scholarly journals Three-Dimensional Imaging of the High Sea-State Wave Field Encompassing Ship Slamming Events

2010 ◽  
Vol 27 (4) ◽  
pp. 737-752 ◽  
Author(s):  
A. Brandt ◽  
J. L. Mann ◽  
S. E. Rennie ◽  
A. P. Herzog ◽  
T. B. Criss
Keyword(s):  
Wave Field ◽  
Imaging System ◽  
Three Dimensional ◽  
Sea State ◽  
Incoming Wave ◽  
Ship Slamming ◽  
Wave Slamming ◽  
Wave Heights ◽  
Surface Wave Field ◽  
The Individual

Abstract Understanding and modeling ship wave slamming necessitates characterizing the surface wave field that results in slamming events. Shipboard measurements of the incoming wave field were made during sea trials of the twin-hull Sea Fighter (FSF-1), using a three-dimensional (3D), stereo-optic imaging system. The data obtained were processed using an image matching algorithm resulting in 3D video sequences of the incoming wave field at forward speeds of 16–40 kt in head seas at sea state 4. Six wave slamming events were captured, characterized, and compared to the average wave field properties. It was found that the salient properties of the individual waves that resulted in ship slamming occurred in groups of two or more, were approximately 30% larger than the significant wave heights during the ∼2-min period encompassing the slamming events, and had wave slopes at least 2 times that of the preceding wave slope. Additionally, wave slamming corresponded to large ship pitching motions resulting from the incident waveforms.

Numerical Research on FPSOs With Green Water Occurrence

2009 ◽  
Vol 53 (01) ◽  
pp. 7-18
Author(s):  
Renchuan Zhu ◽  
Guoping Miao ◽  
Zhaowei Lin
Keyword(s):  
Three Dimensional ◽  
Green Water ◽  
Floating Body ◽  
Incoming Wave ◽  
Model Case ◽  
Floating Structures ◽  
Design And Optimization ◽  
Head Waves ◽  
Wave Heights ◽  
The Impact

Green water loads on sailing ships or floating structures occur when an incoming wave significantly exceeds freeboard and water runs onto the deck. In this paper, numerical programs developed based on the platform of the commercial software Fluent were used to numerically model green water occurrence on floating structures exposed to waves. The phenomena of the fixed floating production, storage, and offloading unit (FPSO) model and oscillating vessels in head waves have been simulated and analyzed. For the oscillating floating body case, a combination idea is presented in which the motions of the FPSO are calculated by the potential theory in advance and computional fluid dynamics (CFD) tools are used to investigate the details of green water. A technique of dynamic mesh is introduced in a numerical wave tank to simulate the green water occurrence on the oscillating vessels in waves. Numerical results agree well with the corresponding experimental results regarding the wave heights on deck and green water impact loads; the two-dimensional fixed FPSO model case conducted by Greco (2001), and the three-dimensional oscillating vessel cases by Buchner (2002), respectively. The research presented here indicates that the present numerical scheme and method can be used to actually simulate the phenomenon of green water on deck, and to predict and analyze the impact forces on floating structures due to green water. This can be of great significance in further guiding ship design and optimization, especially in the strength design of ship bows.

scholarly journals BIPLANAR IMAGING WITH TRIDIMENSIONAL CAPABILITIES: APPLICABILITY OF THIS NEW EXAMINATION TO SPINAL DEFORMITIES

2020 ◽  
Vol 19 (1) ◽  
pp. 67-70
Author(s):  
RAPHAEL DE REZENDE PRATALI ◽  
MURILO TAVARES DAHER ◽  
ROBERT MEVES
Keyword(s):  
Spinal Deformity ◽  
Imaging System ◽  
Adult Spinal Deformity ◽  
Three Dimensional ◽  
Entire Body ◽  
Spinal Deformities ◽  
Compensatory Mechanisms ◽  
Level Of Evidence ◽  
The Individual ◽  
Bone Structures

ABSTRACT This study presents details about the applicability of the new image acquisition system, called the biplanar imaging system, with three-dimensional capabilities (EOS®) to the treatment of spinal deformities. This system allows radiographic acquisition of the entire body, with a great reduction in the dose of radiation absorbed by the patient and three-dimensional (3D) stereoradiographic image reconstruction of bone structures, including the spine. In the case of adolescent idiopathic scoliosis, the analysis of the spinal deformity with 3D reconstruction allows better understanding of the deformity and surgical planning. In the case of adult spinal deformity, full-body analysis allows an evaluation of the spinopelvic deformity, including loss of sagittal alignment, in addition to an evaluation of compensatory mechanisms recruited by the individual in an attempt to maintain the sagittal balance. Level of evidence III; Descriptive Review.

scholarly journals Three-Dimensional Imaging of the High Sea-State Wavefield Encompassing Ship Slamming Events

2009 ◽  
pp. 100731080323068
Author(s):  
A. Brandt ◽  
J. L. Mann ◽  
S. E. Rennie ◽  
A. P. Herzog ◽  
T. B. Criss
Keyword(s):  
Three Dimensional ◽  
Sea State ◽  
Three Dimensional Imaging ◽  
Ship Slamming

Non-Linear Initialization in Three-Dimensional High Order Spectra Deterministic Sea State Modeling

2010 ◽  
Author(s):  
Yves L. Perignon ◽  
Felicien Bonnefoy ◽  
Pierre Ferrant ◽  
Guillaume Ducrozet
Keyword(s):  
Wave Field ◽  
Initial Conditions ◽  
Wave Train ◽  
Three Dimensional ◽  
Energy Calculation ◽  
Sea State ◽  
Density Spectrum ◽  
Linear Interaction ◽  
Non Linear ◽  
Linear Effects

This study deals with the initialization of three-dimensional wave field computations. We carry out such simulations with an HOS model developed at LMF-ECN since 2002 and based on the work of West et al. (1987) and Dommermuth & Yue (1987). In such models, initial conditions for three-dimensional realistic sea state computation are obtained by linearly distributing energy density spectrum. This however implies a relaxation of the non-linear effects as proposed by Dommermuth (2000) for bi-dimensional monochromatic wave train and Tanaka (2001), over several tenths of wave periods. The present work tests those former initialization methods and exposes an alternative initialization based on a non-linear three-dimensional approach. Non-linear interaction processes are both accounted in the spectra of elevation and potential of velocity, in accordance with the formulation of Dalzell (1999) at second order in wave steepness. Non-linear energy calculation is then addressed and the efficiency of the methods as well as their possible impact on properties and statistics of the wave field are investigated.

A Non-Linear Potential Model to Predict Large-Amplitudes-Motions: Application to the SEAREV Wave Energy Converter

2007 ◽  
Author(s):  
J.-C. Gilloteaux ◽  
A. Babarit ◽  
G. Ducrozet ◽  
M. Durand ◽  
A. H. Cle´ment
Keyword(s):  
Wave Field ◽  
Spectral Method ◽  
Three Dimensional ◽  
Floating Body ◽  
Linear Potential ◽  
Sea State ◽  
Flow Surface ◽  
Non Linear ◽  
Large Amplitude Motions ◽  
Six Degree Of Freedom

A time-domain non-linear potential-flow model has been developed in order to predict the large-amplitude motions of the SEAREV device in a prescribed or arbitrary sea state. The floating body three-dimensional, undergoing six degree-of-freedom motions. The fluid is considered homogeneous, incompressible, inviscid and with an irrotational flow. Surface tension is not taken into account and the depth is considered infinite. The incident wave field is given by a higher-order spectral method. This spectral method permits the simulation of very steep wave field.

Sensitivity Study of Calculated Jacket Fatigue Damage due to Long Term Distribution of Wave Heights

2017 ◽  
Author(s):  
Hege Halseth Bang ◽  
Siri Hoel Smedsrud ◽  
Øistein Hagen ◽  
Terje Nybø
Keyword(s):  
Fatigue Damage ◽  
Wave Height ◽  
Time Domain ◽  
Height Distribution ◽  
Scatter Diagram ◽  
Sea State ◽  
Jacket Structures ◽  
Wave Heights ◽  
The Individual

Marine structures like jacket structures are often highly utilized structures operating in an environment dominated by dynamic loading. The fatigue limit state is of main concern and is to a large extent governing the structural dimensions and the amount of resources utilized in inspection and maintenance of members and joints. There is a considerable degree of uncertainty related to the parameters determining the fatigue damage. The models applied, both for describing the fatigue driving mechanisms e.g. the wave-description and load modeling and the deterioration mechanism, are always compromises between the ability to accurately describe the nature and computationally efficiency. The main focus in this paper is to show how sensitive the calculated fatigue damage of a jacket is to different models for the short term variability of wave heights. To obtain consistent basis for comparison a deterministic fatigue analysis is considered and a potential structural dynamic amplification is not included in the comparison study. Sensitivity to selection of wave spectra will not be addressed. In a deterministic approach the long term distribution of individual wave heights is used to calculate the stress ranges occurring in the joints and butt welds. Typically, the long term variability of sea state conditions is given by a scatter diagram of significant wave height (Hs) and the peak period (Tp). When converting the scatter diagram of sea states to the long term distribution of wave heights, it is common to assume that the individual waves in the sea states are Rayleigh distributed. Later developments indicate that a Forristall distribution may be a more accurate assumption. The following cases have been considered: 1. Assuming that the individual waves in each sea state are Rayleigh distributed. 2. Assuming that the individual waves in each sea state follows a Forristall distribution. 3. Calculating the long term wave height distribution from time domain simulations. In the third method, second order wave theory was used to simulate all sea states in the Hs/Tp scatter diagram. I.e. extensive time domain simulations were carried out to cover the complete scatter diagram of possible sea states. The study is performed for an 8-legged jacket. The analyses are performed for a typical North Sea wave environment for water depth about 110 m. The objective of this study is to investigate the robustness in the current design practice for jacket structures where the individual waves in the sea states are Rayleigh distributed. The paper documents the calculated fatigue lives for main joints along the height of the jacket for the three wave height distributions. Further, the paper gives advice on application of wave distribution models for design of new structures and reassessment of existing structures.

Semi-automated methods for 3-D reconstruction of macromolecular complexes

1995 ◽  
Vol 53 ◽  
pp. 42-43
Author(s):  
B. Carragher ◽  
M. Whittaker
Keyword(s):  
Three Dimensional ◽  
Time Saving ◽  
Macromolecular Complexes ◽  
Symmetry Properties ◽  
Dimensional Reconstruction ◽  
Experienced Operator ◽  
Projection Images ◽  
The Individual ◽  
Natural Symmetry

Techniques for three-dimensional reconstruction of macromolecular complexes from electron micrographs have been successfully used for many years. These include methods which take advantage of the natural symmetry properties of the structure (for example helical or icosahedral) as well as those that use single axis or other tilting geometries to reconstruct from a set of projection images. These techniques have traditionally relied on a very experienced operator to manually perform the often numerous and time consuming steps required to obtain the final reconstruction. While the guidance and oversight of an experienced and critical operator will always be an essential component of these techniques, recent advances in computer technology, microprocessor controlled microscopes and the availability of high quality CCD cameras have provided the means to automate many of the individual steps.During the acquisition of data automation provides benefits not only in terms of convenience and time saving but also in circumstances where manual procedures limit the quality of the final reconstruction.

Phonetic iconicity in the evaluative morphology of a sample of Indo-European, Niger-Congo and Austronesian languages

2010 ◽  
Vol 3 (2) ◽  
pp. 156-180 ◽  
Author(s):  
Renáta Gregová ◽  
Lívia Körtvélyessy ◽  
Július Zimmermann
Keyword(s):  
Three Dimensional ◽  
Sound Symbolism ◽  
Three Dimensional Model ◽  
Austronesian Languages ◽  
Place Of Articulation ◽  
European Languages ◽  
Phonetic Symbolism ◽  
The Individual ◽  
Core Vocabulary

Universals Archive (Universal #1926) indicates a universal tendency for sound symbolism in reference to the expression of diminutives and augmentatives. The research ( Štekauer et al. 2009 ) carried out on European languages has not proved the tendency at all. Therefore, our research was extended to cover three language families – Indo-European, Niger-Congo and Austronesian. A three-step analysis examining different aspects of phonetic symbolism was carried out on a core vocabulary of 35 lexical items. A research sample was selected out of 60 languages. The evaluative markers were analyzed according to both phonetic classification of vowels and consonants and Ultan's and Niewenhuis' conclusions on the dominance of palatal and post-alveolar consonants in diminutive markers. Finally, the data obtained in our sample languages was evaluated by means of a three-dimensional model illustrating the place of articulation of the individual segments.

scholarly journals Estimating intrafraction tumor motion during fiducial-based liver stereotactic radiotherapy via an iterative closest point (ICP) algorithm

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Wu-zhou Li ◽  
Zhi-wen Liang ◽  
Yi Cao ◽  
Ting-ting Cao ◽  
Hong Quan ◽  
...  
Keyword(s):  
Stereotactic Radiotherapy ◽  
Imaging System ◽  
Liver Tumors ◽  
Three Dimensional ◽  
Rigid Motion ◽  
Iterative Closest Point ◽  
Tumor Motion ◽  
Tracking Accuracy ◽  
Icp Algorithm ◽  
Anterior Posterior

Abstract Background Tumor motion may compromise the accuracy of liver stereotactic radiotherapy. In order to carry out a precise planning, estimating liver tumor motion during radiotherapy has received a lot of attention. Previous approach may have difficult to deal with image data corrupted by noise. The iterative closest point (ICP) algorithm is widely used for estimating the rigid registration of three-dimensional point sets when these data were dense or corrupted. In the light of this, our study estimated the three-dimensional (3D) rigid motion of liver tumors during stereotactic liver radiotherapy using reconstructed 3D coordinates of fiducials based on the ICP algorithm. Methods Four hundred ninety-five pairs of orthogonal kilovoltage (KV) images from the CyberKnife stereo imaging system for 12 patients were used in this study. For each pair of images, the 3D coordinates of fiducial markers inside the liver were calculated via geometric derivations. The 3D coordinates were used to calculate the real-time translational and rotational motion of liver tumors around three axes via an ICP algorithm. The residual error was also investigated both with and without rotational correction. Results The translational shifts of liver tumors in left-right (LR), anterior-posterior (AP),and superior-inferior (SI) directions were 2.92 ± 1.98 mm, 5.54 ± 3.12 mm, and 16.22 ± 5.86 mm, respectively; the rotational angles in left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were 3.95° ± 3.08°, 4.93° ± 2.90°, and 4.09° ± 1.99°, respectively. Rotational correction decreased 3D fiducial displacement from 1.19 ± 0.35 mm to 0.65 ± 0.24 mm (P<0.001). Conclusions The maximum translational movement occurred in the SI direction. Rotational correction decreased fiducial displacements and increased tumor tracking accuracy.

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