Analysis of repair

Most repairs are basically designed as a joint to transfer load into and out of a patch. In the case of the bonded repair a simple method of determining the load sharing ratio 

Effective Patch Stiffness + Effective Degraded Stiffness 

The design analysis of a scarf may be considered similar to a single lap bonded joint, detailed analysis of which can be found in MIL-HDBK 17-3E 3. The analysis of a bonded joint is made complex, however, by the modulus difference of the adhesive compared to the adherends and the relative thicknesses of both which causes a non-linear distribution of the shear forces in a lap joint with peak stresses at the ends [1]. Scarf repairs provide a more uniform stress distribution however, to achieve this an adequate scarf angle is required [24] shown in Eigure 14.6. 

Scarf repairs can be modelled to a first approximation as a simple scarf joint. If the patch matches the parent material in stifliiess and expansion coefficient, simple theory 

In practice, a general rule of thumb for scarfing is to remove 12.7 mm per ply. Ply thickness varies depending on the materials used in the original structure, but for carbon fibre unidirectional tape, it can be as thin as 0.127 mm. Clearly a scarf repair on a structure of 6.35 mm thickness (50 plies thick) would approximately translate to a scarf of 635 mm. 

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Chen, L. and Dixon, K., Analysis of repair and mutagenesis of chromium induced DNA damage in yeast mammalian cells and transgenic mice, Environmental, Health Perspective, 106, 1027-1032, 1998. 

Vreeswijk, M.P., van Hoffen, A., Westland, B.E., Vrieling, H., van Zeeland, A.A., and Mullenders, L.H. (1994) Analysis of repair of cyclobutane pyrimidine dimers and pyrimidine 6-4 pyrimidone photoproducts in transcriptionally active and inactive genes in Chinese hamster cells. J. Biol. Chem., 269, 31858-31863. 

Yanes, M. Jolgar, F. Modarres, M. 2002. Generalized renewal process for analysis of repairable systems with limited failure experience. Reliability Engineering and System Safety, 77 167-180. 

Gerbec, M., 2010. Case study Reliability analysis of natural-gas pressure-regulating installation. Taylor Francis Group, London, ISBN 978-0-415-60427-7. Lindqvist, B.H., 2006. On the statistical modeling and analysis of repairable system. Statistical Science, 21, 532-551. 

Repairable systems are those systems that can be restored to fully satisfactory performance by a method other than replacement of the entire system (Ascher and Feingold, 1984). Reliability analysis of repairable units can be classified into parametric and non-parametric methods. 

Block, J., Ahmadi, A., Tyrberg, T. Kumar, U. 2013b. Fleet-Level Reliability Analysis of Repairable Units A Non-Parametric Approach using the Mean Cumulative Function. International Journal of Performability Engineering, 9, 335-346. 

Hassett T.F., Dietrich D.L. Szidarovszky F. Time varying failure rates in the availability and reliability analysis of repairable system. IEEE Duns. Reliability, 1995, Mar, pp 155-160, Vol. 44. 

This method is often used to perform reliability-related analysis of repairable systems with constant failure and repair rates. The following assumptions are associated with the Markov method [3,21] ... 

The first results of computer-based assessment system application show that the benefits are obvious for repaired (without heat treatment) welds and complex defect configurations defect with height local increasing, group of defects, case analysis of defects interference and possible joining. 

In the simplest terms, a fault-tree for risk analysis requires the following information probabiUty of detection of a particular anomaly for an NDE system, repair or replacement decision for an item judged defective, probabiUty of failure of the anomaly, cost of failure, cost of inspection, and cost of repair. Implementation of a risk-based inspection system should lead to an overall improvement in the inspection costs as well as in the safety in operation for a plant, component, or a system. Unless the database is well estabUshed, however, costs may fluctuate considerably. 

The press had been designed with a capacity to deliver 280 kN press force and to work at a production rate of 40 lids per minute. Calculations to determine the distribution of forming loads required indicated that the press capacity was adequate to form the family of steel lids to be produced on the machine. One of the major areas of interest in the design was the con-rod and pin (see Figure 4.66). The first option considered was based on a previous design where the con-rod was manufactured from cast iron with phosphor bronze bearings at the big and small ends. However, weaknesses in this approach necessitated the consideration of other options. The case study presents the analysis of the pin and con-rod using simple probabilistic techniques in an attempt to provide in-service reliable press operation. The way a weak link was introduced to ensure ease of maintenance and repair in the event... 

Reliability Analysis of Pumps for Uranium Chemical Process, Operating life repair frequency and cost data service ... 

Repair and maintenance records were analyzed to determine failure rates and distribution of failure modes. Preliminary findings are reported which include the Weibull distribution characteristics. Failure mode distributions are approximate. Overall mean-time-between-failure is given for the kiln, leach tank, screwfeeder, tank pump, tank gearbox, and kiln gearbox. The study was confined to an analysis of unscheduled repairs and failures. 

The data are very comprehensive with direct applications to reliability, risk, and event analysis of nuclear power plants. Information has been assembled on failure frequency, modes, repairs, and maintenance. Rate Information is based on demands calculated. The time period covered varies from the early 1970 s to the present. Using real time access, the output format if the event can be varied by selection of 20 generic and detailed categories. 

Based on the survey, the actual costs normally associated with the maintenance operation were reduced by more than 50 per cent. The comparison of maintenance costs included the actual labor and overhead of the maintenance department. It also included the actual materials cost of repair parts, tools and other equipment required to maintain plant equipment. The analysis did not include lost production time, variances in direct labor or other costs that should be directly attributed to inefficient maintenance practices. 

Scheme 5b, solutions (pH=7.5) of these DNA strands were subsequently irradiated under anaerobic conditions, after reduction of the flavin with sodium dithionite [51]. HPLC analysis of samples removed from the assay solution during such an irradiation experiment showed clean transformation of the Tf=T-containing DNA strands into the repaired TfT-containing DNA strands (Fig. 2). These experiments showed for the first time that a reduced flavin, if incorporated into DNA, can inject an extra electron into a DNA du-...

Figure 3 shows an ion exchange HPLC analysis of the irradiation experiment performed with the duplex 13. The starting duplex 13 elutes at a retention time of 13 min. The cleaved DNA strand has a retention time of 11 min. Clearly evident again is the clean conversion of the unrepaired duplex 13 into the cleaved, repaired , DNA fragment. 

Most often proteins are the bacterial biopolymers studied using MALDI MS either from fractions or whole cells. They are not the only isolated cellular biopolymers studied by MALDI, nor the first. Very soon after the introduction of MALDI there were a few reports of the analysis of bacterial RNA or DNA from bacterial fractions. One of the first applications of MALDI to bacteria fractions involved analysis of RNA isolated from E. coli,4 Other studies included analysis of PCR-amplified DNA,5 6 DNA related to repair mechanisms7 and posttranscriptional modification of bacterial RNA.8 While most MALDI studies involve the use of UV lasers, IR MALDI has been reported for the analysis of double stranded DNA from restriction enzyme digested DNA plasmids, also isolated from E. coli.9... 

Robison SH. Cantoni 0, Costa M. 1984. Analysis of metal-induced DNA lesions and DNA-repair replication in mammalian cells. MutRes 131 173-181. 

Burch (1983) suggests that repair mechanisms cause a non neglectible complication for extrapolation from high to low doses and presents a modification of the linear-quadratic formula given above. Katz and Hofmann (1982) carried out an analysis of particle tracks with the result that they find no basis for a linear or linear-quadratic extrapolation to low doses. Van Bekkum and Bentvelzen (1982) present a hypothesis of the gene transfer-... 

In the case of sulfur mustard, analysis of low molecular weight urinary metabolites suffers from the same drawback as in the case of anticholinesterases, i.e., these products are rapidly excreted and provide therefore limited retrospectivity. Similarly, the in vivo lifetime of DNA adducts of sulfur mustard are less than those of protein adducts due to repair of DNA damage. 

Lee YJ, Park SJ, Ciccone SL, Kim CR, Lee SH (2006) An in vivo analysis of MMC-induced DNA damage and its repair. Carcinogenesis 27(3) 446-453 Loehrer PJ, Einhom LH (1984) Drugs five years later. Cisplatin. Ann Intern Med 100(5) 704-713 Li G, Widom J (2004) Nucleosomes facilitate their own invasion. Nat Struct Mol Biol 11 763-769 Liu W, Sun D, Hurley LH (2005) Binding of G-quadruplex interactive agents to distinct G-quadruplexes induces different biological effects in MiaPaca cells. Nucleosides Nucleotides Nucleic Acids 24(10-12) 1801-1815... 

Weinzweig, J., Panter, K.E., Spangenberger, A., Harper, J.S., McRae, R. and Edstrom, L.E. (2002). The fetal cleft palate III. Ultrastructural and functional analysis of palatal development following in utero repair of the congenital model. Plastic and Reconstr. Surg., 104, 2355-2362. 

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