Time-Saving Techniques

The careful selection of an integration algorithm is not the only means of conserving computer resources in molecular dynamics. In this section we shall discuss two devices that can save a significant amount of computer time during the generation of a phase space trajectory equilibration on subsystems and bookkeeping. 

In some molecular dynamics work, the process of equilibration has accounted for a substantial fraction of the total computer time devoted to the calculation. If the intermolecular potential has a sufficiently short range, however, it is possible to use only a fraction of the molecular dynamics system for equilibration. One can set aside a subsystem containing, say, an eighth of the total number of molecules, select initial conditions, and allow the 

An alternative bookkeeping scheme has recently been proposed. In this method, the molecular dynamics box is divided into a number of small cells. At the beginning of each time step, the particular molecules in each cell are listed. The cells are then scanned, and relative distances are calculated only for pairs of molecules in neighboring cells. In this method the time required at each step is always proportional to N. Thus, as the number of particles in the system increases, this method should become faster than the older bookkeeping method. 

One of the important parameters in this form of bookkeeping is the size of the cell V. There is a trade off between cycle time and accuracy. This procedure only includes interactions between particles in nearest-neighbor cells. If u / is less than or equal to the interaction range, then important interactions will be missed. On the other hand, if v is large so that on the average a large fraction of the N particles occupy each cell, the procedure becomes as inefficient as if no bookkeeping were used. The optimum value of v has been located in an 

The use of bookkeeping procedures will in general yield dramatic reduction in the consumption of computer time in molecular dynamics and can therefore greatly increase the scope of such calculations. 

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Employ time-saving techniques as much as possible. 

Finally, it should be mentioned that Alvarado et al. (1980) used a carbide steel brush to prepare a clean Yb surface, which has the advantage of being a time saving technique. 

Synthesis, analysis and reactivity reactions and methods appropriate for high school microscale chemistry time-saving techniques, inventory control, safety and disposal. 

Coking cycle time, 49-70 human factors, 50 time-saving techniques, 50-51 switching feed between drums, 51-53 vapor valve operation, 53 water feed drain, 53 water filling, 54-56 decoking crew, 56-57 unheading, 57-59 resid line to bottom head, 59 bot-... 

Therefrom follows the dimensionality of the IRC (atomic mass) A and the necessity to define it as the MERP on the mass-weighted PES. By integrating the Eqs. (1.27) on condition that p = 0 at every point (the condition of infinitesimal velocity of motion along the MERP defined by the IRC) or using some other computer-time saving techniques [34,62], the IRC can be calculated. 

The projection reconstruction (PR) method originates from imaging techniques [43, 44] and is based on the projection theorem [45, 46]. The technique has recently attracted considerable interest in multi-dimensional NMR spectroscopy [47-49], especially in the field of protein NMR [2—4,17-19]. It is a particularly efficient time saving technique that works amazingly well with sparse spectra and medium size proteins. The technique has been applied in combination with the 2D/3D (HA)CA CO N NH experiment to a small protein, GBl [36]. The three-dimensional experiment was recorded in just 15 min. The three-dimensional spectrum was reconstructed from three planes - two orthogonal planes and a tilted plane recorded at an optimum projection angle of 69.5°. Figure 21 shows the comparison of the... 

The use of NMR spectroscopy to evaluate potential aryl fluoride monomers as candidates for nucleophilic aromatic substitution polymerization has shown to be an accurate and time saving technique. Since the shift is controlled by the electron density of the carbon to which it is attached, the magnitude of the F chemical shift can... 

A procedure for proplnts is presented by J.W. French (Ref 27), who used both OM and EM (electron microscope) to study plastisol NC curing. He found that the cure time of plastisol NC is a logarithmic function of temp, and direct functions of chemical compn and total available surface area, as well as of particle size distribution. It should be noted that extensive use of statistics is required as a time-saving means of interpreting particle size distribution data. The current state-of-the-art utilizes computer techniques to perform this function, and in addition, to obtain crystal morphology data (Ref 62)... 

CE has been used for the analysis of anionic surfactants [946,947] and can be considered as complementary to HPLC for the analysis of cationic surfactants with advantages of minimal solvent consumption, higher efficiency, easy cleaning and inexpensive replacement of columns and the ability of fast method development by changing the electrolyte composition. Also the separation of polystyrene sulfonates with polymeric additives by CE has been reported [948]. Moreover, CE has also been used for the analysis of polymeric water treatment additives, such as acrylic acid copolymer flocculants, phosphonates, low-MW acids and inorganic anions. The technique provides for analyst time-savings and has lower detection limits and improved quantification for determination of anionic polymers, compared to HPLC. 

Hyphenation of chromatographic separation techniques (SFC, HPLC, SEC) with NMR spectroscopy as a universal detector is one of the most powerful and time-saving new methods for separation and structural elucidation of unknown compounds and molecular compositions of mixtures [171]. Most of the routinely used NMR flow-cells have detection volumes between 40... 

These results obtained from the analyses of industrial blends proved that the identification of the constituents of the different surfactant blends in the FIA-MS and MS-MS mode can be performed successfully in a time-saving manner only using the product ion scan carried out in mixture analysis mode. The applicability of positive ionisation either using FIA-MS for screening and MS-MS for the identification of these surfactants was evaluated after the blends examined before were mixed resulting in a complex surfactant mixture (cf. Fig. 2.5.7(a)). Identification of selected mixture constituents known to belong to the different blends used for mixture composition was performed by applying the whole spectrum of analytical techniques provided by MS-MS such as product ion, parent ion and/or neutral loss scans. 

Results obtained by LC should be discussed in comparison with the identification that could be achieved by the time-saving FIA-MS and MS-MS technique. With the application of time-consuming LC separations, many problems observed in the determination and identification of the constituents of complex mixtures can be solved. The problems that were still observable under these improved possibilities of column separation applied to this commercially available household detergent formulation become obvious with the discussion of results presented in Fig. 2.5.11. 

Advanced composition and production methods developed by Noyes Data Corporation are employed to bring this durably bound book to you in a minimum of time. Special techniques are used to close the gap between "manuscript" and "completed book." In order to keep the price of the book to a reasonable level, it has been partially reproduced by photo-offset directly from the original reports and the cost saving passed on to the reader. Due to this method of publishing, certain portions of the book may be less legible than desired. 

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