Spelling suggestions: "subject:"headers"" "subject:"eaders""
1 |
Flexural Behavior and Strength of Cold-formed Steel L-HeadersPauls, Jesse January 2008 (has links)
Cold-formed steel framing of residential and light commercial buildings continues to grow in popularity due to its structural and material advantages. The North American steel industry is actively performing research studies and developing design standards to assist in the cost-effectiveness of cold-formed steel in these markets. Cold-formed steel L-headers are structural components used over wall openings to transfer the loads to adjacent king studs. Recently, there has been an increased interest in L-headers among homebuilders primarily due to their ease of installation and low material cost. Design of the L-headers in North America is currently governed by the North American Standard for Cold Formed Steel Framing – Header Design, in combination with the North American Specification for Design of Cold Formed Steel Structural Members. However, the design provisions in the AISI - Header Design Standard are particularly limiting. For instance, the method for evaluation of span deflections for both single and double L-headers, and uplift flexural strength for single L-headers is currently not available primarily due to lack of research on the issues.
Presented in this thesis are the findings from an extensive laboratory testing program of full-scale single and double cold-formed steel L-headers. The objective of the research was to investigate the structural behavior of L-headers under both gravity and uplift loads. From the analysis, improved ultimate flexural strength design expressions and new vertical deflection expressions for single and double L-header assemblies were developed. The concept of semi-rigid members was introduced to evaluate the flexural behavior and deflection performance of L-header assemblies.
|
2 |
Flexural Behavior and Strength of Cold-formed Steel L-HeadersPauls, Jesse January 2008 (has links)
Cold-formed steel framing of residential and light commercial buildings continues to grow in popularity due to its structural and material advantages. The North American steel industry is actively performing research studies and developing design standards to assist in the cost-effectiveness of cold-formed steel in these markets. Cold-formed steel L-headers are structural components used over wall openings to transfer the loads to adjacent king studs. Recently, there has been an increased interest in L-headers among homebuilders primarily due to their ease of installation and low material cost. Design of the L-headers in North America is currently governed by the North American Standard for Cold Formed Steel Framing – Header Design, in combination with the North American Specification for Design of Cold Formed Steel Structural Members. However, the design provisions in the AISI - Header Design Standard are particularly limiting. For instance, the method for evaluation of span deflections for both single and double L-headers, and uplift flexural strength for single L-headers is currently not available primarily due to lack of research on the issues.
Presented in this thesis are the findings from an extensive laboratory testing program of full-scale single and double cold-formed steel L-headers. The objective of the research was to investigate the structural behavior of L-headers under both gravity and uplift loads. From the analysis, improved ultimate flexural strength design expressions and new vertical deflection expressions for single and double L-header assemblies were developed. The concept of semi-rigid members was introduced to evaluate the flexural behavior and deflection performance of L-header assemblies.
|
3 |
Steam temperature and flow maldistribution in superheater headersdu Preez, Jean-Pierre 11 September 2020 (has links)
Heat exchangers and steam headers are at the heart of any boiler and are susceptible to a range of failures including tube leaks, ligament cracking, creep and fatigue. These common forms of header failure mechanisms can be exacerbated by local thermal stresses due to temperature and flow maldistribution at full and partial boiler load operations. The purpose of this project is to develop process models of the outlet stubbox header of a final superheater (FSH) heat exchanger in a 620MW coal-fired drum type boiler. The process models were used to assess the impact of steam flow and temperature distribution on the thermal stresses in the header material. The process models were developed using Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA). Thermocouples were installed at key locations on the stubbox headers to monitor metal temperatures and the measured metal temperatures served as boundary values and for validation of the CFD results. The thermocouple data was analysed for three different steady state boiler loads, namely full load, 80% load and 60% load. It showed that the temperature distribution across these headers was not uniform, with a maximum temperature difference across the outlet stubbox of 40℃ at full load and 43℃ at partial loads. Other relevant power plant data, such as steam pressure, was provided from the power plant's Distributed Control System (DCS) and was used as boundary conditions for the CFD models. The exact mass flow distribution across the inlet stubs of the outlet stubbox header was unknown and was estimated using a CFD model of the inlet stubbox header and steam mass flow values from power plant's DCS system. A CFD model was created for each of the three boiler loads at steady state conditions. The CFD results provided the metal temperature profile, internal steam temperature distribution and pressure distribution across the header. The CFD solid temperatures were validated using the thermocouple readings and found to be in agreement. The CFD results were exported to the FEA models, where specific displacement constraints for thermal expansion were utilised. The FEA models were used to assess the extent of thermal stresses due to thermal expansion only, as well as stresses due to thermal expansion combined with internal pressure. High local stresses were found at the borehole crotch corners of the rear outlet branch and inlet stubs. However, these are below 0.2% proof strength at elevated temperatures. The high local stresses thus did not result in local plastic deformation but contribute to exacerbate steady state failure mechanisms such as creep.
|
4 |
Assessing HTTP Security Header implementations : A study of Swedish government agencies’ first line of defense against XSS and client-side supply chain attacksJohnson, Ludwig, Mårtensson, Lukas January 2021 (has links)
Background. Security on the web is a fundamental requirement as it becomes a bigger part of society and more information than ever is shared over it. However, as recent incidents have shown, even Swedish government agencies have had issues with their website security. One such example is when a client-side supply chain for several governmental websites was hacked and malicious javascript was subsequently found on several governmental websites. Hence this study is aimed at assessing the security of Swedish government agencies’ first line of defense against attacks like XSS and client-side supply chain. Objectives. The main objective of the thesis is to assess the first line of defense, namely HTTP security headers, of Swedish government agency websites. In addition, collecting statistics of what HTTP security headers are actually used by Swedish government agencies today were gathered for comparison with similar studies. Methods. To fulfill the objectives of the thesis, a scan of all Swedish government agency websites, found on Myndighetsregistret, was completed and an algorithm was developed to assess the implementation of the security features. In order to facilitate tunable assessments for different types of websites, the algorithm has granular weights that can be assigned to each test to make the algorithm more generalized. Results. The results show a low overall implementation rate of the various HTTP security headers among the Swedish government agency websites. However, when compared to similar studies, the adoption of all security features are higher among the Swedish government agency websites tested in this thesis. Conclusions. Previous tools/studies mostly checked if a header was implemented or not. With our algorithm, the strength of the security header implementation is also assessed. According to our results, there is a significant difference between if a security header has been implemented, and if it has been implemented well, and provides adequate security. Therefore, traditional tools for testing HTTP security headers may be inefficient and misleading.
|
5 |
O papel do estÃgio nas escolas estaduais de educaÃÃo profissional do cearà no contexto de crise estrutural do capital: formando jovens trabalhadores para o desemprego.Jefferson Leite Oliveira Ferreira 00 September 2018 (has links)
nÃo hà / A pesquisa objetiva definir estratÃgias de conversÃo de registros bibliogrÃficos do formato MARC 21 para os esquemas de metadados MARCXML, Metadata Authority Description Schema (MADS) e Metadata Object Description Schema (MODS), por meio dos cabeÃalhos de autoridade de nomes e assuntos como categorias de anÃlise. Procedeu-se ao mapeamento dos subcampos com seus respectivos valores e o posterior cotejamento com as tags dos esquemas de metadados alvo da conversÃo. A pesquisa de carÃter exploratÃria e descritiva propiciada por levantamentos bibliogrÃficos e documentais adota a observaÃÃo sistemÃtica como tÃcnica viabilizadora da etapa empÃrica. Aborda o modelo entidade-relacionamento adotado pelosFunctional Requirements for Bibliographic Records (FRBR) como ferramenta para modelar o relacionamento entre os atributos dos metadados em estudo e o formato MARC com as prescriÃÃes dos Functional Requirements for Authority Data (FRAD)para os dados de autoridade de nome pessoal e os Functional Requirements for Subject Authority Data (FRSAD) para os dados de autoridade de assuntos tÃpicos. A anÃlise preliminar demonstrou que a flexibilidade dos esquemas permite tratar redundÃncias e ambivalÃncias na representaÃÃo de nomes pessoais e seus atributos.Permite, ainda,a abordagem por meio de remissivas e qualificadores apropriados com Ãnfase nos aspectos ligados a sinonÃmia e polissemia dos cabeÃalhos de assuntos. Analisa a flexibilidade notacional de esquemas correlatos como o Metadata Encoding and Transmission Standard (METS) na esteira da perspectiva de recursos de informaÃÃo interoperÃveis. Insere o vocabulÃrio Dublin Core na discussÃo e codificaÃÃo de metadados descritivos, o que possibilitou mapear limites e possibilidades deste vocabulÃrio no contexto bibliogrÃfico. Os resultados das conversÃes realizadas ilustraram o papel estratÃgico do modelo entidade-relacionamento como paradigma conceitual adotado pelos FRBR e, subsidiariamente pelos FRAD e FRSAD, na conduÃÃo das etapas de mapeamento e codificaÃÃo dos dados de autoridade de nome pessoal e assunto tÃpico de MARC para MADS e MODS. Foi observado que todos os campos e subcampos MARC analisados,alÃm de encontrarem seus equivalentes nos esquemas XML correspondentes, sÃo acrescidos de atributos relacionais que demonstraram efetividade nos vÃnculos que associam autores a papÃis assumidos nos recursos. Conclui que as estratÃgias de conversÃo aplicadas extraem o valor semÃntico do paradigma relacional preconizado pelos FRBR como elemento chave para alcance de expressividade, coerÃncia interna e sofisticaÃÃo das relaÃÃes sintÃticas e semÃnticas tÃo caras à efetividade dos catÃlogos. Sugere, a partir da literatura consultada e dos resultados verificados na etapa empÃrica, pesquisas que visem contemplar estratÃgicas de conversÃo de metadados com Ãnfase nos grupos 2 e 3 dos FRBR. / The objective of this research is to define strategies for converting bibliographic records from MARC 21 format to MARCXML, Metadata Authority Description Schema (MADS) and Metadata Object Description Schema (MODS) metadata schemas, through name and subject authority as analysis categories. The mapping of the subfields with their respective values and the subsequent collation with the tags of the metadata schemes target of the conversion were done. The exploratory and descriptive research provided by bibliographical and documentary surveys adopts systematic observation as a technique that enables the empirical stage. It ad-dresses the entity-relationship model adopted by the Functional Requirements for Biblio-graphic Records (FRBR) as a tool to model the relationship between the attributes of the metadata under study and the MARC format with the requirements of Functional Require-ments for AuthorityDescription (FRAD) and the Functional Requirements for Subject Authority Data (FRSAD) for the topics subject authority data. The preliminary analysis showed that the flexibility of the schemas allows to treat redundancies and ambivalences in the representation of personal names and their attributes. It also allows the approach through appropriate refer-ences and qualifiers with emphasis on aspects related to synonymy and polysemy of subject headings. It analyzes the notational flexibility of related schemas such as Metadata Encoding and Transmission Standard (METS) in the wake of the perspective of interoperable infor-mation resources. It inserts the Dublin Core vocabulary into the discussion and coding of de-scriptive metadata, which made it possible to map the limits and possibilities of this vocabu-lary in the bibliographic context. The results of the conversions carried out illustrated the stra-tegic role of the entity-relationship model as a conceptual paradigm adopted by the FRBR and, in a subsidiary way, by the FRAD and FRSAD, in the process of mapping and coding the personal name and subject matter authority data from MARC to MADS and MODS. It was observed that all the analyzed MARC fields and subfields, besides finding their equiva-lents in the corresponding XML schemas, are added with relational attributes that demon-strated effectiveness in the links that associate authors to roles assumed in the resources.
It concludes that the applied conversion strategies extract the semantic value of the relational paradigm advocated by the FRBR as a key element for the reach of expressiveness, internal coherence and sophistication of the syntactic and semantic relations so dear to the effectiveness of the catalogs. It suggests, from the literature consulted and the results verified in the empiri-cal stage, researches that aim to contemplate strategies of metadata conversion with emphasis in groups 2 and 3 of FRBR.
|
6 |
Epaminondas : Strateg och stadsgrundareBengtsson, Gunilla January 2009 (has links)
<p>There is an old saying, that after Epaminondas nothing was ever the same again. In this thesis I will focus on three questions: "Epaminondas the man." Who was he? "Epaminondas the general." How did he change the technique of warfare that made it possible to beat the Spartans? "Epaminondas, founder of cities and wall-builder." How did he build the walls around the cities he initiated, that made them resist enemy attacks for many years to come?</p><p>While seeking the answers to yhese questions I will make a contextual analysis to get the historical background to all the phenomina involved.</p>
|
7 |
Epaminondas : Strateg och stadsgrundareBengtsson, Gunilla January 2009 (has links)
There is an old saying, that after Epaminondas nothing was ever the same again. In this thesis I will focus on three questions: "Epaminondas the man." Who was he? "Epaminondas the general." How did he change the technique of warfare that made it possible to beat the Spartans? "Epaminondas, founder of cities and wall-builder." How did he build the walls around the cities he initiated, that made them resist enemy attacks for many years to come? While seeking the answers to yhese questions I will make a contextual analysis to get the historical background to all the phenomina involved.
|
8 |
An automated tool for website security assessment : Demonstration on Swedish authorities’ websitesValdaserides Olofsson, Max, Stengård, Malte January 2024 (has links)
The evolution of internet has affected society in many ways. Organizations and authorities offer their services on their many corresponding websites. Consequently, secure connections to these websites are a necessity, in addition to continuously evaluate their security. Many studies exist on website security analysis of some set of websites and it is found that researchers often develop and utilize several toolsand scripts for their studies - one for collecting data, one for parsing the output, and one for visualizing the data. Undoubtedly, this whole process is labor intensive, and for this reason we in this thesis propose a tool that automates this whole process. Moreover, the Swedish authorities and their corresponding websites provide information and services regarding their specific areas of expertise that are essential for the functioning of the Swedish society. As such, this puts a high expectation of the usage of state-of-the-art security technology and best practice implementations on these websites in order to keep the Swedish society functioning and keep their websites’ visitors safe. For this reason, we in this thesis focus on mainly two things: 1. Design and develop a tool that will be easy to use to collect a set of websites’ security parameter implementations and best practices, and thereafter automatically and adequately visualize this data to assess the websites’ security readiness; and 2. Demonstrate the developed tool on the Swedish authorities’ websites to assess their website security readiness. The result shows a good overall security in the Swedish authorities’ websites, though there is room for improvement.
|
9 |
The architecture of function : Understanding House K at San Giovenale / Funktionens arkitektur : Att förstå Hus K i San GiovenaleAlyasin, Ghaza January 2020 (has links)
Between 1961 and 1963 a large terraced Etruscan building on the southside of the Acropolis at the archaeological site of San Giovenale in Italy was excavated. The building, named House K, remained largely unpublished and unstudied throughout the years, leaving our picture of the ancient settlement at San Giovenale incomplete. This thesis aims to get a better understanding of the Etruscan architecture, settlement, culture, and society at San Giovenale, by doing an architectural analysis of the building of House K, using unpublished field journals, drawings, and photographs. By comparing the architecture of House K and any structural elements immediately connected with the building, to other structures at San Giovenale, as well as other Etruscan sites, this thesis set out to learn: what kind of structure House K is; what function it had; what its relative dating is; what role it played in the settlement at San Giovenale; and what it can tell us regarding the society and culture at San Giovenale. Using environment-behaviour relations and building archaeology, the study first examined the structural elements of House K, before comparing House K to other structures at San Giovenale built 700–400 BCE. Thereafter, the study looked at parallels outside of San Giovenale, looking at the sites of Acquarossa, Luni sul Mignone, Poggio Civitate, Cerveteri, Pyrgi, Montetosto, Vulci, and Narce. Finally, a discussion was had regarding the character and function of House K, whether it was public, private, sacred, or profane. In the course of the study, an architectural chronology of San Giovenale was established, which dated the construction date of House K to between c. 565 BCE and the late 6th century BCE. The interpretation of the function of House K that seems most probable is that it was a monumental building complex of administrative, political and/or religious significance, which probably also acted as a residence for the ruling elite at San Giovenale – in other words: a palazzo. House K being a palazzo would mean that there was a centralised authority at San Giovenale, suggesting that there was some sort of ruler or leader at the top of the social hierarchy, splitting the social division at San Giovenale further than it was previously believed to have been.
|
10 |
Computational Fluid Dynamics Modelling of Solid Oxide Fuel Cell StacksNishida, Robert Takeo 02 October 2013 (has links)
Two computational fluid dynamics models are developed to predict the performance of a solid oxide fuel cell stack, a detailed and a simplified model. In the detailed model, the three dimensional momentum, heat, and species transport equations are coupled with electrochemistry. In the simplified model, the diffusion terms in the transport equations are selectively replaced by rate terms within the core region of the stack. This allows much coarser meshes to be employed at a fraction of the computational cost. Following the mathematical description of the problem, results for single-cell and multi-cell stacks are presented. Comparisons of local current density, temperature, and cell voltage indicate that good agreement is obtained between the detailed and simplified models, verifying the latter as a practical option in stack design. Then, the simplified model is used to determine the effects of utilization on the electrochemical performance and temperature distributions of a 10 cell stack. The results are presented in terms of fluid flow, pressure, species mass fraction, temperature, voltage and current density distributions. The effects of species and flow distributions on electrochemical performance and temperature are then analyzed for a 100 cell stack. The discussion highlights the importance of manifold design on performance and thermal management of large stacks. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2013-09-30 15:55:18.627
|
Page generated in 0.0487 seconds