Diagnosis of rotor faults by fast Fourier transform using an auxiliary winding voltage

<p>Condition monitoring and on-line detection have attracted several researchers in order to carry out an efficient diagnosis of machine failures. Therefore, the detection in early stage avoids system breakdown and reduce the maintenance cost. This paper presents a new diagnosic approach to detect the broken bars and broken end ring faults for a squirrel cage induction machine based on the fast Fourier transform analysis applied on a new signature as the voltage of an auxiliary winding. The auxiliary winding is a small coil inserted between two of the stator phases, the explicit expression of its voltage is presented. The signal is monitored in six faults cases under a different load level, the emergence of the fault frequencies changes for each kind of failure. The successfully simulation results obtained show the effectiveness of this approach.</p>

POST-COVID MANAGEMENT - A PRAGMATIC APPROACH OF PANCHAKARMA THERAPY

Corona is a highly contagious disease that attacks respiratory System breakdown immunity, produce various symptoms and can cause death according to the severity of diseases. In Ayurveda, two types of Vyadhis are men- tioned i.e., Nija / Doshaj Vyadhi and Agantuj Vyadhi. The etiological factors, pathophysiology & symptoms of corona disease can be correlated with Rajyakshyama. In an emergency, condition Panchakarma can be done in any season other than Sadharan Ritu by creating an artificial environment. We aim to improve pulmonary func- tion and to prevent lungs complication like fibrosis and general symptoms like fatigue, insomnia etc. Panchakar- ma is a preventive, promotive well as a curative and cost-effective approach. Keywords: Corona Virus, Panchakarma, Shodhan, Rajyakshama, Post-Covid

Zero-Dynamics Attack on Wind Turbines and Countermeasures Using Generalized Hold and Generalized Sampler

Most wind turbines are monitored and controlled by supervisory control and data acquisition systems that involve remote communication through networks. Despite the flexibility and efficiency that network-based monitoring and control systems bring, these systems are often threatened by cyberattacks. Among the various kinds of cyberattacks, some exploit the system dynamics so that the attack cannot be detected by monitoring system output, the zero-dynamics attack is one of them. This paper confirms that the zero-dynamics attack is fatal to wind turbines and the attack can cause system breakdown. In order to protect the system, we present two defense strategies using a generalized hold and a generalized sampler. These methods have the advantage that the zeros can be placed so that the zero dynamics of the system become stable; as a consequence, the zero-dynamics attack is neutralized. The effects of the countermeasures are validated through numerical simulations and the comparative discussion between two methods is provided.

Design and Test of an Articulation Mechanism for a Morphing Missile Nosecone

This paper covers the design and development of a mechanism to change the angle of an air-to-air missile nosecone relative to the missile body while in flight. A group of senior cadets at the United States Air Force Academy performed the work in fulfillment of requirements for their capstone design project. The Air Force Research Laboratory (AFRL) sponsored the project and provided a set of requirements to guide the design. These requirements include the challenge of torque transfer under significant loading in order to drive the nosecone to a new angle. The report will cover significant design changes from last year’s design and the justification for these changes. A complete sub-system breakdown follows. Finally, the planned testing and evaluation of the design is discussed.

Strategic asset management approach for planning investment in a large-scale irrigation system

Typically, large-scale irrigation systems are built almost entirely in a short time-frame, a significant part of the assets age at the same time and concentrated investment needs for rehabilitation are predictable. This paper focuses on planning these needs in an aggregated way, providing a big picture for the long term investment plan. A methodology for this purpose was developed and applied to a large-scale irrigation utility in Portugal. For such, the following steps were taken: (i) system breakdown by functional areas; (ii) infrastructure components disaggregation; (iii) diagnosis of the reference situation; (iv) evaluation of long-term alternatives for rehabilitation investment planning. The methodology is in line with the IAM approach recommended by IWA and the ISO55000 standards. In this paper, the specificities of this particular application, namely a proposal of irrigation component classes, and the studied alternatives, are presented. As an overall result, it was possible to indicate a path for economic sustainability without committing the infrastructure sustainability: it is based on gradual replacement of the assets reaching their useful life, combined with a constant rehabilitation rate. This paper is a contribution to an AM system for irrigation utilities, so alignment with IAM and the contribution to a broader IAM system is highlighted.

Role of Daegu Medical Association in the infection control of the COVID-19 outbreak

In the mass outbreak of the 2019 novel coronavirus disease pandemic, the Daegu Medical Association managed to control and reduce the number of victims in Daegu successfully. More than 6,000 people were diagnosed in this city within a four-week period, and both medical system breakdown and increasing mortality were imminent. However, we minimized fatalities despite this explosive outbreak in a short time. The collaboration between the Daegu Medical Association and the local government may provide a reference model for overcoming regional outbreaks in the global pandemic era. We can prevent the shortage of medical resources by recruiting volunteer doctors and nurses early through public awareness campaigns. We can overcome the first massive outbreak using several new diagnostic and therapeutic systems such as the drive-through diagnosis system, telephonic counseling for self-quarantine patients by volunteer doctors, and therapeutic living centers. Both sharing the process of collaboration with the public system and summarizing the factors can provide useful information for building effective response systems to cope with the ongoing local outbreak of COVID-19 and any future epidemics of infectious diseases.

Preventive Maintenance Interval Optimization for Continuous Multistate Systems

Preventive maintenance (PM), which is performed periodically on the system to lessen its failing probability, can effectively decrease the loss caused by the system breakdown or the performance degradation. The optimal PM interval has been well studied for both binary-state systems (BSSs) and discrete multistate systems (MSSs). However, in reality, the performance of many systems can change continuously, ranging from complete failure to perfect functioning. Considering such characteristics of systems, two types of performance-based measures, performance availability and probabilistic resilience, are addressed to quantify the system’s behaviour for continuous MSS. A Monte Carlo-based method is given to analyse the performance change process of the system, and an optimization framework is proposed to find the optimal PM interval with the considerations of per-unit-time cost, system breakdown rate, performance availability, and probabilistic resilience. A computer cluster is used as an example to illustrate the effectiveness of our proposed method.