The Extended Discrete Element Method (XDEM) is a novel and innovative numerical simulation technique that extends classical Discrete Element Method (DEM) (which simulates the motion of granular material), by additiona...
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ISBN:
(纸本)9781538677698
The Extended Discrete Element Method (XDEM) is a novel and innovative numerical simulation technique that extends classical Discrete Element Method (DEM) (which simulates the motion of granular material), by additional properties such as the chemical composition, thermodynamic state, stress/strain for each particle. It has been applied successfully to numerous industries involving the processing of granular materials such as sand, rock, wood or coke [16], [17]. In this context, computational simulation with (X)DEM has become a more and more essential tool for researchers and scientific engineers to set up and explore their experimental processes. However, increasing the size or the accuracy of a model requires the use of High Performance Computing (HPC) platforms over a parallelized implementation to accommodate the growing needs in terms of memory and computation time. In practice, such a parallelization is traditionally obtained using either MPI (distributed memory computing), openMP (shared memory computing) or hybrid approaches combining both of them. In this paper, we present the results of our effort to implement an openMP version of XDEM allowing hybrid MPI+openMP simulations (XDEM being already parallelized with MPI). Far from the basic openMP paradigm and recommendations (which simply summarizes by decorating the main computation loops with a set of openMP pragma), the openMP parallelization of XDEM required a fundamental code re-factoring and careful tuning in order to reach good performance. There are two main reasons for those difficulties. Firstly, XDEM is a legacy code developed for more than 10 years, initially focused on accuracy rather than performance. Secondly, the particles in a DEM simulation are highly dynamic: they can be added, deleted and interaction relations can change at any timestep of the simulation. Thus this article details the multiple layers of optimization applied, such as a deep data structure profiling and reorganization, the usa
In this letter, we propose a trellis-coded nonorthogonal multiple access (NOMA) scheme. The signals for different users are produced by trellis coded modulation (TCM) and then superimposed on different power levels. B...
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Recent studies have demonstrated the superiority of non-orthogonal multiple access (NOMA) over orthogonal multiple access (OMA) in cooperative communication networks. In this paper, we propose a novel half-duplex coop...
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Twin vertices of a graph have the same open neighbourhood. If they are not adjacent, then they are called duplicates and contribute the eigenvalue zero to the adjacency matrix. Otherwise they are termed co-duplicates,...
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In this paper, a novel approach that uses an unmanned aerial vehicle \(UAV\)-carried intelligent reflector \(IR\) is proposed to enhance the performance of millimeter wave \(mmW\) networks. In particular, the UAV-IR i...
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Beyond the traditional use of frequency-shift keying (FSK) radar in tracking moving targets, this work further extends its capability in localizing stationary human subject based on the phase information extracted fro...
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Beyond the traditional use of frequency-shift keying (FSK) radar in tracking moving targets, this work further extends its capability in localizing stationary human subject based on the phase information extracted from the detected vital sign signals. Unlike the I/Q-trajectory-based range detection method that relies on trajectory analysis and therefore is prone to the effect of DC offset and trajectory distortion, the FSK-based technique used in this paper works in spectrum domain utilizing only the motion frequency of the target with a reliable signal-to-noise ratio (SNR). A 5.8-GHz industrial, scientific, and medical (ISM) band FSK radar with a frequency difference of 15 MHz is designed and implemented. Experiments demonstrate that, besides tracking walking human subject, the proposed FSK technique can successfully recover range information of a seated human subject at different locations. A preliminary investigation of the detection robustness and consistency is presented by measuring the range of a 4-mm peak-to-peak periodic motion generated by an actuator over a 90-s observation window.
Deep convolutional neural networks (CNNs) with strong expressive ability have achieved impressive performances on single image super-resolution (SISR). However, their excessive amounts of convolutions and parameters u...
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The development of dual-functional radar-communication (DFRC) systems, where vehicle localization and tracking can be combined with vehicular communication, will lead to more efficient future vehicular networks. In th...
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Focus accuracy is an essential factor that affects the astronomical observations quality. The accurate measure of celestial objects properties depends on focus. Automatic focusing is necessary for astronomical observa...
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Focus accuracy is an essential factor that affects the astronomical observations quality. The accurate measure of celestial objects properties depends on focus. Automatic focusing is necessary for astronomical observations imaging systems. This paper presents a modified focus measure operator. It also proposes the use of fuzzy logic, to transform images, because of its tolerant of imprecise and incomplete data. The focus operators are applied into two sequences of star clusters observations. The experimental results show that the suggested measure overall score exceeds the previous operators.
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