scholarly journals History-dependent percolation on multiplex networks

2020 ◽  
Vol 7 (8) ◽  
pp. 1296-1305 ◽  
Author(s):  
Ming Li ◽  
Linyuan Lü ◽  
Youjin Deng ◽  
Mao-Bin Hu ◽  
Hao Wang ◽  
...  
Keyword(s):  
Abrupt Change ◽  
Morphological Similarity ◽  
Unified Framework ◽  
Percolation Process ◽  
Practical Applications ◽  
Functional Correlation ◽  
Previous State ◽  
Dependent Percolation ◽  
Interacting Networks ◽  
General Method

Abstract The structure of interconnected systems and its impact on the system dynamics is a much-studied cross-disciplinary topic. Although various critical phenomena have been found in different models, study of the connections between different percolation transitions is still lacking. Here we propose a unified framework to study the origins of the discontinuous transitions of the percolation process on interacting networks. The model evolves in generations with the result of the present percolation depending on the previous state, and thus is history-dependent. Both theoretical analysis and Monte Carlo simulations reveal that the nature of the transition remains the same at finite generations but exhibits an abrupt change for the infinite generation. We use brain functional correlation and morphological similarity data to show that our model also provides a general method to explore the network structure and can contribute to many practical applications, such as detecting the abnormal structures of human brain networks.

A unified framework for automated person re-indentification

2020 ◽  
Vol 71 (7) ◽  
pp. 868-880
Author(s):  
Nguyen Hong-Quan ◽  
Nguyen Thuy-Binh ◽  
Tran Duc-Long ◽  
Le Thi-Lan
Keyword(s):  
Deep Learning ◽  
Video Analysis ◽  
Camera Network ◽  
Unified Framework ◽  
Person Detection ◽  
Practical Applications ◽  
Detection And Tracking ◽  
Analysis System ◽  
Bounding Boxes

Along with the strong development of camera networks, a video analysis system has been become more and more popular and has been applied in various practical applications. In this paper, we focus on person re-identification (person ReID) task that is a crucial step of video analysis systems. The purpose of person ReID is to associate multiple images of a given person when moving in a non-overlapping camera network. Many efforts have been made to person ReID. However, most of studies on person ReID only deal with well-alignment bounding boxes which are detected manually and considered as the perfect inputs for person ReID. In fact, when building a fully automated person ReID system the quality of the two previous steps that are person detection and tracking may have a strong effect on the person ReID performance. The contribution of this paper are two-folds. First, a unified framework for person ReID based on deep learning models is proposed. In this framework, the coupling of a deep neural network for person detection and a deep-learning-based tracking method is used. Besides, features extracted from an improved ResNet architecture are proposed for person representation to achieve a higher ReID accuracy. Second, our self-built dataset is introduced and employed for evaluation of all three steps in the fully automated person ReID framework.

Percolation phase transition of static and growing networks under a weighted function

2016 ◽  
Vol 27 (07) ◽  
pp. 1650082 ◽  
Author(s):  
Xiao Jia ◽  
Jin-Song Hong ◽  
Ya-Chun Gao ◽  
Hong-Chun Yang ◽  
Chun Yang ◽  
...  
Keyword(s):  
Phase Transition ◽  
Continuous Phase ◽  
Weighted Function ◽  
Percolation Process ◽  
Practical Applications ◽  
Network Intervention ◽  
Growing Networks ◽  
Discontinuous Phase ◽  
And Control ◽  
Growing Network

We investigate the percolation phase transitions in both the static and growing networks where the nodes are sampled according to a weighted function with a tunable parameter [Formula: see text]. For the static network, i.e. the number of nodes is constant during the percolation process, the percolation phase transition can evolve from continuous to discontinuous as the value of [Formula: see text] is tuned. Based on the properties of the weighted function, three typical values of [Formula: see text] are analyzed. The model becomes the classical Erdös–Rényi (ER) network model at [Formula: see text]. When [Formula: see text], it is shown that the percolation process generates a weakly discontinuous phase transition where the order parameter exhibits an extremely abrupt transition with a significant jump in large but finite system. For [Formula: see text], the cluster size distribution at the lower pseudo-transition point does not obey the power-law behavior, indicating a strongly discontinuous phase transition. In the case of growing network, in which the collection of nodes is increasing, a smoother continuous phase transition emerges at [Formula: see text], in contrast to the weakly discontinuous phase transition of the static network. At [Formula: see text], on the other hand, probability modulation effect shows that the nature of strongly discontinuous phase transition remains the same with the static network despite the node arrival even in the thermodynamic limit. These percolation properties of the growing networks could provide useful reference for network intervention and control in practical applications in consideration of the increasing size of most actual networks.

scholarly journals On the Condition Number Theory of the Equality Constrained Indefinite Least Squares Problem

2018 ◽  
Vol 34 ◽  
pp. 619-638
Author(s):  
Shaoxin Wang ◽  
Hanyu Li ◽  
Hu Yang
Keyword(s):  
Number Theory ◽  
Least Squares ◽  
Condition Number ◽  
Condition Numbers ◽  
Least Squares Problems ◽  
Unified Framework ◽  
Least Squares Problem ◽  
Practical Applications ◽  
New Findings ◽  
Special Cases

In this paper, within a unified framework of the condition number theory, the explicit expression of the \emph{projected} condition number of the equality constrained indefinite least squares problem is presented. By setting specific norms and parameters, some widely used condition numbers, like the normwise, mixed and componentwise condition numbers follow as its special cases. Considering practical applications and computation, some new compact forms or upper bounds of the projected condition numbers are given to improve the computational efficiency. The new compact forms are of particular interest in calculating the exact value of the 2-norm projected condition numbers. When the equality constrained indefinite least squares problem degenerates into some specific least squares problems, our results give some new findings on the condition number theory of these specific least squares problems. Numerical experiments are given to illustrate our theoretical results.

scholarly journals Broadband Achromatic Metasurfaces for Longwave Infrared Applications

Nanomaterials ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2760
Author(s):  
Naitao Song ◽  
Nianxi Xu ◽  
Dongzhi Shan ◽  
Yuanhang Zhao ◽  
Jinsong Gao ◽  
...  
Keyword(s):  
Thermal Imaging ◽  
Chromatic Dispersion ◽  
Numerical Aperture ◽  
Chromatic Aberration ◽  
Average Intensity ◽  
Geometric Phases ◽  
Practical Applications ◽  
Chromatic Aberrations ◽  
Fabrication Costs ◽  
General Method

Longwave infrared (LWIR) optics are essential for several technologies, such as thermal imaging and wireless communication, but their development is hindered by their bulk and high fabrication costs. Metasurfaces have recently emerged as powerful platforms for LWIR integrated optics; however, conventional metasurfaces are highly chromatic, which adversely affects their performance in broadband applications. In this work, the chromatic dispersion properties of metasurfaces are analyzed via ray tracing, and a general method for correcting chromatic aberrations of metasurfaces is presented. By combining the dynamic and geometric phases, the desired group delay and phase profiles are imparted to the metasurfaces simultaneously, resulting in good achromatic performance. Two broadband achromatic metasurfaces based on all-germanium platforms are demonstrated in the LWIR : a broadband achromatic metalens with a numerical aperture of 0.32, an average intensity efficiency of 31%, and a Strehl ratio above 0.8 from 9.6 μm to 11.6 μm, and a broadband achromatic metasurface grating with a constant deflection angle of 30° from 9.6 μm to 11.6 μm. Compared with state-of-the-art chromatic-aberration-restricted LWIR metasurfaces, this work represents a substantial advance and brings the field a step closer to practical applications.

Practical Applications of Scale Independent Elements

1995 ◽  
Author(s):  
Mohammed M. Ettouney ◽  
Raymond P. Daddazio ◽  
Najib N. Abboud
Keyword(s):  
Finite Element ◽  
Energy Methods ◽  
Great Flexibility ◽  
New Approach ◽  
Practical Applications ◽  
Deterministic Methods ◽  
Computer Resources ◽  
Single Coordinate ◽  
General Method ◽  
Vibrating Systems

Abstract Discrete deterministic methods such as finite elements offer great flexibility in analyzing the dynamic response of vibrating systems. However, these methods can easily grow beyond available computer resources as frequencies of interest grow higher. In this paper we present a new approach for the frequency domain dynamic analysis of structures. A theory is developed for the analysis of systems which are uniform along a single coordinate axis but otherwise arbitrary in geometry and material composition. This approach, termed the Scale Independent Element, is shown to be an accurate, efficient and general method for the analysis of vibrating systems. This technique extends the applicability of discrete deterministic finite element based modeling to higher frequencies and is capable of bridging the gap to frequency regimes where statistical energy methods become applicable.

scholarly journals Spatial-Temporal Person Re-Identification

2019 ◽  
Vol 33 ◽  
pp. 8933-8940 ◽  
Author(s):  
Guangcong Wang ◽  
Jianhuang Lai ◽  
Peigen Huang ◽  
Xiaohua Xie
Keyword(s):  
Probability Distribution ◽  
Semantic Information ◽  
Temporal Information ◽  
Unified Framework ◽  
Temporal Constraint ◽  
Query Image ◽  
Similarity Metric ◽  
Heterogeneous Information ◽  
Large Margin ◽  
Previous State

Most of current person re-identification (ReID) methods neglect a spatial-temporal constraint. Given a query image, conventional methods compute the feature distances between the query image and all the gallery images and return a similarity ranked table. When the gallery database is very large in practice, these approaches fail to obtain a good performance due to appearance ambiguity across different camera views. In this paper, we propose a novel two-stream spatial-temporal person ReID (st-ReID) framework that mines both visual semantic information and spatial-temporal information. To this end, a joint similarity metric with Logistic Smoothing (LS) is introduced to integrate two kinds of heterogeneous information into a unified framework. To approximate a complex spatial-temporal probability distribution, we develop a fast Histogram-Parzen (HP) method. With the help of the spatial-temporal constraint, the st-ReID model eliminates lots of irrelevant images and thus narrows the gallery database. Without bells and whistles, our st-ReID method achieves rank-1 accuracy of 98.1% on Market-1501 and 94.4% on DukeMTMC-reID, improving from the baselines 91.2% and 83.8%, respectively, outperforming all previous state-of-theart methods by a large margin.

scholarly journals A unified framework for automated person re-identification

2020 ◽  
Vol 71 (7) ◽  
pp. 868-880
Author(s):  
Nguyen Hong Quan ◽  
Nguyen Thuy Binh ◽  
Tran Duc Long ◽  
Le Thi Lan
Keyword(s):  
Deep Learning ◽  
Video Analysis ◽  
Camera Network ◽  
Unified Framework ◽  
Person Detection ◽  
Practical Applications ◽  
Detection And Tracking ◽  
Analysis System ◽  
Bounding Boxes

Along with the strong development of camera networks, a video analysis system has been become more and more popular and has been applied in various practical applications. In this paper, we focus on person re-identification (person ReID) task that is a crucial step of video analysis systems. The purpose of person ReID is to associate multiple images of a given person when moving in a non-overlapping camera network. Many efforts have been made to person ReID. However, most of studies on person ReID only deal with well-alignment bounding boxes which are detected manually and considered as the perfect inputs for person ReID. In fact, when building a fully automated person ReID system the quality of the two previous steps that are person detection and tracking may have a strong effect on the person ReID performance. The contribution of this paper are two-folds. First, a unified framework for person ReID based on deep learning models is proposed. In this framework, the coupling of a deep neural network for person detection and a deep-learning-based tracking method is used. Besides, features extracted from an improved ResNet architecture are proposed for person representation to achieve a higher ReID accuracy. Second, our self-built dataset is introduced and employed for evaluation of all three steps in the fully automated person ReID framework.

scholarly journals Factors and Economic Evaluation of Transnational Investment Risks

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Guanghui Xiong ◽  
Lei Wang
Keyword(s):  
Risk Factors ◽  
Economic Evaluation ◽  
Evaluation System ◽  
Large Scale ◽  
Evaluation Method ◽  
Investment Risk ◽  
Unified Framework ◽  
Practical Applications ◽  
Investment Projects ◽  
Evaluation Models

Transnational investment is featured by its large scale and high risks. During transnational investment, the frequent risks often bring a huge loss to the investors. Therefore, the risk factors should be included in the economic evaluation of transnational investment projects. However, the existing evaluation models and systems are rather complex, lacking a unified framework. Besides, there are few practical applications of these models or systems. To solve the problem, this paper explores the factors and economic evaluation of transnational investment risks. Firstly, an economic evaluation system was constructed for transnational investment projects, and the economic evaluation result was depicted in two aspects: economic income factors and investment risk factors. Then, the applicability and economic meanings of common indices were clarified one after another. After that, the economic evaluation flow was designed for risk-based transnational investment projects. Finally, an economic evaluation was performed on actual projects, which verifies the feasibility of the proposed evaluation method.

scholarly journals Design of metacontinua in the aeroacoustic spacetime

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Umberto Iemma ◽  
Giorgio Palma
Keyword(s):  
Mechanical Properties ◽  
Mach Number ◽  
Coordinate Transformations ◽  
Acoustic Metamaterials ◽  
Background Flow ◽  
Original Design ◽  
Full Disclosure ◽  
Practical Applications ◽  
Acoustic Disturbances ◽  
General Method

Abstract The effect of background flows on the response of acoustic metamaterials is a key aspect that prevented the full disclosure of their potential in those applications where an aerodynamic velocity field strongly influences the propagation of acoustic disturbances. Indeed, the classic approaches for metamaterial design do not consider the aeroacoustic interaction, and the resulting metamaterials cannot preserve their response when operating in flows. So far, only few authors have addressed the problem, mostly focusing on understanding the phenomenon or identifying corrective techniques with limited usability in practical applications. The present study proposes a general method for the modification of the mechanical properties of acoustic metacontinua to preserve their response in presence of a background flow. The method is based on the application of spacetime coordinate transformations exploiting the spacetime formal invariance of the generalised d’Alembertian. This methodology applies to the equation governing the propagation of acoustic disturbances in a metamaterial having arbitrary constitutive equations independently on the method used for its original design. The approach is validated through numerical simulations, using as a benchmark the problem of the acoustic cloaking of a cylinder impinged by a perturbation generated by an isotropic point source within a flowing medium. Numerical results are obtained for an asymptotic Mach number $$M_\infty \le 0.35$$ M ∞ ≤ 0.35 .

scholarly journals Asymptotic Performances of a Signal-To-Noise Ratio Moment-Based Estimator for Real Sinusoids in Additive Noise

2019 ◽  
Vol 9 (24) ◽  
pp. 5556 ◽  
Author(s):  
Gianmarco Romano
Keyword(s):  
Additive Noise ◽  
Signal To Noise Ratio ◽  
Noise Power ◽  
Signal To Noise ◽  
Practical Applications ◽  
Unknown Variance ◽  
Noise Ratio ◽  
Asymptotic Variances ◽  
Frequency Phase ◽  
General Method

We considered the problem of the estimation of signal-to-noise ratio (SNR) with a real deterministic sinusoid with unknown frequency, phase and amplitude in additive Gaussian noise of unknown variance. A blind SNR estimator that does not require the knowledge of the instantaneous frequency of the sinusoid, through separate estimation of signal and noise power, was derived using the method of moments, a general method to derive estimators based on high-order moments. Statistical performances of the proposed estimators were studied theoretically through derivation of Cramer–Rao lower bounds (CRLBs) and asymptotic variances. Furthermore, results from Monte-Carlo simulations that confirm the validity of the theoretical analysis are presented along with some comments on the use of proposed estimators in practical applications.

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