Transfer function approach

Fig. 3.3 The transfer function approach. Fig. 3.3 The transfer function approach.
The elements of a closed-loop control system are represented in block diagram form using the transfer function approach. The general form of such a system is shown in Figure 4.1.  [c.63]

This may include elimination of signals from solvent molecules, and changes in disposition of peaks in a spectmm with respect to the baseline as a function of the number of directly coupled H nuclei. Polarization transfer, or population transfer, as it is sometimes called, involves shifting characteristics, eg, energy and spin state, of the abundant spin magnetization to or some other nucleus and therefore is an important experimental approach to spectral editing. Two examples of spectral editing techniques are the INEPT and DEPT experiments. Simultaneous transfer of polarization from all H nuclei to all of A nuclei can be accompHshed using the insensitive nuclei enhanced by polarization transfer (INEPT) method (2). A serious drawback of INEPT is the fact that triplets and other multiplets are not immediately recognizable, because intensities are distorted. The distortionless enhancement by polarization transfer (DEPT) method eliminates this drawback and can directly distinguish among methyl, methylene, methine, and quaternary carbons (2). The technique uses polarization transfer from sensitive nuclei such as H, E, or P to insensitive nuclei, ie, Si, or N (see Table 1). One final advantage of polarization transfer-based methods is an increase in sensitivity of where the subscripts refer to the sensitive and insensitive nuclei, respectively.  [c.404]

In the basic continuous adsorption cycle illustrated previously in Fig. 5b two adsorbent beds are heated and cooled out of phase in order to provide continuous heating or cooling. It is possible to recover some of the adsorption heat rejected by each bed and use it to provide some of the heat required by the other bed. This might be done by the use of a circulating heat transfer fluid or a heat pipe. Meunier [5] first systematically looked at the potential gain in COP that might be obtained by such heat recovery, both as a function of the approach temperature of the beds donating and receiving heat and of the number of beds. The number of beds is not limited to two and the COP increases with the number of beds that it is possible to transfer heat between. There is of course a practical limitation, but it is possible to calculate the theoretical benefit of employing heat exchange between any number of beds.  [c.323]

The response produced by Eq. (8-26), c t), can be found by inverting the transfer function, and it is also shown in Fig. 8-21 for a set of model parameters, K, T, and 0, fitted to the data. These parameters are calculated using optimization to minimize the squarea difference between the model predictions and the data, i.e., a least squares approach. Let each measured data point be represented by Cj (measured response), tj (time of measured response),j = 1 to n. Then the least squares problem can be formulated as  [c.724]

Several other improvements of the inversion-recovery scheme employ advanced tools of modem NMR spectroscopy polarization transfer and two-dimensional spectroscopy (see fiirther reading). The basic design of selected pulse sequences is compared with the simple inversion-recovery scheme in figure Bl.13.5 taken from Kowalewski and Maler [24], where references to original papers can be found. The figure Bl.13.5(a), where thick rectangular boxes denote the 180° /-spin pulses and thin boxes the corresponding 90° pulses, is a representation of the inversion-recovery sequence with the continuous saturation of the protons. In figure B1.13.5(b), the inverting /-spin pulse is replaced by a series of pulses, separated by constant delays and applied at both the proton and the /-spm resonance frequencies, which creates a more strongly polarized initial /-spin state (the polarization transfer teclmique). In figure B1.13.5(c), a two-dimensional (2D) NMR teclmique is employed. This type of approach is particularly usefiil when the sample contains many heteromiclear IS spin pairs, with different /s and different. S s characterized by slightly different resonance frequencies (chemical shifts), resulting in crowded spectra. In a generic 2D experiment, the NMR signal is sampled as a fiinction of two time variables t is the miming tune during which the FID is acquired (different  [c.1508]

A variety of interconnected, bimolecular, collision studies have been described that employ laser devices to investigate the detailed energy disposal in product molecular species and to provide a direct experimental measure of the energy-transfer distribution function P(E, E ). A knowledge of this function is important both in testing detailed theoretical energy-transfer calculations and in modelling unimolecular chemical reactions using master-equation methods. Although there have been a number of extremely infonnative studies of the energy relaxation of highly vibrationally excited molecules in the past, with rare exception these studies are not able to follow all the degrees of freedom of the quencher molecules. The experimental approach described here, designed as it is to investigate the detailed dynamics of these collisions by separately probing the vibrational, rotational and translational degrees of freedom, can significantly increase our understanding of the mechanisms for these fundamental processes that are of such importance in studies of photochemistry, unimolecular and bimolecular reactions. All of these experiments provide data of fundamental chemical interest since the infonnation obtained is sensitive to molecular-potential-energy surfaces and can serve as a test for necessarily approximate dynamical theories. In addition, many of the experimental data obtained will be of practical interest in the study and control of unimolecular chemical reactions and photochemical processes in the development of optically pumped molecular  [c.3013]

The second discussion point is how the actual quantum system is to be described should one follow the time evolution of the time-dependent Schrodinger equation (TDSE) that allows mixed states to evolve, or should one insist on selecting a pure state, taking care of (sudden) transitions between states by some additional action in order to satisfy the time evolution of probabilities of states as dictated by the TDSE The former approach was followed, among others, by Bala et al. in wave packet dynamics applied to proton transfer in phospholipase A2 [109,110] and by us in the Density Matrix Evolution (DME) method which describes the mixed time-dependent wave function on asimple, appropriately chosen, basis set. [105, 111, 112, 113,114, 106, 115]. DME is obviously not capable of giving a correct response of the classical environment to quantum transitions, but is perfectly able to describe initial late processes or quantum systems that only weakly influence their environment. In fact, DME is the common method used in the evolution of nuclear spin magnetization [116]. The latter approach has led to the surface hopping method pioneered by Pechukas [117], with a modern formulation by Tully [118]. The basic idea is that the dynamics of a pure quantum state is followed, simultaneous with the classical dynamics of the environment. At every step the probability of a transition to another quantum state is calculated and such transitions are realized on a stochastic basis. When a transition is made, velocities are scaled to conserve total energy. The method has been  [c.17]

Standard reference materials provide a necessary but insufficient means for achieving accuracy and measurement compatibiUty on a national or international scale. Good test methods, good laboratory practices, well-qualified personnel, and proper intralaboratory and intedaboratory quaUty assurance procedures ate equally important. A systems approach to measurement compatibiUty is ikustrated in Figure 2. The function of each level is to transfer accuracy to the level below and to help provide traceabiUty to the level above. Thus traversing the hierarchy from bottom to top increases accuracy at the expense of measurement efficiency.  [c.18]

One drawback of magnetic toners is apparent when colored developers are needed. Materials having the required magnetism are typically brown to black in color and limit the quaUty of colors achievable. A more recent change in development systems is the use of single- or monocomponent developers. As the name implies, only one kind of particle is used. This particle serves as the toner and can be magnetic or nonmagnetic depending on whether ferromagnetic material is incorporated. No carrier particles are used and the system is simpler, smaller, and avoids some aging effects. There is another material involved in controlling the necessary triboelectric charging of the toner. This charge control is accompHshed by coating a roUer with the appropriate material, just as carriers are coated in two-component developers, and the roUer thus acts to control not only the charging but also the transport and metering of the toner. This, or a similar roUer, can also be appropriately biased to function as a development electrode. A particular case of single-component development is jumping-toner development in which triboelectricaUy charged toner covering a donor roU rotates synchronously with the moving photoreceptor. By use of electric fields between the donor roU and photoreceptor, selective transfer of toner occurs. The simplicity, conciseness, and low cost of this approach enabled the introduction of throwaway copier cartridges.  [c.138]

In Fig. 5-22, the shaded areas indicate the operating regimes of a wide range of furnace types. Note the significant properties of the function presented. (1) As firing rate D goes down, the efficiency rises and approaches 1 — Ti in the limit. (This conclusion is modified if wall losses are significant.) (2) Changes in sink temperature have little effect if Ti < 0.3. (3) As the furnace walls approach complete coverage by a black sink [C i 1 in Eqs. (5-176) and (5-177)] and as convection becomes unimportant, tne effect of flame emissivity on D becomes one of inverse proportionality thus at very high firing rates at which efficiency approaches inverse proportionality to D, the efficiency of heat transfer varies directly as g (gas-turbine chambers), but at low firing rates g has relatively httle effect. (4) When C i 1 because of a nonblack sink or much refractory surface, the effecd of changing flame emissivity is to produce a much less than proportional effect on heat flux.  [c.587]

Force fields for small molecules are generally considered transferable, the transfer-ability being attained by the use of various cross terms in the potential energy function. Typically, a set of model compounds representing a type of functional group (e.g., azo compounds or bicarbamates) is selected. Parameters corresponding to the functional group are then optimized to reproduce the available target data for the selected model compounds. Those parameters are then transferred to new compounds that contain that functional group but for which unique chemical connectivities are present (see the ethane-to-butane example above). A recent comparison of several of the small-molecule force fields discussed above has shown this approach to yield reasonable results for conformational energies however, in all cases examples exist of catastrophic failures [52]. Such failures emphasize the importance of user awareness when a force field is being applied to a novel chemical system. This awareness includes an understanding of the range of functional  [c.16]

COMPBRN in is a single-room zone fire model for probabilities risk as.sessment calculations. It models fires in an open or closed compartment using a 2-layer zone model approach. Thermal radiation and flame propagation are included. It requires a large amount of input room geometry ventilation, doorway information, fuel bed geometry, orientation, thermal and combustion properties, ignition fuel location and properties, ignition temperatures of fuel, burning rate as a function of incident heat flux (surface-controlled burning) or ventilation (ventilation-controlled burning), and a definition of which fuel elements exchange thermal radiation with each other and with ceiling and walls. It outputs total mass burning rate, total heat release rate, hot gas layer temperature and depth, indication of fuel cell damage and burning, radiative and total heat fluxes to targets, fuel cellmass, flame height over each fuel cell, flame temperature over each fuel cell, fuel cell temperature, and heat transfer coefficient (convective) for each cell. It only is applicable to single-room, pre-flashover fire compartments. Quasi-steady state assumptions are made it is highly  [c.367]

See pages that mention the term Transfer function approach : [c.722]    [c.887]    [c.2223]    [c.2226]    [c.245]    [c.522]   
Advanced control engineering (2001) -- [ c.41 , c.63 ]