Big Chemical Encyclopedia

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

Articles Figures Tables About

Determination unique system conditioning

Assuming that the pj (t) and Qj (t) can be interpreted as a TS trajectory, which is discussed later, we can conclude as before that ci = ci = 0 if the exponential instability of the reactive mode is to be suppressed. Coordinate and momentum of the TS trajectory in the reactive mode, if they exist, are therefore unique. For the bath modes, however, difficulties arise. The exponentials in Eq. (35b) remain bounded for all times, so that their coefficients q and q cannot be determined from the condition that we impose on the TS trajectory. Consequently, the TS trajectory cannot be unique. The physical cause of the nonuniqueness is the presence of undamped oscillations, which cannot be avoided in a Hamiltonian setting. In a dissipative system, by contrast, all oscillations are typically damped, and the TS trajectory will be unique. [Pg.211]

The integrals Jk (12) introduced here appear to be suitable for the formulation of quantum conditions in the form Jk=nji. By definition, however, they are associated with a co-ordinate system (q, p) in which the Hamilton-Jacobi equation is separable it is therefore essential that we should next examine the conditions under which this co-ordinate system is uniquely determined by the condition of... [Pg.82]

A characteristic of a differential equation is that it involves an unknown function and one or more of the function s derivatives. If the unknown function depends on only one independent variable, it is classified as an ordinary differential equation (ODE). The order of the differential equation is simply the order of the highest derivative that appears in the equations. Consequently, a first-order ODE contains only first derivatives, whilst a second-order ODE may contain both second and first derivatives. The ODEs can also be classified as linear or non-hnear. Linear ODEs are the ones in which all dependent variables and their derivatives appear in a linear form. This implies that they cannot be multiphed or divided by each other, and they must be raised to the power of 1. An ODE has an infinite number of solutions, but with the appropriate conditions that describe systems, i.e. the initial value or the boundary value, the solutions can be determined uniquely. [Pg.81]

Fig. 4-7 Example of a coupled reservoir system where the steady-state distribution of mass is not uniquely determined by the parameters describing the fluxes within the system but also by the initial conditions (see text). Fig. 4-7 Example of a coupled reservoir system where the steady-state distribution of mass is not uniquely determined by the parameters describing the fluxes within the system but also by the initial conditions (see text).
In this chapter the potential of nanostructured metal systems in catalysis and the production of fine chemicals has been underlined. The crucial role of particle size in determining the activity and selectivity of the catalytic systems has been pointed out several examples of important reactions have been presented and the reaction conditions also described. Metal Vapor Synthesis has proved to be a powerful tool for the generation of catalytically active microclusters SMA and nanoparticles. SMA are unique homogeneous catalytic precursors and they can be very convenient starting materials for the gentle deposition of catalytically active metal nanoparticles of controlled size. [Pg.450]

In order to apply the concepts of modern control theory to this problem it is necessary to linearize Equations 1-9 about some steady state. This steady state is found by setting the time derivatives to zero and solving the resulting system of non-linear algebraic equations, given a set of inputs Q, I., and Min In the vicinity of the chosen steady state, the solution thus obtained is unique. No attempts have been made to determine possible state multiplicities at other operating conditions. Table II lists inputs, state variables, and outputs at steady state. This particular steady state was actually observed by fialsetia (8). [Pg.189]

The amount of fluorescence emitted by a fluorophore is determined by the efficiencies of absorption and emission of photons, processes that are described by the extinction coefficient and the quantum yield. The extinction coefficient (e/M-1 cm-1) is a measure of the probability for a fluorophore to absorb light. It is unique for every molecule under certain environmental conditions, and depends, among other factors, on the molecule cross section. In general, the bigger the 7c-system of the fluorophore, the greater is the probability that the photon hitting the fluorophore is absorbed. Common extinction coefficient values of fluorophores range from 25,000 to 200,000 M 1 cm-1 [4],... [Pg.239]

For N particles in a system there are 2N of these first-order equations. For given initial conditions the state of the system is uniquely specified by the solutions of these equations. In a conservative system F is a function of q. If q and p are known at time t0, the changes in q and p can therefore be determined at all future times by the integration of (12) and (13). The states of a particle may then be traced in the coordinate system defined by p(t) and q(t), called a phase space. An example of such a phase space for one-dimensional motion is shown in figure 3. [Pg.431]

Evaluation of diagnostic endeavors reveals two principal and interrelated functions of a classification system. First, diagnostic systems are used to determine what constitutes a disorder (psychiatric condition or not) second, diagnostic systems are used to discriminate among the identified psychiatric conditions. Therefore, in discussing classification, we must first ask what a mental disorder is (i.e., should x be considered a psychiatric condition ). If we answer affirmatively, we must then consider whether this disorder is unique from other disorders within the classification system. We briefly consider each of these issues next. [Pg.10]

Let us now extend the results to dealing with systems where the estimability and redundancy conditions are satisfied. A measurement is considered redundant if its removal causes no loss of estimability. If we consider that the rank of M = g and (m +1) > g, that is, more information is available than is necessary for a unique determination, the following can be stated (Stanley and Mah, 1981a). [Pg.35]

For a binary mixture under constant pressure conditions the vapour-liquid equilibrium curve for either component is unique so that, if the concentration of either component is known in the liquid phase, the compositions of the liquid and of the vapour are fixed. It is on the basis of this single equilibrium curve that the McCabe-Thiele method was developed for the rapid determination of the number of theoretical plates required for a given separation. With a ternary system the conditions of equilibrium are more complex, for at constant pressure the mole fraction of two of the components in the liquid phase must be given before the composition of the vapour in equilibrium can be determined, even for an ideal system. Thus, the mole fraction yA in the vapour depends not only on X/ in the liquid, but also on the relative proportions of the other two components. [Pg.599]

The stability of dioctahedral montmorillonites is, of course, not uniquely a function of P-T conditions acting upon a given silicate mineral assemblage. Studies in the system Na H A O -Sit - O-Cl (Hemley, jet al.. 1961) shows that a high activity of sodium ion at given silica and hydrogen activities can destabilize beidellite. Hess (1966) extrapolates this hydrothermal study to atmospheric conditions where the range of H+, Na+ and SiC activities can determine the presence of an expandable phase. [Pg.87]

It is evident then that the number of phases present can be reduced by restricting the intensive variables to non-unique or inter-dependent conditions and thus a general case" is valid. As the number of chemical components which are perfectly mobile (intensive variables) increases, the number of phases will be decreased. Thus a rock banded in mono-mineralic zones, such as is commonly found in hydrothermal deposits, indicates a system with few inert components. The zonation most commonly represents gradients of the extensive variables temperature and chemical activity of ionic species in aqueous solution. However, it is not always easy to determine which variables are active in a given sequence of mineral bands related to an alteration source. [Pg.176]

Failure Modes and Effects Analysis. Failure modes and effects analysis (FMEA) is applied only to equipment. It is used to determine how equipment could fail, the effect of the failure, and the likelihood of failure. There are three steps in an FMEA (4) (7) define the purpose, objectives, and scope. Large processes are broken down into smaller systems such as feed or cooling. At first, the failures are only considered to affect the system. In a more general study, the effects on a plant-wide basis can be considered. (2) Define the problem and boundary conditions. This includes identifying the system to be studied, establishing the physical boundaries, and labeling the equipment with a unique identifier for use in the FMEA procedure. (3)... [Pg.472]

For systems that have not reached their stationary state (steady state or thermodynamic equilibrium), the behavior with regards to time cannot be determined without knowing the initial conditions, or the values of the state variables at the start, i.e., at time = 0. When the initial conditions are known, the behavior of the system is uniquely defined. Note that for chaotic systems, the system behavior has infinite sensitivity to the initial conditions however, it is still uniquely defined. Moreover, the feed conditions of a distributed system can act as initial conditions for the variations along the length. [Pg.57]


See other pages where Determination unique system conditioning is mentioned: [Pg.122]    [Pg.39]    [Pg.230]    [Pg.638]    [Pg.298]    [Pg.3]    [Pg.472]    [Pg.178]    [Pg.377]    [Pg.842]    [Pg.587]    [Pg.186]    [Pg.377]    [Pg.403]    [Pg.403]    [Pg.266]    [Pg.257]    [Pg.283]    [Pg.382]    [Pg.87]    [Pg.401]    [Pg.389]    [Pg.16]    [Pg.95]    [Pg.42]    [Pg.401]    [Pg.348]    [Pg.130]    [Pg.355]    [Pg.268]    [Pg.265]    [Pg.283]    [Pg.482]    [Pg.969]    [Pg.1506]    [Pg.178]   
See also in sourсe #XX -- [ Pg.318 ]




SEARCH



Condition determination

Conditioning system

Systems conditions 82

UniQuant

Unique

Uniqueness

© 2024 chempedia.info