Deep Reinforcement Learning for Vehicular Edge Computing: An Intelligent Offloading System

The development of smart vehicles brings drivers and passengers a comfortable and safe environment. Various emerging applications are promising to enrich users' traveling experiences and daily life. However, how to execute computing-intensive applications on resource-constrained vehicles still faces huge challenges. In this article, we construct an intelligent offloading system for vehicular edge computing by leveraging deep reinforcement learning. First, both the communication and computation states are modelled by finite Markov chains. Moreover, the task scheduling and resource allocation strategy is formulated as a joint optimization problem to maximize users' Quality of Experience (QoE). Due to its complexity, the original problem is further divided into two sub-optimization problems. A two-sided matching scheme and a deep reinforcement learning approach are developed to schedule offloading requests and allocate network resources, respectively. Performance evaluations illustrate the effectiveness and superiority of our constructed system

Emergency warning messages dissemination in vehicular social networks: A trust based scheme

To ensure users' safety on the road, a plethora of dissemination schemes for Emergency Warning Messages (EWMs) have been proposed in vehicular networks. However, the issue of false alarms triggered by malicious users still poses serious challenges, such as disruption of vehicular traffic especially on highways leading to precarious effects. This paper proposes a novel Trust based Dissemination Scheme (TDS) for EWMs in Vehicular Social Networks (VSNs) to solve the aforementioned issue. To ensure the authenticity of EWMs, we exploit the user-post credibility network for identifying true and false alarms. Moreover, we develop a reputation mechanism by calculating a trust-score for each node based on its social-utility, behavior, and contribution in the network. We utilize the hybrid architecture of VSNs by employing social-groups based dissemination in Vehicle-to-Infrastructure (V2I) mode, whereas nodes' friendship-network in Vehicle-to-Vehicle (V2V) mode. We analyze the proposed scheme for accuracy by extensive simulations under varying malicious nodes ratio in the network. Furthermore, we compare the efficiency of TDS with state-of-the-art dissemination schemes in VSNs for delivery ratio, transmission delay, number of transmissions, and hop-count. The experimental results validate the significant efficacy of TDS in accuracy and aforementioned network parameters. © 2019 Elsevier Inc

COMICS: a community property-based triangle motif clustering scheme

With the development of science and technology, network scales of various fields have experienced an amazing growth. Networks in the fields of biology, economics and society contain rich hidden information of human beings in the form of connectivity structures. Network analysis is generally modeled as network partition and community detection problems. In this paper, we construct a community property-based triangle motif clustering scheme (COMICS) containing a series of high efficient graph partition procedures and triangle motif-based clustering techniques. In COMICS, four network cutting conditions are considered based on the network connectivity. We first divide the large-scale networks into many dense subgraphs under the cutting conditions before leveraging triangle motifs to refine and specify the partition results. To demonstrate the superiority of our method, we implement the experiments on three large-scale networks, including two co-authorship networks (the American Physical Society (APS) and the Microsoft Academic Graph (MAG)), and two social networks (Facebook and gemsec-Deezer networks). We then use two clustering metrics, compactness and separation, to illustrate the accuracy and runtime of clustering results. A case study is further carried out on APS and MAG data sets, in which we construct a connection between network structures and statistical data with triangle motifs. Results show that our method outperforms others in both runtime and accuracy, and the triangle motif structures can bridge network structures and statistical data in the academic collaboration area

The target selection and quantitative evaluation for deep geothermal resource zoning of typical geothermal fields in central Hebei of North China plain

With the rapid economic development in North China, the demand for geothermal energy is increasing. It is urgent to find favorable deep geothermal resource targets in North China. Although geothermal resources in the North China Plain are widely distributed, in order to develop deep geothermal resources in North China safely, stably and efficiently, it is essential to carry out the target selection and evaluation of geothermal resource zoning. This article takes the typical geothermal fields in the central Hebei region as the research object, and through the comprehensive collation of regional geothermal geological data, constructs an optimization evaluation indicator system for geothermal resource target areas from three aspects: resource conditions, mining potential, and heating demand. On this basis, it establishes a linear relationship between the attribute values and scores of each indicator, and uses the analytic hierarchy process to assign weights to each indicator and calculate the comprehensive weight. Then, the comprehensive evaluation value is obtained by weighted calculation of the scores and comprehensive weights of each block in the grid segmentation of the evaluation area. Finally, through the spatial analysis function of GIS, the comprehensive evaluation values of all blocks in the evaluation area were analyzed using kriging difference analysis, and a comprehensive evaluation map, the geothermal resource prospective target area map, was finally obtained. Using quantitative zoning evaluation methods, the target areas for exploration and development of deep geothermal resources in central Hebei Province have been delineated within a large region. The evaluation results indicate that the Cambrian-Ordovician reservoir target area is relatively large, and there are many favorable target areas with good reservoir conditions in the Middle-Upper Proterozoic. The excellent prospective target area of the Mesoproterozoic geothermal reservoir accounts for 56%, mainly located in the Xingji uplift and Gaoyang low uplift. Xiong’an New Area, Cangzhou, and the eastern part of Hengshui are excellent prospective target areas for the evaluation of the Mesoproterozoic geothermal reservoir in a single area. This evaluation method can provide a reference for the optimization of resource exploration and development target areas in key regions

On the Origin of Ultraviolet Emission and the Accretion Model of Low-luminosity AGNs

Low-luminosity active galactic nuclei (LLAGNs) are generally believed to be powered by an inner radiatively inefficient, advection-dominated accretion flow (ADAF), an outer truncated thin disk, and a jet. Maoz (2007) recently challenged this picture based on the observation that the strength of ultraviolet emission relative to the X-ray and radio bands does not depart from empirical trends defined by more luminous sources. He advocates that AGNs across all luminosities have essentially the same accretion and radiative processes, which in luminous sources are described by a standard optically thick, geometrically thin disk. We calculate ADAF models and demonstrate that they can successfully fit the observed spectral energy distributions of the LLAGNs in Maoz's sample. Our model naturally accommodates the radio and X-ray emission, and the ultraviolet flux is well explained by a combination of the first-order Compton scattering in the ADAF, synchrotron emission in the jet, and black body emission in the truncated thin disk. It is premature to dismiss the ADAF model for LLAGNs. The UV data can be fit equally well using a standard thin disk, but an additional corona and jet would be required to account for the X-ray and radio emission. We argue that there are strong theoretical reasons to prefer the ADAF model over the thin disk scenario. We discuss testable predictions that can potentially discriminate between the two accretion models.Comment: 20 pages, 3 figures; ApJ in pres

Revisiting the "Fundamental Plane" of Black Hole Activity at Extremely Low Luminosities

We investigate the origin of the X-ray emission in low-luminosity AGNs (LLAGNs). Yuan & Cui (2005) predicted that the X-ray emission should originate from jets rather than from an advection-dominated accretion flow (ADAF) when the X-ray luminosity $L_{\rm X}$ of the source is below a critical value of $L_{\rm X,crit} \approx 10^{-6}L_{\rm Edd}$. This prediction implies that the X-ray spectrum in such sources should be fitted by jets rather than ADAFs. Furthermore, below $L_{\rm X,crit}$ the correlation between radio ($L_{\rm R}$) and X-ray ($L_{\rm X}$) luminosities and the black hole mass ($M$)--the so-called fundamental plane of black hole activity--should deviate from the general correlation obtained by Merloni, Heinz & Di Matteo (2003) and become steeper. The Merloni et al. correlation is described by ${\rm log}L_{\rm R} =0.6{\rm log}L_{\rm X}+0.78{\rm log}M+7.33$, while the predicted correlation is ${\rm log}L_{\rm R}=1.23{\rm log}L_{\rm X} +0.25{\rm log}M-13.45$. We collect data from the literature to check the validity of these two expectations. We find that among the 16 LLAGNs with good X-ray and radio spectra, 13 are consistent with the Yuan & Cui prediction. For the 22 LLAGNs with $L_{\rm X} < L_{\rm X,crit}$, the fundamental plane correlation is described by ${\rm log}L_{\rm R}=1.22{\rm log}L_{\rm X}+0.23{\rm log}M-12.46$, also in excellent agreement with the prediction.Comment: 24 pages, 2 tables, 3 figures; accepted by Ap

Histomorphological study of the spinal growth plates from the convex side and the concave side in adolescent idiopathic scoliosis

Asymmetrical growth of the vertebrae has been implicated as one possible etiologic factor in the pathogenesis of adolescent idiopathic scoliosis. The longitudinal vertebral growth derives from the endochondral ossification of the vertebral growth plate. In the present study, the growth plates from the convex and concave side of the vertebrae were characterized by the method of histology and immunohistochemistry to evaluate the growth activity, cell proliferation, and apoptosis. Normal zoned architectures were observed in the convex side of the growth plate and disorganized architectures in the concave side. The histological grades were significantly different between the convex and the concave side of the growth plate in the apex vertebrae (P < 0.05). The histological difference was also found significant statistically between end vertebrae and apex vertebrae in the concave side of vertebral growth plates (P < 0.05). The proliferative potential indexes and apoptosis indexes of chondrocytes in the proliferative and hypertrophic zone in the convex side were significantly higher than that in the concave side in the apex vertebral growth plate (P < 0.05). There was a significant difference of the proliferative potential index (proliferating cell nuclear antigen, PCNA index) between convex side and concave side at the upper end vertebra (P < 0.05). The difference of the proliferative potential index and apoptosis index were found significant statistically in the concave side of the vertebral growth plate between end vertebrae and apex vertebrae (P < 0.05). The same result was also found for the apoptosis index (terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate biotin nick end labeling assay, TUNEL index) in the convex side of vertebral growth plate between end vertebrae and apex vertebrae (P < 0.05). Some correlation were found between radiographic measurements and proliferation and apoptosis indexes. The difference in histological grades and cellular activity between the convex and concave side indicated that the bilateral growth plate of the vertebrae in AIS patients have different growth kinetics which may affect the curve progression