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[Author] Hiroki YAMAMOTO(3hit)

1-3hit
  • Variable Retardation Plate by Using Bulk Plastics with Graded Birefringence

    Shinzo MUTO  Hiroki YAMAMOTO  Akio ICHIKAWA  Masamichi MURAKAMI  Hiroshi ITO  

     
    LETTER-Optoelectronics

      Vol:
    E71-E No:4
      Page(s):
    340-341

    A plastics such as polycarbonate take a graded birefringent orientation when a high dc ununiform electric field is applied to its molten phase. This ununiformity is maintained even in a solid phase after decreasing the temperature. Therefore, the plastic plate operating as a variable retardation plate is easily and inexpensively fabricated by using this bulk plastics with graded birefringence.

  • An Extended Scheme for Shape Matching with Local Descriptors

    Kazunori IWATA  Hiroki YAMAMOTO  Kazushi MIMURA  

     
    PAPER-Pattern Recognition

      Pubricized:
    2020/10/27
      Vol:
    E104-D No:2
      Page(s):
    285-293

    Shape matching with local descriptors is an underlying scheme in shape analysis. We can visually confirm the matching results and also assess them for shape classification. Generally, shape matching is implemented by determining the correspondence between shapes that are represented by their respective sets of sampled points. Some matching methods have already been proposed; the main difference between them lies in their choice of matching cost function. This function measures the dissimilarity between the local distribution of sampled points around a focusing point of one shape and the local distribution of sampled points around a referring point of another shape. A local descriptor is used to describe the distribution of sampled points around the point of the shape. In this paper, we propose an extended scheme for shape matching that can compensate for errors in existing local descriptors. It is convenient for local descriptors to adopt our scheme because it does not require the local descriptors to be modified. The main idea of our scheme is to consider the correspondence of neighboring sampled points to a focusing point when determining the correspondence of the focusing point. This is useful because it increases the chance of finding a suitable correspondence. However, considering the correspondence of neighboring points causes a problem regarding computational feasibility, because there is a substantial increase in the number of possible correspondences that need to be considered in shape matching. We solve this problem using a branch-and-bound algorithm, for efficient approximation. Using several shape datasets, we demonstrate that our scheme yields a more suitable matching than the conventional scheme that does not consider the correspondence of neighboring sampled points, even though our scheme requires only a small increase in execution time.

  • BTB Energy Reduction by Focusing on Useless Accesses

    Yoshio SHIMOMURA  Hiroki YAMAMOTO  Hayato USUI  Ryotaro KOBAYASHI  Hajime SHIMADA  

     
    PAPER

      Vol:
    E98-C No:7
      Page(s):
    569-579

    Modern processors use Branch Target Buffer (BTB)[1] to relax control dependence. Unfortunately, the energy consumption of the BTB is high. In order to effectively fetch instructions, it is necessary to perform a branch prediction at the fetch stage, regardless of whether the fetched instruction is a branch or a nonbranch. Therefore, the number of accesses to the BTB is large, and the energy consumption of the BTB is high. However, accesses from nonbranches to the BTB waste energy. In this paper, we focus on accesses from nonbranches to the BTB, which we call useless accesses from a viewpoint of power. For reducing energy consumption without performance loss, we present a method that reduces useless accesses by using information that indicates whether a fetched instruction is a branch or not. To realize the above approach, we propose a branch bit called B-Bit. A B-Bit is associated with an instruction and indicates whether it is a branch or not. A B-Bit is available at the beginning of the fetch stage. If a B-Bit is “1” signifying a branch, the BTB is accessed. If a B-Bit is “0” signifying a nonbranch, the BTB is not accessed. The experimental results show that the total energy consumption can be reduced by 54.3% without performance loss.