scholarly journals Gravity-Based Foundations in the Offshore Wind Sector

2019 ◽  
Vol 7 (3) ◽  
pp. 64 ◽  
Author(s):  
M. Esteban ◽  
José-Santos López-Gutiérrez ◽  
Vicente Negro
Keyword(s):  
Water Depth ◽  
High Water ◽  
Offshore Wind ◽  
Is Research ◽  
Current State ◽  
Different Types ◽  
Large Water ◽  
Water Depths ◽  
Offshore Wind Industry

In recent years, the offshore wind industry has seen an important boost that is expected to continue in the coming years. In order for the offshore wind industry to achieve adequate development, it is essential to solve some existing uncertainties, some of which relate to foundations. These foundations are important for this type of project. As foundations represent approximately 35% of the total cost of an offshore wind project, it is essential that they receive special attention. There are different types of foundations that are used in the offshore wind industry. The most common types are steel monopiles, gravity-based structures (GBS), tripods, and jackets. However, there are some other types, such as suction caissons, tripiles, etc. For high water depths, the alternative to the previously mentioned foundations is the use of floating supports. Some offshore wind installations currently in operation have GBS-type foundations (also known as GBF: Gravity-based foundation). Although this typology has not been widely used until now, there is research that has highlighted its advantages over other types of foundation for both small and large water depth sites. There are no doubts over the importance of GBS. In fact, the offshore wind industry is trying to introduce improvements so as to turn GBF into a competitive foundation alternative, suitable for the widest ranges of water depth. The present article deals with GBS foundations. The article begins with the current state of the field, including not only the concepts of GBS constructed so far, but also other concepts that are in a less mature state of development. Furthermore, we also present a classification of this type of structure based on the GBS of offshore wind facilities that are currently in operation, as well as some reflections on future GBS alternatives.

scholarly journals Customer Segmentation Through Path Reconstruction

2020 ◽  
Author(s):  
Santiago García
Keyword(s):  
Rapid Development ◽  
Customer Segmentation ◽  
Smart Phones ◽  
Indoor Environments ◽  
Flow Conditions ◽  
Gps Receivers ◽  
Current State ◽  
Different Types

With the rapid development of smart phones, tablets and their operative systems, many positioning enabled sensors have been built into these devices. Users can now accurately fix their location according to the function of GPS receivers. For indoor environments, as in the case we are studying, WiFi based positioning is preferred to GPS due to the attenuation or obstruction of signals. This paper deals with the automatic classification of customers in a Sports Shop Center on the basis of their movements around the shop's premises. To achieve this goal, we start by collecting (x,y) coordinates from customers while they visit the store. Consequently, any costumer's path through the shop is formed by a list of coordinates, obtained with a frequency of one measurement per minute. Then, a guess about the full trajectory is constructed and a number of parameters about these trajectories is calculated before performing an Unsupervised Learning Clustering Process. As a result, we can identify several types of customers, and the dynamics of their behavior inside the shop. This information is of great value to the company, to be used both in the long term and also in short periods of time, monitoring the current state of the shop at any moment, identifying different types of situation appearing during restricted periods, or predicting customer flow conditions

Steel Jackets and Monotower Foundations for Offshore Wind Turbines

2012 ◽  
Author(s):  
Kasper Wåsjø ◽  
Morten Bjerkås ◽  
Tore Søreide
Keyword(s):  
Cost Benefit ◽  
Offshore Wind ◽  
Support Structures ◽  
Base Shear ◽  
Offshore Wind Turbines ◽  
Steel Jacket ◽  
Important Benefit ◽  
Comparable Magnitude ◽  
Water Depths ◽  
Offshore Wind Industry

Steel jacket support structures for offshore wind have an increasing popularity for water depths larger than 20 m. Traditionally, support structures such as monopiles and gravity based foundation have dominated at shallow water. Offshore wind industry deals gradually with larger water depths, and light weight foundations as steel jackets are believed to give a cost benefit. The present study shows that the quasi static overturning moment for monotower structures and steel jackets are of comparable magnitude. It is also shown that the most important benefit of steel jackets as support structures is to reduce the base shear. At last it is shown that foundation size is primarily driven by wave and current loads at water depth around 50–60 m.

Influence of Mooring Lines and Risers on the Trim, Heel and Displacement on FPUs

2015 ◽  
Author(s):  
Cecília Coelho ◽  
Bruna Nabuco
Keyword(s):  
Water Depth ◽  
Mooring System ◽  
Mooring Lines ◽  
Different Types ◽  
Zero Degree ◽  
Displacement Based ◽  
System Configurations ◽  
And Behavior ◽  
Seabed Bathymetry ◽  
Water Depths

By monitoring the variation of weights of floating production units (FPUs), the sum of total weight computed by load calculators on board very often does not match the actual displacement based on the current drafts. Differences can also be observed in the trim and heel of FPUs, which present values different from zero degree in the calculations, but in fact they are frequently kept near zero by ballast control. The mooring lines and risers tensions are one of the most uncertain weight items in loading conditions reported by the crew on board, therefore, this paper aims to assess the influence and behavior of these systems to a variety of situations in which FPUs operate. Analyses were performed for semi-submersibles and FPSOs considering two configurations of mooring system: catenary and taut-leg. The purpose is to evaluate how the magnitude of the resulting force varies — and hence how the trim and heel change — for a range of offsets caused by environmental conditions. The effect of mooring lines and risers is also discussed regarding the water depth by means of case studies considering a range of water depths. Actual lines properties and seabed bathymetry from mooring system models of platforms located offshore Brazil have been taken as reference. In short, the mooring lines and risers loads will be calculated for different types of floating production units, mooring system configurations and water depths in order to evaluate their influence on the trim, heel and displacement of FPUs.

scholarly journals Automatic Classification of Gait Impairments Using a Markerless 2D Video-Based System

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 2743 ◽  
Author(s):  
Tanmay Verlekar ◽  
Luís Soares ◽  
Paulo Correia
Keyword(s):  
Stance Phase ◽  
Video Camera ◽  
Step Length ◽  
Support Vector ◽  
Current State ◽  
Gait Features ◽  
Different Types ◽  
Length Step ◽  
Gait Impairments

Systemic disorders affecting an individual can cause gait impairments. Successful acquisition and evaluation of features representing such impairments make it possible to estimate the severity of those disorders, which is important information for monitoring patients’ health evolution. However, current state-of-the-art systems perform the acquisition and evaluation of these features in specially equipped laboratories, typically limiting the periodicity of evaluations. With the objective of making health monitoring easier and more accessible, this paper presents a system that performs automatic detection and classification of gait impairments, based on the acquisition and evaluation of biomechanical gait features using a single 2D video camera. The system relies on two different types of features to perform classification: (i) feet-related features, such as step length, step length symmetry, fraction of foot flat during stance phase, normalized step count, speed; and (ii) body-related features, such as the amount of movement while walking, center of gravity shifts and torso orientation. The proposed system uses a support vector machine to decide whether the observed gait is normal or if it belongs to one of three different impaired gait groups. Results show that the proposed system outperforms existing markerless 2D video-based systems, with a classification accuracy of 98.8%.

Comparative Study of Spar-Type Wind Turbines in Deep and Moderate Water Depths

2012 ◽  
Author(s):  
Madjid Karimirad ◽  
Torgeir Moan
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Water Depth ◽  
Deep Water ◽  
Offshore Wind ◽  
Hydrodynamic Performance ◽  
Offshore Wind Turbine ◽  
Spar Platforms ◽  
Water Depths ◽  
Coupled Wave

This paper compares the dynamic responses and performance of two spar-type wind turbines, DeepSpar and ShortSpar, in deep and intermediate water depths, respectively. The oil and gas industry has implemented spar platforms in deep water areas. Spar platforms show good hydrodynamic performance due to their deep draft. The same idea is applied to offshore wind turbines to present a reliable concept. Hywind is an example of a successful offshore wind turbine based on the spar concept in deep water. The good performance of spar-type wind turbines motivates us to study the feasibility of using these turbines in moderate water depth. Spar-type 5-MW wind turbines in deep and moderate water depths are compared. The power performance, dynamic motions, tension responses, accelerations, structural shear forces and bending moments are studied. Simo/Riflex/TDHMILL3D is used to perform the coupled wave- and wind-induced analyses. Simo/Riflex, developed by MARINTEK, is a commercial tool for analyzing the coupled wave-induced responses of moored offshore structures. TDHMILL3D, is an external DLL that accounts for spar motions while calculating the aerodynamic thrust at each time step using the turbine characteristics and relative velocities. Different environmental conditions are used to compare the responses. The results show that spar-type wind turbine in the moderate water depth exhibits good performance and that its responses are reasonable compared to those of spar-type wind turbine in deep water. This finding indicates the feasibility of implementing the same rotor-nacelle assembly for both concepts. The total mass (the structural mass plus the ballast) of the ShortSpar is 35% less than that of the DeepSpar, while the statistical characteristics of the power generated are almost the same. The reduced mass of the ShortSpar helps to achieve a more cost-effective solution for floating wind turbines in moderate water depth.

Global Sizing of the WindFloat for a 10 MW Generic Wind Turbine

2018 ◽  
Author(s):  
Daewoong Son ◽  
Romain Pinguet ◽  
Dominique Roddier
Keyword(s):  
Wind Turbine ◽  
Economies Of Scale ◽  
Offshore Wind ◽  
Depth Range ◽  
Offshore Wind Turbines ◽  
Levelized Cost ◽  
Cost Of Energy ◽  
Global Performance ◽  
Large Water ◽  
Offshore Wind Industry

It is now widely accepted that, due to significant economies of scale, the levelized cost of energy in offshore wind industry decreases as the turbine size and rated power increases. For offshore wind turbines, fixed and floating foundations can be quite complimentary when sites span a large water depth range. This paper presents the new WindFloat semisubmersible design supporting a 10MW generic wind turbine made by DTU [1]. This study evaluates the initial global performance of the WindFloat 10MW hull. In addition, RAO and frequency domain accelerations at the nacelle are presented. A comparison of the OpenFAST model, that we plan to use in all the future analysis, will be conducted against the benchmarked OrcaFAST model used by PPI and validated against the WindFloat prototype [2].

Dual stain kit for the microscopic gram classification of ocular infection bacteria

1993 ◽  
Vol 51 ◽  
pp. 248-249
Author(s):  
Jacob S. Hanker ◽  
Dale N. Holdren ◽  
Kenneth L. Cohen ◽  
Beverly L. Giammara
Keyword(s):  
Contact Lenses ◽  
Ocular Infection ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Gram Staining ◽  
Ocular Infections ◽  
Different Types ◽  
Culture Positive ◽  
Increased Susceptibility

Keratitis and conjunctivitis (infections of the cornea or conjunctiva) are ocular infections caused by various bacteria, fungi, viruses or parasites; bacteria, however, are usually prominent. Systemic conditions such as alcoholism, diabetes, debilitating disease, AIDS and immunosuppressive therapy can lead to increased susceptibility but trauma and contact lens use are very important factors. Gram-negative bacteria are most frequently cultured in these situations and Pseudomonas aeruginosa is most usually isolated from culture-positive ulcers of patients using contact lenses. Smears for staining can be obtained with a special swab or spatula and Gram staining frequently guides choice of a therapeutic rinse prior to the report of the culture results upon which specific antibiotic therapy is based. In some cases staining of the direct smear may be diagnostic in situations where the culture will not grow. In these cases different types of stains occasionally assist in guiding therapy.

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