Test wide error rate

Test-wide error rate remains at 5 percent... 

Biochemical oxygen demand (BOD) is one of the most widely determined parameters in managing organic pollution. The conventional BOD test includes a 5-day incubation period, so a more expeditious and reproducible method for assessment of this parameter is required. Trichosporon cutaneum, a microorganism formerly used in waste water treatment, has also been employed to construct a BOD biosensor. The dynamic system where the sensor was implemented consisted of a 0.1 M phosphate buffer at pH 7 saturated with dissolved oxygen which was transferred to a flow-cell at a rate of 1 mL/min. When the current reached a steady-state value, a sample was injected into the flow-cell at 0.2 mL/min. The steady-state current was found to be dependent on the BOD of the sample solution. After the sample was flushed from the flow-cell, the current of the microbial sensor gradually returned to its initial level. The response time of microbial sensors depends on the nature of the sample solution concerned. A linear relationship was foimd between the current difference (i.e. that between the initial and final steady-state currents) and the 5-day BOD assay of the standard solution up to 60 mg/L. The minimum measurable BOD was 3 mg/L. The current was reproducible within 6% of the relative error when a BOD of 40 mg/L was used over 10 experiments [128]. 

The value of x varies by only a small amount over a wide range of values of n, so that a representative value of x may be chosen for a material with very little loss in accuracy. This method ean therefore be used to eorrect the shear rate of single point measurements if an approximate value of n is known for the tested material. Schiimmer suggests that if a constant value of x = 0.83 is used for all materials, the error in the viscosity will be 3% or less. 

While the above four techniques are widely used in research laboratories and in field testing, other techniques have also been proposed for determining corrosion rate and investigating the mechanism of corrosion reactions from electrochemical measurements. A brief description of some of them is given here for the sake of completeness. These techniques are not widely used, and the errors involved in these techniques have not been examined. Therefore, they will not be included in the critical comparison of techniques. 

A Box-Behnken experimental design was conducted on an 80 inch wide commercial vacuum metallizer at a constant line speed using Evaporation chamber pressure, chill roll temperature and final film optical density as the three independent process variables. Table 1 lists the variable range studied and table 2 lists the experimental runs in design order. The experiment consists of 12 treatment combinations with five center points to determine the error in the measurements. During the experiment the order of the treatment combinations was randomized and the random order used to minimize any systematic error in the testing.. The response variables were oxygen transmission rate, optical density transverse variability, metal pick off with Scotch 610 and Scotch 600 tapes. 

---