Control scenario

Develop an episode control scenario for a single large coal-fired steam electric generating station. 

Figure 2. Optimal laser fields for the control scenario in Fig. 1. The solid line is the globally optimal laser field. The dashed line is the locally optimal Gaussian field.

RACMO HadAM3H A2 Control/Scenario RACMO H/RACMO H A2... 

Although such tendencies are often viewed individually or by segments, it also appears that generalizations can even be made across some country segments. For instance, it appears that Germans are much more influenced by their attitudes toward risk than by their actual perceptions of risk. In a controlled scenario-based study involving consumers from Germany, The Netherlands, and the United States, these consumers were asked the extent to which they would consume beef under four different risk scenarios in... 

Comparing value scenarios like exchange rate, sales price, elasticity and procurement price experiments with the control scenarios, value scenario influence on profits and volumes is significantly higher than the influence of volume control scenario experiments in the specific case. 

Reactor loss of control scenarios and lines of defense... 

We have demonstrated a strong-held control scenario based on the SPODS. We derived the theoretical background in terms of both classical physics and quantum mechanics. We showed tunability of this bidirectional Stark effect up to nearly 300 meV, a selectivity of almost up to 100% and a precision down to the sub-10 as regime experimentally on atoms and molecules with a theoretical efficiency up to 100%. 

In particular, note that many of our proposed control scenarios provide the experimentalist with a clear-cut statement of which parameters need to be varied to achieve control. Further, they tend to utilize relatively simple laser pulse (or CW) characteristics. Thus, our approach would apply to larger molecules in the same way as to smaller molecules that is, the experimentalist needs only to vary the indicated parameters (e.g., laser intensities, phases, etc.) and search for control in this parameter space. 

Control over the product branching ratio in the photodissociation of Na2 into Na(3s) + Na(3p), and Na(3s) + Na(3d) is demonstrated using a two-photon incoherent interference control scenario. Ordinary pulsed nanosecond lasers are used and the Na2 is at thermal equilibrium in a heat pipe. Results show a depletion in the Na(3d) product of at least 25% and a concomitant increase in the Na(3p) yield as the relative frequency of the two lasers is scanned. 

The fact that this control scenario does not require laser coherence makes it especially attractive for laboratory use since generally available, non-transform limited, nsec dye lasers can be used. In our experiment we use two dye lasers pumped by a frequency-doubled Nd-Yag laser. One dye laser, whose frequency a>2 was tuned between 13,312 cm- and 13,328 cm-1, was used... 

The essential principle of coherent control in the continuum is to create a linear superposition of degenerate continuum eigenstates out of which the desired process (e.g., dissociation) occurs. If one can alter the coefficients a of the superposition at will, then the probabilities of processes, which derive from squares of amplitudes, will display an interference term whose magnitude depends upon the a,. Thus, varying the coefficients a, allows control over the product properties via quantum interference. This strategy forms the basis for coherent control scenarios in which multiple optical excitation routes are used to dissociate a molecule. It is important to emphasize that interference effects relevant for control over product distributions arise only from energetically degenerate states [7], a feature that is central to the discussion below. 

Control over the a, and production of the desired superposition states can be achieved by several routes. One nice way is to utilize the reactants from an earlier photodissociation step, altering the af by any of a number of coherent control scenarios [2] for this piereactive step. Consider then preparing n, 0) via a prereactive stage in which an adduct AB, made up of a structureless atom A and the molecular fragment B, is photodissociated. The AB is assumed to be initially in a pure state of energy Eg and the photodissociation is carried out with a coherent source. Under these circumstances photodissociation produces B in a linear combination of internal states. For... 

Models describing the transport of electrons in molecular junctions have been shown to be quite powerful. Here the emphasis was put on time-dependent effects which can, for example, be triggered by external laser fields. If these fields are strong, a non-perturbative treatment of the laser-matter interaction is of large importance and is included in the presented TL QME. Also the connection of transport through molecular wires or coherent laser control scenarios may play an important role in the future. 

An intuitive method for controlling the motion of a wave packet is to use a pair of pump-probe laser pulses, as shown in Fig. 13. This method is called the pump-dump control scenario, in which the probe is a controlling pulse that is used to create a desired product of a chemical reaction. The controlling pulse is applied to the system just at the time when the wave packet on the excited state potential energy surface has propagated to the position of the desired reaction product on the ground state surface. In this scenario the control parameter is the delay time r. This type of control scheme is sometimes referred to as the Tannor-Rice model. 

The numerator and denominator of Eq. (3.54) each display the canonical form for coherent control, that is, a form similar to Eq. (3.19) in which there are independent contributions from more than one route, modulated by an interference term. Since the interference term is controllable through variation of the (x and 3 — 3 < />,) laboratory parameters, so too is the branching ratio Rqq,(E). Thus, the principle upon which this control scenario is based is the same as that in Section 3.1, but the interference is introduced in an entirely different way. 

In particular, we reconsider the bichroraatic control scenario discussed in Section 3.1.1, assiuning, however, that the molecules are in solution at temperature T. Further, we irradiate the system so as to saturate the ,) to E2) transition and simultaneously photodissociate the system. 

Thus we see that, although collisional effects do reduce the degree of controlji relative to the collision-free case, saturation pumping of superposition in the bichro- ) matic control scenario can be used to overcome collisional effects up to somejli reasonable temperature. 

For cw lasers, laser decoherence appears via the jitter and drift of the laser phase in the field E(z,t) [e.g., Eq. (3.16)] with a concomitant reduction in control (see Section 5.3). However, suitable design of the control scenario can result in a method that is immune to the effects of laser jitter. In particular, to do so we rely upon the way in which the laser phase enters into control scenarios. 

The role of the laser phase in controlling molecular dynamics was clear in the examples shown in Chapter 3, For example, in the one- vs. three-photon scenario the relative laser phase (3 — 3c/>,) enters directly into the interference term [see, e.g., Eq. (3.53)], as does the relative phase ((frl — (j>2) in the bichromatic control scenario [Eq. (3.19)]. These residts embody two useful general rules about the contribution of the laser phase to coherent control scenarios. The first is that the interference term contains the difference between the laser phase imparted to the molecule by one route, and that imparted to the molecule by an alternate route. Second, the phase imparted to the state Em) by a light field of the form ... 

The first panel of Figure 5.12 shows the bichromatic control scenario. The sec panel shows the simplest path to the continuum, consisting of one-photon absorpt of CO]. The subsequent panels show the three-photon process to the contir (absorption of a> followed by stimulated emission and reabsorption of coj, ctc ... 

Figure 6.1 Resonantly enhanced two-photon vs. two-photon control scenarios (a) using J four frequencies and (h) using three frequencies. /...

This control scenario is not limited to the specific frequency scheme discusi above. Essentially all that is required is that two or more resonantly enhaw photodissociation routes interfere and that the cumulative laser phases of the routes be independent of laser jitter. As one sample extension, consider the ci... 

Photodissociation is but one of many processes that are amenable to control. A host of other processes that have been studied are discussed later in this book, such as > asymmetric synthesis, control of bimolecular reactions, strong-field effects, and so forth. Also of interest is control of nonlinear optical properties of materials [203],i particularly for device applications. In this section we describe an application of thfrj bichromatic control scenario discussed in Section 3.1.1) to the control of refractive indices. riff... 

Examination of Eq. (6.21) shows that y(a>) is comprised of two terms that are proportional to c, 2 and that are associated with the traditional contribution to the susceptibility from state 11 ) and E2) independently, plus two field-dependent terms, proportional to a -j = c cje co /eia), which results front the coherent excitation of both II ) and E2) to the same total energy E = Ex + to) = E2+ to2. As a consequence, changing au alters the interference between excitation routes and allows for coherent control over the susceptibility. As in all bichromatic control scenarios, this control is achieved by altering the parameters in the state preparation in order to affect c1,c2 and/or by varying the relative intensities of the two laser fields. Note that control over y(ciy) is expected to be substantial if e(a>j)/e(cOj) is large. However, under these circumstances control over yfro,) is minimal since the corresponding interference term is proportional to e(a>t)/e(cQj). Hence, effective control over the refractive index is possible only at one of co( or >2. 

To see the origin of the molecular phase lag in the one- vs. three-photon control scenario, we reconsider the formalism discussed in Section 3.3.2. However, for notational simplicity, we denote the set of scattering eigenstates of the full Hamiltonian at energy E and fragment quantum numbers n in channel q as E, n ), that is, we subsume the q within the labels n. 

---