In this paper, we investigate secrecy communications in two-hop wireless relaying networks which consist of one source, one amplify-and-forward (AF) relay, one legitimate destination, and one eavesdropper. To prevent ...
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ISBN:
(纸本)9781467325660
In this paper, we investigate secrecy communications in two-hop wireless relaying networks which consist of one source, one amplify-and-forward (AF) relay, one legitimate destination, and one eavesdropper. To prevent the eavesdropper from intercepting the source message, we make the destination send the intended noise to the AF relay during the first phase. This is referred to as cooperative jamming. According to the channel information at the destination, we address two types of jamming power allocation;(i) rate-optimal power allocation and (ii) outage-optimal power allocation. More specifically, without the instantaneous channel knowledge for the eavesdropper side, the outage probability of the secrecy rate is minimized with respect to the intended noise power level. We show that the outage-optimal allocation gives almost the same outage probability as the rateoptimal one. In addition, the jamming power consumption can be significantly reduced compared to the fixed and rate-optimal power allocation methods.
We use a particle-based method to simulate incompressible flows, where the Fast Multipole Method (FMM) is used to accelerate the calculation of particle interactions. The most time-consuming kernelsâ"the Bio...
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ISBN:
(纸本)9781467308052
We use a particle-based method to simulate incompressible flows, where the Fast Multipole Method (FMM) is used to accelerate the calculation of particle interactions. The most time-consuming kernelsâ"the Biot-Savart equation and stretching term of the vorticity equationâ"are mathematically reformulated so that only two Laplace scalar potentials are used instead of six, while automatically ensuring divergence-free far-field computation. Based on this formulation, and on our previous work for a scalar heterogeneous FMM algorithm, we develop a new FMM-based vortex method capable of simulating general flows including turbulence on heterogeneous architectures, which distributes the work between multi-core CPUs and GPUs to best utilize the hardware resources and achieve excellent scalability. The algorithm also uses new data structures which can dynamically manage inter-node communication and load balance efficiently but with only a small parallel construction overhead. This algorithm can scale to large-sized clusters showing both strong and weak scalability. Careful error and timing trade-off analysis are also performed for the cutoff functions induced by the vortex particle method. Our implementation can perform one time step of the velocity+stretching for one billion particles on 32 nodes in 55.9 seconds, which yields 49.12 Tflop/s.
Recognizing that power and cooling cost for data centers are increasing, we address in this study the thermal impact of storage systems. In the first phase of this work, we generate the thermal profile of a storage se...
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Recognizing that power and cooling cost for data centers are increasing, we address in this study the thermal impact of storage systems. In the first phase of this work, we generate the thermal profile of a storage server containing three hard disks. The profiling results show that disks have comparable thermal impacts as processing and networking elements to overall storage node temperature. We develop a thermal model to estimate the outlet temperature of a storage server based on processor and disk utilizations. The thermal model is validated against data acquired by an infrared thermometer as well as build-in temperature sensors on disks. Next, we apply the thermal model to investigate the thermal impact of workload management on storage systems. Our study suggests that disk-aware thermal management techniques have significant impacts on reducing cooling cost of storage systems. We further show that this work can be extended to analysis the cooling cost of data centers with massive storage capacity.
Energy consumption in downlink mode is becoming an important topic as cellular communications grow into a large scale enterprise. The search for high rates keeping energy constraints low has put forward the idea that ...
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ISBN:
(纸本)9781457720529
Energy consumption in downlink mode is becoming an important topic as cellular communications grow into a large scale enterprise. The search for high rates keeping energy constraints low has put forward the idea that cells with smaller size may improve not only the capacity of the network, but also reduce the amount of energy that is needed to achieve such capacities. When using heterogeneous networks, users can be encouraged to handoff to a femtocell, that offers better capacity per unit energy spent, by means of different handoff strategies. These strategies may also improve the energy use of the network if the handoff priority is given to both, capacity, and energy use.
The differentiation by integration method with Jacobi polynomials was originally introduced by Mboup, Join and Fliess [22], [23]. This paper generalizes this method from the integer order to the fractional order for e...
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The differentiation by integration method with Jacobi polynomials was originally introduced by Mboup, Join and Fliess [22], [23]. This paper generalizes this method from the integer order to the fractional order for estimating the fractional order derivatives of noisy signals. The proposed fractional order differentiator is deduced from the Jacobi orthogonal polynomial filter and the Riemann-Liouville fractional order derivative definition. Exact and simple formula for this differentiator is given where an integral formula involving Jacobi polynomials and the noisy signal is used without complex mathematical deduction. Hence, it can be used both for continuous-time and discrete-time models. The comparison between our differentiator and the recently introduced digital fractional order Savitzky-Golay differentiator is given in numerical simulations so as to show its accuracy and robustness with respect to corrupting noises.
This article consists of a collection of slides from the author's conference presentation on Ivy Bridge, power management applications of the third generation core Intel micro architecture. Some of the specific to...
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ISBN:
(纸本)9781467388801
This article consists of a collection of slides from the author's conference presentation on Ivy Bridge, power management applications of the third generation core Intel micro architecture. Some of the specific topics discussed include: an overview of the Ivy Bridge architecture and supported applications; power scaling and management facilities; core product features; power efficiency; voltage control and optimization technqiues; power sharing capabilities; and system architecture.
Unlike stream ciphers, block ciphers are very essential for parallel processing applications. In this paper, the first hardware realization of chaotic-based block cipher is proposed for image encryption applications. ...
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In this article a cost-effective and simple system (circuit and algorithm) which allows recognizing different kinds of films by their magneto-field conductive properties is demonstrated. The studied signals are genera...
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It is clear that none of the current available numerical schemes which may be adopted to solve transport phenomena in porous media fulfill all the required robustness conditions. That is while the finite difference me...
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It is clear that none of the current available numerical schemes which may be adopted to solve transport phenomena in porous media fulfill all the required robustness conditions. That is while the finite difference methods are the simplest of all, they face several difficulties in complex geometries and anisotropic media. On the other hand, while finite element methods are well suited to complex geometries and can deal with anisotropic media, they are more involved in coding and usually require more execution time. Therefore, in this work we try to combine some features of the finite element technique, namely its ability to work with anisotropic media with the finite difference approach. We reduce the multipoint flux, mixed finite element technique through some quadrature rules to an equivalent cell-centered finite difference approximation. We show examples on using this technique to single-phase flow in anisotropic porous media.
In this paper, we present a methodology to model the optimal binary search tree problem as a directed acyclic graph to extract all possible optimal solutions. We provide a mechanism to find optimal binary search trees...
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ISBN:
(纸本)9781920682989
In this paper, we present a methodology to model the optimal binary search tree problem as a directed acyclic graph to extract all possible optimal solutions. We provide a mechanism to find optimal binary search trees relative to different types of cost functions, sequentially. We prove that for a set of n keys our optimization procedure makes O(n3) arithmetic operations per cost function such as weighted depth or average weighted depth.
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