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121.
We provide a variety of classes of functions that can be realized as the mean curvature on the boundary of the standard n dimensional ball, n ≥ 3, with respect to some scalar flat metric. Because of the presence of some critical nonlinearity, blow up phenomena occur and existence results are highly nontrivial since one has to overcome topological obstructions. Our approach consists of, on one hand, developing a Morse theoretical approach to this problem through a Morse-type reduction of the associated Euler–Lagrange functional in a neighborhood of its critical points at Infinity and, on the other hand, extending to this problem some topological invariants introduced by A. Bahri in his study of Yamabe type problems on closed manifolds.  相似文献   
122.
In Next Generation Networks (NGN), survivability and availability are becoming more and more key features. Reliability gains more importance in high- capacity networks where IP and optical technologies have converged toward a common control plane, such as GMPLS. In most previous research works, survivability aspects were mainly limited to a single fiber failure and a few considered the differentiated reliability concepts when routing new connection requests. In this article, a novel survivable multicast routing mechanism under SRLG constraints is proposed. We first formulate the problem as an Integer Linear Programming (ILP) model that is shown NP-Complete. We then propose a heuristic algorithm that alleviates the problem’s complexity by decomposing it into two sub-problems resolved separately. Compared with another algorithm proposed in the literature, our algorithm allows for higher acceptance rates even for stringent reliability requirements.  相似文献   
123.
视觉特征提取是听视觉语音识别研究的热点问题。文章引入了一种稳健的基于Visemic LDA的口形动态特征,这种特征充分考虑了发音时口形轮廓的变化及视觉Viseme划分。文章同时提出了一利利用语音识别结果进行LDA训练数据自动标注的方法。这种方法免去了繁重的人工标注工作,避免了标注错误。实验表明,将'VisemicLDA视觉特征引入到听视觉语音识别中,可以大大地提高噪声条件下语音识别系统的识别率;将这种视觉特征与多数据流HMM结合之后,在信噪比为10dB的强噪声情况下,识别率仍可以达到80%以上。  相似文献   
124.
The quantum noise and the squeezing effect, in the transmitted light, by a dipolariton system formed by a double quantum wells microcavity in the strong coupling regime are investigated. It is shown that the indirect exciton nonlinearity generates stronger squeezing than the direct exciton nonlinearity, nevertheless produces very high fluctuations for some particular detunings and nonlinearities. The system shows a considerable sensitivity to the thermal excitations where the coupling to the direct and indirect excitonic thermal baths progressively destroys the nonclassical effect. Despite that, indirect exciton squeezing manifests a higher resistance against the thermal bath temperature. As a result, the emission field is strongly governed by the indirect excitons, varying between robust squeezing and excess noise.  相似文献   
125.
In this paper, we prove the existence of minimizers of a class of multiconstrained variational problems. We consider systems involving a nonlinearity that does not satisfy compactness, monotonicity, neither symmetry properties. Our approach hinges on the concentration-compactness approach. In the second part, we will treat orthogonal constrained problems for another class of integrands using density matrices method.  相似文献   
126.
In this paper, we propose to apply a simple superposition coding strategy for downlink of OFDMA systems. The novelty of this paper consists on allowing at most two users to share the same subchannel. The main idea is to consider the subchannels allocated to the users with the weakest link, and allow these subchannels to be shared by some potential users who can transmit some number of bits with only a small amount of power. To decrease the overhead of the proposed OFDMA system, we restrict to use a predetermined superposition encoding|decoding scheme. We address the problem of resource allocation, which consists on finding the optimal subchannel assignment in the OFDMA system. A low complexity algorithm, denoted Share Specific Subcarrier Allocation (SSSA) is then proposed. It offers a fairness allocation among users. This can be done by taking into account all user’s buffer states information. Simulation results confirm that the proposed technique outperforms the classical algorithms in terms of total throughput and dropping probability.  相似文献   
127.
In this paper, we present two methods of computing the spectrum of a compact integral operator. The first method is based on an exact matrix representation of the operator. The second method uses a convenient quadrature method to discretisize the integral operator and to provide accurate approximations to the spectrum and the eigenfunctions of this later. Also, we show how our methods can be used in the framework of some stable procedures for the approximation of f the normal solution of the minimal L2-norm of the integral equation of the first kind Af = g, which is often an ill-posed equation. These procedures are based on a spectral expansion of the operator A. To finish, we give some numerical examples that illustrate the results of this work.  相似文献   
128.
In this paper, we further investigate the problem of commutativity up to a factor (or λ-commutativity) in the setting of bounded and unbounded linear operators in a complex Hilbert space. The results are based on a new approach to the problem. We finish the paper by a conjecture on the commutativity of self-adjoint operators.  相似文献   
129.
An analytical solution for a master equation describing the dynamics of a qubit interacting with a nonlinear Kerr-like cavity through intensity-dependent coupling is established. A superposition of squeezed coherent states is propped as the initial cavity field. The dynamics of the entangled qubit-cavity states are explored by negativity for different deformed function of the intensity-dependent coupling. We have examined the effects of the Kerr-like nonlinearity and the qubit-cavity detuning as well as the phase cavity damping on the generated entanglement. The intensity-dependent coupling increases the sensitivity of the generated entanglement to the phase-damping. The stability and the strength of the entanglement are controlled by the Kerr-like nonlinearity, the qubit-cavity detuning, and the initial cavity non-classicality. These physical parameters enhance the robustness of the qubit-cavity entanglement against the cavity phase-damping. The high initial cavity non-classicality enhances the robustness of the qubit-cavity entanglement against the phase-damping effect.  相似文献   
130.
We show that if a densely defined closable operator A is such that the resolvent set of A2 is nonempty, then A is necessarily closed. This result is then extended to the case of a polynomial p ( A ) $p(A)$ . We also generalize a recent result by Sebestyén–Tarcsay concerning the converse of a result by J. von Neumann. Other interesting consequences are also given. One of them is a proof that if T is a quasinormal (unbounded) operator such that T n $T^n$ is normal for some n 2 $n\ge 2$ , then T is normal. Hence a closed subnormal operator T such that T n $T^n$ is normal is itself normal. We also show that if a hyponormal (nonnecessarily bounded) operator A is such that A p $A^p$ and A q $A^q$ are self-adjoint for some coprime numbers p and q, then A must be self-adjoint.  相似文献   
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