Empirical Evaluation of the Impact of Wind Turbines on DVB-T Reception Quality

2012 ◽  
Vol 58 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Itziar Angulo ◽  
David de la Vega ◽  
Olatz Grande ◽  
Nicoletta Cau ◽  
Unai Gil ◽  
...  
2021 ◽  
Vol 11 (2) ◽  
pp. 796
Author(s):  
Alhanoof Althnian ◽  
Duaa AlSaeed ◽  
Heyam Al-Baity ◽  
Amani Samha ◽  
Alanoud Bin Dris ◽  
...  

Dataset size is considered a major concern in the medical domain, where lack of data is a common occurrence. This study aims to investigate the impact of dataset size on the overall performance of supervised classification models. We examined the performance of six widely-used models in the medical field, including support vector machine (SVM), neural networks (NN), C4.5 decision tree (DT), random forest (RF), adaboost (AB), and naïve Bayes (NB) on eighteen small medical UCI datasets. We further implemented three dataset size reduction scenarios on two large datasets and analyze the performance of the models when trained on each resulting dataset with respect to accuracy, precision, recall, f-score, specificity, and area under the ROC curve (AUC). Our results indicated that the overall performance of classifiers depend on how much a dataset represents the original distribution rather than its size. Moreover, we found that the most robust model for limited medical data is AB and NB, followed by SVM, and then RF and NN, while the least robust model is DT. Furthermore, an interesting observation is that a robust machine learning model to limited dataset does not necessary imply that it provides the best performance compared to other models.


2017 ◽  
Vol 46 (2) ◽  
pp. 224-241 ◽  
Author(s):  
Jacob R. Fooks ◽  
Kent D. Messer ◽  
Joshua M. Duke ◽  
Janet B. Johnson ◽  
Tongzhe Li ◽  
...  

This study uses an experiment where ferry passengers are sold hotel room “views” to evaluate the impact of wind turbines views on tourists’ vacation experience. Participants purchase a chance for a weekend hotel stay. Information about the hotel rooms was limited to the quality of the hotel and its distance from a large wind turbine, as well as whether or not a particular room would have a view of the turbine. While there was generally a negative effect of turbine views, this did not hold across all participants, and did not seem to be effected by distance or hotel quality.


2017 ◽  
Vol 2 (2) ◽  
pp. 403-413
Author(s):  
Francesco Grasso ◽  
Domenico Coiro ◽  
Nadia Bizzarrini ◽  
Giuseppe Calise

Abstract. Nowadays, all the modern megawatt-class wind turbines make use of pitch control to optimise the rotor performance and control the turbine. However, for kilowatt-range machines, stall-regulated solutions are still attractive and largely used for their simplicity and robustness. In the design phase, the aerodynamics plays a crucial role, especially concerning the selection/design of the necessary airfoils. This is because the airfoil performance is supposed to guarantee high wind turbine performance but also the necessary machine control capabilities. In the present work, the design of a new airfoil dedicated to stall machines is discussed. The design strategy makes use of a numerical optimisation scheme, where a gradient-based algorithm is coupled with the RFOIL code and an original Bezier-curves-based parameterisation to describe the airfoil shape. The performances of the new airfoil are compared in free- and fixed-transition conditions. In addition, the performance of the rotor is analysed, comparing the impact of the new geometry with alternative candidates. The results show that the new airfoil offers better performance and control than existing candidates do.


Author(s):  
Sandhya Saisubramanian ◽  
Ece Kamar ◽  
Shlomo Zilberstein

Agents operating in unstructured environments often create negative side effects (NSE) that may not be easy to identify at design time. We examine how various forms of human feedback or autonomous exploration can be used to learn a penalty function associated with NSE during system deployment. We formulate the problem of mitigating the impact of NSE as a multi-objective Markov decision process with lexicographic reward preferences and slack. The slack denotes the maximum deviation from an optimal policy with respect to the agent's primary objective allowed in order to mitigate NSE as a secondary objective. Empirical evaluation of our approach shows that the proposed framework can successfully mitigate NSE and that different feedback mechanisms introduce different biases, which influence the identification of NSE.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mahdi Ghaemi Asl ◽  
Muhammad Mahdi Rashidi ◽  
Alireza Ghorbani

Purpose This paper aims to investigate the impact of market structure and market share on the performance of the Islamic banks operating in the Iranian banking system based on the structure-conduct-performance (SCP) paradigm. Design/methodology/approach The Iranian Islamic banking system’s market structure is evaluated by using the econometrics method to test the validity of the traditional SCP paradigm. For this purpose, the authors estimate a simple regression model that is consisted of several independent variables, such as the market share, bank size, real gross domestic product, liquidity and Herfindahl-Hirschman index as a proxy variable for concentration and one dependent variable, namely, the profit as a proxy for performance. The panel data includes a data sample of 22 Islamic banks operating from 2006 to 2019. Data are extracted from the balance sheet of Islamic banks and the time-series database of the Central Bank of Iran and World Bank. Findings The study’s findings indicate that both concentration and market share have a positive impact on the performance of banks in the Iranian Islamic banking system. This result is contradicted with both traditional SCP and efficient structure hypotheses; however, it confirms the existence of oligopoly or cartel in the Iranian Islamic banking system that few banks try to gain the highest share of profit and maintain their market share by colluding with each other. This result is in contradiction with other research studies about the market structure in the Iranian banking system that claimed that banks in Iran operate under monopolistic competition. In addition, it shows that the privatization of some banks in Iran does not improve and help competition in the Iranian banking system. Originality/value This paper is a pioneer empirical study analyzing the market structure, concentration and collusion based on the SCP paradigm in Iranian Islamic banking. The results of the study support the existence of collusive behavior among the Islamic bank in Iran that is not aligned with Sharia. This study clearly shows the difference between ideal Islamic banking and Islamic banking in practice in Islamic countries. This clearly indicates that only prohibiting some operations like receiving interest, gambling and bearing excessive risk is not enough. In fact, the Islamic banking system should be based on the Sharia rule in all aspects and much more modification and study have to be done to achieve an appropriate Islamic banking system. These possible modifications to overcome the issues of cartel-like market structure and collusive behavior in the Iranian Islamic banking system include making the Iranian banking system more transparent, letting foreign banks enter the Iranian banking system and minimizing the government intervention in the Iranian banking system.


2021 ◽  
Author(s):  
Marcus Klose ◽  
Junkan Wang ◽  
Albert Ku

Abstract In the past, most of the offshore wind farms have been installed in European countries. In contrast to offshore wind projects in European waters, it became clear that the impact from earthquakes is expected to be one of the major design drivers for the wind turbines and their support structures in other areas of the world. This topic is of high importance in offshore markets in the Asian Pacific region like China, Taiwan, Japan, Korea as well as parts of the United States. So far, seismic design for wind turbines is not described in large details in existing wind energy standards while local as well as international offshore oil & gas standards do not consider the specifics of modern wind turbines. In 2019, DNV GL started a Joint Industry Project (JIP) called “ACE -Alleviating Cyclone and Earthquake challenges for wind farms”. Based on the project results, a Recommended Practice (RP) for seismic design of wind turbines and their support structures will be developed. It will supplement existing standards like DNVGL-ST-0126, DNVGL-ST-0437 and the IEC 61400 series. This paper addresses the area of seismic load calculation and the details of combining earthquake impact with other environmental loads. Different options of analysis, particularly time-domain simulations with integrated models or submodelling techniques using superelements will be presented. Seismic ground motions using a uniform profile or depth-varying input profile are discussed. Finally, the seismic load design return period is addressed.


Trials ◽  
2015 ◽  
Vol 16 (S2) ◽  
Author(s):  
Royes Joseph ◽  
Julius Sim ◽  
Reuben Ogollah ◽  
Martyn Lewis

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