Nei Yoshihiro Soma

A method for solving the minimization of the maximum number of open stacks problem within a cutting process

In this paper, the problem of minimizing the maximum number of open stacks around a saw machine is addressed. A new heuristic and a branch-and-bound based exact method for the problem are presented. Computational tests comparing the new approach with other algorithms previously suggested in the literature were carried out.

A greedy search for the three‐dimensional bin packing problem: the packing static stability case

We suggest a greedy search heuristic for solving the three-dimensional bin packing problem (3D-BPP) where in addition to the usual requirement of minimum amount of bins being used, the resulting packing of items into the bins must be physically stable. The problem is NP-hard in the strong sense and imposes severe computational strain for solving it in practice. Computational experiments are also presented and the results are compared with those obtained by the Martello, Pisinger and Vigo (2000) heuristic.

An exact algorithm for the subset sum problem

Abstract The subset sum problem (SSP) is defined as: “Given n positive integers w1,…,wn, find a combination amongst them such that their sum is the closest to, but not exceeding, a positive integer c”. We suggest an exact algorithm by introducing a new type of Core Problem and also, by using an improved version of Bellmans recursion. We show that the resulting algorithm is bounded in time and space resource utilizations, respectively, by O ( Max {(n− log 2 c 2 )c, c log 2 c}) and O (n+c) . In addition to the sharp memory requirement decrease in comparison with any dynamic programming-based algorithm, the search space, for a vast range of instances, is restricted only to feasible states.

A new enumeration scheme for the knapsack problem

Abstract This paper presents a new enumeration scheme to solve the one-dimensional knapsack problem motivated by some observations on number theory, more specifically on the determination of the number of solutions of linear diophantine equations. This new algorithm is pseudopolynomial and its special features provide a reduction in running time and in the computational memory requirements as compared with other exact (dynamic programming) methods.

Comments on parallel algorithms for the knapsack problem

Chang et al. [Parallel Comput. (1994) 233] introduced a parallel algorithm based on a shared memory SIMD architecture for the generation phase of the classic Horowitz and Sahni [J. ACM 21(2) (1974) 277] two-list serial algorithm for the knapsack problem. They claimed that their parallel generation phase could be accomplished in time O((n/8)2) and in space O(2n/4) with O(2n/8) processors.We prove that their results are not correct, i.e., that the suggested scheme time and space complexity should be bounded, instead, by O(n2n/2) and O(2n/2), respectively. These results also invalidate the performance analysis of the more recent Lou and Chang [Parallel Comput. (1997) 1985] algorithm.

Benford's Law and articles of scientific journals: comparison of JCR® and Scopus data

Benford’s Law is a logarithmic probability distribution function used to predict the distribution of the first significant digits in numerical data. This paper presents the results of a study of the distribution of the first significant digits of the number of articles published of journals indexed in the JCR® Sciences and Social Sciences Editions from 2007 to 2011. The data of these journals were also analyzed by the country of origin and the journal’s category. Results considering the number of articles published informed by Scopus are also presented. Comparing the results we observe that there is a significant difference in the data informed in the two databases.

A breadth-first search applied to the minimization of the open stacks

This paper presents a heuristic for the minimization of the open stacks problem (MOSP). The proposed heuristic is based on a simple breadth-first search in MOSP graphs and two new greedy rules to overcome errors. The performance of the proposed heuristic is compared with the best exact and heuristic methods available in the literature. The results show that in addition to the suggested heuristic having much shorter running times than the exact algorithm, the error gap between them is small for a substantial proportion of almost 4500 benchmark instances taken from the literature. The proposed heuristic also has a more robust behaviour than the best heuristic for the MOSP, although less accurate. The proposed heuristic therefore constitutes a viable and cost-effective alternative for solving or obtaining good upper bounds for the MOSP.

A heuristic for the minimization of open stacks problem

It is suggested here a fast and easy to implement heuristic for the minimization of open stacks problem (MOSP). The problem is modeled as a traversing problem in a graph (Gmosp) with a special structure (Yanasse, 1997b). It was observed in Ashikaga (2001) that, in the mean experimental case, Gmosp has large cliques and high edge density. This information was used to implement a heuristic based on the extension-rotation algorithm of Posa (1976) for approximation of Hamiltonian Circuits. Additionally, an initial path for Posas algorithm is derived from the vertices of an ideally maximum clique in order to accelerate the process. Extensive computational tests show that the resulting simple approach dominates in time and mean error the fast actually know Yuen (1991 and 1995) heuristic to the problem.

Um algoritmo exato com ordenamento parcial para solução de um problema de programação da produção: experimentos computacionais

In this paper, we present the computational test results of an implementation made of an exact algorithm proposed in the literature to solve a sequencing problem that arises in some productive environments where open orders of clients should be minimized. From the computational tests, it can be observed that the dominance criteria incorporated in the enumeration process of this algorithm reduces the search space, making the algorithm more efficient in terms of execution time.

An analysis of bibliometric indicators to JCR according to Benford's law

Journal Citation Reports (JCR) is the main source of bibliometric indicators known by the scientific community. This paper presents the results of a study of the distributions of the first and second significant digits according to Benford’s law (BL) of the number of articles, citations, impact factors, half-life and immediacy index bibliometric indicators in journals indexed in the JCR Sciences and Social Sciences Editions from 2007 to 2014. We also performed the data analysis to country’s origin and by journal’s category, and we verified that the second digit has a better adherence to BL. The use of the second digit is important since it provides a more sound, complete and consistent analysis of the bibliometric indicators.