33,682 research outputs found
Opaque Service Virtualisation: A Practical Tool for Emulating Endpoint Systems
Large enterprise software systems make many complex interactions with other
services in their environment. Developing and testing for production-like
conditions is therefore a very challenging task. Current approaches include
emulation of dependent services using either explicit modelling or
record-and-replay approaches. Models require deep knowledge of the target
services while record-and-replay is limited in accuracy. Both face
developmental and scaling issues. We present a new technique that improves the
accuracy of record-and-replay approaches, without requiring prior knowledge of
the service protocols. The approach uses Multiple Sequence Alignment to derive
message prototypes from recorded system interactions and a scheme to match
incoming request messages against prototypes to generate response messages. We
use a modified Needleman-Wunsch algorithm for distance calculation during
message matching. Our approach has shown greater than 99% accuracy for four
evaluated enterprise system messaging protocols. The approach has been
successfully integrated into the CA Service Virtualization commercial product
to complement its existing techniques.Comment: In Proceedings of the 38th International Conference on Software
Engineering Companion (pp. 202-211). arXiv admin note: text overlap with
arXiv:1510.0142
Gluon GPDs and Exclusive Photoproduction of a Quarkonium in Forward Region
Forward photoproduction of can be used to extract Generalized Parton
Distributions(GPD's) of gluons. We analyze the process at twist-3 level and
study relevant classifications of twist-3 gluon GPD's. At leading power or
twist-2 level the produced is transversely polarized. We find that at
twist-3 the produced is longitudinally polarized. Our study shows that
in high energy limit the twist-3 amplitude is only suppressed by the inverse
power of the heavy quark mass relatively to the twist-2 amplitude. This
indicates that the power correction to the cross-section of unpolarized
can have a sizeable effect. We have also derived the amplitude of the
production of at twist-3, but the result contains end-point
singularities. The production of other quarkonia has been briefly discussed.Comment: Discussions of results are adde
Topology of Entanglement in Multipartite States with Translational Invariance
The topology of entanglement in multipartite states with translational
invariance is discussed in this article. Two global features are foundby which
one can distinguish distinct states. These are the cyclic unit and the
quantised geometric phase. Furthermore the topology is indicated by the
fractional spin. Finally a scheme is presented for preparation of these types
of states in spin chain systems, in which the degeneracy of the energy levels
characterises the robustness of the states with translational invariance.Comment: major revision. accepted by EPJ
Characterizing time series : when Granger causality triggers complex networks
In this paper, we propose a new approach to characterize time series with noise perturbations in both the time and frequency domains by combining Granger causality and complex networks. We construct directed and weighted complex networks from time series and use representative network measures to describe their physical and topological properties. Through analyzing the typical dynamical behaviors of some physical models and the MIT-BIH* human electrocardiogram data sets, we show that the proposed approach is able to capture and characterize various dynamics and has much potential for analyzing real-world time series of rather short length
Spectroscopic signatures of the Larkin-Ovchinnikov state in the conductance characteristics of a normal-metal/superconductor junction
Using a discrete-lattice approach, we calculate the conductance spectra
between a normal metal and an s-wave Larkin-Ovchinnikov (LO) superconductor,
with the junction interface oriented {\em along} the direction of the
order-parameter (OP) modulation. The OP sign reversal across one single nodal
line can induce a sizable number of zero-energy Andreev bound states around the
nodal line, and a hybridized midgap-states band is formed amid a
momentum-dependent gap as a result of the periodic array of nodal lines in the
LO state. This band-in-gap structure and its anisotropic properties give rise
to distinctive features in both the point-contact and tunneling spectra as
compared with the BCS and Fulde-Ferrell cases. These spectroscopic features can
serve as distinguishing signatures of the LO state.Comment: 8 pages, 5 figures; version as publishe
Carrier Sense Random Packet CDMA Protocol in Dual-Channel Networks
Code resource wastage is caused by the reason that many hopping frequency (FH) sequences are unused, which occurs under the condition that the number of the actual subnets needed for the tactical network is far smaller than the networking capacity of code division net¬working. Dual-channel network (DCN), consisting of one single control channel and multiple data channels, can solve the code resource wastage effectively. To improve the anti-jamming capability of the control channel of DCN, code division multiple access (CDMA) technology was introduced, and a carrier sense random packet (CSRP) CDMA protocol based on random packet CDMA (RP-CDMA) was proposed. In CSRP-CDMA, we provide a carrier sensing random packet mechanism and a packet-segment acknowledgement policy. Furthermore, an analytical model was developed to evaluate the performance of CSRP-CDMA networks. In this model, the impacts of multi-access interference from both inter-clusters and intra-clusters were analyzed, and the mathematical expressions of packet transmission success probability, normalized network throughput and signal interference to noise ratio, were also derived. Analytical and simulation results demonstrate that the normalized network throughput of CSRP-CDMA outperforms traditional RP-CDMA by 10%, which can guarantee the resource utilization efficiency of the control channel in DCNs
Bias and angular dependence of spin-transfer torque in magnetic tunnel junctions
We use spin-transfer-driven ferromagnetic resonance (ST-FMR) to measure the
spin-transfer torque vector T in MgO-based magnetic tunnel junctions as a
function of the offset angle between the magnetic moments of the electrodes and
as a function of bias, V. We explain the conflicting conclusions of two
previous experiments by accounting for additional terms that contribute to the
ST-FMR signal at large |V|. Including the additional terms gives us improved
precision in the determination of T(V), allowing us to distinguish among
competing predictions. We determine that the in-plane component of has a weak
but non-zero dependence on bias, varying by 30-35% over the bias range where
the measurements are accurate, and that the perpendicular component can be
large enough to be technologically significant. We also make comparisons to
other experimental techniques that have been used to try to measure T(V).Comment: 30 pages, 8 figures. Expanded with additional data and discussion. In
press at PR
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