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[Author] Hiroaki TANAKA(7hit)

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  • A Study of the Sense of Security Needed for the Input Devices of the Vehicle in the Vicinity of the Time to Collision

    Hiroaki TANAKA  Ayako KOTANI  Katsuyoshi NISHI  Yurie IRIBE  Koji OGURI  

     
    PAPER

      Vol:
    E100-A No:2
      Page(s):
    473-481

    Driving safety related innovations received increasing interest from automotive industry. We performed an experiment to observe what situations are related to the secured feelings drivers feel when they drive, and found out that drivers need to have four to seven seconds to react possible collision when they operate onboard Human Machine Interface (HMI) devices and check display devices. We explored the distance of semantic space to see what factors of HMI interaction lead to the secured feeling in that time period, and extracted 32 types of factors that lead to the secured feelings. Furthermore, in the process of investigating the semantic space distance, the indicators relating to the secured feelings obtained in the prior studies were further determined to be ‘The layout of the operation device is the same as the driver's image' and ‘The driver can use the word he uses every day to give instructions’ in this time period.’, which were more concrete factors of the secured feelings.

  • Temperature-Independent Narrow-Band Optical Filter by an Athermal Waveguide

    Yasuo KOKUBUN  Shigeru YONEDA  Hiroaki TANAKA  

     
    PAPER

      Vol:
    E80-C No:5
      Page(s):
    632-639

    The temperature dependence of the central wavelength of narrow-band filters is a serious problem for the dense WDM systems. In this study, we realized a temperature independent narrow-band filter at 1.3 µm wavelength. First, we designed an athermal waveguide in which optical path length is independent of temperature by using a finite element method. Using this athermal waveguide, we designed and fabricated a ring resonator. As a result, we successfully decreased the temperature coefficient of central wavelength to 710-4 nm/K, which is 7% of conventional SiO2 waveguide filters and 0.7% of conventional semiconductor waveguide filters.

  • Analysis of Drivers' Anxiety and Security during the Braking of a Vehicle

    Hiroaki TANAKA  Daisuke TAKEMORI  Tomohiro MIYACHI  Yurie IRIBE  Koji OGURI  

     
    PAPER

      Vol:
    E100-A No:2
      Page(s):
    466-472

    Establishing drivers' trust in the automated driving system is critical to the success of automated vehicles. The focus of this paper is learning what drivers of automated vehicles need to feel confident during braking events. In this study, 10 participants drove a test vehicle and each experienced 24 different deceleration settings. Prior to each drive, it was indicated to each participant what the expected brake starting and stopping positions would be. During each drive, participants maintained a set speed, and then stopped the vehicle when they saw a signal to apply the brakes. After each drive, the participants were asked what their perceived safety level was during the deceleration setting they just experienced. The results revealed that ‘jerk’ movements have significant influence on drivers' perceived safety. For this study, we have named this jerk movement impression jerk (IJ). Using IJ, clearly divides the secure and anxious feelings of the drivers along with individual differences.

  • Some Remarks on MTBF's for Non-homogeneous Poisson Processes

    Hirofumi KOSHIMAE  Hiroaki TANAKA  Shunji OSAKI  

     
    PAPER-System Reliability

      Vol:
    E77-A No:1
      Page(s):
    144-149

    Non-homogeneous Poisson Processes (NHPP's) can be applied for analyzing reliability growth models for hardware and/or software. Evaluating the Mean Time Between Failures (MTBF's) for such processes, we can evaluate the present status (the degree of improvement). However, it is difficult to evaluate the MTBF's for such processes analytically except the simplest cases. The so-called instantaneous MTBF's which can be easily evaluated are applied in practice instead of the exact MTBF's. In this paper, we discuss both MTBF's analytically, and derive the conditions for the existence of both exact and instantaneous MTBF's. We further illustrate both MTBF's for the Weibull process and S-shaped reliability growth model numerically.

  • Generation of Pack Instruction Sequence for Media Processors Using Multi-Valued Decision Diagram

    Hiroaki TANAKA  Yoshinori TAKEUCHI  Keishi SAKANUSHI  Masaharu IMAI  Hiroki TAGAWA  Yutaka OTA  Nobu MATSUMOTO  

     
    PAPER-System Level Design

      Vol:
    E90-A No:12
      Page(s):
    2800-2809

    SIMD instructions are often implemented in modern multimedia oriented processors. Although SIMD instructions are useful for many digital signal processing applications, most compilers do not exploit SIMD instructions. The difficulty in the utilization of SIMD instructions stems from data parallelism in registers. In assembly code generation, the positions of data in registers must be noted. A technique of generating pack instructions which pack or reorder data in registers is essential for exploitation of SIMD instructions. This paper presents a code generation technique for SIMD instructions with pack instructions. SIMD instructions are generated by finding and grouping the same operations in programs. After the SIMD instruction generation, pack instructions are generated. In the pack instruction generation, Multi-valued Decision Diagram (MDD) is introduced to represent and to manipulate sets of packed data. Experimental results show that the proposed code generation technique can generate assembly code with SIMD and pack instructions performing repacking of 8 packed data in registers for a RISC processor with a dual-issue coprocessor which supports SIMD and pack instructions. The proposed method achieved speedup ratio up to about 8.5 by SIMD instructions and multiple-issue mechanism of the target processor.

  • Software Reliability Measurement and Assessment with Stochastic Differential Equations

    Shigeru YAMADA  Mitsuhiro KIMURA  Hiroaki TANAKA  Shunji OSAKI  

     
    PAPER-Software Reliability

      Vol:
    E77-A No:1
      Page(s):
    109-116

    In this paper, we propose a plausible software reliability growth model by applying a mathematical technique of stochastic differential equations. First, we extend a basic differential equation describing the average behavior of software fault-detection processes during the testing phase to a stochastic differential equation of ItÔ type, and derive a probability distribution of its solution processes. Second, we obtain several software reliability measures from the probability distribution. Finally, applying a method of maximum-likelihood we estimate unknown parameters in our model by using available data in the actual software testing procedures, and numerically show the stochastic behavior of the number of faults remaining in the software system. Further, the model is compared among the existing software reliability growth models in terms of goodness-of-fit.

  • Heuristic Instruction Scheduling Algorithm Using Available Distance for Partial Forwarding Processor

    Takuji HIEDA  Hiroaki TANAKA  Keishi SAKANUSHI  Yoshinori TAKEUCHI  Masaharu IMAI  

     
    PAPER-Embedded, Real-Time and Reconfigurable Systems

      Vol:
    E92-A No:12
      Page(s):
    3258-3267

    Partial forwarding is a design method to place forwarding paths on a part of processor pipeline. Hardware cost of processor can be reduced without performance loss by partial forwarding. However, compiler with the instruction scheduler which considers partial forwarding structure of the target processor is required since conventional scheduling algorithm cannot make the most of partial forwarding structure. In this paper, we propose a heuristic instruction scheduling method for processors with partial forwarding structure. The proposed algorithm uses available distance to schedule instructions which are suitable for the target partial forwarding processor. Experimental results show that the proposed method generates near-optimal solutions in practical time and some of the optimized codes for partial forwarding processor run in the shortest time among the target processors. It also shows that the proposed method is superior to hazard detection unit.