A spectrum defragmentation problem in elastic optical networks was considered under the assumption that all connections can be realized in switching nodes. But this assumption is true only when the switching fabric has appropriate combinatorial properties. In this paper, we consider a defragmentation problem in one architecture of wavelength-spacewavelength switching fabrics. First, we discuss the requirements for this switching fabric, below which defragmentation does not always end with success. Then, we propose defragmentation algorithms and evaluate them by simulation. The results show that proposed algorithms can increase the number of connections realized in the switching fabric and reduce the loss probability.

Recently, some major changes have occurred in the structure of the European foundry industry, such as a rapid development in the production of castings from compacted graphite iron and light alloys at the expense of limiting the production of steel castings. This created a significant gap in the production of heavy steel castings (exceeding the weight of 30 Mg) for the metallurgical, cement and energy industries. The problem is proper moulding technology for such heavy castings, whose solidification and cooling time may take even several days, exposing the moulding material to a long-term thermal and mechanical load. Owing to their technological properties, sands with organic binders (synthetic resins) are the compositions used most often in industrial practice. Their main advantages include high strength, good collapsibility and knocking out properties, as well as easy mechanical reclamation. The main disadvantage of these sands is their harmful effect on the environment, manifesting itself at various stages of the casting process, especially during mould pouring. This is why new solutions are sought for sands based on organic binders to ensure their high technological properties but at the same time less harmfulness for the environment. This paper discusses the possibility of reducing the harmful effect of sands with furfuryl binders owing to the use of resins with reduced content of free furfuryl alcohol and hardeners with reduced sulphur content. The use of alkyd binder as an alternative to furfuryl binder has also been proposed and possible application of phenol-formaldehyde resins was considered.

Results from the hydro-acoustic studies aiming at evaluation of the Euphausia superba biomass in the Bransfield Strait in March 1981 are presented. These investigations, called conventionally Micro-FIBEX, were carried out on the r/v "Profesor Siedlecki" during 13-16 .March 1981, as continuation of the studies carried out in that region within the scheme of the FIBEX programme in the period of 5-12 March 1981. The abundance of the biomass was estimated at 258 thousand ton, which at the investigated area of about 1755 NM2 gives the mean value of biomass density 142 t/NM2 (41.4 g/m2).

Some aspects of the epidemiology of Maize streak virus (MSV) genus Mastrevirus concerning virus incidence, vector populations and some environmental factors were investigated in field experiments conducted over a three year period (2000–2002) at Samaru, northern Nigeria. Significant positive correlations were obtained between number of leafhoppers caught and MSV incidence and age of plant at infection and also with temperature. Also significant negative correlations were obtained between MSV incidence and mean relative humidity; between number of leafhoppers and age of plants and with mean rainfall. Leafhopper vectors caught included Cicadulina arachidis China, C. mbila Naude, C. triangula Ruppel and C. similis China, in order of abundance. Leafhopper incidence was highest in the months of September and October.