Optimization of touristic distribution netwoorks using genetic algorithms

The eight basic elements to design genetic algorithms (GA) are described and applied to solve a low demand distribution problem of passengers for a hub airport in Alicante and 30 touristic destinations in Northern Africa and Western Europe. The flexibility of GA and the possibility of creating mutually beneficial feed-back processes with human intelligence to solve complex problems as well as the difficulties in detecting erroneous codes embedded in the software are described. A new three-parent edge mapped recombination operator is used to solve the capacitated vehicle routing problem required for estimating associated costs with touristic distribution networks of low demand. GA proved to be very flexible especially in changing business environments and to solve decision-making problems involving ambiguous and sometimes contradictory constraints.Peer Reviewe

Optimization of touristic distribution netwoorks using genetic algorithms

The eight basic elements to design genetic algorithms (GA) are described and applied to solve a low demand distribution problem of passengers for a hub airport in Alicante and 30 touristic destinations in Northern Africa and Western Europe. The flexibility of GA and the possibility of creating mutually beneficial feed-back processes with human intelligence to solve complex problems as well as the difficulties in detecting erroneous codes embedded in the software are described. A new three-parent edge mapped recombination operator is used to solve the capacitated vehicle routing problem required for estimating associated costs with touristic distribution networks of low demand. GA proved to be very flexible especially in changing business environments and to solve decision-making problems involving ambiguous and sometimes contradictory constraints

A review of the analyses of ocean wave groups

[EN] The most common parameters and functions used to characterize wave groups in linear seas are reviewed and interrelated in a unified manner. A three-axes representation of run lengths is used to characterize wave groups using exponential and Markov chain approximations. A relationship between four parameters (Qp, Qe, ¿2, and ¿2) and the correlation coefficient between consecutive wave heights [rHH(1)] is demonstrated. The wave-height function method is reviewed in some detail in order to relate the run length theory with envelope theories. The theoretical estimates used to demonstrate the relationships between the various parameters must be considered as only first-order trends to parameter estimates computed from real wave data due to the statistical variability in these estimates when computed from real wave data.Medina, JR.; Hudspeth, RT. (1990). A review of the analyses of ocean wave groups. Coastal Engineering. 14(6):515-542. https://doi.org/10.1016/0378-3839(90)90033-SS51554214

Crown Wall Stability of Cube and Cubipod Armored Mound Breakwaters

[EN] Mound breakwaters usually have a concrete crown wall to reduce the amount of quarry material and to improve accessibility. Popular methods to design crown walls consider the same value of the horizontal pressure in the lower edge of the vertical wall and the seaward edge of the crown wall base. Up-lift forces are calculated assuming a triangular pressure distribution with a value given by pressures in the vertical wall. This assumption is reasonable in structures where the foundation level is below the sea water level, but may significantly differ from reality in crown walls with foundation levels above the sea water level. This study focuses on the influence of the foundation level on the crown wall stability analyzing 2D physical tests of cube and Cubipod armored breakwaters with crown wall.The authors acknowledge the financial support of FEDER, Spanish Ministerio de Ciencia, Innovación y Universidades (Grant RTI2018-101073-B-100), SATO (Grupo OHL), Universitat Politècnica de València (Grant SP20180111, Primeros Proyectos de Investigación (PAID-06-18),Vicerrectorado de Investigación, Innovación y Transferencia de la Universitat Politècnica de València) and Generalitat Valenciana (Grant AEST/2019/004)Molines, J.; Medina, JR. (2019). Crown Wall Stability of Cube and Cubipod Armored Mound Breakwaters. Bundesanstalt für Wasserbau. 1-7. https://doi.org/10.18451/978-3-939230-64-9_001S1

Robust AR representations of ocean spectra

[EN] A general criterion to qualify ARMA representations of ocean spectra is presented. An objective criterion to qualify simulators becomes the key element to justify the selection or rejection of ARMA representations for practical applications. A technique to calculate robust AR representations appears to be the natural engineering solution to overpass the instability and poor results provided by classical methods. An addition of modicum white noise (0.0025 m0) to the theoretical JONSWAP-type spectra is proved to be sufficient to generate robust AR representations free of instabilities and showing an excellent qualification according to the general criterion justified for most ocean engineering applications.Medina, JR.; Sánchez Carratalá, CR. (1991). Robust AR representations of ocean spectra. Journal of Engineering Mechanics. 117(12):2926-2930. doi:10.1061/(ASCE)0733-9399(1991)117:12(2926)S292629301171

Estimations of wave forces on crown walls based on wave overtopping rates

[EN] In this study, seven input variables are used to estimate wave forces on the crown wall, and explanatory variables are ranked using neural network techniques. 274 small-scale 2D tests, including both wave overtopping and pressure on crown-wall measurements, were used to calibrate the wave force predictors. Wave overtopping (log Q) was the most relevant variable to estimate horizontal wave forces and overturning moments, while the relative foundation level (F-e/L-0p) was the most relevant variable to estimate wave up-lift forces. The new wave force estimators showed prediction errors slightly higher than the formulas given in the literature, but using fewer parameters and explanatory variables. The range of application of the new formulas is 1.67 < R-c/(gamma(f) H-m0) < 6.55, 1.39 < xi(0p) < 7.77, 0.36 < gamma(f) R-u0.1%/R-c < 1.41, 0.00 < (R-c-A(c))/C-h < 0.59, 2.64 < root L-m/G(c) < 6.54, 0.00 < F-c/ L-0p < 0.03 and -6.00 < logQ < -2.78. Compared to pressure on crown walls, the mean wave overtopping rate is relatively easy to measure in small-scale tests and prototypes. The new estimators of wave forces on the crown wall can be used to indirectly calculate forces on models when only overtopping rates are measured. If wave overtopping is one order of magnitude higher, the wave forces and overturning moments on the crown wall increase between 11% and 60%, considerably reducing the crown wall stability.The authors acknowledge financial support from European FEDER and Spanish Mirtisterio de Economia y Competitividad (Grant BIA2015-70436-R), SATO (OHL Group) and CDTI. The second author was funded through the FPU program (Formacion del Profesorado Universitario, Grant FP2013/01872) by the Spanish Ministerio de Educacion, Culturay Deporte. The authors thank Debra Westall for revising the manuscript.Molines, J.; Herrera Gamboa, MP.; Medina, JR. (2018). Estimations of wave forces on crown walls based on wave overtopping rates. Coastal Engineering. 132:50-62. https://doi.org/10.1016/j.coastaleng.2017.11.004S506213

Distortions associated with random sea simulators

[EN] Some numerical techniques for simulating Gaussian ergodic stochastic sea models are described, analyzed, and contrasted. A general method for generating all numerical, linear, one¿dimensional simulators by wave superposition permits one to describe or create any of these numerical random sea simulators in five steps. The distortions associated with each numerical simulator by wave superposition are analyzed from a general point of view and the arbitrariness of some numerical simulation techniques commonly used is noted. The time¿consumed in these Monte Carlo experiments is an important factor. The numerical algorithms used can change indirectly the level of distortions associated with each numerical simulation technique. A special reference has been made to the use of the fast Fourier transform (FFT) for computing and to the second¿order autoregressive behavior of each wave component in order to reduce the time¿consumed. Three criteria are proposed for qualifying the numerical simulators in order to adapt the requirements of each numerical experiment considered. To explain the variability of random sea, the deterministic amplitude component simulators are rejected while a nondeterministic spectral amplitude simulator (NSA) using a FFT algorithm can be employed.Medina, JR.; Aguilar Herrando, J.; Diez, JJ. (1985). Distortions associated with random sea simulators. Journal of Waterway Port Coastal and Ocean Engineering. 111(4):603-627. doi:10.1061/(ASCE)0733-950X(1985)111:4(603)S603627111

Hydraulic stability of nominal and sacrificial toe berms for mound breakwaters on steep sea bottoms

[EN] When mound breakwaters are placed on steep sea bottoms in combination with very shallow waters, the design of the toe berm becomes a relevant issue. Toe berms built close to the water surface on a steep sea bottom must withstand such high wave loads that their design may not be feasible with available quarrystones. In this study, a new design method was developed to reduce the rock size by increasing the toe berm width. The analysis involved specific 2D small-scale tests with toe berms of different rock sizes and widths, placed on a m = 1/10 bottom slope with the water surface close to the toe berm crest. Two new concepts were introduced to better characterize damage to wide toe berms: (1) the most shoreward toe berm area which effectively supports the armor layer, in this study referred to as the primary or nominal toe berm and (2) the most seaward toe berm area which serves to protect the nominal toe berm, in this study called the secondary or the sacrificial toe berm. Damage to the nominal toe berm was used to describe hydraulic stability of wider toe berms. Given a standard toe berm of three rocks wide (nominal toe berm), an equivalent toe berm with damage similar to the nominal toe berm was defined by increasing the berm width and decreasing the rock size. The reduction in rock size showed an inverse 0.4-power relation with the relative berm width.Herrera Gamboa, MP.; Molines, J.; Medina, JR. (2016). Hydraulic stability of nominal and sacrificial toe berms for mound breakwaters on steep sea bottoms. Coastal Engineering. 114:361-368. https://doi.org/10.1016/j.coastaleng.2016.05.006S36136811

Estimation of incident and reflected waves using simulated annealing

This work was supported through the grants PB94-0534 and MAR98-0339 by the Dirección General de Enseñanza Superior e Investigación Científica y Técnica (Spanish Ministry of Science and Education).Medina Folgado, JR. (2001). Estimation of incident and reflected waves using simulated annealing. Journal of Waterway Port Coastal and Ocean Engineering. 213-221. https://doi.org/10.1061/(ASCE)0733-950X(2001)127:4(213)S21322

Influence of Mild Bottom Slopes on the Overtopping Flow over Mound Breakwaters under Depth-Limited Breaking Wave Conditions

[EN] The crest elevation of mound breakwaters is usually designed considering a tolerable mean wave overtopping discharge. However, pedestrian safety, characterized by the overtopping layer thickness (OLT) and the overtopping flow velocity (OFV), is becoming more relevant due to the reduction of the crest freeboards of coastal structures. Studies in the literature focusing on OLT and OFV do not consider the bottom slope effect, even if it has a remarkable impact on mound breakwater design under depth-limited breaking wave conditions. Therefore, this research focuses on the influence of the bottom slope on OLT and OFV exceeded by 2% of incoming waves, hc,2% and uc,2%. A total of 235 2D physical tests were conducted on conventional mound breakwaters with a single-layer Cubipod® and double-layer rock and cube armors with 2% and 4% bottom slopes. Neural networks were used to determine the optimum point to estimate wave characteristics for hc,2% and uc,2% calculation; that point was located at a distance from the model toe of three times the water depth at the toe (hs) of the structure. The influence of the bottom slope is studied using trained neural networks with fixed wave conditions in the wave generation zone; hc,2% slightly decreases and uc,2% increases as the gradient of the bottom slope increases.This research was funded by Ministerio de Economia y Competitividad and the Fondo Europeo de Desarrollo Regional (FEDER) under grant BIA2015-70436-R and RTI2018-101073-B-I00. The first author was also financially supported by the Ministerio de Educacion, Cultura y Deporte through the FPU program (Formacion de Profesorado Universitario) under grant FPU16/05081.Mares-Nasarre, P.; Gómez-Martín, ME.; Medina, JR. (2020). Influence of Mild Bottom Slopes on the Overtopping Flow over Mound Breakwaters under Depth-Limited Breaking Wave Conditions. Journal of Marine Science and Engineering. 8(1):1-16. https://doi.org/10.3390/jmse8010003S11681www.overtopping-manual.comMolines, J., & Medina, J. R. (2016). Explicit Wave-Overtopping Formula for Mound Breakwaters with Crown Walls Using CLASH Neural Network–Derived Data. Journal of Waterway, Port, Coastal, and Ocean Engineering, 142(3), 04015024. doi:10.1061/(asce)ww.1943-5460.0000322Nørgaard, J. Q. H., Lykke Andersen, T., & Burcharth, H. F. (2014). Distribution of individual wave overtopping volumes in shallow water wave conditions. Coastal Engineering, 83, 15-23. doi:10.1016/j.coastaleng.2013.09.003Molines, J., Herrera, M. P., Gómez-Martín, M. E., & Medina, J. R. (2019). Distribution of individual wave overtopping volumes on mound breakwaters. Coastal Engineering, 149, 15-27. doi:10.1016/j.coastaleng.2019.03.006Mares-Nasarre, P., Argente, G., Gómez-Martín, M. E., & Medina, J. R. (2019). Overtopping layer thickness and overtopping flow velocity on mound breakwaters. Coastal Engineering, 154, 103561. doi:10.1016/j.coastaleng.2019.103561Herrera, M. P., Gómez-Martín, M. E., & Medina, J. R. (2017). Hydraulic stability of rock armors in breaking wave conditions. Coastal Engineering, 127, 55-67. doi:10.1016/j.coastaleng.2017.06.010Van Gent, M. R. A. (2003). WAVE OVERTOPPING EVENTS AT DIKES. Coastal Engineering 2002. doi:10.1142/9789812791306_0185Schüttrumpf, H., Möller, J., & Oumeraci, H. (2003). OVERTOPPING FLOW PARAMETERS ON THE INNER SLOPE OF SEADIKES. Coastal Engineering 2002. doi:10.1142/9789812791306_0178Gent, M. R. A. van. (2001). Wave Runup on Dikes with Shallow Foreshores. Journal of Waterway, Port, Coastal, and Ocean Engineering, 127(5), 254-262. doi:10.1061/(asce)0733-950x(2001)127:5(254)Van der Meer, J. W., Hardeman, B., Steendam, G. J., Schuttrumpf, H., & Verheij, H. (2011). FLOW DEPTHS AND VELOCITIES AT CREST AND LANDWARD SLOPE OF A DIKE, IN THEORY AND WITH THE WAVE OVERTOPPING SIMULATOR. Coastal Engineering Proceedings, 1(32), 10. doi:10.9753/icce.v32.structures.10Lorke, S., Scheres, B., Schüttrumpf, H., Bornschein, A., & Pohl, R. (2012). PHYSICAL MODEL TESTS ON WAVE OVERTOPPING AND FLOW PROCESSES ON DIKE CRESTS INFLUENCED BY WAVE-CURRENT INTERACTION. Coastal Engineering Proceedings, 1(33), 34. doi:10.9753/icce.v33.waves.34Herrera, M. P., & Medina, J. R. (2015). Toe berm design for very shallow waters on steep sea bottoms. Coastal Engineering, 103, 67-77. doi:10.1016/j.coastaleng.2015.06.005Gómez-Martín, M. E., & Medina, J. R. (2014). Heterogeneous Packing and Hydraulic Stability of Cube and Cubipod Armor Units. Journal of Waterway, Port, Coastal, and Ocean Engineering, 140(1), 100-108. doi:10.1061/(asce)ww.1943-5460.0000223Argente, G., Gómez-Martín, M., & Medina, J. (2018). Hydraulic Stability of the Armor Layer of Overtopped Breakwaters. Journal of Marine Science and Engineering, 6(4), 143. doi:10.3390/jmse6040143Gómez-Martín, M., Herrera, M., Gonzalez-Escriva, J., & Medina, J. (2018). Cubipod® Armor Design in Depth-Limited Regular Wave-Breaking Conditions. Journal of Marine Science and Engineering, 6(4), 150. doi:10.3390/jmse6040150Battjes, J. A., & Groenendijk, H. W. (2000). Wave height distributions on shallow foreshores. Coastal Engineering, 40(3), 161-182. doi:10.1016/s0378-3839(00)00007-7Victor, L., van der Meer, J. W., & Troch, P. (2012). Probability distribution of individual wave overtopping volumes for smooth impermeable steep slopes with low crest freeboards. Coastal Engineering, 64, 87-101. doi:10.1016/j.coastaleng.2012.01.003Verhagen, H. J., van Vledder, G., & Arab, S. E. (2009). A PRACTICAL METHOD FOR DESIGN OF COASTAL STRUCTURES IN SHALLOW WATER. Coastal Engineering 2008. doi:10.1142/9789814277426_0241Van Gent, M. R. A., van den Boogaard, H. F. P., Pozueta, B., & Medina, J. R. (2007). Neural network modelling of wave overtopping at coastal structures. Coastal Engineering, 54(8), 586-593. doi:10.1016/j.coastaleng.2006.12.001Molines, J., Herrera, M. P., & Medina, J. R. (2018). Estimations of wave forces on crown walls based on wave overtopping rates. Coastal Engineering, 132, 50-62. doi:10.1016/j.coastaleng.2017.11.00