241 research outputs found
A cross-layer approach to enhance QoS for multimedia applications over satellite
No full textThe need for on-demand QoS support for communications over satellite is of primary importance for distributed multimedia applications. This is particularly true for the return link which is often a bottleneck due to the large set of end-users accessing a very limited uplink resource. Facing this need, Demand Assignment Multiple Access (DAMA) is a classical technique that allows satellite operators to offer various types of services, while managing the resources of the satellite system efficiently. Tackling the quality degradation and delay accumulation issues that can result from the use of these techniques, this paper proposes an instantiation of the Application Layer Framing (ALF) approach, using a cross-layer interpreter(xQoS-Interpreter). The information provided by this interpreter is used to manage the resource provided to a terminal by the satellite system in order to improve the quality of multimedia presentations from the end users point of view. Several experiments are carried out for different loads on the return link. Their impact on QoS is measured through different application as well as network level metrics
Half-Sandwich Alkyl, Amido, and Iodo Samarium(II) Complexes: Non-Conventional Sterically Governed Oxidation of (tBu(4)Carb)(2)Sm
No full textbibtex: ISI:000395753300031 bibtex\location:'POSTFACH 101161, 69451 WEINHEIM, GERMANY',publisher:'WILEY-V C H VERLAG GMBH',type:'Article',affiliation:'Trifonov, AA (Reprint Author), Russian Acad Sci, Inst Organometall Chem, Tropinina 49,GSP 445, Nizhnii Novgorod 630950, Russia. Trifonov, AA (Reprint Author), Russian Acad Sci, Inst Organoelement Cpds, Vavilova str 28, Moscow 119334, Russia. Selikhov, Alexander N.; Mahrova, Tatyana V.; Cherkasov, Anton V.; Fukin, Georgy K.; Trifonov, Alexander A., Russian Acad Sci, Inst Organometall Chem, Tropinina 49,GSP 445, Nizhnii Novgorod 630950, Russia. Maron, Laurent, Univ Toulouse, CNRS, INSA, UPS,UMR 5215, Ave Rangueil 135, F-31077 Toulouse, France. Trifonov, Alexander A., Russian Acad Sci, Inst Organoelement Cpds, Vavilova str 28, Moscow 119334, Russia.','author-email':'[email protected]',da:'2018-12-05','doc-delivery-number':'EN1EM',eissn:'1521-3765','funding-acknowledgement':'Russian Foundation for Basic Research [14-03-00527, 16-33-00041]','funding-text':'The Russian Foundation for Basic Research (Projects 14-03-00527 and 16-33-00041) is acknowledged for the financial support of this work.','journal-iso':'Chem.-Eur. J.','keywords-plus':'HIGHLY REACTIVE ORGANOLANTHANIDES; RAY CRYSTAL-STRUCTURE; INTRAMOLECULAR HYDROPHOSPHINATION/CYCLIZATION; CRYSTALLOGRAPHIC CHARACTERIZATION; POLYMERIZATION CATALYSTS; OLEFIN POLYMERIZATION; YTTERBIUM(II) ALKYLS; LANTHANIDE COMPLEXES; ORGANIC-SYNTHESIS; METAL-COMPLEXES','number-of-cited-references':'75','research-areas':'Chemistry','times-cited':'1','unique-id':'ISI:000395753300031','usage-count-last-180-days':'2','usage-count-since-2013':'10','web-of-science-categories':'Chemistry, Multidisciplinary'\International audienceThe half-sandwich tetra-tert-butylcarbazol-9-yl iodo complex [(tBu(4)Carb)Sm(m-I)(THF)(2)](2) (1) was synthesized by the salt metathesis reaction of tBu(4)CarbK and SmI2(THF)(2) in THF. Complex 1 along with metallic Cu was also isolated from the oxidation reaction of (tBu(4)Carb)(2)Sm by CuI. The formation of stable radical tBu(4)Carb(center dot) was detected in this non-conventional process, indicating preferential oxidation of anion tBu(4)Carb(-) vs. Sm-II. The treatment of 1 with two equivalents of dibenzo-18-crown-6 resulted in heterolytic dissocia-tion of a h 5-bond Sm-tBu(4)Carb and afforded an ionic compound [tBu(4)carb(-)][SmI(crown)(THF)(2)](+) (4). Alkylation of 1 with o-NMe2C6H4CH2K (1: 2 molar ratio) in THF allowed for the synthesis of half-sandwich SmII alkyl complex (tBu(4)Carb) SmCH2(o-NMe2C6H4CH2)(THF)(2) (5) in 55% yield. The amido complex (tBu(4)Carb) SmN(SiMe3)(2)(DME) (6) was obtained by the reaction of 1 with two molar equivalents of NaN(SiMe3)(2) in THF in 89% yield
Highlights of Library Automation related documents in the INSPEC
No full textThe paper has attempted to analyse the Library Automation related records in the INSPEC (1969 to July 2004). The growth of Library Automation related literature, country of input, scattering of literature in different publication types, core journals publishing Library Automation related publications, language-wise proportion of the literature, content analysis through keywords/descriptors, availability of URLs (Universal Resource Locator) for full text articles as alternative locations were the main focus of the study. After the year 1984, the literature grows approximately linearly with a growth rate of about 600 items per year. The USA is the predominant publishing country of Library Automation related literature. Journals are the most preferred publication media, followed by Conference/Proceedings-Papers, Book-Chapters, and Reports publications. Most productive journals are: Library Hi Tech, followed by Computers in Libraries, VINE, Information Technology and Libraries, and Program. English articles constitute 91.83% of the total literature. That means the non-English articles constitute only 8.17%. The keyword analysis indicates that the key areas of Library Automation were cataloguing; academic-libraries; information-retrieval; Internet; and information-services. The most occurred URL was http://www.dlib.org/ as alternative locations in the availability notes of Library Automation related records
Prescribing the Jacobian in critical spaces
No full textInternational audienceWe consider the Sobolev space . We prove the existence of a robust distributional Jacobian for provided . This generalizes a result of Bourgain, Brezis and the second author (Comm. Pure Appl. Math. 2005), where the case is considered. In the critical case where , we identify the image of the map . This extends a result of Alberti, Baldo and Orlandi (J. Eur. Math. Soc. 2003) for and . We also present a new, analytical, dipole construction method
Mechanistic Aspects of the Polymerization of Lactide Using a Highly Efficient Aluminum(III) Catalytic System
No full textbibtex: ISI:000400802300037 bibtex\location:'1155 16TH ST, NW, WASHINGTON, DC 20036 USA',publisher:'AMER CHEMICAL SOC',type:'Article',affiliation:'Thomas, CM (Reprint Author), PSL Res Univ, Chim ParisTech, CNRS, Inst Rech Chim Paris, F-75005 Paris, France. Maron, L (Reprint Author), Univ Toulouse, 135 Ave Rangueil, F-31077 Toulouse, France. Maron, L (Reprint Author), UPS, INSA, 135 Ave Rangueil, F-31077 Toulouse, France. Maron, L (Reprint Author), IRSAMC, LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France. Maron, L (Reprint Author), CNRS, F-31077 Toulouse, France. Maron, L (Reprint Author), IRSAMC, UMR 5215, F-31077 Toulouse, France. Robert, Carine; Schmid, Thibault E.; Richard, Vincent; Haquette, Pierre; Raman, Sumesh K.; Rager, Marie-Noelle; Thomas, Christophe M., PSL Res Univ, Chim ParisTech, CNRS, Inst Rech Chim Paris, F-75005 Paris, France. Gauvin, Regis M.; Morin, Yohann, Univ Lille, Univ Artois, CNRS, Cent Lille,ENSCL,UCCS,UMR 8181, F-59000 Lille, France. Trivelli, Xavier, Univ Lille, CNRS, UGSF, UMR 8576, F-59000 Lille, France. Guerineau, Vincent, Univ Paris Sud, Univ Paris Saclay, CNRS UPR2301, Inst Chim Subst Nat, Ave Terrasse, F-91198 Gif Sur Yvette, France. del Rosal, Iker; Maron, Laurent, Univ Toulouse, 135 Ave Rangueil, F-31077 Toulouse, France. del Rosal, Iker; Maron, Laurent, UPS, INSA, 135 Ave Rangueil, F-31077 Toulouse, France. del Rosal, Iker; Maron, Laurent, IRSAMC, LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France. del Rosal, Iker; Maron, Laurent, CNRS, F-31077 Toulouse, France. del Rosal, Iker; Maron, Laurent, IRSAMC, UMR 5215, F-31077 Toulouse, France.','author-email':'[email protected] [email protected]',da:'2018-12-05','doc-delivery-number':'EU1SV','funding-acknowledgement':'ENSCP; ANR [ANR-10-PDOC-010-01]; Fondation Pierre-Gilles de Gennes; CNRS; CALMIP-EOS [p0833]; CNRS [TGIR-RMN-THC Fr3050]','funding-text':'ENSCP, ANR (grant ANR-10-PDOC-010-01), Fondation Pierre-Gilles de Gennes, and CNRS are thanked for financial support of this work. This work was performed using HPC resources from CALMIP-EOS (grant p0833). We would like to thank Purac for a generous loan of rac-lactide. C.M.T. is grateful to the Institut Universitaire de France (IUF). Financial support from the TGIR-RMN-THC Fr3050 CNRS for conducting the research is gratefully acknowledged.','journal-iso':'J. Am. Chem. Soc.','keywords-plus':'RING-OPENING POLYMERIZATION; CHROMIUM SALEN COMPLEXES; QUATERNARY ORGANIC SALT; CARBON-DIOXIDE; PROPYLENE-OXIDE; RAC-LACTIDE; STEREOSELECTIVE POLYMERIZATION; ALTERNATING COPOLYMERIZATION; CYCLIC CARBONATES; RACEMIC LACTIDE','number-of-cited-references':'85','orcid-numbers':'Del Rosal, Iker/0000-0001-6898-4550 Gauvin, Regis/0000-0002-4788-4363 Guerineau, Vincent/0000-0002-1747-5016 Thomas, Christophe/0000-0001-8014-4255','research-areas':'Chemistry','researcherid-numbers':'Del Rosal, Iker/H-3419-2012','times-cited':'12','unique-id':'ISI:000400802300037','usage-count-last-180-days':'13','usage-count-since-2013':'83','web-of-science-categories':'Chemistry, Multidisciplinary'\International audienceWe report here a unique example of an in situ generated aluminum initiator stabilized by a C-2-symmetric salen ligand which shows a hitherto unknown high activity for the ROP of rac-lactide at room temperature. Using a simple and robust catalyst system, which is prepared from a salen complex and an onium salt, this convenient route employs readily available reagents that afford polylactide in good yields with narrow polydispersity indices, without the need for time-consuming and expensive processes that are typically required for catalyst preparation and purification. In line with the experimental evidence, DFT studies reveal that initiation and propagation proceed via an external alkoxide attack on the coordinated monomer
Analysis of DVB-H network coverage with the application of transmit diversity
No full textThis paper investigates the effects of the Cyclic Delay Diversity (CDD) transmit diversity scheme on DVB-H networks. Transmit diversity improves reception and Quality of Service (QoS) in areas of poor coverage such as sparsely populated or obscured locations. The technique not only povides robust reception in mobile environments thus improving QoS, but it also reduces network costs in terms of the transmit power, number of
infrastructure elements, antenna height and the frequency reuse factor over indoor and outdoor environments. In this paper, the benefit and effectiveness of CDD transmit diversity is tackled
through simulation results for comparison in several scenarios of coverage in DVB-H networks. The channel model used in the simulations is based on COST207 and a basic radio planning
technique is used to illustrate the main principles developed in this paper. The work reported in this paper was supported by
the European Commission IST project—PLUTO (Physical Layer DVB Transmission Optimization)
Optimisation Topologique sans Maillage - Vers la reconnaissance d'éléments structuraux
No full textNational audienceCet article présente des résultats d’une étude d’optimisation topologique utilisant une nouvelle approche par ajout de variables de localisation des nœuds. Dans cette approche, la discrétisation spatiale est découplée de la distribution matérielle. Les effets de la méthode de discrétisation, de l’optimiseur et de la fraction de volume sont étudiés. Les résultats de l’approche par ajout de variables de localisation des nœuds sont prometteurs et suggèrent que cette approche pourrait constituer une alternative aux méthodes actuellement utilisées en optimisation topologique
Scaling laws based metamodels for the selection of the cooling strategy of electromechanical actuators in the early design stages
No full textInternational audienceThe integration of electromechanical actuation systems for aerospace applications requires additional thermal stress considerations during the preliminary design, which were not necessary within the hydraulic technology. The favored models during this design phase are simple, continuous and explicit mathematical expressions to enable easy analytical manipulations or implementations in worksheets or optimization loops. The paper shows how such models can be obtained for the desired applications, illustrating the example of a Limited Angle Torque Motor (LATM) with different cooling strategies. The used method for gathering the models is a regression process on data obtained by finite element simulations. The originality of the method stands in the physical insight of the regression function which is based on scaling laws and dimensional analysis. An example of preliminary design of a LATM illustrates the use of the obtained models for the comparison of two possible architectures intended to minimize the mass of the actuator by implementing different cooling strategies. Abbreviations 3D three-dimensional DDV Direct Drive Valve DoE Design of Experiments LATM Limited Angle Torque Motor RMS Root Mean Square SLAWMM Scaling-LAW-based MetaModels Nomenclature β air thermal expansion coefficient [1/K] ∆θ difference between the winding temperature and bulk temperature of the fluid [K] λ fluid thermal conductivity [W/mK] µ fluid dynamic viscosity [kg/ms] π i dimensionless numbers [−] ρ fluid density [kg/m 3 ] ρ Cu copper density [kg/m 3 ] ρ el electrical resistivity [Ωm] τ copper volume fraction in the copper-resin mixture [−] θ temperature [ • C] or [K] ϕ heat flow rate density [W/m 2 ] * Corresponding author. Tel.: +33 (0)5 67048823; fax: +33 (0)5 61559950 Email address: [email protected] (Ion Hazyuk) B r remanent induction of the permanent magnet [T ] C p fluid specific heat capacity [J/kgK] D motor diameter [m] d i geometric dimensions [m] e air gap of the motor [m] g gravitational acceleration [m/s 2 ] Gr Grashof number [−] h global convective heat transfer coefficient [W/m 2 K] J current density [A/m 2 ] L motor length [m] M mass [kg] Nu Nusselt number [−] Pr Prandtl number [−] Q heat flow rate [W] Re Reynolds number [−] S motor external surface [m 2 ] T electromagnetic torque [Nm] T L linear electromagnetic torque [N] U kerosene velocity in the motor air gap [m/s] V Cu volume of the copper [m 3
Reactions of Neutral Cobalt(II) Complexes of a Dianionic Tetrapodal Pentadentate Ligand: Cobalt(III) Amides from Imido Radicals
No full textbibtex: ISI:000398426000046 bibtex\location:'1155 16TH ST, NW, WASHINGTON, DC 20036 USA',publisher:'AMER CHEMICAL SOC',type:'Article',affiliation:'Piers, WE (Reprint Author), Univ Calgary, Dept Chem, 2500 Univ Dr NW, Calgary, AB T2N 1N4, Canada. Maron, L (Reprint Author), Univ Toulouse, LPCNO, INSA, UPS, 135 Ave Rangueil, F-31077 Toulouse, France. Maron, L (Reprint Author), CNRS, LPCNO, F-31077 Toulouse, France. Nurdin, Lucie; Spasyuk, Denis M.; Piers, Warren E., Univ Calgary, Dept Chem, 2500 Univ Dr NW, Calgary, AB T2N 1N4, Canada. Maron, Laurent, Univ Toulouse, LPCNO, INSA, UPS, 135 Ave Rangueil, F-31077 Toulouse, France. Maron, Laurent, CNRS, LPCNO, F-31077 Toulouse, France. Spasyuk, Denis M., Canadian Light Source Inc, 44 Innovat Blvd, Saskatoon, SK S7N 2V3, Canada.','author-email':'[email protected] [email protected]',da:'2018-12-05','doc-delivery-number':'EQ9SR',eissn:'1520-510X','funding-acknowledgement':'NSERC of Canada; The Alexander von Humboldt Foundation; Chinese Academy of Science; Institut Universitaire de France; CNRS; University of Calgary for an Eyes High Postdoctoral Fellowship; Alberta Innovates Technology Futures for Scholarship','funding-text':'Funding for this work was provided by NSERC of Canada (Discovery Grant) the Canada Research Chair secretariat (Tier I CRC 2013-2020) to W.E.P. The Alexander von Humboldt Foundation (W.E.P.and L.M.) and the Chinese Academy of Science (L.M.) are acknowledged for financial support. L.M. is member of the Institut Universitaire de France. L.M. and W.P. also acknowledge CNRS for a bilateral grant through the PICS Program. CalMip is acknowledged for a generous grant of computing time. D.M.S. thanks the University of Calgary for an Eyes High Postdoctoral Fellowship. L.N. thanks Alberta Innovates Technology Futures for Scholarship support. Dr. David W. Bi is acknowledged for collecting the X-ray data for compounds 1, 2-tBu, and 4.','journal-iso':'Inorg. Chem.','keywords-plus':'TRANSITION-METAL-COMPLEXES; COUPLED ELECTRON-TRANSFER; H BOND ACTIVATION; OLEFIN AZIRIDINATION; GENERATING HYDROGEN; OXOIRON(IV) COMPLEX; CRYSTAL-STRUCTURES; ATOM ABSTRACTION; WATER OXIDATION; REACTIVITY','number-of-cited-references':'61','orcid-numbers':'Piers, Warren/0000-0003-2278-1269','research-areas':'Chemistry','times-cited':'7','unique-id':'ISI:000398426000046','usage-count-last-180-days':'6','usage-count-since-2013':'25','web-of-science-categories':'Chemistry, Inorganic & Nuclear'\International audienceNeutral cobalt(II) complexes of the dianionic tetrapodal pentadentate ligand B(2)Pz(4)Py, in which borate linkers supply the dianionic [GRAPHIC] charges, are repotted. Both the six-coordinate THF adduct 1-THF and the five-coordinate THF-free complex 1 are in a high-spin S = 3/2 configuration in the ground state and have been structurally characterized by X-ray crystallography. These two Co(II) starting materials react rapidly with aryl azides of moderate steric bulk. The thermodynamic products of these reactions are low-spin, diamagnetic, Co(III) amido complexes that are either monomeric, when an external hydrogen atom source such as 1,4-cydohexadiene is Present, or dimeric products formed via C-C coupling of the azide aryl group and internal transfer of H-. to the nitrogen. These products are fully characterized and are tare, examples of octahedral CO amid compounds; structural determinations reveal significant pytarrndalization of the amido nitrogens due to pi-pi repulsion wherein the amido is primarily a sigma donor. The amido products arise from highly reactive Co(III) imido radical intermediates that are the kinetic products of the reactions of 1 or 1-THF with the azide reagents. The imido radicals, can be detected by X-band EPR spectroscopy and have been probed by density functional theory computations, which indicate that this doublet species is characterized by a high degree of spin localization on the imido ligand, accounting for the reactivity with hydrogen atom sources and dimerization chemistry observed. The high coordination number and the electron rich nature of the dianionic B(2)Pz(4)Py ligand framework render the imido ligand formed highly reactive
Reactivity studies on [Cp ` Fe(mu-I)](2): nitrido-, sulfido- and diselenide iron complexes derived from pseudohalide activation
No full textbibtex: ISI:000400553000098 bibtex\location:'THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND',publisher:'ROYAL SOC CHEMISTRY',type:'Article',affiliation:'Walter, MD (Reprint Author), Tech Univ Carolo Wilhelmina Braunschweig, Inst Anorgan & Analyt Chem, Hagenring 30, D-38106 Braunschweig, Germany. Maron, L (Reprint Author), Univ Toulouse, INSA UPS LPCNO, CNRS LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France. Reiners, Matthias; Maekawa, Miyuki; Daniliuc, Constantin G.; Freytag, Matthias; Jones, Peter G.; Walter, Marc D., Tech Univ Carolo Wilhelmina Braunschweig, Inst Anorgan & Analyt Chem, Hagenring 30, D-38106 Braunschweig, Germany. White, Peter S., Univ N Carolina, Dept Chem, CB 3290, Chapel Hill, NC 27599 USA. Hohenberger, Johannes; Sutter, Joerg; Meyer, Karsten, Univ Erlangen Nurnberg, Dept Chem & Pharm, Inorgan Chem, Egerlandstr 1, D-91058 Erlangen, Germany. Maron, Laurent, Univ Toulouse, INSA UPS LPCNO, CNRS LPCNO, 135 Ave Rangueil, F-31077 Toulouse, France.','author-email':'[email protected] [email protected]',da:'2018-12-05','doc-delivery-number':'ET8MH',eissn:'2041-6539','funding-acknowledgement':'Alexander von Humboldt Foundation; NSF [CHE-0615704]; Emmy Noether and Heisenberg program [WA 2513/2, WA 2513/6]; Humboldt Foundation','funding-text':'We thank the Alexander von Humboldt Foundation for a Feodor-Lynen Fellowship (M. D. W.) and Prof. Maurice Brookhart for providing financial support (through NSF Grant CHE-0615704) and laboratory facilities (M. D. W.) during the initial phase of this research program. Deutsche Forschungsgemeinschaft (DFG) is acknowledged for generous funding by the Emmy Noether and Heisenberg program (WA 2513/2 and WA 2513/6, respectively). LM is grateful to the Humboldt Foundation for a grant of experienced researcher and the Chinese Academy of Science. CalMip is also gratefully acknowledged for a generous computational grant.','journal-iso':'Chem. Sci.','keywords-plus':'FE2O2 DIAMOND CORE; STRUCTURAL-CHARACTERIZATION; DINITROGEN ACTIVATION; SULFUR CLUSTERS; SOLVENT PURIFICATION; MOLECULAR-STRUCTURES; ELECTRON-TRANSFER; 2FE-2S CLUSTERS; DOUBLE-BOND; FE-IVN','number-of-cited-references':'106',oa:'DOAJ Gold','orcid-numbers':'Meyer, Karsten/0000-0002-7844-2998 Daniliuc, Constantin G./0000-0002-6709-3673','research-areas':'Chemistry','researcherid-numbers':'Meyer, Karsten/G-2570-2012 Walter, Marc/E-4479-2012','times-cited':'4','unique-id':'ISI:000400553000098','usage-count-last-180-days':'4','usage-count-since-2013':'20','web-of-science-categories':'Chemistry, Multidisciplinary'\International audienceThe iron half-sandwich [Cp'Fe(mu-I)](2) (Cp' = 1,2,4-(Me3C)(3)C5H2, 1) reacts with the pseudohalides NCO-, SCN-, SeCN- and N-3(-) to give [Cp'Fe(mu-NCO)](2) (2), [Cp'Fe(mu-S)](2) (3), [Cp'Fe(mu-Se-2)](2) (4) and [Cp'Fe(mu-N)](2) (5), respectively. Various spectroscopic techniques including X-ray diffraction, solid-state magnetic susceptibility studies and Fe-57 Mossbauer spectroscopy were employed in the characterization of these species. Mossbauer spectroscopy shows a decreasing isomer shift with increasing formal oxidation state, ranging from Fe(II) to Fe(IV), in complexes 1 to 5. The sulfido-bridged dimer 3 exhibits strong antiferromagnetic coupling between the Fe(III) centers. This leads to temperature-independent paramagnetism (TIP) at low temperature, from which the energy gap between the ground and the excited state can be estimated to be 2J = ca. 700 cm(-1). The iron(IV) nitrido complex [Cp'Fe(mu-N)](2) (5) shows no reactivity towards H-2 (10 atm), but undergoes clean reactions with CO (5 bar) and XylNC (Xyl = 2,6-Me2C6H3) to form the diamagnetic isocyanate and carbodiimide complexes [Cp'Fe(CO)(2)(NCO)] (7) and [Cp'Fe(CNXyl)(2)(NCNXyl)] (8), respectively. All compounds were fully characterized, and density functional theory (DFT) computations provide useful insights into their formation and the electronic structures of complexes 3 and 5
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