An Approach to the Estimation of Structural Design Loads of Turret Moored FPSO Tankers

2003 ◽  
Author(s):  
Huilong Ren ◽  
Chang Doo Jang
Keyword(s):  
Structural Design ◽  
Three Dimensional ◽  
Wave Loads ◽  
Short Term ◽  
Efficient Calculation ◽  
Restoring Forces ◽  
Design Loads ◽  
The Given ◽  
Equations Of Motions

A practical approach to determine the structural design loads of turret moored FPSO (Floating Production Storage and Offloading) tankers is suggested in this paper. The linearized restoring forces acting on the ship hull by the mooring system are calculated according to the catenary theory. The effect of the restoring forces is included in the equations of motions of the ship in the form of linear stiffness coefficients. The hydrodynamic coefficients are calculated by the three-dimensional potential flow theory. The equations of motions are solved in frequency domain, and the motions and wave loads responses can be obtained. Then the short-term and long-term analyses are carried out for the wave loads of this kind of ship. With a 250m turret moored FPSO tanker as an example, according to the given environmental sea states data, headings, exceeding probability for the FPSO tanker, the structural design loads are calculated and compared with those obtained from rules for traditional tankers with the same dimensions. By the present approach, it is possible to perform a practical and efficient calculation of structural design loads of actual turret moored FPSO tankers.

Numerical Analysis of Ship Wave Loads and Structure Strengthen Analysis on a Wind Power Installation Ship

2011 ◽  
Vol 90-93 ◽  
pp. 2521-2527
Author(s):  
Gang Qiang Li ◽  
Yan Yan Zhao ◽  
Yong He Xie
Keyword(s):  
Wind Power ◽  
Structural Design ◽  
Three Dimensional ◽  
Load Condition ◽  
Wave Loads ◽  
Element Simulation ◽  
Wind Power Installation ◽  
Wave Induced ◽  
Term Response

In a typical load condition of wind power equipment Installation ship, using the three-dimensional potential flow theory to prediction the long-term response of wave induced loads. then using the main load control parameters as a basis for the design wave selection, then application of DNV's SESTRA program make the wave-induced directly to the structure to finite element simulation. The results show that the hull structural design can meet the requirements.

The Research of Statistic Prediction for Wave Loads Based on Three Dimensional Method

2013 ◽  
Author(s):  
Yihan Zhang ◽  
Huilong Ren ◽  
Hui Li ◽  
Xiaoyu Li
Keyword(s):  
Structural Strength ◽  
Wave Spectrum ◽  
Three Dimensional ◽  
Frequency Interval ◽  
Wave Loads ◽  
Short Term ◽  
Empirical Formulas ◽  
Strength Assessment ◽  
Term Prediction

The exact prediction of wave loads for ship or other marine structure is the key to its design and the assessment of structural strength, reliability and security. The short-term and long-term prediction of wave loads are always used in direct calculation for structural strength, fatigue strength assessment and so on based on spectral analysis method. In this paper, the numerical calculation method for statistic prediction is discussed firstly, including the Weibull distribution fitted method and the stack method. Further more, it is necessary to find a quick solution in order to improve the efficiency to compute the nonlinear equation in the second method. Then, some main factors that may influence the long-term or short-term prediction are discussed, such as wave spectrum, wave scatter diagram, incident wave angle interval and frequency interval. Finally, the wave loads prediction for a series of typical bulk carriers and oil tankers are calculated by the uniform predict method discussed above base on three dimensional wave loads calculation theory. The results showed that the method used in this paper can predict the statistic value of wave loads induced by irregular incident waves conveniently and efficiently. A rule to choose a series of uniform factors is confirmed for statistic prediction and some empirical formulas for long-term value of wave bending moment are concluded which are very useful in marine engineering.

The Simplified Method for the Wave Loads Statistical Characteristics Estimation in Stationary Confused Seas

2004 ◽  
Author(s):  
I. F. Davydov ◽  
G. V. Egorov ◽  
V. V. Kozlyakov
Keyword(s):  
Three Dimensional ◽  
Correlation Coefficients ◽  
Statistical Characteristics ◽  
Wave Loads ◽  
Short Term ◽  
Shape Stability ◽  
Response Characteristics ◽  
Combined Stresses ◽  
Definition Of

Practically relevant procedures of construction of the short-term and long-term distributions of wave loads and combined stresses at two- and three-dimensional waves is based on the rather cumbersome schemes of definition of the standards “σyi”, effective periods “Tyie” and correlation coefficients “ryiyi” of wave loads “yi”. These calculations can be made more visible and essentially simplified on the basis of the shape stability of the doubly-normalized amplitude-frequency (AFC) and mutual-frequency response characteristics (MFRC). All specific features of these characteristics are determined by their maximum values and frequencies of maxima. In the report the convenient formulae for estimation of σyi, Tyie and ryiyj are derived, and graphs of functions, determining them, for different wave loads are plotted. These relations allow to reveal major influencing factors and use them for construction of the short-term and long-term spectra of wave loads and stresses for full transport ships (CB > 0.75), including FPSO ships, for which non-linear and dynamic effects are expressed rather weakly.

scholarly journals Remember like humans

2017 ◽  
Vol 14 (1) ◽  
pp. 172988141769231 ◽  
Author(s):  
Ning An ◽  
Shi-Ying Sun ◽  
Xiao-Guang Zhao ◽  
Zeng-Guang Hou
Keyword(s):  
Short Term Memory ◽  
Three Dimensional ◽  
Sensory Memory ◽  
Long Term Memory ◽  
Observation Model ◽  
Two Dimensional ◽  
Short Term ◽  
Term Memory ◽  
Memory Register

Visual tracking is a challenging computer vision task due to the significant observation changes of the target. By contrast, the tracking task is relatively easy for humans. In this article, we propose a tracker inspired by the cognitive psychological memory mechanism, which decomposes the tracking task into sensory memory register, short-term memory tracker, and long-term memory tracker like humans. The sensory memory register captures information with three-dimensional perception; the short-term memory tracker builds the highly plastic observation model via memory rehearsal; the long-term memory tracker builds the highly stable observation model via memory encoding and retrieval. With the cooperative models, the tracker can easily handle various tracking scenarios. In addition, an appearance-shape learning method is proposed to update the two-dimensional appearance model and three-dimensional shape model appropriately. Extensive experimental results on a large-scale benchmark data set demonstrate that the proposed method outperforms the state-of-the-art two-dimensional and three-dimensional trackers in terms of efficiency, accuracy, and robustness.

scholarly journals A survey of short-term and long-term stability of tube parameters in a mammography unit

2014 ◽  
Vol 29 (4) ◽  
pp. 321-325
Author(s):  
Jovica Praskalo ◽  
Jasna Davidovic ◽  
Biljana Kocic ◽  
Monika Zivkovic ◽  
Svetlana Pejovic
Keyword(s):  
Screening Program ◽  
Short Term ◽  
X Ray ◽  
Term Stability ◽  
Long Term Stability ◽  
Mammography Screening Program ◽  
The Republic ◽  
Set Up ◽  
The Given

In order to set up a successful mammography screening program in the Republic of Srpska, a Siemens Mammomat 1000 X-ray machine was selected for analysis as the said mammography system is widely used in clinical practice. The variations in tube parameters (specific air kerma, high-voltage accuracy and reproducibility, linearity between exposure and dose exposure time) were monitored over a five-year period, from 2008 to 2012. In addition, due to observed daily fluctuations for chosen parameters, a series of measurements were performed three times a day within a single-month period (mainly October 2012). The goal of such an experimental set up is to assess short-term and long-term stability of tube parameters in the given mammography unit and to make a comparison between them. The present paper shows how an early detection of significant parameter fluctuations can help eliminate irregularities and optimize the performance of mammography systems.

Recall of Familiar Objects and Projected Color Photographs of Objects by Mentally Retarded Individuals of Comparable Mental Age

1976 ◽  
Vol 42 (1) ◽  
pp. 139-145
Author(s):  
Andrew L. Shotick ◽  
A. Bartow Ray ◽  
C. Lewis Addison
Keyword(s):  
Memory Span ◽  
Three Dimensional ◽  
Mentally Retarded ◽  
Short Term ◽  
Delayed Recall ◽  
Mental Age ◽  
Mentally Retarded Children ◽  
Cue Availability ◽  
Familiar Objects

The effects of cue-availability on short-term and long-term recall of 40 mentally retarded children were investigated. Subjects were chosen on the basis of comparable mental age (approximately 90 mo.) and randomly assigned to either an objects (high cues) group or slides (low cues) group. 52 familiar objects served as stimuli for the objects group and projected color photographs of the objects were presented to the slides group. In the short-term recall session the subjects were shown stimuli grouped into eight trials and asked to recall the names of the stimuli in each trial ten seconds after presentation. Delayed recall was obtained 48 hr. later in a free recall session. The objects group scored significantly higher than the slides group on memory span ( p < .01), short-term recall ( p < .001), and delayed recall ( p < .025). The facilitation of recall achieved by using three-dimensional stimuli was clearly demonstrated, and the relative degree of facilitation was comparable for both short- and long-term recall.

scholarly journals Wuhan MST radar: Technical features and Validation of wind observations

2020 ◽  
Author(s):  
Lei Qiao ◽  
Gang Chen ◽  
Shaodong Zhang ◽  
Qi Yao ◽  
Wanlin Gong ◽  
...  
Keyword(s):  
Doppler Radar ◽  
Three Dimensional ◽  
Data Sets ◽  
Wind Fields ◽  
Short Term ◽  
Peak Output Power ◽  
Mst Radar ◽  
Flexible Architecture ◽  
Technical Features

Abstract. The Wuhan MST radar is a 53.8 MHz monostatic Doppler radar, located in Chongyang, Hubei Province, China, which has the capability to observe the dynamics of the mesosphere-stratosphere-troposphere region in the subtropical latitudes. The system is composed of 576 Yagi antennas with square distribution, and the maximum peak power is 192 kW. The Wuhan MST radar is efficient and cheap, which applies simplifier and more flexible architecture. It includes 24 big TR modules, and the row/column data port of each big TR module connects 24 small TR modules via the corresponding row/column feeding network. Each antenna is driven by a small TR module with peak output power of 300 W. The arrangement of the antenna field, the functions of the timing signals, the structure of the TR modules, and the clutter suppression procedure are described in detail in this manuscript. We compared the MST radar observation results with other instruments and related models in the whole MST region for validation. Firstly, we made a comparison of the Wuhan MST radar observed horizontal winds in the troposphere and low stratosphere with the radiosonde in the short term, as well as the ERA-interim data sets (2016 and 2017) in the long term. Then, we made a comparison of the observed horizontal winds in the mesosphere with the meteor radar and the HWM-07 model in the same way. In general, good agreements can be obtained, and it indicates that the Wuhan MST is an effective tool to measure the three-dimensional wind fields of the MST region in the short-term and long-term.

Persistence of spatial meanings in the conceptualization of causality: at, by, with and about in emotion constructions

2018 ◽  
Vol 54 (2) ◽  
pp. 223-254
Author(s):  
Eunmi Kim
Keyword(s):  
American English ◽  
Three Dimensional ◽  
Corpus Analysis ◽  
Strong Tendency ◽  
Short Term ◽  
Spatial Dimensions ◽  
Spatial Source

Abstract Prepositions encode various causal forces when expressing emotion causality in emotion constructions. This study investigates two pairs of prepositions, the zerodimensional at and by, and the two- or three-dimensional with and about, which show contrasting collocation patterns in emotion constructions. Through a corpus analysis of the Corpus of Contemporary American English, this study claims that there is a strong tendency that zero-dimensional prepositions are used with short-term emotions, whereas two- or three-dimensional prepositions frequently occur with long-term emotions. This study argues that the constraints of distributions of prepositions with emotive adjectives can be accounted for by features of their spatial source meanings in early usages. In the framework of grammaticalization, the constraints of collocation patterns of two pairs of prepositions with emotive adjectives show the phenomenon with respect to the “persistence” of Hopper (1991) in which traces of the source lexemes are retained in the constraints of their distributions. This study is significant in that it suggests a typology of causality based on spatial dimensions of prepositions.

scholarly journals The Triad of Risk-Related Behaviors (TriRB): A Three-Dimensional Model of Cyber Risk Taking

2018 ◽  
Vol 60 (8) ◽  
pp. 1163-1178 ◽  
Author(s):  
Noam Ben-Asher ◽  
Joachim Meyer
Keyword(s):  
Risk Taking ◽  
Three Dimensional ◽  
Three Dimensional Model ◽  
Short Term ◽  
Targeted Interventions ◽  
Protective Actions ◽  
Alerting System ◽  
Tactical Decisions ◽  
Cyber Risk

Objective: We identify three risk-related behaviors in coping with cyber threats—the exposure to risk a person chooses, use of security features, and responses to security indications. The combinations of behaviors that users choose determine how well they cope with threats and the severity of adverse events they experience. Background: End users’ coping with risks is a major factor in cybersecurity. This behavior results from a combination of risk-related behaviors rather than from a single risk-taking tendency. Method: In two experiments, participants played a Tetris-like game, attempting to maximize their gains, while exogenous occasional attacks could diminish earnings. An alerting system provided indications about possible attacks, and participants could take protective actions to limit the losses from attacks. Results: Variables such as the costs of protective actions, reliability of the alerting system, and attack severity affected the three behaviors differently. Also, users dynamically adjusted each of the three risk-related behaviors after gaining experience with the system. Conclusion: The results demonstrate that users’ risk taking is the complex combination of three behaviors rather than the expression of a general risk-taking tendency. The use of security features, exposure to risk, and responses to security indications reflect long-term strategy, short-term tactical decisions, and immediate maneuvering in coping with risks in dynamic environments. Application: The results have implications for the analysis of cybersecurity-related decisions and actions as well as for the evaluation and design of systems and targeted interventions in other domains.

The Effect of Soil Load on Fracture Behaviour of Three-Layer Polymer Pipe for Non-Pressurised Applications

2014 ◽  
Vol 627 ◽  
pp. 197-200 ◽  
Author(s):  
Martin Ševčík ◽  
Florian Arbeiter ◽  
Pavel Hutař ◽  
Gerald Pinter ◽  
Luboš Náhlík
Keyword(s):  
Pipe Wall ◽  
Fracture Behaviour ◽  
Three Dimensional ◽  
Protective Layer ◽  
External Pressure ◽  
Residual Lifetime ◽  
Short Term ◽  
Material Interface ◽  
Soil Load

Fracture behaviour of a three-layer polymer pipe subjected to nonhomogenous distribution of external pressure induced by soil embedding is studied in this paper. Both long term and additional short term loading is considered. Such loading induces tensile stresses in the inner pipe wall which can lead to crack initiation and further slow crack propagation. The material interface between a protective layer and the base pipe can contribute to crack deceleration and can prolong the residual lifetime of the pipe. The paper presents three-dimensional numerical analysis of a commercial three-layer pipe containing an internal semi-elliptical crack. The effect of soil load on the fracture behaviour of the cracked pipe is quantified and discussed.

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