Ahmed Meskini, Mostafa Najam, Mustapha El Alami

FDMP-Fluid Dynamics & Materials Processing, Vol.7, No.1, pp. 97-110, 2011, DOI:10.3970/fdmp.2011.007.097

Abstract A numerical mixed convection investigation was carried out to study the enhancement of heat transfer in a square cavity with identical heated rectangular blocks adjacent to its upper wall, and submitted to a vertical jet of fresh air from below. The configuration so defined is an inverted "T"-shaped cavity presenting symmetry with respect to a vertical axis passing by the middle of the openings. The governing equations have been solved using the finite difference method. The parameters of this study are: Rayleigh number 10⁴ ≤ Ra ≤ 10⁶, Reynolds number 1 ≤ Re ≤ 1000, the opening width C=0.15, the… More >

Hicham Rouijaa¹, Mustapha El Alami², El Alami Semma³, Mostafa Najam²

FDMP-Fluid Dynamics & Materials Processing, Vol.7, No.1, pp. 57-70, 2011, DOI:10.3970/fdmp.2011.007.057

Abstract This article presents a numerical study on natural convection in a bidimensional inclined "T"-shaped cavity. The governing equations are solved in the framework of a control-volume method resorting to the SIMPLEC algorithm (for the treatment of pressure-velocity coupling). Special emphasis is given to the investigation of the effect of inclination on the heat transfer and mass flow rate. Results are discussed for Prandtl number Pr=0.72, geometry with: opening width C=0.15, blocks gap D=0.5, blocks height, B=0.5 and different values of the Rayleigh number (10⁴ ≤ Ra ≤ 10⁶). More >

M. El Alami¹, E. A. Semma^2,3, M. Najam¹, R. Boutarfa²

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.1, pp. 23-36, 2009, DOI:10.3970/fdmp.2009.005.023

Abstract This study is devoted to the investigation of natural convection in a two dimensional horizontal channel with rectangular heated blocks at the bottom. The aspect ratio of the channel is A = L'/H' = 5. The blocks are heated with a constant temperature while the upper plane of the channel is cold. The governing equations are solved using a finite volumes method and the SIMPLEC algorithm is used for the treatment of the pressure-velocity coupling. Special emphasis is given to detail the effect of the Rayleigh number and blocks height on the heat transfer and the mass flow rate generated… More >

Viveca Wallqvist¹, Per M. Claesson², Agne Swerin¹, Patrick A. C. Gane^3,4,3, Joachim Schoelkopf³

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.2, pp. 85-98, 2008, DOI:10.3970/fdmp.2008.004.085

Abstract It has been shown that talc powder can be compacted into tablets with a preferred orientation of the platelets. The tablets can be obtained with different controlled porosity depending on pressing methods and applied pressure. The tablets can be obtained with or without additives, which may, in turn, be adsorbed. The orientation of the high aspect ratio platy talc, the surface chemistry imparted by the additives and the transported fluid influence the imbibition and permeation rates. Non-polar hexadecane displays a higher imbibition and permeability than water for all particulate orientations during short timescale absorption, likely due to the oleophilic nature… More >

Gengxin Sun^1,*, Sheng Bin¹, Meng Jiang², Ning Cao³, Zhiyong Zheng⁴, Hongyan Zhao⁵, Dongbo Wang⁶, Lina Xu⁷

CMC-Computers, Materials & Continua, Vol.60, No.3, pp. 1015-1027, 2019, DOI:10.32604/cmc.2019.05644

Abstract With the emergence and development of blockchain technology, a new type of social networks based on blockchain had emerged. In these social networks high quality content creators, filters and propagators can all be reasonably motivated. Due to the transparency and traceability brought by blockchain technology, the public opinion propagation in such social networks presents new characteristics and laws. Based on the theory of network propagation and blockchain, a new public opinion propagation model for this kind of social network based on blockchain technology is proposed in this paper. The model considers the effect of incentive mechanism produced by reasonably quantifying… More >

Rui Song¹, Yubo Song^1,*, Ziming Liu², Min Tang², Kan Zhou³

CMC-Computers, Materials & Continua, Vol.60, No.3, pp. 973-987, 2019, DOI:10.32604/cmc.2019.06035

Abstract The birth of blockchain has promoted the development of electronic currencies such as Bitcoin and Ethereum. Blockchain builds a financial system based on cryptology instead of credit, which allows parties to complete the transaction on their own without the need for credible third-party intermediaries. So far, the application scenario of blockchain is mainly confined to the peer-to-peer electronic financial system, which obviously does not fully utilize the potential of blockchain.
In this paper, we introduce GaiaWorld, a new system for decentralized application. To solve the problem of resource waste and mismatch between nodes and computing power in traditional PoW… More >

Xin Jiang¹, Mingzhe Liu^1,*, Chen Yang¹, Yanhua Liu¹, Ruili Wang²

CMC-Computers, Materials & Continua, Vol.58, No.1, pp. 45-59, 2019, DOI:10.32604/cmc.2019.03863

Abstract In order to deploy a secure WLAN mesh network, authentication of both users and APs is needed, and a secure authentication mechanism should be employed. However, some additional configurations of trusted third party agencies are still needed on-site to deploy a secure authentication system. This paper proposes a new block chain-based authentication protocol for WLAN mesh security access, to reduce the deployment costs and resolve the issues of requiring key delivery and central server during IEEE 802.11X authentication. This method takes the user’s authentication request as a transaction, considers all the authentication records in the mesh network as the public… More >

Zhiliang Deng^1,2, Yongjun Ren^3,4, Yepeng Liu^3,4, Xiang Yin⁵, Zixuan Shen^3,4, Hye-Jin Kim^6,*

CMC-Computers, Materials & Continua, Vol.58, No.1, pp. 135-151, 2019, DOI:10.32604/cmc.2019.02967

Abstract Cloud storage represents the trend of intensive, scale and specialization of information technology, which has changed the technical architecture and implementation method of electronic records management. Moreover, it will provide a convenient way to generate more advanced and efficient management of the electronic data records. However, in cloud storage environment, it is difficult to guarantee the trustworthiness of electronic records, which results in a series of severe challenges to electronic records management. Starting from the definition and specification of electronic records, this paper firstly analyzes the requirements of the trustworthiness in cloud storage during their long-term preservation according to the… More >

Guoyuan Lin^1,2,*, Bowen Liu¹, Pengcheng Xiao³, Min Lei⁴, Wei Bi^5,6

CMC-Computers, Materials & Continua, Vol.57, No.3, pp. 533-547, 2018, DOI:10.32604/cmc.2018.03720

Abstract Anti-detection is becoming as an emerging challenge for anti-phishing. This paper solves the threats of anti-detection from the threshold setting condition. Enough webpages are considered to complicate threshold setting condition when the threshold is settled. According to the common visual behavior which is easily attracted by the salient region of webpages, image retrieval methods based on texton correlation descriptor (TCD) are improved to obtain enough webpages which have similarity in the salient region for the images of webpages. There are two steps for improving TCD which has advantage of recognizing the salient region of images: (1) This paper proposed Weighted… More >

Daofu Gong^1,2, Yan Chen^1,2, Haoyu Lu^1,*, Zhenyu Li³, Yibing Han¹

CMC-Computers, Materials & Continua, Vol.57, No.2, pp. 243-260, 2018, DOI:10.32604/cmc.2018.03781

Abstract To detect and recover random tampering areas, a combined-decision-based self-embedding watermarking scheme is proposed herein. In this scheme, the image is first partitioned into 2×2 size blocks. Next, the high 5 bits of a block’s average value is embedded into its offset block. The tampering type of block is detected by comparing the watermarks of its pre-offset and post-offset blocks. The theoretical analysis and experiments demonstrate that the proposed scheme not only has a lower ratio of false detection but also better performance with regard to avoiding random tampering. More >