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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

Application of quantitative vegetation reconstruction techniques to Late Holocene records at Inshriach Forest

Twiddle, Claire Louise January 2010 (has links)
This thesis considers some of the main issues surrounding the quantitative models that have been developed to reconstruct vegetation from pollen assemblages. Conducted within a pine dominated woodland, a palynologically difficult landscape, to determine vegetation changes over the late Holocene the results highlight the complexities of undertaking such studies in these contexts. Pollen productivity estimates were calculated from moss samples over the woodland using complete sets and derived subsets to detect influences of sampling design on resultant model output. Differences in the PPE sets were compared using reconstructions from simulation models in comparison to observed vegetation patterns. The results indicate that both parameter calculation and model reconstructions were influenced by the landscape form and composition. Sensitivity of the models to such small variations in parameter values heightens the need for robust data generation and increased investigation to controlling factors on pollen productivity. Performance of the reconstruction models experienced variation with respect to deposition basin size and site specific characteristics. Overall, the regional reconstructions proved to generate more confident estimates of vegetation cover whilst local scale reconstructions were subject to greater variability. Comparison of the quantitative modelling to standard interpretation and the modern analogue approach shows contrasts between the results obtained with respect to limitations associated with each method and the time frames, recent (ca. 100 years) and longer (ca. 3000 years), over which they were applied. Consequently, no one quantitative approach could be identified as being superior as site specific variations were recognised in relation to the most suitable approach. In response, a hierarchical technique is proposed to utilise the benefits of each technique and to obtain detailed information to strengthen interpretations. However, it is stressed study specific constrains that determine the available resources will influence the ability to fully apply this composite approach.
2

Case study for identification and evaluation of construction innovations: the Hotel Georgia project

Awuni, Roland Chiradam 05 1900 (has links)
Architectural, Engineering and Construction (AEC) projects are becoming more complex in terms of client requirements, stakeholder issues, physical, budget and time constraints, and safety and environmental concerns. These constraints have spawned ad-hoc innovations in some AEC projects, without structured frameworks for their assessment, resulting in varying success for these innovations. The primary goal of the thesis is to test an existing framework for evaluating innovative design and construction technologies for high-rise buildings by way of a case-study. The case study is a48-story structure (with an 8-level sub-grade parkade) in a downtown setting with significant constraints and challenges. Unlike most other assessment frameworks which are single-issue based (financial, cost, time or risk), a holistic method that captures a broad range of critical issues at the micro and macro levels is used to screen a number of construction innovations. The process highlights the primary difficulty in balancing stakeholder issues, technical/engineering requirements and project goals in assessing the overall feasibility and net benefits of an innovation. As a useful tool, it facilitates the engineering/technical judgment of proposed innovations and provides evidence of a sufficient trade-off between incremental 'cost and benefits' to justify a detailed evaluation and possible subsequent use of a subset of the innovations that passed successfully through a tiered first stage evaluation process. A secondary objective is to propose appropriate quantitative models for a detailed evaluation of the screened technologies that not only seeks to quantify incremental cost and benefits (e.g. time, increased revenue, etc.) but also assess the level of certainty (in benefits and cost) of innovative construction technologies. An illustrative evaluation provides insights as to the level of modeling and analysis required to evaluate an innovative or novel strategy both at the 'activity/work package' and project levels. The quantum of data required at the pre-construction planning stage coupled with the lack of easy to apply evaluation models probably accounts for the non-prevalence of detailed quantitative evaluation of innovative construction technologies on AEC projects, especially in terms of impact at the project level and the degree of certainty with which net benefits are likely to be achieved.
3

Case study for identification and evaluation of construction innovations: the Hotel Georgia project

Awuni, Roland Chiradam 05 1900 (has links)
Architectural, Engineering and Construction (AEC) projects are becoming more complex in terms of client requirements, stakeholder issues, physical, budget and time constraints, and safety and environmental concerns. These constraints have spawned ad-hoc innovations in some AEC projects, without structured frameworks for their assessment, resulting in varying success for these innovations. The primary goal of the thesis is to test an existing framework for evaluating innovative design and construction technologies for high-rise buildings by way of a case-study. The case study is a48-story structure (with an 8-level sub-grade parkade) in a downtown setting with significant constraints and challenges. Unlike most other assessment frameworks which are single-issue based (financial, cost, time or risk), a holistic method that captures a broad range of critical issues at the micro and macro levels is used to screen a number of construction innovations. The process highlights the primary difficulty in balancing stakeholder issues, technical/engineering requirements and project goals in assessing the overall feasibility and net benefits of an innovation. As a useful tool, it facilitates the engineering/technical judgment of proposed innovations and provides evidence of a sufficient trade-off between incremental 'cost and benefits' to justify a detailed evaluation and possible subsequent use of a subset of the innovations that passed successfully through a tiered first stage evaluation process. A secondary objective is to propose appropriate quantitative models for a detailed evaluation of the screened technologies that not only seeks to quantify incremental cost and benefits (e.g. time, increased revenue, etc.) but also assess the level of certainty (in benefits and cost) of innovative construction technologies. An illustrative evaluation provides insights as to the level of modeling and analysis required to evaluate an innovative or novel strategy both at the 'activity/work package' and project levels. The quantum of data required at the pre-construction planning stage coupled with the lack of easy to apply evaluation models probably accounts for the non-prevalence of detailed quantitative evaluation of innovative construction technologies on AEC projects, especially in terms of impact at the project level and the degree of certainty with which net benefits are likely to be achieved.
4

Case study for identification and evaluation of construction innovations: the Hotel Georgia project

Awuni, Roland Chiradam 05 1900 (has links)
Architectural, Engineering and Construction (AEC) projects are becoming more complex in terms of client requirements, stakeholder issues, physical, budget and time constraints, and safety and environmental concerns. These constraints have spawned ad-hoc innovations in some AEC projects, without structured frameworks for their assessment, resulting in varying success for these innovations. The primary goal of the thesis is to test an existing framework for evaluating innovative design and construction technologies for high-rise buildings by way of a case-study. The case study is a48-story structure (with an 8-level sub-grade parkade) in a downtown setting with significant constraints and challenges. Unlike most other assessment frameworks which are single-issue based (financial, cost, time or risk), a holistic method that captures a broad range of critical issues at the micro and macro levels is used to screen a number of construction innovations. The process highlights the primary difficulty in balancing stakeholder issues, technical/engineering requirements and project goals in assessing the overall feasibility and net benefits of an innovation. As a useful tool, it facilitates the engineering/technical judgment of proposed innovations and provides evidence of a sufficient trade-off between incremental 'cost and benefits' to justify a detailed evaluation and possible subsequent use of a subset of the innovations that passed successfully through a tiered first stage evaluation process. A secondary objective is to propose appropriate quantitative models for a detailed evaluation of the screened technologies that not only seeks to quantify incremental cost and benefits (e.g. time, increased revenue, etc.) but also assess the level of certainty (in benefits and cost) of innovative construction technologies. An illustrative evaluation provides insights as to the level of modeling and analysis required to evaluate an innovative or novel strategy both at the 'activity/work package' and project levels. The quantum of data required at the pre-construction planning stage coupled with the lack of easy to apply evaluation models probably accounts for the non-prevalence of detailed quantitative evaluation of innovative construction technologies on AEC projects, especially in terms of impact at the project level and the degree of certainty with which net benefits are likely to be achieved. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate
5

Tomada de decisão em redes logísticas de reciclagem de materiais através da dinâmica de sistemas / Decision making in logistics networks recycling of materials through System Dynamics

Matos, Daniel Anijar de 27 February 2012 (has links)
O objetivo precípuo deste trabalho é estudar um modelo da cadeia de suprimento de ciclo fechado, que é baseado no comportamento sistêmico, por intermédio da Dinâmica de Sistemas como ferramenta de tomada de decisão. Primeiramente adapta-se este modelo à realidade brasileira e, em seguida, aplica-se em uma rede de reciclagem, no caso o programa municipal de coleta seletiva de São Carlos. A proposta consiste na aplicação de conceitos que acarretem em melhorias nos processos reversos e, com isso, viabilizando sua cadeia e incentivando a implementação destas atividades em redes logísticas tradicionais. Após uma vasta investigação de modelos quantitativos para a rede reversa, uma caracterização da organização é realizada. Com a definição da análise estratégica, o próximo passo foi o ajuste do modelo aos padrões brasileiros com a descrição do programa. Concluída a etapa de validação e parametrização do modelo, para coincidi-lo à sua execução na prática, foram atribuídos cenários para o planejamento da rede com o horizonte de cinco anos. A versatilidade da Dinâmica de Sistemas em incorporar fatores específicos de uma estrutura, além de sua simplicidade e flexibilidade para a elaboração do problema, comparado aos demais modelos quantitativos abordados, são premissas corroboradas no estudo. No mesmo sentido, através da simulação do modelo baseada em 30 cenários, o que se pôde constatar é que 16 cenários são atrativos/viáveis e sem o investimento no aumento da quantidade de material coletado, o cenário torna-se inviável e o programa não é autossuficiente. Ademais, das quatro variáveis decididas para análise, a \"capacidade de coleta\" possui fator decisivo para o desempenho do sistema, sem contar que tanto as variáveis \"tempo de coleta\" e \"índice per capita\" dependem da primeira para a evolução dos materiais coletados. Por fim, a variável \"custo de transporte\" afeta consideravelmente a performance do sistema. / The principal aim of this work is to study a model of the closed-loop supply chain, which is based on systemic behavior, through the System Dynamics as a decision making tool. Firstly this model is adapted to the Brazilian issues and then it is applied in a recycling network, in this case it is the municipal solid waste of São Carlos city. The proposal involves the concepts application that leads to improve reverse processes, thereby performing the chain profitable and encouraging these activities implementation in \"forward logistics networks\". After an extensive investigation of reverse chains quantitative models, an organization description is performed. Thereafter strategic analysis definition, the next step was setting the model into Brazilian patterns based on the program design. Accomplished the stage of model validation and parameterization, to match it for its implementation in practice, scenarios were assigned to the network horizon planning of five years. The System Dynamics versatility to incorporate specific factors in such structure, in addition to its simplicity and flexibility to formulate a problem compared to other quantitative models covered, they are assumptions corroborated in the study. To the same effect, through model simulation based on 30 scenarios, it was found that 16 scenarios are feasible and without an investment to the increase of collected material, those scenarios are unfeasible and the system is not self-sufficient. Furthermore, between the four variables decided to analyze, the \"collection capacity\" has decisive factor to the system performance, besides the \"collection time\" and \"index per capita\" variables depend on the first one to the increase of collected materials. Finally, the cost transportation variable affects substantially the system performance.
6

Tomada de decisão em redes logísticas de reciclagem de materiais através da dinâmica de sistemas / Decision making in logistics networks recycling of materials through System Dynamics

Daniel Anijar de Matos 27 February 2012 (has links)
O objetivo precípuo deste trabalho é estudar um modelo da cadeia de suprimento de ciclo fechado, que é baseado no comportamento sistêmico, por intermédio da Dinâmica de Sistemas como ferramenta de tomada de decisão. Primeiramente adapta-se este modelo à realidade brasileira e, em seguida, aplica-se em uma rede de reciclagem, no caso o programa municipal de coleta seletiva de São Carlos. A proposta consiste na aplicação de conceitos que acarretem em melhorias nos processos reversos e, com isso, viabilizando sua cadeia e incentivando a implementação destas atividades em redes logísticas tradicionais. Após uma vasta investigação de modelos quantitativos para a rede reversa, uma caracterização da organização é realizada. Com a definição da análise estratégica, o próximo passo foi o ajuste do modelo aos padrões brasileiros com a descrição do programa. Concluída a etapa de validação e parametrização do modelo, para coincidi-lo à sua execução na prática, foram atribuídos cenários para o planejamento da rede com o horizonte de cinco anos. A versatilidade da Dinâmica de Sistemas em incorporar fatores específicos de uma estrutura, além de sua simplicidade e flexibilidade para a elaboração do problema, comparado aos demais modelos quantitativos abordados, são premissas corroboradas no estudo. No mesmo sentido, através da simulação do modelo baseada em 30 cenários, o que se pôde constatar é que 16 cenários são atrativos/viáveis e sem o investimento no aumento da quantidade de material coletado, o cenário torna-se inviável e o programa não é autossuficiente. Ademais, das quatro variáveis decididas para análise, a \"capacidade de coleta\" possui fator decisivo para o desempenho do sistema, sem contar que tanto as variáveis \"tempo de coleta\" e \"índice per capita\" dependem da primeira para a evolução dos materiais coletados. Por fim, a variável \"custo de transporte\" afeta consideravelmente a performance do sistema. / The principal aim of this work is to study a model of the closed-loop supply chain, which is based on systemic behavior, through the System Dynamics as a decision making tool. Firstly this model is adapted to the Brazilian issues and then it is applied in a recycling network, in this case it is the municipal solid waste of São Carlos city. The proposal involves the concepts application that leads to improve reverse processes, thereby performing the chain profitable and encouraging these activities implementation in \"forward logistics networks\". After an extensive investigation of reverse chains quantitative models, an organization description is performed. Thereafter strategic analysis definition, the next step was setting the model into Brazilian patterns based on the program design. Accomplished the stage of model validation and parameterization, to match it for its implementation in practice, scenarios were assigned to the network horizon planning of five years. The System Dynamics versatility to incorporate specific factors in such structure, in addition to its simplicity and flexibility to formulate a problem compared to other quantitative models covered, they are assumptions corroborated in the study. To the same effect, through model simulation based on 30 scenarios, it was found that 16 scenarios are feasible and without an investment to the increase of collected material, those scenarios are unfeasible and the system is not self-sufficient. Furthermore, between the four variables decided to analyze, the \"collection capacity\" has decisive factor to the system performance, besides the \"collection time\" and \"index per capita\" variables depend on the first one to the increase of collected materials. Finally, the cost transportation variable affects substantially the system performance.
7

Quantitative Models of Location, Inventory and Transportation Decisions for Sustainable Supply Chain Management

Becerra Muñoz, Pablo Andrés 26 July 2024 (has links)
Tesis por compendio / [ES] La gestión sostenible de las cadenas de suministro se ha transformado en un tema de alto interés entre profesionales e investigadores en el ámbito de la ingeniería industrial. El impacto que generan las actividades económicas en el medioambiente y en las comunidades donde éstas se ubican ha generado un incremento en el desarrollo de herramientas que permitan incorporar dichos impactos en las decisiones tomadas en el nivel estratégico de las empresas e industrias. Es así como surgen nuevos paradigmas respecto al modelo de producción, como por ejemplo la economía circular, donde se busca transitar desde una economía de producción lineal, hacia una circular reduciendo al mínimo la generación de desperdicios, ya sea material y/o energético. En este contexto, esta tesis doctoral, sustentada en una revisión de la literatura y en un análisis de modelos de optimización matemática de referencia, propone un marco conceptual como herramienta de soporte para seguir desarrollando modelos cuantitativos para dar soporte a los problemas de localización, inventario y transporte (LIT) en cadenas de suministro sostenibles, así como, un modelo de optimización multiobjetivo no lineal entero mixto (MOMINLP) para diseñar una cadena de suministro sostenible de bucle cerrado considerando las decisiones LIT, donde los aspectos de sostenibilidad: económico, medioambiental y social son incorporados en cada una de las decisiones anteriores. El modelo propuesto, denominado 3S-LIT, considera cuatro funciones objetivo que pretenden: (1) minimizar el coste total de la cadena de suministro; (2) minimizar los costes asociados a la emisión de CO2 equivalente; (3) minimizar el coste social relacionado con los accidentes laborales; y (4) maximizar el impacto social, medido como el incremento en cuanto a la generación de empleos directos e indirectos y la reducción en la cantidad de personas afectas por los riesgos del transporte dentro de la cadena de suministro. El modelo 3S-LIT ha sido validado en una empresa del sector minero del cobre obteniendo un mejor desempeño en los valores de las funciones objetivo respecto a los obtenidos en la situación actual. Además, el modelo 3S-LIT se ha comparado con un enfoque existente en la literatura científica obteniéndose unos resultados satisfactorios tanto en términos de funcionalidades como de resultados. Finalmente, el modelo propuesto de optimización matemática, 3S-LIT, es replicado en un modelo de simulación con el cual se estudiaron posibles escenarios de disrupción de la cadena de suministro con el objetivo de analizar su capacidad resiliente. / [CA] La gestió sostenible de les cadenes de subministrament s'ha transformat en un tema d'alt interès entre professionals i investigadors en l'àmbit de l'enginyeria industrial. L'impacte que generen les activitats econòmiques en el medi ambient i en les comunitats on aquestes se situen ha generat un increment en el desenvolupament d'eines que permeten incorporar aquests impactes en les decisions preses en el nivell estratègic de les empreses i indústries. És així com sorgeixen nous paradigmes respecte al model de producció, com per exemple l'economia circular, on se cerca transitar des d'una economia de producció lineal, cap a una circular reduint al mínim la generació de desaprofitaments, ja siga material i/o energètic. En aquest context, aquesta tesi doctoral, sustentada en una revisió de la literatura i en una anàlisi de models d'optimització matemàtica de referència, proposa un marc conceptual com a eina de suport per a continuar desenvolupant models quantitatius per a donar suport als problemes de localització, inventari i transport (LIT) en cadenes de subministrament sostenibles, així com, un model d'optimització multi-objectiu no lineal enter mixt (MOMINLP) per a dissenyar una cadena de subministrament sostenible de bucle tancat considerant les decisions LIT, on els aspectes de sostenibilitat: econòmic, mediambiental i social són incorporats en cadascuna de les decisions anteriors. El model proposat, denominat 3S-LIT, considera quatre funcions objectiu que pretenen: (1) minimitzar el cost total de la cadena de subministrament; (2) minimitzar els costos associats a l'emissió de CO2 equivalent; (3) minimitzar el cost social relacionat amb els accidents laborals; i (4) maximitzar l'impacte social, mesurat com l'increment quant a la generació d'ocupacions directes i indirectes i la reducció en la quantitat de persones afectes pels riscos del transport dins de la cadena de subministrament. El model 3S-LIT ha sigut validat en una empresa del sector miner del coure obtenint un millor acompliment en els valors de les funcions objectiu respecte als obtinguts en la situació actual. A més, el model 3S-LIT s'ha comparat amb un enfocament existent en la literatura científica obtenint-se uns resultats satisfactoris tant en termes de funcionalitats com de resultats. Finalment, el model proposat d'optimització matemàtica, 3S-LIT, és replicat en un model de simulació amb el qual es van estudiar possibles escenaris de disrupció de la cadena de subministrament amb l'objectiu d'analitzar la seua capacitat resilient. / [EN] Sustainable supply chain management has become a topic of great interest among practitioners and researchers in the field of industrial engineering. The impact generated by economic activities on the environment and the communities where they are located has generated an increase in the development of tools that allow the incorporation of these impacts in the decisions taken at the strategic level of companies and industries. This is how new paradigms emerge regarding the production model, such as the Circular Economy, which seeks to move from a linear production economy to a circular one by minimising the generation of waste, both material and energetic. In this context, this PhD thesis, supported by a state-of-the-art study and the analysis of benchmark mathematical optimisation models, presents a conceptual framework to provide the key elements that act as a valuable tool to further develop quantitative models of location, inventory and transport (LIT) problems in sustainable supply chains, and a novel mixed integer non-linear multi-objective mixed integer multi-objective optimisation model (MOMINLP) for designing a closed-loop sustainable supply chain considering location, inventory and transportation decisions, where economic, environmental and social sustainability aspects are incorporated in each of the above mentioned decisions. The proposed model, called 3S-LIT, considers four objective functions that aim to: (1) minimise the total cost of the supply chain, (2) minimise the costs associated with CO2 equivalent emissions, (3) minimise the social cost related to occupational accidents, and (4) maximise the social impact, measured as a higher generation of direct and indirect jobs and a lower number of people affected by transport risks within the chain. The 3S-LIT model has been applied in a company in the copper mining sector, confirming a better performance in the values of the objective functions compared to those obtained in the current situation. In addition, the mathematical optimisation model is replicated in a simulation model with which possible supply chain disruption scenarios were studied to analyse the resilience of the supply chain. / This thesis has been developed within the Research Centre on Production Management and Engineering (CIGIP) of the Universitat Politècnica de València, within the framework of the projects: "Industrial Production and Logistics Optimization in Industry 4.0" (i4OPT) (Ref. PROMETEO/2021/065) granted by the Valencian Regional Government and received funding from Grant RTI2018-101344-B-I00 funded by MCIN/AEI/10.13039/501100011033 and by “ERDF A way of making Europe”; “Validation of transferable results of optimisation of zero-defect enabling production technologies for supply chain 4.0” (CADS4.0-II) from the grant PDC2022-133957-I00; and by European Union Next GenerationEU/PRTR, and from the European Union’s Horizon Europe research and innovation programme under grant agreement No. 101070076 "Optimizing Production and Logistic Resources in the Time-critical Bio Production Industries in Europe" (CLARUS). It was also funded by the National Agency for Research and Development (ANID)/Scholarship Program/Doctorado Becas en el Extranjero/2020 – 72210174 and sponsored by the Universidad de Atacama as part of an academic improvement plan. / Becerra Muñoz, PA. (2023). Quantitative Models of Location, Inventory and Transportation Decisions for Sustainable Supply Chain Management [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/196651 / Compendio

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