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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.
71

En undersökning om möjligheterna att använda återanvändningsbara pallband till enhetslaster omlastade till träpallar. / An investigation of the possibility to use reusable pallet strapping for unit loads reloaded to wooden pallets.

Björk, Tomas January 2007 (has links)
<p>En undersökning om möjligheterna att använda återandvändningsbara pallband och de ekonomiska förutsättningarna för detta. En genomsökning av vad som finns på marknaden. Beräkning av de krafter som enhetslasten kan utsätta pallbanden för. Utveckling av egna förslag till återanvändningsbart pallband med snabbspänne och bandning på tre sidor. En översikt av de positiva och negativa effekter som blir vid ett byte från dagens bandning med PP-band till ett återanvändningsbart pallband</p> / <p>An investigation of the possibility to use reusable strapping and the economic conditions for this. Going trough what exist on the market. Calculation of the forces that the unit load can expose the strapping for. Developing of own suggestions for reusable strapping with quick buckle and strapping on three sides. A short look at the positive and negative effects that comes from a change from today’s strapping with PP-strap to a reusable strapping.</p>
72

GESTÃO E GERENCIAMENTO DOS RESÍDUOS SÓLIDOS URBANOS NA REGIÃO NORTE DO TOCANTINS: PERSPECTIVAS DE INCLUSÃO DE CATADORES À LUZ DA LEI 12.305-10

Colares, Raimunda Maria Rodrigues 13 May 2015 (has links)
Made available in DSpace on 2016-08-10T10:47:32Z (GMT). No. of bitstreams: 1 RAIMUNDA MARIA RODRIGUES COLARES.pdf: 1552702 bytes, checksum: 1d3ce11bdbe4ad96ed95104e80ec2983 (MD5) Previous issue date: 2015-05-13 / The accumulation of solid waste, dispersed inappropriately on the planet, has been one of the great problems facing humanity in recent times. The aim of this study was to evaluate the measures adopted by the State of Tocantins, in the cities of Araguaína and Araguatins regarding compliance with the National Solid Waste Policy to social and environmental inclusion of collectors. Therefore, we adopted the methodology of literature research regarding the following subjects: history of solid waste in Brazil and in the world, based in the context of sustainability; exposure of the main legal points established at PNRS and; social inclusion of the collector through the selective collection. We used a field research with a questionnaire applied to the collectors and municipal authorities, which were discussed based on the current literature. It was found that the collectors are mostly illiterate, have month income less than a minimum salary and that the cities do not have formal selective collection. We concluded that cities lean to replace the dumps for controlled landfill sites without the inclusion of waste collectors in formal selective collection. / O acúmulo de resíduos sólidos, dispersos de forma inadequada no planeta, tem sido um dos grandes problemas enfrentados pela humanidade nos últimos tempos. O objetivo desse trabalho foi avaliar as medidas adotadas pelo Estado do Tocantins, nas cidades de Araguaína e Araguatins, quanto ao cumprimento ao disposto na Política Nacional de Resíduos Sólidos, com a inclusão socioambiental dos catadores. Para tanto, adotou-se a metodologia de pesquisa bibliográfica referente aos seguintes temas: histórico dos resíduos sólidos no Brasil e no mundo fundamentado no contexto da sustentabilidade; exposição dos principais contornos jurídicos estabelecidos pela PNRS e a inclusão social do catador por meio da coleta seletiva. Usou-se uma pesquisa de campo com aplicação de questionário junto aos catadores e representantes do poder público municipal, os quais foram discutidos a luz da literatura atual. Foram constatados que os catadores são, em sua maioria analfabetos, tem renda mensal inferior a um salário mínimo e que os municípios não dispõem de coleta seletiva formal. Conclui-se que os municípios tendem a substituir os lixões por aterros controlados sem a inclusão dos catadores na coleta seletiva formal.
73

Re-surface : the novel use of deployable and actively-bent gridshells as reusable, reconfigurable and intuitive concrete shell formwork

Tang, Gabriel Jin-Peng January 2018 (has links)
Following a well-documented rise in the popularity of concrete shell application in the 20th century, thin concrete shells have experienced a global decline despite their potential as efficient structures with an economy of material use with aesthetics benefits. This phenomenon is subject to geographically determined socio-economic conditions and competition from other building solutions as a result of technological advancement in alternative construction systems. Importantly, their decline was attributed to limitations inherent to concrete shell formwork and construction methods. Being able to produce efficient shaping did not ensure that this method of construction is most cost efficient as it still remains difficult to construct double curved surfaces. The thesis addresses the limitations associated with past and present concrete shell building by proposing the use of actively-bent gridshells as re-configurable and reusable formwork for concrete shells to be designed and built. The hypothesis uses deployable scissor-jointed actively-bent gridshells as re-configurable and reusable formwork for concrete shell construction. This was developed from a series of Flash research (Benjamin, 2012) as student construction workshops to investigate the design and creation of actively-bent gridshells held between December 2008 and March 2011 in Sheffield. In this study, to understand this new system, scaled models of actively-bent gridshells were used as preliminary design aid. Deployed into three dimensional forms from a flexible flat grid mat, the structures were rigidized by bracing through triangulation restraints. The temporary rigid structure was subsequently enveloped with fabric onto which concrete was applied to create the concrete shell, thus acting as formwork. This formwork was then removed following the curing of the concrete cast to be reused repeatedly, or reconfigured into another concrete shell form. Hence, the thesis draws on the concepts, principles and ideas pertaining to three key architectural technologies: 1. concrete shell, 2. actively-bent gridshells and 3.fabric formwork. The thesis then presents a series of four prototype concrete shells constructed from different materials spanning between 1.3 meters and 2.45 meters in the workshops at the University of Edinburgh built between August 2014 and September 2015. For each experimental construction, the process of gridshell construction, fabric formwork preparation, concrete casting, gridshell formwork decentring and different design elements of openings, edges and anchorage abutments were analysed and discussed under the themes of construction, architectural tectonics and structure. The tectonic of process and material is understood and discussed based on the idea of stereogeneity (Manelius, 2012). Specifically, the relationship between gridshell as formwork and the concreting process was studied, analysed and assimilated in concrete shells built with progressive sophistication and elegance, culminating in a doubly-curved concrete shell that demonstrated both synclastic and anticlastic geometries, with further abutment simplification, edge leaning and physical openings incorporation. The study concludes with a physical concrete shell model formed by applying concrete onto fabric formwork to cover the Weald and Downland Jerwood gridshell. In the 1:20 scaled model, the proposed method is speculatively applied onto fabric stretched between pre-determined curvatures of the as-built gridshell. This formwork was subsequently removed for reuse, re-deployed and reconfigured. Using finite element analysis, the structural behaviour of the gridshell made of glass-fibre reinforced tubes and structural characteristics of the resultant concrete shell was checked. The interaction between the three technologies are discussed architectonically and structurally to inform guidelines for potential life-scale application. The thesis evidences the feasibility of the proposed system. It re-purposes a scaled model of a deployable gridshell as a physical modelling tool to facilitate concrete shell design, for both pure compression shells and "improper" shells, demonstrating its adaptability. It also promotes and reinvigorates concrete shells as possible architectural systems serving to instigate future research to revive concrete shell construction as an intelligent and intuitive way of creating structures with material economy, structural efficiency and visual elegance.
74

En undersökning om möjligheterna att använda återanvändningsbara pallband till enhetslaster omlastade till träpallar. / An investigation of the possibility to use reusable pallet strapping for unit loads reloaded to wooden pallets.

Björk, Tomas January 2007 (has links)
En undersökning om möjligheterna att använda återandvändningsbara pallband och de ekonomiska förutsättningarna för detta. En genomsökning av vad som finns på marknaden. Beräkning av de krafter som enhetslasten kan utsätta pallbanden för. Utveckling av egna förslag till återanvändningsbart pallband med snabbspänne och bandning på tre sidor. En översikt av de positiva och negativa effekter som blir vid ett byte från dagens bandning med PP-band till ett återanvändningsbart pallband / An investigation of the possibility to use reusable strapping and the economic conditions for this. Going trough what exist on the market. Calculation of the forces that the unit load can expose the strapping for. Developing of own suggestions for reusable strapping with quick buckle and strapping on three sides. A short look at the positive and negative effects that comes from a change from today’s strapping with PP-strap to a reusable strapping.
75

Optimal Pricing And Production Decisions In Reusable Container Systems

Atamer, Busra 01 July 2010 (has links) (PDF)
In this study, we focus on pricing and production decisions in reusable container systems with stochastic demand. We consider a producer that sells a single product to the customers in reusable containers with two supply options: (i) brand-new containers, (ii) returned containers from customers. Customers purchasing the products may return the containers to the producer to receive a deposit price. The return quantity depends on both customer demand and the deposit price determined by the producer. Hence, the producer has the opportunity to manipulate the return quantity via the deposit price. The unit cost of filling brand-new containers is different than the unit cost of refilling returned containers. We also consider resource restrictions on the production operations. Our setting represents certain hybrid manufacturing / remanufacturing systems where (i) the producer collects and recovers his own products, (ii) the producer supplies both brand-new and recovered products to his customers, and (iii) the customers are indierent between brand-new and recovered products. In this setting, we investigate the optimal pricing and production decisions in order to maximize the producer`s profit. Our approach utilizes non-linear optimization techniques. We characterize the optimal acquisition fee and the optimal order quantity of brand-new containers analytically and investigate the effect of parameters with an extensive computational study.
76

The Value Of Radio Frequency Identification Technology For Managing Pools Of Returnable Transport Items

Demir, Aysegul 01 September 2010 (has links) (PDF)
Limited asset visibility is a key problem in the management of returnable transport items (RTIs) like reusable containers, pallets and kegs. One tool to increase asset visibility is radio frequency identification (RFID) technology. However, RFID requires high investment cost and intensive efforts for implementation. In this study, we investigate the added value of using RFID technology for the management of the RTI pool in a closed-loop supply chain setting considering both costs and benefits. We have conducted a case study in a company which has recently started an RFID application in its closed-loop supply chain of RTIs. The aim of this case study is to identify and understand how an existing RTI pool is managed and the impact of using RFID technology on the management of such an RTI pool. In order to quantify the added value of RFID technology in RTI pool management, we search for the minimum cost solutions both without and with the use of RFID technology in a problem environment similar to that of our case study using the simulation optimization method. We also analyze the impact of using RFID technology on RTI pool management in terms of several performance measures, including RTI pool size, RTI lifetime, RTI trippage and the cycle time for RTIs to complete one trip in the closed-loop supply chain. In our study, we develop a number of discrete event simulation models of the identified closed-loop supply chain of RTIs operating with our predetermined decision rules for the RTI pool management using the simulation software Arena. We then develop our simulation optimization model in OptQuest for Arena in which the discrete event simulation models are embedded. The results from the simulation optimization method show that the added value of using RFID technology is mostly positive and it depends on the severity of the problematic issues in the closed-loop supply chain, as well as on the extent of improvements that RFID brings about.
77

Improved Solution Techniques For Trajectory Optimization With Application To A RLV-Demonstrator Mission

Arora, Rajesh Kumar 07 1900 (has links)
Solutions to trajectory optimization problems are carried out by the direct and indirect methods. Under broad heading of these methods, numerous algorithms such as collocation, direct, indirect and multiple shooting methods have been developed and reported in the literature. Each of these algorithms has certain advantages and limitations. For example, direct shooting technique is not suitable when the number of nonlinear programming variables is large. Indirect shooting method requires analytical derivatives of the control and co-states function and a poorly guessed initial condition can result in numerical unstable values of the adjoint variable. Multiple shooting techniques can alleviate some of these difficulties by breaking down the trajectory into several segments that help in reducing the non-linearity effects of early control on later parts of the trajectory. However, multiple shooting methods then have to handle more number of variables and constraints to satisfy the defects at the segment joints. The sie of the nonlinear programming problem in the collocation method is also large and proper locations of grid points are necessary to satisfy all the path constraints. Stochastic methods such as Genetic algorithms, on the other hand, also require large number of function evaluations before convergence. To overcome some of the limitations of the conventional methods, improved solution techniques are developed. Three improved methods are proposed for the solution of trajectory optimization problems. They are • a genetic algorithm employing dominance and diploidy concept. • a collocation method using chebyshev polynomials , and • a hybrid method that combines collocation and direct shooting technique A conventional binary-coded genetic algorithm uses a haploid chromosome, where a single string contains all the variable information in the coded from. A diploid, as the name suggests, uses pair of chromosomes to store the same characteristic feature. The diploid genetic algorithm uses a dominant map for decoding genotype into a stable, consistent phenotype. In dominance, one allele takes precedence over another. Diploidy and dominance helps in retaining the previous best solution discovered and shields them from harmful selection in a changing environment. Hence, diploid and dominance affect a king of long-term memory in the genetic algorithm. They allow alternate solutions to co-exist. One solution is expressed and the other is held in abeyance. In the improved diploid genetic algorithm, dominant and recessive genes are defined based on the fitness evaluation of each string. The genotype of fittest string is declared as the dominant map. The dominant map is dynamic in nature as it is replaced with a better individual in future generations. The concept of diploidy and dominance in the improved method mimics closer to the principles used in human genetics as compared to any such algorithms reported in the literature. It is observed that the improved diploid genetic algorithm is able to locate the optima for a given trajectory optimization problem with 10% lower computational time as compared to the haploid genetic algorithm. A parameter optimization problem arising from an optimal control problem where states and control are approximated by piecewise Chebyshev polynomials is well known. These polynomials are more accurate than the interpolating segments involving equal spaced data. In the collocation method involving Chebyshev polynomials, derivatives of two neighboring polynomials are matched with the dynamics at the nodal points. This leads to a large number of equality constraints in the optimization problem. In the improved method, derivative of the polynomial is also matched with the dynamics at the center of segments. Though is appears the problem size is merely increased, the additional computations improve the accuracy of the polynomial for a larger segment. The implicit integration step size is enhanced and overall size of the problem is brought down to one-fourth of the problem size defined with a conventional collocation method using Chebyshev polynomials. Hybrid method uses both collocation and direct shooting techniques. Advantages of both the methods are combined to give more synergy. Collocation method is used in the starting phase of the hybrid method. The disadvantage of standalone collocation method is that tuning of grid points is required to satisfy the path constraints. Nevertheless, collocation method does give a good guess required for the terminal phase of the hybrid method, which uses a direct shooting approach. Results show nearly 30% reduction in computation time for the hybrid approach as compared to a method in which direct shooting alone is used, for the same initial guess of control. The solutions obtained from the three improved methods are compared with an indirect method. The indirect method requires derivations of the control and adjoint equations, which are difficult and problem specific. Due to sensitivity of the costate variables, it is often difficult to find a solution through the indirect method. Nevertheless, these methods do provide an accurate result, which defines a benchmark for comparing the solutions obtained through the improved methods. Trajectory design and optimization of a RLV(Reusable Launch Vehicle) Demonstrator mission is considered as a test problem for evaluating the performance of the improved methods. The optimization problem is difficult than a conventional launch vehicle trajectory optimization problem because of the following two reasons. • aerodynamic lift forces in the RLV add one more dimension to the already complex launch vehicle optimization problem. • as RLV performs a sub orbital flight, the ascent phase trajectory influences the re-entry trajectory. Both the ascent and re-entry optimization problem of the RLV mission is addressed. It is observed that the hybrid method gives accurate results with least computational effort, as compared with other improved techniques for the trajectory optimization problem of RLV during its ascent flight. Hybrid method is then successfully used during the re-entry phase and in designing the feasible optimal trajectories under the dispersion conditions. Analytical solutions obtained from literature are used to compare the optimized trajectory during the re-entry phase. Trajectory optimization studies are also carried out for the off-nominal performances. Being a thrusting phase, the ascent trajectory is subjected to significant deviations, mainly arising out of solid booster performance dispersions. The performance index during rhe ascent phase is modified in a novel way for handling dispersions. It minimizes the state errors in a least square sense, defined at the burnout conditions ensure possibilities of safe re-entry trajectories. The optimal trajectories under dispersion conditions serve as a benchmark for validating the closed-loop guidance algorithm that is developed for the ascent phase flight. Finally, an on-line trajectory command-reshaping algorithm is developed which meets the flight objectives under the dispersion conditions. The guidance algorithm uses a pre-computed trajectory database along with some real-time measured parameters in generating the optimal steering profiles. The flight objectives are met under the dispersion conditions and the guidance generated steering profiles matches closely with the optimal trajectories.
78

Teens, Behavior Change & the Environment

Dowd, Kim 01 May 2011 (has links)
This thesis document presents the research, synthesis and design work completed for a system for object reuse. This work presents a user-centered process culminating in a service design (ReUseIt) and design guidelines to be employed when working with an audience of teenage girls and designing for behavior change with respect to the environment. This document includes a literature review covering environmental concerns, the relationship of design for behavior change, Generation Z, game design, and the historic value of objects. Research methods documented include journaling kits and designer-led research workshops embedded within middle school and high school art classes. ReUseIt supports improved behavior in relation to the environment through positive feedback around the reuse of objects and attachment of stories to objects. It is a service with touchpoints in shopping malls and a Facebook application. Reflections are offered on the design process undertaken and suggested best practices for creating embedded workshops within middle and high school classes.
79

Creating a closed-loop supply chain model and evaluating it through a business case for sustainability.

Girot, Lola, Kopf, Claudia January 2018 (has links)
Purpose The purpose of this thesis is to set up a closed-loop supply chain model for B2C online subscription box retailers and to develop a business case evaluating the model’s sustainability. Method This explorative thesis has an abductive research approach. Multiple-case studies are conducted and data from four cases and an expert are collected by conducting interviews. The research contains both qualitative and quantitative data. Findings A closed-loop SC model is created with regards to transport packaging. The model suggests that once the package is received by the consumer it can be returned in an empty state. After being cleaned it should be reused by the 3PL. The model’s sustainability is evaluated by developing a business case. Sustainable performance measures with regards to economic, social and environmental practice are assembled. The model enhances general social performance and environmental performance. Economic performance is mostly positively influenced. Options for cost savings in order to improve the economic performance of the model are suggested by the researchers. Practical implications The work provides businesses within the online B2C subscription box retail with a model for a possible closed-loop supply chain with regards to transport packaging. The business case for sustainability can be applied as a guideline to evaluate the model or similar ones. Researchers give suggestions on adapting packaging to enhance economic performance. Societal implications This thesis points out possible environmental and social benefits that may be achieved by a closedloop supply chain model. Besides waste and emission reduction, social performance such as employee motivation is positively influenced. Theoretical implications The thesis provides a model developed from theory and empirical data. The model does not only have practical implementations but also complements theory where a gap has earlier been identified. Through the business case for sustainability researchers contribute to theory since literature is scarce.
80

Construção e difusão colaborativa do conhecimento: uma experiência construtivista de educação em um ambiente virtual de aprendizagem

Cardoso, Antônio Luiz Mattos de Souza January 2010 (has links)
302 f. / Submitted by Suelen Reis (suziy.ellen@gmail.com) on 2013-04-29T17:50:39Z No. of bitstreams: 1 Tese - Antonio Cardoso.pdf: 4362473 bytes, checksum: 36135e27a3f35c3350bdfd333feec8b1 (MD5) / Approved for entry into archive by Maria Auxiliadora Lopes(silopes@ufba.br) on 2013-05-17T18:40:35Z (GMT) No. of bitstreams: 1 Tese - Antonio Cardoso.pdf: 4362473 bytes, checksum: 36135e27a3f35c3350bdfd333feec8b1 (MD5) / Made available in DSpace on 2013-05-17T18:40:35Z (GMT). No. of bitstreams: 1 Tese - Antonio Cardoso.pdf: 4362473 bytes, checksum: 36135e27a3f35c3350bdfd333feec8b1 (MD5) Previous issue date: 2010 / No âmbito da Educação a Distância, os Ambientes Virtuais de Aprendizagem na Web ganham importância crescente. Alguns deles com grande impacto de público, em diferentes instituições de ensino tanto públicas e quanto particulares. Por mais paradoxal que seja, este fenômeno amplo e global abre espaço para o despertar de pequenas soluções similares que buscam atender a necessidades particulares de ensino e aprendizagem on-line de grupos locais. Neste universo em expansão, este trabalho descreve primariamente a trajetória de elaboração, construção e adaptação de um Ambiente Virtual de Aprendizagem na Web chamado Hospital Educacional, que nasceu a partir do desenvolvimento de uma solução de software baseada em ferramentas de Inteligência Artificial e aplicada com uma interface lúdica. Ele tem sido aplicado ininterruptamente em disciplinas de cursos de graduação presencial desde 2006-1, com uma proposta blended learning, haurindo benefícios de uma aprendizagem presencial e à distância. O cerne da prática pedagógica neste trabalho tem como objetivo específico promover o relacionamento aluno-aluno para a construção e difusão do conhecimento de maneira virtual e colaborativa sob mediação do professor. Como objetivo geral, este trabalho busca demonstrar o Hospital Educacional como um ambiente mediador de aprendizagem, que estimula o processo de ensino-aprendizagem e a participação dos alunos. A abordagem metodológica da pesquisa é a Fenomenológica-Hermenêutica, pois se busca compreender o uso deste ambiente de aprendizagem no contexto em que está inserido, através dos atores que o faz acontecer: o professor e os alunos. Como justificativa para execução deste trabalho, enumera-se a perspectiva de construir o conhecimento concebido pelos alunos, armazenando-o virtualmente no ambiente para ser a base de outras oportunidades de aprendizagem, através do uso de Objetos de Aprendizagem Reutilizáveis e, como segunda justificativa, possibilitar resgatar este conhecimento armazenado no ambiente para reconstruí-lo. São empregadas técnicas de pesquisa como Questionários, Entrevistas e Análise de documentos que, somados aos dados decorrentes das ações executadas pelos alunos no ambiente, auxiliam a compreender o uso do Hospital Educacional como um recurso de aprendizagem. Por meio destas técnicas de pesquisa, os resultados observados mostram um elevado nível de participação dos alunos, que aceitam entusiasticamente o ambiente e a sua proposta pedagógica. Estes resultados são expostos em forma de gráficos diversos e de um mosaico, construído a partir dos comentários dos alunos. / Salvador

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