Designing power system stabilizer for multimachine power system using neuro-fuzzy algorithm

This paper describes a design procedure for a fuzzy logic based power system stabilizer (FLPSS) and adaptive neuro-fuzzy inference system (ANFIS) and investigates their robustness for a multi-machine power system. Speed deviation of a machine and its derivative are chosen as the input signals to the FLPSS. A four-machine and a two-area power system is used as the case study. Computer simulations for the test system subjected to transient disturbances i.e. a three phase fault, were carried out and the results showed that the proposed controller is able to prove its effectiveness and improve the system damping when compared to a conventional lead-lag based power system stabilizer controller

A Ka-Band Horn Antenna Excited With Parasitic Dielectric Resonator Antenna

A pyramidal horn antenna excited with parasitic dielectric resonator (DR) antenna for use at Ka-band frequencies is proposed

Experimental Design of Electrocoagulation and Magnetic Technology for Enhancing Suspended Solids Removal From Synthetic Wastewater

Design of experiments (DOE) is one of the statistical method that is used as a tool to enhance and improve experimental quality. The changes to the variables of a process or system is supposed to give the optimal result (response) and quite satisfactory. Experimental design can defined as a test or series of test series by varying the input variables (factors) of a process that can known to cause changes in output (response). This paper presents the results of experimental design of wastewater treatment by electrocoagulation (EC) technique. A combined magnet and electrocoagulation (EC) technology were designed to increase settling velocity and to enhance suspended solid removal efficiencies from wastewater samples. In this experiment, a synthetic wastewater samples were prepared by mixing 700 mg of the milk powder in one litre of water and treated by using an acidic buffer solution. The monopolar iron (Fe) plate anodes and cathodes were employed as electrodes. Direct current was varied in a range of between 0.5 and 1.1 A, and flowrate in a range of between 1.00 to 3.50 mL/s. One permanent magnets namely AlNiCo with a magnetic strength of 0.16T was used in this experiment. The results show that the magnetic field and the flowrate have major influences on suspended solids removal. The efficiency removals of suspended solids, turbidity and COD removal efficiencies at optimum conditions were found to be more than 85%, 95%, and 75%, respectively

Fuzzy logic control for mobile service systems with limited resources

It is common to control systems or plants through changing the values of their inputs in continuous or small discrete steps to achieve gradual change of the performance of the plant under control. However, when changing the inputs can only be achieved in large discrete values, problems arise on achieving stability of the plant under control as such large discrete changes in inputs cause large overshoots and oscillation at the outputs. More difficulties arise when multiple plants are competing simultaneously for limited resources of such large discrete values. This paper describes an approach for controlling such plants. The case study presented is to control a proposed system of mobile service units (MSUs) to be used in a mega-event, the Hajj, where different locations/zones will be competing simultaneously for a limited number of MSUs in order to provide adequate services for their continuously changing number of visitors. These MSUs are of high discrete values such that their provision or removal generates a significant change in the performance of the system. Fuzzy logic controllers (FLCs), representing each zone, are developed for issuing requests for MSUs based on their local situations. These requests are evaluated by the control centre using other sets of FLCs to consider global situations. An algorithm is used to respond to these evaluated requests according to their relative importance and issues orders to MSUs to move to the right zone at the right time to provide the appropriate amount of service for the existing number of visitors or what can be called 'just-in-time MSUs' (JIT-MSUs). Simulation results show that such a system can be controlled using the approach suggested by this paper and the response of the system varies with the values of its discrete inputs. Some conclusions and recommendations are drawn for the appropriate discrete input values and their control settings. The procedure for evaluating the different simulation runs for the different control settings is also presented

A novel Multi-permittivity Cylindrical Dielectric Resonator Antenna for Wideband Applications

In this paper, a novel multi-permittivity cylindrical dielectric resonator antenna for wideband application is presented. The multi-permittivity cylinder is formed by combining two different permittivity material sectors in such a way that each sector (with constant permittivity) is 90 degree apart. A direct microstrip line coupling terminated with T-stub at the open end is used to excite the multi-permittivity cylindrical dielectric resonator. The angular position of the multi sector dielectric resonator with respect to the longitudinal axis of the microstrip line and length of the additional strip at the open end of the feeding circuit is key parameters for wideband operation of the antenna. By optimizing all parameters of the proposed antenna, wideband impedance bandwidth of 56% (12.1 GHz - 21.65 GHz) is achieved. The average gain of the antenna throughout the bandwidth is 5.9 dB with good radiation properties in both E-plane and H-plane. A well matched simulation and experimental results show that the antenna is suitable for wideband applications

Improving IEEE 802.11 to Support Quality of Service in Wireless Networks

This paper investigates and describes the Quality of Services (QoS) provisioning techniques for IEEE 802.11 based networks, focusing on the Distributed Coordination Function (DCF). This paper propose better techniques to provide QoS by assigning new parameters to the DCF access method, involving the DCF Interframe Space (DIFS), backoff time and the maximum data packet size to high priority nodes, which will distinguish the high priority traffic from the low priority traffic to support QoS. A simulation is done using Network Simulator 2 (NS-2) and the expected output is then presented

A Novel Approach on Teaching Network Security for ICT Courses

This paper discusses a curriculum approach that will give emphasis on practical sessions of teaching network security subjects in information and communication technology courses. As we are well aware, the need to use a practice and application oriented approach in education is paramount [1]. Research on active learning and cooperative groups showed that students grasps and have more tendency towards obtaining and realizing soft skills like leadership, communication and team work as opposed to learning using the traditional theory and exam based method. While this teaching and learning paradigm is relatively new in Malaysia, it has been practiced widely in the West. This paper examines a particular approach whereby students learning wireless security are divided into small manageable groups consisting of black hat and white hat team. The former will try to find and expose vulnerabilities in a wireless network while the latter will try to prevent such attacks on their wireless networks using hardware, software, design and enforcement of security policy and etc. This paper will try to demonstrate whether this approach will result in a more fruitful outcome in terms of students concept and theory understandings and motivation to learn

Achieving Stable Throughput to Support QoS in IEEE 802.11 Wireless Networks

This paper investigates and describes a new provisioning technique for IEEE 802.11 based networks, focusing on the ad-hoc Distributed Coordination Function (DCF) to redefine stability of the network throughput to support QoS. This paper propose better techniques to achieve stable throughput in Wireless LAN networks by assigning new values to the Contention Window to high priority traffics which will guarantee better throughput to the selected network traffic. A simulation is done using Network Simulator 2 (NS-2) and findings are then presented. Results showed that stable throughput can be achieved to provide better traffic flows especially for real-time traffic and multimedia applications

Improving IEEE 802.11g Mac to Support Quality of Service for Multimedia Applications in Wireless Networks

This paper paper investigates, describes and propose better techniques to provide QoS by assigning new metrics to the DCF access method, involving the DCF Interframe Space (DIFS), Contention Window values and the maximum data packet size to high priority nodes, which will bias towards high priority multimedia traffic to support QoS. A simulation is done using Network Simulator 2 (NS-2) and comparisons were made between different sets of network simulation scenarios. Improvements on throughput, delay and jitter can clearly be seen and further analysis is then presented