Alternative Refining Methods

Though this new algorithm still requires some time step refinement for computations with highly inelastic particles, it turns out that most computations can be carried out with acceptable time steps of 10 5 s or larger. An alternative numerical method that is also based on the compressibility of the dispersed particulate phase is presented by Laux (1998). In this so-called compressible disperse-phase method the shear stresses in the momentum equations are implicitly taken into account, which further enhances the stability of the code in the quasi-static state near minimum fluidization, especially when frictional shear is taken into account. In theory, the stability of the numerical solution method can be further enhanced by fully implicit discretization and simultaneous solution of all governing equations. This latter is however not expected to result in faster solution of the TFM equations since the numerical efforts per time step increase. 

Caustic refining in particular does not only effectively perform the separation functions described above but is considered more forgiving in operation than alternate physical methods. If the degumming operation has been less than perfect (or is not used), alkali refining will remove the bulk of the phosphatides. If a high amount of metals, particularly calcium and magnesium, are present, these can be... 

The energy balances of the re-refining processes are important for their overall economic viability. The energy balance calculation in terms of the percentage weight feedstock for the three alternative disposal methods is ... 

Alternative techniques of vegetable oil refining have been developed. Simple refining methods were explored to process extruded-expelled (E-E) soybean oils with various fatty acid compositions (Wang and Johnson 2001b, 2001c). E-E... 

Requirements specified in this way are deemed-to-satisfy rules. Such rules cannot be used to quantify the performance of the structure in general, specific effects of additional measures (for instance increasing the cover to the steel), or the consequences of sub-standard practice (for example using a higher w/c). In this respect it is important to note that EN 206 also allows the use of alternative performance-related design methods with respect to durability that consider in a quantitative way each relevant deterioration mechanism, the service life of the element or structure, and the criteria that define the end of the service life. Such methods should draw a picture of the characteristics that the concrete must possess to protect the reinforcement for the service life requested from a predictive model of the corrosion attack. These refined methods (as opposed to standard methods) may be based on long-term experience with local practices in local environments, on data from an established performance test method for the relevant mechanism, or on the use of proven predictive models. 

Konnert s technique for refining the structure of proteins subject to known geometrical constraints has been developed by incorporating restraints on the variances of the interatomic distributions, in order to express the retention of local geometry that accompanies certain modes of motion." As as alternative to the sparse matrix approach, Hoad and Norman have utilized the fast Gauss-Seidel least-squares routine for the refinement of atomic co-ordinates." A comparison has been made of the structures obtained for bovine trypsin (EC 3.4.24.4) by the difference Fourier and real space refinement methods." ... 

Abstract The aim of this chapter is to introduce special numerical techniques. The first part covers special finite element techniques which reduce the size of the computational models. In the case of the substructuring technique, internal nodes of parts of a finite element mesh can be condensed out so that they do not contribute to the size of the global stiffiiess matrix. A post computational step allows to determine the unknowns of the condensed nodes. In the case of the submodel technique, the results of a finite element computation based on a coarse mesh are used as input, i.e., boundary conditions, for a refined submodel. The second part of this chapters introduces alternative approximation methods to solve the partial differential equations which describe the problem. The boundary element method is characterized by the fact that the problem is shifted to the boundary of the domain and as a result, the dimensionality of the problem is reduced by one. In the case of the finite difference method, the differential equation and the boundary conditions are represented by finite difference equations. Both methods are introduced based on a simple one-dimensional problem in order to demonstrate the major idea of each method. Furthermore, advantages and disadvantages of each alternative approximation methods are given in the light of the classical finite element simulation. Whenever possible, examples of application of the techniques in the context of adhesive joints are given. 

The assessment provided in this chapter shows how, from the innovation niche perspective, there are several alternatives and competing technologies that differ in terms of feedstock used, refining method and, most importantly, techno-economic performance and environmental impact. A clear line is drawn between the first- and... 

Extraction or Refining Methods. The most widely used techndogy fi)r produdi aluminum involves two steps extraction and purification of aluminum oxide (alumina) fiom ( es (primarily bauxite although alternate raw materials can be used), and electrolysis of the oxide afto it has beat dissolved in fused cryolite. 

Low temperature filtration (qv) is a common final refining step to remove paraffin wax in order to lower the pour point of the oil (14). As an alternative to traditional filtration aided by a propane or methyl ethyl ketone solvent, catalytic hydrodewaxing cracks the wax molecules which are then removed as lower boiling products. Finished lubricating oils are then made by blending these refined stocks to the desired viscosity, followed by introducing additives needed to provide the required performance. Table 3 Usts properties of typical commercial petroleum oils. Methods for measuring these properties are available from the ASTM (10). 

The matte can be treated in different ways, depending on the copper content and on the desired product. In some cases, the copper content of the Bessemer matte is low enough to allow the material to be cast directly into sulfide anodes for electrolytic refining. Usually it is necessary first to separate the nickel and copper sulfides. The copper—nickel matte is cooled slowly for ca 4 d to faciUtate grain growth of mineral crystals of copper sulfide, nickel—sulfide, and a nickel—copper alloy. This matte is pulverized, the nickel and copper sulfides isolated by flotation, and the alloy extracted magnetically and refined electrolyticaHy. The nickel sulfide is cast into anodes for electrolysis or, more commonly, is roasted to nickel oxide and further reduced to metal for refining by electrolysis or by the carbonyl method. Alternatively, the nickel sulfide may be roasted to provide a nickel oxide sinter that is suitable for direct use by the steel industry. 

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