The thermoelastic behaviour of semicrystalline and of glassy poly(ether-ether-ketone)

A thermoelastic evaluation, based on simultaneous measurements of the mechanical work and of the concomitant heat of deformation by a stretching micro calorimeter, was performed on semicrystalline and glassy PEEK. The objective of this study was to utilize the sensitive technique to detect differences that would account for observed effects of micro structure on mechanical performance. A clear difference was detected beyond a 0.6% strain, where the behaviour of glassy PEEK began to exhibit inelastic features such as yielding and plastic deformation. This difference between the glassy and the semicrystalline polymers was considered the reason for the superior mechanical fatigue and fracture properties produced by the latter micro structure.     

Bridging process and structure through criteria

Scholars in design face two central challenges in design methods inquiry: firstly, to integrate process and solution, and secondly, to examine developmental junctures leading to innovation. With these goals in mind, we maintain that design criteria deserve greater attention and illustrate this position with a study of noted designers' use of criteria. The primary finding was that five criteria functions were considered during the design process. The study also explored potential relationships between designer variables (i.e., professional expertise and personality type) and criteria use.     

Perspective channel-type reactor with enhanced safety

Following the search for new design solutions to develop within the framework of channel trends the reactor with enhanced safety the Research and Development Institute of Power Engineering has developed the design of the multiloop boiling water reactor (MKER). The MKER enhanced safety is attained when involving the inherent safety features, passive safety systems as well as the accident consequences confinement devices. The design realizes several advantages which are typical of the channel-type reactors, namely: the design desintegration simplifying the manufacture, control, equipment delivery and decreasing, versus the pressure vessel reactors, the accident effect if it proceeds in an explosive manner; small operating reactivity margin and fuel burnup increased due to continuous refuelling; fuel cycle flexibility allowing comparatively easily to adopt the reactor to the conjuncture of the country fuel balance; multiloop circuit of the main coolant which reduces the degree and effect of the accidents connected with the equipment and pipings rupture; monitoring of the channels and fuel assemblies leak-tightness.     

FOCUS-type fuel assembly for PWRs

In recent years the development efforts for Siemens PWR fuel assemblies were mainly concentrated on reducing the fuel cycle costs and increasing the operational reliability of the fuel assemblies.The first objective was aimed at increasing the average discharge burnup to > 50 MWd/kgU and increasing the critical heat flux. The high envisaged burnup required to develop a corrosion resistant cladding tube outside the Zry-4 range. The decision was made to use a Duplex cladding tube consisting of a corrosion optimized outer layer on a Zry-4 base material. A ZrSnFeCr alloy with reduced tin content was chosen for the outer layer. The critical heat flux could be increased by introducing mixing vanes on the spacer grids within the active length.To reach the second objective, reliable avoidance of spacer grid damage during core loading and unloading and reduction of fuel rod defects by debris fretting, the spacer grid corners were improved and a debris separation grid was developed.These design improvements were introduced into the new FOCUS-type fuel assembly. The name FOCUS stands for “Fuel assembly with Optimized Cladding and Upgraded Structure”.     

Crack growth measurements on components under cyclic loading: comparison of different methods

The cyclic crack growth behaviour was measured by means of d.c. potential drop, a.c. potential drop, ultrasonic and crack-opening displacement (COD) methods. The methods were applied to component tests on straight pipes with an outer diameter of approximately 800 mm and a wall thickness of approximately 50 mm. The pipes were subjected to constant internal pressure (about 15 MPa) and either an alternating (or pulsating) or a quasi-static bending moment using d.c. potential drop, a.c. potential drop, ultrasonic and flaw-opening (COD) methods. The efficiency of the particular methods has been proved by comparison with fractographical analysis of the fracture surfaces.     

Superconductivity in heavy-electron metals

Some of the most outstanding experimental evidences for unconventional superconductivity in heavy-electron materials are rewiewed and discussed.     

Characterization of the flow behaviour of sausage emulsions with a simple tube viscometer

A specially designed tube viscometer was used to measure apparent viscosity during flow of Bologna type sausage emulsions moving through a pipe. Emulsions varied in fat content (from 21.8 to 44.3%) and in moisture/protein ratio (from 3.7 to 5.6), and the effects of added sodium chloride, sodium diphosphate, starch and blood plasma were investigated in a 36% fat, 3.7 moisture/protein emulsion.
The shear stresses determined as a function of shear rate were fitted by a power law. Yield stress of the emulsions was negligible relative to the applied stress. However, inspection of the flow profiles indicated that considerable slip of the sausage emulsion occurred at the pipe wall. Both emulsion flow and slip contribute to overall flow behaviour, so a kind of effective viscosity is determined. Intrinsic rheological properties and wall slip will both be affected by the composition of the sausage emulsion.