ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Stability and throughput analysis of unslotted CDMA‐ALOHA with finite number of users and code sharing (1997)
    Springer
    Telecommunication systems 8 (1997), S. 257-275 
    Details
    ISSN: 1572-9451
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract We consider a system comprising a finite number of nodes, with infinite packet buffers, that use unslotted ALOHA with Code Division Multiple Access (CDMA) to share a channel for transmitting packetised data. We propose a simple model for packet transmission and retransmission at each node, and show that saturation throughput in this model yields a sufficient condition for the stability of the packet buffers; we interpret this as the capacity of the access method. We calculate and compare the capacities of CDMA‐ALOHA (with and without code sharing) and TDMA‐ALOHA; we also consider carrier sensing and collision detection versions of these protocols. In each case, saturation throughput can be obtained via analysis of a continuous time Markov chain. Our results show how saturation throughput degrades with code‐sharing. Finally, we also present some simulation results for mean packet delay. Our work is motivated by optical CDMA in which “chips” can be optically generated, and hence the achievable chip rate can exceed the achievable TDMA bit rate which is limited by electronics. Code sharing may be useful in the optical CDMA context as it reduces the number of optical correlators at the receivers. Our throughput results help to quantify by how much the CDMA chip rate should exceed the TDMA bit rate so that CDMA‐ALOHA yields better capacity than TDMA‐ALOHA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019117622323
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    On the optimal control of arrivals to a single queue with arbitrary feedback delay (1997)
    Springer
    Queueing systems 27 (1997), S. 1-16 
    Details
    ISSN: 1572-9443
    Keywords: Markov decision theory ; delayed feedback information ; threshold policies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract We consider a problem of admission control to a single queue in discrete time. The controller has access to k step old queue lengths only, where k can be arbitrary. The problem is motivated, in particular, by recent advances in high-speed networking where information delays have become prominent. We formulate the problem in the framework of Completely Observable Controlled Markov Chains, in terms of a multi-dimensional state variable. Exploiting the structure of the problem, we show that under appropriate conditions, the multi-dimensional Dynamic Programming Equation (DPE) can be reduced to a unidimensional one. We then provide simple computable upper and lower bounds to the optimal value function corresponding to the reduced unidimensional DPE. These upper and lower bounds, along with a certain relationship among the parameters of the problem, enable us to deduce partially the structural features of the optimal policy. Our approach enables us to recover simply, in part, the recent results of Altman and Stidham, who have shown that a multiple-threshold-type policy is optimal for this problem. Further, under the same relationship among the parameters of the problem, we provide easily computable upper bounds to the multiple thresholds and show the existence of simple relationships among these upper bounds. These relationships allow us to gain very useful insights into the nature of the optimal policy. In particular, the insights obtained are of great importance for the problem of actually computing an optimal policy because they reduce the search space enormously.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1019145611110
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Stationary lower probabilities and unstable averages (1985)
    Springer
    Probability theory and related fields 69 (1985), S. 1-17 
    Details
    ISSN: 1432-2064
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary This paper explores the possibilities for probability-like models of stationary nondeterministic phenomena that possess divergent but bounded time averages. A random sequence described by a stationary probability measure must have almost surely convergent time averages whenever it has almost surely bounded time averages. Hence, no measure can provide the mathematical model we desire. In turning to lower probability based models we first explore the relationships between divergence, stationarity, and monotone continuity and those between monotone continuity and unicity of extensions. We then construct several examples of stationary lower probabilities for sequences of uniformly bounded random variables such that divergence of time averages occurs with lower probability one. We conclude with some remarks on the problem of estimating lower probability models on the basis of cylinder set observations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00532581
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Kinetic studies on the aminolysis of O-(2,4-dinitrophenyl)-cyclopentanone oxime in benzene (1991)
    Springer
    Reaction kinetics and catalysis letters 43 (1991), S. 117-125 
    Details
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Исследовали реакцию оксима O-(2,4-динитрофенил) циклопентанона с четырьмя первичными алкиламинами и вторичным ариламином-пирролидином в бензоле. В реакции с пирролидином скорость подчинялась третьему порядку по концентрации амина, что обьясняли на основе механизма циклического промежуточного состояния. Аминолиз первичными аминами протекает по обычному закону второго порядка от концентрации амина.
    Notes: Abstract The reaction of O-(2,4-dinitrophenyl) cyclopentanone oxime with four primary alkylamines and a secondary arylamine, pyrrolidine, in benzene has been investigated. In pyrrolidinolysis, a third order dependence on [amine] has been observed, which has been explained on the basis of a cyclic transition state. The aminolysis with primary alkyl amines shows a normal dependence of second order on [amine].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02075422
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Solvent effects on reactions of hydroxide ion with phosphorus(V) esters. A quantitative treatment (1996)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 9 (1996), S. 145-151 
    Details
    ISSN: 0894-3230
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Second-order rate constants of reactions of HO- with phosphate, phosphinate and thiophosphinate esters, (PhO)2PO.OC6H4NO2-p, Ph2PO.OC6H4NO2-p, Ph2PO.SPh, Ph2PO.SC6H4NO2-p and Ph2PO.SEt, go through minima with decreasing water content of H2O-MeCN or H2O-t-BuOH. The rate decrease is due to stabilization of the non-ionic ester on addition of organic solvent to H2O. This inhibition is partially offset by stabilization of the anionic transition states and in the drier solvents partial desolvation of HO- increases rates.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 6
    Electronic Resource
    Electronic Resource
    Effect of sulfuric acid on reactions of peroxymonosulfate ion with sulfides and thiol esters (1998)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 803-808 
    Details
    ISSN: 0894-3230
    Keywords: peroxymonosulfate ion ; oxidation ; sulfuric acid ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Peroxymonosulfate ion, HSO5-, as Oxone in aqueous H2SO4, oxidizes sulfides [MeSC6H4X(p), X = Me, H, NO2] to sulfoxides and converts aryl thiobenzoates [PhCOSC6H4X(p), X = Me, H] and thiol phosphorus(V) esters [Ph2POSPh, (EtO)2POSPh, Ph2POSEt, Ph(EtO)POSEt] into the acids and sulfonate ions. Second-order rate constants increase with increasing concentration of H2SO4 (10-53 wt%), owing to the high polarity of the medium rather than to acid catalysis. The rate increases fit the Grunwald-Winstein equation based on YOTs solvent parameters derived from rate effects on SN1 solvolyses. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 7
    Electronic Resource
    Electronic Resource
    SOLVENT EFFECTS ON REACTIONS OF HYDROXIDE AND OXIMATE IONS WITH PHOSPHORUS(V) ESTERS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 221-228 
    Details
    ISSN: 0894-3230
    Keywords: solvent effects ; hydroxide ; oximates ; phosphorus(V) esters ; nucleophilicity ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: ---Second-order rate constants of reactions of OH-, 2,3-butanedionemonooximate and 2-hydroxybenzaldoximate ions with aryl phosphate, phosphinate and thioarylphosphinate esters go through minima with decreasing water content of aqueous acetonitrile, tert-butyl alcohol and N-methyl-2-pyrrolidone. For reactions in H2O-MeCN the solvent effects are analyzed in terms of activity coefficients of the anionic nucleophiles and transition states. In the drier solvents partial desolvation of the nucleophiles increases rates. Nucleophilicities of several oximates and inorganic anions are compared in water. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 8
    Electronic Resource
    Electronic Resource
    OXIDATIVE HYDROLYSIS OF PHOSPHORUS(V) ESTERS OF THIOLS BY PEROXYMONOSULFATE ION. REACTIONS OF PEROXYMONOSULFATE ION WITH PHOSPHORUS(V) ESTERS OF THIOLS (1997)
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 427-434 
    Details
    ISSN: 0894-3230
    Keywords: phosphorus(V) esters of thiols ; peroxymonosulfate ion ; oxidative hydrolysis ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Peroxymonosulfate ion, HSO-5, as Oxone, readily converts phosphorus(V) esters of thiols into the phosphorus(V) and sulfonic acids. The esters were Ph2PO·SC6H4R(p) with R=MeO (1a), Me (1b), H (1c), Cl (1d) and NO2 (1e), (EtO)2PO · SPh (2), Ph2OI · SEt (3) and PhPO(OEt)SEt (4). Reactions are first order in each reactant and second-order rate constants, k2, for 1a-e fit the Hammett equation with ρ=-0.46. The rate constants increase markedly with increasing water content of H2O-MeCN, the activation enthalpies are low and the entropies are negative. Despite the low value of -ρ, these esters are much less reactive than thiol ethers, but the rate constants of reactions of these compounds and acyl thiols qualitatively follow the ionization potentials of the ethers and the esters. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
  • 9
    facet.materialart.
    Unknown
    Process optimization of graphene growth in a roll-to-roll plasma CVD system (2017)
    American Institute of Physics
    Details
    Publication Date: 2017-11-01
    Electronic ISSN: 2158-3226
    Topics: Physics
    Published by American Institute of Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 10
    facet.materialart.
    Unknown
    Role of defects and microstructure on the electrical properties of solution-processed Al-doped ZnO transparent conducting films (2020)
    Springer
    Details
    Publication Date: 2020-07-08
    Print ISSN: 0947-8396
    Electronic ISSN: 1432-0630
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...