Robustness approaches

If the Sohre approach is taken in a philosophical light, it clearly indicates the need for a robust design. This is true for the basic equipment as well as the installation of foundations and piping. All of the factors were considered in the approach Sohre presented, even if in some cases, they may have been considered subjective. The key to the robust approach can be simplified as low deflection. On a rotor, the shorter the bearing span and/or the heavier the shaft cross section, the lower the deflection. This tends to increase the reliability aspect. On a foundation, heavier sections tend to have lower deflection, which contributes to the ability to maintain train alignment. Better alignment is one of the factors that contributes to higher reliability. 

A multivariate normal distribution data set was generated by the Monte Carlo method using the values of variances and true flowrates in order to simulate the process sampling data. The data, of sample size 1000, were used to investigate the performance of the robust approach in the two cases, with and without outliers. 

Without outliers. The estimation of P both from the conventional indirect approach PC and from the robust approach 4/r gave similar results when compared with the target covariance matrix (P ... 

Without outliers. As shown by comparison with the target covariance, both the conventional indirect approach and the robust approach give a very good estimation of the covariance in this case ... 

The covariance matrix of measurement errors is a very useful statistical property. Indirect methods can deal with unsteady sampling data, but unfortunately they are very sensitive to outliers and the presence of one or two outliers can cause misleading results. This drawback can be eliminated by using robust approaches via M-estimators. The performance of the robust covariance estimator is better than that of the indirect methods when outliers are present in the data set. 

Let us consider the same chemical reactor as in Example 11.1 (Chen et al., 1998). Monte Carlo data for y were generated according to in order to simulate process sampling data. A window size of 25 was used here, and to demonstrate the performance of the robust approach two cases were considered, with and without outliers. 

Without outliers. The results of data reconciliation from the conventional approach Xc and from the robust approach xr are same, that is,... 

Xr from the robust approach, as expected, still gives the correct answer however, the conventional approach fails to provide a good estimate of the process variables. Although the main part of the data distribution is Gaussian, the conventional approach fails in the task because of the presence of just one outlier. In a strict sense, the presence of this outlier results in the invalidation of the statistical basis of data reconciliation,... 

Only the results for the Cauchy and symmetric contaminated distributions are shown in Figs. 13 and 14, respectively. From these figures, it is clearly shown that the robust approach consistently and successfully performs the data reconciliation, regardless of the distributions of the data. This is a very desirable property in real applications, since in most cases the distribution is unknown or known only approximately. 

In comparison to the approach of Ginski et al. [48], the Miyazaki s method appears to be more elaborate and complex and is thus coming closer to the in vivo situation. The device can simulate various effects of pH on dissolution and is, as an open system, closer to in vivo conditions compared to a closed one. However, it exhibits the drawback of not freely adjustable pH values acting on the drug. Low flow rate in the dissolution vessel may limit applications of complete dosage forms and allows predominantly only the use of granules, pellets, or grinded tablets. Furthermore, the application of compendial dissolution devices appears to be a more robust approach. 

The approach of Kataoka et al. [54] shows some desirable features, such as downsized, in vivo relevant volumes, and low complexity of the device and thus low error proneness. However, the device lacks the possibility to add complete dosage forms and the use of compendial dissolution devices would be a more robust approach. 

Remark 1. From Proposition 4, the existence of an input-output linearizing control law capable to regulate exponentially the total concentration of organic substrate St in a desired value S was demonstrated. However, in order to implement this controller in practice, a perfect knowledge of the process dynamics is required. In other words, this implies that either the influent composition St,in or the process kinetics k, /j,. ) must be perfectly known. Nevertheless, this condition is difficult to satisfy in practice limiting its application. But what about if the uncertain terms can be estimated from available measurements and a control scheme with a similar structure to that of the input-output linearizing controller (6) is used. In the next section, a robust approach is proposed based in this fact. 

Fig. 4. Block diagram of the robust approach with antiwindup action (10)...

In regard dynamics and control scopes, the contributions address analysis of open and closed-loop systems, fault detection and the dynamical behavior of controlled processes. Concerning control design, the contributors have exploited fuzzy and neuro-fuzzy techniques for control design and fault detection. Moreover, robust approaches to dynamical output feedback from geometric control are also included. In addition, the contributors have also enclosed results concerning the dynamics of controlled processes, such as the study of homoclinic orbits in controlled CSTR and the experimental evidence of how feedback interconnection in a recycling bioreactor can induce unpredictable (possibly chaotic) oscillations. 

One disadvantage of ANCOVA is that the modelling does involve a number of assumptions and if those assumptions are not valid then the approach could mislead. For example, it is assumed (usually) that the covariates affect outcome in a linear way there is invariably too little information in the data to be able to assess this assumption in any effective way. In contrast, with an adjusted analysis, assumptions about the way in which covariates affect outcome are not made and in that sense it can be seen as a more robust approach. In some regulatory circles adjusted analyses are preferred to ANCOVA for these reasons. 

Now that this mechanism is understood, relatively simple ultrashort optimal pulse shapes can be used for implementation of this robust approach for laser control of photophysical systems. 

Gutierrez GJ, Kouvelis P (1995) A robustness approach to international sourcing. Annals of Operations Research 59 165-193... 

Especially useful is the possibility of preparing conjugates of protein/STV chimeras and biotinylated DNA previous to their application in the assay, thus minimizing the amount of incubation steps required for IPCR (see also Section 2.1.4). Therefore, it could be concluded that if a custom-made protein chimera is accessible as a laboratory tool, or if the facilities and experience for preparing such a reagent are available, and additionally, no capture antibodies were needed, these conjugates allow for a very smart and robust approach to ultrasensitive protein detection by IPCR. 

In this chapter, we describe a simple and robust approach for representing and analyzing three-dimensional protein-ligand complexes called SIFt (Structural Interaction Fingerprint) [6, 7]. We will show how this method can be applied to organizing and analyzing the structural information within the protein kinase family and also how this can be applied to virtual screening for inhibitors. 

The literature focused on model-based FD presents a few applications of observers to chemical plants. In [10] an unknown input observer is adopted for a CSTR, while in [7] and [21] an Extended Kalman Filter is used in [9] and [28] Extended Kalman Filters are used for a distillation column and a CSTR, respectively in [45] a generalized Luenberger observer is presented in [24] a geometric approach for a class of nonlinear systems is presented and applied to a polymerization process in [38] a robust observer is used for sensor faults detection and isolation in chemical batch reactors, while in [37] the robust approach is compared with an adaptive observer for actuator fault diagnosis. 

The integration as illustrated in the Figure 5.1.3 is preferable for practical development and to minimize resistances and efficiency losses, while maintaining an easier and more robust approach with respect to the development of a single catalytic element able to be effective in the three steps light absorption, charge separation, and the multielectron water oxidation. 

Zhang C-X, Thormann W. Head-column field-amplified sample stacking in binary system capillary electrophoresis a robust approach providing over 1000-fold sensitivity enhancement. Anal Chem 1996 68 2523. 

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