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Many types of data mining methods can be used for various applications, including the analysis of materials: classification methods including decision trees, k-nearest neighbour (k-NN) and artificial neural networks (ANN); clustering methods including principal component analysis (PCA) and extensions of this such as soft independent modelling of class analogies (SIMCA), and regression methods including principal component regression (PCR) and partial least squares (PLS).
Multivariate statistical analysis methods such as principal component analysis (PCA) and soft independent modelling of class analogies (SIMCA), and regression methods including principal component regression (PCR) and partial least squares (PLS), are applied to analysis of various materials in our consultancy work. The models that are developed using calibration samples can be highly tailored to a particular application. Either Raman or wide wavelength spectroscopy may be preferred depending on the application. A number of trials have been conducted for various clients in the plastics industry to determine the additives present in certain materials and the material quality. Similar methods have been applied to electrical insulation materials in the power industry.
The surface of a material can be analysed effectively by selecting the best spectroscopic and microscopic techniques to characterise the material in question. This may include a combination of techniques to optimise results. For example changes in the surface chemistry could be analysed using FTIR spectroscopy and the topography could be established using SEM and EDX.
The ability to assess the condition of materials is vital to predict properties such as remaining lifetime, which is vital in making decisions particularly for asset management. GnoSys has experience in this area from the power sector where an aging power grid requires constant monitoring – in this case transformers which have significant value as an asset but also large costs and delays involved upon failure, thus tools that help in replacement decisions.
Novel methods – TranSpec was designed to meet the need for a portable, rapid measurement. Samples of previously failed material were used to build a calibration which can then be taken to make on-site material assessments
The method can be used to look for all sorts of changes such as thermal aging, UV degradation, hydrolysis, embrittlement.
Laboratory based – GnoSys can also use its extensive laboratory instrumentation to test material properties to assess them.
The test methods required are dependent on the properties required:
Transformer Insulation – For the purpose of undertaking broad band spectroscopic measurements directly on the windings of de-tanked transformers to determine insulation condition, a miniature spectrometer probe system was developed. The advantage of a portable system is to enable us to make direct spatial measurements on the insulated windings while they are still wrapped around the transformer core, thus enabling us to determine the dependence of paper ageing, such as degree of polymerisation (DP), and also water content on position along the windings. To interpret the spectroscopic measurements, multivariate data analysis techniques (chemometrics) are applied to the spectra to extract important information and generate models to predict the aged condition with respect to a number of material parameters such as paper type, degree of polymerisation and water content. A later development is likely to include a transmission probe to analyse the oil simultaneously with the paper analysis before the transformer is de-tanked. It may also be possible in the future to perform in-situ measurements; this will depend largely on the ease of access to the transformer windings from outside the tank.
Plastics Processing and Degradation – Wide-wavelength spectroscopic techniques can discriminate between engineering thermoplastics for sorting purposes, and they can be further used to provide a measure of “quality” of the materials in support of maximising the re-use “technical” and economic value and in the development of appropriate qualification standards. This has been done by taking two enclosure polymers, ABS and PC/ABS, and subjecting them to controlled degradation through thermal processing and light (UV) ageing, and showing that these changes can be tracked and predictions made of the mechanical and melt flow properties. The techniques can also qualify some additives in these materials including flame retardants used to reduce fire hazards, whereas the remaining additives can be qualified using Raman spectroscopy.
Companies often require quick and efficient methods to make sure their products are up to specification. The risks involved in not spotting issues early can be:
Bespoke QA and test methods are developed to suit the materials and the properties that require testing. This can be from:
QA methods can be applied right through the manufacture process:
QA is needed for:
The test methods required are dependent on the specifications required:
Gnosys have many years’ experience in QA methods and what test are required to make sure your products go out and perform in the market, protecting your reputation.
Polymers and composites can be characterised using a variety of analytical techniques, depending on the particular materials to be analysed. If the material is unknown techniques can be combined to identify the materials involved and determine concentration. Physical and chemical properties can also be characterised and performance can be predicated using multivariate analysis.
GnoSys’ background in the polymer industry both academically and industrially means they we can give expert service to polymer and composite characterisation, properties and performance. This can be for :
GnoSys are happy to work and produce work at all levels whether you have a scientific background and are looking for very specific results or from a non-scientific background and need the results broken analysed for you to meet your needs GnoSys are flexible.
This can be related to simple checks required to research projects where continued analytical support is required or where expertise is required to find the correct type of analysis.
Our materials characterisation facilities:
Performance properties – e.g. fire retardancy – LOI
Experimental design is the process of planning a study to meet specified objectives. Planning an experiment properly is very important in order to ensure that the right type of data and a sufficient sample size are available to answer the research questions of interest as clearly and efficiently as possible.
In an experiment, we deliberately change one or more process variables (or factors) in order to observe the effect the changes have on one or more response variables. The statistical design of experiments (DOE) is an efficient procedure for planning experiments so that the data obtained can be analyzed to yield valid and objective conclusions.
DOE is intimately linked with Multivariate statistical analysis - aka Chemometrics. This is the science of extracting information from chemical systems by data-driven means. It is a discipline that links many areas of scientific endeavour, using methods frequently employed in core data-analytic areas such as multivariate statistics, applied mathematics, and computer-science, but used to investigate and address problems in chemistry, biochemistry and chemical engineering. It
Our portable TranSpec Wide Wavelength equipment has been used together with multivariate calibration models to measure degradation of electrical insulation materials such as transformer insulating paper and cable and generator insulation. A special design of fibre-optic probe is required for the insulating paper analysis. Work has been undertaken in the laboratory and on site at electrical power grid stations, company laboratories and recycling facilities. For transformer paper, the method has been used to classify transformer insulation paper types, measure the degree of polymerisation, relating it to insulating properties and end of life, and also water and oil content of insulating paper.