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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.
11

Project Managers' Capacity-Planning Practices for Infrastructure Projects in Qatar

Ojo, Emmanuel Opeyemi 01 January 2019 (has links)
Infrastructure project delays and cost overrun are caused by ineffective use of organizational skills, processes, and resources by project managers in the construction industry. Cost overrun and schedule delay in Qatari infrastructure projects have had damaging effects on the national economy by way of claims and litigation, contractual disputes, delays in dependent projects, and project abandonment. The purpose of this qualitative case study was to explore the perceptions of project managers regarding how they utilize capacity-planning practices to mitigate project schedule delay and cost overrun in government-funded infrastructure projects in Qatar. This study was framed by three conceptual models developed by Gill to outline the capacity management needs within a construction company: (a) the time horizon model, (b) the individual-organization-industry levels model, and (c) the capacity development across components model. Date were collected from semistructured interviews with 8 participants, observational field notes, and archival data regarding Qatari infrastructure project managers' experiences in capacity-planning practices. Thematic analysis of textual data and cross-case synthesis analysis yielded 5 conceptual categories that encompassed 15 themes. The conceptual categories were (a) resources to meet performance capacity, (b) knowledgeable and skillful staff, (c) short- and long-term planning strategy, (d) cost overrun issue, and (e) time management. Findings may be used to promote timely completion of infrastructure projects, which may benefit citizens, construction companies, and the economy of Qatar.
12

The risk assessment of aircraft runway overrun accidents and incidents

Kirkland, Ian D. January 2001 (has links)
The UK Civil Aviation Authority has recognised the need for protection against the runway overrun over and above the standard protection recommended by ICAO. Normal protection for the aircraft is provided in ICAO's Annex 14 by the strip at the end of a runway, and a recommendation for the installation of a Runway End Safety Area (RESA). In the UK, the CAA has stated that as part of their safety management system the aerodrome licensee should review the RESA distance requirement for their individual circumstances on an annual basis through a risk assessment. However, current industry knowledge of circumstantial factors in runway overruns is limited. Also, current models that are used to determine likely overrun wreckage locations and RESA dimensions take no account of the operational conditions surrounding the overruns or the aerodrome being assessed. This study has attempted to address these needs by highlighting common factors present in overrun occurrences through the compilation and analysis of a database of runway overruns, and through the construction of a model of wreckage location that takes account of the conditions at an individual aerodrome. A model of overrun probability has been constructed and the consequences of an overrun have been examined. One outcome of the study is an awareness that the industry is in an extremely poor state of knowledge of operational characteristics of non-accident flights, which if not addressed will be a major barrier to future advancement of aviation safety improvement and research.
13

Uncertainties and cost overruns in Construction Industry : An explanatory multiple case study investigating the differences in cost management under uncertainties in conventional and green construction companies

El Khawas, Abdel Rahim, Aghaei, Sanaz January 2020 (has links)
Abstract Background Construction industry greatly affect the environment in the aspect of energy consumption and its contribution to global warming. Accordingly, green building construction is significantly growing, which makes it an interesting topic for researchers. Green buildings are defined as buildings constructed according to sustainability standards that keeps the natural environment healthy. However green construction is challenging in the economic aspect and the cost efficiency. Based on the researches, uncertainty is a main reason for cost overrun. In addition, procedures in early stages of the project is of great importance and have influence on the costs. However, further study is needed to identify the differences between conventional and green construction companies regarding uncertainties, cost overrun, and uncertainty mitigation techniques. Purpose The focus of this research is to compare two types of construction companies (conventional and sustainable) in the aspect of uncertainties as inevitable part of risks, it’s effect on cost overrun, and techniques being used in the pre-construction phase to mitigate them. Method Multiple-case study was conducted, and two construction companies were selected of each type. This research is a qualitative study with abductive approach. The empirical data were collected by conducting semi-structured interviews with several positions in each company. Also, secondary data were collected from companies’ archival reports and documents, and from scientific blogs. Conclusion The findings of this research indicate that sustainability creates fields of uncertainties extra to those existing in conventional construction. The study revealed the direct effect of uncertainties on cost, and the indirect effect by generating events which cause overruns in cost. Moreover, Companies work on improving managerial skills in the preconstruction phase to mitigate the effect of uncertainties and to reduce probability of cost overrun occurrence in both sustainable and convention construction companies. While in sustainable construction, additional techniques and efforts are needed as technology, artificial intelligence, and hiring external resources and staff.
14

Evaluation of Viability of Lactobacillus acidophilus La-5 During Simulated Digestion Process Using a Dynamic In Vitro Model

Tharani, Jenifer 01 May 2012 (has links) (PDF)
In recent years, there has been an upsurge in medical research assessing the therapeutic benefits of probiotic bacteria and growing commercial interest in food fortification with these bacteria. Probiotic bacteria such as L. acidophilus are known to be predominant Lactobacilli species in the intestinal tract of healthy humans and suggested to provide clinical health benefits such as enhancement of immunity against intestinal infections, prevention of diarrhea and hypercholesterolaemia and improvement in lactose utilization. Many studies have demonstrated the possibility of incorporating probiotic bacteria in an ice cream matrix and shown its viability can be maintained throughout the shelf life of the ice cream. However, there is limited information about the protective effect of ice cream on viability of incorporated probiotic bacteria during simulated gastric digestion using an in vitro dynamic model stomach. In phase one of this study, a preliminary study was conducted to determine the effect of air addition on the viability of L. acidophilus La-5. This was done by manufacturing low fat (4%) non-fermented ice cream mix supplemented with L. acidophilus La-5 to yield an initial population of 107cfu/g. The mix was processed with 60% and 100% overrun (OR) and stored at -10ᵒC for 90 days. The effect of air addition at different levels was tested post freezing and every 30 days throughout its shelf life of 90 days. The results showed less than one log reduction in the viable counts of L. acidophilus La-5 for both samples incorporated with 60% and 100% OR after freezing and the number of viable cells did not differ significantly (p>0.05) from day 1 to day 90. In phase two of this study, a 22 full factorial experimental design was used to evaluate whether the viscous nature of ice cream mix plays an important role in improving the survivability of L. acidophilus La-5 during simulated digestion against low pH and presence of mechanical shear and to determine whether initial inoculation level has any effect on the viability of L. acidophilus La-5 at the end of 2 hr simulated digestion. Non-fermented low fat (5%) ice cream mixes with high and low viscosity were produced by changing the amount of stabilizer/emulsifier blend and each of the two mixes were supplemented with two levels of L. acidophilus La-5 to obtain an initial population of 108cfu/g and 106cfu/g before freezing. These mixes were frozen with 60% overrun. The ice cream samples were digested for 2 hr in an in vitro model stomach called Human Gastric Simulator (HGS). This model included factors such as gastric secretions, mechanical shearing due to peristaltic contractions and temperature and pH control. No significant effect (p>0.05) of different levels of viscosity on the survivability of L. acidophilus La-5 was found during and at the end of 2 hr simulated in vitro digestion, irrespective of the difference in initial inoculation level. The initial supplementation level of L. acidophilus La-5 had a significant impact (p<0.05) on its survivability during the simulated digestion of ice cream samples, irrespective of the difference in viscosity. The log survival of L. acidophilus La-5 was on an average 3.64 log cfu/g and 4.08 log cfu/g for ice cream samples supplemented with higher and lower amount of L. acidophilus La-5, respectively at the end of 2 hr. Nevertheless, this difference in overall survival was not statistically significant (p>0.05). These studies demonstrated the efficacy of low fat non-fermented ice cream in maintaining high viable numbers of L. acidophilus La-5 throughout its tested shelf life of 90 days. In addition, protective effect of ice cream on the viability of L. acidophilus La-5 against harsh stomach conditions was observed, but this effect was not as a result of viscosity of ice cream. It was also found that an ice cream supplemented with 106cfu/g would result in a similar overall log reduction of L. acidophilus La-5 at the end of 2 hr simulated digestion compared to an ice cream supplemented with 108cfu/g. The aggressive stomach conditions had a negative impact on the survivability of L. acidophilus La-5 during digestion of all the ice cream samples, but this detrimental effect can be reduced by incorporating L. acidophilus La-5 into an ice cream matrix which would increase the opportunity of bacteria to reach the small intestine and provide the desired health benefit.
15

Probabilistic time estimation in tunnel projects

Mohammadi, Mohammad January 2021 (has links)
Transport infrastructure projects, including tunneling, suffer from timedelays and cost overrun. A literature review shows that the effect ofuncertainty has been neglected in explaining time and cost overrunmeaning that technical explanations matter. Probabilistic estimations oftime and cost can be employed for dealing with uncertainty in transportinfrastructure projects.In this licentiate thesis, KTH’s probabilistic time and cost estimationmodel for tunneling projects (Isaksson and Stille, 2005, Rock Mech. RockEng., 38, 373-398) was improved. The improvements include breakingdown the production activities into their sub-activities, which form thebasis for assessing times (or costs) for tunnel construction. In addition, theexceptional time and the length of model’s geotechnical zones aredescribed as stochastic variables instead of deterministic values used in theoriginal model. Given its hierarchical structure, the model can be used fortime and cost estimation of all types of tunnels and all constructionmethods in various geological condition.The improved version of the model uses three types of input parametersthat are probabilities of occurrences of different geological condition andidentified undesirable events, production effort of sub-activities (i.e. timespent for performing the sub-activity per unit length of tunnel) andadditive delay time that is imposed as a result of occurrence of undesirableevents. The important issues in modeling the uncertainty in the productionefforts of sub-activities are also explained. / Transportinfrastrukturprojekt, inklusive tunnelbyggnad, lider ofta avförseningar och ökade kostnader. En litteraturgenomgång visar atteffekten av osäkerhet inte har beaktats när man försöker förklara orsakentill förseningar och kostnadsökningar, vilket betyder att osäkerheten omgeotekniska förhållanden mycket väl kan spela en stor roll. För att hanteradenna osäkerhet när man bedömer tid och kostnad för tunnelprojekt kansannolikhetsbaserade metoder användas.I denna licentiatuppsats förbättrades den sannolikhetsbaserade modellför tid och kostnadsskattning i tunnelprojekt som tidigare utvecklats påKTH (Isaksson och Stille, 2005, Rock Mech. Rock Eng., 38, 373-398). Denviktigaste förbättringen var att dela upp produktionsaktiviteterna idelaktiviteter, för vilka man sedan enklare kan bedöma tidsåtgång (ellerkostnader). Dessutom beskrivs exceptionella förseningar och längden påmodellens geotekniska zoner nu med stokastiska variabler istället för meddeterministiska värden. Modellen är flexibel nog att kunna användas förtids- och kostnadsskattning av alla typer av tunnelprojekt ochkonstruktionsmetoder i olika geologiska miljöer.Den förbättrade versionen av modellen använder tre typer avindataparametrar: sannolikheter för förekomster av olika geologiskatillstånd och identifierade oönskade händelser; produktionsinsats fördelaktiviteter (d.v.s. den tid som används för att utföra delaktiviteten permeter tunnel); samt försening som orsakas av oönskade händelser.Uppsatsen diskuterar även de viktigaste aspekterna vid modellering avosäkerheten i produktionsinsatsen för delaktiviteter. / <p>QC 20211102</p>
16

Undersökning av kostnadsöverskridande i byggbranschen : Faktorer som påverkar att slutsumman blir högre än den estimerade kostnadskalkylen

Djurisic, Stefan, Glazowski, Pawel January 2020 (has links)
The purpose of this study is to identify main factors when cost estimate is being exceeded in the construction industry both nationally and globally. If the cost estimation is exceeded, it may result in losses for the company, which can be severe and cause extensive damage. Therefore, a study is necessary to see if it is possible to perform a more detailed cost calculation.Cost overruns occur in both bigger and smaller projects. Factors causing cost overruns do not always have to be of the same category. Identifying negative factors as a guideline is troublesome due to the fact that one project outcome might not necessarily be other projects result.In collaboration with Småa AB and our starting point in “The white city”, an examination was performed to identify the factors leading to the costs being exceeded. Study consisting of literature and interviews with the production manager for the White City. At the end of the study the purpose and questions will be answered. Suggestions and solutions will be provided.The work was ongoing during a prevailing pandemic, that has affected the entire world, Covid-19. The pandemic has limited our site visits and interviews. Most of the work has been done digitally.
17

Proaktiv ändringshantering i uppstart av byggprojekt : En fallstudie om hur projektledare kan förebygga kostnader för tillägg i mindre byggprojekt

Kriebel, Matilda, Wolgsjö, Emma January 2019 (has links)
A project can be defined as a temporary work that is within the scope of time and budget in terms of achieving a project goal. Due to the fact that construction projects are unique and usually very complex, project management therefore requires a working method that is adapted to the prerequisites of the project. The project manager's responsibility to follow up on the budget and ensure that resources such as working hours and consulting services are distributed correctly, is becoming increasingly challenging as the change paradox shows that flexibility decreases and costs for changes increase as the project progresses. Exceeding the project budget in construction projects has today become a global phenomenon and involves several negative social effects. Scientific studies show that the increased costs can be derived from deviations such as additions and changes during the construction project. On the other hand, there are perceived gaps in the literature for which factors affect the extent of these and thus became the study's area of ​​investigation. Based on the scientific gap, the study aims to analyze the startup process in smaller construction projects with regard to identifying the factors that have an impact on additions, but also to review how project managers can proactively manage these factors in order to reduce the risk of increased deviations. To answer the research questions and purpose, a qualitative case study has been applied to a global consulting company in the construction industry, where semi-structured interviews were conducted with five project managers at the company.   The result of the study shows that project managers do not take preventive measures or work to prevent deviations in the startup process. Based on a thematic analysis of the results, factors with an impact on deviations have been identified in three areas; systematics, communication and experience and competence. The study has shown that increased costs for additions and changes can be deduced from different approaches to project management and misleading information, inadequate requirement specification that leaves room for own interpretation, unspecified communication channels, conflicts, lack of competence and abrupt completions of the project. In order to achieve a more proactive startup process in order to prevent increased costs for additions and changes, project managers should ensure a clear requirement specification by discussing important issues and decisions, requirements and expectations with support from templates and checklists. To avoid misunderstandings and conflicts, a communication plan can be established. Finally, the choice of project model should be established and routines for final reporting should be introduced to create a learning organisation that increases the project managers' self-insight and competence regarding increased costs for additions and project changes. The theoretical contribution of the study is the identified factors within three areas as well as suggestions for how project managers can facilitate the management of additions in the startup process of construction projects. / Ett projekt kan definieras som ett tillfälligt arbete som förhåller sig inom ramarna för tid, budget och omfattning i avseende att uppnå ett projektmål. Med anledning av att byggprojekt är unika och vanligen mycket komplexa, är projektledare i behov av verktyg och arbetsmetoder som anpassas utifrån projektets förutsättningar. Projektledarens ansvar att följa upp budget och se till att resurser såsom arbetstid och konsulttjänster fördelas rätt, blir allt mer utmanande under projektets gång då ändringsparadoxen påvisar att flexibiliteten minskar och kostnader för ändringar ökar i takt med projektets fortgång. Överskridande av projektbudget inom byggprojekt har idag kommit att bli ett globalt fenomen och innebär flera negativa samhällseffekter. Vetenskapliga studier visar att de ökade kostnaderna kan härledas till tillägg och ändringar under byggprojektet. Däremot upplevs det finnas luckor i litteraturen för vilka faktorer som inverkar på omfattningen för dessa och detta blev således studiens undersökningsområde. Utifrån det vetenskapliga gapet syftar studien till att analysera uppstartsprocessen i mindre byggprojekt i avseende att identifiera de faktorer som har en inverkan på tillägg, men även till att se över hur projektledare kan hantera dessa faktorer för att minska risken för ökade kostnader vid tillägg. För att besvara rapportens frågeställningar och syfte har en kvalitativ fallstudie tillämpats hos ett globalt konsultbolag inom byggbranschen, där semistrukturerade intervjuer genomfördes med fem projektledare på företaget. Resultatet av studien visar att projektledare inte vidtar förebyggande åtgärder eller arbetar för att förhindra tillägg i uppstartsprocessen. Utifrån en tematisk analys av resultatet har faktorer med en påverkan på tillägg kunnat identifieras inom tre områden; systematik, kommunikation samt erfarenhet och kompetens. Studien har visat att ökade kostnader vid tillägg och ändringar går att härleda till olika tillvägagångssätt vid projektledning och vilseledande information, bristfällig kravspecifikation som lämnar utrymme för egen tolkning, ospecificerade kommunikationsvägar, konflikter, bristande kompetens hos projektledaren samt abrupta projektavslut. För att uppnå en mer proaktiv uppstartsprocess i syfte att förhindra ökade kostnader vid tillägg och ändringar bör projektledare säkerställa en tydlig kravspecifikation genom att diskutera viktiga frågor och beslut, krav och förväntningar med stöd från mallar och checklistor. För att undvika missförstånd och konflikter kan en kommunikationsplan upprättas. Avslutningsvis bör val av projektmodell fastställas och rutiner för slutrapportering införas för att skapa en lärande organisation som ökar projektledarnas självinsikt och kompetens vad gäller ökade kostnader för tillägg och ändringar. Studiens teoretiska bidrag är bidragsfaktorer som identifierats inom tre områden samt förslag till hur projektledare kan underlätta hantering av tillägg i uppstartsprocessen av byggprojekt.
18

Development of a Framework for Preliminary Risk Analysis in Transportation Projects

Guo, Wei 25 December 2004 (has links)
"Over the years, risk analysis methodologies have been developed and implemented by many industries. NASA has implemented a cost efficient Continuous Risk Analysis methodology with good results. The U. S. Department of Transportation also states that a continuous risk analysis is the key in identifying, addressing, and handling risks before they become threats to success. However, current practices seldom incorporate this concept into real transportation projects. In general, risk is simply disregarded in feasibility studies. One of primary reasons is the lack of a feasible and effective risk analysis approach to guide efficient implementation in real projects. This thesis reviews current risk analysis practices used in public transportation projects. Using a case study, it also explores potential obstacles encountered in the implementation of systematic risk analysis. Finally, this thesis presents a preliminary risk analysis framework developed through the case study and enriched subsequently by incorporating material documented in the literature. The proposed risk analysis approach is to help achieve continuous risk analysis in transportation projects by enabling early start, frequent implementation, extensive application and flexible adoption."
19

Estimation Of Cost Overrun Risk In Interrnational Project By Using Fuzzy Set Theory.

Han, Sedat 01 May 2005 (has links) (PDF)
In the global construction market, most construction companies are willing to undertake international projects in order to maximise their profitability by taking advantage of attractive emerging markets and minimise dependence on unfavorable domestic market conditions. In order to be awarded a contract in highly competitive global construction market, companies should excel in choosing the most attractive markets and prepare winning bids for the selected construction projects in those markets. While preparing bids, the major concern of companies is to offer an optimum price that will enable them to earn enough profits and win the contract at the same time, where profit making ability is strongly correlated with proper estimation of a risk premium that is added onto the estimated cost of the project. Due to the nature of construction works, there are lots of uncertainties associated with the project, market and country conditions. Therefore, how the profitability of the project changes with occurrence of various risk events, in other words, the sensitivity of project costs to risk events, should be estimated by bidders realistically. In this study, fuzzy set theory is used to estimate cost overrun risk in international projects at the bidding stage. The objective is to propose a methodology which can be used by bidders to quantify cost overrun risk so that a realistic risk premium may be determined. A fuzzy risk rating approach is proposed to quantify cost overrun risk rating, which takes into account of risks characterised in international construction projects. For this purpose, risk sources have been identified and a risk model is put forward by using influence diagramming method. Based on this risk model, a fuzzy risk rating algorithm has been defined and software has been developed to conduct fuzzy risk rating calculations easily. After a decision-maker inserts the necessary inputs related with project and country risk factors, the output of the software is a rating that takes into account of all factors that may affect cost overrun risk in international construction projects. The reliability of the algorithm and developed software have been tested by an application on a real construction project. The proposed methodology and decision support tool have been proved to be reliable for the estimation of cost overrun risk while giving bidding decisions in international markets.
20

Analysis of Construction Cost Variation of Construction Manager General Contractor (CM/GC) Project

Mitra, John Paul, Shrestha, Joseph, Ross, Jeremy, Hong, Jinseok 10 April 2019 (has links)
Cost overrun is prevalent in the construction industry. Usually, an owner sets a budget at the preliminary phase of a project which changes over time. Past studies are focused on analyzing the cost growth of design-bid-build projects during construction. Limited efforts have been made to analyze details of projects delivered with the Construction Manager General Contractor (CM/GC) method. This study tracks and analyzes the construction cost variation of a project from the conceptual phase to the design completion phase. The analysis is presented with a case study of a new stadium construction project. It identifies that the changes in the scope and design of the project due to the change in available budget were a major reason for variation in the cost estimates over time. Further, this study identifies a) trades with the highest variation in subcontractors’ bids, b) trades that were most overestimated, and c) trades that were most underestimated. The findings of this study is expected to aid owners, designers, and contractors of future projects in improving the preparation, planning, and estimating of future projects; reducing cost variation within trades; and optimizing the amount of contingency required to ensure the successful completion of similar projects.

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