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8th International Conference on Advances in Information Technology (IAIT)

作者： Liang, Chen Zhang, Yu Song, Jian Tsinghua Univ Dept Elect Engn Tsinghua Natl Lab Informat Sci & Technol TNList Beijing 100084 Peoples R China Sci & Technol Informat Transmiss & Disseminat Com Shenzhen 518057 Peoples R China Shenzhen City Key Lab Digital TV Syst Shenzhen 518057 Peoples R China

Wireless ad hoc networks with broadcasting are widely applied in IoT and emergency situations as the network can be set up without traditional infrastructures. In this paper, we propose a TDMA-based mac algorithm which supports data transmission by broadcasting. The algorithm is similar with the mechanism in NbIA algorithm (1,2) in neighbour discovery, but differs a lot in collision detection and slot allocation. Our algorithm can dynamically allocate slots according to the demand of nodes and ensures every node get at least one slot a cycle. Based on spatial reuse, idle slots might be found and be used as extra slots of nodes which can promote throughput of our algorithm. After the network converges, only a few nodes need to adjust their slots to adapt to topology changes, while most of the nodes maintain their slots to transmit data. The performance of our algorithm and NbIA algorithm are compared with OPNET simulation. The results show that our algorithm outperforms NbIA especially in convergence time and average throughput of nodes. (C) 2017 The Authors. Published by Elsevier B.V.

关键词： Ad hoc network mac algorithm Broadcast Slot assignment

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A novel broadcasting mac algorithm for ad hoc networks

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Procedia Computer Science 2017年 111卷 268-276页

作者： Chen Liang Yu Zhang Jian Song Tsinghua National Laboratory for Information Science and Technology (TNList) Tsinghua University Department of Electronics Engineering Tsinghua University Beijing 100084 China Science and Technology on Information Transmission and Dissemination in Communication Networks Laboratory Shenzhen City Key Laboratory of Digital TV System Shenzhen 518057 China

Wireless ad hoc networks with broadcasting are widely applied in IoT and emergency situations as the network can be set up without traditional infrastructures. In this paper, we propose a TDMA-based mac algorithm which supports data transmission by broadcasting. The algorithm is similar with the mechanism in NbIA algorithm 1,2 in neighbour discovery, but differs a lot in collision detection and slot allocation. Our algorithm can dynamically allocate slots according to the demand of nodes and ensures every node get at least one slot a cycle. Based on spatial reuse, idle slots might be found and be used as extra slots of nodes which can promote throughput of our algorithm. After the network converges, only a few nodes need to adjust their slots to adapt to topology changes, while most of the nodes maintain their slots to transmit data. The performance of our algorithm and NbIA algorithm are compared with OPNET simulation. The results show that our algorithm outperforms NbIA especially in convergence time and average throughput of nodes.

关键词： Ad hoc network mac algorithm Broadcast Slot assignment

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NUMERICAL STUDY OF FREE CONVECTION Ag-WATER NANOFLUID FLOW IN A SQUARE ENCLOSURE WITH VISCOUS DISSIPATION AND HEAT GENERATION/ABSORPTION EFFECTS IN A POROUS MEDIUM WITH COMPLEX WALL CONDITIONS

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JOURNAL OF POROUS MEDIA 2023年第9期26卷 77-99页

作者： Vinodhini, Nithiyanandam Prasad, Vallampati Ramachandra Vellore Inst Technol Sch Adv Sci Dept Math Vellore 632014 India

Nanofluids hold great promise in improving transport processes in energy systems including hybrid fuel cells. In this present work, a mathematical model is developed for laminar free convection flow of Ag-water nano-additives in an enclosure in a porous medium with complex boundary conditions. Additionally, heat generation/absorption and viscous dissipation effects are included. Via appropriate scaling transformations, the conservation equations for mass, primary and secondary momentum, energy, and nanoparticle vorticity with wall boundary conditions are rendered dimensionless. A finite-difference computational scheme known as the marker and cell (mac) method, developed by Harlow and Welch, is occupied to solve the dimensionless, nonlinear coupled boundary value problem. A mesh independence study is included. The impact of parameters such as Eckert number (Ec), Darcy number (Da), Grashof number (Gr), Prandtl number (Pr), Reynolds number (Re), and Richardson number (Ri) are observed with physical framework. Graphical plots are presented for the impact of key control parameters on streamline contours, isotherm contours, and local Nusselt number. By heat sink (absorption), the Nusselt number is increased, whereas by heat generation it is reduced since there is a decrease in heat transferred to the boundary. The presence of viscous dissipation effects moves the streamlines toward the blue core and allows the temperature to increase in the neighborhood of the hot wall of the envelope. An increase in Richardson number induces a flip in vortex cell structures from an initially strong circulation cell on the left and weaker cell on the right, to the opposite distribution. Significant cooling is also induced in the core zone with an increasing Richardson number, and a decrease in vorticity is observed.

关键词： convective flow Ag-water nanoparticles isotropic porous medium mac algorithm square enclosure viscous dissipation

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Comparative Experiments of V2X Security Protocol Based on Hash Chain Cryptography

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SENSORS 2020年第19期20卷 5719.-5719.页

作者： Hakeem, Shimaa A. Abdel Abd El-Gawad, Mohamed A. Kim, HyungWon Chungbuk Natl Univ Sch Elect Engn Cheongju 28644 South Korea Elect Res Inst ERI Giza 12622 Egypt Korea Univ Sch Elect Engn Seoul 02841 South Korea Natl Telecommun Inst Cairo 11768 Egypt

Vehicle-to-everything (V2X) is the communication technology designed to support road safety for drivers and autonomous driving. The light-weight security solution is crucial to meet the real-time needs of on-board V2X applications. However, most of the recently proposed V2X security protocols-based on the Elliptic Curve Digital Signature algorithm (ECDSA)-are not efficient enough to support fast processing and reduce the communication overhead between vehicles. ECDSA provides a high-security level at the cost of excessive communication and computation overhead, which motivates us to propose a light-weight message authentication and privacy preservation protocol for V2X communications. The proposed protocol achieves highly secure message authentication at a substantially lower cost by introducing a hash chain of secret keys for a Message Authentication Code (mac). We implemented the proposed protocol using commercial V2X devices to prove its performance advantages over the standard and non-standard protocols. We constructed real V2X networks using commercial V2X devices that run our implemented protocol. Our extensive experiments with real networks demonstrate that the proposed protocol reduces the communication overhead by 6 times and computation overhead by more than 100 times compared with the IEEE1609.2 standard. Moreover, the proposed protocol reduces the communication overhead by 4 times and the computation overhead by up to 100 times compared with a non-standard security protocol, TESLA. The proposed protocol substantially reduces the average end-to-end delay to 2.5 ms, which is a 24- and 28-fold reduction, respectively, compared with the IEEE1609 and TESLA protocols.

关键词： mac algorithm hash-chain privacy commercial V2X devices authentication IEEE1609 2

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A Decentralized Lightweight Authentication and Privacy Protocol for Vehicular Networks

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IEEE ACCESS 2019年 7卷 119689-119705页

作者： Hakeem, Shimaa A. Abdel Abd El-Gawad, Mohamed A. Kim, Hyungwon Chungbuk Natl Univ Elect Engn Dept Cheongju 28644 South Korea ERI Giza 12622 Egypt Natl Telecommun Inst Cairo 11768 Egypt

Recently many security protocols have been proposed for road safety applications in Vehicle-to-everything (V2X) communications. Most of them, however, do not fully satisfy the requirements of light-weight and fast processing, which are special properties for V2X. Most of the previous authentication protocols assume that a Certificate Authority (CA) is present within the communication range from all the vehicles, which is not practical for moving vehicles. We propose a light-weight security protocol for authentication and privacy protection for V2X. It employs two security hardware devices, Biometric Device (BD) and Tamper Proof Device (TPD), which verifies the driver and securely keeps the keys, respectively. It decentralizes the CA's tasks by locally generating pseudo-identity and private keys to preserve privacy and provide authentication in Vehicle-to-Vehicle (V2V) communication. In addition, we propose an authentication signature protocol using a notion of hash-chain key generation. We implemented the proposed key generation and authentication protocol using NS-3 simulator. Our extensive simulations demonstrated that the proposed authentication protocol significantly enhances the security level while protecting the conditional privacy of vehicles by utilizing anonymous identities. The proposed protocol has a 20% similar to 85% less communication overhead compared with the previous protocols.

关键词： Hash-chain mac algorithm privacy two-factor authentication biometric tamperproof

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Influence of external magnetic wire on natural convection of non-Newtonian fluid in a square cavity

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Partial Differential Equations in Applied Mathematics 2021年 4卷

作者： Sarala Devi, T. Venkata Lakshmi, C. Venkatadri, K. Suryanarayana Reddy, M. Department of Applied Mathematics Sri Padmavathi Mahila Visvavidyalayam AP Tirupati 517502 India Department of Mathematics Sreenivasa Institute of Technology and Management Studies Chittoor 517127 India Department of Mathematics JNTUA College of Engineering Pulivendula India

The augment of heat transfer and intensity of fluid has wide range of application in science and engineering. The buoyancy-driven flow of Casson viscoelastic fluid in a square cavity in the presence of external magnetic field is examined numerically. Cold temperature is applied on the right side (vertical) wall and high temperature is imposed on left wall while the horizontal walls are kept at thermally insulated. The mathematical model comprises mass and primary and secondary momentum conservation equations and boundary conditions imposed at the four sides of the enclosure. The model is non-dimensional and converted into pressure–velocity form. The Harlow–Welch marker and cell (mac) finite difference technique is employed to solve the nonlinear boundary value problem via pressure–velocity coupling. The developed MATLAB code is validated with previous literature and it gives good agreement. The effects of Rayleigh number Ra, Casson viscoplastic fluid parameter and Hartmann number Ha on the flow and heat transfer characteristics are analyzed. Results indicate that the temperature gradient is an increasing function of the buoyancy force. The heat transfer characteristics and flow behavior are presented in the form of streamlines and isotherms. © 2021 The Author(s)

关键词： Casson viscoelastic fluid Cavity FDM mac algorithm Magnetizable fluid

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An Energy-Efficient Smart Monitoring System Using ZigBee Wireless Sensor Network 4

An Energy-Efficient Smart Monitoring System Using ZigBee Wir...

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4th National-Foundation-for-Science-and-Technology-Development (NAFOSTED) Conference on Information and Computer Science (NICS)

作者： Van-Lan Dao Xuan-Thiep Nguyen Van-Phuc Hoang Le Quy Don Tech Univ 236 Hoang Quoc Viet Str Hanoi Vietnam Viettel Res & Dev Inst Hanoi Vietnam

ISBN: (纸本)9781538632109

In this paper, we present the design of an energy-saving wireless sensor network using ZigBee standard with tree network topology and the frequency band of 2.4 GHz. By choosing low power consumption components, modifying the mac algorithm and AES cryptography, the proposed network allows users to utilize the power efficiently, provide high level of security and can be applied to a variety of applications.

关键词： Wireless sensor networks Temperature sensors Cryptography Monitoring algorithm design and analysis Niobium Wireless sensor networks algorithm design and analysis cryptography Temperature Sensor Device Component niobium Security level mac algorithm ZigBee Frequency bands

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The Study on the Increasing Strategy of Detecting Moving Target in Wireless Sensor Networks

The Study on the Increasing Strategy of Detecting Moving Tar...

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14th International Conference on algorithms and Architectures for Parallel Processing (ICA3PP)

作者： Xu, Jialong Chen, Zhigang Liu, Anfeng Song, Hong Cent South Univ Sch Software Changsha Hunan Peoples R China Cent South Univ Sch Informat Sci & Engn Changsha Peoples R China

ISBN: (纸本)9783319111971;9783319111964

Wireless Sensor Networks (WSNs) have promising and valuable applications. More and more researchers have conducted research in this area. Because sensor nodes are small and cheap, they usually use battery to provide energy. However, as a great number of nodes are arranged in the network and the working environment is bad, it is difficult to replace batteries or recharge. How to make full use of network resources to ensure the high quality of the network and achieve a balanced network is a problem to be faced. This paper focuses on improvement in wireless sensor networks by improving the mac protocol. mac protocols are basic protocols in WSNs and they influence the performance of network a lot. In those networks that need to track mobile targets, how to achieve the goal of increasing the monitor rate and balance the consumption of network are two very important objectives focused by modifying the mac protocols. In this paper, we proposed the IMMA to improve the efficiency of the network. The core of this algorithm is by changing the cycle of the state to balance the energy consumption, and increase the monitor rate. IMMA balances energy consumption and enhances the monitor rate of the moving targets. Theoretical and experimental results show that the algorithm improved network efficiency a lot.

关键词： mac algorithm network energy balance objective monitoring rate

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COMPUTATION OF FLOW PAST COMPLEX GEOMETRIES USING mac algorithm ON BODY-FITTED COORDINATES

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ENGINEERING APPLICATIONS OF COMPUTATIONAL FLUID MECHANICS 2009年第1期3卷 15-27页

作者： Patil, Pratish P. Tiwari, Shaligram Indian Inst Technol Dept Mech Engn Madras 600036 Tamil Nadu India

The study aims to report an algorithm based on co-ordinate transformation to compute complex flows. A two-dimensional computational code is developed using transformation of governing incompressible flow equations by employing body-fitted co-ordinates. The complex flows may involve external flows past obstacles having curved surfaces or internal flows confined in curved domains. The transformed governing equations are discretized using mac algorithm. The code has been validated by comparing variation of Strouhal number with Reynolds number for flow past a circular cylinder.

关键词： complex geometries body-fitted co-ordinates mac algorithm incompressible flows skewed grids

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Text Integrity Verification for Faxed Document Using Pixel Reorganizing Technique

Text Integrity Verification for Faxed Document Using Pixel R...

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10th International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information Technology (ECTI-CON)

作者： Pramoun, Thitiporn Amornraksa, Thumrongrat King Mongkuts Univ Technol Fac Engn Dept Comp Engn Multimedia Commun Lab Bangkok 10140 Thailand

ISBN: (纸本)9781479905461;9781479905454

since text in faxed document can be altered by malicious person who can get the faxed document directly from fax machine without permission from the real recipient, the method of text integrity verification for faxed document is proposed to detect any modification of text content in the faxed document. To solve such problem, digital camera is first employed to capture the faxed document in order to obtain a faxed document image. However, there will be some RST (rotation, scaling and translation) distortions occurring in that captured image, which consequently affects the accuracy of text integrity verification, we thus propose pixel reorganizing technique to reduce such distortions. Text content in the faxed document image is then verified based on the use of mac algorithm in order to detect any altered text in the faxed document. The experimental results show the efficiency of our proposed method with various text font sizes in detecting altered text content in the faxed documents.

关键词： text integrity verification faxed document image digital camera RST (rotation, scaling and translation) distortions mac algorithm

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