We introduce the Robustness of Hierarchically Organized Time Series (RHiOTS) framework, designed to assess the robustness of hierarchical time series forecasting models and algorithms on real-world datasets. Hierarchi...
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ISBN:
(纸本)9798400704901
We introduce the Robustness of Hierarchically Organized Time Series (RHiOTS) framework, designed to assess the robustness of hierarchical time series forecasting models and algorithms on real-world datasets. Hierarchical time series, where lower-level forecasts must sum to upper-level ones, are prevalent in various contexts, such as retail sales across countries. Current empirical evaluations of forecasting methods are often limited to a small set of benchmark datasets, offering a narrow view of algorithm behavior. RHiOTS addresses this gap by systematically altering existing datasets and modifying the characteristics of individual series and their interrelations. It uses a set of parameterizable transformations to simulate those changes in the data distribution. Additionally, RHiOTS incorporates an innovative visualization component, turning complex, multidimensional robustness evaluation results into intuitive, easily interpretable visuals. This approach allows an in-depth analysis of algorithm and model behavior under diverse conditions. We illustrate the use of RHiOTS by analyzing the predictive performance of several algorithms. Our findings show that traditional statistical methods are more robust than state-of-the-art deep learning algorithms, except when the transformation effect is highly disruptive. Furthermore, we found no significant differences in the robustness of the algorithms when applying specific reconciliation methods, such as MinT. RHiOTS provides researchers with a comprehensive tool for understanding the nuanced behavior of forecasting algorithms, offering a more reliable basis for selecting the most appropriate method for a given problem.
Wind power generation has had a profound impact on both the green power and traditional power sectors. As a result, wind power forecasting plays an immense role in effectively predicting and providing wind power gener...
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Wind power generation has had a profound impact on both the green power and traditional power sectors. As a result, wind power forecasting plays an immense role in effectively predicting and providing wind power generated for effective power dispatching for system operators. However, wind power forecasting is a challenging topic with accuracy issues between the predicted power and actual power generation at the point of common coupling. Furthermore, due to the variation of wind, effective dispatching through the utilisation of wind power production forecasting becomes a challenge. This issue is further compounded by the vast amount of data required to train and verify of these forecasting algorithms. This paper presents a fast acting post forecast weighing algorithm designed to evaluate the forecasted power output of a previously developed wind power forecasting package. The developed method is designed to gauge and improve the estimated output forecaster's approach in order to observe performance changes in the algorithm while using minimal data without changing the internal workings of the evaluated forecasting algorithm.
This research aimed to enhance the capacity of transmission lines by developing an algorithm to predict Dynamic Line Rating (DLR) to avert the curtailment of renewable energy sources. This will help meet electricity d...
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This research aimed to enhance the capacity of transmission lines by developing an algorithm to predict Dynamic Line Rating (DLR) to avert the curtailment of renewable energy sources. This will help meet electricity demand, prevent power outages, reduce costs, and protect equipment and personnel. The proposed algorithm was trained by analyzing the correlation between sequential hourly DLR calculations derived from historical weather data and line physical parameters. The proposed algorithm used k-means clustering and Monte Carlo simulation to predict hourly DLR, considering the temporal correlation of historical DLR values for each month. The model's accuracy was verified through statistical tests and was compared to other forecasting methods such as ensemble forecasting, quantile regression, and recurrent neural networks. It was found that the proposed model demon-strated performance that is comparable or superior to existing methods, as seen in forecast skill ranging from 91 to 98%, a Continuous Ranked Probability Score (CRPS) between 0.02 and 0.05, and probabilistic ratings that are 48-70% higher than traditional Static Line Rating (SLR).
Conventional short-term forecasting algorithms for power load consumption mainly use the DNN (Deep Neural Network) deep neural network model to generate variable forecasting curves, which is vulnerable to the impact o...
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In this work, the level of influence of the posts published by famous people on social networks on the formation of the cryptocurrency exchange rate is investigated. Celebrities who are familiar with the financial ind...
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In this work, the level of influence of the posts published by famous people on social networks on the formation of the cryptocurrency exchange rate is investigated. Celebrities who are familiar with the financial industry, especially with the cryptocurrency market, or are somehow connected to a certain cryptocurrency, such as Elon Musk with Dogecoin, are chosen as experts whose influence through social media posts on cryptocurrency rates is examined. This research is conducted based on statistical analysis. Real cryptocurrency exchange rate forecasts for the selected time period and predicted ones for the same period, obtained using three algorithms, are utilized as a dataset. This paper uses methods such as statistical hypotheses regarding the significance of Spearman's rank correlation coefficient and Pearson's correlation. It is confirmed that the posts by famous people on social networks significantly affect the exchange rates of cryptocurrencies.
Overbooking policy, which is part of revenue management, is applied in many sectors today where unused capacity cannot be stored. The purpose of this application, in which the company receives reservation over the cap...
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Overbooking policy, which is part of revenue management, is applied in many sectors today where unused capacity cannot be stored. The purpose of this application, in which the company receives reservation over the capacity in order to cover the spoilage cost it will encounter because of no-show customers, is to maximize the amount of earnings while reducing spoilage costs. In the classical approach, the show probability of each customer is assumed to be the same. In this study, unlike the classical approach, the show probability of each reservation is estimated on a personal basis. Personal probabilities needed for the suggested approach are obtained from historical booking information using forecasting algorithms. The fact that each customer has different show probability makes it difficult to calculate the total number of no-shows in the classical way. For this reason, Monte Carlo simulation is used to calculate the optimal booking limit when show probability of each customer is taken differently on a personal basis. As a result of the study, it is seen that with the proposed dynamic models, higher gains can be achieved compared to the classical approach.
To make sustainable large IoT deployments in smart cities, a promising approach is to develop a new generation of solar energy harvesting IoT devices based on the concept of energy neutrality. Key to this concept are ...
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ISBN:
(纸本)9781728129990
To make sustainable large IoT deployments in smart cities, a promising approach is to develop a new generation of solar energy harvesting IoT devices based on the concept of energy neutrality. Key to this concept are the models for the forecast of energy production, which provide input to the energy neutral schedulers governing the activities of the IoT devices. The development of such models however need to be validated against real-world conditions. To this purpose we propose a testbed aimed at the collection of real-world dataset about the energy parameters of energy harvesting IoT devices, and, on the base of such a dataset, we perform a comparative assessment of state of the art and novel energy production forecast models.
We study multiclass online learning, where a forecaster predicts a sequence of elements drawn from a finite set using the advice of n experts. Our main contributions are to analyze the scenario where the best expert m...
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We study multiclass online learning, where a forecaster predicts a sequence of elements drawn from a finite set using the advice of n experts. Our main contributions are to analyze the scenario where the best expert makes a bounded number b of mistakes and to show that, in the low-error regime where b = o(log n), the expected number of mistakes made by the optimal forecaster is at most log(4) n + o(log n). We also describe an adversary strategy showing that this bound is tight and that the worst case is attained for binary prediction.
To increase efficacy in traditional classroom courses as well as in Massive Open Online Courses (MOOCs), automated systems supporting the instructor are needed. One important problem is to automatically detect student...
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To increase efficacy in traditional classroom courses as well as in Massive Open Online Courses (MOOCs), automated systems supporting the instructor are needed. One important problem is to automatically detect students that are going to do poorly in a course early enough to be able to take remedial actions. Existing grade prediction systems focus on maximizing the accuracy of the prediction while overseeing the importance of issuing timely and personalized predictions. This paper proposes an algorithm that predicts the final grade of each student in a class. It issues a prediction for each student individually, when the expected accuracy of the prediction is sufficient. The algorithm learns online what is the optimal prediction and time to issue a prediction based on past history of students' performance in a course. We derive a confidence estimate for the prediction accuracy and demonstrate the performance of our algorithm on a dataset obtained based on the performance of approximately 700 UCLA undergraduate students who have taken an introductory digital signal processing over the past seven years. We demonstrate that for 85% of the students we can predict with 76% accuracy whether they are going do well or poorly in the class after the fourth course week. Using data obtained from a pilot course, our methodology suggests that it is effective to perform early in-class assessments such as quizzes, which result in timely performance prediction for each student, thereby enabling timely interventions by the instructor (at the student or class level) when necessary.
To increase efficacy in traditional classroom courses as well as in Massive Open Online Courses (MOOCs), automated systems supporting the instructor are needed. One important problem is to automatically detect student...
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ISBN:
(纸本)9781467395038
To increase efficacy in traditional classroom courses as well as in Massive Open Online Courses (MOOCs), automated systems supporting the instructor are needed. One important problem is to automatically detect students that are going to do poorly in a course early enough to be able to take remedial actions. This paper proposes an algorithm that predicts the final grade of each student in a class. It issues a prediction for each student individually, when the expected accuracy of the prediction is sufficient. The algorithm learns online what is the optimal prediction and time to issue a prediction based on past history of students' performance in a course. We derive demonstrate the performance of our algorithm on a dataset obtained based on the performance of approximately 700 undergraduate students who have taken an introductory digital signal processing over the past 7 years. Using data obtained from a pilot course, our methodology suggests that it is effective to perform early in-class assessments such as quizzes, which result in timely performance prediction for each student, thereby enabling timely interventions by the instructor (at the student or class level) when necessary.
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