scholarly journals THE STRUCTURAL BEHAVIOUR AND THE SHELTERING EFFICIENCY OF THE SUBMERGED BREAKWATER AT THE ENTRANCE TO THE PORT OF LEIXOES MAINTENANCE CHARGES AND EFFECTS

1964 ◽  
Vol 1 (9) ◽  
pp. 38
Author(s):  
Duarte Abecasis
Keyword(s):  
Vertical Wall ◽  
Structural Behaviour ◽  
Sandy Bottom ◽  
Submerged Breakwater ◽  
Rocky Bottom ◽  
Model Study ◽  
Concrete Blocks ◽  
New Type ◽  
The Cost ◽  
Conventional Type

The urgent necessity for providing a system of protective works of the harbour of Leixoes with complementary works to improve the poor con ditions of the shelter in the basin and to protect ships entering the port became evident in 193^* In fact, the frequency of disaster to trawlers and to other ships within the basin during southwestern gales as well as the very dangerous conditions at the entrance under such gales were incompatible with the increasing economic importance of Oporto and its hinterland. These bad conditions culminated in the foundering of the 9000 T Dutch steamship "Orania" at anchor in the basin colliding on the 19th December 193^ with the steamship "Luanda" when entering the harbour under severe hurricane. The construction of the 1000 m long new breakwater was started wit a 15 m wide vertical wall to be set partly on rocky bottom and partly o a sandy bottom. Before leaving the rocky bottom the upper part of the wall was destroyed by a strong gale (Fig. l). For the advancement of t work the contractor and an official commission recommended the adoption of the Casablanca type of slope work. For economical reasons and on those of the sure possibility of its conversion into a conventional type of work, would it become convenient it was decided, at the author's suggestion, and after model study at Lausanne School of Engineer's Laboratory, to adopt a new type of submerged work, to replace the unsuccessful vertical type or the type of Casablanca proposed by the contractor (Fig. 2). The section adopted coi prised a rubble mound core of stones to 1• with the crest at level (-9m00), and berms of rubble to kF, 12 m wide to the sea side and 10 m wide to the port side (Fig. l). T The top and slopes of the mound were protected by an armour of 90 concrete blocks with the corners cut for best accommodation. The cost of the work could be reduced to half of that corresponding to the last of these types of breakwaters and its maintenance charge greatly reducec The estimated cost of the works would be reduced from JL 1.770.000 to £. 880.000 and the maintenance charges foreseen reduced from £ 35*^00 yearly to £ 2.800 yearly (comparison with the Casablanca type).

Sorting permutations by fragmentation-weighted operations

2020 ◽  
Vol 18 (02) ◽  
pp. 2050006 ◽  
Author(s):  
Alexsandro Oliveira Alexandrino ◽  
Carla Negri Lintzmayer ◽  
Zanoni Dias
Keyword(s):  
Approximation Algorithms ◽  
Computational Biology ◽  
Cost Function ◽  
Traditional Approach ◽  
Upper Bounds ◽  
Evolutionary Distance ◽  
Lower And Upper Bounds ◽  
Approximation Factor ◽  
New Type ◽  
The Cost

One of the main problems in Computational Biology is to find the evolutionary distance among species. In most approaches, such distance only involves rearrangements, which are mutations that alter large pieces of the species’ genome. When we represent genomes as permutations, the problem of transforming one genome into another is equivalent to the problem of Sorting Permutations by Rearrangement Operations. The traditional approach is to consider that any rearrangement has the same probability to happen, and so, the goal is to find a minimum sequence of operations which sorts the permutation. However, studies have shown that some rearrangements are more likely to happen than others, and so a weighted approach is more realistic. In a weighted approach, the goal is to find a sequence which sorts the permutations, such that the cost of that sequence is minimum. This work introduces a new type of cost function, which is related to the amount of fragmentation caused by a rearrangement. We present some results about the lower and upper bounds for the fragmentation-weighted problems and the relation between the unweighted and the fragmentation-weighted approach. Our main results are 2-approximation algorithms for five versions of this problem involving reversals and transpositions. We also give bounds for the diameters concerning these problems and provide an improved approximation factor for simple permutations considering transpositions.

scholarly journals Study on behaviors of wave-dissipating concrete blocks of submerged breakwater around the Fukui Port using GPS

2008 ◽  
Vol 55 ◽  
pp. 966-969
Author(s):  
Hiroshi YOSHINAGA ◽  
Yoshiyuki OOSHITA ◽  
Tadashi WATANABE ◽  
Yasutaka TAKAMOTO ◽  
Takemitsu TAKANO
Keyword(s):  
Submerged Breakwater ◽  
Concrete Blocks

scholarly journals Slit-type Breakwater; Box-type Wave Absorber

1976 ◽  
Vol 1 (15) ◽  
pp. 154 ◽  
Author(s):  
Shoshichiro Nagai ◽  
Shohachi Kakuno
Keyword(s):  
Cross Section ◽  
Water Depth ◽  
Vertical Wall ◽  
Bottom Wall ◽  
Front Wall ◽  
Type Wave ◽  
Composite Type ◽  
New Type ◽  
Vertical Walls ◽  
Horizontal Bottom

A box-type wave absorber, which is composed of a perforated vertical front-wall and a perforated, horizontal bottom-wall, has been proved by a number of experiments to show lower coefficients of reflection and more distinguished reduction of wave pressures than the perforated vertical- wall breakwater. A breakwater of composite-type, which is 1500 m long and to be built at a water depth of 10 to 11 m below the Datum Line in the Port of Osaka, is being designed to set this new type of wave absorber in the concrete caissons of the vertical-walls which is named "a slit-type breakwater". The typical cross-section of the breakwater and the advantages of the slit-type breakwater are presented herein.

scholarly journals APPLICATION OF SMOOTHED PARTICLE HYDRODYNAMICS IN EVALUATING THE PERFORMANCE OF COASTAL RETROFIT STRUCTURES

2018 ◽  
pp. 109 ◽  
Author(s):  
Soroush Abolfathi ◽  
Dong Shudi ◽  
Sina Borzooei ◽  
Abbas Yeganeh-Bakhtiari ◽  
Jonathan Pearson
Keyword(s):  
Numerical Model ◽  
Smoothed Particle Hydrodynamics ◽  
Vertical Wall ◽  
Laboratory Data ◽  
Wave Structure ◽  
Base Case ◽  
Submerged Breakwater ◽  
Wave Overtopping ◽  
Particle Hydrodynamics ◽  
Smoothed Particle

This study develops an accurate numerical tool for investigating optimal retrofit configurations in order to minimize wave overtopping from a vertical seawall due to extreme climatic events and under changing climate. A weakly compressible smoothed particle hydrodynamics (WCSPH) model is developed to simulate the wave-structure interactions for coastal retrofit structures in front of a vertical seawall. A range of possible physical configurations of coastal retrofits including re-curve wall and submerged breakwater are modelled with the numerical model to understand their performance under different wave and structural conditions. The numerical model is successfully validated against laboratory data collected in 2D wave flume at Warwick Water Laboratory. The findings of numerical modelling are in good agreement with the laboratory data. The results indicate that recurve wall is more effective in mitigating wave overtopping and provides more resilience to coastal flooding in comparison to base-case (plain vertical wall) and submerged breakwater retrofit.

scholarly journals Physical model study of bedrock scour downstream of dams due to spillway plunging jets

2020 ◽  
Vol 62 (3) ◽  
Author(s):  
A Bosman ◽  
G R Basson
Keyword(s):  
Physical Model ◽  
Linear Regression Analysis ◽  
Scour Depth ◽  
Model Study ◽  
Fissured Rock ◽  
Scour Hole ◽  
Plunging Jets ◽  
Concrete Blocks ◽  
Rock Bed ◽  
Equilibrium Scour Depth

The erosive power of a free-falling high-velocity water jet, flowing from a dam spillway, could create a scour hole downstream of the dam, endangering the foundation of the dam. Despite extensive research since the 1950s, there is presently no universally agreed method to predict accurately the equilibrium scour depth caused by plunging jets at dams. These formulae yield a large range of equilibrium scour dimensions. The hydrodynamics of plunging jets and the subsequent scour of a rectangular, horizontal and vertical fissured rock bed were investigated in this study by means of a physical model. Equilibrium scour hole geometries for different fissured dimensions (simulated with rectangular concrete blocks tightly prepacked in a regular rectangular matrix), for a range of flow rates, plunge pool depths, and dam height scenarios were experimentally established with 31 model tests. From the results, non-dimensional formulae for the scour hole geometry were developed using multi-linear regression analysis. The scour depth results from this study were compared to various analytical methods found in literature. The equilibrium scour hole depth established in this study best agrees with that predicted by the Critical Pressure method.

scholarly journals Coastal protection work for Batu Mejan Beach, Bali

2019 ◽  
Vol 276 ◽  
pp. 04019
Author(s):  
Pujianiki Ni Nyoman ◽  
Astawa Diputra I Gede ◽  
Jayantari Made W ◽  
Mataram INK
Keyword(s):  
Wave Energy ◽  
Protective Layer ◽  
Minimum Cost ◽  
Public Works ◽  
Coastal Protection ◽  
Submerged Breakwater ◽  
The Public ◽  
International Tourist ◽  
Tourism Destinations ◽  
The Cost

Batu Mejan Beach is an international tourist destination located in the Canggu area of Badung regency, Bali. Due to erosion problems of Batu Mejan Beach the local government installed a revetment system to protect the coast. However, the revetment that was built before for the Batu Mejan Beach is currently ineffective and damaged. To determine the parameters for the construction of a new coastal protection system, the wave energy occurring at the site was evaluated initially as part of this study. A Submerged breakwater with a tetrapod for a protective layer was then chosen as the alternative to reduce the wave energy before reaching the shore and to reduce erosion as well as further deterioration of the existing revetment. A Submerged breakwater is suitable in coastal areas that are used as tourism destinations because the submerged breakwater construction is under the water, therefore the beauty of the beach will not be interrupted. Four models were made with variations in the width and elevation of the breakwater peak. The model was selected which has the minimum value of transmission coefficient and minimum cost. The cost budget plan was determined by using the analytical list of the Public Works and Housing Regulations of 2016. From the analysis, a model was selected with a submerged breakwater height of 2.45 m, length of 110 m, distance gap of 55 m, and the budget of IDR 17,861,989,813.

Field Investigations on Wave-Dissipating Concrete Blocks Covering Vertical Wall Breakwater

1997 ◽  
Author(s):  
Michio Gomyoh ◽  
Kazuhiko Sakai ◽  
Tomotuka Takayama ◽  
Kojiro Suzuki ◽  
Shigeo Takahashi
Keyword(s):  
Vertical Wall ◽  
Field Investigations ◽  
Concrete Blocks

scholarly journals Personalised Formwork – scientific approach for new solution variants

2019 ◽  
Vol 290 ◽  
pp. 04005
Author(s):  
Raluca Diaconu ◽  
Paul Dan Brindasu
Keyword(s):  
Elastic Material ◽  
Experimental Tests ◽  
Low Resistance ◽  
Synthetic Rubber ◽  
Material Cost ◽  
Creative Methods ◽  
Scientific Approach ◽  
New Type ◽  
The Cost

Application of personalised formwork is of most interest for architects and engineers now-a-days. Although a required demand when designing special constructions, there is little data and material solutions for this case. The cost and domain of application are of most importance in determining new solutions for concrete formworks. To contribute to these requests (a wider usage domain, productive material cost and maintenance), a personalised formwork concept is presented. The idea of reusing the formwork led to an elastic material – membrane (thermoset elastomers, synthetic rubber) with a punching tie-rod solution in order to obtain any architectural shape desired. This first solution was evaluated taking into account different membrane thicknesses. Several experimental tests denoted that the named chosen membrane variants are of low resistance for pouring a concrete architectural slab, so new solutions were discussed. Hence, a re-analysis of the PLM steps was achieved in order to find an answer for the encountered problem. By using creative methods, we obtained a second solution and put it to test. The attained results are used in order to establish the area of workability, to enlarge the tested domain and to assess the sustainability of a new type of personalised formwork

Investigation of Effects of Baffle Configuration on the Performance of a Fixed-Cone Valve by Gas-Liquid Two-Phase Model

2012 ◽  
Vol 166-169 ◽  
pp. 1824-1829
Author(s):  
W.L. Wei ◽  
B. Lv ◽  
Y.L. Liu ◽  
X.F. Yang
Keyword(s):  
Numerical Simulation ◽  
Energy Dissipation ◽  
Turbulent Flow ◽  
Average Velocity ◽  
Simulation Method ◽  
Velocity Fields ◽  
Two Phase ◽  
Pressure Fields ◽  
New Type ◽  
Conventional Type

Nested type Fixed-Cone Valve, numerical simulation, energy dissipating, turbulent flow Abstract: In this paper, In this paper, a new type of Fixed-Cone Valve was proposed by improving the conventional type Fixed-Cone Valve .The flow fields of the two kinds of Fixed-Cone Valves were studied by using numerical simulation method .The computed pressure fields and the velocity fields were analyzed ,which shows that under the same conditions ,and by using the nested Fixed-Cone valve, the pressure of the upstream pipe and the cone valve and the average velocity along the downstream pipeline are reduced ,but the rate of energy dissipation is increased.

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