Haiqi Zhu¹, Fanzhi Meng^2,*, Seungmin Rho³, Mohan Li^4,*, Jianyu Wang¹, Shaohui Liu¹, Feng Jiang¹

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 829-847, 2019, DOI:10.32604/cmc.2019.06115

Abstract In real-world many internet-based service companies need to closely monitor large amounts of data in order to ensure stable operation of their business. However, anomaly detection for these data with various patterns and data quality has been a great challenge, especially without labels. In this paper, we adopt an anomaly detection algorithm based on Long Short-Term Memory (LSTM) Network in terms of reconstructing KPIs and predicting KPIs. They use the reconstruction error and prediction error respectively as the criteria for judging anomalies, and we test our method with real data from a company in the More >

Longqing Zhang¹, Liping Bai^1,*, Xinwei Zhang², Yanghong Zhang², Lei Yang¹, Xiangdu Yan²

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 817-828, 2019, DOI:10.32604/cmc.2019.06062

Abstract The drawbacks of the traditional multi-hop structure of wireless sensor networks (WSNS) are susceptible to reflection, scattering and diffraction, serious attenuation of signal intensity and phase deviation due to various obstacles in cultivated land environment and mountains. In this paper, the wireless signal intensity is measured and curve fitting is done respectively in both open environment and obstacle-environment with both sending and receiving height of 0 m, 1 m, and 2 m. It is found out that packet loss probability is too high when an obstacle exists. In such a case, unmanned aerial vehicle (UAV) More >

Man Yang^1,2,3, Hongyuan Fang^1,2,3,*, Juan Zhang⁴, Fuming Wang^1,2,3, Jianwei Lei^1,2,3, Heyang Jia^1,2,3

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 793-816, 2019, DOI:10.32604/cmc.2019.06042

Abstract Possessing advantages such as high computing efficiency and ease of programming, the Symplectic Euler algorithm can be applied to construct a ground-penetrating radar (GPR) wave propagation numerical model for complex geoelectric structures. However, the Symplectic Euler algorithm is still a difference algorithm, and for a complicated boundary, ladder grids are needed to perform an approximation process, which results in a certain amount of error. Further, grids that are too dense will seriously decrease computing efficiency. This paper proposes a conformal Symplectic Euler algorithm based on the conformal grid technique, amends the electric/magnetic field-updating equations of… More >

Yeting Guo¹, Fang Liu^2,*, Nong Xiao¹, Zhengguo Chen^1,3

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 777-792, 2019, DOI:10.32604/cmc.2019.06366

Abstract Edge computing attracts online service providers (SP) to offload services to edge computing micro datacenters that are close to end users. Such offloads reduce packet-loss rates, delays and delay jitter when responding to service requests. Simultaneously, edge computing resource providers (RP) are concerned with maximizing incomes by allocating limited resources to SPs. Most works on this topic make a simplified assumption that each SP has a fixed demand; however, in reality, SPs themselves may have multiple task-offloading alternatives. Thus, their demands could be flexibly changed, which could support finer-grained allocations and further improve the incomes… More >

Suzhen Wang¹, Shanshan Geng¹, Zhanfeng Zhang¹, Anshan Ye², Keming Chen², Zhaosheng Xu², Huimin Luo², Gangshan Wu^3,*, Lina Xu⁴, Ning Cao⁵

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 739-757, 2019, DOI:10.32604/cmc.2019.06097

Abstract Spark is a distributed data processing framework based on memory. Memory allocation is a focus question of Spark research. A good memory allocation scheme can effectively improve the efficiency of task execution and memory resource utilization of the Spark. Aiming at the memory allocation problem in the Spark2.x version, this paper optimizes the memory allocation strategy by analyzing the Spark memory model, the existing cache replacement algorithms and the memory allocation methods, which is on the basis of minimizing the storage area and allocating the execution area according to the demand. It mainly including two… More >

Chaoyang Li^1,2,3, Gang Xu², Yuling Chen^1,*, Haseeb Ahmad⁴, Jian Li³

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 711-726, 2019, DOI:10.32604/cmc.2019.06279

Abstract Blockchain technology has become a research hotspot in recent years with the prominent characteristics as public, distributed and decentration. And blockchain-enabled internet of things (BIoT) has a tendency to make a revolutionary change for the internet of things (IoT) which requires distributed trustless consensus. However, the scalability and security issues become particularly important with the dramatically increasing number of IoT devices. Especially, with the development of quantum computing, many extant cryptographic algorithms applied in blockchain or BIoT systems are vulnerable to the quantum attacks. In this paper, an anti-quantum proxy blind signature scheme based on More >

Yugai Huang^1,2,3, Yu Shang^1,4, Wenqing Li¹, Jiajing He¹, Hairong Zhou¹, Bin Gu^1,*

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 701-710, 2019, DOI:10.32604/cmc.2019.03109

Abstract The configurations of molecular clusters have significant impacts on their growth into fine particles in atmosphere. In this paper, we explore the topology space of the structure of H2SO4·NH3 dimer with a novel sampling technique of meta-dynamics (MTD) method and ab initio molecular dynamics simulations. The simulations are carried out at the temperatures of both 50 K and 242 K, which represent the typical high and low latitudes of troposphere. The results show that, compared with only traditional MD simulations, the structure samplings are significantly accelerated with MTD method. Therefore, more isomers of the dimer More >

Bin Lu¹, Fenlin Liu¹, Xin Ge^1,*, Zhenyu Li²

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 687-699, 2019, DOI:10.32604/cmc.2019.05633

Abstract Due to the characteristics of chaotic systems, different cryptosystems based on chaos have been proposed to satisfy the security of multimedia data. A plain image-related chaotic algorithm is proposed by Luo et al. with high speed and efficiency. Security weaknesses of the cryptosystem are studied in this paper. It is found that the important secret key information is leaked because an important parameter can be obtained after an inverse operation in the last step of the cryptosystems without secret key. Meanwhile, the value zero is processed improperly in quantification algorithm. Based on the weaknesses, chosen More >

Yang Zhao¹, Shibin Zhang^1,*, Min Yang¹, Peilin He¹, Qirun Wang²

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 677-686, 2019, DOI:10.32604/cmc.2019.05936

Abstract The risk assessment system has been applied to the information security, energy, medical and other industries. Through the risk assessment system, it is possible to quantify the possibility of the impact or loss caused by an event before or after an event, thereby avoiding the risk or reducing the loss. However, the existing risk assessment system architecture is mostly a centralized architecture, which could lead to problems such as data leakage, tampering, and central cheating. Combined with the technology of block chain, which has the characteristics of decentralization, security and credibility, collective maintenance, and untamperability. More >

Chen Zhang¹, Jieren Cheng^1,2,3,*, Xiangyan Tang¹, Victor S. Sheng⁴, Zhe Dong¹, Junqi Li¹

CMC-Computers, Materials & Continua, Vol.61, No.2, pp. 657-675, 2019, DOI:10.32604/cmc.2019.06207

Abstract Distributed denial of service (DDoS) attacks launch more and more frequently and are more destructive. Feature representation as an important part of DDoS defense technology directly affects the efficiency of defense. Most DDoS feature extraction methods cannot fully utilize the information of the original data, resulting in the extracted features losing useful features. In this paper, a DDoS feature representation method based on deep belief network (DBN) is proposed. We quantify the original data by the size of the network flows, the distribution of IP addresses and ports, and the diversity of packet sizes of More >