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We outline and test a new methodology for genuine simulation of stochastic processes with any dependence and any marginal distribution. We reproduce time dependence with a generalized, time symmetric or asymmetric, moving-average scheme. This implements linear filtering of non-Gaussian white noise, with the weights of the filter determined by analytical equations in terms of the autocovariance of the process. We approximate the marginal distribution of the process, irrespective of its type, using a number of its cumulants, which in turn determine the cumulants of white noise in a manner that can readily support the generation of random numbers from that approximation, so that it be applicable for stochastic simulation. The simulation method is genuine as it uses the process of interest directly without any transformation (e.g. normalization). We illustrate the method in a number of synthetic and real-world applications with either persistence or antipersistence, and with non-Gaussian marginal distributions that are bounded, thus making the problem more demanding. These include distributions bounded from both sides, such as uniform, and bounded form below, such as exponential and Pareto, possibly having a discontinuity at the origin (intermittence). All examples studied show the satisfactory performance of the method.
Demetris Koutsoyiannis; Panayiotis Dimitriadis. Towards Generic Simulation for Demanding Stochastic Processes. 2021, 1 .
AMA StyleDemetris Koutsoyiannis, Panayiotis Dimitriadis. Towards Generic Simulation for Demanding Stochastic Processes. . 2021; ():1.
Chicago/Turabian StyleDemetris Koutsoyiannis; Panayiotis Dimitriadis. 2021. "Towards Generic Simulation for Demanding Stochastic Processes." , no. : 1.
Lacking coastal and offshore wind speed time series of sufficient length, reanalysis data and wind speed models serve as the primary sources of valuable information for wind power management. In this study, long-length observational records and modelled data from Uncertainties in Ensembles of Regional Re-Analyses system are collected, analyzed and modelled. The first stage refers to the statistical analysis of the time series marginal structure in terms of the fitting accuracy, the distributions’ tails behavior, extremes response and the power output errors, using Weibull distribution and three parameter Weibull-related distributions (Burr Type III and XII, Generalized Gamma). In the second stage, the co-located samples in time and space are compared in order to investigate the reanalysis data performance. In the last stage, the stochastic generation mathematical framework is applied based on a Generalized Hurst-Kolmogorov process embedded in a Symmetric-Moving-Average scheme, which is used for the simulation of a wind process while preserving explicitly the marginal moments, wind’s intermittency and long-term persistence. Results indicate that Burr and Generalized Gamma distribution could be successfully used for wind resource assessment, although, the latter emerged enhanced performance in most of the statistical tests. Moreover, the credibility of the reanalysis data is questionable due to increased bias and root mean squared errors, however, high-order statistics along with the long-term persistence are thoroughly preserved. Eventually, the simplicity and the flexibility of the stochastic generation scheme to reproduce the seasonal and diurnal wind characteristics by preserving the long-term dependence structure are highlighted.
Loukas Katikas; Panayiotis Dimitriadis; Demetris Koutsoyiannis; Themistoklis Kontos; Phaedon Kyriakidis. A stochastic simulation scheme for the long-term persistence, heavy-tailed and double periodic behavior of observational and reanalysis wind time-series. Applied Energy 2021, 295, 116873 .
AMA StyleLoukas Katikas, Panayiotis Dimitriadis, Demetris Koutsoyiannis, Themistoklis Kontos, Phaedon Kyriakidis. A stochastic simulation scheme for the long-term persistence, heavy-tailed and double periodic behavior of observational and reanalysis wind time-series. Applied Energy. 2021; 295 ():116873.
Chicago/Turabian StyleLoukas Katikas; Panayiotis Dimitriadis; Demetris Koutsoyiannis; Themistoklis Kontos; Phaedon Kyriakidis. 2021. "A stochastic simulation scheme for the long-term persistence, heavy-tailed and double periodic behavior of observational and reanalysis wind time-series." Applied Energy 295, no. : 116873.
Time series analysis is a major mathematical tool in hydrology, with the moving average being the most popular model type for this purpose due to its simplicity. During the last 20 years, various studies have focused on an important statistical characteristic, namely the long-term persistence and the simultaneous statistical consistency at all timescales, when different timescales are involved in the simulation. Though these issues have been successfully addressed by various researchers, the solutions that have been suggested are mathematically advanced, which poses a challenge regarding their adoption by practitioners. In this study, a multilayer perceptron network is used to obtain synthetic daily values of rainfall. In order to develop this model, first, an appropriate set of features was selected, and then, a custom cost function was crafted to preserve the important statistical properties in the synthetic time series. This approach was applied to two locations of different climatic conditions that have a long record of daily measurements (more than 100 years for the first and more than 40 years for the second). The results indicate that the suggested methodology is capable of preserving all important statistical characteristics. The advantage of this model is that, once it has been trained, it is straightforward to apply and can be modified easily to analyze other types of hydrologic time series.
Evangelos Rozos; Panayiotis Dimitriadis; Katerina Mazi; Antonis Koussis. A Multilayer Perceptron Model for Stochastic Synthesis. Hydrology 2021, 8, 67 .
AMA StyleEvangelos Rozos, Panayiotis Dimitriadis, Katerina Mazi, Antonis Koussis. A Multilayer Perceptron Model for Stochastic Synthesis. Hydrology. 2021; 8 (2):67.
Chicago/Turabian StyleEvangelos Rozos; Panayiotis Dimitriadis; Katerina Mazi; Antonis Koussis. 2021. "A Multilayer Perceptron Model for Stochastic Synthesis." Hydrology 8, no. 2: 67.
We investigate the impact of time’s arrow on the hourly streamflow process. Although time asymmetry, i.e., temporal irreversibility, has been previously implemented in stochastics, it has only recently attracted attention in the hydrological literature. Relevant studies have shown that the time asymmetry of the streamflow process is manifested at scales up to several days and vanishes at larger scales. The latter highlights the need to reproduce it in flood simulations of fine-scale resolution. To this aim, we develop an enhancement of a recently proposed simulation algorithm for irreversible processes, based on an asymmetric moving average (AMA) scheme that allows for the explicit preservation of time asymmetry at two or more time-scales. The method is successfully applied to a large hourly streamflow time series from the United States Geological Survey (USGS) database, with time asymmetry prominent at time scales up to four days.
Stelios Vavoulogiannis; Theano Iliopoulou; Panayiotis Dimitriadis; Demetris Koutsoyiannis. Multiscale Temporal Irreversibility of Streamflow and Its Stochastic Modelling. Hydrology 2021, 8, 63 .
AMA StyleStelios Vavoulogiannis, Theano Iliopoulou, Panayiotis Dimitriadis, Demetris Koutsoyiannis. Multiscale Temporal Irreversibility of Streamflow and Its Stochastic Modelling. Hydrology. 2021; 8 (2):63.
Chicago/Turabian StyleStelios Vavoulogiannis; Theano Iliopoulou; Panayiotis Dimitriadis; Demetris Koutsoyiannis. 2021. "Multiscale Temporal Irreversibility of Streamflow and Its Stochastic Modelling." Hydrology 8, no. 2: 63.
To seek stochastic analogies in key processes related to the hydrological cycle, an extended collection of several billions of data values from hundred thousands of worldwide stations is used in this work. The examined processes are the near-surface hourly temperature, dew point, relative humidity, sea level pressure, and atmospheric wind speed, as well as the hourly/daily streamflow and precipitation. Through the use of robust stochastic metrics such as the K-moments and a second-order climacogram (i.e., variance of the averaged process vs. scale), it is found that several stochastic similarities exist in both the marginal structure, in terms of the first four moments, and in the second-order dependence structure. Stochastic similarities are also detected among the examined processes, forming a specific hierarchy among their marginal and dependence structures, similar to the one in the hydrological cycle. Finally, similarities are also traced to the isotropic and nearly Gaussian turbulence, as analyzed through extensive lab recordings of grid turbulence and of turbulent buoyant jet along the axis, which resembles the turbulent shear and buoyant regime that dominates and drives the hydrological-cycle processes in the boundary layer. The results are found to be consistent with other studies in literature such as solar radiation, ocean waves, and evaporation, and they can be also justified by the principle of maximum entropy. Therefore, they allow for the development of a universal stochastic view of the hydrological-cycle under the Hurst–Kolmogorov dynamics, with marginal structures extending from nearly Gaussian to Pareto-type tail behavior, and with dependence structures exhibiting roughness (fractal) behavior at small scales, long-term persistence at large scales, and a transient behavior at intermediate scales.
Panayiotis Dimitriadis; Demetris Koutsoyiannis; Theano Iliopoulou; Panos Papanicolaou. A Global-Scale Investigation of Stochastic Similarities in Marginal Distribution and Dependence Structure of Key Hydrological-Cycle Processes. Hydrology 2021, 8, 59 .
AMA StylePanayiotis Dimitriadis, Demetris Koutsoyiannis, Theano Iliopoulou, Panos Papanicolaou. A Global-Scale Investigation of Stochastic Similarities in Marginal Distribution and Dependence Structure of Key Hydrological-Cycle Processes. Hydrology. 2021; 8 (2):59.
Chicago/Turabian StylePanayiotis Dimitriadis; Demetris Koutsoyiannis; Theano Iliopoulou; Panos Papanicolaou. 2021. "A Global-Scale Investigation of Stochastic Similarities in Marginal Distribution and Dependence Structure of Key Hydrological-Cycle Processes." Hydrology 8, no. 2: 59.
In human societies, we observe a wide range of types of stratification, i.e., in terms of financial class, political power, level of education, sanctity, and military force. In financial, political, and social sciences, stratification is one of the most important issues and tools as the Lorenz Curve and the Gini Coefficient have been developed to describe some of its aspects. Stratification is greatly dependent on the access of people to wealth. By “wealth”, we mean the quantified prosperity which increases the life expectancy of people. Prosperity is also connected to the water-food-energy nexus which is necessary for human survival. Analyzing proxies of the water-food-energy nexus, we suggest that the best proxy for prosperity is energy, which is closely related to Gross Domestic Product (GDP) per capita and life expectancy. In order to describe the dynamics of social stratification, we formulate an entropic view of wealth in human societies. An entropic approach to income distribution, approximated as available energy in prehistoric societies, till present-day economies, shows that stratification can be viewed as a stochastic process subject to the principle of maximum entropy and occurring when limits to the wealth of society are set, either by the political and economic system and/or by the limits of available technology.
G.-Fivos Sargentis; Theano Iliopoulou; Panayiotis Dimitriadis; Nikolaos Mamassis; Demetris Koutsoyiannis. Stratification: An Entropic View of Society’s Structure. World 2021, 2, 153 -174.
AMA StyleG.-Fivos Sargentis, Theano Iliopoulou, Panayiotis Dimitriadis, Nikolaos Mamassis, Demetris Koutsoyiannis. Stratification: An Entropic View of Society’s Structure. World. 2021; 2 (2):153-174.
Chicago/Turabian StyleG.-Fivos Sargentis; Theano Iliopoulou; Panayiotis Dimitriadis; Nikolaos Mamassis; Demetris Koutsoyiannis. 2021. "Stratification: An Entropic View of Society’s Structure." World 2, no. 2: 153-174.
Throughout human history, the quantification of aesthetics has intrigued philosophers, artists, and mathematicians alike. In this chapter, a methodology based on stochastic mathematics is applied for the quantification of aesthetic attributes of paintings and landscapes. The paintings analyzed include Da Vinci, Pablo Picasso, and various other celebrated paintings from 1250 AD to modern times. In regard to landscapes, the analysis focuses on the aesthetic transformations imposed to landscapes from wind energy projects. The methodology used is called stochastic 2D-C analysis and is based on a stochastic computational tool that analyzes brightness fluctuation in images. The 2D-C tool is used to measure the degree of variability and in particular the change in variability vs. scale. The application of the tool provides (a) input on the qualitative efficiency of mainstream methods used in landscape-impact analysis, (b) insights into the expression forms of the examined artists and historical periods, and finally (c) evidence that can be used in the search of the originality of an artwork of disputed authorship.
G.-Fivos Sargentis; Romanos Ioannidis; Michalis Chiotinis; Panayiotis G. Dimitriadis; Demetris Koutsoyiannis. Aesthetical Issues with Stochastic Evaluation. Data Analytics for Cultural Heritage 2021, 173 -193.
AMA StyleG.-Fivos Sargentis, Romanos Ioannidis, Michalis Chiotinis, Panayiotis G. Dimitriadis, Demetris Koutsoyiannis. Aesthetical Issues with Stochastic Evaluation. Data Analytics for Cultural Heritage. 2021; ():173-193.
Chicago/Turabian StyleG.-Fivos Sargentis; Romanos Ioannidis; Michalis Chiotinis; Panayiotis G. Dimitriadis; Demetris Koutsoyiannis. 2021. "Aesthetical Issues with Stochastic Evaluation." Data Analytics for Cultural Heritage , no. : 173-193.
During the last decades, scientific research in the field of flood risk management has provided new insights and strong computational tools towards the deeper understanding of the fundamental probabilistic and stochastic behaviour that characterizes such natural hazards. Flood hazards are controlled by hydrometeorological processes and their inherent uncertainties. Historically, a high percentage of flood disasters worldwide are inaccurately or ineffectively reported regarding the aggregated number of the affected people, economic losses and generated flood insurance claims. In this respect, the recently published National Flood Insurance Program (NFIP) data by the Federal Emergency Management Agency (FEMA), including more than two million claims records dating back to 1978 and more than 47 million policy records for transactions, may provide new insights into flood impacts. The aim of this research is to process the actual insurance data derived from this database, in order to detect the underlying patterns and investigate its stochastic structure, paving the way for the development of more accurate flood risk assessment and modelling strategies.
Konstantinos Papoulakos; Theano Iliopoulou; Panayiotis Dimitriadis; Dimosthenis Tsaknias; Demetris Koutsoyiannis. Investigating the stochastic structure of the recently published Redacted Claims data set by the FEMA National Flood Insurance Program. 2021, 1 .
AMA StyleKonstantinos Papoulakos, Theano Iliopoulou, Panayiotis Dimitriadis, Dimosthenis Tsaknias, Demetris Koutsoyiannis. Investigating the stochastic structure of the recently published Redacted Claims data set by the FEMA National Flood Insurance Program. . 2021; ():1.
Chicago/Turabian StyleKonstantinos Papoulakos; Theano Iliopoulou; Panayiotis Dimitriadis; Dimosthenis Tsaknias; Demetris Koutsoyiannis. 2021. "Investigating the stochastic structure of the recently published Redacted Claims data set by the FEMA National Flood Insurance Program." , no. : 1.
The Hydro-telemetric Network, HYDRO-NET, is a pilot streamflow monitoring network established and operated by the Institute for Environmental Research and Sustainable Development of the National Observatory of Athens (NOA) within the HYDRO-NET Project (2018-2021): Hydro-Telemetric Network of Surface Waters: Gauging instruments, smart technologies, installation and operation. An aim of the project is that HYDRO-NETs’ principles of design, installation and operation will guide establishing of hydrometric networks in the Hellenic territory. HYDRO-NET provides a comprehensive framework for collection, transmission, handling and free use of data that combines technological innovations and advanced scientific methods with efficient use of resources. It particularly responds to the need of estimating the discharge at cross-sections of streams where no prior data exist by inexpensive means.
Technological innovations concern the design and construction of a prototype hydro-telemetry system that combines custom built firmware and intelligent measuring technologies with telecommunication at low cost, ~50% the price of a commercial station. This prototype is equipped with an ultrasonic sensor for measuring stage, a thermometer, a GPRS modem, a camera and a data logger (it can also receive input from a rain gauge), and is powered by a solar panel; data and photos are transmitted to NOA’s server via mobile internet. The systems’ additional advantages are flexibility in programming, low maintenance costs, and the possibility of extending its monitoring capabilities with additional sensors (e.g. for monitoring water quality, video camera).
Progress in streamflow estimation is achieved through the development of a maximum-entropy based method that calculates the discharge, at a cross-section of known bathymetry, using measurements of water stage and surface velocity by SVR (Surface Velocity Radar) and/or video cameras. Rating curves at monitoring stations can be thus constructed by inexpensive field campaigns, and safely under flooding.
HYDRO-NET currently operates 16 hydro-telemetric stations, six of which are of NOA’s design, in the Peloponnese and in Attica, Greece. Measured data are transmitted to NOAs’ Server, where they are automatically processed (Quality Controlled) and stored in a Data Base; the data are freely available to users through the OpenHi.net platform (openhi.net), or upon request ([email protected]). A prime service prospect of the HYDRO-NET system, with its real-time observations, is Flood Warning.
Acknowledgment: The Hellenic General Secretariat for Research & Technology has provided financial support, under the National Strategic Reference Framework (2014-2020), for the project HYDRO-NET: Hydro-Telemetric Networks of Surface Waters: Gauging instruments, smart technologies, installation and operation, as a part of the Hellenic Integrated Marine and Inland Water Observing, Forecasting and Offshore Technology System, HIMIOFoTS (MIS5002739) (https://www.himiofots.gr/).
Katerina Mazi; Antonis D. Koussis; Spyridon Lykoudis; Georgios Vitantzakis; Panayiotis Dimitriadis; Nikolaos Kappos; Basil Psiloglou; Dimitrios Katsanos; Ioannis Koletsis; Evangelos Rozos; Theodora Kopania. HYDRO-NET: Hydro-telemetric Network for surface waters – Innovations and Prospects. 2021, 1 .
AMA StyleKaterina Mazi, Antonis D. Koussis, Spyridon Lykoudis, Georgios Vitantzakis, Panayiotis Dimitriadis, Nikolaos Kappos, Basil Psiloglou, Dimitrios Katsanos, Ioannis Koletsis, Evangelos Rozos, Theodora Kopania. HYDRO-NET: Hydro-telemetric Network for surface waters – Innovations and Prospects. . 2021; ():1.
Chicago/Turabian StyleKaterina Mazi; Antonis D. Koussis; Spyridon Lykoudis; Georgios Vitantzakis; Panayiotis Dimitriadis; Nikolaos Kappos; Basil Psiloglou; Dimitrios Katsanos; Ioannis Koletsis; Evangelos Rozos; Theodora Kopania. 2021. "HYDRO-NET: Hydro-telemetric Network for surface waters – Innovations and Prospects." , no. : 1.
Changes in the land cover occur all the time at the surface of the Earth both naturally and anthropogenically. In the last decades, certain types of land cover change, including urbanization, have been correlated to local temperature increase, but the general dynamics of this relationship are still not well understood. This work examines whether land cover is a parameter affecting temperature increase by employing global datasets of land cover change, i.e. the Historical Land-Cover Change Global Dataset, and daily temperature from the NOAA database. We thoroughly investigate the temperature variability and its possible correlation to the different types of land-cover changes. A comparison is specifically made between the rate of temperature increase measured in urban areas, and the same rate measured in nearby non-urban areas.
Aristoklis Lagos; Stavroula Sigourou; Panayiotis Dimitriadis; Theano Iliopoulou; Demetris Koutsoyiannis. Land Cover Change: Does it affect temperature variability? 2021, 1 .
AMA StyleAristoklis Lagos, Stavroula Sigourou, Panayiotis Dimitriadis, Theano Iliopoulou, Demetris Koutsoyiannis. Land Cover Change: Does it affect temperature variability? . 2021; ():1.
Chicago/Turabian StyleAristoklis Lagos; Stavroula Sigourou; Panayiotis Dimitriadis; Theano Iliopoulou; Demetris Koutsoyiannis. 2021. "Land Cover Change: Does it affect temperature variability?" , no. : 1.
Since the pre-industrial era at the end of the 18th century, the atmospheric carbon dioxide concentration (CO2) has increased by 47.46% from the level of 280 ppmv (parts per million volume) to 412.89 ppmv (Mauna Loa – NOAA Station, November 2020). These increased concentrations caused by natural & anthropogenic activities, interact with the aquatic environment which acts as a safety valve. Nevertheless, the absorbed CO2 amounts undergo chemical transformations, resulting in increasing ionized concentrations that can significantly reduce the water’s pH, a process described as ocean acidification. Here, we use the HOT (Hawaii-Ocean-Time series) to perform time series analysis for temperature, carbon dioxide partial pressure and pH. More specifically, we analyze their temporal changes in month and annual time lag. Then, we proceed in comparisons with relevant studies on atmospheric data to evaluate the produced results. Finally, we make an effort to disentangle the results with simplified assumptions connected with the observed impact of ocean acidification on the aquatic ecosystems.
Georgios Vagenas; Theano Iliopoulou; Panayiotis Dimitriadis; Demetris Koutsoyiannis. Stochastic analysis of time-series related to ocean acidification. 2021, 1 .
AMA StyleGeorgios Vagenas, Theano Iliopoulou, Panayiotis Dimitriadis, Demetris Koutsoyiannis. Stochastic analysis of time-series related to ocean acidification. . 2021; ():1.
Chicago/Turabian StyleGeorgios Vagenas; Theano Iliopoulou; Panayiotis Dimitriadis; Demetris Koutsoyiannis. 2021. "Stochastic analysis of time-series related to ocean acidification." , no. : 1.
In the last few years, the island of Crete (Greece - Eastern Mediterranean) has been affected by extreme events. In recent decades, hydrometeorological processes in the island of Crete are monitored by an extensive network of meteorological stations. Here we stochastically analyze the spatial stochastic structure of precipitation in the island by employing sophisticated statistical tools, as well as by analyzing a large database of daily precipitation records. We investigate fifty-eight rainfall stations scattered in the four prefectures of Crete, for the years 1974-2020. Descriptive statistical analysis of precipitation examines several temporal properties in the data, while correlation analysis of precipitation variability provides relations between stations and regions for spatial patterns identification. This work also investigates the precipitation variability by employing statistical tools such as the autocorrelation, autoregressive (seasonal) analysis, probability distribution function fitting, and climacogram calculation, i.e. variance of the averaged process vs. spatial and temporal scales, to identify statistical properties, temporal dependencies, potential similarities in the dependence structure and marginal probability distribution.
Olianna Akoumianaki; Theano Iliopoulou; Panayiotis Dimitriadis; Emmanouil Varouchakis; Demetris Koutsoyiannis. Stochastic analysis of the spatial stochastic structure of precipitation in the island of Crete, Greece. 2021, 1 .
AMA StyleOlianna Akoumianaki, Theano Iliopoulou, Panayiotis Dimitriadis, Emmanouil Varouchakis, Demetris Koutsoyiannis. Stochastic analysis of the spatial stochastic structure of precipitation in the island of Crete, Greece. . 2021; ():1.
Chicago/Turabian StyleOlianna Akoumianaki; Theano Iliopoulou; Panayiotis Dimitriadis; Emmanouil Varouchakis; Demetris Koutsoyiannis. 2021. "Stochastic analysis of the spatial stochastic structure of precipitation in the island of Crete, Greece." , no. : 1.
A physical process is characterized as complex when it is difficult to analyze and explain in a simple way, and even more difficult to predict. The complexity within an art painting is expected to be high, possibly comparable to that of nature. Herein, we apply a 2D stochastic methodology to images of both portrait photography and artistic portraits, the latter belonging to different genres of art, with the aim to better understand their variability in quantitative terms. To quantify the dependence structure and variability, we estimate the Hurst parameter, which is a common dependence metric for hydrometeorological processes. We also seek connections between the identified stochastic patterns and the desideratum that each art movement aimed to express. Results show remarkable stochastic similarities between portrait paintings, linked to philosophical, cultural and theological characteristics of each period.
G.-Fivos Sargentis; Panayiotis Dimitriadis; Theano Iliopoulou; Demetris Koutsoyiannis. A Stochastic View of Varying Styles in Art Paintings. Heritage 2021, 4, 333 -348.
AMA StyleG.-Fivos Sargentis, Panayiotis Dimitriadis, Theano Iliopoulou, Demetris Koutsoyiannis. A Stochastic View of Varying Styles in Art Paintings. Heritage. 2021; 4 (1):333-348.
Chicago/Turabian StyleG.-Fivos Sargentis; Panayiotis Dimitriadis; Theano Iliopoulou; Demetris Koutsoyiannis. 2021. "A Stochastic View of Varying Styles in Art Paintings." Heritage 4, no. 1: 333-348.
Even though landscape quality is largely a subjective issue, the integration of infrastructure into landscapes has been identified as a key element of sustainability. In a spatial planning context, the landscape impacts that are generated by infrastructures are commonly quantified through visibility analysis. In this study, we develop a new method of visibility analysis and apply it in a case study of a reservoir (Plastiras dam in Greece). The methodology combines common visibility analysis with a stochastic tool for visual-impacts evaluation; points that generate high visual contrasts in landscapes are considered Focus Points (FPs) and their clustering in landscapes is analyzed trying to answer two questions: (1) How does the clustering of Focus Points (FPs) impact the aesthetic value of the landscape? (2) How can the visual impacts of these FPs be evaluated? Visual clustering is calculated utilizing a stochastic analysis of generated Zones of Theoretical Visibility. Based on the results, we argue that if the visual effect of groups of FPs is positive, then the optimal sitting of FPs should be in the direction of faint clustering, whereas if the effect is negative, the optimal sitting of FPs should be directed to intense clustering. In order to optimize the landscape integration of infrastructure, this method could be a useful analytical tool for environmental impact assessment or a monitoring tool for a project’s managing authorities. This is demonstrated through the case study of Plastiras’ reservoir, where the clustering of positively perceived FPs is found to be an overlooked attribute of its perception as a highly sustainable infrastructure project.
G.-Fivos Sargentis; Romanos Ioannidis; Theano Iliopoulou; Panayiotis Dimitriadis; Demetris Koutsoyiannis. Landscape Planning of Infrastructure through Focus Points’ Clustering Analysis. Case Study: Plastiras Artificial Lake (Greece). Infrastructures 2021, 6, 12 .
AMA StyleG.-Fivos Sargentis, Romanos Ioannidis, Theano Iliopoulou, Panayiotis Dimitriadis, Demetris Koutsoyiannis. Landscape Planning of Infrastructure through Focus Points’ Clustering Analysis. Case Study: Plastiras Artificial Lake (Greece). Infrastructures. 2021; 6 (1):12.
Chicago/Turabian StyleG.-Fivos Sargentis; Romanos Ioannidis; Theano Iliopoulou; Panayiotis Dimitriadis; Demetris Koutsoyiannis. 2021. "Landscape Planning of Infrastructure through Focus Points’ Clustering Analysis. Case Study: Plastiras Artificial Lake (Greece)." Infrastructures 6, no. 1: 12.
Clustering structures appearing from small to large scales are ubiquitous in the physical world. Interestingly, clustering structures are omnipresent in human history too, ranging from the mere organization of life in societies (e.g., urbanization) to the development of large-scale infrastructure and policies for meeting organizational needs. Indeed, in its struggle for survival and progress, mankind has perpetually sought the benefits of unions. At the same time, it is acknowledged that as the scale of the projects grows, the cost of the delivered products is reduced while their quantities are maximized. Thus, large-scale infrastructures and policies are considered advantageous and are constantly being pursued at even great scales. This work develops a general method to quantify the temporal evolution of clustering, using a stochastic computational tool called 2D-C, which is applicable for the study of both natural and human social spatial structures. As case studies, the evolution of the structure of the universe, of ecosystems and of human clustering structures such as urbanization, are investigated using novel sources of spatial information. Results suggest the clear existence both of periods of clustering and declustering in the natural world and in the human social structures; yet clustering is the general trend. In view of the ongoing COVID-19 pandemic, societal challenges arising from large-scale clustering structures are discussed.
G.-Fivos Sargentis; Theano Iliopoulou; Stavroula Sigourou; Panayiotis Dimitriadis; Demetris Koutsoyiannis. Evolution of Clustering Quantified by a Stochastic Method—Case Studies on Natural and Human Social Structures. Sustainability 2020, 12, 7972 .
AMA StyleG.-Fivos Sargentis, Theano Iliopoulou, Stavroula Sigourou, Panayiotis Dimitriadis, Demetris Koutsoyiannis. Evolution of Clustering Quantified by a Stochastic Method—Case Studies on Natural and Human Social Structures. Sustainability. 2020; 12 (19):7972.
Chicago/Turabian StyleG.-Fivos Sargentis; Theano Iliopoulou; Stavroula Sigourou; Panayiotis Dimitriadis; Demetris Koutsoyiannis. 2020. "Evolution of Clustering Quantified by a Stochastic Method—Case Studies on Natural and Human Social Structures." Sustainability 12, no. 19: 7972.
Image velocimetry is a popular remote sensing method mainly because of the very modest cost of the necessary equipment. However, image velocimetry methods employ parameters that require high expertise to select appropriate values in order to obtain accurate surface flow velocity estimations. This introduces considerations regarding the subjectivity introduced in the definition of the parameter values and its impact on the estimated surface velocity. Alternatively, a statistical approach can be employed instead of directly selecting a value for each image velocimetry parameter. First, probability distribution should be defined for each model parameter, and then Monte Carlo simulations should be employed. In this paper, we demonstrate how this statistical approach can be used to simultaneously produce the confidence intervals of the estimated surface velocity, reduce the uncertainty of some parameters (more specifically, the size of the interrogation area), and reduce the subjectivity. Since image velocimetry algorithms are CPU-intensive, an alternative random number generator that allows obtaining the confidence intervals with a limited number of iterations is suggested. The case study indicated that if the statistical approach is applied diligently, one can achieve the previously mentioned threefold objective.
Evangelos Rozos; Panayiotis Dimitriadis; Katerina Mazi; Spyridon Lykoudis; Antonis Koussis. On the Uncertainty of the Image Velocimetry Method Parameters. Hydrology 2020, 7, 65 .
AMA StyleEvangelos Rozos, Panayiotis Dimitriadis, Katerina Mazi, Spyridon Lykoudis, Antonis Koussis. On the Uncertainty of the Image Velocimetry Method Parameters. Hydrology. 2020; 7 (3):65.
Chicago/Turabian StyleEvangelos Rozos; Panayiotis Dimitriadis; Katerina Mazi; Spyridon Lykoudis; Antonis Koussis. 2020. "On the Uncertainty of the Image Velocimetry Method Parameters." Hydrology 7, no. 3: 65.
A physical process is characterized as complex when it is difficult to analyze or explain in a simple way. The complexity within an art painting is expected to be high, possibly comparable to that of nature. Therefore, constructions of artists (e.g., paintings, music, literature, etc.) are expected to be also of high complexity since they are produced by numerous human (e.g., logic, instinct, emotions, etc.) and non-human (e.g., quality of paints, paper, tools, etc.) processes interacting with each other in a complex manner. The result of the interaction among various processes is not a white-noise behavior, but one where clusters of high or low values of quantified attributes appear in a non-predictive manner, thus highly increasing the uncertainty and the variability. In this work, we analyze stochastic patterns in terms of the dependence structure of art paintings of Da Vinci and Picasso with a stochastic 2D tool and investigate the similarities or differences among the artworks.
G.-Fivos Sargentis; Panayiotis Dimitriadis; Demetris Koutsoyiannis. Aesthetical Issues of Leonardo Da Vinci’s and Pablo Picasso’s Paintings with Stochastic Evaluation. Heritage 2020, 3, 283 -305.
AMA StyleG.-Fivos Sargentis, Panayiotis Dimitriadis, Demetris Koutsoyiannis. Aesthetical Issues of Leonardo Da Vinci’s and Pablo Picasso’s Paintings with Stochastic Evaluation. Heritage. 2020; 3 (2):283-305.
Chicago/Turabian StyleG.-Fivos Sargentis; Panayiotis Dimitriadis; Demetris Koutsoyiannis. 2020. "Aesthetical Issues of Leonardo Da Vinci’s and Pablo Picasso’s Paintings with Stochastic Evaluation." Heritage 3, no. 2: 283-305.
We compare the stochastic behaviour of temperature outputs of climate models for the 20th century
to the historical data (stations and reanalysis fields) at several temporal and spatial scales. In
particular we examine the marginal distributions and the dependence structure with emphasis on
the Hurst-Kolmogorov behaviour. The comparison aims to contribute to the quantification of
reliability and predictive uncertainty of temperature climate model outputs over different scales in a
framework of assessing their relevance for engineering planning and design.
(Acknowledgement: This research is conducted within the frame of the course "Stochastic Methods"
of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA
provided moral support for the participation of the students in the Assembly.)
Georgios Angelopoulos; Panayiotis Dimitriadis; Theano Iliopoulou; Demetris Koutsoyiannis. Stochastic comparison of climate model outputs to observed temperature fields. 2020, 1 .
AMA StyleGeorgios Angelopoulos, Panayiotis Dimitriadis, Theano Iliopoulou, Demetris Koutsoyiannis. Stochastic comparison of climate model outputs to observed temperature fields. . 2020; ():1.
Chicago/Turabian StyleGeorgios Angelopoulos; Panayiotis Dimitriadis; Theano Iliopoulou; Demetris Koutsoyiannis. 2020. "Stochastic comparison of climate model outputs to observed temperature fields." , no. : 1.
Isolated areas may face difficulties regarding both energy security and water supply as they are often not connected to the energy and water network of the mainland. In this respect, we investigate the integration of a desalination plant in the planning of a hybrid renewable energy system for an isolated area, in order to satisfy energy and freshwater needs. We examine the major desalination technologies (thermal, membrane) and we compare their advantages, limitations and potential for water production, in a small Aegean island. Using stochastic approaches for the energy and water demand and production, the reliability and feasibility of such a renewable energy-based desalination plant are investigated.
Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.
Argyris Ntrizai; Panayiotis Dimitriadis; Theano Iliopoulou; Nikos Mamassis; Demetris Koutsoyiannis. Integrating water desalination plants in renewable energy systems for isolated areas. 2020, 1 .
AMA StyleArgyris Ntrizai, Panayiotis Dimitriadis, Theano Iliopoulou, Nikos Mamassis, Demetris Koutsoyiannis. Integrating water desalination plants in renewable energy systems for isolated areas. . 2020; ():1.
Chicago/Turabian StyleArgyris Ntrizai; Panayiotis Dimitriadis; Theano Iliopoulou; Nikos Mamassis; Demetris Koutsoyiannis. 2020. "Integrating water desalination plants in renewable energy systems for isolated areas." , no. : 1.
We simulate the electrical energy production in the remote island of Astypalaia, Greece. Solar, wind, hydropower, biomass and marine energy are used for the energy mix. The hypothetical energy system has also the ability to store energy through a pumped-storage unit. We use available data at various time scales. The aim of this work is to optimize the energy management of the hypothetical system studied.
Acknowledgement: This research is conducted within the frame of the undergraduate course "Stochastic Methods" of the National Technical University of Athens (NTUA). The School of Civil Engineering of NTUA provided moral support for the participation of the students in the Assembly.
Konstantinos Karkanis; Ioannis Vatsikouridis; Theano Iliopoulou; Panayiotis Dimitriadis; Demetris Koutsogiannis; Nikolaos Mamassis. Simulation of electricity production in a remote island for optimal management of a hybrid renewable energy system. 2020, 1 .
AMA StyleKonstantinos Karkanis, Ioannis Vatsikouridis, Theano Iliopoulou, Panayiotis Dimitriadis, Demetris Koutsogiannis, Nikolaos Mamassis. Simulation of electricity production in a remote island for optimal management of a hybrid renewable energy system. . 2020; ():1.
Chicago/Turabian StyleKonstantinos Karkanis; Ioannis Vatsikouridis; Theano Iliopoulou; Panayiotis Dimitriadis; Demetris Koutsogiannis; Nikolaos Mamassis. 2020. "Simulation of electricity production in a remote island for optimal management of a hybrid renewable energy system." , no. : 1.