In this paper, the nonlinear state feedback controller has been developed to control the pressures of the oxygen and the hydrogen in the PEM（Proton Exchange Membrane） fuel cell system. Nonlinear model of the PEM fue...In this paper, the nonlinear state feedback controller has been developed to control the pressures of the oxygen and the hydrogen in the PEM（Proton Exchange Membrane） fuel cell system. Nonlinear model of the PEM fuel cell system was introduced to study the design problems of the state observer and model based controller. A cascade observer using the filtering technique was used to estimate the pressure derivatives of the cathode and the anode in the system. In order to estimate the pressures of the cathode and the anode, the sliding mode observer was designed by using these pressure derivatives. To estimate the oxygen pressure and the hydrogen pressure in the system, the nonlinear state observer was designed by using the cathode pressure estimates and the anode it. These results will be very useful to design the state feedback controller. The validity of the proposed observers and the controller has been investigated by using a Lyapunov＇s stability analysis strategy.展开更多
This study is focused on service quality assessment in the Nigerian ports with Westem and Eastern port zones as study areas. It discovered the level of satisfaction derived by port users by evaluating expectations and...This study is focused on service quality assessment in the Nigerian ports with Westem and Eastern port zones as study areas. It discovered the level of satisfaction derived by port users by evaluating expectations and perceptions at the ports using some selected analysis tools to test raised hypothesis. This evaluation was based on the service quality model as developed by Parasuraman within the core dimensions of Empathy, Responsiveness, Tangibles, Reliability and Assurance. The attributes of expectations and perceptions raised within these dimensions were addressed with two hypotheses. H1 （Hypothesis one） and H2 （Hypothesis two） were addressed with the results of Factor Analysis which identified the significance port users attach to service quality dimensions and their respective attributes.展开更多
文摘In this paper, the nonlinear state feedback controller has been developed to control the pressures of the oxygen and the hydrogen in the PEM（Proton Exchange Membrane） fuel cell system. Nonlinear model of the PEM fuel cell system was introduced to study the design problems of the state observer and model based controller. A cascade observer using the filtering technique was used to estimate the pressure derivatives of the cathode and the anode in the system. In order to estimate the pressures of the cathode and the anode, the sliding mode observer was designed by using these pressure derivatives. To estimate the oxygen pressure and the hydrogen pressure in the system, the nonlinear state observer was designed by using the cathode pressure estimates and the anode it. These results will be very useful to design the state feedback controller. The validity of the proposed observers and the controller has been investigated by using a Lyapunov＇s stability analysis strategy.
文摘This study is focused on service quality assessment in the Nigerian ports with Westem and Eastern port zones as study areas. It discovered the level of satisfaction derived by port users by evaluating expectations and perceptions at the ports using some selected analysis tools to test raised hypothesis. This evaluation was based on the service quality model as developed by Parasuraman within the core dimensions of Empathy, Responsiveness, Tangibles, Reliability and Assurance. The attributes of expectations and perceptions raised within these dimensions were addressed with two hypotheses. H1 （Hypothesis one） and H2 （Hypothesis two） were addressed with the results of Factor Analysis which identified the significance port users attach to service quality dimensions and their respective attributes.
