Primary subsystems

The expanded system contains one additional subsystem - a catalytic recombining unit. 

Our basic system relies on good workmanship and design, and proper operation to supply a very pure hydrogen stream. A well-designed and well built electrolyzer will produce, at the very least, industrial grade hydrogen. The only contaminants that should need to be removed are particulates and liquid aerosols. 

The expanded system uses a catalytic recombiner to further purify the hydrogen gas stream from oxygen contamination. If you use a catalytic recombiner, the system has to be purged with nitrogen to move the air out of the system. The catalytic recombiner should provide a very pure gas. 

Another element that could be included in the system is a chemical or mechanical dryer to further remove moisture from the hydrogen, if this is desirable. Most commercial gas is delivered dry. Gas from the electrolyzer will tend to have quite a bit of moisture in it. Coalescers and filters will help to remove moisture. 

This system was designed for use with an intermittent renewable energy Electrolyzer specific photovoltaic 

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The FDA also use a systems approach when auditing device manufacturing sites. This breaks down the GMP requirements for devices into seven primary subsystems consisting of ... 

Continuum models remove the difficulties associated with the statistical sampling of phase space, but they do so at the cost of losing molecular-level detail. In most continuum models, dynamical properties associated with the solvent and with solute-solvent interactions are replaced by equilibrium averages. Furthermore, the choice of where the primary subsystem ends and the dielectric continuum begins , i.e., the boundary and the shape of the cavity containing the primary subsystem, is ambiguous (since such a boundary is intrinsically nonphysical). Typically this boundary is placed on some sort of van der Waals envelope of either the solute or the solute plus a few key solvent molecules. 

The SES, ESP, and NES methods are particularly well suited for use with continuum solvation models, but NES is not the only way to include nonequilibrium solvation. A method that has been very useful for enzyme kinetics with explicit solvent representations is ensemble-averaged variational transition state theory [26,27,87] (EA-VTST). In this method one divides the system into a primary subsystem and a secondary one. For an ensemble of configurations of the secondary subsystem, one calculates the MEP of the primary subsystem. Thus the reaction coordinate determined by the MEP depends on the coordinates of the secondary subsystem, and in this way the secondary subsystem participates in the reaction coordinate. 

The secondary subsystem might be treated differently from the primary one both in terms of the potential energy surface and the dynamics. For example, with regard to the former aspect, the primary subsystem might be treated by a quantum mechanical electronic structure calculation, and the secondary subsystem might be treated by molecular mechanics [68] or even approximated by an electrostatic field or a continuum model, as in implicit solvation modeling [69]. The par-... 

In the equilibrium solvation path (ESP) approximation [74, 76], ve first find a potential of mean force surface for the primary subsystem in the presence of the secondary subsystem, and then we finish the calculation using this free energy surface. Notice a critical difference from the SES in that now we find the MEP on U rather than V, and we now find solute vibrational frequencies using U rather than V. 

In the equilibrium-secondary-zone approximation [82, 85] we refine the effective potential along each reaction path by adding the charge in secondary-zone free energy. Thus, in this treatment, we include additional aspects of the secondary subsystem. This need not be more accurate because in many reactions the solvation is not able to adjust on the time scale of primary subsystem barrier crossing [86]. 

In stage 1, all atoms are treated on an equal footing. However in stage 2, the system is divided into Aj primary-zone atoms and N2 secondary-zone atoms. For each a, the N2 secondary-zone atoms are frozen and the N primary-zone atoms are optimized to the nearest saddle point, then a MEP is calculated, again with N2 atoms frozen. In both steps, the secondary-zone atoms are not neglected they provided an effective potential field that is included in the Hamiltonian. Continuing in this fashion, we calculate a free energy of activation profile AG (7 ) for the primary subsystem in the effective field of the secondary subsystem this is reminiscent of the method in Section 5.3.1. Then... 

WSC hardware consists of three primary subsystems computing equipment per se, power-distribution systems, and cooling infrastructure. A brief description of each subsystem follows below. 

The rest of this Status Rei)ort d( scril)es in greater detail each of the individual systeuns of the current snapshot of the DaDar d(d,ector, including alternatives to the primary subsystem choices, where indicat( d. The Ri port, concludes with a synopsis of the i )hysics opj)ortunities, in the study of CP violation and beyond, and with a s( ction on costs and schedule . 

QM/MM-LPS Combined quantum-mechanics/molecular mechanics with large primary-subsystem... 

When applying EA-VTST to enzyme reactions, another kind of system/ environment separation is made. Here the reactive system is considered to be the substrate and perhaps part of the enzyme or coenzyme (and perhaps including one or two closely coupled water molecules), and the environment is the rest of the substrate-coenzyme-enzyme complex plus the (rest of the) surrounding water. In what follows we will sometimes call the reactive system the primary subsystem and the environment as the secondary subsystem. For the treatment of reactions in liquids that was presented earlier, the solvent was replaced by a homogeneous dielectric medium, which greatly simplifies the calculation. For enzyme-catalyzed reactions, we treat the environment explicitly at the atomic level of detail. 

The first step of stage 2 treats the system and its environment together, without distinction, as a supersystem. In all subsequent steps (that is, in step two of stage 1 and in stage 2 as well as the optional stage 3), the N-atom system is divided into two subsystems, a primary subsystem with Nj atoms and secondary subsystem with N2 atoms, such that... 

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