Direct Laser Sintering of Borosilicate Glass

Despite the advantages that selective laser sintering (SLS) offers in terms of material availability, many materials have yet to be explored for feasibility and even fewer are available on a commercial basis. This paper presents initial investigations for one such material, borosilicate glass, which could be of particular interest to filter manufacturers because it presents an attractive alternative to the conventional, time-consuming way of producing filters of various porosity classes. Process results are presented including a determination of the optimal parameter window and the effect of processing parameters on the density and surface quality. The effects of thermal post-processing and the inclusion of an additive are also discussed.Mechanical Engineerin

Stability of the WTP measurements with successive use of choice experiments method and multiple programmes method

This paper is part of an investigation to evaluate the benefits of landscape policies. Such policies are, within a specific area (here the Monts d’Arrée in Brittany), favouring some landscape attributes. We test out a procedure based on a double device. The first one relies on the choice experiments method and focuses on each attribute. Without prior information about the presence of substitution and complementarity effects between attributes, we work on the basis of scenarios built to ensure the independence of attributes. The important question of the impact of an attribute variation on the aesthetic value of another one, when these attributes are jointly perceived, is tackled by use of the multi-programme method. The two surveys were launched after an interval of one year, sampling among the same population. The WTP results obtained from each method are not statistically different.Valuation; choice modelling; multi-attributes choice set; multi-programme method; choice experiments; landscape; Monts d’Arrée

Relating Weyl and diffeomorphism anomalies on super Riemann surfaces

Starting from the Wess-Zumino action associated to the super Weyl anomaly, we determine the local counterterm which allows to pass from this anomaly to the chirally split superdiffeomorphism anomaly (as defined on a compact super Riemann surface without boundary). The counterterm involves the graded extension of the Verlinde functional and the results can be applied to the study of holomorphic factorization of partition functions in superconformal field theory.Comment: (LATEX, 18 pages), MPI-Ph/92-38, LPTB 92-

Organic Agriculture in Estonia

Report contains the information about organic farming development, organic food production, processing and marketing in Estonia until 2004

Direct Laser Sintering of Ceramics

For more than one decade layer manufacturing technologies assist the development of new products. Due to a layer-wise build-up of a three-dimensional geometry, nearly every complex design is producible in a short period of time. Selective Laser Sintering is a powderbased technique to produce plastic prototypes (Rapid Prototyping) or metal mould inserts (Rapid Tooling). The laser sintering of ceramic powder is not yet commercialized but applications could be both Rapid Prototyping and Rapid Tooling. The former involves the laser sintering of investment casting shells and cores to cast metal prototypes and the latter the laser sintering of ceramic master patterns for metal spray forming of steel mould inserts. The advantage compared to actual processes are a faster availability of the final product. To facilitate these applications, special ceramic powders as well as new process parameter combinations were investigated. This paper will present achieved results within the abovedescribed applications.Mechanical Engineerin

On the holomorphic factorization for superconformal fields

For a generic value of the central charge, we prove the holomorphic factorization of partition functions for free superconformal fields which are defined on a compact Riemann surface without boundary. The partition functions are viewed as functionals of the Beltrami coefficients and their fermionic partners which variables parametrize superconformal classes of metrics.Comment: 5 pages, LATEX, MPI-Ph/92-7