Deliberate change

In practice, deliberate changes in flow are necessary to proportion quantities of flow into various systems, and to determine flow rate by various measuring devices by restrictions, e.g. Venturi meters and rotameters. 

By deliberately changing the pressure (in a loop), the temperature response followed immediately [1]. This proved that control of pressure is cmcial for obtaining stable temperature baselines. 

Depending on what species port was activated , i.e. which reactant stream was moved, different flow modes were available, deliberately changing the concentration profiles in a predetermined manner [17]. These flow modes were termed flow mode , inject mode and restarted flow mode , corresponding to Ni ion channel filling, ligand slug injection and Ni ion movement after slug insertion, respectively. 

Within-laboratory reproducibility studies should cover a period of three or more months and these data may need to be collected during the routine use of the method. It is possible, however, to estimate the intermediate precision more rapidly by deliberately changing the analyst, instrument, etc. and carrying out an analysis of variance (ANOVA) [9]. Different operators using different instruments, where these variations occur during the routine use of the method, should generate the data. 

Perhaps it would be most informative to study the enzymes at their respective physiological conditions, at least for the purpose of predicting the effect of pressure on a living organism. Nevertheless, deliberate changes of conditions may be valuable when pressure is used to probe structure and mechanism. As we learn to understand the role of protein structure in the determination of pressure effects, we may be able to predict the effects on one enzyme from knowledge of the effect on another. Then, we may be able to gain information about pressure effects on human enzymes. 

A method is considered to be robust when the effect of typical fluctuations in the method parameters on the outcome of the procedure is demonstrated to be negligible. Robustness is demonstrated by a test in which the effect of deliberate changes in the method parameters is studied on a number of method responses. The extent of the changes should... 

But consider what happened in the foaming example when additional foaming agents were introduced. The single factor foaming was deliberately changed. An experiment was performed. The result of the experiment clearly disproved any hypothesized causal relationship between alcohol content and foaming. 

The synthesis of a gradient copolymer is sometimes desirable in a living polymerization to produce a copolymer with a variation in composition along the polymer chain. This is achieved either by carrying out the copolymerization without addition of monomer to maintain a constant feed composition or addition of monomer to deliberately change the feed composition from its original state. 

Ability of method to remain unaffected by small variations in method parameters (some authors make the distinction be-between the property robustness and a ruggedness test in which deliberate changes are made in a method to assess the robustness)... 

Most processes are open loop stable, also called self-regulating, i.e. stable without any controllers on the system. This means that after a change in the system caused by either a disturbance or by a deliberate change in a manipulated variable, the process will come to a new stable operating condition, i.e. a new steady state. This is not necessarily the... 

Set point changes. These are deliberate changes in the operating conditions, such as a change in polymer grade for a polymerisation reactor, change in distillate composition for a distillation column, etc. 

Temperature profiles versus time were taken for different positions at the reactor tube [19]. The maximum rise in temperature was about 23 °C. Improved pressure control was exerted by using advanced pressure control electronics [19]. In the regions of large temperature increase, pressure was slightly fluctuating this effect diminished downstream. By deliberately changing pressure (in a loop), the temperature response followed immediately [19]. This proved that control of pressure is crucial for obtaining stable temperature baselines. 

Another day you can observe how you walk. On another you can systematically observe the physical distances you maintain from others in various situations. On another you can deliberately change those physical distances and see what happens. The possibilities are endless and fascinating. 

It is also useful to study an individual reaction to see how its rate is affected by deliberate changes in experimental conditions. We can determine act for example, if we measure the rate at different temperatures (Sec. 2.18). But perhaps the most valuable information about a reaction is obtained by studying the effect of changes In concentration on its rate. 

Of especial interest, therefore, are the cases in which the intermediate state, the molecular aggregate, can be retained, but where by deliberate changes in the conditions the decomposition can be brought to completion. If, for instance, zinc chloride is reacted with alcohol, an addition compound is formed on heating, decomposition sets in and in most cases follows immediately. 

Robustness is the ability of the method to withstand small, deliberate changes in the method parameters. It is evaluated by making small and deliberate changes in the method parameters and studying the effect on the system suitability requirements. These can include variations in flow rate, pH of the buffer, autosampler/column temperatures, and organic composition of the mobile phase as well as use of selective columns from different vendors. 

In contrast to the observational approach, data collection in a controlled experiment is active investigators take control of the environment and critical process parameters. By deliberate changes in key factors, the cause-and-effect relationships are forced to show themselves. 

To determine the robustness of a method, several approaches exist. Basically, the situation for robustness testing is similar to that for screening during optimization, except for the range within which the factors are examined. The influence of small but deliberate changes in parameters on the response (s) is evaluated using either an OVAT or an experimental design approach (12). 

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