Rechnerunterstützte Gestaltung und Kostenerkennung von Schweißkonstruktionen

Computer-assisted design and cost assessment of welded constructions. Newly developed functions permit modelling of welded joints in 3D CAD systems. The designer identifies the welding zone and the CAD system suggests appropriate forms and dimensions of welded seams at an early design stage. The user can then correct the proposal if necessary. Detailed information about the welding process can be added later by another specialist or with the aid of an expert system. On utilising the CAD-assisted selection of raw materials, the costs of the welded joint can be calculated automatically in very detailed form.     

Mischen in Schneckenmaschinen,Teil 2: Suspendieren,Desagglomerieren und Emulgieren

Mixing in screw mixers, Part 2: Suspension, de-agglomeration, and emulsification . This paper explains the physical laws pertaining to the suspension of solids in liquids, to deagglomeration, and to mixing of immiscible liquids; some results from these different fields are also presented. In fibre reinfored plastics the length of the fibres must be great and the distribution of their length must be narrow. The product undergoes little grinding on using mixing with low shear stresses, feeding with fibres that are not too long, and adding the fibres to the melt. Pigments and some other additional materials tend to agglomerate. De-agglomeration is necessary to improve the products. It is determined by the adhesion and the force number, which is the product of velocity and time of shearing. Taking suitable action will ensure minimized abrasion in case of abrasive material. A size distribution of droplets will be found if there is only a limited miscibility of liquids. Only size reduction will improve the homogeneity. The velocity of shearing, the interfacial tension, and the ratio of the viscosity of the components, all play a role in this process.     

A preliminary investigation into the restorative potential of public aquaria exhibits: a UK student-based study

Even ‘managed’ natural settings, such as botanical gardens and zoos, can provide restorative experiences. Well-being benefits may also be greater in land/waterscapes with greater biodiversity (eg, species richness). Using two photo studies with student participants, we explored aesthetic and behavioural preferences, affect and the restorative potential of multiple public aquaria exhibits, including variation in biodiversity. Study 1 (N = 39) found that aquarium exhibits, in general, scored as highly as natural environments (eg, green space) on all dimensions. Study 2 (N = 40) examined whether responses were influenced by exhibit characteristics including: climatic region (tropical/temperate), biological group (vertebrates/invertebrates), species richness (high/low) and abundance of individuals (high/low). Supporting predictions, tropical, vertebrate (fish) and high species richness exhibits were generally rated more positively than temperate/invertebrate/low species richness exhibits. However, some low richness/high abundance exhibits were also rated unexpectedly positively. Findings are discussed within the context of the growing well-being and biodiversity literature.     

Swelling behavior of U-Pu-Zr fuel

Recent fast reactor driver fuel tests in the Experimental Breeder Reactor II (EBR-II) have demonstrated good performance of U-Pu-Zr fuel alloys to burnups >15 at. pct. Postirradiation examination of these tests has yielded a large amount of fuel-swelling data and metallographic information. These data show that prior to making contact with the cladding tube, metallic alloy fuel swells rapidly due to its high fission-enhanced creep rate and irradiation growth. Measurements of macroscopic fuel slug growth during the entire fuel pin lifetime can now be understood by properly taking into account the irradiation environment and microstructural changes for the various alloy compositions. It has been determined that fission rate, temperature, and plutonium concentrations influence the observed macroscopic swelling rate.     

Mischen in Schneckenmaschinen,Teil 1: Homogenisieren

Mixing in screw mixers, Part 1: Homogenization . During the treatment of thermoplastic synthetic materials in screw mixers the powder or granular material has to be melted as well degassed, mixed, and delivered against higher pressure. The mixing operations are: Mixing of soluble liquids, suspending of solids in liquids, deagglomeration, mixing of immiscible liquids and mixing of particulate solids. The efficiency of mixing of soluble liquids is poor in conventional single-screw extruders under low pressure. Additional mixing elements are therefore placed on the screw. The distribution of the components is better in co-kneaders and multistage screw mixers than in conventional single-screw mixers. Co-rotating screws which mesh together show a more careful treatment and more steady mixing of soluble liquids than contrarotating screws. The manufacturers of such continuously working machines are venturing increasingly into the area of reaction technology with treatment of highly viscous materials. A new development is the new programmable reactor.     

Design of a cylindrical high-voltage high-temperature vacuum insulator

A design for a high temperature, HV insulator is presented. This design exploits the temperature dependent thermal and electrical properties of alumina and a unique structural insulator design to increase the high voltage hold-off characteristics of the insulator, reduces thermal flux through the insulator, and alleviate stresses caused by mismatch between insulator and electrode thermal expansion coefficients. The designed insulators insulate graphite electrodes at temperatures approaching 1000/spl deg/C and potentials up to 50 kV. In this paper, the general methodology of designing these insulators is explored, and some limited performance data is presented.