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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

Development of a material handlingsystem for a high high-pressure processingmachinemachine: A study of conceptual solutions

Belin, Maximilian, Sjöström, Elvira January 2023 (has links)
When developing a material handling system (MHS) it is crucial to master the various aspects for each developing step to increase the efficiency of the MHS. This Master’s thesis is aimed to identify conceptual solutions of a MHS and analyse the advantages and challenges for each of the developed concepts. Automation and implementation into a factory setting has taken into great consideration for this study. Two research questions (RQ) and three goals were formulated: RQ1: Which conceptual solutions of a material handling system for a high-pressure processing machine can be developed? RQ2: What are the challenges and advantages of each designed concept in terms of automation and implementation? Goal1: Develop three conceptual solutions of a material handling system. Goal2: Identify target specifications and determine their margin and ideal values for evaluation of the three conceptual solutions. Goal3: Analyse each developed material handling system and determine which concept is best out of the three in relation to the target specifications Automation has proven to be a key cause for achieving an effective MHS on the market and the two main reasons for this are, one: the elimination of ongoing labour cost and second; an increase of the overall safety factor for the system. The thesis, using the design research methodology (DRM) type two, consisting of an in-depth literature review and case study that contributed to evaluation and comparison of developed concepts. The literature review contributed to identifying the necessary steps of the structure of the MHS and required tools for the development phase. For the case study, the projects developing phase were taken from Ulrich, Eppinger and Yang (2020) ´s developing method. Identified tools and knowledge from the literature was used throughout the entire case study such as multi criteria decision making (MCDM), computer aided design (CAD), material flow patterns, automation and high-pressure processing (HPP). The findings of the case study showed that there are multiple concepts that can be developed. However, fully automated MHS are preferred when analysing the advantages and challenges for each fully developed MHS concept. The study resulted in three MHS concepts. Two fully automated ones and one semi-automated. The two fully automated MHS concepts showed more promising results than the semi-automated one. This was based on the MCDM-matrix which evaluated every MHS concept in relation to multiple criteria and failure mode effect analysis (FMEA) which investigated safety factors such as human safety and risk of MHS failure. Calculations such as capital cost and operational cost was also considered when analysing the differences between the MHS concepts. A fully automated MHS is not necessarily more costly in capital investment compared to semi-automated systems for the same HPP machine. Human labourers are, in semi-automated systems however, more precise in packaging operations, but also raises the operational costs substantially.
72

Supporting Sustainable selection for lubricants in automotive industry : Constant velocity joint grease as a case study

Murugesan, Rajan, Raafat Youssef Afifi Elsisi, Mohamed January 2023 (has links)
Sustainability within automotive industry has been an important topic that is covered in several studies. Due to the multi-aspect nature of sustainability and the variety of the factors need to be taken in consideration when choosing a material, the decision-making process could be challenging. This study focuses on lubricants within the automotive industry and proposes a framework consisted of three milestones that aspire to assist automotive manufacturers in sustainable lubricant selection. The study uses LCA as an environmental assessment tool for fully formulated lubricants and multicriteria decision matrix to include other criteria indicators in the decision-making process quantitively. The study also contributes to the literature by performing LCA for fully formulated lubricants. The framework was applied on well-established case company within the automotive industry (Volvo Cars Corporation) in Sweden. The results showthe importance and significant impacts of the inclusion of the additives in LCA studies done on lubricants using CV joint grease as a case study. It also shows the effect of the organisational preferences on the final results of the framework.
73

Use of Building Energy Simulation Software in Early-Stage of Design Process / Användning av energisimuleringsprogram i tidiga skeden av byggprocessen

Li, Beidi January 2017 (has links)
In traditional planning process, energy analysts work on finalized architectural designs and have limited capability to amend inefficient energy features such as high aspect ratio. Energy efficiency being a major part of sustainable design, the need for performance-oriented design tools has become imminent. There is a wide range of energy simulation tools across the world. Crawley et al. (2005) proposes a plain comparison of the most common ones based on vendor-supplied information. The present report aims to identify simulation tools that can help architects making energy-efficient design decisions in early stage of building process and the most suitable programs will be tested on a standard case in Stockholm area with respect to their architecture, functionalities, usability and limitations.
74

A performance investigation of stormwater accommodations in Stockholm : A multi-criteria decision analysis / Utvärdering av prestandan hos dagvattensystem i Stockholm : En multikriterieanalys

Jonsson, Martin January 2017 (has links)
Stormwater management is a problematic area and has during the last 20 years been given an increased attention due to more pollution in the cities. The increased pollution and contaminants in stormwater implicates risks for animals, humans, the ecosystem and receiving recipients. Due to the increased attention, authorities, government and other stakeholders have developed measurements to deal with the problem. Stormwater accommodations and other type of stormwater detainment has been developed with increased modern technology and functionality to fit specific areas where different type of pollutants can vary. Stormwater treatment are necessary because it creates social, environmental and technical advantages combined with protection of ecosystem, increased multifunctionality when combining for example stormwater ponds in nature, parks or urban and rural environment. This report describes seven diverse types of stormwater accommodations systems; rain garden, stormwater ponds, wells, screen basins, infiltration trenches, pipe-/concrete magazine and swales in accordance from Structor Mark Stockholm. From these seven accommodations, three were chosen to be included in Multi Criteria Decision Analysis (MCDA). The purpose of the MCDA was to evaluate four different categories linked to stormwater, which are environment, social, technology and economical categories. These categories are broad concepts; therefore, parameters were developed to narrow down the areas within the concept, from which the area of investigation was founded within. The parameters created for each category are degree of purification for the environmental category, performance and maintenance for the technological category, aesthetical and social benefits for the social category and costs and risk for the economical category. The criteria developed from these parameters are specific topics that was scored from the scale between 0-5, where 0 = insignificant, 1= Low, 2= Moderate, 3= Major, 4=High, 5= Very high. A reference option was also created, considered as “no commercial treatment of stormwater”, only to transport stormwater. This reference option was also referred to as a zero-alternative and is drainage by piping. The scoring was conducted by stakeholders and citizens of Stockholm. The scoring of the three chosen stormwater accommodations and the reference alternative after calculating the mean value and summarize it resulted in that stormwater pond received the highest overall score of 11.9 followed by rain gardens 11.4, infiltration trench 11.3 and drainage by piping 7.3. The stakeholders are influential people that works either with stormwater, layout and planning or maintenance personnel. Citizens of Stockholm provided inputs only in regards of the social aspects. A total of 20 stakeholders were contacted and 5 stakeholders participated in the scoring procedure. Citizens were interviewed on the street; a total of 60 people was asked to participate and 13 people decided to participate in the scoring procedure of the social aspects. Although, the attendance of stakeholders was low, they are still considered important to this project since they provided the scoring of the criteria for each respective category (environment, technology, social and economic). In regards of the low attendance by stakeholders, this resulted in a way that it became hard to distinguish the result between the different stormwater accommodation. Therefore, it was hard to determine which stormwater accommodation that was the best out ofthe ranking provided by the MCDA. A benefit by using MCDA as a tool in this case, gave an indication that the MCDA can work as a framework to decision makers, even though the result in this case became difficult to manage and distinguish between the different stormwater accommodations. Finally, the method, layout and analysis itself can provide means of measurements for stormwater investigations when the purpose is to choose between the best stormwater systems included in the MCDA. Inputs from stakeholders concluded that depending on what type of existing circumstances, there must be a site-specific evaluation to treat every area as a unique area, before deciding what type of stormwater accommodation to apply to that specific location. / Dagvattenhantering är ett problematiskt område som under de senaste 20 åren har fått allt mer uppmärksamhet då mer föroreningar uppdagats i städerna. Den ökande föroreningen av dagvatten tenderar att orsaka en större risk för djur, människor, ekosystem och recipienter dit dagvatten rinner. På grund av uppmärksamheten som dagvattenhanteringen har fått, har myndigheter, regering och andra intressenter utvecklat dagvatten teknologin ytterligare för att skapa en modern dagvattenstrategi för att handskas med problemet. Dagvattenhantering är nödvändigt eftersom den skapar sociala, miljömässiga och tekniska fördelar samt om dagvattensystemen kombineras med funktionalitet så kan detta ge ökat skydd för ekosystemen samt förbättrad hälsa hos befolkningen i städerna. Den här rapporten beskriver sju olika typer av dagvattensystem så som; rain gardens, dagvattendammar, brunnar, skärmbassänger, svackdiken, rör-/betong magasin samt krossdiken på begäran av Structor Mark Stockholm. Utav dessa 7 dagvattensystem, ingick 3 anläggningar i en så kallad multi-criteria decision analysis (MCDA). Syftet med en MCDA är att utvärdera fyra olika kategorier som kan förknippas med dagvattenhantering. Kategorierna är miljömässiga, sociala, tekniska och ekonomiska. Dessa kategorier utger dock ett brett budskap och för att begränsa analysen så skapades parametrar. Dessa parametrar skapas utifrån varje enskild kategori. För den miljömässiga kategorin skapades parametern grad av rening, för den tekniska kategorin skapades parametern prestanda och underhåll, för den sociala kategorin skapades parametern estetiska och sociala fördelar, och slutligen för den ekonomiska kategorin skapades parametern kostnader och risker. Utifrån dessa parametrar skapades sedan kriterier med specifika huvudämnen som kan bedömas enligt en poängskala från 0-5 där 0 = insignificant, 1=Low, 2= Moderate, 3= Major, 4= High, 5= Very high. Tre dagvattensystem inkluderas i MCDA vilket var; rain gardens, dagvattendammar, krossdiken vars syfte är att rena och fördröja dagvatten. Ett referensalternativ skapades också som ävenkallas ”zero-alternative”, vilket anses inte ha någon rening av dagvatten utan är endast ett transportsystem för dagvatten. Detta referensalternativ kallas drainage by piping. Poängsättningen gjordes av intressenter och invånare i Stockholm. Intressenterna är människor som arbetar med dagvattenhantering antingen på planeringsstadiet eller ute i fält som drift och underhålls personal. Invånare i Stockholm bedömde endast den sociala kategorin eftersom det kan sakna kunskap och insyn i det miljömässiga, tekniska och ekonomiska detaljerna. Totalt kontaktades 20 intressenter där 5 personer valde att medverka i MCDA. Invånare i Stockholm intervjuades på stan, totalt frågades ca 60 personer varav 13 personer valde att medverka i poängsättningen. Poängsättningen av de tre valda dagvattensystemen samt referensalternativet, efter beräkningav medelvärdet samt den totala summeringen resulterade i att dagvattendammar fick den hösta poängen 11,9 hamnade rain garden på andra plats med 11,4, krossdike på tredje plats med 11,3 samt referensalternativet på en fjärde plats med 7,3. De tre dagvattensystemen hade ett relativt liknande slutgiltigt resultat. Dock så skilde sig den individuella kategoriska bedömningen av miljömässiga, tekniska, sociala samt ekonomiska aspekten med större varierande resultat. Även om deltagandet av intressenter var relativt lågt, endast 25 % av det kontaktade intressenterna valde att ställa upp, så anses dessa intressenter vara viktiga för det här projektet då de, utifrån deras kunskap, bedömer det uppsatta kriterierna och det är denna bedömning som resultatet baseras på. Resultaten mellan det olika dagvattenanläggningarna som var inkluderade i MCDA var svåra att särskilja, troligtvis beroende på att ingen viktningsmetod användes. Däremot så är en fördel med MCDA som verktyg i det här fallet, att det gav en indikation på att MCDA kan fungera som ett stödjande verktyg för beslutsfattare även om resultatet i det här fallet var svårt att särskilja. Själva metoden, upplägget och analysen kan användas som medel för att avgöra vilken typ av dagvattenanläggning som passar bäst utifrån de kriterier som är uppsatta. Slutligen så gav intressenterna en påvisning att dagvattenanläggningar ska konstrueras så att hänsyn tas till omkringliggande omständigheter, där varje plats ska ansesvara unik. Det krävs en platsspecifik utredning där hänsyn till geologiska, geotekniska,hydrologiska samt infrastrukturella och miljömässiga aspekter bör utredas innan valet av dagvattensystem bestäms.
75

Native app vs Web app: Multi-criteria decision-making for optimised mobile solution / Nativ-app eller webb-app: Multikriteriebeslut för optimerad mobillösning

Randleff, Veronica January 2018 (has links)
In today’s digital and mobile world it is more important than ever that companies offer a mobile solution for their costumers. Deciding which mobile solution to implement can be difficult. The purpose of this study is therefore to make this decision easier. Two mobile solutions, web apps and native apps, were compared in order to identify the most important factors that differentiate the two. By assigning the two mobile solutions one score each for every factor, we created a multi-criteria decision-making model. The model was then evaluated, improved and implemented as a decision-making tool. The second evaluation showed that the majority of the respondents agreed with the decision-making tool, suggesting that it could be applied as a recommendation for companies choosing between developing a native app and a web app. / I dagens digitala och mobila värld är det viktigare än någonsin för företag att erbjuda en mobil lösning för sina kunder. Att bestämma vilken mobil lösning som ska implementeras kan vara svårt och därför har denna studie för avsikt att underlätta detta beslut. Två mobila lösningar, webb-appar och nativ-appar, jämfördes för att kunna identifiera de viktigaste faktorerna som skiljer dem emellan. Genom att ge de två mobila lösningarna ett betyg var för varje faktor så kunde en multikriteriebeslutsmodell skapas, utvärderas och implementeras som ett beslutsverktyg. En andra utvärdering visade att majoriteten av de tillfrågade höll med beslutsverktyget vilket tyder på att det kan användas som rekommendation åt företag som väljer mellan att utveckla en nativ-app och en webb-app.
76

A Macro-Level Sustainability Assessment Framework for Optimal Distribution of Alternative Passenger Vehicles

Onat, Nuri 01 January 2015 (has links)
Although there are many studies focusing on the environmental impacts of alternative vehicle options, social and economic dimensions and trade-off relationships among all of these impacts were not investigated sufficiently. Moreover, most economic analyses are limited to life cycle cost analyses and do not consider macro-level economic impacts. Therefore, this thesis aims to advance the Life Cycle Sustainability Assessment literature and electric vehicle sustainability research by presenting a novel combined application of Multi Criteria Decision Making techniques with Life Cycle Sustainability Assessment for decision analysis. With this motivation in mind, this research will construct a compromise-programming model (multi-objective optimization method) in order to calculate the optimum vehicle distribution in the U.S. passenger car fleet while considering the trade-offs between environmental, economic, and social dimensions of the sustainability. The findings of this research provide important insights for policy makers when developing strategies to estimate optimum vehicle distribution strategies based on various environmental and socio-economic priorities. For instance, compromise programming results can present practical policy conclusions for different states which might have different priorities for environmental impact mitigation and socio-economic development. Therefore, the conceptual framework presented in this work can be applicable for different regions in U.S. and decision makers can generate balanced policy conclusions and recommendations based on their environmental, economic and social constraints. The compromise programming results provide vital guidance for policy makers when optimizing the use of alternative vehicle technologies based on different environmental and socio-economic priorities. This research also effort aims to increase awareness of the inherent benefits of Input-Output based a Life Cycle Sustainability Assessment and multi-criteria optimization.
77

Sustainability Assessment Of Wind Energy For Buildings

Noori, Mehdi 01 January 2013 (has links)
Due to increasing concerns for global climate change, onshore and offshore wind energy technologies have stimulated a tremendous interest worldwide, and are considered as a viable solution to mitigate the environmental impacts related to electricity generation. Although wind energy technologies have been considered as one of the cleanest energy sources, they have a wide range of direct and indirect environmental impacts when the whole supply chain is considered. This study aims to quantify the direct and indirect environmental impacts of onshore and offshore wind power technologies by tracing all of the economy-wide supply chain requirements. To accomplish this goal, we developed a comprehensive hybrid life cycle assessment (LCA) model in which process-based LCA model is combined with the economic input-output (EIO) analysis. The analysis results show that on average, concrete and steel and their supply chains are responsible for 37% and 24% of carbon footprint, consequently. On average, offshore wind turbines produce 48% less greenhouse gas emissions per kWh produced electricity than onshore wind turbines. For the onshore wind turbines, concrete, aggregates, and crushed stone approximately consume 95% of total water in this construction phase. On the other hand, concrete, lead, copper, and aggregate are responsible for around 90% of total water for the offshore wind turbines. It is also found that the more capacity the wind turbine has, the less environmental impact the wind turbine generates per kWh electricity. Moreover, based on the economic and environmental impacts of studied wind turbines and also three more nonrenewable energy sources, this study develops a decision making framework to understand the best energy source mix for a building in the state of Florida. This framework accounts for the uncertainty in the input material by deploying a Monte Carlo iii simulation approach. The results of decision making framework show that natural gas is a better option among nonrenewable sources. On the other hand, V90-3.0 MW offshore wind turbine is the best source of energy among renewable energy sources for a building. The findings of this research are critical for policy makers to understand the direct and indirect environmental impacts of different onshore and offshore wind energy systems. Also this study furnishes the decision maker with a range of possible energy mixes based on different economic and environmental weights.
78

Surface Modifications of Reverse Osmosis Membranes for Removal of Bromide and Reduction of Fouling

Seo, Joseph 01 June 2020 (has links) (PDF)
Reverse osmosis (RO) is widely used for water reuse and desalination. Although RO membranes are known for their high salt rejection and practical permeate flux, their performance can be impaired by fouling, and their removal of some disinfection byproducts and their precursors (e.g., bromide, N-Nitrosodimethylamine [NDMA]) does not meet drinking water standards. RO membrane modifications have been widely studied to overcome these limitations. In this research, RO membranes were grafted with cationic polymers to induce a positive charge on the RO membrane surface. This modification aimed at enhancing the rejection of negatively charged bromide ions by removing them from solution by binding them to the membrane surface. The results showed that the modified (positively charged) RO membranes achieved lower rejection (82% rejection) for bromide ions compared to the unmodified ones (94.5% rejection). This behavior was likely a result of increased concentration polarization of the bromide ions at the membrane surface and/or increase in porosity of the modified membranes. Calculations based on the film theory indicate that the concentration of bromide ions at the surface of the modified membrane was 1371 ppm compared to 1307 ppm at the surface of the unmodified membrane. Evidently, the polymer attraction energy was not sufficient to keep the bromide ions attached to the membrane surface and prevent their diffusion across the membrane. Although the goal of the modification in the current study (i.e., enhancing removal of bromide ions) was not met, the permeate flux of the modified membrane was improved compared to the unmodified one. The literature suggests that increasing flux after modification is likely a result of increase in membrane pore size and hydrophilicity. In addition to the experimental work conducted in this study, a multi-criteria decision analysis was performed to prioritize research on surface modifications of reverse osmosis membranes. It was found that surface modifications have been mainly focused on reducing membrane fouling and to a much lower extent on removal of disinfection byproducts and their precursors. The RO membrane modification alternatives for fouling reduction and N-Nitrosodimethylamine (NDMA) removal were ranked based on multiple criteria using the Analytical Hierarchy Process (AHP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS). This multi-criteria decision analysis process resulted in the identification of the top five promising modifications to reduce fouling and improve NDMA rejection. Grafting and coating the RO membranes with complex polymeric salts were the highest ranked modification approaches to reduce fouling. Heat-treatment of RO membranes achieved the highest NDMA rejection (98%); however, this technique was the second highest ranked modification approach for NDMA removal because it scored lower for other evaluation criteria.
79

Application of the Analytic Hierarchy Process Optimization Algorithm in Best Management Practice Selection

Young, Kevin D. 29 September 2006 (has links)
The efficiency of a best management practice (BMP) is defined simply as a measure of how well the practice or series of practices removes targeted pollutants. While this concept is relatively simple, mathematical attempts to quantify BMP efficiency are numerous and complex. Intuitively, the pollutant removal capability of a BMP should be fundamental to the BMP selection process. However, as evidenced by the absence of removal efficiency as an influential criterion in many BMP selection procedures, it is typically not at the forefront of the BMP selection and design process. Additionally, of particular interest to any developer or municipal agency is the financial impact of implementing a BMP. Not only does the implementation cost exist, but there are long-term maintenance costs associated with almost any BMP. Much like pollutant removal efficiency, implementation and maintenance costs seem as though they should be integral considerations in the BMP selection process. However, selection flow charts and matrices employed by many localities neglect these considerations. Among the categories of criteria to consider in selecting a BMP for a particular site or objective are site-specific characteristics; local, state, and federal ordinances; and implementation and long-term maintenance costs. A consideration such as long-term maintenance cost may manifest itself in a very subjective fashion during the selection process. For example, a BMPs cost may be of very limited interest to the reviewing locality, whereas cost may be the dominant selection criterion in the eyes of a developer. By contrast, the pollutant removal efficiency of a BMP may be necessarily prioritized in the selection process because of the required adherence to governing legislation. These are merely two possible criteria influencing selection. As more and more selection criteria are considered, the task of objectively and optimally selecting a BMP becomes increasingly complex. One mathematical approach for optimization in the face of multiple influential criteria is the Analytic Hierarchy Process. "The analytic hierarchy process (AHP) provides the objective mathematics to process the inescapably subjective and personal preferences of an individual or a group in making a decision" (Schmoldt, 2001, pg. 15). This paper details the development of two categories of comprehensive BMP selection matrices expressing long-term pollutant removal performance and annual maintenance and operations cost respectively. Additionally, the AHP is applied in multiple scenarios to demonstrate the optimized selection of a single BMP among multiple competing BMP alternatives. Pairwise rankings of competing BMP alternatives are founded on a detailed literature review of the most popular BMPs presently implemented throughout the United States. / Master of Science
80

A decision support model for identification and prioritization of key performance indicators in the logistics industry

Kucukaltan, B., Irani, Zahir, Aktas, E. 09 March 2016 (has links)
Yes / Performance measurement of logistics companies is based upon various performance indicators. Yet, in the logistics industry, there are several vaguenesses, such as deciding on key indicators and determining interrelationships between performance indicators. In order to resolve these vaguenesses, this paper first presents the stakeholder-informed Balanced Scorecard (BSC) model, by incorporating financial (e.g. cost) and non-financial (e.g. social media) performance indicators, with a comprehensive approach as a response to the major shortcomings of the generic BSC regarding the negligence of different stakeholders. Subsequently, since the indicators are not independent of each other, a robust multi-criteria decision making technique, the Analytic Network Process (ANP) method is implemented to analyze the interrelationships. The integration of these two techniques provides a novel way to evaluate logistics performance indicators from logisticians' perspective. This is a matter that has not been addressed in the logistics industry to date, and as such remains a gap that needs to be investigated. Therefore, the proposed model identifies key performance indicators as well as various stakeholders in the logistics industry, and analyzes the interrelationships among the indicators by using the ANP. Consequently, the results show that educated employee (15.61%) is the most important indicator for the competitiveness of logistics companies.

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