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756 results on '"Mori, Yutaka"'

8. Topology Control Protocols to Conserve Energy in Wireless Ad Hoc Networks

Author

Xu, Ya, Bien, Solomon, Mori, Yutaka, Heidemann, John, and Estrin, D

Subjects
Systems, Wireless sensor networks, Adaptive topology, Topology control, Energy conservation
Abstract

In wireless ad hoc networks and sensor networks, energy use is in many cases the most important constraint since it corresponds directly to operational lifetime. This paper presents two topology control protocols that extend the lifetime of dense ad hoc networks while preserving connectivity, the ability for nodes to reach each other. Our protocols conserve energy by identifying redundant nodes and turning their radios off. Geographic Adaptive Fidelity (GAF) identifies redundant nodes by their physical location and a conservative estimate of radio range. Cluster-based Energy Conservation (CEC) directly observes radio connectivity to determine redundancy and so can be more aggressive at identifying duplication and more robust to radio fading. We evaluate these protocols through analysis, extensive simulations, and experimental results in two wireless testbeds, showing that the protocols are robust to variance in node mobility, radio propagation, node deployment density, and other factors.

Published
2003

30. Drastic decrease of carbonyl group after the loss of ether in PADC exposed to 222 nm UV photons

Author

Kusumoto , Tamon, Mori, Yutaka, Kanzaki, Masato, Oda, Keiji, Kodaira, Satoshi, Rémi, Barillon, Yamauchi, Tomoya, Tamon, Kusumoto, and Satoshi, Kodaira

Abstract

We aim to elucidate the chemical damage structure in poly(allyl diglycol carbonate), PADC, exposed to UV photons with a wavelength of 222 nm using FT-IR spectrometric method. The number density of carbonyl (C˭O) in PADC, which composes carbonate ester, is hardly affected by the UV photons below the critical fluence of 3.0 × 1019 photons/cm2. The number density of carbonyl decreases only above the critical fluence, while those of ether and C-O-C in carbonate ester are monotonically cleaved. These findings corroborate the previous result using 28 MeV electron beams, in which the carbonate ester is lost only above the critical fluence of 1.6 × 1015 electrons/cm2, where the overlapping of electron tracks becomes significant. We extend the conventional track overlapping model to clarify the spatial distribution of point-like defects after the UV exposure. The discrete damage is seen at the critical condition, based on the extended track overlapping model.

Published
2019

48. Distinct step-like changes in G values for the losses of typical functional groups in poly(ethylene terephthalate) along boron ion tracks around the groups in poly(ethylene terephthalate) along boron ion tracks around the detection threshold

Author

Yamauchi, Tomoya, Kusumoto, Tamon, Ueno, Takuya, Mori, Yutaka, Kanasaki, Masato, Oda, Keiji, Kodaira, Satoshi, Rémi, Barillon, Tamon, Kusumoto, and Satoshi, Kodaira

Abstract

G values of the losses of typical functional groups in PET films along boron ion tracks have been determined using FT-IR spectrometry. G value for the loss of aromatic-ring clearly increases above 270 eV/nm. Those of ester and ethylene increase around the slightly lower stopping power of 250 eV/nm. The detection thresholds are defined by determining the original points from which the evolution of etch pit starts along the latent track, when the chemical etching was progressing starting from the front surface of each incident ion trajectory. The thresholds for B, C, N, O, Ar and Kr ions have been determined for other kind of PET sheets. Values of the sensitivity at the thresholds are fairly higher at heavy ions with smaller atomic number.

Published
2018

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