Passive experiments

The active-experiment approach is usually applicable in laboratory conditions. In fact, this is the major area of application of the methods of the experimental design. In the case where the experimenter is not able to control the input variables, one deals with a passive experiment. In this case, the experimenter is presumed able to measure, with negligible error, the values of the input variables (or factors) as well as the values of the output variables, i.e., the responses. In this case, it is also possible for the principles of experimental design to be applied [2], Passive experiments are common in process analysis where the user has little or no control over the process variables under investigation. 

Two types of experiments can produce the data needed to establish statistical models. Passive experiments refer to the classical analysis of an experimental process investigation. They occur when the sets of experiments have been produced (in an industrial or in a pilot unit) either by changing the values of independent process variables one by one or by collecting the statistical materials obtained with respect to the evolution of the investigated process. Active experiments will be produced after the establishment of a working plan. In this case, the values of each of the independent variables of the process used for each planned experiment are obtained by specific fixed procedures. 

The MISSE experiments use a PEC (Passive Experiment Container) which is essentially a simple suitcase that houses the samples (Fig. 1). The PEC is launched as a closed container where the samples are located on the inside, and is then attached to the ISS during a spacewalk and opened fully inside-out to... 

Since the piezoelectric materials are responsive it represented an opportunity to conduct active experiments, collect real-time data and evaluate the performance of these materials in space. MISSE-6 is the first time that active remote experiments have been part of the MISSE project. Both active and passive experiments are flown allowing for a range of experiments and materials to be tested over the course of the exposure (estimated at 6-8 months, depending on the Shuttle flight program for sample recovery). 

During a passive experiment, the test officer acts as an observer, who can only register the values of independent and dependent variables. 

Table 1. Self-Passivation Experiment Erosion Depths...

H.H. Uhlig, History of Passivity, Experiments and Theories, Passivity of Metals, R.P. Frankenthal and J. Kruger, Ed., The Electrochemical Society, 1978, p 1-28... 

Similar passivation experiments at slow scan rate were carried out on MS panels in identical solutions also as per test plan given in Table 4.11. Result compared with corresponding field exposed panels. Polarisation curves are given in Figs. 4.18, 4.19, 4.20, 4.21, 4.22. 

Sometimes the experiment is conducted such that the independent variables are not, or cannot be, controlled. This usually happens in unplanned or passive experiments where samples or objects are measured as they come this type of the experiment may be easier or less expensive to run, but it requires a greater number of measurements to be taken. 

D and v vary with temperature and must be experimentally determined. At passivation, lum should be greater than or equal to the critical passivation current (/cnt). The fcrit values were measured from the polarization curves of steel RDEs in (NH4)4EDTA at various pH values, temperatures, and [EDTA]. When actual passivation experiments were conducted, lum at passivation was also estimated. The relationship between these current densities (CDs) should reveal important information concerning the passivation reaction. 

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