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  • Open Access


    Skew t Distribution-Based Nonlinear Filter with Asymmetric Measurement Noise Using Variational Bayesian Inference

    Chen Xu1, Yawen Mao2, Hongtian Chen3,*, Hongfeng Tao1, Fei Liu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.131, No.1, pp. 349-364, 2022, DOI:10.32604/cmes.2021.019027

    Abstract This paper is focused on the state estimation problem for nonlinear systems with unknown statistics of measurement noise. Based on the cubature Kalman filter, we propose a new nonlinear filtering algorithm that employs a skew t distribution to characterize the asymmetry of the measurement noise. The system states and the statistics of skew t noise distribution, including the shape matrix, the scale matrix, and the degree of freedom (DOF) are estimated jointly by employing variational Bayesian (VB) inference. The proposed method is validated in a target tracking example. Results of the simulation indicate that the proposed nonlinear filter can perform… More >

  • Open Access


    Secure and Robust Optical Multi-Stage Medical Image Cryptosystem

    Walid El-Shafai1, Moustafa H. Aly2, Abeer D. Algarni3,*, Fathi E. Abd El-Samie1,3, Naglaa F. Soliman3,4

    CMC-Computers, Materials & Continua, Vol.70, No.1, pp. 895-913, 2022, DOI:10.32604/cmc.2022.018545

    Abstract Due to the rapid growth of telemedicine and healthcare services, color medical image security applications have been expanded precipitously. In this paper, an asymmetric PTFrFT (Phase Truncated Fractional Fourier Transform)-based color medical image cryptosystem is suggested. Two different phases in the fractional Fourier and output planes are provided as deciphering keys. Accordingly, the ciphering keys will not be employed for the deciphering procedure. Thus, the introduced PTFrFT algorithm comprises asymmetric ciphering and deciphering processes in contrast to the traditional optical symmetric OSH (Optical Scanning Holography) and DRPE (Double Random Phase Encoding) algorithms. One of the principal impacts of the introduced… More >

  • Open Access


    A Resource-constrained Edge IoT Device Data-deduplication Method with Dynamic Asymmetric Maximum

    Ye Yang1, Xiaofang Li2, Dongjie Zhu3,*, Hao Hu3, Haiwen Du4, Yundong Sun4, Weiguo Tian3, Yansong Wang3, Ning Cao1, Gregory M.P. O’Hare5

    Intelligent Automation & Soft Computing, Vol.30, No.2, pp. 481-494, 2021, DOI:10.32604/iasc.2021.019201

    Abstract Smart vehicles use sophisticated sensors to capture real-time data. Due to the weak communication capabilities of wireless sensors, these data need to upload to the cloud for processing. Sensor clouds can resolve these drawbacks. However, there is a large amount of redundant data in the sensor cloud, occupying a large amount of storage space and network bandwidth. Deduplication can yield cost savings by storing one data copy. Chunking is essential because it can determine the performance of deduplication. Content-Defined Chunking (CDC) can effectively solve the problem of chunk boundaries shifted, but it occupies a lot of computing resources and has… More >

  • Open Access


    Numerical Simulation and Experimental Analysis of the Influence of Asymmetric Pressure Conditions on the Splitting of a Gas-Liquid Two-Phase Flow at a T-Junction

    Lihui Ma1, Limin He1,2,*, Xiaoming Luo1,2, Xiangran Mi3

    FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.5, pp. 959-970, 2021, DOI:10.32604/fdmp.2021.016710

    Abstract Dedicated experiments and numerical simulations have been conducted to investigate the splitting characteristics of a gas-liquid two phase flow at a T junction. The experiments were carried out for different gas-liquid velocities. The flow rates in the two branches were measured accurately to determine how the two considered phases distribute in the two outlets. The experimental results have shown that when the two outlet pressures are asymmetric, the two-phase flow always tends to flow into the outlet which has a lower pressure. As the inlet liquid velocity increases, however, the two-phase flow gradually tends to split evenly. Compared with the… More >

  • Open Access


    Topp-Leone Odd Fréchet Generated Family of Distributions with Applications to COVID-19 Data Sets

    Sanaa Al-Marzouki1, Farrukh Jamal2, Christophe Chesneau3,*, Mohammed Elgarhy4

    CMES-Computer Modeling in Engineering & Sciences, Vol.125, No.1, pp. 437-458, 2020, DOI:10.32604/cmes.2020.011521

    Abstract Recent studies have pointed out the potential of the odd Fréchet family (or class) of continuous distributions in fitting data of all kinds. In this article, we propose an extension of this family through the so-called “Topp-Leone strategy”, aiming to improve its overall flexibility by adding a shape parameter. The main objective is to offer original distributions with modifiable properties, from which adaptive and pliant statistical models can be derived. For the new family, these aspects are illustrated by the means of comprehensive mathematical and numerical results. In particular, we emphasize a special distribution with three parameters based on the… More >

  • Open Access


    Image Denoising Based on the Asymmetric Gaussian Mixture Model

    Ke Jin, Shunfeng Wang*

    Journal on Internet of Things, Vol.2, No.1, pp. 1-11, 2020, DOI:10.32604/jiot.2020.09071

    Abstract In recent years, image restoration has become a huge subject, and finite hybrid model has been widely used in image denoising because of its easy modeling and strong explanatory results. The gaussian mixture model is the most common one. The existing image denoising methods usually assume that each component of the natural image is subject to the gaussian mixture model (GMM). However, this approach is not entirely reasonable. It is well known that most natural images are complex and their distribution is not entirely gaussian. As a result, there are still many problems that GMM cannot solve. This paper tries… More >

  • Open Access


    Influence of an Atmospheric Pressure Plasma Surface Treatment on the Interfacial Fracture Toughness on Bonded Composite Joints

    J. Mohan1, D. Carolan1, N. Murphy1, A. Ivankovic1, D. Dowling1

    Structural Durability & Health Monitoring, Vol.3, No.2, pp. 81-86, 2007, DOI:10.3970/sdhm.2007.003.081

    Abstract The aim of this work is to investigate the influence of a variety of plasma treatments on the surface properties of an epoxy-based composite material and to establish a relationship between these properties and the subsequent mechanical behaviour of adhesively bonded joints. To this end, specimens were subjected to three different types of plasma treatment: two short treatments (2min) of He and He plus O2, and one long treatment (15min) of He plus O2. The variation in surface energy of the composite specimens was examined in each case over a period of up to 3 days using contact angle measurements.… More >

  • Open Access


    Finite Element Investigation of Flow Field Below Asymmetric Drill Bits for Reverse Circulation in Drilling Tight Oil and Gas Reservoirs

    Yi Luo1,*, Erxiu Shi2, Yin Feng2, Boyun Guo2, Liehui Zhang1

    CMES-Computer Modeling in Engineering & Sciences, Vol.121, No.1, pp. 105-122, 2019, DOI:10.32604/cmes.2019.06500

    Abstract Development of unconventional tight oil and gas reservoirs such as shale pays presents a huge challenge to the petroleum industry due to the naturally low permeability of shale formations and thus low productivity of oil and gas wells. Shale formations are also vulnerable to the contamination of the water in the drilling and completion fluids, which further reduces reservoir permeability. Although gas-drilling (drilling with gas) has been used to address the issue, several problems such as formation water influx, wellbore collapse, excessive gas volume requirement and hole cleaning in horizontal drilling, still hinder its application. A new technique called gas-lift… More >

  • Open Access


    Dynamic analysis of asymmetrically laminated composite frames

    Fuxing Miao1, Guojun Sun1

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.12, No.3, pp. 93-94, 2009, DOI:10.3970/icces.2009.012.093

    Abstract Based on elastic wave theory, Pao[1] and his colleagues recently proposed a novel frequency domain matrix method, i.e. the Method of Reverberation-Ray Matrix (MRRM) for solving the transient response of truss-type structures. The theory has been shown accurately coincided with experimental data of a model truss for the early responses.
    Fiber reinforced laminated composites have advantages such as high specific strength, high specific stiffness, corrosion resistance etc.. The dynamic as well as the static behavior of laminated composites is largely dependent upon fiber orientation and ply-stacking sequence. Due to inhomogeneity and anisotropy of the material, these structures are vulnerableto highly… More >

  • Open Access


    Numerical Simulations of Unstable Flow through a Spherical Bulge in a 90-degree Asymmetrical Bend

    J.M.M. Sousa1

    CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.2, pp. 211-220, 2005, DOI:10.3970/cmes.2005.009.211

    Abstract Time-dependent numerical simulations of the flow through a spherical bulge in a 90-degree asymmetrical bend have been performed for Reynolds numbers in the range 100-400. The present results have demonstrated that the flow reaches asymptotically steady, symmetrical solutions for Reynolds numbers up to 300, whereas a value of 400 for this parameter leads to unsteadiness. The computed flow behavior at this higher Reynolds number has shown to be characterized by an intermittent transition between small-amplitude, irregular oscillations and large-amplitude bursts occurring at a low frequency. In addition, the unsteady flow was asymmetrical and exhibited swirl switching. More >

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