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Drag reduction on a square cylinder using multiple detached control cylinders
Shams-Ul-Islam,Raheela Manzoor,Umar Khan,Ghazala Nazeer,Sehrish Hassan 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.5
A two-dimensional numerical simulation for flow over a main cylinder with detached controlling cylinders placed at differentposition is performed through Lattice Boltzmann Method (LBM) to reduce fluid forces. For this study the Reynolds number (Re) isfixed at 160, while gap ratio between these cylinders are taken in the range from 0.5 to 8. The results yield in terms of vorticity, timeseriesanalysis of drag and lift coefficients, power spectra of lift coefficients and force statistics. Depending on gap spacing, flow isclassified into four different patterns, called as (i) single blender body, (ii) shear layer reattachment, (iii) fully developed flow and (iv)vortex suppression fully developed flow patterns. In comparison of all three configurations, it is examined that the maximum value ofCdmean and Strouhal number occurs for downstream configuration. Whereas, upstream and dual configuration play a vital role toreduce forces and to suppress vortex shedding. The maximum reduction found in mean drag coefficient for downstream, upstreamand for dual configuration is 8.3%, 51% and 50.8%, respectively. Whereas, the reduction in Clrms values for all three configurationsis 84.4%, 58.2% and 86.4% , respectively.
ON ω-CHEBYSHEV SUBSPACES IN BANACH SPACES
Shams, Maram,Mazaheri, Hamid,Vaezpour, Sayed Mansour Korean Mathematical Society 2008 대한수학회보 Vol.45 No.3
The purpose of this paper is to introduce and discuss the concept of ${\omega}$-Chebyshev subspaces in Banach spaces. The concept of quasi Chebyshev in Banach space is defined. We show that ${\omega}$-Chebyshevity of subspaces are a new class in approximation theory. In this paper, also we consider orthogonality in normed spaces.
Shams-Ul-Islam,Hamid Rahman,Waqas Sarwar Abbasi,Uzma Noreen,Aftab Khan 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.12
A numerical study for flow past a square cylinder in a two-dimensional channel with a detached flat plate is investigated in this paper. A flat plate is detached downstream in order to control the flow around and behind the square cylinder. Fluid forces acting on the squarecylinder, wake structure mechanism and vortex shedding frequency are presented systematically for different Reynolds numbers andspacing ratios. Effects of Reynolds numbers upon physical parameters are also studied. Variation of Reynolds number is from 75 to 200,based on the incoming flow velocity and width of cylinder. The lattice Boltzmann method is used for this numerical investigation. In thisstudy, we choose three different spacing ratios namely closely, moderately and widely. Numerical studies show that some physical parameterssignificantly reduced by the detached flat plate for closely spacing ratio. The results which we obtained in this investigation areauthentic in the sense that some other experimental observations by different authors can be deduced from our results.
Mobile wireless ad-hoc network routing protocols comparison for real-time military application
Shams Al Ajraw,Bang Tran 대한공간정보학회 2024 Spatial Information Research Vol.32 No.1
Mobile wireless Ad-hoc has become more popular because it forms quickly, has an easy setup, and has easy extensibility. The mobile ad-hoc wireless networks can be further classified according to their applications as follows: Regular user ad-hoc networks are commercial communication that applies to vehicles to help avoid collisions and accidents and live connections to transfer data from car to car. Another application is disaster rescue ad-hoc networking, usually used when a normal infrastructure network is destroyed by storms, earthquakes, tsunamis, etc. Nowadays, a lot of applications, particularly those related to the military and emergency situations, rely on mobile ad hoc wireless networks, where security needs are more challenging to provide than in regular networks. We present the tactical network needs for the military. This platform attempts to assess the possible advantages of mobile ad hoc networks in tactical military applications. This work proposes route discovery using reactive (on-demand) routing protocols where nodes need to just transfer data. This eliminates the requirement for each node to store and maintain any routing tables. This study presents and contrasts the benefits and drawbacks of two fundamental mobile ad hoc routing systems (AODV and DSR). Both protocols are On-Demand routing techniques, and when data needs to be sent, the discovery phase begins. The results of the simulation, the AODV routing approach outperforms the DSV routing method under identical simulated conditions. Mobile wireless Ad-hoc has become more popular because it forms quickly, has an easy setup, and has easy extensibility. The mobile ad-hoc wireless networks can be further classified according to their applications as follows: Regular user ad-hoc networks are commercial communication that applies to vehicles to help avoid collisions and accidents and live connections to transfer data from car to car. Another application is disaster rescue ad-hoc networking, usually used when a normal infrastructure network is destroyed by storms, earthquakes, tsunamis, etc. Nowadays, a lot of applications, particularly those related to the military and emergency situations, rely on mobile ad hoc wireless networks, where security needs are more challenging to provide than in regular networks. We present the tactical network needs for the military. This platform attempts to assess the possible advantages of mobile ad hoc networks in tactical military applications. This work proposes route discovery using reactive (on-demand) routing protocols where nodes need to just transfer data. This eliminates the requirement for each node to store and maintain any routing tables. This study presents and contrasts the benefits and drawbacks of two fundamental mobile ad hoc routing systems (AODV and DSR). Both protocols are OnDemand routing techniques, and when data needs to be sent, the discovery phase begins. The results of the simulation, the AODV routing approach outperforms the DSV routing method under identical simulated conditions.
The Impact of Terrorism on Cycle Times in International Supply Chains
Shams Rahman,Christopher Findlay Jungseok Research Institute of International Logis 2003 JOURNAL OF INTERNATIONAL LOGISTICS AND TRADE Vol.1 No.1
Supply chains in East Asia are being redesigned following the reassessment of the risk of disruption through terrorist attacks. The nature of these risks and of the? costs of the private sector responses is reviewed. The research available suggests the costs incurred are substantial. Government regulation applied to security matters also applies within supply chains. It too has been redesigned in response to the change in the risk of terrorist attacks. Examples of its impacts, and its costs and benefit, are presented. Relevant empirical work remains scarce, but principles for government's role can be identified.