958 resultados para Vacuum Packaging
Resumo:
The pectus excavatum treatment has two different approaches: non-surgical techniques (modified dynamic thoracic compressor, exercises and the vacuum bell) or surgical techniques (silastic or solid silicone implant, open surgical repair like sternochondroplasty and minimally invasive repair). The introduction of Nuss procedure improved the pectus excavatum treatment, but its low acceptance was due to the high complication rate (e.g. cardiac perfuration). The thoracoscopy use for bar mediastinal passage reduced the complication rate. In comparison with sternochondroplasty, the Nuss procedure has smaller incision, less blood loss and less operative time. However, it has more reoperations, complications, longer hospital stay and more readmission rates, more time of thoracic epidural catheter for postoperative analgesia and more need for analgesic after being discharged. Although Nuss procedure has been used in children, patients under ten years must be only observed. The Nuss procedure is applicable to moderate or light symmetrical pectus excavatum, without costal protrusion, in young and adolescents patients. Furthermore, the sternochondroplasty is applicable to severe or asymmetric pectus excavatum, with or without inferior costal protrusion. Therefore, Nuss procedure and sternocondroplasty are not antagonistic procedures, and they must be used in accordance with a treatment organogram and the technique choice must be by functional and aesthetic outcome.
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Filtration is a widely used unit operation in chemical engineering. The huge variation in the properties of materials to be ltered makes the study of ltration a challenging task. One of the objectives of this thesis was to show that conventional ltration theories are di cult to use when the system to be modelled contains all of the stages and features that are present in a complete solid/liquid separation process. Furthermore, most of the ltration theories require experimental work to be performed in order to obtain critical parameters required by the theoretical models. Creating a good overall understanding of how the variables a ect the nal product in ltration is somewhat impossible on a purely theoretical basis. The complexity of solid/liquid separation processes require experimental work and when tests are needed, it is advisable to use experimental design techniques so that the goals can be achieved. The statistical design of experiments provides the necessary tools for recognising the e ects of variables. It also helps to perform experimental work more economically. Design of experiments is a prerequisite for creating empirical models that can describe how the measured response is related to the changes in the values of the variable. A software package was developed that provides a ltration practitioner with experimental designs and calculates the parameters for linear regression models, along with the graphical representation of the responses. The developed software consists of two software modules. These modules are LTDoE and LTRead. The LTDoE module is used to create experimental designs for di erent lter types. The lter types considered in the software are automatic vertical pressure lter, double-sided vertical pressure lter, horizontal membrane lter press, vacuum belt lter and ceramic capillary action disc lter. It is also possible to create experimental designs for those cases where the variables are totally user de ned, say for a customized ltration cycle or di erent piece of equipment. The LTRead-module is used to read the experimental data gathered from the experiments, to analyse the data and to create models for each of the measured responses. Introducing the structure of the software more in detail and showing some of the practical applications is the main part of this thesis. This approach to the study of cake ltration processes, as presented in this thesis, has been shown to have good practical value when making ltration tests.
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kuv., 27 x 21 cm
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kuv., 27 x 21 cm
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kuv., 11 x 18 cm
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kuv., 12 x 18 cm
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kuv., 20 x 29 cm
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kuv., 14 x 21 cm
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kuv., 14 x 21 cm
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kuv., 11 x 18 cm
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kuv., 21 x 30 cm
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kuv., 12 x 18 cm
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kuv., 11 x 18 cm
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kuv., 12 x 18 cm
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kuv., 12 x 18 cm