Wentao Ma¹, Jiaohua Qin^1,*, Xuyu Xiang¹, Yun Tan¹, Yuanjing Luo¹, Neal N. Xiong²

CMC-Computers, Materials & Continua, Vol.58, No.3, pp. 665-677, 2019, DOI:10.32604/cmc.2019.05683

Abstract As the first barrier to protect cyberspace, the CAPTCHA has made significant contributions to maintaining Internet security and preventing malicious attacks. By researching the CAPTCHA, we can find its vulnerability and improve the security of CAPTCHA. Recently, many studies have shown that improving the image preprocessing effect of the CAPTCHA, which can achieve a better recognition rate by the state-of-the-art machine learning algorithms. There are many kinds of noise and distortion in the CAPTCHA images of this experiment. We propose an adaptive median filtering algorithm based on divide and conquer in this paper. Firstly, the filtering window data quickly sorted… More >

Ou Zhang^1,*, Xueye Wei¹

CMC-Computers, Materials & Continua, Vol.58, No.2, pp. 529-544, 2019, DOI:10.32604/cmc.2019.04075

Abstract Aiming at the detection of the sucker rod defects, a real-time detection system is designed using the non-destructive testing technology of magnetic flux leakage (MFL). An MFL measurement system consists of many parts, and this study focuses on the signal acquisition and processing system. First of all, this paper introduces the hardware part of the acquisition system in detail, including the selection of the Hall-effect sensor, the design of the signal conditioning circuit, and the working process of the single chip computer (SCM) control serial port. Based on LabVIEW, a graphical programming software, the software part of the acquisition system… More >

Shanshan Yu¹, Ju Liu^1,*, Xiaoqing Zhang¹, Shangbin Wu²

CMC-Computers, Materials & Continua, Vol.58, No.2, pp. 505-516, 2019, DOI:10.32604/cmc.2019.04282

Abstract Relay-assisted transmission could effectively enhance the performance of Device-to-Device (D2D) communications when D2D user equipments (UEs) are too far away from each other or the quality of D2D channel is not good enough for direct communications. Meanwhile, security is one of the major concerns for proximity services. The secure relay selection problem for D2D communications underlaying cellular network is studied in this paper. Firstly, we define a relay selection area and derive the closed-form of outage probability in D2D links using a Poisson Point Process (PPP) method. Next, in the defined relay selection area, we propose a secure relay selection… More >

Nianbin Wang¹, Ming He^1,2, Jianguo Sun^1,*, Hongbin Wang¹, Lianke Zhou¹, Ci Chu¹, Lei Chen³

CMC-Computers, Materials & Continua, Vol.58, No.1, pp. 169-181, 2019, DOI:10.32604/cmc.2019.03709

Abstract Underwater target recognition is a key technology for underwater acoustic countermeasure. How to classify and recognize underwater targets according to the noise information of underwater targets has been a hot topic in the field of underwater acoustic signals. In this paper, the deep learning model is applied to underwater target recognition. Improved anti-noise Power-Normalized Cepstral Coefficients (ia-PNCC) is proposed, based on PNCC applied to underwater noises. Multitaper and normalized Gammatone filter banks are applied to improve the anti-noise capacity. The method is combined with a convolutional neural network in order to recognize the underwater target. Experiment results show that the… More >

Shuai Zhou^3,4, Xiaoying Zhuang^1,2,*

CMC-Computers, Materials & Continua, Vol.57, No.3, pp. 417-446, 2018, DOI:10.32604/cmc.2018.01742

Abstract The microcapsule-enabled cementitious material is an appealing building material and it has been attracting increasing research interest. By considering microcapsules as dissimilar inclusions in the material, this paper employs the discrete element method (DEM) to study the effects of loading rates on the fracturing behavior of cementitious specimens containing the inclusion and the crack. The numerical model was first developed and validated based on experimental results. It is then used to systematically study the initiation, the propagation and the coalescence of cracks in inclusion-enabled cementitious materials. The study reveals that the crack propagation speed, the first crack initiation stress, the… More >

Lingling Xia¹, Bo Song^2,3, Zhengjun Jing⁴, Yurong Song^5,*, Liang Zhang¹

CMC-Computers, Materials & Continua, Vol.57, No.1, pp. 123-144, 2018, DOI:10.32604/cmc.2018.03738

Abstract Considering dynamical disease spreading network consisting of moving individuals, a new double-layer network is constructed, one where the information dissemination process takes place and the other where the dynamics of disease spreading evolves. On the basis of Markov chains theory, a new model characterizing the coupled dynamics between information dissemination and disease spreading in populations of moving agents is established and corresponding state probability equations are formulated to describe the probability in each state of every node at each moment. Monte Carlo simulations are performed to characterize the interaction process between information and disease spreading and investigate factors that influence… More >

Xian Tang^1,*, Ziyang Chen², Haiyan Zhang³, Xiang Liu¹, Yunyu Shi¹, Asad Shahzadi⁴

CMC-Computers, Materials & Continua, Vol.55, No.2, pp. 267-283, 2018, DOI:10.3970/cmc.2018.01839

Abstract Answering reachability queries is one of the fundamental graph operations. Existing approaches either accelerate index construction by constructing an index that covers only partial reachability relationship, which may result in performing cost traversing operation when answering a query; or accelerate query answering by constructing an index covering the complete reachability relationship, which may be inefficient due to comparing the complete node labels. We propose a novel labeling scheme, which covers the complete reachability relationship, to accelerate reachability queries processing. The idea is to decompose the given directed acyclic graph (DAG) G into two subgraphs, G1 and G2. For G1, we… More >

R. Praveena¹, S. Nirmala²

CMC-Computers, Materials & Continua, Vol.53, No.1, pp. 37-47, 2017, DOI:10.3970/cmc.2017.053.039

Abstract DSP operation in a Biomedical related therapeutic hardware need to be performed with high accuracy and with high speed. Portable DSP hardware’s like pulse/heart beat detectors must perform with reduced operational power due to lack of conventional power sources. This work proposes a hybrid biomedical hardware chip in which the speed and power utilization factors are greatly improved. Multipliers are the core operational unit of any DSP SoC. This work proposes a LUT based unsigned multiplication which is proven to be efficient in terms of high operating speed. For n bit input multiplication n*n memory array of 2n bit size… More >

Yanbin Wang^1,2, Deli Gao¹, Jun Fang¹

CMC-Computers, Materials & Continua, Vol.48, No.1, pp. 57-75, 2015, DOI:10.3970/cmc.2015.048.057

Abstract In this paper, the mechanical model to analyze the riser lateral vibration displacement and stress distribution in installation has been established via variational approach and the principle of minimum potential energy. In this model, the influence of vessel motion on riser lateral vibration has been taken into consideration. The specific expression of lateral vibration has also been figured out according to the boundary conditions and initial conditions. At last, the variations of riser maximum lateral displacement and stress distribution on water depth (WD), wave height, wave period, riser OD, BOPS weight have been discussed. More >

CMC-Computers, Materials & Continua, Vol.48, No.1, pp. 43-55, 2015, DOI:10.3970/cmc.2015.048.043

Abstract This study proposed a modified unstructured kinetic model for sodium gluconate fermentation by Aspergillus niger. Four specific growth rate equations (Monod, Tessier, Contois, and logistic) were considered in the biomass growth equation. The growth, instantaneous biomass concentration, instantaneous product, and substrate concentration were considered in the equations of product formation and substrate consumption. Option parameters were introduced to determine the form of the unstructured model. A double-nested optimization strategy was proposed to optimize the option and kinetic parameters. The proposed unstructured kinetic model based on the estimated optimal parameters efficiently simulated sodium gluconate fermentation. The obtained option parameters of the… More >