Improved approach to wave potential estimation using bivariate distributions

2021 ◽  
pp. 1-6
Author(s):  
Rafael Guzmán-Cabrera ◽  
Iván A. Hernández-Robles ◽  
Xiomara González Ramírez ◽  
José Rafael Guzmán Sepúlveda
Keyword(s):  
Extreme Values ◽  
Joint Probability ◽  
Data Series ◽  
Sea Waves ◽  
Probability Models ◽  
Energy Potential ◽  
Activity Data ◽  
Reduced Representation ◽  
Amplitude Fluctuations ◽  
The Waves

Probabilistic approaches are frequently used to describe irregular activity data to assist the design and development of devices. Unfortunately, useful estimations are not always feasible due to the large noise in the data modeled, as it occurs when estimating the sea waves potential for electricity generation. In this work we propose a simple methodology based on the use of joint probability models that allow discriminating extreme values, collected from measurements as pairs of independent points, while allowing the preservation of the essential statistics of the measurements. The outcome of the proposed methodology is an equivalent data series where large-amplitude fluctuations are suppressed and, therefore, can be used for design purposes. For the evaluation of the proposed method, we used year-long databases of hourly-collected measurements of the wave’s height and period, performed at maritime buoys located in the Gulf of Mexico. These measurements are used to obtain a fluctuations-reduced representation of the energy potential of the waves that can be useful, for instance, for the design of electric generators.

Wind speed data analysis for predictions of sea waves in Bitung Coastal Waters

2013 ◽  
pp. 35 ◽  
Author(s):  
Joanes E Koagouw ◽  
Gybert E Mamuaya ◽  
Adrie A Tarumingkeng ◽  
P A Angmalisang
Keyword(s):  
Data Analysis ◽  
Wind Speed ◽  
Coastal Waters ◽  
Transition Period ◽  
Marine Resources ◽  
Land Uses ◽  
Sea Waves ◽  
North West ◽  
North Sulawesi ◽  
The Waves

Coastal area of Bitung Municipality is one of the economical activities centers in North Sulawesi Province such as for land-uses and the exploitation of natural resources. Those activities are exaggerating day bay day and tended to be uncontrollable. The excess of those conditions, it has been recorded the change of waves in Bitung waters that has impacts to coastal areas and can affect the utilization of coastal and marine resources. This research was aimed to observe waves altitude variations in Bitung waters with Svedrup Munk and Bretchsneider (SMB) method that had been used to predict waves altitudes. The results showed that the wind speed during West Season was 0.33 m and were dominant to the East, while during East season was 0.91m from South-East to North-West, and then on transition period (March to May) was 1.08m from South-East to East. The results of those wind speed to the waves altitudes in Bitung waters is discussed in this paper© Pesisir pantai Kota Bitung merupakan salah satu pusat aktivitas ekonomi (misalnya pemanfaatan lahan dan eksploitasi sumberdaya) di Provinsi Sulawesi Utara. Aktivitas tersebut semakin hari semakin meningkat dan memiliki kecenderungan tidak terkontrol. Akibat dari keadaan tersebut, telah terjadi perubahan fenomena gelombang di perairan Bitung yang berdampak pada keberadaan daerah pesisir pantai di mana hal ini dapat mengganggu aktivitas pemanfaatan sumberdaya pesisir dan laut tersebut. Penelitian ini bertujuan untuk mengetahui variasi tinggi gelombang di perairan Bitung dengan menggunakan metode Svedrup Munk and Bretchsneider (SMB) yang biasa digunakan untuk peramalan tinggi gelombang signifikan. Hasil penelitian menunjukkan bahwa kecepatan angin pada Musim Barat sebesar 0,33 meter dan dominan ke arah Timur, sementara pada Musim Timur sebesar 0,91 meter dari arah Tenggara ke Barat Laut, serta pada Musim Peralihan (antara bulan Maret-Mei) adalah sebesar 1,08 meter dari arah Tenggara dan Timur. Pengaruh kecepatan angin tersebut terhadap gelombang laut di perairan Bitung dibahas dalam tulisan ini©

scholarly journals WAVES AT SEKONDI, GHANA

1966 ◽  
Vol 1 (10) ◽  
pp. 1 ◽  
Author(s):  
L. Draper
Keyword(s):  
Southern Hemisphere ◽  
Sea Waves ◽  
Severe Damage ◽  
Pressure Recording ◽  
Electric Wave ◽  
International Geophysical Year ◽  
Time Of Year ◽  
The Waves ◽  
Wave Recorder ◽  
International Geophysical

During the International Geophysical Year the National Institute of Oceanography in collaboration with Ghana IGY Committee and the Ghana Railway and Harbours Administration made recordings of sea waves at a point 2,300 feet off Sekondi point in a direction 156°. The instrument used was an N.I.O. piezo-electric wave recorder of the pressure recording type. Recordings started in June, 1958, and continued until the end of October that year when the cable suffered severe damage which could not easily be repaired. Because of the high cost of cable and the fact that a good series of records had already been obtained for a rough time of year, the instrument was recovered and used elsewhere. Records were taken every two hours and each has a useable length of twelve minutes. Most of the waves arriving at Sekondi are in the form of swell which has been generated by storms in the southern hemisphere; consequently wave conditions do not change very quickly, and it was found unnecessary to analyse every record except during rough conditions. The method of analysis used is that described in the associated paper "The Analysis and Presentation of Wave Data - a Plea for Uniformity".

scholarly journals A New Solution for Sea Wave Energy Harvesting, the Proposal of an Ironless Linear Generator

2020 ◽  
Vol 8 (2) ◽  
pp. 93 ◽  
Author(s):  
Domenico Curto ◽  
Alessia Viola ◽  
Vincenzo Franzitta ◽  
Marco Trapanese ◽  
Fabio Cardona
Keyword(s):  
Wave Energy ◽  
Magnetic Force ◽  
Vertical Motion ◽  
Small Islands ◽  
Sea Waves ◽  
Energy Converter ◽  
Energy Potential ◽  
Linear Generator ◽  
Three Phase ◽  
Sea Wave

The paper investigates an innovative ironless linear generator, installable inside a wave energy converter, in order to produce electricity from sea waves. This energy source is considered strategic for the future, especially in small islands; however, this technology is still far from the commercial phase. Considering the wave energy potential of the Mediterranean Sea, a first prototype of the electrical linear generator was realized at the Department of Engineering of Palermo University. This machine can be run by a two-floating buoys system, able to produce a linear vertical motion. The main goal of this paper is the investigation of the advantages and the disadvantages of the utilization of steel materials to realize the stator of linear generators. Thus, starting from the prototype, the authors analyzed the effects produced by the replacement of steel in the stator with a non-magnetic material. For comparison, the authors evaluated the amplitude of no-load voltages, using a three-phase connection scheme, and the amplitude of the magnetic force produced by the interaction of magnets with the stator. Both aspects were evaluated through numerical simulations and mathematical models.

Part I. The diffraction theory of sea waves and the shelter afforded by breakwaters

1952 ◽  
Vol 244 (882) ◽  
pp. 236-253 ◽  
Keyword(s):  
Diffraction Theory ◽  
Small Island ◽  
Sea Waves ◽  
Diffraction Of Light ◽  
Wave Patterns ◽  
Wave Heights ◽  
Optical Phenomena ◽  
The Waves

The diffraction of sea waves round the end of a long straight breakwater is investigated, use being made of the solutions of mathematically analogous problems in the diffraction of light. The wave patterns and wave heights are determined on both the leeward and windward sides of the breakwater, and for points quite close to the breakwater. This involves some extension of the calculations previously made for optical phenomena. The conditions obtaining in the lee of a small island are discussed. The penetration of waves through a single gap in a long breakwater is examined, and the result is shown to depend very much on whether the gap is small or not compared with the length of the waves. The investigation was suggested by problems arising in the construction of the Mulberry harbours.

scholarly journals ASSESSMENT OF THE ENERGY POTENTIAL OF THE WAVES IN THE BLACK SEA

2018 ◽  
Vol 8 (3) ◽  
pp. 5-10
Author(s):  
Carmen Gasparotti ◽  
◽  
Eugen Rusu ◽  
◽  
◽  
...  
Keyword(s):  
Black Sea ◽  
The Black Sea ◽  
Energy Potential ◽  
The Waves

scholarly journals A CFD Study with Fuzzy Logic Pitch Angle Turbine Control Implementation for OWC Generation System

2017 ◽  
Vol 6 (2) ◽  
pp. 175
Author(s):  
Mansour Madaci ◽  
Djallel Kerdoun
Keyword(s):  
Pitch Angle ◽  
Wave Model ◽  
Sea Waves ◽  
Generation System ◽  
Fem Model ◽  
Wave Generator ◽  
The Waves ◽  
Fast Variation ◽  
Extracted Power ◽  
Control Implementation

The paper takes the improvement of the performance for an OWC converter from the mechanical side. A FEM model of the OWC conversion structure was proposed, studied and simulated using a CFD simulator. A novel wave generation method was applied through the RWMD method (Real Wave Model Simulator) instead of using an ordinary sin wave generator on the tank to make the waves the closest possible to the real sea waves. A mechanical prototype was built for this purpose to get an oscillated wave model. On the electrical side, a pitch angle control system based on fuzzy set was applied on the turbine to be auto-adapted for the fast variation of the airflow speed to establish and maximize the extracted power from the OWC device. The model have been studied, simulated, implemented and tested to validate the obtained results.

scholarly journals Point Process Temporal Structure Characterizes Electrodermal Activity

2020 ◽  
Author(s):  
Sandya Subramanian ◽  
Riccardo Barbieri ◽  
Emery N. Brown
Keyword(s):  
Point Process ◽  
Electrodermal Activity ◽  
Temporal Structure ◽  
Physiological State ◽  
Electrical Conductance ◽  
Pulse Interval ◽  
Data Series ◽  
Inverse Gaussian ◽  
Probability Models ◽  
Gaussian Models

AbstractElectrodermal activity (EDA) is a read-out of the body’s sympathetic nervous system measured as sweat-induced changes in the electrical conductance properties of the skin. There is growing interest in using EDA to track physiological conditions such as stress levels, sleep quality and emotional states. Standardized EDA data analysis methods are readily available. However, none considers two established physiological features of EDA: 1) sympathetically mediated pulsatile changes in skin sweat measured as EDA resemble an integrate-and-fire process; 2) inter-pulse interval times vary depending upon the local physiological state of the skin. Based on the anatomy and physiology that underlie feature 1, we postulate that inverse Gaussian probability models would accurately describe EDA inter-pulse intervals. Given feature 2, we postulate that under fluctuating local physiological states, the inter-pulse intervals would follow mixtures of inverse Gaussian models, that can be represented as lognormal models if the conditions favor longer intervals (heavy tails) or by gamma models if the conditions favor shorter intervals (light tails). To assess the validity of these probability models we recorded and analyzed EDA measurements in 11 healthy volunteers during 1 to 2 hours of quiet wakefulness. We assess the tail behavior of the probability models by computing their settling rates. All data series were accurately described by one or more of the models: two by inverse Gaussian models; five by lognormal models and three by gamma models. These probability models suggest a highly succinct point process framework for real-time tracking of sympathetically-mediated changes in physiological state.

New models for Markov random fields

1992 ◽  
Vol 29 (04) ◽  
pp. 877-884 ◽  
Author(s):  
Noel Cressie ◽  
Subhash Lele
Keyword(s):  
Random Field ◽  
Conditional Probability ◽  
Markov Random Field ◽  
Random Fields ◽  
Markov Random Fields ◽  
Sufficient Conditions ◽  
Joint Probability ◽  
Probability Models ◽  
Markov Random ◽  
New Models

The Hammersley–Clifford theorem gives the form that the joint probability density (or mass) function of a Markov random field must take. Its exponent must be a sum of functions of variables, where each function in the summand involves only those variables whose sites form a clique. From a statistical modeling point of view, it is important to establish the converse result, namely, to give the conditional probability specifications that yield a Markov random field. Besag (1974) addressed this question by developing a one-parameter exponential family of conditional probability models. In this article, we develop new models for Markov random fields by establishing sufficient conditions for the conditional probability specifications to yield a Markov random field.

scholarly journals Factors Influencing the Performance of Regression-Based Statistical Postprocessing Models for Short-Term Precipitation Forecasts

2019 ◽  
Vol 34 (6) ◽  
pp. 2067-2084
Author(s):  
Wentao Li ◽  
Qingyun Duan ◽  
Quan J. Wang
Keyword(s):  
Prediction Models ◽  
Probability Model ◽  
Weather Prediction ◽  
Joint Probability ◽  
Ensemble Spread ◽  
Probability Models ◽  
Short Term ◽  
Huai River ◽  
Censored Regression Model ◽  
Distributional Regression

Abstract Statistical postprocessing models can be used to correct bias and dispersion errors in raw precipitation forecasts from numerical weather prediction models. In this study, we conducted experiments to investigate four factors that influence the performance of regression-based postprocessing models with normalization transformations for short-term precipitation forecasts. The factors are 1) normalization transformations, 2) incorporation of ensemble spread as a predictor in the model, 3) objective function for parameter inference, and 4) two postprocessing schemes, including distributional regression and joint probability models. The experiments on the first three factors are based on variants of a censored regression model with conditional heteroscedasticity (CRCH). For the fourth factor, we compared CRCH as an example of the distributional regression with a joint probability model. The results show that the CRCH with normal quantile transformation (NQT) or power transformation performs better than the CRCH with log–sinh transformation for most of the subbasins in Huai River basin with a subhumid climate. The incorporation of ensemble spread as a predictor in CRCH models can improve forecast skill in our research region at short lead times. The influence of different objective functions (minimum continuous ranked probability score or maximum likelihood) on postprocessed results is limited to a few relatively dry subbasins in the research region. Both the distributional regression and the joint probability models have their advantages, and they are both able to achieve reliable and skillful forecasts.

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