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Poverty alleviation, regional balances and balanced development are considered in all upstream documents and the development plans after the revolution in Iran. The political leaders and policy-makers have also emphasized on them continuously. Nevertheless, there are always major imbalances and differences in poverty and development levels among Iran’s provinces. In this study, unlike previous studies, regional imbalances are measured in terms of political economy. This study tries to explain regional imbalances with economicpolitical power and then adjust it with consider to population, area and distance of the provinces from the center of political power. To doing so, at first, the economic-political power matrix is formed for Iran’s provinces and then the economicpolitical power is calculated using TOPSIS method during the period of 2004-2019. After that, this matrix is adjusted using population, area and distance of provinces from capital city. The results show that even with the adjustment, economicpolitical power among regions is significantly differ. The regions cannot be considered homogeneous from the point of view of economic-political power. [ABSTRACT FROM AUTHOR]

Remarkable advancements have been made in wave energy converters, notably the innovative WaveSAX technology—an oscillating water column system conceptually designed for coastal structures. Proven effective in existing installations, particularly at Civitavecchia Port, Italy, where the WaveSAX-1 prototype was tested in 2018 and the WaveSAX-2 was updated in 2021. The device's power generation capacity was evaluated using a Simulating WAves Nearshore (SWAN) model that simulated 30 years of wave conditions. Validation with radar and Acoustic Doppler Profiler instruments showed excellent performance in wave height simulation. Results revealed higher wave power generation near the harbor breakwater, surpassing offshore levels, especially in central and northern sections. WaveSAX-2, featuring an improved Wells turbine, demonstrated a remarkable 37% increase in average efficiency compared to WaveSAX-1. If a linear WaveSAX array were installed, it could produce 4 GWh annually, satisfying 20% of the port's energy needs and reducing around 2800 tCO2e/year. Doubling arrays and incorporating triangular modules could significantly enhance sustainability for port operations, offering a promising path toward self-sufficiency and environmental responsibility. [ABSTRACT FROM AUTHOR]

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The aim of this work is to assess the influence of different degrees of adaptability of the power take-off (PTO) system on the power absorption of dense wave energy converter (WEC) arrays. The adaptability is included in simulations through a transmission ratio that scales the force actuating the PTO relative to the force generated by the motion of a floater. A numerical model is used in which hydrodynamic interactions between floaters and nonlinearities in the PTO are considered. The lower computational cost of this numerical model makes it possible to study the power extraction of a dense WEC array in irregular waves to easily create power matrices and other performance metrics. The methodology is applied to the case study of the Ocean Grazer WEC to showcase the potential performance improvements achieved through the inclusion of a transmission ratio. The analysis shows that including a high degree of adaptability and choosing WEC array configurations and PTO designs specific to potential deployment locations early in the design process can lead to an increase in extracted power. • The adaptability of a wave energy converter array needs to be defined at the design stage. • The range of adaptability of a design depends on the deployment location. • Increased adaptability results in increased power extraction. [ABSTRACT FROM AUTHOR]

Many studies have evaluated political power from a qualitative and quantitative perspective. But the present study tries to provide a quantitative criterion for calculation of power. To do this, using the country’s budget law, the institutions that enjoys from national budget are identified and then the officials who are at the head of those institutions from each province are identified. Then the importance coefficient of each official is calculated based on multiplication of two indicators: the allocated budget to his/her institution or organization and the duration of his/her tenure in each year. The power matrix for each province is made. Finally, the power index for Iranian provinces is calculated using methods of Simple Additive Weighting, TOPSIS, and Numerical Taxonomy. Then, according to TOPSIS method, the regions of Iran were divided into four groups. The findings show fundamental inequalities in the distribution of economic- political power in the regions of Iran during the period of 2009-2019. Also, The most fluctuations in economic-political power index have occured mainly in the middle groups. Since, most previous studies have emphasized regional inequalities in Iran based on various indicators, it seems that there is a correlation between the distribution of economic-political power and regional inequalities of Economic development. As a result, given the current status without change in the political power of the provinces, one can not expect a significant change in the economic development of the regions.

Let $ a, b $ and $ n $ be positive integers and let $ S $ be a set consisting of $ n $ distinct positive integers $ x_1, ..., x_{n-1} $ and $ x_n $. Let $ (S^a) $ (resp. $ [S^a] $) denote the $ n\times n $ matrix having $ \gcd(x_i, x_j)^a $ (resp. $ {\rm lcm}(x_i, x_j)^a $) as its $ (i, j) $-entry. For any integer $ x\in S $, if $ (y < x, y|z|x \ {\rm and} \ y, z\in S)\Rightarrow z\in\{y, x\} $, then $ y $ is called a greatest-type divisor of $ x $ in $ S $. In this paper, we establish some results about the divisibility between $ (S^a) $ and $ (S^b) $, between $ (S^a) $ and $ [S^b] $ and between $ [S^a] $ and $ [S^b] $ when $ a|b $, $ S $ is gcd closed (i.e., $ \gcd(x_i, x_j)\in S $ for all $ 1\le i, j\le n $), and $ \max_{x\in S}\{|\{y\in S: y \ \text{is a greatest-type divisor of} \ x \ {\rm in} \ S\}|\} = 2 $.

Remarkable advancements have been made in wave energy converters, notably the innovative WaveSAX technology—an oscillating water column system conceptually designed for coastal structures. Proven effective in existing installations, particularly at Civitavecchia Port, Italy, where the WaveSAX-1 prototype was tested in 2018 and the WaveSAX-2 was updated in 2021. The device’s power generation capacity was evaluated using a Simulating WAves Nearshore (SWAN) model that simulated 30 years of wave conditions. Validation with radar and Acoustic Doppler Profiler instruments showed excellent performance in wave height simulation. Results revealed higher wave power generation near the harbor breakwater, surpassing offshore levels, especially in central and northern sections. WaveSAX-2, featuring an improved Wells turbine, demonstrated a remarkable 37% increase in average efficiency compared to WaveSAX-1. If a linear WaveSAX array were installed, it could produce 4 GWh annually, satisfying 20% of the port’s energy needs and reducing around 2800 tCO2e/year. Doubling arrays and incorporating triangular modules could significantly enhance sustainability for port operations, offering a promising path toward self-sufficiency and environmental responsibility.

Refined numerical wave energy resource assessments are required to reduce uncertainties in the evaluation of available power and energy production. However, to restrict the computational cost, a great part of wave hindcast simulations cover a limited time range (below ten years) or rely on coarse spatial resolutions while routinely ignoring tide-induced modulations in wave conditions. Complementing resource assessments conducted in the North-West European shelf seas, we here exploited a 27-year hindcast database (1994–2020) set up at a spatial resolution of 200 m along the coast of France and integrating the effects of tidal currents on waves. This evaluation was conducted in three water depths from offshore to nearshore (60, 40 and 20 m) around Brittany, one of the most energetic regions along the coast of France. We investigated the performances of a series of thirteen state-of-the-art wave energy converters with respect to installation depth range. Beyond confirming the interest of western Brittany in energy exploitation, the results exhibited the first ranking between devices, thus promoting the interests of Oceantec in offshore waters (60 m), Wave Dragon in intermediate waters (40 m), and Oyster and WaveStar C6 in shallow waters (20 m). [ABSTRACT FROM AUTHOR]

This paper presents an optimization model to complete the missing data in the energy matchup matrix which compares different players' energy. The optimization model searched for the solutions that can make the eigenvalue of the energy matrix the biggest that should be the principle one. To test the model, we built a Bayesian matrix of energy matchup which mixes the judgments of energy in a matchup between players given by experts and the statistical data gotten from each game in different positions. The proposed method can complete the probabilities given by the Bayesian matrix. Finally, an implementation shows the effectiveness and rationality of the model. [ABSTRACT FROM AUTHOR]

Accurate evaluations of the available and technically exploitable wave energy resources are fundamental to optimise the design and implementation of energy converters in the marine environment. However, long-term resource assessments have been primarily conducted for large-scale devices in offshore energetic locations, thus ignoring onshore sites such as harbours with easier access, installation and accessibility to devices. Here, we conducted a ten-year evaluation of the performance of wave energy converters (WECs) off Roscoff harbour (northern Brittany, France). As the site of application shows moderately energetic conditions, particular attention was dedicated to small-scale WECs by adapting ratings to the local wave climate. This investigation combined (i) a high-spatial resolution (~5 m) hindcast database established with SWAN with (ii) generic and specific assessments of WEC performance. We exploited, in particular, scaled power matrices derived from the Oyster technology to assess the capacity factors and energy output of devices. In addition to characterising the annual and seasonal variability of the available resource off the harbour breakwater, this investigation provided further insights for optimising WECs, including experimental prototypes. It is therefore suggested that this type of evaluation be considered for the assessment of small- and/or full-scale energy converters in the marine environment. [ABSTRACT FROM AUTHOR]

Let $a, b$ and $n$ be positive integers and $S = \left\{ {x_1, ..., x_n} \right\}$ be a set of $n$ distinct positive integers. The set $S$ is called a divisor chain if there is a permutation $\sigma $ of $\{1, ..., n\}$ such that $x_{\sigma (1)}|...|x_{\sigma (n)}$. We say that the set $S$ consists of two coprime divisor chains if we can partition $S$ as $S=S_1\cup S_2$, where $S_1$ and $S_2$ are divisor chains and each element of $S_1$ is coprime to each element of $S_2$. For any arithmetic function $f$, we define the function $f^a$ for any positive integer $x$ by $f^a(x):=(f(x))^a$. The matrix $(f^a(S))$ is the $n\times n$ matrix having $f^a$ evaluated at the the greatest common divisor of $x_{i}$ and $x_{j}$ as its $(i,j)$-entry and the matrix $(f^a[S])$ is the $n\times n$ matrix having $f^a$ evaluated at the least common multiple of $x_i$ and $x_j$ as its $(i,j)$-entry. In this paper, when $f$ is an integer-valued arithmetic function and $S$ consists of two coprime divisor chains with $1\not\in S$, we establish the divisibility theorems between the determinants of the power matrices $(f^a(S))$ and $(f^b(S))$, between the determinants of the power matrices $(f^a[S])$ and $(f^b[S])$ and between the determinants of the power matrices $(f^a(S))$ and $(f^b[S])$. Our results extend Hong's theorem obtained in 2003 and the theorem of Tan, Lin and Liu gotten in 2011.

Wave energy converters are an important part of future renewable energy infrastructure. Predicting their power matrix, capture width ratio, and power take-off loads at a targeted site is required for performance assessment before deployment. Because their testing is very expensive, numerical modeling and simulations play a significant role in those assessments. Linear potential flow theory has limited accuracy under large amplitude wave forcing. More accurate predictions can be obtained by using higher-fidelity models, which are computationally expensive. We present a framework for multi-fidelity numerical simulations to determine the hydrodynamic response, wave capture capability, and power take-off load of a full-scale dual-flap oscillating surge wave energy converter. This design exploits out-of-phase motion by setting the distance between the flaps to half the wavelength of the most occurring wave. The simulations are validated using a 1:10 model experiments in a wave tank. Based on these validations, it was determined that Euler simulations provide an acceptable prediction with 90% reduction in computational time with only 11% error. Utilizing Euler simulations at full-scale, the results demonstrate that the annual electrical energy output is 1.79 GWh under regular wave conditions. One significant improvement over single-flap designs is the capture width ratio which exceeds unity. [Display omitted] • The hydrodynamic response of a dual-flap OSWEC is investigated. • Experimental testing is used for model validation. • Multi-fidelity simulations of OSWECs are carried out and analyzed. • Power performance of a full-scale dual-flap OSWEC at a targeted site is assessed. [ABSTRACT FROM AUTHOR]

The idea of the proposed image thresholding scheme is simply to consider the histogram as a 2D plot rather than a 1D function. The data can now be represented as a two‐row matrix. The first row is simply the grey levels of the image and the second row is the corresponding histogram values. Multiplying this matrix by its transpose will result in a power‐type matrix of size 2 × 2. The best threshold is the one producing a power matrix closer to that of the original image. Many combinations of the eigenvalues are suggested. To increase the correlation with the first row of the matrix, the histogram is replaced by the cumulative histogram. It is noticed that the trace of the matrix produces the best results. Comparative results show the effectiveness of the proposed schemes. [ABSTRACT FROM AUTHOR]

The present study is focused on assessing the performance of a two-body heaving wave energy converter (WEC) connected to a compressible hydraulic power take-off (PTO) for an approximately 20-year horizon based on the temporal and spatial characteristics of the wave climate at eight selected locations in the Persian Gulf. The variations of the annual, seasonal and monthly mean absorbed, mechanical and electrical power of the selected WEC are presented based on the ERA5 hourly resolution reanalysis wave data set and power matrix of the device. Besides the expected output power, the capture width ratio and the capacity factor are evaluated as well. The hydrodynamic characteristics of the selected WEC are studied in the frequency and time domains. The time-domain modeling relies on the weakly nonlinear potential flow, which considers the instantaneous water surface elevation in water-body interactions to obtain more accurate nonlinear hydrodynamic forces. According to the obtained results in the studied locations, it is concluded that the dominant wave direction is northwest and possible conditions mainly related to events with peak periods between 2.5 and 5 s and significant wave heights up to 1 m. Moreover, based on the overall averaging and from the seasonal view in most locations, the maximum and the minimum mean output power occurs in winter and fall, respectively. The lowest monthly mean output power occurs in August, while the most energetic months are January and February. • Wave power along the eight locations of the Persian Gulf is evaluated. • The hydrodynamic analysis of a heaving two-body WEC connected to a PTO is proposed. • Annual, seasonal, and monthly performance of the considered WEC are investigated. • Output power, capture width ratio and capacity factor are evaluated. [ABSTRACT FROM AUTHOR]

OPV mini-module's power matrix measurements at continuous solar simulator are presented in this study. An detailed analysis of electrical parameters' dependence on temperature and irradiance allowed for the calculation of the temperature coefficients α∊[0.26; 0.31]%/°C for I sc and β∊[−0.11; −0.16]%/°C for V oc. The P max variation with temperature is clearly not linear: P max increases until a certain T (c.a. 35 °C) and then tends to decrease or stabilize. • OPV mini-module's power matrix measurements at continuous solar simulator. • Analysis of electrical parameters' dependence on temperature and irradiance. • Calculated temperature coefficients are α∊[0.26; 0.31]%/°C and β∊[−0.11; −0.16]%/°C. • P max increases until a certain T (c.a. 35 °C) and then tends to decrease or stabilize. The knowledge of electrical current-voltage (I-V) characteristics of photovoltaic (PV) devices under various irradiance, temperature, and spectral conditions is essential for evaluating the output power and energy production of the devices under various climate conditions. The methods to measure the temperature and irradiance dependences of PV devices power are described in the standards IEC 60891 and IEC 61853-1. Newer PV technologies like organic (OPV) and dye-sensitized (DSSC) devices are rapidly evolving and considerable research effort has addressed alternative approaches to increase efficiency with promising values achieved in the last years. Measurements of the irradiance (G) and temperature (T) dependence of these emerging PV technologies are less established –when available– than those of Si-based devices. In this paper we present a first attempt of power-rating measurement for an OPV mini-module. The measurements were performed with a large-area steady-state solar simulator on a reduced (T,G) range compared to what the standard IEC 61853-1 requires. Nevertheless, they were sufficient to calculate the relative temperature coefficients alpha and beta, which have been satisfactorily compared to previous published values. Also, they provided a first data set for the irradiance dependence of OPV device performance. Finally, the power matrix built from these measurements represents at our knowledge the first data set available for energy rating of OPV technology, as the matrix was done for a single device and for both irradiance and temperature dependencies together. [ABSTRACT FROM AUTHOR]

The global pursuit of clean energy resources to cope with escalating energy demands has underscored the pivotal roles of wind and wave power as two prominent renewable energy sources for the power industry. In order to promote the comprehensive harnessing of ocean energy, research efforts have increasingly focused on hybrid approaches, aiming to concurrently capture wind and wave energies. This paper proposes two types of wind-wave hybrid device, which combines wind turbine with a wave energy converter (WEC), based on jacket-frame foundation. The numerical models of the WECs were created using SOLIDWORKS, and the subsequent simulations were conducted using ANSYS Workbench. The comparative analysis revealed that the heave-type WEC had less added mass and radiation damping, coupled with larger response amplitude operator (RAO) and shorter natural period compared to the swinging counterpart. Meanwhile, the swing-type WEC exhibited higher motion speed and greater support reaction force and connecting force, thereby exerting more pronounced influence on the foundation. However, the average hourly power generation of the swinging WEC was significantly better in terms of power capture. In practice, the choice between these WEC configurations should consider aligning the power matrix with the probability distribution of prevailing sea state conditions. • Two types of wind-wave hybrid device integrated into a fixed jacket-frame foundation were proposed. • The numerical models were created using SOLIDWORKS, and simulations were conducted using ANSYS Workbench. • The numerical simulation and generation estimation in specific sea states were comparatively analyzed. • The advantages and disadvantages of the two devices have been analyzed. [ABSTRACT FROM AUTHOR]

A wide range of wave energy converter technologies has been proposed so far. Oscillating body systems are an important class of wave energy converters, which typically harvest wave energy from a single degree-of-freedom response. This article presents a novel 3-degree-of-freedom (heave, pitch and roll) wave energy converter which extracts and converts wave power efficiently. The 3-degree-of-freedom mechanism is invented to absorb and convert wave energy, no matter which direction the waves propagate. The hydraulic power take-off system comprises novel energy conversion devices which can be superposed to realize high-power conversion to produce electricity. First, the power conversion principle of the wave energy converter is proposed, and the kinematics of the 3-degree-of-freedom mechanism is derived. Then, the governing equations of the 3-degree-of-freedom wave energy converter are established. Linear time-domain simulations are performed to calculate instantaneous and mean power outputs. The numerical results show that the rated power absorbed by the wave energy converter is up to 4.2 MW and the efficiency is over 80%. And the power matrix of the wave energy converter is obtained from a range of simulations under different sea states. Finally, directional performance of the wave energy converter is investigated, and the numerical results show that the wave energy converter can operate across a range of incident wave directions, but is most efficient in head, beam and following seas. [ABSTRACT FROM AUTHOR]

Abstract A lift based Cycloidal Wave Energy Converter (CycWEC) was investigated using numerical simulations to estimate its mean annual power absorption. Based on the power absorption as well as size and weight estimates a number of performance measures were derived in order to compare this novel Wave Energy Converter (WEC) to other more established devices for which results have been published by Babarit et al. [1] using a similar benchmarking approach. Comparison of these measures with published data for eight more established WEC designs, including heaving buoy, oscillating water column and flap devices shows that the CycWEC performance in all metrics exceeds that of all other devices. Most importantly, the energy per mass of the CycWEC exceeds that of all other devices by more than an order of magnitude, indicating the potential of the CycWEC to significantly lower the Levelized Cost of Energy (LCoE) and reducing it to a level where the CycWEC can compete with other renewable energy sources like solar and wind. Highlights • Benchmarking of the novel Cycloidal Wave Energy Converter (CycWEC). • The CycWEC performance exceeds that of all other traditional WECs in every metric. • More than an order of magnitude improvement in cost of energy. • The CycWEC is expected to be cost competitive with established renewables like wind. [ABSTRACT FROM AUTHOR]

Abstract This research presents the power performance of the backward-bent duct buoy (BBDB) oscillating water column (OWC) wave energy converters (WECs). To achieve that, following steps are detailed: firstly, power conversion from wave power into pneumatic power by coupling the hydrodynamics and the thermodynamics in the air chamber using a linear air turbine power take-off (PTO), with the calculation of the power response curves for the BBDB OWC device in regular waves; secondly, using the power response curve, a power performance curve is then calculated for irregular waves; thirdly, the power matrices for the device is calculated and the determination of the rated power for the device to meet the target capture factor; and finally, the annual energy production will be assessed as the final indicator for the device's power performance. Using the developed approach, some initial optimisations are made to the original design. It is shown that with some simple optimisations, the BBDB OWC device could increase the annual energy production (AEP) significantly. A simple change in making a uniformed water column for the RM6 device could increase the AEP by about 10%, whilst increasing the horizontal duct length by 10 m could increase the AEP by 58%. Highlights • Formulate the power conversion equation for BBDB oscillating water column wave energy converters. • Perform the analyses of power performance of the BBDB device in both regular and irregular waves. • Optimise the BBDB device for better power performance. • Provide the methodologies for power matrix and rated power for BBDB OWC device. • Compare the annual energy production for different optimisations. [ABSTRACT FROM AUTHOR]

This project involves the management of a network operations center using a web application that simulates the operations of these centers. We analyze the operation and management of the spanish electricity system, what its functions and objectives are highlighting the similarities between the application and the real system. Considering the importance of the power matrix in the electricity system, we explain the power plants available in the application, the types and operation of each production technology is exposed giving special importance the maintenance which directly affects the cost and electricity production. One of the most interesting installations of the application is the high voltage direct current transformer since electricity transport traditionally has been performed in alternating current. Following the study, an increase is seen in the use of renewable sources for generating electricity in recent years. Its participation in the spanish power matrix is almost equal to that of conventional energy sources, although, because many renewable sources depend on weather conditions, they cannot completely replace conventional sources with current technology.

Abstract This work investigates the performance of CECO, a third-generation wave energy converter of the oscillating bodies group. The power matrices of the device – which represent the wave power absorbed for different sea states – are obtained for five PTO inclinations. Then, the wave climate along the west coast of the Iberian Peninsula is characterized by means of the wave energy resource matrices. With the power matrices and the wave energy resource matrices, the performance of the device along the area of study is determined for each PTO inclination. To achieve this, the performance of CECO is assessed by means of a panel model based on the boundary element method, while the wave conditions in the area of study are assessed with a wave propagation spectral model. The results allow fulfilling an important knowledge gap concerning the impact of the PTO inclination on the performance of CECO, which was found to be very significant. In addition, the insight obtained will contribute to optimize future versions of CECO and other wave energy converters of the oscillating body type. Highlights • CECO power matrices are presented for different PTO inclinations. • The performance of CECO in the west coast of the Iberian Peninsula is investigated. • The highest efficiency is reached at the area with the least energetic wave climate. • CECO absorbs the highest amounts of wave energy with 30 and 45° of PTO inclination. • Site-specific values of the rated power and the output energy are presented. [ABSTRACT FROM AUTHOR]

ABSTRACT Esteban, M.D.; López-Gutiérrez, J.S.; Negro, V; Laviña, M., and Muñoz-Sánchez, P., 2018. A New Classification of Wave Energy Converters Used for Selection of Devices. In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 1286–1290. Coconut Creek (Florida), ISSN 0749-0208. Wave is one of the marine renewable energy sources with the greatest potential. Currently, the technology is not completely prepared for a commercial development and its levelized cost of energy (LCOE) is still high. In fact, there are numerous types of wave energy converters (WECs) in the development phase. Given the differences between them, there are several classifications based on different aspects such as the location in relation to the distance to the coast and the bathymetry, the position relative to the sea level, the size and orientation, and the energy capture principle. However, none of the existing classifications considers the operating range at rated power according to the power matrix of the devices. This paper includes a new proposal for classification of WECs, named OPERAWEC (Operation Waver Energy Converters), with the aim of covering that gap. A methodology to implement the classification to different WECs is proposed, and that methodology is applied to ten different existing WECs (Wave Dragon, Pelamis, Aquabuoy, Archimedes Wave Swing, Oyster, Oceantec, OE Buoy, Pontoon, Seabed AB and Wavebob), classifying them into six different groups (Group I, Group II, Group III, Group IV, Group V and Group VI). Most of them belong to the Group IV and/or Group V, and some of them are categorised into several groups. The paper ends showing how to apply OPERAWEC classification as a part of a screening process for WECs selection in the Spanish Atlantic coast. Wave resource is assessed in two specific locations (Estaca de Bares and Golfo de Cádiz), considering four WECs (Pelamis, Aquabuoy, Archimedes Wave Swing, and Oyster). According OPERAWEC classification, Group II WECs for Estaca de Bares, and Group I and Group II WECs for Golfo de Cádiz are recommended. [ABSTRACT FROM AUTHOR]

Wave energy converter power production assessment, usually carried out using a power matrix, is essential for the appraisal of new wave energy converter technologies and for the planning of specific wave energy projects. Errors in power assessment may arise, both from an inaccurate description of the wave energy converter dynamics and from an excessively simplified representation of wave spectra in the power matrix approach. Ideally, the wave energy converter output should be computed in every individual sea state of the wave dataset considered, without the assumption of any parametric spectral shape. However, computationally efficient methods are necessary to achieve such extensive wave energy converter simulation. The non-linear frequency-domain technique is significantly faster than Runge–Kutta time-domain simulations, without affecting the representation of radiation forces and non-linear dynamics. In this article, the two main sources of errors in wave energy converter power assessment, namely the power matrix representation and wave energy converter modelling inaccuracies, are jointly studied and put into perspective, using four case studies (two wave energy converter systems in two locations). It is found that both types of errors can be of comparable magnitude. The non-linear frequency-domain technique simulation technique is shown to be a computationally efficient tool, retaining a realistic representation of the device dynamics while avoiding the use of a power matrix, thus preserving accurate representation of both the sea states and the wave energy converter, at little computational expense. Aside from those main results, the issue of the length and number of simulations, necessary to achieve average power estimates with sufficient accuracy in every sea state, is addressed in detail. [ABSTRACT FROM AUTHOR]

The European Union is a leading patron for the introduction of renewable energy, having set a target that renewable sources will represent at least 27% of total energy consumption by the year 2030. Presently, the most significant Croatian renewable resource is hydropower, which is presently at its peak and will not develop further because of limited hydro resources. Therefore, the share of electricity generation from onshore wind farms in Croatia during in recent years has grown significantly. However, as the Croatian government has already made most of the concessions for possible locations of wind farms, the aim of the present study is to evaluate a different renewable energy resource, wave energy. An assessment of the offshore wave energy potential in the Croatian part of the Adriatic Sea is performed using data taken from WorldWaves atlas (WWA). WWA is based on satellite measurements, validated against buoy measurements and reanalysed by numerical wave modelling. This assessment was done for seven locations, and mean yearly energy is calculated for two offshore wave energy converters. Capacity factors were calculated for annual as well as for seasonal levels, and it was concluded that the bulk of the energy would be generated in autumn and winter. The most probable extreme significant wave height was determined at the investigated locations as well. Furthermore, the offshore wind energy potential was evaluated and compared to the wave energy potential.

We present a study of possible climatic data sets that can be used to perform energy rating calculations on photovoltaic (PV) modules in Europe. We selected five geographic locations across Europe to cover the range of climatic conditions present. In order to assess the validity and significance of such climatic data sets we performed a detailed analysis of the sensitivity of the calculated energy rating to the variability of the input parameters. These are the transmission of the front glass based on the angle of incidence of the irradiance, the spectral response measurement of the PV module, coefficients for calculating module temperature from ambient temperature, and measured power matrices as function of module temperature and irradiance. We found that the calculated energy rating is not sensitive to the first three, but mainly varies due to difference in measured power matrices. This is in particular true for the module performance at low irradiance, and therefore shows a more pronounced difference in climates where such low irradiance conditions occur more frequently, such as in the northern parts of Europe. Nevertheless, the variability found is still less than those between geographic locations. We propose a selection of four energy rating data sets, which differ between them by more than the uncertainty and represent the main climates present across Europe. [ABSTRACT FROM AUTHOR]

This paper presents a study of several factors that affect the long-term performance of Wave energy Converters (WECs) based on the methodology presented in de Andres et al. (2013). This methodology consists of a sea state selection technique (MaxDiss), then this selected sea states are introduced into a numerical model in order to calculate the power performance. Finally this data are interpolated with a non linear technique (Radial Basis functions) in order to obtain the long term performance of a WEC on a long met-ocean data series with low computational requirements. In this paper, three types of converter, a one body heaving converter (follower), a two-body resonant converter as well as a deep water flap are investigated. Also four different locations with different met-ocean conditions in terms of the scatter plots and the sea conditions (swell-wind sea) distribution were selected (North of Spain, West of Denmark, Chile and West of Ireland). The methodology worked perfectly for all the selected alternatives, although it was demonstrated to work better for non-resonant converters that are not band limited in their frequency response. Also, the classical method of power production assessment based on the power matrix was reviewed, analysing the analytical spectrum assumption. The influence of more than one peak spectrum on the power production was found to be large on a sea state by sea state basis (±200%) but also on the Annual Energy Production (±40%). [ABSTRACT FROM AUTHOR]

Let n be a positive integer and let S = { x 1 ,... , x n } be a set of n distinct positive integers. For x ∈ S , one defines G S (x) = { d ∈ S : d < x , d | x and (d | y | x , y ∈ S) ⇒ y ∈ { d , x } }. For any arithmetic function f and any positive integer a , we define power arithmetic function f a by f a (x) = (f (x)) a for any positive integer x. We denote by (f a (S)) and (f a [ S ]) the n × n power matrices having f a evaluated at the greatest common divisor and the least common multiple of x i and x j as its (i , j) -entry, respectively. By | T | we denote the number of elements of any finite set T. In this paper, we show that if S is gcd closed (i.e. gcd ⁡ (x i , x j) ∈ S for all integers i and j with 1 ≤ i , j ≤ n) such that max x ∈ S ⁡ { | G S (x) | } = 1 , then for arbitrary positive integers a and b with a | b , the power matrix (f b (S)) is divisible by the power matrix (f a (S)) if f ∈ C S = { f : (f ⁎ μ) (d) ∈ Z whenever d | lcm (S) } with lcm (S) being the least common multiple of all the elements of S , and the power matrix (f b [ S ]) is divisible by the power matrix (f a (S)) if f ∈ D S = { f ∈ C S : f (x) | f (y) whenever x | y and x , y ∈ S } is multiplicative. Our results extend the theorem of Hong gotten in 2008, that of Li and Tan obtained in 2011 and Zhu's theorem attained recently. [ABSTRACT FROM AUTHOR]

The present work aims to provide a realistic picture of the efficiency along the European continental coasts of ten representative wave energy converters. The main coastal environments targeted are the western sides of Scandinavia, Ireland, UK, Iberian Peninsula and also the Mediterranean and Black seas. In order to evaluate the wave climate corresponding to these coastal areas, several reference points, located at about 50 m water depth, were defined. An analysis of the wave conditions in the target areas has been performed by considering 11-year of hindcast wave data (January 2003–December 2013) provided by the European Centre for Medium-Range Weather Forecasts. At that point, the analysis was focused on the evaluation of the main wave parameters, including the expected average wave power. Thus, for all coastal environments and wave energy converters considered, besides the expected electric power and the capacity factor, some other indicators (as the normalized power) have been also evaluated. The results show that in general the converters with a nominal power greater than 2000 W can generate a significant amount of electricity, compared to the systems rated below 1000 kW, which instead appear to have higher values of the capacity factor, especially during the winter season. [ABSTRACT FROM AUTHOR]

Abstract: In this paper the feasibility of wave energy exploitation off the Italian coasts is investigated. At this aim, the energy production and the performance characteristics of three of the most promising and documented wave energy converters (AquaBuOY, Pelamis and Wave Dragon) are estimated for two of the most energetic Italian locations. The sites are Alghero, on the western coast of Sardinia and Mazara del Vallo, on the Sicily Strait and they have respectively an average annual wave power of 10.3 kW/m and 4 kW/m, and an available annual wave energy of 90 MWh/m and 35 MWh/m. The energy production of the hypothetical wave farms is calculated based on the performance matrices of the wave energy converters (WECs) and on 21 years of wave buoy records, covering the period from 1990 to 2011. The estimated capacity factors are low (between 4% and 9%) compared to the ones obtained for the same wave energy converters in other locations and are affected by a strong seasonal variability. This indicates that the considered WECs are oversized with respect to the local wave climate and that a more efficient energy conversion would be obtained if they were downscaled according to the typical wave height and period of the study sites. As a consequence of the optimization of the device scale, at Alghero the deployment of 1:2.5 AquaBuOY, Pelamis or Wave Dragon devices would result in capacity factors around 20% and in a quite constant energy production throughout the year. In fact, the size reduction of the wave energy converters allows to capture the energy of the small waves which would otherwise be lost with the original WECs. The results of the present work suggest that deploying classic wave energy converters in Italian seas would not be cost effective but if the devices could accommodate a proper downscaling, their performance in energy conversion would become economically attractive also for some Italian locations. [Copyright &y& Elsevier]

The power matrix is the matrix of the coefficients of the power series at 0 of powers of an analytic function. Composition corresponds to matrix multiplication. We generalize the power matrix by replacing power series with Faber polynomial expansions. We show that composition corresponds to multiplication of the generalized power matrices, for both simply and doubly connected domains. We apply this to give some matrix product formulas for the coefficients of conformal welding maps of an analytic homeomorphism of an analytic curve. In particular, in some sense one can solve for the coefficients of the conformal welding maps in terms of the generalized power matrix of the analytic homeomorphism. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study is to estimate the mean annual power absorption of a selection of eight Wave Energy Converters (WECs) with different working principles. Based on these estimates a set of power performance measures that can be related to costs are derived. These are the absorbed energy per characteristic mass [kWh/kg], per characteristic surface area [MWh/m2], and per root mean square of Power Take Off (PTO) force [kWh/N]. The methodology relies on numerical modelling. For each device, a numerical Wave-to-Wire (W2W) model is built based on the equations of motion. Physical effects are modelled according to the state-of-the-art within hydrodynamic modelling practise. Then, the W2W models are used to calculate the power matrices of each device and the mean annual power absorption at five different representative wave sites along the European Coast, at which the mean level of wave power resource ranges between 15 and 88 kW per metre of wave front. Uncertainties are discussed and estimated for each device. Computed power matrices and results for the mean annual power absorption are assembled in a summary sheet per device. Comparisons of the selected devices show that, despite very different working principles and dimensions, power performance measures vary much less than the mean annual power absorption. With the chosen units, these measures are all shown to be of the order of 1. [Copyright &y& Elsevier]

A cylinder that supplements the best vision sphere power appropriately, may improve visual acuity, but this cylinder power can displace the circle of least confusion. A sphere of opposite sign and half the power of the cylinder lens moves the circle back. This added sphere combined with the cylinder is the power of a cross-cylinder lens which, when resolved into independent components called the orthogonal and the oblique antistigmatic components, contains unique, meaningful, calculation-friendly dioptric powers. We calibrate bounds around the antistigmatic coordinates with regular bounds estimated around pure cylinder refractions. The bounds that are then plotted are called profiles of power ranges. The purpose of this article is to determine whether profiles of bounds of the components of antistigmatic lenses, are well-behaved with good foundation with respect to all cylinder axes. Profiles convey the degree of confidence and are key indicators of the quality of the reported powers or calculation. [ABSTRACT FROM AUTHOR]