985 resultados para nuclear engineering
Resumo:
El propòsit central d’aquest treball és el de plantejar un procés d’activació del patrimoni cultural i històric, concretament el de la Central Nuclear de Lemoiz (Biscaia). Si la central fos declarada patrimoni industrial i històric es podria establir un punt de partida per a la resolució d’una situació complexa a nivell social, polític, urbanístic i medi-ambiental com és l’existència de la central nuclear
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Aldosterone and corticosterone bind to mineralocorticoid (MR) and glucocorticoid receptors (GR), which, upon ligand binding, are thought to translocate to the cell nucleus to act as transcription factors. Mineralocorticoid selectivity is achieved by the 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) that inactivates 11β-hydroxy glucocorticoids. High expression levels of 11β-HSD2 characterize the aldosterone-sensitive distal nephron (ASDN), which comprises the segment-specific cells of late distal convoluted tubule (DCT2), connecting tubule (CNT), and collecting duct (CD). We used MR- and GR-specific antibodies to study localization and regulation of MR and GR in kidneys of rats with altered plasma aldosterone and corticosterone levels. In control rats, MR and GR were found in cell nuclei of thick ascending limb (TAL), DCT, CNT, CD cells, and intercalated cells (IC). GR was also abundant in cell nuclei and the subapical compartment of proximal tubule (PT) cells. Dietary NaCl loading, which lowers plasma aldosterone, caused a selective removal of GR from cell nuclei of 11β-HSD2-positive ASDN. The nuclear localization of MR was unaffected. Adrenalectomy (ADX) resulted in removal of MR and GR from the cell nuclei of all epithelial cells. Aldosterone replacement rapidly relocated the receptors in the cell nuclei. In ASDN cells, low-dose corticosterone replacement caused nuclear localization of MR, but not of GR. The GR was redistributed to the nucleus only in PT, TAL, early DCT, and IC that express no or very little 11β-HSD2. In ASDN cells, nuclear GR localization was only achieved when corticosterone was replaced at high doses. Thus ligand-induced nuclear translocation of MR and GR are part of MR and GR regulation in the kidney and show remarkable segment- and cell type-specific characteristics. Differential regulation of MR and GR may alter the level of heterodimerization of the receptors and hence may contribute to the complexity of corticosteroid effects on ASDN function.
Resumo:
Tutkielman tavoitteena on määritellä projektikontrolloinnin ja - riskijohtamisen roolit ja toiminnot saksalaisissa kone- ja tehdassuunnitteluteollisuusyrityksissä. Tämä on kvalitatiivinen tutkielma, jossa käytetään voimakkaasti kuvailevia metodeita. Materiaali tutkimuksen empiiriseen osaan kerättiin kyselykaavakkeen avulla. Kyselykaavakkeiden tulokset käsiteltiin Microsoft Office Access- ohjelmalla ja analysoitiin Microsoft Office Excel- ohjelmalla ja Pivot table- työkalun avulla. Tutkimustulokset osoittavat, että asianmukaisessa projektikontrollointi- ja riskijohtamismetodien käytössä ja käyttötiheydessä esiintyy puutteita saksalaisissa kone- ja tehdassuunnitteluteollisuusyrityksissä. Tehostamalla ja keskittymällä enemmän projektikontrollointi- ja riskijohtamismetodeihin ja prosesseihin sekä projektien että yritysten suorituskyky paranisi.
Resumo:
Objetivou-se determinar o potencial do uso da tomografia de ressonância magnética, como método não-destrutivo, para avaliar os efeitos das injúrias mecânicas em goiabas. Foram utilizados frutos no estádio de maturação "de vez" das cultivares Paluma e Pedro Sato. Na injúria por impacto, os frutos foram deixados cair, em queda livre, de uma altura de 1,20 m, sofrendo dois impactos, em lados opostos de sua porção equatorial. Na injúria por compressão, os frutos foram submetidos a um peso de 29,4 N, por 15 minutos. Para a injúria por corte, foram efetuados dois cortes, no sentido longitudinal dos frutos, de exatamente 30 mm de comprimento por 2 mm de profundidade. Os frutos injuriados foram armazenados sob condições de ambiente (22 ± 2 °C e 40 %UR). Foram realizadas análises com tomógrafo de ressonância magnética Varian Inova de 2 Tesla. As imagens foram obtidas a partir da detecção dos prótons de hidrogênio (¹H). Para cada fruto, foram obtidos tomogramas simétricos a partir do centro do fruto. A tomografia de ressonância magnética nuclear mostrou-se uma ferramenta eficaz na detecção de injúrias internas de frutos. O estresse físico causado pelo impacto produziu um colapso interno nos lóculos desses frutos (internal bruising), levando à perda da integridade celular e a conseqüente liquefação dos tecidos placentários. A cultivar Pedro Sato mostrou uma suscetibilidade maior à injúria por impacto que a 'Paluma'. A injúria por compressão tornou-se mais evidente no pericarpo externo do fruto, de ambas as cultivares. A injúria por corte levou a lignificação dos tecidos no local injuriado e deformações superficiais devido à perda acentuada de matéria fresca no local da lesão, evidentes no sexto dia de avaliação.
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The nuclear matrix, a proteinaceous network believed to be a scaffolding structure determining higher-order organization of chromatin, is usually prepared from intact nuclei by a series of extraction steps. In most cell types investigated the nuclear matrix does not spontaneously resist these treatments but must be stabilized before the application of extracting agents. Incubation of isolated nuclei at 37C or 42C in buffers containing Mg++ has been widely employed as stabilizing agent. We have previously demonstrated that heat treatment induces changes in the distribution of three nuclear scaffold proteins in nuclei prepared in the absence of Mg++ ions. We studied whether different concentrations of Mg++ (2.0-5 mM) affect the spatial distribution of nuclear matrix proteins in nuclei isolated from K562 erythroleukemia cells and stabilized by heat at either 37C or 42C. Five proteins were studied, two of which were RNA metabolism-related proteins (a 105-kD component of splicing complexes and an RNP component), one a 126-kD constituent of a class of nuclear bodies, and two were components of the inner matrix network. The localization of proteins was determined by immunofluorescent staining and confocal scanning laser microscope. Mg++ induced significant changes of antigen distribution even at the lowest concentration employed, and these modifications were enhanced in parallel with increase in the concentration of the divalent cation. The different sensitivity to heat stabilization and Mg++ of these nuclear proteins might reflect a different degree of association with the nuclear scaffold and can be closely related to their functional or structural role.
Resumo:
This paper analyzes the possibilities of integrating cost information and engineering design. Special emphasis is put on finding the potential of using the activity-based costing (ABC) method. Today, the problem of cost estimation in engineering design is that there are two separate extremes of knowledge. On the one extreme, the engineers model the technical parametres behindcosts in great detail but do not get appropriate cost information to their elegant models. On the other extreme, the accounting professionals are stuck with traditional cost accounting methods driven by the procedures and cycles of financial accounting. Therefore, in many cases, the cost information needs of various decision making groups, for example design engineers, are not served satisfactorily. This paper studies if the activity-based costing (ABC) method could offer a compromise between the two extremes. Recognizing activities and activity chains as well as activity and cost drivers could be specially beneficial for design engineers. Also, recognizing the accurate and reliable product costs of existing products helps when doing variant design. However, ABC is not at its best if the cost system becomes too complicated. This is why a comprehensive ABC-cost information system with detailed cost information for the use of design engineers should be examined critically. ABC is at its best when considering such issues as which activities drive costs, the cost of product complexity, allocating indirect costs on the products, the relationships between processes and costs, and the cost of excess capacity.
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Even though the research on innovation in services has expanded remarkably especially during the past two decades, there is still a need to increase understanding on the special characteristics of service innovation. In addition to studying innovation in service companies and industries, research has also recently focused more on services in innovation, as especially the significance of so-called knowledge intensive business services (KIBS) for the competitive edge of their clients, othercompanies, regions and even nations has been proved in several previous studies. This study focuses on studying technology-based KIBS firms, and technology andengineering consulting (TEC) sector in particular. These firms have multiple roles in innovation systems, and thus, there is also a need for in-depth studies that increase knowledge about the types and dimensions of service innovations as well as underlying mechanisms and procedures which make the innovations successful. The main aim of this study is to generate new knowledge in the fragmented research field of service innovation management by recognizing the different typesof innovations in TEC services and some of the enablers of and barriers to innovation capacity in the field, especially from the knowledge management perspective. The study also aims to shed light on some of the existing routines and new constructions needed for enhancing service innovation and knowledge processing activities in KIBS companies of the TEC sector. The main samples of data in this research include literature reviews and public data sources, and a qualitative research approach with exploratory case studies conducted with the help of the interviews at technology consulting companies in Singapore in 2006. These complement the qualitative interview data gathered previously in Finland during a larger research project in the years 2004-2005. The data is also supplemented by a survey conducted in Singapore. The respondents for the survey by Tan (2007) were technology consulting companies who operate in the Singapore region. The purpose ofthe quantitative part of the study was to validate and further examine specificaspects such as the influence of knowledge management activities on innovativeness and different types of service innovations, in which the technology consultancies are involved. Singapore is known as a South-east Asian knowledge hub and is thus a significant research area where several multinational knowledge-intensive service firms operate. Typically, the service innovations identified in the studied TEC firms were formed by several dimensions of innovations. In addition to technological aspects, innovations were, for instance, related to new client interfaces and service delivery processes. The main enablers of and barriers to innovation seem to be partly similar in Singaporean firms as compared to the earlier study of Finnish TEC firms. Empirical studies also brought forth the significance of various sources of knowledge and knowledge processing activities as themain driving forces of service innovation in technology-related KIBS firms. A framework was also developed to study the effect of knowledge processing capabilities as well as some moderators on the innovativeness of TEC firms. Especially efficient knowledge acquisition and environmental dynamism seem to influence the innovativeness of TEC firms positively. The results of the study also contributeto the present service innovation literature by focusing more on 'innovation within KIBs' rather than 'innovation through KIBS', which has been the typical viewpoint stressed in the previous literature. Additionally, the study provides several possibilities for further research.
Resumo:
Process development will be largely driven by the main equipment suppliers. The reason for this development is their ambition to supply complete plants or process systems instead of single pieces of equipment. The pulp and paper companies' interest lies in product development, as their main goal is to create winning brands and effective brand management. Design engineering companies will find their niche in detail engineering based on approved process solutions. Their development work will focus on increasing the efficiency of engineering work. Process design is a content-producing profession, which requires certain special characteristics: creativity, carefulness, the ability to work as a member of a design team according to time schedules and fluency in oral as well as written presentation. In the future, process engineers will increasingly need knowledge of chemistry as well as information and automation technology. Process engineering tools are developing rapidly. At the moment, these tools are good enough for static sizing and balancing, but dynamic simulation tools are not yet good enough for the complicated chemical reactions of pulp and paper chemistry. Dynamic simulation and virtual mill models are used as tools for training the operators. Computational fluid dynamics will certainlygain ground in process design.
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This thesis gives an overview of the validation process for thermal hydraulic system codes and it presents in more detail the assessment and validation of the French code CATHARE for VVER calculations. Three assessment cases are presented: loop seal clearing, core reflooding and flow in a horizontal steam generator. The experience gained during these assessment and validation calculations has been used to analyze the behavior of the horizontal steam generator and the natural circulation in the geometry of the Loviisa nuclear power plant. The cases presented are not exhaustive, but they give a good overview of the work performed by the personnel of Lappeenranta University of Technology (LUT). Large part of the work has been performed in co-operation with the CATHARE-team in Grenoble, France. The design of a Russian type pressurized water reactor, VVER, differs from that of a Western-type PWR. Most of thermal-hydraulic system codes are validated only for the Western-type PWRs. Thus, the codes should be assessed and validated also for VVER design in order to establish any weaknesses in the models. This information is needed before codes can be used for the safety analysis. Theresults of the assessment and validation calculations presented here show that the CATHARE code can be used also for the thermal-hydraulic safety studies for VVER type plants. However, some areas have been indicated which need to be reassessed after further experimental data become available. These areas are mostly connected to the horizontal stem generators, like condensation and phase separation in primary side tubes. The work presented in this thesis covers a large numberof the phenomena included in the CSNI code validation matrices for small and intermediate leaks and for transients. Also some of the phenomena included in the matrix for large break LOCAs are covered. The matrices for code validation for VVER applications should be used when future experimental programs are planned for code validation.
Resumo:
The present study focuses on two effects of the presence of a noncondensable gas on the thermal-hydraulic behavior of thecoolant of the primary circuit of a nuclear reactor in the VVER-440 geometry inabnormal situations. First, steam condensation with the presence of air was studied in the horizontal tubes of the steam generator (SG) of the PACTEL test facility. The French thermal-hydraulic CATHARE code was used to study the heat transfer between the primary and secondary side in conditions derived from preliminary experiments performed by VTT using PACTEL. In natural circulation and single-phase vapor conditions, the injection of a volume of air, equivalent to the totalvolume of the primary side of the SG at the entrance of the hot collector, did not stop the heat transfer from the primary to the secondary side. The calculated results indicate that air is located in the second half-length (from the mid-length of the tubes to the cold collector) in all the tubes of the steam generator The hot collector remained full of steam during the transient. Secondly, the potential release of the nitrogen gas dissolved in the water of the accumulators of the emergency core coolant system of the Loviisa nuclear power plant (NPP) was investigated. The author implemented a model of the dissolution and release ofnitrogen gas in the CATHARE code; the model created by the CATHARE developers. In collaboration with VTT, an analytical experiment was performed with some components of PACTEL to determine, in particular, the value of the release time constant of the nitrogen gas in the depressurization conditions representative of the small and intermediate break transients postulated for the Loviisa NPP. Such transients, with simplified operating procedures, were calculated using the modified CATHARE code for various values of the release time constant used in the dissolution and release model. For the small breaks, nitrogen gas is trapped in thecollectors of the SGs in rather large proportions. There, the levels oscillate until the actuation of the low-pressure injection pumps (LPIS) that refill the primary circuit. In the case of the intermediate breaks, most of the nitrogen gas is expelled at the break and almost no nitrogen gas is trapped in the SGs. In comparison with the cases calculated without taking into account the release of nitrogen gas, the start of the LPIS is delayed by between 1 and 1.75 h. Applicability of the obtained results to the real safety conditions must take into accountthe real operating procedures used in the nuclear power plant.
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Requirements-relatedissues have been found the third most important risk factor in software projects and as the biggest reason for software project failures. This is not a surprise since; requirements engineering (RE) practices have been reported deficient inmore than 75% of all; enterprises. A problem analysis on small and low maturitysoftware organizations revealed two; central reasons for not starting process improvement efforts: lack of resources and uncertainty; about process improvementeffort paybacks.; In the constructive part of the study a basic RE method, BaRE, was developed to provide an; easy to adopt way to introduce basic systematic RE practices in small and low maturity; organizations. Based on diffusion of innovations literature, thirteen desirable characteristics; were identified for the solution and the method was implemented in five key components:; requirements document template, requirements development practices, requirements; management practices, tool support for requirements management, and training.; The empirical evaluation of the BaRE method was conducted in three industrial case studies. In; this evaluation, two companies established a completely new RE infrastructure following the; suggested practices while the third company conducted continued requirements document; template development based on the provided template and used it extensively in practice. The; real benefits of the adoption of the method were visible in the companies in four to six months; from the start of the evaluation project, and the two small companies in the project completed; their improvement efforts with an input equal to about one person month. The collected dataon; the case studies indicates that the companies implemented new practices with little adaptations; and little effort. Thus it can be concluded that the constructed BaRE method is indeed easy to; adopt and it can help introduce basic systematic RE practices in small organizations.
Resumo:
The purpose of this thesis is to analyse activity-based costing (ABC) and possible modified versions ofit in engineering design context. The design engineers need cost information attheir decision-making level and the cost information should also have a strong future orientation. These demands are high because traditional management accounting has concentrated on the direct actual costs of the products. However, cost accounting has progressed as ABC was introduced late 1980s and adopted widely bycompanies in the 1990s. The ABC has been a success, but it has gained also criticism. In some cases the ambitious ABC systems have become too complex to build,use and update. This study can be called an action-oriented case study with some normative features. In this thesis theoretical concepts are assessed and allowed to unfold gradually through interaction with data from three cases. The theoretical starting points are ABC and theory of engineering design process (chapter2). Concepts and research results from these theoretical approaches are summarized in two hypotheses (chapter 2.3). The hypotheses are analysed with two cases (chapter 3). After the two case analyses, the ABC part is extended to cover alsoother modern cost accounting methods, e.g. process costing and feature costing (chapter 4.1). The ideas from this second theoretical part are operationalized with the third case (chapter 4.2). The knowledge from the theory and three cases is summarized in the created framework (chapter 4.3). With the created frameworkit is possible to analyse ABC and its modifications in the engineering design context. The framework collects the factors that guide the choice of the costing method to be used in engineering design. It also illuminates the contents of various ABC-related costing methods. However, the framework needs to be further tested. On the basis of the three cases it can be said that ABC should be used cautiously when formulating cost information for engineering design. It is suitable when the manufacturing can be considered simple, or when the design engineers are not cost conscious, and in the beginning of the design process when doing adaptive or variant design. If the design engineers need cost information for the embodiment or detailed design, or if manufacturing can be considered complex, or when design engineers are cost conscious, the ABC has to be always evaluated critically.
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Genomic instability is related to a wide-range of human diseases. Here, we show that mitochondrial iron–sulfur cluster biosynthesis is important for the maintenance of nuclear genome stability in Saccharomyces cerevisiae. Cells lacking the mitochondrial chaperone Zim17 (Tim15/Hep1), a component of the iron–sulfur biosynthesis machinery, have limited respiration activity, mimic the metabolic response to iron starvation and suffer a dramatic increase in nuclear genome recombination. Increased oxidative damage or deficient DNA repair do not account for the observed genomic hyperrecombination. Impaired cell-cycle progression and genetic interactions of ZIM17 with components of the RFC-like complex involved in mitotic checkpoints indicate that replicative stress causes hyperrecombination in zim17Δ mutants. Furthermore, nuclear accumulation of pre-ribosomal particles in zim17Δ mutants reinforces the importance of iron–sulfur clusters in normal ribosome biosynthesis. We propose that compromised ribosome biosynthesis and cell-cycle progression are interconnected, together contributing to replicative stress and nuclear genome instability in zim17Δ mutants.