334,603 research outputs found
Beam search heuristics for quadratic earliness and tardiness scheduling
In this paper, we present beam search heuristics for the single machine scheduling problem with quadratic earliness and tardiness costs, and no machine idle time. These heuristics include classic beam search procedures, as well as filtered and recovering algorithms. We consider three dispatching heuristics as evaluation functions, in order to analyse the effect of different rules on the performance of the beam search procedures. The computational results show that using better dispatching heuristics improves the effectiveness of the beam search algorithms. The performance of the several heuristics is similar for instances with low variability. For high variability instances, however, the detailed, filtered and recovering beam search procedures clearly outperform the best existing heuristic. The detailed beam search algorithm performs quite well, and is recommended for small to medium size instances. For larger instances, however, this procedure requires excessive computation times, and the recovering beam search algorithm then becomes the heuristic of choice.scheduling, heuristics, beam search, single machine, quadratic earliness, quadratic tardiness
Beam search heuristics for the single machine scheduling problem with linear earliness and quadratic tardiness costs
In this paper, we consider the single machine scheduling problem with linear earliness and quadratic tardiness costs, and no machine idle time. We present heuristic algorithms based on the beam search technique. These algorithms include classic beam search procedures, as well as the filtered and recovering variants. Several dispatching rules are considered as evaluation functions, in order to analyse the effect of different rules on the effectiveness of the beam search algorithms. The computational results show that using better rules indeed improves the performance of the beam search heuristics. The detailed, filtered and recovering beam search procedures outperform the best existing heuristic. The best results are given by the recovering and detailed variants, which provide objective function values that are quite close to the optimum. For small to medium size instances, either of these procedures can be used. For larger instances, however, the detailed beam search algorithm requires excessive computation times, and the recovering beam search procedure then becomes the heuristic of choice.scheduling, single machine, linear earliness, quadratic tardiness, beam search, heuristics
Throughput Optimal Beam Alignment in Millimeter Wave Networks
Millimeter wave communications rely on narrow-beam transmissions to cope with
the strong signal attenuation at these frequencies, thus demanding precise beam
alignment between transmitter and receiver. The communication overhead incurred
to achieve beam alignment may become a severe impairment in mobile networks.
This paper addresses the problem of optimizing beam alignment acquisition, with
the goal of maximizing throughput. Specifically, the algorithm jointly
determines the portion of time devoted to beam alignment acquisition, as well
as, within this portion of time, the optimal beam search parameters, using the
framework of Markov decision processes. It is proved that a bisection search
algorithm is optimal, and that it outperforms exhaustive and iterative search
algorithms proposed in the literature. The duration of the beam alignment phase
is optimized so as to maximize the overall throughput. The numerical results
show that the throughput, optimized with respect to the duration of the beam
alignment phase, achievable under the exhaustive algorithm is 88.3% lower than
that achievable under the bisection algorithm. Similarly, the throughput
achievable by the iterative search algorithm for a division factor of 4 and 8
is, respectively, 12.8% and 36.4% lower than that achievable by the bisection
algorithm
Photoproduction of signal at electron-proton Colliders
We present the photoproduction of an intermediate mass Higgs (IMH) boson
associated with a boson at the future electron-proton colliders using
bremsstrahlung photon beam or laser backscattered photon beam. With
bremsstrahlung photon beam the search for the IMH boson is unfavorable because
of the small signal rate. But with laser photon beam the search is viable due
to a much larger rate, and provided that the -identification is efficient
and measurement has a good resolution.Comment: 12 pages, using RevTex2.0, figures not included, NUHEP-TH-93-2
Beam search algorithms for the early/tardy scheduling problem with release dates
In this paper we consider the single machine earliness/tardiness scheduling problem with di?erent release dates and no unforced idle time. We present several heuristic algorithms based on the beam search technique. These algorithms include classical beam search procedures, with both priority and total cost evaluation functions, as well as the filtered and recovering variants. Both priority evaluation functions and problem-specific properties were considered for the filtering step used in the filtered and recovering beam search heuristics. Extensive preliminary tests were performed to determine appropriate values for the parameters used by each algorithm. The computational results show that the recovering beam search algorithms outperform their filtered counterparts in both solution quality and computational requirements, while the priority-based filtering procedure proves superior to the rules-based alternative. The beam search procedure with a total cost evaluation function provides very good results, but is computationally expensive and can therefore only be applied to small or medium size instances. The recovering algorithm is quite close in solution quality and is significantly faster, so it can be used to solve even large instances.scheduling, early/tardy, beam search, heuristics
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