Study on process parameters in metallocene polymerizations,I. Apparent viscosity and macro-scale mass transfer

A heat balance reaction calorimeter was used to obtain information about the most informative process parameters in polymerizations carried out with Et[Ind]₂ZrCl₂-methylaluminoxane catalyst. The viscosity of the reaction mixture was found to increase dramatically during the homopolymerization of ethylene, but it could be controlled through appropriate selection of the reaction mixture medium. The mass transfer between the gas and liquid phases was the rate-determining step for the polymerization when the reaction mixture-based Reynolds number was below 2.500. The limited mass transfer between the gas and liquid phases was caused by the intensive activity of the metallocene catalyst and the increased viscosity of the reaction mixture.     

Productivity and costs of slash bundling in Nordic conditions

The number of slash bundlers and the volume of slash bundling have been rapidly increasing during the last few years in Finland. However, no comprehensive time or follow-up studies have been carried out on slash bundling technology in Finland or in any other country. Metsäteho Oy carried out studies on the productivity and costs of slash bundling in different Nordic recovering conditions. The study methods included both time and follow-up studies. Data were collected during the summer and winter period primarily in Norway spruce (Picea abies L. Karst.) dominated clear cutting sites. The bundling techniques performed by different types of bundler (Fiberpac 370, Timberjack 1490D, Pika RS 2000, Valmet WoodPac) were studied.

The average productivity of slash bundling was 18.1 bundles per operating (E₁₅, including delays shorter than 15 min) hour with the Timberjack 1490D and Fiberpac 370 bundlers in the follow-up study. The operator of the slash bundler had the greatest effect on the productivity of bundling. The prerequisite for increased bundling volumes is a reduction in the costs of the most expensive sub-stage of the bundling supply chain, i.e. bundling itself. This requires improved recovery conditions at bundling sites, increased bundling productivity, larger sized bundles, and the execution of bundling operations in two work shifts using an efficient bundler and effective operator working methods. Implementation of these development measures will bring the bundling supply chain up to a speed that makes it the most competitive supply chain for forest chips in terms of total supply costs for long-distance transportation distances of more than 60 km.     

Some Notes on the Formal Properties of Bidirectional Optimality Theory

In this paper, we discuss some formal properties of the model ofbidirectional Optimality Theory that was developed inBlutner (2000). We investigate the conditions under whichbidirectional optimization is a well-defined notion, and we give aconceptually simpler reformulation of Blutner's definition. In thesecond part of the paper, we show that bidirectional optimization can bemodeled by means of finite state techniques. There we rely heavily onthe related work of Frank and Satta (1998) about unidirectionaloptimization.     

Lumbar disc degeneration in relation to occupation

Angiogenic growth factors are essential for cancer metastasis, and the growth of metastatic foci also depends on these angiogenic growth factors as well as autocrine or paracrine growth factors. We therefore investigated whether vascular endothelial growth factor (VEGF) and thymidine phosphorylase (dThdPase) are localized more often in primary tumors with hepatic metastasis than in those without such metastasis and whether transforming growth factor (TGF-alpha) and epidermal growth factor receptor (EGF-R) are coexisted more often in hepatic metastases than in primary tumors of gastric cancer. Resected specimens from 82 patients with gastric cancer were examined immunohistochemically. The primary antibodies used were anti-VEGF, anti-dThdPase, anti-TGF-alpha and anti-EGF-R. VEGF expression was found to be higher in primary cancers with than in those without hepatic metastasis (p < 0.001), while VEGF was frequently observed in both hepatic metastases and in the primary tumors. Localization of dThdPase was also higher in advanced than in early gastric cancers (p = 0.021). High co-presence of TGF-alpha and EGF-R was detected more frequently in cancers with deep gastric wall invasion than in those without such invasion (p = 0.050), and also more often in cancers with venous invasion (p = 0.007) and those in the advanced stage (p = 0.020). Co-presence of TGF-alpha and EGF-R was found to be higher, though not significantly, in hepatic metastases (58.8%) than in primary tumors (29.4%). These findings suggest that localization of VEGF may play an important role in hepatic metastasis, and that the expression of VEGF, dThdPase and the TGF-alpha/EGF-R pathway may be responsible for the growth of hepatic metastasis.     

Thermophysical Properties of W–Re Alloys Above the Melting Region

In earlier experiments we have studied pure elements with a fast pulse heating technique to obtain thermophysical properties of the liquid state. We report here results for thermophysical properties such as specific heat and dependences among enthalpy, electrical resistivity, and temperature, for four W–Re alloys (3.95, 21.03, 23.84, and 30.82 at % of Re) in a wide temperature range covering solid and liquid states. Thermal conductivity is calculated using the Wiedemann–Franz law for the liquid alloy, as.well as data for thermal diffusivity for the beginning of the liquid phase. Additionally, data for the entire temperature range studied have been analyzed in comparison with those of the constituent elements, tungsten and rhenium, since both metals have been studied previously with the same experimental technique. Such information is of interest in the field of metallurgy since W–Re alloys of low Re content in the region of mutual component solubility in the solid state are widely used as thermocouple materials for the purposes of high-temperature thermometry.     

Semi-automated user agents in distributed change management

Flexible integration of distributed design and manufacturing activities is one of the key issues in applying just-in-time principles along the logistics chain. The potential of AI based approaches in this field is clear, but the inherent asynchrony, concurrency, and inconsistency of distributed operations has reduced enthusiasm so far.This paper discusses coordination in the context of geographically distributed manufacturing of one-of-a-kind products. Cooperation of partners is based on semi-automated user agents which operate as an integrative layer between more dedicated tools and systems. The management of order changes in elevator manufacture is used as a case example.The work reported here is part of the DIMUN project (DIMUN, 1989) in the RACE program.     

Auditory feedback in haptic collaborative interfaces

The combined effect of haptic and auditory feedback in shared interfaces on the cooperation between visually impaired and sighted persons is under-investigated. A central challenge for cooperating group members lies in obtaining a common understanding of the elements of the workspace and maintaining awareness of the other members' actions, as well as one's own, during the group work process. The aim of the experimental study presented here was to investigate if adding audio cues in a haptic and visual interface makes collaboration between a sighted and a blindfolded person more efficient. Results showed that task performance was significantly faster in the audio, haptic and visual feedback condition compared to the haptic and visual feedback condition. One special focus was also to study how participants utilize the auditory and haptic force feedback in order to obtain a common understanding of the workspace and to maintain an awareness of the group members' actions. Results from a qualitative analysis showed that the auditory and haptic feedback was used in a number of important ways to support the group members' action awareness and in the participants' grounding process.