DSpace Repository :: Browsing by Author "Abdul Aziz Bhatti"

Browsing by Author "Abdul Aziz Bhatti"

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Characterization of biodiesel samples produced from fresh and waste vegetable oils to evaluate their feasibility for power generation
(2013) Mehwish Inam; Ayesha Mohy-Ud-Din; Abdul Aziz Bhatti; Mashood Nasir
The purpose of this paper is to design a system in which the biodiesel prepared from fresh and waste vegetable oil can be converted into useful power output. It is intended that this biodiesel produced may ultimately be a fuel source for the power generation from the generators. The optimal conditions of temperatures and concentration have also been discussed and the criteria to select these parameters have been evaluated.
Comparative analysis on the efficiency and engine properties by using biodiesel and fossil diesel
(2013) Ayesha Mohy-Ud-Din; Mehwish Inam; Abdul Aziz Bhatti; Mashood Nasir
The increase in the demand and prices of petroleum products as well as the environmental concerns resulting from the burning of fossil fuels in electricity production has resulted in focusing on the use of environmental friendly renewable alternative energy resources, like solar, hydro, tidal, wind, geothermal and biomass energy. There has been plenty of research done so far on engine performance and biodiesel production. Biodiesel was produced from fresh oil (BFO) and waste vegetable oil (BWO) on using biofuels for electricity generation. The engine performance tests were conducted with petroleum diesel and biodiesel samples at different loads and variable speeds. On comparing the electrical efficiency of generator and brake specific fuel consumption(BSFC) values, it was observed that less fuel is required for same power output when BFO (0.19kg/kWh) and BWO (0.18kg/kWh) were used in place of petroleum diesel. Moreover, an increase in BSFC values of BFO and BWO as compare to petroleum diesel at different speeds leads to the same interpretation. Higher efficiency and lower BSFC values of BFO (Efficiency: 43.25%; BSFC: 0.19 kg/kWhr) and BWO (Efficiency:41.34%;BSFC:0.2kg/kWh) due to complete combustion and reduction in calorific value of the fuel. In case of BWO, the operational efficiency (41.34%) was found less than the diesel-fueled condition.
Critical analysis of hopfield's neural network model and heuristic algorithm for shortest path computation for routing in computer networks
(IEEE, 2012) Farah Sarwar; Abdul Aziz Bhatti
Shortest path routing and its computation is a crucial point in computer networks, and has significant impact on overall network's performance. Being an issue of salient importance, many algorithms were proposed for shortest path computation and are still under research for more enhancements. Hopfield proposed a neural network based architecture for such optimization problems. Mehmet and Park Keum suggested improved energy functions for this neural network to implement it for routing in computer networks. A * search algorithm is a heuristic based approach, with the properties of Dijikstra algorithm and is used for same purpose. Performances of both approaches are compared and results are analyzed.
Critical analysis of hopfield's neural network model for tsp and its comparison with heuristic algorithm for shortest path computation
(IEEE, 2012) Farah Sarwar; Abdul Aziz Bhatti
For shortest path computation, Travelling-Salesman problem is NP-complete and is among the intensively studied optimization problems. Hopfield and Tank's proposed neural network based approach, for solving TSP, is discussed. Since original Hopfield's model suffers from some limitations as the number of cities increase, some modifications are discussed for better performance. With the increase in the number of cities, the best solutions provided by original Hopfield's neural network were considered to be far away from those provided by Lin and Kernighan using Heuristic algorithm. Results of both approaches are compared for different number of cities and are analyzed properly
Dynamic modeling and characterization of a proton exchange membrane fuel cell
(2012) Muhammad Salik; Abdul Aziz Bhatti; Mashood Nasir
This paper presents the equivalent dynamic model accounting for the thermodynamic and electrochemical characteristics of Proton Exchange Membrane Fuel Cell (PEMFC). The proposed model was implemented in MATLAB/SIMULINK environment. The effects of temperature variations, fluid flow changes and capacitance due to double layer charging were incorporated in this model. The proposed model responses are in good correspondence with the published experimental results. It also predicts the temperature and pressure response of the PEMFC. The model formulated here would be helpful for the optimal prediction of characteristics and dynamic operation of a fuel cell stack.
Dynamic modeling and grid integration of a solid oxide fuel cell
(University of Engineering and Technology, 2013) Muhammad Salik; Syed Mohsin Ali; Abdul Aziz Bhatti; Mashood Nasir
This article presents an equivalent dynamic model of a Solid Oxide Fuel Cell (SOFC) integrated with utility grid. The proposed dynamic model accounts for the electrochemical and thermodynamic characteristics of SOFC. Effects of temperature variations and fluid flow changes are incorporated in the model. Voltage drops inside a fuel cell are also modeled. This proposed model is further integrated with the utility grid with help of power conditioning unit (PCU). PCU consists of a DC-DC Boost converter and a 3-phase voltage source inverter. The output of 3-phase inverter is fed to the grid with the use of AC link integration. Complete model is formulated in MATLAB-SIMULINK environment. Simulation results clearly depict the behavior of SOFC and also show that SOFC is a potential source for distributed generation purpose. The proposed model formulated here would be helpful for the optimal prediction of characteristics and dynamic operation of SOFC based power plants.
Formulation of an electric equivalent circuit of pemfc and its behavioral studies under steady state and transient conditions
(2012) Asfa Javed; Abdul Aziz Bhatti; Mashood Nasir
In this paper electric equivalence model is formulated for the constructional and operational features of a Polymer Electrolyte Membrane Fuel Cell (PEMFC). The proposed model is capable of explaining the behavior of PEMFC in both steady state and transient modes of operation.. For the efficient designing of fuel cell related applications it is highly desirable to model the electrical output of fuel cell in terms of its internal electrochemical dynamics. The proposed model includes the phenomenon like activation polarization, ohmic polarization and mass transport effect. An analogical electrical circuit is formulated by taking these phenomena into considerations. Within acceptable limits, the effects of load variation on output voltage, efficiency and fuel flow demands are also investigated. The static and dynamic characteristics obtained through simulations are compared with the standard available data. Simulation results show that the model can be used in PEM fuel cell distributed generation related control studies.
Impact of extended starobinsky model on evolution of anisotropic, vorticity-free axially symmetric sources
(Journal of Cosmology and Astroparticle Physics, 2015) Ifra Noureen; Abdul Aziz Bhatti; M. Zubair
We study the implications of Rn extension of Starobinsky model on dynamical instability of Vorticity-free axially symmetric gravitating body. The matter distribution is considered to be anisotropic for which modified field equations are formed in context of f(R) gravity. In order to achieve the collapse equation, we make use of the dynamical equations, extracted from linearly perturbed contracted Bianchi identities. The collapse equation carries adiabatic index 􀀀 in terms of usual and dark source components, defining the range of stability/insatbility in Newtonian (N) and post-Newtonian (pN) eras. It is found that supersymmetric supergravity f(R) model represents the more practical substitute of higher order curvature corrections.
A microcomputer-based methodology for distance protection on long uhv transmission lines using symmetrical components
(2012) Abdul Aziz Bhatti; Mashood Nasir
This paper proposes a methodology for the long UHV transmission lines distance protection using microprocessor for fault detection, isolation and auto reclosing processes. In the present era, with the development of microprocessor technology, their extra efficient controlling and computing abilities can be utilized in distance relaying for efficient computing of fault distance and the type of fault occurred on the transmission line. Using Symmetrical component theory a single performance equation is developed that will encounter all type of faults on transmission lines regardless of the nature of the fault. Microprocessor will process on these sequence components to estimate the type of fault and the distance of fault from the relay. ETAP is used as a simulation tool to obtain the desired results. Although the formulation described here is independent of hardware yet it provides a complete analytical base for distance protection and is analyzed for different types of fault conditions using simulation tools.
Microcontroller based implementation of fuel cell and battery integrated hybrid power source
(2012) Fahad Ali; Syed Mohsin Ali; Abdul Aziz Bhatti; Mashood Nasir
This paper presents the implementation of a digitally controlled hybrid power source system, composed of fuel cell and battery. Use of individual fuel cell stacks as a power source, encounters many problems in achieving the desired load characteristics. A battery integrated, digitally controlled hybrid system is proposed for high pulse requirements. The proposed hybrid power source fulfils these peak demands with efficient flow of energy as compared to individual operations of fuel cell or battery system. A dc/dc converter is applied which provides an optimal control of power flow among fuel cell, battery and load. The proposed system efficiently overcomes the electrochemical constraints like over current, battery leakage current, and over and under voltage dips. By formulation of an intelligent algorithm and incorporating a digital technology (AVR Microcontroller), an efficient control is achieved over fuel cell current limit, battery charge, voltage and current. The hybrid power source is tested and analyzed by carrying out simulations using MATLAB simulink. Along with the attainment of desired complex load profiles, the proposed design can also be used for power enhancement and optimization for different capacities.
Model based analysis and efficient control system design for fuel cell power system
(2012) Mashood Nasir; Abdul Aziz Bhatti; Waqas Tariq Toor
In this research work a Fuel cell based power system is explicitly modeled and analyzed under the various possible operating conditions. In order to ensure a reliable, efficient, durable and cost effective operation, a control system based on the management of air and fuel flow regulations can be designed. Fuel cell systems produce clean energy and they have got higher energy conversion efficiencies as compared to Internal Combustion Engines based power plants. In order to make this technology economically viable, feed of the air and fuel, pressure regulations, flow rates and the heat produced must be optimally controlled. Oxygen depletion, during the transient reactions, is the major cause of low performance and subsequent deteriorations. In order to overcome the stated limitations, internal subsystem reactions are modeled deliberately and examined carefully. Based on the mathematical deductions and feedback control techniques, optimal pressures and flow rates for hydrogen and oxygen are selected. Breath control unit can be efficiently controlled by using this model to avoid degradation. The output voltage model is also delineated in terms of internal electrochemical dynamics to confirm the maximum power gain by the selected parameters. Results are also verified using MATLAB/ Simulink tool. The Proposed methodology is equally valid for both Polymer Electrolyte Membrane and Solid Oxide Fuel Cells based power systems with some modifications.
Model Formulation and design of an efficient control algorithm for fuel cell power system
(4th International Conference on Power Engineering, Energy and Electrical Drives Istanbul, Turkey, 2013) Mashood Nasir; Abdul Aziz Bhatti; Waqas Tariq Toor
In this research work a Fuel cell based power system is explicitly modeled and analyzed under the various possible operating conditions. In order to ensure a reliable, efficient, durable and cost effective operation, a control system based on the management of air and fuel flow regulations can be designed. Fuel cell systems produce clean energy and they have got higher energy conversion efficiencies as compared to Internal Combustion Engines based power plants. In order to make this technology economically viable, feed of the air and fuel, pressure regulations, flow rates and the heat produced must be optimally controlled. Oxygen depletion, during the transient reactions is the major cause of low performance and subsequent deteriorations. In order to overcome the stated limitations, internal subsystem reactions are modeled deliberately and examined carefully. Based on the mathematical deductions and feedback control techniques, optimal pressures and flow rates for hydrogen and oxygen are selected. Breath control unit can be efficiently controlled by using this model to avoid degradation. The output voltage model is also delineated in terms of internal electrochemical dynamics to confirm the maximum power gain by the selected parameters. Results are also verified using MATLAB/ Simulink tool. The Proposed methodology is equally valid for both Polymer Electrolyte Membrane and Solid Oxide Fuel Cells based power systems with some modifications.
Neural network based optimal placement of base stations in three dimensional plane
(IEEE, 2012) Waqas Tariq Toor; Abdul Aziz Bhatti
The paper proposes a solution to the problem of optimal placement of base stations, with effective utilization of resources. First, it analyzes the placement of base stations in x-y plane. Then this analysis is extended to 3-dimenional system, by including the z coordinate for representing height. This analysis optimizing these xy coordinate values as well as value of z coordinate, as height also contributes in covering the area of base stations. The Hopfield neural network model is used to find the solution to our problem.. Neural network and all parameters, i.e. x, y and z coordinates are used to maximize the coverage area and to minimize the interference, as optimal placement of base stations refer to these two points. In wireless communication system, the placement of base stations requires work force and costly equipments like GPS etc. resulting in loss of time and money. However, with proposed strategy only a laptop or desktop PC will be required to compute the positions of base stations within very less time. The energy equations are developed for our network which shows that the solution resulting from these equations is stable. The computer simulations and graphs are also included to validate the results.
Neural networks based physical cell identity: assignment for self organized 3gpp long term evolution
(IEEE, 2012) Muhammad Basit Shahab; Abdul Aziz Bhatti
This paper proposes neural networks based graph coloring technique to assign Physical Cell Identities throughout the self organized 3GPP Long Term Evolution Networks. PCIs are allocated such that no two cells in the vicinity of each other or with a common neighbor get the same identity. Efficiency of proposed methodology resides in the fact that minimum number of identities is utilized in the network wise assignment. Simulations are performed on a very large scale network, where initially all the cells are without any PCIs assigned. Results of simulations are demonstrated to analyze the performance of the proposed technique
Reduced order multiport parallel and multidirectional neural associative memories
(Biological Cybernetics, 2009) Abdul Aziz Bhatti
This paper proposes multiport parallel and multidirectional intraconnected associative memories of outer product type with reduced interconnections. Some new reduced order memory architectures such as k-directional and k-port parallel memories are suggested. These architectures are, also, very suitable for implementation of spatiotemporal sequences and multiassociative memories. It is shown that in the proposed memory architectures, a substational reduction in interconnections is achieved if the actual length of original N-bit long vectors is subdivided into k sublengths. Using these sublengths, submemory matrices, Ts or Ws , are computed, which are then intraconnected to form k-port parallel or k-directional memories. The subdivisions of N-bit long vectors into k sublengths save (k−1)×100 k % of interconnections. It is shown, by means of an example, that more than 80% reduction in interconnections is achieved. Minimum limit in bits on k as well as maximum limit on subdivisions in k is determined. The topologies of reduced interconnectivity developed in this paper are symmetric in structure and can be used to scale up to larger systems. The underlying principal of construction, storage and retrieval processes of such associative memories has been analyzed. The effect of complexity of different levels of reduced interconnectivity on the quality of retrieval, signal to noise ratio, and storage capacity has been investigated. The model possesses analogies to biological neural structures and digital parallel port memories commonly used in parallel and multiprocessing systems.
Transient and steady state solution of n-dimensional coupled networks and development of equivalent pi and t matrix networks with distributed parameters
(4th International Conference on Power Engineering, Energy and Electrical Drives Istanbul, Turkey, 2013) Abdul Aziz Bhatti
This paper proposes a new computer based method for transient and steady state solution of n-dimensional coupled transmission line networks or communication circuits with distributed parameters. In this method, a novel approach has been developed for formulating and computing the ndimensional generalized ABCD parameter matrices, as well as for developing and solving the equivalent n-dimensional coupled T and Pi networks with distributed parameters. The proposed method uses Cayley-Hamilton’s theorem to compute the hyperbolic N-dimensional generalized ABCD parameter matrices with finite terms which are fundamental to the solution and development of the equivalent N-dimensional T and Pi matrix networks. The square root function of the complex matrix [W] is also computed with finite terms. As a result, truncation of matrices is eliminated, and an improved closed from solution is achieved. The method is straight forward, computationally efficient, and neither it involves the use of eigenvector based modal transformations necessary for diagonalization of parameter matrices nor it requires the evaluation of infinite series of hyperbolic functions with n-dimensional matrices as their arguments, and is extremely useful in the steady state and transient analysis of n-dimensional, unbalanced, coupled systems with distributed parameters. The method is extremely useful in the fault analysis of n-dimensional unbalanced coupled systems with distributed parameters. To date no such method is reported in the literature.

Browsing by Author "Abdul Aziz Bhatti"

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