Big Is Fragile: an Attempt at Theorizing Scale
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Urban Megaprojects-Based Approach in Urban Planning: from Isolated Objects to Shaping the City the Case of Dubai
Université de Liège Faculty of Applied Sciences Urban Megaprojects-based Approach in Urban Planning: From Isolated Objects to Shaping the City The Case of Dubai PHD Thesis Dissertation Presented by Oula AOUN Submission Date: March 2016 Thesis Director: Jacques TELLER, Professor, Université de Liège Jury: Mario COOLS, Professor, Université de Liège Bernard DECLEVE, Professor, Université Catholique de Louvain Robert SALIBA, Professor, American University of Beirut Eric VERDEIL, Researcher, Université Paris-Est CNRS Kevin WARD, Professor, University of Manchester ii To Henry iii iv ACKNOWLEDGMENTS My acknowledgments go first to Professor Jacques Teller, for his support and guidance. I was very lucky during these years to have you as a thesis director. Your assistance was very enlightening and is greatly appreciated. Thank you for your daily comments and help, and most of all thank you for your friendship, and your support to my little family. I would like also to thank the members of my thesis committee, Dr Eric Verdeil and Professor Bernard Declève, for guiding me during these last four years. Thank you for taking so much interest in my research work, for your encouragement and valuable comments, and thank you as well for all the travel you undertook for those committee meetings. This research owes a lot to Université de Liège, and the Non-Fria grant that I was very lucky to have. Without this funding, this research work, and my trips to UAE, would not have been possible. My acknowledgments go also to Université de Liège for funding several travels giving me the chance to participate in many international seminars and conferences. -
Sensitivity Analysis
Chapter 11. Sensitivity Analysis Joseph A.C. Delaney, Ph.D. University of Washington, Seattle, WA John D. Seeger, Pharm.D., Dr.P.H. Harvard Medical School and Brigham and Women’s Hospital, Boston, MA Abstract This chapter provides an overview of study design and analytic assumptions made in observational comparative effectiveness research (CER), discusses assumptions that can be varied in a sensitivity analysis, and describes ways to implement a sensitivity analysis. All statistical models (and study results) are based on assumptions, and the validity of the inferences that can be drawn will often depend on the extent to which these assumptions are met. The recognized assumptions on which a study or model rests can be modified in order to assess the sensitivity, or consistency in terms of direction and magnitude, of an observed result to particular assumptions. In observational research, including much of comparative effectiveness research, the assumption that there are no unmeasured confounders is routinely made, and violation of this assumption may have the potential to invalidate an observed result. The analyst can also verify that study results are not particularly affected by reasonable variations in the definitions of the outcome/exposure. Even studies that are not sensitive to unmeasured confounding (such as randomized trials) may be sensitive to the proper specification of the statistical model. Analyses are available that 145 can be used to estimate a study result in the presence of an hypothesized unmeasured confounder, which then can be compared to the original analysis to provide quantitative assessment of the robustness (i.e., “how much does the estimate change if we posit the existence of a confounder?”) of the original analysis to violations of the assumption of no unmeasured confounders. -
Design of Experiments for Sensitivity Analysis of a Hydrogen Supply Chain Design Model
OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible This is an author’s version published in: http://oatao.univ-toulouse.fr/27431 Official URL: https://doi.org/10.1007/s41660-017-0025-y To cite this version: Ochoa Robles, Jesus and De León Almaraz, Sofia and Azzaro-Pantel, Catherine Design of Experiments for Sensitivity Analysis of a Hydrogen Supply Chain Design Model. (2018) Process Integration and Optimization for Sustainability, 2 (2). 95-116. ISSN 2509-4238 Any correspondence concerning this service should be sent to the repository administrator: [email protected] https://doi.org/10.1007/s41660-017-0025-y Design of Experiments for Sensitivity Analysis of a Hydrogen Supply Chain Design Model 1 1 1 J. Ochoa Robles • S. De-Le6n Almaraz • C. Azzaro-Pantel 8 Abstract Hydrogen is one of the most promising energy carriersin theq uest fora more sustainableenergy mix. In this paper, a model ofthe hydrogen supply chain (HSC) based on energy sources, production, storage, transportation, and market has been developed through a MILP formulation (Mixed Integer LinearP rograrnming). Previous studies have shown that the start-up of the HSC deployment may be strongly penaliz.ed froman economicpoint of view. The objective of this work is to perform a sensitivity analysis to identifythe major parameters (factors) and their interactionaff ectinga n economic criterion, i.e., the total daily cost (fDC) (response), encompassing capital and operational expenditures. An adapted methodology for this SA is the design of experiments through the Factorial Design and Response Surface methods. -
1 Global Sensitivity and Uncertainty Analysis Of
GLOBAL SENSITIVITY AND UNCERTAINTY ANALYSIS OF SPATIALLY DISTRIBUTED WATERSHED MODELS By ZUZANNA B. ZAJAC A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2010 1 © 2010 Zuzanna Zajac 2 To Król Korzu KKMS! 3 ACKNOWLEDGMENTS I would like to thank my advisor Rafael Muñoz-Carpena for his constant support and encouragement over the past five years. I could not have achieved this goal without his patience, guidance, and persistent motivation. For providing innumerable helpful comments and helping to guide this research, I also thank my graduate committee co-chair Wendy Graham and all the members of the graduate committee: Michael Binford, Greg Kiker, Jayantha Obeysekera, and Karl Vanderlinden. I would also like to thank Naiming Wang from the South Florida Water Management District (SFWMD) for his help understanding the Regional Simulation Model (RSM), the great University of Florida (UF) High Performance Computing (HPC) Center team for help with installing RSM, South Florida Water Management District and University of Florida Water Resources Research Center (WRRC) for sponsoring this project. Special thanks to Lukasz Ziemba for his help writing scripts and for his great, invaluable support during this PhD journey. To all my friends in the Agricultural and Biological Engineering Department at UF: thank you for making this department the greatest work environment ever. Last, but not least, I would like to thank my father for his courage and the power of his mind, my mother for the power of her heart, and my brother for always being there for me. -
A Selection Bias Approach to Sensitivity Analysis for Causal Effects*
A Selection Bias Approach to Sensitivity Analysis for Causal Effects* Matthew Blackwell† April 17, 2013 Abstract e estimation of causal effects has a revered place in all elds of empirical political sci- ence, but a large volume of methodological and applied work ignores a fundamental fact: most people are skeptical of estimated causal effects. In particular, researchers are oen worried about the assumption of no omitted variables or no unmeasured confounders. is paper combines two approaches to sensitivity analysis to provide researchers with a tool to investigate how specic violations of no omitted variables alter their estimates. is approach can help researchers determine which narratives imply weaker results and which actually strengthen their claims. is gives researchers and critics a reasoned and quantitative approach to assessing the plausibility of causal effects. To demonstrate the ap- proach, I present applications to three causal inference estimation strategies: regression, matching, and weighting. *e methods used in this article are available as an open-source R package, causalsens, on the Com- prehensive R Archive Network (CRAN) and the author’s website. e replication archive for this article is available at the Political Analysis Dataverse as Blackwell (b). Many thanks to Steve Ansolabehere, Adam Glynn, Gary King, Jamie Robins, Maya Sen, and two anonymous reviewers for helpful comments and discussions. All remaining errors are my own. †Department of Political Science, University of Rochester. web: http://www.mattblackwell.org email: [email protected] Introduction Scientic progress marches to the drumbeat of criticism and skepticism. While the so- cial sciences marshal empirical evidence for interpretations and hypotheses about the world, an academic’s rst (healthy!) instinct is usually to counterattack with an alter- native account. -
Sensitivity Analysis Methods for Identifying Influential Parameters in a Problem with a Large Number of Random Variables
© 2002 WIT Press, Ashurst Lodge, Southampton, SO40 7AA, UK. All rights reserved. Web: www.witpress.com Email [email protected] Paper from: Risk Analysis III, CA Brebbia (Editor). ISBN 1-85312-915-1 Sensitivity analysis methods for identifying influential parameters in a problem with a large number of random variables S. Mohantyl& R, Code112 ‘Center for Nuclear Waste Regulato~ Analyses, SWH, Texas, USA 2U.S. Nuclear Regulatory Commission, Washington D. C., USA Abstract This paper compares the ranking of the ten most influential variables among a possible 330 variables for a model describing the performance of a repository for radioactive waste, using a variety of statistical and non-statistical sensitivity analysis methods. Results from the methods demonstrate substantial dissimilarities in the ranks of the most important variables. However, using a composite scoring system, several important variables appear to have been captured successfully. 1 Introduction Computer models increasingly are being used to simulate the behavior of complex systems, many of which are based on input variables with large uncertainties. Sensitivity analysis can be used to investigate the model response to these uncertain input variables. Such studies are particularly usefhl to identify the most influential variables affecting model output and to determine the variation in model output that can be explained by these variables. A sensitive variable is one that produces a relatively large change in model response for a unit change in its value. The goal of the sensitivity analyses presented in this paper is to find the variables to which model response shows the most sensitivity. There are a large variety of sensitivity analysis methods, each with its own strengths and weaknesses, and no method clearly stands out as the best. -
Concept Symposium 2018 Governing Megaprojects – Why, What and How
Concept Symposium 2018 Governing Megaprojects – Why, What and How Ingvild Melvær Hanssen Updates on Project Governance in Norway Chief Specialist Ministry of Finance In Norway the Cabinet decides on most major projects. As decision support reviews are produced at specific Norway gateways by independent private consultants holding framework contracts with the Ministry of Finance. There are two intervention points: • Quality Assurance 1 “QA 1” prior to the basic engineering phase. Review topic: The choice of concept. Prime ranking criterion: Net present value (benefits minus costs). Introduced in 2005. • Quality assurance 2 “QA 2” after completion of the basic engineering phase and before budgetary appropriation. Review topics: Cost, risk, schedule and basis for management. Introduced in 2000. The Concept Symposia on Project Governance The Norwegian Ministry of Finance and the Concept Research There is a relatively high threshold value (750 mill. NOK). A total of more than 350 reviews have been made and the Program hosts every second year a symposium on project first projects are now readily implemented and evaluated. This introduction will give some perspectives on the Governance. Project governance, in brief, is concerned about results achieved and how Norway work to improve project governance further, especially looking into how projects investments and their outcome and long-term effects. In view of develop in the early planning period, how costs have increased between QA 1 and QA 2 and recent measures taken the problem at hand, the aim is to ensure that the best to improve focus on cost-effectiveness in this phase of project development. conceptual solution is chosen, that resources are used efficiently and anticipated effects realized. -
Should Scenario Planning Abandon the Use of Narratives Describing
Preparing for the future: development of an ‘antifragile’ methodology that complements scenario planning by omitting causation. Abstract This paper demonstrates that the Intuitive Logics method of scenario planning emphasises the causal unfolding of future events and that this emphasis limits its ability to aid preparation for the future, for example by giving a misleading impression as to the usefulness of ‘weak signals’ or ‘early warnings’. We argue for the benefits of an alternative method that views uncertainty as originating from indeterminism. We develop and illustrate an ‘antifragile’ approach to preparing for the future and present it as a step-by-step, non-deterministic methodology that can be used as a replacement for, or as a complement to, the causally-focused approach of scenario planning. Keywords: scenario planning; Intuitive Logics; causality; indeterminism; fragility; uncertainty 1. Introduction Scenario planning exercises are increasingly common in the private sector and are increasingly underpinned by academic research [1, 2 p.461, 3, 4 p.335]. While this increased popularity has been accompanied by a proliferation of approaches [5], it is widely accepted that most organizations employing scenario planning use an approach based on what is known as ‘Intuitive Logics’ (IL) [1, 6 p.9, 7 p.162]. Here, management team members are facilitated in thinking of the causal unfolding of chains of events into the future. 1 However, questions have been raised about IL’s effectiveness in preparing an organization for the future. In particular, much has recently been written highlighting its limited ability to deal with uncertainty - particularly its ability to assist in preparing for ‘surprise’ events [8-10]. -
Uncertainty and Sensitivity Analysis for Long-Running Computer Codes: a Critical Review
UNCERTAINTY AND SENSITIVITY ANALYSIS FOR LONG-RUNNING COMPUTER CODES: A CRITICAL REVIEW By MASSACHUSE~s INSTrTUTE' Dustin R. Langewisch OF TECHNOLOGY B.S. Mechanical Engineering and B.S. Mathematics MAR 122010 University of Missouri-Columbia, 2007 L A [ LIBRARIES SUBMITTED TO THE DEPARTMENT OF NUCLEAR SCIENCE AND ENGINEERING IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF ARCHIVES MASTER OF SCIENCE IN NUCLEAR SCIENCE AND ENGINEERING AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY FEBRUARY 2010 The author hereby grants MIT permission to reproduce and distribute publicly paper and electronic copies of this thesis document in whole or in part in any medium now known or hereafter created. Copyright 0 Massachusetts Institute of Technology All rights reserved. Signature of Author: "-1epartment of Nuclear Science and Engineering January 28, 2010 Certified by: Dr. Gofge E p-p'stolakis, Thesis Supervisor KEPCO Professor of Nuclear Science and Engineering Professor of Engineering Systems Certified by: Don d Helton, Thesis Reader of ear Regulatory Research a. Regulatory Commission Accepted by: Dr. Jacquelyn C. Yanch Chair, Department Committee on Graduate Students UNCERTAINTY AND SENSITIVITY ANALYSIS FOR LONG-RUNNING COMPUTER CODES: A CRITICAL REVIEW Dustin R. Langewisch SUBMITTED TO THE DEPARTMENT OF NUCLEAR SCIENCE AND ENGINEERING IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN NUCLEAR SCIENCE AND ENGINEERING AT THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY FEBRUARY 2010 Abstract This thesis presents a critical review of existing methods for performing probabilistic uncertainty and sensitivity analysis for complex, computationally expensive simulation models. Uncertainty analysis (UA) methods reviewed include standard Monte Carlo simulation, Latin Hypercube sampling, importance sampling, line sampling, and subset simulation. -
Sensitivity Analysis
Where to find this talk: www.andreasaltelli.eu On sensitivity analysis and its take up Definitions Uncertainty analysis: Focuses on quantifying the uncertainty in model output Sensitivity analysis: The study of the relative importance of different input factors on the model output Dr. Qiongli Wu, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan, China European Commission, 2015 Office for the Management and Budget, 2006 Environmental Protection Agency, 2009 EPA, 2009, March. Guidance on the Development, Evaluation, and Application of Environmental Models. Technical Report EPA/100/K-09/003. Office of the Science Advisor, Council for Regulatory Environmental Modeling, http://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P1003E4R.PDF, Last accessed December 2015. EUROPEAN COMMISSION, Better regulation toolbox, appendix to the Better Regulation Guidelines, Strasbourg, 19.5.2015, SWD(2015) 111 final, COM(2015) 215 final, http://ec.europa.eu/smart- regulation/guidelines/docs/swd_br_guidelines_en.pdf. OMB, Proposed risk assessment bulletin, Technical report, The Office of Management and Budget’s – Office of Information and Regulatory Affairs (OIRA), January 2006, https://www.whitehouse.gov/sites/default/files/omb/assets/omb/inforeg/proposed_risk_assessment_bulleti n_010906.pdf, pp. 16–17, accessed December 2015. http://ec.europa. eu/smart- regulation/ Source: IA Toolbox, p. 391 An engineer’s vision of UA, SA Resolution levels model structures errors Simulation uncertainty analysis Model model data output sensitivity analysis -
MEGAPROJECTS: Changing the Conversation by Sabine Hoover
MEGAPROJECTS: Changing the Conversation By Sabine Hoover How owners and project stakeholders are changing the way they work together to deliver successful megaprojects. The widespread shortcomings and low success rate of megaprojects have been so pervasive that those involved have begun to question the very model. The recent exits of prominent engineering1 and construction (E&C) players in certain types of megaproject markets indicate the situation may be coming to a head.2 Yet, at the same time, megaprojects are constantly growing larger and increasing in number and complexity. Consider this: Between 2013 and 2018, the annual value of U.S. megaproject starts increased from 3% to approximately 33% of all U.S. construction project starts. Similarly, FMI predicts that over the next decade, annual construction put in place (CPiP) on megaprojects in the U.S. will increase nearly 600%, from about $50 billion to just over $350 billion (Exhibits 1 and 2). These are big numbers. So what does this mean for the future of the E&C industry? Will we continue tormenting ourselves with project delays, cost overruns, lawsuits and political debacles until the end of time? Or has the industry finally reached a point where we can say “no more.” The answers are unclear, but we are starting to see signs of a cultural shift in how owners, contractors and designers collaborate and interact with one another on megaprojects. Though success stories are anecdotal and limited, one of the key topics that keeps bubbling to the surface is trust. It is this basic emotional state, a central theme of all human relationships, that can make or break entire project teams and associated outcomes. -
A Receiver Operating Characteristic Framework for Non-Adherence
The AAPS Journal (2019) 21: 40 DOI: 10.1208/s12248-019-0299-9 Research Article A Receiver Operating Characteristic Framework for Non-adherence Detection Using Drug Concentration Thresholds—Application to Simulated Risperidone Data in Schizophrenic Patients Carlos Pérez-Ruixo,1,3 Bart Remmerie,1 Juan José Peréz-Ruixo,1 and An Vermeulen2 Received 19 September 2018; accepted 12 January 2019; published online 14 March 2019 Abstract. Non-adherence to antipsychotic medication is a primary factor in disease relapse in schizophrenic patients. We sought to evaluate if plasma concentrations of the antipsychotic risperidone can be used as a predictor of treatment adherence and to identify the optimal plasma concentration threshold to reliably distinguish between adherent and non-adherent patients. A population pharmacokinetic model was used to simulate plasma risperidone steady-state trough concentrations in 1000 virtual patients, where 60% of the patients were 100% adherent to their medication, while 40% of the patients were non- adherent to their medication. The probability of adherence was assessed by receiver operating characteristic (ROC) analysis on Ctrough. The area under the ROC curve (AUCROC) was used to identify the optimal Ctrough threshold. Single vs multiple Ctrough at steady state was also evaluated. After a single risperidone Ctrough measurement, the AUCROC (95% CI) was estimated to be 0.71 (0.69–0.72) and the optimal Ctrough threshold accounting for the lowest number of adherent and non-adherent misclassifications was estimated to be 11.9 ng/mL. After multiple Ctrough measurements, the AUCROC (95% CI) increased up to 0.85 (0.84–0.87) for three Ctrough measurements.