-10-06

    This research is focused on improving the efficiency of the anion exchange process for purifying plutonium. While initially focused on plutonium, the technology could also be applied to other ion-exchange processes. Work in FY17 focused on the improvement and optimization of porous foam columns that were initially developed in FY16. These foam columns were surface functionalized with poly(4-vinylpyridine) (PVP) to provide the Pu specific anion-exchange sites. Two different polymerization methods were explored for maximizing the surface functionalization with the PVP. The open-celled polymeric foams have large open pores and large surface areas available for sorption. The fluid passes through the large open pores of this material, allowing convection to be the dominant mechanism by which mass transport takes place. These materials generally have very low densities, open-celled structures with high cell interconnectivity, small cell sizes, uniform cell size distributions, and high structural integrity. These porous foam columns provide advantages over the typical porous resin beads by eliminating the slow diffusion through resin beads, making the anion-exchange sites easily accessible on the foam surfaces. The best performing samples exceeded the Pu capacity of the commercially available resin, and also offered the advantage of sharper elution profiles, resulting in a more concentrated product, with less loss of material to the dilute heads and tails cuts. An alternate approach to improving the efficiency of this process was also explored through the development of a microchannel array system for performing the anion exchange.

  2. Anion binding in biological systems

    Energy Technology Data Exchange (ETDEWEB)

    Feiters, Martin C [Department of Organic Chemistry, Institute for Molecules and Materials, Faculty of Science, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ Nijmegen (Netherlands); Meyer-Klaucke, Wolfram [EMBL Hamburg Outstation at DESY, Notkestrasse 85, D-22607 Hamburg (Germany); Kostenko, Alexander V; Soldatov, Alexander V [Faculty of Physics, Southern Federal University, Sorge 5, Rostov-na-Donu, 344090 (Russian Federation); Leblanc, Catherine; Michel, Gurvan; Potin, Philippe [Centre National de la Recherche Scientifique and Universite Pierre et Marie Curie Paris-VI, Station Biologique de Roscoff, Place Georges Teissier, BP 74, F-29682 Roscoff cedex, Bretagne (France); Kuepper, Frithjof C [Scottish Association for Marine Science, Dunstaffnage Marine Laboratory, Oban, Argyll PA37 1QA, Scotland (United Kingdom); Hollenstein, Kaspar; Locher, Kaspar P [Institute of Molecular Biology and Biophysics, ETH Zuerich, Schafmattstrasse 20, Zuerich, 8093 (Switzerland); Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R, E-mail: m.feiters@science.ru.n [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands)

    2009-11-15

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L{sub 3} (2p{sub 3/2}) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  3. Anion binding in biological systems

    International Nuclear Information System (INIS)

    Feiters, Martin C; Meyer-Klaucke, Wolfram; Kostenko, Alexander V; Soldatov, Alexander V; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Kuepper, Frithjof C; Hollenstein, Kaspar; Locher, Kaspar P; Bevers, Loes E; Hagedoorn, Peter-Leon; Hagen, Wilfred R

    2009-01-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L 3 (2p 3/2 ) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  4. Anion binding in biological systems

    Science.gov (United States)

    Feiters, Martin C.; Meyer-Klaucke, Wolfram; Kostenko, Alexander V.; Soldatov, Alexander V.; Leblanc, Catherine; Michel, Gurvan; Potin, Philippe; Küpper, Frithjof C.; Hollenstein, Kaspar; Locher, Kaspar P.; Bevers, Loes E.; Hagedoorn, Peter-Leon; Hagen, Wilfred R.

    2009-11-01

    We compare aspects of biological X-ray absorption spectroscopy (XAS) studies of cations and anions, and report on some examples of anion binding in biological systems. Brown algae such as Laminaria digitata (oarweed) are effective accumulators of I from seawater, with tissue concentrations exceeding 50 mM, and the vanadate-containing enzyme haloperoxidase is implicated in halide accumulation. We have studied the chemical state of iodine and its biological role in Laminaria at the I K edge, and bromoperoxidase from Ascophyllum nodosum (knotted wrack) at the Br K edge. Mo is essential for many forms of life; W only for certain archaea, such as Archaeoglobus fulgidus and the hyperthermophilic archaeon Pyrococcus furiosus, and some bacteria. The metals are bound and transported as their oxo-anions, molybdate and tungstate, which are similar in size. The transport protein WtpA from P. furiosus binds tungstate more strongly than molybdate, and is related in sequence to Archaeoglobus fulgidus ModA, of which a crystal structure is known. We have measured A. fulgidus ModA with tungstate at the W L3 (2p3/2) edge, and compared the results with the refined crystal structure. XAS studies of anion binding are feasible even if only weak interactions are present, are biologically relevant, and give new insights in the spectroscopy.

  5. MALDI-TOF MS analysis of the self-termination products in the anionic methyl methacrylate/tert-butyl acrylate block copolymerization

    Czech Academy of Sciences Publication Activity Database

    Vlček, Petr; Čadová, Eva; Horský, Jiří; Janata, Miroslav

    2015-01-01

    Roč. 72, č. 9 (2015), s. 2227-2239 ISSN 0170-0839 Institutional support: RVO:61389013 Keywords : anionic polymerization * acrylates * block copolymer Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.371, year: 2015

  6. Polarizability of the Nitrate Anion and Its Solvation at the Air/Water Interface

    Czech Academy of Sciences Publication Activity Database

    Salvador, P.; Curtis, J. E.; Tobias, D. J.; Jungwirth, Pavel

    2003-01-01

    Roč. 5, - (2003), s. 3752-3757 ISSN 1463-9076 R&D Projects: GA MŠk LN00A032 Institutional research plan: CEZ:AV0Z4040901 Keywords : polarizability * nitrate anion * air/water Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.959, year: 2003

  7. Water in ionic liquids: correlation between anion hydrophilicity and near-infrared fingerprints

    Czech Academy of Sciences Publication Activity Database

    Tomšík, Elena; Gospodinova, Natalia

    2016-01-01

    Roč. 17, č. 11 (2016), s. 1586-1590 ISSN 1439-4235 R&D Projects: GA ČR(CZ) GA15-14791S; GA ČR(CZ) GA13-00270S Institutional support: RVO:61389013 Keywords : anions * hydrophilicity * ionic liquids Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.075, year: 2016

  8. Anion Receptors based on Ureidocalix[4]arenes Immobilised in the Partial cone Conformation

    Czech Academy of Sciences Publication Activity Database

    Hudeček, O.; Budka, J.; Dvořáková, H.; Cuřínová, Petra; Císařová, I.; Lhoták, P.

    2013-01-01

    Roč. 37, č. 1 (2013), s. 220-227 ISSN 1144-0546 R&D Projects: GA ČR GA203/09/0691; GA AV ČR IAAX08240901 Institutional support: RVO:67985858 Keywords : anion receptors * ureidocalix[4]arenes * partial cone conformation Subject RIV: CC - Organic Chemistry Impact factor: 3.159, year: 2013

  9. Determination of the ion-exchange capacity of anion-selective membranes

    Czech Academy of Sciences Publication Activity Database

    Karas, F.; Hnát, J.; Paidar, M.; Schauer, Jan; Bouzek, K.

    2014-01-01

    Roč. 39, č. 10 (2014), s. 5054-5062 ISSN 0360-3199 Institutional support: RVO:61389013 Keywords : ion-exchange capacity * anion-selective membranes * titration Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.313, year: 2014

  10. Anion recognition by calix[4]arene-based p-nitrophenyl amides

    Czech Academy of Sciences Publication Activity Database

    Flídrová, K.; Tkadlecová, M.; Lang, Kamil; Lhoták, P.

    2012-01-01

    Roč. 53, č. 6 (2012), s. 678-680 ISSN 0040-4039 R&D Projects: GA ČR GA203/09/0691 Institutional research plan: CEZ:AV0Z40320502 Keywords : calixarenes * anion recognition * receptor * complexation * UV/Vis titration Subject RIV: CA - Inorganic Chemistry Impact factor: 2.397, year: 2012

  11. Back-biting termination in methyl methacrylate/tert-butyl acrylate anionic block copolymerization

    Czech Academy of Sciences Publication Activity Database

    Čadová, Eva; Dybal, Jiří; Kříž, Jaroslav; Vlček, Petr; Janata, Miroslav; Toman, Luděk

    2008-01-01

    Roč. 209, č. 16 (2008), s. 1657-1665 ISSN 1022-1352 Institutional research plan: CEZ:AV0Z40500505 Keywords : acrylates * anionic polymerization * spontaneous termination Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.202, year: 2008

  12. Synthesis and anion exchange reactions of a layered copper–zinc ...

    Indian Academy of Sciences (India)

    Unknown

    629. *For correspondence. Synthesis and anion exchange reactions of a layered copper–zinc hydroxy double salt, Cu1⋅6Zn0⋅4(OH)3(OAc)⋅H2O. JACQUELINE THERESE RAJAMATHI, SYLVIA BRITTO and MICHAEL RAJAMATHI*. Department of Chemistry, St. Joseph's College, Lalbagh Road, Bangalore 560 027, India.

  13. Aqueous chemistry of transactinides

    International Nuclear Information System (INIS)

    Schaedel, M.

    2001-01-01

    The aqueous chemistry of the first three transactinide elements is briefly reviewed with special emphasis given to recent experimental results. Short introductory remarks are discussing the atom-at-a-time situation of transactinide chemistry as a result of low production cross-sections and short half-lives. In general, on-line experimental techniques and, more specifically, the automated rapid chemistry apparatus, ARCA, are presented. Present and future developments of experimental techniques and resulting perspectives are outlined at the end. The central part is mainly focussing on hydrolysis and complex formation aspects of the superheavy group 4, 5, and 6 transition metals with F - and Cl - anions. Experimental results are compared with the behaviour of lighter homologous elements and with relativistic calculations. It will be shown that the chemical behaviour of the first superheavy elements is already strongly influenced by relativistic effects. While it is justified to place rutherfordium, dubnium and seaborgium in the Periodic Table of the Elements into group 4, 5 and 6, respectively, it is no more possible to deduce from this position in detail the chemical properties of these transactinide or superheavy elements. (orig.)

  14. Methods and systems for measuring anions

    KAUST Repository

    Masih, Dilshad

    2016-08-18

    Embodiments of the present disclosure provide for methods for detecting the presence and/or concentration of anions in a solution, systems for detecting the presence and/or concentration of anions in a solution, anion sensor systems, and the like.

  15. Analysis and Measurement of Residual Stress in Bridge Membrane MEMS Relays

    Science.gov (United States)

    Ruan, Yong; Wang, Weizhong; Zhu, Yong; You, Zheng

    2017-04-01

    Microelectromechanical system (MEMS) relays are gradually replacing traditional relays because they are smaller and lighter and consume less power. However, performance parameters of MEMS relays, such as the pull-down voltage, response time, and resonant frequency, often deviate from those originally designed, due to residual stress generated during the fabrication process. We present herein a method to measure this residual stress, based on a metal bridge membrane MEMS relay, with the help of a nanoindenter and the finite-element method (FEM). The testing result lies in a reasonable range, indicating that this simple method is reliable and helpful for MEMS relay optimization.

  16. Optimized Policies for Improving Fairness of Location-based Relay Selection

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Olsen, Rasmus Løvenstein; Madsen, Tatiana Kozlova

    2013-01-01

    For WLAN systems in which relaying is used to improve throughput performance for nodes located at the cell edge, node mobility and information collection delays can have a significant impact on the performance of a relay selection scheme. In this paper we extend our existing Markov Chain modeling...... framework for relay selection to allow for efficient calculation of relay policies given either mean throughput or kth throughput percentile as optimization criterium. In a scenario with static access point, static relay, and a mobile destination node, the kth throughput percentile optimization...... is furthermore shown to be beneficial for improving throughput among weak node positions that will otherwise achieve zero throughput....

  17. Effect of chemical retention on anionic species diffusion in compacted clays

    International Nuclear Information System (INIS)

    Bazer-Bachi, Frederic

    2005-01-01

    Anionic radioisotopes are of particular importance within the framework of the calculated health risk associated with high-level and long-lived intermediate-level underground radioactive waste disposal. Therefore, the objective of this work is the construction of a transport model coupled with chemistry in order to quantify the behaviour of anionic solutes in the Callovo-Oxfordian (CO x ) argillite, the argillaceous host rock of the ANDRA Meuse/Haute-Marne underground laboratory. An experimental methodology was defined to characterize this migration, several experimental methods being implemented: batch experiments, laboratory columns and through-diffusion cells. The study of the diffusion of the non-sorbing anionic tracer 36 Cl - highlighted the fact that, due to anionic exclusion, anions only had access to a part of the porosity. The retention of 35 SO 4 2- and 125 I- on CO x argillite was then characterized, quantified by batch experiments and confirmed by other experimental methods. Nevertheless, their migration was less retarded than expected by a model based on batch experiments and on 36 Cl - diffusive data. This difference was explained by anion exclusion which reduced sorption site accessibility. Thus, the intensity of this phenomenon has to be considered to model anion migration in compacted clays. (author) [fr

  18. The anion-binding polyanion: a molecular cobalt vanadium oxide with anion-sensitive visual response.

    Science.gov (United States)

    Seliverstov, Andrey; Forster, Johannes; Heiland, Magdalena; Unfried, Johannes; Streb, Carsten

    2014-07-25

    An anionic molecular cobalt vanadium oxide cluster, (n-Bu4N)3[Co(AcO)V4O12] and its use as anion binding site is reported. Cluster formation is controlled by an anion-dependent dynamic solution equilibrium. Reversible anion binding in solution leads to significant spectral changes, allowing the ratiometric optical detection of the anion concentration in situ, even under harsh thermal conditions (T = 90 °C). Comparative studies showed that the spectral response is dependent on the type of anion so that carboxylates, weakly coordinating anions and halides can be distinguished.

  19. Relay Placement for FSO Multihop DF Systems With Link Obstacles and Infeasible Regions

    KAUST Repository

    Zhu, Bingcheng

    2015-05-19

    Optimal relay placement is studied for free-space optical multihop communication with link obstacles and infeasible regions. An optimal relay placement scheme is proposed to achieve the lowest outage probability, enable the links to bypass obstacles of various geometric shapes, and place the relay nodes in specified available regions. When the number of relay nodes is large, the searching space can grow exponentially, and thus, a grouping optimization technique is proposed to reduce the searching time. We numerically demonstrate that the grouping optimization can provide suboptimal solutions close to the optimal solutions, but the average searching time linearly grows with the number of relay nodes. Two useful theorems are presented to reveal insights into the optimal relay locations. Simulation results show that our proposed optimization framework can effectively provide desirable solution to the problem of optimal relay nodes placement. © 2015 IEEE.

  20. A study on Relay Effect via Magnetic Resonant Coupling for Wireless Power Transfer

    Directory of Open Access Journals (Sweden)

    Rashid N.A.

    2016-01-01

    Full Text Available Wireless power transfer (WPT transmits electrical energy from a power source to an electrical load wirelessly or without any conductors. The capability of WPT to transmit the energy is limited. Therefore, a relay was introduced to increase the distance of the WPT capabilities. The effect of the relay has been investigated to extend the energy transfer distance. The effect of relay was demonstrated by placing a relay coil between transmitter and receiver, relay biased to transmitter and placing two relay coils in the designed system. Experimental results are provided to prove the concept of the relay effect. The power transmission efficiency can be achieved up to 75% at 1 meter distance.

  1. On the capacity of multiple cognitive links through common relay under spectrum-sharing constraints

    KAUST Repository

    Yang, Yuli

    2011-06-01

    In this paper, we consider an underlay cognitive relaying network consisting of multiple secondary users and introduce a cooperative transmission protocol using a common relay to help with the communications between all secondary source-destination pairs for higher throughput and lower realization complexity. A whole relay-assisted transmission procedure is composed of multiple access phase and broadcast phase, where the relay is equipped with multiple antennas, and the secondary sources and destinations are single-antenna nodes. Considering the spectrum-sharing constraints on the secondary sources and the relay, we analyze the capacity behaviors of the underlay cognitive relaying network under study. The corresponding numerical results provide a convenient tool for the presented network design and substantiate a distinguishing feature of introduced design in that multiple secondary users\\' communications do not rely on multiple relays, hence allowing for a more efficient use of the radio resources. © 2011 IEEE.

  2. Asymptotic analysis for Nakagami-m fading channels with relay selection

    KAUST Repository

    Zhong, Caijun

    2011-06-01

    In this paper, we analyze the asymptotic outage probability performance of both decode-and-forward (DF) and amplify-and-forward (AF) relaying systems using partial relay selection and the "best" relay selection schemes for Nakagami-m fading channels. We derive their respective outage probability expressions in the asymptotic high signal-to-noise ratio (SNR) regime, from which the diversity order and coding gain are analyzed. In addition, we investigate the impact of power allocation between the source and relay terminals and derive the diversity-multiplexing tradeoff (DMT) for these relay selection systems. The theoretical findings suggest that partial relay selection can improve the diversity of the system and can achieve the same DMT as the "best" relay selection scheme under certain conditions. © 2011 IEEE.

  3. Laser cooling of molecular anions.

    Science.gov (United States)

    Yzombard, Pauline; Hamamda, Mehdi; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-05-29

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarize the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C_{2}^{-}, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photodetachment process is present, as well as Doppler laser cooling of trapped C_{2}^{-}, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources, and antimatter physics.

  4. Laser Cooling of Molecular Anions

    CERN Document Server

    Yzombard, Pauline; Gerber, Sebastian; Doser, Michael; Comparat, Daniel

    2015-01-01

    We propose a scheme for laser cooling of negatively charged molecules. We briefly summarise the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C$\\_2^-$, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photo-detachment process is present, as well as Doppler laser cooling of trapped C$\\_2^-$, are also simulated. This cooling scheme has an impact on the study of cold molecules, molecular anions, charged particle sources and antimatter physics.

  5. Organic chemistry

    International Nuclear Information System (INIS)

    2003-08-01

    This book with sixteen chapter explains organic chemistry on linkage isomerism such as alkane, cycloalkane, alkene, aromatic compounds, stereo selective isomerization, aromatic compounds, stereo selective isomerization, organic compounds, stereo selective isomerization, organic halogen compound, alcohol, ether, aldehyde and ketone, carboxylic acid, dicarboxylic acid, fat and detergent, amino, carbohydrate, amino acid and protein, nucleotide and nucleic acid and spectroscopy, a polymer and medical chemistry. Each chapter has introduction structure and characteristic and using of organic chemistry.

  6. Simulation of Distance Relay for Load Encroachment Alleviation with Agent Based Supervision of Zone3

    Directory of Open Access Journals (Sweden)

    Mohamed Badr

    2017-03-01

    Full Text Available Cascaded tripping of power lines due to mal-operation of zone-3 distance relays has been one of the main causes of many previous blackouts worldwide. Encroachment of load into zone-3 characteristics during stressed system operation conditions is a basic factor for such mal-operation of the relays. By improving the operation of zone-3, it is possible to prevent mal-operations so that cascaded line tripping can be avoided. For proper study of the behavior of distance relay during faults and load encroachment phenomenon, we must build a model of distance relay, so in this paper a modeling study of distance relay is implemented using MATLAB/Simulink program. However, this model is distinguished from previous models that, examines in detail the third zone of distance relay. Many cases are simulated with changing line loading and fault location to ensure the capability of the relay to detect the fault and thus the maximum load ability limit of distance relay is obtained. In order to prevent cascading events caused by hidden failures in zone-3 relays, agent based relay architectures have been suggested in the recent past. In such architectures each zone-3 relay contains agents that require communication with other agents at various relevant relays in order to distinguish a real zone-3 event from a temporary overload. In this paper, a local master agent is consulted by all zone-3 agents before a tripping decision is made. The master agent maintains a rule base which is updated based on the local topology of the network and real time monitoring of the status of other relays and circuit breakers. Cisco Packet Tracer program is used for running communication network simulations. The result of the simulation indicate that the time estimated to send and receive a packet data unit (PDU message between one relay to anther can satisfy the communication requirement for the proposed scheme with fiber media.

  7. Chemistry Technology

    Data.gov (United States)

    Federal Laboratory Consortium — Chemistry technology experts at NCATS engage in a variety of innovative translational research activities, including:Design of bioactive small molecules.Development...

  8. Technetium chemistry

    International Nuclear Information System (INIS)

    Burns, C.; Bryan, J.; Cotton, F.; Ott, K.; Kubas, G.; Haefner, S.; Barrera, J.; Hall, K.; Burrell, A.

    1996-01-01

    Technetium chemistry is a young and developing field. Despite the limited knowledge of its chemistry, technetium is the workhorse for nuclear medicine. Technetium is also a significant environmental concern because it is formed as a byproduct of nuclear weapons production and fission-power generators. Development of new technetium radio-pharmaceuticals and effective environmental control depends strongly upon knowledge of basic technetium chemistry. The authors performed research into the basic coordination and organometallic chemistry of technetium and used this knowledge to address nuclear medicine and environmental applications. This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL)

  9. 75 FR 67333 - Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and...

    Science.gov (United States)

    2010-11-02

    ... Docket No. 10-191; FCC 10-161] Telecommunications Relay Services and Speech-to-Speech Services for...-Based Telecommunications Relay Service Numbering AGENCY: Federal Communications Commission. ACTION... Internet-based Telecommunications Relay Service (iTRS), specifically, Video Relay Service (VRS) and IP...

  10. 78 FR 49717 - Speech-to-Speech and Internet Protocol (IP) Speech-to-Speech Telecommunications Relay Services...

    Science.gov (United States)

    2013-08-15

    ...] Speech-to-Speech and Internet Protocol (IP) Speech-to-Speech Telecommunications Relay Services; Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and Speech Disabilities... Internet Protocol (IP) Speech-to-Speech Telecommunications Relay Services; Telecommunications Relay...

  11. Bibliographies on radiation chemistry

    International Nuclear Information System (INIS)

    This bibliography lists about 400 papers dealing solely with the production and reactivity of superoxide radical anions in irradiated aqueous and organic liquids. Only papers dealing with quantitative mechanistic, spectroscopic or kinetic data have been included. The listing was prepared by searching the RCDC bibliographic data base with SELECT keywords O 2 - or HO 2 and aqueous solution. The key words radicals (oxygen), peroxy radicals, pulse radiolysis, flash radiolysis, esr and gamma rays were also used. Additional relevant references were obtained from inspection of reviews, individual author indexes and cited references. The present bibliography excludes solid and gas phase studies, and also technical, government and in-house reports, theses, patents and some symposia proceedings. Several references prior to 1960 have been added, and the list should be reasonably comprehensive from 1965-1980. The listing is in chronological order, according to year of publication in the categories Photochemistry, Radiation Chemistry, Other, and Reviews. (author)

  12. Electrochemical Oxidation of [1-X-12-I-CB11Me10–] Anions: Formation of Borenium Ylides [12-Dehydro-1-X-CB11Me10] and Iodonium Ylide Anions [{12-(1-X-CB11Me10–)}2I+

    Czech Academy of Sciences Publication Activity Database

    Wahab, Abdul; Kaleta, Jiří; Wen, Jin; Valášek, Michal; Polášek, Miroslav; Michl, Josef; Ludvík, Jiří

    2016-01-01

    Roč. 55, č. 24 (2016), s. 12815-12821 ISSN 0020-1669 R&D Projects: GA ČR GAP206/11/0727 Institutional support: RVO:61388955 ; RVO:61388963 Keywords : WEAKLY COORDINATING ANIONS * SUBSTITUTION SYMMETRY * CARBORANE ANIONS Subject RIV: CG - Electrochemistry; CA - Inorganic Chemistry (UOCHB-X) Impact factor: 4.857, year: 2016

  13. Measurements of the Lunar Gravity Field using a Relay Subsatellite

    Science.gov (United States)

    Namiki, Noriyuki; Hanada, H.; Kawano, N.; Heki, K.; Iwata, T.; Ogawa, M.; Takano, T.

    1998-01-01

    Space and Astronautical Science (ISAS). Two spacecraft, a main orbiter and a relay subsatellite, constitute the SELENE. The SELENE is scheduled to be launched in 2003. After the SELENE is injected into an elliptical polar orbit of 1 00-km periapsis altitude and 2424-km apoapsis altitude, the relay subsatellite is separated from the main orbiter. Then the main orbiter gradually decreases the eccentricity to a circular orbit in which altitude and inclination are 100 km and 950, respectively. When the mission instruments, including a relay subsatellite transponder for the gravity measurement (RSAT), complete global mapping after a nominal I -year period, the propulsion module of the main orbiter is deorbited to land on the Moon. A differential VLBI experiment by two radio sources on the relay subsatellite and the propulsion module (VRAD-1 and 2) continues until the relay subsatellite will fall on to the lunar surface approximately two months later [6]. RSAT Mission: RSAT is a communication subsystem on the relay subsatellite [7] for four-way Doppler tracking among the main orbiter, the relay subsatellite, and the Usuda Deep Space Center of ISAS (UDSC) [8], as well as two-way range and Doppler measurements, between the relay subsatellite and UDSC (Fig. 1). At the same time, the Tracking and Communication Stations (TACS) of NASDA conduct conventional two-way ranging and Doppler observations of the main orbiter when the main orbiter is visible from Earth.

  14. Switched diversity strategies for dual-hop relaying systems

    KAUST Repository

    Gaaloul, Fakhreddine

    2011-04-29

    This paper investigates the effect of different switched diversity configurations on the implementation complexity and achieved performance of dual-hop amplify-and-forward (AF) relaying networks. A low-complexity model of the relay station is adopted, wherein single-input single-output antenna configuration is employed. Each of the transmitter and the receiver however employs multiple antennas to improve the overall link performance. Single-phase and two-phase based receive switching strategies are investigated assuming optimum first hop signal-to-noise ratio (SNR). Moreover, the simple scheme in which the switched diversity is applied independently over the two hops is studied using tight upper bounds. Thorough performance comparisons and switching thresholds optimization for the aforementioned strategies are presented. Simulation results are also provided to validate the mathematical development and to verify the numerical computations.

  15. Adaptive relaying for ground fault protection of distribution network

    Energy Technology Data Exchange (ETDEWEB)

    Sachdev, M. S.; Sidhu, T. S.; Talukdar, B. K.

    1995-06-01

    In consequence of the increasing complexity of power distribution networks frequent changes in relay settings to achieve effective protection against ground faults is essential. The principal focus of this paper was adaptive relaying which makes use of digital technology and microprocessors to design systems which can provide protection of complex distribution networks under all operating conditions. Specifically, the paper described software modules that were developed to achieve this capability, developed for the City of Saskatoon`s distribution network. The system provides reliable, fast and selective protection of all components of the distribution system by constantly monitoring all the buses and currents in the circuit by substation computers, which are under the control of a central control computer. In addition to adaptive protection, the system can also provide optimal control of feeder loads, transformers, reactors, and capacitors, cold load pick up and reclosing of circuit breakers and reclosers. 2 refs., 8 figs.

  16. Reconfiguration of DNA molecular arrays driven by information relay.

    Science.gov (United States)

    Song, Jie; Li, Zhe; Wang, Pengfei; Meyer, Travis; Mao, Chengde; Ke, Yonggang

    2017-07-28

    Information relay at the molecular level is an essential phenomenon in numerous chemical and biological processes, such as intricate signaling cascades. One key challenge in synthetic molecular self-assembly is to construct artificial structures that imitate these complex behaviors in controllable systems. We demonstrated prescribed, long-range information relay in an artificial molecular array assembled from modular DNA structural units. The dynamic DNA molecular array exhibits transformations with programmable initiation, propagation, and regulation. The transformation of the array can be initiated at selected units and then propagated, without addition of extra triggers, to neighboring units and eventually the entire array. The specific information pathways by which this transformation occurs can be controlled by altering the design of individual units and the arrays. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  17. Feature-Aware Cooperative Relaying for Multiflow Wireless Sensor Networks

    OpenAIRE

    Tao, Ming; Yuan, Huaqiang; Wei, Wenhong; Qu, Chao

    2013-01-01

    Addressing the energy efficiency in data-centric and application-oriented wireless sensor networks is an eternal theme, and in the practical scenarios deployed multiple flows, often a serious problem of collisions among multiple paths caused by the fierce network resource competition directly influences the whole network performance. To address this issue, in terms of the delay sensitivity imposed on the deployed flows, a feature-aware cooperative relay selection scheme is developed by compre...

  18. The tracking and data relay satellite system - An historical perspective

    Science.gov (United States)

    Elwell, Daniel W.; Levine, Allen J.; Harris, David W.

    1992-01-01

    The Tracking and Data Relay Satellite System (TDRSS), NASA's primary communications link between near-earth orbiting spacecraft and the ground, is addressed. The TDRSS supporting elements and their roles are described along with the different phases of the TDRSS life cycle. Users of TDRSS and the extent of support given to them are shown. TDRSS performance is evaluated in terms of availability and service proficiency.

  19. Scalable DeNoise-and-Forward in Bidirectional Relay Networks

    DEFF Research Database (Denmark)

    Sørensen, Jesper Hemming; Krigslund, Rasmus; Popovski, Petar

    2010-01-01

    in order to save transmissions. To ensure decodability at the end-nodes, a priori information about the content of the combined packets must be available. This is gathered during the initial transmissions to the relay. The trade-off between decodability and number of necessary transmissions is analysed...... and simulations show, that S-DNF is able to provide a better trade-off than traditional schemes at high SNR....

  20. Degrees of Freedom of Asymmetrical Multi-Way Relay Networks

    DEFF Research Database (Denmark)

    Sun, Fan; De Carvalho, Elisabeth

    2011-01-01

    In this paper, we introduce an asymmetrical multi-way relay channel where a base station conveys independent symbols to K different users while receiving independent symbols from the users. In this network, user i Shas Mi antennas (i ∈ [1, ..., K]), the base station has Σi=1K Mi antennas and the ...... with a proposed joint multiple access and broadcast precoding design using the signal space alignment concept....

  1. Restrictions on running IRC (Internet Relay Chat) at CERN

    CERN Multimedia

    2005-01-01

    Due to the large number of computer security incidents at CERN where intruders have used IRC (Internet Relay Chat) software to control computers, IRC connections will be blocked in the CERN firewall from 1st February 2005. Personal use of IRC software is not permitted at CERN. Further details of the restrictions on both personal and professional use of IRC are documented at http://cern.ch/security/IRC.

  2. Modified Relay Selection and Circuit Selection for Faster Tor

    OpenAIRE

    Imani, Mohsen; Amirabadi, Mehrdad; Wright, Matthew

    2016-01-01

    Users of the Tor anonymity system suffer from lessthan- ideal performance, in part because circuit building and selection processes are not tuned for speed. In this paper, we examine both the process of selecting among pre-built circuits and the process of selecting the path of relays for use in building new circuits to improve performance while maintaining anonymity. First, we show that having three pre-built circuits available allows the Tor client to identify fast circuits and improves med...

  3. Science Hybrid Orbiter and Lunar Relay (SCHOLR) Architecture and Design

    Science.gov (United States)

    Trase, Kathryn K.; Barch, Rachel A.; Chaney, Ryan E.; Coulter, Rachel A.; Gao, Hui; Huynh, David P.; Iaconis, Nicholas A.; MacMillan, Todd S.; Pitner, Gregory M.; Schwab, Devin T.

    2011-01-01

    Considered both a stepping-stone to deep space and a key to unlocking the mysteries of planetary formation, the Moon offers a unique opportunity for scientific study. Robotic precursor missions are being developed to improve technology and enable new approaches to exploration. Robots, lunar landers, and satellites play significant roles in advancing science and technologies, offering close range and in-situ observations. Science and exploration data gathered from these nodes and a lunar science satellite is intended to support future human expeditions and facilitate future utilization of lunar resources. To attain a global view of lunar science, the nodes will be distributed over the lunar surface, including locations on the far side of the Moon. Given that nodes on the lunar far side do not have direct line-of-sight for Earth communications, the planned presence of such nodes creates the need for a lunar communications relay satellite. Since the communications relay capability would only be required for a small portion of the satellite s orbit, it may be possible to include communication relay components on a science spacecraft. Furthermore, an integrated satellite has the potential to reduce lunar surface mission costs. A SCience Hybrid Orbiter and Lunar Relay (SCHOLR) is proposed to accomplish scientific goals while also supporting the communications needs of landers on the far side of the Moon. User needs and design drivers for the system were derived from the anticipated needs of future robotic and lander missions. Based on these drivers and user requirements, accommodations for communications payload aboard a science spacecraft were developed. A team of interns identified and compared possible SCHOLR architectures. The final SCHOLR architecture was analyzed in terms of orbiter lifetime, lunar surface coverage, size, mass, power, and communications data rates. This paper presents the driving requirements, operational concept, and architecture views for SCHOLR

  4. ATLAS participation to the 36th Annual CERN Relay Race

    CERN Multimedia

    Gagnon, P.

    On May 17, the Annual CERN relay race took place for the 36th time. This is a fun relay race where a team of six runners runs around the CERN site in Meyrin, up and down many hills, to cover the following distances: the first runner runs 1000 m, the second and third runners cover 800 m each, the fourth and fifth runners each have 500 m and finally, the sixth runner covers the last 300 m all the way to the finish line. Each year, serious and occasionnal runners who take this opportunity to make it their only running moment of the year, give it their best to run the 3.9 km loop in times ranging from a mere 10:39.9 for the best team this year to 18:14.3 for the last of the 65 teams that completed the race. Nobody was wasting time at the starting line of the CERN Annual Relay Race. ATLAS was better represented than ever with a record of eight ATLAS teams participating in this race organized by the CERN running club. The names of the ATLAS participants, as well as the team official times are given in the t...

  5. Analysis of channel uncertainty in ARQ relay networks

    Science.gov (United States)

    Khan, Aimal

    2018-01-01

    Several power allocation algorithms for cooperative relay networks are presented in the literature. These contributions assume perfect channel knowledge and capacity achieving codes. However in practice, obtaining the channel state information at a relay or at the destination is an estimation problem and can generally not be error free. The investigation of the power allocation mechanism in a wireless network due to channel imperfections is important because it can severely degrade its performance regarding throughput and bit error rate. In this paper, the impact of imperfect channel state information on the power allocation of an adaptive relay network is investigated. Moreover, a framework including Automatic Repeat reQuest (ARQ) mechanism is provided to make the power allocation mechanism robust against these channel imperfections. For this framework, the end-to-end SNR is calculated considering imperfect channel knowledge using ARQ analytically. The goal is to emphasize the impact of imperfect channel knowledge on the power allocation mechanism. In this paper, the simulation results illustrate the impact of channel uncertainties on the average outage probability, throughput, and consumed sum power for different qualities of channel estimation. It is shown that the presented framework with ARQ is extremely robust against the channel imperfections. PMID:29377904

  6. Mems Electromagnetic Micro Relays Overview and Design Considerations

    Directory of Open Access Journals (Sweden)

    Zuraini Dahari, Thurai Vinay and Dinesh Sood

    2012-10-01

    Full Text Available Miniature electromagnetic relay matrices capable of switching currents up to one ampere range are  widely used in commercial applications such as instrumentation and telecommunication. Traditionally these devices have been fabricated from a number of discrete components, however in recent years the emergence of Micro Electro Mechanical System (MEMS technology has opened up the possibility for batch fabrication of microrelays at much reduced unit cost. While several electromagnetic microrelay designs have been successfully developed and commercialized for use as individual units, development work on electromagnetic microrelay matrices where individual relays can be selectively switched on and off have been fewer and less successful. Due to inherent limitations of the micromachining processes, significant dimensional and material property variations occur among individual relays in a matrix. These variations severely limit the tolerance window and hence the reliability of operation of the device. After reviewing existing designs of electromagnetic microrelays, a set of desirable design features that would make the electromagnetic microrelay more robust are identified.  A novel design incorporating these features is proposed and preliminary results of ANSYS1 simulation studies are presented.Keywords: MEMS, microrelay and electromagnetic

  7. Cognitive relaying and power allocation under channel state uncertainties

    KAUST Repository

    Pandarakkottilil, Ubaidulla

    2013-04-01

    In this paper, we present robust joint relay precoder designs and transceiver power allocations for a cognitive radio network under imperfect channel state information (CSI). The secondary (or cognitive) network consists of a pair of single-antenna transceiver nodes and a non-regenerative two-way relay with multiple antennas which aids the communication process between the transceiver pair. The secondary nodes share the spectrum with a licensed primary user (PU) while guaranteeing that the interference to the PU receiver is maintained below a specified threshold. We consider two robust designs: the first is based on the minimization of the total transmit power of the secondary relay node required to provide the minimum quality of service, measured in terms of mean-square error (MSE) of the transceiver nodes, and the second is based on the minimization of the sum-MSE of the transceiver nodes. The robust designs are based on worst-case optimization and take into account known parameters of the error in the CSI to render the performance immune to the presence of errors in the CSI. Though the original problem is non-convex, we show that the proposed designs can be reformulated as tractable convex optimization problems that can be solved efficiently. We illustrate the performance of the proposed designs through some selected numerical simulations. © 2013 IEEE.

  8. Outage analysis for underlay cognitive networks using incremental regenerative relaying

    KAUST Repository

    Tourki, Kamel

    2013-02-01

    Cooperative relay technology has recently been introduced into cognitive radio (CR) networks to enhance the network capacity, scalability, and reliability of end-to-end communication. In this paper, we investigate an underlay cognitive network where the quality of service (QoS) of the secondary link is maintained by triggering an opportunistic regenerative relaying once it falls under an unacceptable level. Analysis is conducted for two schemes, referred to as the channel-state information (CSI)-based and fault-tolerant schemes, respectively, where different amounts of CSI were considered. We first provide the exact cumulative distribution function (cdf) of the received signal-to-noise ratio (SNR) over each hop with colocated relays. Then, the cdf\\'s are used to determine a very accurate closed-form expression for the outage probability for a transmission rate $R$. In a high-SNR region, a floor of the secondary outage probability occurs, and we derive its corresponding expression. We validate our analysis by showing that the simulation results coincide with our analytical results in Rayleigh fading channels. © 1967-2012 IEEE.

  9. Current organic chemistry

    National Research Council Canada - National Science Library

    1997-01-01

    Provides in depth reviews on current progress in the fields of asymmetric synthesis, organometallic chemistry, bioorganic chemistry, heterocyclic chemistry, natural product chemistry, and analytical...

  10. Anion

    Directory of Open Access Journals (Sweden)

    A. Vadivel Murugan

    2003-01-01

    . Its characterization is investigated by Fourier Transform Infrared Spectroscopy (FT-IR and Scanning Electron Microscopy (SEM. The hybrid material presents predominantly high electronic conductivities of around 2.0 and 7.0 S cm-1 at 300 and 400K respectively.

  11. Nuclear chemistry

    International Nuclear Information System (INIS)

    Vertes, A.; Kiss, I.

    1987-01-01

    This book is an introduction to the application of nuclear science in modern chemistry. The first group of chapters discuss the basic phenomena and concepts of nuclear physics with emphasis on their relation to chemical problems, including the main properties and the composition of atomic nuclei, nuclear reactions, radioactive decay and interactions of radiation with matter. These chapters provide the basis for understanding the following chapters which encompass the wide scope of nuclear chemistry. The methods of the investigation of chemical structure based on the interaction of nuclear radiation with matter including positronium chemistry and other exotic atoms is elaborated in particular detail. Separate chapters are devoted to the use of radioactive tracers, the chemical consequences of nuclear processes (i.e. hot atom chemistry), radiation chemistry, isotope effects and their applications, and the operation of nuclear reactors. (Auth.)

  12. Nuclear chemistry

    International Nuclear Information System (INIS)

    Vertes, A.; Kiss, I.

    1987-01-01

    This book is an introduction to the application of nuclear science in modern chemistry. The first group of chapters discuss the basic phenomena and concepts of nuclear physics with emphasis on their relation to chemical problems, including the main properties and the composition of atomic nuclei, nuclear reactions, radioactive decay and interactions of radiation with matter. These chapters provide the basis for understanding the following chapters which encompass the wide scope of nuclear chemistry. The methods of the investigation of chemical structure based on the interaction of nuclear radiation with matter including positronium chemistry and other exotic atoms is elaborated in particular detail. Separate chapters are devoted to the use of radioactive tracers, the chemical consequences of nuclear processes (i.e. hot atom chemistry), radiation chemistry, isotope effects and their applications, and the operation of nuclear reactors

  13. Commercial grade item (CGI) dedication of MDR relays for nuclear safety related applications

    Science.gov (United States)

    Das, Ranjit K.; Julka, Anil; Modi, Govind

    1994-08-01

    MDR relays manufactured by Potter & Brumfield (P&B) have been used in various safety related applications in commercial nuclear power plants. These include emergency safety features (ESF) actuation systems, emergency core cooling systems (ECCS) actuation, and reactor protection systems. The MDR relays manufactured prior to May 1990 showed signs of generic failure due to corrosion and outgassing of coil varnish. P&B has made design changes to correct these problems in relays manufactured after May 1990. However, P&B does not manufacture the relays under any 10CFR50 Appendix B quality assurance (QA) program. They manufacture the relays under their commercial QA program and supply these as commercial grade items. This necessitates CGI Dedication of these relays for use in nuclear-safety-related applications. This paper presents a CGI dedication program that has been used to dedicate the MDR relays manufactured after been used to dedicate the MDR relays manufactured after May 1990. The program is in compliance with current Nuclear Regulatory Commission (NRC) and Electric Power Research Institute (EPRI) guidelines and applicable industry standards; it specifies the critical characteristics of the relays, provides the tests and analysis required to verify the critical characteristics, the acceptance criteria for the test results, performs source verification to quality P&B for its control of the critical characteristics, and provides documentation. The program provides reasonable assurance that the new MDR relays will perform their intended safety functions.

  14. Linear Processing Design of Amplify-and-Forward Relays for Maximizing the System Throughput

    Directory of Open Access Journals (Sweden)

    Qiang Wang

    2018-01-01

    Full Text Available In this paper, firstly, we study the linear processing of amplify-and-forward (AF relays for the multiple relays multiple users scenario. We regard all relays as one special “relay”, and then the subcarrier pairing, relay selection and channel assignment can be seen as a linear processing of the special “relay”. Under fixed power allocation, the linear processing of AF relays can be regarded as a permutation matrix. Employing the partitioned matrix, we propose an optimal linear processing design for AF relays to find the optimal permutation matrix based on the sorting of the received SNR over the subcarriers from BS to relays and from relays to users, respectively. Then, we prove the optimality of the proposed linear processing scheme. Through the proposed linear processing scheme, we can obtain the optimal subcarrier paring, relay selection and channel assignment under given power allocation in polynomial time. Finally, we propose an iterative algorithm based on the proposed linear processing scheme and Lagrange dual domain method to jointly optimize the joint optimization problem involving the subcarrier paring, relay selection, channel assignment and power allocation. Simulation results illustrate that the proposed algorithm can achieve a perfect performance.

  15. Information-guided transmission in decode-and-forward relaying systems: Spatial exploitation and throughput enhancement

    KAUST Repository

    Yang, Yuli

    2011-07-01

    In addressing the issue of achieving high throughput in half-duplex relay channels, we exploit a concept of information-guided transmission for the network consisting of a source node, a destination node, and multiple half-duplex relay nodes. For further benefiting from multiple relay nodes, the relay-selection patterns are defined as the arbitrary combinations of given relay nodes. By exploiting the difference among the spatial channels states, in each relay-help transmission additional information to be forwarded is mapped onto the index of the active relay-selection pattern besides the basic information mapped onto the traditional constellation, which is forwarded by the relay node(s) in the active relay-selection pattern, so as to enhance the relay throughtput. With iterative decoding, the destination node can achieve a robust detection by decoupling the signals forwarded in different ways. We investigate the proposed scheme considering "decode-and-forward" protocol and establish its achievable transmission rate. The analytical results on capacity behaviors prove the efficiency of the proposed scheme by showing that it achieves better capacity performance than the conventional scheme. © 2011 IEEE.

  16. Optimal transmit power allocation for MIMO two-way cognitive relay networks with multiple relays using AF strategy

    KAUST Repository

    Alsharoa, Ahmad M.

    2014-02-01

    In this letter, we consider a multiple-input multiple-output two-way cognitive radio system under a spectrum sharing scenario, where primary and secondary users operate on the same frequency band. The secondary terminals aims to exchange different messages with each other using multiple relays where each relay employs an amplify-and-forward strategy. The main objective of our work is to maximize the secondary sum rate allowed to share the spectrum with the primary users by respecting a primary user tolerated interference threshold. In this context, we derive an analytical expression of the optimal power allocated to each antenna of the terminals. We then discuss the impact of some system parameters on the performance in the numerical result section. © 2012 IEEE.

  17. Energy-efficient relay selection and optimal power allocation for performance-constrained dual-hop variable-gain AF relaying

    KAUST Repository

    Zafar, Ammar

    2013-12-01

    This paper investigates the energy-efficiency enhancement of a variable-gain dual-hop amplify-and-forward (AF) relay network utilizing selective relaying. The objective is to minimize the total consumed power while keeping the end-to-end signal-to-noise-ratio (SNR) above a certain peak value and satisfying the peak power constraints at the source and relay nodes. To achieve this objective, an optimal relay selection and power allocation strategy is derived by solving the power minimization problem. Numerical results show that the derived optimal strategy enhances the energy-efficiency as compared to a benchmark scheme in which both the source and the selected relay transmit at peak power. © 2013 IEEE.

  18. Decreased anion gap in polyclonal hypergammaglobulinemia.

    Science.gov (United States)

    Qujeq, Durdi; Mohiti, Javad

    2002-02-01

    The anion gap has proved a valuable tool in the diagnosis of various forms of acid-base disorders, although the importance of slight rises in the anion gap remains unclear. The concept of the anion gap is often misunderstood and misapplied. The relationship between gammaglobulins and the serum anion gap has not received much attention except for reports of a narrowing of the gap associated with certain monoclonal immunoglobulin G gammopathies. We present patients with polyclonal gammopathy, the magnitude of which correlated strongly and negatively with the anion gap. The anion gap can be readily calculated from routine laboratory data, and anion gap was calculated as ([Na] +[K])- ([Cl] + [HCO3]). Serum anion gaps were determined in 206 patients with polyclonal hypergammaglobulinemia and 63 healthy subjects. Serum sodium and potassium ions concentration were determined by flame photometry. Serum bicarbonate level was measured as total carbon dioxide content. Serum chloride level was determined by chlorimetric titration with silver ions. All patients with polyclonal hypergammaglobulinemia had a statistically significant reduction in their mean serum anion gaps (6.4 +/- 1.2 mmol/L) when compared with normal control volunteers (15.3 +/- 2.4 mmol/L), p anion gap and gammaglobulins concentration.

  19. Environmental behavior of inorganic anions

    International Nuclear Information System (INIS)

    Garland, T.R.; Cataldo, D.A.; Fellows, R.J.; Wildung, R.E.

    1987-01-01

    Recent efforts have addressed two aspects of anion behavior in the soil/plant system. The first involves evaluation of the gaseous component of the terrestrial iodine cycle in soils and plants. Field analyses of 129 I in soils and vegetation adjacent to a fuels reprocessing facility, which was idle for 10 years prior to the study, indicated that there may be a significant gaseous component to the terrestrial iodine cycle. Soil substrates, including a silt-sand, organic forest soil, quartz sand, and a sterilized soil, were amended with radioiodide, and the rates and quality of the volatile components evaluated

  20. Lowest auto-detachment state of the water anion

    International Nuclear Information System (INIS)

    Houfek, K.; Cizek, M.

    2016-01-01

    Because of the abundance of water in living tissue the reactive low-energy electron collisions with the water molecule represent an important step in the radiation damage of cells. In this paper, the potential energy surface of the ground state of the water anion H 2 O - is carefully mapped using multireference configuration interaction (MRCI) calculations for a large range of molecular geometries. Particular attention is paid to a consistent description of both the O - +H 2 and OH - +H asymptotes and to a relative position of the anion energy to the ground state energy of the neutral molecule. The auto-detachment region, where the anion state crosses to the electronic continuum is identified. The local minimum in the direction of the O - + H 2 channel previously reported by Werner et al. [J. Chem. Phys. 87, 2913 (1987)] is found to be slightly off the linear geometry and is separated by a saddle from the auto-detachment region. The auto-detachment region is directly accessible from the OH - +H asymptote. For the molecular geometries in the auto-detachment region and in its vicinity we also performed fixed-nuclei electron-molecule scattering calculations using the R-matrix method. Tuning of consistency of a description of the correlation energy in both the multireference CI and R-matrix calculations is discussed. Two models of the correlation energy within the R-matrix method that are consistent with the quantum chemistry calculations are found. Both models yield scattering quantities in a close agreement. The results of this work will allow a consistent formulation of the nonlocal resonance model of the water anion in a future publication

  1. Quantum chemistry

    CERN Document Server

    Lowe, John P

    1993-01-01

    Praised for its appealing writing style and clear pedagogy, Lowe's Quantum Chemistry is now available in its Second Edition as a text for senior undergraduate- and graduate-level chemistry students. The book assumes little mathematical or physical sophistication and emphasizes an understanding of the techniques and results of quantum chemistry, thus enabling students to comprehend much of the current chemical literature in which quantum chemical methods or concepts are used as tools. The book begins with a six-chapter introduction of standard one-dimensional systems, the hydrogen atom,

  2. Clinical usefulness of the serum anion gap.

    Science.gov (United States)

    Lee, Sik; Kang, Kyung Pyo; Kang, Sung Kyew

    2006-03-01

    The anion gap in the serum is useful in the interpretation of acid-base disorders and in the diagnosis of other conditions. In the early 1980s, ion-selective electrodes for specific ionic species were introduced for the measurement of serum electrolytes. This new method has caused a shift of the anion gap from 12±4 mEq/L down 6±3 mEq/L. It is worthy for clinicians to understand the range of normal anion gap and the measuring methods for serum sodium and chloride in the laboratories that support their practice. While an increase in the anion gap is almost always caused by retained unmeasured anions, a decrease in the anion gap can be generated by multiple mechanisms.

  3. Application of a macrocyclic compound, bambus[6]uril, in tailor-made liquid membranes for highly selective electromembrane extractions of inorganic anions

    Czech Academy of Sciences Publication Activity Database

    Šlampová, Andrea; Šindelář, V.; Kubáň, Pavel

    2017-01-01

    Roč. 950, JAN (2017), s. 49-56 ISSN 0003-2670 R&D Projects: GA ČR(CZ) GA16-09135S Institutional support: RVO:68081715 Keywords : bambus[6]uril * electromembrane extraction selectivity * inorganic anions Subject RIV: CB - Analytical Chemistry, Separation OBOR OECD: Analytical chemistry Impact factor: 4.950, year: 2016

  4. On the Outage Performance of Full-Duplex Selective Decode-and-Forward Relaying

    KAUST Repository

    Khafagy, Mohammad Galal

    2013-02-25

    We evaluate the outage performance in a three-terminal full-duplex relay channel that adopts a selective decode-and-forward protocol, taking relay self-interference into account. Previous work focused on coverage extension scenarios where direct source-destination transmissions are neglected or considered as interference. In this work, we account for the relay self-interference, and exploit the cooperative diversity offered by the independently fading source/relay message replicas that arrive at the destination. We present an approximate, yet accurate, closed-form expression for the end-to-end outage probability that captures their joint effect. With the derived expression in hand, we propose a relay transmit power optimization scheme that only requires the relay knowledge of channel statistics. Finally, we corroborate our analysis with simulations.

  5. On the benefits of location-based relay selection in mobile wireless networks

    DEFF Research Database (Denmark)

    Nielsen, Jimmy Jessen; Madsen, Tatiana Kozlova; Schwefel, Hans-Peter

    2016-01-01

    . If the relay selection is based on link quality measurements, the number of links to update grows quadratically with the number of nodes, and measurements need to be updated frequently when nodes are mobile. In this paper, we consider a location-based relay selection scheme where link qualities are estimated...... with varying information update interval, node mobility, location inaccuracy, and inaccurate propagation model parameters. Our results show that location-based relay selection performs better than SNR-based relay selection at typical levels of location error when medium-scale fading can be neglected......We consider infrastructure-based mobile networks that are assisted by a single relay transmission where both the downstream destination and relay nodes are mobile. Selecting the optimal transmission path for a destination node requires up-to-date link quality estimates of all relevant links...

  6. Near optimal power allocation algorithm for OFDM-based cognitive using adaptive relaying strategy

    KAUST Repository

    Soury, Hamza

    2012-01-01

    Relayed transmission increases the coverage and achievable capacity of communication systems. Adaptive relaying scheme is a relaying technique by which the benefits of the amplifying or decode and forward techniques can be achieved by switching the forwarding technique according to the quality of the signal. A cognitive Orthogonal Frequency-Division Multiplexing (OFDM) based adaptive relaying protocol is considered in this paper. The objective is to maximize the capacity of the cognitive radio system while ensuring that the interference introduced to the primary user is below the tolerated limit. A Near optimal power allocation in the source and the relay is presented for two pairing techniques such that the matching and random pairing. The simulation results confirm the efficiency of the proposed adaptive relaying protocol, and the consequence of choice of pairing technique. © 2012 ICST.

  7. Throughput maximization for buffer-aided hybrid half-/full-duplex relaying with self-interference

    KAUST Repository

    Khafagy, Mohammad Galal

    2015-06-01

    In this work, we consider a two-hop cooperative setting where a source communicates with a destination through an intermediate relay node with a buffer. Unlike the existing body of work on buffer-aided half-duplex relaying, we consider a hybrid half-/full-duplex relaying scenario with loopback interference in the full-duplex mode. Depending on the channel outage and buffer states that are assumed available at the transmitters, the source and relay may either transmit simultaneously or revert to orthogonal transmission. Specifically, a joint source/relay scheduling and relaying mode selection mechanism is proposed to maximize the end-to-end throughput. The throughput maximization problem is converted to a linear program where the exact global optimal solution is efficiently obtained via standard convex/linear numerical optimization tools. Finally, the theoretical findings are corroborated with event-based simulations to provide the necessary performance validation.

  8. Precoder Design and Power Allocation for MIMO Cognitive Radio Two-Way Relaying Systems

    KAUST Repository

    Sboui, Lokman

    2016-08-11

    In this paper, we study a multiple-antenna two-way relaying (TWR) cognitive radio (CR) system. A space alignment (SA) technique is adopted by the secondary users (SUs) to avoid interference with the primary users (PUs). We derive the optimal power allocation that maximizes the TWR achievable SU sum- rate while respecting the total power budget and the relay power constraints. We also analyze the case in which the relay is able to optimize its gain matrix structure to enhance the SU sum-rate. In the numerical results, we quantify the sum-rate gain of using the SA in the TWR CR and we show that the SU sum-rate is very limited when the relay power is low or the PU power and its resulting interference are high. In addition, we optimize the relay gain using an iterative algorithm and compare between different relay matrix structures.

  9. Performance analysis of selective cooperation with fixed gain relays in Nakagami-m channels

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-09-01

    Selecting the best relay using the maximum signal to noise ratio (SNR) among all the relays ready to cooperate saves system resources and utilizes the available bandwidth more efficiently compared to the regular all-relay cooperation. In this paper, we analyze the performance of the best relay selection scheme with fixed gain relays operating in Nakagami-. m channels. We first derive the probability density function (PDF) of upper bounded end-to-end SNR of the relay link. Using this PDF, we derive some key performance parameters for the system including average bit error probability and average channel capacity. The analytical results are verified through Monte Carlo simulations. © 2012 Elsevier B.V.

  10. Simultaneous Wireless Information and Power Transfer for Decode-and-Forward MIMO Relay Communication Systems

    KAUST Repository

    Benkhelifa, Fatma

    2015-05-01

    In this paper, we investigate the simultaneous wireless information and power transfer (SWIPT) for a decode-and-forward (DF) multiple-input multiple-output (MIMO) relay system where the relay is an energy harvesting node. We consider the ideal scenario where both the energy harvesting (EH) receiver and information decoding (ID) receiver at the relay have access to the whole received signal and its energy. The relay harvests the energy while receiving the signal from the source and uses the harvested power to forward the signal to the destination. We obtain the optimal precoders at the source and the relay to maximize the achievable throughput rate of the overall link. In the numerical results, the effect of the transmit power at the source and the position of the relay between the source and the destination on the maximum achievable rate are investigated. © 2015 IEEE.

  11. Partial relay selection based on shadowing side information over generalized composite fading channels

    KAUST Repository

    Yilmaz, Ferkan

    2011-11-01

    In this paper, in contrast to the relay selection protocols available in the literature, we propose a partial relay selection protocol utilizing only the shadowing side information of the relays instead of their full channel side information in order to select a relay in a dual-hop relaying system through the available limited feedback channels and power budget. We then presented an exact unified performance expression combining the average bit error probability, ergodic capacity, and moments-generating function of the proposed partial relay selection over generalized fading channels. Referring to the unified performance expression introduced in [1], we explicitly offer a generic unified performance expression that can be easily calculated and that is applicable to a wide variety of fading scenarios. Finally, as an illustration of the mathematical formalism, some numerical and simulation results are generated for an extended generalized-K fading environment, and these numerical and simulation results are shown to be in perfect agreement. © 2011 IEEE.

  12. Simultaneous Wireless Information and Power Transfer for MIMO Amplify-and-Forward Relay Systems

    KAUST Repository

    Benkhelifa, Fatma

    2016-01-06

    In this paper, we investigate the simultaneous wireless information and power transfer (SWIPT) for the two-hop Multiple-Input Multiple-Output (MIMO) Amplify-and-Forward (AF) relay communication systems with the multiantenna energy harvesting relay. We derive the optimal source and relay covariance matrices to characterize the achievable region between the sourcedestination rate and the harvested energy at the relay, namely Rate-Energy (R-E) region. In this context, we consider the ideal scenario where the energy harvester (EH) receiver and the information decoder (ID) receiver at the relay can simultaneously decode the information and harvest the energy at the relay. Then, we consider more practical schemes which are the power splitting (PS) and the time switching (TS) which separate the EH and ID transfer over the power domain and the time domain, respectively.

  13. Separations chemistry

    International Nuclear Information System (INIS)

    Anon.

    1976-01-01

    Results of studies on the photochemistry of aqueous Pu solutions and the stability of iodine in liquid and gaseous CO 2 are reported. Progress is reported in studies on: the preparation of macroporous bodies filled with oxides and sulfides to be used as adsorbents; the beneficiation of photographic wastes; the anion exchange adsorption of transition elements from thiosulfate solutions; advanced filtration applications of energy significance; high-resolution separations; and, the examination of the separation agents, octylphenylphosphoric acid (OPPA) and trihexyl phosphate (THP)

  14. Schlenk Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar

    2015-09-01

    Anionic polymerization-high vacuum techniques (HVTs) are doubtlessly the most prominent and reliable experimental tools to prepare polymer samples with well-defined and, in many cases, complex macromolecular architectures. Due to the high demands for time and skilled technical personnel, HVTs are currently used in only a few research laboratories worldwide. Instead, most researchers in this filed are attracted to more facile Schlenk techniques. The basic principle of this technique followed in all laboratories is substantially the same, i.e. the use of alternate vacuum and inert gas atmosphere in glass apparatus for the purification/charging of monomer, solvents, additives, and for the manipulation of air-sensitive compounds such as alkyl metal initiators, organometallic or organic catalysts. However, it is executed quite differently in each research group in terms of the structure of Schlenk apparatus (manifolds, connections, purification/storage flasks, reactors, etc.), the use of small supplementary devices (soft tubing, cannulas, stopcocks, etc.) and experimental procedures. The operational methods are partly purpose-oriented while also featured by a high flexibility, which makes it impossible to describe in detail each specific one. In this chapter we will briefly exemplify the application of Schlenk techniques for anionic polymerization by describing the performance of a few experiments from our own work.

  15. Supramolecular Chemistry

    Indian Academy of Sciences (India)

    antigen interactions. working in different areas such as chemical science, biological science, physical science, material science and so on. On the whole, supramolecular chemistry focuses on two over- lapping areas, 'supramolecules' and ...

  16. Materials Chemistry

    CERN Document Server

    Fahlman, Bradley D

    2011-01-01

    The 2nd edition of Materials Chemistry builds on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field. The 2nd edition continues to offer innovative coverage and practical perspective throughout. After briefly defining materials chemistry and its history, seven chapters discuss solid-state chemistry, metals, semiconducting materials, organic "soft" materials, nanomaterials, and materials characterization. All chapters have been thoroughly updated and expanded with, for example, new sections on ‘soft lithographic’ patterning, ‘click chemistry’ polymerization, nanotoxicity, graphene, as well as many biomaterials applications. The polymer and ‘soft’ materials chapter represents the largest expansion for the 2nd edition. Each ch...

  17. Analytical chemistry

    International Nuclear Information System (INIS)

    Choi, Jae Seong

    1993-02-01

    This book is comprised of nineteen chapters, which describes introduction of analytical chemistry, experimental error and statistics, chemistry equilibrium and solubility, gravimetric analysis with mechanism of precipitation, range and calculation of the result, volume analysis on general principle, sedimentation method on types and titration curve, acid base balance, acid base titration curve, complex and firing reaction, introduction of chemical electro analysis, acid-base titration curve, electrode and potentiometry, electrolysis and conductometry, voltammetry and polarographic spectrophotometry, atomic spectrometry, solvent extraction, chromatograph and experiments.

  18. Green Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Collison, Melanie

    2011-05-15

    Green chemistry is the science of chemistry used in a way that will not use or create hazardous substances. Dr. Rui Resendes is working in this field at GreenCentre Canada, an offshoot of PARTEQ Innovations in Kingston, Ontario. GreenCentre's preliminary findings suggest their licensed product {sup S}witchable Solutions{sup ,} featuring 3 classes of solvents and a surfactant, may be useful in bitumen oil sands extraction.

  19. Analytical chemistry

    Czech Academy of Sciences Publication Activity Database

    Křivánková, Ludmila

    -, č. 22 (2011), s. 718-719 ISSN 1472-3395 Institutional research plan: CEZ:AV0Z40310501 Keywords : analytical chemistry * analytical methods * nanotechnologies Subject RIV: CB - Analytical Chemistry, Separation http://edition.pagesuite-professional.co.uk/launch.aspx?referral=other&pnum=&refresh=M0j83N1cQa91&EID=82bccec1-b05f-46f9-b085-701afc238b42&skip=

  20. Role of acidic chemistries in steam treatment of aluminium alloys

    DEFF Research Database (Denmark)

    Din, Rameez Ud; Jellesen, Morten Stendahl; Ambat, Rajan

    2015-01-01

    The effect of acidic chemistry on the accelerated growth of oxide on aluminium alloys Peraluman 706TM and AA6060 under exposure to high temperature steam was investigated. Studied chemistries were based on citrates and phosphates. Results showed that the presence of citrate and phosphate anions...... initiate doxide growth at the intermetallic particles while growth and corrosion performance of oxide was found tobe a function of anions type and their concentration. Further, steam treatment with phosphates exhibited better performance under acetic acid salt spray and filiform corrosion test whereas...

  1. Energy-Efficient Relay Selection Scheme for Physical Layer Security in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Li Jiang

    2015-01-01

    selection and dynamic power allocation in order to maximize SC and to minimize energy consumption. Moreover, we consider finite-state Markov channels and residual relay energy in the relay selection and power allocation process. Specifically, the formulation of the proposed relay selection and power allocation scheme is based on the restless bandit problem, which is solved by the primal-dual index heuristic algorithm. Additionally, the obtained optimal relay selection policy has an indexability property that dramatically reduces the computational complexity. Numerical results are presented to show that our proposed scheme has the maximum SC and minimum energy consumption compared to the existing ones.

  2. Relay selection in underlay cognitive networks with fixed transmission power nodes

    KAUST Repository

    Hussain, Syed Imtiaz

    2013-07-31

    Underlay cognitive networks operate simultaneously with primary networks satisfying stringent interference constraints, which reduces their transmission power and coverage area. To reach remote destinations, secondary sources use relaying techniques. Selecting the best relay among the available ones is a well known technique. Recently, selective cooperation is investigated in cognitive networks where the secondary nodes can adapt their transmission power to always satisfy the interference threshold. In this paper, we investigate a situation where the secondary nodes have a fixed transmission power and may violate the interference threshold. We present two relay selection schemes; the first one excludes the relays not satisfying the interference constraint and then picks up a relay from the remaining ones that can provide the maximum signal-to-noise ratio (SNR). The other scheme uses a quotient of the relay link SNR and the interference from the relay to the primary user and optimizes it to maximise the relay link SNR. We derive closed form expressions for outage probability, bit error rate, channel capacity and diversity of the system for both schemes by using tight approximations. We also study mutual effects of interference. Simulation results confirm the analytical results and reveal that the relay selection is feasible at low SNRs. Copyright © 2013 John Wiley & Sons, Ltd.

  3. New resource allocation scheme for cognitive relay networks with opportunistic access

    KAUST Repository

    Zafar, Ammar

    2012-06-01

    In this paper, a new resource allocation scheme to minimize Symbol Error rate (SER) for relay assisted cognitive radio networks is studied. A cognitive relay network with amplify-and-forward (AF) fixed gain relays and opportunistic access to the licensed spectrum is considered. The SER objective function and the optimization constraints are derived first. The resource allocation algorithm is then derived using the Langrangian multiplier method. Closed form expressions are derived for the source and relay powers and, symbol time. Analytical results show that the optimal power allocation follows an extended water-filling solution. © 2012 IEEE.

  4. Performance of hybrid-ARQ with incremental redundancy over relay channels

    KAUST Repository

    Chelli, Ali

    2012-12-01

    In this paper, we consider a relay network consisting of a source, a relay, and a destination. The source transmits a message to the destination using hybrid automatic repeat request (HARQ) with incremental redundancy (IR). The relay overhears the transmitted messages over the different HARQ rounds and tries to decode the data packet. In case of successful decoding at the relay, both the relay and the source cooperate to transmit the message to the destination. A maximum number M of HARQ rounds is considered. The channel realizations are independent for different HARQ rounds. We assume Rayleigh fading channels for the links source-relay, source-destination, and relay-destination. We investigate the performance of HARQ-IR over relay channel from an information theoretic perspective. Analytical expressions are derived for the information outage probability, the average number of transmissions, and the average transmission rate. We illustrate through our investigation the benefit of relaying. We also show the impact of the target outage probability and the maximum number M of HARQ rounds on the outage probability, the average number of transmissions, and the average transmission rate. © 2012 IEEE.

  5. Full-Duplex opportunistic relay selection in future spectrum-sharing networks

    KAUST Repository

    Khafagy, Mohammad Galal

    2015-06-01

    We propose and analyze the performance of full-duplex relay selection in primary/secondary spectrum-sharing networks. Contrary to half-duplex relaying, full-duplex relaying (FDR) enables simultaneous listening/forwarding at the secondary relay, thereby allowing for a higher spectral efficiency. However, since the source and relay simultaneously transmit in FDR, their superimposed signal at the primary receiver should now satisfy the existing interference constraint which can considerably limit the secondary network throughput. In this regard, relay selection can offer an adequate solution to boost the secondary throughput while satisfying the imposed interference limit. We first analyze the performance of opportunistic relay selection among a cluster of full-duplex decode-and-forward relays with self-interference by deriving the exact cumulative distribution function of its end-to-end signal-to-noise ratio. Second, we evaluate the end-to-end performance of relay selection with interference constraints due to the presence of a primary receiver. Finally, the presented exact theoretical findings are verified by numerical simulations.

  6. Susceptibility of modern relay protection: Will protection from cyber attacks help?

    Directory of Open Access Journals (Sweden)

    Gurevich Vladimir

    2014-01-01

    Full Text Available Modern trends in relay protection (RP based on the substitution of electromechanical protection relays (EMPR by digital protective relays (DPR have resulted in the emergence of an absolutely new problem, which was not known before. This problem is the possibility of an intentional remote destructive impact (IRDI on relay protection in order to put it out of action or make it perform functions that have nothing to do with the current operational mode of protected electric equipment. Traditional and well-known methods ensuring information safety cannot fully prevent unauthorized actions of RP. The article describes a new way for the problem solution.

  7. A cooperative MAC protocol with error-aware relay selection for wireless ad hoc networks

    Science.gov (United States)

    Liu, Shanzhi; Liu, Kai; Wang, Rui; Fang, Ruochen; Liu, Feng

    2017-01-01

    To solve performance degradation caused by channel fading, we propose a cooperative MAC protocol with error-aware relay selection for wireless ad hoc networks in this paper. In the protocol, the transmission error of data packet caused by channel fading are considered in order to achieve the best cooperative gain in the poor quality channel. In the relay selection process, potential relay nodes satisfying corresponding requirement can compete to sever as final relay node by means of priority selection and collision resolution process. Finally, simulation results show that the proposed protocol outperforms other protocol in terms of packet error rate and the saturation throughput.

  8. Low Complexity Transmission Scheme with Full Diversity for Two-Path Relay Networks

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-01-06

    In this work, we present a new low complexity scheme for two-path relay network to harvest maximum achievable diversity. We analyze the performance of the newly proposed two-path relay network by calculating the symbol error rate (SER) for arbitrary location of relays. It is shown that with this newly proposed scheme, two-path relay networks can mimic a 2x2 multiple-input mulitple-output (MIMO) system and achieve full diversity order of four. Simulations results are provided to verify and illustrate the analytical results.

  9. Toward distributed relay selection for opportunistic amplify-and-forward transmission

    KAUST Repository

    Tourki, Kamel

    2011-05-01

    Opportunistic relaying in cooperative communication depends on careful relay selection. However the traditional centralized method used for opportunistic Amplify-and-Forward (OAF) protocols requires precise measurements of channel state information (CSI) at the destination (CSI-OAF). In this paper, we propose a distributed relay selection framework for opportunistic AF (D-OAF) cooperative communications and offer an accurate performance analysis based on exact statistics of the local signalto- noise ratios of the best relay. Furthermore, we validate our analysis by showing that performance simulation results coincide with our analytical results over different network architectures, and we compare our new results with their CSI-based counterparts. © 2011 IEEE.

  10. Persistence of Li–Yorke chaos in systems with relay

    Directory of Open Access Journals (Sweden)

    Marat Akhmet

    2017-10-01

    Full Text Available It is rigorously proved that the chaotic dynamics of the non-smooth system with relay function is persistent even if a chaotic perturbation is applied. We consider chaos in a modified Li–Yorke sense such that there are infinitely many almost periodic motions embedded in the chaotic attractor. It is demonstrated that the system under investigation possesses countable infinity of chaotic sets of solutions. An example that supports the theoretical results is represented. Moreover, a chaos control procedure based on the Ott–Grebogi–Yorke algorithm is proposed to stabilize the unstable almost periodic motions.

  11. Minimizing Symbol Error Rate for Cognitive Relaying with Opportunistic Access

    KAUST Repository

    Zafar, Ammar

    2012-12-29

    In this paper, we present an optimal resource allocation scheme (ORA) for an all-participate(AP) cognitive relay network that minimizes the symbol error rate (SER). The SER is derived and different constraints are considered on the system. We consider the cases of both individual and global power constraints, individual constraints only and global constraints only. Numerical results show that the ORA scheme outperforms the schemes with direct link only and uniform power allocation (UPA) in terms of minimizing the SER for all three cases of different constraints. Numerical results also show that the individual constraints only case provides the best performance at large signal-to-noise-ratio (SNR).

  12. Terrain dependant hop count selection for transparent relay transmissions

    Directory of Open Access Journals (Sweden)

    Cibile K. Kanjirathumkal

    2013-12-01

    Full Text Available In this Letter, the selection of the best hop count for a particular topography, in the context of enhanced connectivity using multi-hop transparent relay communication is addressed. Based on the coefficient of variation and the terrain specific fading severity factor of the distribution, it is possible to estimate the optimal hop count that can provide the required performance at detector. Two distribution models, which can adequately characterise the terrain fading effects on empirical data are considered for performance comparison. The results are useful in selecting branches, with low variability and optimal hop count for connectivity, in multi-stream switched diversity combining systems.

  13. Four-Way Relaying in Wireless Cellular Systems

    DEFF Research Database (Denmark)

    Liu, Huaping; Popovski, Petar; De Carvalho, Elisabeth

    2013-01-01

    of the new scheme for Decode-and-Forward (DF) operational model for the RS. We compare the performance with a state-of-the-art reference scheme, based on two-way relaying with DF. The results indicate that the achievable rate regions are significantly enlarged for the new scheme....... and the terminals associated with it do not interfere with the other RS, and vice versa. We introduce and analyze a two-phase transmission scheme to serve the four-way traffic pattern defined in this scenario. Each phase consists of combined broadcast and multiple access. We analyze the achievable rate region...

  14. Is a Multi-Hop Relay Scheme Gainful in an IEEE 802.22-Based Cognitive Radio System?

    Science.gov (United States)

    Shin, Jungchae; Lee, Dong-Kyu; Cho, Ho-Shin

    In this paper, we formulate a plan to operate multi-hop relays in IEEE 802.22-based cognitive radio (CR) systems and evaluate system performance to consider the propriety of a multi-hop relay scheme in CR systems. A centralized radio resource management and a simple deployment of relay stations (RSs) are assessed to make relay operations feasible under CR conditions. Simulation results show that the proposed multi-hop relay scheme significantly increases system throughput compared to a no-relay CR system as the incumbent user (IU) traffic gets heavier. Furthermore, the optimal number of hops can be determined given the traffic conditions.

  15. Asymmetric Anion-π Catalysis: Enamine Addition to Nitroolefins on π-Acidic Surfaces.

    Science.gov (United States)

    Zhao, Yingjie; Cotelle, Yoann; Avestro, Alyssa-Jennifer; Sakai, Naomi; Matile, Stefan

    2015-09-16

    Here we provide experimental evidence for anion-π catalysis of enamine chemistry and for asymmetric anion-π catalysis. A proline for enamine formation on one side and a glutamic acid for nitronate protonation on the other side are placed to make the enamine addition to nitroolefins occur on the aromatic surface of π-acidic naphthalenediimides. With increasing π acidity of the formally trifunctional catalysts, rate and enantioselectivity of the reaction increase. Mismatched and more flexible controls reveal that the importance of rigidified, precisely sculpted architectures increases with increasing π acidity as well. The absolute configuration of stereogenic sulfoxide acceptors at the edge of the π-acidic surface has a profound influence on asymmetric anion-π catalysis and, if perfectly matched, affords the highest enantio- and diastereoselectivity.

  16. ANIONS FUNCTIONS IN TRANSITION METALS COORDINATION COMPOUNDS

    Directory of Open Access Journals (Sweden)

    T. V. Koksharova

    2016-04-01

    Full Text Available The effect of anions on the structure and properties of coordination compounds of transition metals has been discussed. The examples of changes in the composition of the formed complexes by replacement of the anion are given: metal ratio to a neutral ligand, the composition of the inner sphere, the direction of template synthesis. Anions can determine the presence of isomers in complexes with different ligands. Examples of conformational, ionization isomerism, inner sphere bond isomerization are given. The nature of the coordination polyhedron is highly sensitive to the replacement of the anion too. Examples of coordination compounds where the anion change causes a change in coordination capacity of neutral ligands and the strength of their bonds with the metal, coordination number and geometry of the inner sphere, the organization of molecular structures (the structure of the hydrogen bond networks and the degree of polymerization, crystal packing. The anions significantly affect the binding of the solvent molecules, complexes magnetic and luminescent properties, they can change the compound color, the mechanisms of thermolysis. Anions make a very noticeable influence on possible redox processes following the complexation in some cases. Anions in the coordination sphere can change catalytic and biochemical processes as well as the ways of interaction of metal ions with drugs.

  17. The many ways of making anionic clays

    Indian Academy of Sciences (India)

    Unknown

    Indian Academy of Sciences. 671. The many ways of making anionic ... In all these cases, the negative charge is compensated for by the inclusion of positive ions in the interlayer region, by virtue ..... as anionic clays. Acknowledgements. The authors thank the Department of Science and Technology, New Delhi for financial.

  18. Test procedure for anion exchange chromatography

    International Nuclear Information System (INIS)

    Cooper, T.D.

    1994-01-01

    Plutonium from stored nitrate solutions will be sorbed onto anion exchange resins and converted to storable plutonium dioxide. Useful information will be simultaneously gained on the thermal stability and ion exchange capacity of four commercially available anion exchange resins over several years and under severe degradative conditions. This information will prove useful in predicting the safe and efficient lifetimes of these resins

  19. Hydrogen in anion vacancies of semiconductors

    Science.gov (United States)

    Du, Mao-Hua; Singh, David

    2009-03-01

    Hydrogen typically terminates the dangling bonds around vacancies in semiconductors, thereby, partially or completely passivating the vacancies. However, it has been shown recently that hydrogen in anion vacancies of many semiconductors, such as ZnO, MgO, InN, SnO2, and GaN, takes multi-coordinated structures and acts as shallow donors, providing n-type conductivity to the materials. We study the hydrogen in the anion vacancies of a series of II-VI and III-V semiconductors using density functional calculations. The results on these materials show that, in the anion vacancies of polar II-VI semiconductors, the hydrogen is usually anionic and is coordinated with more than one cation atoms as a result of the relatively high ionicity of the host materials. The hydrogen coordination number depends on the host anion size. On the other hand, in more covalent semiconductors such as some III-V semiconductors, the single cation-H bonding configuration may become most stable. In the anion vacancies of ZnX and CdX where X represents anions, hydrogen is typically amphoteric except for oxides, in which the small anion size prohibits the formation of the cation-cation bond that is required for the acceptor configuration.

  20. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.

    2003-01-01

    Polypyrrole (PPy) polymer films permanently doped with large, immobile anion dodecyl benzene sulfonate (DBS) have been characterized by cyclic voltammetry in order to clarify the roles of cations and anions in the aqueous electrolyte as mobile ions in the film. Aqueous solutions of 0.05-0.1 M...

  1. MECHANICAL PARAMETERS CONTROL OF THE NEUTRAL RELAY OF RAIL AUTOMATICS BASED ON WAVELET ANALYSIS

    Directory of Open Access Journals (Sweden)

    V. I. Havryliuk

    2016-12-01

    Full Text Available Purpose. The scientific paper focuses on development of a method for mechanical parameters control of the neutral relay of rail automatics by current analyzing in the coil and the relay contacts at switching based on wavelet transform. Methodology. The methodology was based on current analysis of the relay coil and contacts currents under its switching and analysis obtained results by using wavelet transform. Findings. The time dependences of the current in coil and in contacts under switching on and off for the operable relays and relays with certain defects have been measured at different voltages applied to coil (10, 12 и 14 V. When voltage applied to coil was increased the rate of coil current increased, but time constant of the circuit was changed with voltage slightly. The current value maximum at which the relay armature begun to move for the operable relays was depended on applied voltage slightly. For the time interval, at which armature was putted to the relay core fully, time constant of the circuit was changed with voltage slightly also. The maximum current value at which the armature starts to move to the relay serviceable little dependent on the applied voltage. For site based in which the anchor is completely dragged constant current rise time is also a little dependent on the applied voltage. Similar results were obtained for the current reduction time constant with turning off the voltage and current confinement. The current pick-up and the current release of the armature increases for the relay with the load anchor is proportional to the weight of cargo, as well as for the relay contact with the rear, bent down, while the flexural rear contact up these currents have smaller values. Large-scale (low-frequency coefficients of DWT can be used for a more accurate comparison of the current pick-up, and release time constants of the transient. Small scale coefficients fiberboard (HF can be used as distinguishing traits defects

  2. Electrolyte chemistry control in electrodialysis processing

    Science.gov (United States)

    Hayes, Thomas D.; Severin, Blaine F.

    2017-12-26

    Methods for controlling electrolyte chemistry in electrodialysis units having an anode and a cathode each in an electrolyte of a selected concentration and a membrane stack disposed therebetween. The membrane stack includes pairs of cationic selective and anionic membranes to segregate increasingly dilute salts streams from concentrated salts stream. Electrolyte chemistry control is via use of at least one of following techniques: a single calcium exclusionary cationic selective membrane at a cathode cell boundary, an exclusionary membrane configured as a hydraulically isolated scavenger cell, a multivalent scavenger co-electrolyte and combinations thereof.

  3. Relay discovery and selection for large-scale P2P streaming.

    Directory of Open Access Journals (Sweden)

    Chengwei Zhang

    Full Text Available In peer-to-peer networks, application relays have been commonly used to provide various networking services. The service performance often improves significantly if a relay is selected appropriately based on its network location. In this paper, we studied the location-aware relay discovery and selection problem for large-scale P2P streaming networks. In these large-scale and dynamic overlays, it incurs significant communication and computation cost to discover a sufficiently large relay candidate set and further to select one relay with good performance. The network location can be measured directly or indirectly with the tradeoffs between timeliness, overhead and accuracy. Based on a measurement study and the associated error analysis, we demonstrate that indirect measurements, such as King and Internet Coordinate Systems (ICS, can only achieve a coarse estimation of peers' network location and those methods based on pure indirect measurements cannot lead to a good relay selection. We also demonstrate that there exists significant error amplification of the commonly used "best-out-of-K" selection methodology using three RTT data sets publicly available. We propose a two-phase approach to achieve efficient relay discovery and accurate relay selection. Indirect measurements are used to narrow down a small number of high-quality relay candidates and the final relay selection is refined based on direct probing. This two-phase approach enjoys an efficient implementation using the Distributed-Hash-Table (DHT. When the DHT is constructed, the node keys carry the location information and they are generated scalably using indirect measurements, such as the ICS coordinates. The relay discovery is achieved efficiently utilizing the DHT-based search. We evaluated various aspects of this DHT-based approach, including the DHT indexing procedure, key generation under peer churn and message costs.

  4. Fungal growth on anion surfactant medium.

    Science.gov (United States)

    Hamada, Nobuo; Abe, Niichiro

    2009-12-01

    Before the present study, no fungi using anion surfactant as a nutrient had been identified, although some fungi were known to use nonion surfactant. Washing water collected from 63 washing machines was inoculated onto 0.1% LAS (Sodium dodecyl benzenesulfonate) anion surfactant media to identify fungi that can feed on anion-surfactant. Small dark colonies of fungi were found on several of the Petri-dishes from 12 days after inoculation. These were identified as Cladophialophora boppii and Exophiala spinifera using morphological features and rDNA data. A number of the isolates of C. boppii specifically were recognized as using anion surfactant as a nutrient. The growth characteristics of the two fungal species were examined on surfactant media of three kinds. Apart from anion surfactant, the fungi were also able to grow on nonion surfactant and on soap. The application of these fungi for environmental cleansing after detergent pollution is also discussed.

  5. Closing the gap on unmeasured anions

    Science.gov (United States)

    Kellum, John A

    2003-01-01

    Many critically ill and injured patients, especially those with metabolic acidosis, have abnormally high levels of unmeasured anions in their blood. At the same time, such patients are prone to hypoalbuminemia, which makes the traditional anion gap calculation inaccurate. Thus, little is known about the epidemiology and clinical consequences of an excess in unmeasured anions in the blood. Indeed, even the etiology of these "missing ions" is often unclear. Unfortunately, more precise means of quantifying unmeasured anions, such as the strong ion gap (SIG), are cumbersome to use clinically. However, a simple means of correcting the anion gap can be used to estimate SIG and may provide additional insight into this common clinical problem. PMID:12793870

  6. Cardiorespiratory strain of a five day jogging relay.

    Science.gov (United States)

    Oksa, J; Rissanen, S; Martikkala, V

    1995-01-01

    The heart rates of 14 voluntary subjects (seven male and seven females) participating in a 5 d jogging relay were recorded. The jogging speed was controlled at 3.0 m.s-1 on average. The heart rate measurements were related to cardiorespiratory responses obtained during VO2max test on a treadmill. The mean (s.d.) VO2max values were 53(2) and 48(2) ml.kg-1.min-1 and the anaerobic threshold was 42(1) and 38(2) ml.kg-1.min-1 for male and female subjects respectively. During the relay the mean(s.d) heart rate values of male and female subjects were 150(1), and 167(3) beats.min-1 (P jogging time above anaerobic threshold heart rate level was 9(3)% for the males and 43(7)% for the females (P jogging time. The results indicate that even in a leisure oriented jogging event, cardiorespiratory strain can be rather high and that the strain can be significantly higher for female than for male subjects. The determination of the anaerobic threshold as well as VO2max is important when quantifying the level of cardiorespiratory strain of exercise. PMID:8800848

  7. Mars Relay Spacecraft: A Low-Cost Approach

    Science.gov (United States)

    SvitekT, .; King, J.; Fulton, R.; McOmber, R.; Hastrup, R.; Miller, A.

    1995-01-01

    The next phase of Mars exploration will utilize numerous globally distributed small low-cost devices including landers penetrators microrovers and balloons. Direct-to-Earth communications links if required for these landers will drive the lander design for two reasons: a) mass and complexity needed for a steerable high-gain antenna and b) power requirements for a high-power amplifier (i.e. solar panel and battery mass). Total mass of the direct link hardware for several recent small-lander designs exceeded the mass of the scientific payload. Alternatively if communications are via a Mars-orbiting relay spacecraft resource requirements for the local UHF communication link are comparatively trivial: a simple whip antenna and less than 1 watt power. Clearly using a Mars relay spacecraft (MRS) is the preferred option if the MRS mission can be accomplished in an affordable and robust way. Our paper describes a point design for such a mission launched in the s001 or 2003 opportunity.

  8. Polar On-Line Acquisition Relay and Transmission System (POLARATS)

    Energy Technology Data Exchange (ETDEWEB)

    Yuracko, K.

    2004-07-15

    POLARATS (Polar On-Line Acquisition Relay And Transmission System) is being developed by YAHSGS LLC (YAHSGS) and Oak Ridge National Laboratory (ORNL) to provide remote, unattended monitoring of environmental parameters under harsh environmental conditions. In particular, instrumental design and engineering is oriented towards protection of human health in the Arctic, and with the additional goal of advancing Arctic education and research. POLARATS will obtain and transmit environmental data from hardened monitoring devices deployed in locations important to understanding atmospheric and aquatic pollutant migration as it is biomagnified in Arctic food chains. An Internet- and personal computer (PC)-based educational module will provide real time sensor data, on-line educational content, and will be integrated with workbooks and textbooks for use in middle and high school science programs. The educational elements of POLARATS include an Internet-based educational module that will instruct students in the use of the data and how those data fit into changing Arctic environments and food chains. POLARATS will: (1) Enable students, members of the community, and scientific researchers to monitor local environmental conditions in real time over the Internet; and (2) Provide additional educational benefits through integration with middle- and high-school science curricula. Information will be relayed from POLARATS devices to classrooms and libraries along with custom-designed POLARATS teaching materials that will be integrated into existing curricula to enhance the educational benefits realized from the information obtained.

  9. Speed of light exceeded in 31st CERN Relay

    CERN Multimedia

    2001-01-01

    In the closest-ever finish of the CERN relay race, Florian Marinet (number 54) of the Neutrinos to Gran Sasso team just fails to catch Pierre Maesen of The Shabbys on the line. The AThLetic AceS team (number 76) won the Veterans category by just 3 seconds from long-time participants The Lynx Runners, who didn't leave empty handed. They picked up the cup that is drawn at random. Evidence for new physics? No, simply evidence for faster legs. Only at CERN could the speed of light come third to a team called The Shabbys. But that's exactly what happened on Wednesday 23 May when the team from PS Division lifted the Opitz cup after winning the 31st CERN relay race. The Shabbys sped home in 10 minutes 53 seconds, just 0.3 of a second ahead of the 'Neutrinos to Gran Sasso' team. There's some logic there since it is the PS complex that will provide the protons that will give rise to the neutrino beam. As for 'c0 the speed of light', they took a relatively leisurely 11 minutes 1.6 seconds to cover the course. A total...

  10. CERN Relay Race: No records broken in a bumper year

    CERN Multimedia

    2007-01-01

    Tribute is paid to David Dallman, 20 times the organiser of the CERN Relay Race, who is now retiring.Solve the following mathematical problem for athletes: take the first and third-placed teams in the 2006 CERN Relay Race, randomly mix the runners to form two new teams, and what is the result? Answer: first place and fifth place. In short, the team which has reigned supreme in first place since 2001, the "Shabbys", decided to spice up the race this year by merging with their arch rivals, the "Latinos Volantes", themselves no strangers to the podium. And at the winning line, it was the hybrid formation, "Shabbys Volantes", which took the honours (no surprises there!). Sadly, they were unable to beat the Shabbys’ previous record nor get anywhere near the all-time race record of 10 minutes and 13 seconds for the 3.9-km course, held for a quarter of a century by the "UA1 Strollers". One of the members of that legendary team and race organiser 20 times, David Dallman, mar...

  11. Half-Duplex and Full-Duplex AF and DF Relaying with Energy-Harvesting in Log-Normal Fading

    KAUST Repository

    Rabie, Khaled M.

    2017-08-15

    Energy-harvesting (EH) and wireless power transfer in cooperative relaying networks have recently attracted a considerable amount of research attention. Most of the existing work on this topic however focuses on Rayleigh fading channels, which represent outdoor environments. In contrast, this paper is dedicated to analyze the performance of dual-hop relaying systems with EH over indoor channels characterized by log-normal fading. Both half-duplex (HD) and full-duplex (FD) relaying mechanisms are studied in this work with decode-and-forward (DF) and amplify-and-forward (AF) relaying protocols. In addition, three EH schemes are investigated, namely, time switching relaying, power splitting relaying and ideal relaying receiver which serves as a lower bound. The system performance is evaluated in terms of the ergodic outage probability for which we derive accurate analytical expressions. Monte Carlo simulations are provided throughout to validate the accuracy of our analysis. Results reveal that, in both HD and FD scenarios, AF relaying performs only slightly worse than DF relaying which can make the former a more efficient solution when the processing energy cost at the DF relay is taken into account. It is also shown that FD relaying systems can generally outperform HD relaying schemes as long as the loop-back interference in FD is relatively small. Furthermore, increasing the variance of the log-normal channel has shown to deteriorate the performance in all the relaying and EH protocols considered.

  12. Circumstellar chemistry

    International Nuclear Information System (INIS)

    Glassgold, A.E.

    1989-01-01

    Circumstellar chemistry has a special role in astrochemistry because the astrophysical conditions in the circumstellar envelopes of red giants are frequently well known and clear tests of chemical models are feasible. Recent advances in astronomical observations now offer opportunities to test relevant theories of molecule formation, especially in carbon-rich environments. Many new molecules have recently been discovered using radio and infrared techniques and high spatial resolution maps obtained with large telescopes and interferometers indicate where complex molecules are being formed in these envelopes. A large body of observational data can be understood in terms of the photochemical model, which embraces relevant elements of equilibrium chemistry, photodissociation, and ion-molecule chemistry of the photo-products. A critical review of the photochemical model will be presented together with new results on the synthesis of hydrocarbon molecules and silicon and sulfur compounds

  13. Polymer Chemistry

    Science.gov (United States)

    Williams, Martha; Roberson, Luke; Caraccio, Anne

    2010-01-01

    This viewgraph presentation describes new technologies in polymer and material chemistry that benefits NASA programs and missions. The topics include: 1) What are Polymers?; 2) History of Polymer Chemistry; 3) Composites/Materials Development at KSC; 4) Why Wiring; 5) Next Generation Wiring Materials; 6) Wire System Materials and Integration; 7) Self-Healing Wire Repair; 8) Smart Wiring Summary; 9) Fire and Polymers; 10) Aerogel Technology; 11) Aerogel Composites; 12) Aerogels for Oil Remediation; 13) KSC's Solution; 14) Chemochromic Hydrogen Sensors; 15) STS-130 and 131 Operations; 16) HyperPigment; 17) Antimicrobial Materials; 18) Conductive Inks Formulations for Multiple Applications; and 19) Testing and Processing Equipment.

  14. Indoor Chemistry

    DEFF Research Database (Denmark)

    Weschler, Charles J.; Carslaw, Nicola

    2018-01-01

    This review aims to encapsulate the importance, ubiquity, and complexity of indoor chemistry. We discuss the many sources of indoor air pollutants and summarize their chemical reactions in the air and on surfaces. We also summarize some of the known impacts of human occupants, who act as sources...... and sinks of indoor chemicals, and whose activities (e.g., cooking, cleaning, smoking) can lead to extremely high pollutant concentrations. As we begin to use increasingly sensitive and selective instrumentation indoors, we are learning more about chemistry in this relatively understudied environment....

  15. General chemistry

    International Nuclear Information System (INIS)

    Kwon, Yeong Sik; Lee, Dong Seop; Ryu, Haung Ryong; Jang, Cheol Hyeon; Choi, Bong Jong; Choi, Sang Won

    1993-07-01

    The book concentrates on the latest general chemistry, which is divided int twenty-three chapters. It deals with basic conception and stoichiometry, nature of gas, structure of atoms, quantum mechanics, symbol and structure of an electron of ion and molecule, chemical thermodynamics, nature of solid, change of state and liquid, properties of solution, chemical equilibrium, solution and acid-base, equilibrium of aqueous solution, electrochemistry, chemical reaction speed, molecule spectroscopy, hydrogen, oxygen and water, metallic atom; 1A, IIA, IIIA, carbon and atom IVA, nonmetal atom and an inert gas, transition metals, lanthanons, and actinoids, nuclear properties and radioactivity, biochemistry and environment chemistry.

  16. Anion Gap Blood Test: MedlinePlus Lab Test Information

    Science.gov (United States)

    ... https://medlineplus.gov/labtests/aniongapbloodtest.html Anion Gap Blood Test To use the sharing features on this page, please enable JavaScript. What is an Anion Gap Blood Test? An anion gap blood test is a way ...

  17. Anionic polymerization of acrylates. XIV. Synthesis of MMA/acrylate block copolymers initiated with ester-enolate/tert-alkoxide complex

    Czech Academy of Sciences Publication Activity Database

    Vlček, Petr; Čadová, Eva; Kříž, Jaroslav; Látalová, Petra; Janata, Miroslav; Toman, Luděk; Masař, Bohumil

    2005-01-01

    Roč. 46, č. 14 (2005), s. 4991-5000 ISSN 0032-3861 Institutional research plan: CEZ:AV0Z4050913 Keywords : ligated anionic polymerization * (meth)acrylates * block copolymers Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.849, year: 2005

  18. Secure amplify-and-forward untrusted relaying networks using cooperative jamming and zero-forcing cancelation

    KAUST Repository

    Park, Kihong

    2015-12-03

    In this paper, we investigate secure transmission in untrusted amplify-and-forward half-duplex relaying networks with the help of cooperative jamming at the destination (CJD). Under the assumption of full channel state information (CSI), conventional CJD using self-interference cancelation at the destination is efficient when the untrusted relay has no capability to suppress the jamming signal. However, if the source and destination are equipped with a single antenna and the only untrusted relay is equipped with N multiple antennas, it can remove the jamming signal from the received signal by linear filters and the full multiplexing gain of relaying cannot be achievable with the conventional CJD due to the saturation of the secrecy rate at the high transmit power regime. We propose in this paper new CJD scheme where neither destination nor relay can acquire CSI of relay-destination link. Our proposed scheme utilizes zero-forcing cancelation based on known jamming signals instead of self-interference subtraction, while the untrusted relay cannot suppress the jamming signals due to the lack of CSI. We show that the secrecy rate of the proposed scheme can enjoy a half of multiplexing gain in half-duplex relaying while that of conventional CJD is saturated at high transmit power for N ???2. The impact of channel estimation error at the destination is also investigated to show the robustness of the proposed scheme against strong estimation errors.

  19. Formal Development of a Tool for Automated Modelling and Verification of Relay Interlocking Systems

    DEFF Research Database (Denmark)

    Haxthausen, Anne Elisabeth; Kjær, Andreas A.; Le Bliguet, Marie

    2011-01-01

    This paper describes a tool for formal modelling relay interlocking systems and explains how it has been stepwise, formally developed using the RAISE method. The developed tool takes the circuit diagrams of a relay interlocking system as input and gives as result a state transition system modelling...

  20. Improved Relay Node Placement Algorithm for Wireless Sensor Networks Application in Wind Farm

    DEFF Research Database (Denmark)

    Chen, Qinyin; Hu, Y.; Chen, Zhe

    2013-01-01

    -tolerance. Each wind turbine has a potentially large number of data points needing to be monitored and collected, as farms continue to increase in scale; distances between turbines can reach several hundred meters. Optimal placement of relays in a large farm requires an efficient algorithmic solution. A relay...

  1. Diversity-Multiplexing Trade-off for Coordinated Direct and Relay Schemes

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar; De Carvalho, Elisabeth

    2013-01-01

    Direct/Relay (CDR) schemes, which involve two flows, of a direct and a relayed user. In this paper we characterize a CDR scheme by deriving/bounding the Diversity-Multiplexing Trade-off (DMT) function. Two cases are considered. In the first case a transmitter knows the Channel State Information (CSI...

  2. Best relay selection using SNR and interference quotient for underlay cognitive networks

    KAUST Repository

    Hussain, Syed Imtiaz

    2012-06-01

    Cognitive networks in underlay settings operate simultaneously with the primary networks satisfying stringent interference limits. This condition forces them to operate with low transmission powers and confines their area of coverage. In an effort to reach remote destinations, underlay cognitive sources make use of relaying techniques. Selecting the best relay among those who are ready to cooperate is different in underlay settings than traditional non-cognitive networks. In this paper, we present a relay selection scheme which uses the quotient of the relay link signal to noise ratio (SNR) and the interference generated from the relay to the primary user to choose the best relay. The proposed scheme optimizes this quotient in a way to maximize the relay link SNR above a certain value whereas the interference is kept below a defined threshold. We derive closed expressions for the outage probability and bit error probability of the system incorporating this scheme. Simulation results confirm the validity of the analytical results and reveal that the relay selection in cognitive environment is feasible in low SNR regions. © 2012 IEEE.

  3. Coordination of Regenerative Relays and Direct Users in Wireless Cellular Networks

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar

    2011-01-01

    The area of wireless cooperation/relaying has recently been significantly enriched by the ideas of wireless network coding (NC), which bring substantial gains in spectral efficiency. These gains have mainly been demonstrated in scenarios with two-way relaying. Inspired by the ideas of wireless NC...

  4. Remote infeed and arc resistance effects on distance relays settings for 9 bus WSCC system

    Science.gov (United States)

    Ulla, Irshad; Radwan, M. S.; Baharom, M. N. R.; Ahmad, H.; Luqman, H. M.; Zainal, Zainab

    2017-09-01

    This paper introduce the effects of the remote infeed and arc resistance on the distance relays settings coordination for IEEE 9-bus system and the approach to including this effect on the setting using four zones quadrilateral characteristic, the simulation has been done using MATLAB/SIMULINK program which is helpful in constricting the power system and the distance relays.

  5. Improving throughput of single-relay DF channel using linear constellation precoding

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-08-01

    In this letter, we propose a transmission scheme to improve the overall throughput of a cooperative communication system with single decode-and-forward relay. Symbol error rate and throughput analysis of the new scheme are presented to facilitate the performance comparison with the existing decode-and-forward relaying schemes. Simulation results are further provided to corroborate the analytical results. © 2012 IEEE.

  6. Received signal strength in large-scale wireless relay sensor network: a stochastic ray approach

    NARCIS (Netherlands)

    Hu, L.; Chen, Y.; Scanlon, W.G.

    2011-01-01

    The authors consider a point percolation lattice representation of a large-scale wireless relay sensor network (WRSN) deployed in a cluttered environment. Each relay sensor corresponds to a grid point in the random lattice and the signal sent by the source is modelled as an ensemble of photons that

  7. Robust Relay in Narrow-Band Communications for Ubiquitous IoT Access

    Directory of Open Access Journals (Sweden)

    Qinghe Du

    2017-01-01

    Full Text Available We propose a robust wireless relay scheme in narrow-band communications for IoT access, which matches the typical features of IoT often carrying relatively low data rate with limited bandwidth. This framework is towards offering robustness in QoS guarantees with emphases on security and/or reliability, and we use the security-assured network as the typical scenario. In particular, we consider a dual-hop relay network including a transmitter, a receiver, an amplify-and-forward (AF untrusted relay, and a jamming node. The jamming node is treated as a helper. Specifically, the jammer broadcasts artificial noise (AN, which in fact pollutes both the untrusted relay and the destination node’s signals. However, we show that such AN can be effectively mitigated after the destination node obtains the forwarded signal from the relay, while the untrusted relay node cannot do so. The core idea for robustness assurance is to exploit higher signal dimensions at the receiver over the untrusted relay node. Simulations and analyses are also conducted to demonstrate that our proposed scheme can make the performance at the untrusted relay an interference-limited manner while completely removing the interferences at the receiver, therefore corroborating our claim in robustness in terms of security and reliability.

  8. Use of Behavior and Influence Functions for Relay Selection in Cooperative Communications

    DEFF Research Database (Denmark)

    Craciunescu, Razvan; Mihovska, Albena Dimitrova; Prasad, Ramjee

    2015-01-01

    This paper uses a novel set of functions to model the relay selection process in a scenario of cooperative wireless communications. We define a utility function that reflects the behavior and influence that a selected relay may have on the quality of the link to be established for the forwarding...... of Influence and Behavior to assess the effect on the system performance....

  9. Simultaneous Wireless Information and Power Transfer for MIMO Amplify-and-Forward Relay Systems

    KAUST Repository

    Benkhelifa, Fatma

    2016-03-28

    © 2015 IEEE. In this paper, we investigate two-hop Multiple- Input Multiple-Output (MIMO) Amplify-and-Forward (AF) relay communication systems with simultaneous wireless information and power transfer (SWIPT) at the multi-antenna energy harvesting relay. We derive the optimal source and relay covariance matrices to characterize the achievable region between the source-destination rate and the harvested energy at the relay, namely Rate-Energy (R-E) region. In this context, we consider the ideal scenario where the energy harvester (EH) receiver and the information decoder (ID) receiver at the relay can simultaneously decode the information and harvest the energy at the relay. This scheme provides an outer bound for the achievable R-E region since practical energy harvesting circuits are not yet able to harvest the energy and decode the information simultaneously. Then, we consider more practical schemes which are the power splitting (PS) and the time switching (TS) proposed in [1] and which separate the EH and ID transfer over the power domain and the time domain, respectively. In our study, we derive the boundary of the achievable R- E region and we show the effect of the source transmit power, the relay transmit power and the position of the relay between the source and the destination on the achievable R-E region for the ideal scenario and the two practical schemes.

  10. Relay-aided multi-cell broadcasting with random network coding

    DEFF Research Database (Denmark)

    Lu, Lu; Sun, Fan; Xiao, Ming

    2010-01-01

    We investigate a relay-aided multi-cell broadcasting system using random network codes, where the focus is on devising efficient scheduling algorithms between relay and base stations. Two scheduling algorithms are proposed based on different feedback strategies; namely, a one-step scheduling...

  11. Development of micro solar charger with blocking relay; Gyakuryu boshi relay wo oyoshita kogata solar judenki no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Nanno, I.; Matsushita, Y. Oka, S. [Omron Corp., Kyoto (Japan)

    1997-11-25

    Heavy-current tiny-scale solar charger is tentatively built, equipped with a function of preventing overcharge and countercurrent in case of charging storage batteries using solar cells. Incorporated into this solar charger are a countercurrent prevention relay system, a low loss current detection system, and a MOSFET parallel connection, which allow the solar charger to be designed small in size in the presence of an increase in heat due to circuit loss. In the countercurrent prevention relay system, the countercurrent prevention diode is bypassed by MOSFETs when too large a current is generated. In the low loss current detection system, currents are detected by use of the ON resistance of the MOSFETs for the prevention of overcharge. In the MOSFET parallel connection, MOSFETs are connected in parallel for a decrease in the ON resistance. The tentatively built charger is then subjected to a performance evaluation test outside the building, and the test is carried out by measuring the temperatures of the MOSFETs and the air. As the result, it is found that the temperature of MOSFET junction of the 12A tiny-size solar charger is approximately 42.5 degC at the highest, low enough to clear the requirements. 4 refs., 7 figs., 4 tabs.

  12. Anion Binding by Bambus[6]uril Probed in the Gas Phase and in Solution

    Czech Academy of Sciences Publication Activity Database

    Révész, Agnes; Schröder, Detlef; Švec, J.; Wimmerová, M.; Šindelář, V.

    2011-01-01

    Roč. 115, č. 41 (2011), s. 11378-11386 ISSN 1089-5639 Grant - others:European Research Council(XE) AdG HORIZOMS; GA ČR(CZ) GAP207/10/0695 Institutional research plan: CEZ:AV0Z40550506 Keywords : anion recognition * association constants * electrospray ionization * mass spectrometry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.946, year: 2011

  13. Anion Recognition by Diureido-calix[4]arenes in the 1,3-Alternate Conformation

    Czech Academy of Sciences Publication Activity Database

    Cuřínová, Petra; Stibor, I.; Budka, J.; Sýkora, Jan; Lang, Kamil; Lhoták, P.

    2009-01-01

    Roč. 33, č. 3 (2009), s. 612-619 ISSN 1144-0546 R&D Projects: GA ČR GA203/06/0738; GA ČR GA203/07/1424; GA AV ČR IAA400720706 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40320502 Keywords : complexation ability * biological systems * anions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.006, year: 2009

  14. Detect-and-forward in two-hop relay channels: a metrics-based analysis

    KAUST Repository

    Benjillali, Mustapha

    2010-06-01

    In this paper, we analyze the coded performance of a cooperative system with multiple parallel relays using "Detect-and-Forward" (DetF) strategy where each relay demodulates the overheard signal and forwards the detected binary words. The proposed method is based on the probabilistic characterization of the reliability metrics given under the form of L-values. First, we derive analytical expressions of the probability density functions (PDFs) of the L-values in the elementary two-hop DetF relay channel with different source-relay channel state information assumptions. Then, we apply the obtained expressions to calculate the theoretically achievable rates and compare them with the practical throughput of a simulated turbo-coded transmission. Next, we derive tight approximations for the end-to-end coded bit error rate (BER) of a general cooperative scheme with multiple parallel relays. Simulation results demonstrate the accuracy of our derivations for different cooperation configurations and conditions. © 2010 IEEE.

  15. Simultaneous Wireless Information and Power Transfer Mechanism in Interference Alignment Relay Networks

    Directory of Open Access Journals (Sweden)

    Fahui Wu

    2016-01-01

    Full Text Available This paper considers a simultaneous wireless information and power transfer (SWIPT mechanism in an interference alignment (IA relay system, in which source nodes send wireless information and energy simultaneously to relay nodes, and relay nodes forward the received signal to destination nodes powered by harvested energy. To manage interference and utilize interference as energy source, two-SWIPT receiver is designed, namely, power splitting (PS, and antennas switching (AS has been considered for relay system. The performance of AS- and PS-based IA relay systems is considered, as is a new energy cooperation (ECop scheme that is proposed to improve system performance. Numerical results are provided to evaluate the performance of all schemes and it is shown from the simulations that the performance of proposed ECop outperformed both AS and PS.

  16. An Optimal Analysis in Wireless Powered Full-duplex Relaying Network

    Directory of Open Access Journals (Sweden)

    K.-T. Nguyen

    2017-04-01

    Full Text Available Wireless-powered cellular networks (WPCNs are currently being investigated to exploit the reliability and improve battery lifetime of mobile users. This paper investigates the energy harvesting structure of the full-duplex relaying networks. By using the time switching based relaying (TSR protocol and Amplify-and-Forward (AF model in delay-limited transmission scheme, we propose the closed-form expression of the outage probability and then calculate the optimal throughput. An important result can be taken obviously that the time fraction in TSR, the position of relay, the noise as well as the energy conversation impacting on the outage probability as well as the optimal throughput. By Monte Carlo simulation, the numerical results indicate an effective relaying strategy in full-duplex cooperative systems. Finally, we provide fundamental design guidelines for selecting time fraction in TSR that satisfies the requirements of a practical relaying system.

  17. On the Performance of a Wireless Powered Communication System Using a Helping Relay

    Directory of Open Access Journals (Sweden)

    T. N. Nguyen

    2017-09-01

    Full Text Available This paper studies the outage performance and system throughput of a bidirectional wireless information and power transfer system with a helping relay. The relay helps forward wireless power from the access point (AP to the user, and also the information from the user to the AP in the reverse direction. We assume that the relay uses time switching based energy harvesting protocol. The analytical results provide theoretical insights into the effect of various system parameters, such as time switching factor, source transmission rate, transmitting-power-to-noise ratio to system performance for both amplify-and-forward and decode-and-forward relaying protocols. The optimal time switching ratio is determined in each case to maximize the information throughput from the user to the AP subject to the energy harvesting and consumption balance constraints at both the relay and the user. All of the above analyses are confirmed by Monte-Carlo simulation.

  18. Exact Outage Performance Analysis of Multiuser Multi-relay Spectrum Sharing Cognitive Networks

    Directory of Open Access Journals (Sweden)

    T. Zhang

    2015-04-01

    Full Text Available In this paper, we investigate the outage performance of dual-hop multiuser multi-relay cognitive radio networks under spectrum sharing constraints. Using an efficient relay-destination selection scheme, the exact and asymptotic closed-form expressions for the outage probability are derived. From these expressions it is indicated that the achieved diversity order is only determined by the number of secondary user (SU relays and destinations, and equals to M+N (where M and N are the number of destination nodes and relay nodes, respectively. Further, we find that the coding gain of the SU network will be affected by the interference threshold $bar I$ at the primary user (PU receiver. Specifically, as the increases of the interference threshold, the coding gain of the considered network approaches to that of the multiuser multi-relay system in the non-cognitive network. Finally, our study is corroborated by representative numerical examples.

  19. Performance analysis of two-way amplify and forward relaying with adaptive modulation

    KAUST Repository

    Hwang, Kyusung

    2009-09-01

    In this paper, we study two-way amplify-and-forward relaying in conjunction with adaptive modulation over a multiple relay network. In order to keep the diversity order equal to the number of relays and maintain a low complexity, we consider the best relay selection scheme in this work. Based on the proposed selection criterion for the best relay, we analyze the average spectral efficiency by its approximated upper bound. In addition, we extend the proposed scheme to the case where a direct path between source and destination exists. Our numerical examples show that the proposed system offers a considerable gain in the spectral efficiency while satisfying the error rates requirements. ©2009 IEEE.

  20. Cooperation schemes for rate enhancement in detect-and-forward relay channels

    KAUST Repository

    Benjillali, Mustapha

    2010-05-01

    To improve the spectral efficiency of "Detect-and-Forward" (DetF) half-duplex relaying in fading channels, we propose a cooperation scheme where the relay uses a modulation whose order is higher than the one at the source. In a new common framework, we show that the proposed scheme offers considerable gains - in terms of achievable information rates - compared to the conventional DetF relaying schemes for both orthogonal and non-orthogonal source/relay cooperation. This allows us to propose an adaptive cooperation scheme based on the maximization of the information rate at the destination which needs to observe only the average signal-to-noise ratios of direct and relaying links. ©2010 IEEE.

  1. Two-way CSI-assisted AF relaying with HPA nonlinearity

    KAUST Repository

    Qi, Jian

    2015-09-11

    In this paper, we investigate half-duplex two-way dual-hop channel state information (CSI)-assisted amplify-andforward (AF) relaying in the presence of high-power amplifier (HPA) nonlinearity at relays. The expression for the end-toend signal-to-noise ratio (SNR) is derived as per the modified system model by taking into account the interference caused by relaying scheme and HPA nonlinearity. The system performance of the considered relaying network is evaluated in terms of average symbol error probability (SEP) in Nakagami-m fading channels, by making use of the moment-generating function (MGF) approach. Numerical results are provided and show the effects of several parameters, such as quadrature amplitude modulation (QAM) order, number of relays, HPA parameters, and Nakagami parameter, on performance. © 2015 IEEE.

  2. Error-rate performance analysis of cooperative OFDMA system with decode-and-forward relaying

    KAUST Repository

    Fareed, Muhammad Mehboob

    2014-06-01

    In this paper, we investigate the performance of a cooperative orthogonal frequency-division multiple-access (OFDMA) system with decode-and-forward (DaF) relaying. Specifically, we derive a closed-form approximate symbol-error-rate expression and analyze the achievable diversity orders. Depending on the relay location, a diversity order up to (LSkD + 1) + σ M m = 1 min(LSkRm + 1, LR mD + 1) is available, where M is the number of relays, and LS kD + 1, LSkRm + 1, and LRmD + 1 are the lengths of channel impulse responses of source-to-destination, source-to- mth relay, and mth relay-to-destination links, respectively. Monte Carlo simulation results are also presented to confirm the analytical findings. © 2013 IEEE.

  3. On achievable rates of interference and cognitive channels with a relay

    KAUST Repository

    Zorgui, Marwen

    2015-08-30

    We consider a two-user interference channel assisted by a relay. Treating interference as noise at the receivers, and adopting an amplify and forward (AF) strategy at the relay, we derive achievable rates of both users, for given powers. Next, we solve the optimal power allocation problem maximizing the weighted sum rate of both users with and without relay power optimization. In particular, we propose a simple iterative line search algorithm solving the joint optimization problem over the three transmit powers and show that optimizing the relay power enhances the performance of the system. Then, considering the first user as a primary user, we determine the maximum instantaneous rate that the secondary user can achieve subject to an outage constraint with respect to the primary user and a peak power constraint. We show that, likewise the first part, jointly optimizing the secondary user and the relay transmit powers enhances the secondary user performance.

  4. A study of optimization problem for amplify-and-forward relaying over weibull fading channels

    KAUST Repository

    Ikki, Salama Said

    2010-09-01

    This paper addresses the power allocation and relay positioning problems in amplify-and-forward cooperative networks operating in Weibull fading environments. We study adaptive power allocation (PA) with fixed relay location, optimal relay location with fixed power allocation, and joint optimization of the PA and relay location under total transmit power constraint, in order to minimize the outage probability and average error probability at high signal-to-noise ratios (SNR). Analytical results are validated by numerical simulations and comparisons between the different optimization schemes and their performance are provided. Results show that optimum PA brings only coding gain, while optimum relay location yields, in addition to the latter, diversity gains as well. Also, joint optimization improves both, the diversity gain and coding gain. Furthermore, results illustrate that the analyzed adaptive algorithms outperform uniform schemes. ©2010 IEEE.

  5. Cooperative joint precoding in a downlink cellular system with shared relay: Design and performance evaluation

    KAUST Repository

    Kwon, JaeWoo

    2012-10-01

    In this paper, we investigate a relay enhanced cellular system, where a relay station is located in the overlap area served by two base stations. We propose cooperative joint precoding schemes for the downlink transmission of such relay enhanced cellular system to maximize the system capacity while minimizing the interference at both the relay station and the mobile stations. We formulate the optimization problems to maximize the system capacity and design the multiuser precoding vectors at each base station and the relay station. We quantify the ergodic rate performance of the proposed multiuser precoding schemes through statistical analysis. The extensively derived ergodic expressions will facilitate the accurate performance evaluation of the proposed transmission schemes. Numerical results show that the proposed schemes can effectively cancel the interference and improve the sum rate and the outage performance for cell edge users. © 2002-2012 IEEE.

  6. DFT-Based Comparative Study about the Influence of Fluorine and Hydroxyl Anions on Opto-Electric Properties of Borate Crystals: Choice for Better Anion.

    Science.gov (United States)

    Bashir, Beenish; Zhang, Bingbing; Lee, Ming-Hsien; Pan, Shilie; Yang, Zhihua

    2017-05-15

    Replacing hydroxyl anions OH¯ by fluorine anions F¯ in borates can cause the blue shift of the UV cutoff edge and also exhibits apparent differences in nonlinear optical (NLO) properties. To clarify the intrinsic difference between OH¯ anions and F¯ anions, several typical borates with different types of cations (p-cations with lone-pair electrons, trivalent rare-earth, and alkaline earth metals) have been studied. The theoretical studies reveal that the blue shift in the band gap of borates with fluorine as compared to those with hydroxyl can be assumed to be the result of weaker interaction of the cation-fluoride (La/Bi/B-F) bonds compared to that of the cation-oxygen and hydroxyl bonds. NLO properties are found to have the order of BiB 2 O 4 F > BiB 2 O 4 (OH)> LaB 2 O 4 F ≈ LaB 2 O 4 (OH). The large difference can be attributed mainly to the stereochemical activity of the lone pair (SCALP) effect of the Bi cations and the special BO 3 F with strong anisotropy as compared to the BO 4 group. The energy spanning of F-2p orbitals is more extended in BiB 2 O 4 F as compared to LaB 2 O 4 F, Sr 3 B 6 O 11 F 2 , and Ba 3 B 6 O 11 F 2 due to the bonding of Bi/B-F, which indicates F-2p orbitals have more chance to overlap with surrounding atoms and enhance the polarizability in all systems. Moreover, the degree of SCALP of the Bi cations is apparently activated by the introduction of the F¯ anions, which causes an obvious enhancement in NLO properties in bismuth borates with F¯. These investigations will help us to classify the solid-state chemistry of F¯ and OH¯ anions in borate systems with different types of metal cations.

  7. Confectionary Chemistry.

    Science.gov (United States)

    Levine, Elise Hilf

    1996-01-01

    Presents activities and demonstrations that enable teachers to use various types of confections as tactile experiences to spark chemistry students' interest and generate enthusiasm for learning. Presents uses of candy in teaching about atomic structure, spontaneous nuclear decay, chemical formulas, fractoluminescence, the effect of a molecular…

  8. Supramolecular Chemistry

    Indian Academy of Sciences (India)

    by-product from the 'unattractive goo' of an experiment which had gone wrong. Pederson examined the product and the struc- ture of dibenzo-18-crown-6 was determined (Figure 2A). Inter- estingly, in presence. 1. N Jayaraman, 2016 Nobel. Prize in Chemistry: Confer- ring Molecular Machines as. Engines of Creativity ...

  9. Food carbohydrate chemistry

    National Research Council Canada - National Science Library

    Wrolstad, R. E

    2012-01-01

    .... Now in Food Carbohydrate Chemistry, author Wrolstad emphasizes the application of carbohydrate chemistry to understanding the chemistry, physical and functional properties of food carbohydrates...

  10. Handbook of heterocyclic chemistry

    National Research Council Canada - National Science Library

    Katritzky, Alan R

    2010-01-01

    ... Heterocyclic Chemistry I (1984) Comprehensive Heterocyclic Chemistry II (1996) Comprehensive Heterocyclic Chemistry III (2008) Comprehensive Organic Functional Group Transformations I (1995) Compreh...

  11. Lower Bounds on the Capacity of the Relay Channel with States at the Source

    Directory of Open Access Journals (Sweden)

    Zaidi Abdellatif

    2009-01-01

    Full Text Available Abstract We consider a state-dependent three-terminal full-duplex relay channel with the channel states noncausally available at only the source, that is, neither at the relay nor at the destination. This model has application to cooperation over certain wireless channels with asymmetric cognition capabilities and cognitive interference relay channels. We establish lower bounds on the channel capacity for both discrete memoryless (DM and Gaussian cases. For the DM case, the coding scheme for the lower bound uses techniques of rate-splitting at the source, decode-and-forward (DF relaying, and a Gel'fand-Pinsker-like binning scheme. In this coding scheme, the relay decodes only partially the information sent by the source. Due to the rate-splitting, this lower bound is better than the one obtained by assuming that the relay decodes all the information from the source, that is, full-DF. For the Gaussian case, we consider channel models in which each of the relay node and the destination node experiences on its link an additive Gaussian outside interference. We first focus on the case in which the links to the relay and to the destination are corrupted by the same interference; and then we focus on the case of independent interferences. We also discuss a model with correlated interferences. For each of the first two models, we establish a lower bound on the channel capacity. The coding schemes for the lower bounds use techniques of dirty paper coding or carbon copying onto dirty paper, interference reduction at the source and decode-and-forward relaying. The results reveal that, by opposition to carbon copying onto dirty paper and its root Costa's initial dirty paper coding (DPC, it may be beneficial in our setup that the informed source uses a part of its power to partially cancel the effect of the interference so that the uninformed relay benefits from this cancellation, and so the source benefits in turn.

  12. Lower Bounds on the Capacity of the Relay Channel with States at the Source

    Directory of Open Access Journals (Sweden)

    Abdellatif Zaidi

    2009-01-01

    Full Text Available We consider a state-dependent three-terminal full-duplex relay channel with the channel states noncausally available at only the source, that is, neither at the relay nor at the destination. This model has application to cooperation over certain wireless channels with asymmetric cognition capabilities and cognitive interference relay channels. We establish lower bounds on the channel capacity for both discrete memoryless (DM and Gaussian cases. For the DM case, the coding scheme for the lower bound uses techniques of rate-splitting at the source, decode-and-forward (DF relaying, and a Gel'fand-Pinsker-like binning scheme. In this coding scheme, the relay decodes only partially the information sent by the source. Due to the rate-splitting, this lower bound is better than the one obtained by assuming that the relay decodes all the information from the source, that is, full-DF. For the Gaussian case, we consider channel models in which each of the relay node and the destination node experiences on its link an additive Gaussian outside interference. We first focus on the case in which the links to the relay and to the destination are corrupted by the same interference; and then we focus on the case of independent interferences. We also discuss a model with correlated interferences. For each of the first two models, we establish a lower bound on the channel capacity. The coding schemes for the lower bounds use techniques of dirty paper coding or carbon copying onto dirty paper, interference reduction at the source and decode-and-forward relaying. The results reveal that, by opposition to carbon copying onto dirty paper and its root Costa's initial dirty paper coding (DPC, it may be beneficial in our setup that the informed source uses a part of its power to partially cancel the effect of the interference so that the uninformed relay benefits from this cancellation, and so the source benefits in turn.

  13. Synthesis, Reduction Chemistry, and Spectroscopic and Computational Studies of Isomeric Quinolinecarboxaldehyde Triosmium Clusters

    Czech Academy of Sciences Publication Activity Database

    Rosenberg, E.; Rokhsana, D.; Nervi, C.; Gobetto, R.; Milone, L.; Viale, A.; Fiedler, Jan; Botavina, M. A.

    2004-01-01

    Roč. 23, - (2004), s. 215-223 ISSN 0276-7333 R&D Projects: GA ČR GA203/03/0821; GA MŠk OC D15.10 Institutional research plan: CEZ:AV0Z4040901 Keywords : organometallic chemistry * radical-anions * density Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.196, year: 2004

  14. Clinical Usefulness of the Serum Anion Gap

    OpenAIRE

    Lee, Sik; Kang, Kyung Pyo; Kang, Sung Kyew

    2006-01-01

    The anion gap in the serum is useful in the interpretation of acid-base disorders and in the diagnosis of other conditions. In the early 1980s, ion-selective electrodes for specific ionic species were introduced for the measurement of serum electrolytes. This new method has caused a shift of the anion gap from 12±4 mEq/L down 6±3 mEq/L. It is worthy for clinicians to understand the range of normal anion gap and the measuring methods for serum sodium and chloride in the laboratories that suppo...

  15. MODERN TECHNOLOGY OF ANIONIC POLYMERIZATION MONOMERS

    Directory of Open Access Journals (Sweden)

    A. V. Tkachev

    2013-01-01

    Full Text Available The preconditions of use in the manufacture of automobile tyres of vulcanizates-based mortar butadienestyrene rubber with a high content of 1.2 links butadiene and statistical distribution of styrene are formulated. Set out scientific researches in the field of anionic co-polymerization of diene and vinyl aromatic monomers. Formulation of catalytic systems applied in processes of anionic copolymerization of monomers are given. The reasons of formation of gel in the process of anionic polymerization of monomers and terms of their elimination are considered.

  16. Optical Sensing of Anions via Supramolecular Recognition with Biimidazole Complexes.

    Science.gov (United States)

    Rommel, Sebastian A; Sorsche, Dieter; Fleischmann, Maximilian; Rau, Sven

    2017-12-22

    Phosphorescent metal complexes with peripheral N-H donor functionalities have attracted great attention as potential molecular sensing units for anionic species lately. In this contribution we discuss the development and potential of anion recognition and sensing features of recent examples of luminescent 2,2'-biimidazole complexes of ruthenium(II), iridium(III), osmium(II) and cobalt(III). The general dependency of photophysical features in these complexes regarding the acid-base chemistry of the peripheral N-H functionalities will be outlined as a basic requirement for optical ion recognition. Systematic strategies for the tuning and specific improvement by synthetic means will be discussed regarding recent reports. With respect to their distinct photophysical features, different transition metals are considered individually to demonstrate particular trends regarding ligand modification within the respective groups. In summary, this review elucidates the current state-of-the-art and future potential of the versatile class of 2,2'-biimidazole based sensor chromophores. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. 75 FR 49491 - Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and...

    Science.gov (United States)

    2010-08-13

    ... FEDERAL COMMUNICATIONS COMMISSION [CG Docket No. 03-123; FCC 10-115] Telecommunications Relay... Telecommunications Relay Services (TRS) Fund (Fund) year. This action is necessary because the rates for the previous... Telecommunications Relay Services and Speech-to-Speech Services for Individuals with Hearing and Speech Disabilities...

  18. 75 FR 26701 - Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and...

    Science.gov (United States)

    2010-05-12

    ...] Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and Speech Disabilities... formulas and funding requirement estimates for the Interstate Telecommunications Relay Services (TRS) Fund... costs of providing VRS. Telecommunications Relay Services and Speech-to-Speech Services for Individuals...

  19. 78 FR 49693 - Speech-to-Speech and Internet Protocol (IP) Speech-to-Speech Telecommunications Relay Services...

    Science.gov (United States)

    2013-08-15

    ...] Speech-to-Speech and Internet Protocol (IP) Speech-to-Speech Telecommunications Relay Services; Telecommunications Relay Services and Speech-to-Speech Services for Individuals With Hearing and Speech Disabilities... amends telecommunications relay services (TRS) mandatory minimum standards applicable to Speech- to...

  20. Adaptive relaying for ground fault protection of a distribution network

    Energy Technology Data Exchange (ETDEWEB)

    Sachdev, M.S.; Sidhu, T.S.; Talukdar, B.K. [Saskatchewan Univ., Saskatoon, SK (Canada)

    1995-12-31

    Adaptive protection was used for designing a protection system for the City of Saskatoon`s distribution network. The software and hardware were developed and the protection system was implemented in the laboratory at the University of Saskatchewan. In the first phase of the project, phase overcurrent relays were coordinated on the basis of three-phase faults. Most faults in distribution networks were single-phase to ground faults. Ground fault currents varied due to different grounding practices, changes in operating conditions and system topology. In the second phase of the project, adaptive capabilities for ground overcurrent and directional ground overcurrent protection were added. Software modules developed for achieving adaptive ground fault protection were described. Results from system studies carried out using the City of Saskatoon`s distribution network were also analyzed. 7 refs., 8 figs.

  1. Outage analysis of opportunistic decode-and-forward relaying

    KAUST Repository

    Tourki, Kamel

    2010-09-01

    In this paper, we investigate a dual-hop opportunistic decode-and-forward relaying scheme where the source may or not be able to communicate directly with the destination. We first derive statistics based on exact probability density function (PDF) of each hop. Then, the PDFs are used to determine closed-form outage probability expression for a transmission rate R. Furthermore, we evaluate the asymptotic outage performance and the diversity order is deduced. Unlike existing works where the analysis focused on high signal-to-noise ratio (SNR) regime, such results are important to enable the designers to take decisions regarding practical systems that operate at low SNR regime. We show that performance simulation results coincide with our analytical results under practical assumption of unbalanced hops. © 2010 IEEE.

  2. The success of the 45th CERN Relay Race

    CERN Multimedia

    CERN Bulletin

    2015-01-01

    On Thursday, 21 May, 783 people (9 Nordic walkers and 129 teams of 6 runners each) took part in the 45th CERN Relay Race.   The teams were divided into eight different categories: three CERN categories (Seniors, Dames, Mixte) – in which the six runners in the team must belong to the same professional unit – and four “open” categories (Open, Veterans Open, Dames Open, Mixte Open) - in which the six runners in the team do not necessarily belong to the same professional unit and can include people from outside CERN. Each team covered 3,600 metres around the Meyrin site, with the race's fastest runners covering this distance in only 11 minutes and 5 seconds! (See all the results here. For more photos from the event, see here, here and here.)  

  3. Next-Generation NASA Earth-Orbiting Relay Satellites: Fusing Microwave and Optical Communications

    Science.gov (United States)

    Israel, David J.

    2018-01-01

    NASA is currently considering architectures and concepts for the generation of relay satellites that will replace the Tracking and Data Relay Satellite (TDRS) constellation, which has been flying since 1983. TDRS-M, the last of the second TDRS generation, launched in August 2017, extending the life of the TDRS constellation beyond 2030. However, opportunities exist to re-engineer the concepts of geosynchronous Earth relay satellites. The needs of the relay satellite customers have changed dramatically over the last 34 years since the first TDRS launch. There is a demand for greater bandwidth as the availability of the traditional RF spectrum for space communications diminishes and the demand for ground station access grows. The next generation of NASA relay satellites will provide for operations that have factored in these new constraints. In this paper, we describe a heterogeneous constellation of geosynchronous relay satellites employing optical and RF communications. The new constellation will enable new optical communications services formed by user-to-space relay, space relay-to-space relay and space relay-to-ground links. It will build upon the experience from the Lunar Laser Communications Demonstration from 2013 and the Laser Communications Relay Demonstration to be launched in 2019.Simultaneous to establishment of the optical communications space segment, spacecraft in the TDRS constellation will be replaced with RF relay satellites with targeted subsets of the TDRS capabilities. This disaggregation of the TDRS service model will allow for flexibility in replenishing the needs of legacy users as well as addition of new capabilities for future users. It will also permit the U.S. government access to launch capabilities such as rideshare and to hosted payloads that were not previously available. In this paper, we also explore how the next generation of Earth relay satellites provides a significant boost in the opportunities for commercial providers to the

  4. Next-Generation NASA Earth-Orbiting Relay Satellites: Fusing Optical and Microwave Communications

    Science.gov (United States)

    Israel, David J.; Shaw, Harry

    2018-01-01

    NASA is currently considering architectures and concepts for the generation of relay satellites that will replace the Tracking and Data Relay Satellite (TDRS) constellation, which has been flying since 1983. TDRS-M, the last of the second TDRS generation, launched in August 2017, extending the life of the TDRS constellation beyond 2030. However, opportunities exist to re-engineer the concepts of geosynchronous Earth relay satellites. The needs of the relay satellite customers have changed dramatically over the last 34 years since the first TDRS launch. There is a demand for greater bandwidth as the availability of the traditional RF spectrum for space communications diminishes and the demand for ground station access grows. The next generation of NASA relay satellites will provide for operations that have factored in these new constraints. In this paper, we describe a heterogeneous constellation of geosynchronous relay satellites employing optical and RF communications. The new constellation will enable new optical communications services formed by user-to-space relay, space relay-to-space relay and space relay-to-ground links. It will build upon the experience from the Lunar Laser Communications Demonstration from 2013 and the Laser Communications Relay Demonstration to be launched in 2019.Simultaneous to establishment of the optical communications space segment, spacecraft in the TDRS constellation will be replaced with RF relay satellites with targeted subsets of the TDRS capabilities. This disaggregation of the TDRS service model will allow for flexibility in replenishing the needs of legacy users as well as addition of new capabilities for future users. It will also permit the U.S. government access to launch capabilities such as rideshare and to hosted payloads that were not previously available.In this paper, we also explore how the next generation of Earth relay satellites provides a significant boost in the opportunities for commercial providers to the

  5. Anion conductance of the human red cell is carried by a maxi-anion channel

    DEFF Research Database (Denmark)

    Glogowska, Edyta; Dyrda, Agnieszka; Cueff, Anne

    2010-01-01

    Historically, the anion transport through the human red cell membrane has been perceived to be mediated by Band 3, in the two-component concept with the large electroneutral anion exchange accompanied by the conductance proper, which dominated the total membrane conductance. The status of anion...... that the diversity of anionic channel activities recorded in human erythrocytes corresponds to different kinetic modalities of a unique type of maxi-anion channel with multiple conductance levels and probably multiple gating properties and pharmacology, depending on conditions. It demonstrates the role of activator...... played by serum in the recruitment of multiple new conductance levels showing very complex kinetics and gating properties upon serum addition. These channels, which seem to be dormant under normal physiological conditions, are potentially activable and could confer a far higher anion conductance...

  6. Fine chemistry

    International Nuclear Information System (INIS)

    Laszlo, P.

    1988-01-01

    The 1988 progress report of the Fine Chemistry laboratory (Polytechnic School, France) is presented. The research programs are centered on the renewal of the organic chemistry most important reactions and on the invention of new, highly efficient and highly selective reactions, by applying low cost reagents and solvents. An important research domain concerns the study and fabrication of new catalysts. They are obtained by means of the reactive sputtering of the metals and metal oxydes thin films. The Monte Carlo simulations of the long-range electrostatic interaction in a clay and the obtention of acrylamides from anhydrous or acrylic ester are summarized. Moreover, the results obtained in the field of catalysis are also given. The published papers and the congress communications are included [fr

  7. Chemistry and physics

    International Nuclear Information System (INIS)

    Broerse, J.J.; Barendsen, G.W.; Kal, H.B.; Kogel, A.J. van der

    1983-01-01

    This book contains the extended abstracts of the contributions of the poster workshop sessions on chemistry and physics of the 7th international congress of radiation research. They cover the following main topics: primary processes in radiation physics and chemistry, general chemistry in radiation chemistry, DNA and model systems in radiation chemistry, molecules of biological interest in radiation chemistry, techniques in radiation chemistry, hot atom chemistry. refs.; figs.; tabs

  8. Radioanalytical chemistry

    International Nuclear Information System (INIS)

    1982-01-01

    The bibliography of Hungarian literature in the field of radioanalytical chemistry covers the four-year period 1976-1979. The list of papers contains 290 references in the alphabetical order of the first authors. The majority of the titles belongs to neutron activation analysis, labelling, separation and determination of radioactive isotopes. Other important fields like radioimmunoassay, environmental protection etc. are covered as well. (Sz.J.)

  9. Analytical chemistry

    International Nuclear Information System (INIS)

    Anon.

    1985-01-01

    The division for Analytical Chemistry continued to try and develope an accurate method for the separation of trace amounts from mixtures which, contain various other elements. Ion exchange chromatography is of special importance in this regard. New separation techniques were tried on certain trace amounts in South African standard rock materials and special ceramics. Methods were also tested for the separation of carrier-free radioisotopes from irradiated cyclotron discs

  10. Green chemistry

    International Nuclear Information System (INIS)

    Warner, John C.; Cannon, Amy S.; Dye, Kevin M.

    2004-01-01

    A grand challenge facing government, industry, and academia in the relationship of our technological society to the environment is reinventing the use of materials. To address this challenge, collaboration from an interdisciplinary group of stakeholders will be necessary. Traditionally, the approach to risk management of materials and chemicals has been through inerventions intended to reduce exposure to materials that are hazardous to health and the environment. In 1990, the Pollution Prevention Act encouraged a new tact-elimination of hazards at the source. An emerging approach to this grand challenge seeks to embed the diverse set of environmental perspectives and interests in the everyday practice of the people most responsible for using and creating new materials--chemists. The approach, which has come to be known as Green Chemistry, intends to eliminate intrinsic hazard itself, rather than focusing on reducing risk by minimizing exposure. This chapter addresses the representation of downstream environmental stakeholder interests in the upstream everyday practice that is reinventing chemistry and its material inputs, products, and waste as described in the '12 Principles of Green Chemistry'

  11. Green chemistry

    International Nuclear Information System (INIS)

    Colonna, P.

    2006-01-01

    The depletion of world fossil fuel reserves and the involvement of greenhouse gases in the global warming has led to change the industrial and energy policies of most developed countries. The goal is now to reserve petroleum to the uses where it cannot be substituted, to implement renewable raw materials obtained from plants cultivation, and to consider the biodegradability of molecules and of manufactured objects by integrating the lifetime concept in their expected cycle of use. The green chemistry includes the design, development and elaboration of chemical products and processes with the aim of reducing or eliminating the use and generation of harmful compounds for the health and the environment, by adapting the present day operation modes of the chemical industry to the larger framework of the sustainable development. In addition to biofuels, this book reviews the applications of green chemistry in the different industrial processes in concern. Part 1 presents the diversity of the molecules coming from renewable carbon, in particular lignocellulose and the biotechnological processes. Part 2 is devoted to materials and treats of the overall available technological solutions. Part 3 focusses on functional molecules and chemical intermediates, in particular in sugar- and fats-chemistry. Part 4 treats of biofuels under the aspects of their production and use in today's technologies. The last part deals with the global approaches at the environmental and agricultural levels. (J.S.)

  12. Transmission Power Adaption for Full-Duplex Relay-Aided Device-to-Device Communication

    Directory of Open Access Journals (Sweden)

    Hui Dun

    2017-03-01

    Full Text Available Device-to-device (D2D communications bring significant improvements of spectral efficiency by underlaying cellular networks. However, they also lead to a more deteriorative interference environment for cellular users, especially the users in severely deep fading or shadowing. In this paper, we investigate a relay-based communication scheme in cellular systems, where the D2D communications are exploited to aid the cellular downlink transmissions by acting as relay nodes with underlaying cellular networks. We modeled two-antenna infrastructure relays employed for D2D relay. The D2D transmitter is able to transmit and receive signals simultaneously over the same frequency band. Then we proposed an efficient power allocation algorithm for the base station (BS and D2D relay to reduce the loopback interference which is inherent due to the two-antenna infrastructure in full-duplex (FD mode. We derived the optimal power allocation problem in closed form under the independent power constraint. Simulation results show that the algorithm reduces the power consumption of D2D relay to the greatest extent and also guarantees cellular users’ minimum transmit rate. Moreover, it also outperforms the existing half-duplex (HD relay mode in terms of achievable rate of D2D.

  13. The Physical Layer Security Experiments of Cooperative Communication System with Different Relay Behaviors

    Directory of Open Access Journals (Sweden)

    Yishan Su

    2017-04-01

    Full Text Available Physical layer security is an attractive security mechanism, which exploits the randomness characteristics of wireless transmission channel to achieve security. However, it is hampered by the limitation of the channel condition that the main channel must be better than the eavesdropper channel. To alleviate the limitation, cooperative communication is introduced. Few studies have investigated the physical layer security of the relay transmission model. In this paper, we performed some experiments to evaluate the physical layer security of a cooperative communication system, with a relay operating in decode-and-forward (DF cooperative mode, selfish and malicious behavior in real non-ideal transmission environment. Security performance is evaluated in terms of the probability of non-zero secrecy capacity. Experiments showed some different results compared to theoretical simulation: (1 to achieve the maximum secrecy capacity, the optimal relay power according to the experiments result is larger than that of ideal theoretical results under both cooperative and selfish behavior relay; (2 the relay in malicious behavior who forwards noise to deteriorate the main channel may deteriorate the eavesdropper channel more seriously than the main channel; (3 the optimal relay positions under cooperative and selfish behavior relay cases are both located near the destination because of non-ideal transmission.

  14. The Physical Layer Security Experiments of Cooperative Communication System with Different Relay Behaviors.

    Science.gov (United States)

    Su, Yishan; Han, Guangyao; Fu, Xiaomei; Xu, Naishen; Jin, Zhigang

    2017-04-06

    Physical layer security is an attractive security mechanism, which exploits the randomness characteristics of wireless transmission channel to achieve security. However, it is hampered by the limitation of the channel condition that the main channel must be better than the eavesdropper channel. To alleviate the limitation, cooperative communication is introduced. Few studies have investigated the physical layer security of the relay transmission model. In this paper, we performed some experiments to evaluate the physical layer security of a cooperative communication system, with a relay operating in decode-and-forward (DF) cooperative mode, selfish and malicious behavior in real non-ideal transmission environment. Security performance is evaluated in terms of the probability of non-zero secrecy capacity. Experiments showed some different results compared to theoretical simulation: (1) to achieve the maximum secrecy capacity, the optimal relay power according to the experiments result is larger than that of ideal theoretical results under both cooperative and selfish behavior relay; (2) the relay in malicious behavior who forwards noise to deteriorate the main channel may deteriorate the eavesdropper channel more seriously than the main channel; (3) the optimal relay positions under cooperative and selfish behavior relay cases are both located near the destination because of non-ideal transmission.

  15. Interactive effects of relay and circuit breaker aging in a safety-related system

    International Nuclear Information System (INIS)

    Toman, G.J.; Bacanskas, V.P.; Shook, T.A.; Ladlow, C.C.; Gunther, W.

    1987-01-01

    This paper provides an overview of the results of a program to evaluate the aging of circuit breakers and relays and the effects of that aging on the function of a safety system used in nuclear power plants. The program was performed under the Nuclear Plant Aging Research (NPAR) Program of the US Nuclear Regulatory Commission under subcontract to Brookhaven National Laboratory. There were two primary aspects to the program. In the first, the aging and failure modes of relays and circuit breakers were determined by evaluating the construction, design, and materials and the failure data related to nuclear power plant service. In the second, the interactions between a safety system and its relays and circuit breakers were evaluated to determine the effects of relay and circuit breaker aging on the function of the safety system. The aging of relays and circuit breakers was assessed through evaluation of failure data bases, discussions with utility personnel, and evaluation of equipment operating and maintenance manuals. The interaction study was based on an analysis of the safety injection system of a pressurized water reactor. The effects of stresses from the system were analyzed for the tendency to cause deterioration of the relays and circuit breakers in the system. Then the effect of the deterioration of relays and circuit breakers on the functional capability of the safety system was evaluated

  16. Development and testing of a relay nozzle concept for air-jet weaving

    Science.gov (United States)

    Münkel, A.; Gloy, Y. S.; Gries, T.

    2017-10-01

    The textile industry is an energy intensive branch of industry. Increasing energy costs are a challenge for textile manufacturers as well as for the developers of textile production machines [1]. Air jet weaving is the most productive method to produce woven fabrics. However, air-jet weaving machines have a significantly higher level of energy consumption compared to other weaving machines. Approximately 80% of compressed air is consumed by the relay nozzles. Therefore, there are different approaches to reduce the consumption of compressed air and to increase the energy efficiency of air-jet looms [2] At the Institut für Textiltechnik der RWTH Aachen University, Aachen new relay nozzle concepts have been developed. Based on Computational Fluid Dynamics (CFD) the concepts were further developed with the result of an energy-efficient relay nozzle concept. The simulations have shown the potential energy savings up to 60 % compared to conventional relay nozzles. Furthermore, practical validations of these simulation results were done. The velocity, stagnation pressure and volume flow were measured in the reed canal. The optimal position regarding the injection angle and high, as well as the distance between two relay nozzles were identified with the results of the measurements. In addition, the relay nozzles were tested in the industrial environment. These tests have shown a low error rate which is comparable conventional relay nozzle concepts. Furthermore, exergy savings up to 49% has been measured.

  17. Impact of Primary User Traffic on Adaptive Transmission for Cognitive Radio with Partial Relay Selection

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In a cognitive relay system, the secondary user is permitted to transmit data via a relay when licensed frequency bands are detected to be free. Previous studies mainly focus on reducing or limiting the interference of the secondary transmission on the primary users. On the other hand, however, the primary user traffic will also affect the data transmission performance of the secondary users. In this paper, we investigate the impact of the primary user traffic on the bit error rate (BER) of the secondary transmission, when the secondary user adopts adaptive transmission with a relay partially selected. From the numerical results, we can see that the primary user traffic seriously degrades average BER. The worse-link partial selection can perform almost as well as the global selection when the channel conditions of the source-relay links and the relay-destination links differ a lot. In addition, although the relay selection improves the spectral efficiency of the secondary transmission, numerical results show that it only has slight impact on the overall average BER, so that the robustness of the system will not be affected by the relay selection.

  18. Outage Probability Analysis in Power-Beacon Assisted Energy Harvesting Cognitive Relay Wireless Networks

    Directory of Open Access Journals (Sweden)

    Ngoc Phuc Le

    2017-01-01

    Full Text Available We study the performance of the secondary relay system in a power-beacon (PB assisted energy harvesting cognitive relay wireless network. In our system model, a secondary source node and a relay node first harvest energy from distributed PBs. Then, the source node transmits its data to the destination node with the help of the relay node. Also, fading coefficients of the links from the PBs to the source node and relay node are assumed independent but not necessarily identically distributed (i.n.i.d Nakagami-m random variables. We derive exact expressions for the power outage probability and the channel outage probability. Based on that, we analyze the total outage probability of the secondary relay system. Asymptotic analysis is also performed, which provides insights into the system behavior. Moreover, we evaluate impacts of the primary network on the performance of the secondary network with respect to the tolerant interference threshold at the primary receiver as well as the interference introduced by the primary transmitter at the secondary source and relay nodes. Simulation results are provided to validate the analysis.

  19. Massive MIMO Relay Systems with Multipair Wireless Information and Power Transfer

    Directory of Open Access Journals (Sweden)

    Hongwu Liu

    2017-01-01

    Full Text Available This paper investigates destination-aided simultaneous wireless information and power transfer (SWIPT for a decode-and-forward relay network, in which massive multiple-input multiple-output antennas are deployed at relay to assist communications among multiple source-destination pairs. During relaying, energy signals are emitted from multiple destinations when multiple sources are sending their information signals to relay. With power splitting and unlimited antennas at relay, asymptotic expression of harvested energy is derived. The analysis reveals that asymptotic harvested energy is independent of fast fading effect of wireless channels; meanwhile transmission powers of each source and destination can be scaled down inversely proportional to the number of relay antennas. To significantly reduce energy leakage interference and multipair interference, zero-forcing processing and maximum-ratio combing/maximum-ratio transmission are employed at relay. Fundamental trade-off between harvested energy and achievable sum rate is quantified. It is shown that asymptotic sum rate is neither convex nor concave with respect to power splitting and destination transmission power. Thus, a one-dimensional embedded bisection algorithm is proposed to jointly determine the optimal power splitting and destination transmission power. It shows that destination-aided SWIPT are beneficial for harvesting energy and increasing sum rate. The significant sum rate improvements of the proposed schemes are verified by numerical results.

  20. Reliability Analysis of Differential Relay as Main Protection Transformer Using Fuzzy Logic Algorithm

    Science.gov (United States)

    Mulyadi, Y.; Sucita, T.; Sumarto; Alpani, M.

    2018-02-01

    Electricity supply demand is increasing every year. It makes PT. PLN (Persero) is required to provide optimal customer service and satisfaction. Optimal service depends on the performance of the equipment of the power system owned, especially the transformer. Power transformer is an electrical equipment that transforms electricity from high voltage to low voltage or vice versa. However, in the electrical power system, is inseparable from interference included in the transformer. But, the disturbance can be minimized by the protection system. The main protection transformer is differential relays. Differential relays working system using Kirchoff law where inflows equal outflows. If there are excessive currents that interfere then the relays will work. But, the relay can also experience decreased performance. Therefore, this final project aims to analyze the reliability of the differential relay on the transformer in three different substations. Referring to the standard applied by the transmission line protection officer, the differential relay shall have slope characteristics of 30% in the first slope and 80% in the second slope when using two slopes and 80% when using one slope with an instant time and the corresponding ratio. So, the results obtained on the Siemens differential release have a reliable slope characteristic with a value of 30 on the fuzzy logic system. In a while, ABB a differential relay is only 80% reliable because two experiments are not reliable. For the time, all the differential relays are instant with a value of 0.06 on the fuzzy logic system. For ratios, the differential relays ABB have a better value than others brand with a value of 151 on the fuzzy logic system.

  1. Performance Analysis of Virtual MIMO Relaying Schemes Based on Detect–Split–Forward

    KAUST Repository

    Al-Basit, Suhaib M.

    2014-10-29

    © 2014, Springer Science+Business Media New York. Virtual multi-input multi-output (vMIMO) schemes in wireless communication systems improve coverage, throughput, capacity, and quality of service. In this paper, we propose three uplink vMIMO relaying schemes based on detect–split–forward (DSF). In addition, we investigate the effect of several physical parameters such as distance, modulation type and number of relays. Furthermore, an adaptive vMIMO DSF scheme based on VBLAST and STBC is proposed. In order to do that, we provide analytical tools to evaluate the performance of the propose vMIMO relaying scheme.

  2. Relay-assisted Network Coding Multicast in the Presence of Neighbours

    DEFF Research Database (Denmark)

    Khamfroush, Hana; Roetter, Daniel Enrique Lucani; Pahlevani, Peyman

    2015-01-01

    We study the problem of minimizing the cost of packet transmission from a source to two receivers with the help of a relay and using network coding in wireless mesh networks consisting of many active neighbours sharing the same channel. The cost minimization problem is modeled as a Markov Decision...... Process (MDP) and analysed under different network conditions. Two simple heuristics are proposed to estimate the appropriate time for activating the relay to provide close-to-optimal performance. Our numerical results show that a judicious network coding enabled relay can bring up to 2.9x gains...

  3. Effect of the Primary User Traffic on Cognitive Relaying with Adaptive Transmission

    KAUST Repository

    Rao, Anlei

    2012-09-08

    In a cognitive-relay system, the secondary user is permitted to transmit data via a relay when the spectrum bands are detected to be free. The miss detection of spectrum sensing and the primary user traffic will affect the data transmission performance of the secondary user. In this paper, we investigate the impact of the status change of the primary user on the bit error rate (BER) of the adaptive transmission of the secondary user in a cognitive-relay system. Numerical results show that the primary user traffic can significantly degrade the BER of the secondary user transmission.

  4. 78 FR 53684 - Misuse of Internet Protocol (IP) Captioned Telephone Service; Telecommunications Relay Services...

    Science.gov (United States)

    2013-08-30

    ...In this document, the Commission adopts permanent rules addressing marketing, labeling, registration and default equipment- setting requirements for internet protocol captioned telephone relay service (IP CTS). This action is necessary to ensure that persons with hearing disabilities have access to telecommunications relay services (TRS) that address their needs in an efficient manner, in furtherance of the objectives of section 225 of the Communications Act of 1934, as amended (Act), to provide relay services enabling communication that is functionally equivalent to conventional telephone voice services, while at the same time protecting the TRS Fund for all forms of TRS.

  5. Detection of vulnerable relays and sensitive controllers under cascading events based on performance indices

    DEFF Research Database (Denmark)

    Liu, Zhou; Chen, Zhe; Hu, Yanting

    2014-01-01

    The unexpected relay operations have been regarded as one of main reasons to propagate and induce the cascaded blackouts. It is significant to timely detect vulnerable relays to be blocked, and locate sensitive controllers to regulate the emergency states. In this paper, a multi agent system (MAS...... instability induced cascaded blackout built in real time digital simulator (RTDS) will be used to demonstrate the proposed strategy. The simulation results indicate this strategy can effectively detect the vulnerable relays and sensitive controllers under overloading situations....

  6. NRC Information No. 88-14: Potential problems with electrical relays

    International Nuclear Information System (INIS)

    Rossi, C.E.

    1992-01-01

    This information notice is being provided to alert recipients to potential problems involving HFA, PVD 21B, PVD 21D, and HGA relays manufactured by General Electric Company (GE), as described below. Although some of these problems are several years old, they are included because utilities are still identifying problems discovered while implementing advice issued by GE in the early 1980s. The specific problem with the HFA relays concerns mechanical binding in the relay caused by incorrect location of a stop tab that is welded to the armature. The problems with the PVD 21B, PVD 21D, and HGA concern their seismic capability

  7. On the performance of spectrum sharing systems with two-way relaying and multiuser diversity

    KAUST Repository

    Yang, Liang

    2012-08-01

    In this letter, we consider a spectrum sharing network with two-way relaying and multi-user diversity. More specifically, one secondary transmitter with the best channel quality is selected and splits its partial power to relay its received signals to the primary users by using the amplify-and-forward relaying protocol. We derive a tight approximation for the resulting outage probability. Based on this formula, the performance of the spectral sharing region and the cell coverage are analyzed. Numerical results are given to verify our analysis and are discussed to illustrate the advantages of our newly proposed scheme. © 1997-2012 IEEE.

  8. Incorporating Multiple Energy Relay Dyes in Liquid Dye-Sensitized Solar Cells

    KAUST Repository

    Yum, Jun-Ho

    2011-01-05

    Panchromatic response is essential to increase the light-harvesting efficiency in solar conversion systems. Herein we show increased light harvesting from using multiple energy relay dyes inside dye-sensitized solar cells. Additional photoresponse from 400-590 nm matching the optical window of the zinc phthalocyanine sensitizer was observed due to Förster resonance energy transfer (FRET) from the two energy relay dyes to the sensitizing dye. The complementary absorption spectra of the energy relay dyes and high excitation transfer efficiencies result in a 35% increase in photovoltaic performance. © 2011 Wiley-VCH Verlag GmbH& Co. KGaA.

  9. A TorPath to TorCoin: Proof-of-Bandwidth Altcoins for Compensating Relays

    Science.gov (United States)

    2014-07-18

    incentive scheme for Tor relying on two novel concepts. We introduce TorCoin, an “altcoin” that uses the Bitcoin protocol to re- ward relays for...or altcoin, based on the Bitcoin protocol [8]. Unlike Bitcoin , its proof-of-work scheme is based on bandwidth rather than computation. To “mine” a...concepts. We introduce TorCoin, an altcoin" that uses the Bitcoin protocol to re- ward relays for contributing bandwidth. Relays mine" TorCoins, then

  10. Anion gap, anion gap corrected for albumin, base deficit and unmeasured anions in critically ill patients: implications on the assessment of metabolic acidosis and the diagnosis of hyperlactatemia.

    Science.gov (United States)

    Chawla, Lakhmir S; Shih, Shirley; Davison, Danielle; Junker, Christopher; Seneff, Michael G

    2008-12-16

    Base deficit (BD), anion gap (AG), and albumin corrected anion gap (ACAG) are used by clinicians to assess the presence or absence of hyperlactatemia (HL). We set out to determine if these tools can diagnose the presence of HL using cotemporaneous samples. We conducted a chart review of ICU patients who had cotemporaneous arterial blood gas, serum chemistry, serum albumin (Alb) and lactate(Lac) levels measured from the same sample. We assessed the capacity of AG, BD, and ACAG to diagnose HL and severe hyperlactatemia (SHL). HL was defined as Lac > 2.5 mmol/L. SHL was defined as a Lac of > 4.0 mmol/L. From 143 patients we identified 497 series of lab values that met our study criteria. Mean age was 62.2 +/- 15.7 years. Mean Lac was 2.11 +/- 2.6 mmol/L, mean AG was 9.0 +/- 5.1, mean ACAG was 14.1 +/- 3.8, mean BD was 1.50 +/- 5.4. The area under the curve for the ROC for BD, AG, and ACAG to diagnose HL were 0.79, 0.70, and 0.72, respectively. AG and BD failed to reliably detect the presence of clinically significant hyperlactatemia. Under idealized conditions, ACAG has the capacity to rule out the presence of hyperlactatemia. Lac levels should be obtained routinely in all patients admitted to the ICU in whom the possibility of shock/hypoperfusion is being considered. If an AG assessment is required in the ICU, it must be corrected for albumin for there to be sufficient diagnostic utility.

  11. Macropolyhedral boron-containing cluster chemistry. A metallathiaborane from S2B17H17: Isolation and characterisation of [(PMe2Ph)(2)PtS2B16H16]; A neo-arachno ten-vertex cluster shape, and the constitution of the [arachno-B10H15](-) anion(+)

    Czech Academy of Sciences Publication Activity Database

    Carr, MJ.; Londesborough, Michael Geoffrey Stephen; Bould, J.; Císařová, I.; Štíbr, Bohumil; Kennedy, JD.

    2005-01-01

    Roč. 70, č. 4 (2005), s. 430-440 ISSN 0010-0765 R&D Projects: GA ČR(CZ) GA203/05/2646 Grant - others:EPSRC(GB) J/56929; EPSRC(GB) K/05818; EPSRC(GB) L/49505 Institutional research plan: CEZ:AV0Z40320502 Keywords : macropolyhedral * neo-arachno ten-vertex cluster * X-ray diffraction Subject RIV: CA - Inorganic Chemistry Impact factor: 0.949, year: 2005

  12. Interstellar chemistry

    Science.gov (United States)

    Klemperer, William

    2006-01-01

    In the past half century, radioastronomy has changed our perception and understanding of the universe. In this issue of PNAS, the molecular chemistry directly observed within the galaxy is discussed. For the most part, the description of the molecular transformations requires specific kinetic schemes rather than chemical thermodynamics. Ionization of the very abundant molecular hydrogen and atomic helium followed by their secondary reactions is discussed. The rich variety of organic species observed is a challenge for complete understanding. The role and nature of reactions involving grain surfaces as well as new spectroscopic observations of interstellar and circumstellar regions are topics presented in this special feature. PMID:16894148

  13. Theoretical chemistry periodicities in chemistry and biology

    CERN Document Server

    Eyring, Henry

    1978-01-01

    Theoretical Chemistry: Periodicities in Chemistry and Biology, Volume 4 covers the aspects of theoretical chemistry. The book discusses the stably rotating patterns of reaction and diffusion; the chemistry of inorganic systems exhibiting nonmonotonic behavior; and population cycles. The text also describes the mathematical modeling of excitable media in neurobiology and chemistry; oscillating enzyme reactions; and oscillatory properties and excitability of the heart cell membrane. Selected topics from the theory of physico-chemical instabilities are also encompassed. Chemists, mechanical engin

  14. Ternary Complexation on Bacterial Surfaces: Implications for Subsurface Anion Transport

    Science.gov (United States)

    Maclean, L. C.; Higginbottom, C. M.; Fowle, D. A.

    2002-12-01

    The physical, chemical, and biological controls on contaminant mobilities in aquatic ecosystems must be determined to establish the threat that contamination poses to the environment. Quantitative models of contaminant mobilities are required as a prerequisite to guide remediation efforts and to prioritize the potential hazard to the ecosystem of each contaminated site. It is well established that mineral surface adsorption is an important control on contaminant mobilities, and many studies have utilized thermodynamics to quantify metal/organic adsorption in order to yield predictive models of contaminant transport. However, these models of contaminant transport may not be representative of the reactions which control contaminant mobilities as most mineral surfaces are coated with organic acids, bacteria, and extracellular polymers. Numerous laboratory studies have demonstrated that bacterial cell walls have a high affinity for binding metal cations, and field studies indicate that a significant proportion of bacteria cells and associated extracellular matrices are coated with small scale hydrous metal oxides. The small size of bacteria, and in many cases the nanoscale of their associated mineral phases, suggests these bacteria-mineral composites may represent a large proportion of surface area exposed to fluid flow. Therefore, due to the affinity of bacterial cell walls for cations and biominerals, bacteria may also have a significant impact on anionic contaminant mobility in many natural systems. The extent of metal-bacteria adsorption reactions varies drastically as a function of pH and solution chemistry. Current adsorption models have focused on the interactions of positively charged metal cations with bacterial surfaces, however in many oxidizing environments metals such as Cr exist as anions or anionic complexes. We have studied the ability of non-metabolizing cells of the bacterial species Bacillus subtilis and Shewanella putrifaciens to adsorb aqueous Cr

  15. Competition between photodetachment and autodetachment of the 21ππ* state of the green fluorescent protein chromophore anion

    International Nuclear Information System (INIS)

    Mooney, Ciarán R. S.; Parkes, Michael A.; Zhang, Lijuan; Hailes, Helen C.; Fielding, Helen H.; Simperler, Alexandra; Bearpark, Michael J.

    2014-01-01

    Using a combination of photoelectron spectroscopy measurements and quantum chemistry calculations, we have identified competing electron emission processes that contribute to the 350–315 nm photoelectron spectra of the deprotonated green fluorescent protein chromophore anion, p-hydroxybenzylidene-2,3-dimethylimidazolinone. As well as direct electron detachment from S 0 , we observe resonant excitation of the 2 1 ππ* state of the anion followed by autodetachment. The experimental photoelectron spectra are found to be significantly broader than photoelectron spectrum calculated using the Franck-Condon method and we attribute this to rapid (∼10 fs) vibrational decoherence, or intramolecular vibrational energy redistribution, within the neutral radical

  16. Correction of the anion gap for albumin in order to detect occult tissue anions in shock.

    Science.gov (United States)

    Hatherill, M; Waggie, Z; Purves, L; Reynolds, L; Argent, A

    2002-12-01

    It is believed that hypoalbuminaemia confounds interpretation of the anion gap (AG) unless corrected for serum albumin in critically ill children with shock. To compare the ability of the AG and the albumin corrected anion gap (CAG) to detect the presence of occult tissue anions. Prospective observational study in children with shock in a 22 bed multidisciplinary paediatric intensive care unit of a university childrenrsquo;s hospital. Blood was sampled at admission and at 24 hours, for acid-base parameters, serum albumin, and electrolytes. Occult tissue anions (lactate + truly "unmeasured" anions) were calculated from the strong ion gap. The anion gap ((Na + K) - (Cl + bicarbonate)) was corrected for serum albumin using the equation of Figge: AG + (0.25 x (44 - albumin)). Occult tissue anions (TA) predicted by the anion gap were calculated by (anion gap - 15 mEq/l). Optimal cut off values of anion gap were compared by means of receiver operating characteristic (ROC) curves. Ninety three sets of data from 55 children (median age 7 months, median weight 4.9 kg) were analysed. Data are expressed as mean (SD), and mean bias (limits of agreement). The incidence of hypoalbuminaemia was 76% (n = 42/55). Mean serum albumin was 25 g/l (SD 8). Mean AG was 15.0 mEq/l (SD 6.1), compared to the CAG of 19.9 mEq/l (SD 6.6). Mean TA was 10.2 mmol/l (SD 6.3). The AG underestimated TA with mean bias 10.2 mmol/l (4.1-16.1), compared to the CAG, mean bias 5.3 mmol/l (0.4-10.2). A clinically significant increase of TA >5 mmol/l was present in 83% (n = 77/93) of samples, of which the AG detected 48% (n = 36/77), and the CAG 87% (n = 67/77). Post hoc ROC analysis revealed optimal cut off values for detection of TA >5 mmol/l to be AG >10 mEq/l, and CAG >15.5 mEq/l. Hypoalbuminaemia is common in critically ill children with shock, and is associated with a low observed anion gap that may fail to detect clinically significant amounts of lactate and other occult tissue anions. We suggest that

  17. 1,2,3-Triazoles and the Expanding Utility of Charge Neutral CH···Anion Interactions

    Science.gov (United States)

    McDonald, Kevin P.; Hua, Yuran; Flood, Amar H.

    As the field of anion supramolecular chemistry continues to grow in its sophistication and understanding of the noncovalent interactions used to effectively bind anions, there exists new theoretical and experimental evidence for a necessary reexamination of the way in which the field views hydrogen bond donors. The heteroatom based hydrogen-bond donors (e.g., NH and OH) are well-known to provide strong stabilization to negatively charged species. However, new findings point to the untapped stabilization energy that lay dormant in extrinsically-activated CH hydrogen bonds. Computational studies showed that an activated aliphatic or aromatic CH can provide an amount of anion stabilization in the gas phase approaching that of conventional NH based donors. Discovery of the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition to provide 1,2,3-triazoles and the ability to readily "click" this functionality into anion receptors has allowed extensive experimental investigation of the ideas posed by these calculations. This chapter will focus on the evolution of the CH hydrogen bond from being viewed as a weak, secondary interaction to now being utilized as a powerful source of anion stabilization in macrocyclic and oligomeric receptors. In addition, the application of the anion binding power of the 1,2,3-triazole towards the preparation of mechanically interlocked structures will also be discussed.

  18. A Novel Design of Radio Frequency Energy Relays on Power Transmission Lines

    Directory of Open Access Journals (Sweden)

    Jin Tong

    2016-06-01

    Full Text Available In this paper, we investigate the energy problem of monitoring sensors on high-voltage power transmission lines and propose a wireless charging scheme for a Radio Frequency IDentification (RFID sensor tag to solve a commercial efficiency problem: the maintenance-caused power outage. Considering the environmental influences on power transmission lines, a self-powered wireless energy relay is designed to meet the energy requirement of the passive RFID sensor tag. The relay can obtain the electric field energy from the transmission lines and wirelessly power the RFID sensor tags around for longer operating distance. A prototype of the energy relay is built and tested on a 110 kv line. The measurement results show that the energy relay can provide stable energy even with the influences of wind, noise and power outage. To our knowledge, it is the first work to power the RFID sensor tags on power transmission lines.

  19. Development of an adaptive optics test-bed for relay mirror applications

    Science.gov (United States)

    Mansell, Justin D.; Jacobs, Arturo A.; Maynard, Morris

    2005-08-01

    The relay mirror concept involves deploying a passive optical station at a high altitude for relaying a beam from a laser weapon to a target. Relay mirrors have been proposed as a method of increasing the range of laser weapons that is less costly than deploying a larger number of laser weapons. Relay mirrors will only be effective if the beam spreading and beam quality degradation induced by atmospheric aberrations and thermal blooming can be mitigated. In this paper we present the first phase of a multi-year effort to develop a theoretical and experimental capability at Boeing-SVS to study these problems. A team from MZA and Boeing-SVS has developed a laboratory test-bed consisting of a distributed atmospheric path simulated by three liquid crystal phase screens, a Shack-Hartmann wavefront sensor, and a MEMS membrane deformable mirror. We present results of AO component calibration and evaluation, the system construction, and the system performance.

  20. Energy-efficient cooperative protocols for full-duplex relay channels

    KAUST Repository

    Khafagy, Mohammad Galal

    2013-12-01

    In this work, energy-efficient cooperative protocols are studied for full-duplex relaying (FDR) with loopback interference. In these protocols, relay assistance is only sought under certain conditions on the different link outages to ensure effective cooperation. Recently, an energy-efficient selective decode-And-forward protocol was proposed for FDR, and was shown to outperform existing schemes in terms of outage. Here, we propose an incremental selective decode-And-forward protocol that offers additional power savings, while keeping the same outage performance. We compare the performance of the two protocols in terms of the end-to-end signal-to-noise ratio cumulative distribution function via closed-form expressions. Finally, we corroborate our theoretical results with simulation, and show the relative relay power savings in comparison to non-selective cooperation in which the relay cooperates regardless of channel conditions. © 2013 IEEE.

  1. Novel half-coherent receivers for amplify-and-forward relaying

    KAUST Repository

    Khan, Fahd Ahmed

    2012-06-01

    Consider a system in which the signal is transmitted from the source to the destination via an amplify-and-forward relay. For such a system, we derive in this paper, novel receivers that have complete knowledge of either the source-relay link or the relay-destination link. These receivers are termed as, \\'half-coherent receivers\\' as they have channel-state-information (CSI) of only one of two links. These receivers can be very useful in a system in which only the relay can afford high complexity by having a channel estimation module and the destination is unable to support channel estimation or a system in which only the destination can afford higher complexity and includes the channel estimation module. The analytical bit-error-rate (BER) performances of the proposed receivers are derived for Rician fading. Numerical results show considerable performance gains of the new receivers, especially at low signal-to-noise ratio. © 2012 IEEE.

  2. Joint Linear Filter Design in Multiuser Cooperative Nonregenerative MIMO Relay Systems

    Directory of Open Access Journals (Sweden)

    Gen Li

    2009-01-01

    Full Text Available This paper addresses the filter design issues for multiuser cooperative nonregenerative MIMO relay systems in both downlink and uplink scenarios. Based on the formulated signal model, the filter matrix optimization is first performed for direct path and relay path respectively, aiming to minimize the mean squared error (MSE. To be more specific, for the relay path, we derive the local optimal filter scheme at the base station and the relay station jointly in the downlink scenario along with a more practical suboptimal scheme, and then a closed-form joint local optimal solution in the uplink scenario is exploited. Furthermore, the optimal filter for the direct path is also presented by using the exiting results of conventional MIMO link. After that, several schemes are proposed for cooperative scenario to combine the signals from both paths. Numerical results show that the proposed schemes can reduce the bit error rate (BER significantly.

  3. Achievable Rates of Buffer-Aided Full-Duplex Gaussian Relay Channels

    KAUST Repository

    El Shafie, Ahmed

    2017-10-18

    We derive closed-form expressions for the achievable rates of a buffer-aided full-duplex (FD) multiple-input multipleoutput (MIMO) Gaussian relay channel. The FD relay still suffers from residual self-interference (RSI) after the application of self-interference mitigation techniques. We investigate both cases of a slow-RSI channel where the RSI is fixed over the entire codeword, and a fast-RSI channel where the RSI changes from one symbol duration to another within the codeword. We show that the RSI can be completely eliminated in the slow-RSI case when the FD relay is equipped with a buffer while the fast RSI cannot be eliminated. For the fixed-rate data transmission scenario, we derive the optimal transmission strategy that should be adopted by the source node and relay node to maximize the system throughput. We verify our analytical findings through simulations.

  4. 78 FR 28633 - TE Connectivity, a Subsidiary of Tyco Electronics Corporation, Relay Products Business Unit...

    Science.gov (United States)

    2013-05-15

    ... transformers. The notice was published in the Federal Register on April 1, 2013 (78 FR 19532). At the request... electromechanical relays, contactors and transformers to a foreign country. Based on these findings, the Department...

  5. 78 FR 54201 - Misuse of Internet Protocol (IP) Captioned Telephone Service; Telecommunications Relay Services...

    Science.gov (United States)

    2013-09-03

    ...In this document, the Commission seeks comment on further possible actions necessary to improve internet protocol captioned telephone relay service (IP CTS), to ensure that it is used exclusively by eligible individuals, and to develop a better methodology for calculating the compensation rate paid to IP CTS providers. This action is necessary to ensure that persons with hearing disabilities have access to relay services that address their unique needs, in furtherance of the objectives of section 225 of the Communications Act of 1934, as amended (Act), to provide relay services in a manner that is functionally equivalent to conventional telephone voice services, while at the same time protecting the interstate telecommunications relay service (TRS) Fund for all forms of TRS.

  6. Error-rate performance analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2010-10-01

    In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive a closed-form expression for the end-to-end biterror rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact probability density function (PDF) of each hop. Furthermore, we evaluate the asymptotic error performance and the diversity order is deduced. We show that performance simulation results coincide with our analytical results. ©2010 IEEE.

  7. On network coding and modulation mapping for three-phase bidirectional relaying

    KAUST Repository

    Chang, Ronald Y.

    2015-12-03

    © 2015 IEEE. In this paper, we consider the network coding (NC) enabled three-phase protocol for information exchange between two users in a wireless two-way (bidirectional) relay network. Modulo-based (nonbinary) and XOR-based (binary) NC schemes are considered as information mixture schemes at the relay while all transmissions adopt pulse amplitude modulation (PAM). We first obtain the optimal constellation mapping at the relay that maximizes the decoding performance at the users for each NC scheme. Then, we compare the two NC schemes, each in conjunction with the optimal constellation mapping at the relay, in different conditions. Our results demonstrate that, in the low SNR regime, binary NC outperforms nonbinary NC with 4-PAM, while they have mixed performance with 8-PAM. This observation applies to quadrature amplitude modulation (QAM) composed of two parallel PAMs.

  8. Achievable Rate of Multi-relay Cognitive Radio MIMO Channel with Space Alignment

    KAUST Repository

    Sboui, Lokman

    2015-04-21

    We study the impact of multiple relays on the primary user (PU) and secondary user (SU) rates of underlay MIMO cognitive radio. Both users exploit amplify-and-forward relays to communicate with the destination. A space alignment technique and a special linear precoding and decoding scheme are applied to allow the SU to use the resulting free eigenmodes. In addition, the SU can communicate over the used eigenmodes under the condition of respecting an interference constraint tolerated by the PU. At the destination, a successive interference cancellation (SIC) is performed to estimate the secondary signal. We present the explicit expressions of the optimal PU and SU powers that maximize their achievable rates. In the numerical results, we show that our scheme provides cognitive rate gain even in absence of tolerated interference. In addition, we show that increasing the number of relays enhances the PU and SU rates at low power regime and/or when the relays power is sufficiently high.

  9. Error-rate performance analysis of incremental decode-and-forward opportunistic relaying

    KAUST Repository

    Tourki, Kamel

    2011-06-01

    In this paper, we investigate an incremental opportunistic relaying scheme where the selected relay chooses to cooperate only if the source-destination channel is of an unacceptable quality. In our study, we consider regenerative relaying in which the decision to cooperate is based on a signal-to-noise ratio (SNR) threshold and takes into account the effect of the possible erroneously detected and transmitted data at the best relay. We derive a closed-form expression for the end-to-end bit-error rate (BER) of binary phase-shift keying (BPSK) modulation based on the exact probability density function (PDF) of each hop. Furthermore, we evaluate the asymptotic error performance and the diversity order is deduced. We show that performance simulation results coincide with our analytical results. © 2011 IEEE.

  10. Efficient power allocation for fixed-gain amplify-and-forward relaying in rayleigh fading

    KAUST Repository

    Zafar, Ammar

    2013-06-01

    In this paper, we study power allocation strategies for a fixed-gain amplify-and-forward relay network employing multiple relays. We consider two optimization problems for the relay network: 1) optimal power allocation to maximize the end-to-end signal-to-noise ratio (SNR) and 2) minimizing the total consumed power while maintaining the end-to-end SNR over a threshold value. We assume that the relays have knowledge of only the channel statistics of all the links. We show that the SNR maximization problem is concave and the power minimization problem is convex. Hence, we solve the problems through convex programming. Numerical results show the benefit of allocating power optimally rather than uniformly. © 2013 IEEE.

  11. Communications Relay and Human-Assisted Sample Return from the Deep Space Gateway

    Science.gov (United States)

    Cichan, T.; Hopkins, J. B.; Bierhaus, B.; Murrow, D. W.

    2018-02-01

    The Deep Space Gateway can enable or enhance exploration of the lunar surface through two capabilities: 1. communications relay, opening up access to the lunar farside, and 2. sample return, enhancing the ability to return large sample masses.

  12. The Impact of TCSC on IDMT Relays in SLG Fault in Distribution Networks

    Directory of Open Access Journals (Sweden)

    Lazhar Bougouffa

    2016-03-01

    Full Text Available IDMT Directional Over-Current Relays protection is one of the basic protective relaying for distribution systems, for fault detection and clearing as soon as possible. Its function would generally be changed in presence of FACTS devices. In this paper a study to investigate the direct effect of varying reactance of the TCSC on single-line-to-ground (SLG fault in compensated distribution systems. This paper, therefore presents the calculation of fault component, and directional over-current relay operating time characteristics for phase-to-earth fault involving the TCSC. The case study is compared between compensated and uncompensated system. The coordination of the relays is a nonlinear programming problem and it is solved by using MATLAB software.

  13. Effects of Distributed Generation on Overcurrent Relay Coordination and an Adaptive Protection Scheme

    Science.gov (United States)

    Ilik, Semih C.; Arsoy, Aysen B.

    2017-07-01

    Integration of distributed generation (DG) such as renewable energy sources to electrical network becomes more prevalent in recent years. Grid connection of DG has effects on load flow directions, voltage profile, short circuit power and especially protection selectivity. Applying traditional overcurrent protection scheme is inconvenient when system reliability and sustainability are considered. If a fault happens in DG connected network, short circuit contribution of DG, creates additional branch element feeding the fault current; compels to consider directional overcurrent (OC) protection scheme. Protection coordination might get lost for changing working conditions when DG sources are connected. Directional overcurrent relay parameters are determined for downstream and upstream relays when different combinations of DG connected singular or plural, on radial test system. With the help of proposed flow chart, relay parameters are updated and coordination between relays kept sustained for different working conditions in DigSILENT PowerFactory program.

  14. Mutual Information of Buffer-Aided Full-Duplex Relay Channels

    KAUST Repository

    Shafie, Ahmed El

    2017-04-09

    We derive closed-form expressions for the achievable rates of a buffer-aided full-duplex (FD) multiple-input multiple-output (MIMO) Gaussian relay channel. The FD relay still suffers from residual self-interference (RSI) after the application of self-interference mitigation techniques. We investigate both cases of a slow-RSI channel where the RSI is fixed over the entire codeword, and a fast-RSI channel where the RSI changes from one symbol duration to another within the codeword. We show that the RSI can be completely eliminated in the slow-RSI case when the FD relay is equipped with a buffer while the fast RSI cannot be eliminated. For the fixed-rate data transmission scenario, we derive the optimal transmission strategy that should be adopted by the source node and relay node to maximize the system throughput. We verify our analytical findings through simulations.

  15. Wireless Powered Cooperative Communications: Power Splitting Relaying With Energy Accumulation (Author’s Manuscript)

    Science.gov (United States)

    2016-03-21

    ar X iv :1 60 1. 00 37 4v 1 [ cs .I T ] 4 J an 2 01 6 IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 34, NO. X, JAN. 2016 1 Wireless ... wireless - powered multi-relay cooperative networks in this paper. Dif- ferent from the conventional battery-free PS relaying strategy, harvested...operations including the charging and discharging. To this end, PS and battery operations are coupled with distributed beamforming. A throughput

  16. Transformer Protection by Using FL Based Artificial Intelligent Buchholz Relay against Incipient Faults

    OpenAIRE

    SOUMYADEEP SAMONTO; SAGARIKA PAL; SUBRATA BANERJEE; BISHAL SARKAR

    2016-01-01

    Switchgear and Protection are the two vital terminology of Electrical power system. Normally the components of any switchgear needs better protection schemes to be set for a composite power system. Many explorers worked on artificial intelligent breaker but an indulgence of fuzzy theory is nevertheless very absent in case of buchholz relay. Here in this paper discussion has been drawn in favor of the Artificial Intelligent Buchholz (AIB) relay where inputs are level of transformer oil and ...

  17. Performance Analysis of Relays in LTE for a Realistic Suburban Deployment Scenario

    DEFF Research Database (Denmark)

    Coletti, Claudio; Mogensen, Preben; Irmer, Ralf

    2011-01-01

    scenario with real Macro site positions, user density map and spectrum band availability. Based on a proposed heuristic deployment algorithm, results show that deploying In-band relays can significantly reduce the user outage if high backhaul link quality is ensured, whereas Out-band relaying and the usage...... of a lower frequency carrier at the Macro layer guarantee better network coverage and capacity improvements....

  18. DNAzyme Feedback Amplification: Relaying Molecular Recognition to Exponential DNA Amplification.

    Science.gov (United States)

    Liu, Meng; Yin, Qingxin; McConnell, Erin M; Chang, Yangyang; Brennan, John D; Li, Yingfu

    2018-03-26

    Technologies capable of linking DNA amplification to molecular recognition are very desirable for ultrasensitive biosensing applications. We have developed a simple but powerful isothermal DNA amplification method, termed DNAzyme feedback amplification (DFA), that is capable of relaying molecular recognition to exponential DNA amplification. The method incorporates both an RNA-cleaving DNAzyme (RCD) and rolling circle amplification (RCA) carried out by a special DNA polymerase using a circular DNA template. DFA begins with a stimulus-dependent RCA reaction, producing tandemly linked RCDs in long-chain DNA products. These RCDs cleave an RNA-containing DNA sequence to form additional primers that hybridize to the circular DNA molecule, giving rise to DNA assemblies that act as the new inputs for RCA. The RCA reaction and the cleavage event keep on feeding each other autonomously, resulting in exponential growth of repetitive DNA sequences that can be easily detected. This method can be used for the detection of both nucleic acid based targets and non-nucleic acid analytes. In this article, we discuss the conceptual framework of the feedback amplification approach, the essential features of this method as well as remaining challenges and possible solutions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Rumor has it...: relay communication of stress cues in plants.

    Science.gov (United States)

    Falik, Omer; Mordoch, Yonat; Quansah, Lydia; Fait, Aaron; Novoplansky, Ariel

    2011-01-01

    Recent evidence demonstrates that plants are able not only to perceive and adaptively respond to external information but also to anticipate forthcoming hazards and stresses. Here, we tested the hypothesis that unstressed plants are able to respond to stress cues emitted from their abiotically-stressed neighbors and in turn induce stress responses in additional unstressed plants located further away from the stressed plants. Pisum sativum plants were subjected to drought while neighboring rows of five unstressed plants on both sides, with which they could exchange different cue combinations. On one side, the stressed plant and its unstressed neighbors did not share their rooting volumes (UNSHARED) and thus were limited to shoot communication. On its other side, the stressed plant shared one of its rooting volumes with its nearest unstressed neighbor and all plants shared their rooting volumes with their immediate neighbors (SHARED), allowing both root and shoot communication. Fifteen minutes following drought induction, significant stomatal closure was observed in both the stressed plants and their nearest unstressed SHARED neighbors, and within one hour, all SHARED neighbors closed their stomata. Stomatal closure was not observed in the UNSHARED neighbors. The results demonstrate that unstressed plants are able to perceive and respond to stress cues emitted by the roots of their drought-stressed neighbors and, via 'relay cuing', elicit stress responses in further unstressed plants. Further work is underway to study the underlying mechanisms of this new mode of plant communication and its possible adaptive implications for the anticipation of forthcoming abiotic stresses by plants.

  20. CERN Relay Race: The Shabbys again, but only just!

    CERN Multimedia

    2006-01-01

    Gregor Grawer of the Shabbys bringing his team to a narrow victory over ALICE - Out of Control. The sun was shining as the start was given for this year's CERN Relay Race with a record 65 teams at the starting line. 'ALICE - Out of Control' held an impressive lead from the start but were eventually overtaken in the last 300 metres by the Shabbys. In doing so, they claimed their sixth consecutive victory with a time of 10 min 39,9 sec, the fastest they have ever run. This year for the first time a new trophy was awarded for the fastest woman at the 1000 metres line which was won by Helenka Przysiezniak of the Running Athenas, while the men's trophy went to Marc Magrans de Abril of ALICE - Out of Control in 2 min 45 sec. The good weather contributed to the festive atmosphere as runners and spectators relaxed on the lawn of Restaurant No. 1 accompanied by music by the CERN Jazz Club's excellent 'Pink Symbolic Stompers'. The CERN Audiovisual Service and the 'Open Your Eyes' filmmaking club were on hand to recor...