A mathematical model of recovery of dense medium magnetics in the wet drum magnetic separator

Loss of magnetic medium solids from dense medium circuits is a substantial contributor to operating cost. Much of this loss is by way of wet drum magnetic separator effluent. A model of the separator would be useful for process design, optimisation and control. A review of the literature established that although various rules of thumb exist, largely based on empirical or anecdotal evidence, there is no model of magnetics recovery in a wet drum magnetic separator which includes as inputs all significant machine and operating variables. A series of trials, in both factorial experiments and in single variable experiments, was therefore carried out using a purpose built rig which featured a small industrial scale (700 mm lip length, 900 mm diameter) wet drum magnetic separator. A substantial data set of 191 trials was generated in the work. The results of the factorial experiments were used to identify the variables having a significant effect on magnetics recovery. Observations carried out as an adjunct to this work, as well as magnetic theory, suggests that the capture of magnetic particles in the wet drum magnetic separator is by a flocculation process. Such a process should be defined by a flocculation rate and a flocculation time; the latter being defined by the volumetric flowrate and the volume within the separation zone. A model based on this concept and containing adjustable parameters was developed. This model was then fitted to a randomly chosen 80% of the data, and validated by application to the remaining 20%. The model is shown to provide a satisfactory fit to the data over three orders of magnitude of magnetics loss. (C) 2003 Elsevier Science BY. All rights reserved.

Hemodynamic and ventilatory effects of manual respiratory physiotherapy techniques of chest clapping, vibration, and shaking in an animal model

Chest clapping, vibration, and shaking were studied in 10 physiotherapists who applied these techniques on an anesthetized animal model. Hemodynamic variables (such as heart rate, blood pressure, pulmonary artery pressure, and right atrial pressure) were measured during the application of these techniques to verify claims of adverse events. In addition, expired tidal volume and peak expiratory flow rate were measured to ascertain effects of these techniques. Physiotherapists in this study applied chest clapping at a rate of 6.2 +/- 0.9 Hz, vibration at 10.5 +/- 2.3 Hz, and shaking at 6.2 +/- 2.3 Hz. With the use of these rates, esophageal pressure swings of 8.8 +/- 5.0, 0.7 +/- 0.3, and 1.4 +/- 0.7 mmHg resulted from clapping, vibration, and shaking respectively. Variability in rates and forces generated by these techniques was 80% of variance in shaking force (P = 0.003). Application of these techniques by physiotherapists was found to have no significant effects on hemodynamic and most ventilatory variables in this study. From this study, we conclude that chest clapping, vibration, and shaking 1) can be consistently performed by physiotherapists; 2) are significantly related to physiotherapists' characteristics, particularly clinical experience; and 3) caused no significant hemodynamic effects.

Model-based clustering in gene expression microarrays: An application to breast cancer data

In microarray studies, the application of clustering techniques is often used to derive meaningful insights into the data. In the past, hierarchical methods have been the primary clustering tool employed to perform this task. The hierarchical algorithms have been mainly applied heuristically to these cluster analysis problems. Further, a major limitation of these methods is their inability to determine the number of clusters. Thus there is a need for a model-based approach to these. clustering problems. To this end, McLachlan et al. [7] developed a mixture model-based algorithm (EMMIX-GENE) for the clustering of tissue samples. To further investigate the EMMIX-GENE procedure as a model-based -approach, we present a case study involving the application of EMMIX-GENE to the breast cancer data as studied recently in van 't Veer et al. [10]. Our analysis considers the problem of clustering the tissue samples on the basis of the genes which is a non-standard problem because the number of genes greatly exceed the number of tissue samples. We demonstrate how EMMIX-GENE can be useful in reducing the initial set of genes down to a more computationally manageable size. The results from this analysis also emphasise the difficulty associated with the task of separating two tissue groups on the basis of a particular subset of genes. These results also shed light on why supervised methods have such a high misallocation error rate for the breast cancer data.

The tree cut and merge algorithm for estimation of network reliability

This article presents Monte Carlo techniques for estimating network reliability. For highly reliable networks, techniques based on graph evolution models provide very good performance. However, they are known to have significant simulation cost. An existing hybrid scheme (based on partitioning the time space) is available to speed up the simulations; however, there are difficulties with optimizing the important parameter associated with this scheme. To overcome these difficulties, a new hybrid scheme (based on partitioning the edge set) is proposed in this article. The proposed scheme shows orders of magnitude improvement of performance over the existing techniques in certain classes of network. It also provides reliability bounds with little overhead.

Usefulness of quantitative echocardiographic techniques to predict recovery of regional and global left ventricular function after acute myocardial infarction

The left ventricular response to dobutamine may be quantified using tissue Doppler measurement of myocardial velocity or displacement or 3-dimensional echocardiography to measure ventricular volume and ejection fraction. This study sought to explore the accuracy of these methods for predicting segmental and global responses to therapy. Standard dobutamine and 3-dimensional echocardiography were performed in 92 consecutive patients with abnormal left ventricular function at rest. Recovery of function was defined by comparison with follow-up echocardiography at rest 5 months later. Segments that showed improved regional function at follow-up showed a higher increment in peak tissue Doppler velocity with dobutamine therapy than in nonviable segments (1.2 +/- 0.4 vs 0.3 +/- 0.2 cm/s, p = 0.001). Similarly, patients who showed a > 5% improvement of ejection fraction at follow-up showed a greater displacement response to dobutamine (6.9 +/- 3.2 vs 2.1 +/- 2.3 mm, p = 0.001), as well as a higher rate of ejection fraction, response to dobutamine (9 +/- 3% vs 2 +/- 2%, p = 0.001). The optimal cutoff values for predicting subsequent recovery of function at rest were an increment of peak velocity > 1 cm/s, >5 mm of displacement, and a >5% improvement of ejection fraction with low-dose dobutamine. (C) 2003 by Excerpta Medica, Inc.

Evaluation of encapsulation techniques of probiotics for yoghurt

The health benefits provided by probiotic bacteria have led to their increasing use in fermented and other dairy products. However, their viability in these products is low. Encapsulation has been investigated to protect the bacteria in the product's environment and improve their survival. There are two common encapsulation techniques, namely extrusion and emulsion, to encapsulate the probiotics for their use in the fermented and other dairy products. This review evaluates the merits and limitations of these two techniques, and also discusses the supporting materials and special treatments used in encapsulation processes. (C) 2003 Elsevier Science Ltd. All rights reserved.

A matemática na constituição de um currículo integrado : possibilidades e desafios para o ensino médio e a educação profissional de jovens e adultos

O universo que circunda a Educação de Jovens e Adultos nos sensibiliza e nos provoca. Observar que estes alunos e alunas estão em busca de conquistas e sonhos que não puderam se concretizar quando foram gerados nos impulsiona a conduzir esta pesquisa com seriedade e esperança. Este estudo investigou que conhecimentos matemáticos utilizados por professores do Curso Técnico em Metalurgia Integrado ao Ensino Médio na modalidade de Educação de Jovens e Adultos. Influenciam diálogos entre matemática e outras disciplinas do curso considerando a perspectiva da formação integral dos estudantes. Assim, nos propomos a analisar conhecimentos matemáticos que estão presentes em ações e materiais didáticos utilizados por professores em diferentes disciplinas do Curso Técnico em Metalurgia Integrado ao Ensino Médio na modalidade de Educação de Jovens e Adultos. No intuito de responder a questão proposta e alcançar os objetivos expostos, este estudo torna-se mais relevante por estar diretamente envolvido no processo de consolidação do Programa Nacional de Integração da Educação Profissional com a Educação Básica na Modalidade de Educação de Jovens e Adultos – PROEJA do Curso de Metalurgia ofertado pelo IFES/Vitória, pautado na idealização de integração do seu currículo. Portanto, discutir o projeto de integração curricular que norteia o PROEJA tornou-se uma meta em movimento dessa investigação. Nesta direção, observamos o reflexo de como as práticas e materiais didáticos utilizados por professores, que atuam nesta modalidade, puderam contribuir para discussões que nos ajudaram na compreensão do processo de ensino e aprendizagem dos educandos participantes, com vistas ao desenvolvimento no trabalho ou na formação profissional, como na constituição de conhecimentos científicos, escolares/tecnológicos e culturais. Optamos por direcionar a reflexão teórica deste capítulo em conceitos específicos. Assim, ao tratar da Educação de Jovens e Adultos seremos conduzidos pelos estudos e pesquisas de Paulo Freire (1996, 2000, 2005), Maria da Conceição Fonseca (2007) e Jane Paiva (2009); ao direcionarmos para a Teoria do Ensino Integrado e a Educação Profissional faremos uso dos estudos de Gaudêncio Frigotto (2010) e Marise Ramos (2010); quanto às discussões que refletem acerca da Educação Matemática Critica recorremos às ideias de Ole Skovsmose (2001, 2007).

The influence of nationalism in Mercosur and in South America: can the regional integration project survive?

The article discusses if nationalism is getting in the way of regional integration through a Brazilian prism due to Brazil’s pivotal role in regional integration in Mercosur and South America.

Certification and integration of management systems: the experience of Portuguese small and medium enterprises

The purpose of this study was to characterize the situation of Portuguese Small and Medium Enterprises (SMEs) concerning the certification of their Quality Management Systems (QMS), Environmental Management Systems (EMS) and Occupational Health and Safety Management Systems (OHSMS), in their individually form, to identify benefits, drawbacks and difficulties associated with the certification process and to characterize the level of integration that has been achieved. This research was based on a survey carried out by the research team; it was administered to 46 Portuguese SMEs. Our sample comprised 20 firms (43%) from the Trade/Services activity sector, 17 (37%) from the Industrial sector, 5 (11%) from the Electricity/Telecommunications sector and 4 (9%) from the Construction area. All SMEs surveyed were certified according to the ISO 9001 (100%), a quarter of firms were certified according to the ISO 14001 (26.1%) and a few certified by OHSAS 18001 (15.2%). We undertook a multivariate cluster analysis, which enabled grouping variables into homogeneous groups or one or more common characteristics of the SMEs participating in the study. Results show that the main benefits that Portuguese SMEs have gained from the referred certifications have been, among others, an improvement of both their internal organization and external image. We also present the main difficulties in achieving certification. Overall, 7 of the Portuguese SMEs examined indicated that the main benefits of the IMS implementation management included costs reduction, increased employee training and easier compliance of legislation. The respective drawbacks and difficulties are also presented. Finally, we presented the main integrated items in the certified Portuguese SMEs we examined.

A Generic Library for GUI Reasoning and Testing

Graphical user interfaces (GUIs) make software easy to use by providing the user with visual controls. Therefore, correctness of GUI's code is essential to the correct execution of the overall software. Models can help in the evaluation of interactive applications by allowing designers to concentrate on its more important aspects. This paper presents a generic model for language-independent reverse engineering of graphical user interface based applications, and we explore the integration of model-based testing techniques in our approach, thus allowing us to perform fault detection. A prototype tool has been constructed, which is already capable of deriving and testing a user interface behavioral model of applications written in Java/Swing.