Intelligent Fault Inference of Inverters Based on a Three-Layer Bayesian Network

A three-layer Bayesian intelligent fault inference model (BIFIM) for an inverter is established to infer the probable uncertain faults. The topological structure of the BIFIM includes the inverter’s operation conditions for the first layer, the inverter’s faults for the second layer, and the fault symptoms for the third layer, which combines the field technicians’ knowledge and experiences with historical running data. The prior probability table of the root node is acquired by the method of basic probabilities corrected historical operation data. The conditional probability parameter table of the BIFIM is obtained by the improved maximum expectation algorithm. Four kinds of incomplete evidence were reasoned and verified, including simple evidence with obvious support, incomplete evidence information, complex evidence without obvious support, and evidence with information conflict. The proposed strategy can make use of the available evidences to inference the probabilities of faults, indicating different reasoning abilities under the different degree of completeness of evidence, especially demonstrating the same inference result under some incomplete evidence information as under complete evidence information.

Customers’ Perception of Service Quality in a Training Institute

SERVQUAL (Service Quality) model is being used to measure the service quality in almost every service sector globally. However, little research exists on its usage in evaluating the performance of the training sector despite its significant role in many developing economies. This article examines the performance of a very reputed training institute in India using SERVQUAL instrument. The first objective of the study was to check whether the customers were satisfied with the service of the institute. The second objective was to measure the gap between perception and expectations. Two expectation levels of the customers were studied – adequate (or minimum) and desirable (or maximum). The result of this study suggests that the training institute surpassed the minimum expectation level of its customers but fell short of the maximum expectation levels. The key dimension where the institute is lacking in terms of providing quality service is “assurance” and therefore the institute needs to revisit and improve the items considered under this dimension.

Use and misuse of the seas around the Galápagos Archipelago

Although the Galapagos Islands were first colonized over 160 years ago, the major impact on the marine resources by local fishermen has occurred only during the last 40–45 years. During this period, and especially more recently, a lack of attention to the largely uncontrolled fishery has led to confusion, a conflict of interests, and a series of inapplicable laws and regulations. Changing markets, exploding human populations, and a new approach to marine resource exploitation, with minimum investment and maximum expectation, has led to a chaotic situation in which neither the fishermen nor the Galapagos National Park will ultimately benefit.