1,261 research outputs found
Fano resonance in a normal metal/ferromagnet-quantum dot-superconductor device
We investigate theoretically the Andreev transport through a quantum dot
strongly coupled with a normal metal/ferromagnet and a superconductor
(N/F-QD-S), in which the interplay between the Kondo resonance and the Andreev
bound states (ABSs) has not been clearly clarified yet. Here we show that the
interference between the Kondo resonance and the ABSs modifies seriously the
lineshape of the Kondo resonance, which manifests as a Fano resonance. The
ferromagnetic lead with spin-polarization induces an effective field, which
leads to splitting both of the Kondo resonance and the ABSs. The
spin-polarization together with the magnetic field applied provides an
alternative way to tune the lineshape of the Kondo resonances, which is
dependent of the relative positions of the Kondo resonance and of the ABSs.
These results indicate that the interplay between the Kondo resonance and the
ABSs can significantly affect the Andreev transport, which could be tested by
experiments.Comment: 8pages, 7figure
Comparative analysis of partitioned stator flux reversal PM machine and magnetically geared machine operating in Stator-PM and Rotor-PM modes
In this paper, the partitioned stator flux reversal permanent magnet (PM) (PS-FRPM) machine and the conventional magnetically geared (MG) machine operating in both stator-PM (SPM) and rotor-PM (RPM) modes are comparatively analyzed in terms of electromagnetic performance to provide design guides for a MG machine regarding: (a) a SPM or RPM type machine and (b) a higher or lower gear ratio machine. It is found that a SPM type machine is recommended, since both PS-FRPM and MG machines operating in SPM modes have a higher phase back-EMF and hence torque than their RPM counterparts, respectively, as a result of a similar phase flux-linkage but a higher electric frequency since the iron piece number is larger than the PM pole-pair number. Moreover, a smaller gear ratio machine is preferred from the perspective of a higher power factor and hence a lower inverter power rating, as the conventional MG machines with higher gear ratios suffer from larger flux-leakage, higher synchronous reactance and hence lower power factors, as well as higher iron losses, than the PS-FRPM machines. However, higher gear ratio machines feature lower cogging torques and torque ripples due to the smaller difference between the PM pole-pair number and iron piece number. Both prototypes of PS-FRPM machine operating in SPM mode and MG machine operating in RPM mode are built and tested to verify the FE predicted results
New type of hydrogenlike charm-pion or charm-kaon matter
Borrowing the structures of the hydrogen atom, molecular ion, and diatomic
molecule, we predict the nature of a new type of hydrogenlike charm-pion or
charm-kaon matter that could be obtained by replacing the proton and electron
in hydrogen matter with a charmed meson and a pion or a kaon, respectively. We
find that the spectra of the atom, molecular ion, and diatomic molecule can be
obtained simultaneously with the Coulomb potential for the hydrogen, the
charm-pion, and the charm-kaon systems. The predicted charm-pion matter also
allows us to explore the mass shift mediated by the strong interaction. For the
charm-pion and charm-kaon systems, the strong interactions could lead to
binding energy shifts. Our calculations suggests that the binding energy shifts
in charm-pion systems are in the order of several to tens of eV. For the
charm-kaon systems, the results are in the order of tens to hundreds of eV.
Exploring hydrogenlike charm-pion matter must lead to new demands for
high-precision experiments.Comment: 5 pages, 4 figures and 1 table. Typos corrected. Accepted by Phys.
Rev.
Characterizing and Subsetting Big Data Workloads
Big data benchmark suites must include a diversity of data and workloads to
be useful in fairly evaluating big data systems and architectures. However,
using truly comprehensive benchmarks poses great challenges for the
architecture community. First, we need to thoroughly understand the behaviors
of a variety of workloads. Second, our usual simulation-based research methods
become prohibitively expensive for big data. As big data is an emerging field,
more and more software stacks are being proposed to facilitate the development
of big data applications, which aggravates hese challenges. In this paper, we
first use Principle Component Analysis (PCA) to identify the most important
characteristics from 45 metrics to characterize big data workloads from
BigDataBench, a comprehensive big data benchmark suite. Second, we apply a
clustering technique to the principle components obtained from the PCA to
investigate the similarity among big data workloads, and we verify the
importance of including different software stacks for big data benchmarking.
Third, we select seven representative big data workloads by removing redundant
ones and release the BigDataBench simulation version, which is publicly
available from http://prof.ict.ac.cn/BigDataBench/simulatorversion/.Comment: 11 pages, 6 figures, 2014 IEEE International Symposium on Workload
Characterizatio
All-Optical 1-to-8 Wavelength Multicasting at 20 Gbit/s Exploiting Self-Phase Modulation in Dispersion Flattened Highly Nonlinear Photonic Crystal Fiber
All-optical multicasting of performing data routing from single node to multiple destinations in the optical domain is promising for next generation ultrahigh-peed photonic networks. Based on the self-phase modulation in dispersion flattened highly nonlinear photonic crystal fiber and followed spectral filtering, simultaneous 1-to-8 all-optical wavelength multicasting return-to-zero (RZ) signal at 20 Gbit/s with 100 GHz channel spaced is achieved. Wavelength tunable range and dynamic characteristic of proposed wavelength multicasting scheme is further investigated. The results show our designed scheme achieve operation wavelength range of 25 nm, OSNR of 32.01 dB and Q factor of 12.8. Moreover, the scheme has simple structure as well as high tolerance to signal power fluctuation
- …