Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Class method discretization

Although the development of a SIMCA model can be rather cumbersome, because it involves the development and optimization of J PCA models, the SIMCA method has several distinct advantages over other classification methods. First, it can be more robust in cases where the different classes involve discretely different analytical responses, or where the class responses are not linearly separable. Second, the treatment of each class separately allows SIMCA to better handle cases where the within-class variance structure is... [Pg.396]

Equation (12.277) is not necessary conservative due to the finite (i.e., in practice rather coarse) size grid resolution, and some sort of numerical trick must be used to enforce the conservative properties. It is mainly at this point in the formulation of the numerical algorithm that the class method of Hounslow et al [74], the discrete method of Ramkrishna [151] and the multi-group approach used by Carrica et al [24], among others, differs to some extent as discussed earlier. [Pg.1084]

Sectional and class methods for the solution of the collisional KE are generally called discrete-velocity methods (DVM). These methods are based on the simple idea of discretizing the velocity space into a grid constituted by a finite number of points. The existing methods are characterized by different grid structures (Aristov, 2001). For example, lattice Boltzmann methods discretize the velocity space into a regular cubic lattice with a constant lattice size (Li-Shi, 2000), whereas other methods employ different discretization schemes (Monaco Preziosi, 1990). By using a similar approach to that used with PBE, it is possible to define A,- as the number density of the particles with velocity and the discretized KE becomes... [Pg.284]

The group of methods collectively called sectional methods are sometimes referred to as zero order methods, group methods, discrete methods or methods of classes. [Pg.1202]

This method has been devised as an effective numerical teclmique of computational fluid dynamics. The basic variables are the time-dependent probability distributions f x, f) of a velocity class a on a lattice site x. This probability distribution is then updated in discrete time steps using a detenninistic local rule. A carefiil choice of the lattice and the set of velocity vectors minimizes the effects of lattice anisotropy. This scheme has recently been applied to study the fomiation of lamellar phases in amphiphilic systems [92, 93]. [Pg.2383]

Hence, as the second class of techniques, we discuss adaptive methods for accurate short-term integration (Sec. 4). For this class, it is the major requirement that the discretization allows for the stepsize to adapt to the classical motion and the coupling between the classical and the quantum mechanical subsystem. This means, that we are interested in discretization schemes which avoid stepsize restrictions due to the fast oscillations in the quantum part. We can meet this requirement by applying techniques recently developed for evaluating matrix exponentials iteratively [12]. This approach yields an adaptive Verlet-based exponential integrator for QCMD. [Pg.397]

The described method can generate a first-order backward or a first-order forward difference scheme depending whether 0 = 0 or 0 = 1 is used. For 9 = 0.5, the method yields a second order accurate central difference scheme, however, other considerations such as the stability of numerical calculations should be taken into account. Stability analysis for this class of time stepping methods can only be carried out for simple cases where the coefficient matrix in Equation (2.106) is symmetric and positive-definite (i.e. self-adjoint problems Zienkiewicz and Taylor, 1994). Obviously, this will not be the case in most types of engineering flow problems. In practice, therefore, selection of appropriate values of 6 and time increment At is usually based on trial and error. Factors such as the nature of non-linearity of physical parameters and the type of elements used in the spatial discretization usually influence the selection of the values of 0 and At in a problem. [Pg.66]

The discrete merge method is a special case of dynamic programming applied to branch list processing. It is applicable to a wide class of network... [Pg.179]

For optimization problems that are derived from (ordinary or partial) differential equation models, a number of advanced optimization strategies can be applied. Most of these problems are posed as NLPs, although recent work has also extended these models to MINLPs and global optimization formulations. For the optimization of profiles in time and space, indirect methods can be applied based on the optimality conditions of the infinite-dimensional problem using, for instance, the calculus of variations. However, these methods become difficult to apply if inequality constraints and discrete decisions are part of the optimization problem. Instead, current methods are based on NLP and MINLP formulations and can be divided into two classes ... [Pg.70]

The unique properties of oligonucleotides create crosslinking options that are far different from any other biological molecule. Nucleic acids are the only major class of macromolecule that can be specifically duplicated in vitro by enzymatic means. The addition of modified nucleoside triphosphates to an existing DNA strand by the action of polymerases or transferases allows addition of spacer arms or detection components at random or discrete sites along the chain. Alternatively, chemical methods that modify nucleotides at selected functional groups can be used to produce spacer arm derivatives or activated intermediates for subsequent coupling to other molecules. [Pg.66]

Additionally to the x-data, a property y may be known for each object (Figure 2.3). The property can be a continuous number, such as the concentration of a compound, or a chemical/physical/biological property, but may also be a discrete number that encodes a class membership of the objects. The properties are usually the interesting facts of the objects, but often they cannot be determined directly or only with high cost on the other hand, the x-data are often easily available. Methods from... [Pg.45]

Note If a single piece of equipment is capable of performing multiple discrete unit operations (mixing, granulating, drying), the unit was evaluated solely for its ability to dry. The drying equipment was sorted into similar classes of equipment, based upon the method of heat transfer and the dynamics of the solids bed. [Pg.434]

Now the method getCompounds returns an interface—List, which is a super type of all possible concrete List classes. No matter what kind of list CompoundLibrary uses to hold its compounds, its clients do not need to care any more because what they get is the common abstraction List. Another way to achieve this is to have getCompounds to return an iterator. Please note the iterator() method in Java Collection Framework creates a new iterator object every time it is called and therefore is an expensive operation and should be used with discretion. [Pg.15]

MBPT starts with the partition of the Hamiltonian into H = H0 + V. The basic idea is to use the known eigenstates of H0 as the starting point to find the eigenstates of H. The most advanced solutions to this problem, such as the coupled-cluster method, are iterative well-defined classes of contributions are iterated until convergence, meaning that the perturbation is treated to all orders. Iterative MBPT methods have many advantages. First, they are economical and still capable of high accuracy. Only a few selected states are treated and the size of a calculation scales thus modestly with the basis set used to carry out the perturbation expansion. Radial basis sets that are complete in some discretized space can be used [112, 120, 121], and the basis... [Pg.274]

The extracts were fractionated by a Preparative Liquid Chromatography method - PLC-8 [2], in eight distinct chemical classes FI-saturated hydrocarbons (HC), F2-monoaromatics, F3-diaromatics, F4-triaromatics, F5-polynuclear aromatics, F6-resins, F7-asphaltenes and F8-asphaltols. This method, proposed by Karam et al. as an extension of SARA method [4], was especially developed for coal-derived liquids. It combines solubility and chromatographic fractionation, affording discrete, well-defined classes of compounds which are readable for direct chromatographic and spectroscopic analysis. [Pg.187]


See other pages where Class method discretization is mentioned: [Pg.315]    [Pg.112]    [Pg.1079]    [Pg.1080]    [Pg.267]    [Pg.279]    [Pg.400]    [Pg.65]    [Pg.140]    [Pg.378]    [Pg.51]    [Pg.58]    [Pg.3]    [Pg.711]    [Pg.450]    [Pg.5]    [Pg.71]    [Pg.366]    [Pg.351]    [Pg.222]    [Pg.26]    [Pg.512]    [Pg.878]    [Pg.42]    [Pg.164]    [Pg.124]    [Pg.441]    [Pg.35]    [Pg.218]    [Pg.484]    [Pg.118]    [Pg.1724]    [Pg.165]    [Pg.4]   
See also in sourсe #XX -- [ Pg.267 , Pg.268 , Pg.275 ]




SEARCH



Class method

Discrete method

© 2024 chempedia.info