Sequential and Simultaneous

The three principal methods of batch proportioning are accumulative, sequential, and simultaneous the best method for a given appHcation depends on the processing equipment available and the accuracy required. 

Sequential and simultaneous multi-element ultratrace detection... 

Problems related to the use of a guest dye can be reduced if the polymer contains a fluorescent chemical group. Gohil and Salem [70] took advantage of such intrinsic fluorescence to characterize the in-plane distribution of orientation in biaxially drawn PET films. In these experiments, the chain-intrinsic fluorescent label is due to the formation of dimers by two terephthalic moieties, exclusively within the noncrystalline regions. A comparison between sequential and simultaneous drawing along the MD and TD directions was undertaken for a fixed MD draw ratio of 3.5 and various TD draw ratios. The orientational order was characterized by two "orientation ratios" Rmd and RTD such that... 

Fjeld, R. A., Roane, J. E., Leyba, J. D., Paulenova, A., and DeVol, T. A., Sequential and simultaneous radionuclide separation-measurement with flow-cell radiation detection, ACSSymp. Ser., 868, 105-119, 2004. 

Umeda, T. Nishio, M., "Comparison Between Sequential and Simultaneous Approaches in Process Simulation", Ind. Eng. Chem. Proc. Design Dev. (1972) 11 153. 

The optimization model in the sequential case had 342 equations and 362 variables for the reactor flowsheet optimization (96 CPU seconds on the VAX 6320) and 200 equations and 161 variables for the energy integration (170 CPU seconds). The simultaneous optimization model (542 equations, 523 variables) was solved in 1455 CPU seconds and was initialized with the solution to the sequential model. Table I presents a comparison between the results for sequential and simultaneous modes to synthesis. A target production rate of 40,000 Ib/h is assumed for the desired product B. 

In this section, we reconsider the van de Vusse process to illustrate our synthesis approach. This example also shows the application of the unified reaction-separation-energy integration model. Comparisons are made between sequential and simultaneous modes of synthesis, and the applicability of the simplified model is verified. 

Both sequential and simultaneous calculational sequences have been proposed for the modular approach as well as the equation-oriented approach. Either the program and/or the user must select the decision variables for recycle and provide estimates of certain stream values to make sure that covergence of the calculations occurs, especially in a process with many recycle streams. Reviews by Evans and Rosen point out many of the problems and practices pertaining to flowsheeting. 

Mizuma, T., Kawashima, K., Sakai, S., Sakaguchi, S. and Hayashi, M. (2005) Differentiation of organ availability by sequential and simultaneous analyses intestinal conjugative metabolism impacts on intestinal availability in humans. Journal of Pharmaceutical Sciences, 94, 571-575. 

For ICP-AES both sequential and simultaneous as well as combined instruments are used. In sequential spectrometers special attention is given to the speed of the wavelength access and in simultaneous spectrometers to the provision of background correction facilities. In combined instruments a number of frequently used channels are fixed and with a moving detector or an integrated monochromator... 

The multielement capacity of both sequential and simultaneous ICP-AES is high as is the linear dynamic range (up to 5 orders of magnitude). It is restricted on the lower side by the limits of determination and at the higher concentrations by the... 

Fig. 101. Precision achievable in the analysis of high-temperature superconducting powders by sequential and simultaneous ICP-OES [402],...

EXAMPLE WITH RECYCLE COMPARISON OF SEQUENTIAL AND SIMULTANEOUS SOLUTION METHODS... 

For these reasons, multivariate approaches seem better. The multivariate approaches, the topic of this chapter, can be further divided into sequential and simultaneous strategies (7-9). In sequential optimization strategies, initially only a few experiments are performed and their results are used to define the next experiment(s) (7, 8,10). In simultaneous approaches, a predefined number of experiments are performed according to a well-defined experimen-... 

The description of these sequential and simultaneous reactions during transport through a soil system is accomplished using miscible displacement theory, which can be formulated for an interacting, degrading solute (e.g. an organic molecule) as (2) ... 

Clearly, these residuals are far from perfect, and thus, even though the data are known to be perfectly trilinear with two components, the sequential PARAFAC algorithm fails to find a reasonable estimate of the parameters. However, this difference between sequential and simultaneous fitting is not related to the three-way nature of the PARAFAC model. Rather it is the orthogonality of the components in principal component analysis that enables the components to be calculated sequentially. A simple two-way example will help in illustrating this. 

The important points developed in this section are that sequential IPN synthesis tends to make dual phase continuous materials. Eor both sequential and simultaneous syntheses, a metastable phase diagram can be developed to study the kinetics of phase separation and gelation, so that better control of the morphology can be attained. The thermoplastic IPNs depend on equal volume and viscosity ratios to attain the dual phase continuity. 

As rightly pointed out recently by Luque de Castro and Valcarcel [1044], the term simultaneous is not cearly defined in FIA because it has been indiscrimanately used to describe different alternatives. Hence, in their paper, they attempted to establish the difference between multidetection and multidetermination, and the sequential and simultaneous variants of each of these, arriving at the following definitions ... 

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