3,874 research outputs found
Suppressed Superconductivity of the Surface Conduction Layer in BiSrCaCuO Single Crystals Probed by {\it c}-Axis Tunneling Measurements
We fabricated small-size stacks on the surface of
BiSrCaCuO (BSCCO-2212) single crystals with the bulk
transition temperature 90 K, each containing a few intrinsic
Josephson junctions. Below a critical temperature ( ), we have
observed a weakened Josephson coupling between the CuO superconducting
double layer at the crystal surface and the adjacent one located deeper inside
a stack. The quasiparticle branch in the data of the weakened Josephson
junction (WJJ) fits well to the tunneling characteristics of a d-wave
superconductor()/insulator/d-wave superconductor (DID) junction. Also,
the tunneling resistance in the range agrees well with the
tunneling in a normal metal/insulator/d-wave superconductor (NID) junction. In
spite of the suppressed superconductivity at the surface layer the symmetry of
the order parameter appears to remain unaffected.Comment: 13 pages, 6 figure
On the Estimation of the Mission Performance Index of Unmanned Surface Vehicles Based on the Mission Coverage Area
For mission planning and replanning of multiple unmanned surface vehicles (USVs), it is important to estimate each USV’s mission performance in terms of sea surveillance (e.g., illegal ship control). In this study, a mission performance index (MPI) is proposed based on the mission coverage area for estimating the USVs’ mission performance of illegal ship control. The penalty value is considered in the MPI calculation procedure owing to the track-off of the USV. In addition, the USV simulation is conducted under illegal ship control, and the MPI is calculated based on changing the mission coverage area. The results show that the MPI increases with the path width of the mission coverage area
Nested Lattice Codes for Gaussian Relay Networks with Interference
In this paper, a class of relay networks is considered. We assume that, at a
node, outgoing channels to its neighbors are orthogonal, while incoming signals
from neighbors can interfere with each other. We are interested in the
multicast capacity of these networks. As a subclass, we first focus on Gaussian
relay networks with interference and find an achievable rate using a lattice
coding scheme. It is shown that there is a constant gap between our achievable
rate and the information theoretic cut-set bound. This is similar to the recent
result by Avestimehr, Diggavi, and Tse, who showed such an approximate
characterization of the capacity of general Gaussian relay networks. However,
our achievability uses a structured code instead of a random one. Using the
same idea used in the Gaussian case, we also consider linear finite-field
symmetric networks with interference and characterize the capacity using a
linear coding scheme.Comment: 23 pages, 5 figures, submitted to IEEE Transactions on Information
Theor
OCI-Based Group Communication Support in CORBA
Group communication is a useful mechanism guaranteeing consistency among replicated objects. The existing approaches do not allow transparent plug-in of group communication protocols into CORBA. They either require modification of CORBA or OS, or provide no room for incorporating group communication transport protocols into CORBA. We thus propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. We extend the open communications interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. We also define the group communication inter-ORB protocol (GCIOP) as a group communication instantiation of the general inter-ORB protocol (GIOP) that encapsulates underlying group communication protocols. The proposed scheme can be exploited for fault-tolerant CORBA (FT CORBA)
Development and characterization of polymeric hollow fiber membrane with high CO2 separation performance
In this study, we prepared the polyimide based hollow fiber membrane with High CO2 permeance property. In other to prepare high permeable gas separation membrane, we synthesized novel polyimide material using 6FDA, Durene and PEG monomers. And then general property of the polyimide membrane is characterized using flat sheet type of membrane. The membranes were prepared under various controlled conditions such as retention time and concentration of the polymer. And then the hollow fiber membrane is also prepared and then characterized for confirmation of their potential. The Ionic liquid mainchain polymer is also developed to investigate the gas permeability and potential for utilization to coating materials of hollow fiber membrane. Polyimide with pendant ionic liquid (Im-PpC) membrane showed the high α(CO2/N2) value and the main chain polymer prepared by UV crosslinking with PEG & ILMP crosslinker also showed high α(CO2/N2).
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OCI-Based Group Communication Support in CORBA
Group communication is a useful mechanism guaranteeing consistency among replicated objects. The existing approaches do not allow transparent plug-in of group communication protocols into CORBA. They either require modification of CORBA or OS, or provide no room for incorporating group communication transport protocols into CORBA. We thus propose a generic group communication framework that allows transparent plug-in of various group communication protocols with no modification of existing CORBA. We extend the open communications interface (OCI) to support interoperability, reusability of existing group communication, and independency on ORB and OS. We also define the group communication inter-ORB protocol (GCIOP) as a group communication instantiation of the general inter-ORB protocol (GIOP) that encapsulates underlying group communication protocols. The proposed scheme can be exploited for fault-tolerant CORBA (FT CORBA)
Synthesis and characterization of PEEK containing imidazole moiety and effect of functional groups
Anion exchange membrane fuel cells (AEMFCs) are considered as one of the alternative power generation systems due to their high efficiency. Anion exchange membrane (AEM) is a key component in fuel cells for the transfer of anion which is effect to the performance of the fuel cell system. \Therefore, it needs to have high chemical, mechanical, and thermal stabilities, as well as excellent electrochemical properties. For these reasons, various types of novel polymeric materials have been developed for the anion exchange membrane fuel cells. Especially, hydrocarbon based polymer materials such as poly(arylene ether sulfone), poly(ether ether ketone)(PEEK), polybenzimidazole (PBI) have been fabricated for use as electrolytes in fuel cell systems. Also, a number of preparation methods have been developed to enhance the performance of fuel cell membranes. In this study, we modified the monomer by chemical modification reaction and we synthesized the PEEK based polymer with different amination degree. Also we compared the chemical stability of the PEEK based membrane with different functional groups such as ammonium and imidazolium. Finally, the effect of the contents of the anion exchange groups in the PEEK based polymer was evaluated in terms of morphology, water behavior, mechanical properties, chemical stability and ion conductivity.
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