Sealed NiCd cells: The temperature behaviour of electrodes in excess of electrolyte

The temperature behaviour of both cadmium and nickel oxide electrodes of the sintered type (as used in sealed NiCd cells) has been investigated     

Numerical limit analysis of perforated plates

Full limit analysis is preseted of a thin plate under plane stress, perforated with circular holes arranged in a regular penetration pattern. The material is assumed to be elastic–perfectly plastic and to obey the Huber–Mises yield condition together with its associated flow law. The finite element tangential stiffness method is employed. Triangular constant-strain elements are used, the load being generated by means of constant edge displacements at the periphery of a suitably selected subregion. Load-displacement diagrams are obtained for various edge displacement programs and then an interaction curve is constructed for the perforated plate considered. Each computational step is associated with a certain plastic zone which develops until the limit state configuration is reached. The plate is provided with equilateral triangular configuration of holes with arbitrary cutout coefficients. The interaction curves are plotted against the Huber–Mises yield condition for the plate without openings.     

Dielectric properties of /Agl-xKx/NbO3 solid solutions

The possibility of the occurrence of critical point in /Ag_l-xK_x/NbO₃ solid solutions is discussed.     

The complexity of mean flow time scheduling problems with release times

We study the problem of preemptive scheduling of n} jobs with given release times on m identical parallel machines. The objective is to minimize the average flow time. In this paper, show that when all jobs have equal processing times then the problem can be solved in polynomial time using linear programming. Our algorithm can also be applied to the open-shop problem with release times and unit processing times. For the general case (when processing times are arbitrary), we show that the problem is unary NP-hard. P. Baptiste and C. Dürr: Supported by the NSF/CNRS grant 17171 and ANR/Alpage. P. Brucker: Supported by INTAS Project 00-217 and by DAAD PROCOPE Project D/0427360. M. Chrobak: Supported by NSF grants CCR-0208856 and INT-0340752. S. A. Kravchenko: Supported by the Alexander von Humboldt Foundation.     

In-vessel composting for utilizing of municipal sewage-sludge

The amount of sludge generated from wastewater treatment plants has been increasing year-by-year as the sewerage service area expanded. The composting process is considered to be one of the best management methods to stabilize different organic wastes. The main goal of this investigation was to find the optimal ratio of the quantity of the organic waste to the quantity of the sewage sludge. The process of composting was carried out in the Horstmann bioreactor (pilot scale) for 2–3 weeks and then in a compost pile for 6–12 weeks. Seven experiments were performed, with different ratios of the quantity of organic wastes to the quantity of sewage sludge. The results enabled an estimation of the quality of compost and its usefulness and also the usefulness of the bioreactor to be deduced.     

High temperature deformation of ceramic particle composites

The particle composites Al₂O₃/(2 and 3Y)TZP and MgAl₂O₄/3Y-TZP were tested in bending at temperature of 1280 °C over strain rates from 3.4 × 10⁻⁷ to 1 × 10⁻⁴ s⁻¹ and over stresses from 23 to 85 MPa. Strain rate of the composites decreased as a volume fraction of Al₂O₃ or MgAl₂O₄ increased. MgAl₂O₄/3Y-TZP composites deformed easier under the comparable conditions than alumina/zirconia composites. Four models of composite creep behaviour were compared to the experimental data. All the models were unsuitable for MgAl₂O₄/3Y-TZP, in turn an isostress, an isostrain and a constrained isostrain models provide the good predictions for creep rates for alumina/zirconia ceramics, but the rheological model appeared not good. The threshold stresses approach seems to be useful for describing superplastic flow of MgAl₂O₄/3Y-TZP composites.