7,131 research outputs found
Hom-Big Brackets: Theory and Applications
In this paper, we introduce the notion of hom-big brackets, which is a
generalization of Kosmann-Schwarzbach's big brackets. We show that it gives
rise to a graded hom-Lie algebra. Thus, it is a useful tool to study
hom-structures. In particular, we use it to describe hom-Lie bialgebras and
hom-Nijenhuis operators
Cognitive Beamforming for Multiple Secondary Data Streams With Individual SNR Constraints
In this paper, we consider cognitive beamforming for multiple secondary data
streams subject to individual signal-to-noise ratio (SNR) requirements for each
secondary data stream. In such a cognitive radio system, the secondary user is
permitted to use the spectrum allocated to the primary user as long as the
caused interference at the primary receiver is tolerable. With both secondary
SNR constraint and primary interference power constraint, we aim to minimize
the secondary transmit power consumption. By exploiting the individual SNR
requirements, we formulate this cognitive beamforming problem as an
optimization problem on the Stiefel manifold. Both zero forcing beamforming
(ZFB) and nonzero forcing beamforming (NFB) are considered. For the ZFB case,
we derive a closed form beamforming solution. For the NFB case, we prove that
the strong duality holds for the nonconvex primal problem and thus the optimal
solution can be easily obtained by solving the dual problem. Finally, numerical
results are presented to illustrate the performance of the proposed cognitive
beamforming solutions.Comment: This is the longer version of a paper to appear in the IEEE
Transactions on Signal Processin
Transfer of Gravitational Information through a Quantum Channel
Gravitational information is incorporated into an atomic state by correlation
of the internal and external degrees of freedom of the atom, in the present
study of the atomic interferometer. Thus it is difficult to transfer
information by using a standard teleportation scheme. In this paper, we propose
a novel scheme for the transfer of gravitational information through a quantum
channel provided by the entangled atomic state. Significantly, the existence of
a quantum channel suppresses phase noise, improving the sensitivity of the
atomic interferometer. Thus our proposal provides novel readout mechanism for
the interferometer with an improved signal-to-noise ratio
Photon Polarization in the b->s gamma processes in the Left-Right Symmetric Model
The circular-polarization of the photon in the radiative B decays is
dominantly left-handed in the Standard Model (SM), but the right-handed
polarization may be enhanced in some new physics models with right-handed
currents, such as the Left-Right Symmetric Model (LRSM). In this article, we
investigate how large this wrong polarization could be within the allowed
parameter space of the LRSM. We show that in LRSM, the right-handed
polarization of the photon in the processes could be largely
enhanced by the mixing contributions because of the helicity flip on
the internal top quark line of the penguin diagrams and the enhancement by the
CKM factor . We discuss the sensitivity of the proposed
methods to determine the photon polarization to the LRSM as well
as their complementary role compared to the direct search of right-handed
charged gauge bosons at LHC.Comment: 30pages, 5 figures, published version; references adde
Towards Autonomous Unmanned Vehicle Systems
As an emerging technology, autonomous Unmanned Vehicle Systems (UVS) have found not only many military applications, but also various civil applications. For example, Google, Amazon and Facebook are developing their UVS plans to explore new markets. However, there are still a lot of challenging problems which deter the UVS’s development. We study two important and challenging problems in this dissertation, i.e. localization and 3D reconstruction. Specifically, most GPS based localization systems are not very accurate and can have problems in areas where no GPS signals are available. Based on the Received Signal Strength Indication (RSSI) and Inertial Navigation System (INS), we propose a new hybrid localization system, which is very efficient and can account for dynamic communication environments. Extensive simulation results demonstrate the efficiency of the proposed localization system. Besides, 3D reconstruction is a key problem in autonomous navigation and hence very important for UVS.With the help of high-speed Internet and powerful cloud servers, the light-weight computers on the UVS can now execute computationally expensive computer vision based algorithms. We develop a 3D reconstruction scheme which employs cloud computing to perform realtime 3D reconstruction. Simulations and experiments show the efficacy and efficiency of our scheme
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