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Hai Huyen Dam Hans-Jürgen Zepernick Sven Nordholm Jörgen Nordberg 《Annals of Operations Research》2005,133(1-4):249-264
The performance of a code division multiple access system depends on the correlation properties of the employed spreading
code. Low cross-correlation values between spreading sequences are desired to suppress multiple access interference and to
improve bit error performance. An auto-correlation function with a distinct peak enables proper synchronization and suppresses
intersymbol interference. However, these requirements contradict each other and a trade-off needs to be established. In this
paper, a global two dimensional optimization method is proposed to minimize the out-of-phase average mean-square aperiodic
auto-correlation with average mean-square aperiodic cross-correlation being allowed to lie within a fixed region. This approach
is applied to design sets of complex spreading sequences. A design example is presented to illustrate the relation between
various correlation characteristics. The correlations of the obtained sets are compared with correlations of other known sequences. 相似文献
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97.
Capacity Constrained Transit Assignment with Common Lines 总被引:1,自引:0,他引:1
Fumitaka Kurauchi Michael G. H. Bell Jan-Dirk Schmöcker 《Journal of Mathematical Modelling and Algorithms》2003,2(4):309-327
This paper proposes the use of absorbing Markov chains to solve the capacity constrained transit network loading problem taking
common lines into account. The approach handles congested transit networks, where some passengers will not be able to board
because of the absence of sufficient space. The model also handles the common lines problem, where choice of route depends
on frequency of arrivals. The mathematical formulation of the problem is presented together with a numerical example.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
98.
Arthur G. Maki John C. Grecu Brenda Winnewisser Manfred Winnewisser 《Journal of Molecular Spectroscopy》2003,222(2):198-212
High-resolution spectra of 15N12C12C15N and 14N13C13C14N have been measured and analyzed from 200 to 3600 cm−1. All the vibrational levels below 900 cm−1 have been observed and characterized. The Fermi resonance between ν2 and 2ν4 has been studied and the resonance constant has been determined for several cases. Several Σ− states have been directly observed for the first time for each isotopomer, the (0001111)0f, (0011111)0f, and (0002222)0f states. The pattern of the energy levels for clusters of l-type resonance coupled levels, such as 0001131,3, has been determined for cyanogen for the first time. Among other things this involved the determination of the vibrational l-type resonance constant, r45. Many of the power series constants, αi and xij, and higher order constants have been determined. 相似文献
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Standard ODE methods such as linear multistep methods encounter difficulties when applied to differential-algebraic equations (DAEs) of index greater than 1. In particular, previous results for index 2 DAEs have practically ruled out the use of all explicit methods and of implicit multistep methods other than backward difference formulas (BDFs) because of stability considerations. In this paper we embed known results for semi-explicit index 1 and 2 DAEs in a more comprehensive theory based on compound multistep and one-leg discretizations. This explains and characterizes the necessary requirements that a method must fulfill in order to be applicable to semi-explicit DAEs. Thus we conclude that the most useful discretizations are those that avoid discretization of the constraint. A freer use of e.g. explicit methods for the non-stiff differential part of the DAE is then possible.Dedicated to Germund Dahlquist on the occasion of his 70th birthdayThis author thanks the Centro de Estadística y Software Matemático de la Universidad Simón Bolivar (CESMa) for permitting her free use of its research facilities.Partial support by the Swedish Research Council for Engineering Sciences TFR under contract no. 222/91-405. 相似文献