123 research outputs found
Chapter Spectral Efficiency Analysis of Filter Bank MultiāCarrier (FBMC)ā Based 5G Networks with Estimated Channel State Information (CSI)
The heterogeneous cellular network (HCN) is most significant as a key technology for future fifth-generation (5G) wireless networks. The heterogeneous network consists of randomly macrocell base stations (MBSs) overlaid with femtocell base stations (FBSs). Stochastic geometry has been shown to be a very powerful tool to model, analyze, and design networks with random topologies such as wireless ad hoc, sensor networks, and multi-tier cellular networks. HCNs can be energy-efficiently designed by deploying various BSs belonging to different networks, which has drawn significant attention to one of the technologies for future 5G wireless networks. In this chapter, we propose switching off/on systems enabling the BSs in the cellular networks to efficiently consume the power by introducing active/sleep modes, which is able to reduce the interference and power consumption in the MBSs and FBSs on an individual basis as well as improve the energy efficiency of the cellular networks. We formulate the minimization of the power consumption for the MBSs and FBSs as well as an optimization problem to maximize the energy efficiency subject to throughput outage constraints, which can be solved by the Karush-Kuhn-Tucker (KKT) conditions according to the femto tier BS density. We also formulate and compare the coverage probability and the energy efficiency in HCN scenarios with and without coordinated multi-point (CoMP) to avoid coverage holes
Spectral Efficiency Analysis of Filter Bank MultiāCarrier (FBMC)ā Based 5G Networks with Estimated Channel State Information (CSI)
Filter bank multiācarrier (FBMC) modulation, as a potential candidate for physical data communication in the fifth generation (5G) wireless networks, has been widely investigated. This chapter focuses on the spectral efficiency analysis of FBMCābased cognitive radio (CR) systems, and spectral efficiency comparison is conducted with another three types of multiācarrier modulations: orthogonal frequency division multiplexing (OFDM), generalized frequency division multiplexing (GFDM), and universalāfiltered multiācarrier (UFMC). In order to well evaluate and compare the spectral efficiency, we propose two resource allocation (RA) algorithms for singleācell and twoācell CR systems, respectively. In the singleācell system, the RA algorithm is divided into two sequential steps, which incorporate subcarrier assignment and power allocation. In the twoācell system, a noncooperative game is formulated and the multiple access channel (MAC) technique assists to solve the RA problem. The channel state information (CSI) between CR users and licensed users cannot be precisely known in practice, and thus, an estimated CSI is considered by defining a prescribed outage probability of licensed systems. Numerical results show that FBMC can achieve the highest channel capacity compared with another three waveforms
Class Prior-Free Positive-Unlabeled Learning with Taylor Variational Loss for Hyperspectral Remote Sensing Imagery
Positive-unlabeled learning (PU learning) in hyperspectral remote sensing
imagery (HSI) is aimed at learning a binary classifier from positive and
unlabeled data, which has broad prospects in various earth vision applications.
However, when PU learning meets limited labeled HSI, the unlabeled data may
dominate the optimization process, which makes the neural networks overfit the
unlabeled data. In this paper, a Taylor variational loss is proposed for HSI PU
learning, which reduces the weight of the gradient of the unlabeled data by
Taylor series expansion to enable the network to find a balance between
overfitting and underfitting. In addition, the self-calibrated optimization
strategy is designed to stabilize the training process. Experiments on 7
benchmark datasets (21 tasks in total) validate the effectiveness of the
proposed method. Code is at: https://github.com/Hengwei-Zhao96/T-HOneCls.Comment: Accepted to ICCV 202
Parametric Modeling of a Magnetorheological Engine Mount Based on a Modified Polynomial Bingham Model
This work mainly addresses the establishment of a phenomenological mechanical model for magnetorheological (MR) engine mounts under frequency variation and magnetic variation effects. First, the mounts' reaction force is divided into three parts: a Coulomb damping force, an elastic reaction force, and a viscous damping force. Then, by using correlation analysis on these forces with the frequency and magnetic field, a modified polynomial Bingham parameterized model is proposed. This model takes external current and external loading frequency as the variables. As a result of analyzing the relationship between energy dissipation and storage caused by the external displacement excitation, an identifying method is proposed to identify the nine parameters in the model. Based on this model, an experimental scheme was designed, and the forceādisplacement relationship of a typical MR mount under different working conditions was tested through an experiment. By using the proposed method, the relationship of the reaction force of an MR mount with current and external loading frequency was obtained. The experimental results show that the proposed model can correctly reflect the wide-frequency dynamic characteristics of the mounts in dynamic stiffness, lagging angle, and hysteretic curve
Bridging the Gap: A Unified Video Comprehension Framework for Moment Retrieval and Highlight Detection
Video Moment Retrieval (MR) and Highlight Detection (HD) have attracted
significant attention due to the growing demand for video analysis. Recent
approaches treat MR and HD as similar video grounding problems and address them
together with transformer-based architecture. However, we observe that the
emphasis of MR and HD differs, with one necessitating the perception of local
relationships and the other prioritizing the understanding of global contexts.
Consequently, the lack of task-specific design will inevitably lead to
limitations in associating the intrinsic specialty of two tasks. To tackle the
issue, we propose a Unified Video COMprehension framework (UVCOM) to bridge the
gap and jointly solve MR and HD effectively. By performing progressive
integration on intra and inter-modality across multi-granularity, UVCOM
achieves the comprehensive understanding in processing a video. Moreover, we
present multi-aspect contrastive learning to consolidate the local relation
modeling and global knowledge accumulation via well aligned multi-modal space.
Extensive experiments on QVHighlights, Charades-STA, TACoS , YouTube Highlights
and TVSum datasets demonstrate the effectiveness and rationality of UVCOM which
outperforms the state-of-the-art methods by a remarkable margin
Treatment of Unruptured Vertebral Artery Aneurysm Involving Posterior Inferior Cerebellar Artery With Pipeline Embolization Device
Background: Treatment of unruptured vertebral artery aneurysm involving posterior inferior cerebellar artery (PICA) is challenging. The experience of pipeline embolization device (PED) therapy for these lesions is still limited.Objective: To evaluate the safety and efficacy of the PED for unruptured vertebral artery aneurysm involving PICA.Methods: Thirty-two patients with unruptured vertebral artery aneurysm involving PICA underwent treatment with PED were retrospectively identified. Procedure-related complications, PICA patency, clinical, and angiographic outcomes were analyzed.Results: Thirty-two aneurysms were successfully treated without any procedure-related complications. Images were available in 30 patients (93.8%) during a period of 3ā26 months follow-up (average 8.4 months), which confirmed complete occlusion in 17 patients (56.5%), near-complete occlusion in 9 patients (30%), and incomplete occlusion in one patient (3.3%). Parent artery occlusion (PAO) was occurred in 3 patients (10%). Twenty-eight of 30 PICA remained patent. The two occlusions of PICA were secondary to PAO. At a mean of 20.7 months (range 7ā50 months) clinical follow-up, all the patients achieved a favorable outcome without any new neurological deficit.Conclusion: PED seems to be a safe and effective alternative endovascular option for patients with unruptured vertebral artery aneurysm involving PICA
Mechanism of bubble action in backfill slurry and the evolution of its rheological properties
Cemented paste backfill is a suspension composed of solid-liquid-gas three-phase. For a long time, the focus has been mostly on the rheological behavior of solid-liquid two-phase, while the effect of gas phase on slurry with complex rheological behavior remains obscure. The gaseous phase components can significantly reduce the yield stress and viscosity of high-concentration backfilling slurry, which plays a significant role on improving pipeline transportation performance and reducing pipeline wear. In order to reveal the mechanism of bubbles to its rheological properties of slurry, the gas content of slurry was controlled by adjusting the content of air entrainment agent (TTAB), and tests such as surface tension, air content and rheological properties were carried out to find out the influence of bubbles on the rheological behavior of slurry, and capillary force (Fcay) and the bubble evolution model of dimensionless yield stress (\begin{document}\end{document}) were introduced to analyze the bubble evolution characteristics in the slurry and reveal the mechanism of bubbles on the rheological properties of slurry. The results showed that under the low gas content ( < 12.5%), the gas phase had little effect on the rheological behavior of the suspended slurry. As the increase of gas content, the effect of bubbles on the rheological behavior of backfilling slurry was immense. Under the action of the air-entraining, the bubble surface had a repulsive force on the fine particles in the slurry, and could reduce the adsorption capacity of cement and solid waste, resulting in a decreasing trend of slurry yield stress and increasing fluidity. Based on capillary force (Fcay) and dimensionless yield stress theory (\begin{document}\end{document}), evolutional mechanism of rheological properties of slurry in different gas content was analyzed. It could be seen that as the gas content increased (12.5%ā27.7%), the surface tension and yield stress of slurry decreased, and the bubble would be deformed by extrusion. When the gas content (28.6%) was high, the bubbles in the slurry were easy to burst. In addition, bubbles, retained inside the backfilling body, leading to strength degradation, so the effect of bubbles on the mechanical properties of the backfilling body and its solution were explored and three effective measures were proposed. By revealing the effect of bubbles on the rheological properties of suspension slurry and its evolution characteristics, it provides theoretical support for the development of high bubble filling, which can achieve the goal of drag reduction and friction reduction
The Outcome of the 2022 Landslide4Sense Competition: Advanced Landslide Detection from Multi-Source Satellite Imagery
The scientific outcomes of the 2022 Landslide4Sense (L4S) competition organized by the Institute of Advanced Research in Artificial Intelligence (IARAI) are presented here. The objective of the competition is to automatically detect landslides based on large-scale multiple sources of satellite imagery collected globally. The 2022 L4S aims to foster interdisciplinary research on recent developments in deep learning (DL) models for the semantic segmentation task using satellite imagery. In the past few years, DL-based models have achieved performance that meets expectations on image interpretation, due to the development of convolutional neural networks (CNNs). The main objective of this article is to present the details and the best-performing algorithms featured in this competition. The winning solutions are elaborated with state-of-the-art models like the Swin Transformer, SegFormer, and U-Net. Advanced machine learning techniques and strategies such as hard example mining, self-training, and mix-up data augmentation are also considered. Moreover, we describe the L4S benchmark data set in order to facilitate further comparisons, and report the results of the accuracy assessment online. The data is accessible on Future Development Leaderboard for future evaluation at https://www.iarai.ac.at/landslide4sense/challenge/ , and researchers are invited to submit more prediction results, evaluate the accuracy of their methods, compare them with those of other users, and, ideally, improve the landslide detection results reported in this article
The effect of meteoric water on the very fine crystalline dolomite reservoir in the shallow burial zone: A case study of the Ma55 submember of Majiagou Formation in Ordos Basin
The meteoric water has obviously changed the physical properties of dolostone reservoirs in the vertical vadose zone and the horizontal phreatic zone, but its influence on the dolostone reservoirs in the shallow burial zone beneath the phreatic surface is still unclear. This study aims to reveal the effect of meteoric water on the dolostone reservoirs in the shallow burial zone through X-ray diffraction, cathodoluminescence, C, O, and Sr isotope using the sample from Majiagou Formation in the Daniudi gas field, Ordos Basin. The diagenesis and paragenesis of the Ma 55 submember were identified and interpreted through petrological study, combined with data from electron probe, X-ray diffraction analysis, and geochemical parameters of diagenetic minerals. The color of the very fine crystalline dolomite under the cathodeluminescence is dark red and red. The order degree of dolomite ranges from 0.54 to 0.91, showing the origin of early seepage-reflux dolomitization. There are a large number of different calcite cements as fills within the pores and fractures. The color of the calcite cement under the cathodoluminescence is orange-yellow, with a zonal structure. Hydrothermal fluid during late diagenesis could be identified by the authigenic fluorite filling in the fractures. According to the assembly of diagenetic minerals, the very fine crystalline dolostones have experienced the seepage-reflux dolomitization, meteoric water dissolution, shallow burial cementation and late cementation. The void spaces of the very fine crystalline dolostones are intercrystalline pores and microfractures. Although a large number of dissolved pores and caves developed in the period of meteoric water dissolution, these caves and dissolved pores has been mostly filled by multi-stages of cementation. Therefore, the effect of meteoric water on dolostone reservoirs in the shallow burial zone beneath the phreatic surface is not obvious. The main controlling factor for the quality of dolostone reservoir was dolomitization. This study provides a new understanding of the influence of meteoric water on reservoir quality in the shallow burial zone during the paleokarst period
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