N. Jayashree^1,*, R. S. Bhuvaneswaran¹

CMC-Computers, Materials & Continua, Vol.58, No.1, pp. 263-285, 2019, DOI:10.32604/cmc.2019.03924

Abstract Watermarking is a widely used solution to the problems of authentication and copyright protection of digital media especially for images, videos, and audio data. Chaos is one of the emerging techniques adopted in image watermarking schemes due to its intrinsic cryptographic properties. This paper proposes a new chaotic hybrid watermarking method combining Discrete Wavelet Transform (DWT), Z-transform (ZT) and Bidiagonal Singular Value Decomposition (BSVD). The original image is decomposed into 3-level DWT, and then, ZT is applied on the HH3 and HL3 sub-bands. The watermark image is encrypted using Arnold Cat Map. BSVD for the watermark and transformed original image… More >

Ma Ning^1,*, Jianhe Guan¹, Pingzeng Liu², Ziqing Zhang³, Gregory M. P. O’Hare⁴

CMC-Computers, Materials & Continua, Vol.58, No.1, pp. 215-227, 2019, DOI:10.32604/cmc.2019.03763

Abstract With the rapid development of China’s economy, the scale of the city has been continuously expanding, industrial enterprises have been increasing, the discharge of multiple pollutants has reached the top of the world, and the environmental problems become more and more serious. The air pollution problem is particularly prominent. Air quality has become a daily concern for people. In order to control air pollution, it is necessary to grasp the air quality situation in an all-round way. It is necessary to evaluate air quality. Accurate results of air quality evaluation can help people know more about air quality. In this… More >

Ying Li¹, Jianbo Li^1,*, Jianwei Chen¹, Minchao Lu¹, Caoyuan Li^2,3

CMC-Computers, Materials & Continua, Vol.57, No.3, pp. 571-587, 2018, DOI:10.32604/cmc.2018.02851

Abstract The explosive growth of mobile data demand is becoming an increasing burden on current cellular network. To address this issue, we propose a solution of opportunistic data offloading for alleviating overloaded cellular traffic. The principle behind it is to select a few important users as seeds for data sharing. The three critical steps are detailed as follows. We first explore individual interests of users by the construction of user profiles, on which an interest graph is built by Gaussian graphical modeling. We then apply the extreme value theory to threshold the encounter duration of user pairs. So, a contact graph… More >

Xiaorui Zhang^1,3,*, Jiali Duan¹, Lifeng Zhu², Ladislav Kavan³

CMC-Computers, Materials & Continua, Vol.57, No.3, pp. 505-519, 2018, DOI:10.32604/cmc.2018.01842

Abstract Puncture is a common operation in surgery, which involves all kinds of tissue materials with different geometry and mechanical properties. As a new cross-disciplinary research area, Virtual Surgery (VS) makes simulation of soft tissue in puncture operation possible in virtual environment. In this paper, we introduce a VS-based puncture system composed by three-layer soft tissue, simulated with spherical harmonic function (SHF), which is covered with a force mesh, constructed by mass spring model (MSM). The two models are combined together with a parameter of SHF named surface radius, which provides MSM with real-time deformation data needed in force calculation. Meanwhile,… More >

Tiejun Wang¹, Tao Wu^1,*, Amir Homayoon Ashrafzadeh², Jia He¹

CMC-Computers, Materials & Continua, Vol.57, No.1, pp. 81-96, 2018, DOI:10.32604/cmc.2018.03259

Abstract Crowdsourcing is widely used in various fields to collect goods and services from large participants. Evaluating teaching quality by collecting feedback from experts or students after class is not only delayed but also not accurate. In this paper, we present a crowdsourcing-based framework to evaluate teaching quality in the classroom using a weighted average operator to aggregate information from students’ questionnaires described by linguistic 2-tuple terms. Then we define crowd grade based on similarity degree to distinguish contribution from different students and minimize the abnormal students’ impact on the evaluation. The crowd grade would be updated at the end of… More >

Yi Cao^1,2, Zhili Zhou^1,2,3, Xingming Sun^1,2, Chongzhi Gao^4,*

CMC-Computers, Materials & Continua, Vol.54, No.2, pp. 197-207, 2018, DOI:10.3970/cmc.2018.054.197

Abstract The traditional information hiding methods embed the secret information by modifying the carrier, which will inevitably leave traces of modification on the carrier. In this way, it is hard to resist the detection of steganalysis algorithm. To address this problem, the concept of coverless information hiding was proposed. Coverless information hiding can effectively resist steganalysis algorithm, since it uses unmodified natural stego-carriers to represent and convey confidential information. However, the state-of-the-arts method has a low hidden capacity, which makes it less appealing. Because the pixel values of different regions of the molecular structure images of material (MSIM) are usually different,… More >

Zhengong Zhou¹, Shuang Tian^1,2, Jiawei Zhang³

CMC-Computers, Materials & Continua, Vol.52, No.2, pp. 105-121, 2016, DOI:10.3970/cmc.2016.052.105

Abstract The methods of numerical simulation and test are combined to analyze the impact behavior of glass fiber reinforced aluminum alloy laminate (GLARE). A new failure criteria is proposed to obtain the impact failure of GLARE, and combined with material progressive damage method by writing code of LS-DYNA. Low velocity impact test of GLARE is employed to validate the feasibility of the finite element model established. The simulation results have been shown that progressive damage finite element model established is reliable. Through the application of the finite element model established, the delamination of GLARE evolution progress is simulated, various failure modes… More >

Smitha Gopinath^1,2, S. Meenu³, A. Ramach,ra Murthy¹

CMC-Computers, Materials & Continua, Vol.51, No.2, pp. 81-103, 2016, DOI:10.3970/cmc.2016.051.081

Abstract This paper presents experimental and analytical investigations on concrete beams reinforced with basalt fiber reinforced polymer (BFRP) and steel fibers without stirrups. Independent behaviour of BFRP reinforced beams and steel fiber reinforced beams were evaluated and the effect of combining BFRP bars and steel fiber was investigated in detail. It is found that combining steel fibers with BFRP could change the shear failure of BFRP reinforced beam to flexural failure. Further, the existing analytical models were reviewed and compared to predict the shear strength of both FRP reinforced and steel fiber reinforced beams. Based on the review, the appropriate model… More >

Bui Duc Thuan^1,2, Wong Yonghui², Chua Kian Jon², Ng Kim Choon²

CMC-Computers, Materials & Continua, Vol.47, No.2, pp. 89-105, 2015, DOI:10.3970/cmc.2015.047.089

Abstract The cup method and dynamic moisture permeation cell (DMPC) method are two common techniques used to determine the water vapor permeation properties of a membrane. Often, ignoring the resistance of boundary air layers to the transport of water vapor results in the water vapor permeance of the membrane being underestimated in practical tests. The measurement errors are higher with highly permeable membranes. In this study, the two methods were simulated using COMSOL Multiphysics platform and the extent of the error was evaluated. Initial results showed that the error is equally high in both methods. With the correction for the still… More >

Sanjeev Saxena¹, Raghvendra Singh², Geeta Agnihotri²

CMC-Computers, Materials & Continua, Vol.36, No.3, pp. 257-270, 2013, DOI:10.3970/cmc.2013.036.257

Abstract The present numerical study is an attempt to understand the dependency of characteristic distance on the fracture specimen thickness and temperature. The presented work will be useful to establish the characteristic distance prediction methodology using three dimensional FEM model. Based on the methods proposed for the numerical prediction of characteristic distance, it comes out that it depends on fracture specimen thickness and finally it converges after a specified thickness of fracture specimen. In Armco iron material, characteristic distance varies in temperature ranges where dynamic strain ageing phenomenon is observed, initially decrease and then increases again. More >