65 research outputs found
The state sum invariant of lens spaces
In this paper, we calculate the values of the state sum invariants for
the lens spaces . In particular, we show that the values of the
invariants are determined by and . As a corollary,
we show that the state sum is a homotopy invariant for the oriented lens
spaces.Comment: 6 pages, 0 figure
Spatially-Coupled MacKay-Neal Codes with No Bit Nodes of Degree Two Achieve the Capacity of BEC
Obata et al. proved that spatially-coupled (SC) MacKay-Neal (MN) codes
achieve the capacity of BEC. However, the SC-MN codes codes have many variable
nodes of degree two and have higher error floors. In this paper, we prove that
SC-MN codes with no variable nodes of degree two achieve the capacity of BEC
The development of “Ultimate Rudder” for EEDI
EEDI (Energy Efficiency Design Index) came into effect mandatory in Jan.
2013, and the ship owners definitely required a higher efficiency propulsion system than ever
before. Hence, the shipyards have been conducting an optimization of ESD (Energy Saving Device)
system in self-propulsion test for each project. As the results, the shipyards have
installed a rudder bulb as an effective ESD.
The rudder bulb is a popular ESD system from a long time ago. Mewis1) described that the rudder
bulb was developed by Costa in 1952 and the efficiency improve by the rudder bulb for a container
vessel was 1% on average. Fujii et al.2) developed “MIPB (Mitsui Integrated Propeller Boss)” as an
advanced rudder bulb. The feature of MIPB was a streamlined profile from propeller cap to rudder.
According to their paper, the efficiency improve by installing MIPB was 2-4%.
Recently, NAKASHIMA PROPELLER Co., Ltd. developed ECO-Cap (economical propeller
cap)3) as a new ESD with FRP (Fiber Reinforced Plastics). The strength of FRP is higher than that
of NAB (Nickel Aluminium Bronze), therefore ECO-Cap was able to adopt thin fins on propeller
caps for low resistance. Although the material used for the energy- saving propeller cap
was generally NAB, the research results on FRP showed that FRP could be used as ESD due to their
properties such as lightweight and flexibility.
As explained above, the authors thought that there was a possibility to evolve the rudder bulb
profile using the easily moldable FRP compared with NAB. This paper described about the development
of “Ultimate Rudder” of new design concept by FRP. The authors optimized the profile of “Ultimate
Rudder” by CFD and confirmed the efficiency increase from 4.9 to
5.4% in self-propulsion test
Study on the rudder characteristics of ultimate rudder by numerical calculation
The authors invented Ultimate Rudder3) as the rudder with bulb. The authors
calculated the rudder characteristics of the normal rudder and Ultimate Rudder by CFD
at several steering angles and compared these values. The result showed that regardless of the
presence or absence of the bulb, signs of separation appear on the control surface
with a steering angle of 20 deg. to 30 deg. and regarding the steering torque coefficient, it was
found that the steering torque coefficient of Ultimate Rudder is larger than the normal Rudder when
the steering angle is less than 20 deg. and also the steering torque coefficient can be decreased
by changing the shape of the rudder bulb
Common mechanism for helical nanotube formation by anodic polymerization and by cathodic deposition using helical pores on silicon electrodes
We report that platinum-assisted chemical etching formed self-organized helical pores in silicon substrates can be utilized as platforms for the electrochemical production of nanohelices of conducting polymers (polypyrrole) and metals (gold). Surprisingly, the nanohelices thus created are tubes although the polymerization and deposition were carried out by anodic and cathodic reactions, respectively. Based on our results, we propose a common mechanism for the formation of tubular nanohelices by both anodic polymerization and cathodic deposition through the accumulation of reactants in microporous silicon which covers the wall surface of the helical pores
Photoemission Angular Distribution Beyond the Single Wavevector Description of Photoelectron Final States
We develop a novel simulation procedure for angle-resolved photoemission
spectroscopy (ARPES), where a photoelectron wave function is set to be an
outgoing plane wave in a vacuum associated with the emitted photoelectron wave
packet. ARPES measurements on the transition metal dichalcogenide
- are performed, and our simulations exhibit good
agreement with experiments. Analysis of our calculated final state wave
functions quantitatively visualizes that they include various waves due to the
boundary condition and the uneven crystal potential. These results show that a
more detailed investigation of the photoelectron final states is necessary to
fully explain the photon-energy- and light-polarization-dependent ARPES
spectra.Comment: 6+14 pages, 4+15 figure
Broken Screw Rotational Symmetry in the Near-Surface Electronic Structure of -Stacked Crystals
We investigate the electronic structure of - and
by angle-resolved photoemission spectroscopy (ARPES) and
photoemission intensity calculations. Although in bulk form, these materials
are expected to exhibit band degeneracy in the plane due to screw
rotation and time-reversal symmetries, we observe gapped band dispersion near
the surface. We extract from first-principles calculations the near-surface
electronic structure probed by ARPES and find that the calculated photoemission
spectra from the near-surface region reproduce the gapped ARPES spectra. Our
results show that the near-surface electronic structure can be qualitatively
different from the bulk one due to partially broken nonsymmorphic symmetries.Comment: 6+11 pages, 4+13 figure
Devil's staircase transition of the electronic structures in CeSb
Solids with competing interactions often undergo complex phase transitions
with a variety of long-periodic modulations. Among such transition, devil's
staircase is the most complex phenomenon, and for it, CeSb is the most famous
material, where a number of the distinct phases with long-periodic
magnetostructures sequentially appear below the Neel temperature. An evolution
of the low-energy electronic structure going through the devil's staircase is
of special interest, which has, however, been elusive so far despite the
40-years of intense researches. Here we use bulk-sensitive angle-resolved
photoemission spectroscopy and reveal the devil's staircase transition of the
electronic structures. The magnetic reconstruction dramatically alters the band
dispersions at each transition. We moreover find that the well-defined band
picture largely collapses around the Fermi energy under the long-periodic
modulation of the transitional phase, while it recovers at the transition into
the lowest-temperature ground state. Our data provide the first direct evidence
for a significant reorganization of the electronic structures and spectral
functions occurring during the devil's staircase.Comment: 22 pages, 5 figure
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