Identification of the critical parts for a medium courier turboprop aircraft

Each time an aircraft system fails, a series of steps are required to repair or restore the aircraft to full operational status. The steps include failure detection, fault isolation, disassembly to gain access to the defective element, repair, and so on. The frequency of the maintenance becomes a significant parameter in determining system support requirements. The maintenance frequency for a particular item depends very much on the reliability of that item. In order to exemplify this idea the present paper contains a series of analyzes whose purpose is to identify the critical parts for a medium courier turboprop aircraft operated by the Romanian Air Force.

Health Assessment of Large Two Dimensional Structures Using Limited Information: Recent Advances

Some recent advances of a recently developed structural health assessment procedure proposed by the research team at the University of Arizona, commonly known as generalized iterative least-squares extended Kalman filter with unknown input (GILS-EKF-UI) are presented. The procedure is a finite elements-based time-domain system-identification technique. It can assess structural health at the element level using only limited number of noise-contaminated responses. With the help of examples, it is demonstrated that the structure can be excited by multiple loadings simultaneously. The method can identify defects in various stages of degradation in single or multiple members and also relatively less severe defect. The defective element(s) need not be in the substructure, but the defect detection capability increases if the defect spot is close to the substructure. Two alternatives are suggested to locate defect spot more accurately within a defective element. The paper advances several areas of GILS-EKF-UI to assess health of large structural systems.

A Modified Autonomous En Transposon in Maize (Zea mays L.) Elicits a Differential Response of Reporter Alleles

Transposable elements in maize are composed of a defined molecular structure that includes coding sequences, determiners of functionality and ordered terminal motifs that provide binding sites for transposase proteins. Alterations in these components change the phenotypic expression of unstable genes with transposon inserts. The molecular basis for the altered timing and frequency of transposition as determined by the size and number of spots on kernels or stripes on leaves has generally been described for defective inserts in genes. Most differential patterns can be ascribed to alterations in the terminal motifs of the reporter allele structure that supplies a substrate (terminal inverted repeat motifs) for transposase activity. For autonomously functioning alleles, the explanations for changes in phenotype are not so clear. In this report, an En-related element identified as F-En is described that shares with En the recognition of a specific defective element c1(mr)888104 but differs from En in that this F-En element does not recognize the canonical c1(mr) elements that are recognized by En. Evidence is provided suggesting that F-En does not recognize other En/Spm-related defective elements, some of whose sequences are known. This modified En arose from a c1-m autonomously mutating En allele.

The Effect of a Single Defective Mask Element on the Multiplex Advantage in Hadamard Transform Spectroscopy

The effect of a single defective mask element on the output signal-to-noise ratio (SNR) for a stationary-mask Hadamard transform (HT) spectrometer is investigated. The decrease in output-SNR from that of an HT spectrometer having a perfect mask is found to be dependent on the amount of energy impinging on the defective element. A method of compensating for the defective mask element is presented. The method is computationally inexpensive and can be fully automated.

Transitory cis complementation: a method for providing transposition functions to defective transposons.

A genetic complementation system is described in which the complementing components are close together in a single linear DNA fragment; the complementation situation is temporary. This system is useful for providing transposition functions to transposition-defective transposons, since transposition functions act preferentially in cis. The basic procedure involves placing a transposition-defective transposon near the gene(s) for its transposition functions on a single DNA fragment. This fragment is introduced, here by general transduction, into a new host. The transposase acts in cis to permit the defective element to transpose from the introduced fragment into the recipient chromosome. The helper genes do not transpose and are lost by degradation and segregation. The method yields single insertion mutants that lack transposase and are not subject to further transposition or chromosome rearrangement. The general procedure is applicable to other sorts of transposable elements and could be modified for use in other genetic systems.