The regression model for the evaluation of the quality parameters for pellets.

Abstract. In Latvia no European legislation concerning the quality of the production of pellets is adopted. Since the market is not regulated by any governmental regulations, biofuel testing is not compulsory. This aspect leads to a situation where pellets of various qualities are available on the market. The main objective of this paper is to compare the characteristics of the pellets which are produced in various regions of Latvia. The second goal is to develop a regression model which describes the influence of the independent aspects (physical parameters, price, trading form, transportation distance etc.) on the pellet quality. The quality parameters for the solid biofuels were determined according to the methods described in the Technical Specifications of the European Commission for Standardization. The regression model for the pellet quality has been implemented using the software STATGRAPHICS Centurion 16.1.15. The results of the research emphasize that the physical parameters of the pellets vary widely. Three regression models were built in order to describe the influence of the various parameters on the indicator (price per net calorific value) and on the mechanical quality of the pellets. The fitted Models were described by the regression equation given in the paper

Post Si(C)N hillock nucleation and growth in IC copper lines controlled by diffusional creep

International audiencePost Si(C)N hillocks are characterized on Cu interconnects networks. Each network is compounded by standard damascene process electroplated Cu lines with given width and local line density. AFM results show that total volume per area of post Si(C)N hillocks both on narrow and large lines increases linearly with local Cu line density. Two trends of hillocks nucleation and growth are highlighted depending on line width. For line widths inferior to 4 pun, hillocks are located at the line edge. As line density increases, the number of hillocks remains constant but their mean volume proportionally increases. For wider lines, hillocks preferentially nucleate at the center of the line. The number of hillocks proportionally increases as line density increases, but hillock mean volume remains constant. Post Si(C)N hillocks density is found to be proportional to post CMP Cu grain surface boundary density before capping. It is proposed that hillocks growth could be controlled by Cu/Ta interface diffusion on narrowest lines and by grain boundary diffusion on wider ones. (C) 2009 Elsevier B.V. All rights reserved

Effect of wall conduction on natural convection over a vertical slender hollow circular cylinder

An analysis is made of the laminar natural convection of incompressible fluids over a slender, hollow circular cylinder with the inner surface at a constant temperature of T b . The temperature of the outer surface must be solved from the coupled conduction of the cylinder and the natural convection of the fluid over the cylinder. The objective of this paper is to investigate the effect of conduction on the heat transfer characteristics of the natural convection boundary layer of the fluid. A wall conduction parameter, p , is introduced which is a measure of the heat conductivities of the solid and the fluid and the thickness of the cylindrical shell. The governing differential equations, being non-similar, are solved by a finite-difference method. Numerical results are generated for a series of values of p 's and Prandtl numbers.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41805/1/10494_2005_Article_BF01666801.pd