Sharif Digital Repository

The safe operating condition for the vacuum tubes is very important and critical since they are very expensive and delicate. Providing limited short circuit energy for the vacuum tube and fast transferring from the short circuit to the nominal operation state are absolutely necessary. Extant protection strategies threat the availability of the vacuum tubes. In addition, they cannot completely protect the tube due to the delay of the fault detection system. This article proposes a high voltage (HV) short circuit fault current limiter which can limit the short circuit energy of the system inherently. The proposed structure activates automatically when the current exceeds the predetermined... 

AQM router aims primarily to control the network congestion through marking/dropping packets which are used as congestion feedback in traffic sources to balance their flow rate. However, stabilizing queuing delay and maximizing link utilization have been considered as the main control objectives, especially in media dominated networks. Usually, most of the AQM algorithms are designed for a nominal operating point. However, time-varying nature of network parameters frequently violates their robustness bounds. In this paper, a self-tuning compensated PID controller is proposed to address the time-varying nature of network conditions caused by parameter variations and unresponsive connections.... 

AQM router aims primarily to control the network congestion through marking/dropping packets which are used as congestion feedback in traffic sources to balance their flow rate. However, stabilizing queuing delay and maximizing link utilization have been considered as the main control objectives, especially in media dominated networks. Usually, most of the AQM algorithms are designed for a nominal operating point. However, time-varying nature of network parameters frequently violates their robustness bounds. In this paper, a self-tuning compensated PID controller is proposed to address the time-varying nature of network conditions caused by parameter variations and unresponsive connections.... 

To achieve a good performance of a boiler-turbine unit, dynamic variables such as steam pressure, water level of drum and electric output of turbine must be controlled. In this paper a nonlinear model of the boiler-turbine unit is considered in which the inputs are the valve positions of fuel flow, steam control, and feed-water flow. Using two control methods, feedback linearization and gain scheduling, a PI controller is designed. It is shown that by applying both methods, system goes from one operating point to another with an appropriate specification of time response. Results show that system with a controller designed based on gain scheduling method has a better time response from a...