Analysis of Motions of a Semisubmersible in Sea Waves

1982 ◽  
Vol 104 (1) ◽  
pp. 29-38
Author(s):  
F. Z. Sun
Keyword(s):  
Transfer Functions ◽  
Three Dimensional ◽  
Theoretical Data ◽  
Statistical Characteristics ◽  
Sea Waves ◽  
Regular Waves ◽  
Short Term ◽  
Equivalent Wave ◽  
Processing Techniques

The forces acting on a three-dimensional cylinder with arbitrary symmetrical cross section are derived taking into account viscous effect and applying linear-processing techniques. Then general expressions for the hydrodynamic forces, motion equation and its solution for a semisubmersible platform in regular waves are obtained. Based on linear theory of statistical analysis, it is proposed to employ the concept of “equivalent wave height” for the calculation of transfer functions with which both the short-term and long-term distribution and statistical characteristics of the motion of a semisubmersible may be estimated. A computer program has been developed. Comparison between model experimental and theoretical data has shown satisfactory agreement.

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.

Comparison of Spar and Semisubmersible Floater Concepts of Offshore Wind Turbines Using Long-Term Analysis

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Hasan Bagbanci ◽  
D. Karmakar ◽  
C. Guedes Soares
Keyword(s):  
Wind Turbine ◽  
Wind Turbines ◽  
Transfer Functions ◽  
Probability Distributions ◽  
Offshore Wind ◽  
Short Term ◽  
Offshore Wind Turbines ◽  
Floating Wind Turbine ◽  
Offshore Floating Wind Turbine

The long-term probability distributions of a spar-type and a semisubmersible-type offshore floating wind turbine response are calculated for surge, heave, and pitch motions along with the side-to-side, fore–aft, and yaw tower base bending moments. The transfer functions for surge, heave, and pitch motions for both spar-type and semisubmersible-type floaters are obtained using the fast code and the results are also compared with the results obtained in an experimental study. The long-term predictions of the most probable maximum values of motion amplitudes are used for design purposes, so as to guarantee the safety of the floating wind turbines against overturning in high waves and wind speed. The long-term distribution is carried out using North Atlantic wave data and the short-term floating wind turbine responses are represented using Rayleigh distributions. The transfer functions are used in the procedure to calculate the variances of the short-term responses. The results obtained for both spar-type and semisubmersible-type offshore floating wind turbine are compared, and the study will be helpful in the assessments of the long-term availability and economic performance of the spar-type and semisubmersible-type offshore floating wind turbine.

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.

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.

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.

scholarly journals Multimodal Sensor Motion Intention Recognition Based on Three-Dimensional Convolutional Neural Network Algorithm

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Mofei Wen ◽  
Yuwei Wang
Keyword(s):  
Neural Network ◽  
Convolutional Neural Network ◽  
Three Dimensional ◽  
Short Term ◽  
Spatiotemporal Features ◽  
Emg Signal ◽  
Intention Recognition ◽  
Wide Range ◽  
Motion Intention

With the development of microelectronic technology and computer systems, the research of motion intention recognition based on multimodal sensors has attracted the attention of the academic community. Deep learning and other nonlinear neural network models have a wide range of applications in big data sets. We propose a motion intention recognition algorithm based on multimodal long-term and short-term spatiotemporal feature fusion. We divide the target data into multiple segments and use a three-dimensional convolutional neural network to extract the short-term spatiotemporal features. The three types of features of the same segment are fused together and input into the LSTM network for time-series modeling to further fuse the features to obtain multimodal long-term spatiotemporal features with higher discrimination. According to the lower limb movement pattern recognition model, the minimum number of muscles and EMG signal characteristics required to accurately recognize the movement state of the lower limbs are determined. This minimizes the redundant calculation cost of the model and ensures the real-time output of the system results.

Influence of Whipping on Long-term Vertical Bending Moment

2004 ◽  
Vol 48 (04) ◽  
pp. 261-272
Author(s):  
Gro Sagli Baarholm ◽  
Jørgen Juncher Jensen
Keyword(s):  
Nonlinear Response ◽  
Extreme Values ◽  
Bending Moment ◽  
Sea Waves ◽  
Short Term ◽  
Strip Theory ◽  
Long Time ◽  
Wave Induced ◽  
Vertical Bending Moment

This paper is concerned with estimating the response value corresponding to a long return period, say 20 years. Time domain simulation is required to obtain the nonlinear response, and long time series are required to limit the statistical uncertainty in the simulations. It is crucial to introduce ways to improve the efficiency in the calculation. A method to determine the long-term extremes by considering only a few short-term sea states is applied. Long-term extreme values are estimated using a set of sea states that have a certain probability of occurrence, known as the contour line approach. Effect of whipping is included by assuming that the whipping and wave-induced responses are independent, but the effect of correlation of the long-term extreme value is also studied. Numerical calculations are performed using a nonlinear, hydroelastic strip theory as suggested by Xia et al (1998). Results are presented for the S-175 containership (ITTC 1983) in head sea waves. The analysis shows that whipping increases the vertical bending moment and that the correlation is significant.

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.

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