An algorithm for detecting drift in the value of the comparison standard when analyzing the data of key comparisons of national standards

An algorithm for revealing the piecewise-linear drift of the value of the comparison standard when making international comparisons is proposed. The probabilities of errors of the 1st and 2nd kinds are estimated and recommendations are made on choosing the parameters of the algorithm. A comparative analysis of different algorithms for identifying a point of discontinuity of the piecewise-linear drift model is carried out. __________ Translated from Izmeritel’naya Tekhnika, No. 2, pp. 68–72, February, 2008.     

Relationship of Coating Failure to Deformation in the Deep Drawn Cup

Deformation of the metal substrate in the deep drawing process was characterized by macroscopic appearance and strain distribution. The results of the analysis were correlated with the modes of coating failure. The characteristic ears and valleys at the top of the cup and buckling of the metal in the valley regions resulted from instabilities raised during the cupping process. Earing was a plastic instability that originated from the combined factors of the crystallographic unit cell and the anisotropy of the rolled metal substrate. Buckling was an elastic instability that occurred when the valleys lost constraint before the ears. Stopping the forming process at intermediate positions before the cup was completely formed revealed four stages in the cupping process. Stage I was the initial indentation with formation of six ears. Stage II was conversion from 6 ears to 4 ears separated by alternating deep and shallow valleys. Stage III, loss of constraint in the deep valleys, led to buckling. Stage IV was total loss of constraint. Relationships between the deep drawing process as described by the 4 stages and coating failure were explored with two coating formulations: one that did not fail during deep drawing and one that failed. Two failure modes were observed on the deep drawn cup. Mode I, coating delamination at the top of the cup, was related to the bucking instability. Mode II, loss of adhesion along the cup wall, was caused by elastic retraction of the unconstrained cup in stage IV.     

Prospects for the use of high-Tc superconductors in fusion magnets and options for their test in SULTAN

In the last few years, the critical current densities of long commercially available REBa₂Cu₃O_7?x (RE-123, where RE represents Y or a rare earth element) coated conductors have reached values of 250 A/cm-width at 77 K and zero applied field. Even higher values of 600 A/cm-w (77 K, B = 0) have been demonstrated in shorter lengths. The attractive features of the use of these high-T_c superconductors (HTS) are operation temperatures above 20 K and/or magnetic fields higher than those envisaged for the ITER TF coils. Possible operation conditions for HTS fusion magnets have been studied taking into consideration the possible further improvements of RE-123 coated conductors. Investigations of stability and quench behavior indicate that stability is not a problem, whereas quench detection and protection need attention. Because of the high currents necessary for fusion magnets, many tapes need to be assembled into a transposed conductor. The qualification of HTS conductors for fusion magnets would require their test at magnetic fields of 11 T and currents well above 10 kA. The possibilities to test straight HTS conductor samples in SULTAN have been considered. For a test at 4.5 K, only the development of a low resistance joint between the HTS conductor under test and the NbTi transformer of SULTAN would be necessary. Tests up to 20 K would require that the HTS sample is connected with the NbTi transformer by a conduction-cooled HTS bus bar of large thermal resistance similar to the HTS module of a current lead. HTS conductor tests at temperatures around 50 K would be possible with modified cryogenics.     

Prospects for constructing cogeneration stations equipped with back-pressure steam turbines

The possibilities of using back-pressure cogeneration turbines developed on the basis of serially produced ones are considered together with the thermal process circuits in which such turbines are applied. Design versions and advantages of cogeneration stations in which the proposed process circuits are implemented are described.