Twist-channel angular pressing: effect of the strain path on grain refinement and mechanical properties of copper

Substructural characteristics of Cu (99.97%) were examined after the Twist channel angular pressing (TCAP) process carried out at ambient temperature. Grain refinement efficiency and resulting thermal stability were evaluated after three passes with respect to utilization of various strain paths. Results were obtained using light microscopy and X-ray diffraction methods; Mechanical properties of extruded materials were also tested. Thermal stability was studied after application of three annealing cycles. Based on the findings, Bc route is the most efficient strain path with respect to the grain refinement; higher speed of extrusion (10 mm/s) corresponds with suppression of the static recrystallization. Measured strength, obtained after three passes (route A), achieved values around 440 MPa homogeneously along the cross section of the extruded material. Homogeneity of deformation was also confirmed by micro-hardness tests. The grain size, determined after three passes, averaged out 1.2 μm. Application of TCAP (three passes) brought markedly homogeneous deformation throughout the processed sample in comparison with classical ECAP process.     

Second Inflection Point of the Surface Tension of Water

The theme of a second inflection point of the temperature dependence of the surface tension of water remains a subject of controversy. Using data above 273 K, it is difficult to get a proof of existence of the second inflection point, because of experimental uncertainties. Data for the surface tension of supercooled water and results of a molecular dynamics study were included into the exploration of existence of an inflection point. A new term was included into the IAPWS equation to describe the surface tension in the supercooled water region. The new equation describes the surface tension values of ordinary water between 228 K and 647 K and leads to the inflection point value at a temperature of about 1.5 °C.     

在飞思卡尔DSC中实现矢量控制算法

本文重点介绍永磁电机的无传感器器矢量控制及其在飞思卡尔DSC上的实现。     

A study on the spectral changes of reactive textile dyes and their implications for online control of dyeing processes

Evidence is presented that confirms the colour changes of a widely used trichromatic mixture of bifunctional reactive dyes (Levafix CA) under alkaline conditions, showing that they occur slowly and throughout the dyeing time, and not instantly after alkali addition to the dyebath. Thus, it is impossible to determine the specific absorptivity of the dyes at each moment of the dyeing process. An investigation into the relationship of the type of reactive group to the dye and the visible spectral changes over time was undertaken. Model reactive dyes were studied. The samples collected from the simulated dyebaths were monitored online using an automated system and their absorption on the whole of the visible spectrum was measured. The studies of dyes that included halo‐s‐triazinyl groups revealed the existence of hypochromic shifts in the spectra of the dyes in the presence of an electrolyte (sodium chloride or sodium sulphate) and bathochromic and hyperchromic shifts, when evaluated in the presence of alkaline agents. However, the vinylsulphonyl derivatives present a more stable spectral profile. The use of buffer solution at pH 5 was an efficient method to stabilise the absorption profile of Levafix CA trichromatic samples.     

Summary report on new regulatory codes and criteria and guidelines: IAEA guidelines for WWER reactor coolant system integrity assessment

In the frame of the nuclear safety programme to assist the countries of Central and Eastern Europe, the IAEA identified and ranked in total 263 safety issues for WWER-440/230, WWER-440/213 and WWER-1000/320 nuclear power plants, related to both design and operation. In the area of reactor coolant system integrity, 24 safety issues were identified and 15 of them ranked as of high safety significance. These include: reactor pressure-vessel integrity and related aspects, primary and secondary high-energy piping integrity, steam generator integrity and reliability of the non-destructive testing for in-service inspection. In addition to obtaining international consensus on possible solutions to address the safety issues identified and to reviewing completeness of proposed safety improvements, the IAEA initiated development of guidelines to address the issues of highest safety concern. In the area of the reactor coolant system integrity, guidelines for the leak before break concept application, for the pressurized thermal shock analysis and for the in-service inspection systems qualification were developed. Further activities of the IAEA were focused on the implementation of guidelines developed in the Member States concerned. With this objective, a Co-ordinated Research Programme ‘Round-robin Exercise on WWER-440 Reactor Pressure Vessel Embrittlement, Annealing and Re-embrittlement’, a ‘WWER-440/213 Pressurized Thermal Shock Analysis Benchmark Exercise’ and a pilot study to implement the qualification approach to a real power plant component have been initiated by the IAEA and are well under way at present. In this paper, an overview of these IAEA activities related to reactor coolant system integrity is provided and the main principles and elements of guidelines developed discussed.