

Papers Published in Technical Journals and ConferencesOptimal Guidance for Autonomous Underwater Vehicle Navigation within Undersea Areas of Current DisturbancesK. Kim and T. Ura Advanced Robotics, Brill, Vol. 23, No. 5, pp. 601–628, 2009. Simulated navigations of an autonomous underwater vehicle (AUV) achieved by the minimum time guidance within undersea areas of current disturbances are presented. When an AUV has to transit to a given destination within an area of current disturbance, ingenious guidance enables the minimum time navigation. In this study, a numerical solution procedure for an optimal heading guidance rule is developed. As the optimal heading reference, the solution of the optimal guidance rule is fed to the heading controller. Simulated optimal navigations are realized on the basis of the dynamics of an AUV ¡Ær2D4’. The r2D4 is a deepoceanexploring AUV developed by the Institute of Industrial Science, University of Tokyo. The developed procedure never fails to derive the optimal heading sequence within a finite computational time, provided that the current velocity in the navigation region is known a priori. As a failsafe strategy in achieving the optimal navigation, the concept of quasioptimal navigation is presented. The quasioptimal navigation is implemented by onsite updates of the optimal guidance followed by the heading tracking control. Singleelectron counting statistics of shot noise in nanowire Si MOSFETsK. Nishiguchi, Y. Ono, and A. Fujiwara SSDM, JSAP, 2009, Proc., Vol. 1, No. 1, pp. 1140–1141, Sendai, Japan. Shot noise in the transport of single electrons in a Si MOSFET is monitored with a realtime measurement using a highchargesensitivity electrometer. In the zepto and attoampere current characteristics, the current characteristics are found to be divided into two regimes: a temperatureindependent regime in the lower current range and a temperaturedependent one in the higher current range. A timedomain analysis reveals that, for both regimes, the singleelectron transport obeys a pure Poisson process with the Fano factor being nearly unity, except around the boundary where it is reduced. The NILFS2 Filesystem: Review and ChallengesR. Konishi Japan Linux Symposium 2009, The Linux Foundation, Proc., Vol. 1, No. 1, pp. 1–26, Tokyo, Japan. The Nilfs2 filesystem has finally been merged into the mainline kernel after a long refinement period since its debut. With the continuous snapshotting nilfs2 provides, versioning of the entire file system is easily applicable, and users can even restore files mistakenly overwritten or destroyed just a few seconds ago. This presentation first looks back on the motivation and adopted design of this filesystem and checks the achievement status of the project. Then, the remaining challenges and enhancement will be mentioned for discussing the future prospect and direction of development. In addition to making this filesystem fit for practical use, we are intending to keep trying to enhance it to exploit continuous snapshotting. The challenges include extendedattribute, posixacls, checkpointbased remote replication, fsck, nicer garbage collection, defrag, and better SSD support; the key lies in both user land and kernel code. Random Telegraph Signal and Lowfrequency Noise in Silicon Chargesensitive ElectrometersN. Clement, K. Nishiguchi, A. Fujiwara, and D. Vuillaume SSDM 2009, JSAP, Proc., Vol. 1, No. 1, pp. 1138–1139, Sendai, Japan. We have studied the random telegraph signal (RTS) noise amplitude at room temperature in one of the simplest systems, i.e., a very low density of traps, Debye screening length > devices dimensions and traps depth << oxide thickness. Due to Coulomb repulsion, traps are active one by one. This allows us to confirm the validity of the correlated number/mobility fluctuation model and include the drain bias dependence. Finally we conclude that, for our devices, strong accumulation can be highly suitable for remote electron sensing because of the relative reduction in RTS amplitude owing to correlated mobility fluctuation. Singleelectron stochastic resonance using Si nanowire transistorsK. Nishiguchi, S. Miyamoto, and A. Fujiwara MNC 2009, JSAP, Proc., Vol. 1, No. 1, pp. 470–471, Sapporo, Japan. We demonstrated singleelectronbased stochastic resonance (SR) using nanoscale MOSFETs. The correlation between input and output signal is enhanced by adding noise. Moreover, it is confirmed that a parallel SR system allows further enhancement of the correlation. This is very useful for practical applications because optimization of added noise becomes easy and robustness to fluctuation of the electrical characteristics of nanoscale MOSFETs is guaranteed. singleelectronbased SR would also be useful for the analysis of individualelectron behavior in an electrically defined quantum dot. Sleep and Adaptive Link Rate Control for Power Saving in 10GEPON SystemsR. Kubo, J. Kani, Y. Fujimoto, N. Yoshimoto, and K. Kumozaki IEEE GLOBECOM 2009, Proc., Vol. 1, No. 2, pp. 1–6, Honolulu, USA. This paper proposes a novel powersaving mechanism for the 10 Gbit/s Ethernet passive optical network (10GEPON) systems that are currently being discussed in IEEE 802.3av. The proposed powersaving mechanism includes a sleep control function and an adaptive link rate (ALR) control function. The sleep control function switches the modes of optical network units (ONUs), i.e., active and sleep modes, depending on the presence or absence of traffic. The ALR control function switches the link rate between the optical line terminal (OLT) and an ONU, i.e., 1 Gbit/s or 10 Gbit/s, depending on the quantity of traffic. The proposed hybrid mechanism offers effective power management of ONUs on the basis of the traffic conditions. The proposed hybrid mechanism is validated by some numerical simulations. A Sequence of Nearest Polynomials with Given FactorsH. Sekigawa The Joint Conference of ASCM2009 and MACIS2009, Kyushu Univ., Proc., Vol. 22, No. 1, pp. 187–190, Fukuoka, Japan. Let p and f_{0} be given nonzero multivariate polynomials with real coefficients and f_{0}=1, where f_{0} is the Euclidean norm of f_{0}. For j=1, 2, ¡Ä, let p_{2j–1}=f_{j–1gj} be the nearest polynomial to p such that f_{j–1} is a factor of p_{2j–1} and deg (p_{2j–1}) ≤ deg (p), where deg is the total degree, and let p_{2j}=c_{j}f_{j}g_{j} be the nearest polynomial to p such that g_{j} is a factor of p_{2j}, deg (p_{2j}) ≤ deg (p), f_{j}=1, and c_{j} > 0. We investigate the behavior of the sequences {p_{j}}, {f_{j}}, {g_{j}}, and {c_{j}}. 