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Multiobjective Optimization of a Micromixer with Convergent–Divergent Sinusoidal Walls
Afzal, Arshad,Kim, Kwang-Yong Taylor Francis 2015 Chemical engineering communications Vol.202 No.10
<P>A multiobjective optimization of a micromixer with convergent-divergent sinusoidal walls has been conducted using flow and mixing analyses, surrogate modeling, and multiobjective genetic algorithm. The ratios of amplitude to wavelength of the sinusoidal walls, throat width to depth of the convergent-divergent sections, and diameter of the inner circular wall to wavelength were chosen as the design variables for optimization. The full-factorial method was used to discretize the design space. The mixing index and nondimensional pressure loss were selected as objective functions. Radial basis neural network functions were used to train the objective functions. The optimization was carried out at a Reynolds number of 30. A concave Pareto-optimal front representing the trade-off between the two objective functions was obtained. The analysis of representative designs along the Pareto-optimal front showed significant variation in the ratio of throat width to depth of the convergent-divergent sections, whereas the ratio of amplitude to wavelength of the sinusoidal walls maintained a nearly constant value. The concept of mixing effectiveness was used to select the most efficient designs considering both the mixing performance and pressure drop.</P>
Blue-Shifted Rogue Waves Generation in Normal Dispersion Fiber Laser
Afzal, Muhammad Imran,Alameh, Kamal,Yong Tak Lee IEEE 2015 IEEE photonics technology letters Vol.27 No.22
<P>In the presence of noise in normal dispersion fiber mode-locked lasers, dissipative resonance disappears, which leads to instability of spectral broadening and makes the asymptotic accumulation of energy impossible. We experimentally generate dissipative soliton molecules-like spectral peaks and rogue waves in the frequency domain in a self-mode-locked fiber laser. Due to noise in the initial triangular-shaped mode locked wave, these molecules are arranged in the form of lobes on the longer wavelength side, thus forming three virtual groups of soliton molecules. Further dissipative accumulation of power in the mode-locked wave ultimately leads to the formation of a blue-shifted group of three rogue waves, due to the effective fusion of adjacent soliton molecules. This is the first report of an experimental observation of blue-shifted and three rogue waves in a single experiment. The results have far reaching implications for experimentation with soliton collisions, optical rogue waves, and understanding of hydrodynamics.</P>
Efficient and Reliable MPEG-4 Multicast MAC Protocol for Wireless Networks
Afzal, Muhammad Khalil,Kim, Byung-Seo,Kim, Sung Won IEEE 2015 IEEE Transactions on Vehicular Technology VT Vol.64 No.3
<P>Multicasting is the transmission of data to a group of nodes identified by a single destination address. Furthermore, multicasting is considered as an appropriate transmission method for multimedia services. Multimedia applications are expected to become more prevalent over mobile ad hoc networks in the near future. Therefore, achieving reliability in multimedia communications is an important task. Video compression technologies are about reducing and removing redundant video data so that a digital video file can be effectively sent over a network. With modern compression standards, such as Moving Picture Expert Group 2 (MPEG-2), MPEG-4, and H.264, which is also known as advanced video coding MPEG-4 part 10, losses of different frames have different impacts on video quality. In this paper, we propose a leader-based reliable multicast medium-access control layer protocol for multimedia applications to enhance video quality. We present a Markov chain model and numerical formulation of our proposed protocol. Simulation results show that our proposed method is better than other protocols in terms of the number of decodable frames, peak signal-to-noise ratio (PSNR), and video quality.</P>
Afzal, Muhammad Raheel,Oh, Min-Kyun,Lee, Chang-Hee,Park, Young Sook,Yoon, Jungwon Hindawi Publishing Corporation 2015 BioMed research international Vol.2015 No.-
<P>Gait asymmetry caused by hemiparesis results in reduced gait efficiency and reduced activity levels. In this paper, a portable rehabilitation device is proposed that can serve as a tool in diagnosing gait abnormalities in individuals with stroke and has the capability of providing vibration feedback to help compensate for the asymmetric gait. Force-sensitive resistor (FSR) based insoles are used to detect ground contact and estimate stance time. A controller (Arduino) provides different vibration feedback based on the gait phase measurement. It also allows wireless interaction with a personal computer (PC) workstation using the XBee transceiver module, featuring data logging capabilities for subsequent analysis. Walking trials conducted with healthy young subjects allowed us to observe that the system can influence abnormality in the gait. The results of trials showed that a vibration cue based on temporal information was more effective than intensity information. With clinical experiments conducted for individuals with stroke, significant improvement in gait symmetry was observed with minimal disturbance caused to the balance and gait speed as an effect of the biofeedback. Future studies of the long-term rehabilitation effects of the proposed system and further improvements to the system will result in an inexpensive, easy-to-use, and effective rehabilitation device.</P>
A Sampling Plan for the Selection of Supplier using Process Yield Index based on Linear Profiles
Afzal, Kalsoom,Aslam, Muhammad,Jun, Chi-Hyuck,Ahmad, Liaquat Korean Institute of Industrial Engineers 2017 Industrial Engineeering & Management Systems Vol.16 No.2
In this article, a multiple dependent state repetitive (MDSR) sampling plan is developed to choose a more capable process by comparing two suppliers' processes. The proposed MDSR plan is based on the ratio of two process yield indices based on the estimated linear profiles. The linear profile for both processes is estimated by a regression model with a single explanatory variable having the specified number of levels. The operating characteristic function of the proposed plan will be derived. The plan parameters related to the decision rule as well as the sample size are determined by minimizing the average sample number while satisfying the producer's and the consumer's risks.
GIS Exploitation for New Facility Location Decisions- A Logistics Perspective
Afzal Mohammad Khaled,Yong Jin Kim 인하대학교 정석물류통상연구원 2012 JOURNAL OF INTERNATIONAL LOGISTICS AND TRADE Vol.10 No.1
Logistical facility location decisions can make a crucial difference in the success or failure of a company. Geographical Information Systems (GIS) have recently become a very popular decision support system to help deal with facility location problems. However, until recently, GIS methodologies have not been fully embraced as a way to deal with new facility location problems in business logistics. This research makes a framework for categorizing empirical facility location problems based on the intensity of the involvement of GIS methodologies in decision making. This framework was built by analyzing facility location models and GIS methodologies. The research results revealed the depth of the embracement of GIS methodologies in logistics for determining new facility location decisions. In the new facility location decisions, spatial data inputs are almost always coupled with the visualization of the problems and solutions. However, the usage of GIS capability solely (i.e. suitability analysis) for problem solving has not been embraced at the same level. In most cases, the suitability analysis is used together with special optimization models for choosing among the multiple alternatives.