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Journal of Information Security 2011年第2期2卷 69-84页

作者： shahriar Mohammadi Reza Ebrahimi Atani Hossein Jadidoleslamy 不详

Wireless sensor networks (WSNs) have many potential applications [1,2] and unique challenges. They usually consist of hundreds or thousands of small sensor nodes such as MICA2, which operate autonomously;conditions such as cost, invisible deployment and many application domains, lead to small size and resource limited sensors [3]. WSNs are susceptible to many types of link layer attacks [1] and most of traditional network security techniques are unusable on WSNs [3];This is due to wireless and shared nature of communication channel, untrusted transmissions, deployment in open environments, unattended nature and limited resources [1]. Therefore security is a vital requirement for these networks;but we have to design a proper security mechanism that attends to WSN’s constraints and requirements. In this paper, we focus on security of WSNs, divide it (the WSNs security) into four categories and will consider them, include: an overview of WSNs, security in WSNs, the threat model on WSNs, a wide variety of WSNs’ link layer attacks and a comparison of them. This work enables us to identify the purpose and capabilities of the attackers;furthermore, the goal and effects of the link layer attacks on WSNs are introduced. Also, this paper discusses known approaches of security detection and defensive mechanisms against the link layer attacks;this would enable IT security managers to manage the link layer attacks of WSNs more effectively.

关键词： Wireless Sensor Network Security Link Layer Attacks Detection Defensive Mechanism

Comparative Analysis of Hydrodynamics Behavior of Microalgae Suspension Flow in Circular, Square and Hexagonal Shape Photo Bioreactors

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American Journal of Computational Mathematics 2016年第4期6卷 320-335页

作者： Mushfique shahriar Mohammad Iftekhar Monir Ujjwal Kumar Deb Department of Mechanical Engineering Chittagong University of Engineering & Technology Chittagong Bangladesh Department of Mathematics Premier University Chittagong Bangladesh Department of Mathematics Chittagong University of Engineering & Technology Chittagong Bangladesh

Microalgae based biofuel is an emerging natural source of energy alternative to the fossil fuel. As microalgae are photosynthetic microorganisms, light is one of the limiting factors for its culture. Though many researches have been carried out for findings behind suitable culture system for the proper growth of microalgae, those are confined only to tubular Photo-bioreactor (PBR). This paper aims to make comparison among the horizontal loop photo bioreactors with different cross sections based on the analysis of hydrodynamics behavior. Three different geometrical shapes having vertical cross sections of circular, square and hexagonal PBR, have been proposed taking into account light intensity for microalgae culture. In this study, we simulate the flow dynamics of three types of PBRs and discuss the velocity, pressure and shear stress properties as microalgae endurance capacity depends on them. For the dimension of the three PBRs we considered here, each of them have radius of about 0.05 m while the length together with bending portion is approximately 20.5 m for a single loop. From the study, the hydrodynamic behaviors are observed to be quite dissimilar in case of three PBR’s. In the straight portion the velocity profile is quite parabolic in tubular but distorted minimally in case of square and hexagonal PBRs. In the middle of the U-loop, a haphazard fluid distribution is noticed. The velocity magnitude and agitation of microalgae cells are higher in hexagonal than in square and tubular. The shear rate is less in case of tubular compared to square and hexagonal. A linear pressure drop is found from the inlet to the outlet for three PBR’s. From this comparison, it can be said that the tubular one would be the best option for microalgae culture in case of industrial purposes.

关键词： CFD Microalgae Biofuel Photo Bioreactor Simulation

Experimental Study on Reflection Coefficient of Curved Perforated Plate

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Journal of Marine Science and Application 2016年第4期15卷 382-387页

作者： Sayed Mohammad Reza Hodaei1, Mohammad Reza Chamani Mohammad Reza Chamani Mohammad Navid Moghim, shahriar Mansoorzadeh Abdoreza Kabiri-Samani Department of Civil Engineering Isfahan University of Technology Isfahan PO. Box 84156 Iran SubSea R&D Center Isfahan University of Technology Isfahan P.O. Box 84156 Iran

一套实验在一辆拖引的坦克被执行在波浪思考系数上学习穿孔盘子的弯曲的效果(C r ) 。一个穿孔盘子的弯曲能被旋转改变一本参考书穿孔了板 aboutits 起源根据寓言的方程 y=x 2 。一个塞子类型波浪制造者被用来产生常规波浪。思考系数用... 详细信息

一套实验在一辆拖引的坦克被执行在波浪思考系数上学习穿孔盘子的弯曲的效果(C r ) 。一个穿孔盘子的弯曲能被旋转改变一本参考书穿孔了板 aboutits 起源根据寓言的方程 y=x 2 。一个塞子类型波浪制造者被用来产生常规波浪。思考系数用 Goda 和铃木(1976 ) 被计算方法。结果与垂直或倾斜的被动波浪吸收器的那些相比。比较证明有弄弯的侧面的一个穿孔盘子以减少波浪思考系数是高度有效的。关联被建立作为流动和几何学特征的功能估计弄弯的穿孔盘子的思考系数。

关键词：穿孔的板弄弯的侧面思考系数波浪吸收器常规波浪

A Comparative Study of Email Forensic Tools

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Journal of Information Security 2015年第2期6卷 111-117页

作者： Vamshee Krishna Devendran Hossain shahriar Victor Clincy Department of Compute Science Kennesaw State University Kennesaw GA USA

Over the last decades, email has been the major carrier for transporting spam and malicious contents over the network. Email is also the primary source of numerous criminal activities on the Internet. Computer Forensics is a systematic process to retain and analyze saved emails for the purpose of legal proceedings and other civil matters. Email analysis is challenging due to not only various fields that can be forged by hackers or malicious users, but also the flexibility of composing, editing, deleting of emails using offline (e.g., MS Outlook) or online (e.g., Web mail) email applications. Towards this direction, a number of open source forensics tools have been widely used by the practitioners. However, these tools have been developed in an isolated manner rather than a collaborative approach. Given that email forensic tool users need to understand to what extent a tool would be useful for his/her circumstances and conducting forensic analysis accordingly. In this paper, we examine a set of common features to compare and contrast five popular open source email forensic tools. The study finds that all email forensic tools are not similar, offer diverse types of facility. By combining analysis tools, it may be possible to gain detailed information in the area of email forensic.

关键词： Email Forensic Header and Content Analysis Data Recovery Search Option Visualization

A Novel Cross-Layer Scheduling Algorithm for OFDMA-Based WiMAX Networks

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International Journal of Communications, Network and System Sciences 2011年第2期4卷 98-103页

作者： Ronak Farhadi Vahid Tabataba Vakili shahriar Shirvani Moghaddam 不详

IEEE 802.16e based WiMAX networks promise a desirable available quality of service for mobile users and scheduling algorithms provide the best effective use of network resources in it. In this paper, we propose a novel cross-layer scheduling algorithm for OFDMA-based WiMAX networks. Our scheme employs a priority function at the MAC layer and a slot allocation policy at physical layer and by interaction between these two layers specifies the best allocation for each connection. Simulation results show performance of proposed scheme in comparison with two other well-known scheduling algorithms, MAX-SNR scheduling and Proportional Fairness (PF) scheduling. Our proposed cross-layer algorithm outperforms the other algorithms in delay and packet loss rate values for real-time services.

关键词： Cross-Layer IEEE802.16e OFDMA QoS Scheduling WiMAX

Investigation of Flow Dynamics for a Microalgae Suspension in an Open Pond System

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American Journal of Computational Mathematics 2017年第3期7卷 195-207页

作者： Nandita Barua Singha Ujjwal Kumar Deb Mushfique shahriar Department of Mathematics Marine Fisheries Academy Chittagong Bangladesh Department of Mathematics Chittagong University of Engineering and Technology Chittagong Bangladesh Department of Mechanical Engineering Chittagong University of Engineering and Technology Chittagong Bangladesh

In the microalgae based biofuel technology, two main cultivation methods are available such as the Open pond system and the Closed photo bioreactor (PBR). The primary advantages of utilizing open raceway ponds are low production and maintenance cost. Though the open raceway ponds have been adjudged potentially cost effective, so many surrounding issues are involved to produce microalgae at a large scale that could make microalgae fuel cost competitive with the conventional petro oil. Many researchers have been studied so far to increase the efficiency of the cultivation methods without providing a proper mathematical model of flow dynamics inside the open raceway ponds. This paper presents a mathematical model to analyze the flow behavior of an open pond culture focusing the mixing factors by using a paddlewheel while the paddlewheel have its own unique dynamic characteristics. From our simulation we observed that the paddlewheel plays a vital role in mixing and the growth of microalgae. The velocity profiles, shear stress distributions are also studied at different parts of an open pond culture for a microalgae suspension.

关键词： Biofuel Microalgae Open Pond System Fluid Dynamics Simulation

Magnetohydrodynamic Activity During Limiter Biasing on the CT-6B Tokamak

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Chinese Physics Letters 2001年第3期18卷 393-395页

作者： KHORSHID Pejman 王龙杨宣宗冯春华张鹏云戚霞枝 ROUHANI shahriar RAHIMITABAR M.Reza AGHAMIR M.Farzin GHORANNEVISS Mahmud HANTEZADEH M.Reza Institute of Physics Chinese Academy of SciencesBeijing 100080 Plasma Physics Research Centre Azad UniversityTehranIran Institute for Studies in Theoretical Physics and Mathematics TehranIran

Magnetohydrodynamic phenomena in the CT-6B Tokamak based on Mirnov oscillations have been investigated by applying the limiter biasing potentials and changing the vacuum chamber gas pressure and plasma *** results show that setting up a radial electric field at the plasma edge could drive electromagnetic instabilities in the tokamak *** oscillation frequency upon application of a positive bias decreases about 10-15%and then after a delay time,τ_(d)=2.5-3 ms increases about 20-25%with respect to their value without *** the negative bias regime the oscillation frequency increases about 10%in 1 ms after the application of the bias *** poloidal rotation velocity changes during two steps are related to its link with the radial electric field and the time scale of the density *** frequency of oscillations increases with the increasing chamber gas pressure and decreases with the increasing the outward plasma displacement.

关键词： Tokamak oscillation tokamak

Phytochemical screening, antibacterial and anthelmintic activities of leaf and seed extracts of Coix lacryma-jobi L.

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Journal of Coastal Life Medicine 2017年第8期5卷 360-364页

作者： Sajan Das Rumana Akhter Sumana Khandaker Sumaiya Huque Promit Das md.Rafi Anwar Kaniz Afroz Tanni Samia Shabnaz Mohammad shahriar Phytochemistry Research Laboratory Department of PharmacyUniversity of Asia PacificDhaka-1215Bangladesh

Objective: To evaluate the possible phytochemical constituents, antibacterial and anthelmintic activity of Coix lacryma-jobi L. (Job's tears) using the chloroform leaves and seed extracts. Methods: The test for antibacterial activity and minimum inhibitory concentration was conducted by the disc diffusion and two-fold dilution method, respectively. In anthelmintic activity test, using Pheretima posthuma model, vermifuge and vermicidal activity were determined by using the chloroform extract at various concentrations. Results: The preliminary phytochemical screening of chloroform extracts of Job's tears leaves indicated the presence of alkaloid, carbohydrate, saponin, glycosides, flavonoids, phenols, tannins and steroids whereas the seeds extract contained glycosides, flavonoids, phenols and steroids, which revealed highest antimicrobial activity against Bacillus cereus and Klebsiella pneumoniae. The lowest minimum inhibitory concentration (12.5–50 mg/mL) was observed against all selected bacteria. On the other hand, it has been observed that chloroform leaves extracts showed shortest time of paralysis (P = 8.17 min) and death (D = 18.23 min) at 100 mg/mL concentration, in comparison with seed extracts (P = 36.83 min and D = 62.33 min) at 100 mg/mL concentration and albendazole (10 mg/mL) used as reference drug (P = 20.17 min and D = 43.67 min), which indicated the plant possessed mild anthelmintic activity. Conclusions: The chloroform extracts (leaves and seeds) showed efficacy for both bacterial infections and parasitic diseases, which ensure the traditional uses of Coix lacryma-jobi L.

关键词： Coix lacryma-jobi L. Phytochemical screening Antibacterial activity Anthelmintic activity

Projection of Future Climate over the Koshi River Basin Based on CMIP5 GCMs

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Atmospheric and Climate Sciences 2016年第2期6卷 190-204页

作者： Rupak Rajbhandari Arun Bhakta Shrestha Santosh Nepal shahriar Wahid Department of Meteorology Tri-Chandra Campus Tribhuvan University Kathmandu Nepal International Centre for Integrated Mountain Development Kathmandu Nepal

This paper analyses the climate projections over the Koshi river basin obtained by applying the delta method to eight CMIP5 GCMs for the RCP4.5 and RCP8.5 scenarios. The GCMs were selected to cover the full envelope of possible future ranges from dry and cold to wet and warm projections. The selected coarse resolution GCM outputs were statistically downscaled to the resolution of the historical climate datasets. The scenarios were developed based on the anomaly between the present reference period (1961-1990) and the future period (2021-2050) to generate transient climate change scenarios for the eight GCMs. The analyses were carried out for the whole basin and three physiographic zones: the trans-Himalaya, high-Himalaya and middle mountains, and southern plains. Future projections show a 14% increase in rainfall during the summer monsoon season by 2050. The increase in rainfall is higher over the mountains than the plains. The meagre amount of rainfall in the winter season is projected to further decrease over both the mountain and southern plains areas of the basin for both RCPs. The basin is likely to experience warming throughout the year, although the increase in winter is likely to be higher. The highest increase in temperature is projected to be over the high Himalayan and middle mountain area, with lower increases over the trans-Himalayan and southern plains areas.

关键词： Climate Projection Climate Change Himalaya Koshi Future Scenario