Degradation measurement, parameters

The second method uses dynamic limits that monitor the rate of change in the measurement parameters. This type of monitoring can detect minor deviations in the rate that a machine or system is degrading and anticipate when an alarm will be reached. The use of dynamic limits will greatly enhance the automatic diagnostic capabilities of a predictive maintenance system and reduce the manual effort required to gain maximum benefits. 

The changes that occur after the heat processing of food systems are often monitored by different parameters, such as total carotenoid content (and therefore isomerization and oxidation are underestimated), individual carotenoids (overall changes may be missed), and CIELAB color parameters (no information on carotenoid degradation mechanism). The data given in Table 12.3 reflects the influence of matrix composition, food state (liquid or solid), and measured parameter on the carotenoid degradation kinetics. 

Since these indicators are given in different scales it is necessary to convert them into the specific quantities which are expressed in the same scale. Convolution of these indicators wills represent an integral measuring parameter which will reflect the total quality of the system. Any degradation of the system will lead to the decrease of Sustainability Index. 

One conclusion from Fig. 15.3 is that our idea to use easily measurable parameters to predict in-situ degradation rates is not principally wrong. However, this survey has demonstrated that existing methods applied in the field studies do not provide a quantitative approach to model degradation rates. One of the major reasons that our attempt failed is the lack of reliable data. Most data sets were incomplete with respect to the relevant redox chemical parameters. In some cases not even the pH was specified... 

To determine the behavior of a product, it must be stored at known conditions for a period of time and its properties measured. In the case of oxidation, for example, some method must be available to determine the amount of reaction with oxygen that the product has undergone. This is often done by measuring peroxide values for oil-containing products, or hexanal values for products that have hexanal as the end degradation product for oxidation. For moisture sorption, the product can be stored over a saturated salt solution until moisture uptake is at equilibrium. Then taste or texture is often the measured parameter to determine the end-point of shelf life. For pharmaceuticals, the true end-point is determined by the bioavailability of the drug. 

Ageing effects may be detected by a change in measurable parameters. For example, increase in temperature or pressure may be an indication of die accumulation of corrosion products in the tube of a heat-exchanger and instrument drift may be an indication of electronic component degradation. Parameters should be measured periodically in a consistent manner and the readings should be compared and assessed. Physical parameters, such as temperature, pressure, flow rate, control rod drop times, radiation level (e.g. neutron and gamma), water quality, are indicators of the state of a system, structure or component. 

A valuable approach for measuring thermal degradation kinetic parameters is controlled-transformation-rate thermal analysis (CRTA) - a stepwise isothermal analysis and quasi-isothermal and quasi-isobaric method. In this method, some parameters follow a predetermined programme as functions of time, this being achieved by adjusting the sample temperature. This technique maintains a constant reaction rate, and controls the pressure of the evolved species in the reaction environment. CRTA is, therefore, characterised by the fact that it does not reqnire the predetermined temperature programmes that are indispensable for TG. This method eliminates the nnderestimation and/or overestimation of kinetic effects, which may resnlt from an incomplete understanding of the kinetics of the solid-state reactions normally associated with non-isothermal methods. 

Sewer Disposal. Photoprocessing and printing wastes tend to be aqueous solutions that ate combined with other plant effluents and sent to the local sewer plant for treatment. The parameters of concern include silver, pH, and biological oxygen demand (BOD). BOD is a measure of how well a waste material degrades in the environment. Lower values ate preferred. Silver-bearing waste streams ate typically treated on-site, and the treated effluent is released to the drain. The printer usually receives a small cash credit for silver recovered. 

In order to evaluate the extent of attrition and its impact on the particle size distribution, there is a need of a qualitative and quantitative characterization. This, however, is not as simple as it may seem at first. There are many different properties, parameters and effects that manifest themselves and could be measured. In addition, as will be shown, the choice of the assessment procedure is strongly connected with the definition of attrition which, on its part, depends on the degradation mechanism that is considered to be relevant to the process. Hence there are a lot of procedures and indices to characterize the process of particle attrition. Section 3 deals with those which are relevant to fluidized beds and pneumatic conveying lines. 

---