REFINE trial

Execution of refiner trials at mills is often difficult without disrupting normal production. Moreover, it is very expensive to undertake such a trial in terms of hardware requirements and machine time. Traditionally, studies to evaluate the impact of refining on pulp quality have been undertaken in the laboratory using the PFI mill (Welch and Kerekes, 1994). This type of study provides little information in terms of defining the optimal refining parameters... 

A series of in-situ refining trials that involved both mill and laboratory evaluation were necessary to undertake to generate sufficient data to convince the mill, beyond any reasonable doubt, to retrofit the refiners with appropriate tackles... 

Deflocculation and Slurry Thinning. Sihcates are used as deflocculants, ie, agents that maintain high sohds slurry viscosities at increased sohds concentrations. Soluble sihcates suppress the formation of ordered stmctures within clay slurries that creates resistance to viscous flow within the various sytems. Laboratory trials are necessary, because the complexity of the systems precludes the use of a universal deflocculant. Sihcates are employed in thinning of limestone or clay slurries used in the wet-process manufacture of cements and bricks, clay refining, and petroleum drilling muds (see also... 

The optimization of reactions involving a large number of variables, and in tire case of metal production diese might include die temperature, gas, slag and metal compositions, die state of motion of each phase, and die leiigdi of die refining period, could be analysed by die classical, so-called Newtonian mediod in which one variable is altered in a given series of tests while all odier variables are held constant, and die results are collected in order to assess die dependence of die productivity on diat variable. However, since each test would be expensive of time and labour on die industrial scale, an alternative may be adopted which reduces die number of plant trials required to separate die effects of die variables. 

Gareisen, n. refined iron trial rod (for testing melted copper). 

X-Ray diffraction from single crystals is the most direct and powerful experimental tool available to determine molecular structures and intermolecular interactions at atomic resolution. Monochromatic CuKa radiation of wavelength (X) 1.5418 A is commonly used to collect the X-ray intensities diffracted by the electrons in the crystal. The structure amplitudes, whose squares are the intensities of the reflections, coupled with their appropriate phases, are the basic ingredients to locate atomic positions. Because phases cannot be experimentally recorded, the phase problem has to be resolved by one of the well-known techniques the heavy-atom method, the direct method, anomalous dispersion, and isomorphous replacement.1 Once approximate phases of some strong reflections are obtained, the electron-density maps computed by Fourier summation, which requires both amplitudes and phases, lead to a partial solution of the crystal structure. Phases based on this initial structure can be used to include previously omitted reflections so that in a couple of trials, the entire structure is traced at a high resolution. Difference Fourier maps at this stage are helpful to locate ions and solvent molecules. Subsequent refinement of the crystal structure by well-known least-squares methods ensures reliable atomic coordinates and thermal parameters. 

The effects that changes in vegetation have on soil carbon pools and nutrient availability are also difficult to evaluate. However, several models have been successful in predicting vegetation-soil nutrient relationships because they assume that such changes occur as a result of different rates of decomposition and nutrient release from leaf litter of different taxa 50, 60), Such predictions could be tested and the models refined or parameterized for new taxa by measuring soil nutrient availability and respiration in stands of different species on the same soil type. For example, fifty years ago the U.S. Civilian Conservation Corps (CCC) established such stands as species trial plots measurements in some indicate large differences in soil nutrient availability (48), Further measurements in these stands would now occur at the same time-scale at which we expect the feedback between species replacement and soil processes to occur. 

The trial functions in the finite element method are not limited to linear ones. Quadratic functions and even higher-order functions are frequently used. The same considerations hold as for boundary value problems The higher-order trial functions converge faster, but require more work. It is possible to refine both the mesh h and the power of polynomial in the trial function p in an hp method. Some problems have constraints on some of the variables. For flow problems, the pressure must usually be approximated by using a trial function that is one order lower than the polynomial used to approximate the velocity. 

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