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191.
Sudip Misra P. Venkata Krishna Kiran Isaac Abraham 《Wireless Personal Communications》2011,56(1):55-72
Providing effective medium access for wireless networks is a challenging task. Most of the existing protocols of IEEE 802.11
Medium Access Control (MAC) work towards the goal of achieving effective channel access by developing various backoff procedures.
In this paper, we make an attempt to develop a new medium access protocol named Learning Automata (LA) based Wireless Channel
Reservation (LAWCR). We use an LA approach to implement reservation for channel access for single hop wireless networks. Also,
sequence procedure is used to improve the reservation mechanism. The performance of the proposed LAWCR scheme show significant
improvements over the legacy DCF protocol with respect to important criteria such as the average time spent in the buffer
and the throughput. 相似文献
192.
Moure AL Arrayás RG Carretero JC 《Chemical communications (Cambridge, England)》2011,47(23):6701-6703
The α,β-unsaturated sulfones are suitable activated olefins in catalytic asymmetric conjugate β-boration. These substrates undergo smooth conjugate addition of bis(pinacolato)diboron [B(2)(pin)(2)] catalyzed by nonracemic Cu(I)-diphosphine complexes to provide, upon subsequent oxidation, β-hydroxy sulfones in good yields and high enantiocontrol. 相似文献
193.
Abraham Y Salman H Suwinska K Eichen Y 《Chemical communications (Cambridge, England)》2011,47(21):6087-6089
Cyclo[2]benzimidazole is a new host for anions that turns on its luminescence up to 150 fold upon binding. Photoexcited cyclo[2]benzimidazole undergoes an efficient non-radiative deactivation through an excited-state intramolecular proton-transfer (ESIPT) mechanism. Upon binding an anion, the ESIPT pathway is blocked, resulting in an increase in the luminescence efficiency. 相似文献
194.
Conventional training simulators commonly use a hexapod configuration to provide motion cues. While widely used, studies have
shown that hexapods are incapable of producing the range of motion required to achieve high fidelity simulation required in
many applications. A novel alternative is the Atlas motion platform. This paper presents a new generalized kinematic model
of the platform which can be applied to any spherical platform actuated by three omnidirectional wheels. In addition, conditions
for slip-free and singularity-free motions are identified. Two illustrative examples are given for different omnidirectional
wheel configurations. 相似文献
195.
Lara Turner Abraham P. Punnen Yash P. Aneja Horst W. Hamacher 《Mathematical Methods of Operations Research》2011,73(1):19-27
In the generalized balanced optimization problem (GBaOP) the objective value \({\max_{e \in S}{|c(e)-k\max(S)|}}\) is minimized over all feasible subsets S of E = {1, . . . , m}. We show that the algorithm proposed in Punnen and Aneja (Oper Res Lett 32:27–30, 2004) can be modified to ensure that the resulting solution is indeed optimal. This modification is attained at the expense of increased worst-case complexity, but still maintains polynomial solvability of various special cases that are of general interest. In particular, we show that GBaOP can be solved in polynomial time if an associated bottleneck problem can be solved in polynomial time. For the solution of this bottleneck problem, we propose two alternative approaches. 相似文献
196.
Exact and approximate solutions for the reliability of a circular shaft, simultaneously subjected to a bending moment and a torque, are derived and compared. The closed-form solution is obtained in terms of an equivalent bending moment having a noncentral chi-square distribution, whereas the approximate solution is derived via the Hasofer-Lind reliability index. Comparison shows a remarkably high accuracy of the index.On leave from the Technion, Israel Institute of Technology, Haifa, Israel 相似文献
197.
Christophe Abraham 《Journal of multivariate analysis》2005,95(1):50-65
We provide the rate of convergence of the Bayes action derived from non smooth loss functions involved in Bayesian robustness. Such loss functions are typically not twice differentiable but admit right and left second derivatives. The asymptotic limit of three measures of global robustness is given. These measures are the range of the Bayes actions set associated with a class of loss functions, the maximum regret of using a particular loss when the subjective loss belongs to a given class and the range of the posterior expected loss when the loss ranges over a given class. An application to prior robustness with density ratio classes is provided. 相似文献
198.
We explore the consequences of certain commutativity hypotheses on a single nilpotent element or the set N of all nilpotent elements. We give several sufficient conditions for N to be an ideal. We present some nontrivial examples, including an example in which N is commutative (in fact, N
2 = {0}) and N is not an ideal.
Received: April 27, 2006. Revised: July 31, 2006. 相似文献
199.
Abraham D. Nagar R. Ruberto M.N. Eisenstein G. Koren U. Zyskind J.L. DiGiovanni D.J. 《Photonics Technology Letters, IEEE》1993,5(4):377-379
The authors demonstrate optical frequency tuning by direct electrical means as well as FM and AM mode-locking in an erbium-doped fiber laser with an intracavity distributed Bragg reflector active filter/modulator. They obtained a 6 nm discrete tuning range and pulses of 38 and 78 ps duration in AM and FM mode-locking, respectively 相似文献
200.
The effect of the ionosphere on remote sensing of sea surface salinity from space: absorption and emission at L band 总被引:2,自引:0,他引:2
The purpose of this work is to examine the effects of Faraday rotation and attenuation/emission in the ionosphere in the context of a future remote sensing system in space to measure salinity. Sea surface salinity is important for understanding ocean circulation and for modeling energy exchange with the atmosphere. A passive microwave sensor in space operating near 1.4 GHz (L-band) could provide global coverage and complement in situ arrays being planned to provide subsurface profiles. However, the salinity signal is relatively small and changes along the propagation path can be important sources of error. It is shown that errors due to the ionosphere can be as large as several psu. The dominant source of error is Faraday rotation but emission can be important 相似文献