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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Moment-rotation behaviour of universal beam to tubular column connections using reverse channel

Li, Xue January 2012 (has links)
Steel tubular structures are becoming more widely used in recent years because of their excellent structural performance as well as appearance. For structures with steel hollow section (SHS) columns and concrete filled tubular (CFT) columns, several types of joint may be used to connect to wide flange beams. The topic of this research is a relatively new type of joint, the 'reverse channel' connection, in which the legs of a channel are welded to the tube thus converting the closed tubular column into an open section for connection purpose. However, since tubular columns have only recently become more popular in frames, there is a lack of research to quantify the moment-rotation characteristics of connections between I beams and tubular columns. A total of eight tests on loaded steel beam to RHS column connections using reverse channel and endplate, up to collapse, were carried out. The objectives of these tests were to investigate the effects of different connection details on connection performance and to provide experimental data for validation of numerical simulations. Validation of numerical modelling was carried out to check accuracy of the numerical simulation model developed using the general finite element package ABAQUS. The validated ABAQUS model was then used to perform various parametric studies to provide insight into structural behaviour. A systematic approach to quantify the load carrying capacity of the reverse channel web and the column face were adopted based on yield line theory. This thesis presents the derivation and validation of the analytical approach. The moment resistance of the whole connection can be obtained by assembling all the components together. A procedure for calculation was proposed to provide feasibility for designer and the analytical results were compared with the test results.
2

Estudo do canal reverso de alimentos descartados comercialmente no varejo: análise do canal de produtos lácteos / Study of the reverse channel of victuals discarded commercially in the retail: analysis of the channel of milky products

Marangoni, Suzana Marcia 28 September 2010 (has links)
Este trabalho refere-se ao estudo de um canal reverso de distribuição de produtos lácteos. O objetivo foi verificar a estrutura do canal reverso de produtos lácteos não comercializados e como ocorre o seu gerenciamento. Entendem-se como produtos não comercializados, alimentos lácteos não vendidos pelos atacadistas e varejistas, cujos prazos de validade ainda não expiraram. Especificamente, buscou-se identificar o design do canal reverso desses alimentos e quais as funções de cada membro participante de seu canal de distribuição; investigar como é feito o gerenciamento em relação à coordenação, às operações comerciais e à logística reversa do canal em foco, além de identificar o portfólio de produtos em questão. A relevância do estudo está na importância crescente dos canais de distribuição, os quais têm se desenvolvido e inovado tanto por meio de seus diferentes formatos, quanto pela agregação de valor aos seus membros, como estratégia competitiva de mercado. Este estudo objetivou conhecer o caminho contrário percorrido pelos produtos em questão no canal de distribuição, então chamado reverso, em referência às movimentações de materiais no sentido inverso ao da cadeia de distribuição. Atualmente no Brasil descartam-se toneladas de produtos alimentares. Sendo assim, por meio desta pesquisa, buscou-se verificar se há uma estrutura reversa gerenciada para o descarte e/ou reaproveitamento de produtos não comercializados. Este trabalho constitui-se em uma pesquisa exploratória e qualitativa, sendo realizado estudo de casos, dentre os quais foram pesquisados uma indústria, três distribuidores, dois atacadistas e seis supermercados. Como instrumentos de coleta de dados foram utilizadas entrevistas em profundidade. O principal resultado identificado neste estudo demonstra que as empresas participantes do canal de distribuição de produtos lácteos não possuem uma estrutura definida para o gerenciamento do canal reverso, ou seja, estas não têm um modelo do caminho contrário percorrido pelos produtos em questão no canal de distribuição, apesar do interesse demonstrado pelas empresas. / This work refers to the study of a reverse channel distribution of diary products. The objective was to verify the structure of the reverse channel of diary products which were not commercialized and how their management occurs. It is understood as not commercialized products diary foods which were not commercialized by the wholesalers and retailers and which the validity data has not expired yet. This work tried to identify specifically the reverse channel design of these foods and the function of each participant member of the channel of distribution; to investigate how management is made regarding the coordination, the commercial transactions and logistic channel reverse in focus, and also identify the portfolio of products in question. The relevance of the study is due to the increasing importance of the distribution channels, which have developed and innovated by means of different formats, as well as for value aggregation to its members, as a competitive market strategy. The objective of this study is to know the contrary path of the products in question in the distribution channel, which is called reverse, in reference to the movements of materials in the inverse direction to the one of the distribution chain. Currently in Brazil tons of alimentary products are disposed. Therefore, by means of this research, the intention is to verify if there is a reverse management structure for the disposal and/or reuse of not commercialized products. This work consists in an exploratory and qualitative research, being carried out through case studies, which researched an industry, three distributors, two wholesalers and six supermarkets. As instruments of data collection the procedure used was in depth interviews. The main result identified in this study was that the participating companies of the distribution channel of diary products do not have a defined structure for managing the reverse channel, that is, there is no model of the contrary path of the products in question in the distribution channel, even though the companies show interest.
3

Estudo do canal reverso de alimentos descartados comercialmente no varejo: análise do canal de produtos lácteos / Study of the reverse channel of victuals discarded commercially in the retail: analysis of the channel of milky products

Suzana Marcia Marangoni 28 September 2010 (has links)
Este trabalho refere-se ao estudo de um canal reverso de distribuição de produtos lácteos. O objetivo foi verificar a estrutura do canal reverso de produtos lácteos não comercializados e como ocorre o seu gerenciamento. Entendem-se como produtos não comercializados, alimentos lácteos não vendidos pelos atacadistas e varejistas, cujos prazos de validade ainda não expiraram. Especificamente, buscou-se identificar o design do canal reverso desses alimentos e quais as funções de cada membro participante de seu canal de distribuição; investigar como é feito o gerenciamento em relação à coordenação, às operações comerciais e à logística reversa do canal em foco, além de identificar o portfólio de produtos em questão. A relevância do estudo está na importância crescente dos canais de distribuição, os quais têm se desenvolvido e inovado tanto por meio de seus diferentes formatos, quanto pela agregação de valor aos seus membros, como estratégia competitiva de mercado. Este estudo objetivou conhecer o caminho contrário percorrido pelos produtos em questão no canal de distribuição, então chamado reverso, em referência às movimentações de materiais no sentido inverso ao da cadeia de distribuição. Atualmente no Brasil descartam-se toneladas de produtos alimentares. Sendo assim, por meio desta pesquisa, buscou-se verificar se há uma estrutura reversa gerenciada para o descarte e/ou reaproveitamento de produtos não comercializados. Este trabalho constitui-se em uma pesquisa exploratória e qualitativa, sendo realizado estudo de casos, dentre os quais foram pesquisados uma indústria, três distribuidores, dois atacadistas e seis supermercados. Como instrumentos de coleta de dados foram utilizadas entrevistas em profundidade. O principal resultado identificado neste estudo demonstra que as empresas participantes do canal de distribuição de produtos lácteos não possuem uma estrutura definida para o gerenciamento do canal reverso, ou seja, estas não têm um modelo do caminho contrário percorrido pelos produtos em questão no canal de distribuição, apesar do interesse demonstrado pelas empresas. / This work refers to the study of a reverse channel distribution of diary products. The objective was to verify the structure of the reverse channel of diary products which were not commercialized and how their management occurs. It is understood as not commercialized products diary foods which were not commercialized by the wholesalers and retailers and which the validity data has not expired yet. This work tried to identify specifically the reverse channel design of these foods and the function of each participant member of the channel of distribution; to investigate how management is made regarding the coordination, the commercial transactions and logistic channel reverse in focus, and also identify the portfolio of products in question. The relevance of the study is due to the increasing importance of the distribution channels, which have developed and innovated by means of different formats, as well as for value aggregation to its members, as a competitive market strategy. The objective of this study is to know the contrary path of the products in question in the distribution channel, which is called reverse, in reference to the movements of materials in the inverse direction to the one of the distribution chain. Currently in Brazil tons of alimentary products are disposed. Therefore, by means of this research, the intention is to verify if there is a reverse management structure for the disposal and/or reuse of not commercialized products. This work consists in an exploratory and qualitative research, being carried out through case studies, which researched an industry, three distributors, two wholesalers and six supermarkets. As instruments of data collection the procedure used was in depth interviews. The main result identified in this study was that the participating companies of the distribution channel of diary products do not have a defined structure for managing the reverse channel, that is, there is no model of the contrary path of the products in question in the distribution channel, even though the companies show interest.
4

Robustness of connections to concrete-filled steel tubular columns under fire during heating and cooling

Elsawaf, Sherif Ahmed Elkarim Ibrahim Soliman January 2012 (has links)
Joint behaviour in fire is currently one of the most important topics of research in structural fire resistance. The collapse of World Trade Center buildings and the results of the Cardington full-scale eight storey steel framed building fire tests in the UK have demonstrated that steel joints are particularly vulnerable during the heating and cooling phases of fire. The main purpose of this research is to develop robust joints to CFT columns that are capable of providing very high rotational and tying resistances to make it possible for the connected beam to fully develop catenary action during the heating phase of fire attack and to retain integrity during the cooling phase of fire attack. This research employed the general finite element software ABAQUS to numerically model the behaviour of restrained structural subassemblies of steel beam to concrete filled tubular (CFT) columns and their joints in fire. For validation, this research compared the simulation and test results for 10 fire tests previously conducted at the University of Manchester. It was envisaged that catenary action in the connected beams at very large deflections would play an important role in ensuring robustness of steel framed structures in fire. Therefore, it was vital that the numerical simulations could accurately predict the structural behaviour at very large deflections. In particular, the transitional behaviour of the beam from compression to catenary action presented tremendous difficulties in numerical simulations due to the extremely high rate of deflection increase. This thesis will explain the methodology of a suitable simulation method, by introducing a pseudo damping factor. The comparison between the FE and the experimental results demonstrates that the 3-D finite element model is able to successfully simulate the fire tests. The validated ABAQUS model was then applied to conduct a thorough set of numerical studies to investigate methods of improving the survival temperatures under heating in fire of steel beams to concrete filled tubular (CFT) columns using reverse channel connection. This study investigated five different joint types of reverse channel connection: extended endplate, flush endplate, flexible endplate, hybrid flush/flexible endplate and hybrid extended/flexible endplate. The connection details investigated include reverse channel web thickness, bolt diameter and grade, using fire-resistant (FR) steel for different joint components (reverse channel, end plate and bolts) and joint temperature control. The effects of changing the applied beam and column loads were also considered. It is concluded that by adopting some of the joint details to improve the joint tensile strength and deformation capacity, it is possible for the beams to develop substantial catenary action to survive very high temperatures. This thesis also explains the implications on fire resistant design of the connected columns in order to resist the additional catenary force in the beam. The validated numerical model was also used to perform extensive parametric studies on steel framed structures using concrete filled tubular (CFT) columns with flexible reverse channel connection and fin plate connection to find means of reducing the risk of structural failure during cooling. The results lead to the suggestion that in order to avoid connection fracture during cooling, the most effective and simplest method would be to reduce the limiting temperature of the connected beam by less than 50°C from the limiting temperature calculated without considering any axial force in the beam.
5

Reverse Channel Training in Multiple Antenna Time Division Duplex Systems

Bharath, B N January 2013 (has links) (PDF)
Multiple-Input Multiple-Output (MIMO) communication using multiple antennas has received significant attention in recent years, both in the academia and industry, as they offer additional spatial dimensions for high-rate and reliable communication, without expending valuable bandwidth. However, exploiting these promised benefits of MIMO systems critically depends on fast and accurate acquisition of Channel State Information (CSI) at the Receiver (CSIR) and the Transmitter (CSIT). In Time Division Duplex (TDD) MIMO systems, where the forward channel and the reverse channel are the same, it is possible to exploit this reciprocity to reduce the overhead involved in acquiring CSI, both in terms of training duration and power. Further, many popular and efficient transmission schemes such as beam forming, spatial multiplexing over dominant channel modes, etc. do not require full CSI at the transmitter. In such cases, it is possible to reduce the Reverse Channel Training (RCT) overhead by only learning the part of the channel that is required for data transmission at the transmitter. In this thesis, we propose and analyze several novel channel-dependent RCT schemes for MIMO systems and analyze their performance in terms of (a) the mean-square error in the channel estimate, (b) lower bounds on the capacity, and (c) the diversity-multiplexing gain tradeoff. We show that the proposed training schemes offer significant performance improvement relative to conventional channel-agnostic RCT schemes. The main take-home messages from this thesis are as follows: • Exploiting CSI while designing the RCT sequence improves the performance. • The training sequence should be designed so as to convey only the part of the CSI required for data transmission by the transmitter. • Power-controlled RCT, when feasible, significantly outperforms fixed power RCT.
6

Behaviour of reverse channel connection to concrete filled hollow tube columns under fire conditions

Jafarian, Mostafa January 2013 (has links)
This thesis presents the results of a research project to investigate the behaviour of the two components of a reverse channel connection to concrete filled tubular sections: the reverse channel and the steel tubular section, at both ambient and elevated temperatures. This research forms part of a European Union funded project on the robustness of joints to composite columns under fire conditions. The specific objectives of this research are to develop methods of quantifying the load-deformation behaviour at various temperatures of the two components. This research has been carried out through a combination of experiments, numerical simulations and analytical developments. Two series of tests have been carried out at different elevated temperatures, one for the reverse channels with lateral loads to the web applied as tensile loads through bolts and one for the concrete filled tubular sections under lateral loads applied through two steel plates (simulating the legs of a reverse channel) in the longitudinal direction of the section. These tests have been used to provide data for the validation of the numerical models based on using the general finite element package ABAQUS. The validated numerical models have been used to conduct a number of parametric studies to provide extensive data for the development of analytical methods to determine the load-deflection characteristics of the two components. For the reverse channel web, the load-deflection relationship consists of two parts and this research has developed analytical equations to predict initial stiffness, yield and ultimate resistance. The initial stiffness is based on extending and simplifying the Timoshenko solution for a plate under a block of lateral loads. The yield resistance is based on the yield line solution that the failure patterns were chosen based on the results attained from test and simulations. The ultimate resistance was calculated based on virtual work principle for the patterns considered in the yield resistance part. For the rectangular concrete filled tubular sections under lateral pulling forces applied through two plates, the load-deflection curve consists of two parts, depicting a linear phase followed by a nonlinear part. This research has developed expressions to calculate initial stiffness, yield resistance, and ultimate resistance. The initial stiffness is formulated according to the Timoshenko solution for a partially loaded plate. The yield resistance is determined by employing yield line solution for the yield patterns obtained from both the test and FE modelling. The ultimate resistance is evaluated by implementing the virtual work principle to the patterns considered in former part. The analytical load-deflection solutions have been compared with the numerical simulation and the experimental results and the agreement is generally satisfactory.
7

Contribuição ao estudo de perdas no varejo supermercadista: avaliação da quebra operacional e proposição de arranjo institucional para redução do desperdício de alimentos descartados comercialmente / Contribution to the study of losses in retail supermarket: evaluation of the operational break and propose of a institutional arrangement to reduce the waste of commercially disposed food

Corrêa, Stella Ribeiro Alves 14 October 2011 (has links)
A presente pesquisa tem como finalidade analisar a ocorrência, a forma e os motivos do desperdício de alimentos no varejo supermercadista, analisando um procedimento das rotinas varejistas chamado de quebra operacional. Nesse sentido, as perdas, resultado direto das quebras, será apresentada sob uma perspectiva tripla, gerando problemas de natureza financeira para o varejo e indústria e ambientais e sociais para a sociedade como um todo, sendo, portanto, uma prática incoerente com as demandas sustentáveis. Considerando o desperdício como um resultado de assimetrias no canal de distribuição e a necessidade das organizações em considerar a sociedade em suas estratégias de negócios, a pesquisa apresenta e discute canais reversos e canais de ciclo fechado como modelos institucionais de coordenação para o tratamento e redução de desperdício e o marketing social como ferramenta para a mudança de comportamento e geração de benefícios à sociedade por parte das organizações. Para ilustrar a conjugação dos temas propostos, a pesquisa apresentará o projeto Last Minute Market, que tem por finalidade a transformação do desperdício em recurso. Em sentido complementar apresentar-se-á a quantificação da quebra operacional de uma loja varejista localizada na cidade de Ribeirão Preto, SP e os mecanismos que a loja usa para gerenciar as perdas e o descarte de alimentos. A conclusão que se tem é que o varejo se esforça para que a perda seja reduzida, mas esforços são necessários para que o desperdício seja também evitado. / This study aims to analyse the occurrence, form and the reasons for food wastage in the retail business context, analyzing a routine retail procedure called operational break. In this sense, the losses, as a direct result of the operational break, will be presented in a triple perspective, generating financial problems to the retail business and industry and environmental and social problems to the society as a whole, therefore, an inconsistent practice with the sustainable demands. Considering the waste as a result of asymmetries in the distribution channel and the need for organizations to consider the society in their business strategies, the study presents and discusses reverse channels and closed-loop channels as institutional models of coordination for the treatment and waste reduction and the social marketing as a tool for behavior change and benefits generation to the society by the organizations. To illustrate the combination of the proposed topics, the research will presents the Last Minute Market project, which aims to convert the waste into resource. On complementary sense, a operational break quantification of a retail store at Ribeirão Preto, SP and the mechanisms that the store uses to manage the loss and disposal of food will be presented. The conclusion is that retail business is striving for the loss to be reduce, but efforts are necessary so that the waste could be also avoided.
8

Contribuição ao estudo de perdas no varejo supermercadista: avaliação da quebra operacional e proposição de arranjo institucional para redução do desperdício de alimentos descartados comercialmente / Contribution to the study of losses in retail supermarket: evaluation of the operational break and propose of a institutional arrangement to reduce the waste of commercially disposed food

Stella Ribeiro Alves Corrêa 14 October 2011 (has links)
A presente pesquisa tem como finalidade analisar a ocorrência, a forma e os motivos do desperdício de alimentos no varejo supermercadista, analisando um procedimento das rotinas varejistas chamado de quebra operacional. Nesse sentido, as perdas, resultado direto das quebras, será apresentada sob uma perspectiva tripla, gerando problemas de natureza financeira para o varejo e indústria e ambientais e sociais para a sociedade como um todo, sendo, portanto, uma prática incoerente com as demandas sustentáveis. Considerando o desperdício como um resultado de assimetrias no canal de distribuição e a necessidade das organizações em considerar a sociedade em suas estratégias de negócios, a pesquisa apresenta e discute canais reversos e canais de ciclo fechado como modelos institucionais de coordenação para o tratamento e redução de desperdício e o marketing social como ferramenta para a mudança de comportamento e geração de benefícios à sociedade por parte das organizações. Para ilustrar a conjugação dos temas propostos, a pesquisa apresentará o projeto Last Minute Market, que tem por finalidade a transformação do desperdício em recurso. Em sentido complementar apresentar-se-á a quantificação da quebra operacional de uma loja varejista localizada na cidade de Ribeirão Preto, SP e os mecanismos que a loja usa para gerenciar as perdas e o descarte de alimentos. A conclusão que se tem é que o varejo se esforça para que a perda seja reduzida, mas esforços são necessários para que o desperdício seja também evitado. / This study aims to analyse the occurrence, form and the reasons for food wastage in the retail business context, analyzing a routine retail procedure called operational break. In this sense, the losses, as a direct result of the operational break, will be presented in a triple perspective, generating financial problems to the retail business and industry and environmental and social problems to the society as a whole, therefore, an inconsistent practice with the sustainable demands. Considering the waste as a result of asymmetries in the distribution channel and the need for organizations to consider the society in their business strategies, the study presents and discusses reverse channels and closed-loop channels as institutional models of coordination for the treatment and waste reduction and the social marketing as a tool for behavior change and benefits generation to the society by the organizations. To illustrate the combination of the proposed topics, the research will presents the Last Minute Market project, which aims to convert the waste into resource. On complementary sense, a operational break quantification of a retail store at Ribeirão Preto, SP and the mechanisms that the store uses to manage the loss and disposal of food will be presented. The conclusion is that retail business is striving for the loss to be reduce, but efforts are necessary so that the waste could be also avoided.

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