http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Buffer and Rate Control Based Congestion Avoidance in Wireless Sensor Networks
( Muhammad Mahbub Alam ),( Choong Seon Hong ) 한국정보처리학회 2007 한국정보처리학회 학술대회논문집 Vol.14 No.1
Due to dense deployment and innumerable amount of traffic flow in wireless sensor networks (WSNs), congestion becomes more common phenomenon from simple periodic traffic to unpredictable bursts of messages triggered by external events. Even for simple network topology and periodic traffic, congestion is a likely event due to dynamically time varying wireless channel condition and contention caused due to interference by concurrent transmissions. In this paper, we have proposed three mechanisms: upstream source count and buffer based rate control and snoop based MAC level ACK scheme to avoid congestion. The simulation results show that our proposed mechanism achieves around 80% delivery ratio even under bursty traffic condition.
CRRT: Congestion-Aware and Rate-Controlled Reliable Transport in Wireless Sensor Networks
ALAM, Muhammad Mahbub,HONG, Choong Seon The Institute of Electronics, Information and Comm 2009 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.92 No.1
<P>For successful data collection in wireless sensor networks, it is important to ensure that the required delivery ratio is maintained while keeping a fair rate for every sensor. Furthermore, emerging high-rate applications might require complete reliability and the transfer of large volume of data, where persistent congestion might occur. These requirements demand a complete but efficient solution for data transport in sensor networks which reliably transports data from many sources to one or more sinks, avoids congestion and maintains fairness. In this paper, we propose congestion-aware and rate-controlled reliable transport (CRRT), an efficient and low-overhead data transport mechanism for sensor networks. CRRT uses efficient MAC retransmission to increase one-hop reliability and end-to-end retransmission for loss recovery. It also controls the total rate of the sources centrally, avoids the congestion in the bottleneck based on congestion notifications from intermediate nodes and centrally assigns the rate to the sources based on rate assignment policy of the applications. Performance of CRRT is evaluated in NS-2 and simulation results demonstrate the effectiveness of CRRT.</P>
ALAM, Muhammad Mahbub,HAMID, Md. Abdul,RAZZAQUE, Md. Abdur,HONG, Choong Seon The Institute of Electronics, Information and Comm 2010 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.93 No.6
<P>Broadband wireless access networks are promising technology for providing better end user services. For such networks, designing a scheduling algorithm that fairly allocates the available bandwidth to the end users and maximizes the overall network throughput is a challenging task. In this paper, we develop a centralized fair scheduling algorithm for IEEE 802.16 mesh networks that exploits the <I>spatio-temporal bandwidth reuse</I> to further enhance the network throughput. The proposed mechanism reduces the length of a transmission round by increasing the number of non-contending links that can be scheduled simultaneously. We also propose a greedy algorithm that runs in polynomial time. Performance of the proposed algorithms is evaluated by extensive simulations. Results show that our algorithms achieve higher throughput than that of the existing ones and reduce the computational complexity.</P>
Energy-Aware QoS Provisioning for Wireless Sensor Networks: Analysis and Protocol
Alam, Muhammad Mahbub,Razzaque, Abdur,Mamun-Or-Rashid, Mamun-Or-Rashid,Hong, Choong-Seon The Korea Institute of Information and Commucation 2009 Journal of communications and networks Vol.11 No.4
Wireless sensor networks (WSNs) are envisioned to facilitate information gathering for various applications and depending on the application types they may require certain quality of service (QoS) guarantee for successful and guaranteed event perception. Therefore, QoS in WSNs is an important issue and two most important parameters that hinder the goal of guaranteed event perception are time-sensitive and reliable delivery of gathered information, while a minimum energy consumption is desired. In this paper, we propose an energy-aware, multi-constrained and multipath QoS provisioning mechanism for WSNs based on optimization approach. Hence, a detailed analytical analysis of reliability, delay and energy consumption is presented to formulate the optimization problem in an analytical way. A greedy algorithm is proposed to achieve the desired QoS guarantee while keeping the energy consumption minimum. Also, a simple but efficient retransmission mechanism is proposed to enhance the reliability further, while keeping the delay within delay bound. Simulation results demonstrate the effectiveness of our scheme.
An efficient multi-channel communications scheme for wireless sensor network
Shariful Islam,Muhammad Mahbub Alam,Choong Seon Hong 한국정보과학회 2010 한국정보과학회 학술발표논문집 Vol.37 No.2B
This paper presents a multi-channel communications system for wireless sensor networks (WSNs), referred to as Load-adaptive practical multi-channel communications (LPMC). LPMC estimates the active load of a channel at the sink, and dynamically adds or removes channel based on the estimated load. The nodes in a path use the same channel; and therefore, they do not need to switch channels to receive or forward packets. Furthermore, LPMC updates the routing path to balance the loads of the channels. LPMC is evaluated by simulation in NS-2, and the results demonstrate that it can effectively increase the channel utilization and network throughput, and decrease the delay.
Vertical axis wind turbine types, efficiencies, and structural stability – A Review
Shafiqur Rehman,Muhammad M. Rafique,Md. Mahbub Alam,Luai M. Alhems 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.1
Much advancement has been made in wind power due to modern technological developments. The wind energy technology is the world’s fastest-growing energy option. More power can be generated from wind energy by the use of new design and techniques of wind energy machines. The geographical areas with suitable wind speed are more favorable and preferred for wind power deployment over other sources of energy generation. Today’s wind turbines are mainly the horizontal axis wind turbines (HAWTs) and vertical axis wind turbines (VAWTs). HAWTs are commercially available in various sizes starting from a few kilowatts to multi-megawatts and are suitable for almost all applications, including both onshore and offshore deployment. On the other hand, VAWTs finds their places in small and residential wind applications. The objective of the present work is to review the technological development, available sizes, efficiencies, structural types, and structural stability of VAWTs. Structural stability and efficiencies of the VAWTS are found to be dependent on the structural shape and size.
Wakes of two inline cylinders at a low Reynolds number
Farhan Zafar,Md. Mahbub Alam,Zaka Muhammad,Md. Islam 한국풍공학회 2019 Wind and Structures, An International Journal (WAS Vol.29 No.1
The effect of vortex impingement on the fluid dynamics around a cylinder submerged in the wake of another of different diameters is numerically investigated at a Reynolds number Re = 200. While the diameter (D) of the downstream cylinder is fixed, impinging vortices are produced from the upstream cylinder diameter (d) varied as d/D = 0.24, 0.4, 0.6, 0.8 and 1.0, with a spacing ratio L = 5.5d, where L is the distance between the center of the upstream cylinder to the front stagnation point of the downstream cylinder. Two-dimensional simulations are carried out using the finite volume method. Fluid forces acting on the two cylinders are correlated with impinging vortices, vortex shedding, and wake structure. Different facets of wake formation, wake structure, and flow separation and their connections to fluid forces are discussed.