Aeroservoelastic design definition of a 20 MW common research wind turbine model

Wind turbine upscaling is motivated by the fact that larger machines can achieve lower levelized cost of energy. However, there are several fundamental issues with the design of such turbines, and there is little public data available for large wind turbine studies. To address this need, we develop a 20 MW common research wind turbine design that is available to the public. Multidisciplinary design optimization is used to define the aeroservoelastic design of the rotor and tower subject to the following constraints: blade‐tower clearance, structural stresses, modal frequencies, tip‐speed and fatigue damage at several sections of the tower and blade. For the blade, the design variables include blade length, twist and chord distribution, structural thicknesses distribution and rotor speed at the rated. The tower design variables are the height, and the diameter distribution in the vertical direction. For the other components, mass models are employed to capture their dynamic interactions. The associated cost of these components is obtained by using cost models. The design objective is to minimize the levelized cost of energy. The results of this research show the feasibility of a 20 MW wind turbine and provide a model with the corresponding data for wind energy researchers to use in the investigation of different aspects of wind turbine design and upscaling. Copyright © 2016 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134256/1/we1970.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134256/2/we1970_am.pd

Witnessing and re-enacting in Cambodia: reflection on shifting testimonies

Thirty years after the collapse of the Khmer Rouge regime (1975-1979) how do Cambodians cope with the traumatic legacy of Pol Pot's reign of terror? What forms does witnessing take on in post-socialist and transitional Cambodia as senior Khmer Rouge leaders await prosecution at the Cambodian Tribunal? The paper examines aspects of witnessing in today's Cambodia, expressing each in its own way the idea of the 'shifting' of witnessing: the transformation of testimonies due to time passing and contrasted systems of justice through a comparison of testimonies in the trial of the 'Pol Pot/Ieng Sary clique' (1979) and the current Cambodian Tribunal; the complex forms of witnessing emerging from participatory projects developed with Western authors in 'We want (u) to know' (documentary movie made by an international film crew with the inhabitants of the village of Thnol Lok in 2009) and 'Breaking the silence' (theatre play realised by the Dutch dramaturge Annemarie Prins that premiered in Phnom Penh in 2009 and toured Cambodia in the following years); the relationship between documentary and legal forms of witnessing through the example of Vann Nath, a survivor of S-21/Tuol Sleng, the prison where the Khmer Rouge tortured and killed thousands of their fellow countrymen. The paper analyses the difficulty Western organisers of participatory projects experienced in applying the hybrid model of transitional justice to sociocultural contexts of witnessing. Nevertheless it points out their contribution to processes of 'recognition beyond recognition' in which cultural differences in coming to terms with historical trauma are expressed and recorded

Outcomes of chronic total occlusion percutaneous coronary intervention from the RAIAN (RAjaie - Iran) registry

Objective: While most of the evidence in CTO interventions emerge from Western and Japanese studies, few data have been published up today from the Middle East. Objective of this study was to evaluate technical success rates and clinical outcomes of an Iranian population undergoing CTO PCI in a tertiary referral hospital. Moreover, we sought to evaluate the efficacy of our CTO teaching program. Methods: This is a retrospective single-center cohort study including 790 patients who underwent CTO PCI performed by operators with different volumes of CTOs PCI performed per year. According to PCI result, all patients have been divided into successful (n = 555, 70.3 %) and unsuccessful (n = 235, 29.7 %) groups. Study endpoints were Major Adverse Cardiovascular Events and Health Status Improvement evaluated using the Seattle Angina Questionnaire at one year. Results: A global success rate of 70 % for antegrade and 80 % for retrograde approach was shown despite the lack of some CTO-dedicated devices. During the enrollment period, the success rate increased significantly among operators with a lower number of CTO procedures per year. One-year MACE rate was similar in both successful and unsuccessful groups (13.5 % in successful and 10.6 % in unsuccessful group, p = 0.173). One year patients' health status improved significantly only in successful group. Conclusions: No significant differences of in-hospital and one-year MACE were found between the successful and unsuccessful groups. Angina symptoms and quality of life significantly improved after successful CTO PCI. The RAIAN registry confirmed the importance of operator expertise for CTO PCI success

Attitudes and perceptions regarding entrepreneurship around the world : a cluster analysis approach

Nowadays it is believed that entrepreneurship could be a driving force in growth and development. For the achievement of a relevant national entrepreneurship rate the social and economic business environment can be crucial. However, despite the international attention given to entrepreneurship, it is not known if it is a global phenomenon or if there are particular regions where the entrepreneurial activity is specially recognized by society. Applying cluster analysis statistical techniques to a dataset gathered by the Global Entrepreneurship Monitor (GEM) and that includes, in 2010, 59 countries this paper intends to identify groups of countries with the same population attitude and perception regarding entrepreneurship

Attitudes and perceptions regarding entrepreneurship around the world : a cluster analysis approach

Nowadays it is believed that entrepreneurship could be a driving force in growth and develop-ment. For the achievement of a relevant national entrepreneurship rate the social and economic business environment can be crucial. However, despite the international attention given to entrepreneurship, it is not known if it is a global phenomenon or if there are particular regions where the entrepreneurial activity is specially recognized by society. Applying cluster analysis statistical techniques to a dataset gathered by the Global Entrepreneurship Monitor (GEM) and that includes, in 2010, 59 countries this paper intends to identify groups of countries with the same population attitude and perception regarding entrepreneurship

Forecasting Ratio of Low Bid to Owner\u27s Estimate for Highway Construction

Several state departments of transportation (state DOTs) have encountered significant challenges to accurately estimate costs of their highway projects. It is not uncommon that states\u27 DOT estimates (owner\u27s estimates) are significantly different from contractors\u27 submitted bids. This is a critical problem for state highway agencies that strive to develop more accurate cost estimates, deliver projects within the budget, and optimize constrained funds for their highway programs. This inaccuracy problem is a temporal issue since the engineer\u27s estimate is developed ahead of time before the project is advertised and bids are received. The question that transportation agencies are interested in finding an answer to is: are there any significant risk factors in the construction market indicating to the increased likelihood of the deviation between owner\u27s estimate and the submitted low bid? In this research, a temporal perspective is selected to answer this question through identifying risk factors affecting the accuracy of the owner\u27s estimate. The ratio of low bid to owner\u27s estimate is examined using time-series analysis. The objectives of this research are to (1) examine several variables representing local highway construction market, overall construction market, macroeconomic conditions, and energy market, to identify the leading indicators of ratio of low bid to owner\u27s estimate; and (2) use the identified leading indicators to develop an appropriate time-series model to forecast the ratio of low bid to owner\u27s estimate. Four variables are identified as the major leading indicators: (1) number of projects awarded in the same month at the state level; (2) average number of bidders last month; (3) producer price index for steel mill products (PPISM); and (4) construction cost index (CCI). Several seasonal autoregressive integrated moving average with explanatory variable (ARIMAX) models are developed that are capable of forecasting the ratio of low bid to owner\u27s estimate with a high accuracy. This research contributes to the state of knowledge of analyzing the difference between owner\u27s estimate and low bid through: (1) identification of leading indicators of ratio of low bid to owner\u27s estimate that convey the extent of risk and uncertainty associated with construction projects at the cost estimation phase; and (2) development of appropriate multivariate time-series models (i.e., ARIMAX models) to predict the ratio of low bid to owner\u27s estimate. It is anticipated that the results will help cost estimating professionals in transportation agencies better understand the variability between their estimates and submitted bids by highway contractors, and thus, prepare more accurate cost estimates and develop appropriate risk management strategies for enhanced decision-making

Decision Analytics in Design and Construction

Presented on September 26, 2019 from 11:00 a.m.-12:00 p.m. in the Caddell Building, Flex Space, Georgia Tech.Forum panelists are: •Baabak Ashuri -- Associate Professor in the School of Building Construction and the School of Civil and Environmental Engineering •Leila Aflatoony -- Assistant Professor in the School of Industrial Design •Chris Bartlett -- Research Scientist in the School of Industrial Design, School of Mechanical Engineering, and the Georgia Tech Research Institute •Tarek Rakha -- Assistant Professor in the School of Architecture and faculty at the High Performance Building Lab. All panelist are associated with the Georgia Institute of Technology.Runtime: 52:07 minutesDecision analytics stands to have a profound impact on how design and construction disciplines are woven together to solve today's most complex problems. Rigorous data collection and analysis are core to design and construction decision making. The nature of analysis is to study complexity and deduce a reasonable summary that will then inform design and construction decisions. Decision analytics is distinguished from analysis by the emphasis on causality and prediction. The proliferation of computing power and access to rich data sets has driven innovation in the analytics tools market, lowering the barrier for entry to powerful analytics tools for designers and constructors. This means that decision-makers can more accurately identify causality and leverage the predictive power of analytics to inform design and construction decisions that anticipate and solve for problems much further into the future. Opportunities are growing to align decision analytics across multiple disciplines to minimize economic waste, maximize energy efficiencies, and enhance the lives of individuals and communities. An intuitive example of this opportunity lies in new building design and construction. Construction Analytics is a distinctive discipline, bridging the fields of building construction, civil and environmental engineering, economics, and operations research. Designers and decision-makers use descriptive analytics to identify indicators to cost overruns, diagnostic analytics to predict construction market resiliency after natural disasters, predictive analytics to identify future building trends, and prescriptive analytics to optimize resource allocation during construction projects. Building performance analytics explores various performance measures linked to building energy investigations, including measuring existing building performance through detailed audits to achieve substantial energy savings in deteriorating infrastructures, as well as simulating and visualizing new building and urban energy-flows to formulate informed design decisions empowered by data analytics for a sustainable and energy efficient future. In the example of new hospital construction, human-centered analytics can produce powerful insights and unlock empathy for the people (pediatric doctors, nurses, patients) who actively use the hospital space. Merging and visualizing several sources of quantitative and qualitative data draws out causality and enables predictive decision making aimed at improving the experience and performance of the people using the space

State of practice in portfolio management : a comprehensive survey

There has been an increase in the practice of managing multiple projects as the number of megaprojects has decreased and firms try to manage a larger number of smaller projects. The use of portfolio management is growing in the industry to allow firms to maximize the use of their limited resources. This paper reports on the outcome of a comprehensive survey, which was supported by the Construction Industry Institute (CII) and a team of 17 experts from various firms. The survey focused on identifying contemporary portfolio management practices by asking 28 questions on five topics: firm information, makeup of a portfolio, current practices, performance metrics, and implementation. The survey was designed to give an insight into what successful owners and contractors have done in implementing portfolio management. It was found that owners approach portfolio management differently from contractors. Owners generally establish strategic business objectives and select projects and form their portfolios using their available resources. On the other hand, contractors try to win projects and follow their clients’ regulations; however, they still need portfolio management to efficiently manage their projects. A major emphasis of this research effort was the list of performance metrics used in portfolio management. Owners who successfully implemented portfolio management within their firms have practiced the use of a formal project prioritization system in a portfolio. All of these firms use dashboards with performance metrics to show the performance of a portfolio. The Main indicators found on current dashboards include cost, schedule, safety, and overall success of the portfolio.Non UBCUnreviewedFacult

Multidisciplinary design optimization of large wind turbines: Technical, economic, and design challenges

Wind energy has experienced a continuous cost reduction in the last decades. A popular cost reduction technique is to increase the rated power of the wind turbine by making it larger. However, it is not clear whether further upscaling of the existing wind turbines beyond the 5–7MW range is technically feasible and economically attractive. To address this question, this study uses 5, 10, and 20MW wind turbines that are developed using multidisciplinary design optimization as upscaling data points. These wind turbines are upwind, 3-bladed, pitch-regulated, variable-speed machines with a tubular tower. Based on the design data and properties of these wind turbines, scaling trends such as loading, mass, and cost are developed. These trends are used to study the technical and economical aspects of upscaling and its impact on the design and cost. The results of this research show the technical feasibility of the existing wind turbines up to 20 MW, but the design of such an upscaled machine is cost prohibitive. Mass increase of the rotor is identified as a main design challenge to overcome. The results of this research support the development of alternative lightweight materials and design concepts such as a two-bladed downwind design for upscaling to remain a cost effective solution for future wind turbines.Wind Energ