The current Internet inherently has a degree of survivability due to the connection less IP Protocol. Dynamic routing Protocols are designed to react to Faults by changing routes when routers learn about topology changes via routing information updates (e.g., link status advertisements). Loss of Quality of service (QoS) has not been an issue because current Internet traffic is the best-effort. On the contrary, the multi protocol label switching (MPLS) approach is connection-oriented, which implies greater potential vulnerability to Faults. At the same time, MPLS will support integrated services, which are more sensitive to loss of service. Reliability is becoming more important as more users depend on the internet for critical communication services and expect a higher level of performance. Usually, Fault Recovery is attempted first at the lowest layer, and escalated to the next layer if Recovery was unsuccessful or impossible. Fault Recovery capabilities in the MPLS layer are needed as well to decouple MPLS from dependence on physical layer Fault Recovery mechanisms which may differ between networks. This paper proposes an enhanced-scheme for fast rerouting to pre-assigned label-switched paths (LSPs) in case of LSP or link failures. In order to minimize backup resources, it allows possibility of splitting traffic of Faulty LSP onto available alternative LSPs for Fault Recovery. We use Pre-assigned backup LSPs for restoration, when Fault occurs. Total traffic throughput and resource utilization can be maximized if the traffic of Faulty LSP is split over multiple pre-assigned LSPs. In this paper a new approach to providing Fault tolerance in MPLS networks using case-based reasoning (CBR) as a method to find out the amount of traffic forwarded on each pre-assigned LSP based on past experiences of loading process is presented. The pre-assigned LSPs and the percentage of traffic splitting are calculated off-line based on desired QoS and capacity constraints. Also we evaluate the operation of successful decomposition of traffic based on the two mentioned constraints by using CBR, when the number of backup LSPs as a complexity factor increase. In another point of view, in cases when there is no possibility of using the experiences successfully, there would be no other way than using the erroneous unsuccessful experiences. We thus solved our Recovery problem by using, first incorrect databases in our experiments, to moving later towards decreasing the error rate in a gradual manner.

A Fault Tolerant attitude control system has been designed in this paper, which provides abilities of Fault detection, identification and Recovery. For this purpose, nonlinear dynamics of satellite is modeled based on Takagi-Sugeno method, which enables us to extend advantages of linear adaptive observer for nonlinear dynamics of satellite. In the designed adaptive observer, occurrence of Fault in satellite reaction wheels are estimated based on an adaptive law which provides abilities of Fault detection and identification in these actuators. Also, a back stepping feedback linearization control law has been applied for Recovery which uses estimated Fault term provided by adaptive observer as a compensation term in control law. So, bounded error of attitude control has been guaranteed even in Faulty conditions. Finally, Fault detection, identification and Recovery algorithms have been verified by simulation results.

This paper presents the application of automatic under voltage load tripping and switching of shunt reactors as counter measures for Fault induced delayed voltage Recovery (FIDVR). As dynamic behavior of loads has significant impact on simulating FIDVR, proper load modeling is also discussed in this paper. Simulations conducted on actual network show that the proposed load model is effectively able to simulate FIDVR. It also shown that automatic under voltage load shedding and switching of shunt reactors can be used as counter measures for reducing risk of voltage collapse or over voltage conditions that may take place following load tripping caused by FIDVR.

The phenomenon of Fault-Induced Delayed Voltage Recovery (FIDVR) appears in networks with high penetration of induction motor loads because the increase in requested reactive powers of motor loads after clearing the Fault prevents the rapid return of the bus voltage to the pre-Fault level. Load shedding is one of the effective ways to deal with the FIDVR phenomenon, which causes the amount of demand to approach the production of reactive power. In this paper, a wide-area load-shedding method is presented, which performs based on network conditions and loads. Since the introduced indicators for determining the locations and amounts of loads to be shed are based on the values of bus voltages, loads currents, and network impedance matrix; therefore, the proposed method can effectively shed the loads and deal effectively with FIDVR. The voltage estimation process is an important tool to predict the voltages at future moments and is defined based on the modified Gauss-Seidel load flow and the three-order model of the induction motor. This tool enables the proposed method to understand the effect of applying load shedding on voltage Recovery and prevents the application of unnecessary ones.

In areas where the motor load is the predominant load, when the short circuit occurs, the speed of the motors decreases and their power reactive consumption increases, which causes some delays in voltage Recovery after Fault clearance. This delay can cause operation of protection systems and load shedding. Fault-Induced Delayed Voltage Recovery is a phenomenon in which the voltage level does not reach the pre-Fault value immediately after the Fault is cleared. If the Voltage Recovery delay is significant, the wind power plant will be disconnected from the power system, which causes other problems in the power system. The purpose of this paper is to evaluate the effect of different wind power plant controls on voltage Recovery delay. Wind power plant modeling is based on IEC61400-27-1 standard. Also in this paper the effect of location of wind power plant and the ability to Low Voltage Rid Through of wind power plant is considered. All the simulations are performed in DIgSILENT PowerFactory 2021 software.

In this paper we have presented a new design of Fault tolerant comparator with a Fault free hot spare. The aim of this design is to achieve a low overhead of time and area in Fault tolerant comparators. We have used hot standby technique to normal operation of the system without interrupting and dynamic Recovery method in Fault detection and correction. The circuit is divided to smaller modules for ease of testing and one hot spare is used for reconfiguration. Complexity, time and area overhead of designed Fault tolerant comparator are more effective in compared recent methods.

In Air conditioning systems (HVAC), including heating, cooling and ventilation systems use much of the total energy consumed in commercial buildings. Air Handling Unit (AHU) is one of the most important parts in air conditioning systems. In a survey of the UK buildings, data has shown that 25-50% of energy is wasted due to errors in air-conditioned buildings. If these errors are identified in the early stages before unacceptable damage occur and recognized, this range can be reduced to below 15%.Along with the evolution of energy-efficient air conditioning in commercial buildings, a wide range of diagnostics and Fault detection methods continuously increased in the fields of air conditioning. Different techniques are developed using computer with the low installation cost for years to increase real-time detection of errors. In this study, a method of Fault Recovery in temperature sensor of air handling unit has been proposed using simulation of field programing analog array (FPAA) and genetic algorithms as evolutionary algorithms. It is assumed that multiple sensors are working and the output is the average temperature sensors. In Faulty situation, using the Fault Recovery method, the system is able to work properly with one of the sensors. The study consists of two parts, which is a part related to bias, scale and drift Fault detection using time series method, noise Fault detection using the sample standard deviation, constant Fault detection using a voter and the another part is Fault Recovery using FPAA.

In this paper, a new open-switch Fault diagnosis method is proposed for the six-phase AC-DC converter based on the difference between the phase current and the corresponding reference using an adaptive threshold. The open-switch Faults are detected without any additional equipment and complicated calculations, since the proposed Fault detection method is integrated with the controller required signals. The proposed Fault-tolerant technique reduces the value of overcurrent and total harmonic distortion (THD) on the healthy and Faulty phases, by considering the redundancy mode of space vectors in space vector pulse width modulation (SVPWM) and changing the switching signals in Fault regions. This technique is performed without adding any legs, switches or triode for alternating currents (TRIAC) to the circuit. Finally, the proposed Fault-tolerant technique is evaluated by MATLAB simulation and the results show its effectiveness.

The right movement of the trade in the current society needs the government's supervision beside to investors trust to the tradesman.Something that encourages the investors to invest and makes them hopeful is assurance of maintaining the money, hoping to get benefit and banning the trademan to waste it. A trademan who uses the people's trust and gathers their money and does the trade, should exceed taking care of the people's money. Any kind of encroachment or dissipation of the trade man is regarded Fault and leads to trade man to the Fault bankruptcy conviction. The present paper considers the different aspects of Fault bankruptcy.