937 resultados para Data quality control


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DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT

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Every year production volume of castings grows, especially grows production volume of non-ferrous metals, thanks to aluminium. As a result, requirements to castings quality also increase. Foundry men from all over the world put all their efforts to manage the problem of casting defects. In this article the authors present an approach based on the use of cognitive models that help to visualize inner cause-and-effect relations leading to casting defects in the foundry process. The cognitive models mentioned comprise a diverse network of factors and their relations, which together thoroughly describe all the details of the foundry process and their influence on the appearance of castings’ defects and other aspects.. Moreover, the article contains an example of a simple die casting model and results of simulation. Implementation of the proposed method will help foundry men reveal the mechanism and the main reasons of casting defects formation.

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The purpose of the work is to claim that engineers can be motivated to study statistical concepts by using the applications in their experience connected with Statistical ideas. The main idea is to choose a data from the manufacturing factility (for example, output from CMM machine) and explain that even if the parts used do not meet exact specifications they are used in production. By graphing the data one can show that the error is random but follows a distribution, that is, there is regularily in the data in statistical sense. As the error distribution is continuous, we advocate that the concept of randomness be introducted starting with continuous random variables with probabilities connected with areas under the density. The discrete random variables are then introduced in terms of decision connected with size of the errors before generalizing to abstract concept of probability. Using software, they can then be motivated to study statistical analysis of the data they encounter and the use of this analysis to make engineering and management decisions.

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The concept of the quality control circle (QCC) has worked well in Japanese industry in increasing efficiency, production, and profits. The author explores the QCC, its history and advantages, and tells how it could be adapted quite easily and effectively to the hospitality industry

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BACKGROUND: Although most gastrointestinal stromal tumours (GIST) carry oncogenic mutations in KIT exons 9, 11, 13 and 17, or in platelet-derived growth factor receptor alpha (PDGFRA) exons 12, 14 and 18, around 10% of GIST are free of these mutations. Genotyping and accurate detection of KIT/PDGFRA mutations in GIST are becoming increasingly useful for clinicians in the management of the disease. METHOD: To evaluate and improve laboratory practice in GIST mutation detection, we developed a mutational screening quality control program. Eleven laboratories were enrolled in this program and 50 DNA samples were analysed, each of them by four different laboratories, giving 200 mutational reports. RESULTS: In total, eight mutations were not detected by at least one laboratory. One false positive result was reported in one sample. Thus, the mean global rate of error with clinical implication based on 200 reports was 4.5%. Concerning specific polymorphisms detection, the rate varied from 0 to 100%, depending on the laboratory. The way mutations were reported was very heterogeneous, and some errors were detected. CONCLUSION: This study demonstrated that such a program was necessary for laboratories to improve the quality of the analysis, because an error rate of 4.5% may have clinical consequences for the patient.

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Microneedles (MNs) are emerging devices that can be used for the delivery of drugs at specific locations1. Their performance is primarily judged by different features and the penetration through tissue is one of the most important aspects to evaluate. For detailed studies of MN performance different kind of in-vitro, exvivo and in-vivo tests should be performed. The main limitation of some of these tests is that biological tissue is too heterogeneous, unstable and difficult to obtain. In addition the use of biological materials sometimes present legal issues. There are many studies dealing with artificial membranes for drug diffusion2, but studies of artificial membranes for Microneedle mechanical characterization are scarce3. In order to overcome these limitations we have developed tests using synthetic polymeric membranes instead of biological tissue. The selected artificial membrane is homogeneous, stable, and readily available. This material is mainly composed of a roughly equal blend of a hydrocarbon wax and a polyolefin and it is commercially available under the brand name Parafilm®. The insertion of different kind of MN arrays prepared from crosslinked polymers were performed using this membrane and correlated with the insertion of the MN arrays in ex-vivo neonatal porcine skin. The insertion depth of the MNs was evaluated using Optical coherence tomography (OCT). The implementation of MN transdermal patches in the market can be improved by make this product user-friendly and easy to use. Therefore, manual insertion is preferred to other kind of procedures. Consequently, the insertion studies were performed in neonatal porcine skin and the artificial membrane using a manual insertion force applied by human volunteers. The insertion studies using manual forces correlated very well with the same studies performed with a Texture Analyzer equipment. These synthetic membranes seem to mimic closely the mechanical properties of the skin for the insertion of MNs using different methods of insertion. In conclusion, this artificial membrane substrate offers a valid alternative to biological tissue for the testing of MN insertion and can be a good candidate for developing a reliable quality control MN insertion test.

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The construction industry requires quality control and regulation of its contingent,unpredictable environment. However, taking too much control from workers candisempower and demotivate. In the 1970s Deci and Ryan developed selfdeterminationtheory which states that in order to be intrinsically motivated, threecomponents are necessary - competence, autonomy and relatedness. This study aimsto examine the way in which the three ‘nutriments’ for intrinsic motivation may beundermined by heavy-handed quality control. A critical literature review analysesconstruction, psychological and management research regarding the control andmotivation of workers, using self-determination theory as a framework. Initialfindings show that quality management systems do not always work as designed.Workers perceive that unnecessary, wasteful and tedious counter checking of theirwork implies that they are not fully trusted by management to work without oversight.Control of workers and pressure for continual improvement may lead to resistanceand deception. Controlling mechanisms can break the link between performance andsatisfaction, reducing motivation and paradoxically reducing the likelihood of thequality they intend to promote. This study will lead to a greater understanding ofcontrol and motivation, facilitating further research into improvements in theapplication of quality control to maintain employee motivation.

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Mammography equipment must be evaluated to ensure that images will be of acceptable diagnostic quality with lowest radiation dose. Quality Assurance (QA) aims to provide systematic and constant improvement through a feedback mechanism to address the technical, clinical and training aspects. Quality Control (QC), in relation to mammography equipment, comprises a series of tests to determine equipment performance characteristics. The introduction of digital technologies promoted changes in QC tests and protocols and there are some tests that are specific for each manufacturer. Within each country specifi c QC tests should be compliant with regulatory requirements and guidance. Ideally, one mammography practitioner should take overarching responsibility for QC within a service, with all practitioners having responsibility for actual QC testing. All QC results must be documented to facilitate troubleshooting, internal audit and external assessment. Generally speaking, the practitioner’s role includes performing, interpreting and recording the QC tests as well as reporting any out of action limits to their service lead. They must undertake additional continuous professional development to maintain their QC competencies. They are usually supported by technicians and medical physicists; in some countries the latter are mandatory. Technicians and/or medical physicists often perform many of the tests indicated within this chapter. It is important to recognise that this chapter is an attempt to encompass the main tests performed within European countries. Specific tests related to the service that you work within must be familiarised with and adhered too.

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This document does NOT address the issue of oxygen data quality control (either real-time or delayed mode). As a preliminary step towards that goal, this document seeks to ensure that all countries deploying floats equipped with oxygen sensors document the data and metadata related to these floats properly. We produced this document in response to action item 14 from the AST-10 meeting in Hangzhou (March 22-23, 2009). Action item 14: Denis Gilbert to work with Taiyo Kobayashi and Virginie Thierry to ensure DACs are processing oxygen data according to recommendations. If the recommendations contained herein are followed, we will end up with a more uniform set of oxygen data within the Argo data system, allowing users to begin analysing not only their own oxygen data, but also those of others, in the true spirit of Argo data sharing. Indications provided in this document are valid as of the date of writing this document. It is very likely that changes in sensors, calibrations and conversions equations will occur in the future. Please contact V. Thierry (vthierry@ifremer.fr) for any inconsistencies or missing information. A dedicated webpage on the Argo Data Management website (www) contains all information regarding Argo oxygen data management : current and previous version of this cookbook, oxygen sensor manuals, calibration sheet examples, examples of matlab code to process oxygen data, test data, etc..

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This study addresses the effects of gamma irradiation (1, 5 and 8 kGy) on color, organic acids, total phenolics, total flavonoids, and antioxidant activity of dwarf mallow (Malva neglecta Wallr.). Organic acids were analyzed by ultra fast liquid chromatography (UFLC) coupled to a photodiode array (PDA) detector. Total phenolics and flavonoids were measured by the Folin-Ciocalteu and aluminium chloride colorimetric methods, respectively. The antioxidant activity was evaluated based on the DPPH(•) scavenging activity, reducing power, β-carotene bleaching inhibition and thiobarbituric acid reactive substances (TBARS) formation inhibition. Analyses were performed in the non-irradiated and irradiated plant material, as well as in decoctions obtained from the same samples. The total amounts of organic acids and phenolics recorded in decocted extracts were always higher than those found in the plant material or hydromethanolic extracts, respectively. The DPPH(•) scavenging activity and reducing power were also higher in decocted extracts. The assayed irradiation doses affected differently the organic acids profile. The levels of total phenolics and flavonoids were lower in the hydromethanolic extracts prepared from samples irradiated at 1 kGy (dose that induced color changes) and in decocted extracts prepared from those irradiated at 8 kGy. The last samples also showed a lower antioxidant activity. In turn, irradiation at 5 kGy favored the amounts of total phenolics and flavonoids. Overall, this study contributes to the understanding of the effects of irradiation in indicators of dwarf mallow quality, and highlighted the decoctions for its antioxidant properties.